Computer Networking & Hardware Concepts.pdf

Tools for
Teaching Computer
Networking and
Hardware Concepts
NurulI.Sarkar,AucklandUniversityofTechnology,NewZealand
Hershey • London • Melbourne • Singapore
Information Science Publishing

Acquisitions Editor: Michelle Potter
Development Editor: Kristin Roth
Senior Managing Editor: Amanda Appicello
Managing Editor: Jennifer Neidig
Copy Editor: Beth Arnesen
Typesetter: Jennifer Neidig
Cover Design: Lisa Tosheff
Printed at: Yurchak Printing Inc.
Published in the United States of America by
Information Science Publishing (an imprint of Idea Group Inc.)
701 E. Chocolate Avenue
Hershey PA 17033
Tel: 717-533-8845
Fax: 717-533-8661
E-mail: cust@idea-group.com
Web site: http://www.idea-group.com
and in the United Kingdom by
Information Science Publishing (an imprint of Idea Group Inc.)
3 Henrietta Street
Covent Garden
London WC2E 8LU
Tel: 44 20 7240 0856
Fax: 44 20 7379 0609
Web site: http://www.eurospanonline.com
Copyright © 2006 by Idea Group Inc. All rights reserved. No part of this book may be
reproduced, stored or distributed in any form or by any means, electronic or mechanical,
including photocopying, without written permission from the publisher.
Product or company names used in this book are for identification purposes only.
Inclusion of the names of the products or companies does not indicate a claim of
ownership by IGI of the trademark or registered trademark.
Library of Congress Cataloging-in-Publication Data
Tools for teaching computer networking and hardware concepts / Nurul Sarkar, editor.
p. cm.
Summary: "This book offers concepts of the teaching and learning of computer networking
and hardwar eby offering undamental theoretical concepts illustrated with the use of
interactive practical exercises"--Provided by publisher.
Includes bibliographical references and index.
ISBN 1-59140-735-4 (h/c) -- ISBN 1-59140-736-2 (s/c) -- ISBN 1-59140-737-0 (ebook)
1. Computer networks--Study and teaching. 2. Computer input-output equipment--Study
and teaching. I. Sarkar, Nurul.
TK5105.5.T66 2006
004.6071--dc22
2005027411
British Cataloguing in Publication Data
A Cataloguing in Publication record for this book is available from the British Library.
All work contributed to this book is new, previously-unpublished material. The views
expressed in this book are those of the authors, but not necessarily of the publisher.

Dedication
To my wife, Laila A. Sarkar

Tools for Teaching
Computer Networking
and Hardware Concepts
Table of Contents
Foreword ........................................................................................................ viii
Preface .............................................................................................................. ix
Section I: Introduction
Chapter I. Introduction to Computer Networking and Hardware
Concepts ........................................................................................................... 1
Nurul I. Sarkar, Auckland University of Technology, New Zealand
Section II: Teaching and Learning Computer Networking
Chapter II. WebLan-Designer: A Web-Based Tool to Enhance
Teaching and Learning Wired and Wireless LAN Design ..................... 21
Krassie Petrova, Auckland University of Technology, New Zealand
Chapter III. INetwork: An Interactive Learning Tool for
Communication Networks ............................................................................ 39
K. Sandrasegaran, The University of Technology Sydney,
Australia
M. Trieu, The University of Technology Sydney, Australia

Chapter IV. Effectively Using a Network Simulation Tool to Enhance
Students’ Understanding of Computer Networking Concepts .............. 62
Cecil Goldstein, Queensland University of Technology, Australia
Karen Stark, Queensland University of Technology, Australia
Susanna Leisten, Queensland University of Technology, Australia
Alan Tickle, Queensland University of Technology, Australia
Chapter V. Teaching Protocols through Animation ................................. 86
Kenneth J. Turner, University of Stirling, UK
Chapter VI. Enhancing Student Understanding of Packet-Forwarding
Theories and Concepts with Low-Cost Laboratory Activities............. 101
Anthony P. Kadi, The University of Technology Sydney, Australia
Chapter VII. Ethereal: A Tool for Making the Abstract Protocol a
Concrete Reality .......................................................................................... 119
David Bremer, Otago Polytechnic, New Zealand
Section III: Wireless Networking and Information Security
Chapter VIII. Enhancing Teaching and Learning Wireless
Communication Networks Using Wireless Projects.............................. 135
Trevor Craig, Wollongong College Auckland, New Zealand
Chapter IX. Teaching and Learning Wi-Fi Networking
Fundamentals Using Limited Resources................................................. 154
Wilson Siringoringo, Auckland University of Technology,
New Zealand
Nurul I. Sarkar, Auckland University of Technology,
New Zealand
Chapter X. Information Security Risk Analysis: A Pedagogic
Model Based on a Teaching Hospital ...................................................... 179
Sanjay Goel, University at Albany, SUNY, and NYS Center for
Information Forensics and Assurance, USA
Damira Pon, University at Albany, SUNY, and NYS Center for
Information Forensics and Assurance, USA

Section IV: Teaching and Learning Computer Hardware
Chapter XI. A Practical Introduction to Input and Output Ports......... 201
David L. Tarnoff, East Tennessee State University, USA
Chapter XII. Enhancing Teaching and Learning Computer
Hardware Fundamentals Using PIC-Based Projects ............................. 229
New Zealand
Chapter XIII. Assistant Tool for Instructors Teaching Computer
Hardware with the PBL Theory ................................................................ 249
Maiga Chang, National Science and Technology Program for
e-Learning, Taiwan
Kun-Fa Cheng, Chih-Ping Senior High School, Taiwan
Alex Chang, Yuan-Ze University, Taiwan
Ming-Wei Chen, Chih-Ping Senior High School, Taiwan
Chapter XIV. A Simulator for High-Performance Processors ............. 267
John Morris, University of Auckland, New Zealand
Chapter XV. A Remotely Accessible Embedded Systems
Laboratory .................................................................................................... 284
Steve Murray, The University of Technology Sydney, Australia
Vladimir Lasky, The University of Technology Sydney, Australia
Chapter XVI. LOGIC-Minimiser: A Software Tool to Enhance
Teaching and Learning Minimization of Boolean Expressions............ 303
New Zealand
Khaleel I. Petrus, University of Southern Queensland, Australia
Section V: Data Communication Protocols and Learning Tools
Chapter XVII. A Practical Introduction to Serial Protocols ................. 319

Chapter XVIII. VMware as a Practical Learning Tool .......................... 338
Eduardo Correia, Christchurch Polytechnic Institute of
Technology, New Zealand
Ricky Watson, Christchurch Polytechnic Institute of Technology,
New Zealand
Appendix Section ......................................................................................... 355
Glossary......................................................................................................... 359
About the Authors ....................................................................................... 375
Index .............................................................................................................. 383

Foreword
viii
Computer networking and hardware concepts have come alive! With Tools for
Teaching Computer Networking and Hardware Concepts, the teaching and
learning of computer networking and hardware are made more interesting and
applied. Fundamental theoretical concepts are illustrated with the use of inter-
active practical exercises.
Each chapter presents learning objectives, figures and illustrations, real-world
examples as well as review questions, all of which provides teachers and stu-
dents with a resource to enhance learning.
This book is somewhat unique in that it brings together experiences from aca-
demics in countries such as Scotland, Taiwan, the United States of America,
Australia, and New Zealand. In sharing their use of online tools and flexible
learning practices, I hope that you will find this book a useful resource in the
teaching and learning of computer networking and hardware essentials.
Dr. Felix B. Tan
Professor of Information Systems and Head
School of Computer and Information Sciences
Auckland University of Technology
New Zealand

ix
Preface
Because of the high demand for networking and hardware skills in commerce
and in industry worldwide, computer networking and hardware courses are
becoming increasingly popular in universities, polytechnic institutions,
postsecondary colleges, and private training institutions around the globe. De-
spite this, it is often difficult to motivate students to learn computer networking
and hardware concepts because students appear to find the subject technical
and rather dry and boring. We strongly believe, as do many others, that students
learn computer networking and hardware fundamentals better and feel more
engaged with their courses if they are given interactive practical exercises that
illustrate theoretical concepts.
There are numerous textbooks on computer networking and hardware con-
cepts as well as publications, including journals and conference proceedings, in
computer education and Web-based learning. However, these publications have
very limited discussion on software and hardware tools that enhance teaching
and learning computer networking and hardware concepts. To address this need,
we have written Tools for Teaching Computer Networking and Hardware
Concepts, focusing on the development and use of innovative tools for teaching
and learning various aspects of computer networking and hardware concepts.
We believe the proposed book is unique and is a useful resource to both stu-
dents and teachers at university, polytechnic, postsecondary, and private train-
ing institutions. This book: (1) provides comprehensive coverage of tools and
techniques for teaching and learning computer networking and hardware con-
cepts at introductory and advanced levels; (2) can be used as a resource both
by students and by teachers in different teaching and learning contexts; (3)
offers both students and teachers an opportunity to benefit from the experience
of teachers and researchers in other countries in the areas of teaching and

x
learning computer networking and hardware; (4) represents a rich starting point
for researchers interested in developing innovative tools for teaching and learn-
ing computer networking and hardware concepts; and (5) raises the awareness
of the need to enhance face-to-face teaching through the use of online interac-
tive learning and flexible mode of delivery of papers. Although various hard-
ware and software tools, methods, and laboratory settings are discussed in the
text, an emphasis has been placed on the development and use of tools and
techniques in the classroom that enhance the teaching and learning of various
aspects of computer networking and hardware concepts.
Organization and Outline
The book is organized into five sections.
Section I: Introduction. Section I (Chapter I) provides a rationale and intro-
duction to the book. It provides an introduction to computer networking and
hardware concepts and highlights the use of software and hardware tools as an
aid to enhance teaching and learning computer networking and hardware fun-
damentals. It also outlines the remainder of this book.
Section II: Teaching and Learning Computer Networking. Section II con-
sists of six chapters (II through VII) and provides detailed coverage of the
software and hardware tools and lab activities designed to enhance teaching
and learning various aspects of computer networking. Chapter II describes the
development and use of an interactive software tool (named WebLan-Designer)
as an aid to enhance teaching and learning both wired and wireless LAN de-
sign. Chapter III describes INetwork, an interactive learning tool for communi-
cation networks. Chapter IV emphasizes the use of a network simulation tool in
large classes to enhance student understanding of computer networking con-
cepts effectively. Chapter V highlights the use of simulation and animation tools
in teaching communication protocols. Chapter VI describes a low-cost labora-
tory infrastructure for enhancing student understanding of packet-forwarding
concepts and theories. Chapter VII examines the use of the tool Ethereal in the
classroom for teaching TCP/IP protocols in a practical way.
Section III: Wireless Networking and Information Security. Section III
consists of three chapters (VIII through X) and provides detailed coverage of
the software and hardware tools, cases, and lab activities designed to enhance
teaching and learning various aspects of wireless networking concepts and in-
formation security risk analysis. Chapter VIII describes a series of wireless
projects for teaching and learning wireless communication networks. Chapter
IX focuses on teaching and learning Wi-Fi networking and propagation mea-
surements using limited resources. Chapter X highlights teaching and learning
information security risk analysis using a teaching hospital model.

xi
Section IV: Teaching and Learning Computer Hardware. Section IV con-
sists of six chapters (XI through XVI) and provides software and hardware
tools, including processor simulator and lab activities, to enhance teaching and
learning various aspects of computer hardware concepts. Chapter XI provides
a practical introduction to input and output ports. Chapter XII describes a set of
PIC-based practical laboratory exercises for teaching and learning computer
hardware concepts. Chapter XIII focuses on teaching computer hardware con-
cepts using PBL theory. Chapter XIV discusses the use of a processor simula-
tor in teaching computer architecture both at introductory and advanced levels.
Chapter XV describes a remotely accessible embedded systems laboratory for
teaching and learning computer hardware. Chapter XVI reports on the devel-
opment and use of a software tool (named LOGIC-Minimiser) for teaching and
learning minimization of Boolean expressions.
Section V: Data Communication Protocols and Learning Tools. Section
V consists of two chapters (XVII and XVIII) and provides detailed coverage
of learning tools and techniques designed to enhance teaching and learning
various aspects of data communication protocols. Chapter XVII provides a
practical introduction to serial protocols for data communications, and Chapter
XVIII describes the use of VMware in teaching and learning contexts.
Target Audience for This Book
Teachers, tutors, and students in schools of business, information technology,
engineering, computer and information sciences, and other related disciplines
will benefit from the use of this book. Moreover, the book will provide insights
and support for both instructors and students involved in training courses in
networking and hardware fundamentals at various vocational training institu-
tions.
How to Use This Book
The innovative open source software and hardware tools and new ideas pre-
sented in the book enable the book to be used by both teachers and students as
a resource to enhance teaching and learning computer networking and hard-
ware concepts in a variety of teaching and learning contexts. Students can also
benefit from the learning aids, such as learning objectives, summary, key terms
and definitions, figures and illustrations, examples and review questions, and
references that are provided in each chapter.

xii
Learning Aids
The book provides the following learning aids:
• Learning Objectives: Each chapter begins with a list of learning objec-
tives that previews the chapter’s key ideas and highlights the key con-
cepts and skills that students can achieve by completing the chapter. Learn-
ing objectives also assist teachers in preparing a lesson plan for a particu-
lar topic.
• Figures and Illustrations: The key concepts in both computer network-
ing and hardware are illustrated using diagrams and screenshots through-
out the book. These illustrations help students to develop a better under-
standing of the key concepts in computer hardware and networking.
• Examples: Various real-world examples have been introduced in the chap-
ters to explain the use of tools and techniques learned from the text.
• Summary: Each chapter provides a brief summary of the contents pre-
sented in the chapter. This helps students to preview key ideas in the chap-
ter before moving on to the next chapter.
• Key Terms and Definitions: Each chapter provides a set of key terms
and their definitions. Both students and teachers can benefit by using the
listing of key terms and definitions to recall key networking and hardware
concepts before and after reading the chapter.
• Review Questions: Each chapter provides a set of end-of-chapter re-
view questions linked to the learning objectives, allowing the teachers to
evaluate their teaching effectiveness. Answers to most of the review ques-
tions can be found in the relevant chapter(s), and hence students are en-
couraged to revisit the relevant sections of the chapter in order to find the
answers. By answering the review questions, students can develop a deeper
understanding of many key networking and hardware concepts and tools.
Teachers and instructors can use the review questions to test their teach-
ing effectiveness and to initiate class discussion.

This book contains contributions from many leading professors and researchers
from around the world in the field of computer networking and hardware con-
cepts. One of the most challenging tasks for the editor was to integrate the
individual submissions from the 26 authors involved (including the editor) into a
coherent book. Toward this end, to enhance the readability of the book and to
make it a useful resource, the editor has introduced some additional material,
including learning objectives, an end-of-chapter summary, and review ques-
tions. The editor maintained close liaison with the contributing authors through-
out the manuscript preparation process. Each chapter was reviewed by two or
more anonymous reviewers and then revised to address the concerns of the
reviewers. While most individual chapter authors were contacted for the revi-
sions, the editor revised some of the chapters. The list of authors who contrib-
uted full chapters to this book is as follows:
• Nurul I. Sarkar, Auckland University of Technology, New Zealand
• Krassie Petrova, Auckland University of Technology, New Zealand
• K. Sandrasegaran, University of Technology, Australia
• Minh Trieu, University of Technology, Australia
• Cecil Goldstein, Queensland University of Technology, Australia
• Karen Stark, Queensland University of Technology, Australia
• Susanna Leisten, Queensland University of Technology, Australia
• Alan Barry Tickle, Queensland University of Technology, Australia
• Kenneth J. Turner, University of Stirling, Scotland
• Anthony P. Kadi, University of Technology, Australia
• David Bremer, Otago Polytechnic, New Zealand
• Trevor M. Craig, Wollongong College, New Zealand
• Wilson Siringoringo, Auckland University of Technology, New Zealand
Contributing Authors
xiii

xiv
• Sanjay Goel, University at Albany, SUNY, and NYS Center for Information
Forensics and Assurance
• Damira Pon, University at Albany, SUNY, and NYS Center for Information
Forensics and Assurance
• David L. Tarnoff, East Tennessee State University, USA
• Maiga Chang, National Science and Technology Program for e-Learning,
Taiwan
• Kun-Fa Cheng, Chih Ping Senior High School, Taiwan
• Alex Chang, Yuan-Ze University, Taiwan
• Ming-Wei Chen, Chih Ping Senior High School, Taiwan
• John Morris, The University of Auckland, New Zealand
• Steve Murray, University of Technology, Australia
• Vladimir Lasky, University of Technology, Australia
• Khaleel I. Petrus, University of Southern Queensland, Australia
• João de Jesus Eduardo Correia, Christchurch Polytechnic Institute of Tech-
nology, New Zealand
• Ricky Watson, Christchurch Polytechnic Institute of Technology, New Zealand

Acknowledgments
I would like to thank each of the chapter authors, without whose
contributions this book would not have been possible. I am indebted
also to the anonymous reviewers for their invaluable time and effort
in reviewing the manuscripts. Their constructive comments and sug-
gestions helped to improve the quality of the book significantly. My
thanks go also to Mr. Michael Taler for providing feedback on Chap-
ter II and to the entire production team at Idea Group Inc. for their
ongoing support. Lastly, but most importantly, to my wife for her pa-
tience, love, and encouragement throughout this project.
Nurul I. Sarkar
xv

Introduction to Computer Networking and Hardware Concepts 1
Copyright © 2006, Idea Group Inc. Copying or distributing in print or electronic forms without written
permission of Idea Group Inc. is prohibited.
Chapter I
Introductionto
ComputerNetworking
andHardwareConcepts
Abstract
This chapter provides an introduction to computer networking and hardware
concepts and highlights the use of software and hardware tools as an aid
to enhance teaching and learning computer networking and hardware
fundamentals. A basic knowledge of network topology, channel access
protocol, network traffic, and networking devices is needed when designing
and implementing a LAN. The term computer hardware refers to the
physical components of a computer system — those that one can see and
touch. The CPU, memory, and input and output devices are the main
components of a computer. To understand the operation of a modern
processor, it is important that the student grasp the basic concepts of
computer hardware.

2 Sarkar
Learning Objectives
After completing this chapter, you will be able to:
• Give an overview of computer networking and hardware fundamentals.
• Draw a block diagram of a computer.
• Discuss the significance of interactive teaching in introductory computer
networking and hardware courses.
• Appreciate the need for software/hardware tools for teaching and learning
various aspects of computer networks and hardware.
Overview of Computer Networking
A computer network consists of two or more computers or other intelligent
devices linked by communication media (e.g., cable or wireless media) to
achieve successful communication. Computer networking is used in many
aspects of our lives, and its applications are proliferating. For example, computer
networks can be found in universities, secondary schools, and colleges, while in
the corporate world, networks link geographically separated offices. Local and
state government offices use computer networks, as do military organizations,
medical facilities, and the Internet.
Computer networks can be categorized as: (1) local area networks (LANs), (2)
metropolitan area networks (MANs), and (3) wide area networks (WANs). The
fundamental differences among LANs, MANs, and WANs are distance cover-
age, transmission speed, media, and error rate. A LAN is a class of computer
network that covers a relatively small geographic area, for example, a room, a
building or a campus. A LAN is owned by a single organization and physically
located within the organization’s premises. IEEE 802.3 Ethernet CSMA/CD
(Carrier Sense Multiple Access with Collision Detection) is an example of a
LAN (IEEE 802.3, 1998). More details about LANs, in general, can be found in
many textbooks (Forouzan, 2003; Keiser, 2002; Stamper, 2001), and LAN design
is discussed in Fitzgerald and Dennis (2002) and Sarkar and Petrova (2005b). A
MAN is a backbone network that links multiple LANs in a large city or a
metropolitan region covering up to 40 km. The IEEE 802.6 Fibre Distributed Data
Interface (FDDI) is an example of a MAN (Comer, 2001; Forouzan, 2004). A
WAN is a class of network that covers a large geographical area (e.g., a country
or a continent). Telephone networks and the Internet are examples of WANs.

How to Design a LAN
To implement a LAN, both hardware and software are required. A network
operating system (NOS), such as Novell NetWare or MS Windows 2003, needs
to be installed on a PC (called the server), and client software is installed on every
PC (called a workstation or client) that is linked to the network. Each workstation
and the server must have a network interface card (NIC). A cable then connects
the NIC to the LAN’s hub or switch.
Table 1 lists the LAN topologies, access protocols, and corresponding network-
ing devices and cables for wired LAN design. In designing and implementing a
LAN, it is important to have a plan for the: (1) network architecture and channel
access protocol (e.g., Ethernet CSMA/CD or token passing), (2) network size
(i.e., number of servers, workstations, printers, etc.), and (3) connecting devices
(e.g., hub-based or switched network).
Figure 1 shows an Ethernet LAN with one file server, 10 workstations, and two
printers using a star physical and logical topology.
Overview of Computer Hardware
A computer is an electronic machine that can process data/information ex-
tremely quickly and accurately. Computer hardware is the visible, physical
component of the computer that we can touch. There are four main components
of a computer system: (1) processor (also called central processing unit, or
CPU), (2) memory, (3) input devices, and (4) output devices. Figure 2 shows a
block diagram of a computer.
Table 1. LAN topologies, access protocols, and networking devices and
associated cables
Topology/Architecture
Channel
Access Method
Device Cable
Physical Bus Logical Bus
Physical Star Logical Bus
Physical Star Logical Star
Physical Star Logical Ring
Physical Ring Logical Ring
Ethernet CSMA/CD
Ethernet CSMA/CD
Ethernet CSMA/CD
Token Passing
Token Passing
-------
Ethernet Hub
Ethernet Switch
Token Ring Hub
------
Coaxial
UTP
UTP
UTP/Optical Fibre
UTP/Optical Fibre

4 Sarkar
The CPU can be thought of as the heart of a computer. Examples of CPUs
include Intel Pentium 4, Motorola M68000, and Zilog Z-80. The memory is used
to store data and instruction. Random access memory (RAM) is an example of
main memory. The input devices are used to enter data (or programs) into the
computer, and output devices are used to display the results. The keyboard and
mouse are common examples of input devices, while the monitor and printer are
common output devices.
The CPU has two main components: (1) arithmetic and logic unit (ALU), and (2)
control unit (CU). The ALU performs all arithmetic, comparison and logical
operations, and the CU controls the processing of instructions and movement of
Figure 1. A server-based Ethernet LAN with 10 PCs and two printers
(physical and logical star topology)
Figure 2. Block diagram of a computer
Switch: some of the switching fabric
Server
Memory
Input
Device
Processor
(CPI)
Output
Device

internal data from one part of the CPU to another. Arithmetic operations include
addition, subtraction, multiplication, and division. Logical operations include
AND, OR, NOT, and Compare. The ALU contains a set of general-purpose
registers called the accumulator. An accumulator is a temporary storage used to
hold data that is used for arithmetic and logical operations. It is also used to hold
results of arithmetic and logical operations. More details about CPUs and
memory can be found in many textbooks (Englander, 2000; Shelly, Cashman, &
Vermaat, 2003).
The CU has several special-purpose registers and their functions are briefly
described below:
• Program counter (PC): The PC holds the address of the next instruction
to be executed.
• Instruction register (IR): The IR holds the actual instruction being
executed currently by the computer.
• Memory address register (MAR): The MAR holds the address of a
memory location.
• Memory data register (MDR): The MDR holds a data value that is being
stored to or retrieved from the memory location currently addressed by the
memory address register.
• Status register (SR): The SR indicates the results of an arithmetic and
logic unit operation. For example: carry, overflow, negative.
Figure 3 shows the main components of a control unit.
Figure 3. Components of a control unit
Components of CU
PC
IR
MAR
MDR
SR
CU = Control Unit
PC = Program Counter
IR = Instruction Register
MAR = Memory Address Register
MDR = Memory Data Register
SR = Status Register

6 Sarkar
The CPU-Memory Interaction
A computer processes and stores data as a series of binary digits called bits. A
bus is a collection of wires or lines used for transferring data and instructions
between the CPU and the main memory; one line for each bit (data and address).
There are three types of CPU buses: (1) address bus, (2) data bus, and (3) control
bus. The address bus is used to select a memory address or location and can be
8-bit, 16-bit, or 32-bit. The data bus is used to carry data or the address of the
data between the CPU and main memory and vice versa. The data bus can be
8-bit, 16-bit, 32-bit, or 64-bit. The control bus is used to carry control signals (e.g.,
READ, WRITE, HALT) to perform specific operations. For example, when the
READ signal is activated (i.e., R/W line is high or 1), the memory performs the
READ operation. Figure 4 illustrates the CPU-memory interaction.
The Fetch-Execute Cycle
Depending on the complexity of each operation (i.e., task), the computer may
take two or more machine cycles in order to complete the task. A machine cycle
consists of both fetch and execution cycles. In the fetch cycle, the CU brings the
program instruction from the memory, decodes it (i.e., translates the instruction
into commands), and then sends the data to the ALU for execution. In the
execution cycle, the ALU performs an operation and then sends the result to the
memory for temporary storage. Figure 5 illustrates the basic concept of the
fetch-execution cycle.
Figure 4. The CPU-memory interaction
CPU
Address Bus
MEMORY
Data Bus
Control Bus

Tools for Teaching Computer
Networking and Hardware Concepts
Computer networking and hardware courses are becoming increasingly popular
in universities, polytechnical institutions, postsecondary colleges, and private
training institutions worldwide because of the high demand for people with
computer networking and hardware skills.
The learning-by-doing approach is an essential component in courses on
computer networking and hardware fundamentals (Abe et al., 2004; Burch,
2002; Comer, 2002; Sarkar, 2005). The view is frequently supported in the
educational literature (Anderson, Reder, & Simon, 1996; Young, 1993) that
students learn computer networking and hardware concepts better if they are
given hands-on practical exercises that illustrate theoretical concepts. Yet,
despite the Chinese adage, attributed to Confucius (551-479 BC), “I hear, I
know. I see, I remember. I do, I understand,” only a limited amount of material
designed to supplement the teaching of computer networking is publicly avail-
able, as searches of the Computer Science Teaching Center Web site (http://
www.cstc.org/)andtheSIGCSEEducationLinkspage(http://sigcse.org/topics/)on
the Special Interest Group on Computer Science Education Web site reveal.
To enable students to appreciate and understand computer networking and
hardware fundamentals, a teaching and learning tool should be Web-based,
portable, modular, configurable, and extensible. Some existing tools for teaching
and learning computer networking and hardware concepts are described next.
Figure 5. Fetch and execution cycle
Control Unit ALU
2. Decode instruction
1. Fetch instruction
3. Get data
4. Perform operation
Primary Memory/RAM

8 Sarkar
Some Existing Tools for Teaching Computer-Networking
Concepts
Both open source and commercial tools are available for building a variety of
network models and visualization of network topologies. We briefly highlight
some of the tools reported in the computer-networking literature that are suitable
for classroom use.
• ns-2 (Fall & Varadhan, 2003): The network simulator ns-2 is a powerful,
text-based simulation software package suitable for performance analysis
and evaluation of computer networks. It is a discrete event simulator
originally developed at Lawrence Berkeley Laboratory at the University of
California, Berkeley, as part of the Virtual InterNetwork Testbed (VINT)
project. The Monarch project at Carnegie Mellon University (Monarch,
2004) has extended the ns-2 by adding support for IEEE 802.11 wireless
LANs.
• OPNET (2004): OPNET is a popular commercial software package
commonly used by researchers and practitioners for modeling and simula-
tion of computer networks. Unlike ns-2, OPNET is menu-driven with an
easy-to-use graphical user interface for rapid model construction, data
collection, and other simulation tasks. As working with the simulator
involves setting up complex experiments, it might be suitable as a learning
environment in advanced networking classes.
• cnet (McDonald, 2004): The cnet network simulator enables experimen-
tation with protocols at the data link, routing, and transport layers in
networks consisting of any combination of WANs and LANs. Although
cnet is being used worldwide in undergraduate networking courses, the
need to prepare a network topology file as the basis of topology visualization
might be a challenging task for beginners.
• JASPER (Turner & Robin, 2001): JASPER (Java Simulation of Proto-
cols for Education and Research) is a protocol simulator that can be used
as an aid to enhance teaching and learning communication protocols. It is
an extensible tool in which students can readily add new protocols.
• WebLan-Designer (Sarkar & Petrova, 2005a): WebLan-Designer is a
Web-based tool for interactive teaching and learning both wired and
wireless LAN design. Using the “modeling” page, students can experiment
with a variety of LAN topologies and channel access protocols. Students
can also test their knowledge of various aspects of LAN design by using
two interactive quizzes. Each quiz consists of a set of more than 25 multiple-
choice questions, each with four possible answers. At the end of each quiz

session, the system displays the total score, which allows students to assess
their prior knowledge about LAN design. The system provides a friendly
environment for interactive quiz management. This is particularly useful for
the teacher to update quizzes on a regular basis.
• DlpSim (King, 2004): DlpSim (data link protocol simulator) may be
suitable for classroom use to enhance teaching protocols through simula-
tion. However, its emphasis is exclusively on data link layer protocols.
• WebTrafMon (Hong, Kwon, & Kim, 1999): The WebTrafMon is a
Web-based system for network analysis and traffic monitoring. However,
the system focuses exclusively on network analysis and traffic monitoring,
and the system needs to be configured and set up for use in a teaching
environment.
• NetMod (Bachmann, Segal, Srinivasan, & Teorey, 1991): The NetMod
is a network modeling tool which uses some simple analytical models,
providing designers of large, interconnected local area networks with an in-
depth analysis of the potential performance of such systems. The tool can
be used in university, industrial, or governmental campus networking
environments and might serve as a useful demonstration in the classroom.
• iNetwork (see Chapter III): iNetwork is an interactive software tool for
teaching and learning data communication networks. iNetwork allows
students to assemble and build customised networks using networking
devices such as workstations, switches, routers, DNS servers, and DHCP
servers. Students can simulate data communication between networking
devices and identify and troubleshoot problems in their custom-built net-
works. Through experimenting with key parameters, students gain insights
into the key concepts of communication network design and analysis.
Some Existing Tools for Teaching Computer Hardware
Concepts
A number of open source tools exist for modeling and simulation of computer
hardware and processors. We briefly review some existing tools, suitable for
classroom use, that have been reported in the literature.
• Logisim (Burch, 2002): Logisim is a software tool for logic circuit design
and simulation which is suitable for classroom use. It has a graphical user
interface, which helps students to gain a better understanding of the design
and simulation of logic circuits. Logisim is a Java application and can be run
on both Windows and UNIX workstations.

10 Sarkar
• DigitalWorks 3.0 (Anonymous, 2006): DigitalWorks is similar to Logisim
inthatitprovidesagraphicaltoolboxinterfaceforcomposingandsimulating
logic circuits.
• WinLogiLab (Hacker & Sitte, 2004): WinLogiLab is an interactive
Microsoft-Windows-compatible computerized teaching suite suitable for
classroom use as an aid to enhance teaching and learning digital logic design
concepts. It provides a set of interactive teaching aids to approach the
basics of combinatorial and sequential digital circuit design. WinLogiLab is
targeted toward introductory digital design courses in electrical and com-
puter engineering curricula.
• Web-based processor simulator (see Chapter XIV): This is a Web-
based modular and extensible processor simulator designed as an aid to
teaching and leaning computer architecture and hardware concepts. Stu-
dents in advanced classes are able to incorporate new modules by simply
writing new Java classes and adding them to a configuration file, which
specifies the new modules’ connections to other modules. The modular
structure means that it can be used for both introductory computer
organization and more advanced processor architecture courses.
• LOGIC-Minimiser (see Chapter XVI): LOGIC-Minimiser is an inter-
active software tool suitable for classroom use as an aid to enhance
teaching and learning Boolean expression minimization. It serves as both
student-centered, self-paced learning and a classroom demonstration tool.
LOGIC-Minimiser is easy to use and can be run under MS-DOS/Windows
machines.
• Picocontroller simulator (Collier, 2003): This is an interactive applet in
a Web page for PIC16F84 picocontroller simulation. It displays the source
program, RAM locations, and the contents of special function registers.
Users can step through programs observing the memory changes to
facilitate an understanding of the operation of the picocontroller.
Outline of the Remainder of This Book
Chapter II. Motivating students to learn local area network (LAN) design can
be difficult since students find the subject dry, technical, and boring. To
overcome this problem, the authors have developed a Web-based software tool
named WebLan-Designer for interactive teaching and learning both wired and
wireless LAN design. Chapter II reports on the development and use of
WebLan-Designer as an aid to enhance teaching and learning LAN design. It

also highlights the educational benefits of using WebLan-Designer in classroom
settings.
Chapter III. A country or a nation would be immobilized without its computer
and data communication networks. Computer networking courses are being
offered by not only universities and tertiary institutions but also many technical
colleges and secondary schools worldwide. The cost associated with purchasing
networking devices and equipment to enable students to gain practical experi-
ence in setting up a customised network can be significant. Therefore, network-
ing fundamentals are taught by a combination of textbooks and lecture-only
methods in many schools and publicly funded tertiary institutions. Chapter III
describes the development and use of an interactive learning tool called
iNetwork for teaching and learning computer communication networks. iNetwork
provides an environment in which students can experiment with different
network configurations and gain hands-on learning experience in computer and
data communication networks without the need for expensive equipment.
Chapter IV. Teaching computer networking in large classes (e.g., 350-400
students) can be challenging compared to teaching in small classes of 15-20
students. This is partly because of the difficulty in motivating students to learn
technical and rather dry subjects and also because of the lack of interaction
among the students in large classroom settings. Network simulators allow
students to build a network dynamically by placing network devices as icons on
a screen and connecting them. The graphical display and animation brings more
interactivity and liveliness in the classroom, and consequently it is easier for
students to engage in learning computer networking more effectively. Chapter
IV focuses on the use of a network simulator in large classroom settings to
enhance teaching and learning computer-networking fundamentals.
Chapter V. Communication protocols are essential components of computer
and data communication networks. Therefore, it is important that students grasp
these concepts and become familiar with widely used protocols. Unfortunately,
communication protocols can be complex and their behavior difficult to under-
stand. In order to learn about protocols, a student therefore needs a more
controlled and constrained environment. Chapter V describes the development
and use of a protocol animator for teaching and learning communication
protocols.
Chapter VI. Teaching packet-forwarding theories and concepts in a practical
way to undergraduate students requires both a teaching and learning framework
and a laboratory infrastructure. Creating a teaching and learning framework in
which students can develop a deeper knowledge and understanding of abstract
concepts is not a simple task. In addition to teaching materials, the teacher
requires a clear idea about learning theories and issues: (1) What is learning? (2)
What is knowledge? and (3) How do students go about learning? Chapter VI

12 Sarkar
describes a low-cost laboratory infrastructure for teaching and learning packet-
forwarding theories and concepts. The framework is learner-centred and is
focused on learning experiences in both the classroom and the laboratory. The
laboratory-based activities form a critical component of the overall framework.
Chapter VII. Students can learn data communication and networking protocols
better if they are given hands-on practical exercises, in which the concept of
abstract protocols can be linked to real-world communication concepts. For
example, one can learn about address resolution protocol (ARP) by lectures and
readings. However, by examining actual ARP traffic from a sample of packets,
identifying their behavior, and performing troubleshooting, students gain first-
hand experience that cannot be gained through theoretical study. One of the
challenges that networking educators are facing is the problem of giving students
an “up close and personal” interaction with protocols that are so heavily
immersed in theory. Chapter VII emphasises that real experience with network
protocols is crucial to effective student learning.
Chapter VIII. Due to the rapid developments in wireless communication and
networking technologies and the high demand for wireless networking skills in
the industry worldwide, wireless communication and networking courses are
becoming increasingly popular in universities, polytechnics, and private training
institutions around the globe. Unfortunately, wireless communication and net-
working is a challenging subject to teach in a meaningful way because many
students appear to find the subject technical and rather boring. To overcome this
problem, the authors introduce a set of new projects in order to provide students
of wireless communication and networking with a hands-on learning experience.
The projects are suitable for classroom use in introductory wireless networking
courses.
Chapter IX. Wi-Fi networking has been becoming increasingly popular in recent
years, both in terms of applications and as the subject of academic research
papers and articles in the IT press. It is important that students grasp the basic
concepts of both Wi-Fi networking and wireless propagation measurements.
Unfortunately, the underlying concepts of wireless networking often intimidate
students with their apparently overwhelming complexity, thereby discouraging
the students from learning in-depth this otherwise exciting and rewarding
subject. Chapter IX provides a tutorial on Wi-Fi networking and radio propaga-
tion measurements using wireless laptops and access points. Various hands-on
learning activities are also discussed.
Chapter X. There is a strong need for information security education, which
stems from the pervasiveness of information technology in business and society.
Both government departments and private industries depend on information
systems, as information systems are widespread across all business functions.
Disruption of critical operational information systems can have serious financial

impacts. According to the CSI/FBI report, losses from security breaches have
risen rapidly in recent years and exceeded $200 million in 2003. The information
security field is very diverse and combines disciplines such as computer science,
business, information science, engineering, education, psychology, criminal
justice, public administration, law, and accounting. The broad interdisciplinary
nature of information security requires several specialists to collaboratively
teach the curriculum and integrate different perspectives and teaching styles into
a cohesive delivery. Chapter X presents a pedagogical model based on a
“teaching hospital” concept that addresses the issues introduced above. By using
a specific information risk analysis case, the chapter highlights the basic concept
of the teaching hospital and its application in teaching and learning contexts.
Chapter XI. It is important that students grasp the basic concepts of commu-
nication between a processor and external devices, and become familiar with
tools that are available to implement such systems. Chapter XI describes the
operation of the processor bus and explains how I/O devices are connected to
it. It also discusses advanced I/O techniques and how the operating systems use
I/O to access a computer’s resources.
Chapter XII. Computer hardware, number systems, CPU, memory, and I/O
(input/output) ports are topics often included in computer science, electronics,
and engineering courses as fundamental concepts involved in computer hard-
ware. We believe that students learn computer hardware fundamentals better if
they are given practical learning exercises that illustrate theoretical concepts.
However, only a limited range of material designed specifically to supplement the
teaching of computer hardware concepts is publicly available. Chapter XII
describes a set of PIC-based projects that give students a hands-on introduction
to computer hardware concepts and are suitable for classroom use in under-
graduate computer hardware courses.
Chapter XIII. Students often get a good score in written exams but fail to apply
their knowledge when trying to solve real-world problems. This applies particu-
larly to computer hardware courses in which students are required to learn and
memorize many key terms and definitions. Also, teachers often find it difficult
to gauge students’ progress when teaching computer hardware fundamentals
courses. These problems are related to the learning process, so it is necessary
to find an appropriate instructional model to overcome these problems. Chapter
XIII describes a Web-based tool called an assistant tool based on problem-based
learning (PBL) theory that not only assists instructors in teaching computer
hardware fundamentals but also overcomes the above-mentioned problems.
Chapter XIV. Computer architecture educators are constantly looking for
modular tools that allow processors to be configured in a transparent way; the
visualization enables rapid verification that modules have been connected in the
desired manner. Thus, simple experiments which demonstrate, for example, the

14 Sarkar
effect of different cache organizations are readily configured by instructors or
students. Advanced computer architecture students will also be able to add
experimental capabilities (in the form of new modules or modifications to existing
ones) and perform simple experiments to assess their effect on processor
performance. Chapter XIV discusses the development and use of a processor
simulator in teaching computer architecture at both introductory and advanced
levels. It is written in Java, which allows it to be easily embedded in other Web-
based course materials and run anywhere.
Chapter XV. To teach modern embedded systems, including operating systems,
in a meaningful way, a moderately sophisticated processor is required to
demonstrate many key concepts, such as multitasking, multithreading, structured
and abstracted hardware management layer, communications utilising various
protocols over network interfaces, and memory resident file systems. Unfortu-
nately, high-end 32-bit embedded systems processors capable of supporting
these facilities are expensive compared to conventional 8-bit and 16-bit targets,
and it is not feasible to acquire a large number of them to house in a laboratory
in an effort to enable practical exercises for over 100 students. Chapter XV
describes the development and use of a remotely accessible embedded systems
laboratory that uses a small number of 32-bit development systems and makes
them available to students over the Internet.
Chapter XVI. Boolean algebra, minimization of Boolean expressions, and logic
gates are often included as a subject in electronics, computer science, informa-
tion technology, and engineering courses as computer hardware and digital
systems are a fundamental component of IT systems today. We believe that
students learn minimization of Boolean expressions better if they are given
interactive practical learning activities that illustrate theoretical concepts. Chap-
ter XVI describes the development and use of a software tool (named LOGIC-
Minimiser) as an aid to enhance teaching and learning minimization of Boolean
expressions.
Chapter XVII. Serial communication is used as a long-distance computer
system interface due to its reliability and cost effectiveness. All information
pertaining to the delivery of a message must be contained within a single stream
of bits. In order to implement a serial data communication system, a well-defined
set of rules called a protocol must exist to specify the placement and purpose of
every bit sent across the link. Chapter XVII provides a practical introduction to
serial protocols for data communications. It shows how a protocol analyser can
be used in examining the frames of the data link layer and the packets of the
network layer.
Chapter XVIII. Providing a dedicated lab to each group of students in order to
gain hands-on learning experience is not always possible due to budget and space
constraints. For example, in a class of 20 students, each student requires at least

three computers with each computer capable of running three operating systems,
such as UNIX, Linux, and Windows Server 2003. This requires a large computer
laboratory with 60 computers in total. In addition, it is difficult to manage the
laboratory to accommodate students from other classes. For example, once one
class leaves the laboratory, another class of 20 students needs to start immedi-
ately, with each person configuring Windows Server 2003 Active Directory on
four computers. This requires another large computer laboratory with eighty
computers. Chapter XVIII presents VMware as a teaching and learning tool to
overcome the problems mentioned above. Under the VMware system, students
do not require administrative privileges on physical machines. Consequently,
they have complete freedom to experiment within their own virtualised environ-
ments.
Conclusion
Because of the high demand for people with computer networking and hardware
skills worldwide, computer networking and hardware courses are becoming
increasinglypopularinbothtertiaryandprivatetraininginstitutions.Unfortunately,
motivating students to learn computer networking and hardware concepts is often
difficult because students appear to find the subject technical and rather dry.
Interactive teaching and learning using software/hardware tools is an attractive
solution to the problem of motivating students to learn computer networking and
hardware fundamentals. This chapter describes the basic concepts of computer
networking and hardware fundamentals and highlights various tools for interac-
tive teaching and learning computer networking and hardware concepts. It also
provides an outline of the remainder of the book.
Summary
Computer networks can be classified as local area networks, metropolitan area
networks, and wide area networks. Each class of network has certain charac-
teristics that make it suitable for certain networking applications. A basic
knowledge of network topology, channel access protocol, network traffic, and
networking devices is needed when designing and implementing a LAN.
The term computer hardware refers to the physical components of a computer
system — those that one can see and touch. The CPU, memory, and input and

16 Sarkar
output devices are the main components of a computer. To understand the
operation of a modern processor, it is important that the student grasp the basic
concepts of computer hardware. An overview of computer networking and
hardware concepts is presented, and various tools for interactive teaching and
learning computer networking and hardware essentials are highlighted.
Key Terms and Definitions
DHCP: DHCP stands for dynamic host configuration protocol. It is often used
to dynamically assign IP addresses to hosts.
DNS: DNS stands for domain name system. It is a service used to map
hostnames onto IP addresses and allow for resolution of hostnames to IP
addresses.
Ethernet: A popular LAN technology that uses a shared channel and the
CSMA/CD access method. Basic Ethernet operates at 10 Mbps, Fast
Ethernet operates at 100 Mbps, and Gigabit Ethernet operates at 1,000
Mbps.
Hub: A networking device that interconnects two or more workstations in a star-
wired local area network and broadcasts incoming data onto all outgoing
connections. To avoid signal collision only one user can transmit data
through the hub at a time.
LAN: LAN stands for local area network. A class of computer network suitable
for a relatively small geographic area, for example, a room, a building, or
a campus. A LAN is owned by a single organization and physically located
within the organization’s premises. Ethernet is the most popular LAN
architecture.
Logical topology: This refers to the way the data is sent through the network
from one computer (or device) to another.
MAN: MAN stands for metropolitan area network. A MAN is a backbone
network that links multiple LANs in a large city or a metropolitan region.
NIC: NIC stands for network interface card. It is the hardware interface that
provides the physical link between a computer and a network.
NOS: NOS stands for network operating system. It is a complex set of computer
programs that manage the common resources of a local area network. In
addition, NOS performs the standard operating system services. Examples
are NetWare, Linux, and MS Windows 2003.
Optical fibre: A type of cable which consists of one or more glass or plastic fibre
cores inside a protective cladding material, covered by an outer plastic PVC

jacket. Signal transmission along the inside fibres is accomplished using
light pulses. The optical fibre cable is characterised by an extremely large
data-carrying capacity. Optical fibre is used for undersea cables and for
countrywide telecommunications backbones.
Peer-to-peer network: A class of network in which a computer can commu-
nicate with any other networked computers on an equal or peer-like basis
without going through an intermediary, such as a server or a dedicated host.
Physical topology: This refers to the way computers and other devices are
connected within the network physically.
Protocol: A protocol is a collection of rules for formatting, ordering, and error-
checking data sent across a network.
Switch: Unlike a hub, a switch allows multiple users to communicate simulta-
neously in order to achieve a higher throughput.
WAN: WAN stands for wide area network. A WAN covers a large geographical
area (e.g., a country or a continent). Telephone networks and the Internet
are examples of WANs.
Workstation: An end-user computer that has its own CPU and is used as a
client to access another computer, such as a file server.
Review Questions
1. What is a network? Discuss the basic difference between a local area
network and a wide area network.
2. List and describe three important components of a communication system.
3. Define the following networking terms: LAN, MAN, WAN, protocol, peer-
to-peer network, and server-based network.
4. You are given the following components: one server, 10 PCs, and one
printer. Draw a diagram to show how the above components can be
connected to construct a LAN using: (a) bus topology, (b) ring topology, and
(c) star topology. Use a hub/switch when appropriate.
5. Discuss the importance of interactive teaching in introductory computer
networking and hardware courses.
6. List and describe four main components of a computer system.
7. List and describe two main components of a central processing unit.
8. Describe the function of address, data, and control buses.
9. Draw a diagram to illustrate the interaction between a CPU and the main
memory.

18 Sarkar
10. Discuss the significance of software/hardware tools in teaching and
learning computer networking and hardware concepts.
11. List and describe three software tools suitable for classroom use to
enhance teaching and learning computer-networking concepts.
References
Abe, K., Tateoka, T., Suzuki, M., Maeda, Y., Kono, K., & Watanabe, T. (2004).
An integrated laboratory for processor organization, compiler design, and
computer networking. IEEE Transactions on Education, 47(3), 311-320.
Anderson, J. R., Reder, L. M., & Simon, H. A. (1996). Situated learning and
education. Educational Researcher, 25(4), 5-11.
Anonymous. (2006). Digital Works. Retrieved January 5, 2006, from http://
www.spsu.edu/cs/faculty/bbrown/circuits/howto.html
Bachmann, D. W., Segal, M. E., Srinivasan, M. M., & Teorey, T. J. (1991).
NetMod: A design tool for large-scale heterogeneous campus networks.
IEEE Journal on Selected Areas in Communications, 9(1), 15-24.
Burch, C. (2002). Logisim: A graphical system for logic circuit design and
simulation. Journal of Educational and Resources in Computing, 2(1),
5-16.
Collier, M. (2003). A picocontroller training simulator in a Web page. Interna-
tional Journal of Electrical Engineering Education, 40(2), 158-168.
Comer, D. E. (2001). Computer networks and Internets with Internet appli-
cations (3rd
ed.). Prentice Hall.
Comer, D. E. (2002). Hands-on networking with Internet technologies.
Prentice Hall.
Englander, I. (2000). The architecture of computer hardware and systems
software: An information technology approach (2nd
ed.). Wiley.
Fall, K., & Varadhan, K. (2003). The ns manual. Retrieved January 5, 2006,
from http://www.isi.edu/nsnam/ns/
Fitzgerald, J., & Dennis, A. (2002). Business data communications and
networking (7th
ed.). New York: Wiley.
Forouzan, B. A. (2003). Local area networks (1st
ed.). McGraw-Hill.
Forouzan, B. A. (2004). Data communications and networking (3rd
ed.).
McGraw-Hill.

Hacker, C., & Sitte, R. (2004). Interactive teaching of elementary digital logic
design with WinLogiLab. IEEE Transactions on Education, 47(2), 196-
203.
Hong, J. W.-K., Kwon, S.-S., & Kim, J.-Y. (1999). WebTrafMon: Web-based
Internet/intranet network traffic monitoring and analysis system. Com-
puter Communications, 22(14), 1333-1342.
IEEE 802.3. (1998). Information technology—Telecommunications and in-
formation exchange between systems—Local and metropolitan area
networks specific requirements—Part 3: Carrier sense multiple access
with collision detection (CSMA/CD) access method and physical layer
specifications. Unpublished manuscript.
Keiser, G. (2002). Local area networks (2nd
ed.). McGraw-Hill.
King, P. J. B. (2004). dlpjava. A data link protocol simulator. Retrieved
January 5, 2006, from www.cee.hw.ac.uk/~pjbk/dlpjava
McDonald, C. (2004). The cnet network simulator (v2.0.9). Retrieved January
5, 2006, from www.csse.uwa.edu.au/cnet/
Monarch. (2004). CMU Monarch project. Retrieved January 5, 2006, from
http://www.monarch.cs.cmu.edu
OPNET. (2004). OPNET Technologies—Commercial simulation software.
Retrieved June 20, 2004, from www.opnet.com
Sarkar, N. I. (2005). LAN-Designer: A software tool to enhance learning and
teaching server-based LAN design. International Journal of Informa-
tion and Communication Technology Education, 1(2), 74-86.
Sarkar, N. I., & Petrova, K. (2005a). The WebLan-Designer. Retrieved
January 5, 2006, from http://elena.aut.ac.nz/homepages/weblandesigner/
Sarkar, N. I., & Petrova, K. (2005b, June 27-30). WebLan-Designer: A Web-
based system for interactive teaching and learning LAN design. Paper
presented at the 3rd
IEEE International Conference on Information Tech-
nology Research and Education, Hsinchu, Taiwan (pp. 328-332).
Shelly, G. B., Cashman, T. J., & Vermaat, M. E. (2003). Discovering comput-
ers 2004: Complete. Course Technology.
Stamper, D. (2001). Local area networks (3rd
ed.). Prentice Hall.
Turner, K. J., & Robin, I. A. (2001). An interactive visual protocol simulator.
Computer Standards & Interfaces, 23, 279-310.
Young, M. F. (1993). Instructional design for situated learning. Educational
Technology, 41(1), 43-58.

20 Sarkar
Section II
Teaching and Learning
Computer Networking

WebLan-Designer 21
Chapter II
WebLan-Designer:
A Web-Based Tool to
Enhance Teaching and
Learning Wired and
Wireless LAN Design
Krassie Petrova, Auckland University of Technology, New Zealand
Abstract
It is somewhat difficult to motivate students to learn both wired and wireless
local area network design because students find the subject technical, dry
when delivered in class, and rather boring. This chapter introduces the
case of a Web-based tool for class demonstration as well as modelling LAN
design. The background of the case is presented and is followed by a review
of some existing tools for network simulation and modelling. After
introducing the learning theories and concepts (e.g., experiential learning
and constructivism) relevant to the tools’ pedagogical value, the chapter
describes the architecture and components of WebLan-Designer. The main
benefits of using WebLan-Designer are discussed in the light of educational
theories, and their validation is supported by a summary of comments
received. The chapter concludes with remarks on the strengths and
weaknesses of WebLan-Designer and its future development.

22 Sarkar & Petrova
Learning Objectives
• Discuss the usefulness of WebLan-Designer in teaching and learning
contexts.
• Use WebLan-Designer in both face-to-face and distance learning environ-
ments for teaching and learning LAN design.
• Verify the solutions to LAN design exercises using WebLan-Designer.
• Suggest further enhancements to WebLan-Designer.
Introduction
It is somewhat difficult to motivate students to learn both wired and wireless local
area network design because students find the subject technical, dry when
delivered in class, and rather boring. Educators have experimented with different
approaches to alleviate this problem. Examples include computer-assisted
learning packages (Diab & Tabbara, 1995), game-based simulation (Shifroni &
Ginat, 1997), approaches based on the constructivist paradigm (Chen, 2003),
experiential learning (R. K. C. Chang, 2004), and learning research techniques
such as the phenomenographical approach (Berglund, 2003).
This chapter introduces the case of a Web-based tool for class demonstration as
well as modelling LAN design. The motivational background of the case is
presented in the next section and is followed by a review of some existing tools
for network simulation and modelling. After introducing the learning theories and
concepts (e.g., experiential learning and constructivism) relevant to the tools’
pedagogical value, the chapter describes the architecture and components of
WebLan-Designer. The main benefits of using WebLan-Designer are discussed
in the light of educational theories, and their validation is supported by a summary
of comments received. The chapter concludes with remarks on the strengths and
weaknesses of WebLan-Designer and its future development.
Background and Motivation
LANs are often included as a topic in computer science, information technology,
engineering, and business courses as LANs are a fundamental component of IT

WebLan-Designer 23
systems today. We believe that students learn LAN design better if they are
given interactive practical exercises that illustrate theoretical concepts. There is
still very little material publicly available to supplement the teaching of LAN
design, as a searches of the Computer Science Teaching Center Web site (http:/
/www.cstc.org/) and the SIGCSE Education Links page (http://sigcse.org/
topics/) on the Special Interest Group on Computer Science Education Web site
reveal. Even less course material is available on wireless networking and related
topics. The need for learner support in the areas of computer networking is
especially strong (Petrova, 2002).
We strongly believe, as do many others (Abe et al., 2004; Bhunia, Giri, Kar,
Haldar, & Purkait, 2004; Garcia & Alesanco, 2004; Hacker & Sitte, 2004), that
students learn more effectively from courses that involve them in interactive
learning activities. The theoretical underpinnings of this approach come from
two theories of learning: experiential learning and constructivism. First, the
hands-on learning experience is derived from learning which involves observa-
tion and experimentation and aims to help students develop skills in testing out
different approaches to completing a project (Kolb, Boyatzis, & Mainemelis,
2000). Secondly, as students make their way through the basic framework of
pre-supplied content-related constructs, they are given the opportunity to
develop and reorganize their own concepts and ideas. Learning occurs not by
absorption but through the construction of students’ own knowledge in authentic
context (Chen, 2003).
Computer networking is a particularly challenging subject to learn and to teach
in a meaningful way; students may find the subject technical and rather dry when
presented. A team of Auckland University of Technology-based researchers
developed a Web-based tool called WebLan-Designer, aiming to provide stu-
dents with an interactive learning experience in LAN design. A teacher involved
in an introductory networking course might be able to use WebLan-Designer in
the classroom as a demonstration to enhance the lecture environment. Students,
on the other hand, can use the system to complete networking assignments and
verify (interactively and visually) the solutions to LAN design exercises and in-
class tasks. WebLan-Designer can be accessed at any time either through an
intranet or the Internet. In addition to enhancing classroom teaching by including
an element of online learning, WebLan-Designer also provides online support for
off-campus students and enhances learning by engaging them in a flexible,
learner-centered manner.
LAN design concepts are described in many textbooks (Bing, 2002; Dornan,
2002; Palmer & Sinclair, 2003), and Web-based tools are discussed extensively
in the computer networking literature (Kofke & Mihalick, 2002; Rokou, Rokos,
& Rokou, 2003; Sitthiworachart & Joy, 2003). In the following section we briefly
review various existing software tools related to the proposed system described
in this chapter.

24 Sarkar & Petrova
Some Existing Tools: A Review
Various tools and simulators (both open source and commercial) are available for
building LAN models (X. Chang, 1999; Sanchez & Manzoni, 2001; Zheng & Ni,
2003). However, these often powerful systems can have a steep learning curve,
and while excellent for doing an in-depth performance evaluation of LANs, the
simulated networking environment created is typically far more detailed than is
necessary for introduction to fundamental concepts. Some of the tools which are
reported in the networking literature are described below.
• NetMod (Bachmann, Segal, Srinivasan, & Teorey, 1991): NetMod is
a network modelling tool which uses simple analytical models to provide
designers of large, interconnected LANs with an in-depth analysis of the
potential performance of these systems. The tool can be used in university,
industrial, or governmental campus networking environments, comprising
thousands of computer sites. NetMod is implemented in combination with
the easy-to-use software (HyperCard, Excel).
• The Layer-Module set (Diab & Tabbara, 1995): This teaching tool for
computer network systems includes graphical animation and simulation of
the functions of a network. The environment provides textual information
on the seven OSI layers, supplemented with figures, examples and demon-
strations, and multiple-choice questions. Protocol simulation is used; for
example, the shortest path first and network flow using graph theory.
• WebTrafMon (Hong, Kwon, & Kim, 1999): The WebTrafMon is a
Web-based system for network analysis and traffic monitoring. It provides
monitoring and analysis capabilities not only for traffic loads but also for
traffic types, sources, and destinations. Using a Web browser, users can
monitor traffic statistics and review traffic history.
• ns-2 (Fall & Varadhan, 2003): Ns-2 (network simulator) is a powerful
text-based simulation software package suitable for performance analysis
of computer networks.
• Network Intelligence (Nieuwelaar & Hunt, 2004): Network Intelli-
gence (NI) provides an easy way to view complex traffic patterns in a wide
area networking environment. NI can perform simulations of network
topologies using actual gathered data as opposed to arbitrary data.
• cnet (McDonald, 2004): The cnet network simulator enables experimen-
tation with various data link, network, routing, and transport networking
protocols in networks consisting of any combination of wide area networks
(WANs) and LANs. As a learning tool, cnet has been used worldwide in
undergraduate networking courses.

WebLan-Designer 25
• LAN-Designer (Sarkar & Lian, 2003): LAN-Designer is a prototype
software tool for wired LAN modelling. The software is simple and easy
to use and can be used either in the classroom or at home to enhance
teaching and learning of some aspects of LAN design. However, the
current version of LAN-Designer has very limited features and requires
significant improvement.
• WLAN-Designer (Sarkar, 2004): WLAN-Designer is a Web-based
software tool for wireless LAN modelling (still a prototype). The software
is easy to use and can be accessed either from an intranet or through the
Internet to enhance learning and teaching of various aspects of wireless
LAN design. As LAN-Designer, the current version of WLAN-Designer
requires improvement.
WebLan-Designer, which we describe in the next section, has its own
unique features, including the integration of wired and wireless LAN
design, simplicity, ease-of-use, and a Web-based interactive system.
WebLan-Designer Architecture
and Components
Figure 1 illustrates the three-tier client-server architecture approach used in
implementing the system.
The components of WebLan-Designer are shown in Figure 2. The system
consists of two parts: (1) wired LAN design and (2) wireless LAN design. Both
parts of WebLan-Designer have the following main components:
Figure 1. Architecture of WebLan-Designer
Internet
Web browser
Web server
WebLan-Designer
Database

26 Sarkar & Petrova
• Tutorial: A step-by-step guide designed to take the student through a set
of tasks related to the type of network studied, aiming to enhance the
student’s knowledge and understanding of various aspects of LAN design.
Each tutorial includes self-assessment both at commencement and after
completion.
• Quiz: Students can test their knowledge on both wired and wireless LAN
design at any time by using the two interactive quizzes. Each quiz consists
of a set of 50 multiple-choice questions with four possible answers, and
each question is designed to cover a key concept of LAN design. At the end
of a quiz session, the system displays the total score, which allows the
student to assess his or her knowledge about LAN design. This also allows
the teacher to gauge students’ prior knowledge; for example, how much
students already knew about LAN design before starting the course. As
students use WebLan-Designer’s learning resources, such as LAN mod-
elling and networking key terms and definitions, to learn about some aspects
of LAN design, it might be useful to be able to see the impact of WebLan-
Designer on students’ learning about LAN design. This can be achieved by
comparing the total scores obtained from two quiz sessions: (1) before and
(2) after using the WebLan-Designer learning resources.
• Modelling: It provides an interactive and easy way to develop a variety of
LAN models. Using the “modelling” page of WebLan-Designer, students
Figure 2. Components of WebLan-Designer
WebLan-Designer
Wired LAN
Interactive Quiz
Tutorial
Modelling
Key terms
Scenarios
Review questions
Wireless LAN
Interactive Quiz
Tutorial
Modelling
Key terms
Scenarios
Review questions

WebLan-Designer 27
can experiment with LAN topologies and channel access protocols to
enhance their knowledge and understanding of LAN design. Table 1 lists
the supported topologies and access methods.
Figure 3 shows a screenshot of a modelling page of WebLan-Designer. An
infrastructure wireless LAN is modelled, including 10 workstations, eight
personal digital assistants (PDAs), and two printers.
• Key terms: The key terms and definitions of various topics related to both
wired and wireless networking are summarized in these pages. Examples
of key terms related to LAN design include: bus, star, and ring physical
topologies, logical topology, channel, channel access protocol, CSMA/CD,
Table 1. Topologies and access protocols
Topology/Architecture Channel access method
Wired LAN
Physical Bus Logical Bus
Physical Star Logical Bus
Physical Star Logical Star
Physical Ring Logical Ring
Physical Star Logical Ring
Ethernet CSMA/CD
Token Passing
Wireless LAN
Ad Hoc Network
Infrastructure Network
CSMA/CA
Figure 3. A screenshot of a modelling page

28 Sarkar & Petrova
token passing, workstation, file server, hub, switch, and UTP Cat 5e.
Examples of key terms related to wireless LANs include: ad hoc network,
infrastructure network, PCMCIA card, access point, wireless channel,
CSMA/CA, OFDM, modulation, line of sight, direct sequence spread
spectrum (DSSS), and frequency-hopping spread spectrum (FHSS).
• Scenarios: This feature allows students to examine example backbone
networks based on small business and corporate case scenarios. By
observing an integrated LAN which spans over multiple floors on two or
more buildings (close or at a distance), students can enhance their
knowledge and understanding about campus, small business, and corpo-
rate-wide LAN design. Two scenario examples are shown in Table 2.
• Review questions: The review questions in each part serve as an
extension of the quiz and modelling tasks. Examples include: What layer of
the OSI model is concerned with turning binary code into a physical signal?
and What type of propagation is used by low-frequency radio waves
traveling close to the Earth? The review questions broaden the scope of the
system as they refer to knowledge gained through other activities, such as
lectures or independent reading. We felt that adding a suggested answer
would serve the purposes of learning better than leaving the questions
unanswered.
WebLan-Designer is currently installed on a Web server at Auckland Univer-
sity of Technology (AUT) and is being tested for performance and robustness.
The database-driven implementation is based on the use of PHP and MySQL and
involves a combination of static and dynamic Web pages. Two examples of the
models that the modelling engine creates are shown in Figure 4.
Table 2. Scenario examples
A wired network scenario A wireless network scenario
Two of the university departments are about to
be rehoused and jointly need to install a new
computer laboratory. This laboratory will
occupy two adjacent rooms, with each room
containing 40 PCs. The requirements are: (1)
Each laboratory must be capable of operating
independently. It should be possible to disable
the network in each room separately and at a
single point. (2) The two laboratories should be
capable of being combined for use with large
classes. (3) Each laboratory needs to have its
own Windows 2003 server. Both laboratories
will need to have access to a Linux server,
which they will share.
Pizza House wants to attract more customers
to its pizza parlor in King Street and has
decided to offer a Hotspot Internet Coupon
(Hroup) with every pizza ordered on the spot.
One Hroup gives a 30-minute free Internet
access to any customer who has ordered a
pizza and has a wireless-enabled PDA, a
laptop, or a mobile phone that can access the
Wi-Fi hotspot. The coupon expires if not used
within 1 hour of the purchase. Pizza House has
signed a deal with Broad Bush (a local ISP) to
obtain from them cheap broadband (wireless)
Internet access and use it to offer to Hroup
holders.

WebLan-Designer 29
Teaching and Learning Aspects of
Using WebLan-Designer
For simplicity and ease of use, WebLan-Designer has a graphical user interface
(GUI). The GUI is not only user-friendly but self-explanatory.
Let us briefly highlight the value of WebLan-Designer and how we use it in
teaching and learning contexts. At AUT, the authors teach various aspects of
networking and LAN design, including wireless networks, across three different
programmes: (1) bachelor of business, (2) bachelor of computer and information
sciences, and (3) diploma in IT classes. In line with the observation made by other
authors, for example, Berglund (2003), our experience shows that at times it is
quite difficult to motivate students to learn about wired and wireless LAN design
using the traditional lecture-only method. Students find the topic full of technical
jargon, rather dry when delivered in lecture, and even boring.
Figure 4. (a) A model of a wired LAN (Ethernet); (b) a model of a wireless
LAN (ad hoc)
(a) (b)

30 Sarkar & Petrova
To make the lessons more interesting and to encourage students’ participation
in class, we use WebLan-Designer as an integral part of two 2-hour sessions; for
example, the first session might be based on wired LANs and the second session
on wireless LANs. In the classroom, students are asked to design a server-based
LAN on paper. After a prescribed period of time (e.g., 15 minutes), we introduce
WebLan-Designer to the students and do a walk-through with them to verify
(visually and interactively) their solutions and to learn more about server-based
LAN design. The interactive quizzes, review questions, and key term definitions
are also being used, complementing the modelling task.
In addition to classroom use, the students can access WebLan-Designer from
home and work on exercises and tutorials in their own time and at their own pace.
Thus the tool not only enhances lectures by including an element of online
learning but also provides off-campus online support for students. This is
especially important for students taking courses in a flexible mode, combining
face-to-face classes with self-directed online learning. Figure 5 shows sche-
matically two suggested study guidelines (wired LANs).
As discussed earlier, teaching networking concepts without the ability to engage
students in some practical work makes networking classes dry and boring and
does not motivate students. Consequently, the tool described here attempts to
provide a space for experimentation and knowledge construction, building on
findings in the literature on experiential learning (Kolb, Boyatzis, & Mainemelis,
2000; Kolb & Kolb, 2004) and the constructivist approach to teaching and
Figure 5. A suggested sequence of study
Start Start
Or
Quiz - Wired LAN
Key Terms
Key Terms
LAN Modelling
LAN Modelling
LAN design exercises
LAN design exercises
Scenario-based design
Scenario-based design
Quiz - Wired LAN
Verify
Verify

WebLan-Designer 31
learning using computer-based tools (Chen, 2003; Resnick, 2002). Summarizing
the findings of a large body of research in experiential learning, Kolb et al. point
out that learners from a nontechnical background such as business and manage-
ment tend to learn better when engaged in “concrete experimentation” and
“active experimentation.” With regard to teaching networking, Chen suggests
that constructivism could provide a sound theoretical foundation for teaching
given the complexity of the domain. We believe that the tool described in this
chapter offers educational benefits aligned with the view that students today
need to learn actively and independently, “with the teacher serving as consultant,
not chief executive” (Resnick, 2002).
Firstly, the tool is easy to use and navigate and is accessible through the Internet.
Therefore, it is suitable for a distance learning (off-campus) environment. The
user access to the system can be restricted through a login/password to comply
with additional requirements or constraints. Secondly, the learner is engaged in
a broad and dynamic learning experience. For example, the modelling function
provides a simple and easy way to develop a variety of network configurations,
and students can experiment with LAN topologies and channel access protocols
and thus gain a better understanding of LAN design. In addition to LAN
modelling, eight business case scenarios and suggested solutions, which provide
real-world examples to students about the organization and corporate network-
ing requirements, are included in the system. The combining experimentation
through modelling and observation using scenarios enable students to construct
their own knowledge (Chen, 2003), which might be especially important for
learners from a nontechnical background (Kolb et al., 2000).
WebLan-Designer was trilled for the first time during semester 1 of 2005 in three
classes, and the informal feedback from students was positive. We asked the
teaching community in New Zealand to send us comments, and we hoped to
receive feedback from visitors to the Web site. At the time of writing, we have
received comments from seven lecturers involved in teaching networking (three
from AUT, three from other New Zealand institutions, and one from an overseas
university). The responses are positive (see Table 3) and confirm the validity of
the educational benefits stated above, as lecturers perceive the tool’s compo-
nents as valuable and express interest in using WebLan-Designer in class.
The critical comments are about improving the presentation (spelling and typos)
and also about the need to use the tool with care as not to create an illusion of
“easiness” while trying to make it easy to learn. We agree with these comments
wholeheartedly. The suggested improvements include adding more functions
and adding more internal links; we will consider these suggestions carefully in our
future work.

32 Sarkar & Petrova
Concluding Remarks
The design of a new networking tutorial suite (named WebLan-Designer)
follows our previous efforts in both a flexible teaching and learning model
(Petrova, 2002) and a tool to enhance teaching and learning (Sarkar, 2004;
Sarkar & Lian, 2003). WebLan-Designer is a Web-based interactive tool for
teaching and learning LAN design. The tool can be used either in the classroom
to enhance the lecture environment or at home (i.e., off campus) as an aid to
enhance learning various aspects of computer networking and LAN design
(Reinig & The, 1998). Objectifying network topology concepts is one of the
aspects of the constructivist approach towards teaching computer networking.
As WebLan-Designer provides both visual and animated representations, it
supports constructivist pedagogical approaches and can improve students’
participation in flexible learning activities (Chen, 2003). The flexibility in
modelling LAN design enhances learning as it introduces variation — an
experience stimulating the understanding of the concept under investigation
(Berglund, 2003). Both flexibility and variation provide opportunities for students
to build and refine their own knowledge, which they can apply further to solve
Table 3. Evaluation by peers
Positive
… I like the network designer part especially (i.e., the physical star logical bus, etc.).
… Web-based questions and answers are useful for students. I have experienced that students like to use
these for self-review. The different scenarios are useful for students to see and analyze different network
configurations.
… Easy-to-use tutorial and good interface, helpful for learners especially to review and test their
knowledge on wireless LAN, useful Links is a very good idea, especially for students who would like to
explore and learn more.
… A very useful resource … good for learning. (2)
… Interested to use WebLan-Designer … in class. (2)
Critique
… A link from task 5: wireless Design Exercises to Scenarios/Exercises required.
… Some spelling mistakes in the quiz texts.
… A couple of [typographical] errors in your LAN test … [suggested corrections].
… The modeller part may help the visualization of the different network layouts but may also convey an
oversimplified idea of network design.
Recommendations
… More navigation links might make the tutorial easier to navigate and use; for example, after completing
the quiz, there is a link to reattempt the quiz. Similarly links to other parts of the Designer such as tutorial
might make it more navigable.
… There can be more user-friendly feedback and interaction features added.
… It would be helpful to have some graphic-related questions too (i.e., a picture of a network and a
multiple-choice question set about what it is called, etc.). It looks good for the students for revision
especially.
… A usability testing may also be done.

WebLan-Designer 33
problems and develop deeper understanding of properties and relationships — a
necessary component of self-learning (Shifroni & Ginat, 1997).
Compared to the traditional method of classroom teaching of computer network-
ing, WebLan-Designer provides students a different way of learning more LAN
design concepts (e.g., modelling component of the tool). The mixed (and often
very minimal) level of prior student knowledge, recognised by R. K. C. Chang
(2004) as one of the challenges in teaching computer networks, is addressed by
the inbuilt flexibility. More experienced students can go through quizzes and
scenario-based LAN design. Students exposed to networking for the first time
can do a walk-through and learn about computer networks. Finally, learning is
further enhanced by multi-coverage of the content (e.g., quiz, key terms, and
review questions have many commonalities) and making the concepts interesting
and engaging (e.g., when working with the scenarios). Students are given the
opportunity to identify their misconceptions and reconstruct their knowledge,
which helps them internalise, rather then absorb, the basic ideas and concepts
(Chen, 2003).
The tool has some limitations. Currently, WebLan-Designer displays LAN
diagrams with up to 20 workstations, four file servers, and four printers. The
software can easily be upgraded to accommodate any number of components.
The incorporation of wireless personal area networks (Bluetooth technology) is
also suggested for future work. Other developments might include expanding the
scope of the tool to include interactive content at the higher layers of the TCP/
IP protocol stack, such as NAT translation and IP subnetwork modelling.
WebLan-Designer is available at no cost to faculty interested in using it to
supplement their teaching. More information about WebLan-Designer can be
obtained by contacting the first author or through the WebLan-Designer Web
site at http://elena.aut.ac.nz/homepages/weblandesigner/.
Acknowledgments
This work was supported in part by AUT’s RELT Contestable Grant (Grant No.
CJ9987105000, 2004). An earlier version of this chapter appears as: Sarkar, N.,
& Petrova, K. (2005, June). WebLan-Designer: A Web-based system for
interactive teaching and learning LAN design. Proceedings of the 3rd Inter-
national Conference on Information Technology: Research and Education
(ITRE 2005).

34 Sarkar & Petrova
Summary
Interactive teaching and learning by using software tools is an attractive solution
to motivate students to learn a rather technical and dry subject such as LAN
design. This chapter described a Web-based tool called WebLan-Designer that
gives students an interactive and flexible learning experience in both wired and
wireless LAN design. Both teacher and students can benefit from the use of
WebLan-Designer in different teaching and learning contexts. A teacher is able
to use it in the classroom as a demonstration, to liven up the traditional lecture.
Students, on the other hand, can use the system in achieving the following
learning outcomes: (1) complete tutorials on both wired and wireless LAN
design; (2) test prior knowledge on networking through interactive quizzes; (3)
verify the solution to in-class tasks and exercises through LAN modelling; and
(4) learn more about scenario-based LAN design. In addition to enhancing face-
to-face teaching by including an element of online learning in the classroom,
WebLan-Designer provides online support for off-campus students and facili-
tates learning through flexible course delivery. The effectiveness of WebLan-
Designer as an aid to teaching and learning LAN design has been evaluated both
by students and teaching team.
Access point (AP): AP stands for access point. Typically, infrastructure-based
wireless networks provide access to the wired backbone network via an
AP. The AP may act as a repeater, bridge, router, or even gateway to
regenerate, forward, filter, or translate messages. All communication
between mobile devices has to take place via the AP.
Ad hoc network: A class of wireless network architecture in which there is no
fixed infrastructure or wireless access points. In ad hoc networks, each
mobile station acts as a router to communicate with other stations. Such a
network can exist on a temporary basis to share some resources among the
mobile stations.
Constructivism: A theory of learning which regards learning as a process of
developing knowledge through the construction and reconstruction of
concepts and ideas, providing learners with motivation, and supporting self-
directed learning. It suggests that learners are particularly likely to make
new ideas when they are actively engaged in making some type of external
artifact, which they can reflect upon and share with others (http://
mia.openworldlearning.org/constructivism.htm).

WebLan-Designer 35
Experiential learning: A process through which a learner constructs knowl-
edge, skill, and value based on direct experiences. Engage students in
critical thinking, problem solving, and decision making in contexts that are
personally relevant and connected to academic learning objectives by
incorporating active learning. This approach requires the making of oppor-
tunities for debriefing and consolidation of ideas and skills through reflec-
tion, feedback, and application of the ideas and skills to new situations
(http://www.stolaf.edu/services/cel/definition.html).
GUI: GUI stands for graphical user interface. Most of the modern operating
systems provide a GUI, which enables a user to use a pointing device, such
as a computer mouse, to provide the computer with information about the
user’s intentions.
IEEE 802.11b/a/g: Generally refers to wireless LAN standards. The IEEE
802.11b is the wireless LAN standard with a maximum bandwidth of 11
Mbps operating at 2.4 GHz. The IEEE 802.11a is the high-speed wireless
LAN with a maximum bandwidth of 54 Mbps operating at 5 GHz. The IEEE
802.11g is backward compatible with the IEEE 802.11b, with a maximum
bandwidth of 54 Mbps operating at 2.4 GHz.
Infrastructure network: A class of wireless network architecture in which
mobile stations communicate with each other via access points, which are
usually linked to a wired backbone. Such a network has a fixed infrastruc-
ture and a centralized control.
MySQL: An open source relational database tool which is used for Web
development (often used in conjunction with PHP).
NAT: Stands for Network Address Translation; a process of converting internal
IP addresses to external ones and vice versa, establishing a sort of a
“firewall” between a LAN and the rest of the network.
PHP: “Hypertext Preprocessor”; a general-purpose scripting language which
can be embedded in HTML, widely used for Web development. It is
compatible with a variety of database management systems.
TCP/IP: The family of protocols used for Internet communication.
Wired LAN: This term refers to a LAN which uses cable media (e.g., UTP Cat
5e) for LAN connectivity and typically covers a limited area, such as a
room, a building, or a campus.
Wireless LAN: This term refers to a LAN which uses infrared or radio
frequencies rather than physical cable as the transmission medium.

36 Sarkar & Petrova
Review Questions
1. List and describe the main features of WebLan-Designer.
2. Discuss the difference between an ad hoc and an infrastructure wireless
LAN.
3. State two advantages and two disadvantages of wireless LAN over wired
LAN.
4. State two advantages and two disadvantages of wired LAN over wireless
LAN.
5. Define the following key terms: ad hoc network, access point, infrastruc-
ture network, and wireless LAN.
6. Explain how WebLan-Designer can be used in the classroom as an aid to
enhance teaching and learning LAN design.
7. Explain how WebLan-Designer can be used for class demonstration.
8. Explain how WebLan-Designer can be used to verify the solutions to LAN
design exercises.
9. List and describe possible enhancements to WebLan-Designer.
References
Bachmann, D. W., Segal, M. E., Srinivasan, M. M., & Teorey, T. J. (1991).
NetMod: A design tool for large-scale heterogeneous campus networks.
IEEE Journal on Selected Areas in Communications, 9(1), 15-24.
Berglund, A. (2003, November). What is good teaching of computer networks?
Proceedings of the 33rd
ASEE/IEEE Frontiers in Education Confer-
ence, Boulder, CO (pp. S2D13-S2D19).
Bhunia, C., Giri, S., Kar, S., Haldar, S., & Purkait, P. (2004). A low-cost PC-
based virtual oscilloscope. IEEE Transactions on Education, 47(2), 295-
299.
Bing, B. (2002). Wireless local area networks: The new wireless revolution.
New York: Wiley.
Chang, R. K. C. (2004, June). Teaching computer networking with the help of
personal computer networks. Proceedings of the 9th annual SIGCSE

WebLan-Designer 37
conference on Innovation and Technology in Computer Science
Education (ITiCSE), Leeds, UK (pp. 208-212).
Chang, X. (1999). Network simulations with Opnet. Proceedings of the 1999
Winter Simulation Conference: Simulation - A Bridge to the Future (pp.
307-314).
Chen, C. (2003). A constructivist approach to teaching: Implications in teaching
computer networking. Information. Technology. Learning and Perfor-
mance Journal, 21(2), 17-27.
Diab, H. B., & Tabbara, H. S. (1995). An educational tool for computer
networks. Australasian Journal of Engineering Education, 6(1).
Dornan, A. (2002). The essential guide to wireless communications applica-
tions: From cellular systems to Wi-Fi (2nd ed.). Prentice Hall.
Garcia, J., & Alesanco, A. (2004). Web-Based system for managing a telematics
laboratory network. IEEE Transactions on Education, 47(2), 284-294.
203.
Hong, J. W.-K., Kwon, S.-S., & Kim, J.-Y. (1999). WebTrafMon: Web-based
Internet/intranet network traffic monitoring and analysis system. Com-
puter Communications, 22(14), 1333-1342.
Kofke, D. A., & Mihalick, B. C. (2002). Web-based technologies for teaching
and using molecular simulation. Fluid Phase Equilibria, 194-197, 327-
335.
Kolb, A., & Kolb, D. A. (2004). Learning styles and learning spaces:
Enhancing the experimental learning in higher education. Retrieved
April 23, 2005, from http://www.learningfromexperience.com/images/up-
loads/Learning-styles-and-learning-spaces.pdf
Kolb, D. A., Boyatzis, R., & Mainemelis, C. (2000). Experimental learning
theory: Previous research and new directions. In R. J. Sternberg & L. F.
Zhang (Eds.), Perspectives on cognitive, learning, and thinking styles.
NJ: Lawrence Erlbaum.
McDonald, C. (2004). The cnet network simulator (v2.0.9). Retrieved January
5, 2006, from http://www.csse.uwa.edu.au/cnet/
Nieuwelaar, M. van den, & Hunt, R. (2004). Real-time carrier network traffic
measurement, visualisation and topology modelling. Computer Communi-
cations, 27, 128-140.

38 Sarkar & Petrova
Palmer, M., & Sinclair, R. B. (2003). Guide to designing and implementing
local and wide area networks (2nd
ed.). Canada: Course Technology.
Petrova, K. (2002, December 3-6). The quest for the best mix: An ongoing
project in e-learning. Proceedings of the International Conference on
Computers in Education (ICCE) (pp. 227-228).
Reinig, B., & The, J. (1998). Supporting higher education with the World Wide
Web. Journal of Computer Information Systems, 39(1), 76-83.
Resnick, M. (2002). Rethinking learning in the digital age. In G. Kirkman, J. D.
Sacns, K. Schwab, & P. Cornelius (Eds.), The global information
technology report 2001-2002: Readiness for the networked world (pp.
31-37). Center for International Development, Harvard University.
Rokou, F. P., Rokos, Y., & Rokou, E. (2003, July). InfoLab: A Web learning
pedagogical based content repurposing approach. Proceedings of the 3rd
IEEE International Conference on Advanced Learning Technologies
(ICALT’03), Athens, Greece (pp. 150-154).
Sanchez, M., & Manzoni, P. (2001). ANEJOS: A Java based simulator for ad
hoc networks. Future Generation Computer Systems, 17, 573-583.
Sarkar, N. I. (2004, August/September). WLAN-Designer: A Web-based
software tool to enhance learning and teaching wireless LAN design.
Proceedings of the 4th IEEE International Conference on Advanced
Learning Technologies, Joensuu, Finland (pp. 260-261).
Sarkar, N. I., & Lian, J. H. (2003, July). LAN-Designer: A software tool for
teaching and learning LAN design. Proceedings of the 3rd IEEE Inter-
national Conference on Advanced Learning Technologies, Athens,
Greece (pp. 624-628).
Shifroni, E., & Ginat, D. (1997). Simulation game for teaching communications
protocols. ACM SIGCSE Bulletin. Proceedings of the28th SIGCSE
Technical Symposium on Computer Science Education, 29(1), 184-188.
Sitthiworachart, J., & Joy, M. (2003, July). Web-based peer assessment in
learning computer programming. Proceedings of the 3rd IEEE Interna-
tional Conference on Advanced Learning Technologies (ICALT’03),
Athens, Greece (pp. 180-184).
Zheng, P., & Ni, L. M. (2003). EMPOWER: A network emulator for wireline
and wireless networks. Proceedings of the 22nd annual Joint Confer-
ence of the IEEE Computer and Communication Societies (INFOCOM)
(pp. 1933-1942).

INetwork 39
ChapterIII
INetwork:
An Interactive
Learning Tool for
Communication Networks
K. Sandrasegaran, The University of Technology Sydney, Australia
M. Trieu, The University of Technology Sydney, Australia
Abstract
A country or a nation would be immobilized without computers and data
communication networks. Computer networking courses are being offered
by not only universities and tertiary institutions but also many technical
colleges and secondary schools worldwide. The cost associated with
purchasing networking devices and equipment to enable students to gain
practical experience in setting up a customised network can be significant.
Therefore, networking fundamentals are taught by combination of textbooks
and lecture-only methods in many schools and publicly funded tertiary
institutions. This chapter describes the development and use of an interactive
learning tool called iNetwork for teaching and learning computer
communication networks. iNetwork provides an environment in which
students can experiment with different network configurations and gain
hands-on learning experience in computer and data communication networks
without the need for expensive equipment.

40 Sandrasegaran & Trieu
Learning Objectives
• List and describe the main features of iNetwork.
• Discuss the usefulness of iNetwork in teaching and learning contexts.
• Explain how iNetwork can be used in the classroom to enhance teaching
and learning various aspects of computer communication networks.
• Define the following key terms: ARP, DHCP, DNS, firewall, OSPF, RIP,
TCP/IP, and VPN.
• Suggest further enhancements to iNetwork.
Introduction
Communication networks form an important part of business and society today.
As the Internet has continued to expand, so has the demand for education in
networking. Traditionally providers of networking subjects and courses were
limited to universities and technical colleges. At present, IT and networking
subjects are being introduced into most high schools. The cost involved with
providing every student with the equipment necessary to set up a practical
network is significant, particularly for schools and publicly funded tertiary
institutions, and consequently most networking concepts are taught using a
combination of standard textbook- and lecture-based approaches and limited
laboratories on small networks.
In this chapter, we present a solution to the above-mentioned resource and cost
problem which aims at improving the way networking is commonly taught. Our
solution will allow users to gain authentic practice in experimenting with different
network configurations without the cost of providing each student with their own
networking equipment. The chapter reports on the requirements, development,
and evaluation of an interactive learning tool called iNetwork, which allows users
to assemble and simulate custom networks composed of commonly used
networking devices. iNetwork lets students simulate the running of these
custom-built networks, identify problems, and learn more about communication
networks.
In the development of iNetwork, a packet-capturing software was used to
monitor the behaviour of an experimental network. The data thus obtained was
integrated into this tool so that it could simulate the real-life behaviour of a

INetwork 41
network. The iNetwork Software allows users to configure real-life networks as
the software emulates configuration settings (e.g., IP addresses and routing
tables) obtained from commercial network equipment. The iNetwork Software
was evaluated by a number of undergraduate engineering students through a
survey. The results of the survey are presented at the end of the chapter. This
is followed by a conclusion and future work.
In general, the motivation for building an interactive learning tool is to improve
the quality of education by supplementing the work done in the classroom with
appropriate and realistic laboratory or practical work. The basis for the use of
computers as an educational tool is well supported by evidence from researchers
in the educational field. Bloom (1984) reports that conventional teaching, that is,
teacher in front of 20 to 200 students, provides one of the least effective methods
for educational delivery, and one-to-one tutoring is far superior to conventional
teaching and is the most effective educational delivery method. Studies on human
retention conclude that instructional environments that use several human senses
result in better retention: On average people retain 25% of what they hear; 45%
of what they hear and see; and 70% of what they hear, see, and do (Edwards,
1985). A computer equipped with the appropriate hardware and software
provides an excellent medium to invoke visual, auditory, and tactile senses.
Edwards reports that information is better retained if a student is an active
participant rather than a passive absorber during the learning phase.
Interactive learning environments (ILEs) provide an opportunity for students to
do tasks relevant to information gathered in the classroom. A student’s attention
is heightened by the interactivity of the system. The availability of the tool at all
times of the day coupled with the fact that the tool can be used without constant
human supervision is an added bonus to the student. Furthermore, the fact that
the pace of learning is controlled by the student will assist learning. Interactive
learning environments provide a protected environment where students can
explore and perform actions without the fear of real-life consequences, such as
damaging costly equipment, components, and so forth. Another possible use is
for simulation of fault scenarios that are difficult to observe due to infrequent
occurrence, thus preparing the student to handle such situations in real life.
Training should be possible in remote areas where expertise or equipment may
not be readily available, thus promoting distant learning.
A number of ILEs have been successfully trialled in the field. One example of
this is the system known as Sherlock, which was developed to teach air-force
trainees the skills of electronic troubleshooting. It has been reported that trainees

using the Sherlock tutor for 20 to 25 hours gained proficiency equivalent to that
of trainees with four years’ on-the-job experience (Lesgold, Lajoie, Bunzo, &
Eggan, 1992). Another ILE to be reportedly successfully trialled in the field is the
LISP tutor (Anderson, 1990), which provided students with programming
exercises and tutorial assistance. The times to complete identical exercises
under various tutoring strategies were 11.4 hours (human one-to-one tutored),
15.0 hours (LISP tutored), and 26.5 hours (conventional teaching). These
successes provide some of the motivation for this work on developing an
interactive learning tool for communication networks.
A small number of proprietary tools that serve a similar purpose as the iNetwork
Software currently exist. The main problem with these proprietary tools is that
they heavily specialise in certain market products, protocols, and operating
systems.Forexample,RouterSim(http://www.routersim.com)andBosonNetSim
(http://www.boson.com/netsim) focus much on configuring Cisco routers and
switches using Cisco’s proprietary operating system. Due to these reasons,
these tools have become inappropriate learning tools for students undertaking
fundamental networking subjects.
Description of the System
The iNetwork Software is an interactive learning tool that focuses mainly on
general data communication networks. It aims at teaching anyone the fundamen-
tals of communication networks and internetworking and was built based on a
number of features that have made RouterSim’s Network Visualizer very
popular. Such features include operating system emulation and user-friendly
interface. The software was developed based on principles of network operation
that were covered in a Communication Network Subject (Sandrasegaran, 2003)
and other resources (Davis, n.d.; Lavigne, 2001; Network Sorcery, n.d.;
Stallings, 2000).
iNetwork allows users to assemble or build custom networks using common
networking devices, including workstations, switches, routers, domain name
system (DNS) servers, and Dynamic Host Configuration Protocol (DHCP)
servers. The tool allows users to simulate communication between devices,
allowing users to identify and troubleshoot problems in their custom-built
networks. Users can develop a better understanding of the workings of a
communication network by simulating communication between networking
devices.

INetwork 43
Software Requirements
The iNetwork Software was designed to satisfy the following requirements:
Graphical User Interface Requirements
• The iNetwork Software interface shall be graphical and easy to use.
• It will allow for drag and drop functionality when assembling a network so
to allow users the ability to build networks.
• The GUI should contain drop-down menus or icons containing fundamental
networking devices, such as workstations, switches, routers, and so forth.
• It should allow the properties of network elements to be specified by left-
clicking on the network objects on the GUI.
• It will allow users to save and load custom-built networks for future use.
Networking Requirements
• The networking devices will include workstations, switches, routers, serv-
ers, and cables. More sophisticated networking components, such as
firewalls and coaxial cables, will be implemented in the future releases of
iNetwork.
• The workstation device will act as a simple computer. For the first release
of iNetwork, it was decided that the majority of emulation of networking
elements will be performed using these workstations.
• The server device will be an extension of a workstation but with additional
services such as DNS service and DHCP services.
• For iNetwork Release 1, the switch device will have up to four ports to allow
a maximum of four network elements to be attached to it.
• The router device will have up to three network interfaces to allow for
communication between three different networks in Release 1.
• The router device shall allow for static routing. Features such as adding
routes, deleting routes, and modifying routes should be available.
• The router device shall allow dynamic routing. The software shall emulate
dynamic routing protocols such as RIP, OSPF, or both.
• The functions of the networking devices should mimic real-life networking
devices as closely as possible. For example, all networking interfaces
should have a MAC address, switches should have a MAC-interface
memory table, and so on.

• The workstations and servers should adopt common TCP/IP properties,
similar to the ones found in Microsoft Windows. The routers shall also adopt
a similar setting for each of its network interfaces.
• The DHCP server should allow for IP addresses, gateway addresses, and
DNS addresses to be leased. Another important requirement is to display
an address lease table showing leased addresses.
• The DNS server should allow for mapping of IP addresses to hostnames
and vice versa. There should be options to add, change, and remove DNS
entries.
• The software should emulate configuration settings obtained from real-life
commercial network equipment, giving users exposure to the set of
parameters that requires configuring in real-life networks; for example,
subnet mask, gateway, and DNS servers.
• The interface to configuring the configuration setting the TCP/IP proper-
ties on the software should be similar to ones found on a Microsoft
Windows operating system.
Simulation Requirements
• If required, it should provide users with an output to track events that occur
during simulation when users invoke a command; for example, output
showing important packet header information that is sent during DNS
resolution.
• It should allow users to test their custom-built networks using DOS/UNIX
utilities, such as ping, tracert, route, arp, and ipconfig.
• The ipconfig command shall display appropriate settings of components.
The layout of output shall be similar to the ipconfig command under DOS.
• The route command shall display the routing tables of the workstation or
server. The layout of output shall be similar to the route command under
DOS.
• The ping simulation shall have similar output to DOS pings upon successful
and unsuccessful pings.
• The tracert simulation shall display the list of intermediate network nodes
required to reach the destination from the source. The layout of output shall
be similar to the tracert command under DOS.
• The ARP simulation shall allow for adding of IP-MAC addresses, removal
of IP-MAC mappings, flushing of ARP cache, and displaying of ARP
cache. The layout of output shall be similar to the ARP command under
DOS.

INetwork 45
Software Architecture
The iNetwork tool is written in C# using Microsoft Visual Student .NET 2003.
To run the software, a computer loaded with Windows 2000/XP, Microsoft .NET
framework, and the iNetwork executable is required. The top-level architecture
of the iNetwork Software is shown in Figure 1. There are four important
components, namely, the graphical user interface (GUI), the device simulator,
the network simulator, and the network calculator.
The iNetwork core components perform the following functions:
• The GUI component allows user interaction with iNetwork. It allows users
to build their own networks by adding, removing, and configuring the
properties of networking devices.
• The network simulator (or emulator) component emulates common net-
working utilities such as ipconfig, ping, tracert, and arp.
• The device simulator component emulates a variety of real-life networking
devices such as switches, routers, workstations, servers, and so forth.
• The network calculator component performs mathematical and logical
calculations. These include calculating network ID, determining if an
address is within the correct subnet, calculating appropriate destination
routes, checking ARP tables, and so on.
During the development phase of the software, a prototype was built. Feedback
from the iNetwork Software prototype indicated that the user interface was of
considerable importance as an interactive learning tool. As seen in Figure 2, the
iNetwork GUI is tidy, consistent, informative, and appealing.
Figure 1. Core components of iNetwork
User
iNetwork
Network
Simulator
Network
Calculator
GUI
Device
Simulator

Usefulness and Benefits of the System
The iNetwork Software eliminates the cost associated with purchasing, setting
up, and maintaining hardware and software required to provide users with
practical experience in computer networking. It provides an environment that is
available to students at all times. Students can explore networking without the
fear of disturbing a live network. Another benefit is the ability to teach
networking concepts more effectively because the students are engaging with
the concepts on an interactive and explorative basis.
The software is capable of simulating many hardware devices, allowing users to
build fairly complex networks all on a single computer. The software can be
upgraded to cover other important aspects of communication networks such as
network security. The upgrades could include adding additional networking
components such as firewalls and wireless access points.
Lecturers and trainers can design laboratory exercises for students and allow
them to work through the exercises either in class or from home without
supervision. This provides students with the opportunity to learn at their own
pace. Distance learning of networking should be possible in remote areas where
expertise or equipment may not be readily available.
The iNetwork Software provides an environment in which students can practice
or perform tasks relevant to information gathered in the lectures or laboratory.
Figure 2. iNetwork Software interface

INetwork 47
Some of the features of this tool — for example, capturing and viewing the
contents of packets, flushing the contents of memory — are beneficial for a
detailed understanding of network operation.
Typical Laboratory Exercise
To demonstrate the usefulness of the software, a typical laboratory exercise
performed by an iNetwork user is described below.
Step 1
Double Click on iNetSim.exe to start the interactive learning tool. Note that the
application has a toolbar with buttons to save, open, and print your network
schematics. The white surface underneath the toolbar is your workspace and will
be used to build your network.
Step 2
If you right click anywhere within the white workspace, a menu will appear with
a list of networking devices similar to the one shown in Figure 3.
Step 3
Add six workstations and two switches onto the workspace. To move the device,
left click on a device and hold the mouse button down. Move the networking
devices to a suitable location as shown in Figure 4.
Step 4
Right click on the top left workstation and a menu will appear as shown in
Figure 5.
Figure 3. List of networking devices
Add Workstation
Add DHCP Server
Add DNS Server
Add Switch
Add Router

Step 5
Select Connect with Cable, and draw a cable to the switch. When both the switch
and workstation are highlighted in green, right click for the cable to be drawn as
shown in Figure 6.
Step 6
Continue to draw all the remaining cables as shown in Figure 8.
Step 7
Right click on a workstation and select Configure IP. A window will pop up,
allowing users to enter an IP address for the workstation. Provide the worksta-
tion with the addresses as shown in Figure 9, and then click on OK.
Figure 4. Device layout
Figure 5. Workstation menu

INetwork 49
Figure 6. Connecting device with cable
Figure 7. Connecting device with cable
Figure 8. Connecting networks
Switch 0

Step 8
Configure another workstation with an IP address of 192.168.1.20 and a subnet
mask of 255.255.255.0.
Step 9
Right click on the workstation that was given the IP address of 192.168.1.10 and
select Command Prompt. Type “ipconfig” and press Enter; the output should be
as shown in Figure 10.
Step 10
Type “ping 192.168.1.20” and press Enter; if everything was set up correctly, the
output should be as shown in Figure 11.
Note that the output of the ping command in the iNetwork Software is similar to
the output found on Windows XP, if the same command were entered on a
Windows XP workstation. This allows students to familiarise themselves with
the outputs received from commercial operating systems.
Step 11
Close the Command Prompt by typing “exit.”
Figure 9. Connecting networks

INetwork 51
Step 12
Click on the Activity icon on the toolbar and an Activity Log window will appear
as shown in Figure 12. The activity log provides detailed information on activities
occurring during the simulation process. Step through the activities to trace
exactly what was going on for the successful ping to occur.
Another possible use is simulation of network fault scenarios that rarely occur
in real-life troubleshooting, thus preparing the student to handle such situations
in real life. A typical example would be to provide students with the network
shown in Figure 13. We can purposely introduce an error in the network by
Figure 10. Command Prompt
Figure 11. Successful ping

providing an incorrect DNS server address to pc2. We can then get students to
determine why pc1 is able to ping the DNS server as shown in Figure 14, whereas
pc2 is experiencing a problem as shown in Figure 15. Students can then perform
a combination of tasks that includes running ipconfig to check the IP configura-
tions, inspecting the DNS hostname mappings, pinging the DNS server using its
IP address, or tracing through the activity logs to understand the DNS commu-
nication process. Students should then be able to isolate the problem and apply
a suitable fix to resolve the problem.
Complex Scenario
A more complex scenario is shown in Figure 16. In this scenario, we might have
a router with some missing routes in its routing table. Students may be asked to
determine why pc1 can communicate with pc2 and pc3, whereas pc2 can only
communicate with pc1. Students can then run a variety of tests on the network,
Figure 12. Activity Log

INetwork 53
Figure 13. Simple network with a name resolution problem
Figure 14. PC1 is able to ping DNS server
dns-server
pc1 pc2

either using the ping or tracert utilities. As shown in Figure 17, students may then
experiment with adding and removing routes in a router’s routing table in an
attempt to find a solution to the problem. Additional follow-up exercises where
students are asked to fix the problem using dynamic routing (RIP) will only
further strengthen their understanding of routing.
Experimental Investigation
To ensure that the iNetwork Software performs accurate simulation, a real
(physical) experimental local area network was set up as shown in Figure 18. The
experimental local area network consisted of a switch and three workstations,
Figure 15. PC2 is unable to ping DNS server
Figure 16. A network with routing problems
pc2
pc1
pc3
router1
router2
router3

INetwork 55
Figure 17. Adding routes to a router’s routing table
Figure 18. Experimental laboratory configuration used to retrieve TCP/IP
simulation data for the iNetwork Software

with one workstation also acting as a router. This configuration was sufficient
to capture most TCP/IP data traffic that will flow in a real network.
Different types of network traffic were generated in this experimental network,
including ARP request, ARP Reply, ICMP Request (Ping), ICMP Reply (Ping),
ICMP Request (Tracert), ICMP Reply (Tracert), DNS Query, DNS Response,
DHCP Discover Message, DHCP Offer, DHCP Request, DHCP ACK, and
RIP v1 Response traffic. Network behaviour data was captured through the use
of Ethereal, which is a freely available packet capturing software. The results
from Ethereal were documented and analysed carefully. The results of the
analysis have been used to design the simulation components of the iNetwork
Software. This ensures that simulation output from the GUI is accurate and
detailed.
Evaluation and Interpretation
The iNetwork Software was evaluated in June 2004 by 37 undergraduate
engineering students (20 male and 17 female) from the University of Technology
Sydney (UTS) who were undergoing the 48740 Communication Networks
subject. The evaluation survey consisted of several laboratory exercises which
the students were asked to complete. Upon completing the exercises, students
were asked to assess the iNetwork Software based on factors revolving around
functionality and usability. The results of the survey have been statistically
compiled and presented in Figure 19. The survey provides an indication of the
strengths and weaknesses of the iNetwork Software.
Only one student reported that the iNetwork would not be useful as a laboratory
tool for 48740 Communication Networks with the reason being that the student
could not run the iNetwork Software from home using the Linux operating
system. Since a large number of users run Microsoft operating systems, the
results from the surveys proved to be very positive.
Conclusion
In this chapter, a description of the motivation, requirements, design, benefits,
usage, and evaluation of the iNetwork Release1 Software has been presented.
The software requirements analysis, design, and implementation have been
successful. Evaluation of the software by students at UTS was very positive.

INetwork 57
Figure 19. Students’ response to survey
Network device demonstration
0
5
10
15
20
25
Poor Okay Very good
Response
Number
of
responses
User friendliness
0
5
10
15
20
25
30
Poor Okay Very good
Response
Number
of
responses
Time taken to become
familiar with the Tool
0
5
10
15
20
25
30
35
< 1 hour 1-3 hours > 3 hours
Response
Number
of
responses
Effectiveness as an interactive
learning tool
0
5
10
15
20
25
30
Poor Okay Very good
Response
Number
of
responses
Intuitiveness & ease of
learning
0
5
10
15
20
25
30
Poor Okay Very good
Response
Number
of
responses
Simulation capability
0
5
10
15
20
25
Poor Okay Very good
Response
Number
of
responses
Recommended as a
laboratory tool for the subject
communication networks
0
10
20
30
40
Yes No
Response
Number
of
responses
1
1
2
2
3
Number
of
responses
Simulation output
Response
Not
enough
detail
Sufficient Too much
detail
0
5
10
15
20
25
30
35

Evaluation by other groups of students at high schools is also envisaged for the
near future. A number of options are available to further improve the iNetwork
Software and enhance its use as a learning tool. These options include adding
additional networking devices such as firewalls, Web servers, mail servers,
virtual private networks (VPNs), and wireless networks and devices such as
access points and wireless LAN cards. Students who have completed the
evaluation survey have suggested adding animation, improving the simulation
interface, and reducing the occurrences of bugs when running the iNetwork
Software. More complex problem-solving scenarios are planned for the future.
For students to obtain the most educational benefit from the iNetwork Software,
prior knowledge of communication networks is required. The tool is best used as
a supplementary tool to further reinforce and extend students’ understanding of
certain network topics. One of the major problems with the iNetwork Software
is its ability to be upgraded. Due to the existing design adopted, external
developers will find it difficult adding additional network devices to the iNetwork
Software. This problem can be addressed by spending more time redesigning
critical modules in the software.
In light of the survey responses, the iNetwork Software proves to have much
potential. With educational institutions facing economical constraints and bud-
getary cutbacks, the iNetwork Software serves as an ideal solution for not only
preventing the loss or degradation of learning outcomes but also possibly
enhancing students’ learning and understanding of communication networks.
Acknowledgments
Acknowledgments to Anthony Kadi and Keiko Yasukawa for reviewing this
manuscript and the students of 48740 Communication Networks (Autumn 2004)
for taking the survey.
Summary
The computer communication network is an important topic for many computer
networking courses around the globe. Unfortunately, it is difficult to motivate
students to learn computer communication networks because many students

INetwork 59
appear to find the topic technical and rather dry and boring. This chapter
described the development and use of a software tool (called iNetwork) for
teaching and learning communication networks.
Both the teacher and students can benefit for the use of iNetwork in different
teaching and learning contexts. A teacher is able to use it in the classroom as a
demonstration, to liven up the lecture environment. Students, on the other hand,
can use the system in developing a better understanding of the communication
networks. Through experimenting with key parameters, the students gain
insights into the key concepts of communication network design and analysis.
The software has been tested and found to be robust. Student responses to the
survey were mostly favourable. The students indicated that they had found
iNetwork easy to use and helpful in gaining an understanding of communication
networks concepts.
ARP: Address Resolution Protocol is used to translate between IP addresses
and hardware addresses. There is an arp utility found on both Microsoft and
UNIX operating systems which can be used to view and modify the ARP
cache.
DHCP: Dynamic Host Control Protocol is a service used to provide dynamic IP
addresses for client workstations.
DNS: The domain name system is a service used to map between hostnames and
IP addresses and allow for resolution of hostnames to IP addresses.
Firewall: A software application running on a device that is responsible for
filtering incoming and outgoing traffic.
GUI: A graphical user interface is a computer application which interacts with
its users via graphical interface rather than command line instructions.
iNetwork Software: An interactive learning tool that teaches students about
data communication and networking.
OSPF: Open Shortest Path First is a dynamic routing protocol used to update
routing tables in routers using a more sophisticated routing algorithm.
Ping: A network diagnostic tool found on both Microsoft and UNIX operating
systems that is used to show communication successes or failures between
nodes.
RIP: Routing Information Protocol is a dynamic routing protocol used to update
the routing tables in routers.

TCP/IP: Transmission Control Protocol/Internet Protocol is a protocol used to
facilitate communication between computers.
Tracert: A network diagnostic tool found on both Microsoft and UNIX operating
systems. The diagnostic tool is used to track the path of network commu-
nication.
VPN: A virtual private network Is a networking technology that involves
network tunnels being created between nodes within a public network.
Web server: A software application running on a computer that is responsible
for serving Web pages on a network.
Wireless network: A network that is not constrained by cable and relies on
high-frequency radio waves for communication.
Review Questions
1. List and describe three important features of iNetwork.
2. Explain how iNetwork can be used in the laboratory to enhance teaching
and learning computer communication networks.
3. Explain how you would add and remove routes in the router’s routing tables.
4. Explain how iNetwork can be configured to capture data traffic from a
LAN.
5. Define the following key terms: ARP, DHCP, DNS, firewall, OSPF, RIP,
TCP/IP, and VPN.
6. List and describe possible enhancements to iNetwork.
References
Anderson, J. (1990). Diagnostic monitoring of skill and knowledge acquisition.
In N. Fredericksen et al. (Eds.), Analysis of student performance with
LISP Tutor. Hillsdale, NJ: Lawrence Earlbaum.
Bloom, B. S. (1984). The 2 sigma problem: The search for methods of group
instruction as effective as one-to-one tutoring. Educational Researcher,
13, 3-16.
Davis, D. (n.d.). Select the right routing protocol for your network. Re-
trieved May 14, 2004, from http://techrepublic.com.com/5100-6265-
1040261.html

INetwork 61
Edwards, M. (1985). The Mercedes Benz of interactive video. Hardcopy, 14,
74-80.
Lavigne, D. (2001). Examining ICMP packets. Retrieved December 20, 2003,
fromhttp://www.onlamp.com/pub/a/bsd/2001/04/04/FreeBSD_Basics.html
Lesgold, A., Lajoie, S., Bunzo, M., & Eggan, C. (1992). SHERLOCK: A
coached practice environment for an electronics troubleshooting job. In R.
W. Chabay & J. H. Larkin (Eds.), Computer assisted instruction and
intelligent tutoring systems: Establishing communication and collabo-
ration. Hillsdale, NJ: Lawrence Erlbaum.
Network Sorcery. (n.d.). RFC sourcebook. Retrieved February 23, 2004, from
http://www.networksorcery.com/enp/default0602.htm
Sandrasegaran, K. (2003). Supplementary Communication Networks lecture
notes. Sydney, Australia: University of Technology Sydney.
Stallings, W. (2000). Data & computer communications (6th
ed.) NJ: Prentice
Hall.

62 Goldstein, Stark, Leisten, & Tickle
ChapterIV
Effectively Using a
NetworkSimulationTool
toEnhanceStudents’
Understandingof
ComputerNetworking
Concepts
Cecil Goldstein, Queensland University of Technology, Australia
Karen Stark, Queensland University of Technology, Australia
Susanna Leisten, Queensland University of Technology, Australia
Alan Tickle, Queensland University of Technology, Australia
Abstract
This chapter discusses the effective use of a simulation tool in the teaching
of data communication concepts. Because such concepts can be abstract
and therefore difficult to visualise and understand, simulation can help
facilitate learning. In looking to develop a structured approach to optimally
utilising a network simulator in teaching networking concepts, a series of
targeted exercises were developed. These applied the principles of active

Students’ Understanding of Computer Networking Concepts 63
learning to the use of the simulator in practical exercises to encourage
independent and analytical processes and facilitate deeper learning. The
background to this, as well as the design and implementation of the
exercises, is presented. Similarly, the features of an appropriate network
simulator that can be effectively used in this context are discussed, and a
brief overview of the simulation tool used, Packet Tracer, is given. To
illustrate the methodology, examples are provided from the actual exercises
given to students. The system was also evaluated through an experiment
that measured the improvement in understanding of a particular topic,
switched networks, after students participated in a practical on this topic
using the exercises discussed. A clear increase in understanding was
shown. The incorporation of the simulator in developing case studies to
progressively integrate concepts learned as an ongoing, practical exercise
is also presented. In addition, the use of simulation to learn troubleshooting
skills and strategies by employing a simulated network containing
deliberately created errors that need to be resolved is discussed.
Learning Objectives
• Develop exercises using a network simulator to enhance the teaching and
learning of data communications concepts in large classes.
• Apply the principles of active learning in a practical teaching environment.
• Utilise the methods detailed to encourage independent learning of such
concepts as collisions, Internetworking, IP addressing, ping, protocols, and
routing.
• Use the ideas outlined as a basis for innovation in the application of a
simulator in teaching networking.
• Suggest further enhancements to the laboratory activities described in this
chapter.
Introduction
The challenge of teaching data communications in depth to a large cohort of
students is compounded by the fact that the subject material is inherently

intangible, is difficult to visualise, and is conceptually different than what
students are usually familiar with. Data moving across a network and network
processes such as routing cannot readily be “seen.” Similarly, a concept like
protocol layering, which refers to peer protocols when talking of communication
but to a protocol hierarchy when talking of data transfer, can often appear
contradictory until really understood. Unlike, for instance, the study of program-
ming, where many concepts (e.g., conditional loops) are directly paralleled in an
actual language construct and then used in real coding exercises, network
behaviour and ideas cannot be so readily shown. Indeed, because of the
considerable resources required, it is difficult, if not impossible, to expose a large
class of students studying networking even to basic tools such as “sandpit”
networks or some real network devices.
In teaching a second-year subject in Internetworking at the Queensland Univer-
sity of Technology in Brisbane, we have, like others in this area, sought to
overcome these limitations and to enhance the learning experience for our
students by utilising various tools and techniques. These have included simula-
tion, visualisation, animation, demonstration, and use of analogy. While such
methods generally seem to have a positive effect on the teaching environment
and are received favourably by students, two issues have concerned us: whether
there were ways in which we could improve our use of these tools, and whether
such tools actually aided the learning process and led to a deeper understanding.
Since one of the main tools we use in supporting our teaching is a network
simulator, we determined to focus our efforts on developing and evaluating an
approach to using simulation in a structured manner, so as to provide a
framework to facilitate active independent learning. This does not detract from
the use of simulation to demonstrate activities and for stepped, recipe-type
exercises, such as router configuration, but represents a specific effort to use the
simulator to provide a directed, flexible, and engaging environment for the
student to learn independently even when removed from immediate teacher
support.
This chapter will outline the way we designed, structured, and implemented a set
of practical exercises to achieve this purpose, the nature of the simulation tool
we used, and how we evaluated the effectiveness of this approach. We will
further comment on the use of the simulation tool in developing a framework for
an ongoing practical exercise linking material together from week to week and
using the simulator to teach troubleshooting skills. It should also be emphasized
that our approach was geared to working with a large teaching class of 350 to
400 students and that the needs and dynamics are therefore different from
working with a small (10 to 15) group in a workshop or lab environment with
accessibility to actual network equipment.

Understanding networks and how networks operate requires an understanding
of concepts and processes that are both complex and abstruse. The tools that can
be used to demonstrate, simulate, or visualise networks and network behaviours
lend themselves very readily to teaching in this area. Some tools, such as network
or packet analysers, are utilities employed professionally in the industry, and their
very use is in itself is an important skill. Others, such as simulators, are expressly
for the purposes of teaching and learning and are generally used to create a
specific environment which enables the student or trainee to interact as if in the
real situation. In this respect, simulators can mimic reality very closely. A flight
simulator can create an environment so authentic that even sensory stimuli such
as motion, sound, and visuals are evident. Others simply provide a representation
of the reality in a different format, allowing actions to be observed and
demonstrated. For example, a queuing simulator might simply show the behaviour
of a queue as a graph of numbers in a queue against time waited in that queue.
Simulators become more effective when parameters can be changed, randomly
or specifically, to create different scenarios requiring different responses or
reactions from the student. Furthermore, by recording the student’s interaction
their performance can be later analysed and lessons learned.
Network simulators usually enable a network to be designed and built dynami-
cally as a computer-based graphic by placing network devices as icons on a
screen and connecting these devices. This visualisation in itself immediately
makes the material more tangible. A network is then more realistic, even though
it is actually a graphic! It makes it easier to understand the components and
nature of a genuine network, which we can often see parts of (devices,
computers, cabling) but cannot generally observe in its entirety or at its lower
level of operation. The simulated network can be configured by opening
simulated interfaces to the different devices and setting the various parameters
required, such as, for example, network interface addresses and gateway
addresses. The level of configuration and authenticity of the device interfaces
will depend on the sophistication of the simulator. In the simulator we used, it was
possible to configure devices using a simple graphical interface or a console
window that very effectively replicated a subset of IOS (Internetwork Operating
System) commands. This will be discussed in greater detail later in the chapter.
When we initially introduced the simulator into practical sessions, the exercises
used were mainly “recipe” based, stepping the students through a series of
configuration exercises to build a network and then testing this by using simulated
“pings.” While students appeared to enjoy doing this, the learning outcomes were
in many cases largely limited to the rote learning of commands. Indeed, the work
of learning theorists such as Biggs (1999), Salomon (2000), and Ehrmann (1995)

indicates that without engaging in sound pedagogical practice, the use of
simulation tools can be limited in their effectiveness. Educators such as Ramsden
(1992), Entwistle (1981), and Biggs distinguish between deep and surface
approaches to learning. Biggs, for example, describes the surface approach to
learning as “an intention to complete a task with the minimum effort.” In contrast,
the deep approach to learning “arises from a felt need to engage the task
appropriately and meaningfully” (Biggs, p. 16). Deep learning approaches have
been “consistently associated with the types of quality outcomes appropriate for
higher education” (Cope, 2003, p. 135).
Just performing tasks in a simulation exercise, while appearing to impart a good
understanding, is surface learning and generally does not provide the student with
a deep understanding of the issue. Indeed, student performance over a number
of semesters showed no marked difference in understanding between the
semesters when the simulator was used and earlier semesters when it was not.
The use of the simulator did however appear to add to students’ enjoyment of the
classes and did improve their skills in actually interacting and configuring devices
such as routers and switches. The question then asked was, could surface
learning be reduced and deep learning increased, particularly when students are
working independently, and could we develop a framework, using the simulation
tool to effectively implement this?
“It’s not just the tool, but the educational rationale that counts” (Salomon, 2000).
Salomon believes that the assumption that a tool alone can achieve optimum
learning outcomes is misdirected. He states: “Whether information is turned into
meaningful knowledge or stays as a collection of scattered bits and pieces, like
an assortment of screws and nails in a shoe box, greatly depends on numerous
factors, and technology plays but a minor role among them.” It is essential to
consider the specific learning objective when deciding how a tool should be used.
Perkins and Salomon (1992) distinguish between near transfer (to closely related
contexts and performances) and far transfer (to rather different contexts and
performances). If the objective is to train a student in the operation of a device,
this is near transfer and the approach might be to include a series of repetitive
tasks. However, if the objective is far transfer, as it is in our case, then we need
to involve the student in “deliberate effortful abstraction and a search for
connections” (Perkins & Salomon, p. 2). In considering the pedagogical ap-
proach to address this, we felt that the methods suggested in the application of
active learning could be incorporated to achieve our objective.
Active learning can be seen as “instructional activities involving students in doing
things and thinking about what they are doing” (Bonwell & Eison, 1991). Bonwell
and Eison explain that a framework that promotes active learning should include
higher-order thinking tasks such as problem solving, analysis, synthesis, and
evaluation. Such a framework challenges the student and encourages deeper
understanding. Our objective was to design practical exercises that used the

simulation tool for active learning and so facilitated a deeper understanding of
network concepts.
There appears to be very little literature that specifically seeks to evaluate the
effectiveness of using simulation tools. In the teaching of ICT (information and
communication technology), it seems that formal evaluation of the effectiveness
of teaching tools is often neglected. A literature survey of methods used to
evaluate innovations in computer science teaching showed that “the teacher’s
own impression of the teaching and the students’ comments is the most common
way of evaluating novelties in teaching” (Carbone & Kaasbøll, 1998). In our
literature survey of the area of data networking, only two papers, Cameron
(2003) and Yaverbaum and Nadarajan (1996), were found which formally
evaluated the teaching innovation they described. We determined that formal
evaluation of the effectiveness of the simulation tool was integral to its use and
that we would attempt to actually measure whether any improvement in
understanding occurred.
The main emphasis of this system is to use the simulation tool as a framework
to facilitate and engage the student in active learning. The practical session is
therefore structured to promote active learning by progressively leading the
student through the concepts incrementally while challenging them to synthesise,
interpolate, and apply their evolving knowledge. As part of this process, students
need to be able to assess their answers, receive feedback, and correct any
misconceptions before progressing further. For this, the simulator must have
functionality that not only allows the student to create, visualise, configure, and
manipulate their networks but must also provide a framework for the student to
be able to assess their progress through self-evaluation and feedback mecha-
nisms.
While any simulator with suitable features could be used, the simulation tool that
provided the basis for the implementation in this discussion is Packet Tracer, a
network simulator developed by Cisco Systems. Although Packet Tracer is not
a generally available tool, we were able to use it with permission of QUT’s Cisco
Networking Academy program. Our choice of this product was based on both
its powerful and appropriate features and its availability to us. The suitability of
Packet Tracer for use as an interactive learning system was confirmed by
mapping it against the 14 pedagogical dimensions described by Reeves (2003).
While we found Packet Tracer appropriate for our needs, it is not the intention
of this chapter to evaluate Packet Tracer as a software simulation package or

to compare it to other simulators. Rather, we hope to demonstrate how such a
tool can beused topromoteactivelearning. Any network simulation programthat
can provide similar features could be used.
A key feature of the simulation tool used is that it should be easy to work with
and, if possible, fun to use since students should not be distracted from the
learning objectives by having to contend with a complex system. In other words,
the means should not transcend the ends. Furthermore, the simulator should
accurately and adequately mimic the reality. While, understandably, a simulator
might not be able to include every possible feature available in the actual device,
the subset provided must be sufficient so as to make the interaction meaningful.
In other words, it would be pointless to provide a simulation of IOS without
including commands to configure an interface! Similarly, the operation of the
simulator must be accurate. Again, for example, if a packet is incorrectly routed
to its destination, it would mislead and confuse the students.
Packet Tracer is a powerful, highly visual, but simple-to-use network simulation
application. It enables a simulated network to be built in a topography view (see
Figure 1) by connecting a range of network devices (routers, switches, bridges,
hubs, servers, and PCs) together using a variety of connection media. These
devices can then be appropriately configured. Interfaces can be set and routing
tables can be built. The network created can be extensive or simple, and the
specific functionality of individual devices is also available. For example,
switches can be used to implement virtual local area networks (VLANs).
In simulation mode, Packet Tracer enables data packets to be created and sent
from device to device. The behaviour of the packet and the path it follows are
Figure 1. Topography view of a simulated network

Figure 2. Simulation view (showing failure of data transmission)
Figure 3. Simulation showing packet information and routing table
animated and simulate the way a packet will act in an actual network. Errors in
the network configuration, for example, incorrect routes, will therefore cause a
data transmission to fail, and this is shown in the visualisation (see Figure 2).
Furthermore, at each hop in a transmission, the state of the transmission as well
as the message headers in a packet can be examined. Device information can
also be viewed (see Figure 3). Devices such as routers can even be configured
using IOS commands through a console window (see Figure 4).

This makes it a powerful tool not only for practicing network configuration but
also for investigating network behaviour. By observing the network activity and
then analysing the network and packet status, the cause and effect of a particular
configuration or setting can be identified, confirmed, and understood. This
capability lends itself strongly to the use of Packet Tracer to facilitate active
learning. Laurillard (2002) believes that the ability to offer intrinsic feedback
“forms the core of any understanding of the contribution that ICT can make in
education” (p. 126). We believe that the ability of Packet Tracer to give students
meaningful intrinsic feedback is one of the keys to why this tool effectively
supports independent learning.
Packet Tracer networks, including their configurations, can be saved and stored
as files. Multiple networks can therefore be used. For example, two versions of
the same network can be built and then compared. Similarly, a network can be
modified and extended over a period of time as more and more concepts are
learned. This feature is used to build an integrated, ongoing exercise and will be
elaborated on further in this chapter.
In addition, Packet Tracer allows scenarios to be built and saved. A scenario is
essentially a stored animation within a simulated network that can be run anytime
and be observed. Together with the analytical features within Packet Tracer
already referred to, this feature plays a crucial role in facilitating active learning
since specific actions can be modelled and then analysed.
The concepts or material to be covered in the exercises should be material either
already introduced to the students in another mode, for example, in a lecture, or
Figure 4. Console window allowing router configuration using IOS

ideas that can be extrapolated or evolved from previous knowledge, for example,
troubleshooting. An example of this will be given further in this chapter. If
possible, the topics should be structured so that the fundamental concepts are
initially presented and then used as the basis to incrementally and logically move
to more complex topics. A simulated network is then built that includes
components illustrating the concepts being targeted. Questions that test the
students’ knowledge about these concepts are then designed by referring to the
concept in the context of the simulated network. For example, if considering
routing, the question might ask what path a packet might follow as it is routed
across the network from a particular source to a particular destination.
For each question, a scenario is included which in essence provides an animation
of the activity referred to in the question. In the example above, this animation
would show a packet actually being sent through the path referred to. That is, the
scenario contains the “answer” to the question. So, if the question asked how a
packet would be routed from node A to node B, the corresponding scenario
would actually show this as a simulated packet sent from A to B. While not
directly presenting a solution, the animation would enable the student to
determine what actually happens by observing the action. This would either
confirm their understanding or encourage them to ascertain why their assess-
ment was not correct. To do this they would be able to analyse the action and
infer what should be happening by examining headers, consulting notes, rerun-
ning the action in steps, changing the action and observing differences, and
generally interacting with the resources available. The main thing is that they are
actively seeking the solutions.
Where predefined scenarios are not suitable, students can be asked to modify
their network (this provides practice in network configuration) and then asked
about the effect that these changes will bring. The student can also create a
scenario in the changed network to enable them to test and investigate these
effects. So if, for example, subnets were added to the network, the students
would be able to build a scenario sending a packet to the subnet and examining
how this impacts on the network.
The sequence of the exercises is quite simple but important. Students are asked
to open the simulated network in the simulator, examine the network in its
visualised form first, and then answer the questions about the specific topic. They
are then able to switch to the simulation mode and run the animated scenarios that
relate to each question to confirm and evaluate their responses. If their
assessment is not correct, then, by analysing the scenario and looking at the
device or packet configuration at each step of the process, they are able to learn
what went wrong and why. In this way the simulation provides them with the
framework for analysis, feedback, synthesis, and evaluation. On completion of
the topic, a broader question is presented which leads them to the next topic.
Topics are structured in such a manner that they increase incrementally in

complexity so that questions in later topics require understanding gained in earlier
ones, and this provides a continuous and contextually meaningful environment.
To illustrate this we will look at two exercises taken from a practical given as part
of the normal course work of the unit.
The topic presented in the practical is “switched networks and VLANs (virtual
local area networks).” This topic and the theory behind it were presented in an
earlier lecture. The practical exercises were then based on five concepts taken
from this topic area. The five concepts were: collision domains, broadcast
domains, switching, VLANs, and inter-VLAN communication. For each of the
concepts, a separate Packet Tracer network and configuration were built.
Similarly, for each concept, a series of questions was designed to test under-
standing of that concept (remembering that this had already been introduced in
the lecture). For each question on a concept, a simulated scenario was included
that implemented and demonstrated the situation referred to in the question.
Furthermore the structure of these practical exercises was fairly uniform in
order to encourage students to be methodical in their approach.
Below are the two actual exercises. Images of the visualised networks are also
shown although these would have been viewed by the students directly in Packet
Tracer.
The introduction to the exercises briefly presents the objectives and explains the
processes and rationale involved. It should be remembered that the exercises
were part of the normal program for this unit, so the material had already been
presented in a lecture and the students were familiar with the general conduct
of the practicals and with using Packet Tracer.
The first exercise is straightforward and clearly illustrates the methodology and
use of predefined scenarios. The second exercise is somewhat more complex
and requires that the students modify their networks and then create their own
scenarios to analyse network processes, in this case, inter-VLAN routing.
Students were given detailed information on how to modify their networks. This
was because the objective was to achieve an understanding of the concepts
involved rather than focusing on configuration changes that needed to be made.
Example
Two exercises from the practical on switched networks and VLANs
The objective of this prac is to illustrate the concepts of:

• collisiondomains
• broadcast domains
• switching
• VLANs
• inter-VLAN communication
For each exercise you will be given a Packet Tracer network and be asked to
examine this network and answer questions about it. You will then be able to run
a number of predefined scenarios for the network, observing and analysing the
resultant actions. This will further help you understand your answers and, where
necessary, correct these. In some cases you will be required to modify the
network topography and configuration and then observe the effects of these
changes. The networks are all related to each other, and so you will be able to
see how progressive changes in the network topography and architecture impact
on network behaviour.
In order to derive the most benefit from these exercises, you should do these in
sequence and not jump ahead since subsequent exercises and situations relate
to previous ones.
Setup
Download the following files from the Unit OLT site (Prac Index page) into
a temporary folder on your PC:
PT_exercise1.pkt
PT_exercise2.pkt
PT_exercise3.pkt
Start Packet Tracer
Exercise 1
Open the file PT_exercise1.pkt (see Figure 5) and examine the network shown.
Answer the following questions:
1. If a packet is sent from PC1 to PC4, what path will the packet travel and
why?
2. If a packet is broadcast from PC2, what path will that packet travel and
why?

3. What is the difference between the two actions in 1 and 2 above and why?
What happens to the packet sent?
4. If one packet is sent from PC3 and another from PC5 at the same time, what
will occur and why? (see Figure 6)
Figure 5. Exercise 1, initial network
Figure 6. Scenario for Question 4 showing a collision

Now, go to the simulation screen and run Scenarios 1, 2, and 4 in turn. Each
scenario corresponds to the situation outlined in the previous questions, for
example, Scenario 1 relates to Question 1, but for Question 3, consider both
Scenarios 1 and 2. At the end of each scenario, consider whether the action you
observed agrees with the action you thought would occur. If not, try to determine
what is occurring and where your assessment was wrong. To help, run the
scenarios in step mode and click on the packet at each stage to see what is
happening at each protocol layer at that stage and what the state of the
transmission is. (Remember, clicking on the + next to a layer will expand that
layer and show a detailed explanation of the state for that layer.)
Answer the following question based on your observations from the scenarios
shown:
Question
The above network demonstrates a collision domain. Why is this? In this
instance is there any difference between a collision domain and broadcast
domain?
Exercise 2
Like any other network based on TCP/IP, for communication to occur between
VLANs a router must be introduced to connect the VLANs (networks) together.
Each VLAN must be considered as a separate network (or subnet) with an
appropriate network id, and routing must be implemented to send data from one
VLAN to another.
Refer again to the network in Packet Tracer.
In topology mode now add a router. For clarity, position it at the bottom of the
layout between PC0 and PC5 (see Figure 7).
For the router to connect the VLANs together, each VLAN must be connected
to a separate interface. This can be done by simply connecting two ports on the
switch to two separate interfaces on the router and configuring these ports to be
in VLAN1 and VLAN2. Each VLAN is then configured as a separate network
(or subnet) with its own IP network address, and each interface is given an IP
address appropriate to the VLAN it is on.
Connect the router to the switch. The connection should be between Interface
0 on the router and Port 6 on the switch. Note: Now make another connection.
This connection should be between Interface 1 on the router and Port 7 on the
switch.

Now configure Port 6 on the switch to be in VLAN1 (it should be by default) and
Port 7 to be in VLAN2.
On the router now configure Interface 0 with the IP address 212.1.1.1 and
network mask 255.255.255.0.
Configure Interface 1 with the IP address 212.1.2.1 and network mask
255.255.255.0.
Because VLAN2 now has a different IP network address, the PCs in VLAN2
(PCs 3, 4, 5) must have their IP addresses reconfigured. The easiest way to do
this is to click on each of these PCs in turn and then click on “use DHCP.” Note
that the IP address changes to an address in network 212.1.2.0. Also, the PCs
in VLAN1 must have a default gateway configured as well. Again the easiest
way to do this is to click on these in turn and then click on “use DHCP.” The IP
addresses will change, but these will still be in network 212.1.1.0 and the default
gateway will be configured.
Note: Usually a router will be configured on a single trunk and the
interface for each VLAN configured as a subinterface. Traffic for each
VLAN is then identified through frame tagging. The net result, however, is
the same as the configuration we have implemented.
Figure 7. Modified network for Exercise 2 with the added router, in
simulation mode

Consider the following questions:
1. What will happen when a packet is sent from PC0 to PC2?
Now create a packet to do this and confirm your answer.
2. What path does a packet sent from PC1 to PC5 take to reach its
destination? Explain each stage.
Now create a packet to do this and analyse the path by stepping through this
action and examining the packet state at each stage. If your own conclusions are
different, try to understand what is occurring here by sending and examining
packets sent between PCs on the same VLAN and PCs on different VLANs.
3. What path would a packet broadcast on VLAN2 follow and why?
Now create a broadcast packet (from PC4) to do this and observe what happens
to confirm your answer. Remember to use “expert mode” to create a broadcast
packet.
End Practical Exercises
Continuing Practice
To further utilise the simulation and to enhance deeper learning, an ongoing
exercise was developed as a case study to progressively build an expanding
network. This network was changed and enhanced to reflect the topics,
concepts, and processes that were discussed from week to week. In this way,
new ideas were incorporated into the network in a logical and contextual manner.
There was continuity, and students were led to an understanding of how new
concepts and processes fitted into the network as it grew in complexity. Rather
than focusing on the concepts and processes in isolation, the objective was to
focus on how they were integrated in a network and the function they fulfilled
in that network.
In week 1 the idea of a simple, single segment network was introduced and then
simulated in Packet Tracer. This was used to illustrate the concepts of network
connectivity, direct delivery, and simple addressing. Later, when routing was

covered, the simulated network was changed to include routers and to examine
both static and dynamic routing. Later again, the network changed and grew to
reflect the inclusion of features such as subnetting, switching, and Network
Address Translation (NAT). To provide a context for this expanding network,
a story line was maintained which followed the growth of a fictitious company
as it developed and required changes and more sophisticated functionality from
its network. So, for example, the introduction of subnets was required to enable
the company to build additional networks for new sections and branches, and
new servers had to be added and configured as the company’s range of services
expanded. NAT was introduced when the company required external Internet
access. To the student this made the material more relevant, provided a
meaningful context as well as a sense of achievement as they saw their work
grow.
The features available in Packet Tracer also enable the simulator to be used to
develop troubleshooting skills in students. Students are given simulated networks
with errors in them. They use scenarios to test the network and then, when
problems are found, identify these by analysing the details available from Packet
Tracer about packet headers, state information, IP addresses, and routing tables.
The errors can be corrected within Packet Tracer and immediately checked.
Students can therefore learn how to check their networks, identify which errors
can occur, how these are manifested, and how they can be corrected. For
example, a network can be provided to the students with a number of scenarios
(animations), each of which fail. These scenarios could include: invalid or missing
gateway on a PC, invalid TTL (time-to-live) in a packet, invalid IP address, route
missing, no default route, invalid subnet address or incorrect subnet mask used,
trunking not configured in a switch, VLANs not correctly assigned, incorrect
cabling used, or invalid NAT configuration. Faulty hardware can even be
simulated by leaving a device in the simulation in an off state. Using these
scenarios the students can develop troubleshooting strategies and an understand-
ing of the errors involved. Later in an assessment exercise, students can be
provided with a network with similar errors and be asked to locate, identify, and
correct these using the troubleshooting strategies they had developed.
Usefulness and Benefits
The benefit in using this approach is that students are involved in active learning.
They are required to think deeply about what they are doing and what is
occurring, and as they work through the exercises they get rapid feedback from
the simulator. This enhances the students’ learning experience by providing a

framework for active, independent study. The simulation tool provides a hands-
on, practical environment which engages the student and is more exciting and
real because of the use of relevant visuals and animations. Material can be
placed in a context, continuity can be achieved, and analytical and troubleshoot-
ing skills can be developed. Students seek understanding and explanation through
analysing, synthesising, and extrapolating information and knowledge through
dynamic interaction with the system rather than just being told. Students can
therefore work more effectively and independently. Finally, in terms of data
communication, the system enables concepts and process that are otherwise
esoteric to be made more tangible and accessible and, ultimately, more under-
standable.
Educational technology “if applied without deliberative study of its use in context
and without the evaluation of the technology’s impact on this use … remains a
toy” (Almstrum et al., 1996, p. 201). While it was clear that students enjoyed
using Packet Tracer and found the exercises engaging, we also wanted to
determine whether the use of simulation in such an active learning framework
did indeed improve their understanding of the concepts presented.
Our evaluation strategy was based on the framework developed by Naps et al.
(2002) that considered the relationship between a learner’s form of engagement
with a visualisation and the types of understanding that are affected by that
engagement. The evaluation included a pretest, a posttest, a student background
questionnaire, and learner feedback questions. The pre- and posttests were
isomorphic. The same questions were used in each test but in a different order.
Students attended normal practical sessions, but at the start of the session that
was used to assess the exercises, they were tested to determine their current
understanding of the material by completing a pretest multiple-choice question-
naire. Since Packet Tracer was used as an integral part of all the practical
classes in the subject and students were familiar with its functionality and
operation, there was no need to focus on its operation. After the students
completed the practical exercises as discussed in this chapter, they were given
a posttest similar to the initial pretest. We found that student understanding
appeared to improve considerably following completion of the practical.

Results
Sixty-six students participated in the practical and responded to the pre- and
posttests. Of these, six were excluded from the analysis because of missing data.
The pre- and posttests were marked out of 10. In the pretest the average was
55%. In the posttest this improved to 67%, an average increase of 12% (see
Table 1).
The difference between pre- and posttests was shown to be statistically
significant (see Table 2). We calculated the standardised effect size to be d= 0.63
suggesting that participation in the practical session was a significant factor in
improving the understanding of the concepts presented.
In terms of individual results, 63.3% of the students improved their results in the
posttest, 18.3% showed no change, but 18.3% actually showed deterioration.
The average improvement in marks for those who did improve was 23% while
those did worse went down by an average 15%. There was no clear reason why
some students did not improve their results since this was not confined to any
single identifiable group. Factors such as becoming confused, not being as
familiar with the analytical functionality of Packet Tracer, or simply guessing
might have played a role, and this will require further investigation.
On a question by question basis, overall there was an improvement in the
responses for 8 out of the 10 questions. For one question there was no change,
and for one the results in the posttest were actually worse. This could have been
related to a difficulty in understanding the question. The average improvement
for individual question scores was 12% (see Table 3).
Table 1. Paired-samples statistics
Mean N Std. Deviation Std. Error Mean
Pair 1 POSTOTAL 6.67 60 1.56 .20
PRETOTAL 5.55 60 1.54 .19
Table 2. Paired-samples test
Pair 1 t-value df Sig
Postotal-
Pretotal
4.89 59 <0.01

We collected demographic data from students related to their previous experi-
ence in data communication and IT studies and found that this did not have any
evident impact on how they performed. We did note however that students who
perceived themselves as coping well with studies in the unit as a whole showed
a greater improvement in understanding after doing the exercise.
Conclusion
This chapter focuses on the use of a network simulator to provide a dynamic
framework to facilitate active learning in the study of data communication
concepts. By taking advantage of the visualisation, animation, and feedback
features of the simulator, a set of practical exercises were designed to enable
students to independently examine a series of networking concepts by:
• Reviewing a given network
• Explaining activity on the network
• Confirming their assessment through evaluation, analysis, the synthesis of
previous knowledge and feedback provided by the simulator
The key to success lies in the structured use of the simulation tool based on a
defined pedagogical approach. We do not suggest that simulation cannot
effectively be used in other ways but offer some ideas on how the tool can be
used to enhance the student experience. A marked improvement in student
understanding over the course of the practical session was shown by pre- and
posttesting.
Student response to doing the exercises was very positive. Students remained
engaged during the practical and demonstrated a high level of concentration and
interest. No student left the practical session early. Student feedback questions
Table 3. Individual question response
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Ave
Pre
45 52 36 22 11 47 27 40 30 23 33.3
Post
59 54 33 41 17 52 27 44 53 27 40.7
Diff
14 2 -3 19 6 5 0 4 23 4 7.4
%
23 3 -5 31 10 8 0 6 38 6 12

in the posttest confirmed this positive response. (The majority of students
indicated that they felt that the approach had been effective.) Anecdotally as
well, good feedback was received about the practical and about the use of Packet
Tracer.
Not every topic would lend itself to being presented in exactly the same manner.
However applying sound pedagogical practice to the innovative use of simulation
tools can produce good outcomes and can extend the benefits of these tools.
Furthermore, we have demonstrated how simulation tools can be used to address
the practical needs of large classes or in situations where there are restrictions
in the availability of real equipment.
In future work we will investigate why in some cases student understanding of
the topic seemed to be impeded by participation in the practical session. We
would also like to compare the effectiveness of using simulations to other
teaching methods.
Summary
It is often difficult for students to understand data communications concepts
when in a large class because, without firsthand experiences, students can find
the subject technical and rather dry and boring. This chapter describes the use
of a network simulator in large classroom settings to enhance the teaching and
learning of various aspects of data communication at both the introductory and
advanced levels. By using the visualisation, animation, feedback, and analytical
features of the simulator in an active learning framework, a set of practical
exercises was designed for students to examine and independently explore a
number of key networking concepts. Results were positive and students indi-
cated that they had found the simulation tool very effective and helpful in gaining
an understanding of these concepts.
Broadcast domain: Devices networked together and which will receive a
broadcast packet sent from any of these devices are said to be in a
broadcast domain.
Collision: When two or more packets are simultaneously sent on a common
network medium that only can transmit a single packet at a time. The
packets collide and are corrupted and need to be resent.

Collision domain: A single physical or logical network segment using Ethernet
technology through which collisions will be propagated. Devices in a
collision domain communicate directly with each other and share the
network medium.
Gateway address: Usually the address of the default route to be used to reach
a network that is not specifically known.
Internetwork (or Internet): A network of networks made up of separate
networks connected by devices such as routers. The global Internet is the
definitive example of this.
IP address (Internet address): A network address expressed as a 32-bit
number and usually represented in dotted decimal as four decimal numbers
separated by full stops. Every device connected to an internet, including the
global Internet, has a unique IP address. The IP address identifies the
device and the network that device is on. This form is currently the
standard, but later Internet protocols define addresses in a different format.
Network simulator: A computer program that simulates the layout and
behaviour of a network and enables network activity to be initiated and
observed.
Packet: A generic term used to define a unit of data including routing and other
information that is sent through an internet.
Ping: The name of a utility program used to test availability of a device on an IP
network. It works by sending a small packet to the target device and then
waiting for a response. The term is also now used as a verb meaning to
check if a device is accessible.
Protocols: A set of rules defining the standards for network communication
usually implemented as a suite of programs running on computers con-
nected to the network.
Router: The network device that connects networks together and implements
routing.
Routing: It is a process that occurs on a network when a packet is shunted from
router to router along the path to the target destination. Routing is based on
identifying the destination network from the IP address of the target
machine.
Switch: A network device that connects communication links together, enabling
networks to be built that are on the same network but do not have to share
the same link. This reduces collisions and improves network efficiency.
TTL (time-to-live): A parameter set in a data packet that defines how long that
packet can remain active on the network.

VLAN (virtual local area network): A logical shared network created by
connecting devices to configurable switches so that the network is not
constrained by any physical boundary.
Review Questions
1. List and describe the desirable features of a network simulator.
2. Explain how a network simulator can be used in large classes to enhance
teaching and learning data communications concepts.
3. Consider the effectiveness of a simulation tool in the teaching and learning
contexts.
4. Explain how a simulator can be used in conjunction with active learning
methodologies.
5. What is Packet Tracer? Explain how Packet Tracer can be used as an aid
to enhance teaching and learning data communications.
6. Understand the functions and facilities of a teaching-orientated network
simulator program.
7. List and describe possible enhancements to the proposed practical activi-
ties described in this chapter.
References
Almstrum, V. L., Dale, N., Berglund, A., Granger, M., Currie Little, J., Miller,
D. M., et al. (1996). Evaluation: Turning technology from toy to tool: Report
of the Working Group on Evaluation. In Proceedings of the 1st Confer-
ence on Integrating Technology into Computer Science Education (pp.
201-217).
Biggs, J. B. (1999). Teaching for quality learning at university: What the
student does. Buckingham, UK: Open University Press.
Bonwell, C., & Eison, J. (1991). Active learning: Creating excitement in the
classroom (ASHE-ERIC Higher Education Rep. No. 1). Washington, DC:
George Washington University.
Cameron, B. (2003). Effectiveness of simulation in a hybrid online networking
course. Quarterly Review of Distance Education, 4(1), 51-55.

Carbone, A., & Kaasbøll, J. J. (1998). A survey of methods used to evaluate
computer science teaching. Proceedings of the Annual Joint Confer-
ence Integrating Technology into Computer Science Education (pp.
41-45).
Cope, C. (2003). A framework for using learning technologies in higher
education to enhance the quality of students’ learning outcomes. Proceed-
ings of the 20th Annual Conference of the Australian Society for
Computers in Learning in Tertiary Education (ASCILITE) (pp. 134-
141).
Ehrmann, S. C. (1995). Asking the right question: What does research tell us
about technology and higher learning? Change, 27(2), 20-27.
Entwistle, N. J. (1981). Styles of learning and teaching: An integrated
outline of educational psychology for students, teachers and lectur-
ers. Chichester, UK: Wiley.
Laurillard, D. (2002). Rethinking university teaching: A conversational
framework for the effective use of learning technologies (2nd
ed.).
London: Routledge/Falmer.
Naps, T., Rößling, G., Almstrum, V., Dann, W., Fleischer, R., Hundhausen, C.,
et al. (2002). Exploring the role of visualization and engagement in
computer science education: ITiCSE 2002 working group report. ACM
SIGCSE Bulletin, 35(2), 131-152.
Perkins, D., & Salomon, G. (1992). Transfer of learning. In International
encyclopedia of education (2nd
ed.). Oxford, UK: Pergamon Press.
Retrieved February 6, 2004, from http://learnweb.harvard.edu/alps/think-
ing/docs/traencyn.pdf
Ramsden, P. (1992). Learning to teach in higher education. London: Routledge.
Reeves, T. C. (2003). Interactive learning systems evaluation. Englewood
Cliffs, NJ: Educational Technology.
Salomon, G. (2000). It’s not just the tool, but the educational rationale that
counts.RetrievedJuly24,2004,fromhttp://construct.haifa.ac.il/~gsalomon/
edMedia2000.html
Yaverbaum, G., & Nadarajan, U. (1996). Learning basic concepts of telecom-
munications: An experiment in multimedia and learning. Computers &
Education, 26(4), 215-224.

86 Turner
Chapter V
TeachingProtocols
throughAnimation
Kenneth J. Turner, University of Stirling, UK
Abstract
Communication protocols are essential components of computer and data
communication networks. Therefore, it is important that students grasp
these concepts and become familiar with widely used protocols.
Unfortunately, communication protocols can be complex and their behavior
difficult to understand. In order to learn about protocols, a student
therefore needs a more controlled and constrained environment. This
chapter describes the development and use of a protocol animator for
teaching and learning communication protocols.
Learning Objectives
• List and describe the desirable features of a protocol animation tool.
• Describe the main features of the JASPER protocol animator.

Teaching Protocols through Animation 87
• Explain how an animation tool can be used in the classroom to enhance
teaching and learning communication protocols.
• Define the following key terms: animation, simulation, message, time-
sequence diagram, medium, protocol, and protocol entity.
• Consider further enhancements to JASPER and the protocols it simulates.
Introduction
Communications protocols are a vital ingredient of all networks. It is essential for
students to grasp their fundamental principles and to become familiar with widely
used protocols. Unfortunately, communications protocols can be complex and
difficult to understand. Even the simple Alternating Bit Protocol displays
surprising depths of complexity. It is easy to understand static aspects of a
protocol such as message formats. Where protocols become difficult is in their
dynamic behavior.
The main behavior of a protocol is often straightforward. However that may
account for only 20% of its functionality. Protocols may be used in different
configurations such as client-server or peer-to-peer. They have to operate
reliably over a communications link that may exhibit a variety of faults. The
complications in protocol design usually arise in error recovery: dealing with
message loss, misordering, duplication, or misdelivery. Protocols operate in real
time, so tracing their behavior in practice can be difficult.
In order to learn about protocols, a student therefore needs a more controlled and
constrained environment. This chapter explains how a protocol animator has
been developed to meet these needs. The animator is platform-independent,
being written in Java, and is available in source code form, precompiled, and on
the Web.
Existing Work
The term protocol animation is used in this chapter in the sense of giving life
to a protocol definition (from Latin anima meaning soul). Protocol animation has
received surprisingly little attention. An overview of work on the topic can be
found in Turner (2002).

88 Turner
Formal modeling of protocols is commonly used as a basis for protocol simula-
tion. However the goal is to discover flaws in the design of a protocol rather than
to explain how it works. MSCs (Message Sequence Charts; ITU, 2000a) and
SDL (Specification and Description Language; ITU, 2000b) are popular speci-
fication techniques used with communications protocols. Both SDL and MSCs
have graphical syntaxes and can be simulated visually to investigate a specifica-
tion. As examples of protocol simulation to gain understanding, Stepien and
Logrippo (2002) and Yasumoto, Umedu, Yamaguchi, Nakata, and Higashino
(2002) graphically animate specifications written in LOTOS (Language of
Temporal Ordering Specification; ISO, 1987).
There are many network simulators to support modeling and performance
analysis of networks and protocols. Two major examples are the ns/nam
network simulator/network animator (Network Simulator Team, 2005; Yu &
Salehi, 2000) and the cnet computer network simulator (McDonald, 1991, 2005).
A variety of network simulations have been developed under the auspices of the
VINT (Virtual Internet) project. The basis of these simulations is normally some
form of queuing network model. Such simulators are aimed at analyzing
performance issues rather than conveying an understanding of protocols.
The dlpjava data link protocol simulator (King, 1992, 2004) has the aim of
teaching protocols through simulation. However, it focuses exclusively on the
data-link layer. The Pascal-based tool of Lindsay (1992) uses a scripting
language to animate protocol interaction diagrams. A number of one-off protocol
simulators have also been developed. Hudek (2005) presents a Java applet that
graphically simulates the ATM UNI (asynchronous transfer mode user-network
interface). The operation of a simple data transfer protocol has been illustrated
using JavaScript with SDL (Bayfront Technologies, 2003).
Yet other types of simulators deal with distributed algorithms. Here, the
emphasis is on algorithm design rather than protocol design. However Krumm
(1997) shows how the approach can be used to animate the Alternating Bit
Protocol with sequence diagrams.
The JASPER Protocol Animator
The author teaches data communications to undergraduate and graduate stu-
dents. Although a variety of techniques have been used in this (such as message
sequence diagrams), it was found that students grasped only the bare essentials
of protocols. It was felt that a visual, dynamic animation would allow students to
understand protocols more thoroughly. In addition, the advantage of a tool is that
students can learn in their own time and at their own pace.

As explained earlier, no existing tool meets the specific requirements for
teaching protocols. The ideal protocol animation tool should have the following
characteristics:
• It should demonstrate protocol behavior graphically. A visual animation
captures the student’s interest much more than a tool that just produces
traces of protocol messages.
• It should focus on the dynamics of a protocol. Syntactic clutter such as
detailed message formats should be kept to a minimum.
• It should run stand-alone (e.g., on a student’s PC) and also in a Web
environment (e.g., in a computing laboratory). The tool should be written in
a modern, platform-independent language. These features increase the
possibilities for deployment.
• It should support a library of well-known protocols, including standard
pedagogical examples like Alternating Bit as well as realistic protocols used
on the Internet. The tool should have a well-defined API (application
programming interface) that allows new protocol animations to be devel-
oped.
These goals have been realised in the protocol animator called JASPER (Java
Simulation of Protocols for Education and Research). JASPER is intended for
a number of uses:
• It animates well-known protocols as a teaching aid in networking courses.
An instructor can readily deploy protocol animations to Java-enabled Web
browsers.
• It is an extensible tool to which students can readily add new protocols.
Creating a new animation for JASPER is a valuable learning exercise in its
own right. The tool respects object-oriented design principles; for example,
its architecture is that of MVC (model-view-controller). Development for
JASPER therefore reinforces good software design practice.
• Although its main aim is to support teaching, JASPER can also be used in
research and development of protocols. The extensibility and visual anima-
tion offered by the tool are valuable adjuncts to more formal kinds of
modeling and simulation.
Turner and Robin (2001) discuss the design of JASPER in some detail. The same
reference also gives a worked example of how to extend the tool for new
protocols. JASPER can immediately be used by anyone over the Internet: http:/

90 Turner
/www.cs.stir.ac.uk/~kjt/software/comms/jasper. The code is open source and
can be downloaded in precompiled form from the same location. JASPER has
been extensively used in the author’s own institution and is also employed by
several other universities.
Animation Examples
Figure 1 shows a screenshot of the animator executing the Alternating Bit
Protocol. This figure is taken from a Web browser window running the animator
as an applet. It illustrates a three-column display with two protocol entities
(sender, receiver) and the communications medium (i.e., communications link or
network). DATA and ACK messages flow between the sender and the receiver.
In this simulation, messages are simply numbered since the content of data
messages is unimportant.
The control panel at the bottom left allows the user to select protocol actions. The
Clear button restarts an animation. The Undo and Redo buttons move backwards
and forwards in the animated behavior. Run is used to animate the protocol
automatically; while this is happening, the button is labeled as Stop. When the
animator is executed as an application (as opposed to an applet), it allows
scenarios to be loaded and saved. This is useful to place a protocol into a known
state (e.g., connected) and to demonstrate finer points of its behavior. An
application can also print out an entire animation.
To the right of the control panel is a menu of user choices determined by the
protocol rules. Only one choice is currently possible in Figure 1, namely, to send
a DATA message numbered 1. Other choices in this simulation include transfer-
ring messages through the medium, losing them in the medium, and timing out at
the sender.
Figure 2 shows a much more complex animation: TCP (Transmission Control
Protocol) working in peer-to-peer mode. This is a five-column display showing
two service users, two protocol entities, and the medium. The animator interface
allows the main protocol parameters to be defined: user message sizes, protocol
window sizes, and maximum packet size in the medium. Data in transit can be
flushed by either user setting the push flag.
TCP users (most likely, applications) make use of a service interface to set up
a connection, exchange data, and close the connection. In Figure 2 each user has
initiated an active open, leading to a connection being established. User A has

then sent 100 octets (i.e., bytes) to User B, asking that the data be flushed. The
protocol messages to achieve this are shown. Each carries a sequence number
(Seq) and a receive window size (Win). Connection setup messages carry the
synchronization (SYN) flag, while flushed data carries the push (PSH) flag. The
menu in Figure 2 shows that the two users may continue to send data or to close
the connection. By varying the protocol parameters, the tool user can experiment
with fragmentation and the effects of packet loss on parts of a message.
Currently JASPER supports the following protocols, though its design makes
extension straightforward:
Figure 1. Alternating Bit Protocol animation

92 Turner
Figure 2. Transmission Control Protocol animation

• ABP (Alternating Bit Protocol)
• ABRA (Abracadabra Protocol)
• BOOTP (Boot Protocol)
• HTTP (Hypertext Transfer Protocol)
• IP (Internet Protocol)
• SMTP (Simple Mail Transfer Protocol)
• SWP (Sliding Window Protocol, three- and five-column variants)
• TCP (Transmission Control Protocol, peer-to-peer and client-server vari-
ants)
• TFTP (Trivial File Transfer Protocol)
• UDP (User Datagram Protocol)
Tool Architecture
The animator follows the familiar MVC paradigm.
• Model: The model of a protocol is its behavior defined by Java classes. No
particular implementation style is mandated by JASPER. However, many
protocols are already defined by (extended) finite state machines. These
are readily represented in Java using a table-driven approach. The major
state describes whether the protocol is disconnected, processing an incom-
ing connection, and so forth. The state variables contain extra protocol
information such as the current sequence number and the window size. The
model contains one object for each communicating party, for example, the
two users, the two protocol entities, and the underlying medium. Although
these have individual classes, they extend generic definitions that apply to
any protocol.
• View: The view of a protocol is the graphical display of its behavior as a
time-sequence diagram. This is a common way of displaying protocol
message exchanges. It would have been possible to make strict use of
MSCs (Message Sequence Charts) for this purpose. However, for instruc-
tional purposes it was felt that a simplified notation was preferable. In fact,
the time-sequence diagrams are based on the standard for service conven-
tions (ISO, 1992). The columns represent the communicating parties, such
as the two protocol entities and the medium. Time runs down the page, with
message exchanges shown as arrows between the parties. The diagrams
are also annotated by JASPER to show situations such as message loss or
the receiver becoming blocked.

94 Turner
• Controller: The main JASPER class acts as overall controller of the
animation. It coordinates the objects for the communicating parties. The
protocol rules determine which actions are permitted at each step in the
animation (e.g., send or receive a message, lose a message in the medium,
time-out, and retry). The tool user selects an action at each stage. The
controller can also be placed in automatic mode, when it will randomly
select permitted actions at regular intervals. This often highlights unusual
error cases that could be missed during manual simulation.
Animator Interfaces
The animator defines abstract classes and interfaces that are specialized for
each protocol. The Protocol class is the basic framework for any protocol; it is
subclassed for each particular protocol. Protocol entities and the medium are
coordinated by exchange of ProtocolEvent messages. Apart from transmission
and reception, events also include time-outs and comments that allow the
protocol to explain what it is doing.
The ProtocolEntity interface defines the framework for entities that support a
protocol. This is subclassed to create conventional protocol entities as well as
users of communications services. The ProtocolEntity interface requires
generic methods to be implemented, such as initializing the protocol and sending/
receiving messages.
The Timeouts class handles message timers. Since the aim of animation is
educational, the tool does not run in real time. Rather, the tool user decides on
time-out through a menu choice. This gives more control when investigating error
recovery in the protocol. The protocol definition determines whether it supports
time-outs. These are normal in lower-level protocols but not in higher-level ones.
The Medium base class defines the generic properties of a communications
medium. These include the ability to transfer a message successfully or to lose
a message (e.g., due to noise or congestion). This class may be subclassed for
particular protocols. For example, some protocols are expected to operate over
a medium that may duplicate or reorder messages.
JASPER has been class-tested over a period of 4 years at the author’s institution
(a total of about 250 students). It has been used in the following ways:

• Networking courses cover the basic principles of protocol design as well as
major Internet protocols. These are introduced through textual descriptions
and graphical snapshots of a protocol in action. However, JASPER allows
live walk-throughs to be given of protocol behavior. This is easily the most
effective way of conveying how a protocol works.
• Students use Web pages containing the protocol animations. This allows
them to experiment with the protocols at their own pace. Students are
encouraged to investigate corner behavior, whereby a protocol gets into
an unusual state and then recovers from it. There are often so many
situations like this that they cannot be presented formally by the instructor.
It is preferable for students to discover these for themselves. The automatic
run feature is particularly useful for this, allowing an animation to evolve by
itself. If the student sees unusual behavior develop, automatic animation
can be suspended so the situation can be analyzed in depth.
• Students may also download the animator code. It is instructive for them to
see how a protocol is defined (typically, by its state machine). As an
application, the animator can also be used to load, save, and print animation
scenarios.
• Protocol animations have been used in class assignments. Animations also
provide insight into protocol development. For example, an assignment to
implement SMTP is greatly helped by studying the protocol first through
animation.
• New protocol animations have also been set as student projects. In fact a
number of the protocols supported by JASPER have been developed in this
way.
The effectiveness of JASPER has not been evaluated formally. However each
course is assessed by a questionnaire that includes the provision of Web-based
facilities. On a 5-point scale, these are regularly rated 4 (very good).
JASPER has a number of intentional limitations, imposed due to its primary goal
of protocol education:
• The animation does not have any concept of real time, partly because the
animation would then be too fast to follow and partly because the tool user
is required to have full control over how protocol behavior evolves. Certain
protocols are, of course, required to respect real-time constraints. The
animation of such protocols must abstract away from time.
• Protocol messages are shown only in outline since detailed formats would
confuse and complicate the graphical presentation. As a result, students
must learn separately about how protocol messages are actually formatted.

96 Turner
• Currently, only three-column and five-column diagrams can be shown. This
is a limitation of the graphical presentation, not of the core animation
approach. Most protocols can be adequately represented in this way.
However some protocols are not strictly peer-to-peer or client-server. For
example, distributed transaction processing and certain bus protocols
involve multiple entities. These can be represented only as pairs of
communicating protocol entities.
• The protocols currently supported are based on the author’s understanding
of their defining standards. The animation may not completely reflect what
a conforming implementation should do. Certain aspects have also been
simplified in the interests of effective training rather than absolute com-
pleteness. For example, TCP has sophisticated traffic management proce-
dures that are missing from the current animation.
Impact on Students’ Performance
The impact of JASPER on students’ performance has been assessed only
qualitatively. However the author’s experience (substantiated by course ques-
tionnaires and student grades) is that the animation tool has been valuable. Since
the introduction of JASPER, an understanding of protocols has been demon-
strated in greater depth during tutorials, and protocol development assignments
have been completed more effectively.
From the instructor’s point of view, the availability of protocol animation means
that more realistic assignments can be set (and not just trivial protocols). The
instructor can also set more in-depth questions in formal examinations. For
example, these can address tricky issues such as error recovery and protocol
performance over lossy mediums.
From the student’s point of view, it is easier and quicker to learn about protocols.
This has been evident in the students’ grasp of subtler issues during tutorial
discussions. Students have also been able to tackle more complex protocols in
assignments than could previously have been set.
Conclusion
A thorough understanding of communications protocols is vital to any networking
course. However the dynamic and complex nature of many protocols makes it

difficult for students to gain any real insight into them. It has been argued that
a graphical protocol animator is an important tool in allowing students to study
protocols — especially their behavior under error conditions.
Although a number of network simulation tools exist, their focus is quite different
from that required of an instructional aid. The JASPER protocol animator has
therefore been developed as an adjunct to other network teaching techniques.
The animator is graphical and can be Web-based or stand-alone. It exploits Java
as an object-oriented, platform-independent implementation language. The
animator can be driven manually by the tool user or can be set to run
automatically. Through experimenting with key protocol parameters and unusual
behaviors, the student can gain new insights into general principles of protocol
design, as well as into the operation of well-known protocols.
Acknowledgments
The bulk of the design and implementation work for JASPER was undertaken
by I. A. Robin while a master’s student under the author’s supervision. Further
protocol animations were added by P. K. Johnson and K. J. A. Whyte as student
projects.
Summary
Communications protocols are an essential part of many computer networking
courses around the globe. Unfortunately, it is difficult to motivate students to
learn communication protocols because the topic appears to be rather technical
and complex. This chapter describes the design and use of a graphical protocol
animator called JASPER that enhances the teaching and learning of protocols.
Both instructors and students can benefit from the use of JASPER in different
teaching and learning contexts. An instructor is able to use it in the classroom for
practical demonstrations that liven up lectures and also to use it in support of
assessments. Students can use the system to develop a better understanding of
communication protocols, especially their behavior under error conditions.
Through experimenting with key protocol parameters, students can gain an
insight into the basic principles of protocol design and analysis, as well as into the
operation of well-known protocols.

98 Turner
Animation, simulation: The abstract execution of a system model. The two
terms are barely distinguished, though animation has the sense of symbolic
execution while simulation has a more general sense and may deal with
performance.
Formal language, formal method: A mathematically based technique for
precisely specifying and analyzing systems through abstract models. Major
classes of formal methods include those based on process algebras (e.g.,
the LOTOS language) or on state machines (e.g., the SDL language).
Medium: The communications link or network that carries protocol messages.
Message: The structured data communicated by a protocol. Parameters of a
message typically include the message type, sequence number, control
flags, and user data.
Protocol: The formats and rules governing exchange of messages among
communicating systems.
Protocol entity: The component of a system that implements a protocol.
Service: The abstract interface to a protocol. Details of how the protocol works
are hidden from the service user. For example, protocol error recovery
mechanisms such as retransmission on time-out are not visible in the
service.
State machine: An abstract model that characterizes the behavior of a system
through the transitions it makes between states. Practical models have a
finite number of states. An extended finite state machine has a major state
that controls its main behavior and also state variables that have a smaller
impact on the general operation of the system.
Three/five-column diagram: A form of time-sequence diagram that shows the
two protocol entities and the medium (three-column) or also the two service
users (five-column).
Time-sequence diagram: A graphical presentation of message exchange
among communicating systems. Time flows down the page. Arrows show
messages between carried from one system element to another.
User: The system element that employs a service. This may be a human end-
user or, more typically, a communications application that provides further
services to the end user.

Review Questions
1. Describe three important features of a protocol animator.
2. Discuss how JASPER might be used to enhance teaching and learning of
protocols.
3. Illustrate the behavior of the Alternating Bit Protocol and the Transmission
Control Protocol by drawing the kinds of time-sequence diagrams that
JASPER supports.
4. Define the following key terms: animation, time-sequence diagram, and
protocol.
5. Describe enhancements that might make JASPER more user-friendly.
6. List some additional protocols that might be supported by JASPER using the
current style of animation. What kinds of protocols would be unsuitable for
this approach?
References
Bayfront Technologies. (2003). DataXfer protocol simulation in JavaScript.
Retrieved April 2005, from http://www.bayfronttechnologies.com/
l01fun.htm
Hudek, D. (2005). UNI 3.1 signaling package simulator. Retrieved April
2005, from http://www.ultranet.com/~dhudek/junidemo1.shtml
International Organization for Standardization/International Electrotechnical
Commision. (1987). Information processing systems – Open systems
interconnection – LOTOS – A formal description technique based on
the temporal ordering of observational behaviour (ISO/IEC 8807).
Geneva, Switzerland: International Organization for Standardization.
International Organization for Standardization /International Electrotechnical
Commision. (1992). Information processing systems – Open systems
interconnection – Conventions for the definition of OSI services (ISO/
IEC TR 10731). Geneva, Switzerland: International Organization for
Standardization.
International Telecommunications Union. (2000a). Message Sequence Chart
(MSC) (ITU-T Z.120). Geneva, Switzerland: International Telecommuni-
cations Union.

100 Turner
International Telecommunications Union. (2000b). Specification and Descrip-
tion Language (ITU-T Z.100). Geneva, Switzerland: International Tele-
communications Union.
King, P. J. B. (1992). Data link simulation. IEEE Transactions on Education,
40(3), 172-178.
King, P. J. B. (2004). Data link protocol simulator. Retrieved April 2005, from
http://www.cee.hw.ac.uk/~pjbk/dlpjava
Krumm, H. (1997). Verteilte Algorithmen. Retrieved April 2005, from http://
ls4-www.cs.uni-dortmund.de/RVS/MA/hk/OrdnerVertAlgo/AltBit.html
Lindsay, D. (1992). Visualising computer communications. In D. C. Bateman &
T. Hopkins (Eds.), Developments in the teaching of computer science
(pp. 72-79). Canterbury, UK: University of Kent.
McDonald, C. S. (1991). A network specification language and execution
environment for undergraduate teaching. In Proceedings ACM Computer
Science Education Symposium (pp. 25-34). New York: ACM Press.
McDonald, C. S. (2005). The cnet network simulator. Retrieved April 2005,
from http://www.cs.uwa.edu.au/pls/cnet
Network Simulator Team. (2005). Network simulator version 2. Retrieved
April 2005, from http://www.isi.edu/nsnam/ns
Stepien, B., & Logrippo, L. (2002). Graphic visualization and animation of
LOTOS execution traces. Computer Networks, 40(5), 665-681.
Turner, K. J. (Ed.). (2002). Protocol animation [Special issue]. Computer
Networks, 40(5).
Turner, K. J., & Robin, I. A. (2001). An interactive visual protocol simulator.
Computer Standards and Interfaces, 23, 279-310.
Yasumoto, K., Umedu, T., Yamaguchi, H., Nakata, A., & Higashino, T. (2002).
Protocol animation based on event-driven visualization scenarios in real-
time LOTOS. Computer Networks, 40(5), 639-663.
Yu, H., & Salehi, N. (2000). The network simulator ns-2. In Proceedings
Network Simulator Workshop. Cooperative Association for Internet
Data Analysis.

Student Understanding of Packet-Forwarding Theories 101
ChapterVI
EnhancingStudent
Understandingof
Packet-Forwarding
TheoriesandConcepts
withLow-Cost
LaboratoryActivities
Anthony P. Kadi, The University of Technology Sydney, Australia
Abstract
Teaching packet-forwarding theories and concepts in a practical way to
undergraduate students requires both a teaching and learning framework
and a laboratory infrastructure. Creating a teaching and learning
framework in which students can develop a deeper knowledge and
understanding of abstract concepts is not a simple task. In addition to
teaching materials, the teacher requires a clear idea about learning
theories and issues: (1) what is learning; (2) what is knowledge; and (3)
how do students go about learning. This chapter describes a low-cost

102 Kadi
laboratory infrastructure for teaching and learning packet-forwarding
theories and concepts. The framework is learner-centred and is focused on
learning experiences in both classroom and laboratory. The laboratory-
based activities form a critical component of the overall framework.
Learning Objectives
• Explain how packet-forwarding theories can be taught in a practical way.
• Discuss the effectiveness of hands-on laboratory activities in teaching and
learning contexts.
• Define the following key terms: experiential learning, packet forwarding,
and static and dynamic routing.
• Suggest further improvements to the laboratory activities described in the
chapter.
Introduction
This chapter presents a teaching and learning framework for packet-forwarding
concepts which aims to give students a deep understanding of these concepts.
The framework is learner-centred and focuses on learning experiences in the
classroom and the laboratory. The laboratory-based activities form a critical
component of the overall framework; however, the other elements of the
framework are equally important in achieving the intended aim. The chapter
begins with a philosophical basis for the teaching and learning framework and
then describes the elements of the framework and how these are put into
practice, illustrated by several examples. The chapter concludes with a discus-
sion on some initial indicators of the efficacy of the framework and directions for
future work.

Enhancing Student Understanding
Creating a teaching and learning framework in which students can come to
deeply understand abstract concepts is not necessarily a simple task. Among
other things, the teacher needs to have a clear idea of such fundamental, yet often
glossed-over issues such as:
• What is learning?
• What is knowledge?
• How do students go about learning?
An individual teacher’s answers to the above questions will have a profound
impact on precisely what activities take place in the classroom and how these
activities are conducted. This, in turn, has a major impact on what students learn
(the subject content), but also how they go about learning (the process) and the
resulting level of understanding that they are able to demonstrate (the depth of
understanding). Although seemingly simple questions, there is significant debate
within the global education community on the answers to these questions. This
chapter presents a set of answers to these questions which forms the philosophi-
cal basis for the teaching and learning framework described. The answers are
drawn from one of the more widely accepted viewpoints on learning from the
scholarly education literature.
Kolb (1984) provides a “working definition” of learning: “Learning is the process
whereby knowledge is created through the transformation of experience.” He
then goes on to say that “to understand learning, we must understand the nature
of knowledge, and vice versa.” Kolb is one of many who reject the absolutist
view of knowledge, which says that knowledge is an independent entity that
exists in the world, waiting to be discovered or acquired. Such a view would imply
that teaching is simply a process of transmitting knowledge from a source into
the mind of a student. Kolb’s alternative theory is that knowledge is something
that exists only within individual minds, and that it has to be created by a process
of learning involving transformations and negotiations between existing knowl-
edge and experiences. Whether or not a teacher makes a deliberate choice about
which learning theory they accept, their understanding of what learning is and
how it occurs will largely influence the type of activities that students in their
classes are asked to do.
Kolb’s theory of experiential learning has numerous synergies with the notion of
constructivism, in which, as Duffy and Jonassen (1992) explain, “meaning is
imposed on the world by us, rather than existing in the world independently of us.

104 Kadi
There are many ways to structure the world, and there are many meanings or
perspectives for any event or concept. Thus there is not a correct meaning that
we are striving for.” The focus, in this instance, is on meaning. However, it can
be argued that meaning is actually a facet of knowledge itself. Gorman (2002)
describes three classes of knowledge and four facets of the more commonly
understood type of knowledge:
• Tacit knowledge: Knowledge that is learned without conscious under-
standing of underlying theory.
• Explicit knowledge: There are four types:
Ø Information: sometimes also called propositional knowledge.
Ø Skills: knowing how to use information, also referred to as procedural
knowledge.
Ø Judgment: knowing when it is appropriate to use skills and informa-
tion in a given context.
Ø Wisdom: knowing why it is appropriate to use certain judgments, skills,
and/or information in the right combination for a given set of circum-
stances; wisdom and judgment are sometimes referred to collectively
as dispositional knowledge.
• Distributed knowledge: collectively owned knowledge that is owned as
a result of teamwork.
In comparison, it would seem that Duffy and Jonassen’s notion of meaning could
be considered as a combination of Gorman’s judgment and wisdom.
A critical aspect of all of these theories is that knowledge is not simply
information or facts that can be presented to a student for regurgitation. Deep
understanding of a concept involves knowing about it, how to apply it, when to
apply it, and also why to apply it.
Successful teaching which results in deep understanding of a given set of
concepts also requires an understanding of how students go about learning.
Entwistle (1997) describes three different approaches that students take to
learning. Table 1 summarizes the three approaches of learning.
If a teacher wants his or her students to take a deep approach to learning, what
conditions need to be in place to enable and/or encourage this? Biggs (1987)
addressed this question in his research. He found that there are a number of
factors that will contribute to the choice of learning approach taken by a given

student in a give instance, and these include personal attributes such as ability,
experiences, and locus of control (extent to which the learner can control their
learning experience to suit them); and situational attributes such as the nature of
the task, situational stipulations (e.g., student must pass this subject in order to
progress towards graduation), instructional set (things that students actually
have to do), and formal teaching. Biggs concluded “Whether or not a deep
approach is used will depend more on the way the task is presented in context,
than on the individual student doing it.”
In the application of these teaching and learning theories to the aim of having
students coming to a deep understanding of packet-forwarding concepts, there
is very little in the literature on this specific topic. There are examples of writings
that describe laboratory equipment and configuration or software (e.g., Bokhari
et al., 2004; Casado, Vijayaraghavan, Appenzeller, & McKeown, 2002), but
these do not link the laboratory activities to the teaching and learning approach
used within a given context and, hence, do not describe how the lab activities
contribute, if at all, to student understanding. Other works do attempt to link
teaching and learning theories with the broad area of computer networking (see,
e.g., Chang, 2004); however, these are often nonspecific regarding packet-
forwarding concepts. They may incorporate some aspects of this specific area
but rarely focus on it. There are many courses and training programs that do deal
with this specific topic (e.g., Cisco courses such as Cisco Certified Network
Associate); however, these are rarely reported in the literature, if at all (e.g.,
Liang, 2000), and rarely link education theory with specific learning outcomes.
Table 1. Entwistle’s three different student approaches to learning
Deep Approach
(transforming)
Surface Approach
(reproducing)
Strategic Approach
(organising)
Intention: to understand ideas
for yourself by:
• Relating ideas to previous
knowledge and experience
• Looking for patterns and
underlying principles
• Checking evidence and
relating it to conclusions
• Examining logic and
argument cautiously and
critically
• Becoming actively interested
in the learning materials and
processes
Intention: to cope with learning
requirements by:
• Studying without reflecting on
either purpose or strategy
• Treating learning as unrelated
bits of knowledge acquisition
• Memorising facts and
procedures routinely
• Finding difficulty in making
sense of new ideas presented
• Feeling undue pressure and
worry about work and/or
learning
Intention: to please oneself and
significant others with high
marks, grades etc. by:
• Putting consistent effort into
studying
• Finding the right conditions
and materials for study
• Managing time and effort
effectively
• Being alert to assessment
requirements and criteria
• Gearing work to the perceived
preferences of assessors
Focus is on learning process and
meaning
Focus is on facts and procedures Focus is on assessment of
learning

106 Kadi
The Teaching and Learning Framework
Using the learning and teaching theory briefly outlined above, a framework has
been developed and successfully applied in a relatively large class (approxi-
mately 60 students) at the postgraduate level in the Faculty of Engineering,
University of Technology, Sydney. The class is known as 49202 Communication
Protocols and is taken by students enrolled in the master of engineering or master
of engineering studies program with a major in telecommunications. The only
difference between these two programs is that students in the master of
engineering also need to complete a graduate project (which is like a half-thesis).
The focus of the class is on generic concepts that are critical to an understanding
of communication protocols, and these concepts are illustrated predominantly
with examples from the TCP/IP protocol suite. The textbook used for the class
is Forouzan (2003).
The framework is focused on and best described by the set of learning
experiences that students are asked to undertake as part of the class. These are:
• Reading specific chapters/sections from the textbook. This experience
introduces the student to a specific topic area and begins to situate this topic
within the course as a whole.
• Participating in a “lecture” session. During this experience, the student is
introduced to abstractions of specific examples and begins to construct a
basic understanding of the underlying concepts. The teacher-centred
lecturing is regularly interrupted, and the student is asked to solve basic
problems. This keeps the student active and is a critical component of
building understanding as it tests the students’ current knowledge with what
they have just been exposed to. The result is either reinforcement of current
knowledge or realignment.
• Completing a set of prework questions for a laboratory session that is held
at least one week after the lecture session. These questions relate
specifically to the concepts developed in the lecture session, and some of
the problems solved during the lecture session by the students are related
to or form part of the laboratory prework.
• Sitting for a short (e.g., 15-minute) online quiz of concepts developed in the
lecture session. This quiz is held in the week following the lecture class to
give students time to further develop their understanding through self and
group study. The quiz contributes 15% of the final grade. The main reason
for this is to provide an incentive to keep up-to-date each week and spread
the learning out over the entire semester. Some of the questions in the
quizzes are specifically related to the laboratory prework.

• Undertaking a series of laboratory activities that are linked to the concepts
developed during the lecture sessions. The basic aim of each lab session is
to confirm (or deny) the work that was done in the lecture and the lab
prework. Observations made during the lab are discussed in groups, and
students help each other to gain a better understanding of the concepts and
theory. The laboratory activities are not entirely prescriptive but do allow
for some individual experimentation and observation (Biggs’ locus of
control).
• Writing a laboratory report for documenting prework and results obtained
in the lab and explaining the results with regard to the theory from the
textbook, lectures, and prework. The report also includes answers to
higher-level conceptual questions that probe deeper understanding of key
concepts. The report is assessed, and overall, lab reports contribute 30%
of the total assessment. The successful completion of laboratory reports is
thus one of Biggs’ institutional stipulations.
• Reflecting on the assessment of their laboratory report and quiz to
determine whether their understanding of key concepts and theories is
aligned with the teacher’s. This alignment of the student’s understanding
with the teacher’s understanding is a critical element of the teaching and
learning process, which Laurillard (2002) models using what she calls a
“conversational framework.” Detailed feedback on laboratory reports, as
well as the posting of the best report on the Web, allows students to validate
their knowledge — if there is substantial alignment, then the knowledge is
reinforced; if there is misalignment, the student can realign and eliminate
misconceptions by comparing their report with the one posted on the Web
or by individual discussions with the teaching staff during consultation
times.
• Completing a final examination at the end of semester which has some
questions from lectures, quizzes, and labs, as well as questions that the
students have not previously seen. The exam contributes 55% of the final
grade. The questions in the final exam are designed to test understanding
and application of the key concepts, not regurgitation of information or
facts.
The semester consists of six modules of 2 weeks each. The first week in each
module consists of pre-lecture readings, attending and participating in the
lecture, and then doing the lab prework. The second week in each module
consists of sitting for the short quiz, doing the lab activities, and then writing and
submitting the report. A detailed report assessment is returned 2 weeks after
submission and is discussed during a subsequent lecture. Quiz questions are also
briefly discussed in lectures to clarify any ambiguities.

108 Kadi
The learning and teaching framework, therefore, is based on learning experi-
ences and specifically links theory with reality. A carefully constructed series
of learning experiences, of which the laboratory activities are the nexus, allows
the student to construct knowledge over time and enables misconceptions to be
revealed and dealt with, if present. These learning experiences also enable
deepening of understanding by reinforcing theory with real observations and the
need to demonstrate knowledge in various assessment tasks over the course of
the semester.
Laboratory Activities
and Infrastructure
A number of important practical considerations in the implementation of the
learning and teaching framework are:
• What is the cost associated with the laboratory infrastructure required to
deliver the various learning outcomes?
• Can the laboratory infrastructure be used for other purposes to help justify
its acquisition and operation?
In the Faculty of Engineering at the University of Technology, Sydney (UTS), we
have a networking teaching laboratory which can be used by a number of
different classes and courses. Normally, this is a nontrivial matter because both
software and hardware may need to be significantly altered for different
activities and different classes. We have implemented a system using removable
hard-disk drives and easily accessible networking hardware which allows rapid
reconfiguration of both the hardware and software. We use this laboratory
infrastructure for many different subjects and lab activities, but the one that is
detailed in this chapter is on layer-3 packet-forwarding concepts known as
routing.
A laboratory session consists of a number of learning activities. Each activity in
the routing lab session is designed to demonstrate the behaviour of the network
in a particular state and link this to the theory. Questions in the lab notes which
need to be answered as part of a lab report are designed to link these activities
together and to assist students in constructing knowledge of packet-forwarding
concepts in general.
The 2-and-a-half-hour laboratory session that focuses on routing consists of the
following seven specific activities:

1. Static routing using default routes around a logical ring topology;
2. Static routing using fixed routes in a mesh topology;
3. Static routing incorporating a deliberate routing loop;
4. Dynamic routing using Routing Information Protocol (RIP);
5. Simulated failure and subsequent recovery of a router using RIP;
6. Dynamic routing using Open Shortest Path First (OSPF); and
7. Simulated failure and subsequent recovery of a router using OSPF.
The lab infrastructure is described next.
The Laboratory Infrastructure
For the routing lab activities, the following equipment is used and is intercon-
nected as shown in Figure 1:
• 50 personal computers (PCs) spread amongst 10 benches
Ø 10 of these PCs (one PC on each bench, shown in green in Figure 1)
configured with RedHat Linux version 9.0 (http://www.redhat.com)
on a removable hard-disk drive to act as a router. These PCs are
equipped with:
• One four-port Ethernet network interface card (NIC; D-Link
DFE-580TX; D-Link Australia, 2003).
• Two single-port Ethernet NICs (D-Link DFE-538TX; D-Link
Systems, 2005). One of these acts as the “management inter-
face” to the router.
Ø The remaining 40 PCs to act as “client” computers. These have a CD
drive (but not a hard disk) and can boot and run a version of Linux
called Knoppix (http://www.knoppix.net). Each of these PCs has a
single-port Ethernet NIC (D-Link DFE-538TX). Students are as-
signed to these client computers in pairs. Thus, the lab can accommo-
date up to 80 students in a session.

110 Kadi
• Ten eight-port unmanaged Ethernet switches (one on each bench) to
connect each of the client PCs on that bench to one port of the router.
• One 16-port unmanaged Ethernet switch to connect all management
interfaces of all the routers together to form a management subnetwork
(shown in dotted lines in Figure 1).
• A number of Ethernet cables:
Ø Standard Cat-5e patch cables for connecting the PCs to the Ethernet
switches (shown in blue in Figure 1).
Ø Cat-5e crossover cables for connecting the routers to each other
(shown in red in Figure 1). These cables are “strung up” to the ceiling
and labelled on each end, so that staff and students can clearly identify
where each of the cables originates and terminates and they are easily
accessible for simple and rapid reconfiguration.
All of this hardware (apart from the four-port NICs) can be purchased from most
retail computer outlets. The infrastructure can be scaled up or down to suit local
needs. If computers with more than three PCI expansion slots are used, an
equivalent result can be achieved with using only the more commonly available
and inexpensive single-port NICs. The software, RedHat Linux, Knoppix Linux,
and other software mentioned in this chapter are all freely available on the Web.
One of the routers (or an additional PC connected to the management subnet)
acts as a management station. From here, the logical topology and forwarding
Figure 1. UTS laboratory configuration
A
B
D
L
K
J
H
G
F
C
‘Client’
PCs
Ethernet
switch
PC acting as router
Cat-5e cables

behaviour of the network can be changed by issuing a single command. For
example, to transition the routers from activity 3 (static routing) to activity 4
(dynamic routing with RIP), a single command is entered at the management
station console. This command is generally a script that makes secure shell
command calls to each of the routers via the management interfaces to change
routing tables manually, start/stop routing daemons, or configure routing soft-
ware. For dynamic routing activities, a software package known as GNU Zebra
(http://www.zebra.org) is used for the implementation of the routing protocols
and associated behaviours. This freely available software has a command line
interface that emulates Cisco routers.
In each activity, students can use the ping program, usually with the route
recording option enabled, to determine the following information:
• if there is connectivity in both the forward and reverse paths to a particular
destination from their location;
• the details of the forward and reverse paths (i.e., the router interfaces
traversed);
• the end-to-end delay statistics of multiple pings (minimum, maximum, and
average) as well as the first ping (generally delayed due to address
resolution process taking place).
The IP addressing structure used for the routing laboratory enables a simple
translation between physical location and IP address. This allows students to
ping particular destinations and examine the routes taken with relative ease.
Details of this can be obtained from the author, if desired.
Students are also able to use a packet sniffer, in this case, the freely available
Ethereal (http://www.ethereal.com), on both client and router interfaces to gain
more details about forwarding behaviour. Ethereal is one of the packages
available in Knoppix Linux, and it can also be installed from the RedHat 9.0
distribution.
Unfortunately, due to space limitations, it is not possible to share the details of
each of the activities with the reader; however, a couple of examples will
illustrate the design and implementation philosophies described earlier.
Example Activity 1: Static Routing With Logical Mesh Topology
The students are given copies of the routing tables for each router, which are
manually configured for optimal mesh routing. An example routing table is shown
in Table 2. For prework, students are asked to:

112 Kadi
• Determine the forward and reverse routes for particular source and
destination pairs.
• Compare the total number of hops between various destinations for a
particular source with those if a logical ring topology were used.
• Predict what would happen if particular links fail and compare to the case
of a logical ring topology.
During the lab activity, they actually ping various destinations from the source
that they have been assigned and verify that their predictions are consistent with
reality and the theory. They also do this for the logical ring topology in a previous
activity.
This activity allows students to learn and understand:
• Routing in networks at layer 3 can be done manually through the use of
routing tables stored at each router.
Table 2. Example routing table
ROUTING TABLE FOR ROUTER A (Activity 2)
Destination Next Hop Genmask Iface
10.1.6.0 Direct 255.255.255.252 eth0
10.1.2.0 Direct 255.255.255.252 eth1
10.1.3.0 Direct 255.255.255.252 eth2
10.1.1.0 Direct 255.255.255.0 eth3
10.2.2.0 10.1.2.2 255.255.255.0 eth1
10.3.3.0 10.1.3.2 255.255.255.0 eth2
10.4.4.0 10.1.2.2 255.255.255.0 eth1
10.6.6.0 10.1.6.2 255.255.255.0 eth0
10.7.7.0 10.1.6.2 255.255.255.0 eth0
10.8.8.0 10.1.6.2 255.255.255.0 eth0
10.10.10.0 10.1.6.2 255.255.255.0 eth0
10.11.11.0 10.1.2.2 255.255.255.0 eth1
10.12.12.0 10.1.2.2 255.255.255.0 eth1
10.2.3.0 10.1.2.2 255.255.255.252 eth1
10.2.4.0 10.1.2.2 255.255.255.252 eth1
10.3.6.0 10.1.3.2 255.255.255.252 eth2
10.4.6.0 10.1.6.2 255.255.255.252 eth0
10.4.12.0 10.1.2.1 255.255.255.252 eth1
10.6.7.0 10.1.6.2 255.255.255.252 eth0
10.7.8.0 10.1.6.2 255.255.255.252 eth0
10.7.10.0 10.1.6.2 255.255.255.252 eth0
10.7.12.0 10.1.6.2 255.255.255.252 eth0
10.8.10.0 10.1.6.2 255.255.255.252 eth0
10.10.11.0 10.1.6.2 255.255.255.252 eth0
10.11.12.0 10.1.2.2 255.255.255.252 eth1

• The logical topology of the network need not necessarily follow the physical
topology of the network, and this can be changed by modifying the routing
tables.
• A ring topology provides a more consistent routing delay but is prone to
catastrophic failure by the failure of a single link.
• An optimal mesh topology provides a lower, but more variable routing delay
(for different destinations in the network, not for different packets!) and is
more resilient to link or node failures.
Example Activity 2: Dynamic Routing Using OSPF
In this activity, there is no prework, as it follows on from previous activities. The
students determine a destination that requires a path through a particular router.
They begin to ping that destination with the route recording option and with a ping
frequency of 5 seconds. The tutor then announces that the particular router has
failed and simulates this by disconnecting all of the network cables to that router.
The ping packets stop getting responses until the OSPF protocol rearranges the
topology and provides alternate paths. At this point, the pings begin to work again,
and by counting the number of ping packets lost, students can estimate the
recovery time of the network. The “failed” router is then re-enabled by plugging
the cables back in, and after a brief delay, the routes are updated to the original,
more optimal routes. Again, the time required for reconfiguration can be
estimated. These times can then be compared to those obtained from the same
activity but using RIP. The students are asked to answer the following questions:
• Why does the ping continue after some delay following the failure of a
router?
• Why does the route change when the failed router is re-enabled?
• Why are the recovery times different for the different routing protocols?
• From this activity, students develop a better understanding of:
• A dynamic routing protocol can allow the network to adapt to link and/or
router failures and provide alternate forwarding paths, if they are available.
• A routing protocol will always result in the most “optimal” route being
chosen, and this can vary over time as routers and/or link states change.
• The performance of routing protocols varies depending on their design and
implementation. (In the previous activity, students investigate the size,
frequency, and format of routing messages exchanged between routers for
both RIP and OSPF.)

114 Kadi
Student Results and Feedback
Initial results from the implementation of the teaching and learning framework
described in this chapter have been very encouraging. At the time of writing, a
formal study and analysis of the efficacy of this framework have not been carried
out. This section describes some initial indicators of its effectiveness and
acceptance by the students.
In the autumn semester of 2004, a class of 55 postgraduate coursework students
undertook the laboratory activities described above. In the final exam (3 hours
duration, five questions, 20 marks each), the average score in the final exam
question specifically related to routing was 13.9/20 (»70%), which was the
highest of all the questions asked that semester. This was quite different to
previous semesters in which a more traditional teaching and learning approach
was used, and the scores for questions on routing were much worse.
Students also responded very favourably to the experiential teaching and
learning approach in the end-of-semester survey. Here is a selection of the
comments that students made in open-ended questions such as “What did you
like best about this subject and why?”:
• “[The lecturer] made the learning process a fun activity to do, and this is
quite [a] difficult thing to do. I really enjoyed it and also can appreciate the
amazing preparation for one of the labs, particularly the one relating to
routing. ... Having done five Cisco courses, I believe the coordination put
together in the routing is just outstanding. Appreciating the differences of
OSPF and RIP functionalities, for example, and static and dynamic routing
in a single session ... well, [it] is just fantastic.”
• “I liked the lab activities the most, because it was helpful to understand what
we learnt from the class time. Especially, most of lab activities were deeply
related to the practical ideas.”
• “I particularly enjoyed the fortnightly rotation of theory and practical work.
It gives students enough time to prepare and absorb materials and to test
those ideas and theories out during the quiz and laboratories. The first week
provides the background, and the second week grounds and cements that
information into knowledge. Having this duality helps keep the subject
‘alive’ and ‘fresh’; pure book reading tends to reduce student interests and
‘zest’ for learning materials. The rotation helps keep a healthy interest in
study.”
• “The labs strongly bought home the theoretical concepts. They made us see
what was happening right before our eyes. There is nothing worse than not
understanding how theory has meaning.”

Conclusion and Directions
for Future Work
Although it is too early to conclusively say that the approach described in this
chapter to helping students learn and understand packet-forwarding concepts is
better than traditional approaches, the results to date are very encouraging. With
a focus on learning experiences rather than on content and with the low-cost
laboratory infrastructure described briefly in this chapter (which can also be used
for many other purposes), the teacher can ensure that appropriate knowledge is
constructed by the learners in an effective and efficient manner.
Further work is required to gauge the effectiveness of this teaching and learning
approach and to determine whether the approach used in this particular context
can be applied to other contexts. More information about the laboratory
infrastructure and course materials can be found by contacting the author.
Summary
It is often difficult to motivate students to learn packet-forwarding theories and
concepts because many students appear to find the topic technical and rather dry
and boring. This chapter described a framework for enhancing teaching and
learning various aspects of packet-forwarding theories and concepts at both
introductory and advanced levels. The framework is based on a set of learning
activities: readings, class participation, laboratory session, problem solving,
quizzes, practical laboratory activities, report writing, and summative assess-
ments.
Both teacher and students can benefit from the use of laboratory infrastructure
in different teaching and learning contexts. A teacher is able to use the system
both in the classroom and laboratory as a demonstration to liven-up the lecture
environment. Students, on the other hand, gain a practical hands-on learning
experience by setting up and configuring routing protocols. Through experiment-
ing with key parameters, the students can gain insights into the key concepts of
packet-forwarding theories. Student responses to the end-of-semester survey
were mostly favourable. The students indicated that they had found the
laboratory activities easy to use and helpful in gaining an understanding of
packet-forwarding theories and concepts.

116 Kadi
Constructivism: A theory of learning and knowing that holds that learning is an
active process of knowledge construction in which learners build on prior
knowledge and experience to shape meaning and construct new knowl-
edge.
Deep learning: The process by which a person comes to achieve a critical
awareness of a particular item of information or an idea as well as how this
information can be used in the real world, why it should be used, in what
ways and what situations it is applicable, and its relationship to other
matters.
Dynamic routing: A form of routing in which the routes that packets take in a
network are able to change as a function of time. The routes can change
as a result of node or link failures or as a result of node or link characteristics
(speed, cost, etc.), including the volume of traffic that is currently being
serviced.
Experiential learning: A theory about the process of learning that involves a
four-stage cycle consisting of concrete experience, reflective observation,
abstract conceptualisation, and active experimentation.
Packet forwarding: The process by which protocol data units in a packet-based
network are sent from their source to their destination.
Routing: The process of packet forwarding that is done at layer 3, usually called
the “networking” layer in a protocol architecture. The most common
protocol used at layer 3 in the world is the Internet Protocol (IP).
Static routing: A form of routing in which the routes that packets take in a
network do not change as a function of time once they are configured.
Review Questions
1. Describe the low-cost laboratory infrastructure for enhancing teaching and
learning packet-forwarding concepts.
2. Explain how learning theories are linked to teaching and learning packet-
forwarding theories and concepts.
3. Explain how the teaching and learning framework for packet-forwarding
concepts is put into practice.
4. Compare and contrast deep, surface, and strategic approaches to learning.

5. Explain how removable hard-disk drives can be used in the laboratory for
experimenting with static and dynamic routings.
6. Discuss the difference between static and dynamic routing.
7. List and describe possible enhancements to the practical laboratory activi-
ties described in the chapter.
References
Biggs, J. B. (1987). Student approaches to learning and studying. Melbourne,
Australia: Australian Council for Education Research.
Bokhari, S. H., Ahmed, M., bin Sohail, S., Khan, R. H., Mirza, J. A., & Ali, M.
(2004). A networking laboratory for the developing world. IEEE Commu-
nications, 42(2), 106-113.
Casado, M., Vijayaraghavan, V., Appenzeller, G., & McKeown, N. (2002). The
Stanford Virtual Router: A teaching tool and network simulator. ACM
SIGCOMM Computer Communication Review, 32(3), 26.
Chang, R. K. C. (2004). Teaching computer networking with the help of personal
computer networks. In Proceedings of the 9th annual SIGCSE Confer-
ence on Innovation and Technology in Computer Science Education
(pp. 208-212). Leeds, UK: ACM Press.
D-Link Australia. (2003). DFE-580TX: 4-port PCI fast Ethernet server
adapter. Retrieved January 21, 2005, from http://www.dlink.com.au/
products/adapters/dfe580tx/
D-Link Systems. (2005). DFE-538TX. Retrieved January 21, 2005, from http:/
/support.dlink.com/products/view.asp?productid=DFE%2D538TX
Duffy, T. M., & Jonassen, D. H. (1992). Constructivism: New implications for
instructional technology. In T. M. Duffy & D. H. Jonassen (Eds.),
Constructivism and the technology of instruction: A conversation.
Lawrence Erlbaum.
Entwistle, N. (1997). Contrasting perspectives on learning. In F. Marton, D.
Hounsell, & N. Entwistle (Eds.), The experience of learning (2nd
ed, p.
19). Edinburgh, UK: Scottish Academic Press.
Forouzan, B. (2003). TCP/IP protocol suite (2nd
ed.). New York: McGraw-Hill.
Gorman, M. E. (2002). Turning students into professionals: Types of knowledge
and ABET engineering criteria. Journal of Engineering Education,
91(3), 327-332.

118 Kadi
Kolb, D. A. (1984). Experiential learning: Experience as the source of
learning and development. Prentice Hall.
Laurillard, D. (2002). Rethinking university teaching: A conversational
framework for the effective use of learning technologies (2nd
ed.).
Routledge.
Liang, C. (2000). A course on TCP/IP networking with Linux. In Proceedings
of the 5th annual CCSC Northeastern Conference on The Journal of
Computing in Small Colleges (pp. 256-264). Consortium for Computing
Sciences in Colleges.
Redhat | The Open Source Leader. Viewed January 21, 2005, at http://
www.redhat.com/

Ethereal 119
ChapterVII
Ethereal:
A Tool for Making the
Abstract Protocol a
Concrete Reality
David Bremer, Otago Polytechnic, New Zealand
Abstract
Learning the nature of data communication and networks requires
understanding of how a theoretical protocol is implemented as actual
communication. Taking ARP as a simple example, it is one thing to be able
to understand its purpose and operation from readings and lectures. It is
another thing entirely to be able to identify the actual ARP traffic from a
sample of packets, identify any unusual behavior, and perform
troubleshooting activities based on previous practical experience. A
theoretical understanding may be enough to describe a particular aspect
of networking, perhaps even enough to pass an exam. Practical knowledge,
however, shows a deeper understanding that comes from actual experience
with the protocol, beyond that of reading and discussion. One issue for
educators in the field of networking is the problem of giving the students an
“up close and personal” interaction with protocols that are so heavily
immersed in theory. How do we make the theoretical protocol a more
concrete reality for the students?

120 Bremer
Learning Objectives
• Recognise the difficulty that students face in becoming familiar with
networking protocols when approached from a purely theoretical perspec-
tive.
• Explain how a packet sniffer tool such as Ethereal can be used to make the
protocols more accessible to students and ease the learning process.
• Critically consider one example for designing a series of related lessons.
• Suggest further enhancements to laboratory activities that make use of
packet analysis.
Introduction
Learning the nature of data communication and networks requires understanding
of how a theoretical protocol is implemented as actual communication. Taking
ARP as a simple example, it is one thing to be able to understand its purpose and
operation from readings and lectures. It is another thing entirely to be able to
identify the actual ARP traffic from a sample of packets, identify any unusual
behavior, and perform troubleshooting activities based on previous practical
experience.
A theoretical understanding may be enough to describe a particular aspect of
networking, perhaps even enough to pass an exam. Practical knowledge,
however, shows a deeper understanding that comes from actual experience with
the protocol, beyond that of reading and discussion. One issue for educators in
the field of networking is the problem of giving the students an “up close and
personal” interaction with protocols that are so heavily immersed in theory. How
do we make the theoretical protocol a more concrete reality for the students?
Within the field of general education, it is fairly well established that it is desirable
to have students work with a “real” system in order to learn the theoretical
foundations of that system. Proponents of making the theoretical concrete
include Dewey (1987), Kolb and Fry (1975), and Papert (1980). These educa-
tionalists advocated the avoidance, or perhaps the postponement, of actually

Ethereal 121
teaching the theory in favor of allowing the students to discover the underlying
principles for themselves. Kolb and Fry (1975) describes learning as a continu-
ous spiral of concrete experience, observation and reflection, development of
abstract concepts, and testing in new situations.
As Sarkar (2005) points out, even Skinner, the archetype behaviorist, favored an
experiential approach to learning (Skinner, 1964). Dewey (1987) suggested that
the language and concepts formed when children were asked to create a chair
were much deeper than when chairs were simply discussed. Papert (1980)
created a child-centered environment (the programming environment LOGO)
that would allow students to engage with geometry on a personal and concrete
level through which they discovered geometric rules for themselves. The
common element is that the learner is working directly with the thing that is being
studied. Unfortunately, while experiential and discovery learning can be very
powerful, most students do not have the time available to independently reinvent
30 years of research into networking, at least not in the 17 weeks that we have
available for teaching a one-semester paper. However, the core principles
proposed by these educationalists are important.
Many networking educators are searching for tools that will allow their students
to experience the abstract theory of networking in a practical way (Cigas, 2003;
Francia & Chao, 2004). This entire book is directed towards this aim. Various
tools and techniques are used to enhance the learner’s understanding of
networks, including simulation and modeling (Cameron & Wijekumar, 2003;
Perez-Hardy, 2003) and the expression of the concept as a graphical animation
(Holliday, 2003). The most concrete approach is having the student interact with
a real network. A number of educators are moving in this direction (McDonald,
Rickman, McDonald, Heeler, & Hawley, 2001).
Comer (2004) quite forcibly argues that “the best way to learn is by doing —
there is no good substitute for hands-on experience with a real network.
Interconnecting the hardware, configuring network systems, measuring perfor-
mance, observing protocols in action, and creating client-server programs that
communicate over a network all help sharpen one’s understanding and apprecia-
tion” (p. 15).
We should remember that networking is not about abstract theory. Sometimes
instructors and lecturers get so immersed in the theory that we forget the reality
that is networking. Even the dry RFCs are in fact describing actual, real,
concrete things that are able to be implemented and are directly observable with
the right tool. We have found that a very powerful educational tool in network
education is one that allows students to capture traffic that they themselves have
created and then to analyze that traffic.
This tool is variously known as a packet analyzer or packet sniffer and will be
known to most networking professionals and educators. We use the open source
product Ethereal in this role within our courses. Many other products, such as

122 Bremer
Network Associates Sniffer, Etherpeek, and Microsoft Server Network Moni-
tor, exist. Network educators have reported that these tools are very useful for
“enhancing the sense of concreteness by giving the student a firsthand look at
TCP/IP transport and protocols” (Mechtly & Decker, 2003). Most sniffers
perform adequately for educational purposes. Ethereal has the advantages that
it is free and cross-platform and performs almost all of the network analysis tasks
that we wish to undertake. The only exception to this that we have encountered
is the monitoring of the PPP connection process. Because of certain interface
restrictions it is not possible to capture the LCP and IPCP traffic in Linux or any
NT-based system. We have however captured such traffic under Windows 98.
Use a Tool or Program a Sniffer?
Our courses have taken the approach that students will analyze real traffic that
occurs within a typical network using an existing tool rather than have the
students develop their own sniffer as a way of learning about network protocols.
There are numerous tutorials available that guide students through the process
of making their own packet analyzer (for those who are interested, refer to
Insolvibile, 2001; Renfro, 1999). Our decision follows the reasoning of Jipping,
Bugaj, Mihalkova, and Porter (2003), who suggest that “If students program
network sniffing themselves, it is very easy to get mired in the data structures and
system interfaces needed to properly fetch a network packet and extract data
that can be analyzed. Students should focus on the analysis itself, not the
mechanics of traffic sniffing.”
In some courses (especially computer science), the data structures may indeed
be the focus of the study. Our course, similar to Adams and Erickson’s (2001),
is targeted more towards a network and system administration model rather than
towards either computer science or business systems. In our situation we wish
to develop an understanding of the network protocols rather than focus on the
data structures involved in programming a network application.
Ethereal
Ethereal is available as open source software (Open Source Initiative, 2004)
distributed under the GNU General Public License (Free Software Foundation,
1991) and is freely available at http://www.ethereal.com. It is a graphical tool
that captures and displays an interpretation of packets that become available to

Ethereal 123
the network card. Providing the network card can be placed in promiscuous
mode, all packets seen by the network card can be displayed, even if they were
not destined for the device on which Ethereal is installed.
One of the criticisms of Ethereal has been the lack of documentation. This has
changed recently with the publication of the online “Ethereal User’s Guide”
(Sharpe, 2004) andtheprinted “Ethereal Packet Sniffing” (Orebaugh& Ramirez,
2004).
Overview of Ethereal Operation
Ethereal’s display interface is broken into three sections as shown in Figure 1.
The top section shows a separate packet in each row. This provides a useful
summary of the traffic that has been captured. The middle section contains an
interpretation of the packet contents with the data arranged in layers resembling
the OSI model. The bottom section displays, in both hexadecimal and ASCII, the
raw data that was captured.
In Figure 1, a line is selected in the top section. This selection is a summary
showing that we have selected a packet traveling from 10.1.0.50 to 10.100.0.145
and that it is an HTTP version 1.1 OK response. The middle section displays an
interpretation of the data within the packet, arranged according to the various
protocols. In this example we would normally see:
• Ethernet II (data link layer),
• Internet Protocol (network layer),
• Transmission Control Protocol (transport layer), and
• HTTP (application layers). To see this you would scroll up in the middle
section.
Figure 1. Ethereal display interface

124 Bremer
Each protocol heading contains a summary of the data within that protocol. The
user may drill down and obtain the detailed protocol data by clicking on the
triangle icon next to the protocol data, as has been done for Hypertext Transfer
Protocol in Figure 1.
The bottom section shows the raw data that was captured. It is worth noting that
the CRC or Frame Check Sequence is not captured. This is removed by the
network card before Ethereal manages to capture any data.
Classroom Use
The procedure used within the class is very simple. We normally follow a routine
of:
• Start Ethereal,
• Begin the data capture,
• Create the traffic that we wish to analyze,
• Stop the capture,
• Analyze the traffic.
The capture interface is shown in Figure 2. Introducing this interface to students
allows us to readdress the various delivery aspects of the data link layer and to
reinforce the fact that traffic may be received by a device that is not actually
intended for that device. This is especially important in a logical bus network that
uses hubs rather than switches. The network card’s promiscuous mode is usually
introduced at this point.
We normally do not introduce the capture filter until well into the course. The
capture filter only records packets matching specified conditions and uses a
rather difficult syntax. Instead we rely on the display filter, which restricts the
display of packets after they have been captured.
We began this discussion of Ethereal by identifying the desirability of turning
abstract theory into a concrete reality for the learner. It is perhaps useful to look
at a particular example of using Ethereal to support the learning of a specific
topic.

Ethereal 125
We have developed a structured or “scaffolded” approach for many of our
topics. While generally favoring the open discovery model of educationalists
such as Kolb, we prefer to include an initial structure that directs students, while
allowing for more open-ended experimentation. The aim is to bring the student
from a stage of reasonable ignorance of a topic through to being able to problem-
solve new or novel aspects of the topic. We try to provide a sequence of related
activities that will provide a scaffolded and staged progression between these
two extremes. Our approach involves the following series of five activities:
1. Instruction: An introductory lesson where the topic is explained to the
student.
The student is a passive participant.
2. Directed task: Modeling and sometimes extreme hand-holding, often with
worksheets.
The student is a very constrained but active participant.
3. Independent activity: The student reproduces their own version of
activities modeled previously.
The student is an active participant demonstrating that they can reproduce
a previously modeled activity.
4. Novel situation, troubleshooting, and diagnostic problem-solving:
Introduce novel situations in which the learner has to investigate, diagnose,
troubleshoot, and problem solve.
Figure 2. Capture Options dialog box

126 Bremer
The student begins to show mastery of the topic by demonstrating an
understanding of an activity that is related but not previously modeled.
5. Reinforcement: The student applies the skills and knowledge from one
topic to activities that are being used to learn subsequent topics.
Example Use of Ethereal in Lessons and Labs
It may be useful to describe the use of this structure by presenting our approach
to teaching the three-way handshake used by TCP to establish a connection.
Stage 1: Instruction — Old-Fashioned Teaching
We begin a sequence of lessons with a lecture that includes an explanation of the
three-way handshake as one stage within TCP (Postel, 1981). The lesson is
typical of any lecture; the instructor is in charge and in full control. Student
activity is reduced to asking occasional questions from the floor, answering
questions posed by the instructor, and note-taking.
Stage 2: Directed Task — Modeling an Investigation of the Topic
The first activity is a very directed worksheet, which directs students to open a
file containing the data already captured from a connection to a Web site. The
students are then asked to answer a number of questions, each designed to point
out aspects of the three-way handshake that were introduced during the lecture.
In many ways the worksheet tells the students what it is they are seeing. One
example taken from the worksheet is shown in Figure 3.
The worksheet is merely an introduction. Such directed learning is not ideal on
its own, but we believe that it has a place in the overall development of the
learner’s understanding. Ethereal captures a large amount of information. The
worksheet is designed to highlight certain aspects of the traffic to the student.
A useful reference for the students in these labs is an article by Chappell (2000)
which discusses this topic using packet analysis.
Stage 3: Independent Activity — Analyze and Discuss a New
Connection
The student is then asked to start a capture session of a connection to a Web site
of their own choosing. They are to stop the capture once the page has loaded.

Ethereal 127
The students must identify the three-way handshake that opened the connection,
noting the packet place in the capture sequence, TCP flags, sequence numbers,
and acknowledgment numbers.
By this stage, students are sometimes beginning to associate the three-way
handshake with an HTTP connection, which is fine when considering that HTTP
uses TCP but a harmful misunderstanding if they begin to assume that TCP
implies HTTP. A number of small tasks are usually performed during which
students capture an FTP, Telnet, and SMTP session of their own making.
Stage 4: Novel Situation, Troubleshooting and Diagnostic Problem-
Solving
Finally, the students are given a capture file of a denial-of-service SYN Flood
attack along with a scenario:
Clients were reporting that the network seemed slow when opening files.
You performed a packet capture from the file server, which is supplied.
Does this capture help explain the problem? What is happening? What
solution may be appropriate?
Figure 3. Student exercise

128 Bremer
We then discuss the traffic and the effect that this would have on the network.
The capture shows that the FIN, URG, and SYN bits are all set, which is almost
saying, “We are finishing a connection and beginning a connection while also
needing to pass some urgent data.” Students are asked to research the effect of
a flood of SYN flags. This allows a discussion of the resource limitation of
transmission control blocks (a device only has a limited number; one is used for
each packet received with a SYN flag set). A class discussion is encouraged to
reflect on the result of this strange combination. The detail of the conversation
is less important than the participation of students in actively engaging in thinking
about the repercussions of this type of traffic.
Stage 5: Reinforcement at a Later Stage
We return to this topic at a later stage when we discuss FTP in detail. During
those labs the students look into the way that FTP opens separate connections
for the data transfer. By the time the students are looking at the detail of the FTP
protocol, they can readily identify the new handshake occurring within the FTP
session.
Security and Political Issues: Our Experience
The use of a packet analyzer within a class is not without a number of risks, both
perceived and actual. The approach taken must vary between institutions and
will depend entirely on the institutional policies and relationship between the
academic department and the department that is charged with maintaining the
network. In some cases the network labs are separated from the institutional
network, either logically via a router or physically separated. Other labs are fully
integrated with the campus network.
In our situation we are able to install our own software within the computer suites
used in the networking classes; this is not the case for other computer suites.
However, we felt that it would be unethical and irresponsible to begin using
Ethereal in our classes without first discussing this with the department that
maintains our institution’s network. Initially the CIO (chief information officer)
was hesitant and referred us to the network engineer. He was very encouraging
and saw value in teaching students the use of what he viewed as an important
tool within his profession. From his perspective there was no issue with using

Ethereal 129
Ethereal as our network is fully switched; any workstation will only be able to
capture packets destined for or sourced from itself and broadcast packets.
It was decided that any information gained by students would be of minor
importance, resulting in a low probability of subsequent harm. At a later stage our
networking lab was placed behind a router and firewall so that we could teach
DHCP without upsetting our network neighbors. The separation provided by the
router, primarily to block DHCP broadcasts, also reduces the risk that students
may capture sensitive data originating outside of the lab.
It is recommended that all teaching staff consult with their IT support department
before proceeding with using a packet-capturing tool on the main institutional
network. The risk of harm on any reasonably well designed network (i.e., without
hubs) is exceptionally low. But it is always better to work alongside departments
that are responsible for maintaining an area rather than risk causing disputes due
to lack of consultation.
Student Evaluation
Students in all courses have the opportunity to complete a course evaluation
form. Following the introduction of Ethereal into the classes, we observed a
reduction in the negative comments stating that the course was too theoretical.
A number of students have commented that they value the experience of using
tools commonly used by network professionals.
Student Grades
We believe that there has been a minor improvement in the detail of the answers
in the written exam questions relating to topics in which Ethereal has been used.
However we have observed an increased enthusiasm in studying the protocols
via Ethereal and an increased richness in the classroom discussions during these
topics. The tool may not have dramatically improved the final understanding, at
least as measured by the final exam, but it appears to have made the topic more
pleasant to study. We have also observed students using Ethereal in other
courses to solve problems occurring when using networked-based applications.
Examples include students in subsequent courses using Ethereal to help in their
implementation of a DNS server, troubleshooting a client-server setup, and
troubleshooting an online booking package. This voluntary transference of skills
between courses was not expected but is pleasing.

130 Bremer
Conclusion
Packet sniffing with Ethereal gives students the ability to view the abstract
protocols as real artifacts that can be captured and examined. We have found
it to be a very useful tool that increases student engagement in the study of
various aspects of networking. The fact that students return to this tool to help
solve problems encountered within tasks in other courses is a strong recommen-
dation. Ethereal not only assists the learning of networking aspects but enhances
the students’ problem-solving tool set for use in other related topics. I now could
not imagine teaching protocols such as ARP, IP, TCP, and DHCP without using
a packet sniffer at some stage.
Summary
It is important that students grasp the basic concepts behind the operation of
commonly used protocols such as ARP, IP, TCP, and DHCP. Unfortunately, it
is difficult to motivate students to learn these protocols because many students
appear to find the topics technical and rather dry.
To overcome this problem many networking educators use software tools to
enhance teaching and learning network protocols in a practical way. This chapter
emphasizes the importance of hands-on learning activities in teaching and
learning various aspects of network protocols. By using Ethereal, students can
view the abstract protocols as real artifacts that can be captured and examined.
The tool not only assists students in developing a better understanding of network
protocols but also enhances the students’ problem-solving skills. The students
indicated that they had found Ethereal easy to use and helpful in gaining an
understanding of networking theories and concepts. In summary, this chapter
answers the question: How do we make the theoretical protocol a more concrete
reality for the students?
Concrete: Something that involves the immediate experience rather than an
abstraction. A “concrete learner” is someone who prefers learning prima-
rily through hands-on activities rather than by studying a theoretical model.

Ethereal 131
Ethereal: An open source implementation of a packet sniffer. Available freely
at http://www.ethereal.com.
Experiential learning: Learning as a continuous spiral of concrete experience,
observation and reflection, development of abstract concepts, and testing
in new situations.
GNU: Technically means “Gnu’s Not Unix” (a weak recursive pun). GNU is a
project run by the Free Software Foundation, established to produce a free
Unix-style operating system (not to be confused with Linux, even though it
often comes with some GNU tools). Ethereal uses the copyright license
(sometimes called “copyleft”) developed by this project (Free Software
Foundation, 1991).
Open source: A software distribution model in which the source must be
available to the user, and in addition anyone distributing the software must
do so for free and without any restriction being placed on anyone receiving
the code (apart from that defining open source). Refer to Open Source
Initiative (2004) for a more complete definition.
Packet sniffer: Also known as packet analyzer or just sniffer. Software that
captures network traffic and displays the data for analysis. The data is
normally interpreted in some way so that the user does not need to manually
identify the individual fields within a packet.
RFC: Request for comment. A set of documents that identifies issues, describes
best common practice, and defines standards for the Internet. Published by
the Internet Engineering Task Force (IETF).
SYN flood: A form of denial-of-service attack. The attacker sends a victim an
excessive number of packets that initiate the three-way handshake and
then does not follow up with further responses. This leaves the target
unable to deal with legitimate connection requests.
Three-way handshake: The initial exchange of messages that occurs when
two devices are establishing a connection using TCP. Understanding this
is essential to understanding the TCP connection and things that can
potentially go wrong with the connection.
Review Questions
1. List and describe three main features of a packet sniffer.
2. Explain how Ethereal can be used in the classroom to enhance teaching and
learning networking protocols.

132 Bremer
3. Define the following networking terms: ARP, IP, Ethereal, packet sniffer,
and DNS server.
4. Explain how Ethereal can be used in the classroom to teach ARP, IP, TCP,
and DHCP protocols in a practical way.
5. Explain how you would capture data traffic using Ethereal.
6. Describe further enhancements to the laboratory activities for packet-
forwarding concepts presented in this chapter.
References
Cameron, B. H., & Wijekumar, K. (2003). The effectiveness of simulation in a
hybrid and on-line networking course. In Proceedings of the 34th Special
Interest Group in Computer Science Education Technical Symposium
on Computer Science Education (pp. 117-119). New York: ACM Press.
Chappell, L. (2000, March). Inside the TCP handshake. NetWare Connection.
RetrievedApril27,2005,fromhttp://www.novell.com/connectionmagazine/
2000/03/hand30.pdf
Cigas, J. (2003). An introductory course in network administration. Proceed-
ings of the 34th Special Interest Group in Computer Science Education
Technical Symposium on Computer Science Education (pp. 113-116).
New York: ACM Press.
Comer, D. E. (2004). Hands-on networking with Internet technologies (2nd
ed.). Upper Saddle River, NJ: Prentice Hall.
Dewey, J. (1987). Experience and education. New York: Free Press. (Origi-
nal work published 1938.)
Francia, G. A., & Chao, C. (2004). Computer networking laboratory projects.
Journal of Computing Sciences in Colleges, 19(3), 226-237.
Free Software Foundation. (1991, June). GNU General Public License (Ver-
sion 2). Retrieved April 27, 2005, from http://www.gnu.org/licenses/
gpl.html
Holliday, M. A. (2003). Animation of computer networking concepts. Journal
of Educational Resources in Computing, 3(2), 1-26.
Insolvibile, G. (2001, June). The Linux Socket Filter: Sniffing bytes over the
network. The Linux Journal.
Jipping, M. J., Bugaj, A., Mihalkova, L., & Porter D. E. (2003). Using Java to
teach networking concepts with a programmable network sniffer. In

Ethereal 133
Proceedings of the 34th Special Interest Group in Computer Science
Education Technical Symposium on Computer Science Education (pp.
120-124). New York: ACM Press.
Kolb, D. A., & Fry, R. (1975). Toward an applied theory of experiential learning.
In C. Cooper (Ed.), Theories of group process. London: Wiley.
McDonald, M., Rickman, J., McDonald, G., Heeler, P., & Hawley D. (2001).
Practical experiences for undergraduate computer networking students.
Journal of Computing Sciences in Colleges, 16(3), 226-237.
Mechtly, B., & Decker, J. (2003). Using Ethereal and TCPportconnect in
undergraduate networking labs. Journal of Computing Sciences in
Colleges, 19(1), 289-298.
Open Source Initiative. (2004). The open source definition (Version 1.9).
Retrieved April 27, 2005, from http://www.opensource.org/docs/
definition.php
Orebaugh, A. D., & Ramirez, G. (2004). Ethereal packet sniffing. Syngress.
Papert, S. (1980). Mindstorms: Children, computers and powerful ideas.
New York: Harper Colophon Books.
Perez-Hardy, S. (2003). The use of network simulation to enhance network
curriculum. In Proceedings of the 4th Conference on Information
Technology Education (pp. 93-95).
Postel, J. (1981, September). Transmission Control Protocol (RFC 793).
Retrieved April 27, 2005, from ftp://ftp.rfc-editor.org/in-notes/rfc793.txt
Renfro, C. (1999). Basic packet-sniffer construction from the ground up:
Part 1. Retrieved April 27, 2005, from http://packetstormsecurity.org/
sniffers/Sniffer_construction.txt
Sarkar, N. I. (2005). LAN-Designer: A software tool to enhance learning and
teaching server-based LAN design. International Journal of Informa-
tion and Communication Technology Education, 1(2), 74-86.
Sharpre, R. (2004). Ethereal user’s guide: V2.00 for Ethereal 0.10.5.
Retrieved April 27, 2005, from http://www.ethereal.com/docs/user-guide/
Skinner, B. F. (1964). Technology of teaching. New York: Appleton-Century-
Crofts.

134 Bremer
Section III
Wireless Networking
andInformationSecurity

Enhancing Teaching and Learning Wireless Communication Networks 135
ChapterVIII
EnhancingTeaching
andLearningWireless
Communication
NetworksUsing
WirelessProjects
Abstract
Due to the rapid developments in wireless communication and networking
technologies and the high demand for wireless networking skills in the
industry worldwide, wireless communication and networking courses are
becoming increasingly popular in universities, polytechnics, and private
training institutions around the globe. Unfortunately, wireless
communication and networking is a challenging subject to teach in a
meaningful way because many students appear to find the subject technical,
dry, and rather boring. To overcome this problem, the authors introduce a
set of new projects in order to provide the students of wireless communication
and networking with a hands-on learning experience. The projects are
suitable for classroom use in introductory wireless networking courses.

136 Craig & Sarkar
Learning Objectives
• Discuss the usefulness of the wireless projects in teaching and learning
contexts.
• Explain how wireless projects can be set up for class demonstrations.
• Define the following key terms: ad hoc network, access point, infrastruc-
ture network, modulation, and wireless link.
Introduction
Wireless communication and networking is a challenging subject to teach in a
meaningful way because many students appear to find the subject rather dry and
technical and so quite boring. To overcome this problem, the authors have
prepared a set of projects in order to provide the students of wireless commu-
nication and networking with a hands-on learning experience. These projects are
designed around low-cost wireless modules and PC cards that are available from
local electronics shops. The projects are suitable for classroom use in introduc-
tory-level wireless networking courses. The effectiveness of these projects has
been evaluated by both students and a teaching team. The implementation of the
wireless projects was successful not only because of the positive student
feedback but also in that students scored better in the final exam. This chapter
describes these projects completed to date, their overall effectiveness, and our
plans for further projects. It also discusses the impact of wireless projects on
student learning and comprehension.
Wireless communication and networking courses are becoming increasingly
popular in universities, polytechnics, postsecondary colleges, and private training
institutions around the globe. This is partly because of rapid developments in
wireless communication and networking technology and the high demand for
wireless communication networks skills in the industry worldwide. Unfortu-
nately, it is difficult to motivate students to learn wireless communication and

networking fundamentals because many students appear to find the subject
rather dry, full of technical jargon, and boring. However, the view is frequently
supported in the educational literature (Anderson, Reder, & Simon, 1996; Young,
1993) that incorporating practical demonstrations into these courses, thereby
illustrating theoretical concepts and providing the opportunity for hands-on
learning experiences, significantly enhances student learning about wireless
communication and networking. Yet, despite the Chinese adage, attributed to
Confucius (551-479 BC), “I hear, I know. I see, I remember. I do, I understand,”
only a limited amount of material designed to supplement the teaching of wireless
communication and networking fundamentals is publicly available, as searches
of the Computer Science Teaching Center Web site (http://www.cstc.org/) and
the SIGCSE Education Links page (http://sigcse.org/topics/) on the Special
Interest Group on Computer Science Education Web site reveal.
We strongly believe, as do many others (Hacker & Sitte, 2004; Klassen &
Willoughby,2003;Lopez-Martin,2004;Moallem,2004),thatstudentslearnmore
effectively from courses that provide for active involvement in hands-on learning
experiences. To that end, we have prepared some interesting projects that
facilitate an interactive approach to learning wireless communication and
networking concepts. The first of these projects used the PIC sound generator
project described in Sarkar and Craig (2004) and the infrared (IR) signals
produced by a pair of TV remote controls. The second project involved setting
up a wireless link between two computers. This project used a pair of commer-
cially available receiver and transmitter modules which operate in the 2.4 GHz
band and have audio and video inputs and outputs, respectively. The third project
involved the students in experimenting with a Wi-Fi antenna. The fourth project
involved the students setting up a peer-to-peer wireless link using a pair of
computers fitted with commercially available Wi-Fi PC cards. Finally, several
such links were formed into a wireless network. These projects can be used
either in the classroom as a demonstration to enhance the lecture environment
or in the laboratory to provide a practical hands-on learning experience in
wireless communication and networking fundamentals.
Wireless communication and networking is described in many textbooks (e.g.,
Holloway, 2003; Rappaport, 2002; Sikora, 2003). A number of sophisticated
network simulators exist for building a variety of network models (Commsimm,
2001; Fall & Varadhan, 2003; Jipping, Bugaj, Mihalkova, & Porter, 2003;
McDonald, 2005). Nevertheless, by setting up and configuring actual wireless
communication networks, the students gain firsthand experience that cannot be
gained through computer simulation and modelling.
This hands-on learning approach to teaching and learning wireless communica-
tion and networking was first trialled during semester 2 of 2004 in the E-business
IT Infrastructure undergraduate course at Auckland University of Technology

138 Craig & Sarkar
(AUT). This course covers various aspects of wireless communication and
networking.
The focus of the projects discussed in this chapter has been on preparing
demonstration projects to support teaching wireless communication and net-
working fundamentals. These projects are described in the next section, while
the effectiveness and the main benefits of wireless projects as a means of
enhancing the teaching and learning of wireless networking fundamentals are
discussed in the remainder of the chapter. A brief conclusion section ends the
chapter.
Project Description
Table 1 lists the six projects that have been developed and trialled during a period
of one semester in the E-business IT Infrastructure undergraduate course at
AUT.
Project 1: Infrared Remote Controls
Attention is drawn in Wesel (1998) to the similarities between communication
links that utilize IR and wireless links that utilize radio transmission in the 2.4 GHz
band. The first project exploits these similarities as a means of introducing Wi-
Fi to students via a technology with which they are already familiar — IR remote
control units. Project 1 uses an IR-detector module from a dismantled computer
to detect the IR pulse-modulated signals produced by a pair of TV remote
controls. The IR detector and power supply were assembled on a breadboard as
Table 1. Wireless projects and related wireless networking concepts
Projects Wireless networking concepts
1. Infrared (IR) IR transmission link; signal interference; modulation / demodulation
2. 2.4 GHz wireless link FM transmission; encoding and decoding; microwave radiation, wireless
link throughput
3. Wi-Fi Antenna External Wi-Fi antenna; signal strength; response time and throughput
4. Ad hoc network Peer-to-peer networking; file sharing; security
5. Infrastructure network Infrastructure-based network; centralised network control; wireless
access point , basic service set, Extended service set
6. Network security Access control; Firewalls; encryption; SSID

shown in Figure 1. The IR detector is the black unit on the right-hand side of the
PCB. When the detector unit receives an IR signal, it turns on a transistor, which,
in turn, drives the LEDs seen on the left side of the PCB. The switch in the centre
of the PCB enables the transistor to be turned on in the absence of an IR signal,
as seen in Figure 1. The output from the IR detector was captured on a Tektronix
2230 storage oscilloscope, which is seen together with the remote control units
in Figure 2.
The same signals were also fed to the PIC sound generator project described in
Sarkar and Craig (2004), where they were filtered and then passed to the audio
amplifier built into that project. As a result, students could both see and hear
representations of the IR signals being produced by the two remote control units.
Figure 3 shows the signal train produced by a single remote control. In Figure 4,
the overlapping of the IR signals produced by a pair of TV remote controls when
one controller is operated slightly later than the other can be seen. The
importance of the receiver being able to distinguish between overlapping signals
Figure 1. Testing the infrared detector
Figure 2. Two IR remote controls and a display of their signals

140 Craig & Sarkar
can be well demonstrated by the refusal of devices (such as a TV set) to react
as expected when both remote control units are used simultaneously. The
storage oscilloscope can be used to capture also a display of the serial signal used
to control the LCD display described in Sarkar and Craig, as well as the RS232C
signals produced by the project described in Corcoran and Lusted (2004). Many
students have indicated that they found being able to experience in new ways
something as familiar to them as a TV remote control unit was both enlightening
and intriguing, and they were thus better able to appreciate the behaviour of a
wireless communication link.
In completing this project, students develop a better understanding of IR
transmission link, signal interference, and modulation techniques.
Figure 3. The signal produced by a single remote control unit
Figure 4. The overlapping signal trains from the two remote control units

Project 2: A 2.4 GHz Wireless Link
Leading on from the first project, this project endeavors to provide students with
an appreciation of the characteristics of another part of the electromagnetic
spectrum, namely, microwave radiation as an information carrier. The project is
based around two commercially available kits (from Oatley Electronics,
www.oatleye.com), which comprise an FM transmitter and a matched receiver.
These modules are pre-tuned to one of four frequencies within the 2.4 GHz band.
Again, students will be familiar with the some aspects of the technology involved
through their experience with FM broadcasting and TV broadcasts, although
these services operate at lower frequencies than Wi-Fi. The kits were installed
in plastic project boxes, and the transmitter was fitted with a socket so that it
could be fitted with an external antenna, as seen in Figures 5 and 6.
The transmitter module has inputs for both audio and video. In this project, only
the audio inputs were utilized, these being connected to the speaker jack on the
sound card of a PC (computer A). Similarly, the receiver has audio and video
outputs, but only the audio outputs were utilized, these being connected to the
line-in socket on the sound card of a second PC (computer B). Students could
then arrange to play a music CD on computer A and listen to the contents of the
CD on computer B via the radio link. The influence of the distance between the
transmitter and the receiver, the polarization of the respective antennas, the
presence of obstacles between the transmitter and the receiver, as well as
interference by out-of-phase reflected signals and the polarization of the signal
were all easily observable via the changing quality of the music produced by
Figure 5. Linking a laptop computer (foreground) with a benchtop computer
(background) via a wireless link

142 Craig & Sarkar
computer B. The ability to switch between the four different channels within the
2.4 GHz band that are built into the modules would enable channel-hopping to be
explored as a future project using a PIC microcontroller. The currently active
channel is indicated by one of the LEDs seen in Figure 6.
In completing this project, students develop a better understanding of FM
transmission, the effect of transmitter-receiver separation, polarization of the
antennas, obstacles between the transmitter and the receiver, as well as
interference by out-of-phase reflected signals on wireless link throughput.
Project 3: Wi-Fi Antenna
The transmitter module in Project 2 was fitted with a BNC socket so that an
external antenna could be attached. Numerous antenna designs have been
published (Clark, 2003; Gardelli, La Cono, & Albani, 2004), and students were
encouraged to consult these sources and to build an antenna of their own design.
One such endeavour, consisting of the bow-tie PCB antenna supplied by the
module manufacturer (from Oatley Electronics, www.oatleye.com) coupled
with a CD disc used as a reflector, can be seen in Figure 6. The student’s work
does not need to be an elaborate design for it to be an effective means of
engendering student interest and confidence. In fact, the wireless can be
established with a 50-ohm terminator (as used in Ethernet networks) connected
to the transmitter antenna socket, provided the receiver and transmitter modules
are located within a few meters of each other. This link however is easily broken
if the separation between the modules is increased to around 5 meters. The
influence of objects in or near the signal path is more apparent when the signal
Figure 6. Close-up view of the transmitter and receiver modules

strength is restricted in this way, one indicator of the link quality being the quality
of the sound produced by the receiving computer (B). A second way of
determining the strength of the signal being received by the receiving computer
is to use either a proprietary software program, such as NetStumbler (2004), or
the program that is provided within Windows XP (by double-clicking on the
Network Connection icon on the status bar). Projects 1 and 2 appear to provide
students with a qualitative grasp of the behaviour of IR and radio links, thereby
preparing them to set up a peer-to-peer link between two computers using
commercially available Wi-Fi computer cards, as described next.
Project 4: Ad Hoc Network
The basic concept of wireless ad hoc networks and their potential application
areas are discussed during lectures. This project showed students how to set up
a wireless ad hoc network. In addition, students were able to investigate the
effect of transmitter-receiver separation, floors, and line-of-sight blockage on
the file transmission time as well as link throughput of a typical IEEE 802.11b
wireless local area network (WLAN) in peer-to-peer mode. The project involved
the installation of two IEEE 802.11b Wi-Fi PC computer cards, purchased from
an electronics store, in a pair of PCs. This procedure is well documented in
textbooks such as Carter and Whitehead (2004), and most of the students found
little difficulty in completing this step. Of greater interest to them was the
question of how to achieve the transmission of the same music that they had
become acquainted with through the 2.4 GHz FM wireless link. Should the file
on the CD be sent as a compact disc audio track file (cda file) or should it be sent
as a bit stream? In completing this project, students gain a better understanding
of the operation of wireless ad hoc networks.
Project 5: Infrastructure Network
When more than two computers are to be connected, it is necessary to have a
means of controlling the communication between each computer. In an infra-
structure network, this task is allocated to a wireless access point (AP). The APs
are more expensive than computer Wi-Fi cards, but only one is needed for a small
network. The basic concepts of wireless access points, infrastructure-based
wireless LANs, basic service set (BSS), and extended service set (ESS) are
introduced during lectures. This project shows students how to set up an
infrastructure-based network. As in Project 4, the procedure for setting up an
infrastructure network is well documented, as in Carter and Whitehead (2004),
and most students are able to complete this extension of their network with little

144 Craig & Sarkar
supervision. In completing this project, students gain hands-on experience in
setting up a wireless infrastructure network and develop a better understanding
of its uses, benefits, and limitations.
Project 6: Network Security
This project demonstrates to students the basic concept of wireless network
security (Khan & Khwaja, 2003; Lin, Sathu, & Joyce, 2004). In lectures, the
basic concept of wireless LAN security and related issues and challenges were
introduced. These concepts were reinforced when the students were setting up
Project 4 and Project 5, in accordance with the procedures described in Carter
and Whitehead (2004), because the information required when setting up the
network software requires a good knowledge of both network operation and
terminology, for example, terms such as service set identifier (SSID), access
control, and Media Access Control (MAC) address.
Additional Projects
The following projects are being considered:
• Integrating Wi-Fi with PIC projects: The hands-on learning activities
include using a Wi-Fi radio link to control a PIC microcontroller.
• IEEE 802.11a/g: The learning activities include experimenting with
OFDM (orthogonal frequency-division multiplexing) technology and the 5
GHz radio spectrum.
• Open: A category for student-suggested projects.
of Wireless Projects
The wireless projects described in this chapter provide the following benefits:
• Hands-on: Wireless projects facilitate an interactive learning experience
in wireless communication and networking.

• Easy to use: Wireless projects are easy to use and set up for demonstra-
tions.
• Low cost: Wireless projects can be built with limited resources and budget
(e.g., within a few hundred dollars).
• Reusability: Some hardware components of Wi-Fi projects can be reused
in developing a variety of other projects.
• Usefulness: The wireless projects can be used either in the classroom or
in the laboratory to provide hands-on learning experiences in wireless
communication and networking.
• Challenging: Wireless projects provide a challenging, yet friendly environ-
ment in which students can test their knowledge of wireless communication
and networking.
Classroom Experiences with
Wireless Projects
Our experiences with the wireless projects have been favorable overall. The
wireless projects were easy to use and set up for demonstrations, and it was
observed that by participating in the wireless projects and demonstration
activities, students became increasingly motivated to learn more about wireless
communication networks and enjoyed this course more than previous courses
that consisted of lectures only. The authors seek feedback regularly both from
students and staff for further improvement of the demonstration materials.
The wireless projects were offered as a capstone project to two undergraduate
diploma students, who carried out the project in the final semester towards the
diploma in information technology (DipIT) qualification. The students had
completed most of the courses required for a DipIT qualification, including data
communications and computer networking, before taking up the wireless projects.
The students achieved the following learning outcomes: (1) set up a wireless link
using IR technology; (2) set up both ad hoc and infrastructure-based wireless
LANs; (3) design a Wi-Fi booster antenna; (4) set up Wi-Fi projects for class
demonstration and evaluate the effectiveness of the projects through student
feedback; (5) write a report containing requirements analysis, a project plan,
minutes of meetings, summary of findings, and reflective statements; and (6)
give an oral presentation to an audience of staff and students.
The wireless projects were completed successfully, and the students indicated
that they had learnt quite a lot about wireless communication and networking

146 Craig & Sarkar
through the hands-on experience that the wireless projects provided. This is
evident in the students’ reflective statements, which follow:
“I learnt quite a lot about Wi-Fi technology and networking by doing hands-on
projects.”
“Even though we had passed the ‘Data communication and networking’ courses
before taking up the Wi-Fi projects, we did not learn much about the practical
aspects of wireless communication and networking until we carried out the Wi-
Fi projects.”
“Wireless communication and networking should be taught using hands-on
learning activities as we did with the Wi-Fi projects.”
Impact of Wireless Projects on
Students’ Performance
The wireless projects were trialled as a class demonstration in the E-business IT
Infrastructure (EBITI) undergraduate course in semester 2 of 2004. The EBITI
(Petrova, 2000) course is at level 6, or 1st-year degree level, and constitutes 15
credit points (52 contact hours) at AUT. Until this trial, the wireless communi-
cation and networking course was taught through of a series of lectures and
tutorials only.
To estimate (quantitatively) the impact of the wireless projects and demonstra-
tions on student learning and comprehension, the class was given an assessment
test (multiple-choice questions) on wireless communication networks before the
projects were introduced. Then, after the entire class had an opportunity to gain
hands-on experience with the wireless projects, the same test was given again
to measure any change in student learning and comprehension.
The class consisted of 11 students, five female and six male. While not a
particularly large group, it was at least a diverse mix. The examination consisted
of 19 multiple-choice questions covering various aspects of wireless and mobile
networking technology, including ad hoc and infrastructure wireless LANs,
Bluetooth, and wireless security (see Table 3 for assessment test questions).
Table 2 shows results of these tests. The question numbers of the 19 multiple-
choice questions are indicated in the first column. The fraction of the students
in the class who answered correctly (expressed as a percentage) in each of the
19 questions in the class test before and after they had experience with the
wireless projects is shown in columns 2 and 3, respectively. As seen in Table 2,

on each of the 19 questions, the class as a whole showed an improvement ranging
from 8% to 100%, and the overall improvement for the test is 33%. Because the
tests (before and after) were conducted among students having the same
background and who had been exposed to the same theoretical material, it is
considered that much of this improvement can be accounted for by the effect of
the practical experience that the students gained from the wireless projects.
Table 2. Impact of wireless projects on student learning and comprehension
Percentage of class
answering correctly
Question
Before After
Improvement (%)
1 33 100 67
2 67 91 24
3 11 73 62
4 56 91 35
5 44 100 56
6 33 64 30
7 0 100 100
8 67 91 24
9 56 64 8
10 22 36 14
11 22 82 60
12 22 36 14
13 56 64 8
14 44 91 46
15 56 64 8
16 22 55 32
17 56 64 8
18 22 45 23
19 33 45 12
Overall 38 71 33

148 Craig & Sarkar
Table 3. Assessment test (maximum time allowed to complete is 20 minutes)
1 What is the maximum distance an IEEE 802.11b network can cover?
a) 100 meters
b) 10 meters
c) 1000 meters
d) 20 meters
2 What is the maximum theoretical speed of IEEE 802.11b and IEEE 802.11g?
IEEE 802.11b IEEE 802.11g
a) 12 Mbps a) 12 Mbps
b) 54 Mbps b) 54 Mbps
c) 22 Mbps c) 22 Mbps
d) 11 Mbps d) 11 Mbps
3 What security protocols are commonly used in Wi-Fi?
a) MAC address restrictions
b) WEP Key 64/128 bit
c) BLT on rye
d) USB access key
4 What does SSID stand for?
a) Super Security Implementation Device
b) Seismic Standard Identification Deployment
c) Service Set IDentifier
d) Slow Service IDentifier
5 What is the difference between WEP and MAC filtering?
a) One’s hardware and one’s software
b) They’re the same thing
c) One is a pie protocol
d) WEP has a greater maximum distance
6 What is a MAC address?
a) Location of the closet Mac Donald’s
b) Management Address Character for Wi-Fi
c) The Numeral ID of your network card
d) Closet reseller of Mac Trucks
7 What is the difference between an Ad-hoc and an Infrastructure network?
8 What are hotspots?
a) Something you should avoid standing on
b) Areas that you can get open assess to a Wi-Fi Network
c) Areas on the Sun that are brighter
9 Which of the following characteristics differ between Bluetooth and Wi-Fi?
a) Speed
b) Frequency
c) Distance
d) Cost
10 List three advantages of wireless LANs over wired networks
11 List three disadvantages of wireless LANs over wired networks
12 What is DHCP?
a) A protocol that assign your computer an IP address?
b) A devise that lets Wi-Fi dial up ADSL
c) Decipher Help Character Protocol
d) Transdimensional Gateway to Pluto
13 What other common household items use the same frequency as Wi-Fi?
a) Cell Phone
b) Microwave
c) Cordless Phone
d) Sky Box

Conclusion and Future Work
A series of interesting projects has been developed, which can be used either in
the classroom for class demonstrations to enhance the traditional lecture
environment or in the computer laboratory for hands-on practical work at an
introductory level. The wireless projects described in this chapter are easy to use
and set up for class demonstrations. The projects consist of inexpensive and
widely available modules and kits and are thus likely to be within reach of even
already extended budgets. Student responses to the project demonstrations were
mostly favorable. The students indicated that they had found the wireless
projects easy to use and helpful in gaining an understanding of wireless
communication and networking fundamentals. The wireless projects demonstra-
tion has had a positive impact on student learning and comprehension.
More projects such as IEEE 802.11a, IEEE 802.11g, and integrating Wi-Fi and
PIC are being prepared. These materials are available to faculty interested in
using the wireless projects to supplement their wireless communication and
networking courses or as the basis for more complex projects. More information
about the wireless projects and demonstration materials can be obtained by
contacting the first author.
Table 3. cont.
14 What does Wi-Fi stand for?
a) Wired-Fiction
b) Wireless-Fitting
c) Wireless-Fidelity
d) Wired-Fix
15 Can a Wi-Fi network replace a wired network in every case?
a) No
b) Yes
c) No clue what so ever
16 Is all Wi-Fi equipment compatible?
a) No
b) Yes
17 Is each Wi-Fi a secure network?
a) Yes, better than wired networks
b) No, Worse than wired networks
c) Yes, Equal to wired networks
18 Does it cost more to set a Wi-Fi network than a wired network?
a) Yes, a lot more than a wired network
b) Yes, but not much more than a wired network
c) No, The same
d) No, a lot cheaper than a wired network
19 An access point is required to set up a wireless LAN.
a) False
b) True

150 Craig & Sarkar
Summary
This chapter describes a set of hands-on wireless projects that can be used either
in the classroom to enhance traditional lecture environment or in the laboratory
to provide hands-on learning experience in wireless communication networks.
The wireless projects are designed around low-cost modules and PC cards that
are available from local electronics shops. The effectiveness of these projects
has been evaluated by both students and a teaching team. The students indicated
that they had found the wireless projects easy to use and helpful in gaining an
understanding of wireless communication and networking fundamentals. The
wireless projects demonstration has had a positive impact on student learning and
comprehension.
Ad hoc network: A class of wireless networking architecture in which there is
no fixed infrastructure or wireless access points. In ad hoc networks, each
mobile stations.
IEEE 802.11: Generally refers to wireless LAN standards. The IEEE 802.11
is the wireless LAN standard operating at 2.4GHz.
Infrared: Electromagnetic waves whose frequency range is above that of
microwave but below the visible spectrum. The applications of infrared
technology include TV remote control and wireless LAN systems.
Infrastructure network: A class of wireless networking architecture in which
ture and centralized control.
PIC microcontroller: PIC stands for programmable interface controller. A
PIC microcontroller is an on-chip computer containing CPU, memory,
programmable ROM, and input/output ports.
Wi-Fi antenna: This term generally refers to an antenna used with Wi-Fi
equipment to enhance the transmission and reception of the wireless signals
used in the transfer of data between the sending equipment and the intended
receiving equipment.

Wireless link: Generally refers to a pathway for the transmission of information
via a modulated unconstrained electromagnetic wave.
Review Questions
1. List and describe three main benefits of using the wireless projects.
2. Discuss the usefulness of the wireless projects in teaching and learning
contexts.
3. Discuss the difference between an ad hoc wireless LAN and an infrastruc-
ture LAN.
4. Define the following wireless key terms: modulation, wireless link, Wi-Fi
antenna, ad hoc network, and infrastructure network.
5. Describe how an infrastructure wireless LAN can be set up for demonstra-
tion.
6. Explain how the basic concept of wireless network security can be
reinforced using Project 6 described in this chapter.
7. Describe further enhancements to the wireless projects.
References
Carter, P., & Whitehead, T. (2004). Teach yourself visually wireless network-
ing. Wiley.
Clark, R. (2003, August). Home-brew weatherproof 2.4GHz WiFi antennas.
Silicon Chip, 16, 42-48.
Commsim 2001: Network & Communications Simulation [Computer software].
(2001). Toronto, Ontario, Canada: Electronics Workbench.
Corcoran, P., & Lusted, K. (2004). Teaching programming techniques for
embedded microcontrolllers:Back to basics with 8-bit RISC
microcontrollers. Retrieved December 12, 2004, from www.ulst.ac.uk/
cticomp/corcoran.html

152 Craig & Sarkar
Gardelli, R., La Cono, G., & Albani, M. (2004). A low-cost suspended patch
antenna for WLAN access points and point-to-point links. Antennas and
Wireless Propagation Letters, 3(6), 90-93.
203.
Holloway, D. (2003). Wireless networking: A guide to wireless networking
and deployment. Retrieved September 25, 2003, from http://www.hill.com/
archive/pub/papers/2003/01/paper.pdf
Jipping, M. J., Bugaj, A., Mihalkova, L., & Porter, D. E. (2003). Using Java to
teach networking concepts with a programmable network sniffer.
Paper presented at the Proceedings of the 34th Technical Symposium on
Computer Science Education (SIGCSE’03), Reno, NV (pp. 120-124).
Khan, J., & Khwaja, A. (2003). Building secure wireless networks with
802.11. Wiley.
Klassen, K. J., & Willoughby, K. A. (2003). In-class simulation games: Assess-
ing student learning. Journal of Information Technology Education, 2,
1-13.
Lin, C.-T., Sathu, H., & Joyce, D. (2004, July). Wireless network security.
Paper presented at the 17th annual conference of the National Advisory
Committee on Computing Qualifications (NACCQ), Christchurch, New
Zealand (pp. 337-340).
Lopez-Martin, A. J. (2004). Teaching random signals and noise: An experimen-
tal approach. IEEE Transactions on Education, 47(2), 174-179.
McDonald, C. (2005). The cnet network simulator (Version 2.0.9). Retrieved
January 10, 2005, from www.csse.uwa.edu.au/cnet/
Moallem, M. (2004). A laboratory testbed for embedded computer control. IEEE
Transactions on Education, 47(3), 340-347.
NetStumbler [Computer software]. (2004). Retrieved January 15, 2004, from
www.netstumbler.com
Petrova, K. (2000). Teaching electronic commerce: An information technology
infrastructure design & management approach. New Zealand Journal of
Applied Computing & Information Technology, 4(1), 70-77.
Rappaport, T. S. (2002). Wireless communications—Principles and practice
(2nd ed.). NJ: Prentice Hall.
Sarkar, N. I., & Craig, T. M. (2004, March 3-7). Illustrating computer
hardware concepts using PIC-based projects. Paper presented at the
35th SIGCSE Technical Symposium on Computer Science Education,
Norfolk, VA (pp. 270-274).

Sikora, A. (2003). Wireless personal and local area networks. Wiley.
Wesel, E. K. (1998). Wireless multimedia communications—Networking
video, voice and data. Addison-Wesley.
Technology, 41(1), 43-58.

154 Siringoringo & Sarkar
ChapterIX
TeachingandLearning
Wi-FiNetworking
FundamentalsUsing
LimitedResources
Wilson Siringoringo, Auckland University of Technology, New Zealand
Abstract
Wi-Fi networking has been becoming increasingly popular in recent years,
both in terms of applications and as the subject of academic research
papers and articles in the IT press. It is important that students grasp the
basic concepts of both Wi-Fi networking and wireless propagation
measurements. Unfortunately, the underlying concepts of wireless
networking often intimidate students with their apparently overwhelming
complexity, thereby discouraging the students from learning in-depth this
otherwise exciting and rewarding subject. This chapter provides a tutorial
on Wi-Fi networking and radio propagation measurements using wireless
laptops and access points. Various hands-on learning activities are also
discussed.

Teaching and Learning Wi-Fi Networking Fundamentals 155
Learning Objectives
• Describe the architecture of Wi-Fi networks.
• Discuss the evolution of IEEE 802.11 standards.
• Set up Wi-Fi networks for class demonstration.
• Suggest future enhancements to the practical activities described in the
chapter.
Introduction
In recent years, Wi-Fi networks (also called IEEE 802.11b) have been gaining
in popularity, both in business and in home networking applications. With the
growing proliferation of mobile equipment, this trend is likely to continue in the
future. It is therefore important for students of information and telecommunica-
tion technologies to cover the fundamentals of wireless networking technologies
as part of their curriculum.
Many people find that networking technology in general is somewhat arcane and
difficult to understand. Similarly, the apparently overwhelming complexity of the
underlying concepts of wireless networking often intimidates students. This
perception can easily discourage the students from learning in-depth this
otherwise exciting and rewarding subject.
This chapter attempts to overcome these problems by providing a hands-on
introduction to Wi-Fi networking. A tutorial is also included to guide learners on
how to set up Wi-Fi networks using relatively few computing resources.
Although a host of problems are to be expected, given the technical limitations
of commercially available hardware, students are encouraged to gain a hands-
on learning experience in setting up Wi-Fi networks. The chapter also discusses
the effectiveness, measured by student feedback, of Wi-Fi projects.

Background
Nowadays business organizations rely heavily on computer networks for their
operation. The trend towards mobile communication and computing drives the
networking industry further towards wireless technology — particularly Wi-Fi
technology. As explained later in this chapter, the term Wi-Fi refers to the IEEE
802.11 standard for wireless LAN (WLAN). Therefore the terms Wi-Fi, IEEE
802.11, and WLAN are used interchangeably in this chapter.
Kaczman (2002) reports that an estimated 1 to 1.5 million Wi-Fi communication
cardsandWi-Fi-enabledlaptopsweresoldeverymonthduring2002.Vaxevanakis
et al. (2003) offer similar sales projections in their reports.
Wireless networks, especially the ones employing Wi-Fi technology, are gaining
popularity not only in the business domain but also with home users (Vaxevanakis
et al., 2003). The reasons for the popularity of wireless networks over the wired
ones are highlighted below (Proxim, 1998):
• Mobility: Wireless LANs can provide users with real-time information
within their organization without the restrictions inherent with physical
cable connections.
• Installation speed and simplicity: The installation of wireless LANs
does not involve the tedious work of pulling cables through walls and
ceilings.
• Installation flexibility: Wireless LANs allow access from places un-
reachable by network cables.
• Cost of ownership: Overall installation expenses and life-cycle costs of
wireless LANs are significantly lower than wired LAN. The discrepancy
is even higher in dynamic environments requiring frequent moves and
changes.
• Scalability: Wireless LANs can be configured relatively easily since no
physical arranging of network cables is required.
Although wireless networks may never completely replace wired networks, they
will gain in importance as business assets in the future. Howard (2002) reports
that the use of wireless networks for mobile Internet access is also becoming big
business, as is indicated by the rising number of wireless Internet service
providers in the United States. The increasing number of public hotspots also

opens the possibility of providing continuous connection to a roaming business
traveller (Vaughan-Nichols, 2003).
Motivation
Wireless technology is likely to continue evolving at rapid a pace in the near
future.
Further developments will mainly involve bandwidth increase and optimization,
which enable performance improvement in terms of throughput and reliability. In
anticipation of the availability of increased bandwidth, various network-based
business and multimedia applications are also being developed. Prasad and
Prasad(2002)discusssomeapplicationssuchasteleconferencing,telesurveillance,
and video-on-demand operating on wireless network backbones.
Given the importance of research and implementation of Wi-Fi networking in the
future, students need to prepare themselves by gaining a thorough understanding
about the technology. An overview is presented to introduce the students to the
significance of wireless networking technology from a technical standpoint. To
facilitate a hands-on learning experience, a tutorial for setting up a Wi-Fi network
is also provided.
IEEE 802.11 Wireless LAN
A wireless network is a data communications system which uses electromag-
netic media such as radio or infrared waves instead of cables. Wireless networks
are implemented either to complement or as an alternative to a wired network.
The most prominent feature of wireless networks is mobility, which provides
users with freedom of movement while maintaining connectivity. Flexibility is
another great advantage of wireless networks since they allow connectivity to
places physically inaccessible to network cables.
The application of wireless networks is not confined only to substituting for wired
networks. It also enables communication schemes not available in wired
networks. With the proliferation of mobile computers and handheld devices such
as PDAs and cellular phones, the role of wireless networks is becoming more
important as a means of data exchange.
In more general terms, there are currently three primary applications for wireless
network technology:

1. Wireless local area network (WLAN): A class of wireless LAN which
provides wireless connectivity within an organization. WLAN enables
access to a corporate network by individual users without hindering their
mobility. Access to WLAN is provided within a defined physical region,
such as within an office building.
2. Wireless personal area network (WPAN): The main role of WPAN is
to simplify the communication process by eliminating the need for physical
connection through cables at home. For example, linking all electronics
devices at home using radio technology operating at 2.4 GHz.
3. Wireless wide area network (WWAN): This provides wireless access
to users outside the boundaries of WLAN. Currently, cellular technologies
play the main role in making WWAN feasible. Typical example of WWAN
use is when a user gets access to e-mail or Web sources through a mobile
phone.
Several standards have emerged to implement the wireless network technology
in the three areas above. The Bluetooth standard (IEEE 802.15) is now
dominating the WPAN implementation, whereas the IEEE 802.11 family of
specifications is now standard for WLAN implementations. In the WWAN
domain, several mobile communication technologies such as GSM, GPRS, and
CDMA 2000 are still competing with each other to become the ultimate standard.
Overview
The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards
define the protocols at the physical (PHY) and MAC layers. The MAC layer
makes the lower part of the data link layer in the OSI model as shown in Figure 1.
At the physical layer, three different transmission techniques are used by 802.11:
frequency hopping spread spectrum (FHSS), direct sequence spread spectrum
(DSSS), and infrared (IR). For the 802.11b specification, only the direct
sequence spread spectrum is used. Other popular standards, such as Bluetooth,
use frequency hopping spread spectrum instead, although it shares the 2.4 GHz
band used by 802.11b.
The original 802.11 standard uses an 11-bit chipping code called the Barker
sequence to send data via radio waves. Each 11-bit sequence represents one
single bit of data. A transmission technique called binary phase shift keying
(BPSK) is used to transmit the sequences at the rate of 1 million per second,
which corresponds to the basic 1 Mbps data transfer rate of the 802.11. A more
sophisticated technique referred to as quadrature phase shift keying (QPSK) is
used to achieve a 2 Mbps data transfer rate.

Instead of Barker sequences, the 802.11b uses Complementary Code Keying
(CCK). When CCK is used, a 16-bit sequence transmitted over the radio channel
contains either 4 or 8 information bits and can achieve data transfer rates of 5.5
Mbps and 11 Mbps, respectively.
At the MAC layer, the fundamental protocol component specified by the 802.11
is the distributed coordination function (DCF). The DCF utilizes a Carrier Sense
Multiple Access with Collision Avoidance (CSMA/CA) channel access method.
When a station realizes that no other has transmitted within a predetermined time
called the interframe space (IFS), it transmits its own frame. In unicast
transmission, the receiving station is expected to reply with an acknowledgment
(ACK), in a similar fashion to the standard automatic repeat request (ARQ)
control mechanism. A mechanism called backoff procedure is used by DCF to
Figure 1. IEEE 802.11 in the OSI layer

prevent frame collision, which results from stations transmitting simultaneously
(Golmie et al., 2003).
To complement the DCF, an optional component at the MAC layer, referred to
as point coordination function (PCF), provides a centralized, polling-based
access mechanism. To utilize PCF, an AP is required to perform the point
coordination function. The PCF is an optional feature of the IEEE 802.11 MAC
layer and is not supported by all Wi-Fi devices.
In PCF, the AP acts as the central access coordinator. It applies the round robin
algorithm to poll thestations withinthe serviceset. UnlikeDCF, stations wishing
to transmit data must first obtain permission from the AP using the request-to-
send and clear-to-send (RTS/CTS) scheme. When a polled station does not have
data to transmit, it sends a null frame. Otherwise the station is allowed to transmit
its data frame (Youssef et al., 2002).
Wi-Fi Transmission Issues
The use of the unlicensed 2.4 GHz radio band for Wi-Fi transmission medium
leads to interference problems. In most countries the 2.4 GHz spectrum is
crowded with other radio devices such as cordless phones, microwaves, and
Bluetooth WPAN devices. Due to the effect of radio interference, Wi-Fi
performance degrades. With the ever increasing popularity of Bluetooth WPAN,
the potential problem of interference becomes sufficiently serious to compel
researchers to find mechanisms that allow Wi-Fi and Bluetooth to coexist (Ophir
et al., 2004).
Wi-Fi networks have limited range, typically covering up to 46m indoors and
100m outdoors from the nearest access point (Ferro & Potorti, 2005). While
significantly wider than Bluetooth coverage, which is 10m, performance degra-
dation can be an issue when a station is located near the limit of Wi-Fi range from
the other station or the access point.
The use of radio broadcast also raises security concerns. Unlike wired network
where access is limited by physical cable connections, any device within range
of Wi-Fi network can intercept the packets and potentially intrude into the
network. This potential threat necessitates the use of data encryption in order to
minimize the risk of intrusion.
Wi-Fi Network Design Issues
The basic building block of a wireless network is the basic service set (BSS). A
BSS consists of a set of fixed or mobile Wi-Fi stations. The simplest network

configuration is the independent BSS (IBSS), which is an ad hoc network
consisting of two or more stations without any structure other than peer-to-peer
cooperation.
When a set of BSSs are connected by a fixed network infrastructure, the
resulting structure is called an extended service set (ESS). An ESS is a set of one
or more BSSs connected by a distribution system (DS), which is not specified by
the IEEE 802.11 standard. The DS can take the form of wired networks or some
other form of wireless network. A Wi-Fi network with all the typical components
is illustrated in Figure 2.
The stations connected to the DS are called access points (APs). An AP offers
distribution system services, which allow data exchange between stations of
different BSSs. An AP normally performs a function called point coordination
(PC), which employs a round robin policy to poll each station for data transmis-
sion.
802.11 Standard Family
The IEEE released the 802.11 standard for wireless LAN (WLAN) in 1997. The
specification requires a data transfer rate of from 1 Mbps up to 2 Mbps while
Figure 2. A typical Wi-Fi network with ESS structure

retaining compatibility with existing LAN hardware and software infrastructure.
The standard defines protocols for MAC layer and physical transmission in the
unlicensed 2.4 GHz radio band. After successful implementation by commercial
companies such as Lucent Technologies, amendment was made for a better
performance in the same year. The resulting standard was IEEE 802.11b, which
specifies higher data transfer rates of 5.5 and 11 Mbps.
The IEEE 802.11b differs from the 802.11 in the MAC layer even though it
retains compatibility with its predecessor. The physical layer is left unchanged.
The 802.11b standard was approved in 1999, and during that year the term
wireless fidelity or Wi-Fi was introduced. The IEEE 802.11b has proven to be
very successful in the commercial domain. The majority of Wi-Fi devices
nowadays are made to the 802.11b standard.
In parallel with the IEEE 802.11b, another variant of the original 802.11 was also
made. This variant is referred to as IEEE 802.11a, which differs from both IEEE
802.11 and IEEE 802.11b by using the 5 GHz band rather than the 2.4 GHz band.
The 5 GHz radio band is unlicensed in the United States but not in many other
countries, especially inEurope. TheIEEE 802.11a provides up to 54 Mbps, which
is much faster than both 802.11 and 802.11b. However the use of different radio
frequencies denies compatibility between 802.11a and 802.11/802.11b. Never-
theless the 802.11a was found satisfactory and approved in 1999.
To resolve the incompatibility problem between the standards, an amendment to
IEEE 802.11a was approved in 2003. The new standard is referred to as IEEE
802.11g, which operates at 2.4 GHz radio band while retaining the 54 Mbps data
transfer rate of the 802.11a. There are other standards in the 802.11 family, as
summarized in Table 1.
Table 1. IEEE 802.11 standards family (Ferro & Potorti, 2005)

Experiment Details
In this section we describe the implementation aspect of an IEEE 802.11 wireless
LAN using available wireless equipment. We first describe Wi-Fi networks set
up both in ad hoc (IBSS) and infrastructure (ESS) modes. We then focus on the
experiments and Wi-Fi performance measurement.
Hardware and Software Requirements
A number of hardware and software applications are used in the experiment.
The requirement for IBSS, BSS, and ESS differs mainly in the presence of the
AP. The following is the more detailed description of the resources used in the
experiment.
Hardware
For the basic service set, at least two Wi-Fi capable computers are required. This
is a fairly loose requirement, which can be satisfied by most commercial
computer hardware. However, the configuration for wireless laptops and APs
that we used in the experiment is shown in Tables 2 and 3.
A different configuration is used for the extended service set (ESS). In an ESS
network, an AP is used in addition to two Wi-Fi stations. A third computer is also
required to simulate the wired network the AP is attached to (see Table 3).
Table 2. Basic service set hardware specification
System Specification
Host 1 (H1) Make:
CPU:
RAM:
OS:
Wi-Fi:
Toshiba
Mobile Intel® Celeron® 2.4GHz
496MB
Windows XP Professional 2002 SP 1
WLAN adapter D-Link 650+ 802.11b
Host 2 (H2) Make:
CPU:
RAM:
OS:
Wi-Fi:
Toshiba
496MB
WLAN adapter Cisco 350 802.11b

Software
The IEEE 802.11b protocol automatically establishes data-link-level connection
whenever the Wi-Fi-enabled hosts are active and within range to each other. To
measure the actual throughput, however, connection at the application layer is
also required. Special software applications are used to enable such connection
to take place.
Colligo WE software from Colligo Networks Inc. enables users of Wi-Fi–
capable devices to exchange information. The communication can take place
either in ad hoc mode or infrastructure mode. It is necessary that every
participant of a Colligo network session has a copy of the software installed on
the computer. More complete information regarding the software can be
obtained from the company’s Web site at http://www.colligo.com/products/
workgroupedition/. Evaluation copy of the software is also available to download
from the Web site.
The software has many useful features, such as interactive chat, unidirectional
message delivery, virtual whiteboard, and file transfer. The file transfer feature
is crucial for this experiment, as it provides the means of measuring the link
throughput (Colligo, 2005).
Colligo has been designed for nontechnical users. The implication is that Colligo
is relatively easy to set up in a typical setting, such as in a wireless ad hoc
network. On the other hand, very little control is provided for technical users to
customize the settings. This restriction makes it especially difficult for setting up
a wireless network in infrastructure mode.
Table 3. Extended service set hardware specification
System Specification
Host 1 (H1) Make:
CPU:
RAM:
OS:
Wi-Fi:
Toshiba
496MB
WLAN adapter D-Link 650+ 802.11b
Host 2 (H2) Make:
CPU:
RAM:
OS:
Wi-Fi:
Dell
Intel® Pentium® M 1.4GHz
512MB
Intel® PRO/Wireless LAN 2100 3A Mini Adapter
AP Controller Make:
CPU:
RAM:
OS:
Wi-Fi:
Toshiba
496MB
D-Link DWL-900AP+ connected through crossover Ethernet cable

To set up an infrastructure network, appropriate application is required to
configure and control the AP. In this particular example, the AP hardware comes
with AirPlus Access Point Manager configuration software. The AirPlus
Access Point Manager is a Window-based program which allows setting up the
access point parameters from a computer through a wired connection. The AP
manager therefore is needed only in setting up the network in infrastructure
mode. As an alternative, the AP can also be managed using an Internet browser
such as Microsoft Internet Explorer.
IBSS Practical Setup
The following setup procedure creates a Colligo basic service set consisting of
two Wi-Fi stations, as shown inFigure3. Settingup such a Colligo ad hoc network
session is relatively simple and straightforward.
To initiate a session, all participating stations must activate their Wi-Fi adapter
and run the Colligo software. When Colligo is used for the first time, it is also
necessary to enter a user name and other personal details for identification
purposes.
Figure 4a shows the Colligo main screen for user benny after the program starts.
Clicking the Create Instant Network button in the upper-right corner, as shown
in Figure 4b, will either create a new BSS or join an existing ad hoc network. The
same procedure is repeated by other users wishing to join the network.
Following a successful ad hoc network connection, the user names of other
stations will be listed in the main window. The time it takes for hosts to detect
each other varies from a few seconds to several minutes. Figure 5a shows that
a remote user named wilson has been detected. The name of the remote user
is written in italics to indicate that the user has not yet been authenticated and
therefore is unable to communicate or gain access to the network resources.
Right-clicking on the remote user name will activate the authentication menu.
The ensuing interactive authentication sequence ensures that the remote user is
Figure 3. Simple two-station BSS

Figure 4. Colligo start-up main window
a. Initial window b. Starting an ad hoc network
Figure 5. Authenticating a remote user
a. Remote user has no network access b. Access to network has been granted

a legitimate member of the BSS. When the authentication is successful, the
remote user name is no longer written in italics, indicating that access to network
has been granted to the user, as shown in Figure 5b.
After the remote user is authenticated, all communication features of Colligo can
be used. The next step is to set up a file transfer session in which the link
throughput can be measured. Figure 6a shows the Colligo main menu to invoke
the file transfer feature. Selecting the Send Files item brings a file transfer
window similar to that shown in Figure 6b.
Colligo allows us to transfer a batch of files to a number of users. The empty lists
in Figure 6b must be correctly populated before the file transfer can begin.
Clicking on the Add Users button brings another window where all remote users
are listed (see Figure 7a). In this example, only one remote user called wilson
is selected. Now select the file(s) from the local drive for transmission (see
Figure 7b). Clicking on the Send button will initiate a confirmation sequence,
which is immediately followed by the actual file transfer.
BSS and ESS setup
In the infrastructure mode, the wireless network operates under the coordination
of an AP. The AP itself is connected to a wired network such as a LAN. In a
Figure 6. Initiating file transfer
a. Action menu b. File transfer window

simple home network, the AP can be directly connected to a router, which
provides access to the Internet (see Figure 8). Two stations such as Host 1 and
Host 2 communicate through an AP to access the Internet.
The AP is connected to a wired network even when access to the Internet is not
required. In our case, no access to the Internet is required. The wired network
is simulated by a third host called AP controller. The AP controller is connected
to the AP with a crossover Ethernet cable, as shown in Figure 9.
Figure 7. Completing file transfer setup
a. Selecting recipient b. Completed file transfer setup
Figure 8. ESS for home use

The AP must be configured in such a way that allows a Colligo network to be
established. Configuring the AP can only be completed from the AP controller
host using either the AP manager or the Web browser as discussed. When the
AP is active and connected to the controller host, launching the AP manager will
show the summary tab (see Figure 10). The screen capture shows the param-
eters set to run a Colligo wireless network in infrastructure mode.
Some of the parameters shown in the summary tab are static; whereas, others
are variables that need to be set with correct values.
• AP name is the name assigned to the particular AP. In larger networks
several APs may be used, which makes it necessary to assign unique names
to each to avoid naming conflict.
• SSID stands for service set ID, which is a unique name for the service set.
The Colligo software works correctly if the SSID is set to COLLIGO, as
shown Figure 11. Setting the AP’s SSID to anything other than COLLIGO
will prevent the Colligo wireless network from establishing.
• IP address in this context is the address of the AP for the wired connection
to the controller host. The default factory value is 192.168.0.50, which
indicates that the AP is designed for the use in small networks only. The
controller host must use a compatible IP address to communicate with the
AP through the Ethernet cable.
• MAC address displayed in the summary tab is the one used in the wireless
connection. This value is permanently assigned to the AP and cannot be
changed.
Figure 9. Simplified ESS

• Channel needs to be set to a number that does not conflict with another
nearby AP. Since there is no other AP within range, an arbitrary channel
number can be used.
• WEP security refers to the Wired Equivalent Privacy security scheme.
When turned on, all devices in the network must use the same encryption
key. For simplicity, this feature is turned off.
The most important settings are configured in the AP Setting tab. Figure 11
shows the configuration already set for a Colligo network in infrastructure mode.
The Mode Setting selector defines what role the AP device will assume in its
operation. The device cannot perform on more that one mode at a time.
1. Access point: The default operation mode of the device, which creates a
wireless LAN on infrastructure mode.
Figure 10. AP manager summary tab

2. Wireless client: The AP acts as an adapter, which transforms an 802.3
Ethernet device into a 802.11b wireless client.
3. Wireless bridge: Used to utilize two APs to connect two wired LANs with
wireless medium.
4. Multi-point bridge: An extension of the wireless bridge, where multiple
APs are used to connect more LANs.
5. Repeater: The device is used to extend the range of the network when the
wireless hosts are out of range of the actual LAN-connected AP.
In our experiment we set up the mode as Access Point. In practice, setting the
mode to other than Access Point always results in the network failure. Once the
AP is configured, the wireless infrastructure network is ready to operate, and the
wireless hosts can join the network. The Colligo software automatically sets the
SSID for each host to COLLIGO every time it is started. To join the ESS, a host
Figure 11. AP setting tab

only needs to launch Colligo and wait for the connection to establish automati-
cally. In contrast to the procedure with the BSS, the Create Instant Network
button should not be clicked. The user name of other hosts will appear on the main
Colligo window list a few minutes after a host enters the ESS coverage. The
routine for authenticating other users, sending files, and other actions is identical
to that in ad hoc mode.
Experiment Results
A text file of size 137 MB was transferred from Host 1 to Host 2 using the Send
Files feature of the Colligo Workgroup Edition 3.2, which allowed us to obtain the
file transmission time (Colligo, 2005). Different host formations were used to
examine the effects of distance on the throughput performance. Tables 4 and 5
summarize the experiment results.
Analysis and Interpretation
As seen in Table 4, a 4.5 Mbps throughput rate was achieved in ad hoc mode
although the bandwidth was 11 Mbps. The poor performance was due to the
Table 4. File transfer time in ad hoc mode
Table 5. File transfer time in infrastructure mode
Distance (m) Obstacle Transmission time Throughput (Mbps)
1 0 3m50s 4.66
1 1 4m00s 4.46
16 0 3m57s 4.52
Distance (m)
H1-H2
Distance (m)
H1-AP
Distance (m)
H2-AP
Transmission
time
Throughput
(Mbps)
1 1 2 10m45s 1.66
1 2 2 9m50s 1.82
1 1 1 10m20s 1.73
2 1 1 15m10s 1.18
32 12 20 9m33s 1.87
171
12 12 10m30s 1.70

retransmission of a large number of data packets that had been lost. Conducting
the experiment within a room may also have contributed to the low throughput.
At 2.4 GHz, the radio wavelength is only 12.5cm. At such a short length, signals
echoed by various surfaces within the room will reach the receiver in various
phases. The result is that at any given time, signals with varying phases and
amplitudes will either reinforce or cancel each other as they reach the receiver’s
antenna. The original signal is therefore received in a distorted form. This
problem is called multipath interference and is common in mobile communication
(Stallings, 2002).
Increased distance and the presence of obstacles also degrade network perfor-
mance noticeably. This effect is indeed unavoidable since the radio signals used
have very low power. Overcoming obstacle and distance problems by increasing
the power is not really an option since it will also increase the chance of
interfering with other wireless networks nearby.
A drastic performance drop is observed when the network operates in infrastruc-
ture mode. On average the throughput in infrastructure mode is only around 40%
that of ad hoc mode. Since the network uses PCF to synchronize the communi-
cations, the network is more efficient in using the available bandwidth by the use
of fewer control packets. The poor throughput can therefore be explained by the
mechanism by which data packets are transmitted from sender to the AP and
then from the AP to the receiver. It is very likely that the AP uses a store-and-
forward scheme, which results in the channel being occupied for twice as long.
On the other hand, the infrastructure mode makes it possible for wireless hosts
to communicate when they are out of range from each other as long as both are
within the AP’s range. This implies that more flexibility and mobility are achieved
at the expense of lower throughput.
Evaluation by Student Feedback
The Wi-Fi projects were offered to two graduate students as part of their
summative assessment towards Net-centric Computing, a postgraduate course.
The project learning outcomes include: (1) setting up and testing Wi-Fi projects;
(2) demonstration of working prototype to project supervisors; (3) development
of teaching resources for classroom use; (4) written report containing summary
of findings and reflective statements; and (5) oral presentation to the staff and
students.
The Wi-Fi projects were completed successfully, and students indicated that
they had learned a great deal about Wi-Fi fundamentals in completing hands-on

learning activities included in the Wi-Fi projects. This is evident from the
students’ reflective statements, as follows:
Student 1
The Wi-Fi project has helped me immensely to develop a sound knowledge of Wi-
Fi technology. During the practical project, I discovered that there are various
issues with regard to the deployment of Wi-Fi technology. The level of exposure
and knowledge that I gained from the hands-on experiment, I would have never
achieved from just a theoretical mode of learning.
There are many positives that can be drawn from a hands-on project like the Wi-
Fi propagation measurement. A project such as this helps you to understand and
appreciate technology better, which may not (be) possible from a mere theoreti-
cal form of learning. I would strongly recommend hands-on projects to others
who are interested to gain in-depth knowledge and experience of the technology.
Student 2
By taking up the hands-on project, I realised that with a correct approach, the
subject of networking in general and Wi-Fi in particular is no more difficult than
other subjects in computing science. By understanding the basic issues of the
technology, one can make sense on why the designers built the devices the way
they did. Further, it challenges us to think about how various aspects of the
technology can be improved.
With an engineering background, I never believe in any new technology unless
I see it actually working. The project convinced me that the Wi-Fi technology
does work, and any person willing to invest time studying and experimenting can
learn to set up his or her own Wi-Fi network. Also the experience enriches us
with another skill that may be important in our career later.
I would recommend similar projects to anyone interested in practical experi-
ments and is not shy of technical challenges. They are also suitable for veterans
of theoretical investigations who want to enrich their skill and experience with
practical ones.
Through a series of experiments and measurements made at various locations of
the AUT’s WY office building, we gained an insight into the performance of Wi-
Fi links in an office environment. This project involves both literature review and

practical investigation regarding the IEEE 802.11b protocol known as Wi-Fi. A
number of conclusions can be drawn from the findings of this study.
The use of electromagnetic waves as the medium instead of cables presents
many technical challenges. To begin with, the available radio band is limited, and
most ranges are licensed by governments across the world. This restriction
forces various wireless devices to crowd into the same unlicensed bands. Also
problems inherent in radio communication, such as noise, interference, and
security issues, also affect wireless networks. The implication is that, despite its
growing importance in recent years, the wireless network is not going to replace
the wired network. It is most likely that both wired and wireless networks will
coexist in the future.
The experiments reveal that data transfer rate through the wireless medium is
much lower than the wired network. The wireless connection is also fragile,
which necessitates that the whole transmission process be repeated whenever
the connection drops during file transfer session. Because of these limitations,
wireless networks at present serve mainly as a connectivity solution rather than
as a performance solution. This may change in the future, however, as new
wireless technologies supporting quality of service (QoS) are also being devel-
oped.
For Wi-Fi networks, it is found that the ad hoc mode provides better throughput
in a low-populated network. The same network operating in infrastructure mode
provides only about half the throughput of the ad hoc network. It is very likely
that the AP uses a store-and-forward algorithm in delivering the data packets,
which results in the drastic performance drop. The AP, however, is indispensable
when the stations are out of range of each other. The technical difficulties
encountered during the experiment suggest that Wi-Fi technology is not yet
mature. This is indicated by the complexity of the setting-up procedure and the
incompatibility that is common between Wi-Fi devices.
As it grows, wireless technology will provide research opportunities in several
areas. Future research relevant to the scope of this project will mainly involve
bandwidth increase and optimization, which are aimed at throughput improve-
ment. At present the IEEE 802.11b system has many limitations since it provides
services on “best effort” basis. The development of new wireless standards
providing QoS is the most effective way of achieving satisfactory network
performance (Prasad & Prasad, 2002).
In anticipation of the increased available bandwidth, various network-based
business and multimedia applications are also being developed. Prasad and
Prasad discuss applications such as teleconferencing, telesurveillance, and
video-on-demand operating on wireless network backbones. The required
bandwidths for delivering the data in various presentation formats are also
provided in their discussion.

Summary
The IEEE 802.11 wireless LAN standard has been gaining popularity worldwide
in recent years. The IEEE 802.11b, commonly referred to as wireless fidelity
(Wi-Fi), is by far the most successful commercially. There are other standards
in the IEEE 802.11 family being developed to overcome the limitations of IEEE
802.11b.
This chapter focused on the teaching and learning aspects of Wi-Fi networking
using limited hardware resources. A number of hands-on learning activities were
reported, including setting up both ad hoc and infrastructure networks. We found
that the throughput performance of Wi-Fi network under ad hoc mode is slightly
better than the infrastructure mode. This is mainly due to the store-and-forward
mechanism used by the access point.
Ad hoc network: A class of wireless LAN where nodes communicate without
wireless access points. A wireless network operating in ad hoc mode is also
called an independent basic service set (IBSS).
AP: Or access point. A device which acts as a bridge between wireless LANs
and a wired backbone network. An AP coordinates communication among
the mobile stations.
BSS: Or basic service set. A wireless network consisting of mobile stations
connected through an access point and any number of fixed stations.
Colligo software: A commercial software package that allows users to run
collaborative applications such as interactive chat, unidirectional message
delivery, virtual whiteboard, and file transfer.
DCF: Or distributed coordination function. DCF is the main channel access
method used in the IEEE 802.11 protocol, which uses the Carrier Sense
Multiple access with Collision Avoidance (CSMA/CA) protocol.
ESS: Or extended service set. A set of BSSs connected to a wired network
infrastructure.
IBSS: Or independent basic service set. A wireless LAN configuration without
access points. An IBSS is also referred to as an ad hoc mode wireless
network.
IEEE 802.11: A family of wireless LAN standards.

Infrastructure network: A class of wireless network in which mobile stations
are connected to the wired backbone network through wireless access
points.
PCF: Or point coordination function. An optional component of the MAC layer
protocol which provides a centralized mechanism for packet collision
avoidance during transmission via radio waves.
SSID: Or service set ID. A unique name that must be assigned to a service set
before the wireless network can operate.
Wi-Fi: Or wireless fidelity. A trade or commercial name for wireless networking
equipment using IEEE 802.11b standard.
Review Questions
1. Discuss the main differences between wireless PAN and wireless LAN.
2. Describe the main limitations of current Wi-Fi technologies.
3. Explain why Wi-Fi equipment operates at 2.4GHz in most countries.
4. What are the main challenges in increasing bandwidth in wireless network-
ing?
5. Describe the architecture of a typical Wi-Fi network.
6. Discuss the key characteristics of IEEE 802.11b standard.
7. Explain the significance of SSID in setting up a Wi-Fi network.
8. Can a Wi-Fi network simultaneously operate on both ad hoc and infrastruc-
ture modes? Provide sufficient argument or evidence to support your
answer.
References
Anonymous. (2005). Introduction to wireless LAN and IEEE 802.11.
Colligo. (2005). Colligo Networks, Inc. — Workgroup Edition, Colligo Inc. 2005
[online]. Retrieved from http://www.colligo.com
Ferro, E., & Potorti, F. (2005). Bluetooth and Wi-Fi wireless protocols: A survey
and a comparison. IEEE Wireless Communications, 12(1), 12-26.
Golmie, N., Van Dyck, R., et al. (2003). Interference evaluation of Bluetooth and
IEEE 802.11 systems. Wireless Networks, 9(3), 201-211.

Howard, D. (2002). It’s a Wi-Fi world. netWorker, 6(3), 26-30.
Kaczman, J. (2002). Wi-Fi hotspot networks sprout like mushrooms. IEEE
Spectrum, 39(9), 18-20.
Ophir, L., Bitran, Y., et al. (2004). Wi-Fi (IEEE 802.11) and Bluetooth coexist-
ence: Issues and solutions. In 15th IEEE International Symposium on
Personal, Indoor and Mobile Radio Communications, PIMRC 2004.
Prasad, N., & Prasad, A. (2002). WLAN systems and wireless IP for next
generation communications. Boston: Artech House.
Proxim. (1998, March). What is a wireless LAN? (White Paper No. 7680).
Mountain View, CA.
Stallings, W. (2002). Wireless communications and networks. NJ: Prentice
Hall.
Vaughan-Nichols, S. (2003). The challenge of Wi-Fi roaming. Computer, 36(7),
17-19.
Vaxevanakis, K., Zahariadis, T., et al. (2003). A review on wireless home
network technologies. ACM SIGMOBILE Mobile Computing and Com-
munications Review, 7(2), 59-68.
Youssef, M. A., Vasan, A., et al. (2002). Specification and analysis of the DCF
and PCF protocols in the 802.11 standard using systems of communicating
machines. In Proceedings of the 10th IEEE International Conference
on Network Protocols.
Endnote
1
There is no line of sight between H1 and H2.

Information Security Risk Analysis 179
Chapter X
InformationSecurity
RiskAnalysis:
A Pedagogic Model Based
on a Teaching Hospital
Sanjay Goel, University at Albany, SUNY, and
NYS Center for Information Forensics and Assurance, USA
Damira Pon, University at Albany, SUNY, and
NYS Center for Information Forensics and Assurance, USA
Abstract
There is a strong need for information security education, which stems from
the pervasiveness of information technology in business and society. Both
government departments and private industries depend on information
systems, as information systems are widespread across all business functions.
Disruption of critical operational information systems can have serious
financial impacts. According to a CSI/FBI report (2004), losses from
security breaches have risen rapidly in recent years and exceeded $200
million in 2003. The information security field is very diverse and combines
disciplines such as computer science, business, information science,
engineering, education, psychology, criminal justice, public administration,
law, and accounting. The broad interdisciplinary nature of information
security requires several specialists to collaboratively teach the curriculum
and integrate different perspectives and teaching styles into a cohesive

180 Goel & Pon
delivery. This chapter presents a pedagogical model based on a “teaching
hospital” concept that addresses the issues introduced above. By using a
specific information-risk-analysis case, the chapter highlights the basic
concept of the teaching hospital and its application in teaching and
learning contexts.
Learning Objectives
• Discuss the issues associated with information assurance education.
• Describe the basic concept of teaching hospital approach in information
security risk analysis.
• Understand the case development methodology used to support the teach-
ing hospital.
• Suggest possible improvements to the cases described in the chapter.
Introduction
Information assurance (IA) is a complex field, especially due to the dynamically
changing security environment and constant evolution of practices and proce-
dures. It is difficult to provide training in such an area since material developed
becomes obsolete very quickly. To develop a better understanding of IA,
concepts should be assimilated from several disciplines (i.e., computer and
information science, law, business, etc.) and blended into the context of real
problems. In this chapter, a teaching hospital model that has been developed for
IA training in the context of information security risk analysis is described. The
teaching hospital approach involves incorporating real cases to supplement
existing curriculum, which keeps teaching material relevant over time through
infusion of current research problems in the curriculum and creates a rich
learning environment that is both stimulating and dynamic. The New York State
Center for Information Forensics and Assurance (CIFA) at the University at
Albany has developed a teaching hospital for IA education (Goel & Pon, 2005).
Within this teaching hospital, a research program that solves current industry
problems is combined with a teaching program responsible for dissemination of
curriculum. Problems from public and private sector organizations are intro-

duced in the research lab, which are solved and abstracted into living cases that
are then used to supplement the training material. Bridges and Hallinger (1999)
have shown case-based learning to be a powerful pedagogical tool for dissemi-
nation of instruction. The teaching hospital model provides a constant stream of
cases that keeps the curriculum current. Though effective, such an approach is
still labor-intensive and contingent upon smooth functioning of research and
educational case development programs. The field of security is so vast that a
considerable time will elapse before most of the information security domain is
covered through cases. Over time, it is envisaged that a library of cases will
emerge, requiring less effort in new case development.
The general philosophy behind use of cases in curriculum and in context of the
teaching hospital proposed is detailed in the chapter. The rest of the chapter is
organized as follows: We first introduce the case-based learning techniques and
the concept of a teaching hospital. We then present a case on risk analysis that
demonstrates the use of the teaching hospital in information assurance curricu-
lum. Finally, we conclude the chapter, followed by a brief summary
Teaching Hospitals and
Case-Based Teaching
Teaching hospitals have been used extensively for medical training since the 20th
century (Barzansky, Jonas, & Etzel, 1998). They enabled control on medical
student production and medical education quality monitoring. Training is pro-
vided to medical students and doctors-in-training through direct clinical experi-
ence of treating actual patients under the supervision and guidance of attending
physicians in medical wards. Medical teaching hospitals are important because
their students need hands-on experience; otherwise, it is very difficult to
translate the abstract knowledge from the literature into a diagnosis. This
practice enables residents to crystallize theoretical knowledge into field knowl-
edge, which they can utilize when practicing medicine. In IA education, it is also
essential to find a balance between theory and practice. The field not only
requires students to be able to conceptualize but also to practically apply what
is learned within the classroom in the outside world. Teaching hospitals tend to
offer “a comprehensive array of facilities” as well as possess sufficiently high
volumes of patients from whom students can gain experience. Teaching hospi-
tals have also traditionally “conducted a wide variety of clinical research” (MGT
of America, 1999). Although derived from medical education, the teaching
hospital model has been implemented with great effect within the pedagogical
practices of other disciplines that require eventual application of theory into
practice.

182 Goel & Pon
We propose a teaching hospital for training students in the IA field where
students receive hands-on experience by working on real problems under the
supervision of researchers and practitioners in the field. Our model attempts to
emulate a teaching hospital by structuring an integrated program in IA research
and education through collaboration with other organizations (problem-rich in the
area of information security). Since the IA potential student population is large
and few researchers in the area are available, it is not feasible to send students
to directly apprentice with researchers in the field. As an alternative, cases from
state and law enforcement agencies are utilized. Real problems are abstracted
into living cases, which are used for classroom instruction; a constant stream of
cases can thus be generated. This approach allows the context of real problems
to be introduced into education and maintains the currency of the curriculum as
newer cases replace (or supplement) older cases. An active research program
and a mechanism for abstraction of projects into teaching cases are required for
the constant infusion of new material.
The fundamental underpinning of the teaching hospital is incorporation of a case-
based learning (Naumes & Naumes, 1999) approach. Cases assist in bringing
real-life context to abstract concepts. Case-based learning is believed to provide
more motivation for learning as well as a concrete framework from which
complex concepts can be more easily understood. It reduces the potential for
“inert knowledge,” where the learned information is difficult or impossible to
apply to realistic situations, and is critical to avoid learning inert knowledge since
it uses significant mental resources without commensurate returns. When
learning risk analysis, for example, simply learning the terms and definitions will
leave students with inert knowledge, which is not sufficient when they have to
perform a formal risk analysis in the field. Isolated facts are more difficult to
integrate within memories than facts taught in a realistic context. Generic
concepts should be applied and reiterated over multiple cases so students can
begin to understand the diversity of uses for that information.
While such a teaching hospital approach is very powerful, it is also very resource-
intensive (at least in the beginning). However, once streamlined, it can reduce
the teaching and preparation effort significantly. Especially when a large case
library is built, the time to collect data and build cases reduces significantly. In
addition, if properly coupled with an educational research program, pedagogical
research and domain research can synergistically operate, reducing the burden
and amortizing efforts over multiple streams. Cases can be of several types,
including detailed cases, narrative cases, mini cases, and bullet cases. They vary
in size and scope, with narrative cases being the largest (10 to 100 pages) and
bullet cases being the smallest (a few sentences). The use of cases depends on
the impact that the instructional designer is trying to achieve, and often several
different types of cases are used in various situations. As professed in this
chapter, we will use a specific information-risk-analysis case to illustrate the

concept of the teaching hospital. We chose the domain of risk analysis because
it forms a classic example of where the teaching hospital can be beneficial. It is
an abstract field where the terms and definitions are “inert knowledge” and
application of that knowledge is difficult.
Risk Analysis
Risk can be defined as the inherent uncertainty and unpredictability in the
outcomes of events or hazards that are faced while taking actions. Risk analysis
is the assessment of what could go wrong (risks), determination of which risks
warrant preventive or contingency actions, and development of strategies to deal
with those risks. Operationally, risk analysis can be defined as a method of
identifying the organizational assets, the threats to those assets, and the
vulnerability of the system to those threats in order to determine the exposure of
an organization and to determine suitable controls to reduce the exposure to
manageable levels (Goel & Chen, 2005). Assets are the valuables of an
organization which need to be protected, and vulnerabilities are weak character-
istics of assets. Threats are potential causes of harm to assets through exploi-
tation of vulnerabilities, and controls are implementations that reduce risk and
vulnerability (Office of Information and Communications Technology, 2003).
Risk analysis thus involves aggregating these parameters to determine the
exposure of the organization to the threats, and management is the process of
determination of controls that are necessary to reduce the impact of the risks to
manageable levels. Accomplishing a risk analysis can be an enormously intimi-
dating task since there are few management analysis topics that are as abstract
and complex as risk analysis. While risk analysis has been practiced for a long
time in various disciplines (Covello & Mumpower, 1985), its application to
information security is relatively new. Information security risk analysis, though
conceptuallysimple,isdifficultinapplication.Managersandinformationsecurity
officers often struggle with understanding the information security risks and their
relative importance.
The main issue in such analysis is the ambiguity in identifying the assets,
vulnerabilities, threats, and controls, especially since the same parameter can be
an asset, a vulnerability, and a control at the same time. Such problems provide
fertile ground for use of cases, and a case was developed for the purpose of
assisting students in articulating the assets, vulnerabilities, and threats; facilitat-
ing their understanding in rating these values based on their relative importance;
and assisting them in gaining experience in using a qualitative risk methodology.
To understand risk analysis the students need to develop the concepts of risk and

184 Goel & Pon
uncertainty to conceptualize the basic premise of risk analysis. Once conceptu-
ally grounded in theory, students need to gain a practical understanding by
applying risk analysis to real problems. Finally, they need to gain familiarity with
risk analysis tools and apply them to an actual risk analysis project.
In the pedagogic work presented here, students were provided basic skills in risk
analysis and provided a historical perspective of risk analysis as well as its
application in other fields. Once students were familiar with the concepts in risk,
they were introduced to formal definitions of risk analysis and introduced to a risk
analysis methodology. In most existing risk analysis tools, the tool and method-
ology are so complex that the students get defocused from the fundamental
learning of risk analysis. To direct their focus on the subtle nuances of the risk
analysis process, the students were given a set of simple matrices, which they
used to collect the data on assets, threats, vulnerabilities, and controls. The
students were presented with a working example in the class, and then a larger
case was introduced to apply the knowledge learned. The students were
expected to identify the organizational assets, threats, vulnerabilities, and
controls; value the assets; and determine the relationships between assets,
threats, vulnerabilities, and controls. A scale of 0 (none), 1 (low), 3 (medium), and
9 (high) was used to rate the impact of vulnerabilities on assets, threats on
vulnerabilities, and controls on threats. A tool was provided to enter the data and
compute the results. The students had knowledge of the basics of information
security that they were expected to use in their work.
A narrative case was developed with some ambiguity built into the analysis so
that the students were able to experience making subjective judgments about the
relative importance of information gathered. The goals of the case were to
reinforce the risk analysis concepts taught in class by assisting the students in
applying these concepts to a real situation. The case presented in the next section
was based on a business engaged in making and delivering natural soap products
to customers, which was selected because the product could be easily under-
stood and the business model was relatively transparent.
Natural Soap Company Case
Natural Soap Products, LLC, is a small (but rapidly growing!) family business
located in upstate New York in Schoharie County. This small family-run business
is engaged in making natural soap using recipes that have been in their family for
several generations. Roughly, two-thirds of their business is through wholesale
distribution of soaps and other products to specialty stores and commercial
lodging facilities. The remaining third of their business is through online sales
from their Web site. The business is managed and operated by a mother and her
daughter; the mother is around 40 years of age and the daughter is around 20

years of age. The mother and daughter are responsible for the wholesale
distribution of the products and the online sale of the products, respectively. The
wholesale distribution catalog is mailed to potential customers, and those orders
are collected via phone.
All orders are prepaid, and all major credit cards are accepted, including Visa,
MasterCard, American Express, and Discover. U.S. bank checks and money
orders are also accepted. All orders being paid with check or money order are
not shipped until payments are received and have cleared the bank. A New York
state tax of 8.25% (effective June 1, 2004) is added to both wholesale and retail
orders. Their orders are shipped within 3 to 5 business days, depending on the
shipping option selected by the customer. Shipping and handling charges are
extra and are based on weight and method of shipment.
The mother and the daughter do all the manufacturing in house. The mother is
responsible for making soaps, and the daughter is responsible for making lotions
and other products. Each batch of soap is handcrafted, incorporating the natural
ingredients supplied either through local vendors or through online orders. Soap
making involves two steps. In the first step, all the ingredients are processed
together. In the second step, the soaps are placed on large racks and cured until
they are ready for delivery. They are constantly preparing new products to keep
their product line vibrant. They advertise mainly through word of mouth from
satisfied customers, and their business is growing very briskly.
A Web site has been developed that provides a catalog of their products and
allows users to place orders online. Their Web site is hosted by Yahoo, which
manages the content and ordering system, as well as the order data. Yahoo is
privy to order information that is submitted via the Web site; however, it can only
use aggregate data for its analysis and maintains user anonymity. Yahoo also
automatically collects data on shopper experience if the Web site is accessed
through Yahoo. The Yahoo Privacy Policy, located at http://privacy.yahoo.com,
discusses how this information is used.
The privacy policy for Natural Soap is stated as follows:
At naturalsoapproducts.com we value our customers and respect their
privacy. We assure you that we will maintain use of customer information
responsibly. We will never sell or rent the information you provide to us
online to third parties. We may wish to contact you via mail or e-mail to
inform you of any promotions or specials taking place at Natural Soap
Products. If you do not wish to receive such information, please let us know
in the ‘special instructions’ box at checkout. If you have any questions
about our privacy policy, please feel free to contact us at
naturalsoapproducts@yahoo.com.

186 Goel & Pon
For legal protection, the company also posts a disclaimer:
Our products are not created to treat or cure any diseases or health
problems. All descriptions and sizes are approximate. Actual colors, sizes,
and styles may vary slightly from photos and descriptions and are subject
to change. Prices and policies of this website are effective April 2004 and
are subject to change without notice.
All orders are insured in value up to $100. If an item is damaged during shipping
customers are expected to contact the company immediately and to save all
packing materials and paperwork. If the damage to the package is noticed at the
time of the delivery, the recipient is expected to inform the delivery person and
have them verify the damage in writing. Damage caused to the order may then
be claimed through UPS or USPS.
Returns are accepted, and refunds or credits are honored as long as all of the
conditions listed below are met.
1. Item is unused and in its original condition.
2. The company is notified of the return within 7 days of customer’s receipt
of the item.
3. Customer assumes the responsibility of all shipping charges (original and
return) and returns the item within 7 days of notifying the company of the
return.
Two desktop computers are used for storing and processing the orders and
invoices. The computers also contain all of their client and vendor information as
well as inventory status. The daughter has some background in Web develop-
ment but has very little knowledge of computer security. The mother has
functional knowledge on how to use computers but has no knowledge of how to
configure, alter, or secure her computer and network. They have a broadband
network connection into the computer that the computers are constantly
connected to. They do not use a firewall or an intrusion detection system.
The company has about $1 million in annual revenue, of which 20% goes towards
raw material, 10% towards maintenance of equipment and temporary labor, and
30% towards the salaries of the two principals. In addition, they have fixed
expenses for maintaining the office and utilities.

Instructions to the Student
You want to analyze the information security risks for the organization and
determine the exposure of the organization due to security breaches. You will
need to identify assets, vulnerabilities, threats, and controls for the organization
and determine the most important controls that the organization will need to
install. You will perform a qualitative analysis initially to determine the relative
importance of the controls and then you will perform a quantitative analysis.
Results of the Analysis
The students were divided into groups of 4 to 5 who worked together in teams
to determine the threats, assets, vulnerabilities, and controls. The students had
a fair understanding of finance, economics, information technology, and security
upon entering the class. The discussed the different elements of the case and
built consensus in determining the values. Different teams did not communicate
with each other, and at the end of the session, each team reported its results. As
expected, the students had difficulty in identifying the risks, threats, controls, and
vulnerabilities. Another area that they struggled with was valuing the assets, and
they had vastly different concepts of the losses that could be incurred by
exposure of specific assets. The case was then discussed in the class, and the
numbers were rationalized during the discussion so that in the end a consensus
analysis was computed. Sometimes there can be alternate answers to the same
question based on the judgment of the analyst. Students tend to find it difficult
to grasp the ambiguity in the analysis and always seek definitive answers. A
sample solution is provided below. The solution also contains the rationalization
that evolved in its development.
Valuation of Assets
Valuating the information assets of a company is a very difficult process when
data is difficult to find and can be inaccurate, and some assets are intangible and
cannot be easily quantified. In addition, the value of the assets is not simply their
total values but should be considered as their estimated maximum loss. Estimated
maximum loss, an insurance term, can be defined as the largest probable loss that
could occur from a single event. This value could be well below the value of the
total asset. The company’s proprietary information is very important. If someone
obtained their recipes, customer base, supplier base, and so forth, it would be
possible to duplicate their product(s) and compete. In addition, the company

188 Goel & Pon
would have to spend time in obtaining information on the customers or suppliers.
However, the potential for all of their proprietary information to be stolen is
relatively low and due to their customer loyalty would not be too affected, even
though some time and effort would be needed for data collection and potentially
a small loss in revenue. Therefore, the valuationwouldbe about $25,000. If client
confidential information is stolen through loss of credit cardnumbers and identity
theft through either hacking or theft, then the company would probably have to
report the incident to the customers involved and potential lawsuits are possible.
This may result in loss of reputation and revenue as well as court fees. The
valuation for this asset would be $200,000. Personnel are essential to this
business. If something happened to the mother or daughter, it may be difficult to
operate as normal, and additional staff may need to be hired. Death is not very
probable because of the ages of the personnel; however, it is probable that the
daughter could decide to get a separate job. Time would be needed in training and
interviewing additional staff. The valuation would be $60,000 due to loss in
revenue, staff training, and hiring. Whiletheequipment is extensive, the potential
of much of the equipment being affected is low. The computers or soap
equipment may need to be replaced over time. However, in the case of theft, the
cost may be up to $30,000, to include likely stolen or broken items as well as
impact on operations and revenue. The Web site is hosted by Yahoo; however,
the company is liable for any damage to its data and is expected to have business
continuity measures and comply with the Cardholder Information Security
Program. The data is currently also stored in house computers, but the Web site
is not saved. Time and effort would need to be spent in reconstructing the Web
site, and any loss of information would incur some damage to client confidential
information located on the Web server. The estimated loss would be $110,000.
The reputation is the basis of this company. Most of its customers come through
Table 1. Asset valuations

word of mouth. Loss of reputation would likely occur through loss of data or loss
of personnel (e.g., the mother, depending on how contact is made). It is more
likelythat loss of informationwill occur, andtheresulting loss ofreputationwould
be estimated at $100,000. Inventory can be stolen, degrade, or be damaged. It
is a high probability that a batch of soap will be damaged or that some inventory
items might be stolen. This is estimated at $3,000. The credit line can be damaged
if overdrawn or someone takes a false credit card under the company’s name.
If a corporation loses its credit line, about $30,000 could be lost. The premises
of the company is most likely to be damaged through a break-in or environmental
damage such as rain, flood, lightning, or fire. The whole premises is not likely to
be damaged at any one point in time; however, probable damage will be
approximately $20,000. Documents may contain company proprietary informa-
tion and client confidential information and result in loss of reputation, revenue,
and time and effort of personnel. Maximum loss associated with theft or damage
is approximately $110,000. Theraw materials candegrade over timeor be stolen.
It is more probable that some raw materials will degrade, resulting in a loss of
$1,000. Revenue can be lost through loss of reputation, competition, and
slowdown of operations. It is estimated that loss occurring within one event
would be $150,000.
Correlating Assets and Vulnerabilities
There is a subtle difference between vulnerabilities and threats that needs to be
clear for accurately identifying vulnerabilities. Threats are the perpetrators of
losses while vulnerabilities are facilitators that help the threats manifest and
cause damage. The same vulnerability may affect different assets differently.
The matrix shown in Table 2 aggregates the impacts of different vulnerabilities
on the assets of the organization. The next paragraph provides the rationale that
was used to determine the valuation. This is the most critical part in understand-
ing the analysis.
Company proprietary information can be slightly impacted by Yahoo Web
hosting since some customer information may be located on the Web site and
database (1). Through the home network, there is a low probability of impact to
companyproprietary informationsinceinformationwillusuallynot be exchanged
so often (1). The premises can be exploited through break-ins to gain access to
some company proprietary information (1). Employees would not likely give out
proprietaryinformation and would not likelybe persuadedtodoso. However, due
to negligence or mistakes, they could prove to be vulnerabilities (1). Suppliers
may be able to give their own information but would not really have access to the
company’s information (0). Some of the client confidential information would be
located on the Web servers, and there would be a medium impact (3). Getting

190 Goel & Pon
client confidential information through transmission on the home network is not
likely; however, it is still possible (1). Home computers would be a better source
of getting information in terms of client confidential information (9). The
premises is also similarly low impact of being exploited to gain client confidential
information (1). While employees would have access to the information, they
would be unlikely to give up client confidential information. However, just as said
earlier with the company proprietary information, a mistake on the part of the
employees could lead to vulnerability (1). Personnel would likely be affected
through insecurity in the premises (1) and themselves (9). Equipment within the
organization would not really be affected by a vulnerability within Web hosting
at Yahoo (0). There is the chance of a medium impact of equipment through the
home network since it affects computers and the network (3). Home computers
will also have a medium impact on equipment since they are not all inclusive of
the equipment available (3). A vulnerability in the premises would lead to a
medium impact on equipment (3). Employees can have a medium impact on
equipment due to negligence in security implementation, user errors, or mistakes
causing damage (3). The manufacturing process can put wear on the equipment
Table 2. Asset/Vulnerability matrix

but not enough to damage it greatly. However, over time the manufacturing
process will degrade the equipment. Shipment is not likely to damage the
equipment since it will be located in the house and already exists (0). The Yahoo
Web hosting is most likely to be affected through the Website (9). There is a
possibility of gaining access permissions through vulnerabilities in the home
network. However, the chance that this would occur is low (1). It is possible that
through the home computers non-expired cookies or keyloggers could provide
access to the Web site and database information (3). Suppliers are not dealing
with the Web site so this is not likely (0). The company’s reputation can be
impacted through the Web hosting. For example, if credit card numbers are
stolen through the Web database (3). The home network may lead to loss of
reputation if it is exploited to gain access to something, but the chance of this is
very small (1). The home computers have a higher impact on reputation loss since
it is most associated with client confidential information (9). There is a low
impact on the reputation from vulnerability in the premises (1). Employees have
a medium impact on the reputation since the reputation of the company is
dependent primarily on the mother (3). Reputation may suffer if the suppliers go
away or the materials lose quality. In addition, if the process changes or the
shipping is affected, then the reputation can also be affected slightly (1). The
Web hosting, network, or computers will not affect inventory. However,
inventory may be affected by a vulnerability in the premises. For example,
leaving the door unlocked could allow someone to steal some inventory (1).
Employees could damage inventory through physical accidents and through
leaving security vulnerabilities (3). Suppliers take care of the raw material
delivery so they would not impact the inventory (0). Inadequate raw materials
and problems in the manufacturing could result in lower quality or lower amounts
of inventory (1). Shipment is a likely cause of inventory damage (3). The credit
score can be affected through overdrawing (probably through mistake of
employees) or someone stealing the company’s credit information. This can be
done through the Yahoo Web hosting, the home network, or the home computers
(3). The network and computers are vulnerable to negligence in security
measures by employees (3). It is also possible for vulnerabilities in the supplier
systems or weakness in the infrastructure to affect the credit. The premises is
mostly impacted by itself (9) and can also be affected by the employees who
work within there (3). Both suppliers and shippers would tend to have some
documentation (1). In addition, exploitation of Yahoo Web hosting, the home
network, and the premises could lead to impacts on some documents (1). Home
computers and employees would most likely impact documents in terms of where
they would be contained and the security and safety of them (3). Raw materials
could be stolen due to weak physical security of the premises (1). Employees
could handle the raw materials badly and cause other vulnerabilities due to weak
security management (3). Suppliers and shipment providers would be respon-

192 Goel & Pon
sible for the safe travel of the materials, where some could be damaged or
degraded (3). In addition, the manufacturing process can result in destruction of
raw materials (3). Raw materials are mostly impacted through natural elements
such as degradation over time so they are self-degrading (9). Revenue is
impactedthrough allvulnerabilities. TheWebhostingis responsible for about half
of the revenue generated (3). The network is used to communicate to the Web
database where customers can place orders (3). In addition, the home computers
store all the important information (3). The site does contain all the equipment,
inventory, and employees (1). Employees may most affect revenue since the
customers choose the company based on word of mouth and the personnel (3).
Supplier availability and quality of raw materials all affect the potential revenue
(3). In addition, the integrity of the manufacturing process and the shipment of
the materials could affect revenue (3).
Vulnerabilities and Threats
Threats are probably easier to determine compared to vulnerabilities and assets.
However, determining how important a given vulnerability is for a threat can be
difficult and often requires domain knowledge. The students in the class had a
detailed knowledge of the information security threats and technology from
previous lectures, which were instrumental for them in developing this matrix.
Since information security is a multidisciplinary field, it is often essential for the
experts to have familiarity with other disciplines, such as psychology and law.
The correlation between the threats and their interaction with vulnerabilities are
presented in Table 3, and the corresponding rationale for selecting these values
is provided in the next paragraph.
Accidental computer failure can result through weaknesses in the home comput-
ers themselves (9) and somewhat through employee actions with a machine (1).
Malicious code could exploit Yahoo Web hosting; however, this is not so likely
since Yahoo can afford more controls. This is still possible with new exploits
where no definition has been made (3). Malicious code could also affect an asset
through the network of the home and within home computers (3). Employees
could let in malicious code through clicking on an e-mail, going to a Web site, or
simply not securing the systems appropriately (3). A network intrusion on home
computers would exploit vulnerabilities in the home network with no firewall or
an improperly configured firewall (3) and the home computers (9). In addition,
the employees can be exploited to give out information or because they
improperly configure the firewall (1). A network intrusion or DOS attack on
Yahoo is through Yahoo Web hosting (9). A DOS attack on the home computers
would occur because of the network security (9) and employee misconfiguration
(3). The password to the Web account or data theft could occur through Yahoo

Web hosting (1) and through the home computers (3). Spyware and keyloggers
are likely to come into a system through negligence of an employee (3).
Accidental data alteration may be impacted by Yahoo Web hosting (1) but will
mostly be affected by user error (3). Physical theft of equipment is likely to occur
through vulnerabilities in the premises (9). Data theft is likely through the Yahoo
Web hosting and the home computers (3). It is also perpetuated through the home
network, employees, and the premises if present in paper documents (1). Physical
theft of inventory or raw materials could occur through the premises or when
shipping(3).Poorinventoryqualityismostlyduetothequalityoftherawmaterials,
mistakes done by employees, and effects of the manufacturing process (3).
However, the inventory can also be affected during shipment (1). Raw materials
can be affected by degradation of themselves and the suppliers (1). The mother
or daughter not being able to work occurs mostly within the employees themselves
(9). Damage to inventory is most likely to occur through the shipment (3) but can
alsooccurduetoaccidentsofemployees(3).Disruptionofthesupplychainislikely
to occur due to problems with suppliers (3) or shippers (1). Environmental damage
is likely to occur due to weaknesses in the premises (3).
Table 3. Vulnerability/Threat matrix

194 Goel & Pon
Threats and Controls
Domain knowledge is also critical for selection of controls, as analysts need to
understand the mechanisms behind the controls and the manifestation of threats
to accurately determine their impact on threats. Field experience is often
necessary for accurate characterization of the associations between threats and
controls that novice learners often lack. This matrix results in computation of the
relative utility of different controls for ensuring security. Based on this ranking,
controls can be selected. One should be cautious, however, since some controls
may be more expensive than others. A cost-benefit analysis must be performed
to determine the most effective control strategy. In addition, dropping some
controls altogether may not be feasible, even if their impact is low. It is perhaps
better to implement the control at a lower potency rather than eliminating it.
Table 4 presents the threat/control matrix.
The rationalization of the different values as perceived by the students is
presented in this paragraph. This is perhaps not the most comprehensive list of
Table 4. Threat/Control matrix

controls or the most accurate of correlations; however, it demonstrates the
thinking behind the analysis. Network security should have a medium impact on
malicious code and network intrusion on the home computers (3). It will have a
low impact on password and data theft by spyware and keyloggers (1) but a high
impact on DOS attacks on the home computers (9). Anti-virus would be very
helpful in preventing the spread of malicious code (9) and would help somewhat
in network intrusions on the home computers (3). Physical security would greatly
assist in the physical theft of equipment (9). It would also impact the theft of data
in the form of documents (3). In addition, it would assist somewhat in the theft
of inventory and raw materials (3). In addition, physical security such as a locked
room would keep damage to inventory lower (1) and protect against environmen-
tal damage by having a good roof which keeps water out (3). Warranties would
affect the accidental computer failure the most and allow free maintenance of
the computers (9). Business insurance would be likely to cover most of the
physical theft of equipment and environmental damage since the losses associ-
ated with these are high (9). It would also cover some of the losses due to theft
of inventory or raw materials and damage to inventory (3). Organizational
policies could help in the performance of employees and revenue by incorporat-
ing rewards for work or quality assurance standards increasing inventory quality
and impacting poor inventory quality (3), inability of the daughter and mother
working (3), and damage to inventory (1). This can affect accidental data
alteration in that the employee is required to have data entries checked by
another employee (3). Also, incorporation of liability waivers and an improved
privacy policy could manage effects of data theft, for example, malicious code,
network intrusion on home computers and Yahoo, or data theft by spyware and
keyloggers (3). It will also affect the password theft by spyware and keyloggers
for the home but not Yahoo (1). Encryption of stored and transmitted data will
help with network intrusions on the home computers as well as physical theft of
data (9). Having multiple sources of raw material should help with ensuring the
quality of the raw material (3) as well as having alternate sources to prevent
supply chain disruption in case one of the suppliers goes out of business or
temporarily closes (9). Secure packing of the inventory, such as using the bubble
wrap or Styrofoam packing peanuts, will help with prevention of damage to the
inventory when shipping (3). Anti-spyware (if updated with latest signatures)
should be able to identify most spyware and keylogging software that can lead
to data and password theft (9). Data backups will help in terms of time when
there is accidental computer failure (3), a DOS attack occurs on a computer (3),
data is stolen (3), or computer equipment that contains the data is stolen (3).
The matrices can evolve over time as new assets are acquired, more vulnerabili-
ties and threats are determined, and new controls are devised. This lightweight
approach is dependent on the rationalization of the data by the analysts. Field
experience is often essential to accurately perform risk analysis. Given the lack

196 Goel & Pon
of experience of the students, cases can substitute for fieldwork experience and
prepare the students for employment in the area.
Conclusion
Dissemination of abstract material in a classroom is usually a challenge that can
be overcome by using thoughtful examples to illustrate a case. Although such
examples may be effective in assisting students in conceptualizing the problem,
they are not adequate for clarifying the concepts enough to extend their
conceptualization in new domains. According to Bloom’s taxonomy, there are six
stages of learning: (1) knowledge (definition), (2) comprehension (conceptual
understanding), (3) application (usage), (4) analysis (understanding of mechan-
ics), (5) synthesis (adaptation of knowledge for problems), and (6) evaluation
(knowing when to apply knowledge). Without a case-based approach, students
remain in the application and analysis stages. Use of cases allows students to
learn in the synthesis and analysis stages. To develop practitioners who
effectively use their knowledge to business problems, it is imperative that their
learning allows them to understand the mechanics of a solution as well as to adapt
the knowledge gained to other similar problems.
The students acquired a basic understanding of risk analysis concepts and
terminology through the classroom lecture. However, the knowledge gained was
shallow, and they were unable to apply that to all but the simplest problems
through initial questions. Once the case was investigated in the classroom, the
studentseagerlyparticipated,buttheconceptswereabstractandconceptualization
of the learning was not consolidated. The feedback received from the students
makes it clear that the real learning came when they were provided with a
partially structured case and had to ask questions regarding the different
elements of the case as well as the methodology. Some of the students misapplied
the concepts; however, through class discussions they were all able to get a
correct understanding of the material. Casework alone is not sufficient for the
learning; group learning through active discussions is equally important.
Summary
The teaching hospital model presented here is a very effective learning tool for
abstract subject matter. The students gain a deeper knowledge of the material
and are able to better retain it in memory. While implementation of this model

requires a significant organizational effort, when operational it can be self-
sustaining, wherein an educational program dovetails a research program,
creating a constant flow of fresh cases into the curriculum. This is however
contingent upon an active research program in the area of interest. Such an
approach would be useful for most curriculums, but the impact is greatest when
there is abstract material that is hard to conceptualize through theory or has
practical applications in multiple domains. The model proposed here has been
adapted from the classic medical teaching hospital in that not all students work
directly on the research problems and cases are abstracted from research to
support learning. Risk analysis is a complex area, where the subtleties of its
application are often missed in understanding of terminology and definitions. The
teaching hospital approach was very pertinent and effective in this case and
certainly led to improved understanding and learning. Some issues that resulted
within its initial implementation were mainly related to logistics and case
development effort. If a sustainable research program already exists, it would be
worthwhile for instructors to try to incorporate case development work into the
curriculum.
Acknowledgments
We would like to thank Kendall McGillycuddy from McGillycuddy’s Natural
Soap for providing the material to develop the case. We would also like to thank
the New York State Center for Information Forensics and Assurance for its
support. This work is done with partial assistance of National Science Founda-
tion NSF 01-67 Grant 020657151 and U.S, Department of Education FIPSE
Grant P116B020477.
Assets: Valuables of an organization which need to be protected.
Cases: Abstraction of real problems that are used for training purposes.
Controls: Implementations for reduction of risk and vulnerability.
Inert knowledge: Knowledge that is theoretical but difficult to apply in other
areas.
Information assurance: Conducting operations that protect and defend infor-
mation and information systems by ensuring availability, integrity, authen-

198 Goel & Pon
tication, confidentiality, and non-repudiation. This includes providing for
restoration of information systems by incorporating protection, detection,
and reaction capabilities.
Risk analysis: An assessment of what could go wrong (risks), determination of
which risks warrant preventive or contingency actions, and development of
strategies to deal with those risks.
Teaching hospital: A hospital that is affiliated with a medical school and
provides the means for medical education to students, interns, and resi-
dents. It also functions as a formal center of learning for the training of
physicians, nurses, and allied health personnel.
Threats: Potential causes of harm to assets through exploitation of vulnerabili-
ties.
Vulnerabilities: Weak characteristics of assets in an organization.
Review Questions
1. Why is information assurance a unique problem?
2. Where did the concept of the teaching hospital emerge? Describe the
concept of the teaching hospital in the context of information assurance.
3. Define case-based learning. What are the advantages of using cases in
curriculum?
4. What different types of cases exist? Describe them and explain their role
in the teaching hospital.
5. Define risk analysis and explain the meaning of assets, threats, vulnerabili-
ties, and controls.
6. Why is asset valuation hard?
7. What is the relation between vulnerabilities and assets?
8. Are employees of an organization assets, vulnerabilities, threats, or con-
trols? Explain why or why not.
9. What are the different stages of learning according to Bloom’s taxonomy?
10. Take your own life as an example and find out the assets, threats,
vulnerabilities, and controls in it. Then, perform a risk analysis and figure
out how you should change your life to minimize your risk exposure.
Consider things like your habits, career plans, and options that you have in
life.

References
Barzansky, B., Jonas, H. S., & Etzel, S. I. (1998). Educational programs in US
medical schools, 1997-1998. Journal of the American Medical Associa-
tion, 280, 803-808.
Bridges, E. M., & Hallinger, P. (1999). The use of cases in problem based
learning. Journal of Cases in Educational Leadership, 2(2), 1-6.
Covello, V. T., & Mumpower, J. (1985). Risk analysis and risk management: An
historical perspective. Risk Analysis, 5, 103-120.
CSI/FBI. (2004). CSI/FBI computer crime and security survey. Computer
Security Institute Publications, 1-18.
Goel, S., & Chen, V. (2005). Information security risk analysis—A matrix-based
approach. In Proceedings of the Information Resource Management
Association (IRMA) International Conference.
Goel, S., & Pon, D. (2005). An innovative model for information assurance
curriculum: A teaching hospital. In Proceedings of the Information
Resource Management Association (IRMA) International Conference.
MGT of America. (1999, November). Accredited models for clinical training
of physicians in medical schools that operate without a teaching
hospital under the control of the university. Tallahassee, FL: Author.
Retrieved September 24, 2004, from Florida State University, College of
Medicine Web site: http://med.fsu.edu/pdf/03_clin_training_of_phys.pdf
Naumes, W., & Naumes, M. J. (1999). The art and craft of case writing.
Thousand Oaks, CA: Sage.
Office of Information and Communications Technology. (2003, June). Informa-
tion security guideline for NSW government—Part 1 Information
security risk nanagement (Issue No. 3.2). Retrieved on June 28, 2005,
from http://www.oit.nsw.gov.au/pdf/4.4.16.IS1.pdf

200 Goel & Pon
Section IV
Teaching and Learning
Computer Hardware

Input and Output Ports 201
ChapterXI
APractical
IntroductiontoInput
and Output Ports
Abstract
This chapter discusses how microprocessors interact with devices. It takes
the student from the basics of input and output, through the design of the
interface between a processor and an external device, and concludes with
a discussion of how to improve the performance of the I/O interface using
interrupts. The PC parallel port is examined to give the student a chance to
apply these concepts in hardware and software. Once the student has
studied the material of this chapter and completed the hands-on experiments,
they will be prepared to begin a study of how device drivers work within the
context of an operating system.

202 Tarnoff
Learning Objectives
• Describe the interaction between a processor, bus, and I/O devices.
• Explain how operating systems use I/O to access a computer’s resources.
• Define the following key terms: device interface, digital logic probe, IC, and
I/O ports.
• Suggest further enhancements to the materials presented in the chapter.
Introduction
Although the typical desktop computer has evolved into a stand-alone device,
isolated from its environment except for a keyboard, a monitor, and a connection
to a network, many computer applications still exist where the processor is used
to control devices or read data from external processes or events. Outputs are
needed for actions as simple as starting or stopping a process or as complex as
positioning a robotic arm. Inputs are needed to monitor sensors ranging in
capability from a simple switch to high-frequency analog input sampling cir-
cuitry. The discipline of sampling signals from the physical world so that the data
can be analyzed or processed by a computer is called data acquisition (DAQ).
There are two types of input and output (I/O) signals associated with computer
systems: analog and digital. Digital signals are usually associated with binary
control, levels that can be either on or off. In some cases, however, they can be
associated with scaleable input or output values. A stepper motor, for example,
is a digitally controlled motor, the position of which can be controlled with binary
outputs from a processor. There are also digital position encoders that can
provide a processor with the position of a rotating shaft using digital patterns of
ones and zeros.
An analog signal is a value read from the physical world such as temperature or
pressure. A device called an analog-to-digital converter (ADC) measures the
analog signal and sends a numeric representation of the measurement to the
processor. The process of reading an analog signal has a number of issues
regarding accuracy and timing. These issues are beyond the scope of this chapter
though.
Even the basic desktop machine depends on I/O for its operation. The processor
must be able to transfer data to and from devices such as a hard drive or a flash

RAM, receive data from inputs such as the keyboard and mouse, and send data
to outputs such as the video system.
The purpose of this chapter is to examine the issues surrounding the communi-
cation between a processor and its external devices and to introduce the reader
to some of the tools that are available to implement such systems. It begins with
a description of the operation of the processor bus and how I/O devices are
connected to it. One of the most basic I/O devices, the parallel or printer port,
is then presented along with the details needed to create a simple interface to it.
Finally, some advanced I/O techniques are presented to give the reader an idea
of how operating systems use I/O to access a computer’s resources. Throughout
the chapter, the circuitry behind some basic controls and sensors is presented
along with some of the tools used for testing them.
Basic Structure of a DAQ
and Control System
As Moore (1965) observed, every year brings higher and higher densities of
digital circuitry. This allows integrated circuit (IC) designers to pack greater
functionality into each successive generation of processors and to do it without
increasing the cost. One of the effects of Moore’s law is to allow device I/O
circuitry to be incorporated into the processor silicon. When this is done, I/O can
be accomplished merely by reading from or writing to one of the processor’s
registers.
Either due to the unusual type of I/O, the complexity of the I/O, or special needs
of the application, many I/O devices are still external to the processor. This
chapter assumes this configuration. In this case, the I/O must be connected
through a generic interface, specifically the processor’s bus.
Figure 1 presents the basic structure of the interface between a processor and
the external I/O devices with which it is meant to communicate. At the far end
of this organization are the sensors and controls that come in direct contact with
the physical world. The purpose of the sensors is to convert a physical
phenomenon, such as temperature, pressure, or sound, into electrical signals.
These electrical signals are captured by the device interface and converted into
binary data readable by the computer. Controls, on the other hand, are outputs
to the physical world. In this case, the purpose of the device interface is to take
digital commands from the processor and convert them into signals that drive the
controls. Examples of this include digital signals to turn on or off lights, protocols
sent to a display to print text or graphics, or data streams to control a printer’s

204 Tarnoff
output. Finally, the I/O module acts as a liaison between the processor and the
I/O device interface. It is this generic interface that allows the processor to use
a common method to communicate with all devices regardless of their special
communication needs.
Using the Bus to Communicate
with I/O Devices
Up to this point, the discussion has concentrated on the device end of I/O. In
order to show how the programmer can access these devices, it must be shown
how the bus is used to connect the devices to the processor.
The primary external interface to a processor is its memory bus. A bus is a
collection of parallel wires or conductors that connect the processor and all of
the devices with which it is to communicate. There are three types of wires in
a bus: data, address, and control. The data lines are used to pass information
between the processor and the other devices on the bus; the address lines are
used to identify which device is being addressed and which memory location or
subsystem within the device is of interest to the processor; and the control lines
are used to define the characteristics of the transfer, such as the timing and
direction of the data flow. Although any device on the bus may place data on the
data lines in order to send information, only the processor controls the address
and control lines of the bus.
The wires of the bus, usually referred to as conductors, are each capable of
delivering one binary digit or bit, that is, they are either transmitting a one or a
zero. The data lines are labeled using a capital letter D with a subscript identifying
the bit that conductor represents. For example, the least significant digit of the
data bus is labeled D0
, the next D1
, and so on. The address lines are labeled using
a capital letter A along with the same subscripting method that is used for the data
lines. The highest address line is labeled An-1
, where n represents the total
Figure 1. Basic organization of an external I/O device
Processor Bus
I/O
Module
External
sensors
and
controls
Device
Interface
Device
Interface
Device
Interface

number of address lines. This information can be used to identify the amount of
memory that the processor can access, specifically, the processor can access 2n
memory locations on its bus.
The devices of the bus, including the processor, are all connected in parallel to
the conductors of the bus, each bit of each connection type having its own
conductor. For example, all of the devices have a connection for address line A0
,
and all of these connections are tied together using the same conductor. This
method of connecting devices to a bus is referred to as daisy-chaining. An
example of daisy-chaining is shown in Figure 2, where address line A19
of the
processor is connected to A19
of Memory Device 1, which is in turn connected
to A19
of Memory Device 2. This is true for each of the address, data, and control
connections.
Two of the most important control lines are the read control line and the write
control line. The processor uses these binary lines to control the direction of the
data transaction. Table 1 presents the operation of the bus for the different
settings of the read and write control lines.
The configuration of the address lines is also important. They are a vital part of
the system that identifies which device on the bus is being addressed by the
processor. Without the address lines, the processor would require a separate bus
to each device. The problem is that with multiple devices on the same bus, only
one device can be enabled at a time. If two devices tried to drive the data lines
simultaneously, data would be lost. It would be like two people trying to talk at
the same time. This condition is called bus contention.
Figure 3 presents a situation where data is being read from Memory Device 1
while Memory Device 2 remains “disconnected” from the bus. Disconnected is
in quotes because the physical connection is still present; it just does not have an
electrical connection across which data can pass.
Notice that Figure 3 shows that the only lines disconnected from the bus are the
data lines. This is because bus contention only occurs when multiple devices are
Figure 2. Daisy-chained configuration of the processor bus
Memory Device 1
A19…A0 D15…D0 R W
Memory Device 2
A19…A0 D15…D0 R W
Memory Device 3
A19…A0 D15…D0 R W

206 Tarnoff
trying to output to the same conductors at the same time. Since only the processor
outputs to the address and control lines, they can remain connected.
In order for this scheme to work, an additional control signal must be sent to each
of the memory devices telling them when to be connected to the bus and when
to be disconnected. This control signal is called a chip select, and it is derived
from the address lines.
Note that a memory device will always have a smaller capacity than that
addressable by the processor. Because of this, some of the higher address lines
from the bus do not have corresponding connections at the memory device.
These leftover address lines are used to create the chip select that uniquely
identifies the device. If a different binary pattern is selected for each set of high-
order address lines going to each device, then only one device can be enabled at
a time. Table 2 shows how four chip selects might be used to enable only one of
the four devices or leave all of them disabled.
Table 1. Summary of read and write control line settings
Read
Line
Write
Line
Bus Operation
0 0
This is an illegal setting and should never
happen.
0 1
Setting the read line low indicates that the
processor wishes to receive data (read) from
memory.
1 0
Setting the write line low indicates that the
processor wishes to store data (write) to
memory.
1 1
The memory bus is idle. There is no
transmission of data.
Figure 3. Block diagram of two memory devices sharing a bus
Micro-
processor
Memory
1
Memory
2
Data lines
are connected
to the bus.
Data lines are
disconnected
from the bus.

Using the address lines, data lines, and the read and write control lines, the basic
interface to a collection of memory devices can be created. Figure 4 presents the
basic interface to a memory device. A NAND gate is used to represent the chip
select circuitry.
The Intel 80x861
processors use the names ^MRDC and ^MWTC for the read
and write control lines, respectively.
So why bother going into such detail regarding the memory bus? The reason is
that most I/O devices are connected to the processor using the same bus.
Although I/O devices may have little or no memory, sending data to them is
equivalent to storing data in a memory device while receiving data from an I/O
device is like reading a memory device.
Table 2. The allowable settings of four chip selects
CS0 CS1 CS2 CS3
High-order address bits set to
enable device 0
enabled disabled disabled disabled
enable device 1
disabled enabled disabled disabled
enable device 2
disabled disabled enabled disabled
enable device 3
disabled disabled disabled enabled
High-order address bits match no
device
disabled disabled disabled disabled
Figure 4. Typical bus connections for a memory device
Memory
Device
chip select
R/W
Low-order
address
lines
Data
lines
High-order
address
lines
R/W

208 Tarnoff
Memory Mapped I/O vs.
Port Addressed I/O
The Intel 80x86 family of processors, the ones on which the IBM PC-clone
architecture is based, treats I/O devices slightly different than it does memory
devices. The Intel 80x86-based systems access external devices through reads
and writes to I/O ports. An I/O port allows a processor to access an external
device using an addressing scheme identical to that of the memory bus address-
ing scheme. In fact, the 80x86 I/O devices are wired to the same bus as
processor’s memory. There are two minor differences that distinguish I/O port
communication from transactions with main memory.
First, the I/O ports use different read and write control lines. For the Intel 80x86
processors, the read and write lines for I/O ports are named ÎORC and ÎOWC,
respectively. Table 3 summarizes how the processor uses the signals ^MRDC,
^MWTC, ÎORC, and ÎOWC to distinguish between I/O port and memory
operations.
In some cases, I/O devices are connected to the memory bus so that they act just
like a memory device. This practice, called memory mapping, is quite common,
and for processors that do not have separate read and write control lines for their
I/O ports, it is necessary. In the case of the Intel processors though, the majority
of I/O devices use these alternative read and write control lines.
The second difference between memory and I/O port communication on the Intel
80x86 processor bus is that only the lower 16 address lines are used when
communicating with an I/O port. This means that only 216
= 65,536 addresses are
available to any processor in the 80x86 family. This generally is not a problem.
The typical I/O device only requires a few memory locations to perform all of its
transactions with the processor as opposed to the large amount of storage
associated with a memory device. Therefore, all but a few of the address lines
can be connected to the chip select circuitry, meaning fewer address lines are
needed from the processor for I/O ports.
Table 3. Control signal differences between I/O and memory transactions
^MRDC ^MWTC ÎORC ÎOWC
Reading data from memory low high high high
Writing data to memory high low high high
Inputting data from an I/O port high high low high
Outputting data to an I/O port high high high low

These issues have a direct effect on the software that accesses I/O ports. To
store data to memory, all that the software needs is an address. By assigning an
address to a pointer, software can store or retrieve the data in either a memory
location or a memory-mapped I/O device using the same methods it would to
modify a program variable. For I/O ports, however, a different set of instructions
is needed so that the second set of read and write control lines are used and not
the memory read and write control lines. At the Intel 80x86 assembly language
level, these instructions are IN and OUT. A different set of instructions for
accessing I/O ports using a high-level programming language will be presented
in the next section.
As would be expected, I/O devices function differently than memory. When a
processor reads a memory location, the value retrieved should be the same as the
last value written to it. In most cases, reading from an I/O device accesses an
entirely different service than writing to it does. For example, assume that one
of the processor’s I/O ports is a serial communication device. Writing data to one
of the port’s addresses may send data out the serial port while reading from the
same address may retrieve the last piece of data received by the port. Writing
to another address may enable the transmitter and receiver while reading from
the same address may return the status of the receive and transmit buffers. For
programmers unfamiliar with I/O ports, it may seem odd to write to a port and
then receive completely different data when the port is read.
Operating systems benefit greatly from having separate mechanisms for access-
ing memory and I/O ports. If an I/O device is memory mapped instead of
connected to an I/O port, any communication to it would be subject to the
operating system’s memory management. This would prohibit direct access to
the device and make the sharing of devices very difficult.
Structure of the Parallel Port
Although the original purpose of the parallel port of a PC was to provide a
connection to a printer, this digital port provides a quick, simple method for
implementing digital I/O. Typically, this port is free on most computers since
printer manufacturers have begun taking advantage of the versatility of the USB
interface.
The parallel port is a 25-pin port on the back of almost every PC. It has sockets
where the pins from a printer cable connector are inserted. These sockets,
however, can also be accessed using a section of 24 AWG solid-core telephone
wire with about one quarter of an inch of insulation stripped from each end. By

210 Tarnoff
looping the wire from one socket to another, a test circuit can be created where
output connections can drive input connections.
Figure 5 presents the pin definitions of the parallel port. Signal names preceded
by a “^” are active low signals. To indicate the direction of the data flow, arrows
going away from the pin represent outputs (from the PC to the printer or other
external device) and arrows going into the pin represent inputs (from the printer
or external device into the PC). The figure’s perspective is from the outside of
the female connector coming off the back of the PC.
This port offers numerous opportunities for performing digital I/O using a PC.
Possible projects include motor control for robotics, digital sensor input for data
acquisition, and LCD display control for user interfaces (Tarnoff, 2004).
Each parallel port uses three separate addresses that point to registers used to
control the port or retrieve its status. The first register, the data output register,
is used to send data to the data lines (pins 2 through 9). This register is a one-
to-one mapping of the bits from an 8-bit data value to the eight individual outputs.
The least significant bit of the data value corresponds to pin 2 while the most
significant bit corresponds to pin 9.
The second register is used to receive data from the status inputs (pins 10, 11,
12, 13, and 15). This register is called the status register, and it also uses an 8-
bit data value. Since there are only five status inputs, three of the bits are left
unused. The most significant bit of the 8-bit status register represents the value
present at the busy input (pin 11). The next bit contains the value from the ACK
input (pin 10). After that comes the paper empty signal (pin 12), then the printer
selected input (pin 13), and finally the error input (pin 15).
Figure 5. Pinout of a DB25 parallel port
^STROBE
Data 0
Data 1
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
ÂCK
Busy
Paper Empty
Select
Âuto Feed
Êrror
Initialize Printer
^Select Input
1
14
13 25

The control register is the third register, and it functions on two levels. Four of
its bits are used to send control signals out of the 25-pin port to control the
operation of a printer. These include the strobe (pin 1), a paper feed signal called
auto feed (pin 14), a signal to initialize a printer (pin 16), and a printer select signal
(pin 17) that is used to enable the printer connected to that port. The remaining
used bit of the control register is used to enable and monitor the parallel port’s
interrupt operation through pin 10 of the interface. Interrupts will be discussed
later in this chapter.
Figure 6 presents the organization of these three registers.
Each register has its own I/O port address that is used in conjunction with the IN
and OUT commands. Regardless of the specific address where the parallel port
is located within the address range of the I/O ports, these three addresses are
located next to each other. The address of the data register is often considered
the base address since it has the numerically lowest address of the three. Its
address is equivalent to the address assigned to the parallel port by the system.
The next address is the one that points to the status register. The address for this
register is the base address plus 1. The control register is located at the next
address, the base address plus 2.
The typical Intel-based PC uses one of the following three addresses for the base
address of the parallel port: 378 (hex), 278 (hex), or 3BC (hex). There are two
methods available to the user to determine this base address. First, since the
address is usually set in the BIOS rather than the operating system, the user can
access this value through the system setup. By referring to the system documen-
tation, the user can go into system setup when the machine is booted. Within the
Figure 6. Organization of the three parallel port addressable registers
Data Output Register
D7 D6 D5 D4 D3 D2 D1 D0
pin 9
output
pin 8
output
pin 7
output
pin 6
output
pin 5
output
pin 4
output
pin 3
output
pin 2
output
Status Register
S7 S6 S5 S4 S3 unused
busy
input
ACK
input
paper end
input
select
input
error
input
Control Register
unused C4 C3 C2 C1 C0
IRQ
ctrl
select
output
init
output
auto fd
output
strobe
output

212 Tarnoff
setup menu, there should be an option to set or view the parameters of the
computer’s integrated devices. From this menu, the user may record the I/O
address of the parallel port.
The parallel port’s base address can also be found using an operating system
such as Microsoft Windows. In Windows, go to Control Panel and select System.
From the System window, select the Hardware tab, and then click on the button
that provides information on the devices. In Windows XP, this button is labeled
Device Manager. From the Device Manager, there should be an entry labeled
Ports (COM and LPT). LPT refers to the parallel port hardware. When the plus
sign next to the ports entry is clicked, a list of the available ports should drop down
below it. By right-clicking on the LPT port, a context-specific menu should allow
the user to select Properties. It is from this Properties window that the resource
settings can be examined. This is where the address for the parallel port can be
found. Make a note of this address so that it can be referenced in the application
software presented later in this chapter.
Simple Digital I/O Circuits
Before developing the software behind a device driver for digital I/O, the basics
of some simple test circuitry must be explained. The simplest output from a digital
circuit is a light-emitting diode (LED). An LED is a solid-state device that glows
brightly when a small current passes through it from one input to the other. No
light will appear if there is no current or if the current tries to flow in the opposite
direction. This means that one of the first things to check when debugging an
LED circuit is to verify the orientation of the LED.
Figure 7 presents the schematic symbol of an LED. For the LED to turn on,
current must flow from the A terminal to the B terminal.
There are two things to note here. First, the current must be very small. The solid-
state circuitry possesses no mechanism to limit the amount of current flowing
through it, and if too much current flows, the LED will be destroyed. An external
device called a resistor must be added in order to keep the current small enough
to protect the LED. By placing a resistor in series with the LED, the current is
choked enough to protect the LED. Without the resistor, the LED will emit a soft
popping sound followed by a strong, acrid odor. Figure 8 shows a typical LED
circuit.
The second item of importance is that the LED circuit of Figure 8 will turn on only
when the output from the IC is a binary zero. The LED is turned off by sending
a binary 1 to the circuit. This is the optimum way to drive an LED. If an IC is
expected to provide the current to an external circuit, it must draw extra current

from its own power source. This increased power consumption will generate
heat and reduce the reliability of the IC. It is much better for an IC to act as a
connection to dissipate (sink) current rather than provide (source) it.
The simplest input to a digital circuit is a switch. It seems that the logical way to
connect a switch to a digital circuit would be to connect it so that it toggles
between a direct connection to a binary 1 and a direct connection to a binary 0.
Switching back and forth between these connections should produce binary 1s
and 0s, right?
Due to the internal electronics of an IC, this is not the case. Instead, connections
to positive voltages are made through resistors called pull-up resistors. This
protectstheICbylimitingthecurrentflowingintoitwhilestillprovidingapositive
voltage that can be read as a binary 1.
Figure 9 presents a generic switch design for a single input to a digital circuit. It
uses a pull-up resistor connected to 5 volts, which represents the circuit’s power
source. When the switch is open, the pull-up resistor creates a binary 1 at the
IC’s input. When the switch is closed, the IC’s input is connected to ground,
which acts as a binary 0.
By using these circuits for switches and LEDs, simple test circuitry for digital
I/O can be built.
Figure 7. Schematic symbol of a light-emitting diode (LED)
A
B
+5 V
IC Output
Figure 8. Typical LED circuit

214 Tarnoff
Measuring Digital Voltage Levels
There is an alternative method to using an LED to test the output of a digital
circuit. Each digital output of a PC uses two voltage levels to represent ones and
zeros. Traditionally, a voltage of 5 volts represents a binary 1 while a ground or
0 volts represents a binary 0. If this is the case, there is a ubiquitous circuit testing
device that can be used to detect whether a 1 or a 0 is present on a digital output.
This simple device, a sample of which is pictured in Figure 10, is called a digital
logic probe.
The digital logic probe has a metallic tip that the user places on the portion of the
circuit to be analyzed. The opposite end of the probe has a pair of wires to be
connected to a power supply. Typically, the red clip of the power supply
connections is connected to 5 volts, and the black clip is connected to ground.
Figure 9. Generic switch circuit to an IC’s input
IC's Input
+5 V
Pull-up Resistor
Figure 10. An example of a digital logic probe

These voltages are available from the power supply of the computer.
As for the controls and indicators on the probe body, the typical logic probe
combines some or all of the following:
• An LED indicating when the tip of the probe is touching a low or binary 0.
• An LED indicating when the tip of the probe is touching a high or binary 1.
• An LED indicating when the tip of the probe is touching a signal that is
pulsing. (Typically this LED is used in conjunction with the low and high
LEDs, the brighter of the two indicating whether the signal is more often
high or more often low.)
• A CMOS/TTL switch which is used to switch between different types of
digital circuits. (CMOS is most common in today’s circuitry.)
• A memory switch used simply to let the probe keep the LEDs lit to whatever
the last setting was even after the probe is removed from the circuit.
As far as gaining access to voltages within the computer, all standard computer
power supplies provide enough power to run not only the motherboard and its
supporting peripherals but also enough power to support a few external devices.
For example, the +5V and ground signals that are referred to in the LED circuit,
the switch circuit, and the logic probe connections are available from the same
connector that is used to power the hard drives and CD-ROMs. The four-pin
connecter shown in Figure 11 has four wires, one yellow, two black, and one red.
The yellow wire supplies +12 volts, the black wires provide ground connections,
and the red wire is a +5 volt supply.
Figure 11. Basic four-pin Molex connector from a PC power supply

216 Tarnoff
I/O Port Software
As stated earlier in this chapter, I/O ports can be accessed directly using the
assembly language commands IN and OUT. IN retrieves data from an I/O
device. It uses as its operands (data arguments) the address of the I/O port and
the register in the processor where the retrieved value is to be stored. OUT sends
data to an I/O device. It uses as its operands the address of the I/O port and the
data to send to the I/O device.
Access to I/O ports is not limited to assembly language programmers however.
Similar commands are available to the high-level programming languages of both
Linux and Microsoft Windows. The problem is that modern operating systems
have isolated the programmer from the hardware to a great extent. In many
cases, the programmer must add special libraries of functions or run the
programs as administrators in order to access the I/O ports.
In Microsoft Windows, a number of third-party vendors have created dynamic
link libraries (DLLs) that provide additional functionality to the programmer in
the form of high-level language functions that replace the assembly language
routines IN and OUT. It is important to note that by offering these functions as
part of a DLL, these vendors have provided port functionality to almost any
Windows programming language. The following is a short list of some of these
DLLs and the vendors that supply them.
• Inpout32.dll (Axelson, 2003) from Logix4u
• Win95io.dll (1997) and Vbasm.dll (1997) from SoftCircuits Programming
• NTPort Library (2002) from Zeal SoftStudio
Typically, all that is needed to install a DLL is to copy it to the appropriate folder
under the Windows directory. In the case of the libraries shown above, the DLL
needs to be copied into the folder windowssystem.
Accessing the routines within the DLL depends on the programming environ-
ment being used. The following discussion shows how the functions from
Logix4u’s Inpout32.dll can be used with Microsoft Visual Basic 6 to create an
interface to the parallel port. (It is assumed that the reader is at least somewhat
familiar with the programming environment. Development in Linux will be
discussed later in the chapter.)
In order to send and receive data from an I/O port, a number of controls will be
needed. To begin with, since an I/O port is referred to with a memory address,
the user must have a method to set the address for the I/O port. As discussed
earlier, the parallel port on the PC uses one of the three base addresses: 378

(hex), 278 (hex), and 3BC (hex). Therefore, a combo box will be added to the
interface to select from one of the three standard parallel port addresses.
Next, a text box is needed to allow a user to enter data to be sent to the parallel
port’s output. Since the data bus for the parallel port is 8 bits wide, the values sent
to it must be limited to positive integers from 0 to 255. In addition to the text box
for output data, a button is needed to cause the data to be sent to the port. Another
text box is needed to display data retrieved from the parallel port along with a
second button to cause the application to retrieve the data from the port. Lastly,
some labels are needed to identify the components of the interface.
After opening the Visual Basic development environment, create a new project
by selecting New Project from the File menu. A standard executable is sufficient
since all that is needed is to create a small window with a few text inputs, a combo
box, two buttons, and some labels. Figure 12 presents a sample configuration of
the inputs needed for a simple window to send and receive data to and from an
I/O port.
To make the application function more appropriately, the window is titled, forced
to remain a fixed size, and given a start-up position of the screen’s center. The
inputs are also labeled and given initial values. Figure 13 presents the modified
window.
Figure 12. Sample I/O control window
Figure 13. Sample I/O control window with components identified

218 Tarnoff
To aid in the programming of this application, the combo box has been renamed
Port_addr, the text box containing data to be sent is renamed out_data, the text
box used to display incoming data is renamed in_data, the button used to initiate
a send is renamed Send_data, and the button used to initiate a read from the port
is renamed Get_data. It is also helpful to set the DataFormat properties of both
the out_data and in_data text boxes to Number with no digits allowed after the
decimal point. This will avoid any errors due to improperly formatted inputs.
Since the combo box is used to limit the I/O port addresses to the ones available
for the parallel port, it needs to be initialized to the three standard values for the
parallel port I/O addresses. In Visual Basic 6, adding values to the list of items
for a combo box is done with code, specifically, the AddItem method. This needs
to be done as soon as the application is first loaded. To gain access to the code
that is executed upon loading an application, right-click on the form and select
View Code from the context-specific menu that appears.
The code window that appears should have two list boxes at the top, one from
which to select the object (it probably says (General) in it) and one from which
to select the event. In the object list box, select the form’s name, and from the
event list box select Load. A block of code similar to that shown in Figure 14
should appear in the code window.
Three items need to be added to the combo box. Figure 15 shows these three
items added with the AddItem event. The last line of the added code selects the
default value as index 0, that is, 378 (hex).
Now that the interface is fully defined, the functions from the DLL need to be
made visible to the code of this application. From the Project menu, select Add
Private Sub Form_Load()
End Sub
Figure 14. Template for code to be executed upon loading a VB form
Figure 15. Template for code to be executed upon loading a VB form
Private Sub Form_Load()
Port_addr.AddItem "378 (hex)"
Port_addr.AddItem "278 (hex)"
Port_addr.AddItem "3bc (hex)"
Port_addr.Text = Port_addr.List(0)
End Sub

Module. A window will appear allowing a module to be inserted into the project.
Click on the Open button to insert this new module.
Open this module, and from the general declarations area, add the declarations
shown in Figure 16 to point to the functions of the DLL. By doing this, the code
now has access to the I/O port controls Inp and Out of the Inpout32 DLL. All
that needs to be done now is to associate these functions with the controls of the
application.
The first function, Inp, is used to retrieve data from an I/O port. Just like the
assembly language instruction IN, it requires the address of the I/O port. This is
declared as the integer variable PortAddress. The function returns an integer
representing the value read from the I/O port’s inputs.
The second function, Out, is used to send data to the I/O port. It is equivalent to
the assembly language instruction OUT, and just like OUT it requires two pieces
of data: the address of the I/O port (PortAddress) and the data to send to it
(Value).
From the design view, double-click on the Send_data button. This should open
the code window with a function inserted called Send_data_Click(). This
function is called when the button Send_data is clicked by the user. Two things
need to be done within this function. First, the address represented by the combo
box Port_addr must be retrieved. This can be done with a simple Select-Case
block. Second, the Inpout32 function Out must be called to send the data to the
I/O port. Figure 17 presents the code that performs this function.
In the line of code that assigns the value read from out_data to the integer
out_value, a logical AND is performed on the data in order to limit the output
value to integers from 0 to 255.
Now to receive data from the five status input pins on the parallel port. Return
to the design view and double-click on the Get_data button. Once again, the
code view should appear, this time with a new function Get_data_Click()
inserted. As with the Send_data button, code will be inserted here to determine
the parallel port’s address from the Port_addr combo box followed by a call to
the appropriate Inpout32 function. In this case, the port address will be 1 greater
than the base address for the I/O port, for example, if the parallel port’s address
Figure 16. VB function declarations for Inpout32.dll
Public Declare Function Inp Lib "inpout32.dll" Alias
"Inp32" (ByVal PortAddress As Integer) As Integer
Public Declare Sub Out Lib "inpout32.dll" Alias "Out32"
(ByVal PortAddress As Integer, ByVal Value As Integer)

220 Tarnoff
is 378 (hex), then the status lines are read from address 379 (hex). For the
receive case, the Inpout32 function called in Inp will be used to return the value
from the appropriate address. Figure 18 presents the code for the receive
function.
Figure 19 shows the device used by the author to evaluate the operation of the
program along with a screen shot of the application. The device connects an LED
circuit similar to that shown in Figure 8 to each of the parallel port’s outputs, pins
2 through 9, and a switch circuit similar to that shown in Figure 9 to each of the
status inputs to the parallel port, pins 10, 11, 12, 13, and 15.
Linux C development software2
provides similar functionality for its application
development without the need for an additional library. The function inb() is used
to read a single byte from an I/O port while the function outb() writes a single
byte to an I/O port. Additional routines, ioperm() and iopl(), are needed to grant
the application permission to access the ports. Both of these routines are found
in the sys/io.h include file when using the glibc libraries. The syntax for these
Figure 17. VB code to send data to parallel port
Private Sub Send_data_Click()
'Declare one variable to hold the I/O address and
'another to contain the data to send to the port.
Dim port_address, out_value As Integer
'Determine which address the parallel port is at:
Select Case (Port_addr.ListIndex)
Case Is = -1 'Default start for combo box
port_address = &H378
Case Is = 0
Case Is = 1
Case Is = 2
port_address = &H3BC
End Select
'Next, retrieve the data to output
out_value = Val(out_data.Text) And 255
'Lastly, send the data to the port using the
'Out function
Out port_address, out_value
End Sub

and other I/O port functions is presented below(Rubini & Corbet, 2001, pp. 230-
232). Note that this list is not comprehensive.
• unsigned inb(unsigned io_port)—inb() reads a single byte (8 bits) from
the I/O port at address io_port.
Figure 18. VB code to receive data from parallel port
Private Sub Get_data_Click()
'Declare a variable to hold the I/O address
Dim port_address As Integer
'Determine which address the parallel port
'status is at:
Select Case (Port_addr.ListIndex)
Case Is = -1 'Default start for combo box
Case Is = 0
Case Is = 1
Case Is = 2
port_address = &H3BD
End Select
'Retrieve the data from the parallel port
in_data.Text = Inp(port_address)
End Sub
a. Parallel port device b. Application screen shot
Figure 19. Parallel port I/O device and corresponding control application

222 Tarnoff
• unsigned inb_p(unsigned io_port)—inb_p() reads a single byte (8 bits)
from the I/O port at address io_port then pauses to allow I/O device time
to process the command. This is specifically for older platforms where the
I/O devices could not keep up with the speed of the processor. Similar
functions are available for the other “in” commands.
• unsigned insb(unsigned io_port, void *addr, unsigned long count)—
insb() reads a string of count bytes from the I/O port at address io_port
and stores the string starting at memory address addr.
• unsigned inw(unsigned io_port)—inw() reads a word (16 bits) from the
I/O port at address io_port. This function is not universally supported and
is not in common use. Its operation can be duplicated with two successive
inb() function calls.
• int ioperm(unsigned long from, unsigned long num, int turn_on)—
ioperm() sets the I/O port permissions to a value of turn_on for num port
addresses beginning with address from. ioperm() only works for I/O ports
0 through 0x3FF (decimal 1023). iopl() must be used to grant permission to
the remaining ports. turn_on is a boolean-type value: 1 allows access and
0 disallows access. To set an I/O port’s permission to anything other than
0, the calling process must have CAP_SYS_RAWIO capability. This
capability is inherent for the user root but may also be granted using setid.
ioperm() returns 0 on success and –1 on error.
• int iopl(int level)—iopl() changes the privilege level of all I/O ports to the
value level for the calling process. Be sure to use ioperm() when accessing
ports below 0x3FF because iopl() could leave the system vulnerable to
problems such as accessing the incorrect port or disabling interrupts.
Setting level equal to 3 grants the calling process permission to access the
ports while setting it to 0 removes those privileges. iopl() returns a 0 on
success and a –1 on error.
• void outb(unsigned char val, unsigned io_port)—outb() writes a
single byte val to the I/O port at address io_port.
• void outb_p(unsigned char val, unsigned io_port)—outb_p() writes a
single byte val to the I/O port at address io_port then pauses to allow I/O
device time to process the command. This is specifically for older platforms
where the I/O devices could not keep up with the speed of the processor.
Similar functions are available for the other “out” commands.
• void outsb(unsigned io_port, void *addr, unsigned long count)—
outsb() reads a string of count bytes from the memory address starting at
addr and outputs them to the I/O port at address io_port.
• void outw(unsigned short val, unsigned io_port)—outw() writes a
word val to the I/O port at address io_port. Like inw(), this function is not

universally supported and is not in common use. Its operation can be
duplicated with two successive outb() function calls
In order to access the I/O ports, begin by setting the privileges for accessing the
port using ioperm() or iopl(). In Linux, this will require root privileges for the
user running the application.
Once your process is allowed access to the ports, use the “in” functions to
retrieve data from a port and the “out” functions to send data to the port.
Advanced I/O Techniques
For the hobbyist, the description of I/O port communication up to this point is
sufficient. For the programmer who is developing device drivers or operating
system code, the concepts of I/O port communication must be taken further. This
is because the method used by the programmer to communicate with the I/O
ports directly affects the performance of the processor.
The Visual Basic application presented in this chapter represents the simplest
form of I/O. In order to detect any changes on the inputs of the parallel port, the
application must constantly read the input pins. For example, the text box that
displays the values of the status lines remains static unless the Get_data button
is pressed. This method of monitoring I/O is called programmed I/O, and it is
known for its poor performance.
There are three problems with this method. First, data might be missed if the
inputs are not read often enough. Second, it is impossible to determine with any
accuracy the moment at which the input data changed. Both of these problems
can be resolved by increasing the rate at which the inputs are read. This,
however, comes at a price. By forcing the processor to continuously monitor its
inputs, considerable processing time is eaten up without having much to show for
it. The majority of the reads are not going to show any change in the input values.
A second method takes the burden off of the processor and places it on the
device. Interrupt driven I/O gives each device the ability to “call” the processor
to tell it that there is new data available. The data might tell the processor that
there has been a change at the inputs, that a process has completed, or that the
device’s outputs are available. The call to the processor demanding service is
called an interrupt.
It is as if someone was reading a book when the telephone rings. The reader,
concerned about keeping her place in the book, places a bookmark to indicate
where she left off. She then answers the phone and carries on a conversation

224 Tarnoff
while the book “waits” for her attention to return. While chatting on the phone,
the person notices her dog standing at the door waiting to be let out. She tells the
person on the other end of the line, “Hold that thought, I’ll be right back.” After
she lets out the dog, she returns to the phone and picks up the conversation where
she left it. When she finishes talking on the phone, she hangs up and returns to
her reading exactly where she left off.
This analogy reflects how the computer handles devices that need service. When
a device interrupts the processor, the processor remembers where it was at by
storing the current condition of all variables, the address of the line of code it was
currently executing, and any other information it would need to restore its
operation. Once this is done, it can execute a function that will handle the
device’s request. This function is called an interrupt service routine (ISR). By
using interrupts and the corresponding ISRs, the processor is able to concentrate
on running applications while it is the responsibility of the devices themselves to
watch their inputs.
It is important to note that the programmer does not have to write any function
call in their code to access the interrupts. The processor maintains a list of the
ISRs that correspond to each device. When a device interrupts the processor, the
processor halts the execution of the main code, looks up the address of the
appropriate ISR, and jumps to it. Once the ISR is complete, the processor
restores itself so that it picks up the main code where it left it. Figure 20 presents
a basic diagram of this operation.
In order to support the use of interrupts for external devices, a processor must
have one additional output and at least one additional input. The processor uses
the input to receive the interrupt request from the device. This input is referred
to as the interrupt request, or IRQ, input. The additional output from the
processor is called an interrupt acknowledge. The processor uses this output
Figure 20. Basic operation of an ISR
Main program
.
.
.
.
.
Interrupt Service
Routine
Return when done
Upon receiving an interrupt
request, the CPU stops execution
of code to execute ISR
Once ISR is finished,
CPU returns to where it left off

to tell the device that is requesting service that the interrupt was received and
will be handled. It is the processor’s way of saying, “Okay, you can stop calling
now.”
This means that for a device to be able to take advantage of interrupts, it must
also have an additional output and an additional input. The device changes the
level on the digital output when it needs service and watches the level on the input
to see when the processor has acknowledged the request. On the parallel port,
the device output is connected to pin 10 of the 25-pin interface. If conditions are
right and the level on this input pin changes, an interrupt is issued to the processor.
For the processor to detect an interrupt, the interrupt must first be enabled. This
is handled at two levels. The processor itself has a global setting that enables and
disables the majority of the external interrupts. This is usually handled by a single
bit or flag in the processor that is controlled by the operating system.
There are also enable flags at the device level. A control register within each
device contains one or more flags that are used to enable and disable the device’s
interrupts. When interrupts are disabled at the local or device level, the IRQ
output from the device remains at the level that the processor interprets as idle.
For the parallel port, local enabling of interrupts is done with bit 4 of the control
register. By setting the bit to a 1, a change on the ACK input (pin 10) from a low
to a high value will cause an interrupt to be sent to the processor. If the processor
has globally enabled interrupts, it will execute the parallel port’s ISR. The
creation and installation of a user-defined ISR are highly dependent on the
processor operating system and are beyond the scope of this discussion.
Conclusion
Regardless of the special needs of each I/O device in a computer system, there
are standard methods of communicating with a computer system’s I/O. These
methods have been designed to allow an operating system or an application to
communicate with the physical world. Through an understanding of device
addressing and the details of the I/O device’s resources, data may be collected
or processes may be controlled from any computer.
The interaction between a processor and its I/O devices is similar to its
interaction with memory. Data is passed to and from registers in the device using
addresses just like memory. Some processors, including the Intel 80x86 family
of processors, distinguish I/O transactions from memory transactions by using
different machine-language instructions. To handle this difference, a special set
of functions is used to store data to and retrieve data from the I/O device. These

226 Tarnoff
functionsmaybeaccessedfrommanydevelopmentsystems,includingMicrosoft’s
Visual Studio and GNU’s Compiler Collection (gcc).
Finally, in order to improve performance, processors use a hardware-based
system of device service requests called interrupts. All operating systems and
many applications use interrupts to avoid the overhead of having to constantly
watch an I/O device’s status.
Summary
It is important that students grasp the basic concepts of communication between
a processor and its external devices and to become familiar with tools that are
available to implement such systems. This chapter described the operation of the
processor bus, I/O connectivity, and the PC parallel port along with its interface.
By configuring a PC parallel port, students develop the basic concepts in both
hardware and software. The control and sensor circuitry is presented along with
some of the tools used for testing them. Some advanced I/O techniques are also
presented.
Key Terms and Definition
Bus contention: This is an erroneous condition that occurs when multiple
devices attempt to put data on the data lines of the bus at the same time.
Daisy-chaining: This is a configuration that connects the inputs of multiple
devices together using a single conductor.
Data acquisition: The discipline of sampling signals from the physical world so
that the data can be analyzed or processed by a computer.
Device interface: Sometimes referred to as a transducer, it is the circuit
element that converts physical phenomenon to electrical signals and
eventually to digital values readable by the processor.
Digital logic probe: A simple test device that is used to sense whether a binary
1 or a binary 0 is present on a digital conductor.
DLL: Stands for dynamic link library. This is a library of functions that are
available to the applications of an operating system at runtime. They are not
required to be part of the compile process, rather they are loaded as needed
when the application is executed.

IC: Stands for integrated circuit. This is the circuitry contained within a chip or
component of the circuit board of a computer system.
I/O port: A bus on the Intel 80x86 processors that uses the same address and
data lines as the memory bus but different read and write control lines.
LED: Stands for light-emitting diode. This is a solid-state device that glows
brightly when a small current passes through it from one input to the other.
Review Questions
1. Explain how a processor communicates with I/O devices.
2. Discuss the basic organization of an external I/O device.
3. Define the following terms: bus, data lines, address lines, and read and write
control lines.
4. Draw a block diagram to illustrate the interaction between a CPU and a
memory.
5. Draw a block diagram to illustrate the basic interface to a memory device.
6. Discuss the difference between memory and I/O port communication of a
typical Intel 80x86 processor.
7. Describe the pin configuration of a typical DB25 parallel port.
8. Describe the function of control, status, and data output registers.
References
Axelson, J. (2003). Inpout32.dll. Logix4u. Retrieved December 9, 2004, from
http://www.logix4u.cjb.net/
Moore, G. (1965, April 19). Cramming more components onto integrated
circuits. Electronics Magazine.
NTPort Library. (2002). Zeal SoftStudio. Retrieved December 9, 2004, from
http://www.zealsoftstudio.com/ntport/
Rubini, A., & Corbet, J. (2001). Linux device drivers. O’Reilly & Associates.
Tarnoff, D. (2003). ETSU/CSCI embedded systems course notes: Digital
input and output. Retrieved July 8, 2003, from Eastern Tennessee State
UniversityWebsite:http://faculty.etsu.edu/tarnoff/ntes4956/Ch03_v02.pdf

228 Tarnoff
Tarnoff, D. (2004). Incorporating embedded system design into a CS curricu-
lum. In Proceedings of the 2nd Annual Mid-South College Computing
Conference (pp. 131-140).
Vbasm.dll. (1997). SoftCircuits Programming. Retrieved December 9, 2004,
from http://www.softcircuits.com/sw_tools.htm
Win95io.dll. (1997). SoftCircuits Programming. Retrieved December 9, 2004,
from http://www.softcircuits.com/sw_tools.htm
Endnotes
1
80x86 is a general reference to the Intel family of processors beginning with
the 80286 continuing through to the current-day Pentium processors.
2
In Linux, when compiling code used to access the I/O ports using the
routines mentioned in this text, set gcc to compile with optimization turned
on using the –O option.

PIC-Based Projects 229
ChapterXII
EnhancingTeaching
andLearning
ComputerHardware
FundamentalsUsing
PIC-BasedProjects
Abstract
Computer hardware, number systems, CPU, memory and I/O (input/output)
ports are topics often included in computer science, electronics, and
engineering courses as fundamental concepts involved in computer
hardware. We believe that students learn computer hardware fundamentals
better if they are given practical learning exercises that illustrate theoretical
concepts. However, only a limited range of material designed specifically
to supplement the teaching of computer hardware concepts is publicly
available (see http://sigcse.org/topics/, the SIGCSE Education Links page
on the Special Interest Group on Computer Science Education Web site).

230 Sarkar & Craig
This chapter describes a set of PIC-based projects that give students a
hands-on introduction to computer hardware concepts and are suitable for
classroom use in undergraduate computer hardware courses.
Learning Objectives
• Discuss the usefulness of PIC projects in teaching and learning contexts.
• Set up PIC-based projects for class demonstrations.
• Define the following key terms: RAM, ROM, LCD display, and
microcontroller.
• Suggest further enhancements to PIC projects described in the chapter.
Introduction
Not infrequently, it proves difficult to motivate students to learn computer
hardware fundamentals because many students appear to find the subject rather
technical, dry, and boring. To overcome this problem the authors have prepared
a set of projects that give students a hands-on introduction to computer
hardware. They are designed around the PIC16F84, a low-cost, powerful 8-bit
microcontroller chip and are suitable for classroom use in undergraduate
computer hardware courses. Students have evaluated the effectiveness of these
projects formally. The feedback from students indicates that the development
and implementation of the projects were successful. This chapter describes the
PIC-based projects, their overall effectiveness, and plans for further projects.
Computer hardware, digital systems design, number systems, CPU, memory,
and I/O (input/output) ports are topics often included in computer science,
electronics, and engineering courses as fundamental concepts involved in
computer hardware. We believe that students learn computer hardware and

organization better if they are given practical learning exercises that illustrate
theoretical concepts. However, only a limited range of material designed
specifically to supplement the teaching of computer hardware concepts is
publicly available, as searches of the Computer Science Teaching Center Web
site (http://www.cstc.org/) and the SIGCSE Education Links page (http://
sigcse.org/topics/) on the Special Interest Group on Computer Science Educa-
tion Web site reveal.
We strongly believe, as do many others (Abe et al., 2004; Bhunia, Giri, Kar,
Haldar, & Purkait, 2004; Hacker & Sitte, 2004; Leva, 2003; Williams, Klenke,
& Aylor, 2003), that students learn more effectively from courses that provide
for active involvement in practical activities. Towards that end, we are develop-
ing some interesting and entertaining projects that facilitate an interactive,
hands-on introduction to traditional computer hardware concepts. These projects
are designed around the PIC16F84 microcontroller chip (8-bit, 4MHz) and can
be used either in the classroom as a demonstration to enhance the traditional
lecture environment or in the laboratory to provide practical hands-on experience
at an introductory level.
Computer hardware concepts are described in many references (Englander,
2000; Shelly, Cashman, & Vermaat, 2003; Tanenbaum, 1999), and the PIC
microcontroller is discussed extensively in the computer hardware literature
(Iovine, 2000; James, 2001; Morton, 2001; Predko). Rowe (2003) describes
several low-cost PIC programming kits designed for the PIC16F84 chip, and
Smith (2003) deals with MS Windows 2000 and XP-based PIC programming
software for a PIC programmer. Assembled modules that incorporate one or
more PIC microcontrollers, such as those described in Comfile Technology
(2003), are available commercially.
A number of sophisticated simulators exist for building a variety of computer
architecture models (Bem & Petelczyc, 2003; Ibbett, 2002; Shelburne, 2003).
However, these powerful tools can have a steep learning curve, and while
excellent for doing an in-depth performance evaluation of computer hardware,
they often simulate a hardware design environment in far more detail than is
necessary for a simple introduction of fundamental concepts. Nevertheless, by
setting up PIC projects, the students gain firsthand experience that cannot be
gained through computer simulation and modeling. To date, we have focused on
developing some demonstration projects to support teaching computer hardware
and organization. These projects are described in some detail in this chapter
along with our plans for future projects.
The remainder of this chapter is organized as follows. In the first section, we
discuss the PIC microcontroller environment; followed by the second section,
where we describe a series of interesting projects completed to date and plans
for future projects. The main benefits of PIC projects are then highlighted in the

232 Sarkar & Craig
third section. This is followed in the next section by a discussion of the
implementation of PIC-based projects in laboratory settings. The conclusion
follows the fifth section, in which the effectiveness of the PIC-based projects is
evaluated and interpreted.
PIC Environment:
Hardware and Software
Microcontrollers contain the essential features of a computer on a single silicon
chip — CPU, memory, I/O ports, and timing and control circuitry. They are
frequently found in roles befitting their name, namely, controlling devices such
as VCR or DVD players, and in motor vehicles, trains, and planes, where the
tasks at hand require computer control but do not require an extensive memory
or processing capacity. Some microcontrollers have additional circuitry, such as
an analogue-to-digital (A/D) converter, built in, which makes them particularly
useful in certain applications (James, 2001; Morton, 2001). The electrically
erasable programmable read-only memory (EEPROM) built into the PIC16F84
is particularly useful in the classroom as it enables the PIC to be reprogrammed
many times over as students develop new programs. The computer-in-miniature
aspect of microcontrollers makes them an ideal aid for teaching and learning
about computer hardware and software principles. For example, the Harvard
architecture of the PIC16F84 illustrates a computer architecture different from
the von Neuman architecture commonly found in larger computers.
Once a program has been written for a microcontroller, the program has to be
entered into the memory of the microcontroller. With the PIC16F84 this can be
achieved using the programmer module shown in Figure 2. Iovine (2000)
presents details on the availability of this module and the associated software.
The software supplied with the programmer module enables programs written in
BASIC on a PC to be quickly transferred to the PIC microcontroller. Iovine
provides a step-by-step guide to creating programs for the PIC that become more
advanced as the student’s experience grows. The short turnaround time between
program writing, installing the program in the EEPROM, and testing the PIC in
the circuitry developed on the breadboard makes this amalgam of hardware and
software particularly effective as a learning tool.

Description of PIC Projects
Table 1 lists the five projects that have been developed to date and which were
trialed over a period of one semester in our IT Concepts and Skills diploma
course. This course is at level 4 or 1st year diploma in information technology at
the Auckland University of Technology (AUT).
Project 1: Data Representation
This introductory project demonstrates to students the basic concepts of bits,
bytes, and binary numbers. In lectures, the basic concepts of number systems are
introduced, and students are shown how to convert from binary to hex and vice
versa. The teacher then demonstrates the project to the class to illustrate the
theoretical concepts of bits, bytes, and a binary sequence counter. Through
active participation in the demonstration and hands-on activities, students gain
basic knowledge about the binary number system. Figure 1 shows the breadboard
with eight LEDs (light-emitting diodes) and the PIC programmed to output
10011011. Figure 2 shows the PIC programmer module that connects to the PC
parallel port via a ribbon cable connected to the 25-pin D-socket located at top
right on the module. Figure 3 shows a ZIF (Zero Insertion Force) socket and
associated cable that can be connected to the PIC programmer module via the
socket located at center left in Figure 2. Using the ZIF socket, instead of the DIP
socket provided on the programmer board (see Figure 2), reduces the chance of
pin damage to the PIC while it is being inserted in or removed from the
programmer module.
Table 1. PIC-based projects and related hardware concepts
Projects Hardware concepts
1.Data representation Binary sequence, bits, nibbles, bytes.
2.Memory Memory addressing, flash memory, RAM, ROM, EEPROM.
3.LED matrix Nibble, word, decoding, encoding, LED matrix, voltage and
logic levels, switches, non-interlaced scanning.
4.LCD display CPU and registers, I/O port, LCD display.
5.Speech generation Processor, serial-to-parallel shift registers, amplifier.

234 Sarkar & Craig
Project 2: Memory
The basic concepts of memory addressing, random access memory (RAM),
flash memory, read-only memory (ROM), and electrically erasable program-
mable ROM (EEPROM) are introduced during lectures. This project shows
students how digital data can be read from and written to RAM. Students also
gain hands-on experience in reading data from and writing data to EEPROM,
whether this is located within the PIC16F84 microcontroller or externally on the
breadboard.
Figure 1. The eight-LED display (Project 1) represents the 1-byte word
10011011. The four yellow LEDs correspond to the most significant bits
and the four red LEDs to the least significant bits.
Figure 2. PIC programmer module

Project 3: LED Matrix
Although initially the projects followed closely the projects described in Iovine
(2000), the students were encouraged to experiment once they had mastered the
concepts in the original design. An example of this development is seen in Figure
4, which shows an LED matrix module attached to the breadboard. The
description of Project 3 that follows illustrates the many opportunities for turning
principle into practice that PIC projects can present to students. In particular,
students will learn about the way the 8 individual bits that make up a byte can be
manipulated and utilized for purposes other than counting. The description of
Project 3 and the project itself aptly illustrate the Chinese adage, attributed to
Confucius (551-479 BC), “I hear, I know. I see, I remember. I do, I understand.”
As in Project 1, the PIC in Project 3 is programmed to produce 1-byte words.
However, in addition to lighting the appropriate LEDs, which can be seen near
the top left-hand corner of the breadboard, the 1-byte word in Project 3 is split
into two 4-bit nibbles. These in turn are sent to two 74LS154 ICs (seen at the
bottom of the matrix module), each of which activates 1 of its 16 output ports in
accordance with the 4-bit input. Each of these output ports is linked to a column
or a row of the LED matrix — in effect producing an (x, y) coordinate pair. Each
point on the 16x16 LED matrix corresponds to an 8-bit word. By programming
the PIC to produce the correct sequence of 8-bit words, a display such as that
shown in Figure 4 can be produced. This project also illustrates the distinction
between logic levels and voltage levels. To turn an individual LED at (x, y)
requires a positive voltage to be applied to row y, but the voltage level on a
74LS154 output port goes low when that port is selected. Consequently, four
74LS04 hex inverters were inserted between the 74LS154 connected to the 16
rows and the LEDs. These are seen on the left of the display.
Figure 3. ZIF (Zero Insertion Force) socket

236 Sarkar & Craig
If the matrix board is connected to the breadboard as shown in Figure 3 when
the microcontroller is programmed with the binary counting program used in
Project 1, a sequence of LEDs will light, starting at the bottom left-hand corner
of the matrix (position (1,1)) and proceeding along each row in turn until the top,
or 16th, row is reached (position (16,16)). At the end of the 16th row, the
sequence repeats, starting at position (1,1). The students’ attention can be drawn
to the identical nature of this “scanning” of the LED matrix and the scanning that
occurs in a computer monitor, noting the rapid fly-back period when the “spot”
moves from the end of one line to the beginning of the next line (or the next scan).
This analogous situation can be further exploited by asking the students how the
displayed scanning procedure differs (if at all) from the nature of the scanning
procedure in a television receiver. Students can be reminded that television uses
interlaced scanning in order to conserve bandwidth while simultaneously reduc-
ing flicker on the television screen to a level acceptable by viewers. A
comprehension question for students is to ask them to replicate interlaced
scanning of the LED matrix via either modifying the binary counting program in
Project 1 or by modifying the hardware on the breadboard in some way, or
perhaps by some method involving both the program and the hardware. If the bits
in the byte produced by the binary counting program and displayed on the 8 LEDs,
as shown in Figure 1, are labeled b0 to b7, then bits b0 to b3 are used in Project
3 to control the x-coordinate on the LED matrix and bits b4 to b7 are used to
control the y-coordinate. An illustration of the interplay between software and
hardware solutions to problems is provided by simply changing the order in which
the b4 to b7 bits are presented to the LED matrix board. This can be easily
achieved on the breadboard by moving connector wires from b4, b5, b6, b7 to b7,
b4, b5, b6. This action results in the odd lines (1, 3, 5, … 13, 15) of the LED matrix
being scanned first, followed by the even lines (2, 4, 6, … 14, 16) being scanned.
The scan then starts again at line 1.
Figure 4. LED matrix display (Project 3)

The brightness of the LEDs depends on the total number of LEDs that are lit in
the display. More LEDs being lit means a shorter duty cycle for each individual
LED, thereby reducing the brightness. This aspect can be addressed by
increasing the current supplied to each LED, which can be achieved by reducing
the value of the current limiting resistor used in series with each row in the matrix
display or by increasing the voltage applied across the resistor and LED series
circuit. Both of these outcomes can be brought about by connecting an NPN
transistor between each LED and its series resistor, while using the positive 5-
volt output of the TTL inverter ICs (74LS04) to provide, via a suitable resistor,
the base drive for the transistor. A measure of control over the brightness of all
the LEDs could then be achieved by supplying the transistors through a single
variable resistor connected to the 5-volt supply. Although potted LED matrix
units and LED matrix controller ICs are available commercially [18], the authors
consider that these items would be more suitable for a follow-up project rather
than as an initial introduction to the principles involved. The slight variation in the
brightness exhibited amongst even just 256 LEDs provides students with a better
appreciation of the difficulties that manufacturers have when producing high-
quality active matrix displays involving thousands of components. The photo-
graph in Figure 4 has been retouched to improve the clarity of the LED matrix
display.
Project 4: LCD Display
This project utilizes a serial bit stream generated by the PIC 16F84 to create a
two-line display on an LCD readout. The project follows the description in Iovine
(2000), but innovation on the part of the student is possible in the way that the
PIC is programmed and in the content of the displayed message. This aspect of
this project is enhanced when it is combined with the speech generator in Project
5. Figure 5 shows the LCD displaying the message “Hi Nurul, how is life at the
AUT?”
Project 5: Speech Generation
This project is based around the SPO256 Speech Generator IC, which can
produce 59 allophones. Although the speech produced does not sound completely
natural, it is of sufficient quality to be easily comprehended. Iovine (2000)
describes in detail the use of a serial-to-parallel converter (74LS164) to increase
the number of I/O lines available from the PIC. This allows the PIC to control
the speech generator (SPO256) so as to produce speech through the speaker,
shown in Figure 5, and, at the same time, display on the LCD readout the words

238 Sarkar & Craig
coming from the speaker. This combined project tests the student’s mastery of
the concepts (hardware and software) presented in the previous projects, and
many students appear to respond positively when their creation speaks and
displays its “first words.”
By changing the clock frequency of the speech generator chip (by substituting
a different crystal) or by using different resistors and/or capacitors to form the
low-pass filter that precedes the audio amplifier IC (LM836), students can gain
firsthand experience of the influence that changing the frequency content of an
audio signal has upon the sound perceived by the listener. Some students found
that initially they were unable to obtain any sound from this project and that the
regulated voltage had dropped from 5 volts to 2 volts. Closer inspection revealed
that the filter capacitor on the output of the 7805 regulator IC had been omitted.
This resulted in a feedback loop being established, and the resulting oscillations
were the cause of the project failure. Provision of a 0.1-microfarad capacitor on
the 5-volt output pin of the 7805 regulator solved this problem and proved a useful
learning experience for the students.
Figure 5. LCD display (Project 4) combined with the speech generator
project (Project 5)

Additional projects: The following projects are being considered:
• Process control—DC motor control: The hands-on learning activities
include a real-time process control system.
• Pulse-code modulation—Analogue-digital converter: The learning
activities include sampling, analogue-to-digital converters, and serial-to-
parallel conversion.
• Wireless technology: Integrating both infrared data from a remote
control and Wi-Fi radio signals into the PIC projects to incorporate some
aspects of data communications.
• Open: A category for student-suggested projects.
Benefits of PIC-Based Project
The PIC-based projects provide the following benefits:
• Low cost: The current street price of a PIC16F84 is $7.5.
• Easy to use: PIC-based projects are easy to use and set up for demonstra-
tions.
• Hands-on: PIC projects facilitate a hands-on introduction to computer
hardware concepts.
• Programmable: The PIC16F84 can be reprogrammed many times over as
students develop new programs for a variety of projects.
• Challenging: The PIC projects provide the students with a challenging yet
friendly environment in which students can test their knowledge of com-
puter hardware.
• Usefulness: The PIC projects can be used either in the classroom or in the
laboratory to provide hands-on experience.
• Economical/Reusability: Some hardware components of PIC projects
can be reused in developing a variety of projects on a breadboard.

240 Sarkar & Craig
Example of PIC Programming
In this example program (see Table 2), single bytes are placed on the B port pins
of the PIC. If an LED is connected to one of these pins via a suitable current
limiting resistor, the LED will be lit when the voltage on that pin goes high.
Alternatively, this same high (approximately 5 volts) voltage can be used to
control other devices. For example, if the value sent to Port B is 242 (decimal),
this corresponds to the byte 11110010, which would make the x-nibble described
in Project 3 (LED matrix) to be 0010 and the y-nibble to be 1111. In decimal
notation, these x and y values correspond to column 2 and row 15. And so this
program would result in the LED located at the intersection of column 2 and row
15 being lit, if only for approximately 50 ms. This event will recur once the
program loops back to the beginning, so because of the 4 MHz clock speed of
the PIC and because of persistence of vision, the LED may appear to be
constantly lit.
By assigning different numbers to be “poked” into Port B, different displays, such
as a smiley face, as here, can be created. Such changes to the program can be
carried out using a word processor such as MS Word or Notepad. The changed
program is then compiled using the EPIC compiler. The hex file created by the
compiler can then be burned into the PIC memory using the EPIC software and
PIC programming board (Figure 2). By inserting the reprogrammed PIC into the
breadboard (Figure 4), the new pattern on the matrix display can be observed.
This cycle can easily be repeated until the desired display is obtained.
PIC Projects in Laboratory Settings
Figure 6 illustrates how PIC projects can be set up and used in a typical computer
laboratory to provide a hands-on learning experience in computer hardware and
organization. A typical medium-sized computer laboratory with 25 computers
allows a class size of up to 25 students. As seen in Figure 6, the PIC compiler
and associated software are installed and run on a stand-alone PC (labeled Old
PC), which is linked to a PIC programmer via a printer port (DB25-pin
connector). The reason for using a stand-alone PC is to have a single copy of the
PIC compiler, which is more economical and eliminates the need for multiple
licensing.

Table 2. Source code for binary counting program
'Program: Binary Counting
'Initialize variables
Symbol TRISB = 134 'Assign TRISB for port B to decimal value of 134
Symbol PortB = 6 'Assign the variable PortB to the decimal value 6
'Initialize Port (s)
Poke TRISB, 0 'Set port B pins to output
Loop:
'For B0 = 0 to 15
'Poke PortB, B0
'Next B0
Poke PortB, 242 'Place B0 values at port to light LEDS
Pause 50
Poke PortB, 250
Pause 50
Poke PortB, 251
Pause 50
Poke PortB, 252
Pause 50
Poke PortB, 253
Pause 50
Poke PortB, 254
Pause 50
Poke PortB, 226
Pause 50
Poke PortB, 236
'Pause 5
Poke PortB, 209
'Pause 5
Poke PortB, 210
'Pause 5
Poke PortB, 211
'Pause 5
Poke PortB, 220
'Pause 5
Poke PortB, 192
'Pause 10
Poke PortB, 196
'Pause 10
Poke PortB, 204
'Pause 5
Poke PortB, 176
'Pause 5
Poke PortB, 180
'Pause 5
Poke PortB, 188
'Pause 5
Poke PortB, 165
'Pause 5
Poke PortB, 169
'Pause 5
Poke PortB, 149
'Pause 5
Poke PortB, 153
'Pause 5
Poke PortB, 133
'Pause 5
Poke PortB, 137
'Pause 5
Poke PortB, 117
'Pause 5

242 Sarkar & Craig
Poke PortB, 121
'Pause 5
Poke PortB, 102
'Pause 5
Poke PortB, 103
'Pause 5
Poke PortB, 104
'Pause 5
Poke PortB, 82
'Pause 5
Poke PortB, 90
'Pause 5
Poke PortB, 91
'Pause 5
Poke PortB, 92
'Pause 5
Poke PortB, 93
'Pause 10
Poke PortB, 94
'Pause 10
Poke PortB, 66
'Pause 10
Poke PortB, 76
'Pause 10
Poke PortB, 49
'Pause 10
Poke PortB, 50
'Pause 10
Poke PortB, 51
'Pause 10
Poke PortB, 60
'Pause 10
Poke PortB, 32
'Pause 10
Poke PortB, 36
'Pause 10
Poke PortB, 44
'Pause 10
Poke PortB, 16
'Pause 10
Poke PortB, 20
'Pause 10
Poke PortB, 28
'Pause 10
'Without pause, counting proceeds too fast to see
Rem Next B0 'Next B0 value
Goto loop
'end
Table 2. cont.
Figure 6. PIC programmer set up in a typical laboratory

Evaluation by Student Feedback
Student Experience
We offered PIC projects as a capstone project to two students who carried out
this project on their final semester towards the diploma in information technology
(DipIT) qualification. The students had completed most of the courses required
for DipIT qualification, including hardware fundamentals and data communica-
tions, before taking up the PIC projects. The project activities include: (1) setting
up and testing PIC-based projects; (2) demonstration of working prototype to
project supervisors; (3) evaluation of the effectiveness of PIC projects by
students’ feedback; (4) development of teaching resources (e.g., prototype
video) for classroom use; (5) written report, containing requirements analysis,
project plan, minutes of the meetings, summary of findings, and reflective
statements; and (6) oral presentation to audience of staff and students.
The PIC-based projects were completed successfully, and students indicated
that they had learned a great deal about hardware fundamentals by doing the
hands-on learning activities included in the PIC projects. This is evident from the
students’ reflective statements as follows:
Even though we passed the HF100 Hardware Fundamentals course before
taking up PIC projects, we did not learn much about hardware concepts
until we carried out PIC projects.
Hardware concepts should be taught by hands-on learning activities like
we did with PIC projects.
Classroom Evaluation
The effectiveness of PIC-based projects has been evaluated both formally by
students (through student evaluation forms) and informally through discussion
within the teaching team. The evaluation was conducted in the classroom with
DipIT students at AUT. A member of the teaching team conducted the
evaluation, and anonymity of the respondents was protected. Participation in the
evaluation was entirely voluntary. As part of the formal evaluation process,
students were asked to complete a short, five-question questionnaire as follows:

244 Sarkar & Craig
1. Prior knowledge: How well did you understand computer hardware
fundamentals before entering this course?
2. Easy to follow: How easy (overall) did you find the PIC-based projects to
follow?
3. Measure of success: How effective were the PIC-based project demon-
strations in helping you to improve your understanding of computer hard-
ware concepts?
4. Hands-on: Would you like to have more projects of this kind as part of your
course?
5. PIC programming: Would you prefer to learn to program the PIC
microcontroller in BASIC or in another language such as Assembler or C?
A 5-point Likert scale was used in the questionnaire. For questions 1 to 3, 1= poor
and 5 =excellent; for questions 4 and 5, 1=No and 5=Yes. Forty undergraduate
diploma students (60% male, 40% female) from the IT Concepts and Skills
course completed the questionnaire, and their responses were interpreted as
follows:
1. Twenty-six students indicated that they had no prior knowledge of com-
puter hardware before entering this course. Six students had a basic
knowledge of hardware; whereas the remaining 8 students were neutral.
2. The PIC projects were found to be reasonably easy to use and set up for
demonstrations. Twenty-eight students were satisfied with the demonstra-
tions and the hands-on experience, five students expressed some concern,
and the remaining 7 students were neutral.
3. Thirty students indicated that the PIC projects had clearly assisted them in
developing a better understanding of hardware concepts. However, three
students indicated that they were not totally satisfied with the PIC projects,
and the remaining 7 students were neutral.
4. Twenty-eight students indicated that they would like to have more hands-
on projects in the course. Four students were not very interested in trying
more projects, and the remaining 8 students were neutral.
5. Most students were not very familiar with using programming languages
(such as C or Assembler) to program microcontrollers and appeared to be
quite satisfied with using BASIC to program the PIC microcontroller.
We observed that by participating in the PIC-based projects and demonstration
activities, students became increasingly motivated to learn more about computer

hardware and enjoyed this course more than previous courses that consisted of
lectures only. We are seeking feedback regularly both from students and staff
for further improvement of the demonstration materials.
A set of new projects has been developed which can be used either in the
classroom for class demonstrations to enhance the traditional lecture environ-
ment or in the computer laboratory for hands-on practical experience in
computer hardware. Student responses to the project demonstrations were
mostly favourable. The students indicated that they had found the PIC-based
projects easy to use and helpful in gaining a better understanding of computer
hardware concepts. More projects such as an analogue-to-digital converter, a
DC motor controller, and an integration of both infrared data from a remote
control and Wi-Fi radio signals into the PIC projects are under development. Our
materials, including the source code for all PIC applications, are available at no
cost to faculty interested in using the PIC projects to supplement teaching their
computer hardware courses or as the basis for more complex projects. More
information about PIC-based projects and demonstration materials can be
obtained by contacting the first author.
Summary
Computer hardware is a challenging subject to teach and learn in a meaningful
way because many students appear to find the subject rather technical, dry, and
boring. This chapter describes a set of new PIC-based projects which can be
used either in the classroom to enhance the lecture environment or in the
laboratory to provide a hands-on learning experience in computer hardware. The
PIC projects are designed around the PIC16F84, a low-cost 8-bit microcontroller
chip. The projects are suitable for classroom use in introductory computer
hardware. The effectiveness of these projects has been evaluated by both
students and the teaching team. The students indicated that the PIC-based
projects are easy to use and helpful in developing a better understanding of
computer hardware concepts.

246 Sarkar & Craig
Computer hardware: Generally refers to electronic, electrical, and mechanical
components that make up a computer.
EEPROM: EEPROM stands for electrically erasable ROM. This type of
memory differs from ROM in that the contents can be changed if suitable
voltages are applied to the memory chip.
LCD displays: LCD stands for liquid crystal display, which is a flat panel display
that uses liquid crystal to present information on the screen. The liquid
crystal is contained between two sheets of transparent material. When an
electric current passes through the crystals, they twist. This causes some
light waves to be blocked and allows others to pass through, which creates
the images on the screen.
PIC BASIC: An adaptation of the BASIC computer language for use with PIC
microcontrollers.
PIC microcontroller: PIC stands for programmable interface controller. The
PIC microcontroller is an on-chip computer containing a CPU (central
processing unit), RAM (random access memory), programmable ROM,
timers, and input/output ports.
PIC programming: Generally refers to the procedures involved in creating a
sequence of instructions that can be installed in and acted upon by the PIC
microcontroller in order to control the operation of electrical and/or
mechanical equipment.
PIC projects: PIC-based projects which are developed to enhance teaching
and learning computer hardware concepts, as reported in this chapter.
RAM: RAM stands for random access memory. A class of memory that is used
in the computer as main memory for the storage and retrieval of data and
instructions by the processor and other devices.
ROM: ROM stands for read-only memory. A class of memory that is used in
the computer for storing data, instructions, or information that can be read
but not modified; the data is recorded permanently on the chips. ROM is
nonvolatile memory, meaning its contents are not lost when power is
removed from the computer.

Review Questions
1. List and describe three main benefits of PIC-based projects.
2. Discuss the usefulness of the PIC projects in teaching and learning
contexts.
3. Define the following key terms: bit, byte, binary number, RAM, ROM,
LCD, and EEPROM.
4. Describe how PIC-based projects can be set up for class demonstrations.
5. Explain how PIC projects can be used in the laboratory to enhance teaching
and learning computer hardware concepts.
6. List and describe further enhancements to the PIC projects.
References
Bem, E. Z., & Petelczyc, L. (2003, February 19-23). MiniMIPS—A simulation
project for the computer architecture laboratory. Paper presented at
the Proceedings of the 34th Technical Symposium on Computer Science
Education (SIGCSE’03), Reno, NV (pp. 64-68).
Bhunia, C., Giri, S., Kar, S., Haldar, S., & Purkait, P. (2004). A low-cost PC-
based virtual oscilloscope. IEEE Transactions on Education, 47(2), 295-
299.
Comfile Technology. (2003). What is PICBASIC. Retrieved September 20,
from http://www.comfile.co.kr/english2/study/pbstudy.html
Englander, I. (2000). The architecture of computer hardware and systems
software: An information technology approach (2nd
ed.). Wiley.
203.
Ibbett, R. N. (2002, June 24-26). WWW visualization of computer architecture
simulations. Paper presented at the 7th annual SIGCSE conference on
Innovation and Technology in Computer Science Education (ITiCSE),
Aarhus, Denmark (p. 247).

248 Sarkar & Craig
Iovine, J. (2000). PIC microcontroller project book. McGraw-Hill.
James, M. (2001). Microcontroller cookbook PIC & 8051 (2nd
ed.). Newnes.
Leva, A. (2003). A hands-on experimental laboratory for undergraduate courses
in automatic control. IEEE Transactions on Education, 46(2), 263-272.
Morton, J. (2001). PIC your personal introductory course (2nd
ed.). Newnes.
Predko, M. (2003). Some useful references on PIC microcontrollers. Re-
trieved September 20, from http://www.myke.com/
Rowe, J. (2003, April). Three do-it yourself PIC programmers. Silicon Chip,
58-65.
Shelburne, B. (2003). Teaching computer organization using a PDP-8
simulator. Paper presented at the SIGCSE’03 Technical Symposium on
Computer Science Education (p. 69-73).
Shelly, G. B., Cashman, T. J., & Vermaat, M. E. (2003). Discovering comput-
ers 2004: Complete. Course Technology.
Smith, P. (2003, July). Updating the PIC programmer and checkerboard. Silicon
Chip, 79-81.
Tanenbaum, A. S. (1999). Structured computer organization (4th
ed.). Prentice
Hall.
Williams, R. D., Klenke, R. H., & Aylor, J. H. (2003). Teaching computer design
using virtual prototyping. IEEE Transactions on Education, 46(2), 296-
301.

Assistant Tool for Instructors Teaching Computer Hardware 249
ChapterXIII
AssistantToolfor
InstructorsTeaching
ComputerHardware
with the PBL Theory
Maiga Chang, National Science and Technology
Program for e-Learning, Taiwan
Kun-Fa Cheng, Chih-Ping Senior High School, Taiwan
Alex Chang, Yuan-Ze University, Taiwan
Ming-Wei Chen, Chih-Ping Senior High School, Taiwan
Abstract
Students often get a good score in written exams but fail to apply their
knowledge when trying to solve real-world problems. This is applies
particularly to computer hardware courses in which students are required
to learn and memorize many key terms and definitions. Also, teachers often
find it difficult to gauge students’ progress when teaching computer
hardware fundamentals. These problems are related to the learning process,
so it is necessary to find an appropriate instructional model to overcome
these problems. This chapter describes a Web-based tool called the assistant
tool, which is based on problem-based learning (PBL) theory and not only
assists instructors in teaching computer hardware fundamentals but also
overcomes the above-mentioned problems.

250 Chang, Cheng, Chang, & Chen
Learning Objectives
• Discuss the usefulness of PBL theory in teaching and learning contexts.
• Discuss the effectiveness of the assistant tool in enhancing teaching and
learning computer hardware concepts.
• Define the following key terms: problem-based learning, brainstorm map,
concept map, and cooperative learning.
• Suggest further enhancements to the assistant tool proposed in the chapter.
Introduction
There are numerous key terms, definitions, and abstract concepts in computer
hardware fundamentals courses that students are required to learn and memo-
rize to pass the exam. Therefore, it is often difficult to motivate students to learn
computer hardware because many students appear to find the subject rather
abstract, technical, and boring. Teachers also find it a bit difficult to gauge
students’ progress in their classes.
There are two primary issues a teacher must investigate to gauge student
progress: (1) memorization, that is, how many terms or abbreviations students
have learned; and (2) relations between concepts (e.g., whether students know
that both Pentium and Athlon are processors or whether students know the
difference between a printer and a scanner). Memorization can easily be
measured by a simple quiz or test. However, determining whether a student
understands the relationships between concepts is not an easy task. Further-
more, a teacher needs to be assured that students have acquired the knowledge
required and understand the numerous abstract concepts.
Sometimes students make mistakes and incorrectly group together concepts on
different levels. For example, a student may have memorized ViewSonic VE700,
an output device, and incorrectly associated this with the CPU and motherboard
instead of Intel Pentium IV and IWill P4SE2. The questions arise, how can a
teacher teach students about the conceptual relations among computer compo-
nents and what concepts should a teacher provide as supplemental instruction.
To overcome the above issues and problems, we have proposed an assistant tool
based on problem-based learning (PBL) theory that can be used in assisting
instructors teaching computer hardware courses.

The author’s past teaching experience at a vocational school showed that
vocational students often obtain high scores on tests but fail when applying what
they have learned when trying to solve related problems in the real world. A
problem can then be said to exist in the learning process. It is necessary and
urgent to find an appropriate instructional model to resolve this problem in
education. In the 1960s, researchers at McMaster University in Canada obtained
a similar finding. They argued that students cannot apply education-based
knowledge and skills to their work (Albanese & Mitchell, 1993). To solve this
problem, the School of Medicine at McMaster University developed and applied
a PBL method for medical education (“What is PBL?”, 2004).
Problem-based learning is a student-centered teaching method in which students
are placed into small groups and the teacher acts as a facilitator or guide
(Barrows & Tamblyn, 1980). A poorly structured problem (real-life problem) is
used as a starting point for the instructional process in PBL (Simon, 1973), and
students acquire problem-solving and self-directed learning skills (Barrows,
1996).
According to Barrows (1996), there are several key characteristics of PBL: It
is student-centered, it employs small student groups, teachers function as
facilitators or guides, and instruction begins with unstructured problems. A goal
of PBL is to transform the teacher’s role from that of a lecturer to a facilitator
and the student's role from that of a passive observer to an active participant in
the learning process (Ahern-Rindell, 1999).
To motivate students, PBL employs realistic situations (unstructured problems)
to promote group discussions. These realistic situations can be used to create
relationships between their education and their professional lives. Unstructured
problems are utilized to force students to define problems for themselves, which
leads to learning by critical thinking. A brainstorm map, which is drawn by
student(s) according to their pre-learned knowledge, and group discussion can
enhance a student's ability to think creatively, reason critically, make decisions,
and communicate and cooperate with other students while exposing them to
different viewpoints. During a PBL activity, acquiring knowledge coincides with
solving the problem, enabling students to identify what they know and what they
need to know. Thereby, learning becomes meaningful.
Problem-based learning is based on several cognitive theories: constructivism,
situated learning, experimentalism, and cooperative learning.
A. Constructivism: Constructivism assumes that knowledge is not absolute
but rather constructed via the learning process and based on a learner’s

previous knowledge and their overall view of the world. According to
Savery and Duffy (1995), the three primary constructivist principles are (1)
understanding is a product of our interactions with the environment; (2)
cognitive conflict stimulates learning; and (3) knowledge evolves through
social negotiation and evaluation of individual beliefs. Constructivism then
is the basis for changing the student role from passive to active by placing
students into groups for discussion and social negotiation.
B. Situated learning: Situated learning argues that learning should take place
in realistic settings to make learning meaningful (Anderson, Reder, &
Simon, 1996; Brown, Collins, & Duguid, 1989; Young, 1993). There are
four primary claims of situated learning with respect to education principles
in situated learning: (1) Action is grounded in the concrete situation in which
it occurs; (2) knowledge does not transfer between tasks; (3) training by
abstraction is of little use; and (4) instruction needs to take place in complex
social environments (Anderson et al.). According to these principles,
instruction in the sciences should be rooted in real-world experience. The
situational nature of cognition renders education more effectively for
promoting student development of practical knowledge. This rationale,
perhaps, explains why students pass tests with high scores but have
difficulties solving real-world problems.
C. Experimentalism: Dewey (1938) argued that knowledge acquisition is a
product of perception and is active rather than static; that is, acquiring
knowledge is a process of discovery. Based on this notion of learning,
students can only learn from experience, that is, learning by doing.
D. Cooperative learning: Cooperative learning focuses on student interac-
tion (Ahern-Rindell, 1999). Cooperative learning must comprise the follow-
ing elements: positive interdependence, individual accountability, face-to-
face interaction, and, interpersonal skills (Johnson, Johnson, & Smith,
1991). Cooperative learning proposes that the different perspectives in a
group can enrich each member’s understanding. Furthermore, cooperative
learning can enhance critical and reasoning skills and enhance tolerance of
different perspectives.
The PBL method has been implemented for the last decade. Different from a
traditional education model, there are a number of instructional decisions that
need to be made based on factors such as class size, instructor preference, and
course objectives. Duch (2001) classified those models into four types to allow
instructors to teach large numbers of students: medical school model, floating
facilitator model, peer tutor model, and large class model. In the floating
facilitator model, the teacher is a facilitator working with groups no larger than
four to five students. When the teacher identifies confusion in a group, the

teacher may provide guidance to assist the group in resolving their confusion.
When all groups become stuck on the same issue, the teacher suspends group
discussions and discusses the issue with the whole class.
Figure 1 shows the eight steps in the PBL instructional template. Sage (2000)
noted that the teacher should be a coach and guide students and that students
must actively complete the problem-solving activity.
Teachers always need to gauge the progress of their students. Problem-based
learning allows teachers to measure student learning via a brainstorm map
constructed by students. The brainstorm map is created (Figure 2) when students
try to solve a problem proposed by a teacher. Since this map represents
concretely the concepts a student understands, teachers can use this map to
measure student knowledge and to guide the direction future classes should take.
The experimental lecture used in this chapter is a portion of a lecture on computer
hardware. The teacher is first asked to teach the fundamental concepts of the
computer components. Then, based on the PBL instructional theory, the teacher
poses a real-world problem for the students to solve. In this case, the problem
is for small groups of students to design their dream computer.
For Chinese students a dream computer is either a high-performance computer
or a computer that a student most wanted. Students are asked to discuss and
Figure 1. The instructional template of PBL units (Sage, 2000)
Critical PBL teaching and learning events
Prepare for learners
Meet the problem
Identify what we know
, what
we need to know, and our ideas
Define the problem
Gather and share
information
Gather possible solutions
Determine the“ best
fit” solution
Present the solution
Debrief the problem
Coaching students
• Teachers as coach
• Student as active learners
Embedded
instruction
assessments
iterative

create a brainstorm map for their dream computer. Students are required to
discuss and identify all details from the abstract level to the product level on their
brainstorm maps.
Students should, for example, discuss whether their dream computer needs a
display card. Then, if they decide that it needs a card, they have to discuss which
brand they want, WinFast or S3, then, in greater detail, they have to decide which
product they want, such as WinFast 3D S680 or S3 Tri64 D2/V2.
If the students pick the HP brand as their display card, then they may have an
incorrect conceptual relation between computer modules and computer acces-
sories. Actually HP does not have any display card accessories. Similarly, if
students decide they do not need a display card or forget to discuss whether they
need a display card, then they may have missed one or more concepts. These two
problems can be identified quickly by the teacher via the brainstorm maps.
However, as the brainstorm map is drawn by a small group (five to seven
students), it is difficult to understand at first (Figure 2). Moreover, when the PBL
process is applied to Internet teaching, the question arises, how can a teacher
rapidly provide students with feedback based on the student discussions. This
chapter presents a novel feedback tool based on PBL theory for Web-based
teaching. This feedback tool first retrieves discussion records from a database
and then restores the brainstorm map in hierarchical form to the concept-map
relational database management system (RDBMS). With the concept-map
Figure 2. Brainstorm map for force in physics (Hsu, Chen, Chang, & Yang,
2003)
NO.3
12/24
•
•
•
•
•
• •
(
•
•
)
•
•
•
•
2.
•
•
•
•
•
•
3.
•
•
•
•
•
•
•
•
•
•
•
•
m
g
,
k
g
,
g
.
.
.
{
•
•
•
•
•
•
•
(
•
•
•
)
•
•
•
•,
•
•,
•
•
•
• •
•
•
•
•
•
•
• • • •
• • • •
•
•
1
.
•
•
2
.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
{
1.
•
•
•
•
•
•
2.
•
•
•
•
•
•
•
•
•
•
•
.
•
•
•
• 1
.
•
•
2.
•
•
•
3.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
1.
•
•
•
•
•
•

RDBMS, the tool can replay the concept map to identify the differences of the
brainstorm maps of the students and the teacher.
There are several issues that will be involved when this feedback system is
developed. One major issue is who the system is designed for. This system is
designed to provide teaching suggestions to teachers rather than learning
methods to students. Another issue requires comparing methodologies for
identifying the differences of the brainstorm maps of the students and the
teacher. As we know, if teachers want to judge whether the brainstorm maps of
students are right or wrong, they must have their brainstorm map first. The
difference between traditional education and Internet-based education is that
when teachers teach in the traditional classroom, the map could be stored either
in the teacher's mind or in the computer, but the teachers must store the map in
the computer when they teach in the Internet-based environment. The final issue
is how to determine the sequence for teachers to provide the missed concepts
to students.
The most challenging task is how to communicate to the teacher which concepts
were missed by the students and how these concepts should be prioritized for
future instruction. It is considerably easier to teach with the PBL method on the
Internet if there is a tool that can provide feedback regarding the concepts
students have missed. Such a tool would allow the teacher to feel more
comfortable using PBL theory on the Internet. In the next section, the proposed
Web-based PBL environment and the novel assistant tool (feedback system) are
described.
There is considerable research into how to best implement PBL theory in a Web-
based learning environment (Hsu, Chen, Chang, & Yang, 2003). Chen, Kuo,
Chang, and Yang (2003) developed an instructional model for PBL-based
Internet learning called the Problem-Based Internet Assisted Learning System
(PBIALS). Figure 3 displays the pedagogical model of the PBIALS.
Although the brainstorm map represents the knowledge students have learned,
the concept map is easier for teachers to interpret (Figure 2). The concept map
(Novak, 1981; Novak & Gowin, 1984) was designed to represent what knowl-
edge students had learned and to aid teachers in determining the concepts that
students are lacking. The concept map is significantly more hierarchical than the
brainstorm map; the concept map is a semantic description of concepts and can
do whatever the brainstorm map can do (Jones, Palincsar, Ogle, & Carr, 1987).
Hence, the concept map was adopted in the development of the assistant tool.

Therefore, this chapter redevelops two parts of PBIALS, brainstorm time and
group discussion, to provide teachers with suggestions about the concepts
students lack. Although the brainstorm map is drawn by students during a
brainstorm discussion, this map does not allow teachers to quickly identify the
supplemental concepts students may require. To resolve this problem, the
assistant tool generates a concept map-like tree map, which is based on the
original brainstorm map and is stored in the discussion database in the PBIALS.
Before we present the assistant tool, the instructional process and the experi-
mental PBIALS should be first described. According to the instructional model
of the PBIALS, the instructional process is designed to include three major
stages in school and one for outside school: School I, School II, School III, and
Outside School. Figure 4 shows the whole instructional process. The rectangular
with single line in Figure 4 is the instruction function in the PBIALS, and the
double line represents the activity in class.
Based on the instructional process of the PBIALS designed in previous research,
the architecture of the PBIALS is systematically constructed by integrating
several tools for personal use, teamwork use, and recording (Figure 5). An
Internet virtual classroom (IVC) is a Web-based learning system with commu-
nity architecture, which supports knowledge management, community behaviors
(chat room/bulletin board, etc.), and personal tools (Chang, Chang, & Heh, 2000;
Lin, Chang, Cheng, & Heh, 1999). The instructional model/process of the
PBIALS is evaluated with the IVC system.
The assistant tool is designed as a feedback system for teachers while using PBL
theory to teach a class on computer hardware (Delisle, 1997; Gallagher, Sher,
Figure 3. Pedagogical model of the PBIALS
Grouping
Rule Introduction
Problem Presentation
Brain-storm Time
Group Discussion
Expert Speech or Seminar
Information Collection
Summative Assessment
Questionnaire
Formative
assessment
Coach
student

Figure 4. Instructional process of the PBIALS
Figure 5. System architecture of the PBIALS
School I
Login
Rule Introduction
Brain-storm Time
Whiteboard
Record
Logout
Information
Collection
End
Outside
School
Login
End
Problem
Presentation
Logout
School III
End
End
School II
1. Teaching Video
2. Computer Animation
3. Projection
Group
Discussion I
Discuss about Brain-
storm map
Group
Discussion II Discuss about PBL
Steps Recoder
Group
Discussion III
Speech or
Seminar
Group Report
Self Examination
Oral
Presentation
Conclusion
Questionnaire
1. Chat Room
2. Discussion
Area
3. Web Search
Engine
4. Library
5. Experts
Homework and
Report Upload
PBIALS
User
User
User
User
Web Server
(Tomcat)
Personal
Tools
Team
Tools
DataBase
Whiteboard
Brain-storm
Map
Presentation
Area
Chat
Room
Discussion
Area
Teaching
Material
File
Upload
Server
Client
Jsp + JavaScript
Learning
DB
Material
DB
Personal
Knoweldge
Solution
DB
Homework
Upload Area
Personal
Tools
Database
Team
Tools

Figure 6. Retrieved concept map for Team 8
Stepien, & Workman, 1995). The feedback system first retrieves the concept
map for each group from the discussion database which is integrated into the
PBIALS (the Learning DB and the Personal Knowledge in Figure 5). The
system then constructs the concept map for each team (Figure 6).
After constructing the concept map for each team, the system transforms the
concept map into a two-dimensional plane. The x-axis of the two-dimensional
plane is the concept-axis, and the y-axis is the abstraction level of the concept
Team8

(level-axis). This concept map is similar to a tree map in that its branches can
bend either left or right. The system will attempt to bend together those branches
in which the leaf concept nodes belong to the same abstraction level. Figure 7
illustrates the concept map for Team 8 on a two-dimensional plane after the
system bent (transforming) the original concept map (Figure 6).
Once the system merges both the teacher’s concept map and the students' map
on a two-dimensional plane (Figure 8), an adjustable baseline can be calculated.
By rotating the adjustable baseline until it approaches the teacher's baseline,
feedback identifying the concepts that require reteaching by teacher is gener-
ated. To generate the feedback, the system will rotate the adjustable baseline
incrementally. If the adjustable baseline touches a teacher concept that students
lack, then the system will report this to the teacher. This simple methodology is
employed because once students receive the supplemental materials from the
teacher, students will perhaps remember other things and correct their brain-
storm map accordingly. For example, assume a group of students lacks both a
display card and a sound card for designing their dream computer. When teacher
tells the students that they lack a display card in their brainstorm map, they might
Figure 7. Consequent concept map of Team 8 on a two-dimensional plane
CD-ROM
speaker
keyboard
video
card
SDRAM
DDR
SRAM
EDORAM
RAMBUS
SGARM
memory
mouse
cordless
optical
mouse
ABIT
Iwill
Soyo
GIGA
ECS
ASUS
MSI
mainboard
WD
Maxtor
Quantum
IBM40g
hard
disk
IBM
Seagate
concept
Level
Intel
CPU
1
2
0 NODE
Team 8
LINE
Team 8

recall that they are missing a sound card too. If so, the adjustable baseline will
be recalculated by the system.
The latest version of the assistant tool can be downloaded at http://
maiga.dnsalias.org/PBL/tools/feedback.htm.
Usefulness and Evaluation
of the System
Most assistant tools focus on how to best provide interactive services for
students. This chapter presents an assistant tool designed to provide teaching
recommendations for teachers based on PBL theory. In the PBIALS, students
use keyboards and a discussion database instead of pencils and paper during
discussions. The goal of this chapter is to provide a method that provides suitable
teaching suggestions to instructors teaching in PBL-based e-learning systems.
This novel assistant tool is integrated into the PBIALS. There is a discussion
database in the PBIALS that stores the discussion records for each team and can
Figure 8. Feedback according to the adjustable baseline
CD-ROM
speaker
keyboard
video
card
SDRAM
DDR
SRAM
EDORAM
RAMBUS
SGARM
memory
mouse
cordless
optical
mouse
ABIT
Iwill
Soyo
GIGA
ECS
ASUS
MSI
mainboard
WD
Maxtor
Quantum
IBM40g
hard
disk
IBM
Seagate
concept
Level
Intel
CPU
1
2
0 NODE
Teacher
Team 8
both
LINE
Teacher
Adjustable Baseline
Team 8

be retrieved by the assistant tool as previously described. Two questionnaires
were developed to do an assessment of the PBIALS and the novel assistant tool.
One questionnaire, the Curriculum Opinion Investigation, targets students learn-
ing about computer hardware through the PBIALS. The other questionnaire,
Satisfaction and Usefulness Investigation for the PBL Assistant, is for teachers
needing to make supplemental material with the assistant tool.
The Curriculum Opinion Investigation comprises two parts. The first part has 26
questions with answers measured on a 5-point Likert scale: strongly agree (SA),
agree (A), neutral (N), disagree (DA), and strongly disagree (SDA). The second
part has open questions allowing participants to make suggestions and ask
questions regarding any aspect of the PBL and PBIALS. The Satisfaction and
Usefulness Investigation also contains two parts, comprising five questions
measured on a 5-point Likert scale and two open questions.
Two teachers in two semesters were enrolled in the study. The participants,
roughly 50 students each semester (mostly male), were 1st-year students in the
Information Program at Chih-Ping Vocational School. After the teaching unit
finished, the questionnaire was handed out to the participants and teachers.
There were 59.4% of students who considered brainstorming time very useful,
allowing students to discuss and construct a specific map according to a given
objective.
Both teachers reported that the assistant tool identified what they should know
about the concepts the student groups lacked. The teachers also reported that
using the assistant tool, it was easy to identify the concepts and the appropriate
sequence in which they needed to be taught to students. Based on their
responses, this assistant tool will be significantly improved if it can provide instant
or, say, real-time feedback. Currently, the assistant tool is provided to teachers
after the discussion stage (in PBL theory) is completed. However, this discus-
sion stage covers more than one class, and students could also be allowed to
continue their discussions after class. Hence, the assistant tool should be able to
be used by teachers anytime during the discussion stage. To let teachers use the
assistant tool mid-discussion is not a difficulty as it requires only a minor
adjustment to the operational process of PBIALS; that is, the assistant tool is
always ready.
Conclusion
Applying assistant tools and feedback systems to the e-learning field is not new.
However, most of these applications focus on providing interactive services for
students. This chapter presents a new assistant tool that produces teaching

recommendations for teachers based on the PBL theory. The PBL theory is a
student-centered teaching strategy which allows students to discover knowledge
through small-group discussions. The teacher in this scenario acts merely as a
facilitator. The goal of this chapter is to develop a possible solution that provides
suitable teaching suggestions about students for instructors using a PBL-based
e-learning system.
According to the questionnaire results, the teachers reported that the feedback
tool was of considerable assistance in identifying and reporting what the students
(small groups) were learning and thinking. Moreover, it was easy for the
teachers to determine which concepts the students lacked and, thereby, teach
these concepts to students. This assistant tool also increased teacher comfort
levels when employing PBL theory.
The assistant tool was provided to teachers when the discussion stage (in PBL
theory) was complete. However, the discussion stage could cover more than one
class, and students could also be allowed to continue their discussions after class.
Teachers reported that the assistant tool would be much better if it could provide
instant or, say, real-time feedback; this feedback tool will be improved in the near
future to allow teachers to use it at any point during a discussion stage of the
PBIALS.
Summary
There are numerous key terms, definitions, and abstract concepts in computer
hardware courses that students are required to learn and memorize in order to
pass the exam. Therefore, it is often difficult to motivate students to learn
computer hardware fundamentals because students appear to find the subject
rather abstract, technical, and boring. Teachers also find it a bit difficult to gauge
students' progress when teaching computer hardware concepts. These problems
are related to the learning process, and therefore it is necessary to find an
appropriate instructional model to overcome these problems. This chapter
described a Web-based tool called the assistant tool, which is based on problem-
based learning (PBL) theory and not only assists instructors in teaching
computer hardware fundamentals but also overcomes the above-mentioned
problems.

Brainstorm map: A brainstorm map and discussion can improve students'
creative thinking and critical reasoning, communication, cooperation, and
decision-making skills and provide students with various viewpoints. Stu-
dents record their thoughts regarding what they already know and what
they need to know on a brainstorm map (Figure 2).
Concept map: A concept map is a knowledge representation commonly used
in education. It is a graphical node-arc representation illustrating the
relationship among concepts (Novak, 1981; Novak & Gowin, 1984). The
concept map, based on the cognitive map, can be in three forms: spider map,
chain map, and hierarchy map (Jones et al., 1987). Different concept maps
can be applied to handle different types of knowledge. The hierarchy map
was selected in this chapter for being easily understood.
Constructivism: Constructivism assumes that knowledge is not absolute but
rather constructed via the learning process and based on a learner's
previous knowledge and worldview.
Cooperative learning: Cooperative learning focuses on student interaction.
Cooperative learning exposes students to different perspectives that can
enrich their understanding. Cooperative learning can enhance critical and
reasoning skills and improve tolerance of and willingness to adopt new
concepts.
PBL: Problem-based learning is student-centered, uses small student groups,
and positions the teacher as a facilitator or guide. Life problems (real-world
problems) are used as the starting point for the instructional process in
PBL. Clinical problem-solving and self-directed learning skills can then be
learned via the learning process.
PBIALS: The instructional model of the PBIALS is similar to the instructional
template proposed by Sage (2000). There are eight principal stages
(excluding the questionnaire stage) in this instructional model (Figure 3).
Situated learning: Situated learning argues that learning should take place in
realistic settings to make learning meaningful. From this, we can infer that
scientific curriculum should be incorporated into students' experiences.
Without situated learning, traditional education loses its ability to teach
practical knowledge.

Review Questions
1. Discuss the difference between the PBL system and the traditional learning
approach.
2. Discuss the effectiveness of PBL theory in teaching and learning introduc-
tory computer hardware courses.
3. Discuss the difference between a brainstorm map and a concept map.
4. Discuss the architecture of the Problem-Based Internet Assisted Learning
System (PBIALS).
5. List and describe three main features of the assistant tool.
6. List and describe possible enhancements to the assistant tool.
References
Ahern-Rindell, A. J. (1999). Applying inquiry-based and cooperative group
learning strategies to promote critical thinking. JCST, 203-207.
Albanese, M. A., & Mitchell, S. (1993). Problem-based learning: A review of
literature on its outcomes and implementation issues. Academic Medicine,
68(1), 52-81.
Barrows, H. S. (1996). Problem-based learning in medicine and beyond: A brief
overview. New Directions for Teaching and Learning, 68, 3-11.
Barrows, H. S., & Tamblyn, R. M. (1980). Problem-based learning: An
approach to medical education. New York: Springer.
Brown, J. S., Collins, A., & Duguid, P. (1989). Situated cognition and the culture
of learning. Educational Researcher, 18(1), 34-41.
Chang, J. C., Chang, M., & Heh, J. S. (2000, October/November). Designing an
asynchronous/synchronouscombinationdistancelearningenvironmentbased
on Web-BBS. In Proceedings of WebNet 2000 (pp. 669-670).
Chen, M.-W., Kuo, R., Chang, M., & Yang, K.-Y. (2003). Internet virtual
classroom: An implementation of the instructional model of the PBIALS
based on the PBL theory. In Proceedings of the IEEE International
Conference on Advanced Learning Technologies 2003 (p. 441).
Delisle, R. (1997). How to use problem-based learning in the classroom.
Alexandria, VA: Association for Supervision and Curriculum Development.

Dewey, J. (1938). Experience and education. New York: Collier and Kappa
Delta Pi.
Duch, B. J. (2001). Models for problem-based instruction in undergraduate
courses. In B. J. Duch, S. E. Groh, & D. E. Allen (Eds.), The power of
problem-based learning. Sterling, VA: Stylus.
Gallagher, S. A., Sher, B. T., Stepien, W. J., & Workman, D. (1995). Implement-
ing problem-based learning in science classrooms. School Science and
Mathematics, 95(3), 136-146.
Hmelo, C. E., & Ferrari, M. (1997). The problem-based learning tutorial:
Cultivating higher order thinking skills. Journal of the Education of the
Gifted, 20(4), 401-422.
Hsu, C.-C., Chen, M.-W., Chang, M., & Yang, K.-Y. (2003). XOOPS: A rapid
tool for developing problem based learning environment for teachers. In
Proceedings of the International Conference on Computers in Educa-
tion (pp. 89-92).
Johnson, D. W., Johnson, R. T., & Smith, K. A. (1991). Cooperative learning:
Increasing college faculty instructional productivity (ASHE-ERIC Higher
Education Rep. 4). Washington, DC: George Washington University.
Jones, B. F., Palincsar, A. S., Ogle, D. S., & Carr, E. G. (Eds.). (1987). Strategic
teaching and learning: Cognitive instruction in the content areas.
Elmhurst, IL: North Central Regional Laboratory and the Association for
Supervision and Curriculum Development.
Lin, Y. Y., Chang, J. C., Cheng, S. Y., & Heh, J. S. (1999). IVC: Internet virtual
classroom. In Proceedings of the 3rd Global Chinese Conference on
Computers in Education ’99.
Novak, J. D. (1981). Applying learning psychology and philosophy of science to
biology teaching. American Biology Teacher, 73, 12-20.
Novak, J. D., & Gowin, D. N. (1984). Learning how to learn. Cambridge, UK:
Cambridge University Press.
Sage, S. M. (2000). A natural fit: Problem-based learning and technology
standards. Learning & Leading with Technology, 28(1), 6-12.
Savery, J. R., & Duffy, T. M. (1995). Problem based learning: An instructional
model and its constructivist framework. Educational Technology, 35(5),
31-38.
Simon, H. A. (1973). The structure of ill-structured problems. Artificial
Intelligence, 4, 181-201.
What is PBL? (2004). Retrieved December 22, 2004, from McMaster Univer-
sity, School of Medicine Web site: http://www.fhs.mcmaster.ca/bhsc/
CellBiology/what_is_pbl.htm

Technology, Research and Development, 41(1), 43-58.

A Simulator for High-Performance Processors 267
ChapterXIV
ASimulatorfor
High-Performance
Processors
John Morris, University of Auckland, New Zealand
Abstract
This chapter describes a Web-based modular, extensible processor simulator
designed as an aid to teaching computer architecture. It is written entirely
in Java, which allows it to be easily embedded in other Web-based course
materials and to run anywhere. Users configure a collection of Java
classes which model individual processor modules. Java’s dynamic class
loading capability means that students in advanced classes are able to
incorporate new modules by simply writing new classes and adding them to
a configuration file which specifies the new modules' connections to other
modules. The modular structure means that it can be used for both
introductory computer organization and more advanced processor
architecture courses. For example, it can be used to demonstrate how (a)
the data path of a modern processor is structured, (b) pipelining keeps
multiple instructions in flight at any time, (c) hazards occur, and (d)
resource conflicts are resolved. Processing modules follow a simple design

268 Morris
pattern which correctly simulates the behavior of a complex synchronous
processor. The design is simple, yet powerful enough to model complex data
paths with extensive feedback capabilities. To manage complexity, the
system being simulated may be specified as a hierarchy of models, each of
which can be viewed in a separate window on demand. This provides a
customizable level of detail to students studying processor operation.
Learning Objectives
• Explain how a processor simulator can be used in the classroom as an aid
to enhance teaching and learning computer architecture.
• Discuss the usefulness of a processor simulator in teaching and learning
contexts.
• Define the following key terms: cache, data paths, dynamic loading,
pipeline, and toolkit.
• Consider further enhancements to the processor simulator described in the
chapter.
Introduction
Decreasing feature sizes leads to more transistors per unit area of a processor
die and a continued growth in a designer’s transistor budget: Tens of millions of
transistors are now available to designers of high-performance processors. This
motivates a continual search for additional performance-enhancing devices:
even if the benefit is relatively small, it has become economically feasible to
incorporate them into new designs. Thus we now commonly see deep pipeline,
superscalar designs with large numbers of modules, each providing perhaps only
a small performance improvement. Tens of instructions may be “in flight” (in
various stages of processing) in each clock cycle, and large amounts of data may
be cached in various modules; as well as conventional caches, many modules
hold data in registers (e.g., most pipeline modules) and tables (e.g., branch
history buffers). The high degree of parallelism and complex data storage is only
effectively demonstrated with visual tools. Additionally, with instructions and

data stored in so many different modules at the same time, the potential for
hazards and the complexity of circuitry needed to avoid them have become
significant.
The increasing transistor budget (and thus the scope for incorporating even more
performance-enhancing modules) also means that unless a simulator is easily
extensible, it, like an old processor design, may be consigned to some digital scrap
heap in a very short period.
Thus, to enable students to appreciate and understand how all the modules
interact and contribute to the performance of a modern processor and — perhaps
more importantly — what factors cause bottlenecks and prevent maximum
instruction throughput being attained, a teaching tool should be:
a. Web-based: easily incorporated into existing teaching materials;
b. Portable: students should be able to run the simulator on any system,
anywhere;
c. Modular: new modules should be able to be added by instructors and
students;
d. Configurable: it should be possible to include or exclude modules and
change their sizes or other operational parameters;
e. Hierarchical: modules should be able to be nested within others to control
the level of detail visible to a student at any time;
f. Extensible: there should be no limit to the complexity of designs; and
g. Cycle-based: the existence of hazards is an important concept, and
students should be able to both see them arise and see how they are
resolved.
The ability to configure modules, for example, to set the size of a cache, is vital
for efficient teaching. Whilst processor designers typically want to increase the
size of caches and other tables, for teaching purposes, one generally wants to
reduce the size of such elements (sometimes to trivially small sizes — one or two
elements) so that effects such as cache misses show up quickly rather than after
several hundred instructions have been processed. Students' interest should be
maintained and boredom should not be allowed to set in! It is also necessary to
be able to set other characteristics, such as the cache write policy. Although
simulation speed is a goal of many processor simulation projects (Schnarr &
Larus, 1998), in which billions of instructions (Perez, Mouchard, & Temam,
2004) may need to be simulated to “prove” the efficacy of a new architectural
idea, it is not a primary goal for this project. Here, the aim is that students should
be able to understand how a design technique (e.g., pipelining) or module (e.g.,

270 Morris
system write-back queue) contributes to improved performance rather than to
measure the likely performance enhancement in order to convince a manufac-
turer to incorporate it in the next design.
Existing Simulation and
Visualization Systems
Many architectural simulators with a wide variety of capabilities have been
written. The lowest-level systems — circuit simulators (such as SPICE or those
simulating VHDL or Verilog models) — simulate real circuit delays, limited
voltage levels, and competing drivers but are very slow and are more relevant to
electronic design courses than the higher-level architecture courses targeted
here. Higher-level “cycle accurate” simulators (SimpleScalar is a widely known
recently developed example; Austin, Larson, & Ernst, 2002) are designed to
compare the impact on performance of new architectural features. Thus they
aim to simulate streams of tens of millions of instructions as quickly as possible
and are more concerned with producing operational statistics than visualizing
individual steps. A host of simulators for simple microprocessors have been
written with a single target architecture in mind, for example, Lovegrove’s
(1996) Motorola 6800 simulator; these tools target introductory computer
organization courses which cover assembly language programming and basic
processor operation. Similar tools for specific, but more complex processors are
available, for example, Clarke, Czezowski, and Strazdins's (2001) SPARC tool.
Debuggers (e.g., gdb) and emulators also provide instruction-by-instruction
execution with the ability to examine register and memory content as each
instruction is executed, but their focus is on the output of instructions — not the
individual steps of the micro-architecture that led to that output so that pipelines,
caches, and many other performance-enhancing devices are transparent to
them.
An existing animation system (Morris, 2004b), designed for visualizing the steps
in computer algorithms, had been built as a toolkit of Java classes. The toolkit
approach allows many of the lessons learned in the design of those algorithm
animations, as well as some thoroughly tested classes, to be exploited in designing
a new system. An alternative design strategy uses a higher-level language,
specifically designed for the target application. Although this approach is
common and superficially attractive because the high-level features of the
language allow some types of applications to be written very quickly, it lacks
flexibility. The high-level language inevitably has a large amount of domain
knowledge built into it, reducing its ability to handle new scenarios — even some

in the target application domain. The toolkit approach requires no new knowledge
other than the ability to write in a standard, common language (Java in this case)
and to read specifications for the classes making up the toolkit. Thus, although
the work to create a new animation is slightly larger, the ability to add new
features or capabilities is not constrained — an animator can do anything that
Java will allow. Use of Java also makes meeting requirements (a) Web-based,
(c) modular, and (d) configurable (on the fly using Java’s dynamic class loading
capability) simple. A similar approach was adopted by Miller, Seila, and Xiang
(2003) to build their JSIM Web-based simulator.
Animation Framework
The basic animation framework builds on a core of animation support classes
designed for animating algorithms — for example, quick sort and Kruskal’s —
commonly taught in computer science courses (Morris, 2004a, 2004b). It
provides
• menus for selecting data sets,
• controls for animation rates,
• start, stop, step, and skip buttons,
• a standard layout with drawing panel, commentary box, and so forth
and methods associated with all these objects, for example, a method to “mark”
a point in an animation to which it will proceed once the step button is pressed,
methods to open files selected as input data sets (these files follow some simple
format rules, in particular, the first line contains the text used for the menu item),
and so forth. In addition, the animation toolkit provides classes for drawing
• boxes, arrows, arcs, and so forth,
• labels associated with objects, and
• simple graphs, bar displays, histograms, and so forth.
A Trajectory class defines a path along which an object will move during the
animation and handles the detail of calculating the next position, erasing the
object at its old position and redrawing it at the new one, and so forth. Initially,
the toolkit grew rapidly as new animations provided new requirements, but it has

272 Morris
now reached the point where new animations can be created with few demands
for new capabilities being encountered.
This toolkit has proved to be an efficient way of generating algorithm animations;
students in data structures and algorithms classes are able to create new ones
as class exercises. Several new ones were added to the basic collection by a
class of about 20 students at ChungAng University (Seoul) as the final assign-
ment of a one-semester course; their efforts may be seen on the University of
Auckland site (Morris, 2004a). It has also been used to develop animated course
materials to support courses in control structures and basic electronics at the
University of Western Australia. A minor aim of the current project was to
determine whether the basic framework (the classes for creating the main
drawing panel and associated controls) was adequate for this application. The
animation framework, including a running simulation, may be seen in Figure 1.
Processor Animation
One of the challenges of adapting the animation toolkit to handle processor
simulation was the large number of operations which happen concurrently in a
Figure 1. Simulation in progress

modern processor. Since the visualization was intended to show the correct
logical operation of a processor, accurate simulation of circuit delays (a
requirement of circuit simulators) was not necessary here. Equally, it was not
realistic to ignore circuit delays altogether. The compromise adopted here was
to assume that all circuits operate with some identical, fixed delay which was less
than the clock cycle time. This is equivalent to assuming that the circuits operate
without electrical races. However, logical races, such as those caused by trying
to read a register in the same cycle as it is written, will still be present. From a
teaching point of view, illustrating these hazards is one of the principal aims of
the simulator.
Clocked Pipeline Simulation
This section describes the mechanisms used by the visualization system to
emulate the behavior of a real clocked pipeline. Users write Java classes to
Figure 2. (a) Class hierarchy (b) Processor module showing the major
interface methods
MemoryModule Processor ProcessorUnit
ALUModule BPModule LSModule
ProcBean
ProcModule
OpFetchModule
IFModule IFModule
RegisterModule CacheModule
(a)
ProcModule
implements ProcBean
initialize()
processClockEvent()
boolean isBusy()
draw(Graphics g)
expandWhenClicked()
getInputEnabled(int port_index)
(b)

274 Morris
model the behavior of individual modules in the system. These modules provide
(logical) input andoutput ports for signals, clock, andbusysignals. Formally, Java
classes modeling processor modules are specializations of (inherit from) the
ProcModule abstract class, which implements the ProcBean interface. This
formal structure ensures that new modules, which are dynamically loaded as a
configuration file is read, all function correctly. The ProcBean interface
contains specifications for vital methods needed by all modules:
• initialize: this method is passed a string found in the configuration file
which may specify parameter values (e.g., memory size), a file to be read
(e.g., containing initial contents of a memory), and so forth;
• getBoundingBox: returns the bounding box for drawing this module;
• addInputSource: adds a connection to an input (used in the configuration
process);
Figure 3. Processor pipeline showing computation blocks and registers.
Note that the processClockEvent method invocation latches computed
values and corresponds to the global clock; invoking processInput
causes the computation blocks to compute new values. The lower section
shows the relation (in time) between method invocations and the clock
signal.

• addOutputListener: adds a “listener” (module receiving input from
this module) to an output port;
• draw: invoked to draw this module;
• expand: invoked when a user clicks on a module to expand it;
• outputChange: invoked when a source for this module has changed its
output;
• disableOutput: disables an output (tri-states a driver);
• processClockEvent: invoked when a clock edge is received; and
• processInput: invoked mid-cycle (cf. Figure3) to calculate new outputs.
Some additional methods required for drawing, getting, and setting attributes are
also specified.
The abstract class ProcModule provides all the common attributes of modules
(label, position, bounding box, latency, lists of inputs and outputs, internal
modules, etc.) and default implementations of some methods in the ProcBean
interface. This provides some core capabilities and saves considerable amounts
of repetitive programming; writers of new modules can use the default imple-
mentations if they are appropriate (or to make a “fast start” to a functional, if not
elegant, system). The new module writer only overrides (writes special versions
of) a method if the capabilities of the new module require it. Some additional
methods in ProcModule are defined as abstract methods which must be
implemented by actual module implementations. Figure 2(a) shows the class
hierarchy. Note that additional hierarchies of modules have been specified, for
example, the MemoryModule and ProcessorUnit “trees.” This facilitates the
writing of new modules which share capabilities with existing modules; the new
module is defined as a specialization of an existing one, and the module writer
only needs to rewrite methods which have changed behavior.
Clocked pipelines operate in two basic phases: latching of data from input or
previous stageandcomputing. To simulate this behavior, each functional module
is sent two signals:
• read: read data from the preceding stage and
• compute: compute a new result from the inputs just read.
These two signals, the modules to which they are applied, and their relationship
to the global clock are shown in Figure 3. Signal read emulates the latching of
data in the output registers of the preceding module by a global clock edge. The
data which is read in this phase has been computed by the preceding module in

276 Morris
the previous compute phase. The controlling thread causes all modules to enter
this phase by invoking the ProcessClockEvent method of each module. When
a modulecontainsa hierarchyof internal modules, thentheProcessClockEvent
methods of the “container” modules invoke the ProcessClockEvent method
of all their components. As with an actual clock signal, invoking
ProcessClockEvent sends no information (other than the event itself) to each
invoked module; each module reads its inputs through a list of references to
modules to which it is connected. A module will also check a busy signal in each
module to determine whether the sending module is asserting valid data — or
whether it is still computing values that require multiple cycles. Bussed configu-
rations are permitted, so multiple modules may be acting as sources for any port:
at most, one should respond with valid data.
The “compute” signal is sent by invoking the processInput() method in each
module. It takes the values of the inputs read in the read phase and computes new
outputs. The new outputs are stored internally in logical output “registers” of
each module, ready to be read in the subsequent read phase.
This two-phase protocol implemented with these simple calls provides cycle-
accurate simulation (as provided by several full architectural simulators; Austin
et al., 2002 Cain, Lepak, Schwartz, & Lipasti, 2002) in the absence of logic race
conditions, that is, assuming that a processor clock has been set correctly.
Without cycle-accurate simulation, many hazards cannot be exposed: instruc-
tion-by-instruction simulation as provided by, for example, software debuggers
running in single step modes, which complete each instruction as an atomic
operation and are not subject to the hazards that pipelines commonly introduce.
Critically, without understanding hazards, students do not appreciate a key
sourceof pipelinestalls andtheir effect on total instruction throughput. They also
miss an understanding of theworkthat anoptimizingcompiler performs toreduce
pipeline stalls or the purpose of register renaming.
A processor is “built” for visualizationby creatinga text configurationfilewhich
lists the individual modules and specifies their interconnections. An example is
shown in Figure 4. Each line represents a module, starting with a label (allowing
multiple instances of modules such as caches) and followed by the name of the
class (which must be a specialization of ProcModule). The Java VM is used to
load the code for the individual modules using this class name. The remainder of
the line specifies connections to other modules and the location of the "port" for
each connection on the icon for the module. Note that multiple connections to
individual ports (busses) are allowed. Modules may load additional data from a
text file using the argument in parentheses following the module (class) name.
This string, usually a file name, is passed to the constructor and permits, for
example, a common class to be used for several memory modules — all of which
can be loaded with different initial data through this argument. However, this

argument is simply a Java string, so that it can be used to set one or more arbitrary
parameters for the loaded module: memory sizes, operation modes, and so forth.
Once a configuration file is loaded, the modules and their connections are
displayed. This visualization enables rapid verification that modules have been
connected in the desired manner. The system also checks for errors in the
configuration file, such as attempting to connect to nonexistent ports.
Since the configuration file is a simple text file, it can be easily edited by students
or instructors to:
• change module parameters, for example, to reduce the size of a cache so
that miss rates increase and the processing of misses can be studied; and
• add additional modules, for example, caches, branch predictors, buffers in
system interface units, and so forth.
This allows students to experiment quickly with different configurations to
compare the effect of adding (or removing) modules or changing their mode of
Figure 4. Configuration file for a system with memory, IF unit, op fetch unit,
ALU, load/store processor, branch processor, and write-back unit. Note
that the PSW is configured as a separate module to simplify access by other
modules; not all interactions are shown.
CONFIGURATION
Configuration File
m1 MemoryModule(mm.dat) (60,0) (200,10,10) (if1,L/S,WB(100,65)) (if1,L/S(130,65))
if1 IFModule (5,90) (1,200,5) [(m1,(75,90))(BP,(275,155))] [(m1,(55,90))(op1,(50,155))]
op1 OpFetchModule (10,180) (200,0,150) [(if1,(55,180))(rf1,(95,245))(rf1,(180,245))]
[(rf1,(75,245))(rf1,(160,245))(ALU,(295,245))(L/S,(305,245))(BP,(315,24
5))]
ALU ALUModule (20,280) (0,200,200) [(op1,(120,280))]
[(WB,(105,365))(PSW,(115,365))]
L/S LSModule (240,280) (200,0,200) [(op1,(360,280))(rf1,(315,365))(m1,(380,280))]
[(rf1,(335,365))(m1,(340,280))(WB,(345,280))]
BP BPModule (650,280) (200,200,0) [(op1,(670,280))(PSW,(680,280))]
[(if1,(690,280))(PSW,(700,280))(WB,(710,280))]
rf1 RegisterModule(reg.dat) (400,135) (0,200,10)
[(op1,(500,230))(op1,(590,230))(L/S,(680,230))(WB,(770,230))]
[(op1,(520,230))(op1,(610,230))(L/S,(745,230))]
WB WBModule (350,0) (0,0,200) [(ALU,(360,65))(L/S,(380,65))(BP,(400,65))]
[(rf1,(440,65))(m1,(420,65))]
PSW PSWModule(psw.dat) (610,0) (0,100,200) [(ALU,(620,95))(BP,(660,95))]
[(BP,(640,95))]

278 Morris
operation. Thus, by preparing configurable models (generally a simple matter of
good coding practice!), instructors can create a set of experiments designed to
illustrate the concepts being expounded in formal classes.
Note that the “program” which the simulator runs is simply encoded as the
contents of a memory module and stored in the initialization file for the primary
memory. It is only necessary to ensure that a suitable instruction is placed at the
standard processor bootstrap location.
Extensibility
The key to extensibility of this visualization system is the specification of
individual modules conforming to a common specification — they must be
specializations of the abstract ProcModule class. This allows new modules to
be dynamically linked into the existing animation framework as the configuration
file is read and classes representing modules in it are loaded by name. Students
or instructors wishing to add new modules simply write a new specialization of
the ProcModule class, compile it, and add an appropriate entry to a configuration
file.
Working entirely from scratch, an undergraduate BE(SE) student was able to
add a working cache module in an 8-week vacation work experience period. This
exercise was undertaken while some experimentation with the core modules was
still proceeding; using the experience gained, such an exercise would now
require only half the time.
Visualizing Operation
As the simulator was built, it soon became obvious that all the detail that was
needed to understand operation of a complex modern processor, for example,
register and memory contents, instructions (as originally stored in memory and
in decoded forms), and so forth would not fit in the available screen space.
Accordingly, an additional operation was added — the ability to click on any
module and pop up tables of internal detail, for example, register or memory
contents, in a separate frame which can be moved to any part of the screen,
resized, hidden, or closed as the student wishes. These frames are updated on
every cycle as the processor “executes” instructions. By using separate frames,
students are able to bring information that is currently relevant to the foreground,
allowing the considerable mass of irrelevant detail to be removed from sight, thus
conserving scarce screen real-estate for critical details.

Modules may also be designed as hierarchies of modules, so that structures such
as memory management units which have internal “caches” (the translation
look-aside buffers) may be examined in some detail if the student desires. These
complex modules may be specified in their own configuration files; the configu-
ration file entry for the enclosing module may specify the name of this
configuration file as the constructor argument (cf. Configuration File subsec-
tion). As with memory modules, clicking on an expandable module causes a new
frame showing the internal structure to appear. There is no limit to the number
of levels of internal substructure which may be specified. Each frame acts as an
independent display with inputs derived from modules in a parent frame and
outputs similarly directed to the parent frame.
Current Capabilities
To date, this system is able to “execute” a subset of the MIPS instruction set,
including most of the integer ALU instructions. Key branch instructions are also
handled by a separate branch processor unit, mimicking the organization of
several high-performance processors. Memory access is similarly handled
through a separate load/store unit. The current implementation has four pipeline
stages (instruction fetch, decode and operand fetch, ALU, and write-back) and
so is able to illustrate basic pipeline operations. Memory modules with various
latencies may be configured to demonstrate pipeline stalls caused by long latency
operations. Modules with more than single-cycle latency (e.g., memory and
ALUs for some operations) display a “countdown” timer, which counts down the
latency (in cycles) and indicates when the module will produce a result. The
effect of branch instructions on throughput is also able to be demonstrated
naturally; the branch processor effectively stalls the pipeline as a new instruction
is fetched from cache or memory.
Programs are fed to the visualization through memory configuration files. These
are also simple, easily edited text files since, for teaching purposes, we want
students to understand at various levels of detail how all the processor's modules
interact as well as the effect that various modules, such as cache, have on overall
performance. This simulator was not designed as an architectural simulator —
well-developed packages such as SimpleScalar (Austin et al., 2002) were
designed for this purpose — but rather as a visualization tool. Furthermore, the
cost of visualization slows down the system too much for it to be able to execute
the billions of instructions now expected of architecture simulators. However,
anticipating limited demandfor architecture simulation, a switchwas provided to
turn off graphical output and dramatically increase the rate of instruction
processing!

280 Morris
Conclusion
This project started with a set of requirements for an effective tool for teaching
the architecture of modern high-performance processors. The original set was
modified slightly as the simulator was developed and evaluated, leading to the list
in the Introduction section. It has met its initial aims of providing an extensible,
cycle-accurate visualization of complex processor operation. The properties of
a modern object-oriented language were used to set up a framework which
ensures that modules written for the simulator properly implement the two
phases — latching and computing — of a typical clocked pipelined processor. It
also handles busses with multiple drivers and receivers correctly. Several
"pattern" modules are now available, so it is anticipated that implementation of
further capabilities should require only moderate programming effort.
The whole system is highly modular, and processors are simply configured in a
transparent way — thevisualizationenables rapid verificationthat modules have
been connected in the desired manner. Thus, simple experiments which demon-
strate, for example, the effect of different cache organizations, are readily
configured by instructors or students.
Success with the first student project to extend the system’s capabilities suggests
that this system will provide not only support to processor architecture classes
but also software engineering projects for many years yet! Advanced computer
architecture students will also be able to add experimental capabilities (in the
form of new modules or modifications to existing ones) and perform simple
experiments to assess their effect on processor performance.
Ongoing Work
Manual layout of the modules on the drawing panel is not a simple problem.
Finding a placement that minimizes interconnection crossover and clutter is the
key problem— anda known hard one(Batista, Eades, Tamassia, & Tollis, 1999).
An intermediate solution is to allow users to lay out interconnection paths (in
place of the direct connections made now), but this will require more effort in
configuration. A simple drawing tool is probably the best answer; automatic
layout is known to be a hard problem!
A full implementation of the ISA for a high-performance processor needs to be
tested. Although the current implementation can demonstrate most pipeline-
related phenomena, techniques to visualize some more subtle design problems,
such as precise exception handling, have not been checked.

Acknowledgment
The majority of the classes in the original toolkit were written by Woi Ang.
Individual students who wrote or extended animations are listed on the Data
Structures and Algorithms Web site (Morris, 2004a). The core modules of this
simulator were mostly written by Ivan Surya. A cache simulation module was
added by Athena Wu.
Summary
This chapter described a Web-based modular and extensible processor simulator
designed as an aid to teaching and leaning computer architecture. It is written in
Java, which allows it to be easily embedded in other Web-based course materials
and to run anywhere. Users configure a collection of Java classes which model
individual processor modules. Java’s dynamic class loadingcapability means that
students in advanced classes are able to incorporate new modules by simply
writing new classes and adding them to a configuration file which specifies the
new modules’ connections to other modules. The modular structure means that
it can be used for both introductory computer organization and more advanced
processor architecture courses. For example, it can be used to demonstrate how
(a) the data path of a modern processor is structured, (b) pipelining keeps
multiple instructions in flight at any time, (c) hazards occur, and (d) resource
conflicts are resolved.
Processing modules follow a simple design pattern which correctly simulates the
behavior of a complex synchronous processor. Thedesign is simple, yet powerful
enough to model complex data paths with extensive feedback capabilities. To
manage complexity, the system being simulated may be specified as a hierarchy
of models, each of which can be viewed in a separate window on demand. This
provides a customizable level of detail to students studying processor operation.
Cache: A small fast memory which stores recently used values so that they can
be accessed faster than the bulk memory behind it.
Cycle-accurate: A simulator which models the operation of a processor on a
cycle-by-cycle basis so that the state of the processor at the end of each
cycle is correct.

282 Morris
Data path: The main path along which data flows in a processor; usually extends
from an instruction fetch unit to a result write-back one.
Dynamic loading: The ability of a system to load additional software compo-
nents (e.g., Java classes) as it executes.
Hazard: A situation in which a processor with multiple functional units could
compute an incorrect value by using the wrong data if appropriate precau-
tions are not taken.
Pipeline: An arrangement of functional models in a high-performance proces-
sor in which part of the computation is carried out in each stage of the
pipeline. Data “flows” from one end of the “pipe” to the other.
Stall: A pipeline stalls when data is prevented from flowing from one stage to
the other to avoid a hazard or while waiting for a long latency operation such
as a memory fetch.
Synchronous: All operations are synchronized to a global clock.
Toolkit: A library of classes which model objects commonly required in
animations; classes designed for reuse.
Review Questions
1. List and describe three desirable features of a processor simulator.
2. Discuss the usefulness of a processor simulator in teaching and learning
contexts.
3. Give three examples of circuit simulators.
4. Describe the principle of operation of clocked pipeline.
5. Explain how you would configure a collection of Java classes in modeling
individual processor modules.
6. List and describe possible enhancements to the proposed processor simu-
lator.
References
Austin, T., Larson, E., & Ernst, D. (2002). SimpleScalar: An infrastructure for
computer system modeling. Computer, 35(2), 59-67.

Batista, G. D., Eades, P., Tamassia, T., & Tollis, I. G. (1999). Graph drawing:
Algorithms for the visualization of graphs. Upper Saddle River, NJ:
Prentice Hall.
Cain, H. W., Lepak, K. M., Schwartz, B. A., & Lipasti, M. H. (2002). Precise
and accurate processor simulation. In 5th Workshop on Computer
Architecture Evaluation Using Commercial Workloads.
Clarke, B., Czezowski, A., & Strazdins, P. (2001). Implementation aspects of a
SPARC V9 complete machine simulator. Conferences in Research in
Information Technology, 9, 23-32.
Lovegrove, W. P. (1996). A microprocessor trainer simulator. In FIE’96, IEEE
(pp. 506-509).
Miller, J. A., Seila, A. F., & Xiang, X. (2003). The JSIM Web-based simulation
environment. Future Generation Computer Systems, 17, 119-133.
Morris, J. (2004a). Algorithm animations. Retrieved from www.cs.auckland
.ac.nz/software/AlgAnim/alg_anim.html
Morris, J. (2004b). A toolkit for algorithm animation. In Proceedings of
AEESEAP Mid-Term Conference, Auckland, New Zealand (pp. 150-
155).
Perez, D. G., Mouchard, G., & Temam, O. (2004). Microlib: A case for the
quantitative comparison of micro-architecture mechanisms. In MICRO-
37: Proceedings of the 37th International Symposium on
Microarchitecture (pp. 43-54). IEEE Computer Society.
Schnarr, E., & Larus, J. R. (1998). Fast out-of-order processor simulation using
memoization. In Proceedings of the 8th International Conference on
Architectural Support for Programming Languages and Operating
Systems (pp. 283-294). ACM Press.

284 Murray & Lasky
ChapterXV
ARemotelyAccessible
EmbeddedSystems
Laboratory
Steve Murray, The University of Technology Sydney, Australia
Vladimir Lasky, The University of Technology Sydney, Australia
Abstract
To teach modern embedded systems including operating systems in a
meaningful way, a moderately sophisticated processor is required to
demonstrate many key concepts, such as multitasking, multithreading, a
structured and abstracted hardware management layer, communications
utilising various protocols over network interfaces, and memory resident
file systems. Unfortunately, high-end 32-bit embedded systems processors
capable of supporting these facilities are expensive compared to
conventional 8-bit and 16-bit targets, and it is not feasible to acquire a
large number of them to house in a laboratory in an effort to enable
practical exercises for over 100 students. This chapter describes the
development and use of a remotely accessible embedded systems laboratory
that uses a small number of 32-bit development systems and makes them
available to students over the Internet.

A Remotely Accessible Embedded Systems Laboratory 285
Learning Objectives
• Discuss the usefulness of a remotely accessible embedded systems
laboratory in teaching and learning contexts.
• Define the following key terms: embedded computer system, multitasking,
and multithreading.
• Suggest further enhancements to practical activities proposed in the
chapter.
Introduction
In 2001, the Information and Communications Group in the Faculty of Engineer-
ing at the University of Technology, Sydney, decided — after surveying
industrial trends — to focus upon embedded computer systems as a basis for
case studies and application areas in which to demonstrate theoretical concepts.
In particular the undergraduate subject 48450 Real-Time Operating Systems
strove to differentiate itself from computer science and IT-styled subjects in that
area by using embedded computer system hardware platforms. To demonstrate
many of the concepts that are essential to a modern operating system, for
example, multitasking, multithreading, a structured and abstracted hardware
management layer, communications utilising various protocols over network
interfaces, and memory resident file systems, a moderately sophisticated proces-
sor is required. Unfortunately, high-end 32-bit embedded systems processors
capable of supporting these facilities are expensive when compared to conven-
tional 8-bit and 16-bit targets, and it is not feasible to acquire a large number of
them to house in a laboratory in an effort to enable practical exercises for over
100 students. Instead, a remotely accessible embedded systems laboratory has
been constructed which uses a small number of 32-bit development systems and
makes them available to students over the Internet. Students can use them in the
conventional way following a development path that commences with cross-
development and concludes with testing on the 32-bit target and viewing the
results.

286 Murray & Lasky
Embedded computer systems in use worldwide constitute a very large market in
comparison to that of personal computers and workstations (In-Stat/MDR,
2002). Computer systems engineering and software engineering graduates with
their knowledge of microprocessor and microcontroller hardware are arguably
the best equipped to serve the needs of this high-volume market. Developing
software for an embedded computer system involves certain idiosyncratic
difficulties, however — in particular, cross-development. When constructing a
laboratory designed to facilitate cross-development, it is conventional practice to
have a large number of pairs of directly connected development systems and
embedded targets. Individual students write programs on a development system,
then transfer the executable program via a communication channel of some sort
(serial data transfer via a cable or infrared, or perhaps a packet-based protocol
using an Ethernet interface, or by sharing memory where the target card is
installed on the host’s bus) to the target adjoining, and then assess the success
or failure of the developed code by observing the behaviour of the target as the
program runs.
This development cycle is particular and intrinsic to the construction of embed-
ded systems, and it would be remiss of any educator to dilute the experience by
attempting to reduce support costs and complexity via simulation. A collection
of real cross-development systems that can be shared from remote locations is
one way of efficiently making these experiences available to students.
A representative collection of examples of existing remote cross-development
systems is described next.
The Remote Experiment Lab (RExLab)
The Remote Experiment Lab (RExLab) is an embedded systems laboratory
located at the Federal University of Santa Catarina, Brazil (Marques, Wisintainer,
& Alves, 1998). The laboratory allows students to perform experiments remotely
with devices based on the popular 8051 series of microcontrollers. The students
are able to write programs in 8051 assembly language, upload assembled code
to the laboratory to be executed remotely, and view the contents of registers and
internal memory. The system consists of several components:
• A development board containing an 8051 microcontroller and auxiliary
components that allow communication between the microcontroller and the
PC;

• Client software (RExLab-Client), which loads the user’s compiled binary
and transfers it to the server to be executed; and
• Server software (RExLab-Server), which receives the information from
the client, forwards it to the 8051, and sends the requested result back to
the client.
Both the user client and the server software are custom applications written in
Borland Delphi but make use of some libraries that support the user interface and
standard TCP/IP communications. Marques et al. (1998) do not explicitly state
how many such development boards are available for remote use by students,
and the system does not appear to support time limits on access.
The Virtual Automation Laboratory
The Virtual Automation Laboratory at the University of Tübingen (Bühler,
Küchlin, Gruhler, & Nusser, 2000) is a Web-based interactive learning environ-
ment for both computer science and automation engineering students. It was
launched as an initiative from the Baden-Württemberg state government that
encouraged the development of virtual universities. The automation engineering
content is mainly concerned with learning about devices connected by controller
area network (CAN) bus networks, whilst the computer science content is
concerned with both programming language and operating systems concepts,
such as OOP in Java, network communication, client/server systems, and
middleware. Whilst one of the experiments provided in this project is a simulation,
there are two others that involve work being performed using a remote
laboratory. This remote laboratory infrastructure consists of a server which acts
as a bridge between the Internet and some CAN bus experimental apparatus.
There are currently two types of CAN bus-connected hardware installed: a
video-monitored LED display board in which individual characters can be
switched on and off and a static industrial robot arm which has a number of
monitoring cameras at various positions. The user interface is provided by a Java
applet that is downloaded from the main Web site. No proprietary software is
required on the user side, and no browser plug-ins are needed to access the
devices via the Internet. Details of an arbitration capability are not clearly
specified, but users are given a limited time in which equipment can be used,
implying that a queuing system of some kind is used.

288 Murray & Lasky
Distance Learning Applied to Control Engineering
Laboratories: Oregon State University
Aktan, Bohus, Crowl, and Shor (1996) describe a remote laboratory used for
control engineering experiments at Oregon State University in the United States.
This paper is highly influential; it has been cited by most of the other papers on
remote laboratories and was responsible for inspiring aspects of the system
developed at the UTS. The first part of their paper discusses the economics,
logistics, and presentation criteria that should be considered when selecting an
experiment to be adapted for remote use. The logistic criteria are significant, for
example, having the ability for a remote laboratory to run without human
intervention and having a stable start state or reset position from which a new
experiment can be commenced. The second section of the paper describes an
implemented remote laboratory used for control engineering experiments. The
experiment involves remotely controlling and monitoring a robot arm. Students
using a client application called Second Best to Being There (SBBT) are able to
develop, compile, debug, and run controllers in real time. In addition, the software
provides live audio and video monitoring of the robot arm and collaboration with
fellow students via text messaging and an online whiteboard. The work that was
performed was quite remarkable considering the year in which it was developed
(1996). This was before Web cameras (Webcams) were accessible consumer
items, standards for audiovisual streaming over the Internet were in their infancy,
and available levels of bandwidth were lower. The laboratory avoided the need
for users to download a special client by using X Windows Java applets that were
just being introduced at the time. The SBBT client could execute on any UNIX
server, and students could view the console output on any computer with an X
Windows server. The drawback of this technology was the bandwidth require-
ment — productive work had to be done from somewhere on the local network.
The implementation places a great deal of emphasis on collaboration and
communication between fellow students — the arbitration system does not
impose time limits on sessions or provide automatic scheduling; instead, students
must communicate with each other online and negotiate their turn to use the
equipment. It was intended “that students may linger and talk about their findings,
help each other, and form collegial relationships.” As the laboratory has moving
parts (due to the presence of the robot), additional interlocks had to be included
to guarantee safety of passersby.

A Distance Learning Laboratory for Engineering
Education
Knight and DeWeerth (1997) describe a remote laboratory at the Georgia
Institute of Technology used for teaching graduate electronic circuit classes.
Their system is an interactive remote testing system that operates over the
Internet. The user interface consists of a Java applet designed to recreate the
“look and feel” of a laboratory bench fitted with equipment. The interactive
remote testing system displays the front-panel controls of each instrument in its
own optionally visible window, allowing the user to see only the instruments.
Measurement data from the laboratory equipment is fed back to the user in real
time. The infrastructure consists of a device under test (DUT), which is
connected to a set of general purpose interface bus (GPIB)-controlled test
instruments via a switching matrix. A remote user can extract data from the
DUT by configuring the matrix and stimulus instruments and then querying
response instruments. The laboratory implements robust arbitration functionality
— when the user logs into the laboratory via the testing applet, all the instruments
and the user interface controls are set to a known initial state. Each command
or command group sent to a specific instrument is followed by an acknowledge
request. An instrument is only considered synchronised when all of its pending
requests have been answered by the laboratory server. A scheduling system is
also implemented. On the Web page, users can reserve blocks of time in the
laboratory in advance. If resources have not been previously reserved, the
laboratory is available on a first-come, first-served basis. The system maintains
open network connections to all users waiting to use the laboratory equipment
and updates each user with the queue status continuously. It must be noted that
as the laboratory only has a single testing station, the implementation of
arbitration is relatively straightforward, and the system is of smaller scale than
others evaluated here, being designed to support less than 20 clients.
Summary of Surveyed Examples
Some organisations had comparatively large budgets with which to investigate
and develop remotely accessible laboratories. Regrettably, this is not universal.
Some laboratories had grand aims and represented a significant commitment by
the participants, whereby others were more modest in their capabilities and
intentions. Some laboratories did not have a structure that encouraged scalability
(either vertical or horizontal). This naturally tends to limit their ability to meet
fluctuating demand.

290 Murray & Lasky
One other important quality of any system which might be used to support
remotely accessible laboratory apparatus is that it should ensure it is completely
indifferent to any analysis, design, and testing methodologies which might be
used by the students. It should not influence in any way their approach to problem
solving and should be completely transparent in this respect. By placing emphasis
on a technique whereby the remotely accessible laboratory is viewed as
infrastructure which simply transfers the students’ senses from their remote
location to the laboratory, it is most unlikely that any unintentional and harmful
side effects of this nature would be introduced.
The Remotely Accessible Embedded Systems Laboratory has been developed
for use by students of the undergraduate Real-Time Operating Systems course
at the UTS. The laboratory is comprised of a collection of 12 senTec CO-
BRA5272 development boards (senTec Elektronik GmbH, Ilmenau, Germany)
based on a Motorola Coldfire architecture, a popular 32-bit embedded systems
platform used in industry.
Experiments performed by the students to date have covered a number of
operating systems concepts, including memory management on embedded
architectures (which must be managed without hardware support), POSIX
programming, embedded client-server systems, and kernel device driver devel-
opment. Students are able to use the laboratory from any Internet-connected
Figure 1. SenTec COBRA5272 target processor development board

location. In the spring 2003 semester, the laboratory was shared by over 150
students. The ultimate aim of the laboratory is to be “the next best thing to being
there.”
User Facilities
• User Interface: The system is accessed by starting a command-line
terminal client on any PC and logging in to the master server, which is
running a distribution of the Linux operating system. Users have their own
personal accounts with private home directories to store their work.
Installed on the system are various engineering application programs and
the widely used GNU development suite. It is intended to extend the
students’ skills base by promoting UNIX literacy. In this respect, the log-
in to a shell account is completely indistinguishable from any other UNIX
environment, which assists in making students feel comfortable with the
system.
• Device access and real-time debugging: Students are able to remotely
compile, upload, and debug programs interactively on the development
boards.
• Fair sharing of boards: The arbitration system guarantees each student
their fair share of time to use the system. When the system is busy, students
are placed in a queue to wait for an available board. Time limits are tailored
Figure 2. Example of remote user’s view

292 Murray & Lasky
by the academic staff to suit anticipated development times and are
imposed to prevent other students from hogging resources.
• Video monitoring: Video monitoring of peripherals connected to the
target processors permits users to perform experiments on connected
peripherals and see the results in real time over the World Wide Web. The
user can open a Web browser on their PC and connect to the master server,
which — after log-in — will permit them to specify which video format they
would prefer. Video is available in several standard formats to ensure wide
availability:
Ø Multipart JPEG (400 kbps) provides lowest latency for those accessing
the Internet from university laboratories or broadband connections
outside the university. A Java client is available that can execute on
any computer with a Java-enabled browser.
Ø Windows Media Player MPEG4 encoded video (40 kbps) provides
support for those who are connecting to the Internet via dial-up with
56 kbps modems.
Ø Still JPEG Snapshots are also available when motion video is not
needed or when bandwidth must be conserved.
Administrator Facilities
• Fair sharing of boards: Staff may set time limits on system usage that can
be tailored to suit system load and the proximity of submission deadlines for
practical work. This ensures that all students are given an equal opportunity
to share use of the system.
• Account administration: The system can use enrolment information from
UTSOnline (the university portal to student access to all teaching- and
learning-related resources), which helps to automate enrolments at the
start of the academic semester, avoiding painstaking manual account
creation. Account names and passwords are automatically assigned and e-
mailed to the students’ registered e-mail addresses.
• Support: Although this system is able to function completely independently
from other computer-based learning environments and tools, it provides a
highly effective collaborative learning environment when combined with
UTSOnline discussion boards and virtual classrooms. Short turnaround
times are possible for student queries as staff can assist by logging in to the
development system from any location and providing advice.
• Dynamic removal and addition of devices: Individual development
boards and board servers can be removed or installed at any time when the
system is live to allow repair or replacement or expansion.

Architecture
The hierarchy consists of a number of systems with different roles:
• Master server: The master server is the central point of access to the
system. Users log in to the master server using Secure Shell (SSH). The
master server stores user home directories and all tools and documentation
required for development and laboratory tasks. The arbitration system,
which is the primary system-management program, is based in this server
and is responsible for allocating users to development boards, which are
connected to the board servers. The master server runs the PostgreSQL
database server to maintain tables containing user attributes (not all users
are of the same class) and tables of data relating to the laboratory hardware
and software configuration.
• Board server: The board servers are responsible for providing access to
the individual development boards. Each board server can control up to four
target processor boards; this limitation is introduced by the number of input/
output (I/O) ports that the board servers offer. When a user commences
a session, the arbitration program allocates the user to one of the board
servers. Programs that require direct communication with the target
processor boards — for example, the terminal emulator and the remote
Figure 3. Remotely accessible embedded systems laboratory topology
coldfire
cf1
coldview/cv1
I/O I/O I/O I/O
cf2
cv2
I/O I/O I/O I/O
cf3
cv3
I/O I/O I/O I/O
Master Server
Board Server
Monitoring Server
Standard
Module

294 Murray & Lasky
debugger — are then executed locally. The arbitration system makes this
allocation process transparent to the users.
• Monitoring server: The monitoring servers provide live real-time video
monitoring of devices over the World Wide Web. Each server is responsible
for monitoring four development boards; this again is influenced by I/O port
availability and to an extent by processing load on the monitoring server
also. The first monitoring server coldview has a secondary role as the
central Web server for the laboratory. From a Web page, visitors can view
the arbitrator queue and observe the peripheral boards on any of the boards
in the collection.
• Standard module: The combination of a board server, monitoring server,
four target processor development boards, and four video cameras is called
a standard module; hence, the laboratory currently has three standard
modules. When or if it becomes necessary to add capacity, additional
standard modules are added to the collection. Limits to this scalability have
not been determined.
It is useful to examine the virtues of remotely accessible laboratories as a class
of experimentation and learning infrastructure initially and then consider positive
attributes of our chosen design.
The Case for Remote Laboratories
• Convenience: The laboratory can be accessed from any location with
Internet access, such as homes, cafes, overseas locations, and other
general-purpose university laboratories. The only equipment required is a
modern network-enabled personal computer (PC) with a graphical Web
browser and an SSH client; the freely available PuTTY (http://
www.chiark.greenend.org.uk/~sgtatham/putty/) SSH client is suitable for
Windows and is small enough to be carried on floppy disk.
• Reduced demand upon real estate: Equipment can be installed more
densely as people will not be sitting at desks or standing next to benches.
A lower level of occupational health and safety compliance is needed when
laying out remote laboratories, making construction more flexible.
Underutilised spaces can be used to make a contribution.
• Reduced cost: More efficient utilisation of resources means that less
equipment has to be purchased to service the same number of students
compared to an equivalent physical laboratory.

• High availability: The facility can be accessed whenever desired by both
students and staff members.
• Security: Controlled access to conventional laboratory rooms certainly
makes some progress in securing physical laboratories, but it is not
infallible. A remote laboratory would not require students to be given any
physical access. In addition, equipment can be placed in more secure
locations, such as dedicated machine/server rooms or those with key
access only.
• Immune to physical misuse and vandalism: Students have been known
to vandalise equipment either out of malice for the subject or to force staff
to provide extensions for laboratory exercises and assignments (A. Gibson,
personal communication, September 1, 2003, and others). The architecture
of a remote laboratory would ideally be designed to be immune or highly
resistant to intentional misuse, hence, mitigating this risk.
• Easily upgraded and modernised: Equipment in a remote laboratory can
be upgraded and replaced in stages. It may not even be necessary to shut
down the laboratory whilst an upgrade is in progress. It is also possible to
have a transition period where current and new equipment is accessible to
allow for any technical hurdles or “teething problems” to be overcome; this
situation is somewhat more easily controlled in a remotely accessible
laboratory because equipment cannot be accessed by remote users unless
the staff explicitly brings it online.
• Scalability: A well-implemented remote laboratory could be easily aug-
mented with extra equipment to handle more students. Whilst this is also
possible in a conventional physical laboratory, we contend that the bulk of
this paper suggests with a remotely accessible laboratory it can be achieved
more efficiently.
• Enables distance education: The range of university courses that can be
undertaken by distance education is very limited in scope. Humanities-
based courses traditionally dominate this field as they rely on reading and
written communication (Open Learning Australia, 2003). Remote labora-
tories could make distance education for many science and engineering
courses more practical.
The Case Against Remote Laboratories
There are also some identifiable limitations in the remotely accessible laboratory
concept:
• No face-to-face contact between students and staff: Some students do
not find the isolated environment optimal. To an extent this can be alleviated

296 Murray & Lasky
by suggesting that they access the remote laboratory from one of the
university’s PC laboratories, where the geography is somewhat more like
a conventional physical laboratory.
• Senses are not always transmitted perfectly: The most realistic labo-
ratory experience would be provided when human senses are conveyed to
a remote location without any distortion. Technology in this field has
developed substantially over the last decade, but it still has many limitations.
Most of the effort in this field has been in audiovisual technologies. The
status of these is briefly discussed:
• Vision: It is generally understood that images are transmitted over the
Internet as static two-dimensional camera views. Using multiple cameras
to provide several viewpoints is possible. Dynamic panning and movement
is possible using motorised equipment, but it increases the costs of
implementation substantially. Full-colour three-dimensional viewing re-
quires special display equipment and is uncommon. The transmission of
images over the Internet is susceptible to real-time delays in periods of high
network traffic. Visual effects relying on persistence of vision of the human
eye cannot be transmitted easily due to limited frame rates.
• Hearing: Audio transmission has progressed substantially with the devel-
opment of compression algorithms that provide high fidelity but use a
relatively low amount of bandwidth, for example, Moving Picture Experts
Group Audio Layer 3 encoding (MP3). Sound is most commonly monopho-
nic in nature, but software support for stereophonic and surround sound
standards, for example, Dolby Pro Logic, is common. The only requirement
is the availability of suitable sound hardware at the client side. The
transmission of audio is also susceptible to delays in periods of high network
traffic as is often experienced when using the Internet to make telephone
calls. It is also sensitive to sporadic packet loss; unlike video, it is not
possible to interpolate to make up for missing data.
Design Advantages in the Remotely Accessible Embedded Systems
Laboratory
• Low cost: The system was designed to minimise construction and mainte-
nance costs, primarily by setting out to efficiently utilise a relatively small
number of development systems.
• Minimised use of custom software: The design attempts to avoid the use
of custom software. Custom software is widely understood to be the
weakest link in any complex system. The use of standard hardware and
software components speeds up implementation and increases reliability
(Hamlet, Mason, & Woit, 2001).

• Maximised use of open-source software: The system uses open source,
freely available software technologies when possible, for example, Linux
and PostgreSQL server. This relieves the UTS of the obligation to maintain
and finance continued development of the software, while at the same time
allowing the UTS to make enhancements which can be re-released to the
general community in the spirit of the UTS’s role as an educational
institution. This also contributes to an overall reduction in cost since
purchasing and licensing costs are removed.
• Maximised use of off-the-shelf hardware: The system uses off-the-
shelf hardware conforming to popular, well-known standards for operating
systems support, interconnection, and interoperability. Proprietary prod-
ucts have been avoided when possible.
• Dynamic system: The system is not monolithic; the implementation does
not force the use of any specific technologies. It is dynamic in nature, and
different components can be replaced and improved as new technologies
are developed.
• High availability: Students can use the laboratory from any Internet-
connected computer with a modern Java-enabled Web browser and freely
available SSH client.
• Efficient use of limited real estate: Laboratory components do not have
to be situated in the same room. They can be distributed over different
rooms or even different countries, as long as each location has Internet
access. This makes expansion more practicable as any free space within
the university can be utilised.
• High security: The use of encrypted protocols such as SSH and HTTPS
avoids the transmission of plain-text passwords over university networks,
preventing security breaches through password “sniffing.”
A system which poses such a dramatic departure from conventional physical
laboratory infrastructure and modes of use naturally requires careful and
continual assessment. This has been carried out over the past three years, and
a considerable amount of effort has been directed at ensuring that the evaluation
processes have been completed from every conceivable perspective.

298 Murray & Lasky
Real-Time Operating Systems Assignments Completed
by the Students
The remote laboratory has been highly successful. Students are applying theory
learnt in the lectures and tutorials to a real-world environment. In the past, the
students relied on special teaching operating systems which were frequently
based only on PC hardware and possessed inherent limitations (Comer &
Fossum, 1984; Tanenbaum & Woodhull, 1997). Assignment and practical work
which is potentially hazardous to the health of the running operating system can
be carried out without concern. For example, an experimental modification to the
uClinux kernel that results in a damaged memory-based file system will not cause
significant damage when tested on the target processor; whereas, it certainly has
the potential to cause serious data loss if attempted on the student’s own personal
computer. Students are not restricted to carrying out relatively superficial
programming assignments that involve only developing some user-space pro-
grams.
Student Feedback
The UTS Planning & Quality Unit (and its predecessors) has been responsible
for administering a UTS Subject Feedback System (SFS) for a number of years.
As part of this system, Subject Feedback surveys are issued to students in each
UTS subject at the end of every academic semester as a single-page sheet. The
sheet contains a set of standard questions relating to the subject in a general
sense but also permits the student to make unstructured comments. In three
semesters surveyed, the students returned mixed responses to the system. Some
students reported having difficulty relating to the system they were using. In
some cases these difficulties were attributed to the system being physically
remote, making it difficult to visualise what it was they were actually doing with
the system (Moulton, Lasky, & Murray, 2003). In subsequent semesters, the
students were taken on a one-off guided tour of the remotely accessible
embedded systems laboratory at an early juncture in the semester so that they
could better appreciate their later interactions with the various components of the
system. This helped those who were having some difficulty coming to terms with
the abstractions.
Students throughout all semesters expressed comments stating strong apprecia-
tion of the practical nature of the exercises they had been able to complete. Some
praised the hands-on nature of the assignments and stated that they believed that
knowledge gained was industrially and commercially relevant. Many students

had not had previous exposure to Linux or UNIX and were happy to have the
chance to learn how to operate in this environment.
Tutor Feedback
In spring 2003, it was decided to begin a survey of academic staff tutoring the
Real-Time Operating Systems subject. It was structured in a similar way to the
Subjects Feedback surveys but included questions related directly to the remote
laboratory and assignments. The tutors were unanimous in their opinion of online
support being effective in supporting students, and all of them found to a
significant degree that it reduced their normal support workload. It can be
concluded that the academic staff were generally satisfied and enthusiastic
about the environment. In the first written-answer question, all academics
agreed that the convenience of being able to access the laboratory from
anywhere was one of the best features.
The remotely accessible embedded systems laboratory has been recently made
available to a small number of students to use in completion of their major
undergraduate project. This further demonstrates the flexibility of the system
and increases its utilisation. There is little overhead in providing project students
with an account on the system and permitting them to work at their own pace on
complex tasks over two semesters.
Conclusion and Future Directions
The remotely accessible embedded systems laboratory as used by the Real-Time
Operating Systems course at the UTS is an invaluable resource. It exposes
students to development processes which are outside of their normal experience
and are relevant to industry needs. The students are able to conduct potentially
complex programming tasks in a safe, convenient, and secure way — something
which traditionally has only been available with vastly greater infrastructure and
cost in a conventional physical laboratory.
As a testament to the solid design and development of this particular laboratory,
the Faculty of Engineering at the UTS has embarked upon a program that aims
at converting several other conventional physical laboratories to a remotely
accessible mode (Weber, personal communication, 2003). The flexibility inher-
ent in the original design of the remotely accessible embedded systems labora-
tory means that much of the infrastructure required will not have to be developed
from scratch. Currently, two more remotely accessible laboratories are under

300 Murray & Lasky
development. One supports a development system for field programmable gate
array (FPGA) devices, and the other entails controlling electromechanical and
pneumatic apparatus via programmable logic controller (PLC) systems. It is
anticipated that these will be online for the autumn 2005 semester.
Summary
A sophisticated processor is required to demonstrate the key concepts that are
essentialtoamodernoperatingsystem,forexample,multitasking,multithreading,
a structured and abstracted hardware management layer, communications
utilising various protocols over network interfaces, and memory resident file
systems. Unfortunately, high-end 32-bit embedded systems processors capable
of supporting these facilities are expensive compared to the conventional 8-bit
and 16-bit targets, and also it is not always feasible to acquire a large number of
high-end processors to house in a laboratory to provide practicals for more than
100 students. To overcome this problem, this chapter proposed a remotely
accessible embedded systems laboratory. The proposed system uses a small
number of 32-bit development systems and is accessible through the Internet so
that students can use it in the conventional way following a development path that
commences with cross-development and concludes with testing on the 32-bit
target and viewing the results.
Cross-development: The process of using software development tools like
compilers, linkers, and debuggers which are resident on a reprogrammable
computer to produce executable programs for an embedded computer
system. The executable programs must then be transferred from the
reprogrammable computer (called the development system) to the embed-
ded computer (called the target system) for testing.
Embedded computer system: Computers that are comprised of a processor
(microprocessor or microcontroller), memory, and I/O devices that are
“special purpose” in that they are tightly coupled to or even architecturally
a component of other systems with which they interact. Their primary I/O
devices are usually not human-user-centric. Examples are regulators and
controllers in domestic appliances and automotive systems, negative feed-
back automatic control systems in the chemical process industries, and
autopilots for ships and aircraft.

Review Questions
1. List and describe three main features of the proposed remotely accessible
embedded systems laboratory.
2. List and describe three main benefits of using the remotely accessible
embedded systems laboratory.
3. Discuss the effectiveness of the remotely accessible embedded systems in
teaching and learning contexts.
4. List and describe three existing remote cross-development systems.
5. Describe the topology of the remotely accessible embedded systems
laboratory.
6. Discuss the possible enhancements to the practical activities in general and
the remotely accessible embedded systems laboratory in particular.
References
Aktan, B., Bohus, C. A., Crowl, L. A., & Shor, M. H. (1996). Distance learning
applied to control engineering laboratories. IEEE Transactions on Educa-
tion, 39(3).
Bühler, D., Küchlin, W., Gruhler, G., & Nusser, G. (2000). The virtual automa-
tion lab—Web-based teaching of automation engineering concepts. In
Proceedings of the 7th annual IEEE International Conference on the
Engineering of Computer Based Systems. Edinburgh, Scotland, UK:
IEEE Computer Society Press.
Comer, D., & Fossum, T. (1984). Operating system design: The Xinu
approach. Englewood Cliffs, NJ: Prentice Hall.
Hamlet, D., Mason, D., & Woit, D. (2001). Theory of reliability of software
components. Retrieved November 14, 2003, from http://www.cs.pdx.edu/
~hamlet/icse01.pdf
In-Stat/MDR. (2002, September 10). MCU market to experience unit growth
through 2006 while prices erode. Retrieved December 2004 from https:/
/www.instat.com/newmk.asp?ID=325
Knight, C. D., & DeWeerth, S. P. (1997). A distance learning laboratory for
engineering education (No. 1532). Southeastern University and College
Coalition for Engineering Education. Retrieved from http://
www.succeed.ufl.edu/papers/97/01316.pdf

302 Murray & Lasky
Lasky, V. L. A. (2003). Remote embedded systems laboratory (Capstone
Project Rep.). New South Wales, Australia: University of Technology,
Sydney, Faculty of Engineering.
Marques, L. C. C., Wisintainer, M. A., & Alves, J. B. d. M. (1998). Real remote
experiment with 8051 microcontroller—RExLab. Retrieved November
2003 from http://www.edatoolscafe.com/technical/papers/Rexlab/
Moulton, B. D., Lasky, V. L., & Murray, S. J. (2003). Remote embedded
systems development environment: Feedback from students and subse-
quent enhancements. UICEE World Transactions on Engineering and
Technology Education, 2(1).
Open Learning Australia. (2003). OLA list of qualifications in 2003. Retrieved
November 2003 from http://www.ola.edu.au/cgi-bin/hive/
hive.cgi?HIVE_PROD=0&HIVE_REQ=2001&HIVE_REF=hin%3aO
LA%2003000PUB04%20DOC%20Content&HIVE_RET=ORG&HIVE_CMP=1
Tanenbaum, A. S., & Woodhull, A. S. (1997). Operating systems design and
implementation (2nd ed.). Upper Saddle River, NJ: Prentice Hall.

LOGIC-Minimiser 303
ChapterXVI
LOGIC-Minimiser:
A Software Tool to
Enhance Teaching and
Learning Minimization of
Boolean Expressions
Khaleel I. Petrus, University of Southern Queensland, Australia
Abstract
Boolean algebra, minimization of Boolean expressions, and logic gates are
often included as subjects in electronics, computer science, information
technology, and engineering courses as computer hardware and digital
systems are a fundamental component of IT systems today. We believe that
students learn minimization of Boolean expressions better if they are given
interactive practical learning activities that illustrate theoretical concepts.
This chapter describes the development and use of a software tool (named
LOGIC-Minimiser) as an aid to enhance teaching and learning minimization
of Boolean expressions.

304 Sarkar & Petrus
Learning Objectives
• List and describe three main features of LOGIC-Minimiser.
• Explain how LOGIC-Minimiser can be used in the classroom to enhance
teaching and learning Boolean expression minimization.
• Describe the Q-M algorithm for the minimization of Boolean expressions.
• Define the following key terms: Boolean expression, SOP, logic gate, logic
minimization, and K-maps.
Introduction
It is often difficult to motivate students to learn minimization of Boolean
expressions because students find the subject rather abstract and technical. A
software tool (named LOGIC-Minimiser) has been developed that gives students
a hands-on learning experience in minimizing Boolean expressions. LOGIC-
Minimiser was developed in C language under MS Windows and is suitable for
classroom use in introductory Boolean algebra courses. Based on user input (i.e.,
logic expression), the system displays the sum of product (SOP) functions as well
as minimized logic gate diagrams. Test results demonstrate the successful
implementation of LOGIC-Minimiser, and the simplicity of the user interface
makes it a useful teaching and learning tool for both students and instructors.
This chapter describes the development of LOGIC-Minimiser and its usefulness
as an aid to teaching and learning minimization of Boolean expressions. The
chapter concludes with a discussion of the strengths and weaknesses of LOGIC-
Minimiser and its future development.
essential concepts included in electronics, computer science, information tech-
nology, and engineering. These concepts play a fundamental role in computer
hardware and digital systems design. We believe that it is extremely important
to incorporate practical demonstrations into these courses to illustrate theoretical

LOGIC-Minimiser 305
concepts and therefore provide an opportunity for hands-on experience. These
demonstrations will significantly enhance student learning about Boolean ex-
pressionminimization.
In fact, very little material has been designed and made available for public
access to supplement the teaching of Boolean expression minimization. This is
revealed by searches of the Computer Science Teaching Center Web site (http:/
/www.cstc.org/) and the SIGCSE Education Links page (http://sigcse.org/
topics/) on the Special Interest Group on Computer Science Education Web site.
We strongly believe, as do many others (Bem & Petelczyc, 2003; Hacker &
Sitte, 2004; Ibbett, 2002; Leva, 2003; Shelburne, 2003; Williams, Klenke, &
Aylor, 2003), that students learn more effectively from courses that provide for
active involvement in hands-on learning activities.
Boolean expression minimization is one of the most challenging subjects to teach
and learn in a meaningful way because students find the topic full of technical
jargon, dry in delivery, and quite boring. Sarkar, Petrus, and Hossain (2001) have
developed LOGIC-Minimiser in C under MS Windows to give students an
interactive, hands-on learning experience in minimization of Boolean expres-
sions. LOGIC-Minimiser can be used by a teacher in the classroom as a
demonstration to enhance the traditional lecture environment at an introductory
level. Also, students can use the system in completing tutorials on Boolean
expression minimization and to verify (interactively and visually) the results of
in-class tasks and exercises on Boolean expression minimization. LOGIC-
Minimiser can be used either in the classroom or at home as an aid to enhance
teaching and learning Boolean expression minimization.
Minimization of Boolean expressions using traditional methods such as truth
tables, Boolean algebra, and K-maps can be very tedious and is not well-suited
for expressions involving more than six variables. A more useful approach, the
Quine-McCluskey (Q-M) algorithm, also called tabular method, is an attractive
solution for minimizing complex Boolean expressions involving variables of any
length. Moreover, the algorithm lends itself to a fast and easy machine implemen-
tation.
The remainder of the chapter is organized as follows. First we examine various
open source software tools suitable for logic-gate design and minimization. We
then describe LOGIC-Minimiser in teaching and learning contexts. Then,
software implementation of LOGIC-Minimiser is discussed, and the educational
benefits of the software are highlighted. An example of a classroom plan and
LOGIC-Minimiser in practice is discussed. Test results which verify the
successful implementation of LOGIC-Minimiser are presented, followed by a
conclusion and future research directions.

306 Sarkar & Petrus
Related Work
A detailed discussion of digital systems design and minimization of Boolean
expressions in general can be found in Green (1985), Greenfield (1977), Mano
(1984), and Tanenbaum (1999). The Quine-McCluskey algorithm is described
extensivelyinthecomputerhardwareanddigitallogicdesignliterature(Carothers,
2003; Costa, 2004; Hideout, 2003; Hintz, 2003). Grimsey (2000) examined the
strengths and weaknesses of various methods of minimizing Boolean expres-
sions, including truth tables, Boolean algebra, and Karnaugh maps (K-maps).
A variety of open source and commercial software tools exist for modelling and
simulation of logic circuit design and Boolean expression minimization. These
powerful tools can have steep learning curves; while they may be good for doing
in-depth performance modelling of computer hardware and logic design, they
often simulate a hardware environment in far more detail than is necessary for
a simple introduction to the subject.
Lockwood (2003) presented a program for the implementation of the Q-M
algorithm. However, it is of limited use as a teaching and learning tool because
of its text-based interface that is not user-friendly. Leathrum (2003) described
another text-based menu-driven program for the Q-M algorithm, but the user
interface is rather difficult to use. Costa (2004) developed a package called
“bfunc” for Boolean functions minimization. It is an MS-DOS-based program
and is considered an alternative to the K-map method of simplifying Boolean
functions. Burch (2002) proposed a tool named Logisim, a graphical system for
logic circuit design and simulation which is suitable for classroom use. Logisim
is a Java application and can be run on both Windows and Unix workstations.
WhileLogisimisanexcellenttoolforbuildingavarietyofcomplexcombinational
circuits, but it is not suitable for logic gate minimization. Other tools such as
Digital Works 3.0 (2001) and LogicWorks (1999) are similar to Logisim in that
they provide a graphical toolbox interface for composing and simulating logic
circuits. LOGIC-Minimiser, which we describe in the next section, has its own
unique features, including simplicity and ease of use either in the classroom or
at home, to enhance teaching and learning Boolean expression minimization.
Architecture of LOGIC-Minimiser
Figure 1 shows the structured diagram of LOGIC-Minimiser. The main features
of LOGIC-Minimiser are briefly described.

LOGIC-Minimiser 307
• New: This feature allows users to enter a new set of variables for
minimization.
• Min/Out: This feature allows users to view a minimized sum of product
(SOP) expression and logic circuit diagram.
• Quit: This feature allows users to exit from the program at any time.
The following three features have not been implemented yet and are considered
as future work.
• Load: This feature will allow users to view existing data (i.e., minimized
minterms) for further analysis and modifications.
• Save: This feature will allow users to store outputs on disk for later use and
further modifications.
• Help: This feature will provide help on various topic related to minimization
Software Implementation
The Q-M algorithm is used to reduce a Boolean expression to its simplest form.
It is designed particularly for use with problems containing six variables or more
but can be used equally well for a smaller number of variables. The algorithm is
based on repeated applications of the distributed law and the fact that XOR
Figure 1. Structured diagram of LOGIC-Minimiser

308 Sarkar & Petrus
(NOT X) is always true. The Q-M method is a systematic way of selecting the
pairs to be used for simplification. The main steps in the Q-M algorithm are
summarized below:
1. Representing all addends as sums of minterms
2. Grouping the minterms that have the same number of ones
3. Merging the terms that differ in only one bit (this is done in several steps)
4. In order to find the irredundant cover we use the min-cover algorithm:
a. Find all distinct minterms.
b. Find all essential prime implicants.
c. Find all the minterms that are covered by the essential prime implicants.
d. Remove all minterms and prime implicants found in (a)-(c).
e. Choose that prime implicant that covers most of the remaining
minterms.
f. Repeat (d) until all minterms have been covered.
A structured analysis and design has been employed to design the package. C
programming language under MS Windows has been used in the implementation.
of LOGIC-Minimiser
For simplicity and ease of use, it has been decided to implement LOGIC-
Minimiser with a menu-driven, keyboard-based interface with a few menu
options. The interface is self-explanatory, which makes the package well-suited
for both students and teachers for classroom use. Therefore, the package can
be an integral part of a 2-hour session for teaching and learning the Q-M method
for logic gate minimization. An in-class task will be given to the students to
produce a minimized logic diagram on paper. After a prescribed period of time
(for example, 20 minutes), LOGIC-Minimiser will be introduced to the students
on a step-by-step basis to verify their solution and learn more about minimization
LOGIC-Minimiser provides the following main benefits:

LOGIC-Minimiser 309
• Hands-on: It facilitates an interactive, hands-on introduction to minimiza-
tion of Boolean expressions.
• Modelling: It provides a simple and easy way to develop a variety of SOP
functions and models. Students can experiment with minterms of various
sizes and develop a sound knowledge and understanding of Boolean
expressionminimization.
• Ease of use: The use of a menu-driven interface makes LOGIC-Minimiser
easy to use and a user-friendly tool. The software can be easily installed
and run on any PC operating under MS Windows.
• Economical/usefulness: It enhances face-to-face teaching with online
learning and can be used either in the classroom or at home to provide
hands-on experience.
• Robustness: It was tested on various PCs across campuses and was found
to be robust.
• Challenging: It provides an environment for students to test their knowl-
edge on Boolean expression minimization.
Example of Classroom Plan
In this section we present a detailed lesson plan (2-hour session) which can be
used in teaching and learning minimization of Boolean expressions using LOGIC-
Minimiser. The learning outcomes focus on learning the Q-M algorithm as well
as use of the software tool for verifying results of Boolean expression minimi-
zation. The lesson plan incorporates a number of resources and classroom
activities, including revision of Boolean expressions, brainstorming, teaching,
example, worksheet, demonstration of software package, and use of the package
to verify the worksheet exercises.
Lesson Plan
Table 1 lists the learning outcomes, resources, and various activities that can be
conducted in the classroom in teaching minimization of Boolean expressions
effectively. It can be used for a 2-hour lecture session on the minimization of
Boolean expressions. The lesson plan includes a guided worksheet (see Table 2)
suitable for classroom use.

310 Sarkar & Petrus
How to Use the System
LOGIC-Minimiser is easy to use and can be run from any PC operating under
MS-DOS/Windows. To run the package, the user can either double-click on
“newqm.exe” or type “newqm” at the DOS prompt. The main steps of using this
package (from Windows) are summarized below:
• Run: Double-click on “newqm.exe.”
• Entering minterms: Select the New option to enter a new set of
minterms. The user will be prompted for the number of variables to be used.
After entering the appropriate number of variables, a matrix of cells with
index numbers will appear on the screen. At this point the user can enter
each minterm by selecting a cell by pressing the Enter key on the keyboard.
• Accepting data: When a set of minterms has been entered, press the F8
key to accept.
• Display diagram: The minimized logic-gate diagram can be seen on the
screen in graphics mode. The user can zoom the diagram using the F1, F2,
Table 1. Lesson plan (2-hour session with 10-minute break)
By the end of this session students will be able to:
• Outline steps in minimization of Boolean expressions using Q-M algorithm.
• Use LOGIC-Minimiser to verify the minimization of Boolean expressions.
Resources
required
• LOGIC-Minimiser
• Data Show
• Computer Laboratory
• Whiteboard
• Worksheets
Time (minutes) Activity
10 Quickly review of Boolean expressions
5 Brain storming (ask the class what they know about Boolean expression
minimization)
15 Explain Q-M algorithm
5 LOGIC-Minimiser demonstration
15 Solve workout/example problems
10 Break
20 Worksheet Exercises (ask the class to work in pairs and solve worksheet exercises)
20 Use LOGIC-Minimiser and verify results of minimization (worksheet exercises)
10 Conclusion and checking learning outcomes
Review:
What went well:
What could be improved:

LOGIC-Minimiser 311
and F3 keys for 100%, 50%, and 20% scaling, respectively. To go back to
main menu, press the F10 key.
• Display minterms and output: Select the Min/Out option from the main
menu to see the list of minterms (that have been entered) and the minimized
output expression.
• Exit from the program: Select the Quit option from the main menu to exit
from the program at any time.
Table 2. Boolean expression minimization worksheet
Consider the minimization of following logical function:
D
C
B
A
D
C
B
A
D
C
B
A
D
C
B
A
D
C
B
A
D
C
B
A
F .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
. +
+
+
+
+
=
The above function can be written as:
∑
= )
9
,
8
,
4
,
2
,
1
,
0
(
)
,
,
,
( D
C
B
A
F
Where 0, 1, 2, 4, 8, 9 are the decimal values of the minterms.
It is required to apply the minimization on this Boolean function with the use of Quine-McCluckey’s
algorithm, firstly by hand and then verify the solution using LOGIC-Minimiser.
Solution:
1. Write the first list as:
A B C D
0 0 0 0 0
1 0 0 0 1
2 0 0 1 0
4 0 1 0 0
8 1 0 0 0
9 1 0 0 1
2. Deduce the second list (You have to complete this list)
A B C D
0,1 0 0 0 -
0,2
0,4
0,8
1,9
8,9 1 0 0 -
3. Third list (You have to do it all yourself)
A B C D
0,8,1,9
4. Now build the chart which relates minterms with the prime implicates as shown:
0 2 4 8 9
C
B
A .
. X X
5. Now use the LOGIC-Minimiser to cross check your solution.

312 Sarkar & Petrus
Test Results
To evaluate the performance of LOGIC-Minimiser, the software has been
installed on various PCs and tested with various Boolean expressions, each
involving a different number of input variables. Then the test results were
validated manually. Figure 2 shows a sampletest result for four-variable(A, B, C,
and D) Boolean expression minimization. The following minterms were entered
fromthekeyboard:[0,2,3, 5,7,8,10,13,15],andthesoftwareproducedthesimplified
logic-gate diagram as well as the output expression, as shown in Figure 2.
Evaluation
An earlier version of LOGIC-Minimiser had been presented at the National
Advisory Committee on Computing Qualifications conference in Napier, New
Zealand (Sarkar & Petrus, 2001). The discussion during the conference presen-
tation was quite encouraging, and many staff members from various polytechnic
institutions expressed their interest in using the package in their classes.
Figure 2. Example of four-variable minimization with minimized output
expression and logic gate diagram

LOGIC-Minimiser 313
To assess the educational value of LOGIC-Minimiser, we administered a survey
to the students of the introductory digital logic subject. The survey was repeated
for two consecutive years. Overall results revealed that the majority of students
found the package useful and user-friendly, with an overall rating of 4 out of 5.
The questionnaire also posed five open-ended questions: (1) How well did you
understand minimization of Boolean expressions before entering this course? (2)
How easy did you find the software package to use? (3) How well did the
package help in understanding the minimization of Boolean expressions? (4)
Would you like to have more software tools of this kind as part of your course?
(5) Would you prefer to learn minimization of Boolean expressions in a hybrid
mode (i.e., minimization by hand and verification of results by software tool)?
Concluding Remarks
A software tool (LOGIC-Minimiser) has been developed that can be used in the
classroom to enhance the teaching and learning of various aspects of Boolean
expression minimization. LOGIC-Minimiser is easy to use and can be run from
any computer operating under MS-DOS and MS Windows. It was tested on
various PCs and was found to be robust. Many staff members from various
polytechnic institutions expressed their interest in using the software in the
classroom.
Currently, the system minimizes Boolean expressions involving variables of size
8, which is adequate for demonstration purposes. LOGIC-Minimiser can easily
be upgraded to accommodate variables of any length. User options such as New,
Min/Out, and Quit have been implemented. More options such as Save, Load,
and Help are still under development, and incorporation of a mouse-based user
interface is also suggested for future work.
LOGIC-Minimiser is available free of cost to faculty interested in using it to
supplement their teaching. More information about LOGIC-Minimiser can be
obtained by contacting the first author.
Summary
essential concepts included in electronics, computer science, information tech-
nology, and engineering. These concepts play a fundamental role in computer

314 Sarkar & Petrus
hardware and digital systems design. We believe that it is extremely important
to incorporate practical demonstrations into these courses to illustrate theoretical
concepts and therefore provide an opportunity for hands-on experience. These
demonstrations will significantly enhance student learning about Boolean ex-
pression minimization. This chapter described the development and use of
LOGIC-Minimiser as an aid to enhance teaching and learning Boolean expres-
sion minimization. It was tested on various PCs and was found to be robust.
Boolean expression: An expression which results in a Boolean (binary or
TRUE/FALSE) value. For example 4 > 3 is a Boolean expression. All
expressions that contain relational operators like >, <, and so forth are
Boolean. Logical gates and their combinations are used to implement
physical representations of Boolean expressions.
K-maps: This term refers to Karnaugh maps, a logical minimization method
based on graphical representation of Boolean functions in which each row
in the truth table of the Boolean function is represented as a box. Unlike the
truth table, K- map values of input must be ordered such that the values of
adjacent columns vary by one single bit.
Logic gate: An electronic device (based on transistors) used for implementing
logical functions. The inputs and outputs of the gate are Boolean (i.e.,
binary) values. Gates can be used to implement various Boolean functions.
NOT gates take one input and have one output. The AND, NAND, OR, and
NOR gates may take two or more inputs and have one output. XOR gates
take two inputs and have one output. Logical functions are all combinational
functions, that is, their output depends on the input. Gates can also be used
to implement latches and flip-flops which have an internal state and are
used to implement sequential logical systems.
Logic minimization: Simplification of Boolean expressions with the aim of
reducing the number of logical gates. This is done by reducing the number
of minterms into a number of prime implicants in which as many variables
as possible are eliminated. The tabular method makes repeated use of the
rule Â + A = 1.
LOGIC-Minimiser: Software package developed at the Auckland University
of Technology to enhance teaching and learning minimization of Boolean
expressions. The package was implemented in C programming language.

LOGIC-Minimiser 315
Minterms: This term refers to the product of Boolean variables. These
variables can appear either as themselves or their inverses. A minterm
corresponds to exactly one row in the truth table of the Boolean function.
If we have four variables A, B, C, and D, then a minterm can be something
like A.B.C.D or .B.C.D, and so forth.
Quine-McCluskey algorithm: Table-based reduction method for simplifica-
tion of Boolean expressions. This method is quite versatile as compared
with other algorithms. It can handle any number of inputs and can easily be
implemented on machines. The method starts from the truth table of the
Boolean function.
Sum of product (SOP): A two-level expression which represents a sum of
minterms of a logical function. It is two-level because it is implemented by
two layers of logic gates. The first level represents the product of Boolean
variables of the logical function and the second level represents summing
the products with OR operator.
Review Questions
1. List and describe three main features of LOGIC-Minimiser.
2. Discuss the usefulness of LOGIC-Minimiser in teaching and learning
contexts.
3. Describe the main steps in the Q-M algorithm for the minimization of
Boolean expressions.
4. Define the following key terms: Boolean expression, logic gate, logic,
minterms, and K-maps.
5. Explain how LOGIC-Minimiser can be used in the classroom for demon-
stration.
6. List and describe further enhancements to LOGIC-Minimiser.
References
Anonymous. (2006). Digital Works. Retrieved January 5, 2006, from http://
www.spsu.edu/cs/faculty/bbrown/circuits/howto.html
Bem, E. Z., & Petelczyc, L. (2003, February 19-23). MiniMIPS: A simulation
project for the computer architecture laboratory. Paper presented at

316 Sarkar & Petrus
the Proceedings of the 34th Technical Symposium on Computer Science
Education (SIGCSE‘03), Reno, NV (pp. 64-68).
Burch, C. (2002). Logisim: A graphical system for logic circuit design and
simulation. Journal of Educational and Resources in Computing, 2(1),
5-16.
Carothers, J. D. (2003). Quine-McCluskey algorithm. Retrieved September
20, 2004, from http://www.ece.arizona.edu/~csdl/474aslide4
Costa, A. (2004). Boolean functions simplification (logic minimization).
Retrieved December 27, 2004, from http://www.dei.isep.ipp.pt/~acc/bfunc
Green, D. C. (1985). Digital techniques and systems (2nd
ed.). Longman.
Greenfield, J. D. (1977). Practical digital design using ICs. Wiley.
Grimsey, G. (2000). The truth, the whole truth, and/or nothing but the truth.
Journal of Applied Computing & Information Technology, 4(1), 42-52.
203.
Hideout, G. (2003). The Quine-McCluskey method of logic reduction.
Retrieved September 20, 2004, from http://www.geekhideout.com/
qmm.shtml
Hintz, K. (2003). Quine-McCluskey method. Retrieved September 20, from
http://www.cpe.gmu.edu/courses/ece331/lectures/331_8/sld001.htm
Ibbett, R. N. (2002, June 24-26). WWW visualization of computer architecture
simulations. Paper presented at the 7th annual SIGCSE conference on
Innovation and Technology in Computer Science Education (ITiCSE),
Aarhus, Denmark (pp. 247).
Leathrum, J. F. (2003). Quine McCluskey tabular minimization method.
Retrieved September 20, 2004, from http://www.ece.odu.edu/~leathrum/
ECE241_284/support/quine.html
Leva, A. (2003). A hands-on experimental laboratory for undergraduate courses
in automatic control. IEEE Transactions on Education, 46(2), 263-272.
Lockwood, J. W. (2003). Quine-McClusky algorithm; computational tech-
niques; cygwin freeware (GPL) tools. Retrieved September 20, 2004,
from http://www.arl.wustl.edu/~lockwood/class/coe460/
LogicWorks. (1999). Capilano Computing Systems Ltd. Retrieved January 10,
2006, from http://www.logicworks4.com
Mano, M. (1984). Digital design. Prentice Hall.

LOGIC-Minimiser 317
Sarkar, N., & Petrus, K. (2001, July 2-5). Logic gate minimization demonstra-
tion. Paper presented at the 14th annual conference of the National
Advisory Committee on Computing Qualifications (NACCQ), Napier,
New Zealand (p. 456).
Sarkar, N., Petrus, K., & Hossain, H. (2001, July 2-5). Software implementa-
tion of the Quine-McCluskey algorithm for logic gate minimization.
Paper presented at the 14th annual conference of the National Advisory
Committee on Computing Qualifications (NACCQ), Napier, New Zealand
(pp. 375-378).
Shelburne, B. (2003). Teaching computer organization using a PDP-8
simulator. Paper presented at the SIGCSE‘03 Technical Symposium on
Computer Science Education (pp. 69-73).
Tanenbaum, A. S. (1999). Structured computer organization (4th
ed.). Prentice
Hall.
Williams, R. D., Klenke, R. H., & Aylor, J. H. (2003). Teaching computer design
using virtual prototyping. IEEE Transactions on Education, 46(2), 296-
301.

318 Sarkar & Petrus
Section V
Data Communication
Protocols and Learning Tools

A Practical Introduction to Serial Protocols 319
ChapterXVII
APractical
Introductionto
SerialProtocols
Abstract
This chapter discusses how addressing information, control information,
and data are encapsulated in a serial packet or frame. It shows the bit-level
detail of an IEEE 802.3 Ethernet frame, an IP packet, and a TCP packet and
shows how these protocols are used to create a sample protocol stack. The
GNU-licensed and Windows-based application Packetyzer is used to explore
a sample TCP/IP packet contained in an Ethernet frame. Once the student
has studied the material of this chapter and has completed the hands-on
experiment, he or she will have the skills to examine any packet or frame
and, using the description of its protocol, extract the details of the message.

320 Tarnoff
Learning Objectives
• Describe the Ethernet, TCP and IP packet structures.
• Describe using general terms what a protocol stack is and how it is
important.
• Explain how a frame can be transmitted from one device to another across
a serial link.
• Define the following key terms: CRC, datagram, data link layer, MAC
address, and protocol.
• Suggest further enhancements to the practical activities presented in the
chapter.
Introduction
Since the early days of computer system design, it has been necessary to develop
communication schemes to allow the components of a digital system to exchange
data. For example, the earliest mainframe computers used terminals as the
standard method for user input and output. These terminals, connected either by
direct connection or through a modem, used a single wire to transmit characters
typed on the keyboard to the mainframe and a second wire to receive characters
from the mainframe to be displayed on the user’s screen. Any communication
method where data is transmitted over a single wire is referred to as serial
communications.
A number of different schemes have been developed for serial communications.
These schemes are defined by a set of rules that must be followed by both the
transmitting device and the receiving device in order to successfully transfer
data. The set of rules defining a specific serial communication scheme is referred
to as a protocol.
This chapter presents a general description of the components of a serial
protocol. This is followed by an overview of three serial protocols: Ethernet,
TCP, and IP. Finally, the Windows-based application Packetyzer is used to
examine an Ethernet packet containing a simple TCP acknowledgment message.
The methods presented here should allow for a basic understanding of some
standard protocols and how they might be embedded within each other.

Anatomy of a Frame
Although parallel wires are capable of sending data at a higher throughput,
sending data in a serial stream is by far the most common method of communi-
cating between two physically separate computer systems. This is due to the
physical nature of the connection. If fewer wires are needed to connect two
devices, then both the connectors and the cables are much cheaper. In addition,
when there are fewer connections to fail, the system becomes more reliable.
Fewer connections also make for smaller connectors, aiding in the miniaturiza-
tion of devices.
In order to communicate from one device to another, a number of pieces of
information are needed. If more than two devices are present on a network, then
addressing information for both the sender and receiver is required in order to
uniquely identify them. Signals are also needed for control, such as synchroni-
zation (timing), message type, data length, and error detection. For some
exchanges, it is also necessary to identify a message as being part of a specific
session or sequence. Finally, while not all exchanges contain data, many do.
Provisions must be available to identify where the data is located and how much
of it there is.
In a parallel communication scheme, each of the types of information listed
above is given a separate conductor or group conductors. This results in a bus
consisting of tens or even hundreds of conductors. These conductors are
separated into three groups: address, control, and data. One of the most common
examples of parallel communications is the bus that a processor uses to
communicate with the memory and I/O devices of the motherboard.
In serial communications, address, control, and data must all be sent across a
single wire. To compensate for the fact that only one wire is available for all of
the signals, a set of rules called a protocol is used to define timing and signal
components. These definitions describe the basic unit of communication be-
tween serial devices. At the bit level, this basic unit is referred to as a frame. As
the bits of a data transmission are sent out a device’s communications port, their
position within the frame defines their purpose. This level of communication is
referred to as the data link layer (layer 2) of the seven-layer OSI model of
networks.
In a large network, the addressing and control information is needed in order to
properly deliver messages. Usually, this requires a message to be embedded as
the data within another group of bits containing logical address and control
information. In the OSI model, this is referred to as the network layer (layer 3).
It is one layer above the data link layer. The packet is the basic unit of the network
layer. It is similar to a frame in that it contains addressing information, control

322 Tarnoff
signals, and data. The primary difference is that the addressing at the data link
layer is the physical address assigned to the devices that are communicating
while the network layer uses a logical addressing scheme. The logical addressing
scheme usually contains information to identify a device as part of a group, then
locate that device within the group. Physical addresses typically cannot be
altered while logical addresses can be configured by a network administrator.
In general, a frame is divided into three parts: the header, the body, and the trailer.
The header takes most of the responsibility for the addressing and control
information and may include:
• a bit pattern representing the start of a frame;
• a bit pattern used for signal synchronization;
• addressing for both the sender and receiver;
• session or sequence numbers;
• message length; and
• message type.
The body of the frame contains the data. The data may be either the raw data
passed from one device to another, or it may be an encapsulation of another
frame or packet. There are many examples of frames being packaged inside of
other frames. Typically, this occurs at the network layer where a frame crosses
from one network to another. An example of this is when a TCP/IP frame is
transferred from an Internet service provider (ISP) to a dial-up client across a
phone line. For the period when the message is moving across the phone line, the
TCP/IP frame is embedded as data inside the frame that the dial-up system is
using to communicate with the ISP.
The trailer brings up the end of the message. It usually contains error detection
information followed by a special bit pattern to indicate that the frame is
complete.
Sample Protocol: IEEE 802.3 Ethernet
IEEE 802.3 Ethernet is an example of a data link layer protocol that can be used
to transmit frames from one device to another across a serial link. It uses the
physical addresses of the device hardware interfaces to transmit anywhere from
0 to 1,500 octets of data in a single frame. Since the detection of errors is critical,
IEEE 802.3 Ethernet includes a 32-bit error detection value in the frame trailer.

Figure 1 presents the basic layout of an IEEE 802.3 Ethernet frame (IEEE
Computer Society, 2002, p. 38).
The frame begins with a preamble and start delimiter. The purpose of these 8
octets is to tell receiving devices when the message is going to start and to
provide synchronization for the receive circuitry. Specifically, the preamble is 7
octets (56 bits) of alternating ones and zeros, the very first bit of which is a one.
This “square wave” acts like a clock, ensuring that all of the receiving devices
are reading data at the same point in each bit time. The preamble is immediately
followed by a single octet equal to 10101011. This start delimiter maintains the
alternating binary pattern set up by the preamble until the last bit. The pair of ones
next to each other informs the receiving devices that the next component of the
frame’s header, the destination address, will immediately follow.
The destination address and source address identify the hardware involved in the
message transaction. It is important not to confuse these addresses with IP
addresses, which are logical addresses for the network layer. Instead, these
addresses are hardwired into the physical hardware of the network interface
card (NIC). These addresses, referred to as Medium Access Control (MAC)
addresses, are loaded into the NIC by the manufacturer and cannot be modified.
They are six octets long with the first three octets identifying the manufacturer.
If the destination address is all ones, then the message is meant to be a broadcast
and all devices are to receive it.
The next field in the frame is the 16-bit length field. The value in this field
represents the number of octets in the data field. With two octets, it is possible
to represent a value from 0 to 216
= 65,535. The definition of the IEEE 802.3
Ethernet, however, limits the range from 0 octets to 1,500 octets. Since only the
lower 11 bits of the 16 available bits are needed to represent the number 1,500,
5 bits of this field are unused. This is useful because later expansions of the
Ethernet protocol use these 5 unused bits to identify specific types of messages.
Figure 1. Layout of an IEEE 802.3 Ethernet frame
One Octet
Preamble
Start
Delimiter
Destination
Address
Source
Address
Length
Data Field (46
to 1500 octets)
CRC

324 Tarnoff
The data field comes next, and it contains the transmitted data. Although the
length of this field is defined by the two octets in the length field, the definition
of IEEE 802.3 Ethernet requires that the minimum length of the data field is 46
octets. If less than 46 octets are being transmitted, additional octets are used as
filler to expand this field to 46 octets. The filler octets are added after the valid
data octets.
The frame trailer at the end of the message contains a single 4-octet value called
a cyclic redundancy check (CRC). A CRC is a special value that is generated
from a long binary sequence. Imagine it as the remainder from a long division
where the entire frame, excluding the preamble and delimiter, is the dividend and
a universally defined constant is the divisor. If any error occurs during transmis-
sion of the frame, the remainder calculated by the receiver becomes significantly
different than that calculated and sent by the transmitting device. If the CRC
calculated by the receiver does not match the CRC sent with the message, then
an error has occurred and a retransmission of the frame is requested by the
receiver.
Since the destination and source addresses are each 6 octets, the length is 2
octets, the minimum data field is 46 octets, and the CRC is 4 octets, the minimum
Ethernet frame is 64 octets long. If the maximum data field length of 1,500 octets
is used, then the length of the maximum Ethernet frame is 1,518 octets.
Sample Protocol: Internet Protocol
The Ethernet frame is meant to encapsulate a packet from the network layer. A
common network layer packet for this is the Internet Protocol (IP) packet. IP
is used to transmit blocks of data called datagrams as either single blocks or as
partitioned fragments from one host to another across a logical network (Postel,
1981a). The basic function of IP is to provide routing. Therefore, it offers error
checking only for the header and has no mechanism for message sequencing or
flow control.
Basically, IP adds a header to a block of data so that the mechanisms of an IP
network can direct the packet from one host to another. Figure 2 presents the
basic layout of an IP packet header (Postel, 1981a, p. 11).
The IP packet header contains 14 fields providing the control information needed
to get a message from one host to another. Each field has a well-defined purpose
(Postel, 1981a, pp. 11-23).

• Version: The first four bits of the header identify the version of the protocol
defining the header.
• Internet header length: The number of octets in the IP header can be
calculated by multiplying the value contained in the last four bits of the first
octet of the header by 4. This shows the receiving device where the IP
header ends and the data block begins. Since the protocol defines the
minimum header length to be 20 octets long, the minimum value of this field
is 5.
• Type of service: The second octet of the header indicates how the packet
should be handled by the network. This includes properties such as
throughput and reliability.
• Total length: The two octets following the type of service indicate the total
length of the message, that is, the combined number of octets in the IP
header and the data that follows it. If the IP packet is embedded within a
frame, for example, an Ethernet frame, this total length field refers only to
the IP packet. Sixteen bits would allow for messages of length 65,535,
although most networks will not allow packets of this size.
• Identification: The two octets following the total length field are used by
the receiver to group the fragments contained in multiple IP packets.
• Flags: The next three bits are used for control of fragments of a datagram.
The most significant bit is reserved. The next bit indicates whether
Figure 2. Layout of an IP packet header
Version
Internet Header Length
Type of Service
Total Length
Identification
One Octet
Flags
Fragment Offset
Time to Live
Header Checksum
Destination
Address
Padding
Protocol
Source
Address
Options

326 Tarnoff
fragmentation of the datagram is allowed. The third bit indicates whether
the current fragment is the last fragment.
• Fragment offset: The 13 bits of this field identify the contained fragment’s
offset into the full datagram. This allows for reassembly of the datagram
by the receiver. Datagrams are partitioned into fragments at 64-bit
boundaries (8 octets), so the value in this field is to be multiplied by 8 to
determine the specific offset in octets. An offset of 0 indicates the fragment
contained in this packet is the first in the datagram.
• Time to live: This octet limits the amount of time that an IP packet is
allowed to remain on the network. It should be decremented every time the
packet encounters a module on the network before arriving at the destina-
tion. If allowed to reach zero, the packet is killed.
• Protocol: The eight bits of the protocol field identify the protocol of the
packet contained in the data field.
• Header checksum: The 16-bit header checksum is the one’s complement
of the one’s complement datasum of the 16-bit words contained in the IP
header. Note that since the checksum is part of the IP header, zeros are
inserted in this field during the checksum calculation. In addition, since
fields such as the time to live field may change during the routing of the
packet, the header checksum may need to be recalculated.
• Source and destination addresses: Each of these four-octet fields
contains an IP address. The first is the IP address of the sending device
while the second is the IP address of the receiving device.
• Options: Depending on the needs of a specific packet, a number of options
can appear in this field. The options identify requirements such as security,
time stamps, and routing information. This field is variable in length.
• Padding: The total length of an IP header must be a multiple of four octets.
The padding field of the IP header appends zeros to the header to guarantee
this.
Sample Protocol:
Transmission Control Protocol
One layer of abstraction above the network layer in the OSI model is the
transport layer. In general, the transport layer provides a means for breaking
large blocks of data into smaller fragments so that they may be reassembled by
the receiving device for the purpose of a specific application. A typical transport

layer protocol to be embedded in an IP packet is the Transmission Control
Protocol (TCP). TCP provides error checking, error recovery, and sequencing
for the packets along with providing a means for identifying the type of
application the packet is being delivered to, for example, distinguishing the
packets defining a Web page from those defining an e-mail.
TCP adds a header to a block of data so that the receiving device can manage
the incoming data. Figure 3 presents the basic layout of a TCP packet header
(Postel, 1981b, p. 15).
The TCP packet header contains 10 fields allowing large blocks of data to be
fragmented and sent from an application running on one device to an application
running on a second device. Each field has a well-defined purpose (Postel,
1981b, pp. 15-19).
• Source and destination ports: A port is a logical connection specifying
the type of service for which the data is meant to serve. Many protocols
have preassigned port values. For example, a port value of 80 identifies the
packet as containing http data while a port value of 23 identifies a telnet
packet. The source and destination port fields are both 16 bits in length and
identify the ports of the sending application and receiving application,
respectively.
• Sequence number: The sequence number is part of the mechanism used
to ensure that the multiple TCP packets making up a block of data have
Figure 3. Layout of a TCP packet header
Data Offset
Window
Urgent Pointer
Sequence
Number
Source
Port
Destination
Port
Acknowledgement
Number
Control Bits
Checksum
Options & Padding
One Octet

328 Tarnoff
been received and are ordered properly. The sender and receiver must
keep track of the sequence numbers, incrementing them by the amount of
data sent with each packet. The sequence number field is 32 bits long.
• Acknowledgment number: This 32-bit field is used in conjunction with
the sequence number. The receiver of a TCP packet acknowledges the
receipt of a TCP packet by responding to the sender with the next expected
sequence number inserted into the acknowledgment number field.
• Data offset: The length of the TCP header can be calculated by multiplying
the value contained in the four bits of the data offset field by 4. This shows
the receiving device where the TCP header ends and the data block begins.
A TCP header must always be an integer multiple of 32 bits long.
• Control bits: The 12 bits following the data offset field consist of six
reserved bits followed by six flag bits. The flag bits include flags such as
ACK (an indication that the acknowledge field contains a sequence
number), RST (a request to reset the connection), and FIN (an indication
that the sender has no more data to send).
• Window: The 16-bit window field is used by the device requesting data and
indicates how much data it or its network has the capacity to receive. It is
based on the amount of free buffer space the requesting device has and the
amount of available bandwidth.
• Checksum: The 16-bit checksum field contains the one’s complement of
the one’s complement datasum of 16-bit words contained in the TCP
header. Note that since the checksum is part of the TCP header, zeros are
inserted in this field during the checksum calculation.
• Urgent pointer: The 16-bit value in the urgent pointer field is used in
conjunction with the sequence number to identify the location of urgent data
in the data block.
• Options: Depending on the needs of a specific packet, a variable set of
options may appear in this field. The options identify requirements such
maximum receive segment size. This field is variable in length.
• Padding: The length of a TCP header must be a multiple of four octets. The
padding field of the TCP header appends zeros to the header to guarantee
this.

Protocol Stacks
By embedding packets from upper layers of the OSI network model within
packets or frames from lower layers, data can be sent from an application
running on one host to another application running on a second host. This format
of embedded packets and frames is called a protocol stack. The block diagram
in Figure 4 shows how the TCP packet is embedded within the IP packet, which
is in turn embedded in the Ethernet frame. This embedding will become clear with
the use of the protocol sniffer presented in the next section.
Capturing and Examining an
Ethernet Frame
The concepts of the previous sections can be demonstrated by examining the raw
data of an Ethernet frame containing an IP packet, which in turn contains a TCP
packet. The problem is that unless the user has access to electronic testing
equipment such as an oscilloscope, some of the bit patterns of ones and zeros of
an Ethernet frame are not visible. For example, the preamble and start delimiter
of the Ethernet frame are used only by the NIC for timing and synchronization.
These values are not saved for use by the user. The information contained within
the frame, however, is accessible by the user.
There are a number of programs available called protocol analyzers or sniffers,
that can display the data captured by a NIC. These nonintrusive programs
Figure 4. Layout of a TCP packet header
Data
TCP Header
IP Header
Ethrnt Header Ethrnt Trailer

330 Tarnoff
monitor the data that pass across the local network connection and capture it for
analysis. The user may specify one of a number of formats in which to display
the captured data. These formats range from decoded packets indicating the
type of message and the commands contained within it to the raw data copied
directly from the frame.
One such program, Packetyzer, is available for the Windows operating system
under the GNU license agreement (Waters, 2003). There are plenty of other
commercial, shareware, and open source applications available for both the
Microsoft and Unix platforms. Because of the principles behind the GNU
General Public License agreement supporting contributions to human knowl-
edge, universities are encouraged to use GNU GPL software in both education
and research (Stallman, 2002). This makes the use of Packetyzer in the
classroom an attractive option, although the concepts are general and should be
applicable to any of the other programs.
Upon start-up, Packetyzer prompts the user for the details of the capture session
using the window shown in Figure 5. These details include the adapter that will
be monitored, the capture session name, and any limits to be placed on the
captured data.
First, an Ethernet adapter should be selected from the adapter drop box. By
selecting an adapter that is connected to an active TCP/IP network, the student
should have plenty of Ethernet frames to analyze. To give the student a wide
range of packets to examine, the box enabling promiscuous mode should be
checked. This will allow Packetyzer to capture all frames and packets seen by
this adapter, not just the ones sent to it. The capture name allows the user to
identify the file name under which the captured data can be stored. Since
Packetyzer allows the user to reload saved sessions, saving a particular session
Figure 5. Packetyzer capture options window

may be used to allow the students to examine the same session or to allow
analysis of captured data without being connected to a network.
Once the user clicks the OK button, the Packetyzer main display screen appears.
In order to begin a capture session, the decode tab should be selected, as shown
in Figure 6.
At this point, a simple capture can be performed by clicking on the start/stop
capture button shown in Figure 7.
Once this button is pressed, packet information begins appearing in the main
display screen. In addition, the start/stop capture button should change such that
a small red circle with a white X appears on it. This button now serves to stop
the capture. After a significant number of packets have been captured, the
capture session should be stopped in order to examine a specific message. The
main display screen should look something like that shown in Figure 8.
The three windows in the main display screen present the details and data of the
captured packets. The left window is the tree details view. The students use this
view to examine the components of a selected packet or frame. The top right
Figure 6. Packetyzer decode tab identified on main display screen
Figure 7. Start/stop capture button identified on main display screen

332 Tarnoff
window, the packet list view, presents a list of all of the packets received during
the capture session. The bottom right window, the hex and ASCII details view,
shows the raw data of the selected packet divided into octets.
The student begins by selecting a TCP packet from the packet list view. This will
allow the user to examine not only the TCP header information but also the IP
header and Ethernet frame that encapsulate it in the protocol stack. In Figure 9,
packet number 14, a TCP acknowledge packet, has been selected.
Figure 8. Packetyzer main display screen with captured data
Figure 9. Packet list view with TCP packet selected

With a packet selected, the tree details view can be used to display the parsed
information from each of the protocols present in the packet. Figure 10 presents
this view with each of the branches collapsed.
By clicking on the plus sign next to each of the protocols, the details of the frame
are revealed. Figure 11 presents the tree details view with the details of the
Ethernet frame revealed.
The details of the Ethernet frame include the destination and source addresses.
Remember from the Ethernet frame discussion that the first three octets of the
MAC address used by Ethernet identify the manufacturer. In the details revealed
beneath the Ethernet identifier branch, it can be seen that the first three octets
of the destination address in this example represent a Cisco NIC while the first
three octets of the source address represent a Dell NIC.
By clicking on any of the details in the tree details view, the corresponding raw
data from the hex and ASCII details view is highlighted. Figure 12 shows how
selecting the Ethernet destination address causes the corresponding raw data to
be highlighted in the hex and ASCII details view.
Similarly, the components of each of the other protocols can be identified and
used by the students to compare with the raw data. Using the items from the tree
Figure 10. Tree details view with all branches collapsed
Figure 11. Tree details view with Ethernet branch expanded

334 Tarnoff
details view along with the highlighted data from the hex and ASCII view, the
students can examine and verify the components of the frame and embedded
packets. These components include addressing, header and frame lengths, and
checksums.
Conclusion
Serial communication is favored as a long-distance computer system interface
due to its reliability and cost-effectiveness. This comes with a consequence
though. All information pertaining to the delivery of a message must be contained
within a single stream of bits. In order to implement a serial data communication
system, a well-defined set of rules called a protocol must exist to specify the
placement and purpose of every bit sent across the link.
This chapter has shown how a tool called a protocol analyzer can be used to
examine the frames of the data link layer and the packets of the network and
transport layers. This can be a valuable tool for any network administrator who
wishes to debug or evaluate the performance of a network or a system designer
who needs to verify the operation of their system.
Figure 12. Message with Ethernet destination address identified

Summary
This chapter described the serial packet and its addressing, data encapsulation,
and control information. It showed the bit-level detail of an IEEE 802.3 Ethernet
frame, an IP packet, and a TCP packet and showed how these protocols are used
to create a sample protocol stack. The GNU-licensed and Windows-based
application Packetyzer is used to explore a sample TCP/IP packet contained in
an Ethernet frame. By completing the practical activities, students developed a
better knowledge and understanding of the use of a protocol analyzer.
CRC: CRC stands for cyclic redundancy check. This is a method for checking
for errors in a data stream. It uses a polynomial (a pattern of ones and zeros)
as a divisor in a modified division of the entire data stream. The remainder
of the division is appended to the message along with the data to be used
as a verification by the receiver of the data stream.
Datagram: A datagram is a block of data meant to be treated as a unit. If the
datagram is too large to be handled by a network, it is possible to fragment
it for transmission into smaller packets.
Data link layer: This is the second layer of the OSI model, and it defines the
pattern or purpose of the bits of a frame. Except for the physical layer,
which defines the electronics behind a computer interface, it is the lowest
level of the OSI model.
ISP: ISP stands for Internet service provider. This is a company that acts as a
access point for users of the Internet.
MAC address: MAC stands for Medium Access Control. The MAC address
is a six-octet value that is permanently assigned to a NIC to uniquely
identify it in any network. MAC addresses are loaded into the NIC by the
manufacturer and can not be modified. The first three octets identify the
manufacturer.
Network layer: This is the third layer of the OSI model, and it defines the means
for host-to-host logical addressing across a network. In the OSI model, it
is immediately above the data link layer.
NIC: NIC stands for network interface card, which is the hardware interface
that provides the physical link between a computer and a network.

336 Tarnoff
Octet: An octet is a sequence of eight bits. The term octet is preferred over byte
because the term byte has become ambiguous, oftentimes referring to the
number of bits reserved for a character.
Preamble (Ethernet): This is a string of 56 alternating binary ones and zeros
(starting with a one) that is sent at the beginning of an IEEE 802.3 Ethernet
frame.
Protocol: A protocol is a set of strict definitions for the transmission of data from
one device to another across a communications network.
OSI model: This is a model for the operation of computer interfaces. It divides
the needs of computer communication into levels and details what needs to
be defined at each of these levels for a successful interface.
Start delimiter (Ethernet): This is an octet immediately following the pre-
amble of the IEEE 802.3 Ethernet frame that indicates the message starts
at this point. It is always a binary pattern equal to 10101011.
Transport layer: This is the fourth layer of the OSI model, immediately above
the network layer. It provides a network-independent mechanism for
sending large blocks of data, thereby hiding the details of the network from
the services in the layers above it.
Review Questions
1. List and describe three desirable features of a protocol analyzer.
2. Explain how a protocol analyzer can be used in teaching and learning
contexts.
3. Explain how data link layer frames and network layer packets can be
examined by a protocol analyzer.
4. Explain how data packets can be captured by a protocol analyzer.
5. Define the following key terms: serial communication, frame, and protocol
stack.
6. Draw a block diagram to illustrate the layout of an IEEE 802.3 Ethernet
frame.
7. Describe the IEEE 802.3 Ethernet frame structure.
8. Discuss the difference between a MAC address and an IP address.
9. Draw a block diagram to illustrate the layout of an IP packet header.
10. Draw a block diagram to illustrate the layout of a TCP packet header.

References
IEEE Computer Society. (2002). Carrier Sense Multiple Access with Colli-
sion Detection (CSMA/CD) access method and physical layer specifi-
cations (IEEE Standard 802.3-2002). Retrieved December 14, 2004, from
the Institute of Electrical and Electronics Engineers Web site: http://
standards.ieee.org/getieee802/download/802.3-2002.pdf
OPENXTRA Limited. (2003). Packetyzer user guide [Computer manual].
West Yorkshire, UK: Author.
Postel, J. (1981a). Internet Protocol: DARPA Internet program protocol
specification (RFC 791). Arlington, VA: Defense Advanced Research
Projects Agency. Retrieved May 27, 2005, from the Advameg Inc. Web
site: http://www.faqs.org/rfcs/rfc791.html
Postel, J. (1981b). Transmission Control Protocol: DARPA Internet program
protocol specification (RFC 793). Arlington, VA: Defense Advanced
Research Projects Agency. Retrieved May 27, 2005, from the Advameg
Inc. Web site: http://www.faqs.org/rfcs/rfc793.html
Stallman, R. (2002). Releasing free software if you work at a university.
Retrieved May 27, 2005, from the GNU Project Web site: http://
www.gnu.org/philosophy/university.html
Waters, C. (2003). Packetyzer—Network Packet Analyzer (Version 4.0.0)
[Computer software]. Menlo Park, CA: Network Chemistry. Retrieved
May 26, 2005, from the SourceForge.net Web site: http://sourceforge.net/
projects/packetyzer

338 Correia & Watson
ChapterXVIII
VMware as a Practical
LearningTool
Eduardo Correia, Christchurch Polytechnic
Institute of Technology, New Zealand
Ricky Watson, Christchurch Polytechnic
Institute of Technology, New Zealand
Abstract
Providing a dedicated lab to each group of students in order to gain hands-
on learning experience is not always possible due to budget and space
constraints. For example, in one class of 20 students, each student requires
at least three computers with each computer capable of running three
operating systems, such as UNIX, Linux, and Windows Server 2003. This
requires a large computer laboratory with 60 computers in total. In
addition, it is difficult to manage the laboratory to accommodate students
from other classes. For example, once one class leaves the laboratory,
another class of 20 students needs to start immediately with each person
configuring Windows Server 2003 Active Directory on four computers. This
requires another large computer laboratory with 80 computers. This
chapter presents VMware as a teaching and learning tool to overcome the
problems mentioned above. Under VMware, students do not require
administrative privileges on physical machines. Consequently, they have
complete freedom to experiment within their own virtualised environments.

VMware as a Practical Learning Tool 339
Learning Objectives
• Discuss the usefulness of VMware in teaching and learning contexts.
• Use VMware in laboratory settings for hands-on learning experience.
• Define the following key terms: DHCP, ISA, NTFS, RIS, VMware, and
Virtual PC.
• Suggest further enhancements to the practical activities presented in the
chapter.
Introduction
VMware is an application that emulates a hardware environment. It allows one
or more virtual machines (guests) to run on one physical machine (host). On top
of the existing operating system of the physical machine, one or more operating
systems can run in this environment, including any of a number of Microsoft
operating systems, Linux distributions, Netware, Solaris, or variants of BSD.
These systems running within VMware behave, with only a few exceptions, in
exactly the same way as any other conventional system (Stockman, 2003). What
VMware does is to “carve a single physical system into compartments, each
running its own copy of an operating system, applications and content in the
illusion that it is a complete, independent machine” (Deane, Haff, & Enuice,
2004). This partitioning of a system through the use of VMware has several
distinct benefits for teachers of computer studies; notably, the ability to:
a. provide a richer learning environment,
b. offer a safe environment for learners,
c. exploit powerful and flexible networking options,
d. employ cost-effective solutions that scale well, and
e. simplify the administration of the learning environment.
Some of the technology students are exposed to through VMware would simply
not be practicable through conventional means because of the prohibitive cost of
additional hardware and the physical space and maintenance it would entail.

How else can one easily give 20 students each three computers running UNIX,
Linux, and Windows Server 2003 and allow them to configure these machines
as part of one larger network (60 computers in total)? And what if, once one class
leaves, another class of 20 students needs to start immediately with each person
configuring Windows Server 2003 Active Directory on four computers (80
computers in total)? VMware makes this practically feasible. What is more,
students do not require administrative privileges on physical machines to be able
to have complete freedom to experiment within their own virtualised environ-
ments.
This chapter describes how the authors came to adopt VMware and the specific
feature sets of value for its use as a learning tool, such as networking capabilities
and virtualised/real media support as well as some key infrastructural consider-
ations. More importantly, it outlines how this tool can be employed to enhance
teaching and learning through the use of specific tasks and practical project
work.
Motivation for Using
VMware as a Learning Tool
In 1998 the School of Computing at the Christchurch Polytechnic Institute of
Technology (CPIT) decided to offer a course on managing Windows NT4
Workstation. The IT Division at CPIT was asked to provide a solution that
allowed the school to use machines both for normal classes as well as specialist
operating systems classes, which require full access to the operating system.
After evaluating a number of options, the IT Division recommended that Iomega
JAZ drives be used, which we did. Unfortunately the solution failed. With no
other workable solution, the course made use of the existing installed system with
mixed and somewhat unsatisfactory results. In an attempt to improve the system,
the IT Division provided each machine with multiple partitions. While this
solutionofferedbetterresults,ithadsignificantlimitationsandpotentialproblems
for normal classes. Any student could see and in fact destroy another student’s
work or even destroy the operating system installed by the IT Division for normal
classes. Furthermore, the number of students that could use the machine was
limited to the number of available partitions. One of the authors then decided to
investigate the use of VMware as a potential solution for running Windows NT4
in emulation on a Linux host system. In 2001 he decided to use VMware (at that
time Version 2) specifically for the teaching of Windows NT4 and Linux.
However, the hardware had to be upgraded to make it suitable for teaching

Windows 2000. Each machine had 384 MB of memory, a 20 GB disk partitioned
into 4 GB and 14 GB, the latter reserved for storing virtual machines. With the
increase in demand for courses utilising Microsoft Official Curriculum, a
specialist network called Techlabs was established. While initially this specialist
network was created primarily for the purposes of teaching Microsoft operating
systems and networking, it also caters for courses that require students to work
extensively with a number of other platforms, including Linux, Netware, and
BSD.
Feature Sets of Benefit for Learning
VMware is available as three separate products that essentially all do the same
thing: offer users the ability to run numerous virtual machines that may or may
not be connected to one another and to other physical and/or virtual machines on
the network. The three VMware products are:
a. VMware ESX Server. VMware ESX Server has a number of advanced
features, including the ability to migrate virtual machines to another location
without them needing to be powered down. It makes use of a custom Linux
kernel and has a limited hardware compatibility list so as to ensure stability.
It is really an enterprise server application with a price tag to match that is
difficult to justify in an educational institution.
b. VMware GSX Server. VMware GSX Server provides a remote console
that is essentially a terminal to the virtual machines running on the physical
server. These sessions with the server can be started and terminated
without the virtual machines themselves being affected.
c. VMware Workstation. VMware Workstation provides the basic function-
ality of virtual machines, but as soon as a user logs off the physical machine
or closes the VMware dialog box, the virtual machine stops running.
In a specialist teaching network, VMware Workstation allows students to create,
change, and even destroy (if they wish) their own virtual machines while
VMware GSX Server allows teaching staff to make running virtual machines
available to all students. Used together these two products are capable of
providing a learning environment that is highly flexible, scalable, and feature-
rich.

Features common to all three VMware products include:
a. Virtual switches, allowing for up to 10 different isolated networks, from
VMnet0 to VMnet9 (see Figure 1).
b. Physical network adapters in the host can be assigned to a virtual switch,
allowing virtual machines access to a physical network.
c. Special networks to help create useful scenarios. VMnet1 is a network for
just the virtual machines and the host to communicate; whereas, VMnet8
allows virtual machines to use network address translation (NAT) to obtain
a private network address and interact with the physical network via the
host’s network address.
d. Each virtual machine can have up to three network adapters assigned, but
this can be extended to more.
e. Each virtual network has a server running Dynamic Host Control Protocol
(DHCP) to issue addresses. The scopes can be reconfigured or the DHCP
server disabled.
f. Each machine can accommodate a limited range of hardware, including
disk drives, compact disc drives, Universal Serial Bus (USB) controllers,
sound cards, floppy disk drives, parallel ports, serial ports, and network
cards (see Figure 2).
Figure 1. VMware network configuration

As in the case of physical machines, students may start out with a particular
hardware configuration and then decide to change or upgrade it later. A virtual
machine that initially has just one hard disk drive and one network card may have
five hard disk drives and three network cards added to it. Students may therefore
be given the task of adding a number of virtual SCSI disks and may set up a
redundant array of independent disks with parity (RAID 5). This rich learning
environment is supported by a set of powerful networking features. While one
or more VMware virtual machines may run simultaneously on a single physical
machine, they appear just like any other machine on the network (Hu, Meinel, &
Schmitt, 2004); though if one wishes, it is easy to ensure that no other machine,
virtual or physical, can see or access it. This is because each virtual machine can
have one or more network interfaces that may or may not be connected to the
same virtual switch. This is a feature that has great value for learning because
each student can run a DHCP server and DHCP client simultaneously and test
this without disrupting what anyone else is doing or even the activities of another
virtual machine running on the same hardware. Similarly, for project work it is
possible to provide students with a server that is configured up to a certain point
and only require them to complete certain specified tasks, making learning a
smoother, more efficient process. Students do not waste time on installation
issues, unless of course the project is designed to deal specifically with
installation.
Figure 2. VMware add hardware wizard

In the course of installing, configuring, maintaining, and troubleshooting systems,
people may easily corrupt an entire system. In a VMware environment, learners
can easily undo major operations that would normally be impractical to reverse,
actions such as deleting partitions and creating file systems. This risk can be
significantly reduced through the use of VMware because it is possible to:
a. keep an additional copy of the entire virtual machine, which involves simply
copying a few files to another location; and
b. utilise the snapshot feature of VMware that allows someone to revert to the
state of a system at a particular point in time.
This snapshot is comparable to making a number of transactions to a database
and deciding only later whether or not to commit the changes. It is a feature that
was initially harnessed by developers (Zeichick, 2004), but its benefits have been
widely recognised by both individuals as well as organisations, such as Microsoft
and Novell (VMware, 2004).
VMware also reduces and simplifies the administration of course setups and
makes disaster recovery as simple as copying a particular folder and its files. As
virtual machines are simply a collection of files on a computer, it is possible to
provide students with “clean” virtual machines that they can copy but not
change. Because they can change their own copies of the virtual machines, if
they do corrupt their own classroom machines, it is possible to revert to the
original machine by making a copy of it. This means that the classroom only
needs to be set up once for a particular course, as all subsequent instances of that
course make use of the same original set of virtual machines, which once
students copy they have full control over. This is cost-effective because setup
time and maintenance of course machines are greatly reduced, and it is easy to
back up and restore entire systems. It is also a cost-effective solution because
in a typical learning (non-production) environment, physical machines made
available to students are not serving many clients, if at all. As a particular
computer may be running multiple virtual machines simultaneously, more effi-
cient use is made of existing hardware resources.
Practical Project Work Using VMware
VMware is a valuable tool for learning, where the application of practical skills
can be as important as theoretical knowledge. As part of course requirements,
students may be given practical projects that require the installation, configura-

tion, and maintenance of a number of systems that, for example, may involve
Windows Server 2003, Windows XP Professional, Linux, and Netware. In one
project that requires basic administration and configuration of objects in Active
Directory, students are provided with a fully built virtual system that requires
them only to create stated users, groups, printers, and volumes and enhance
performance. This is simply a matter of making a domain controller available on
a network location for them to copy and then configure. As students do not need
to make this domain controller connect with any other student’s machine, there
is no requirement to subject this machine to the process of the System
Preparation Tool (Sysprep). In order to enhance the performance of their
systems, students can add an extra virtual disk and move their directory database
log files to this new volume. In a subsequent project they use the server of the
previous project to configure folder and file permissions, then are given a virtual
XP Professional machine to test whether different users have no more and no
less than the requisite permissions. Students can find that they have not
completed this task properly because even if they have configured the NT File
System (NTFS) permissions, they may have overlooked configuring the share
permissions, and in Windows Server 2003 these are “Everyone—Read Only.”
In this way a second project may expand on the first and grow from one machine
to two, without the costs and complexity of supporting additional hardware.
To implement routing, students require more than just one machine if they are to
be given anything more than a fleeting opportunity to learn and practise
networking skills. Multiple machines offer the prospect of gaining something akin
to real-world experience, since there is little difference between using virtual or
physical machines in such a way. As one can see in Figure 3, the student
workstation is host to three virtual machines and three subnets: client1 (a
Microsoft NT4 Workstation on VMnet 4), client2 (a machine with Debian Linux
3 on VMnet 5), and a Linux server (with Debian Linux 3 on VMnet 4, VMnet 5,
and VMnet 2). The Linux server routes between the two clients as well as
between the clients of a student and clients of other students through VMnet 2.
The students can use static routing and managed routing using the provided
configuration.
In a similar, though more elaborate project, students configure four Microsoft
Windows Server 2003 routers first using static routes and then Routing Informa-
tion Protocol (RIP; see Figure 4). The four routers are said to be located in
Auckland, Wellington, Christchurch, and Invercargill, and students add routes
and verify connectivity between all four devices. In addition students also
configure a backup route. Normally the router in Invercargill is connected to
Wellington, but should this link drop for some reason, a backup route should
automatically connect to Christchurch; but as Invercargill should normally route
to Wellington, this requires the configuration of costs to individual routes. All four
routers have access to the Internet through the router in Auckland, and this router

is configured with NAT. In fact, students are able to add an interface on the
Auckland router that will have a default gateway of another machine on the
network that provides access to the Internet. As a result all routers should be able
to ping a public address on the Internet.
A course titled Fundamentals of Security includes a project that utilises the host
machine as well as four virtual machines: FW1, FW2, SQL, and WEB (all have
Windows 2000 Advanced Server installed; see Figure 5). This virtual network
implements the typical scenario of a perimeter network using two firewalls (FW1
and FW2), a Demilitarized Zone (DMZ), and a client. FW2 separates the Web
from the internal trusted network, which contains a Structured Query Language
(SQL) database server. FW1 and FW2 need to have properly configured packet
filters so that someone can access the Web server (WEB) from WinXP, and this
Web server will be able to fetch data from the SQL server while not allowing
traffic from untrusted sources into the internal network.
Other projects are designed to utilise as many as nine machines, including the
physical host machine, so that students can create two entire networks,
Developmentum and Fabrikim, each with its own Internet Security and Accel-
eration Server (ISA) firewall and one with an ISA 2000 Proxy Array (see Figure
6). The two networks should be connected by demand-dial interfaces that
automatically create a VPN connection between them when a client from one
Figure 3. Routing with Linux
Student Host Machine
VMnet4
VMnet5
VMnet2
SERVER
LINUX
Vmnet2(172.19.67.x)
VMnet4(192.168.x.1/24)
VMnet5(192.168.100+x.1/24)
CLIENT1
WinNT4
VMnet4(192.168.x.2/24)
CLIENT2
LINUX
VMnet5(192.168.100+x.2/24)

network connects to a resource on the other network. The student host machine
is used to connect to the resources on either network, using either Point-to-Point
Tunnelling Protocol or Layer 2 Tunnelling Protocol.
To avoid problems and disappointment, teaching staff need to be prepared for the
challenge of using VMware. Firstly, it does add to students’ initial workload as
they need to familiarise themselves not only with the content of the course but
also understand how to make use of this mode of virtualisation. Secondly,
VMware has its limits with regard to unsupported operating systems, unusual
hardware access, or specific configurations. Not all operating systems are
supported, and even the ones that are, cannot do absolutely everything a physical
machine can. For example, virtual machines do not run easily within virtual
machines (Lorincz, Redwine, & Sheh, 2003). VMware also does not always
cope well with nonstandard-size floppy disks and power management options,
such as standby and hibernation (Correia & Watson, 2004). It has also been
found to give intermittent problems with both the Windows 2000 Server and
Figure 4. Routing with MS Windows
Backup Route
Internet 1
0
.
2
0
1
.
5
.
0
/
2
4
INV
CHC
AUK
172.17.x.y
1
0
.2
0
1
.3
.0
/2
4
10.201.4.0/24
1
0
.
2
0
1
.
2
.
0
/
2
4
WELL
10.100.1.0/24
10.100.2.0/24
10.100.3.0/24
1
0
.
1
0
0
.
4
.
0
/
2
4

Figure 5. Security project
Figure 6. ISA project with tunnel-mode VPN
Fabrikim
ISA2000 PROXY ARRAY
DC-CHC-01
W2KAS,DC,DNS,DHCP,CA
VMnet4(10.0.1.1/16)
FW-CHC-01
W2KAS,ISA,FIREWALL
VMnet4(10.0.0.1/16)
NMnet2(172.19.67.140+#/24)
FW-WLG-01
W2KAS,ISA,FIREWALL
VMnet5(192.168.0.1/24)
VMnet2(172.19.67.100+#)
PY-CHC-01
W2KAS,ISA,PROXY
VMnet4(10.0.1.2/16)
PY-CHC-02
W2KAS,ISA,PROXY
VMnet4(10.0.1.3/16)
PY-WLG-01
W2KAS,ISA,PROXY
VMnet5(192.168.0.1/24)
Developmentum
Client
WinXP
VMnet4(10.0.2.1/16)
Client
WinXP
VMnet2(DHCP)
VMnet4
VMnet2
Client
WinXP
VMnet5(192.168.0.3/16)
VMnet5
FW2
W2KAS, RRAS
VMnet4(192.168.0.2/24)
VMnet5(192.168.1.1/24)
FW1
W2KAS, RRAS
VMnet4(192.168.0.1/24)
VMnet2(172.19.67.100+x/24)
SQL
W2KAS, SQL, CA, IIS
VMnet5(192.168.1.2/24)
WEB
W2KAS, IIS
VMnet4(192.168.0.3/24)
Student Host Machine
WinXP
VMnet2(DHCP)
VMnet4
VMnet5
VMnet2

Windows Server 2003 versions of Remote Boot Disk Generator (rbfg.exe),
which creates floppy disks used to connect client machines with a Remote
Installation Service (RIS). VMware now offers the alternative of PXE boot
functionality, so that virtual machines can boot off their network cards to connect
with the RIS server, just as one can with many current network interface cards.
VMware is also not ideal for performance testing, as any one individual virtual
machine is not aware that it is sharing resources with both other virtual machines
as well as the host system (Zeichick, 2004). In reality these issues are only rare,
isolated instances of a technology that is remarkably flexible and powerful as a
learning tool. Such issues can be expected to be resolved in the future.
Infrastructural Considerations
VMware places significant demands on hardware and as a result demands
newer, well-resourced machines. Virtual machines require hardware resources
comparable to physical machines. For example, a Windows Server 2003
machine runs best when it has at least 128 MB of RAM and requires the same
amount of memory under VMware. These are important considerations; other-
wise, virtual machines will be unstable, run very slowly or not run at all. Older
hardware is often not suitable because it is simply not sufficiently powerful to
host multiple operating systems and cope with the demands made on CPU, disk,
and memory. An important factor is whether one needs to run more than one
virtual machine at a time and precisely what systems are required; for example,
Windows Server 2003 with Exchange Server 2003 needs at least 512 MB of
RAM to run satisfactorily, whereas a Debian Linux machine does not need
anything more than 128 MB of RAM and can perform well with considerably
less. As new computers are obtained, they are better able to cope with the
demands made by virtual machines in VMware, and the constraints imposed by
particular hardware are reduced. More powerful hardware ultimately enables
more virtual machines to run simultaneously, including servers that require
significant hardware resources, such as Exchange.
An extensive physical infrastructure is required in order to extract the greatest
benefits from VMware as a learning tool. One important consideration is the
specifications of a typical host machine and network configuration. Virtual
machines are best placed on cabling and switches entirely separate from the
physical machines that host them. Access permissions must be carefully applied
through the operating system of the physical machine so that students’ virtual
machines can only be accessed by the owner of the virtual machine, the tutor and
anyone else the tutor deems necessary to have access to a particular virtual

machine. Virtual machines used in class are simply copies, so that in a worst-
case scenario, students can revert to the original clean machine, to which they
have read access, if necessary. Also, students can easily take copies of virtual
machines so that they can continue to work on them on their own computers at
home.
Techlabs stores hundreds of virtual machines that are required for classes.
These class machines are all protected by means of NTFS permissions, and
processes have been developed to restore these quickly and easily. However, the
students’ machines are not backed up, as it is not feasible to do so for the over
1,000 virtual machines students create on their workstations for the purpose of
completing practical projects. As one virtual machine can be over 2 GB in size,
it is too expensive and time-consuming for the institution to make adequate
backups of all virtual systems. As a result, students are informed that they are
responsible for their own project machines and advised to store them on
removable media, such as external USB hard drives, or at the very least to
regularly place copies on digital video/versatile disc (DVD). This is not entirely
satisfactory, but there is some value to students learning to back up their own
work and to feel the pain of wasted hours if they do not!
Conclusion
Virtualisation software such as VMware, Virtual PC, and User Mode Linux
(McEwan, 2002) makes it feasible to offer every learner the practical experience
of making systems work. It allows people to learn by doing, so that when they
configure their virtual machines they understand the technology and see for
themselves how it behaves on a particular platform. This tool allows students to
gain experience in technologies that would otherwise be too expensive to make
widely available using conventional physical hardware, such as RAID arrays or
making an entire network available. It has now been used extensively for a
number of years in Techlabs and earlier networks in a wide range of computing
courses. At first it was applied tentatively, but its role has expanded over time,
so that now it is essential for exploring a variety of systems and networks in a
safe learning environment. Of itself it gives rise to a few problems and imposes
some constraints, but these are insignificant compared to the benefits.
VMware transcends the traditional constraints of hardware solutions and helps
overcome the challenges of rapid technological change in software and hard-
ware. This has led many vendors to exploit virtualisation to port legacy
applications to new hardware or to provide cost-effective server redundancy, in
terms of both operating system and data. The additional layer of VMware does

add overhead that may reduce the performance of both host and guest machines,
but most people using this technology agree that “The benefits of successful
virtual machine systems far outweigh any overhead that they introduce”
(Rosenblum, 2004). For courses in operating systems, programming, and net-
working, VMware enhances learning through doing and in this way infuses
virtual technology with real meaning and purpose.
Summary
Due to budget constraints, it is not always possible to provide a dedicated lab to
each group of students for hands-on learning experience. For example, one class
of 20 students requires at least three computers with two or more operating
systems (e.g., UNIX, Linux, and Windows Server 2003) each. This requires a
large computer laboratory with 60 computers in total. And what if, once one class
leaves, another class of 20 students needs to start immediately with each student
configuring Windows Server 2003 Active Directory on four computers (80
computers in total)?
This chapter described the use of VMware in teaching and learning contexts to
overcome the above-mentioned problems. Under VMware, students do not
require administrative privileges on physical machines to be able to experiment
within their own virtualised environments.
Some of the technology students are exposed to through VMware would simply
not be practicable through conventional means because of the cost of additional
hardware, physical space, and maintenance it would entail.
DHCP: Dynamic Host Control Protocol is used to issue and obtain IP addresses,
both on local area networks and wide area networks.
Exchange: Exchange Server 2003 is Microsoft’s latest mail server and as an
enterprise server application requires significant resources in terms of
processor, RAM, and disk space.
ISA: Internet and Acceleration Server is Microsoft’s firewall and proxy server
application. It followed Proxy Server 2.0 and was released in its first
version in 2000. Another version was released in 2004.

NTFS: The NT File System is Microsoft’s most secure file system and is as a
result supported by Windows NT, Windows 2000, Windows XP, and
Windows 2003 operating systems.
PXE: Preboot Execution Environment is a way of booting off the network card
in order to connect to a server on the network.
RAID 5: A redundant array of independent (or inexpensive) disks, level 5 is a
way of employing at least three disks in combination for the purpose of
performance and fault tolerance.
Remote Boot Disk Generator: The Remote Boot Disk Generator is a tool that
allows users to easily produce floppy disks that can connect a client
machine with a RIS server.
RIS: Remote Installation Service is a service that can be installed on a Windows
2000 Server or Windows Server 2003 for the purpose of deploying, usually
in an automated fashion, various Microsoft operating systems to client
machines.
SQL: While SQL refers to Structured Query Language, this chapter refers to
SQL as Microsoft’s well-known database application.
Sysprep: Microsoft’s System Preparation Tool is a utility for the mass deploy-
ment of the Microsoft NT family of operating systems.
USB: Universal Serial Bus is a standard that supports Plug and Play and is used
for connecting peripheral devices to a PC.
User Mode Linux: User Mode Linux is an open source product that does the
same kinds of things as VMware but unlike VMware is limited to Linux
systems.
Virtual PC: Virtual PC is Microsoft’s commercial product that competes
directly with and is comparable to VMware.
VMware: VMware is a commercial product that allows one simultaneously to
run a number of systems within the context of this application.
Review Questions
1. List and describe three main features of VMware.
2. List and describe three main benefits of using VMware in laboratory
settings.
3. Define the following key terms: DHCP, ISA, NTFS, RIS, and Remote Boot
Disk Generator.

4. Describe the usefulness of VMware in teaching and learning contexts.
5. List and describe three potential limitations of VMware.
6. List and describe possible enhancements to the practical activities de-
scribed in this chapter.
References
Correia, E., & Watson, R. (2004). A virtual solution to a real problem: VMware
in the classroom. In Conference Proceedings: Papers from the Pro-
ceedings of the 17th NACCQ (pp. 250-253).
Deane, T., Haff, G., & Enuice, J. (2004, August 9). VMware on the march.
Retrieved December 13, 2004, from http://www.VMware.com/pdf/
illuminata.pdf
Hu, J., Meinel, C., & Schmitt, M. (2004, March). Tele-Lab IT security: An
architecture for interactive lessons for security education. In SIGSE
Technical Symposium on Computer Science Education.
Kneale, B., de Horta, A. Y., & Box, I. (2004, January). Velnet (virtual
environment for learning networking). In R. Lister & A. Young (Eds.),
Sixth Australasian Computing Education Conference (pp. 161-168).
Lorincz, K., Redwine, K., & Sheh, A. (2003). Stacking virtual machines—
VMware and VirtualPC. Retrieved March 6, 2004, from
www.eecs.harvard.edu/~konrad/References/notes/CS253-VMware-
Report.pdf
McEwan, W. (2002). Virtual machine technologies and their application in the
delivery of ICT. In Proceedings of 15th annual Conference of the
NACCQ (pp. 55-62).
Rosenblum, M. (2004, July/August). The reincarnation of virtual machines:
Virtualization makes a comeback. ACM Queue, 2(5).
Shankland, S. (2001). Novell tows VMware into education market. Retrieved
March 7, 2004, from http://news.com.com/2102-001_3268219.html
Stockman, M. (2003, October). Creating remotely accessible ‘virtual networks’
on a single PC to teach computer networking and operating systems. In
Proceedings of the 4th Conference on Information Technology Cur-
riculum.
VMware. (2004). VMware partners with Novell to provide innovative
training solution. Retrieved March 27, 2004, from http://
www.vwware.com/news/releases/novell.html

Zeichick, A. (2004, September 28). VMware: The virtual desktop, the virtual
server. AMD64 dev Source. Retrieved December 12, 2004, from http://
www.devx.com/amd/article/22036

Appendix Section 355
AppendixSection
Appendix A
Useful Tools
Tool Description URL
WebLan-
Designer
A Web-based tool for teaching and learning
both wired and wireless LAN design.
http://elena.aut.ac.nz/homepages/w
eblandesigner/
JASPER JASPER (Java Simulation of Protocols for
Education and Research) is a protocol
simulator suitable for teaching and learning
communication protocols.
http://www.cs.stir.ac.uk/~kjt/softwa
re/comms/jasper
Colligo
Workgroup
Colligo software allows interactive chat,
unidirectional message delivery, virtual
whiteboard, and file transfer. The software
can be downloaded from the Web site.
http://www.colligo.com/products/w
orkgroupedition/
Animation
Tool
Algorithm animations. www.cs.auckland.ac.nz/software/Al
gAnim/alg_anim.html
Logisim Logisim is a Java application that can run
on both MS Windows and Unix
workstations.
http://www.cburch.com/proj/logisi
m/
Wi-Fi Projects List of equipment for setting up Wi-Fi
projects.
http://elena.aut.ac.nz/homepages/sta
ff/Nurul-Sarkar/wifi/
Wi-Fi Antenna Various kits for Wi-Fi antenna can be
found at the Oatley Electronics Web site.
http://oatleyeelectronics.com/kits/K
199.html

356 Appendix Section
Tool Description URL
Assistant Tool A tool for instructors teaching computer
hardware fundamentals with the PBL
theory.
http://maiga.dnsalias.org/PBL/tools
/feedback.htm
WinLogiLab WinLogiLab is can be used as an aid to
enhance teaching and learning digital logic
design concepts.
http://www.gu.edu.au/school/eng/m
mt/MMTdownlds.html
SIGCSE
Education
Links
Various tools and computer science course
materials are available through SIGCSE
Education Links.
http://sigcse.org/topics/
CSTC Links Various teaching materials for computer
science education.
http://www.cstc.org/
Appendix B
A Table of Power of 2
Number Power of 2 Number Power of 2
0 1 21 2,097,152
1 2 22 4,194,304
2 4 23 8,388,608
3 8 24 16,777,216
4 16 25 33,554,432
5 32 26 67,108,864
6 64 27 134,217,728
7 128 28 268,435,456
8 256 29 536,870,912
9 512 30 1,073,741,824
10 1,024 31 2,147,483,648
11 2,048 32 4,294,967,296
12 4,096 33 8,589,934,592
13 8,192 … …
14 16,384
15 32,768
16 65,536
17 131,072
18 262,144
19 524,288
20 1,048,576

Appendix Section 357
Appendix C
Binary Coding Schemes
A computer uses a coding scheme to represent characters. The widely used
coding schemes are ASCII, EBCDIC, and Unicode.
Code Description
ASCII The American Standard Code for Information Interchange
Original ASCII 7-bit
Extended ASCII is 8-bit (including parity bit)
EBCDIC Extended Binary Coded Decimal Interchange Code
8-bit code used mainly IBM mini and mainframe computers
Unicode A new 16-bit code, supports many different languages (including English)
Character ASCII EBCDIC
A 01000001 11000001
B 01000010 11000010
C 01000011 11000011
D 01000100 11000100
E 01000101 11000101
F 01000110 11000110
G 01000111 11000111
H 01001000 11001000
I 01001001 11001001
J 01001010 11010001
K 01001011 11010010
L 01001100 11010011
M 01001101 11010100
N 01001110 11010101
O 01001111 11010110
P 01010000 11010111
Q 01010001 11011000
R 01010010 11011001
S 01010011 11100010
T 01010100 11100011
Appendix D
Example of ASCII and EBCDIC Coding

358 Appendix Section
Character ASCII EBCDIC
U 01010101 11100100
V 01010110 11100101
W 01010111 11100110
X 01011000 11100111
Y 01011001 11101000
Z 01011010 11101001
# 00100011 01111011
$ 00100100 01011011
% 00100101 01101100
& 00100110 01010000
Note: For all other characters and numbers, please refer to the ASCII and
EBCDIC tables available in computer hardware textbooks.

Glossary 359
Glossary
A
Access point (AP): AP stands for access point. Typically, infrastructure-based
wireless networks provide access to the wired backbone network via an
AP. The AP may act as a repeater, bridge, router, or even gateway to
regenerate, forward, filter, or translate messages. All communication
between mobile devices has to take place via the AP.
Ad hoc network: A class of wireless network architecture in which there is no
fixed infrastructure or wireless access points. In ad hoc networks, each
mobile stations.
Animation: The abstract execution of a system model. The terms animation
and simulation are barely distinguished, though animation has the sense of
symbolic execution while simulation has a more general sense and may deal
with performance.
ARP: Address Resolution Protocol is used to translate between IP addresses
and hardware addresses. There is an arp utility found on both Microsoft and
UNIX operating systems which can be used to view and modify the ARP
cache.
Assets: Valuables of an organization which need to be protected.

360 Glossary
B
Boolean expression: An expression which results in a Boolean (binary or
TRUE/FALSE) value. For example 4 > 3 is a Boolean expression. All
expressions that contain relational operators like >, <, and so forth are
Boolean. Logical gates and their combinations are used to implement
physical representations of Boolean expressions.
Brainstorm map: A brainstorm map and discussion can improve students’
creative thinking and critical reasoning, communication, cooperation, and
decision-making skills and provide students with various viewpoints. Stu-
dents record their thoughts regarding what they already know and what
they need to know on a brainstorm map.
Broadcast domain: Devices attached to the network that each receive a
broadcast packet sent from any of these devices are said to be in a
broadcast domain.
Bus contention: This is an erroneous condition that occurs when multiple
devices attempt to put data on the data lines of the bus at the same time.
C
Cache: A small fast memory which stores recently used values so that they can
be accessed faster than the bulk memory behind it.
Cases: Abstraction of real problems that are used for training purposes.
Colligo software: A commercial software package that allows users to run
collaborative applications such as interactive chat, unidirectional message
delivery, virtual whiteboard, and file transfer.
Collision: When two or more packets are simultaneously sent on a common
network medium that only can transmit a single packet at a time. The
packets collide and are corrupted and need to be resent.
Collision domain: A single physical or logical network segment using Ethernet
technology through which collisions will be propagated. Devices in a
collision domain communicate directly with each other and share the
network medium.
Computer hardware: Generally refers to electronic, electrical, and mechanical
components that make up a computer.
Concept map: A concept map is a knowledge representation commonly used
in education. It is a graphical node-arc representation illustrating the
relationship among concepts.

Glossary 361
Concrete: Something that involves the immediate experience rather than an
abstraction. A “concrete learner” is someone who prefers learning prima-
rily through hands-on activities rather than by studying a theoretical model.
Constructivism: A theory of learning which regards learning as a process of
developing knowledge through the construction and reconstruction of
concepts and ideas, providing learners with motivation, and supporting self-
directed learning.
Controls: Implementations for reduction of risk and vulnerability.
Cooperative learning: Cooperative learning focuses on student interaction.
Cooperative learning exposes students to different perspectives that can
enrich their understanding. Cooperative learning can enhance critical and
reasoning skills and improve tolerance of and willingness to adopt new
concepts.
CRC: CRC stands for cyclic redundancy check. This is a method for checking
for errors in a data stream. It uses a polynomial (a pattern of ones and zeros)
as a divisor in a modified division of the entire data stream. The remainder
of the division is appended to the message along with the data to be used
as a verification by the receiver of the data stream.
Cross-development: The process of using software development tools like
compilers, linkers, and debuggers which are resident on a reprogrammable
computer to produce executable programs for an embedded computer
system. The executable programs must then be transferred from the
reprogrammable computer (called the development system) to the embed-
ded computer (called the target system) for testing.
Cycle-accurate: A simulator which models the operation of a processor on a
cycle-by-cycle basis so that the state of the processor at the end of each
cycle is correct.
D
Daisy-chaining: This is a configuration that connects the inputs of multiple
devices together using a single conductor.
Data acquisition: The discipline of sampling signals from the physical world so
that the data can be analyzed or processed by a computer.
Data link layer: This is the second layer of the OSI model, and it defines the
pattern or purpose of the bits of a frame. Except for the physical layer,
which defines the electronics behind a computer interface, it is the lowest
level of the OSI model.

362 Glossary
Data path: The main path along which data flows in a processor; usually extends
from an instruction fetch unit to a result write-back one.
Datagram: A datagram is a block of data meant to be treated as a unit. If the
datagram is too large to be handled by a network, it is possible to fragment
it for transmission into smaller packets.
Deep learning: The process by which a person comes to achieve a critical
awareness of a particular item of information or an idea as well as how this
information can be used in the real world, why it should be used, in what
ways and what situations it is applicable, and its relationship to other
matters.
Device interface: Sometimes referred to as a transducer, it is the circuit
element that converts physical phenomenon to electrical signals and
eventually to digital values readable by the processor.
DHCP: Dynamic Host Control Protocol is used to issue and obtain IP addresses,
both on local area networks and wide area networks.
Digital logic probe: A simple test device that is used to sense whether a binary
one or a binary zero is present on a digital conductor.
DLL: Stands for dynamic link library. This is a library of functions that are
available to the applications of an operating system at runtime. They are not
required to be part of the compile process, rather they are loaded as needed
when the application is executed.
DNS: The domain name system is a service used to map between hostnames and
IP addresses and allow for resolution of hostnames to IP addresses.
Dynamic loading: The ability of a system to load additional software compo-
nents (e.g., Java classes) as it executes.
Dynamic routing: A form of routing in which the routes that packets take in a
network are able to change as a function of time. The routes can change
as a result of node or link failures or as a result of node or link characteristics
(speed, cost, etc.), including the volume of traffic that is currently being
serviced.
E
EEPROM: EEPROM stands for electrically erasable ROM. This type of
memory differs from ROM in that the contents can be changed if suitable
voltages are applied to the memory chip.
Embedded computer system: Computers that are comprised of a processor
(microprocessor or microcontroller), memory, and I/O devices that are

Glossary 363
“special purpose” in that they are tightly coupled to or even architecturally
a component of other systems with which they interact. Their primary I/O
devices are usually not human-user-centric. Examples are regulators and
controllers in domestic appliances and automotive systems, negative feed-
back automatic control systems in the chemical process industries, and
autopilots for ships and aircraft.
Ethereal: An open source implementation of a packet sniffer. Available freely
at http://www.ethereal.com.
Ethernet: A popular LAN technology that uses a shared channel and the
CSMA/CD access method. Basic Ethernet operates at 10 Mbps, Fast
Ethernet operates at 100 Mbps, and Gigabit Ethernet operates at 1,000
Mbps.
Exchange: Exchange Server 2003 is Microsoft’s latest mail server and as an
enterprise server application requires significant resources in terms of
processor, RAM, and disk space.
Experiential learning: A process through which a learner constructs knowl-
edge, skill, and value based on direct experiences. Engage students in
critical thinking, problem solving, and decision making in contexts that are
personally relevant and connected to academic learning objectives by
incorporating active learning.
Experiential learning: Learning as a continuous spiral of concrete experi-
ence, observation and reflection, development of abstract concepts, and
testing in new situations.
F
Firewall: A software application running on a device that is responsible for
filtering incoming and outgoing traffic.
Formal language, formal method: A mathematically based technique for
precisely specifying and analyzing systems through abstract models. Major
classes of formal methods include those based on process algebras (e.g.,
the LOTOS language) or on state machines (e.g., the SDL language).
G
Gateway address: Usually the address of the default route to be used to reach
a network that is not specifically known.

364 Glossary
GNU: Technically means “Gnu’s Not Unix” (a weak recursive pun). GNU is a
project run by the Free Software Foundation, established to produce a free
Unix-style operating system (not to be confused with Linux, even though it
often comes with some GNU tools). Ethereal uses the copyright license
(sometimes called “copyleft”) developed by this project.
GUI: GUI stands for graphical user interface. Most of the modern operating
systems provide a GUI, which enables a user to use a pointing device, such
as a computer mouse, to provide the computer with information about the
user’s intentions.
H
Hazard: A situation in which a processor with multiple functional units could
compute an incorrect value by using the wrong data if appropriate precau-
tions are not taken.
Hub: A networking device that interconnects two or more workstations in a star-
wired local area network and broadcasts incoming data onto all outgoing
connections. To avoid signal collision only one user can transmit data
through the hub at a time.
I
IBSS: Or independent basic service set. A wireless LAN configuration without
access points. An IBSS is also referred to as an ad hoc mode wireless
network.
IC: Stands for integrated circuit. This is the circuitry contained within a chip or
component of the circuit board of a computer system.
IEEE 802.11b/a/g: Generally refers to wireless LAN standards. The IEEE
802.11b is the wireless LAN standard with a maximum bandwidth of 11
Mbps operating at 2.4 GHz. The IEEE 802.11a is the high-speed wireless
LAN with a maximum bandwidth of 54 Mbps operating at 5 GHz. The IEEE
802.11g is backward compatible with the IEEE 802.11b, with a maximum
bandwidth of 54 Mbps operating at 2.4 GHz.
Inert knowledge: Knowledge that is theoretical but difficult to apply in other
areas.
iNetwork Software: An interactive learning tool that teaches students about
data communication and networking.

Glossary 365
Information assurance: Conducting operations that protect and defend infor-
mation and information systems by ensuring availability, integrity, authen-
tication, confidentiality, and non-repudiation. This includes providing for
restoration of information systems by incorporating protection, detection,
and reaction capabilities.
Infrared: Electromagnetic waves whose frequency range is above that of
microwave but below the visible spectrum. The applications of infrared
technology include TV remote control and wireless LAN systems.
Infrastructure network: A class of wireless network architecture in which
ture and a centralized control.
Internetwork (or internet): A network of networks made up of separate
networks connected by devices such as routers. The global Internet is the
definitive example of this.
I/O port: A bus on the Intel 80x86 processors that uses the same address and
data lines as the memory bus but different read and write control lines.
IOS: Internetworking Operating System. A proprietary operating system found
on Cisco networking devices.
IP address (Internet address): A network address expressed as a 32-bit
number and usually represented in dotted decimal as four decimal numbers
separated by full stops. Every device connected to an internet, including the
global Internet, has a unique IP address. The IP address identifies the
device and the network that device is on. This form is currently the
standard, but later Internet protocols define addresses in a different format.
ISA: Internet and Acceleration Server is Microsoft’s firewall and proxy server
application. It followed Proxy Server 2.0 and was released in its first
version in 2000. Another version was released in 2004.
ISP: ISP stands for Internet service provider. This is a company that acts as an
access point for users of the Internet.
K
K-maps: This term refers to Karnaugh maps, a logical minimization method
based on graphical representation of Boolean functions in which each row
in the truth table of the Boolean function is represented as a box. Unlike the
truth table, K-map values of input must be ordered such that the values of
adjacent columns vary by one single bit.

366 Glossary
L
LAN: LAN stands for local area network. A class of computer network suitable
for a relatively small geographic area, for example, a room, a building, or
a campus. A LAN is owned by a single organization and physically located
within the organization’s premises. Ethernet is the most popular LAN
architecture.
LCD displays: LCD stands for liquid crystal display, which is a flat panel display
that uses liquid crystal to present information on the screen. The liquid
crystal is contained between two sheets of transparent material. When an
electric current passes through the crystals, they twist. This causes some
light waves to be blocked and allows others to pass through, which creates
the images on the screen.
LED: Stands for light-emitting diode. This is a solid-state device that glows
brightly when a small current passes through it from one input to the other.
Logic minimization: Simplification of Boolean expressions with the aim of
reducing the number of logical gates. This is done by reducing the number
of minterms into a number of prime implicants in which as many variables
as possible are eliminated. The tabular method makes repeated use of the
rule Â + A = 1.
Logic gate: An electronic device (based on transistors) used for implementing
logical functions. The inputs and outputs of the gate are Boolean (i.e.,
binary) values. Gates can be used to implement various Boolean functions.
NOT gates take one input and have one output. The AND, NAND, OR, and
NOR gates may take two or more inputs and have one output. XOR gates
take two inputs and have one output. Logical functions are all combinational
functions, that is, their output depends on the input. Gates can also be used
to implement latches and flip-flops which have an internal state and are
used to implement sequential logical systems.
LOGIC-Minimiser: Software package developed at the Auckland University
of Technology to enhance teaching and learning minimization of Boolean
expressions. The package was implemented in C programming language.
Logical topology: This refers to the way the data is sent through the network
from one computer (or device) to another.
M
MAC address: MAC stands for Medium Access Control. The MAC address
is a six-octet value that is permanently assigned to a NIC to uniquely

Glossary 367
identify it in any network. MAC addresses are loaded into the NIC by the
manufacturer and can not be modified. The first three octets identify the
manufacturer.
Mail-Server: an application responsible for handling incoming and outgoing
emails.
MAN: MAN stands for metropolitan area network. A MAN is a backbone
network that links multiple LANs in a large city or a metropolitan region.
Medium: The communications link or network that carries protocol messages.
Message: The structured data communicated by a protocol. Parameters of a
message typically include the message type, sequence number, control
flags, and user data.
Minterms: This term refers to the product of Boolean variables. These
variables can appear either as themselves or their inverses. A minterm
corresponds to exactly one row in the truth table of the Boolean function.
If we have four variables A, B, C, and D, then a minterm can be something
like A.B.C.D or Â.B.C.D, and so forth.
MySQL: An open source relational database tool which is used for Web
development (often used in conjunction with PHP).
N
NAT: Stands for Network Address Translation; a process of converting internal
IP addresses to external ones and vice versa, establishing a sort of a
“firewall” between a LAN and the rest of the network.
Network layer: This is the third layer of the OSI model, and it defines the means
for host-to-host logical addressing across a network. In the OSI model, it
is immediately above the data link layer.
Network simulator: A computer program that simulates the layout and
behaviour of a network and enables network activity to be initiated and
observed.
NIC: NIC stands for network interface card, which is the hardware interface
that provides the physical link between a computer and a network.
NOS: NOS stands for network operating system. It is a complex set of computer
programs that manage the common resources of a local area network. In
addition, NOS performs the standard operating system services. Examples
are NetWare, Linux, and MS Windows 2003.
NTFS: The NT File System is Microsoft’s most secure file system and is as a
result supported by Windows NT, Windows 2000, Windows XP, and
Windows 2003 operating systems.

368 Glossary
O
Octet: An octet is a sequence of eight bits. The term octet is preferred over byte
because the term byte has become ambiguous, oftentimes referring to the
number of bits reserved for a character.
Open source: A software distribution model in which the source must be
available to the user, and in addition anyone distributing the software must
do so for free and without any restriction being placed on anyone receiving
the code (apart from that defining open source).
Optical fibre: A type of cable which consists of one or more glass or plastic
fibre cores inside a protective cladding material, covered by an outer plastic
PVC jacket. Signal transmission along the inside fibres is accomplished
using light pulses. The optical fibre cable is characterised by an extremely
large data-carrying capacity. Optical fibre is used for undersea cables and
for countrywide telecommunications backbones.
OSI model: This is a model for the operation of computer interfaces. It divides
the needs of computer communication into levels and details what needs to
be defined at each of these levels for a successful interface.
OSPF: Open Shortest Path First is a dynamic routing protocol used to update
routing tables in routers using a more sophisticated routing algorithm.
P
Packet: A generic term used to define a unit of data including routing and other
information that is sent through an internet.
Packet forwarding: The process by which protocol data units in a packet-based
network are sent from their source to their destination.
Packet sniffer: Also known as packet analyzer or just sniffer. Software that
captures network traffic and displays the data for analysis. The data is
normally interpreted in some way so that the user does not need to manually
identify the individual fields within a packet.
PBIALS: The instructional model of the PBIALS is similar to the instructional
template proposed by Sage (2000). There are eight principal stages
(excluding the questionnaire stage) in this instructional model.
PBL: Problem-based learning is student-centered, uses small student groups,
and positions the teacher as a facilitator or guide. Life problems (real-world
problems) are used as the starting point for the instructional process in

Glossary 369
PBL. Clinical problem-solving and self-directed learning skills can then be
learned via the learning process.
Peer-to-peer network: A class of network in which a computer can commu-
nicate with any other networked computers on an equal or peer-like basis
without going through an intermediary, such as a server or a dedicated host.
PHP: “Hypertext Preprocessor”; a general-purpose scripting language which
can be embedded in HTML, widely used for Web development. It is
compatible with a variety of database management systems
Physical topology: This refers to the way computers and other devices are
connected within the network physically.
PIC BASIC: An adaptation of the BASIC computer language for use with PIC
microcontrollers.
PIC microcontroller: PIC stands for programmable interface controller. The
PIC microcontroller is an on-chip computer containing a CPU (central
processing unit), RAM (random access memory), programmable ROM,
timers, and input/output ports.
PIC programming: Generally refers to the procedures involved in creating a
sequence of instructions that can be installed in and acted upon by the PIC
microcontroller in order to control the operation of electrical and/or
mechanical equipment.
PIC projects: PIC-based projects which are developed to enhance teaching
and learning computer hardware concepts, as reported in chapter 12.
Ping: The name of a utility program used to test availability of a device on an
IP network. It works by sending a small packet to the target device and then
waiting for a response. The term is also now used as a verb meaning to
check if a device is accessible.
Pipeline: An arrangement of functional models in a high-performance proces-
sor in which part of the computation is carried out in each stage of the
pipeline. Data “flows” from one end of the “pipe” to the other.
Preamble (Ethernet): This is a string of 56 alternating binary ones and zeros
(starting with a one) that is sent at the beginning of an IEEE 802.3 Ethernet
frame.
Protocol: A protocol is a collection of rules for formatting, ordering, and error-
checking data sent across a network.
Protocol entity: The component of a system that implements a protocol.
PXE: Preboot Execution Environment is a way of booting off the network card
in order to connect to a server on the network.

370 Glossary
Q
Quine-McCluskey algorithm: Table-based reduction method for simplifica-
tion of Boolean expressions. This method is quite versatile as compared
with other algorithms. It can handle any number of inputs and can easily be
implemented on machines. The method starts from the truth table of the
Boolean function.
R
RAID 5: A redundant array of independent (or inexpensive) disks, level 5 is a
way of employing at least three disks in combination for the purpose of
performance and fault tolerance.
RAM: RAM stands for random access memory. A class of memory that is used
in the computer as main memory for the storage and retrieval of data and
instructions by the processor and other devices.
Remote Boot Disk Generator: The Remote Boot Disk Generator is a tool that
allows users to easily produce floppy disks that can connect a client
machine with a RIS server.
RFC: Request for comment. A set of documents that identifies issues, describes
best common practice, and defines standards for the Internet. Published by
the Internet Engineering Task Force (IETF).
RIP: Routing Information Protocol is a dynamic routing protocol used to update
the routing tables in routers.
RIS: Remote Installation Service is a service that can be installed on a Windows
2000 Server or Windows Server 2003 for the purpose of deploying, usually
in an automated fashion, various Microsoft operating systems to client
machines.
Risk analysis: An assessment of what could go wrong (risks), determination of
which risks warrant preventive or contingency actions, and development of
strategies to deal with those risks.
ROM: ROM stands for read-only memory. A class of memory that is used in
the computer for storing data, instructions, or information that can be read
but not modified; the data is recorded permanently on the chips. ROM is
nonvolatile memory, meaning its contents are not lost when power is
removed from the computer.
Router: The network device that connects networks together and implements
routing.

Glossary 371
Routing: It is a process that occurs on a network when a packet is shunted from
router to router along the path to the target destination. Routing is based on
identifying the destination network from the IP address of the target
machine.
S
Service: The abstract interface to a protocol. Details of how the protocol works
are hidden from the service user. For example, protocol error recovery
mechanisms such as retransmission on time-out are not visible in the
service.
Situated learning: Situated learning argues that learning should take place in
realistic settings to make learning meaningful. From this, we can infer that
scientific curriculum should be incorporated into students’ experiences.
Without situated learning, traditional education loses its ability to teach
practical knowledge.
SQL: While SQL refers to Structured Query Language, chapter 18 refers to
SQL as Microsoft’s well-known database application.
SSID: Or service set ID. A unique name that must be assigned to a service set
before the wireless network can operate.
Stall: A pipeline stalls when data is prevented from flowing from one stage to
the other to avoid a hazard or while waiting for a long latency operation such
as a memory fetch.
Start delimiter (Ethernet): This is an octet immediately following the pre-
amble of the IEEE 802.3 Ethernet frame that indicates the message starts
at this point. It is always a binary pattern equal to 10101011.
State machine: An abstract model that characterizes the behavior of a system
through the transitions it makes between states. Practical models have a
finite number of states. An extended finite state machine has a major state
that controls its main behavior and also state variables that have a smaller
impact on the general operation of the system.
Static routing: A form of routing in which the routes that packets take in a
network do not change as a function of time once they are configured.
Sum of product (SOP): A two-level expression which represents a sum of
minterms of a logical function. It is two-level because it is implemented by
two layers of logic gates. The first level represents the product of Boolean
variables of the logical function and the second level represents summing
the products with OR operator.

372 Glossary
Switch: A network device that connects communication links together, enabling
networks to be built that are on the same network but do not have to share
the same link. This reduces collisions and improves network efficiency.
SYN flood: A form of denial-of-service attack. The attacker sends a victim an
excessive number of packets that initiate the three-way handshake and
then does not follow up with further responses. This leaves the target
unable to deal with legitimate connection requests.
Synchronous: All operations are synchronized to a global clock.
Sysprep: Microsoft’s System Preparation Tool is a utility for the mass deploy-
ment of the Microsoft NT family of operating systems.
T
TCP/IP: Transmission Control Protocol/Internet Protocol is the family of
protocols used for Internet communication.
Teaching hospital: A hospital that is affiliated with a medical school and
provides the means for medical education to students, interns, and resi-
dents. It also functions as a formal center of learning for the training of
physicians, nurses, and allied health personnel.
Threats: Potential causes of harm to assets through exploitation of vulnerabili-
ties.
Three/five-column diagram: A form of time-sequence diagram that shows
the two protocol entities and the medium (three-column) or also the two
service users (five-column).
Three-way handshake: The initial exchange of messages that occurs when
two devices are establishing a connection using TCP. Understanding this
is essential to understanding the TCP connection and things that can
potentially go wrong with the connection.
Time-sequence diagram: A graphical presentation of message exchange
among communicating systems. Time flows down the page. Arrows show
messages between carried from one system element to another.
Toolkit: A library of classes which model objects commonly required in
animations; classes designed for reuse.
Tracert: A network diagnostic tool found on both Microsoft and UNIX
operating systems. The diagnostic tool is used to track the path of network
communication.
Transport layer: This is the fourth layer of the OSI model, immediately above
the network layer. It provides a network-independent mechanism for

Glossary 373
sending large blocks of data, thereby hiding the details of the network from
the services in the layers above it.
TTL (time-to-live): A parameter set in a data packet that defines how long that
packet can remain active on the network.
U
USB: Universal Serial Bus is a standard that supports Plug and Play and is used
for connecting peripheral devices to a PC.
User: The system element that employs a service. This may be a human end-
user or, more typically, a communications application that provides further
services to the end user.
User Mode Linux: User Mode Linux is an open source product that does the
same kinds of things as VMware but unlike VMware is limited to Linux
systems.
V
Virtual PC: Virtual PC is Microsoft’s commercial product that competes
directly with and is comparable to VMware.
VLAN (virtual local area network): A logical shared network created by
connecting devices to configurable switches so that the network is not
constrained by any physical boundary.
VMware: VMware is a commercial product that allows one simultaneously to
run a number of systems within the context of this application.
VPN: A virtual private network is a networking technology that involves network
tunnels being created between nodes within a public network.
Vulnerabilities: Weak characteristics of assets in an organization.
W
WAN: WAN stands for wide area network. A WAN covers a large geographi-
cal area (e.g., a country or a continent). Telephone networks and the
Internet are examples of WANs.
Web server: A software application running on a computer that is responsible
for serving Web pages on a network.

374 Glossary
Wi-Fi: Or wireless fidelity. A trade or commercial name for wireless networking
equipment using IEEE 802.11b standard.
Wi-Fi antenna: This term generally refers to an antenna used with Wi-Fi
equipment to enhance the transmission and reception of the wireless signals
used in the transfer of data between the sending equipment and the intended
receiving equipment.
Wired LAN: This term refers to a LAN which uses cable media (e.g., UTP Cat
5e) for LAN connectivity and typically covers a limited area, such as a
room, a building, or a campus.
Wireless LAN: This term refers to a LAN which uses infrared or radio
frequencies rather than physical cable as the transmission medium.
Wireless link: Generally refers to a pathway for the transmission of informa-
tion via a modulated unconstrained electromagnetic wave.
Workstation: An end-user computer that has its own CPU and is used as a
client to access another computer, such as a file server.

About the Authors 375
AbouttheAuthors
Nurul I. Sarkar is a senior lecturer in the School of Computer and Information
Sciences at Auckland University of Technology, New Zealand. He has more
than nine years of teaching experience in universities at both undergraduate and
postgraduate levels and has taught a range of subjects, including computer
networking, data communications, computer hardware, and e-commerce. Sarkar
has published in the international journals and conferences, including the IEEE
Transactions on Education, International Journal of Electrical Engineer-
ing Education, International Journal of Information and Communication
Technology Education, International Journal of Business Data Communi-
cations and Networking, Measurement Science & Technology, the 2005
Information Resources Management Association international conference, the
third IEEE International Conference on Information Technology Research and
Education, the 35th
ACM Technical Symposium on Computer Science Educa-
tion, the fourth IEEE International Conference on Advanced Learning Technolo-
gies, and the sixth IEEE Symposium on Computers and Communications. In
addition, he has contributed chapters to several edited research compilations.
Sarkar served as regional editor of the Pakistan Journal of Information and
Technology; chair of the IEEE New Zealand Communications Society Chapter;
executive peer-reviewer of the SSCI indexed journal of Educational Technol-
ogy & Society; member of editorial review board of the International Journal
of Information & Communication Technology Education; and a member on
the IASTED Technical Committee on Computers and Advanced Technology in
Education (2004–2007). His research interests include wireless communication

376 About the Authors
networks, simulation and modeling of computer and data communication net-
works, and tools to enhance methods for teaching and learning computer
networking and hardware concepts. He is a member of the IEEE Communica-
tions Society.
* * * * *
David Bremer is a senior lecturer in the School of Information Technology and
Electrotechnology and program manager for the computer technician certificate
at Otago Polytechnic, New Zealand. Coming from a career as a systems
administrator, he now teaches Year 2 and 3 networking papers in the bachelor
of information technology program during the day and the Cisco Network
Academy Program in the evening. Current academic interests include negotiated
contract learning, vocational IT education, and professional development. How-
ever, his most significant activities involve his wife Karen and their new son
Christopher, who should just about be talking when this is published.
Alex Chang received his BS degree from the Department of Information and
Computer Engineering at Chung-Yuan Christian University in 2004. He has been
a lecturer in the Department of Lifelong Education at Yuan Ze University,
Taiwan, since 2004. Also, he is a system engineer in the Department of Research
and Development at Knowledge Square (K2
) Ltd. Chang’s research interests
include mobile learning, instant learning feedback, knowledge structure, PBL,
conceptual diagnosis, and learning behavior analysis.
Maiga Chang received his PhD from the Department of Electronic Engineering
at the Chung-Yuan Christian University in 2002. His BS and MS degrees were
received from the Department of Information and Computer Engineering at the
same university in 1996 and 1998, respectively. From 2000 to 2003, he taught in
three universities and was an IT/EC/e-business consultant for about 10 busi-
nesses and organizations, including the Small and Medium Enterprises Guidance
& Service Center of Taipei City Government. He was also invited as a member
by the International Who’s Who of Professionals in 2000. In September 2004 he
received the 2004 Young Researcher Award in Advanced Learning Technolo-
gies from the IEEE Technical Committee on Learning Technology (IEEE
TCLT). He currently is the international program coordinator in the Program
Office of the National Science and Technology Program for e-Learning,
Taiwan.

Ming-Wei Chen is a private vocational school teacher and gives computer-
related lessons at Chih-Ping Senior High School, Taiwan. He received his BS
degree in the Department of Information and Computer Engineering at Chung-
Yuan Christian University in 1999. He also got an MS degree from the Graduate
Institute of Science Education at CYCU in 2004. Besides, Chen is the author of
a book about Microsoft Office Specialist certification (in press). His recent
research is about problem-based learning (PBL) issues for vocational students
in Taiwan. In the future, he will keep working hard on PBL research to make
PBL become one of the most popular instructional strategies in Taiwan.
Kun-Fa Cheng received his BS degree from the Department of Information and
Computer Engineering at Chung-Yuan Christian University in 2002. He worked
as programmer at Ford Motor Company and was a leader of the Technology
Support Group in the Department of Research and Development at Knowledge
Square (K2
) Ltd. He is currently a teacher in the Department of Computer
Science at Chih-Ping Senior High School, Taiwan. He is also working in the e-
Learning Resource Center at the same school. Cheng’s research interests
include problem-based learning, knowledge structure, rough set, and e-learning
instructional model.
Eduardo Correia arrived in New Zealand with his family in January 1999. He
has lectured at various universities in South Africa, including Rhodes University,
the Eastern Cape University of Technology and the University of the Western
Cape. He worked for a number of years both as a systems engineer and as a
trainer in the IT industry before being appointed as a senior lecturer in the School
of Computing at the Christchurch Polytechnic Institute of Technology, New
Zealand. Correia is a Microsoft Certified Systems Engineer in Windows NT4,
Windows 2000 Server, and Windows Server 2003 and has been a Microsoft
Certified Trainer for a number of years.
Trevor Craig completed an MSc in statistics and mathematics at Massey
University in New Zealand in 1986 and then took up a teaching position at the
Sydney Institute of Technology, where he taught mathematics to students
studying for various trade qualifications. This environment and his involvement
in amateur radio encouraged his interest in the use of electronic equipment and
computer software as teaching aids. He took this interest a step further in 2001
by taking up a position teaching English at a polytechnic in Daegu, South Korea.
At that time, he enrolled in an MA in applied linguistics program via distance
learning at the University of Southern Queensland, Australia. In the same year,
he also completed an RSA Celta certificate at the British Council in Seoul, South

Korea. Since returning to New Zealand in 2004, he has been teaching freshman
mathematics and statistics at Wollongong College, a University of Wollongong,
Australia, enterprise, located in Auckland, New Zealand.
Sanjay Goel is an assistant professor in the School of Business at the University
at Albany, State University of New York, USA. He is also the director of
research at the New York State Center for Information Forensics and Assur-
ance at the university. Before joining the university, he worked at the General
Electric Global Research Center. Dr. Goel received his PhD in mechanical
engineering in 1999 from Rensselaer Polytechnic Institute. His current research
interests include self-organized systems for modeling of autonomous computer
security systems using biological paradigms of immune systems, epidemiology,
and cellular regulatory pathways. He also actively works on distributed service-
based computing, network security, and active networks. His research includes
use of machine-learning algorithms to develop self-learning adaptive optimiza-
tion strategies and use of information theoretic approaches for classification of
data for use in applications such as portfolio analysis and information assurance.
He has been invited to present seminars at several conferences in information
security with topics including wireless security, hacking, botnets, and so forth.
He has several publications in leading conferences and journals. Dr. Goel
teaches several classes, including computer networking and security, informa-
tion security risk analysis, security policies, enterprise application development,
database design, and Java language programming.
Cecil Goldstein is a lecturer in the School of Software Engineering and Data
Communications at Queensland University of Technology (QUT), Australia. His
main teaching focus has been in the area of internetworking, and he is currently
teaching and coordinating a core second-year unit in this subject. He has been
involved in research to investigate strategies for facilitating the teaching of data
communications concepts and evaluating these, particularly for large classes. He
holds a BA in the social sciences and an MSc in computer science.
Anthony P. Kadi received his BE in electrical engineering, majoring in
telecommunication engineering, in 1991 from The University of Technology,
Sydney (UTS), Australia. After working in medical diagnostic ultrasound
research for the CSIRO, he joined UTS as an associate lecturer in 1996 and was
awarded a master of telecommunication engineering from the same institution in
2001. He is currently employed as a senior lecturer and director of postgraduate
coursework programs. He hopes to complete a PhD in education.

Vladimir Lasky has worked over the years in various embedded systems
development roles for CTI Communications and Lake Technology. He com-
pleted his undergraduate BE (computer systems) degree with first class honours
at The University of Technology, Sydney, Australia, in 2003 and is now
undertaking a PhD at the Australian Centre for Field Robotics at the University
of Sydney. At various times he has held positions of responsibility as a part-time
academic staff member at the University of Technology, Sydney, where he
pioneered the development of remotely accessible laboratories whilst lecturing
and tutoring undergraduate courses.
Susanna Leisten earned a BS and honours and a postgraduate certificate of
education from Cambridge University, United Kingdom, and then migrated to
Australia and taught high school maths and physics for 10 years. A career
change commenced with a master’s degree in information technology at
Queensland University of Technology (QUT), Australia, a few years work in
industry as a network engineer, and finally the move back to teaching
internetworking at QUT. Years of observation of school students has led her to
a conviction that the few truly vital ingredients required to encourage and assist
with positive learning experiences transcend age groups. We all learn more when
we are actively engaged in a novel field of study and are provided with suitably
interactive learning experiences and feedback that captures our interest suffi-
ciently to engender the focus needed to fully comprehend complex concepts.
John Morris earned a PhD from the University of Sydney by studying the
optical properties of some obscure aromatic hydrocarbon systems. After a close
encounter with the 30kV power supply of a pulsed laser in the Institute for
Physical and Chemical Research, Saitama, Japan, he retreated to the much safer
arena of computer architecture research, where he has watched approvingly as
power supply voltages dropped from 5V to a very safe 1V or so. He now holds
a joint appointment to the departments of Computer Science and Electrical and
Computer Engineering at the University of Auckland, New Zealand.
Steve Murray completed a BE (electrical) at the University of Newcastle, New
South Wales, in 1986, and after some years working for Ferranti Computer
Systems in the United Kingdom and Australia, he graduated from the University
of New South Wales with an MEngSc (systems and control). He joined The
University of Technology Sydney, Australia, in 1992 and has since been a full-
time teaching-oriented academic staff member in initially the Computer Systems
Engineering Group and later in the Information and Communications Technolo-
gies Group. His technical interests are in the fields of real-time operating systems
and embedded computer systems.

Krassie Petrova is a senior lecturer and program leader at the School of
Computer and Information Sciences at Auckland University of Technology,
New Zealand, where she teaches networking, information security, information
technology, and e-business courses and coordinates the master of computing and
information sciences program. She received her master’s degree from the
University of Sofia. She has held teaching and research positions in IS/IT in
several universities and has published and presented over 40 papers on informa-
tion technology and e-business education, flexible and online learning, IT and e-
business cooperative education, IT and e-business curriculum development, and
mobile business applications. Her current research work belongs to two main
areas: education (student capability development and innovation) and informa-
tion systems (mobile business models and viability).
Khaleel I. Petrus earned his BSc and MSc in electronics and communications
from the University of Baghdad, Iraq, in 1976 and 1978, respectively. In 1979,
he joined the University of Mosul, Iraq, as an assistant lecturer until 1983. He
earned his PhD in 1987 from the University of Essex, UK. He then worked at
the University of Mosul as a lecturer. In 1995 he worked as a lecturer at the
Engineering Academy, Libya. In 1997, he joined the University of Applied
Sciences, Jordan, as an associate professor. In 1999 he started working as a
lecturer at the Auckland University of Technology, New Zealand. Since 2003,
he has worked as a lecturer at the University of Southern Queensland, Australia.
His teaching areas include computer graphics, multimedia systems, and informa-
tion technology ethics. His research interest is in bioinformatics.
Damira Pon is currently pursuing a doctoral degree in information science with
a specialization in information assurance at the College of Computing and
Information at the University at Albany, State University of New York (SUNY),
USA. She received her MS degree in 2004 from the School of Information
Science & Policy at the University at Albany, SUNY. Her doctoral dissertation
uses elements from biological phenomena to develop models and tools for
information security. She is currently employed at the New York State Center
for Information Forensics and Assurance, where she works with faculty on
solving information security problems in businesses and developing curriculum
for information assurance. She has also worked on several topics, including risk
analysis, botnets, and wireless security.
K. Sandrasegaran holds a PhD in electrical engineering from McGill Univer-
sity, Canada, an MS in telecommunication engineering from Essex University,
United Kingdom, and a BS (honours) in electrical engineering (first class) (UZ).
At present, he is a program head of telecommunication engineering within the

Faculty of Engineering, The University of Technology Sydney (UTS), Australia.
Prior to joining UTS, he worked at Massey University, New Zealand, and
University of Durban, South Africa. During his academic career, he has taught
a number of undergraduate and postgraduate subjects in telecommunication
engineering, communication networks, wireless networking technologies, and so
forth.
Wilson Siringoringo received his bachelor’s degree in information technology
from Bandung Institute of Technology, Indonesia. He worked for several years
as a computer programmer in Indonesia before moving to New Zealand. Prior
to taking up postgraduate study, Siringoringo is writing Delphi code for a
software house in Auckland. Now he is about to start his master’s thesis at
Auckland University of Technology. His current interests are artificial intelli-
gence, data mining, and mobile computing. He likes to spend his spare time
reading, watching sports, and jogging around the neighborhood.
Karen Stark is a research assistant in the Faculty of Information Technology
at Queensland University of Technology (QUT), Australia. She was awarded
her bachelor of education in 1989 and her master of information technology in
1999. She has participated in a number of research projects aimed at improving
the teaching and learning of information technology.
David L. Tarnoff is an assistant professor in the Computer and Information
Sciences Department at East Tennessee State University, USA, where he
teaches computer hardware, embedded system design, and Web technologies.
He holds a bachelor’s and a master’s of science in electrical engineering from
Virginia Tech. In 1999, Tarnoff started Intermation Inc., a business that develops
software for remote data collection and automation. His research interests
include embedded system design and the application of Web technologies to
teaching and research. He also develops case studies for engineering education
and serves as an officer of the Southeast Case Research Association.
Alan Tickle is an assistant dean in the Faculty of Information Technology at
Queensland University of Technology (QUT), Australia, where he has respon-
sibility for the design of the undergraduate course offerings. Currently his main
research interest is in identifying the impediments students have in learning
complex and abstract topics in information technology and networking. During
his time at QUT Dr. Tickle has conducted training courses both nationally and
internationally in communications networks and information security for govern-
ment and private-sector clients. He has also consulted for government and
industry on various facets of information technology and telecommunications.

M. Trieu is a final-year student in the software engineering program of the
Faculty of Engineering, The University of Technology Sydney, Australia.
Kenneth J. Turner holds a bachelor’s degree in electrical engineering and a
doctorate in computer science. He worked for 12 years as a communications
consultant in industry. Since 1987, he has been a professor of computing science
at the University of Stirling, Scotland. His teaching interests include communi-
cations systems, software engineering, and compiler design. His research
interests include communications services, distributed systems, and formal
methods.
Ricky Watson has been active as a systems and network administrator since
1991. During this time he has implemented and supported (both for production
and teaching purposes) a variety of systems, including Novell Netware, IBM’s
OS/2 LAN Server, NetBSD, Linux, and various Microsoft Windows NT
operating systems. He developed an interest in virtual technologies from an early
experience with a Macintosh emulator on an Amiga 500. Later, he discovered
VMware Workstation and began using it to teach operating systems, networking,
and programming. Watson is a Microsoft Certified Systems Engineer and is
currently a senior lecturer in the School of Computing at the Christchurch
Polytechnic Institute of Technology, New Zealand.

Index 383
Index
A
access point 143
active learning 66
ADC (analog-to-digital converter) 202
analog-to-digital converter (ADC) 202
analogue-to-digital (ADC) 232
animation 71, 86
animation system 270
application programming interface 89
assets 189
assistant tool 249
Auckland University of Technology 23
B
base address 211
bit pattern 322
Boolean expression 303
brainstorm map 250
bus contention 205
C
cable 2
case-based learning 181
case-based teaching 181
cellular phone 157
chief information officer 128
chip select 206
Cisco 105
client software 287
clocked pipeline simulation 273
cnet 8, 24, 88
communication 321
communication protocol 86
computer hardware 1, 299, 306
computer networking 1, 62
concept map 250
constructivism 21, 103, 251
control system 203
control unit (CU) 4
cooperative learning 250, 252
corner behavior 95
CRC (cyclic redundancy check) 324
cross-development 286
CU (control unit) 4
cyclic redundancy check (CRC) 324
D
daisy-chaining 205
DAQ (data acquisition) 202
data acquisition (DAQ) 202
data communication 63, 86

384 Index
data output register 210
debugging 291
device interface 203
device under test (DUT) 289
digital logic design 306
DigitalWorks 3.0 10
distributed knowledge 104
distribution system 161
DlpSim 9
DUT (device under test) 289
E
EEPROM 234
electromagnetic 141
ethereal 119
Ethernet Frame 329
experiential learning 21, 103
experimentalism 252
explicit knowledge 104
extended service set 161
extensibility 278
F
face-to-face 295
fetch-execute cycle 6
G
government 179
H
hands-on 239
hands-on learning 135, 154
hardware 1, 163
I
I/O (input/output) 202, 229
iNetwork 9
information assurance 180
information security risk 179
infrared remote control 138
infrared signal 137
input/output (I/O) 202, 229
input devices 1
Input port 201
installation 156
instruction register (IR) 5
internal memory 286
Internet 64, 123, 256, 284, 325, 346
Internet protocol (IP) 324
Internet service provider (ISP) 322
Internet virtual classroom (IVC) 256
IP (Internet protocol) 324
IR (instruction register) 5
ISP (Internet service provider) 322
IVC (Internet virtual classroom) 256
J
JASPER 8, 88
Java 267
K
knowledge 101, 182, 251
L
laboratory 108
LAN (local area network) 2, 22
LAN-Designer 25
Layer-Modul 24
LCD Display 237
learner 339
learning 63, 101, 135,154,181,229
learning and teaching theory 106
learning experience 102
learning tool 338
learning-by-doing 7
LEDmatrix 235
lesson plan 309
light-emitting diode 233
local area network (LAN) 2, 22
LOGIC-Minimiser 10, 303
logisim 9
M
MAC (medium access control) 323
MAN (metropolitan area network) 2
MAR (memory address register) 5
MDR (memory data register) 5
medium access control (MAC) 323
memory 1, 206, 229, 279,284

Index 385
memory address register (MAR) 5
memory data register (MDR) 5
message sequence chart (MSC) 88
metropolitan area network (MAN) 2
microprocessor 201
mobility 156
motivation 157, 340
MSC (message sequence chart) 88
multitasking 284
multithreading 284
N
NAT (network address translation) 342
NetMod 9, 24
network 65
network address translation (NAT) 342
network education 121
network intelligence 24
network interface card (NIC) 323
network simulation tool 62
network simulator 24, 65
networking 137
NIC (network interface card) 323
ns-2 8, 24
O
OPNET 8
Oregon State University 288
output devices 1
output port 201
P
Packet Tracer 63
packet-forwarding 101
Packetyzer 320
parallel port 209
PBL (problem-based learning) 249
PC (program counter) 5
PCF (point coordination function) 160
PDA (personal digital assistant) 27, 157
personal digital assistant (PDA) 27, 157
PIC 229
Picocontroller simulator 10
ping 65
pipelining 267
point coordination function (PCF) 160
practical knowledge 120
problem-based learning (PBL) 249
process control 239
processor animation 272
processor simulator 10
program counter (PC) 5
protocol 86
protocol animation 87
pull-up resistor 213
pulse-code modulation 239
Q
Q-M algorithm 307
R
RAM (random access memory) 234
random access memory (RAM) 234
read-only memory (ROM) 234
RemoteExperimentLab(RExLab) 286
Remote Installation Service (RIS) 349
Reusability 145, 239
RExLab(RemoteExperimentLab) 286
risk analysis 183
ROM (read-only memory) 234
S
scalability 156
security 128, 144, 179, 295, 346
serial communication 321
serial protocols 319
server software 287
situated learning 252
sniffer 122
software 164
SOP (sum of product) 304
Specification and Description Language 88
speech generation 237
SR (status register) 5, 210
status register (SR) 5, 210
student 101, 187, 252
student interaction 252
student understanding 101
student-centered 251
sum of product (SOP) 304

386 Index
synchronization 322
T
tacit knowledge 104
teaching 21, 135, 154, 181, 229
teaching hospital 179
transmission control protocol 90
troubleshooting 125
V
video monitoring 292
virtual automation laboratory 287
virtual Internet 88
virtual local area network (VLAN) 68
virtual switch 342
VLAN (virtual local area network) 68
VMware 338
vulnerabilities 189
W
WAN (wide area network) 2
Web browser 90
Web cameras 288
Web Lan-Designer 21
Web-based processor simulator 10
Webcams 288
WebLan 8
WebTrafMon 9, 24
Wi-Fi networking 154
wide area network (WAN) 2
Windows XP 143
WinLogiLab 10
wireless 156
wireless Communication 135
wireless local area network (WLAN) 158
wireless media 2
wireless personal area network (WPAN)
158
wireless technology 239
wireless wide area network (WWAN) 158
WLAN (wireless local area network) 158
WLAN-Designer 25
WPAN (wireless personal area network)
158
WWAN (wireless wide area network) 158
Z
zero insertion force 233
zero insertion force socket 233

InfoSci-Online
Experience the latest full-text research in the fields
of Information Science, Technology & Management
infosci-online.com
A PRODUCT OF
Publishers of Idea Group Publishing, Information Science Publishing, CyberTech Publishing, and IRM Press
“…The theoretical bent
of many of the titles
covered, and the ease
of adding chapters to
reading lists, makes it
particularly good for
institutions with strong
information science
curricula.”
— Issues in Science and
Technology Librarianship
To receive your free 30-day trial access subscription contact:
Andrew Bundy
Email: abundy@idea-group.com • Phone: 717/533-8845 x29
Web Address: www.infosci-online.com
InfoSci-Online is available to libraries to help keep students,
faculty and researchers up-to-date with the latest research in
the ever-growing field of information science, technology, and
management.
The InfoSci-Online collection includes:
Scholarly and scientific book chapters
Peer-reviewed journal articles
Comprehensive teaching cases
Conference proceeding papers
All entries have abstracts and citation information
The full text of every entry is downloadable in .pdf format
Some topics covered:
Business Management
Computer Science
Education Technologies
Electronic Commerce
Environmental IS
Healthcare Information Systems
Information Systems
Library Science
Multimedia Information Systems
Public Information Systems
Social Science and Technologies
InfoSci-Online
features:
Easy-to-use
6,000+ full-text
entries
Aggregated
Multi-user access

An excellent addition to your library
It’s Easy to Order! Order online at www.idea-group.com or
call 1-717-533-8845 x10!
Mon-Fri8:30am-5:00pm(est)orfax24hoursaday717/533-8661
ISBN 1-59140-106-2(h/c); eISBN 1-59140-114-3 • US$79.95 • 255 pages • Copyright © 2003
The organization, functioning, and the role of
libraries in university communities continue to
change dramatically. While academic research
libraries continue to acquire information,
organize it, make it available, and preserve it,
the critical issues for their management teams
in the twenty-first century are to formulate a
clear mission and role for their library,
particularly as libraries transition to meet the
new information needs of their university
constituents. Building a Virtual Library
addresses these issues by providing insight into the current changes
and developments within the area of library science.
“Itiscriticalfortheuniversitytomakelongstandingfinancialcommitmentsto
supportthelibrary’sroleintheacademiconlineenvironment. Thisincludes
innovativefundinginitiativesandcommitmentsforresourcesthatthelibrary
anduniversitytogethermustidentifyandestablish.”
–Ardis Hanson and Bruce Lubotsky Levin
University of South Florida, USA
Building a Virtual
Library
Ardis Hanson and Bruce Lubotsky Levin
University of South Florida, USA
Ardis Hanson
Bruce Lubotsky Levin
Building a
Virtual
Library
Hershey • London • Melbourne • Singapore • Beijing

Computer Networking & Hardware Concepts.pdf

More Related Content

Similar to Computer Networking & Hardware Concepts.pdf (20)

More from arshi bharda (12)

Recently uploaded (20)

Computer Networking & Hardware Concepts.pdf