Chapter_2.pdf course of network and subject

© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
ITE PC v4.0
Chapter 1 1
Communicating over the
Network
Network Fundamentals – Chapter 2

ITE PC v4.0
Chapter 1 2
Objectives
ƒ Describe the structure of a network, including the
devices and media that are necessary for successful
communications.
ƒ Explain the function of protocols in network
communications.
ƒ Explain the advantages of using a layered model to
describe network functionality.
ƒ Describe the role of each layer in two recognized
network models: The TCP/IP model and the OSI
model.
ƒ Describe the importance of addressing and naming
schemes in network communications.

ITE PC v4.0
Chapter 1 3
Network Structure
The Elements of Communication
ƒ 3 common elements of communication
• message source
• the channel
• message destination
ƒ The network term is
– data or information networks capable of carrying many different types of communications

ITE PC v4.0
Chapter 1 4
Network Structure
Communicating the Messages
ƒ Data is sent across a network in small “chunks” called segments

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Chapter 1 5
Network Structure
Components of the Network
ƒ Hardware
– Physical element or hardware of the network
ƒ Software
– Communication programs such as services and processes that run on the networked devices

ITE PC v4.0
Chapter 1 6
Network Structure
End Devices and their Role in the Network
ƒ End devices form interface with human network & communications network
– Computer
– Network printer
– Mobile handheld devices
ƒ Role of end devices:
– Client
– Server
– Both client and server

ITE PC v4.0
Chapter 1 7
Network Structure
Intermediary Devices and their Role on the Network
ƒ Examples of intermediary network devices are:
– Network Access Devices (Hubs, Switches, and Wireless Access Points)
– Internetworking Devices (Routers)
– Communication Servers and Modems
– Security Devices (Firewalls)
ƒ Role of an intermediary device
– provides connectivity and ensures data flows across network

ITE PC v4.0
Chapter 1 8
Network Structure
Network Media
ƒ The channel over which a message travels

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Chapter 1 9
Network Types
Local Area Networks (LANs)
ƒ A network serving a home, building or campus is considered a Local Area Network (LAN)

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Chapter 1 10
Network Types
Wide Area Networks (WANs)
ƒ LANs separated by geographic distance are connected by a network known as a Wide Area
Network (WAN)

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Chapter 1 11
Network Types
The Internet – A Network of Networks
ƒ The internet is defined as a global mesh of interconnected networks

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Chapter 1 12
Network Types
Network Representations

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Chapter 1 13
Function of Protocol in Network
Communication
Rules that Govern Communications
ƒ All communication, whether face-to-face or over a network is governed by
predetermined rules called protocols.
ƒ Successful communication between hosts on a network requires the interaction
of many different protocols.

ITE PC v4.0
Chapter 1 14
Communication
Network Protocols
ƒ Network protocols are used to allow devices to
communicate successfully
ƒ Networking protocols suites describe
processes such as:
– The format or structure of the message
– The process by which networking devices
share information about pathways with other
networks
– How and when error and system messages are
passed between devices
– The setup and termination of data transfer
sessions

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Chapter 1 15
Communication
Protocol Suites and Industry Standards
ƒ A standard is a process or protocol that has been endorsed by the networking
industry and ratified by a standards organization

ITE PC v4.0
Chapter 1 16
Communication
The Interaction of Protocols
ƒ Involved with a number of protocols and standard in the process of exchanging information,
e.g. the interaction between a web server and a web browser.

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Chapter 1 17
Communication
Technology Independent Protocols
ƒ Many diverse types of devices can communicate using the same sets of protocols. This is
because protocols specify network functionality, not the underlying technology to support this
functionality.

ITE PC v4.0
Chapter 1 18
Layers with TCP/IP and OSI Model
The benefits of Using a Layered Model
ƒ Benefits include
– Assists in protocol design, because protocols that operate at a specific layer have
defined information that they act upon and a defined interface to the layers above and
below
– Fosters competition because products from different vendors can work together
– Prevents technology or capability changes in one layer from affecting other layers
above and below
– Provides a common language to describe networking functions and capabilities

ITE PC v4.0
Chapter 1 19
Protocol and Reference Models
ƒ A protocol model
– provides a model that closely
matches the structure of a
particular protocol suite.
ƒ A reference model
– provides a common reference for
maintaining consistency within
all types of network protocols
and services.

ITE PC v4.0
Chapter 1 20
The TCP/IP Model

ITE PC v4.0
Chapter 1 21
The Communication Process
ƒ A complete communication process includes the following steps:
– Creation of data at the application layer of the originating source end device
– Segmentation and encapsulation of data as it passes down the protocol stack in the source end
device
– Generation of the data onto the media at the network access layer of the stack
– Transportation of the data through the internetwork, which consists of media and any intermediary
devices
– Reception of the data at the network access layer of the destination end device
– Decapsulation and ressembly of the data as it passes up the stack in the destination device
– Passing this data to the destination application at the Application layer of the destination end device

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Chapter 1 22
Protocol Data Units (PDU) and Encapsulation

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Chapter 1 23
The Sending and Receiving Process

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Chapter 1 24
The OSI Model

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Chapter 1 25
Comparing the OSI Model with the TCP/IP model

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Chapter 1 26
Addressing and Naming Schemes
Addressing in the Network
ƒ There are various types of addresses that must be included to successfully deliver the data
from a source application running on one host to the correct destination application on
another.

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Chapter 1 27
ƒ Examples of Ethernet MAC Addresses, IP Addresses, and
TCP/UDP Port numbers

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Chapter 1 28
Getting the Data through the Internetwork
ƒ Labels in encapsulation headers are used to manage communication in data networks

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Chapter 1 29
Getting the Data to the Right Application
ƒ Information in the encapsulation header is used to identify the source and destination processes
for data communication

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Chapter 1 30
Summary

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Chapter 1 31

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