2. Objectives
After completing this part, you will be able to:
Explain how rules are used to facilitate communication.
Explain the role of protocols and standards organizations in
facilitating interoperability in network communications.
Explain how devices on a LAN access resources in a small to
medium-sized business network.
3. Part 3
3.1 Rules of Communication
3.2 Network Protocols and Standards
3.3 Moving Data in the Network
3.4 Summary
6. The Rules
Establishing the Rules
An identified sender and receiver
Agreed upon method of communicating (face-to-face, telephone, letter,
photograph)
Common language and grammar
Speed and timing of delivery
Confirmation or acknowledgment requirements
8. The Rules
Message Formatting and Encapsulation
Example: Personal letter contains the following elements:
Identifier of the recipient’s location
Identifier of the sender’s location
Salutation or greeting
Recipient identifier
The message content
Source identifier
End of message indicator
9. The Rules
Message Size
An overview of the segmenting process:
The size restrictions of frames require the source host to break a long
message into individual pieces (or segments) that meet both the
minimum and maximum size requirements.
Each segment is encapsulated in a separate frame with the address
information, and is sent over the network.
At the receiving host, the messages are de-encapsulated and put back
together to be processed and interpreted.
12. Protocols
Network Protocols
How the message is formatted or structured
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
13. Protocols
Interaction of Protocols
Application Protocol – Hypertext Transfer Protocol (HTTP)
Transport Protocol – Transmission Control Protocol (TCP)
Internet Protocol – Internet Protocol (IP)
Network Access Protocols – Data link & physical layers
15. Protocol Suites
Creation of Internet, Development of TCP/IP
The first packet switching network and predecessor to today’s Internet was
the Advanced Research Projects Agency Network (ARPANET), which came
to life in 1969 by connecting mainframe computers at four locations.
ARPANET was funded by the U.S. Department of Defense for use by
universities and research laboratories. Bolt, Beranek and Newman (BBN)
was the contractor that did much of the initial development of the
ARPANET, including creating the first router known as an Interface
Message Processor (IMP).
In 1973, Robert Kahn and Vinton Cerf began work on TCP to develop the
next generation of the ARPANET. TCP was designed to replace
ARPANET’s current Network Control Program (NCP).
In 1978, TCP was divided into two protocols: TCP and IP. Later, other
protocols were added to the TCP/IP suite of protocols including Telnet,
FTP, DNS, and many others.
17. Standards Organizations
Open Standards
The Internet Society (ISOC)
The Internet Architecture Board (IAB)
The Internet Engineering Task Force (IETF)
Institute of Electrical and Electronics Engineers (IEEE)
The International Organization for Standards (ISO)
21. Standards Organizations
Other Standards Organization
The Electronic Industries Alliance (EIA)
The Telecommunications Industry Association (TIA)
The International Telecommunications Union – Telecommunications
Standardization Sector (ITU-T)
The Internet Corporation for Assigned Names and Numbers (ICANN)
The Internet Assigned Numbers Authority (IANA)
27. Data Encapsulation
Communicating the Messages
Segmenting message benefits
Different conversations can be interleaved
Increased reliability of network communications
Segmenting message disadvantage
Increased level of complexity
33. Accessing Local Resources
MAC and IP Addresses
PC1
192.168.1.110
AA-AA-AA-AA-AA-AA
PC2
192.168.1.111
BB-BB-BB-BB-BB-BB
FTP Server
192.168.1.9
CC-CC-CC-CC-CC-CC
R1
192.168.1.1
11-11-11-11-11-11
ARP
Request
S1 R1
36. Network Protocols and Communications
Summary
In this part, you learned:
Data networks are systems of end devices, intermediary devices, and
the media connecting the devices. For communication to occur, these
devices must know how to communicate.
These devices must comply with communication rules and protocols.
TCP/IP is an example of a protocol suite.
Most protocols are created by a standards organization such as the
IETF or IEEE.
The most widely-used networking models are the OSI and TCP/IP
models.
Data that passes down the stack of the OSI model is segmented into
pieces and encapsulated with addresses and other labels. The process is
reversed as the pieces are de-encapsulated and passed up the
destination protocol stack.
37. Network Protocols and Communications
Summary (cont.)
In this part, you learned:
The OSI model describes the processes of encoding, formatting,
segmenting, and encapsulating data for transmission over the network.
The TCP/IP protocol suite is an open standard protocol that has been
endorsed by the networking industry and ratified, or approved, by a
standards organization.
The Internet Protocol Suite is a suite of protocols required for
transmitting and receiving information using the Internet.
Protocol Data Units (PDUs) are named according to the protocols of
the TCP/IP suite: data, segment, packet, frame, and bits.
Applying models allows individuals, companies, and trade associations
to analyze current networks and plan the networks of the future.
Editor's Notes
#1:Cisco Networking Academy program
Introduction to Networks
Chapter 3: Network Protocols and Communications