This document provides an introduction to computer communication networks. It discusses the motivation to learn about networks, including benefits to business, science, education and industry. The topics to be covered include data communications, networks, the Internet, and protocols and standards. Specifically, it defines data communications and networks, describes the components and flow of data communications, different network types and models, and standards organizations. The Internet is introduced as a global system of interconnected networks that has revolutionized information sharing.

1. Unit 0
[ Prerequisite ]
Introduction
to
Computer Communication Networks

2. Motivation to learn this Subject . . . . . . . . . .
 Business
 Science
 Education
 Industry

3. Topics to be covered in this Introductory Chapter
 Data Communications
 Networks
 Internet
 Protocols & Standards

4. 1-1 DATA COMMUNICATIONS
Data communications collectively refers to the
exchange of data between two devices via some form of
transmission medium ( such as a wire cable ).
Data
 facts and statistics collected together for reference or analysis.
Communication
 the imparting or exchanging of information by speaking, writing, or
using some other medium.
Topics discussed in this section:
a) Effectiveness of a Data Communication System
b) Components
c) Data Representation
d) Data Flow

5. a) Effectiveness of a Data Communication System
The effectiveness of a data communication system depends on
the following four fundamental characteristics :
~ Delivery [ Destination reached should be correct ]
~ Accuracy [ The data should be 100 % same, as it was, when transmitted ]
~ Timeliness [ The delay should be insignificant ]
~ Jitter [ The speed should be uniform for all data packets ]

6. b) Components of Data Communication System
The five important components of Data Communications are :
~ Message [ Message is the information to be communicated ]
~ Sender [ The sender is the device that sends the message ]
~ Receiver [ The receiver is the device that receives the message ]
~ Transmission Medium [ It is the physical path through which a message travels from sender to receiver ]
~ Protocol [ It is a set of rules that govern data communications ]

7. c) Data Representation
The data can come in different forms such as :
~ Text [ e.g. a, b, c, X, Y , Z . ]
~ Numbers [ e.g. 0,1,2 , . . . . . . . 9 ]
~ Images [ e.g. *.jpeg , *.png files ]
~ Audio [ e.g. *.mp3 files ]
~ Video [ e.g. *.mp4 , *.avi files etc.]
Text
Data
Form
Numbers
Audio Images
Video

8. d ) Data Flow

9. 1-2 NETWORKS
What do you mean by network ?
 A network is a set of devices (often referred to as nodes)
connected by communication links.
* A node can be a computer, printer, or any other device capable of sending and/or
receiving data generated by other nodes on the network.
* A link is communication pathway that transfers data from one device to another.
Topics discussed in this section:
a) Distributed Processing
b) Network Criteria
c) Physical Structures
d) Network Models
e) Categories of Networks
f) Interconnection of Networks: Internetwork

10. a) Distributed Processing
 Modern day networks use
distributed processing, in which a
task is divided among multiple
computers.
Note : Contrast this with Centralized Processing

11. b) Network Criteria
~ Performance [ maximum throughput and minimum delay ]
~ Reliability [ the work should continue in spite of any catastrophe ]
~ Security [ Protecting data from manipulation or damage ]

12. c) Physical Structures
~ Type of Connection
[based on type of link]
~ Physical Topology
[based on network’s physical layout ]

13. Type of Connection

14. Physical Topology

15. i) Mesh Topology

16. ii) Star Topology

17. iii) Bus Topology

18. iv) Ring Topology

19. Hybrid Topology

20. d) Network Models
~ OSI Model ( 7 - layer model )
~ Internet Model ( 4 - layer model )

21. e) Categories of Networks
~ Local Area Network ( LAN )
~ Metropolitan Area Network ( MAN )
~ Wide Area Network ( WAN )

22. i) LAN ( Local Area Network )

23. ii) MAN ( Metropolitan Area Network )
Typical Cable TV Network
[ An example of MAN ]

24. iii) WAN ( Wide Area Network )

25. f ) Interconnection of Networks : Internetwork

26. 1-3 THE INTERNET
 The Internet is a communication system that has
brought a wealth of information to our fingertips and
organized it for our use.
 The Internet has revolutionized many aspects of our
daily lives. It has affected the way we do business as
well as the way we spend our leisure time.

27.  Brief History of Internet
~ In mid-1960s’, mainframe computers in research organization were stand-alone devices.
~ In 1967, ARPA ( Advanced Research Projects Agency ) presented the idea for ARPANET.
~ By 1969, ARPANET was a reality. [ Four Universities in USA were interconnected ]
~ In 1973, Vint Cerf and Bob Kahn present the landmark paper outlining the foundations
for TCP/IP.
 Internet Today
~ The Internet has come a long way since the 1960s’. It complexity has grown enormously.
~ It is difficult to give an accurate representation of the Internet because it is continually
changing.
~ Hierarchy in Internet Usage : IISPs’ ⇋ NISPs’ ⇋ RISPs’ ⇋ LISPs’ ⇋ Users’.
Note : ISP stands for Internet Service Provider

28. Hierarchical organization of the Internet
* ISP stands for Internet Service Provider
* NAP stands for Network Access Point

29. 1-4 PROTOCOLS AND STANDARDS
 Protocol
 A protocol is a set of rules that govern data communications
 Standards
~ something that is used or accepted as normal or average.
~ something that is used as a measure, norm, or model in
comparative evaluations.

30.  Standards Organization
 Standards are developed through the cooperation
of standards creation committees, forums, and government
regulatory agencies. A standards organization is one among
these.
( e.g. : ISO / ITU-T / ANSI / IEEE / EIA )
 Internet Standards
 An Internet Standard is a thoroughly tested
specification that is useful to and adhered to by those who
work with the Internet. It is a formalized regulation that
must be followed.