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Chapter 2
Introduction to Computer Networks
INTRODUCTION TO COMPUTER NETWORKS
Learning outcomes
The difference between networks and internets The difference between logical and physical
addresses What is a protocol in the context of computer
networking How protocols are used on remote computers to
communicate easily Explain the concept of layering
– OSI , – TCP/IP and – hybrid models
Reading
Joe Casad, Teach Yourself TCP/IP, Chs 1-2 William Buchana, Mastering the Internet, Ch. 3 Neil Briscoe, Understanding the 7-layer OSI model, July 2000.
– http://pcnetworkadvisor.com Julian Moss, Understanding TCP/IP (first part September 1997)
– http://pcnetworkadvisor.com
What is a network?
A network consists of two or more computers connected by network media
– .i.e cables, telephone lines, radio waves– share the same resources such as database, printer– Exchange files – Exchange electronic message between each others
Example of a simple network
How are they linked?
Computers on a network may be linked through:
– cables, – telephone lines, – radio waves, satellites or – wireless technologies
Router
An example of a network
Internet
Segment Node
Hub
Hub
Bridge
Applications of Networks
Introduction to Computer Networks
Resource SharingHardware (computing resources, disks, printers)Software (application software)
Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)
CommunicationEmailMessage broadcast
Remote computing
Distributed processing (GRID Computing)
Categories of networks
• A LAN is a network that is used for communicating among computer devices, usually within an office building or home
• LAN’s enable the sharing of resources such as files or hardware devices that may be needed by multiple users
• Is limited in size, typically spanning a few hundred meters, and no more than a mile
• Is very fast, with speeds from 10 Mbps to 10 Gbps
• Requires very little wiring, typically a single cable connecting to each device
• Has lower cost compared to MAN’s or WAN’s
Local Area Network
LAN
LAN (Continued)
• MAN is designed extended over an entire city.
• May be wholly owned and operated by a private company, or it may be a service provided by a public company, such as a local telephone company.
Metropolitan-Area Networks (MAN)
•Provides long-distance transmission of data, voice, image, and video information over large geographic areas
Wide-Area Networks (WAN)
WAN (Continued)
– WANs connect larger areas, such as whole states, or even the world.
– Transoceanic cables and satellites are used to connect WANs