Computer Network Basics

Introduction to Computer Networks

Objectives

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Need of networks

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History of computer networks (ARPANET)

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Types of computer networks

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Client/Server configuration

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Layers of OSI model

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Applications

Computer Network 

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Interconnection of two or more computers and peripherals Allows user to share and transfer information

Need of Computer Networks      

Sharing Resources Reduced Cost Reduced time Scalability Reliability Security

History of Computer Networks (ARPANET) 

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ARPA designed for Department of Defense (DOD), US Small computers were connected to large mainframe computers IMPs were connected to each other through modem Supported different operating systems Telenet and ftp services was provided by ARPANET

Types of Computer Networks 

Networks are classified depending on the geographical area covered by the network Computer Networks

Local Area Network (LAN)

Campus Area Network (CAN)

Metropolitan Area Network (MAN)

Wide Area Network (WAN)

Local Area Network (LAN) - I  

Covers a small area Connects computers and workstations covering a local area like, office or home

Local Area Network (LAN) - II 

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Advantages of LAN:  Improves productivity due to faster work  Provides easy maintenance  New systems can be installed and configured easily Disadvantages of LAN:  Limited number of systems can only be connected  Cannot cover large area  Network performance degrades as number of users exceeds

Types of LAN 

LANs are classified depending on the techniques used for data sharing LAN Types

Ethernet

Token Ring

Token Bus

FDDI

Campus Area Network (CAN)  

Made up of multiple LANs within limited area Connects different LANs in a campus

Metropolitan Area Network  

Interconnects networks within a city Supports data and voice transmission

Wide Area Network 

Covers a wide geographical area which includes multiple computers or LANs e.g. Internet

Client/Server Configuration  

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Consists of two elements, Client and Server Server:  A centralized element which provides resources to client  Manages data, printers or network traffic Client:  Manages local resources used by users such as monitor, keyboard, CPU and peripherals

Open System Interconnection (OSI) Model

Network Applications   

Financial Institution (Banking Sector) Communication Services (Telecom Industry) Internet Service (WWW, ISP)