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Introduction to

Computer Networks

Chapter 1

Jetking Infotrain Ltd.

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Chapter Objectives

Explain the need of networks

Explain history of computer networks (ARPANET)

Explain the types of computer networks

Explain Client/Server configuration

Explain layers of OSI model

Explain network selection criteria Application

Explain Standards Organizations


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Computer Network

Interconnection of two or more computers and

peripherals

Allows user to share and transfer information


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Need of Computer Networks

Sharing Resources

Reduced Cost

Reduced time

Scalability

Reliability

Security


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History of Computer Networks(ARPANET)

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 byARPANET


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Types of Computer Networks

Networks are classified depending on thegeographical area covered by the network

ComputerNetworks

LocalArea Network

(LAN)

CampusArea Network

(CAN)

MetropolitanArea Network

(MAN)

WideArea Network

(WAN)


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Local Area Network (LAN) - I

Covers a small area Connects computers and workstations covering a

local area like, office or home


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Local Area Network (LAN) - II

Advantages of LAN: Improves productivity due to faster work

Provides easy maintenance

New systems can be installed and configuredeasily

Disadvantages of LAN:

Limited number of systems can only be connected

Cannot cover large area Network performance degrades as number of

users exceeds


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Campus Area Network (CAN)

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


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Metropolitan Area Network

Interconnects networks within a city

Supports data and voice transmission


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Wide Area Network

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


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Case Study - I

MoneyMaker is a bank having its registered office atDelhi. It has branches at Mumbai, Chennai,Hyderabad and Bangalore. The operating departmentsin the bank are Finance, Insurance, Loan, IT,Marketing, Customer Service and HR. MoneyMakerbank uses LAN as their computer network for eachdepartment. All the branches of the bank from differentcities are connected through WAN. The bank is

expanding and decided to open its branches atdifferent locations in the city.


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Problem

Determine which type of network to be used within a

city


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Suggested Solution

Use LAN computer network for each department in the

new branch. MAN can be used for connecting thedifferent branches of the bank within the city


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Client/Server Configuration

Consists of two elements, Client and Server Server:

A centralized element which provides resources toclient

Manages data, printers or network traffic

Client:

Manages local resources used by users such as

monitor, keyboard, CPU and peripherals


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OSI Model

Run it through CBT


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Network Selection Criteria

Helps to improve network functionality

Network

Criteria

Performance Reliability Security


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Network Applications

Financial Institution (Banking Sector)

Communication Services (Telecom Industry)

Internet Service (WWW, ISP)


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Standards Organizations

Also known as Standards DevelopmentOrganization (SDO)

Develop, maintain, improve and revise standards

Classified as:

International organozations

InternationalOrganization for Standardization (ISO)

National organozations American NationalStandards Institute (ANSI)

Regional organozations Euro-Asian Council forStandardization (EASC)


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Summary - I

Computer network enables the user to share dataand network resources

Network allows remote users to communicate with

each other

Computer networks are divided into LAN, CAN,MAN and WAN depending on the coverage area

LAN is a small network and easy to create Client/Server configuration also called as two-tier

architecture, consist of two nodes, client and server


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SummaryII

OSI model consists of seven layers and providesstandards for computer communication

Physical layer is responsible for actual transmission

of bits over the medium Data Link layer is responsible for node to node

delivery of frames

Network layer is responsible for end to end delivery

of packets, and routing


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Summary - III

Transport layer is responsible for end to end deliveryof the entire message

Session layer is responsible for establishing,

managing and terminating sessions

Presentation layer is responsible for translation,encryption and data compression

Application layer is responsible for providing accessto the network


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Summary - IV

Performance, reliability and security are the network

selection criterion which enables to choose efficientnetwork

Standards organizations like ISO and ANSI developtechnical and non- technical standards

International standards organizations areInternational Standard Organization (ISO),

International Telecommunication Union (ITU),Institute of Electrical and Electronics Engineers(IEEE) and World Wide Web Consortium (W3C)


Documents

Chapter 1 vN.2