Arpanet.53

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Sub topic : ARPANet and WWW

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Recap

In the previous class, you have learnt about

• Definition of a bridge • Importance of a bridge

• Types of bridges

• Functioning of a bridge

• Definition of a gateways

• Function of gateways

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Objectives

On completion this topic, you would be able to know about

• ARPA Net (Advanced Research Project Agency Net)

• WWW (World Wide Web)

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ARPA Network

• Advanced Research Project Agency (ARPA) was established in 1969

• ARPANET was a large wide – area network created by the United States Defense Department

• ARPANET served as a test bed for new networking technologies, linking many Universities and research centers

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• The first two nodes that formed the ARPANET were

UCLA and the Standard Research Institute

• It has evolved into the Internet

• When the ARPANET migrated to the internet protocols in

1983, the major application protocols migrated along

with it

ARPA Network contd….

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E-mail • In 1971, Ray Tomlinson of BBN sent the first network

email

• By 1973, 75% of the ARPA net traffic was email

File Transfer

• By 1973, the File Transfer Protocol (FTP)

specification had been defined and implemented,

enabling file transfer over the ARPANET

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Voice Traffic

• A Network Voice Protocol (NVP) specifications was

also defined (RFC 741) and then implemented

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• Network that has worldwide broadcasting capability, a

mechanism for information dissemination, and a medium for

collaboration , interaction between individuals and their

computers regardless of their geographical location

• The internet is a packet switched global network system that

consists of millions of local area networks and computers

ARPA Network contd….

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• In 1983, the U.S military portion of the ARPANET was

broken off as a separate network the MILNET

• Prior to this the ARPA consists of 113 nodes after that

the MILNET consists of 68nodes

ARPA Network contd….

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World Wide Web (WWW)

• The WWW (world wide web) is a system of interlinked,

hypertext documents accessed via the internet

• With a web browser, a user views web pages that may

contain text, images video and other multimedia

• .WWW are commonly found at the beginning of web

addresses

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• The www today is a distributed client / server service , in

which client using a browser can access a service using

a server

• The service provided is distributed over many locations

called ‘sites’

• Each site holds one or more documents referred to as

web pages

World Wide Web (WWW) contd….

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• A web page is made up of two parts. The head and the

body

• The head is the first part of a web page. The head contains

the title of the page and other parameters that the browser

will use

• The actual contents of a page are in the body, which

includes text and the tag

World Wide Web (WWW) contd….

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• Each web page can contain a link to other pages

• The web pages are written in the HTML language i.e.

Hyper Text Mark up Language

• Web server is a program running on a server computer

World Wide Web (WWW) contd….

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• The web server constantly waits for a request for a web

page from browser program which runs on the client

• HTTP i.e. Hyper Text Transfer Protocol is a protocol

used mainly to access data on the www, which governs

the dialog between the client and server

World Wide Web (WWW) contd….

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Architecture of www

client Site B

Request

Request

Site A

Web page A

Web page B Fig .1

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• Each web page can contain a link to other pages. The

client needs to see some information that belongs to site A

• Site A sends a request through its browser, that is

designed to fetch web documents

• Along other information the request includes the address of

the site and the web page called URL

Architecture of www contd….

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• The URL (Uniform Resource Locator) consists of for example

http// www. yahoo. com / index

Protocol to be used

Domain name space Document / file name

Architecture of www contd….

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• The server at site A finds the document and sends it to

the client

• When the user views the document, she finds some

references to other documents, including a web page at

site B

Architecture of www contd….

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Summary

In this class, you have learnt about

• ARPANET

• WWW and its Architecture

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Quiz

1) URL stands for ____________________________

a) Uniform resource locator

b) Uniform register locator

c) Universal resource locator

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Frequently Asked Questions

1. Explain briefly about www

2. Write short notes on ARPANET