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CS101 Introduction to Computing

Lecture 28Introduction to the Internet

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During the Last Lecture

(Computer Networks)

We looked at the role of networks in

computing

We looked at several different types of

networks

We familiarized ourselves with networking

topologies and protocols

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Computer Network

Multiple computers that are

connected together to share

information and otherresources

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Types of Computer Networksaccording to the network access policy

Private

Public

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Types of Computer Networksaccording to the distance between nodes

LAN: Local Area Network

WAN: Wide Area Network

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Network Topologies

The pattern in which computers are connectedto form a network

Popularpatterns:

Point-to-point

Star

Bus

Ring

Networks are also formed by combining 2 or

more of these 4 basic patterns

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Networking Protocols

Networks use protocols, or rules, to exchangeinformation through shared channels

These protocols prevent collisions of datacaused by simultaneous transmission between

two or more computers

Several protocols are available for various

types of networks. Here we discuss two that

are popular for LANs: Ethernet; Token Ring

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Types of Communication Channels

Wire

Wireless

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Wireless (Radio) LANs Are Becoming Popular

Key benefits: Set-up time

Set-up cost

Maintenance cost

Cost Key challenges:

Security & privacy Quality of service

Cost

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Todays Goal:

Introduction to the Internet

To become able to appreciate the role of the

Internet in todays computing

To become familiar with the history and

evolution of the Internet

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an accident!

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This car was involved in that accident

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It belongs to

Mr. Tom Petersof

Palo Alto, California

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After the accident, Mr. Peters

filled out a form, giving info about:

Himself

The circumstances of the accident

Estimated repair expenses

& then

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Mr. Peterss fax machine

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ACME Insurance Groupsserver in New York

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Bhola eServices (Pvt) Ltdsserver at Davis Rd,Lahore

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Claims processing inLahore

4/7

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Bhola eServices (Pvt) Ltdsserver at Davis Rd,Lahore

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ACME Insurance Groupsserver in New York

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Mr. Peterss home PC

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Key Question!

Why process the insuranceclaim in Pakistan?

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Answer: Everybody Wins!

Tom Peters ACME Insurance

Bhola eServices

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Bhola eServices

Lower premium&

Quicker turnaround

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Bhola eServices

Better margins due to

50% saving on claim

processing costs

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Bhola eServices Internal rate of

return (IRR) of60-80%

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The Key Point

Bhola eServices (Pvt) Ltd is

supplying a service

using local, attractively-priced workers

to a remote, overseas client

over the Internet & making good money in the process!

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Internet:

the enabler !

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What else does

the Internetenable?

Wh t El ?

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What Else?

Enables users located at far-way locations toeasily share information with others located all

over the world

Enables users to easily and inexpensively

communicate with others located all over the

world

Enables the users to operate and run programs

on computers located all over the world

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The Internet is unlike

any previous human

invention. It is aworld-wide resource,

accessible to all ofthe humankind.

I t t U W ld id

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Internet Users Worldwide

673M in 2002

1B+ in 2005

(48% wireless)

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1.2M Internet users in Pakistan in 5/2000

(1% of population)

In early 2002,

54% ofAustralian population51% ofSingaporean population

39% ofJapanese population

3% ofChinese population

Key Characteristics (1)

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Geographic Distribution

Global - reaches around the world

Robust ArchitectureAdapts to damage and error

Speed

Data cantravels at near con copper,

fiber, airwaves


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Universal Access

Same functionality to everyone

Growth Rate

The fastest growing technology ever

Freedom of Speech

Promotes freedom of speech

The Digital Advantage

Is digital: can correct errors

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inter net

Internet: Network of Networks

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Internet: Network of Networks

A large number of networks,interconnected physically

Capable of communicating and sharing

data with each other

From the users point view, Internet a

collection of interconnected networks

looks like a single, unified network

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Internet ---- Web

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Internet ---- Intranet

Internet Networking Protocols

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Internet Networking Protocols

Communications on the Internet iscontrolled by a set of two protocols:

TCP and IP

TCP/IP (1)

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TCP/IP (1)Transmission Control Protocol/Internet Protocol

Networking protocol used by allcomputers and

networks on the Internet

Originally developed by the US DoD for Unix,

but now available for most other OSes

TCP/IP (2)

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TCP/IP (2)Transmission Control Protocol/Internet Protocol

TCP breaks down the message to be sent over

the Internet into packets

IP routes these packets through the Internet to

get them to their destination

When the packets reach the destination

computer, TCP reassembles them into the

original message

Tools & Services Available on the Internet

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Tools & Services Available on the Internet

Electronic mail (POP, IMAP, SMTP)

Instant messaging (ICQ, MSN)

Remote login (telnet)

File transfer(ftp)

Network news (nntp)

WWW (http)

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Chronology of events that ledto todays Internet

1960's

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1960 s

1969- DoD-ARPA creates an experimentalnetworkARPANET as a test-bed for

emerging networking technologies

ARPANET originally connected 4 universities &

enabled scientists to share info & resources

across long distances

ARPANET continued to expand throughout the

70's and 80's

1970's

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1970 s

Networking tools developed in the 70's include:

1972 - The National Center for

Supercomputing Apps. (NCSA) develops thetelnet application forremote login, making it

easier to connect to a remote computer

1973 - FTP (File Transfer Protocol) is

introduced, standardizing the transfer of files

between networked computers

1980's

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1980 s

1983- The TCP/IP protocols becomes the onlyset ofprotocols used on the ARPANET

This sets a standard for all networks, andgenerates the use of the term Internet as the

net of nets

ARPANET splits into two nets to keep military

& non-military network sites separate:

ARPANET and MILNET

1980's

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1980 s

In 1982 and 1983, the first desktop computers

begin to appear

Many are equipped with an OS called Berkeley

Unix, which includes networking SW, allowing

easy connection to the Internet using telnet

The PC revolution continues through the 80s,

making access to computer resources & net-

worked info increasingly available to public

1980's

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1980 s

1985-86:NSF connectsthe USs six

supercomputing centers together, calling it thethe NSFNET, orNSFNET backbone

To expand access to the Internet, NSFdeveloped regional nets, which were then

connected to the NSFNET backbone

Plus, NSF supported institutions (universities,

etc.) in their efforts to connect to the regional

nets

1980's

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1980 s

1987 - NSF awards a grant to Merit Network,

Inc. to operate & manage future development

of the NSFNET

Merit collaborates with IBM & MCI on R&D for

fast networking technologies

1989 - The backbone network is upgraded to

T1, making it able to transmit data at speeds of

1.5 Mb/s (approx. 60 pages of text/second)

1990's

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1990 - TheARPANET is dissolved

1991 - Gopheris developed at the U of MN

It provides a hierarchical, menu-based methodforproviding & locating info on the Internet

1993 - CERN releases WWW, developed by

Tim Berners-Lee

It uses HTTP and hypertext, revolutionizing the

way info is presented & accessed on Internet

1990's

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1993 - The NSFNET is upgraded to T3 (45

Mb/s or about 1800 pages/s)

1993-1994 - Web browsers Mosaic & NetscapeNavigator are introduced

Their GUI makes WWW & Internet moreappealing to the general public

1995 - NSFNET is replaced by a newarchitecture, called vBNS which utilizes

regional networks and Network Access Points

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A lot has happenedsince 1995

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Who runs the Internet?

Who owns it?

Todays Goal:

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Today s Goal:

Introduction to the Internet

We looked at the role Internet plays in todays

computing

We reviewed some of the history and

evolution of the Internet

Next Lecture:

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Next Lecture:

Internet Services

We will try to familiarize ourselves with with

some of the Internet services:

http (surfing, shopping, searching) eMail

ftp

News groups, message boards, forums

Instant messaging

Multimedia delivery

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