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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
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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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Answer: Everybody Wins!
Tom Peters ACME Insurance
Bhola eServices
Lower premium&
Quicker turnaround
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Answer: Everybody Wins!
Tom Peters ACME Insurance
Bhola eServices
Better margins due to
50% saving on claim
processing costs
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Answer: Everybody Wins!
Tom Peters ACME Insurance
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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Key Characteristics (1)
Geographic Distribution
Global - reaches around the world
Robust ArchitectureAdapts to damage and error
Speed
Data cantravels at near con copper,
fiber, airwaves
Key Characteristics (2)
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Key Characteristics (2)
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