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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 other resources

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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 connected to form a network

• Popular patterns:– 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 exchange information through shared channels

• These protocols prevent collisions of data caused 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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Today’s Goal:Introduction to the Internet

• To become able to appreciate the role of the Internet in today’s 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 Peters

of

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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1/ 7

Mr. Peters’s fax machine

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2/ 7

ACME Insurance Group’s server in New York

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3/ 7

Bhola eServices (Pvt) Ltd’s server at Davis Rd, Lahore

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Claims processing in Lahore

4/ 7

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5/ 7

Bhola eServices (Pvt) Ltd’s server at Davis Rd, Lahore

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6/ 7

ACME Insurance Group’s server in New York

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7/ 7

Mr. Peters’s 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) of 60-80%

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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 Internet

enable?

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What Else?

• Enables users located at far-way locations to easily 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 a world-wide resource, accessible to all of the humankind.

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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% of Australian population

51% of Singaporean population39% of Japanese population3% of Chinese population

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Key Characteristics (1)

Geographic Distribution

Global - reaches around the world

Robust Architecture

Adapts to damage and error

Speed

Data can travels at near ‘c’ on copper, fiber, airwaves

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Key Characteristics (2)

Universal AccessSame functionality to everyone

Growth RateThe fastest growing technology ever

Freedom of SpeechPromotes freedom of speech

The Digital AdvantageIs digital: can correct errors

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inter.net

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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 user’s 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?

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Internet Networking Protocols

Communications on the Internet is controlled by a set of two protocols: TCP and IP

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

• Networking protocol used by all computers and networks on the Internet

• Originally developed by the US DoD for Unix, but now available for most other OSes

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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

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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 led to today’s Internet

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1960's

1969 - DoD-ARPA creates an experimental network – ARPANET – 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

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1970's

Networking tools developed in the 70's include:

1972 - The National Center for Supercomputing Apps. (NCSA) develops the telnet application for remote 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

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1980's

1983 - The TCP/IP protocols becomes the only set of protocols used on the ARPANET

This sets a standard for all networks, and generates 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

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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 80’s, making access to computer resources & net-worked info increasingly available to public

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1980's

1985-86: NSF connects the US’s six supercomputing centers together, calling it the the NSFNET, or NSFNET backbone

To expand access to the Internet, NSF developed 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

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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)

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1990's

1990 - The ARPANET is dissolved

1991 - Gopher is developed at the U of MN

It provides a hierarchical, menu-based method for providing & 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

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1990's

1993 - The NSFNET is upgraded to T3 (45 Mb/s or about 1800 pages/s)

1993-1994 - Web browsers Mosaic & Netscape Navigator are introduced

Their GUI makes WWW & Internet more appealing to the general public

1995 - NSFNET is replaced by a new architecture, called vBNS which utilizes regional networks and Network Access Points

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A lot has happened since 1995

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Who runs the InternetWho runs the Internet??

Who owns itWho owns it??

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Today’s Goal:Introduction to the Internet

• We looked at the role Internet plays in today’s computing

• We reviewed some of the history and evolution of the Internet

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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