James Tam

The Internet

Concepts covered

•What is the Internet

•History of the Internet

•How does the Internet work

•Getting connected

•Internet applications

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A Network: A Bunch of Connected Computers

Hub or switch

Hub or switch

Router

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The Internet: A Gigantic Network of Networks

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Arpanet: The Parent of the Internet

Research network (U.S. Department of Defense)

Huge network• Eventually spanned much of the U.S.

Designed to remain functional in the case of disaster or war• Existing system (single path connection)

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Arpanet (Continued)

Designed to remain functional in the case of disaster or war• New system (multiple paths – allows for alternatives)

Designed to transport many kinds of data

Initiated and completed during the cold war• Started in 1957 in response to the Soviet space program• First went on the air in the summer of 1969

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Growth Of The Arpanet Over Time

a) December 1969 b) July 1970 c) March 1971

d) April 1972 September 1972

From Computer Networks by Tanenbaum

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Birth And Growth Of The Internet1983 MILNET• The military portion of the Arpanet separates into it's own network

Mid 1980's• People began to view the Arpanet network as 'the Internet'.

1986 NSFNET• Designed by the U.S. National Science Foundation (NSF) as a high speed

successor to the Arpanet• Created as it's own network connected to the Arpanet and increased it's

overall speed.

NSFNET (fiber optic)

Arpanet (phone lines)

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Birth And Growth Of The Internet (Continued)

1990 The original Arpanet abandoned in favour of the higher speed connections of the NSFNET

• 3,000 networks and 200,000 computers

The size of the Internet approximately doubles each year (Paxson 1994)

NSFNET (fiber optic)

Arpanet (phone lines)

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Protocols: The Rules That Make It All Possible

Protocols in real life• Rules for determining the format of communication

Hello?Hello!

Hello!

Hello!

Ciao?

Bonjour?

Hola?

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Computer Protocols

Determines the format and method of communication

Internet protocols• TCP/IP (Transmission Control Protocol/ Internet Protocol)

•Amiga•Canada•Send email

The Internet

•PowerPC•U.K.•Send picture

•Windows•U.S.A•Get video

TCP/IP TCP/IP

TCP/IP

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Requires you to sign up with an Internet Service Provider (ISP)

Types of Internet connections• Old phone dialup connections• Faster phone line connections• Cable connection

Connecting Your Computer To The Internet

The Internet

Your computer

ISP

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Old Phone Dialup Connections

Having your computer call another computer to connect to the Internet

Problem: Phone lines and computers don't easily mix

From the The Complete Idiot's Guide to High Speed Internet Connections by Soper

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Old Dialup Connections (Continued)

Requires a modem (modulator/demodulator)

Very slow (300 – 56,000 bps/56Kbps)

Cheap ($20.00/month)

Uses up a phone line

May not allow for a continuous internet connection

From the The Complete Idiot's Guide to High Speed Internet Connections by Soper

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Faster Phone Line Connections

Types of fast phone line connections• ISDN (Integrated Services Digital Network)• DSL (Digital Subscriber Line) - ADSL (Asymmetrical DSL)

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ISDN (Integrated Services Digital Network)

Allows internet connections at about twice the max speed of a regular modem connection (128 Kbps)

Allows for a dialup internet connection

An older technology being replaced by DSL

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DSL/ADSL

Uses a single wire for voice and data (computer)

Uses a different sound frequency for each

From the The Complete Idiot's Guide to High Speed Internet Connections by Soper

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DSL/ADSL (Continued)

Faster than regular dialup• ~ 100's Kbps – several Mbps

Allows for a continuous internet connection

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DSL/ADSL

ADSL (Asymmetrical DSL)• You can download information (get information from the internet) faster

than you can upload it (send information somewhere to the internet)• Costs about $35.00/month

The Internet

Your computer

Upload 32 – 300 Kbps

Download 1.5 – 8 Mbps

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Cable Connections To The Internet

Uses a coaxial (cable TV) connection

Employs unused T.V. channels

From the The Complete Idiot's Guide to High Speed Internet Connections by Soper

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Cable Connections To The Internet (Continued)

Fast connection • "100 times faster than dialup" • approximately several Megabits (1 – 3 Mbps) per second download• Approximately several hundred thousand Kilobits (200 – 300 Kbps)

upload

A bit more ($40.00/month plus installation)

Allows for a continuous internet connection

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Cable Connections To The Internet (Continued)

Problem: You are not alone in your cyberspace connection

The Internet

Dialup 56 Kbps

DSL/ADSL~128 Kbps – 3 Mbps

Cable Modemsseveral Mbps (shared)

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Speed Of Your Internet Connection

The Internet

It is limited by the speed of the slowest path

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Characteristics Of The Internet

Dynamic routing

Delivery of information through packets

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The Internet: Dynamic Routing

The Internet

As long as the source and destination are connected to the Internet the information will be transmitted

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Tracing The Route Of Your Packets: tracert / traceroute

U of C Telus Sprint

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The Internet: Packets (Real-life analogy)

From the The Complete Idiot's Guide to High Speed Internet Connections by Soper

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The Internet: Packets

Information sent on the Internet is broken down into packets

The packets may or may not be sent along the same route from the source to the destination

Source

? ??

The Internet

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The Internet: Packets (Continued)

At the destination the packets are checked and reassembledThe Internet

Destination

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The Internet Society

An international professional organization headed by a Board of Governors

A portion of the Internet Society's mission• To promote the use of the Internet• To facilitate the development of standards, protocols and administration of

the Internet• …

Not a managing organization!For further details http://www.isoc.org

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The Internet: Applications

Original set of applications of the Internet• Email• News• Remote login (telnet, rlogin and ssh, Stel) – lets you login to a computer

from outside the network• File transfer (ftp, ssh) – download / upload information

World Wide Web (WWW)• Consisted of documents containing text, pictures, sound, video and links to

other documents.

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HTML (Hypertext Mark-up Language)

Used to create typical web pages

Hypertext• Points to another document (indicated through the URL)• Documents end with the suffix ".html"

Mark-up• Style instructions (e.g., bolding or italicizing text, bulleting lists, inserting

images etc)

Language• HTML is not a programming language!• It's a language that allows you to create documents that will be a part of the

WWW

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URL's (Uniform Resource Locator)

Provide a standardize way of describing information

Parts of a url (each part is enclosed by angled brackets)

<protocol> <machine where document is located> <path to the document>

e.g., http://www.gamespot.com

http – indicates a hypertext document (a web page)

www.gamespot.ca - a place on the world wide web (web sever)

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THE INTERNET

URL's (Continued)

ACS Web Server

http://www.ucalgary.ca/

index.html

Account: jrtam

public_html

~jrtam /personal_pics/

personal_pics

hohoho.jpg

hohoho.jpg

e.g., http://www.ucalgary.ca/~jrtam/personal_pics/hohoho.jpg

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Types Of Domain Names

Suffixes at the end of the url

Generic Countries

com

edu gov mil org net ca jp

com…commercial

edu…educational institutes

gov..the U.S. federal government

mil…U.S. armed forces

org…non-profit organizations

net…Network providers

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Email

Addresses similar to web addresses

Three main parts:

Format: <person's name> @ <host>.<domain>

Example: tamj@cpsc.ucalgary.ca

.ca…top level domain (Canada)

ucalgary…domain name for the University of Calgary

cpsc…the name of the Computer Science network at the U of C

tamj..my login name for cpsc network

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The World Wide Web: Web Servers

Computer running web browser – person clicks on link

1) Browser determines URL

Sever containing a web page

2) Browser connects to the server with that URL

3) The server sends back information about the link (web page)

4) The browser displays the web page

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Plug-ins For Web Browsers

Extend the basic features of web browsers

Can be downloaded from the web

Examples:• QuickTime (Apple) • RealPlayer (Real)• ShockWave Flash (Macromedia)• Acrobat (Adobe)

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Internet2

A non-profit consortium of 190 universities partnered with industry and government

Goal is not to replace the Internet but to improve it

For more information see: http://www.internet2.edu

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Intranets

A mini version of the Internet

Provides the features of the Internet (e.g., web pages) but is self enclosed• Cannot be accessed from the outside• Uses the protocols of the Internet

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SummaryHow the Internet can be viewed as a vast network of networks

The origins of the Internet and how did it evolve into its present (and still evolving state)

How is the Internet interconnected and how is information transmitted across it (packets, dynamic routing)

What are the different ways of establishing a connection to the Internet• Dialup, DSL/ADSL, Cable

What are the main applications of the Internet

Email, File Transfer, Remote Login, News, The World Wide Web