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The Internet
Concepts covered
•What is the Internet
•History of the Internet
•How does the Internet work
•Getting connected
•Internet applications
James Tam
A Network: A Bunch of Connected Computers
Hub or switch
Router
Hub or switch
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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 Internet
1983 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
NSFNET
(fiber optic)
Arpanet (phone lines)
• 3,000 networks and 200,000 computers
The size of the Internet approximately doubles each year
(Paxson 1994)
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Protocols: The Rules That Make It All Possible
Protocols in real life
• Rules for determining the format of communication
Ciao?
Hello!
Hello?
Bonjour?
Hello!
Hello!
Hola?
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Computer Protocols
Determines the format and method of communication
Internet protocols
• TCP/IP (Transmission Control Protocol/ Internet Protocol)
TCP/IP
•Amiga
•Canada
•Send email
The
Internet
TCP/IP
•Windows
•U.S.A
•Get video
TCP/IP
•PowerPC
•U.K.
•Send picture
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Connecting Your Computer To The Internet
Requires you to sign up with an Internet Service Provider
(ISP)
The Internet
Your
computer
ISP
Types of Internet connections
• Old phone dialup connections
• Faster phone line connections
• Cable connection
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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)
From the The Complete Idiot's Guide to High Speed Internet Connections by Soper
Very slow (300 – 56,000 bps/56Kbps)
Cheap ($20.00/month)
Uses up a phone line
May not allow for a continuous internet connection
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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)
From the The Complete Idiot's Guide to High Speed Internet Connections by Soper
Uses a different sound frequency for each
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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
Upload 32 –
300 Kbps
The Internet
Your
computer
Download 1.5 – 8 Mbps
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Cable Connections To The Internet
Uses a coaxial (cable TV) connection
From the The Complete Idiot's Guide to High Speed Internet Connections by Soper
Employs unused T.V. channels
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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
Dialup
56 Kbps
DSL/ADSL
~128 Kbps – 3 Mbps
Cable Modems
several Mbps (shared)
The Internet
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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 reassembled
The 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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URL's (Continued)
e.g., http://www.ucalgary.ca/~jrtam/personal_pics/hohoho.jpg
http://www.ucalgary.ca/ ~jrtam /personal_pics/ hohoho.jpg
Account: jrtam
THE INTERNET
public_html
ACS Web Server
index.html
personal_pics
hohoho.jpg
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Types Of Domain Names
Suffixes at the end of the url
Generic
com
edu
gov mil
Countries
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: [email protected]
.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
2) Browser connects to
the server with that URL
Sever containing a
web page
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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Summary
How 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
James Tam