The Internet - University of Calgary by panniuniu


									            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


                Hub or switch

                                            James Tam
The Internet: A Gigantic Network of Networks

                                               James Tam
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)

                                                               James Tam
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

                                                               James Tam
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           James Tam
Birth And Growth Of The Internet
• 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'.

• 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                              Arpanet (phone lines)
    (fiber optic)
                                                                            James Tam
Birth And Growth Of The Internet (Continued)
1990 The original Arpanet abandoned in favour of the higher
speed connections of the NSFNET

 NSFNET                           Arpanet (phone lines)
 (fiber optic)

• 3,000 networks and 200,000 computers

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

                                                           James Tam
Protocols: The Rules That Make It All Possible
Protocols in real life
  • Rules for determining the format of communication   Ciao?


                                           Hello!       Hola?

                                                             James Tam
Computer Protocols
Determines the format and method of communication

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

              TCP/IP               The              TCP/IP

•Send email                     TCP/IP                         •Send picture

                   •Get video                                           James Tam
Connecting Your Computer To The Internet
Requires you to sign up with an Internet Service Provider

                                        The Internet

   Your               ISP

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

                                                            James Tam
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

                                                           James Tam
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

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

                                                            James Tam
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

                                                           James Tam
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

                                                                                  James Tam
DSL/ADSL (Continued)
Faster than regular dialup
• ~ 100's Kbps – several Mbps

Allows for a continuous internet connection

                                              James Tam
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 –                    The Internet
                    300 Kbps

                    Download 1.5 – 8 Mbps

                                                                            James Tam
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

                                                                                  James Tam
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

                                                                       James Tam
Cable Connections To The Internet (Continued)
Problem: You are not alone in your cyberspace connection
Dialup    DSL/ADSL                    Cable Modems
56 Kbps   ~128 Kbps – 3 Mbps          several Mbps (shared)

                               The Internet

                                                              James Tam
Speed Of Your Internet Connection

                         The Internet

 It is limited by the speed of the slowest path
                                                  James Tam
Characteristics Of The Internet
Dynamic routing

Delivery of information through packets

                                          James Tam
The Internet: Dynamic Routing

                        The Internet

 As long as the source and destination are connected to the
 Internet the information will be transmitted
                                                              James Tam
Tracing The Route Of Your Packets: tracert /

    U of C             Telus           Sprint

                                                James Tam
 The Internet: Packets (Real-life analogy)

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

                                                                                  James Tam
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


                    ?                  ?

                        The Internet

                                                          James Tam
The Internet: Packets (Continued)
At the destination the packets are checked and reassembled
                      The Internet


                                                             James Tam
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

                                                                            James Tam
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.

                                                                               James Tam
HTML (Hypertext Mark-up Language)
Used to create typical web pages

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

• Style instructions (e.g., bolding or italicizing text, bulleting lists, inserting
  images etc)

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

                                                                                      James Tam
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>


http            – indicates a hypertext document (a web page) - a place on the world wide web (web sever)

                                                                        James Tam
URL's (Continued)
 e.g., ~jrtam /personal_pics/ hohoho.jpg

                                       Account: jrtam


  ACS Web Server                                        personal_pics


                                                                        James Tam
Types Of Domain Names
Suffixes at the end of the url
                  Generic                Countries

com     edu    gov   mil    org   net   ca    jp

 edu…educational institutes
 gov..the U.S. federal government
 mil…U.S. armed forces
 org…non-profit organizations
 net…Network providers

                                                     James Tam
Addresses similar to web addresses

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

 .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

  login name for cpsc network

                                                                    James Tam
 The World Wide Web: Web Servers
Computer running                       Sever containing a
web browser –                          web page
person clicks on link

1) Browser determines URL
                                       3) The server sends back
2) Browser connects to                 information about the link (web
the server with that URL               page)
4) The browser displays the web page

                                                                         James Tam
Plug-ins For Web Browsers
Extend the basic features of web browsers

Can be downloaded from the web

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

                                            James Tam
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:

                                                             James Tam
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

                                                                 James Tam
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

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