Educational Computing

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EducationalComputing
CIS 204Fall 2008

• David Goldschmidt, Ph.D.
• Computer Science
• The College of Saint Rose

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Networks

• Hierarchical Networks
• Nodes are not equal
• Nodes interconnect instrict pattern
• Single point of failure
• Heterarchical Networks
• Nodes interconnected at random
• No node is more important than another

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The Internet

• Internet is a global decentralized heterarchical
  network made up of many smaller networks
• Information Superhighway
• Originally developed in 1960s as ARPANET
• Advanced Research Projects Agency NETwork
• Continued linked computer availabilityin case of
  nuclear attack
• Use in academia led to e-mail, file transfer,
  Web, etc.

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Internet Backbone Network
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Internet Service Providers

• Internet Service Providers (ISPs) have direct
  connections to (or are part of ) the Internet
• ISPs sell temporary Internet accessto businesses
  and individuals
• Telephone access numbers
• Time Warner Cable
• Digital Subscriber Line (DSL)
• Leased line (e.g. T1, T3) through telephone
  company
• Satellite

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Digital and Analog Communications

• Original telephone infrastructure designed to
  carry analog signals (voice)
• Modems translateanalog to digitaland digital to
  analog
• Digital modems use newer infrastructure
• e.g. fiber-optic cables
• No more analog....

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Internet Service Providers
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Internet Service Providers
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Local Area Networks

• Local Area Network (LAN) is a networkof machines
  coveringa limited geographicalarea
• Metropolitan AreaNetwork (MAN)covers more
  denselypopulated area

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Wide Area Networks

• Wide Area Network(WAN) covers multiplelocations
• Each location consistsof a LAN or MAN
• LANs and WANs areoften private networks

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The Internet as Global WAN

• The Internet is the worlds largest network
• Links millions of businesses, governments,educati
  onal institutions, and individuals

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How the Internet Works
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Internet Protocols

• What is a protocol ?
• A protocol describes how communicationshould
  take place
• e.g. Roberts Rules of Orders
• Transmit data over the Internet using 2
  protocols
• Transmission Control Protocol (TCP), which
  provides error handling, packet resubmission,
  etc.
• Internet Protocol (IP), which provides
  low-level packet-based communications

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Internet Addresses

• An Internet Addresses identifiesmachines on the
  Internet
• Numeric addresses
• e.g. 66.195.8.30, 128.113.2.9
• Non-numeric addresses
• e.g. www.strose.edu, www.rpi.edu

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Internet Addresses
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Use of the Internet

• How is the Internet used?
• File Transfer Protocol (FTP)
• E-mail
• Interactive Chat / Instant Messaging
• Newsgroups (e.g. USENET)
• Internet Telephony
• Videoconferencing
• World Wide Web

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Billions and Billions Served....
to be continued....