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					            Introduction
                 CST 415




10/1/2012    CST 415 - Computer Networks   1
Topics
   •    Definitions
   •    TCP/IP Internet
   •    Internet Services
   •    Networking History
   •    IAB
   •    RFC



 10/1/2012         CST 415 - Computer Networks   2
Definitions
   Network

         Any collection of items tied together through
          some media allowing transfer from one item to
          the next.




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Definitions
   What are some networks?

         –   Telephone network
         –   Utility Network
         –   Satellite Network
         –   Other?




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Definition
   Computer Network

         A collection of computers tied together by some
          media to allow information exchange.

             What is the simplest computer network you can think
              of?


             What is the media used for information exchange in
              this network?
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Definition
   Protocol

         The customs and regulations dealing with the
          ceremonies and etiquette of the diplomatic
          courts and others at a court or capital.

             How does protocol relate to network
              communications?


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Definition
   Protocol

         In general, protocol deals with rules and
           regulations that must be followed for two parties
           to get along and communicate.

         In data communications, protocol deals with:
         – Message format
         – Message sequence
         – Rules governing message transfer
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Definition
   To have a computer network, we must have:
         – At least two computers.
         – The two computers are tied together via some
           communication media.
         – The communications between the computers
           must behave according to some set of
           communication rules (the communication
           protocol).


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Definition
   Exercise

         – Define a media
         – Given this media
             » Define a method of information encoding
             » Define a standard to allow
                 Unreliable exchange of information
                 Reliable exchange of information



         Write your message definitions, sequencing, and rules
          down. Hand this in at the beginning of next class.
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TCP/IP Internet
   Although there are many computer
    communication protocols –
             » NetBEUI
             » ISO OSI
             » etc.


   The Internet is primarily based on the protocol
    TCP/IP (Transmission Connect
    Protocol/Internet Protocol)
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TCP/IP Internet
   The TCP/IP Internet is an example of a “de-facto”
     standard.

   At the time of the Internet’s emergence, there was a
     competing standard ISO OSI (International
     Standards Organization Open Systems
     Interconnect).

   ISO OSI was defined by a standards committee.

   TCP/IP was developed and defined “in-place” as part
     of a research project.
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TCP/IP Internet
   As has been seen in many other areas of computer
     technology, the ISO Standards Committee
     attempted to define a protocol that was “something
     for everybody”.

   This slowed the implementation of the standard as
     well as caused it to bloat.

   TCP/IP grew out of an implementation.

   TCP/IP won the Internet because it was already there.
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Internet Services
   • Internet Services are based on protocols.
      – Application-Level Services (Application
        Layer)
             » FTP (File Transfer Protocol)
             » Telnet (Remote Login)
             » HTTP (Hyper Text Transfer Protocol)
             » POP (Post Office Protocol)
             » SMTP (Simple Mail Transfer Protocol)

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Internet Services
   • Internet Services are based on protocols.
         – Network-Level Services (Network Layer)
             » Connectionless Packet Delivery
                 Packets are delivered through what is known as a virtual
                  circuit.
                 This means the path between node A and B could change
                  at any time during network based communication.
                 What are the ramifications of such a scheme?

             » Reliable Stream Transport
                 Delivery of information is guaranteed to arrive at the
                  network destination end-point in the order in which it was
                  sent.
                 Applications do not need to worry about checking delivery
                  status and buffering data until it is all delivered.
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Internet Services
   • TCP/IP Features
         – Technology Independent : Drivers can be
           written for any underlying physical transport
           mechanism.
         – Universal Interconnect : Any computer on the
           network is recognized due to a standardized
           address mechanism.
         – End-to-end Connectivity : Messages pass from
           source to destination and are acknowledged as
           such. Intermediate routing does not change
           delivery.
         – Standardized Applications : e-mail, ftp, etc.
 10/1/2012            CST 415 - Computer Networks     15
Historical Perspective
 Year                                                       Event
 1966    ARPA packet-switching experimentation done
 1969    First ARPANET nodes go operational.
 1972    Network based e-mail written by Ray Tomlinson and brought on-line.
 1973    First non-US computer linked to the ARPANET
 1975    ARPANET transferred to the DOD to become DARPANET.
 1980    TCP/IP protocol experimentation begins
 1981    Every 20 days, a now host computer is added to the DARPANET.
 1983    DARPANET is switched over to use the new TCP/IP protocol suite.
 1986    NSF funds and creates the NSFnet to connect 6 supercomputer centers.
 1990    ARPANET is retired
 1991    Gopher introduced, WWW invented, PGP released
 1992    Mosaic released after being developed by Mark Andreasson et. al. at NCSA.
 1995    Internet backbone goes private.
 1996    OC-3 (155 Mbps) backbone built.
 1998    Number of registered domain names exceeds 2 million
 2000    Number of indexable web pages exceeds 1 billion. – currently at 11.5 billion

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 Historical
 Perspective

Internet growth from
1981 through 2000
plotted on a log scale
illustrates the
exponential growth.




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IAB
  The IAB (Internet Architecture Board) was founded
    in 1983 to oversee the coordination of the TCP/IP
    protocol suite.

  Goals:
  • Encourage exchange of ideas.
  • Focus common objectives for research activities.
  • Control direction of network based technologies


10/1/2012         CST 415 - Computer Networks      18
RFC
  Internet Requests For Comments

  • A series to technical papers covering the TCP/IP
    Protocol suite.
  • These papers chronicle the work done on the
    TCP/IP protocol standard as well as work intended
    for future research.
  • RFCs are located at http://www.rfc-editor.org


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RFC
  By 1989, the work in networking had become so
    large that the informal RFC method for
    communication and standardization no longer
    worked.

  Two groups were introduced:
  • IRTF (Internet Research Task Force) : concentrates on long
    term research.
  • IETF (Internet Engineering Task Force) : concentrate on
    short-term engineering issues.

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RFC
  To get a standard:

  1.        The basic idea must be explained in an RFC.
  2.        The RFC must generate enough interest to warrant
            consideration.
  3.        The RFC will then be advanced to a Draft Standard.
  4.        A reference implementation must be produced and tested.
  5.        If the software is sound and the idea works, the IAB will
            advance the Draft Standard to become a Standard.


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RFC




            The 802 working groups. The important ones are
              marked with *. The ones marked with  are
             hibernating. The one marked with † gave up.
10/1/2012                 CST 415 - Computer Networks        22

				
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