History of the Internet


Source www.isoc.org/internet/history/brief.shtml


1962 concept of large network

1964 concept of packet switching

1967 work starts at DARPA

1968 ARPANet original specs

1969 four computers connected to ARPANet UCLA, Stanford, UCSB, and Utah

1972 ARPANet public demo and email used

1973 TCP/IP defined for ARPANet

Other defining features:

   Local networks can maintain own protocols

   Error packets retransmitted from source

   No global control of the network

   32 bit address with 8 bits to designate target network

1983 TCP/IP becomes official protocol for ARPANet

1985 Internet Protocol being used by other networks, especially NSFNet

1990 --ARPANet decommissioned

1995 -- NSF stops funding the NSFNet backbone. The Internet is now private.



Internet Architecture

        Packet switching v circuit switching

        Distributed resources v Star topology


MCI Worldcom



        Internet Service Providers (ISP)


Internet Addresses

      Domain Name System (DNS)

   Legal aspects

   Technical aspects

   Top-level or zone (.com, .mil, .edu)

   Vaxa.oshkosh.edu (US assumed)




Message Movement

        Message broken into packets

        Packets sent independently

        Packets reassembled and reordered at receiving machine

        Each router forwards message using optimal path (determined by hop count, proximity, queue length, and priority).



IP Headers

      Encapsulated packet begins with these fields:

    IP Version ( 4 bits, currently v4)

    Header length (4 bits, normally 20 bytes)

    Priority level (7 bits)

    Packet length (16 bits 65,535 byte max)

    Packet ID # (16 bits)

    Flag (3 bits last or more fragments)

    Fragment offset (12 bits used in packet reassembly)

   Time to Live (8 bit hop count)

   Protocol of next layer (8 bits)

   Parity check (16 bits)

   Source address (32 bits)

   Destination address (32 bits)

(32 bits can encode an address no larger than 4,294,967,296 or 2**32)


Internet Services

      E-mail and listservs

      Remote log-in Telnet

      Information Retrieval

   FTP File transfer protocol


   World Wide Web


History of the Web

      Tim Berners-Lee (CERN) 1989

   Hypertext linkage of technical documents

      Marc Andreeson U of Illinois

   Mosaic Browser

   Later founded Netscape



Functions of a Browser

             Display name of URLs

             Translate name to Internet address

             Request service of server holding document

             Copy document to local computer

             Display document