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

·        Backbones

MCI Worldcom

GTE

Sprint

·        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)

   Namibian.com.na

 

 

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

   Gopher

   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