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York University
Natural Science
NATS 1775
Vera Pavri

Copyright © 2009 Vera Pavri Internet Technology I. Internet Technology - Studying history of Internet shows us again how users shape technological systems; also allows us to explore complex (but interesting) world of technical standards - Recall that standards are important because they assure consumers that there will some compatibility for competing technologies worldwide - Standards are equated with product equality, reliability, safety, efficiency and interchangeability - DE FACTO standard: usually first “standard” out on market that is followed for convenience - Internet is large and complicated system - local computers hooked up to regional, national and international computing systems - each computer is “node” on the network, and all computers connected to each other through variety of technical means such as fiber optic cables, microwave transmissions or satellite technology - computers communicate with each other by using machine language standards such as TCP/IP protocol - messages are transmitted through packet-switching, whereby information is broken up into bits and transmitted according to computer capacity - packets are labeled with a final destination address, and are finally reassembled at receiving computer - while messages automatically routed, they are managed by systems’ administrator who makes sure machinery is functioning II. Packet-Switching Technology - development of Internet starts with creation of ARPANET in the 1960s - happened within the United States Department of Defense (DOD) - Advanced Research Project Agency ([D]ARPA), a division of DOD, was given mandate to create new communications system that would connect various computing research communities across the country; wanted system that would be able to withstand possible attack - network originally intended to aid scientists who were having difficulties running programs on remote computers - what was created was ARPANET, a decentralized communications system based on packet-switching technology that allowed for reliable data communications - technology based on military goals of survivability, flexibility and high performance - this was in contrast to more commercial goals such as low cost, simplicity or consumer appeal Copyright © 2009 Vera Pavri - packet-switching technology developed in both the United States (Paul Baran) and Britain (Donald Davies) in mid 1960s - Baran: believed conventional communications systems (i.e. telephone network) was too concentrated and hierarchal - For instance, circuit switching technology used for telegraphy and telephony whereby messages send through a “fixed” route - destroying on part of system would therefore cause problems all over - Baran wanted digital system where message labeled and then passed through network (i.e. post office); nodes determine routes automatically and there is no need for human intervention - packet switching: digital packets that act like message blocks - This kind of system was a distributed system whereby messages would be “packeted” and send via different routes - redundant components of system compensate for any failures - Davies: different priorities; wanted to improve interactive computing - did not envision system for military use; thought new network could compete for business market - despite fact that idea for packet switching occurs almost simultaneously, Davies never able to build national network, techniques don’t go beyond National Physics Lab - more successful in US because British institutions were eager to create viable commercial technology - did so at expense of further research and development - Britain only begins working on packet-switching services in 1970s but by this time, using American technology - in contrast, individuals like Baran working within umbrella of US military were left alone with ample resources to eliminate “kinks” in the technology - allowed technology to mature - political and cultural climate within key British institutions thus inhibited growth of packet switching technology in country III. The Creation of the ARPANET - ARPANET: distributed network (i.e. one computer is connected to at least two others) where messages are distributed via packet switching technology - most successful aspects of ARPANET: high speed transmission, adaptive routing and efficient packet switching - use of small fast, computers to help overcome limits of older communications systems - Lawrence Roberts first recruited by ARPA to work on project; had informal management style - overcame many technical difficulties that came with linking all research communities via layering - example: use of minicomputers to serve as nodes of network; each host computer attached to minicomputer Copyright © 2009 Vera Pavri - network of minicomputers called interface message processors (IMP); would be connected via telephone lines - simplifies packet switching programming: write for IMP network as opposed for all different types of hosts - host: responsible for content of packages; IMPS: handle packet switching operations - thus basic infrastructure of ARPANET: time sharing hosts, packet switching interface message processors, telephone lines to connect IMPS - eventually, IMPS able to hand multiple hosts; by 1971 Roberts tries to modify system to make it accessible to users who don’t have hosts - TIP: new version of IMP which allows any user to access host on network - network control center of ARPA also allows group to control aspects of communications system: cost, connection setup, reliability - host functions also represent Robert’s focus on “layering”: - a. host layer: general purpose protocol sets up communications b/w hosts - b. applications layer: specify protocols for network applications such as remote login or file transfer - ARPANET officially launched in 1969 when four host computers are connected at the University of California - ARPA able to get funding by emphasizing military possibilities of system - initially, ARPANET created as way for researchers to “share” computers via remote login
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