Class Notes (837,484)
Canada (510,274)
York University (35,409)
Natural Science (2,813)
NATS 1775 (361)
Vera Pavri (352)


6 Pages
Unlock Document

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
More Less

Related notes for NATS 1775

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.