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Computer Networks

Computer Networks. Instructor: Bruhadeshwar Monsoon 2007. Design Motivation. “ While highly survivable and reliable communications systems are of primary interest to those in the military concerned , (for automated decision making) ,…,

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Computer Networks

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  1. Computer Networks Instructor: Bruhadeshwar Monsoon 2007

  2. Design Motivation “While highly survivable and reliable communications systems are of primary interest to those in the military concerned, (for automated decision making),…, the basic notions are also of interest to communications systems planners and designers having need to transmit digital data” –Paul Baran, August 1964

  3. The Necessity: Time Sharing “Time sharing tried to make it possible for research institutions to use the processing power of other institutions computers when they had large calculations to do that required more power, or when someone else's facility might do the job better” -Ian Peter (www.nethistory.info)

  4. Networking History • Origins of Internet are hazy, visit www.nethistory.info for interesting reading • 1961: Kleinrock - queuing theory shows effectiveness of packet-switching • 1964: Baran - packet-switching in military applications for survivable networks • 1967: ARPAnet conceived by Advanced Research Projects Agency • 1969: First ARPAnet node operational • Prof.Kleinrock sends a message across from UCLA to Stanford • 1972: • ARPAnet demonstrated publicly • NCP (Network Control Protocol) first host-host protocol • First e-mail program • ARPAnet has 15 nodes

  5. Networking History... • 1970: ALOHAnet satellite network in Hawaii (CSMA developed), later connects to ARPANet • 1973: Bob Metcalfe’s PhD thesis proposes Ethernet (CSMA/CD developed) • 1974: Cerf and Kahn - architecture for interconnecting networks: the word “Internet” makes its appearance from Cerf’s writings

  6. Networking History... • Time sharing became difficult since different machines had different operating systems, versions and programs –however, these led to development of Internet • Vinton Cerf. Bob Kahn, Bob Braden and Jon Pestel developed TCP/IP • Cerf and Kahn’s internetworking principles: • minimalism, autonomy - no internal changes required to interconnect networks • best effort service model • stateless routers • decentralized control define today’s Internet architecture

  7. Networking History... • 1978: TCP/IP v4 was released • Aimed to interconnect different kinds of networks • 1979: ARPAnet has 200 nodes • 1983: deployment of TCP/IP in ARPAnet • 1983: SMTP e-mail protocol defined • 1983: DNS defined for name-to-IP-address translation • 1985: FTP protocol defined • 1988: TCP congestion control • 100,000 hosts connected to confederation of networks

  8. Networking History... • Early 1990’s:ARPAnet decommissioned • Early 1990s: WWW • Hypertext (1945 Bush: “As We May Think” article, Ted Nelson, Engelbert, Andries in 1968 ) • HTTP: Tim Berners-Lee develops WWW an Internet based hypermedia initiative at CERN, specifies URLs, HTTP and HTML which became basis for today’s WWW • 1994: Mosaic (Univ. of Illinois), later Netscape the major browsers until late 1990’s • late 1990’s: commercialization of the WWW, with introduction of HTTPS e-commerce is realized Late 1990’s: • est. 50 million computers on Internet • est. 100 million+ users • backbone links running at 1 Gbps

  9. The ARPANET • Growth of the ARPANET (a) December 1969. (b) July 1970. • (c) March 1971. (d) April 1972. (e) September 1972.

  10. Hosts on the Web

  11. Over the past year, the UK added a net increase of 6.1 subscribers per 100 inhabitants. The US added 4.7 subscribers, while Japan added 2.6. The UK's superior growth rate propelled it past the US and Japan to become second only to Canada among G7 countries surveyed in broadband penetration. Source: http://www.websiteoptimization.com/bw/0611/

  12. Total Broadband Subscribers • Over the past year, the US has maintained its lead with 31% of total broadband subscribers worldwide. Source: http://www.websiteoptimization.com/bw/0611/

  13. Course Overview • Aimed to impart • Fundamentals of Networking principles • Application of these principles in Internet • Understanding of Issues in Theory and Practical Design of networking hard ware and software • Understand some network programming principles • Practice of using standard networking tools

  14. Some Pre-requisites • Brush up on your probability and statistics concepts, especially, probability distributions • Revise a bit of operating systems (memory addressing in CAMs, TCAMs etc) • Bit of processor architecture • Try to learn C++ in the first two weeks before the labs/programming assignments begin

  15. Grading Overview • Homework Assignments: 20% • Programming Assignments: 20% • Mid-terms: 40% • Final Exam: 15% • Class Participation: 5% • Anyone sent out of class even once for causing disruption will receive not receive this credit • Important: Minimum pass mark for the course is 50% of overall marks achievable (in absolute sense) • Any copied * will get 0 marks for * and anyone caught more than once fails the course • One lab and/or tutorial per week, schedule will be announced soon

  16. Course Textbook and References Text Book • Jim Kurose and Ross “Internetworking: A top-down Approach” • Bertsekas and Gallagher “Data Networks” References • S.Keshav “An Engineering Approach to Computer Networking” • Radia Perlman “Interconnections: Bridges and Routers”

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