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A Very Brief History of Early Digital Networking

COMP 150-IDS: Internet Scale Distributed Systems (Fall 2012). A Very Brief History of Early Digital Networking. Noah Mendelsohn Tufts University Email: noah@cs.tufts.edu Web: http://www.cs.tufts.edu/~noah. Shannon & Information Theory. Claude Shannon and Information Theory.

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A Very Brief History of Early Digital Networking

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  1. COMP 150-IDS: Internet Scale Distributed Systems (Fall 2012) A Very Brief History of Early Digital Networking Noah Mendelsohn Tufts UniversityEmail: noah@cs.tufts.edu Web: http://www.cs.tufts.edu/~noah

  2. Shannon&Information Theory

  3. Claude Shannon and Information Theory 1948: Claude Shannon publishes: A mathematical theory of communication* * http://www.alcatel-lucent.com/bstj/vol27-1948/articles/bstj27-3-379.pdf Photo by Tekniska Museet

  4. Claude Shannon and Information Theory • Shannon’s work is as fundamental to digital communication as Turing’s is to digital computing • Information theory • Quantifies information: how much information does a bit represent? • Relates information transmission to bandwidth requirements • Provides quantitative analysis of rate at which information can be sent over a noisy channel • Shannon showed that information could be communicated reliably • He predicted how much information could be communicated reliably given that channel characteristics are known • BTW: Shannon and Turing knew each other and met for several months

  5. Whirlwind, SAGE&US Air Defense

  6. Early history of digital data transmission • 1948: Claude Shannon publishes: A mathematical theory of communication* • Late 1940’s: US seeks means of providing cold-war air defense • Late 1949: Digital Radar Relay – experiment sending radar dataover phone lines - first digital transmisison over the phone • 1951: MIT Whirlwind machine goes online

  7. Whirlwind computer

  8. Whirlwind computer • The first significant real time computer system • Innovation: core memory & digital networking • 5000 vacuum tubes • 16 bit parallel ALU • 20,000 instructions/second – limited by storage speed • 4000 bytes of core memory – invented for Whirlwind Pictures by Dan Smity

  9. Core Memory Aside: for 20 years before transistor memories became available,core memory made digital computing practical

  10. Early history of digital data transmission • 1948: Claude Shannon publishes: A mathematical theory of communication* • Late 1940’s: US seeks means of providing cold-war air defense • Late 1949: Digital Radar Relay – experiment sending radar dataover phone lines - first digital transmisison over the phone • 1951: MIT Whirlwind machine goes online • 1953: Cape Cod System tests sending radar data through phone lines to Whirlwind • 1957: First SAGE system, based on Whirlwind technology – SAGE runs US air defenses until 1983! (video) ** Good book on Whirlwind: Bright Boys, by Tom Green History of Whirlwind and MIT Lincoln Lab: http://www.ll.mit.edu/about/History/origins.html

  11. Paul Barran&Packet Switching

  12. Paul Baran, Donald Davies and Packet Switching • 1964: Paul Baran proposes packet switching design • Design goal: a resilient network to maintain command and control

  13. Circuit switching (the way the old phone system worked) When you make a call… …switches are set to reserve linksfor a fixed route for the life of the call

  14. Packet switching When you communicate… …packets find independent routes through the network

  15. Packet switching When you communicate… …packets find independent routes through the network

  16. Paul Baran, Donald Davies and Packet Switching • 1964: Paul Baran proposes packet switching design • Design goal: a resilient network to maintain command and control • Questions to consider: • Performance: better or worse than circuit switch? • How are routing tables maintained? • Why was it counter-intuitive • Success of early packet switching tests motivates government funding for ARPANet

  17. Packet vs. Circuit Switching • Circuit switching • Good for continuous predictable flows • Easy to put “smarts” into the middle of the network (smart switches) • The way to go when all you have is analog communication • Packet switching • Adapts well to changing loads • Relatively cheap to make lots of quick “connections” • Paul Baran’s insight: digital makes packet switching possible (packet does not “degrade” as it gets copied through intermediate nodes) • 1960’s: AT&T did not believe packet switching would work • Packet switching tends to put value outside the network

  18. A Brief History of The Internet

  19. History of the Internet DNS(Mockapetris) First Web Server 14 Arpanet Nodes + 1/month NSFNet BobMetcalfeBegins Ethernet work at Xerox PARC Baran & Davies Packet Switching WorkPrompts Gov’t Investment 1989:80,000 hosts Tim BL Proposes Web ARPANet Developed TCP/IP (Cerf & Kahn) 1960 1965 1970 1975 1980 1985 1990 Adapted from http://www.computerhistory.org/internet_history/

  20. History of the Internet DNS(Mockapetris) First Web Server 14 Arpanet Nodes + 1/month NSFNet By 1992, the Internet is doublingin size every 3 months Baran & Davies Packet Switching WorkPrompts Gov’t Investment MetcalfeBegins Ethernet work at Xerox PARC 1989:80,000 hosts Tim BL Proposes Web ARPANet Developed TCP/IP (Cerf & Kahn) 1960 1965 1970 1975 1980 1985 1990

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