A Very Brief History of Early Digital Networking

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1 COMP 117: Internet Scale Distributed Systems (Spring 2017) A Very Brief History of Early Digital Networking Noah Mendelsohn Tufts University noah@cs.tufts.edu Web: Copyright 2012, 2015,2016 & 2017 Noah Mendelsohn

2 Shannon & Information Theory 2

3 Claude Shannon and Information Theory 1948: Claude Shannon publishes: A mathematical theory of communication* * Photo by Tekniska Museet 3

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 4

5 Whirlwind, SAGE & US Air Defense 5

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 6

7 Whirlwind computer 7

bit parallel ALU 20,000 instructions/second limited by storage speed

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 8

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

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 (approximate) 1953: Cape Cod System tests sending radar data through phone lines to Whirlwind 10

11 Forrester promptly began preparing to receive and process digitized radar signals. The feasibility demonstration of the radar/digital-data concept took place at Hanscom Field in September The radar, which was an original experimental model of a microwave earlywarning unit built by the wartime MIT Radiation Laboratory, closely resembled the radars used in the D-Day invasion of Normandy. History of Whirlwind and MIT Lincoln Lab: 11

12 Forrester promptly began preparing to receive and process digitized radar signals. The feasibility demonstration of the radar/digital-data concept took place at Hanscom Field in September The radar, which was an original experimental model of a microwave earlywarning unit built by the wartime MIT Radiation Laboratory, closely resembled the radars used in the D-Day invasion of Normandy. While military observers watched closely, an aircraft flew past the radar, the digital radar relay transmitted the signal from the radar to Whirlwind via a telephone line, and the result appeared on the computer's monitor. The demonstration was a complete success and proved the feasibility of ADSEC's air defense concept. History of Whirlwind and MIT Lincoln Lab: 12

13 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 (approximate) 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: 13

14 The SAGE Computer System (AN/FSQ-7) 60,000 vacuum tubes[8] (49,000 in the computers) Consumed up to 3 megawatts of electricity Performed about 75,000 instructions per second Memory: ~65, bit words Source: 14

15 Paul Barran & Packet Switching 15

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 16

17 Circuit switching (the way the old phone system worked) When you make a call switches are set to reserve links for a fixed route for the life of the call 17

18 Packet switching When you communicate packets find independent routes through the network 18

19 Packet switching When you communicate packets find independent routes through the network 19

20 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 20

21 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 When systems are fault-tolerant, you can often build them from cheaper components 21

22 A Brief History of The Internet 22

23 History of the Internet DNS (Mockapetris) First Web Server Baran & Davies Packet Switching Work Prompts Gov t Investment ARPANet Developed 14 Arpanet Nodes + 1/month Bob Metcalfe Begins Ethernet work at Xerox PARC TCP/IP (Cerf & Kahn) NSFNet 1989: 80,000 hosts Tim BL Proposes Web Adapted from 23

24 History of the Internet DNS (Mockapetris) First Web Server Baran & Davies Packet Switching Work Prompts Gov t Investment ARPANet Developed 14 Arpanet Nodes + 1/month Metcalfe Begins Ethernet work at Xerox PARC By 1992, the Internet is doubling in size every 3 months TCP/IP (Cerf & Kahn) NSFNet 1989: 80,000 hosts Tim BL Proposes Web

Ali Kamandi Spring 2007 Sharif University of Technology

Ali Kamandi Spring 2007 Sharif University of Technology Ali Kamandi Spring 2007 kamandi@sharif.edu Sharif University of Technology Internet History Internet Evolution Internet Pioneers Internet Growth Conclusion 1836 Telegraph invented by Cooke and Wheatstone