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互联网技术的机遇和挑战

This article explores the evolution of communication from smoke signals to the Internet, highlighting the opportunities and challenges faced. It discusses the contributions of Nyquist and Shannon, the birth of the Internet, and the current trends and challenges in communication technology.

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互联网技术的机遇和挑战

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  1. 互联网技术的机遇和挑战 清华大学 李星 二〇〇七年六月十六日

  2. 大纲 • 回顾 • 挑战和动向 • 大师论网络 • 案例分析和体会 • 总结

  3. Communication has a long history • Communication has a long history • Smoke signals, telegraph, telephone… • 1895: invention of the radio by Marconi • 1901: Trans-Atlantic communication • State of affairs: Early 20th century • Most communication systems are analog. • Engineering designs are ad-hoc, tailored for each specific application.

  4. Big Questions • Is there a general methodology for designing communication systems? • Is there a limit to how fast one can communicate?

  5. Harry Nyquist (1928) • Nyquist converted the continuous-time problem to a discrete-time problem. • Analog signals of bandwidth W can be represented by 2W samples/s • Channels of bandwidth W support transmission of 2W symbols/s • But has he really solved the communication problem? • No. You can communicate infinite number of bits in one continuous-valued symbol!

  6. source Bit stream Source Encoder Channel encoder channel Claude Shannon (1948) • His information theory addressed all the big questions in a single stroke. • Shannon showed the universality of a digital interface between the source and the channel.

  7. Initial Reactions Engineers didn’t understand what he was talking about. • People were still stuck in the analog world. • Complexity way too high for implementation technology of the day. • He didn’t really tell people exactly how to design optimal communication systems.

  8. D Internet S 50 years later…. • Our communication infrastructure is going fully digital. • Most modern communication systems are designed according to the principles laid down by Shannon.

  9. Lessons for Us • Think different • Think big • Think simple

  10. Internet - The Beginning • Fall, 1968 • US Department of Defense Advanced Research Projects Administration envisions what would become the ARPANET Project. • Official justification: create a communications network capable of surviving nuclear war • Real reason: An ARPA administrator had 3 terminals on his desk connecting to 3 different timesharing systems and he thought this was stupid.

  11. Big Questions • How to build a reliable networking using unreliable components?

  12. Larry Robert ARPANET

  13. TCP/IP • Vinton G. CerfandRobert Kahn • Concept in 1972 (ICCC) • Paper in 1974 • Implementation in 1978 • Industry standard in 1983

  14. J. C. R. Licklider Ted Nelson Claude Shannon Vannevar Bush Paul Baran Steve Crocker Leonard Kleinrock Jon Postel Vinton Cerf Lawrence Roberts Mark Andreesen Christian Huitema Brian Carpenter Tim Berners-Lee Robert Kahn Internet Pioneers

  15. Architecture

  16. Comparison

  17. Decision that made a difference

  18. Do you remember?

  19. Internet Milestones

  20. 发展趋势 • 通信 • 模拟通信 • 数字通信 • ？ • 网络 • 电路交换 • 分组交换 • ？

  21. 挑战 • 可扩展性 • 安全性 • 服务质量 • 组播 • 移动 • 过渡

  22. 战略 • US prospective • Internet • Next Generation Network

  23. Putting on weight… An accident(NAT&ALG)…. IP over IP Tunnel… Mid Life crisis… The Hourglass mode of Internet Architecture

  24. IPv6 IPv4 IPv6

  25. IPv4 Pool

  26. IPv6 Road Map

  27. IPv4 IPv6 Routing Table

  28. Routing and Addressing

  29. Optical Networking • GLIF • HOPI • UCLP

  30. GENI

  31. Defense

  32. A Cloudy Crystal Ball

  33. Lessons Learned

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