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Network Management

Explore the evolution of network management, from the 1980s to present challenges like video-induced congestion collapse. Understand the significance of fair bandwidth sharing models and the future of intelligent network management solutions.

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Network Management

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  1. Network Management has always been and always will be essential to the Internet FCC Broadband Industry Practices Hearing WC Docket No. 07-52 Stanford University April 17, 2008 Testimony of George Ou Former Network Engineer www.LANArchitect.net

  2. Internet meltdown in 1980s • Lack of adequate congestion control in TCP allowed too many FTP users to overload Internet around 1986 • Van Jacobson created congestion control algorithm for TCP in 1987 • Congested routers randomly dropped packets to force every TCP end-point (client) to cut flow rate in half • TCP clients then slowly increased flow rate with every successful transmission until next packet drop • Caused all TCP streams to home in towards equal flow rate • Fair bandwidth sharing, but only for applications of its time • Jacobson’s algorithm saved the Internet in 1987 and remains dominant standard after 20 years • Early example of managing network congestion

  3. World Wide Wait in 1990s • First generation of web browsers were not optimized for Internet • World Wide Web turned in to theWorld Wide Wait • Version 1.1 of HTTP revamped to efficiently use resources over 1.0

  4. Today’s crisis on the Internet • Video-induced congestion collapse • Efficient existing broadcast model migrating to bandwidth-intensive Video on Demand model over IP • Full migration of video could require 100- to 1000-fold increase in Internet capacity • Exponentially more bandwidth required as video bit-rate and resolution increase to improve quality • P2P is the dominant distribution model because most of its content is“free” (read pirated) • Video can fill any amount of bandwidth

  5. More bandwidth doesn’t help The few throttling the many According to the Japanese Government 1% of users account for ~47% of traffic 10% of users account for ~75% of traffic 90% of users get leftover 25% Bandwidth hogs

  6. Exploiting Jacobson’s algorithm 50/50 Fair 80/20 Unfair 92/8 Unfair

  7. Persistence advantage in P2P apps * Corporate VPN telecommuter worker using G.722 codec @ 64 kbps payload and 33.8 kbps packetization overhead ** Vonage or Lingo SIP-based VoIP service with G.726 codec @ 32 kbps payload and 18.8 kbps packetization overhead *** I calculated that I sent 29976 kilobytes of mail over the last 56 days averaging 0.04956 kbps

  8. Weighted TCP: Per-user fairness 92/8 Unfair 50/50 Fair • BT chief researcher Bob Briscoe proposes TCP fix before the IETF to neutralize multi-stream loophole • Changing TCP takes many years, but it’s even harder to get over a billion devices to switch to new TCP client • Newer network-based solutions being implemented

  9. Present and future solutions • Present solutions use protocol throttling • P2P applications use disproportionately large amounts of bandwidth so they’re throttled to balance them out • Use conventional router de-prioritization techniques on P2P • Use TCP resets to occasionally stop P2P seeders • Potentially affect an extremely rare low-bandwidth P2P user • Can be fooled by protocol obfuscation techniques • Future solutions are protocol-agnostic • Weighted packet dropping at router and/or fair upstream scheduling on CMTS accomplishes per-user fairness • Only targets bandwidth hogs and forces them to back off • Cannot be fooled by protocol obfuscation

  10. What is reasonable network management? Protocol-agnostic per-user fairness Fair Future Intelligent Reasonable ISP throttles BW hogging protocols Metered Internet Unreasonable No network management Unfair Dumb Past

  11. Network management ensures harmonious coexistence • P2P applications need volume, not priority • Interactive applications (Web) and real-time applications (VoIP) want priority and not volume • P2P, Interactive, and real-time applications each get what they want under a managed network • Interactive and real-time apps have small/fixed volume so no matter how much they’re prioritized, they cannot slow down a P2P download. • Unmanaged networks regardless of capacity will always be unfair and hostile to interactive and real-time applications

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