MAGISTARSKA TEZA - Simon Fraser ljilja/cnl/pdf/ ¢  MAGISTARSKA TEZA FLEKSIBILNI INTERNET

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  • UNIVERZITET U BEOGRADU

    ELEKTROTEHNIČKI FAKULTET

    VLADIMIR V. VUKADINOVIĆ

    MAGISTARSKA TEZA

    FLEKSIBILNI INTERNET SERVISI NA BAZI KONTROLE KAŠNJENJA I PROPUSNOSTI

    Teza je odbranjena 15. oktobra 2004. godine pred komisijom u sastavu:

    Prof. Grozdan Petrović, mentor Elektrotehnički fakultet, Univerzitet u Beogradu

    Srbija i Crna Gora

    Prof. Ljiljana Trajković, mentor School of Engineering Science, Simon Fraser University

    Canada

    Prof. Zoran Petrović Elektrotehnički fakultet, Univerzitet u Beogradu

    Srbija i Crna Gora

    Prof. Zoran Bojković Saobraćajni fakultet, Univerzitet u Beogradu

    Srbija i Crna Gora

    Beograd, oktobar 2004. godine

  • ii

    Abstrakt

    Vladimir V. Vukadinović

    Fleksibilni Internet servisi na bazi kontrole kašnjenja i propusnosti

    Internet je transportna infrastruktura za aplikacije sa različitim zahtevima u

    pogledu kvaliteta servisa. Današnji Internet je međutim samo “best-effort” mreža bez

    implementiranih mehanizama za diferencijaciju servisa. Skorašnji napori da se obezbede

    takvi mehanizmi usmereni su ka takozvanim fleksibilnim servisima. Većina predloženih

    arhitektura za pružanje fleksibilnih servisa se bazira na principu pružanju servisa malog

    kašnjenja po cenu povećanja verovatnoće gubitka paketa. Ove arhitekture međutim ne

    uzimaju u obzir uticaj diferencijacije kašnjenja na performanse TCP-a, najčešće

    korišćenog transportnog protokola na Internetu. Prilikom projektovanja mehanizama za

    diferencijaciju servisa, neophodno je uzeti u obzir kompleksnost TCP algoritma za

    kontrolu zagušenja. U ovoj tezi pretstavljen je nova arhitektura za diferencijaciju

    kašnjenja i propusnosti zasnovana na konceptu fleksibilnih servisa. Neophodni uslovi za

    ostvarivanje željene diferencijacije servisa između razlicitih klasa mrežnog saobraćaja

    izvedeni su na osnovu analize kontrolnog sistema sa povratnom spregom koga čine TCP

    algoritam za kontrolu zagušenja i mehanizmi za diferencijaciju kašnjenja i kontrolu

    verovatnoće gubitaka.

    Ključne reči—diferencijacija servisa, fleksibilni servisi, QoS, aktivna kontrola bafera,

    TCP, mrežni saobraćaj.

  • iii

    Abstract

    Vladimir V. Vukadinović

    Delay and throughput differentiation mechanisms for non-elevated services

    Internet is a transport infrastructure intended for applications with various service

    requirements. However, Internet remains to be a best-effort network without widely

    deployed mechanisms for service differentiation and quality of service (QoS)

    provisioning. Research efforts to provide service differentiation in the Internet have been

    recently directed toward non-elevated services. Majority of proposed non-elevated

    mechanisms aim to provide low delay service at the expense of increased packet loss

    probability. However, these proposals do not consider the influence of delay and loss

    differentiation on the behaviour of TCP, the most widely used transport protocol in

    today’s Internet. Service differentiation mechanisms cannot be properly designed without

    taking into account the complexity of TCP’s congestion control algorithm. In this thesis,

    we propose a new non-elevated service differentiation architecture and derive necessary

    conditions to provide desired service differentiation among traffic classes by considering

    TCP’s congestion control algorithm, delay differentiation mechanisms, and proposed

    packet loss controller as a feedback control system.

    Keywords—non-elevated services, service differentiation, TCP, QoS, queue

    management.

  • iv

    Acknowledgements

    First and foremost I would like to thank my academic advisors, Dr. Ljiljana

    Trajkovic and Dr. Grozdan Petrovic.

    Dr. Ljiljana Trajkovic deserves my deepest gratitude and respect for her continued

    support during the writing of this thesis. She gave me a wonderful opportunity to spend a

    memorable time at Simon Fraser University, Vancouver, Canada. Special thanks for

    teaching me how to write academic papers and encouraging me to continue my studies.

    Dr. Grozdan Petrovic has been providing me continuous support for many years,

    both during my undergraduate and graduate studies. He showed me different ways to

    approach a research problem and the need to be persistent to accomplish any goal.

    I would also like to thank all the members of Communication Networks

    Laboratory, especially my dear friends Svetlana and Bozidar Vujicic, Nikola Cackov,

    Nenad Laskovic, Hui (Grace) Zhang, and Hao (Johnson) Chen for their help and

    companionship.

  • v

    Table of Contents

    Abstrakt.............................................................................................................................. ii Abstract ............................................................................................................................. iii Acknowledgements........................................................................................................... iv Table of Contents .............................................................................................................. v List of Figures ..................................................................................................................vii List of Tables..................................................................................................................... ix List of Abbreviations and Acronyms............................................................................... x 1. Introduction ................................................................................................................... 1 2. Quality of Service in Internet: an overview................................................................ 6

    2.1. QoS control mechanisms .......................................................................................... 6 2.2. Proposed QoS architectures...................................................................................... 9

    2.2.1. Integrated Services (IntServ) ........................................................................... 10 2.2.2. Differentiated Services (DiffServ)................................................................... 12 2.2.3. Non-Elevated Services..................................................................................... 14

    3. Survey of existing proposals for non-elevated services............................................ 16 3.1. Alternative Best-Effort (ABE)................................................................................ 16 3.2. Best-Effort Differentiated Services (BEDS) .......................................................... 17 3.3. Equivalent Differentiated Services (EDS).............................................................. 22

    4. Proposed service differentiation architecture for non-elevated services ............... 26 5. Scheduling for proportional delay differentiation ................................................... 29

    5.1. Backlog-Proportional Rate scheduler (BPR).......................................................... 30 5.2. BPR+: an optimized BPR scheduler ....................................................................... 31

    5.2.1. A heuristic approximation of BPR+ ................................................................. 34 5.3. Performances of BPR and BPR+............................................................................. 37

    5.3.1. Influence of traffic load ................................................................................... 38 5.3.2. Influence of load distribution........................................................................... 39 5.3.3. Influence of buffer size .................................................................................... 40 5.3.4. Influence of timescale...................................................................................... 41

    5.4. Influence of proportional delay differentiation on TCP throughput....................... 43

    6. Packet Loss Controller................................................................................................ 46 6.1. No-loss region: minqq ≤ ........................................................................................ 52 6.2. Early-drop region: maxmin qqq

  • vi

    6.3. Forced-drop region: maxqq ≥ ................................................................................. 54

    7. Simulation results........................................................................................................ 56 7.1. Influence of delay differentiation parameter δ ....................................................... 58 7.2. Influence of UDP load............................................................................................ 60 7.3. Multi-hop topology scenario .................................................................................. 62

    8. Conclusions and open issues....................................................................................... 65 Appendix A ...................................................................................................................... 68 Appendix B ...............................................................