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A Receiver-Driven Bandwidth Sharing System (BWSS) for TCP

A Receiver-Driven Bandwidth Sharing System (BWSS) for TCP. Puneet Mehra, Avideh Zakhor UC Berkeley, USA Christophe De Vleeschouwer Université Catholique de Louvain, Belgium. Talk Outline. Motivation & Goals BWSS Overview NS-2 Simulations Internet Experiments Related Work Conclusion.

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A Receiver-Driven Bandwidth Sharing System (BWSS) for TCP

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  1. INFOCOM 2003 A Receiver-Driven Bandwidth Sharing System (BWSS) for TCP Puneet Mehra, Avideh Zakhor UC Berkeley, USA Christophe De Vleeschouwer Université Catholique de Louvain, Belgium

  2. INFOCOM 2003 Talk Outline • Motivation & Goals • BWSS Overview • NS-2 Simulations • Internet Experiments • Related Work • Conclusion

  3. INFOCOM 2003 Motivation • Most traffic on Internet is TCP • HTTP, FTP, P2P,… • In many cases access links are bottleneck • Limited Bandwidth (B/W) eg: DSL/Cable < 1.5Mbps • User run many apps that compete for B/W • Problem: TCP shares bottleneck B/W according to RTT • Not fair to flows w/ large RTT • Doesn’t consider application needs or user prefs!

  4. INFOCOM 2003 Example Situation Low RTT Med. RTT High RTT Congestion

  5. INFOCOM 2003 Goal & Approach • Goal: Let user control application B/W allocations • User preferences dictate bandwidth allocation • Approach: limit throughput of low-priority flows to provide additional B/W for high-priority ones • Ensure full utilization of access link • Don’t change TCP/senders or routers  easily deployable!

  6. INFOCOM 2003 Talk Outline • Motivation & Goals • BWSS Overview • NS-2 Simulations • Internet Experiments • Related Work • Conclusion

  7. INFOCOM 2003 BWSS Overview

  8. INFOCOM 2003 σ User Prefs. Tn Target Rate Allocation Subsystem T1 • Some apps need minimum guaranteed rate(video), others don’t (ftp) • User assigns each flow: • Priority, minimum rate and weight • Bandwidth allocation algorithm: • Satisfy minimum rate in decreasing order of priority • Remaining B/W shared according to weight

  9. INFOCOM 2003 BWSS Overview

  10. INFOCOM 2003 w – TCP window d – delay in ACKs RTT – Flow RTT MSS – TCP MSS Flow Control System (FCS)

  11. INFOCOM 2003 BWSS Overview

  12. INFOCOM 2003 σ – Calculation Subsystem R1 σ RN • Goal: Choose σ to maximize link utilization. U = Σi Ri (σ) • Approach: Iteratively increase/decrease σ and measure the impact on utilization T2 != R2 T2 = R2 T1 = R1 T2 = R2 Link Capacity T1 = R1 U σ W1 W2

  13. INFOCOM 2003 BWSS Overview

  14. INFOCOM 2003 Talk Outline • Motivation & Goals • BWSS Overview • NS-2 Simulations • Internet Experiments • Related Work • Conclusion

  15. INFOCOM 2003 Example of User Preferences Time 0: Min. Rate = 0 Kb/s weights = 1,2,3 for S0-S2 Priority -> S0 (max), S2(min) Time 300: Min Rate = 600 Kb/s TCP BWSS

  16. INFOCOM 2003 Network-Congestion Example Priorities: increasing from S0-S2 Min Rate: S0,S2 – 600Kb/s S1 – 100 Kb/s Time 400s to 1200s 700Kb/s Interfering TCP traffic S2 limited to 300Kb/s

  17. INFOCOM 2003 Multimedia Streaming Example • S0 – Ftp traffic. Low Priority • Min Rate = 700Kb/s • S1 – Streaming at 450Kb/s • High Priority • 300Kb/s UDP flow (400s-1000s)

  18. INFOCOM 2003 Talk Outline • Motivation & Goals • BWSS Overview • NS-2 Simulations • Internet Experiments • Related Work • Conclusion

  19. INFOCOM 2003 APP_1 APP_n APP_2 BWSS Implementation BWSS User-space shared library setsockopt() No Kernel Mods! ETH0 Invisible to Apps

  20. INFOCOM 2003 Experimental Setup AT&T Cable modem connection Host PC running Linux 2.4.8 kernel

  21. INFOCOM 2003 Experiment 1 – User Preferences Standard TCP Minimum Rate of 100Kb/s Priorities: Blue, green, red Weighted Fair Sharing Ratios: 3,2,1 • BWSS allows flexible allocation of B/W

  22. INFOCOM 2003 Related Work • Network-Modifying Solutions • Router Scheduling Policies • WFQ, W2FQ: allow B/W allocation • Require infrastructure changes  little deployment • Network Appliances – PacketShaper • Placed at network ingress  does traffic management • Not easy to manage individual preferences • End-Host solution • Modify receiver’s window [Spring et al, 2000] • Prioritize short-lived flows over longer ones • Focus: reduce queuing delay for interactive apps (telnet)

  23. INFOCOM 2003 Conclusions • BWSS allows user to allocate link B/W • Flexible B/W allocation model • Adapts to changing network conditions • No changes to TCP/senders/routers • Implemented as shared library  easily deployable • Enables efficient video streaming over TCP • Simulations show better performance than standard TCP • Additional Internet experiments validate [TCP Based Video Streaming using Receiver-Driven Bandwidth Sharing, Packet Video 2003, To appear]

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