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Dynamic-CBT and ChIPS –

Dynamic-CBT and ChIPS –. Jae Chung and Mark Claypool. Router Support for Improved Multimedia Performance on the Internet. Computer Science Department Worcester Polytechnic Institute Worcester, Massachusetts, USA. http://perform.wpi.edu/. The Internet and Multimedia.

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Dynamic-CBT and ChIPS –

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  1. Dynamic-CBT and ChIPS – Jae Chung and Mark Claypool Router Support for Improved Multimedia Performance on the Internet Computer Science Department Worcester Polytechnic Institute Worcester, Massachusetts, USA http://perform.wpi.edu/

  2. The Internet and Multimedia • Internet routers are best effort • No timing constraints • Packet loss, which indicates congestion • TCP • Completely reliable delivery through retransmission • Respond to loss as congestion • But … TCP often unsuitable for interactive multimedia • Full reliability not needed • Window-based rate fluctuations

  3. Multimedia Using TCP

  4. Multimedia Using UDP

  5. Multimedia on the Internet • Multimedia often uses UDP • Avoid delay and jitter from retransmission • Rate-based • Unresponsive! • Router queue management goals • Congestion Control • Fairness • Reduce Jitter

  6. Resource Reservation Active Queue Mgmt ... CBQ RED ... (Floyd, Jacobson ‘95) (Floyd, Jacobson ‘93) Class-Based Threshold (CBT) (Parris, Jeffay, Smith ‘99) Router Queue Management Bursty Loss Unfairness Drop Tail (FIFO)

  7. Outline • Introduction  • CBT  • D-CBT • ChIPS • Conclusion

  8. CBT Design

  9. FRED (Lin, Morris ‘97) Dynamic-CBT Router Queue Management ChIPS Drop Tail (FIFO) Resource Reservation Active Queue Mgmt ... CBQ RED ... (Floyd, Jacobson ‘95) (Floyd, Jacobson ‘93) Class-Based Threshold (CBT) (Parris, Jeffay, Smith ‘99)

  10. D-CBT Design Responsive MM Enable Thrsh

  11. Evaluation in NS • Developed responsive multimedia application (for tagged UDP class) • AIMD Media Scaling (5 discrete rates) • “MPEG-1 like” transmission rates • Implemented and validated CBT • Implemented D-CBT and measured congestion time fairness • RED vs. CBT vs. D-CBT

  12. 25Mbps, 5ms 25Mbps, 5ms 25 FTP-TCP s1 r2 25Mbps, 20ms 10 MM-UDP s2 r2 n1 n2 s66 r66 n1-n2: q_size = 60 RED: max_th = 15 min_th = 5 qweight = 0.002 max_prb = 0.1 CBT: mmu_th = 2.9 udp_th = 0.6 2 CBR-UDP (5Mbps each) s67 r67 30 FTP-TCP 0 10 20 30 Second Simulation (RED, CBT, D-CBT)

  13. Fairness: RED

  14. Fairness: CBT

  15. Fairness: D-CBT

  16. Outline • Introduction  • CBT and D-CBT  • Design  • Evaluation  • ChIPS  • Design • Evaluation • Conclusion

  17. Cut-In Packet Scheduling (ChIPS) Design

  18. ChIPS Evaluation - Jitter

  19. TCP Packets Delivered TCP Packet Drop Rate TCP Throughput D-CBT 66,648 pkts 4.46 % 17,773 Kbps D-CBT w/ ChIPS 66,386 pkts 4.44 % 17,703 Kbps ChIPS Evaluation - Fairness

  20. Conclusion • D-CBT • Protect responsive flows from unresponsive • Class-based consideration • Adaptive to mix of flows • ChIPS • Reduce multimedia jitter during congestion

  21. Future Work • Active Flow Counting (Overhead) • For every incoming packet, update flow info • Hash Table - O(1) • Every ms, delete old flows • Hash Table - O(n) • Measure Overhead • Processing Time and Memory Usage

  22. Future Work • How many different classes are needed? • Example • 1 class is RED • 1 class per flow is FRED • Overhead per class • Effects of D-CBT and ChIPS on Perceptual Quality

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