Dynamic-CBT and ChIPS - Router Support for Improved Multimedia Performance on the Internet

1. Dynamic-CBT and ChIPS - Router Support for Improved Multimedia Performance on the Internet • Jae Chung and Mark Claypool • Department of Computer Science • WPI • In Proceedings of ACM Multimedia • November 2000

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. Bursty loss Unfairness (tcp, other) No QoS support Current Router Queue Management Drop Tail (FIFO) Resource Reservation Active Queue Mgmt ... CBQ RED FRED ... Floyd, Jacobson 95 Floyd, Jacobson 93 Lin, Morris 97

7. Class-Based Threshold (CBT) AQM Support for Multimedia -Jeffay, 99 Drop Tail (FIFO) Resource Reservation Active Queue Mgmt ... CBQ RED FRED ... Class-Based Threshold (CBT)

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

9. TCP R E D MM UDP UDP CBT Concepts • CBQ + RED: Class-based isolation on RED • Use Class Thresholds and Avg. # of enqueued packets on a single FIFO Queue • Three classes: TCP, MM UDP (flow controlled) and Unresponsive UDP

10. CBT Design

11. CBT - Pros and Cons • Pros:RED + Class-Based Isolation • Early Congestion Notification • Protect TCP, and protect (distinguish) MM UDP • Different flows coexist with predefined fairness. • Dividing bandwidth assigned is up to the class. • Cons:CBQ function w/o admission control • Might not work well for certain traffic mixes • Arguable that it’s not fair (as in the case of CBQ)

12. Dynamic-CBT Drop Tail (FIFO) Resource Reservation Active Queue Mgmt ... CBQ RED FRED ... Class-Based Threshold (CBT) Dynamic-CBT

13. Dynamic-CBT and ChIPS Drop Tail (FIFO) ChIPS Resource Reservation Active Queue Mgmt ... CBQ RED FRED ... Class-Based Threshold (CBT) Dynamic-CBT

14. D-CBT Design Responsive MM Enable Thrsh

15. Flow Counting in D-CBT • For every incoming packet, insert or update<dest-addr, flow-id, local-time> info and update count • Sorted Linked List - O(n) • Hash Table - O(1) • Every ms, delete old info and update count • Sorted Linked List - O(n) • Hash Table - O(n) • (How are flows counted in FRED?)

16. Evaluation in NS • Developed responsive multimedia application (for tagged UDP class) • AIMD Media Scaling (5 discrete rates) • “MPEG-1 like” transmission rates • [CC00a], MM-Flow • Implemented and validated CBT • Implemented D-CBT and measured congestion time fairness • RED vs. CBT vs. D-CBT

17. 6 ProShare - Unresponsive MM (210Kbps each) 240 FTP-TCP 1 UDP blast (10Mbps, 1KB) 0 20 60 110 160 180 Validation of CBT on NS • RED Settings: qsize = 60 pkts max-th = 30 pkts min-th = 15 pkts qweight = 0.002 max-pro = 0.1 • CBT Settings: mm-th = 10 pkts udp-th = 2 pkts (Second)

18. Aggregate TCP Throughput under RED X axis: Seconds, Y axis: Kbyte/Sec PJS99 Experimental Results NS Simulated Results (Our setup is ok, so now can check our CBT test)

19. Aggregate TCP Throughput under CBT X axis: Seconds, Y axis: Kbyte/Sec PJS99 Experimental Results NS Simulated Results

20. 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)

21. ( xi)2 n n   i=0 i=0 f (x0, x1, x2,…, xn) = n xi 2 Jain’s Fairness Index ( f ) - Jain, 91 • Examples: • 1 flow • 2 flows, 5 Kbps each • 2 flows, 9 Kbps and 1Kbps 0  f  1 (Greatest Fairness)

22. Fairness: RED

23. Fairness: CBT

24. Fairness: D-CBT

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

26. Cut-In Packet Scheduling (ChIPS) Design

27. MM Frame Delay D-CBT-FIFO MM1 Delay D-CBT-ChIPS MM1 Delay Second Frame Sequence Number ChIPS Evaluation - Jitter

28. 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

29. Fair to TCP Fair to Mixed (Fixed) Fair to Mixed (Variable) Improve MM Jitter D-CBT ChIPS D-CBT FIFO RED CBT X X X X X X X X X X Conclusion

30. 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

31. 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

32. Evaluation of Science? • Category of Paper • Science Evaluation (1-10)? • Space devoted to Experiments?