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Performance Evaluation of PISA and PI using NS simulations. Presented by Brad Burres Yatin Manjrekar. Agenda. Introduction Background Setup Results Conclusion. Introduction . 80% of traffic flows are short (http) and represent 20% of data
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Performance Evaluation of PISA and PI using NS simulations Presented by Brad Burres Yatin Manjrekar
Agenda • Introduction • Background • Setup • Results • Conclusion
Introduction • 80% of traffic flows are short (http) and represent 20% of data • 20% of traffic flows are long and represent 80% of data • Prioritizing short flow transmission (dropping Long flows first) will help the network congestion • Our scope is limited to TCP.
AQM congestion control • Droptail – FIFO • RED – Random Early Detection • SHRED- Short lived flow friendly RED • DCN-Differential Congestion Notification • PI – Proportional Integrator
PISA Algorithm • PISA – Proportional Integrator with Short-lived flow Adjustment • It clamps queue length to Qref • CWND hint in Type of Service field • Drop probability is increased or decreased depending on cwnd ratio
PISA Algorithm Cont Weighted Cwnd Average
Simulations and Measurements Measurements Made • Queue Length • Instantaneous • Average • Drop Rate • Web Objects • Transmission Time • Items Transmitted • Utilization (pending)
Queue Length (all graphs are the ftp 100, http 100, pareto = 1.3) PI AVG = 199.94 PISA AVG = 198.97 (both clamp to 200)
Web Object Transmission • PI • Started 28630 • Finished 28549 • PISA • Started 34358 • Finished 34273 • For both, tails go out to 500 seconds
Conclusions • PISA does a better job at giving priority to short flows • There is still room for improvement • We still need to do more analysis of the data
References • [UW] Stefan Saroiu, Krishna Gummadi, Richard Dunn, Steven Gribble, Henry Levy, “An Analysis of Internet Content Delivery Systems”. • [FJ93] S Floyd and V Jacobson, “Random Early Detection Gateways for Congestion avoidance”. IEEE/ACM Tractions on Networking • [CJO01] M Christiansen,K Jeffay, D. Ott and F.D.Smith, “Tuning RED for Web Traffic” IEEE/ACM Transactions on Networking. • [HCK02] M Hartling, M Claypool and R. Kinicki, “Active Queue Management for Web Traffic” • Technical Report WPI-CS-TR-02-20, Worcester Polytechnic Institute, May 2002 • [LAJS04] Long Le, Jay Aikat, Kevin Jeffay, F. Donelsom Smith “Differential Congestion Notification:Taming the elephant” IEEE/ICNP 04
References Cont. • [K04]Minchong Kim, “Proportional Integrator with Short-lived flow adjustment” http://www.wpi.edu/Pubs/ETD/Available/etd-0122104-154529/unrestricted/mjkim.pdf • Thesis submitted to WPI Faculty, Jan 2004 • [S04] David Sonderling. “Master Qualifying Project”. MQP submitted to WPI Faculty. 2004. • [NS201]NS-2 Network Simulator http://www.isi.edu.nsnam/ns, September 2001 • Jae Chung and Mark Claypool “NS by example” http://nile.wpi.edu/NS/ • http://www.freesoft.org/CIE/Course/Section3/7.htm
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