Dynamic-CBT – Router Queue Management for Improved Multimedia Performance on the Internet

The explosive increase in Internet traffic has placed a growing emphasis on congestion control and fairness in Internet routers. Approaches to the problem of congestion, such as active queue management schemes like Random Early Detection (RED) that are successful with TCP flows, use congestion avoidance techniques. Approaches to the problem of fairness, such as Fair Random Early Drop (FRED), punish misbehaved, non-TCP flows. Unfortunately, these punishment mechanisms result in a significant performance drop for multimedia flows that are well behaved. We propose a new active queue management mechanism as an extension to RED called Dynamic Class-Based Threshold (D-CBT) to improve multimedia performance on the Internet. Also, as an effort to further improve multimedia performance especially on jitter, we propose a lightweight packet scheduling called Cut-In Packet Scheduling (ChIPS) as an alternative to FIFO packet scheduling. The performance of our proposed mechanisms is measured, analyzed and compared with other mechanisms (RED and CBT) in terms of throughput, fairness and multimedia jitter through simulation using NS. The study concludes that D-CBT improves fairness among different classes of flows and ChIPS improves multimedia jitter without degrading fairness. The contributions we make are the design, implementation and evaluation of D-CBT and ChIPS, the first study of multimedia jitter due to network queue management policy, and a simulator implementation of CBT, D-CBT and ChIPS.