CONGESTION CONTROL IN COMPUTER NETWORKS USING A MODIFIED RED AQM ALGORITHM

Abstract

Congestion control plays an important role in netwo rk resource management in very large networks with heavy traffic. Active Queue Management (AQM) algorithms are one of the approach es to resolve the congestion problems. Majority of AQM algorithms mainly focus on single queued links. The input queued swit ches are limited in throughput and output queued sw itches require a large speedup factor so our attention is directed towards Combine d Input and Output Queued (CIOQ) switches. A simple modification to the RED AQM algorithm is proposed in this paper in order to account for the presence of both input and output queues in the switch. The weighted sum of input and output queue lengths are specifically used as the congestion measure instead of just the output queue length. The average backlog in the switch is signif icantly reduced in the low speedup region by using our modified algorithm as compared to RED without this modification. Simulati ons show that the loss rate in the modified RED sli ghtly larger than that in traditional RED but the output queue length in modi fied RED is tremendously reduced. The congestion me asure which is computed using weighting factor results in reduction of the average backlog. Using our modified algorithm simul ations indicate improvement in the queue length and switch utilization.