CONGESTION CONTROL IN COMPUTER NETWORKS USING A MODIFIED RED AQM ALGORITHM

Mohit Shrivastav, Santanu Mukherjee, Sandeep Gonnade

Abstract: Congestion control plays an important role in network resource management in very large networks with heavy traffic. Active Queue Management (AQM) algorithms are one of the approaches to resolve the congestion problems. Majority of AQM algorithms mainly focus on single queued links. The input queued switches are limited in throughput and output queued switches require a large speedup factor so our attention is directed towards Combined 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 significantly reduced in the low speedup region by using our modified algorithm as compared to RED without this modification. Simulations show that the loss rate in the modified RED slightly larger than that in traditional RED but the output queue length in modified RED is tremendously reduced. The congestion measure which is computed using weighting factor results in reduction of the average backlog. Using our modified algorithm simulations indicate improvement in the queue length and switch utilization.

Keywords: Combined Input and Output Queued (CIOQ), Active Queue Management (AQM), Random Early Detection (RED), congestion, congestion control

DOI: https://doi.org/10.15623/ijret.2013.0209084