Analysis of RED-Family Active Queue Management Over a Wide-Range of TCP Loads

RED is an Active Queue Management (AQM) technique that is intended to achieve high link utilization with a low queuing delay. Recent studies show that RED is difficult to configure for some rapidly changing traffic mixes and loads [2]. Other studies show that under some conditions, the performance gains of RED and its variants over traditional drop-tail queue management is not significant given the additional complexity required for proper configuration [9, 3]. Recent variants of RED, such as Adaptive-RED [8], are designed to provide more robust RED performance under a wider-range of traffic conditions. This paper provides additional analysis of RED and newer variants of RED over a wider range of traffic mixes and loads than has previously been studied. Through extensive simulation results and analysis, this paper confirms that RED-like AQM techniques that employ packet dropping do not significantly improve performance over that of drop-tail queue management. However, when AQM techniques use Explicit Congestion Notification (ECN) as a method to notify TCP sources of congestion rather than packet drops, the performance gains of AQM in terms of goodput and delay can be significant over that of drop-tail queue management.