Document Type

Other

Publication Date

2-2002

Abstract

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 [1]. 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 [2], [3]. Recent variants of RED, such as Adaptive- RED [4], are designed to provide more robust RED performance under a wider-range of traffic conditions. This paper develops a general queue law for TCP-RED control systems that use packet dropping and/or Explicit Congestion Notification (ECN) marking as congestion signaling methods, and illustrates the impact of TCP traffic on the behavior of congested router queue. Furthermore, this paper provides additional analysis of RED and newer variants of RED including Adaptive-RED [4] that is designed to provide more robust RED performance under a wider-range of traffic conditions. Through careful simulation designs using the queue law 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 ECN marking, the performance gains of AQM in terms of goodput and delay can be significant over that of drop-tail queue management.

DOI

WPI-CS-TR-02-05

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