On the Evaluation of the Active Queue Management Mechanisms

The active queue management in Internet routers exploits the idea that an incoming packet can be dropped by the router even if there is some available buffering space in the router. Therefore, the router can send congestion signals to TCP before the actual congestion occurs, preventing queues and delays from growing too high. Many active queue management algorithms has been proposed till now. Unfortunately, it is difficult to compare their performance because the authors often describe new features of a proposed algorithm using some specific network scenarios. In fact, among hundreds of papers it is hard to find a few that use exactly the same network scenario for evaluation of the proposed algorithm. In this paper, we propose a common testbed for the evaluation of active queue management mechanisms. It includes a specification of the network topology, link bandwidths and delays, traffic patterns on the application level, transport protocols, congestion level, bidirectional traffic characterization, metrics for the performance evaluation etc. As all active queue management algorithms cooperate closely with TCP, their evaluation methodology has to be closely connected with the TCP evaluation methodology. Therefore the testbed presented herein is based on the newest TCP evaluation suite (by Lachlan Andrew et al.), properly tailored for the active queue management evaluation purposes.