Parc of Sophia Antipolis

Active queue management (AQM) refers to a family of packet drop-ping mechanisms for router queues that has been proposed to sup-port end-to-end congestion control mechanisms in the Internet. In this paper, we examine the performance of AQM mechanisms by varying two parameters: the queue size and the dropping function. AQM flavors considered include “RED”, the more recently pro-posed “Gentle RED ” and an additional mechanism we call “Gentle RED with instantaneous queue size”. We use experimentation to analyze the performance of the AQM mechanisms identified above on the aggregate traffic going through a congested router. The metrics used are: TCP goodput, TCP and UDP loss rate, queueing delay and consecutive loss probabil-ity. The AQM mechanisms are compared to Drop from Tail, the buffer management mechanism currently found in most operational routers. The major observation is that AQM mechanisms have a minor im-pact on the aggregate performance metrics we observe. On the other hand, we observe an important sensitivity of the AQMs con-sidered to traffic characteristics that may compromise their opera-tional deployment. 1