Active queue management (AQM) refers to a family of packet dropping mechanisms for router queues that has been proposed to support 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 proposed "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 probability. 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 impact on the aggregate performance metrics we observe. On the other hand, we observe an important sensitivity of the AQMs considered to traffic characteristics that may compromise their operational deployment.