Passive capacity estimation: Comparison of existing tools

In this paper, we focus on the issue of passive capacity estimation. We consider all the existing passive tools devised so far, namely PPrate, Nettimer and MultiQ. We first compare those passive tools to one state-of-the-art active tool, Pathrate, using Planetlab. We next investigate the performance of the passive tools in a more realistic and challenging environment, namely an ADSL platform. Our study reveals that Nettimer is unable to work properly on TCP ack streams and tends to underestimate path capacities when working on TCP data streams. In contrast, MultiQ works on both TCP ack and TCP data streams but tends to overestimate path capacities. Overall, PPrate offers a good compromise in most situations.