1 CapProbe: A Simple and Accurate Technique to Measure Path Capacity

Abstract: Measuring the capacity of the narrow link in an Internet path in an unobtrusive and end-to-end manner is a fundamental issue and has received a lot of attention in previous literature. Most attempts have been based on packet dispersion measurements, but they have been so far not very accurate. Both ‘Packet Pairs ’ and ‘Packet Trains ’ have been shown to be inadequate. In this work, we extend the packet dispersion paradigm as a result of a fundamental queuing delay observation. Our technique, called CapProbe, makes use of not only the dispersion between packets of the Packet Pair, but also the actual delays of the packets. Using various simulation experiments, we show that our technique works across a very broad range of cross-traffic scenarios. In fact, the only case where our technique does not work is when the cross-traffic is predominantly non-reactive (like UDP). Even in this case, the scheme fails only when the UDP traffic saturates the bottleneck link, a very unlikely event in the current Internet dominated by TCP applications