PBProbe: A CapProbe based Scalable Capacity Estimation Tool∗

We present a scalable capacity estimation technique, called PBProbe. PBProbe is based on CapProbe. Instead of solely relying on packet pairs, PBProbe employs a “packet bulk” technique and adapts the bulk length in order to overcome a well known problem with packet pair based approaches, namely the lack of accurate timer resolution. As a result, PBProbe not only preserves the simplicity and speed of CapProbe, but it also correctly estimates link capacities within a much larger range. Using analysis, we evaluate the accuracy and speed of PBProbe with various bulk lengths. We then perform a set of experiments to evaluate the accuracy of PBProbe in the Internet over wired and wireless links. Finally, we perform emulation and Internet experiments to verify the accuracy and speed of PBProbe on extremely high-speed links. The results show that PBProbe is consistently fast and accurate in the great majority of test cases.