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Accuracy of Link Capacity Estimates using Passive and Active Approaches with CapProbe


CapProbe is an inexpensive and accurate means to estimate capacity. CapProbe combines both dispersion and end-to-end delay to estimate the capacity of the nar- rowest link on a path. We evaluate in this paper the ac- curacy of CapProbe estimation, and its dependence on end systems speed, packet sizes, narrow link speeds, and other system parameters. We test kernel and user level implementations of CapProbe and find the kernel imple- mentation to be much more accurate. We also evaluate through experiments the effect of probing packet size on the accuracy of CapProbe estimation. Finally, we ex- plore the idea of a “passive CapProbe” within the con- text of a TCP flow. Passive here means that the disper- sion and delay observed for the TCP flow data and ACK packets, without introducing any additional probing packets. We test active and passive versions of CapProbe with TCP. The active version is found to produce more accurate capacity estimates than the passive version.

Paper: PDF file of paper

Information & Date

The Ninth IEEE Symposium on Computers and Communications (ISCC 2004), Alexandria, Egypt, January. 2004


Rohit Kapoor
Ling-Jyh Chen
M. Y. Sanadidi
Mario Gerla