Packet Dispersion Techniques and Capacity Estimation
Constantinos Dovrolis, Parameswaran Ramanathan, David L. Moore · 2001
The packet pair technique estimates the capacity of a path (bottleneck bandwidth) from the dispersion (spacing) experienced by two back-to-back packets [5][19][13]. It has also been claimed that the dispersion of longer packet bursts (`packet trains') can measure the available bandwidth of a path [5][9][3]. This paper examines such packet pair and packet train dispersion techniques. We first demonstrate that the dispersion of packet pairs in loaded paths follows a multimodal distribution, and discuss the queueing effects that cause multiple local modes. The path capacity is not necessarily the global mode, and so it cannot be estimated using statistical procedures for the most common bandwidth range. The effect of the probing packet size is also investigated, showing that the conventional wisdom of using maximum sized packet pairs is not optimal. On the contrary, if the probing packets of different packet pairs are of variable size, the sub-capacity local modes become wider and weaker.