A method of IP traffic management using TCP flow statistics

We propose a method of IP traffic management where the quality of TCP performance at a bottleneck link is estimated from monitored data on the behavior of the number of active flows versus utilization of the link, each of which is easy to measure. Our method is based on the characteristics that (i) TCP performance remains constant until the level of link utilization exceeds some threshold value, but becomes degraded when the utilization exceeds this value and (ii) the number of active flows increases linearly with utilization of the link up to the same value, above which the increase becomes nonlinear. Though this threshold may vary from network to network, our method requires neither predetermination of a threshold, on the basis of assumed traffic conditions, nor direct measurement of TCP performance.