Towards stochastic flow-level network modeling: Performance evaluation of short TCP flows

We present in this paper a stochastic flow-level network model for the performance evaluation of IP networks with multiple bottlenecks supporting short-lived and long-lived TCP flows. Flow-level network models are efficient at estimating the mean bandwidth of TCP flows in various topologies, but they are generally limited to the study of infinite flows. This paper extends such models in order to evaluate short-lived flows alternating between idle and active periods where data of random size is transferred. We study the interaction between multiple flows and derive mean bandwidths, durations of file transfer or average number of active flows. We first study a single bottleneck, and then extend our analysis to networks with multiple bottlenecks as well as the effect of slow-start. We apply our results to various networks and assess the accuracy of our approach by comparing our analytical results with results of the discrete event simulator ns-2.