Bursty fluid approximation of TCP for modeling internet congestion at the flow level

We propose an improved model for TCP flow level congestion performance. Conventional fluid approximation models yield incorrect results for TCP congestion at the flow level due to throughput overestimation. We introduce a more accurate model incorporating some of the packet level burstiness, by approximating TCP sources as on-off fluid sources. Our model is largely based on the work of D. Anick, D. Mitra and M. M. Sondhi exploring buffer statistics of the superposition of on-off sources. Incorporating some of the TCP burstiness at the packet level while retaining the over all fluid approximation framework allows us to substantially improve the accuracy of the flow level congestion model at the price of a relatively small increase in mathematical complexity. The model is extensively validated against ns2 simulations and shown to perform better than the M/M/1/B based model typically used in this context.