Performance analysis of fast-TCP mechanism for networks with high bandwidth-delay products

A number of revised algorithms have been proposed to improve TCP performance. Among them F-TCP is a distinguished one which arises from the fact that controlled ACK flow can indirectly affect the dynamics of TCP´s behavior. We study TCP and F-TCP presented in [1-3] and attempt to develop a basic understanding of them through mathematics modeling and simulation. We obtain that buffer size is approximately half the window size in networks with high bandwidth-delay product. Though these bounds are not new, the proofs are elegant in using simple differential equations. It is worthwhile to clarify that when maximum window size is comparatively smaller than bandwidth-delay product, F-TCP gains on average the same throughput as TCP with no loss when the round-trip time of each cycle is the same. Furthermore, analysis and simulation results show that F-TCP obtains higher throughput than TCP through reducing the buffer requirement and preventing congestion