Research On Round-trip Delay Of VFAST TCP Protocol Under LAN

With the growing size of the Internet and network technology, networks tend to be large-scale, high-speed, high-capacity, diverse applications areas such as development, the resulting congestion is becoming increasingly serious problem. The reason of Network congestion have faced in its load over its capacity. FAST TCP is a new TCP congestion control protocol, in view of the current characteristics of high-speed network design.however there are still some outstanding issues, Because FAST TCP adjust the RTT the window size in accordance with the propagation delay, so the accuracy of measurement of propagation delay on the connection FAST TCP is very important. When the RTT is not an accurate measurement, the performance of FAST TCP will cause a great impact, so that FAST TCP connection can not get a fair bandwidth allocation.This article focuses on the VFAST TCP protocol, which is aimed at an improvement of FAST TCP version, it can more accurately estimate the RTT, the elimination of the fluctuations when the RTT throughput and queue oscillation problem. At present, the simulation of VFAST is simulated in high-speed long-delay network. However the delay does not necessarily have been caused by the distance, in the LAN environment, when there are a lot of TCP flows to compete a link will have a big delay. In this paper, the campus local area network as a model, through simulation experiments and compared with TCP Reno, analysis the round trip delay performance of VFAST TCP under the LAN environment. Simulation results show that, VFAST offer better performance than TCP Reno in terms of RTT estimation, queue length and throughput.