FAST TCP Congestion Control Algorithm Research And Improvement

With the rapid development of computer network technology, the network of high-bandwidth long delay began to emerge. Efficient and universal access of information technology increased use of high-speed networks in the broader areas of research. Now, some applications such as scientific collaboration, remote medical diagnosis, through the dissemination of high-speed network real-time data from remote probes, other new services such as high-definition signals, cloud computing, that require high-speed network to support. Currently, congestion control for high-speed network is still in the initial stage, there have been some representative algorithms, such as HSTCP, STCP, BICTCP, FAST TCP and so on. These new algorithm largely improves the network performance. by adjusting the congestion window of the increment mechanism or the reduction mechanism. The FAST algorithm based on link delay estimation, compared with other methods has certain advantages, but there are still some performance shortcomings.This article analyzes the traditional congestion control algorithm TCP Reno, a brief description of several high-speed network congestion control algorithm and its evaluation criteria. Through theoretical and experimental simulation system study the FAST congestion control algorithm and point out the FAST algorithm in fairness, convergence deficiency. This paper calculate the propagation delay over-estimated by estimating the number of data streams and the bandwidth of current network data link and then eliminate the over estimation of the error, correct data stream propagation delay, so that the link in the Data flow to the fair. As for the convergence problem by changing the strategy of adjusting the slow start threshold to eliminate the impact of the convergence and the overshoot caused by exchanging the network parameters, shorten the convergence time and reduced overshoot. In the NS2 simulation environment, this paper simulates the improved FAST algorithm and the simulation results also show that the improved algorithm can improve the fairness and reduce the link convergence time.