Research And Improve Of TCP Congestion Control Algorithm Over Large BDP Network

In the computer network research, the congestion control is an active field and TCP congestion control is the mainstream of it as more than 60% of traffic transmitted via TCP protocols. Nowadays, with the improvements of network technology, the Internet tends to develop in a trend of diversification and a high bandwidth-delay product(HBDP). Therefore, it is difficult to meet the needs of the network with traditional TCP Reno algorithm and a wide range of new TCP congestion algorithm has been developed for the demand of different network conditions.An improved algorithm-W-Cubic has been put forward based on the Cubic algorithm and its bad friendliness, over-radical increasing and the improper adjustment mechanism of congestion window has been taken into account. The new algorithm adjusts the congestion window with the adoption of two branches. Before the congestion, it is the mechanism of measuring the current number of the router cache packet, while, after the congestion, it is the current usable bandwidth obtained by the bandwidth estimation algorithm based on the measurement of ACK receiving rate.In this paper, the simulation environment was constructed with NS-3 network simulator by six common TCP congestion control algorithm and the W-Cubic, respectively. The congestion control algorithms were assessed by the parameter of efficiency, fairness, friendliness, astringency and stability, both in the high and low bandwidth delay product of network simulation environment. In addition, the parameters were designated by the dual weighting method. It indicated that the W-Cubic algorithm has a good performance both in the high and low bandwidth delay product, which showed the effectiveness of the improvement.