Research Of Congestion Control Algorithm Based On XCP Protocol

Explicit Control Protocol (XCP) is newly proposed for high bandwidth-delay product networks. XCP achieves a significant advance in Internet congestion control by carrying the control information in the congestion header and generalizing the Explicit Congestion Notification proposal (ECN). The routers can inform the sender about the degree of congestion at the bottleneck instead of just congestion or not. This allows senders to increase or decrease their sending windows responsively according to status of network. XCP outperforms TCP both in traditional environments and in high bandwidth-delay product networks,and further remains efficient, fair, and stable.First of all, the thesis introduces the problems of TCP briefly. With the per-flow product of bandwidth and latency increases, TCP becomes inefficient and prone to instability, regardless of the queuing scheme. And then introduce the reseach situation of congestion control at home and abroad. Then the thesis analysises the structure and the performance algorithm to the XCP protocol. The results of simulation demonstrate that the eXplicit Control Protocol(XCP) outperforms TCP and remains efficient, fair, and stable in the large bandwidth-delay product (BDP) networks. Afterwards, based on the research of the parameter of XCP, we discover that parameterαinfecting the network utilization obviously, parameterβinfecting the time of empting queue in the router. All the parameters are the trade-off between of efficiency and stability, which still have regulating range .With the changed data stream numbers and various link in the network,the parameter a of XCP limits the use of bandwidth. so, adaptive algorithm had been brought forward. It can adjust a according to the state of the network witch can be judged by the changes in the average of queue. Simulation results prove that the scheme is effective. Using NS2 to analyse the network's throughput and bandwidth utilization of the network of the improved algorithms, the simulation results show that, Adaptive algorithm can improve Bandwidth utilization of the network, and keep Stability network's throughput.