Research On Network Congestion Control And Simulation

The development of congestion control algorithm has a history of more than twenty years. Every step makes possible higher bandwidth utilization rate. From RFC 1122 to TCP Tahoe and to the most widely used TCP Reno, each modification has made a big enhancement in its performance. However, as the application field of network technology becomes wider, the congestion control technology has to adapt to it. So, network investigators face challenges of this field all the time.TCP Vegas is one of the most promising mechanisms that may substitute TCP Reno, which is most widely implemented in the current Internet. However, the weakness that TCP Vegas shows in competing with TCP Reno over mixed network scenario has prevented it from being widely implemented. The weakness of TCP Vegas in mixed network scenarios is analyzed, and a new slow start algorithm is presented. The analytic result shows that the improved slow start algorithm can generate a better initial value for congestion avoidance, so that the throughput is improved.Then this paper studies admission control algorithm in the application level, and improves the performance of Web server. By establishing its mathematical model, we confirm the validation of the modification. At the same time, this paper provides a way to compute TO rate.Although analytical model has its own advantages—when the application background changes, it can foresee the effects — simulation can further test its effect. So, we also study NS-2 in this paper and do some experiments by using it.