大带宽时延积网络TCP Vegas自适应慢启动算法

An Adaptive Slow Start Algorithm of TCP Vegas for Large BDP Networks

TCP Vegas具有比TCP Reno更好的带宽利用能力和稳定性,但是在带宽时延积较大的网络中,TCP Vegas会出现慢启动过早结束、拥塞窗口过小的问题,降低了传输效率。文中在分析慢启动结束的原因和条件的基础上,提出一种对临时性排队时延进行估计,将其排除后再进行慢启动结束条件判断的TCP Vegas慢启动算法,对不同网络条件有自适应能力。仿真结果表明本算法能有效避免慢启动过早结束,使TCP性能明显改善。

TCP Vegas performs better than TCP Reno with respect to network utilization and stability. But TCP Vegas is inefficient in the large BDP networks. TCP Vegas stops slow start too early, and the congestion window is too small to fully make use of available bandwidth. An adaptive slow start （ASS） algorithm is presented based on the reason and condition of the termination of Vegas slow start. The temporary queue delay is estimated and eliminated before Vegas calculates and judges. Simulation results show that ASS algorithm can get right congestion window and improve the performance.