应用于非对称网络的改进TCP Vegas协议

TCP Vegas协议已被证明比传统TCP协议性能优越,但在非对称网络中的性能不理想.文中提出针对这一缺陷的改进算法.首先基于确认包中的ecn_to_echo_位估计反向链路的拥塞概率,证明了拥塞概率和分组的环型流程时间(RTT)成正比.接着,通过监测拥塞概率的变化,求出RTT的变化,进而求得拥塞前的实际RTT,并以此为基础执行TCP Vegas流量控制协议.基于NS-2的仿真实验表明,文中算法在正、反向链路出现拥塞时的性能均优于现有Vegas算法.

Enhanced TCP Vegas Protocol for Asymmetric Networks

It has been proved that the TCP Vegas protocol underutilizes the available bandwidth in asymmetric networks although it possesses better performance than the traditional TCP protocol.In order to solve this problem,an enhanced TCP Vegas algorithm is proposed.In this algorithm,the ecn_to_echo_bits in the acknowledge packets are first used to estimate the congestion probability in the backward path,proving that the change of Round-Trip-Time(RTT) is directly proportional to the change of congestion probability.Then,when backward congestion occurs,the change of RTT is estimated by monitoring the change of congestion probability.Thus,the actual RTT before the congestion is obtained,which is used to implement the TCP Vegas protocol.The simulations based on NS-2 show that the proposed algorithm is more applicable than the existing Vegas algorithm when the congestion occurs both in forward and backward paths.