TCP流的带宽公平性保证机制研究

端到端的TCP拥塞控制机制使得TCP连接获得的瓶颈带宽反比于RTT。为了缓解TCP对于RTT较小流的偏向，区分服务的流量调节机制在RTT较小的流取得目标速率且获得多余资源的情况下可以确保RTT较大流不至于饥饿。现有的方法在网络拥塞程度较重或者RTT差异较大时不能有效地工作，因此提出了一种改进方法。其主要思想就是根据网络的拥塞程度自适应地调整对RTT较大流的保护程度。大量的仿真试验表明，所提的机制能有效保障TCP流的带宽公平性并且比现有方法具有更好的性能。

STUDY ON THE MECHANISM TO GUARANTEE THE BANDWIDTH FAIRNESS OF TCP FLOWS

The end-to-end TCP congestion controls casuse the throughput of TCP connection inversely proportional to the connection Round Trip Time(RTT).To mitigate TCP bias to short RTT connections,a differentiated service traffic conditioner can ensure connections with long RTT do not starve when connections with short RTT get all extra resource after achieving the target rate.The existing methods for RTT-aware conditioner cannot work well when congestion status is severe or the RTT difference of TCP flows is large.Thus and improved method is proposed.Its main idea is adaptively adjusting the degree of protection to flows with long RTT according to the congestion status of networks.Extensive simulation experiments show that the proposed mechanism can guarantee the bandwidth fairness of TCP flows effectively and outperform the existing methods.