基于RTT的TCP流带宽公平性保障机制  

A RTT-based mechanism to guarantee the bandwidth fairness of TCP flows

作　　者：张顺亮[1] 叶澄清[1] 李方敏[2] 

机构地区：[1]浙江大学计算机学院,浙江杭州310027 [2]湘潭工学院信息系,湖南湘潭411201

出　　处：《通信学报》2004年第5期131-137,共7页Journal on Communications

基　　金：湖南省自然科学基金资助项目(01JJY2064)

摘　　要：TCP端到端的拥塞控制机制使得TCP连接获得的瓶颈带宽反比于RTT(数据包往返时间)。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。现有的基于RTT的流量调节机制在网络拥塞程度较轻时非常有效,但是当网络拥塞程度较重时,由于对RTT较大流的过分保护而导致RTT较小流饥饿。因此,通过引进自适应的思想提出了改进方法,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的方法具有更好的强壮性。The end-to-end TCP congestion controls cause 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 work well when the congestion level is low. However, when congestion level is high, they often over-protect the flows with long RTT and starve the flows with short RTT. Due to this problem, an improved method based on adaptive thoughts 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.

关 键 词：带宽公平性 拥塞控制 RTT 自适应方法 主动队列管理 

分 类 号：TP393[自动化与计算机技术—计算机应用技术]