一种改善RTT公平性的TCP慢启动算法  

A New TCP Slow Start Algorithm to Improve RTT Fairness

作　　者：王思思[1] 朱金鹏[1] 王建峰[2] 

机构地区：[1]空军指挥学院,北京100097 [2]空军工程大学电讯工程学院,陕西西安710077

出　　处：《空军工程大学学报（自然科学版）》2009年第3期86-90,共5页Journal of Air Force Engineering University(Natural Science Edition)

基　　金：国防预研基金资助项目(51422010108JB3202);陕西省自然科学基金资助项目(SJ08F14)

摘　　要：针对Internet拥塞控制策略在慢启动阶段中,具有不同RTT的TCP连接在竞争带宽时存在的不公平性,以及慢启动后期窗口增长过快等问题,提出一种改善RTT公平性的TCP慢启动新算法。新算法在慢启动初期窗口仍保持指数增长,慢启动后期引入与RTT成正比的窗口增长控制因子,使RTT较大的TCP连接窗口增加较快,反之增加较慢。性能分析和仿真结果表明,新算法在慢启动后期减缓了拥塞窗口的增长速度,削弱了RTT较小的TCP连接竞争带宽的侵略性,在一定程度上保证了不同RTT的TCP连接共享带宽的公平性,并且保持了标准慢启动算法的端到端语义,简单易实现,具有一定的理论和实际应用价值。To solve the problems such as the unfairness existing when standard TCP connects with different RTT competing bandwidth, the window over -fast growth caused in the late phase of slow start and etc. , a new TCP slow start algorithm for improving, termed SS ＋, is proposed. In the early slow start phase, using SS ＋ can keep the congestion window exponential grow; in the late phase, the window control growth factor in direct propor- tion to RTT is introduced to increase the congestion window of TCP connecting with larger RTT faster, otherwise the increase will be slower. Performance analysis and simulation results show that by using SS ＋ algorithm the congestion window growth rate is slowed down and the TCP connection with smaller RTT in the aggressive bandwidth competition is weakened in the late slow start phase. To a certain extent, by using SS ＋ algorithm a fair sharing of available bandwidth between TCP connections with different RTT is obtained. And SS ＋ algorithm is easy to realize and only requires the TCP source revised. This SS ＋ algorithm has some theoretical and practical application value.

关 键 词：拥塞控制 TCP 慢启动 RTT公平性 

分 类 号：TP393[自动化与计算机技术—计算机应用技术]