TCP流带宽公平性研究

为了缓解TCP拥塞控制机制对于往返时间（RTT）较小流的偏向问题，现有方法在网络拥塞程
度严重时由于对RTT较大流的过分保护而不能有效地工作。为了解决这一问题，通过引进自适应的思想并
结合主动队列机制BLUE提出了改进方法。根据网络的拥塞状况动态调整对RTT较大流的保护程度，随着网
络拥塞程度的增大逐渐减小对RTT较大流的保护程度。仿真试验表明，在任何拥塞程度情况下，所提出的
机制均能有效地保障TCP流的带宽公平性。

Study on bandwidth fairness of TCP flows

To mitigate the bias of TCP congestion mechanisms to short RTT flows, the existing methods cannot work well when network congestion level is high due to the over protecting to long RTT flows. To solve this problem, an improved method based on adaptive thoughts was proposed and realized by combining the method with an active queue mechanism-BLUE. Dynamically adjusting the protecting strength to long RTT flows according to the networks congestion level, the method gradually decreases the protection to long RTT flows with the increase of networks congestion level. Simulation results show that the proposed mechanism can guarantee the bandwidth fairness of TCP flows effectively at any congestion level of networks.