网络TCP/RED算法稳定性研究

主动队列管理算法(AQM)是IETF推荐的基于路由器拥塞控制的关键技术,它和TCP拥塞控制相结合,是解决目前Internet拥塞控制问题的一个主要途径。主动队列管理算法中,随机早期检测(RED)提供网络拥塞避免和拥塞控制机制。RED拥塞控制机制的基本思想是通过计算平均队列长度估计值来计算包标记概率,实现早期拥塞通知。本文针对在TCP/RED系统中,对由于平均队列长度变化而出现的稳定性问题进行了分析研究,在具体条件下通过对4个参数的设置来分析系统的稳定性。使用NS2仿真软件对RED算法进行一系列的仿真实验。实验结果表明,在不同网络负载的情况下,平均队列长度和包标记概率变化很大。最后,针对RED自身稳定性问题提出改进方案。

Research on stability of TCP/RED algorithm of networks

Active queue management (AQM) is recommended by IETF as the key congestion control technology of based on routers. In Internet,active queue management algorithm of random early detection(RED) algorithm provides congestion avoidance and control mechanisms. RED is introduced to calculate the average queue length evaluation by which calculated the packet-making probability and notify the connection. It has been found that a bottleneck RED gateway of TCP/RED system can become instability in terms of the average queue length. By applying the TCP/RED dynamic model,this paper established some explicit conditions in order to analyze the stability performance with regulating the four parameters. A serial of simulation had been done based on NS2 simulator. The results indicated that the average queue length and packet-marking probability changed greatly in the condition of different network load.At last,an improved scheme aims at the stability of RED is bringed forward.