点到多点ABR业务的拥塞控制机制

Point to Multipoint ABR Service Congestion Control Mechanism

在异步传递模式（ＡＴＭ）网络中，可用比特速率（ＡＢＲ）业务类型主要面向数据通信服务，ＡＢＲ采用基于速率的拥塞控制机制．在点到多点的通信环境下，ＡＢＲ拥塞控制要解决的一个关键问题是如何将信元接收端的反馈信息进行合并，使得信元发送端以所有叶节点能够支持的速率发送信元．讨论了点到多点环境下ＡＢＲ拥塞控制所面临的主要问题，提出了对合并算法的性能评价准则．分析了现有的几个算法的优缺点，并在此基础上提出了一个改进的算法，从实现的复杂性、响应速度、可扩展性及噪音问题等几方面对这些算法进行了比较．

In ATM networks, ABR service is mainly used for data communication, and it adopts rate based congestion control mechanism. Under the point to multipoint communication environment, the key problem is how to merge the feedback information from leaf points in order to control the source rate to the minimum rate indicated by all the leaf points. This paper discusses the problems that the ABR mechanism meets and proposes criteria of evaluating the algorithms. It also analyses the characteristics of some existing algorithms, and proposes a new one. The performances between them are compared in terms of implementation complexity, response speed, scalability and merging noise.