ATM网络中ABR业务的开环控制机制

ＡＴＭ网络中ＡＢＲ业务的流量控制是ＡＴＭ论坛的流量管理规范（ＴＭ４．０）中没有完全解决的问题，ＡＢＲ基于速率的闭环控制方案在最大－最小准则下获得了一定进展。但在拥塞发生在信源外或对突发性业务进行控制的情况下，添加开环控制的ＡＢＲ拥塞控制可以获得比闭环控制更佳的作用。研究了ＡＢＲ的开环控制方案，早期的ＵＩＬＩ机制本身存在在一定的问题，在交换机处采用基于计数的ＵＩＬＩ机制能够取得较好的效果。

Open-Loop Control of ABR Service in ATM Networks

In ATM networks, the traffic control of ABR service was only partly solved in ATM forum recommandation TM4.0. The rate based close loop control for ABR under max min fairness has improved the ABR traffic control in some cases. However, in case the connection is source bottlenecked or the service is burst, ABR congest control plus open loop control can do a better job than close loop control. This article studies the open loop control for ABR. It shows that the early UILI control has some defects, UILI based on count at the switch can do a better job.