提供服务质量保证是目前lnternet的重要研究课题之一,其核心问题是实现不同业务流的分类转发。本文分析了基于EDF的优先级队列PQBEDF算法,由于PQBEDF方案中动态优先级随时间片变化过快从而降低了高优先级队列服务质量,针对这个不足我们引入阈值来控制计数器一个时间片以后是否加1,从而为每类业务的信元保证一个最小的服务速率。 To provide service quality assurance is one of the important research topics of lnternet at present. The core problem is to realize the classification and forwarding of different service flows. This paper analyzes the EDF-based priority queue PQBEDF algorithm, because PQBEDF program dynamic priority changes too fast with the time slice thus reducing the high-priority queue service quality, in view of this problem, we introduce a threshold to control the counter after a time slice is added 1, thus ensuring a minimum service rate for the cells of each type of service.