QPRED:一种公平多级主动缓冲管理算法

QPRED: A Fair Multi-Level Buffer Manager Algorithm

DiffServ模型是当前实现IPQoS的体系结构之一 ,在其实现中 ,缓冲管理技术是很重要的一个方面 .根据DiffServ模型实现的需要 ,在分析现有缓冲管理算法的基础上 ,提出了QPRED多级主动缓冲管理算法 ,这种算法在分组分类的粒度上提供了分级的缓冲管理能力 ,并将每一类分组的缓冲状态引入到了分组丢弃概率的计算中 ,同时结合优先级因子实现了类和类之间在优先级意义上的公平性 .通过分析和仿真 ,证明了QPRED算法的性能 .与现有的缓冲管理算法相比 ,QPRED多级主动缓冲管理算法更适合于DiffServ模型的要求 .

DiffServ model is an important IP QoS architecture. In mechanism of realizing DiffServ model, buffer manager is an important aspect. But the present buffer manager algorithms are not able to solve DiffServ’s problems. According to the needs of DiffServ model and based on the analysis of present buffer manager algorithms, this paper gives QPRED muliti -level buffer manager algorithm. QPRED algorithm is based on the RED algorithm, but it is changed so that it can be used in the DiffServ model. At first QPRED algorithm provides the grade of buffer manager at the packer classification granularity, so it can solve the need of AF PHB. Secondly, by inducing buffer state (buffer queue length in bytes) of every packet classification into the packet drop probability calculation , the algorithm can prevent some class packet from occuping the buffer for long time. And lastly, by integrating priority parameter, the algorithm realizes fairness in every packet class at the priority meaning. Through analysis and simulation, QPRED algorithm’s benefit is proved. In this paper, the detailed QPRED algorithm is given too, which is easy to realize and its calculation cost is low. Comparing with present buffer manager algorithms, QPRED algorithm is more fit feasible DiffServ model.