分组调度的基本方法有2种:基于优先级的方法和基于轮循的方法.一般的轮循算法对所有队列进行轮循调度,但是由于分组长度不固定,带宽公平性受到很大限制.而差额轮循算法(DRR)通过为每个队列分配带宽配额并且维护一个计数器的方法,解决了带宽分配的公平性问题,缺陷是不能以较为平滑的方式调度输出.文章通过在节点处加入基于网络演算的流量整形器,弥补了这一缺陷,从而使信息流更加平滑的输出,提高了网络服务质量.%Aim.The introduction of the full paper reviews some papers in the open literature, points out their shortcoming that the common round-robin algorithm schedules the queues with unequal packet lengths and then it outlines how to suppress it.Sections 1 through 4 explain what we believe to be our new and better algorithm.Section 1 is entitled the basics of network calculus; its core is that we define the arrival curve, service curve, minus-plus algebra and its convolution and deconvolution.Section 2 is entitled shaper with a finite number of buffers; its core is that we obtain the number of discarded packets, buffering zone, delay and the maximum delay through network calculus.To shape the input traffic of a network, section 3 introduces the token bucket algorithm.Section 4 presents the DRR algorithm that assigns each queue a quota and a counter, thus solving the bandwidth fairness problem; the flow chart of the DRR algorithm is given in Fig.2.Section 5 combines the shaper with a finite number of buffers with the DRR algorithm and simulates the input traffic; the simulation results, shown in Figs.4 and 5, and their analysis indicate preliminarily that our new algorithm can smooth the output traffic of a network and improve its quality of service.
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