Research Of Worst-case Fair Queueing Scheduler

With the continued rapid development of Internet-scale, various types of services on the Internet are emerging; particularly the transmission-of multimedia services that the traditional best-effort network service has not satisfied current network. On the other hand, in order to overcome the traditional defects of the structure of Internet, and adapt to new services requirements, a new research direction called network virtualization was come out. For ensuring that running multiple virtual networks, the construction of virtual network maps the user requirements to the corresponding underlying physical network resources, and optimizes the allocation of resources. Queuing scheduler can isolate the resources of links of different virtual networks. Therefore it is significant to study queue scheduling algorithm.At first this paper introduces the basic concepts of queueing scheduler, and analyses the current main two kinds of queue scheduling algorithms:timestamp based scheduling, round-robin-based scheduling, proposes the shortcomings of these algorithms. Then this paper proposes a new queue scheduling algorithm based on DRR scheduler--PWFDRR. In order to guarantee worst -case fairness and prevent large-weight flows from affecting significantly small-weight flows in terms of packet delay, the algorithm limits the transmission order of each flow in every round, and also introduces the concept of priority into DRR algorithm, which allows high-priority flows to obtain transmission service more fastly. The theoretical analysis and experimental results demonstrate that PWFDRR is better than the previous algorithms in terms of fairness and delay guarantee.