Packet Forwarding Scheduling Algorithm FC-WFQ for iSCSI Virtualization Switch
Chen Jin-zhong · Dianzi xuebao · 2013
Different from traditional IP switches,the iSCSI virtualization switch not only realizes the IP packets transmission,but also performs the processing of TCP,iSCSI and SCSI protocol.The short packet first scheduling algorithm insures the priority transmission of iSCSI command and status PDUs(Packet Data Unit),but does not impose restrictions on the forwarding bandwidth of such packets.Moreover,it is lack of quantitative analysis on iSCSI data flow characteristics for this method.The mathematical model of iSCSI PDUs forwarding process within the iSCSI virtualization switch was created by queuing theory.Then the packet scheduling algorithm called FC-WFQ(Flow Control-WFQ) was designed for the iSCSI virtualization switch used in the SANs.Finally the iSCSI virtualization switch with FC-WFQ was tested under certain network scenarios built by ns-2.In the experiments,while the command arrival rate and the ratio of read/write commands were changing,the FC-WFQ dynamically adjusted the forwarding bandwidth weight of each packet flow correspondingly.The results show that the scheduling algorithm can greatly reduce the mean response time of the read/write tasks,and significantly improve the throughput of the iSCSI virtualization switch.