Operation Manual – QoSH3C S7500 Series Ethernet Switches Chapter 1 QoS Configuration1-10Packets to be sentthrough an interfacePacketclassifyingQueuescheduling2 2- 1 -1ForServicwarding directioned queueOutboundinterface……Queue 1Queue N Weight NWeight 1Queue 2 Weight 2Queue N-1 Weight N-1Figure 1-6 Diagram for WRRThe WRR queue scheduling algorithm schedules all the queues in turn and everyqueue can be assured of a certain service time. Assume there are 8 priority queues ona port. The WRR queue scheduling algorithm assigns a weight value to each queue,which are w7, w6, w5, w4, w3, w2, w1, and w0 respectively. The weight value indicatesthe proportion of obtaining resources. On a 100M port, configure the weight value ofWRR queue-scheduling algorithm to 50, 50, 30, 30, 10, 10, 10 and 10 to w7, w6, w5, w4,w3, w2, w1, and w0 respectively. In this way, the queue with the lowest priority can get5Mbps bandwidth at least, and the disadvantage of the SP queue scheduling algorithmthat the packets in queues with lower priority may get no service for a long time isavoided. Another advantage of the WRR queue scheduling algorithm is that: though thequeues are scheduled in order, the service time for each queue is not fixed, that is tosay, if a queue is empty, the next queue will be scheduled immediately. In this way, thebandwidth resources are fully utilized.1.1.11 Traffic-based Traffic StatisticsThe traffic-based traffic statistics feature is to use ACL rules for traffic identifying andperform traffic statistics on the packets matching the ACL rules. You can get thestatistics of the packets you are interested in through this feature.1.1.12 REDWhen severe congestion occurs, the switch can adopt the random early detection(RED) algorithm to solve the problem of excessive congestion and avoid global TCPsynchronization caused by the tail-drop algorithm.
