Operation Manual – QoSH3C S5500-EI Series Ethernet Switches Chapter 4 Congestion Management4-1Chapter 4 Congestion ManagementWhen configuring congestion management, go to these section for information that youare interested in:z Overviewz Congestion Management Policyz Configuring an SP Queuez Configuring a WRR Queuez Configuring SP+WRR Queuesz Displaying and Maintaining Congestion Management4.1 OverviewWhen the rate at which the packets arrive is higher than the rate at which the packetsare transmitted on an interface, congestion occurs on this interface. If there is notenough storage space to store these packets, parts of them will be lost. Packet lossmay cause the transmitting device to retransmit the packets because the lost packetstime out, which causes a malicious cycle.The core of congestion management is how to schedule the resources and determinethe sequence of forwarding packets when congestion occurs.4.2 Congestion Management PolicyQueuing technology is generally adopted to solve the congestion problem. Thequeuing technology is to classify the traffic according to a specified queue-schedulingalgorithm and then use the specified priority algorithm to forward the traffic. Eachqueuing algorithm is used to solve specific network traffic problems and affects theparameters such as bandwidth allocation, delay and delay jitter.The following paragraphs describe strict-priority (SP) queue-scheduling algorithm, andweighted round robin (WRR) queue-scheduling algorithm.1) SP queue-scheduling algorithm
