Dell PowerConnect 5548 User Guide - Page 646

Configuring QoS Properties Using CLI Commands The following table summarizes the CLI commands for configuring fields in the QoS Properties: Summary page. Table 22-2. QoS Properties CLI Commands CLI Command Description qos cos default-cos no qos cos Defines the default CoS value of a port. Use the no form of this command to restore the default configuration. The following is an example of the CLI command: console(config)# interface gi1/0/15 console(config-if)# qos cos 3 Queue The switch supports eight queues for each interface. Queue number eight is the highest priority queue. Queue number one is the lowest priority queue. Traffic Limitation Methods There are two ways of determining how traffic in queues is handled, Strict Priority and Weighted Round Robin (WRR): • Strict Priority - Egress traffic from the highest-priority queue is transmitted first. Traffic from the lower queues is processed only after the highest queue has been transmitted, thus providing the highest level of priority of traffic to the lowest-numbered queue. • Weighted Round Robin (WRR) - In WRR mode, the number of packets sent from the queue is proportional to the weight of the queue (the higher the weight, the more frames are sent). For example, if all eight queues are WRR and the default weights are used, queue 1 receives 1/15 of the bandwidth (assuming all queues are saturated and there is congestion), queue 2 receives 2/15, queue 3 receives 4/15, and queue 8 receives 8/15 of the bandwidth. The type of WRR algorithm used in the device is not the standard Deficit WRR (DWRR), but rather Shaped Deficit WRR (SDWRR). 646 Dell PowerConnect 55xx Systems User Guide