5-3
Figure 5-2
Schematic diagram for WRR queuing
Assume there are eight output queues on a port. WRR assigns each queue a weight value (represented
by w7, w6, w5, w4, w3, w2, w1, or w0) to decide the proportion of resources assigned to the queue. On
a 100 Mbps port, you can configure the weight values of WRR queuing to 50, 30, 10, 10, 50, 30, 10, and
10 (corresponding to w7, w6, w5, w4, w3, w2, w1, and w0 respectively). In this way, the queue with the
lowest priority is assured of 5 Mbps of bandwidth at least, thus avoiding the disadvantage of SP queuing
that packets in low-priority queues may fail to be served for a long time.
Another advantage of WRR queuing is that while the queues are scheduled in turn, the service time for
each queue is not fixed, that is, if a queue is empty, the next queue will be scheduled immediately. This
improves bandwidth resource use efficiency.
SP+WRR queuing
You can implement SP+WRR queue scheduling on a port by assigning some queues on the port to the
SP scheduling group and the others to the WRR scheduling group (that is, group 1 and group 2).
Packets in the SP scheduling group are scheduled preferentially. When the SP scheduling group is
empty, packets in the WRR scheduling group are scheduled. Queues in the SP scheduling group are
scheduled by SP. Queues in the WRR scheduling group are scheduled by WRR.
Congestion Management Configuration Methods
Complete the following tasks to achieve congestion management:
Task
Remarks
Configuring SP Queuing
Optional
Configure WRR Queuing
Optional
Configuring SP+WRR Queuing
Optional
