HP A6600 Configuration Manual page 77

WRR queuing
WRR queuing schedules all the queues in turn to ensure every queue can be served for a certain time, as
shown in Figure
Figure 25 WRR queuing schematic diagram
Packets to be sent through
this port
Assume a port provides eight output queues. 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, 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 at least 5 Mbps of bandwidth, 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 when the queues are scheduled in turn, the service time for each
queue is not fixed. If a queue is empty, the next queue is scheduled immediately. This improves bandwidth
resource use efficiency.
WRR queuing falls into the following types:
Basic WRR queuing—Contains multiple queues. Configure the weight, percentage (or byte count) for

each queue, and WRR schedules these queues based on the user-defined parameters in a round robin
manner.
 Group-based WRR queuing—All queues are scheduled by WRR. Divide the output queue to WRR
priority queue group 1 and WRR priority queue group 2. Round robin queue scheduling is performed
for group 1 first. If group 1 is empty, round robin queue scheduling is performed for group 2.
WRR queuing with the maximum delay—Assures packets in the highest-priority queue are transmitted

within the specified maximum delay, making it different from basic WRR queuing.
25.
Queue 0 Weight 1
Queue 1 Weight 2
......
Queue N-2 Weight N-1
Packet
classification
Queue N-1 Weight N
Sent packets
Queue Sending queue
scheduling
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Interface