R3303-HP HSR6800 Routers ACL and QoS Configuration Guide

Figure 26 WRR queuing

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, 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 can get a minimum of 5 Mbps of bandwidth. WRR avoids the disadvantage of SP

queuing that packets in low-priority queues might fail to be served for a long time.

Another advantage of WRR queuing is that when the queues are scheduled in turn, the service time for

each queue is not fixed. If a queue is empty, the next queue will be scheduled immediately. This improves

bandwidth resource use efficiency.

WRR queuing includes the following types:

• Basic WRR queuing—Contains multiple queues. You can 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 the queues are scheduled by WRR. You can 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 that packets in the highest-priority queue are

transmitted within the specified maximum delay, which makes it different from basic WRR queuing.

Queue 0 Weight 1

……

Queue 1 Weight 2

Queue N-2Weight N-1

Queue N-1 Weight N

Packets to be sent through

this port

Sent packets

Interface

Queue

scheduling

Sending queue

Packet

classification