3com S7906E 설치 설명서

5-3

Figure 5-3 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 5, 3, 1, 1, 5, 3,

1, and 1 (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.

WFQ queuing

Figure 5-4 Schematic diagram for WFQ queuing

Queue 1 Band width 1

……

Queue 2 Band width 2

Queue N-1 Band width N-1

Queue N Band width N

Packets to be sent through

this port

Packet

classification

Sent packets

Interface

Sending queue

Queue

scheduling

WFQ is derived from fair queuing (FQ), which is designed for fairly sharing network resources, reducing

the delay and jitter of all traffic. FQ fully consider the interests of all queues to ensure that:

Different queues have fair dispatching opportunities, preventing a single queue from being delayed

for too long.