H3C Technologies H3C S6300 Series Switches - Manual (Page 53)

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Figure 13 SP queuing
In Figure 13 , SP queuing classifies eight queues on a port into eight classes, numbered 7 to 0 in
descending priority order.
SP queuing schedules the eight queues in the descending order of priority. SP queuing sends packets in
the queue with the highest priority first. When the queue with the highest priority is empty, it sends
packets in the queue with the second highest priority, and so on. You can assign mission-critical packets
to a high priority queue to make sure they are always served first, and common service packets to the low
priority queues to be transmitted when the high priority queues are empty.
The disadvantage of SP queuing is that packets in the lower priority queues cannot be transmitted if
packets exist in the higher priority queues. In the worst case, lower priority traffic might never get
serviced.
WRR queuing
WRR queuing schedules all the queues in turn to ensure every queue is served for a certain time, as
shown in Figure 14 .