Figure 15 SP queuing
Packets to be sent through
15, 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 the high priority queue to make sure that they are always served first, and assign common service
packets to the low priority queues and 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. This may cause lower priority traffic to starve to death.
WRR queuing schedules all the queues in turn to ensure every queue is served for a certain time, as
Figure 16 WRR queuing