HP 1910 User Manual page 510

Figure 475 SP queuing
A typical switch provides eight queues per port. As shown in Figure 475, 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 strictly according to the descending order of priority. It 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 common service
(such as Email) 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 the
higher priority queues have packets. This causes lower priority traffic to starve to death.
WRR queuing
WRR queuing schedules all the queues in turn to make sure that every queue can be served for a certain
time, as shown in Figure 476.
Figure 476 WRR queuing
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