TP-Link T1700G-28TQ User Manual page 171

2. WRR-Mode: Weight Round Robin Mode. In this mode, packets in all the queues are sent in
order based on the weight value for each queue and every queue can be assured of a certain
service time. The weight value indicates the occupied proportion of the resource. WRR queue
overcomes the disadvantage of SP queue that the packets in the queues with lower priority
cannot get service for a long time. In WRR mode, though the queues are scheduled in order,
the service time for each queue is not fixed, that is to say, if a queue is empty, the next queue
will be scheduled. In this way, the bandwidth resources are made full use of. The default
weight value ratio of TC0, TC1, TC2, TC3, TC4, TC5, TC6 and TC7 is 1:2:4:8:16:32:64:127.
3. SP+WRR-Mode: Strict-Priority+Weight Round Robin Mode. In this mode, the switch provides
two scheduling groups, SP group and WRR group. Queues in SP group and WRR group are
scheduled strictly based on Strict-Priority mode while the queues inside WRR group follow the
WRR mode. In SP + WRR mode, TC7 and the queue with its weight value set as 0 are in the
SP group; other queues, with none-zero weight value, belong to the WRR group and the
weight value can be customized, ranging from 0 to 127. In this way, when scheduling queues,
the switch allows TC7 and zero-weight-value queue to occupy the whole bandwidth following
the SP mode and the queues in the WRR group will take up the bandwidth according to their
ratio.
Figure 11-4 SP-Mode
Figure 11-5 WRR-Mode
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