Users Guide

Dell PowerConnect 55xx Systems User Guide 647
Combination of WRR and Strict Priority
The priority for handling traffic can be selected for each queue. When the
queuing mode is Weighted Round Robin for all queues, queues are serviced
according to their weights. If all queues are assigned strict priority, queues are
serviced according to that order.
The following is true if some queues are assigned strict priority and others are
assigned WRR:
• If one queue is assigned strict priority, all higher queues are also assigned
strict priority. Conversely, if a queue is assigned a WRR weight, all lower
queues must also have a WRR weight assigned to them.
• In the above case, traffic for the strict priority queues is always sent before
traffic from the WRR queues. Traffic from the WRR queues is forwarded
only after the strict priority queues have been emptied. The relative
portion from each WRR queue depends on its weight.