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WFQ is similar to WRR. On an interface with group-based WFQ queuing enabled, you can assign
queues to the SP group. Queues in the SP group are scheduled with SP. The SP group has higher
scheduling priority than the WFQ groups. The difference is that WFQ enables you to set guaranteed
bandwidth that a WFQ queue can get during congestion.
Queue scheduling profile
Queue scheduling profiles support three queue scheduling algorithms: SP, WRR, and WFQ. In a
queue scheduling profile, you can configure SP + WRR or SP + WFQ. When the three queue
scheduling algorithms are configured, SP queues, WRR groups, and WFQ groups are scheduled in
descending order of queue ID. In a WRR or WFQ group, queues are scheduled based on their
weights. When SP and WRR groups are configured in a queue scheduling profile, the following
figure shows the scheduling order.
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Queue 7 has the highest priority. Its packets are sent preferentially.
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Queue 6 has the second highest priority. Packets in queue 6 are sent when queue 7 is empty.
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Queue 3, queue 4, and queue 5 are scheduled according to their weights. When both queue 6
and queue 7 are empty, WRR group 1 is scheduled.
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Queue 1 and queue 2 are scheduled according to their weights. WRR group 2 is scheduled
when queue 7, queue 6, queue 5, queue 4, and queue 3 are all empty.
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Queue 0 has the lowest priority, and it is scheduled when all other queues are empty.
Priority mapping
When a packet arrives, a device assigns values of priority parameters to the packet for the purpose
of queue scheduling and congestion control.
Priority mapping allows you to modify the priority values of the packet according to priority mapping
rules. The priority parameters decide the scheduling priority and forwarding priority of the packet.
Port priority
When a port is configured with a priority trust mode, the device trusts the priorities included in
incoming packets. The device can automatically resolve the priorities or flag bits included in packets.
The device then maps the trusted priority to the target priority types and values according to the
priority maps.
When a port is not configured with a priority trust mode but is configured with a port priority, the
device does not trust the priorities included in incoming packets. The device uses its port priority to
look for priority parameters for the incoming packets.
Configuring the port priority
After you configure a port priority for a port, the device uses its port priority to look for priority
parameters for incoming packets.
