Class of Service Configuration

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3

Selecting the Queue Mode

You can set the switch to service the queues based on a strict rule that requires all
traffic in a higher priority queue to be processed before lower priority queues are
serviced, or use Weighted Round-Robin (WRR) queuing that specifies a relative
weight of each queue.
Command Usage
• Strict priority requires all traffic in a higher priority queue to be processed before
lower priority queues are serviced.
• WRR uses a relative weighting for each queue which determines the amount of
packets the switch transmits every time it services each queue before moving on
to the next queue. Thus, a queue weighted 8 will be allowed to transmit up to 8
packets, after which the next lower priority queue will be serviced according to it’s
weighting. This prevents the head-of-line blocking that can occur with strict priority
queuing.
Command Attributes
•WRR - Weighted Round-Robin shares bandwidth at the egress ports by using
scheduling weights with default values of 1, 2, 4, 8, for queues 0 through 3,
respectively. (This is the default selection.)
•Strict - Services the egress queues in sequential order, transmitting all traffic in the
higher priority queues before servicing lower priority queues.
Web – Click Priority, Queue Mode. Select Strict or WRR, then click Apply.
Figure 3-111 Queue Mode
CLI – The following sets the queue mode to WRR priority service mode.
Console(config)#queue mode wrr 4-245
Console(config)#exit
Console#show queue mode 4-248
Queue mode: wrr
Console#