Selecting The Queue Mode; Setting The Service Weight For Traffic Classes; Figure 3-133 Queue Mode - Samsung iES4028F Management Manual

3
Configuring the Switch

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.
CLI – The following sets the queue mode to strict priority service mode.
Console(config)#queue mode strict
Console(config)#exit
Console#show queue mode
Queue mode: strict

Setting the Service Weight for Traffic Classes

This switch uses the Weighted Round Robin (WRR) algorithm to determine the
frequency at which it services each priority queue. As described in "Mapping CoS
Values to Egress Queues" on page 3-232, the traffic classes are mapped to one of
the four egress queues provided for each port. This weight sets the limit for the
number of packets the switch will transmit each time the queue is serviced, and
subsequently affects the response time for software applications assigned a specific
priority value.
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Figure 3-133 Queue Mode

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