C
HAPTER
34
| Class of Service Commands
Priority Commands (Layer 2)
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queue mode This command sets the scheduling mode used for processing each of the
class of service (CoS) priority queues. The options include strict priority,
Weighted Round-Robin (WRR), or a combination of strict and weighted
queuing. Use the no form to restore the default value.
SYNTAX
queue mode {strict | wrr | strict-wrr [queue-type-list]}
no queue mode
strict - Services the egress queues in sequential order, transmitting
all traffic in the higher priority queues before servicing lower priority
queues. This ensures that the highest priority packets are always
serviced first, ahead of all other traffic.
wrr - Weighted Round-Robin shares bandwidth at the egress ports
by using scheduling weights (based on the queue weight
command), and servicing each queue in a round-robin fashion.
strict-wrr - Uses strict or weighted service as specified for each
queue.
queue-type-list - Indicates if the queue is a normal or strict type.
(Options: 0 indicates a normal queue, 1 indicates a strict queue)
DEFAULT SETTING
Strict and WRR, with Queue 3 using strict mode
COMMAND MODE
Global Configuration
COMMAND USAGE
â—† The switch can be set to service the port queues based on strict
priority, WRR, or a combination of strict and weighted queueing.
â—† Strict priority requires all traffic in a higher priority queue to be
processed before lower priority queues are serviced.
â—† WRR queuing specifies a relative weight for each queue. WRR uses a
predefined relative weight for each queue that determines the
percentage of service time the switch services each queue before
moving on to the next queue. This prevents the head-of-line blocking
that can occur with strict priority queuing. Use the queue weight
command to assign weights for WRR queuing to the eight priority
queues.
â—† If Strict and WRR mode is selected, a combination of strict and
weighted service is used as specified for each queue. Regardless of the
selected mode, the queues are processed sequentially from high to
lower priority (i.e., queues 3 to 0). The queues assigned to use strict or
WRR priority should be specified using the queue-type-list parameter.
â—† A weight can be assigned to each of the weighted queues (and thereby
to the corresponding traffic priorities). This weight sets the frequency
at which each queue is polled for service, and subsequently affects the
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