Brocade 6910 Ethernet Access Switch Configuration Guide (Supporting R2.2.0.0) - Manual (Page 472)

416 Brocade 6910 Ethernet Access Switch Configuration Guide
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Priority Commands (Layer 2)
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 - Strict priority is used for the high-priority queues and WRR for the rest of the
queues.
queue-type-list - Indicates if the queue is a normal or strict type. (Options: 0 indicates a
normal queue, 1 indicates a strict queue)
NOTE
When using strict-wrr mode, assign strict mode on to higher priority queues; that is, the
higher numbered queues by default settings. Otherwise, the switch will not be able to
process the queues in a reliable manner due to chip set limitations.
Default Setting
WRR
Command Mode
Global Configuration
Command Usage
• The switch can be set to service the port queues based on strict priority, WRR, or a
combination of strict and weighted queueing.
• Strict priority requires all traffic in a higher priority queue to be processed before lower priority
queues are serviced.
• Weighted Round Robin (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.
• If Strict and WRR mode is selected, a combination of strict service is used for the high priority
queues and weighted service for the remaining queues. The queues assigned to use strict
priority should be specified using the Strict Mode field parameter.