Queue mode – Brocade Communications Systems Brocate Ethernet Access Switch 6910 User Manual
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Brocade 6910 Ethernet Access Switch Configuration Guide
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Priority Commands (Layer 2)
21
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
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)
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
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.
•
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 response time for software applications assigned a specific priority
value.
•
Service time is shared at the egress ports by defining scheduling weights for WRR, or for the
queuing mode that uses a combination of strict and weighted queuing. Service time is
allocated to each queue by calculating a precise number of bytes per second that will be
serviced on each round.