Edge-Core ECS4660-28F, Management Manual, Page: 307 / 2020

C
HAPTER
10
| Class of Service
Layer 2 Queue Settings
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C
OMMAND
U
SAGE
◆
Strict priority requires all traffic in a higher priority queue to be
processed before lower priority queues are serviced.
◆
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.
◆
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 one of the queuing modes that use a combination
of strict and weighted queuing.
◆
The specified queue mode applies to all interfaces.
◆
Protocols used to synchronize distributed switches use packets of 1588
bytes to control the synchronization process. This switch therefore
assigns packets of this size to the highest priority queue to ensure
quick passage.
P
ARAMETERS
These parameters are displayed:
◆ Interface – Port or trunk identifier.
◆ 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, and servicing each queue in a
round-robin fashion. (This is the default setting.)
■
Strict and WRR – Uses strict priority on the high-priority queues
and WRR on the rest of the queues.
◆ Queue ID – The ID of the priority queue. (Range: 0-7)
◆ Strict Mode – If “Strict and WRR” mode is selected, then a
combination of strict service is used for the high priority queues and