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Catalyst 3750 Metro Switch Command Reference
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Chapter 2 Catalyst 3750 Metro Switch Cisco IOS Commands
priority-queue
priority-queue
Use the
priority-queue
interface configuration command to enable the egress priority queue on a port.
Use the
no
form of this command to return to the default setting.
priority-queue
out
no priority-queue out
Syntax Description
Defaults
The egress priority queue is disabled.
Command Modes
Interface configuration
Command History
Usage Guidelines
When you configure the
priority-queue out
command, the shaped round robin (SRR) weight ratios are
affected because there is one fewer queue participating in SRR. This means that
weight1
in the
srr-queue
bandwidth shape
or the
srr-queue bandwidth share
interface configuration command is ignored (not
used in the ratio calculation). Before servicing the other queues, SRR services the priority queue until it
is empty.
Follow these guidelines when the priority queue is enabled; otherwise, the egress queues are serviced
based on their SRR weights:
•
If the egress priority queue is enabled, it overrides the SRR shaped and shared weights for queue 1.
•
If the egress priority queue is disabled and the SRR shaped and shared weights are configured, the
shaped mode overrides the shared mode for queue 1, and SRR services this queue in shaped mode.
•
If the egress priority queue is disabled and the SRR shaped weights are not configured, SRR services
the queue in shared mode.
To avoid a loss of priority traffic on an enhanced-services (ES) port when the switch is congested, you
can configure both the egress priority queueing and the strict-priority queueing (low-latency queueing
[LLQ]) features. Note that when you map certain traffic classes to the egress priority queue, they are not
automatically placed into the strict-priority queue. You must configure both the
priority-queue out
interface configuration and the
priority
policy-map class configuration commands. For more
information, see the
“priority” section on page 2-363
.
out
Enable the egress priority queue.
Release
Modification
12.1(14)AX2
This command was introduced.