Configuring Low-Latency Queueing With Strict Priority Queueing; Restrictions - Cisco ASR 9000 Series Configuration Manual

How to Configure QoS Congestion Management on Cisco ASR 9000 Series Routers
Command or Action
Step 14
end
or
commit
Example:
RP/0/RSP0/CPU0:router(config-if)# end
or
RP/0/RSP0/CPU0:router(config-if)# commit
Step 15
show policy-map interface type instance
[input | output]
Example:
RP/0/RSP0/CPU0:router# show policy-map
interface gigabitethernet 0/2/0/0

Configuring Low-Latency Queueing with Strict Priority Queueing

The priority command configures low-latency queueing (LLQ), providing strict priority queueing (PQ).
Strict PQ allows delay-sensitive data, such as voice, to be dequeued and sent before packets in other
queues are dequeued. When a class is marked as high priority using the priority command, we
recommend that you configure a policer to limit the priority traffic. This configuration ensures that the
priority traffic does not starve all of the other traffic on the line card, which protects low priority traffic
from starvation. Use the police command to explicitly configure the policer.

Restrictions

Within a policy map, you can give one or more classes priority status. When multiple classes within a
single policy map are configured as priority classes, all traffic from these classes is queued to the same
single priority queue.
The bandwidth, priority, and shape average commands should not be configured together in the same
class.
Cisco ASR 9000 Series Aggregation Services Router Modular Quality of Service Configuration Guide
QC-48
Configuring Modular Quality of Service Congestion Management on Cisco ASR 9000 Series Routers
D r a f t — C i s c o C o n f i d e n t i a l
Purpose
Saves configuration changes.
When you issue the end command, the system prompts
•
you to commit changes:
Uncommitted changes found, commit them before
exiting(yes/no/cancel)?
[cancel]:
– Entering yes saves configuration changes to the
running configuration file, exits the configuration
session, and returns the router to EXEC mode.
Entering no exits the configuration session and
–
returns the router to EXEC mode without
committing the configuration changes.
Entering cancel leaves the router in the current
–
configuration session without exiting or
committing the configuration changes.
Use the commit command to save the configuration
•
changes to the running configuration file and remain
within the configuration session.
(Optional) Displays policy configuration information for all
classes configured for all service policies on the specified
interface.
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