Punt policing protects the Route Processor (RP) from having to process noncritical traffic, which increases the CPU bandwidth available to critical traffic. Traffic is placed into different CPU queues based on various criteria. The Punt Policing and Monitoring feature allows you to police the punt rate on a per-queue basis.
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see
Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.
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Packets received on an interface are punted to the Router Processor (RP) for various reasons. Some examples of these various reasons include, unicast and multicast control plane traffic that are destined for a routing protocol process running on the RP, and IP packets that generate Internet Control Message Protocol (ICMP) exceptions such as a Time to live (TTL) expiration. The RP has a limited capacity to process the punted packets, and while some of them are critical for the router operation and should not be dropped, some can be dropped without impacting the router operation.
Punt policing frees the RP from having to process noncritical traffic. Traffic is placed in queues based on various criteria, and you can configure the maximum punt rate for each queue which allows you to configure the system so that packets are less likely to be dropped from queues that contain critical traffic.
Note
Traffic on certain CPU queues could still be dropped, regardless of the configured punt rate, based on other criteria such as the queue priority, queue size, and traffic punt rate.
Traffic on a specific CPU queue may be dropped irrespective of the configured maximum punt rate, based on the queue priority, queue size, and the configured traffic punt rate.
Perform this task to specify the maximum punt rate on the specified queue.
Use the
show platform software infrastructure punt statistics command to verify that punt policing is configured for a queue. If the feature is configured on your interface, the command output displays punt police statistics:
The following example shows how to enables punt-policing, set the maximum punt-rate to 9000 bps, and set the maximum burst-rate to 10000 bps, on queue 20:
Cisco IOS Quality of Service Solutions Command Reference
Traffic marking
“Marking Network Traffic” module
Traffic policing
“Traffic Policing” module
Traffic policing and shaping concepts and overview information
“Policing and Shaping Overview” module
Modular quality of service command-line interface (MQC)
“Applying QoS Features Using the MQC” module
Standards
Standard
Title
None
—
MIBs
MIB
MIBs Link
None
To locate and download MIBs for selected platforms, Cisco IOS XE Software releases, and feature sets, use Cisco MIB Locator found at the following URL:
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Feature Information for Punt Policing and Monitoring
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1 Feature Information for Punt Policing and Monitoring
Feature Name
Releases
Feature Information
Punt Policing and Monitoring
Cisco IOS XE Release 3.5S
The Punt Policing and Monitoring feature allows you to specify a maximum punt rate on a per-queue basis.
For Cisco IOS XE Release 3.5S, this feature was implemented on Cisco ASR 903 Router.
The following command was introduced:
platform punt-police queue