- Policing and Shaping Overview
- Distribution of Remaining Bandwidth Using Ratio
- QoS Percentage-Based Shaping
- Ethernet Overhead Accounting
- MQC Traffic Shaping Overhead Accounting for ATM
- PPP Session Queueing on ATM VCs
- Traffic Policing
- Policer Enhancement - Multiple Actions
- Control Plane Policing
- Class-Based Policing
- QoS Percentage-Based Policing
- Two-Rate Policer
Traffic Policing
This feature module describes the Traffic Policing feature. The Traffic Policing feature performs the following functions:
- Limits the input or output transmission rate of a class of traffic based on user-defined criteria.
- Marks packets by setting the ATM Cell Loss Priority (CLP) bit, Frame Relay Discard Eligibility (DE) bit, IP precedence value, IP differentiated services code point (DSCP) value, MPLS experimental value, and Quality of Service (QoS) group.
Traffic policing allows you to control the maximum rate of traffic that is transmitted or received on an interface. The Traffic Policing feature is applied when a service-policy containing the feature is attached to an interface. A service-policy (traffic policy) is configured using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see 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 document.
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.
Restrictions for Traffic Policing
- Traffic policing can be configured on an interface or a subinterface.
- Traffic policing is not supported on the EtherChannel interfaces.
Benefits of Traffic Policing
Bandwidth Management Through Rate Limiting
Traffic policing allows you to control the maximum rate of traffic transmitted or received on an interface. Traffic policing is often configured on interfaces at the edge of a network to limit traffic into or out of the network. In most Traffic Policing configurations, traffic that falls within the rate parameters is transmitted, whereas traffic that exceeds the parameters is dropped or transmitted with a different priority.
Packet Marking
Packet marking allows you to partition your network into multiple priority levels or classes of service (CoS). A packet is marked and these markings can be used to identify and classify traffic for downstream devices. In some cases, such as ATM Cell Loss Priority (CLP) marking or Frame Relay Discard Eligibility (DE) marking, the marking is used to decide whether the packet can be dropped in congested environments.
- Use traffic policing to set the IP precedence or DSCP values for packets entering the network. Networking devices within your network can then use the adjusted IP precedence values to determine how the traffic should be treated. For example, the Weighted Random Early Detection (WRED) feature uses the IP precedence values to determine the probability that a packet will be dropped.
- Use traffic policing to assign packets to a QoS group. The router uses the QoS group to determine how to prioritize packets within the router.
Traffic can be marked without using the Traffic Policing feature. If you want to mark traffic but do not want to use Traffic Policing, see the "Marking Network Traffic" module.
Packet Prioritization for Frame Relay Frames
The Traffic Policing feature allows users to mark the Frame Relay DE bit of the Frame Relay frame. The Frame Relay DE bit is one bit and, therefore, can be set to either 0 or 1. In congested environments, frames with the DE bit set to 1 are discarded before frames with the DE bit set to 0.
Packet Prioritization for ATM Cells
The Traffic Policing feature allows users to mark the ATM CLP bit in ATM cells. The ATM CLP bit is used to prioritize packets in ATM networks. The ATM CLP bit is one bit and, therefore, can be set to either 0 or 1. In congested environments, cells with the ATM CLP bit set to 1 are discarded before cells with the ATM CLP bit set to 0.
How to Configure Traffic Policing
Configuring Traffic Policing
| Command |
Purpose |
|---|---|
| Router(config-pmap-c)# police bps burst-normal burst-max conform-action action exceed-action action violate-action action |
Specifies a maximum bandwidth usage by a traffic class. |
Monitoring and Maintaining Traffic Policing
| Command |
Purpose |
|---|---|
| Router# show policy-map |
Displays all configured policy maps. |
| Router# show policy-map policy-map-name |
Displays the user-specified policy map. |
| Router# show policy-map interface |
Displays statistics and configurations of all input and output policies that are attached to an interface. |
Configuration Examples for Traffic Policing
Example Configuring a Service Policy That Includes Traffic Policing
The following configuration shows how to define a traffic class (with the class-mapcommand) and associate that traffic class with a traffic policy (with the policy-map command). Traffic policing is applied in the traffic policy. The service-policy command is then used to attach the traffic policy to the interface.
In this particular example, traffic policing is configured with the Committed Information Rate (CIR) at 8000 bits per second, the normal burst size at 2000 bytes, and the excess burst size at 4000 bytes. Packets coming into FastEthernet interface 1/1/1 are evaluated by the token bucket algorithm to analyze whether packets conform exceed, or violate the specified parameters. Packets that conform are transmitted, packets that exceed are assigned a QoS group value of 4 and are transmitted, and packets that violate are dropped.
Router(config)# class-map acgroup2 Router(config-cmap)# match access-group 2 Router(config-cmap)# exit Router(config)# policy-map police Router(config-pmap)# class acgroup2 Router(config-pmap-c)# police 8000 2000 4000 conform-action transmit exceed-action set-qos-transmit 4 violate-action drop Router(config-pmap-c)# exit Router(config-pmap)# exit Router(config)# interface fastethernet1/1/1 Router(config-if)# service-policy input police Router(config-if)# end
Additional References
Related Documents
| Related Topic |
Document Title |
|---|---|
| QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples |
Cisco IOS Quality of Service Solutions Command Reference |
| Conceptual information about policing and shaping |
"Policing and Shaping Overview" module |
| MQC |
"Applying QoS Features Using the MQC" module |
| Marking network traffic |
"Marking Network Traffic" module |
Standards
| Standard |
Title |
|---|---|
| None |
-- |
MIBs
| MIB |
MIBs Link |
|---|---|
| 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: |
RFCs
| RFC |
Title |
|---|---|
| RFC 2697 |
A Single Rate Three Color Marker |
Technical Assistance
| Description |
Link |
|---|---|
| The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for Traffic Policing
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 Traffic Policing |
| Feature Name |
Releases |
Feature Information |
|---|---|---|
| Traffic Policing |
Cisco IOS XE Release 2.1 |
This feature was introduced on Cisco ASR 1000 Series Routers. The following commands were modified: police, show policy-map, show policy-map interface. |
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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