- Policing and Shaping Overview
- IPv6 QoS: MQC Traffic Policing
- Configuring Traffic Policing
- IPv6 QoS: MQC Traffic Shaping
- Two-Rate Policer
- Policer Enhancement - Multiple Actions
- Percentage-Based Policing and Shaping
- Modular QoS CLI Three-Level Hierarchical Policer
- ATM Policing by Service Category for SVC and SoftPVC
- Modular QoS CLI Unconditional Packet Discard
- Control Plane Policing
- Control Plane Protection
- Control Plane Logging
- Management Plane Protection
- Class-Based Policing
- QoS Percentage-Based Policing
- Overhead Accounting
- Adaptive QoS over DMVPN
Contents
- Configuring Traffic Policing
- Finding Feature Information
- Feature Overview
- Benefits
- Restrictions
- Supported Platforms
- Supported Standards MIBs and RFCs
- Prerequisites
- Configuration Tasks
- Configuring Traffic Policing
- Troubleshooting Tips
- Monitoring and Maintaining Traffic Policing
- Configuration Examples
- Example Configuring a Service Policy that Includes Traffic Policing
Configuring Traffic Policing
This feature module describes the Traffic Policing feature. Traffic policing allows you to control the maximum rate of traffic transmitted or received on an interface.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn . An account on Cisco.com is not required.
- Finding Feature Information
- Feature Overview
- Supported Platforms
- Supported Standards MIBs and RFCs
- Prerequisites
- Configuration Tasks
- Monitoring and Maintaining Traffic Policing
- Configuration Examples
Finding Feature Information
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.
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.
Feature Overview
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.
The Traffic Policing feature is applied when you attach a traffic policy contain the Traffic Policing configuration to an interface. A traffic policy is configured using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).
The table below lists the feature history.
|
Cisco IOS Release |
Enhancement |
|---|---|
|
12.1(5)T |
This command was introduced for Cisco IOS Release 12.1 T. A new Traffic Policing algorithm was introduced. The violate-action option became available. This feature became available on Cisco 2600, 3600, 4500, 7200, and 7500 series routers. |
|
12.2(2)T |
The set-clp-transmit option for the action argument was added to the police command. The set-frde-transmit option for the action argument was added to the police command. However, the set-frde-transmit option is not supported for Any Transport over Multiprotocol Label Switching (MPLS) (AToM) traffic in this release. The set-mpls-exp-transmit option for the action argument was added to the police command. |
|
Cisco IOS |
For information about feature support in Cisco IOS software, use Cisco Feature Navigator. |
Benefits
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 classify traffic.
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.
Restrictions
On a Cisco 7500 series router, traffic policing can monitor Cisco Express Forwarding (CEF) switching paths only. In order to use the Traffic Policing feature, Cisco Express Forwarding must be configured on both the interface receiving the packet and the interface sending the packet.
On a Cisco 7500 series router, traffic policing cannot be applied to packets that originated from or are destined to a router.
Traffic policing can be configured on an interface or a subinterface.
Traffic policing is not supported on the following interfaces: - Fast EtherChannel
- Tunnel
 Note | Traffic policing is supported on tunnels that are using the Cisco generic routing encapsulation (GRE) tunneling protocol. |
Supported Platforms
Cisco 2500 series
Note | Cisco IOS Release 12.2(2)T or later does not run on Cisco 2500 series routers. |
Cisco 2600 series
Cisco 3640 routers
Cisco 4500 series
Cisco 7000 series with RSP7000
Cisco 7100 series
Cisco 7200 series
Cisco 7500 series
Note | To use the set-clp-transmit action available with this feature, the Enhanced ATM Port Adapter (PA-A3) is required. Therefore, the set-clp-transmitaction is not supported on any platform that does not support the PA-A3 adapter (such as the Cisco 2600 series router, the Cisco 3640 router, and the 4500 series router). For more information, see the documentation for your specific router. |
Supported Standards MIBs and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
Class-Based Quality of Service MIB
CISCO-CLASS-BASED-QOS-MIB
CISCO-CLASS-BASED-QOS-CAPABILITY-MIB
For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on CCO at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
RFC 2697, A Single Rate Three Color Marker
Prerequisites
On a Cisco 7500 series router, Cisco Express Forwarding (CEF) must be configured on the interface before traffic policing can be used.
Configuration Tasks
Configuring Traffic Policing
Troubleshooting Tips
Check the interface type. Verify that your interface is not mentioned in the nonsupported interface description in the Restrictions section of this module.
For input traffic policing on a Cisco 7500 series router, verify that CEF is configured on the interface where traffic policing is configured.
For output traffic policing on a Cisco 7500 series router, ensure that the incoming traffic is CEF-switched. Traffic policing cannot be used on the switching path unless CEF switching is enabled.
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
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 example, traffic policing is configured with the average rate at 8000 bits per second, the normal burst size at 1500 bytes, and the excess burst size at 4000 bytes. Packets coming into Fast Ethernet interface 0/0 are evaluated by the token bucket algorithm to analyze whether packets conform, exceed, or violate the parameters. Packets that conform are transmitted, packets that exceed are assigned a QoS group value of 4 and are transmitted, 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 1500 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 fastethernet 0/0 Router(config-if)# service-policy input police