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This document describes the Two-Rate Policer feature and how to configure it. Two-Rate Policer allows you to manage traffic rates through an interface; it is especially helpful in managing network bandwidth where large packets are in the same traffic stream.
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.
Note |
The set-clp-transmit action available with Two-Rate Policer, the Enhanced ATM Port Adapter (PA-A3) is required. The set-clp-transmit action is not supported on any platform that does not support the PA-A3 adapter (such as the Cisco 2600 series router, the Cisco 3620 router, and the 3640 router). For more information, see the documentation for your specific router. |
The following restrictions apply to the Two-Rate Policer feature:
Networks police traffic by limiting the input or output transmission rate of a class of traffic based on user-defined criteria. Policing traffic allows you to control the maximum rate of traffic sent or received on an interface and to partition a network into multiple priority levels or class of service (CoS).
The Two-Rate Policer performs the following functions:
With the Two-Rate Policer, you can enforce traffic policing according to two separate rates--committed information rate (CIR) and peak information rate (PIR). You can specify the use of these two rates, along with their corresponding values, by using two keywords, cir and pir, of the police command.
The Two-Rate Policer manages the maximum rate of traffic through a token bucket algorithm. The token bucket algorithm can use the user-configured values to determine the maximum rate of traffic allowed on an interface at a given moment in time. The token bucket algorithm is affected by all traffic entering or leaving the interface (depending on the location of the interface on which the Two-Rate Policer is configured) and is useful in managing network bandwidth in cases where several large packets are sent in the same traffic stream.
The token bucket algorithm provides users with three actions for each packet: a conform action, an exceed action, and an optional violate action. Traffic coming into the interface with the Two-Rate Policer configured is assigned one of these categories. Within these three categories, users can decide packet treatments. For instance, packets that conform can be configured to be sent, packets that exceed can be configured to be sent with a decreased priority, and packets that violate can be configured to be dropped.
The Two-Rate Policer is often configured on interfaces at the edge of a network to limit the rate of traffic entering or leaving the network. In the most common configurations, traffic that conforms is sent and traffic that exceeds is sent with a decreased priority or is dropped. Users can change these configuration options to suit their network needs.
Note |
Two-Rate Policer enables you to use Differentiated Services (DiffServ) Assured Forwarding (AF) Per-Hop Behavior (PHB) traffic conditioning. For more information about DiffServ, see the "Implementing DiffServ for End-to-End Quality of Service Overview" module. |
Note |
Starting with Cisco IOS Release 12.1(5)T, you can police traffic by using the Traffic Policing feature (sometimes referred to as the single-rate policer). The Two-Rate Policer (available with Cisco IOS Release 12.2(4)T) is in addition to the Traffic Policing feature, and it provides additional functionality. For more information about the Traffic Policing feature, see the "Traffic Policing" module. |
Two-Rate Policer provides improved bandwidth management through rate limiting. Before this feature was available, you could police traffic with the single-rate Traffic Policing feature. The Traffic Policing feature provided a certain amount of bandwidth management by allowing you to set the peak burst size (be). The Two-Rate Policer supports a higher level of bandwidth management and supports a sustained excess rate. With the Two-Rate Policer, you can enforce traffic policing according to two separate rates--CIR and PIR--specified in bits per second (bps).
In addition to rate-limiting, the Two-Rate Policer allows you to independently mark the packet according to whether the packet conforms, exceeds, or violates a specified rate. Packet marking also allows you to partition your network into multiple priority levels or CoSs.
If you want to mark traffic but do not want to use the Two-Rate Policer, see the "Marking Network Traffic" module.
The Two-Rate Policer 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 that have the DE bit set to 1 are discarded before frames that have the DE bit set to 0.
The Two-Rate Policer 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 that have the ATM CLP bit set to 1 are discarded before cells that have the ATM CLP bit set to 0.
Command |
Purpose |
---|---|
Router# show policy-map interface |
Displays statistics and configurations of all input and output policies attached to an interface. |
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. |
In this example, the Two-Rate Policer is configured on a class to limit traffic to an average committed rate of 500 kbps and a peak rate of 1 Mbps:
Router(config)# class-map police Router(config-cmap)# match access-group 10 1 Router(config-cmap)# policy-map policy1 Router(config-pmap)# class police Router(config-pmap-c)# police cir 500000 bc 10000 pir 1000000 be 10000 conform-action transmit exceed-action set-prec-transmit 2 violate-action drop Router(config)# interface serial3/0 Router(config-if)# service-policy output policy1 Router(config-if)# end Router# show policy-map policy1 Policy Map policy1 Class police police cir 500000 conform-burst 10000 pir 1000000 peak-burst 10000 conform-action transmit exceed-action set-prec-transmit 2 violate-action drop
Traffic marked as conforming to the average committed rate (500 kbps) will be sent as is. Traffic marked as exceeding 500 kbps, but not exceeding 1 Mbps, will be marked with IP Precedence 2 and then sent. All traffic exceeding 1 Mbps will be dropped. The burst parameters are set to 10,000 bytes.
Router# show policy-map interface serial3/0 Serial3/0 Service-policy output: policy1 Class-map: police (match all) 148803 packets, 36605538 bytes 30 second offered rate 1249000 bps, drop rate 249000 bps Match: access-group 101 police: cir 500000 bps, conform-burst 10000, pir 1000000, peak-burst 100000 conformed 59538 packets, 14646348 bytes; action: transmit exceeded 59538 packets, 14646348 bytes; action: set-prec-transmit 2 violated 29731 packets, 7313826 bytes; action: drop conformed 499000 bps, exceed 500000 bps violate 249000 bps Class-map: class-default (match-any) 19 packets, 1990 bytes 30 seconds offered rate 0 bps, drop rate 0 bps Match: any
The following sections provide references related to the Two-Rate Policer feature.
Related Topic |
Document Title |
---|---|
MQC |
|
QoS features such as class-based weighted fair queueing (CBWFQ), traffic marking, and traffic policing |
Standard |
Title |
---|---|
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
-- |
MIB |
MIBs Link |
---|---|
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFC |
Title |
---|---|
RFC 2698 |
A Two Rate Three Color Marker |
Description |
Link |
---|---|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
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 Two-Rate Policer |
Feature Name |
Releases |
Feature Information |
---|---|---|
Two-Rate Policer |
12.2(4)T 12.2(4)T3 12.0(26)S 12.2(28)SB 12.2(33)SRA 12.2(33)SXH Cisco IOS XE 3.1.0 SG |
This feature was introduced. Support for the Cisco 7500 series routers was added. This feature was integrated into Cisco IOS Release 12.0(26)S for the Cisco 7200 and 7500 series routers. This feature was integrated into Cisco IOS Release 12.2(28)SB. This feature was integrated into Cisco IOS Release 12.2(33)SRA. This feature was integrated into Cisco IOS Release 12.2(33)SXH. This feature was integrated into Cisco IOS XE 3.1.0 SG. |
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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.