Set ATM CLP Bit Using Policer

First Published: March 28, 2011
Last Updated: March 29, 2011

The Set ATM CLP Bit Using Policer feature allows you to police and then mark outbound PPP over ATM (PPPoA) traffic. You can set the ATM cell loss priority (CLP) bit using either of the following methods:

•A policed threshold

•Matching a class

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 for Set ATM CLP Bit Using Policer" section.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Prerequisites for Set ATM CLP Bit Using Policer

•Restrictions for Set ATM CLP Bit Using Policer

•Information About Set ATM CLP Bit Using Policer

•How to Set the ATM CLP Bit Using Policer

•Configuration Examples for Set ATM CLP Bit Using Policer

•Additional References

•Feature Information for Set ATM CLP Bit Using Policer

Prerequisites for Set ATM CLP Bit Using Policer

If you are setting the ATM CLP bit by a policed threshold, ensure that a policy map includes the set-clp-transmit action. The new policer action conditionally marks PPPoA traffic in the matched class for a higher drop probability in the ATM network when traffic exceeds a given rate.

If you are setting the ATM CLP bit strictly by matching a class, ensure that a policy map includes the set atm-clp action. The set directive marks all traffic in the matched class for higher drop probability in the ATM network.

You can attach policy maps with the set-clp-transmit or set atm-clp actions to a virtual template. This template is cloned when PPPoA sessions are created or by dynamic assignment.

Restrictions for Set ATM CLP Bit Using Policer

The Set ATM CLP Bit Using Policer feature is supported only for broadband PPPoA traffic.

Information About Set ATM CLP Bit Using Policer

To configure the Set ATM CLP Bit Using Policer feature feature, you should understand the following concept:

•ATM CLP Bit

ATM CLP Bit

The ATM CLP bit shows the drop priority of the ATM cell. During ATM network congestion, the router discards ATM cells with the CLP bit set to 1 before discarding cells with a CLP bit setting of 0.

Using the Set ATM CLP Bit Using Policer feature, you can configure the police command to enable the ATM CLP bit in cell headers. The ATM CLP bit can be explicitly marked by a set directive.

The Set ATM CLP Bit Using Policer feature supports the set-clp-transmit policing action in the following types of policies:

•Single-rate policing

•Dual-rate policing

•Hierarchical

How to Set the ATM CLP Bit Using Policer

This section shows you how to configure a policy map to police PPPoA broadband traffic and mark the ATM CLP bit.

•Configuring PPPoA Broadband Traffic Policing

•Marking the ATM CLP Bit

Configuring PPPoA Broadband Traffic Policing

Prerequisites

Before configuring the policy map, ensure that you have defined any class maps used to classify traffic.

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map policy-map-name

4. class {class-name | class-default]

5. police cir rate exceed-action set-clp-transmit

6. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

policy-map policy-map-name

Example:

Router(config)# policy-map parent-policy

Enters policy-map configuration mode and creates a policy map.

Step 4 

class {class-name | class-default]

Example:

Router(config-pmap)# class class-default

Enters policy-map class configuration mode.

Specifies the name of the class whose policy you want to create or change or specifies the default class (commonly known as the class-default class) before you configure its policy. Repeat this command as many times as necessary to specify the child or parent classes that you are creating or modifying:

•class name—Name of the class to be configured or whose policy is to be modified. The class name is used for both the class map and to configure a policy for the class in the policy map.

•class-default—Specifies the default class so that you can configure or modify its policy.

Step 5 

police [cir cir] [conform-action action] [exceed-action action]

Example:

Router(config-pmap-c)# police 1000000

Router(config-pmap-c-police)# conform-action

transmit

Router(config-pmap-c-police)# exceed-action

set-clp-transmit

Configures traffic policing and specifies multiple actions applied to packets marked as conforming to, exceeding, or violating a specific rate.

•Enters policy-map class police configuration mode. Use one line per action that you want to specify:

–cir—(Optional) Committed information rate. Indicates that the CIR will be used for policing traffic.

–conform-action—(Optional) Action to take on packets when the rate is less than the conform burst.

–exceed-action—(Optional) Action to take on packets whose rate is within the conform and conform plus exceed burst.

Step 6 

end

Example:

Router(config-pmap-c)# end

(Optional) Returns to privileged EXEC mode.

Examples

The following example shows you how to set the ATM CLP using a policer: 

policy-map egress_atm_clp_policer

 class prec0

  police cir 5000000

 class prec1

  police cir 3000000 conform-action transmit exceed-action set-clp-transmit 

 class class-default

  police cir 1000000 conform-action transmit exceed-action set-clp-transmit

Marking the ATM CLP Bit

Prerequisites

Before configuring the policy map, ensure that you have defined any class maps used to classify traffic.

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map policy-map-name

4. class {class-name | class-default]

5. set atm-clp

6. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

policy-map policy-map-name

Example:

Router(config)# policy-map parent-policy

Enters policy-map configuration mode and creates a policy map.

Step 4 

class {class-name | class-default]

Example:

Router(config-pmap)# class class-default

Enters policy-map class configuration mode.

Specifies the name of the class whose policy you want to create or change or specifies the default class (commonly known as the class-default class) before you configure its policy. Repeat this command as many times as necessary to specify the child or parent classes that you are creating or modifying:

•class name—Name of the class to be configured or whose policy is to be modified. The class name is used for both the class map and to configure a policy for the class in the policy map.

•class-default—Specifies the default class so that you can configure or modify its policy.

Step 5 

set atm-clp

Example:

Router(config-pmap-c)# set atm-clp

Configures marking of the ATM CLP bit for all traffic matching this class.

Step 6 

end

Example:

Router(config-pmap-c)# end

(Optional) Returns to privileged EXEC mode.

Examples

The following example shows you how to set the ATM CLP using explicit marking: 

policy-map egress_atm_clp_policer

 class prec0

  police cir 5000000

 class class-default

  set atm-clp

Configuration Examples for Set ATM CLP Bit Using Policer

This section shows how to mark ATM CLP by Policer Action.

•Example: Marking the ATM CLP by Policer Action Matching a Class

•Example: Marking the ATM CLP by Policer Action Policed Threshold

Example: Marking the ATM CLP by Policer Action Matching a Class

This example shows how to do the following:

•Define traffic classes.

•Configure a two-layer policy map.

•Apply the policy map to PPPoA sessions.

This policy conditionally marks the ATM CLP bit on the traffic in the matching low_interest class once traffic on the class exceeds a given rate. 


class-map voice

  match precedence 4

!

class-map web

  match precedence 3

!

class low_interest

  match precedence 1 0

!

policy-map child

 child class voice

  police cir 256000

  priority level 1

 class web

  bandwidth remaining ratio 10

 class low_interest

  police cir 1000000 conform-action transmit exceed-action set-clp-transmit

 class class-default

  bandwidth remaining ratio 1

!

policy-map parent

 class class-default

  shape average 15000000

  service-policy child

policy maps attached to virtual templates are cloned and used to create a virtual access interface for each PPPoA session: 

interface Virtual-Template1

 ip unnumbered Loopback1

 load-interval 30

 peer default ip address pool POOL1

 ppp authentication chap ppp

 ipcp address required

 service-policy output parent

Example: Marking the ATM CLP by Policer Action Policed Threshold

This example shows how to do the following:

•Define traffic classes.

•Configure a two-layer policy map.

•Apply the policy map to PPPoA sessions.

This policy marks all non-essential traffic with the ATM CLP bit so that it is eligible for dropping if the ATM network becomes congested. 

class-map video

  match precedence 5

!

class-map voice

  match precedence 4

!

class-map web

  match precedence 3

!

policy-map child

 child class voice

  police cir 256000

  priority level 1

 class video

  police cir 4000000

  priority level 2

 class web

  set atm-clp

  bandwidth remaining ratio 10

 class class-default

  bandwidth remaining ratio 1

  set atm-clp

!

interface Virtual-Template1

 ip unnumbered Loopback1

 load-interval 30

 peer default ip address pool POOL1

 ppp authentication chap ppp

 ipcp address required

 service-policy output parent

Additional References

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

Quality of Service commands

Cisco IOS Quality of Service Command Reference


Standards

Standard
Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

—


MIBs

MIB
MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFC
Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

—


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.

http://www.cisco.com/cisco/web/support/index.html


Feature Information for Set ATM CLP Bit Using Policer

Table 1 lists the release history for this feature.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 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.

Table 1 Feature Information for Set ATM CLP Bit Using Policer

Feature Name
Releases
Feature Information

Set ATM CLP Bit Using Policer

Cisco IOS XE Release 3.3S

The Set ATM CLP Bit Using Policer feature allows you to police and then mark outbound PPPoA traffic.

The following commands were introduced or modified:
set atm-clp and police.


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