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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
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.
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•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
•Feature Information 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.
The Set ATM CLP Bit Using Policer feature is supported only for broadband PPPoA traffic.
To configure the Set ATM CLP Bit Using Policer feature feature, you should understand the following concept:
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
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
Before configuring the policy map, ensure that you have defined any class maps used to classify traffic.
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
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
Before configuring the policy map, ensure that you have defined any class maps used to classify traffic.
1. enable
2. configure terminal
3. policy-map policy-map-name
4. class {class-name | class-default]
5. set atm-clp
6. end
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
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
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
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
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
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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.