QoS: Child Service Policy for Priority Class

Table Of Contents

QoS: Child Service Policy for Priority Class

Contents

Prerequisites for QoS Child Service Policy for Priority Class

Restrictions for QoS Child Service Policy for Priority Class

Information About QoS Child Service Policy for Priority Class

Priority Class of a Parent Policy

Hierarchical Policies

How to Configure a Child Policy Under a Parent Priority Class

Configuring a Child Policy Under a Priority Class

Attaching a Hierarchical Service Policy to a Subinterface

Configuration Examples for Configuring a Child Policy Under a Priority Class

Configuring a Police-Based Child Policy Under a Priority Class: Example

Attaching a Bandwidth-Based Child Policy to a Priority Class—Invalid Configuration: Example

Attaching Bandwidth to a Child Policy Attached to a Priority Class—Invalid Configuration: Example

Attaching Priority to a Parent Policy with a Queuing-Based Child Policy—Invalid Configuration: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

QoS: Child Service Policy for Priority Class

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First Published: November, 2006

The QoS: Child Service Policy for Priority Class feature allows you to configure a child service policy with nonqueuing-based features and attach the child policy to a priority class.

History of QoS Child Service Policy for Priority Class

Release	Modification
12.2(31)SB2	This feature was introduced and implemented on the Cisco 10000 series router for the PRE3.

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Contents

•Prerequisites for QoS Child Service Policy for Priority Class

•Restrictions for QoS Child Service Policy for Priority Class

•Information About QoS Child Service Policy for Priority Class

•How to Configure a Child Policy Under a Parent Priority Class

•Configuration Examples for Configuring a Child Policy Under a Priority Class

•Additional References

•Command Reference

Prerequisites for QoS Child Service Policy for Priority Class

Traffic classes must be configured using the class-map command.

Restrictions for QoS Child Service Policy for Priority Class

The child policy that you attach to a priority class must be based on nonqueuing features. For example, if you attempt to do any of the following, an error message displays:

•Attach queuing-based child policy—You cannot attach a child service policy that is based on queuing features to a priority class. For example, you cannot attach a bandwidth-based child policy to a class with priority configured.

•Add queuing features to child policy—You cannot add queuing features (such as bandwidth) to a child policy that is already attached to a parent class with priority configured.

•Add priority to parent class—If a queuing-based child policy is already attached to a non-priority class of a parent policy, you cannot then configure the priority command for the parent class.

Information About QoS Child Service Policy for Priority Class

The QoS Child Service Policy for Priority Class feature allows you to configure a child service policy with nonqueuing-based features and attach the child policy to a priority class. In a three-level hierarchical policy, the priority class to which you attach the child policy must be in the middle-level policy. In a two-level hierarchical policy (nested policy), the priority class to which you attach the child policy is in the parent policy.

Prior to Cisco IOS Release 12.2(31)SB2, you could not attach a child service policy to a priority class even if the child policy contained nonqueuing-based commands. If you attempted to do so, an error message similar to the following displayed:

Please remove priority before attaching a child policy.

Priority Class of a Parent Policy

A parent policy contains traffic classes with various queuing and nonqueuing features enabled on the classes. You can give priority to a traffic class by configuring the priority command under the class. The router processes the packets belonging to the priority class before processing nonpriority classes.

Hierarchical Policies

A hierarchical policy is a quality of service (QoS) model that enables you to specify QoS behavior at multiple levels of hierarchy. Depending on the type of hierarchical policy you configure, you can use hierarchical policies to:

•Specify multiple policy maps to shape multiple queues together

•Apply specific policy map actions on the aggregate traffic

•Apply class-specific policy map actions

•Restrict the maximum bandwidth of a virtual circuit (VC) while allowing policing and marking of traffic classes within the VC

All hierarchical policy types consist of a top-level parent policy and one or more child policies. The service-policy command is used to apply a policy to another policy, and a policy to an interface, subinterface, virtual circuit (VC), or virtual LAN (VLAN).

How to Configure a Child Policy Under a Parent Priority Class

To configure a child policy under a parent priority class, perform the following configuration tasks:

•Configuring a Child Policy Under a Priority Class

•Attaching a Hierarchical Service Policy to a Subinterface

Configuring a Child Policy Under a Priority Class

Use the following procedure to configure a child policy under a priority class.

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map policy-map-name

4. class class-map-name

5. police [cir] bps [bc] burst-normal [be] burst-excess [conform-action action] [exceed-action action] [violate-action action]

6. exit

7. policy-map policy-map-name

8. class class-map-name

9. priority

10. service-policy policy-map-name

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 Business	Creates or modifies the child policy. Enters policy-map configuration mode. •policy-map-name is the name of the child policy map. The name can be a maximum of 40 alphanumeric characters.
Step 4	class class-map-name Example: Router(config-pmap)# class video	Assigns the traffic class you specify to the policy map. Enters policy-map class configuration mode. •class-map-name is the name of a previously configured class map.
Step 5	police [cir] bps [Bc] burst-normal [Be] burst-excess [conform-action action] [exceed-action action] [violate-action action] Example: Router(config-pmap-c)# police 4000000 2000 5000 conform-action transmit exceed-action set-dscp-transmit 5	Configures traffic policing. •cir is the committed information rate. •bps specifies the average rate in bits per second (bps). •Bc is the normal or committed burst (bc) size used by the first token bucket for policing. •burst-normal specifies the committed burst size in bytes. •Be is the excess burst (be) size used by the second token bucket for policing. •burst-excess specifies the excess burst in bytes. •conform-action action specifies the action to take on packets that conform to the rate limit. •exceed-action action specifies the action to take on packets that exceed the rate limit, but not the peak information rate (PIR). •violate-action action specifies the action to take on packets that continuously exceed the PIR limit.
Step 6	exit Example: Router(config-pmap-c)# exit	Exits policy-map class configuration mode.
Step 7	policy-map policy-map-name Example: Router(config-pmap)# policy-map Premium	Creates or modifies the top-level parent policy (nested policy), or the middle-level policy (three-level hierarchical policy). •policy-map-name is the name of the parent or middle-level policy map. The name can be a maximum of 40 alphanumeric characters.
Step 8	class class-map-name Example: Router(config-pmap)# class Gold	Assigns the traffic class you specify to the policy map. Enters policy-map class configuration mode. •class-map-name is the name of a previously configured class map.
Step 9	priority Example: Router(config-pmap-c)# priority	Assigns priority to the traffic class.
Step 10	service-policy policy-map-name Example: Router(config-pmap-c)# service-policy Business	Applies a child policy to the parent or middle-level priority class. •policy-map-name is the name of a previously configured child policy map. Note For three-level hierarchical policies, after applying the child policy to the middle-level priority class, you must then apply the middle-level policy to the parent policy. For more information, see "Defining QoS for Multiple Policy Levels" in theCisco 10000 Series Router Quality of Service Configuration Guide.

Attaching a Hierarchical Service Policy to a Subinterface

Use the following procedure to attach a hierarchical service policy to a subinterface.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface type slot/module/port.subinterface [point-to-point]

4. service-policy {input | output} policy-map-name

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	interface type slot/module/port.subinterface [point-to-point] Example: Router(config)# interface atm 1/0/2.1	Configures or modifies a subinterface. Enters subinterface configuration mode. •type is the interface type (for example, ATM). •slot/module/port is the slot, module, and port number of the interface card (for example, 1/0/0). •.subinterface is the number of the subinterface (for example, .1)
Step 4	service-policy {input | output} policy-map-name Example: Router(config-subif)# service-policy input Premium	Applies an hierarchical policy to the subinterface. •policy-map-name is the name of parent policy map. •input indicates to apply the service policy to inbound packets. •output indicates to apply the service policy to outbound packets.

Configuration Examples for Configuring a Child Policy Under a Priority Class

This section provides the following configuration examples:

•Configuring a Police-Based Child Policy Under a Priority Class: Example

•Attaching a Bandwidth-Based Child Policy to a Priority Class—Invalid Configuration: Example

•Attaching Bandwidth to a Child Policy Attached to a Priority Class—Invalid Configuration: Example

•Attaching Priority to a Parent Policy with a Queuing-Based Child Policy—Invalid Configuration: Example

Configuring a Police-Based Child Policy Under a Priority Class: Example

The following example configuration shows how to configure a child policy with policing enabled and attach it to a priority class of a parent policy.

policy-map Child

class class1

police 10000

!

policy-map Parent

class P2

priority

service-policy Child

Attaching a Bandwidth-Based Child Policy to a Priority Class—Invalid Configuration: Example

As shown in the following example configuration, the router does not allow you to attach a bandwidth-based child policy to a priority class of a parent policy. This is an invalid configuration.

policy-map Child

class class1

bandwidth 100

!

policy-map Parent

class P2

priority

service-policy Child

Please remove priority before attaching a child policy.

!

!

show policy-map

policy-map Child

class class1

bandwidth 100

!

policy-map Parent

class P2

priority

Attaching Bandwidth to a Child Policy Attached to a Priority Class—Invalid Configuration: Example

As shown in the following example configuration, the router does not allow you to add the bandwidth command to a child policy that is already attached to a priority class of a parent policy. This is an invalid configuration.

policy-map Child

class class1

police cir 10000 bc 1500 conform-action transmit exceed-action drop

!

policy-map Parent

class P2

priority

service-policy Child

!

!

policy-map Child

class class1

bandwidth 10

Cannot configure `bandwidth' in child policy with `priority' in parent

!

!

show policy-map

policy-map Child

class class1

police cir 10000 bc 1500 conform-action transmit exceed-action drop

!

policy-map Parent

class P2

priority

service-policy Child

Attaching Priority to a Parent Policy with a Queuing-Based Child Policy—Invalid Configuration: Example

As shown in the following example configuration, the router does not allow you to assign priority to a class of a parent policy when a queuing-based child policy is already attached to the parent class. This is an invalid configuration.

policy-map Child

class class1

bandwidth 10

!

policy-map Parent

class P2

police cir 10000 bc 1500 conform-action transmit exceed-action drop

service-policy Child

!

!

policy-map Parent

class P2

priority 

Cannot configure `priority' in parent policy with queuing-related child policy.

!

!

show policy-map

policy-map Child

class class1

bandwidth 10

!

policy-map Parent

class P2

police cir 10000 bc 1500 conform-action transmit exceed-action drop

service-policy Child

Additional References

The following sections provide references related to the QoS Child Service Policy for Priority Class feature.

Related Documents

Related Topic	Document Title
Hierarchical policies	Cisco 10000 Series Router Quality of Service Configuration Guide, "Defining QoS for Multiple Policy Levels"
Policing and shaping	Cisco IOS Quality of Service Solutions Configuration Guide, Policing and Shaping Overview Cisco 10000 Series Router Quality of Service Configuration Guide Policing Traffic Shaping Traffic
Policy maps	Cisco 10000 Series Router Quality of Service Configuration Guide, Configuring QoS Policy Actions and Rules

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 IOS 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 Technical Support & Documentation website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/techsupport

Command Reference

This feature uses no new or modified commands.

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