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Cisco IOS Software Releases 12.0 S

Class-Based Marking

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Class-Based Marking

Table Of Contents

Class-Based Marking

Contents

Feature Overview

IP Precedence and IP DSCP Marking

QoS Group Value Marking

CoS Value Marking

ATM Cell Loss Priority Bit Setting

Frame Relay Discard Eligibility Bit Setting

Benefits

Restrictions

Prerequisites

Configuration Tasks

Configuring an IP Precedence Value

Configuring an IP DSCP Value

Configuring a QoS Group Value

Configuring a CoS Value

Changing an ATM CLP Bit Setting

Changing a Frame Relay DE Bit Setting

Verifying the Class-Based Packet Marking Feature

Configuration Examples

Configuring an IP Precedence Value Example

Configuring an IP DSCP Value Example

Configuring a QoS Group Value Example

Configuring a Classifying CoS Values Example

Changing the ATM CLP Value Example

Changing the Frame Relay DE Bit Value Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

set atm-clp

set cos

set fr-de

set ip dscp

set ip precedence

set qos-group


Class-Based Marking


Feature History for Class-Based Marking

Release
Modification

12.0(5)XE

This feature was introduced as QoS Packet Marking. The original version of this feature supported matching based on IP Precedence, IP DSCP, and QoS Groups.

12.1(2)T

This feature was introduced for Cisco IOS Release 12.1(2)T and support for ATM virtual circuits (VCs) was added. In addition, support was added for the Cisco 2600 series, Cisco 3640 series, and Cisco 4500 series routers.
Support for the Cisco 7200 series router was also introduced for Cisco IOS Release 12.1 T.

12.1(5)T

The set cos command was introduced.
The
set atm-clp command was introduced in Cisco IOS Release 12.1 T.

12.2(2)T

The set fr-de command was introduced.

12.0(26)S

This feature was integrated into Cisco IOS Release 12.0(26)S for the Cisco 7200 and 7500 series routers.


Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.


Note This document only details Class-Based Marking. The document does not detail matching on packets based on these markings. If you need information regarding packet matching, see the Modular Quality of Service Command-Line Interface document, which previews all aspects of the Modular QoS CLI, including packet matching.


Contents

Feature Overview

Prerequisites

Configuration Tasks

Configuration Examples

Additional References

Command Reference

Feature Overview

The Class-Based Packet Marking feature provides users with a user-friendly command-line interface (CLI) for efficient packet marking by which users can differentiate packets based on the designated markings. The Class-Based Packet Marking feature allows users to perform the following tasks:

Mark packets by setting the IP precedence bits or the IP differentiated services code point (DSCP) in the IP type of service (ToS) byte.

Mark packets by setting the Layer 2 Class of Service (CoS) value.

Associate a local quality of service (QoS) group value with a packet.

Set the Cell Loss Priority (CLP) bit setting in the ATM header of a packet from 0 to 1.

Set the Frame Relay Discard Eligibility (DE) bit in the address field of the frame relay frame from 0 to 1.


Note This feature module does not document any information related to MPLS experimental value marking. For information on MPLS experimental value marking, see the MPLS Quality of Service Enhancements feature module in the Cisco IOS Release 12.0(22)S new feature documentation index.


In most cases, the purpose of a packet mark is identification. After a packet is marked, downstream devices identify traffic based on the marking and categorize the traffic according to network needs. This categorization occurs when the match commands in the traffic class are configured to identify the packets by the mark (for example, match ip precedence, match ip dscp, match cos, etc.). The traffic policy using this traffic class can then set the appropriate QoS features for the marked traffic. (For information on packet matching, see the note at the beginning of this feature module).

In some cases, the markings can be used for purposes besides identification. WRED and DWRED, for instance, can use the IP precedence or IP DSCP values to detect and drop packets. In ATM networks, the CLP bit of the packet is used to determine the priority of packet in a congested environment. If congestion occurs in the ATM network, packets with the CLP bit set to 1 are dropped before packets with the CLP bit set to 0. Similarly, the DE bit of a frame relay frame is used to determine the priority of a frame in a congested frame relay network. In frame relay networks, frames with the DE bit set to 1 are dropped before frames with the DE bit set to 0.

Packet marking is supported on interfaces, subinterfaces, and ATM virtual circuits (VCs). In an ATM PVC, a user can configure packet marking in the same traffic policy where he or she configures the queueing actions, on a per-VC basis.

IP Precedence and IP DSCP Marking

Marking a packet with an IP precedence or IP DSCP marking allows users to classify traffic based on an IP precedence or IP DSCP value, depending on which value is marked. These marking can be used to identify traffic within the network, and other interfaces can match traffic based on the IP Precedence or DSCP markings.

IP Precedence and DSCP markings are also used to decide how packets should be treated in Weighted Random Early Detection (WRED).

The IP DSCP value is the first 6 bits in the ToS byte, while the IP Precedence value is the first 3 bits in the ToS value. Therefore, the IP Precedence value is actually part of the IP DSCP value. For this reason, both values cannot be set simultaneously. If both values are set at the same time, the packet will be marked with the IP DSCP value.

If you need to mark packets in your network and all of the devices support IP DSCP marking and matching, use the IP DSCP marking to mark your packets, since the IP DSCP markings provide more packet marking options (64 individual values can be marked using IP DSCP marking, while only 8 individual values can be marked using IP precedence marking). If marking by IP DSCP is somehow undesirable, however, or if you are unsure if the devices in your network support IP DSCP values, use the IP precedence value to mark your packets. The IP precedence value is likely supported by all devices in the network.

A user can set up to 8 different IP precedence markings and 64 different IP DSCP markings.

QoS Group Value Marking

Marking a packet with a local QoS group value allows users to identify a group ID with a packet. The group ID can be used to classify packets into QoS groups based on prefix, autonomous system, and community string. This QoS group marking can only be used to classify traffic within a single router and cannot, therefore, be used to mark packets leaving the router. For this reason, QoS group values cannot be applied on output traffic policies (which are attached to interfaces using the service-policy output command).

The QoS group value is usually used for one of the two following reasons:

To leverage a large range of traffic classes. The QoS group value has 100 different individual packet markings, as opposed to IP DSCP and IP Precedence, which have 64 and 8 values, respectively.

If changing the IP Precedence or IP DSCP value of the packet is undesirable.

A user can set up to 100 different QoS group markings.

CoS Value Marking

Marking a packet with a local CoS value allows users to associate a Layer 2 Class of Service value with a packet. The value can then be used to classify packets based on user-defined requirements. Layer 2 to Layer 3 mapping can also be configured by matching on the CoS value, since switches already have the capability to match and set CoS values. If a packet that needs to be marked to differentiate user-defined QoS services is leaving a router and entering a switch, the router should set the CoS value of the packet, since the switch can process the layer 2 CoS header marking.

The CoS value cannot be marked as part of an input traffic policy (which is attached to an interface using the service-policy input command). A CoS value marking can only be applied to output traffic policies (which are attached using the service-policy output command).

A user can set up to 8 different CoS markings.

ATM Cell Loss Priority Bit Setting

The ATM Cell Loss Priority (CLP) bit setting is used as a method for prioritizing the discarding of cells in congested ATM networks. A CLP bit has only one bit and can therefore only have two settings, 0 or 1. If congestion occurs in an ATM network, cells with a CLP bit setting of 1 are discarded before cells with a CLP bit setting of 0. Therefore, important ATM cells should be forwarded with the CLP bit set to 0, while less important ATM cells should be forwarded with the CLP bit set to 1.

ATM CLP bit setting is especially useful when a packet that left a Cisco router has been converted into an ATM cell. By default, the new cell has a CLP bit setting of 0. This setting can be changed using ATM CLP bit setting.


Note To use the set atm-clp command available with the Class-Based Marking feature, you must have one of the following adapters: the Enhanced ATM Port Adapter (PA-A3), the ATM Inverse Multiplexer over ATM Port Adapter with 8 T1 Ports (PA-A3-8T1IMA), or the ATM Inverse Multiplexer over ATM Port Adapter with 8 E1 Ports (PA-A3-8E1IMA).

Therefore, the set atm-clp command is not supported on any platform that does not support these adapters. For more information, refer to the documentation for your specific router.


Frame Relay Discard Eligibility Bit Setting

The discard eligibility (DE) bit in the address field of a frame relay frame is used as a method for prioritizing the discarding of frames in congested frame relay networks. The frame relay DE bit has only one bit and can therefore only have two settings, 0 or 1. If congestion occurs in a frame relay network, frames with the DE bit set at 1 are discarded before frames with the DE bit set at 0. Therefore, important traffic should have the DE bit set at 0 while less important traffic should be forwarded with the DE bit set at 1.

The default DE bit setting is 0. The Class-Based Packet Marking feature allows users to change the DE bit setting to 1 for various traffic, giving users the option of keeping the default value of 0 or changing the value to 1. For this reason, users can use the frame relay DE bit marking to prioritize frames in a frame relay network.

Benefits

Network Partitioning and Categorizing

Packet marking allows you to partition your network into multiple priority levels or classes of service, as follows:

Class-Based Packet Marking is often used to set the IP precedence or IP DSCP values for packets entering a network. Networking devices within your network can then use the newly-marked IP precedence values to determine how traffic should be treated. For example, voice packets can be marked with a particular marking (IP precedence or DSCP) and Low Latency Queueing (LLQ) can then be configured to put all packets of that mark into a priority queue. In this case, the marking was used to identify a packet for LLQ.
A marking can be used to identify a packet for any class-based QoS feature (any feature available in policy map class configuration mode, although some restrictions exist).

Use Class-Based Marking to assign packets to a QoS group within a router. The router can use the QoS groups to determine how to prioritize packets for transmission.
The QoS group value is usually used for one of the two following reasons:

To leverage a large range of traffic classes. The QoS group value has 100 different individual packet markings, as opposed to IP DSCP and IP Precedence, which have 64 and 8, respectively.

If changing the IP Precedence or IP DSCP value of the packet is undesirable.

Layer 2 to Layer 3 Mapping

If a packet that needs to be marked to differentiate user-defined QoS services is leaving a router and entering a switch, the router can set the CoS value of the packet, since the switch can process the layer 2 CoS header marking, and vice versa.

Weighted Random Early Detection Configuration

Weighted random early detection (WRED) uses IP precedence values or IP DSCP values to determine the probability that a packet will be dropped. Therefore, the IP precedence and IP DSCP markings can be used in conjunction with the WRED feature.

Improved Bandwidth Management in ATM Networks

The ability to set the ATM CLP bit allows users to extend their IP QoS policies into an ATM network. As congestion occurs in the ATM network, cells with the CLP bit set are more likely to be dropped, resulting in improved network performance for higher priority traffic and applications.

Improved Bandwidth Management in Frame Relay Networks

The ability to set the Frame Relay DE bit allows users to manage bandwidth in a frame relay network. As congestion occurs in a Frame Relay network, frames with the Frame Relay DE bit set are more likely to be dropped, resulting in improved network performance for higher priority traffic and applications.

Restrictions

The Class-Based Packet Marking feature can only mark packets traveling on Cisco Express Forwarding (CEF) switching paths. In order to use the Class-Based Packet Marking feature, CEF must be configured on both the interface receiving the packet and the interface sending the packet.

For information on CEF switching, consult the Cisco Express Forwarding section of the Cisco IOS Switching Services Configuration Guide.

Class-Based Marking can be configured on an interface, a subinterface, or an ATM permanent virtual circuit (PVC). This feature is not supported on the following interfaces:

Fast EtherChannel

Tunnel

PRI

ATM switched virtual circuit (SVC)

Frame Relay data-link connection identifier (DLCI)

Any interface that does not support CEF

Before modifying the encapsulation type from IEEE 802.1 Q to ISL, or vice versa, on a subinterface, detach the policy map from the subinterface. After changing the encapsulation type, reattach the policy map.

A traffic policy contain the set qos-group command can only be attached as an input traffic policy. QoS group values are not usable for packets leaving a router.

A traffic policy containing the set cos command can only be attached as an output traffic policy.

A traffic policy containing the set atm-clp command can be attached as an output traffic policy only. The set atm-clp command does not support packets that originate from the router.

Prerequisites

CEF must be configured on the interface before class-based QoS packet marking can be used.

For information on CEF switching, consult the Cisco Express Forwarding section of the Cisco IOS Switching Services Configuration Guide.

Configuration Tasks

See the following sections for configuration tasks for the Class-Based Packet Marking feature. Each task in the list is identified as optional or required.

Configuring an IP Precedence Value (Optional)

Configuring an IP DSCP Value (Optional)

Configuring a QoS Group Value (Optional)

Configuring a CoS Value (Optional)

Changing an ATM CLP Bit Setting (Optional)

Changing a Frame Relay DE Bit Setting (Optional)

Verifying the Class-Based Packet Marking Feature (Optional)

To configure the Class-Based Packet Marking feature, you must either configure an IP precedence value or an IP DSCP value.

Configuring an IP Precedence Value

To mark a packet by setting the IP precedence bits in the ToS byte, use the following commands beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# policy-map policy-name

Specifies the name of the service policy to configure.

Step 2 

Router(config-pmap)# class class-name

Specifies the name of a predefined class, which was defined with the class-map command, included in the service policy.

Step 3 

Router(config-pmap-c)# set ip precedence 
ip-precedence-value

Specifies the IP precedence of packets within a traffic class. The ip-precedence-value is in the range 0 to 7.

The service policy configured in this section is not yet attached to an interface. This command is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see theModular Quality of Service Command-Line Interface document

Configuring an IP DSCP Value

To mark a packet by setting the IP DSCP value, use the following commands beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# policy-map policy-name

Specifies the name of the service policy to configure.

Step 2 

Router(config-pmap)# class class-name

Specifies the name of a predefined class, which was defined with the class-map command, included in the service policy.

Step 3 

Router(config-pmap-c)# set ip dscp ip-dscp-value

Specifies the IP DSCP value of packets within a traffic class. The number is in the range 0 to 63.

Reserved keywords such as EF (expedited forwarding) and AF11 (assured forwarding class AF11) can be specified instead of numeric values.

The service policy configured in this section is not yet attached to an interface. This command is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Configuring a QoS Group Value

To associate a local QoS group value with a packet, use the following commands beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# policy-map policy-name

Specifies the name of the service policy to configure.

Step 2 

Router(config-pmap)# class class-name

Specifies the name of a predefined class, which was defined with the class-map command, included in the service policy.

Step 3 

Router(config-pmap-c)# set qos-group qos-group-value

Specifies a QoS group value to associate with the packet. The number is in the range 0 to 99.

The service policy configured in this section is not yet attached to an interface. This command is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Configuring a CoS Value

To mark a packet with a specific CoS value, use the following commands beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# policy-map policy-name

Specifies the name of the service policy to configure.

Step 2 

Router(config-pmap)# class class-name

Specifies the name of a predefined class, which was defined with the class-map command, included in the service policy.

Step 3 

Router(config-pmap-c)# set cos cos-value

Specifies a CoS value or values to associate with the packet. The number is in the range 0 to 7.

The service policy configured in this section is not yet attached to an interface. This command is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.


Note A service policy that contains the set cos command can only be attached as an output service policy. The set cos command cannot be applied to packets entering an interface.


Changing an ATM CLP Bit Setting

To set the CLP bit to 1 on all packets matching a specified class, use the following commands.

 
Command
Purpose

Step 1 

Router(config)# policy-map policy-name

Specifies the name of the policy-map to configure.

Step 2 

Router(config-pmap)# class class-name

Specifies the name of a predefined class included in the service policy.

Step 3 

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

Sets the ATM CLP bit setting for all packets matching the specified class from 0 to 1.

This command is applied when you create a service policy in policy map configuration mode. This service policy is not yet attached to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Changing a Frame Relay DE Bit Setting

To change the Frame Relay DE bit from the default value of 0 to 1 on classified traffic using the Modular QoS CLI, enter the following commands:

 
Command
Purpose

Step 1 

Router(config)# policy-map policy-name

Specifies the name of the policy-map to configure.

Step 2 

Router(config-pmap)# class class-name

Specifies the name of a predefined class included in the service policy.

Step 3 

Router(config-pmap-c)# set fr-de

Sets the Frame Relay DE bit setting for all packets matching the specified traffic class from 0 to 1.

This command is applied when you create a service policy in policy map configuration mode. This service policy is not yet attached to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Verifying the Class-Based Packet Marking Feature

To verify the Class-Based Packet Marking feature and display the configuration of a policy map and retrieve information regarding QoS packet marking features that are configured in policy map configuration mode, use the show policy-map [interface [interface-spec [input | output [class class-name]]]] command in EXEC mode. See the Modular Quality of Service Command-Line Interface document for more information abou the show policy-map command.

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.

Router# show policy-map interface interface-spec

Displays configuration and statistics of the input and output policies attached to a particular interface.

Router# show policy-map interface interface-spec [input]

Displays configuration and statistics of the input policy attached to an interface.

Router# show policy-map interface interface-spec [output]

Displays configuration and statistics of the output policy attached to an interface.

Router# show policy-map interface-spec [input | output] [class class-name]

Displays the configuration and statistics for the class name configured in the policy.


Configuration Examples

This section provides the following configuration examples:

Configuring an IP Precedence Value Example

Configuring an IP DSCP Value Example

Configuring a QoS Group Value Example

Configuring a Classifying CoS Values Example

Changing the ATM CLP Value Example

Configuring an IP Precedence Value Example

In the following example, a service policy called policy1 is created. This service policy is associated to a previously defined classification policy through the use of the class command. This example assumes that a classification policy called class1 was previously configured.

In this example, the IP precedence bit in the ToS byte is set to 1.

Router(config)# policy-map policy1 
Router(config-pmap)# class class1 
Router(config-pmap-c)# set ip precedence 1

The service policy configured in this section is not yet attached to an interface. This command is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Configuring an IP DSCP Value Example

In the following example, a service policy called policy1 is created. This service policy is associated to a previously defined classification policy through the use of the class command. This example assumes that a classification policy called class1 was previously configured.

In the following example, the IP DSCP value in the ToS byte is set to 5.

Router(config)# policy-map policy1 
Router(config-pmap)# class class1 
Router(config-pmap-c)# set ip dscp 5

Router(config-pmap-c)# class class2 
Router(config-pmap-c)# set ip dscp ef

After you configure the settings shown for voice packets at the edge, all intermediate routers are configured to provide low latency treatment to the voice packets, as follows:

Router(config)# class-map voice
Router(config-cmap)# match ip dscp ef
Router(config)# policy qos-policy
Router(config-pmap)# class voice
Router(config-pmap-c)# priority 24

The service policy configured in this section is not yet attached to an interface. This action is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Configuring a QoS Group Value Example

In the following example, a service policy called policy1 is created. This service policy is associated to a previously defined classification policy through the use of the class command. This example assumes that a classification policy called class1 was previously configured.

In the following example, the QoS group value is set to 4.

Router(config)# policy-map policy1 
Router(config-pmap)# class class1 
Router(config-pmap-c)# set qos-group 4

The service policy configured in this section is not yet attached to an interface. This command is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Configuring a Classifying CoS Values Example

In the following example, a service policy called policy1 is created. This service policy is associated to a previously defined classification policy through the use of the class command. This example assumes that a classification policy called class1 was previously configured.

In the following example, the CoS value is set to 5.

Router(config)# policy-map policy1 
Router(config-pmap)# class class1 
Router(config-pmap-c)# set cos 5

Changing the ATM CLP Value Example

In the following example, a service policy called policy1 is created. This service policy is associated to a previously defined classification policy through the use of the class command. This example assumes that a classification policy called class1 was previously configured.

In this example, all packets with IP precedence values of 0 or 1 are sent with the CLP bit set to 1:

Router(config)# policy-map policy1
Router(config-pmap)# class atm-discard
Router(config-pmap-c)# set atm-clp

The service policy configured in this section is not yet attached to an interface. This command is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Changing the Frame Relay DE Bit Value Example

In the following example, a traffic policy called policy1 is created. This traffic policy is associated to a previously defined traffic class through the use of the class command. This example assumes that a traffic class called class1 was previously configured.

In this example, all packets with IP precedence values of 0 or 1 are sent with the Frame Relay DE bit set to 1:

Router(config)# policy-map policy1
Router(config-pmap)# class fr-discard
Router(config-pmap-c)# set fr-de

The traffic policy configured in this section is not yet attached to an interface. This command is applied when you attach a service policy to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Additional References

The following sections provide references related to Class Based Marking.

Related Documents

Related Topic
Document Title

Modular Quality of Service

Modular Quality of Service Command-Line Interface

Distributed Weighted Random Early Detection and Distributed Class Based Weighted Fair Queuing

Distributed Weighted Random Early Detection and Distributed CBWFQ

Quality of Service

Cisco IOS Quality of Service Solutions Configuration Guide, Release 12.3

Cisco IOS Quality of Service Solutions Command Reference, Release 12.3


Standards

Standards
Title

None


MIBs

MIBs
MIBs Link

The Class-Based Quality of Service MIB stores information about Modular QoS CLI features, including the Class-Based Marking features. This MIB is actually the following two MIBs:

CISCO-CLASS-BASED-QOS-MIB

CISCO-CLASS-BASED-QOS-CAPABILITY-MIB

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

RFCs
Title

RFC 2474

Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers

RFC 2475

An Architecture for Differentiated Services

RFC 2597

Assured Forwarding PHB Group

RFC 2598

An Expedited Forwarding PHB


Technical Assistance

Description
Link

Technical Assistance Center (TAC) home page, containing 30,000 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/public/support/tac/home.shtml


Command Reference

This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.3 command reference publications.

set atm-clp

set cos

set fr-de

set ip dscp

set ip precedence

set qos-group


Note These commands are applied using the Modular QoS CLI. For more information on the Modular QoS CLI, including a listing of match command options, see the Modular Quality of Service Command-Line Interface document on CCO and the Documentation CD-ROM.



Note This feature module does not document any information related to MPLS experimental value marking which is applied using the set mpls experimental command. For information on MPLS experimental value marking, see the MPLS Quality of Service Enhancements feature module in the Cisco IOS Release 12.0(22)S new feature documentation index.


set atm-clp

To set the cell loss priority (CLP) bit when a policy map is configured, use the set atm-clp command in policy-map class configuration mode. To remove a specific CLP bit setting, use the no form of this command.

set atm-clp

Syntax Description

This command has no arguments or keywords.

Defaults

The CLP bit is automatically set to 0 when Cisco routers convert IP packets into ATM cells for transmission through Multiprotocol Label Switching (MPLS)-aware ATM networks.

Command Modes

Policy-map class configuration

Command History

Release
Modification

12.1(5)T

This command was introduced.

12.2(4)T

This command was implemented on the Cisco MGX 8850 switch and the MGX 8950 switch with a Cisco MGX RPM-PR card.

12.2(4)T2

This command was implemented on the Cisco 7500 series.

12.0(26)S

This command was integrated into Cisco IOS Release 12.0(26)S.


Usage Guidelines

To disable this command, remove the service policy from the interface.

To use the set atm-clp command, you must have one of the following adapters: the Enhanced ATM Port Adapter (PA-A3), the ATM Inverse Multiplexer over ATM Port Adapter with 8 T1 Ports (PA-A3-8T1IMA), or the ATM Inverse Multiplexer over ATM Port Adapter with 8 E1 Ports (PA-A3-8E1IMA). Therefore, the set atm-clp command is not supported on any platform that does not support these adapters. For more information, refer to the documentation for your specific router.

A policy map containing the set atm-clp command can be attached as an output policy only. The set atm-clp command does not support packets that originate from the router.

Examples

The following example illustrates setting the CLP bit using the set atm-clp command in the policy map:

Router(config)# class-map ip-precedence
Router(config-cmap)# match ip precedence 0 1
Router(config-cmap)# exit
Router(config)# policy-map atm-clp-set
Router(config-pmap)# class ip-precedence
Router(config-pmap-c)# set atm-clp
Router(config-pmap-c)# exit
Router(config-pmap)# exit
Router(config)# interface atm 1/0/0.1
Router(config-if)# service-policy output bear

Related Commands

Command
Description

policy-map

Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy.

show atm pvc

Displays all ATM PVCs and traffic information.

show policy-map

Displays information about the policy map for an interface.


set cos

To set the Layer 2 class of service (CoS) value of an outgoing packet, use the set cos command in policy-map class configuration mode. To remove a specific CoS value setting, use the no form of this command.

set cos {cos-value}

no set cos {cos-value}

Syntax Description

cos-value

Specific IEEE 802.1Q CoS value from 0 to 7.


Defaults

Disabled

Command Modes

Policy-map class configuration

Command History

Release
Modification

12.1(5)T

This command was introduced.

12.0(26)S

This command was integrated into Cisco IOS Release 12.0(26)S.


Usage Guidelines

CoS packet marking is supported only in the Cisco Express Forwarding (CEF)-switching path.

The set cos command should be used by a router if a user wants to mark a packet that is being sent to a switch. Switches can leverage Layer 2 header information, including a CoS value marking.

The set cos command can be used only in service policies that are attached in the output direction of an interface. Packets entering an interface cannot be set with a CoS value.

The match cos and set cos commands can be used together to allow routers and switches to interoperate and provide quality of service (QoS) based on the CoS markings.

Layer 2 to Layer 3 mapping can be configured by matching on the CoS value because switches already can match and set CoS values. If a packet that needs to be marked to differentiate user-defined QoS services is leaving a router and entering a switch, the router should set the CoS value of the packet because the switch can process the Layer 2 header.

Examples

In the following example, the policy map called "cos-set" is created to assign different CoSs for different types of traffic. This example assumes that the class maps called "voice" and "video-data" have already been created.

Router(config)# policy-map cos-set
Router(config-pmap)# class voice
Router(config-pmap-c)# set cos 1
Router(config-pmap-c)# exit
Router(config-pmap)# class video-data
Router(config-pmap-c)# set cos 2
Router(config-pmap-c)# exit
Router(config-pmap)# exit


Note The set cos command is applied when you create a service policy in policy-map configuration mode and attach the service policy to an interface or ATM virtual circuit (VC). For information on attaching a service policy, refer to the "Modular Quality of Service Command-Line Interface Overview" chapter of the Cisco IOS Quality of Service Solutions Configuration Guide.


Related Commands

Command
Description

match cos

Matches a packet on the basis of Layer 2 CoS marking.

policy-map

Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy.

service-policy

Attaches a policy map to an input interface or VC, or an output interface or VC, to be used as the service policy for that interface or VC.

show policy-map

Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.

show policy-map class

Displays the configuration for the specified class of the specified policy map.

show policy-map interface

Displays the configuration of all classes configured for all service policies on the specified interface or displays the classes for the service policy for a specific PVC on the interface.


set fr-de

To change the DE bit setting in the address field of a frame relay frame to 1 for all traffic leaving an interface, use the set fr-de command in policy map class mode. To disable the setting, use the no form of this command.

set fr-de

no set fr-de

Syntax Description

This command has no arguments or keywords.

Defaults

The DE bit is set to 0.

Command Modes

Policy map class

Command History

Release
Modification

12.2(2)T

This command was introduced.

12.0(26)S

This command was integrated into Cisco IOS Release 12.0(26)S.


Usage Guidelines

To disable this command in a traffic policy, use the no set fr-de command in policy map class configuration mode of the traffic policy.

If the DE bit is already set to 1, no changes are made to the frame.

Examples

The following example illustrates a DE bit that was set using the set fr-de command in the traffic policy:

Router(config)# class-map ip-prec
Router(config-cmap)# match ip precedence 0 1
Router(config-cmap)# exit
Router(config)# policy-map atm-clp-set
Router(config-pmap)# class ip-prec
Router(config-pmap-c)# set fr-de
Router(config-pmap-c)# exit
Router(config-pmap)# exit
Router(config)# interface atm 1/0/0
Router(config)# service-policy output bear

Related Commands

Command
Description

policy-map

Specifies the policy map to which the class belongs.

show policy-map

Displays information about the policy-map for an interface.


set ip dscp

To mark a packet by setting the IP differentiated services code point (DSCP) in the type of service (ToS) byte, use the set ip dscp policy map configuration command. To remove a previously set IP DSCP value, use the no form of this command.

set ip dscp ip-dscp-value

no set ip dscp ip-dscp-value

Syntax Description

ip-dscp-value

A number from 0 to 63 that sets the IP DSCP value. Reserved keywords, such as EF (expedited forwarding) and AF11 (assured forwarding class AF11), can be specified instead of numeric values.


Defaults

No default behavior or values.

Command Modes

Policy map configuration

Command History

Release
Modification

12.0(5)XE

This command was introduced in policy map configuration mode.

12.1(2)T

This command was enhanced to include reserved keywords such as EF, AF11, AF12, and so on instead of numeric values.

12.0(26)S

This command was integrated into Cisco IOS Release 12.0(26)S.


Usage Guidelines

Once the IP DSCP bit is set, other quality of service (QoS) services can then operate on the bit settings.

You cannot mark a packet by the IP precedence with the set ip precedence command and mark the same packet with an IP DSCP value by entering the set ip dscp command. If you are unsure of which method of marking to utilize, utilize IP precedence marking when your

The network gives priority (or some type of expedited handling) to marked traffic. Typically, you set IP precedence at the edge of the network (or administrative domain); data then is queued based on the precedence. Weighted fair queueing (WFQ) can speed up handling for high-precedence traffic at congestion points. Weighted random early detection (WRED) ensures that high-precedence traffic has lower loss rates than other traffic during times of congestion.

Reserved keywords such as EF, AF11, AF12 and so on can be specified instead of numeric values.

Examples

In the following example, the IP DSCP ToS byte is set to 8 in the policy map named policy1:

Router(config)# policy-map policy1 
Router(config-pmap)# class class1 
Router(config-pmap-c)# set ip dscp 8

All packets that satisfy the match criteria of class1 are marked with the IP DSCP value of 8. How packets marked with the IP DSCP value of 8 are treated is determined by the network configuration.

After you configure the settings shown for voice packets at the edge, all intermediate routers are then configured to provide low latency treatment to the voice packets, as follows:

Router(config)# class-map voice
Router(config-cmap)# match ip dscp ef
Router(config)# policy qos-policy
Router(config-pmap)# class voice
Router(config-pmap-c)# priority 24

The set ip dscp command is applied when you create a service policy in policy map configuration mode. This service policy is not yet attached to an interface. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Related Commands

Command
Description

policy-map

Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy.

service-policy

Displays the configuration of classes configured for service policies on the specified interface or PVC.

show policy-map

Displays the configuration of all classes comprising the specified service policy map or all classes for all existing policy maps.

show policy-map class

Displays the configuration for the specified class of the specified policy map.

show policy-map interface

Displays the configuration of classes configured for service policies on the specified interface or PVC.


set ip precedence

To set the precedence value in the IP header, use the set ip precedence policy map configuration command. To leave the precedence value as is, use the no form of this command.

set ip precedence ip-precedence-value

no set ip precedence

Syntax Description

ip-precedence-value

A number from 0 to 7 that sets the precedence bit in the IP header.


Defaults

This command is disabled by default.

Command Modes

Policy map configuration

Command History

Release
Modification

11.0

This command was introduced.

12.0(5)XE

This command was introduced in the modular quality of service (QoS) command-line interface.

12.0(26)S

This command was integrated into Cisco IOS Release 12.0(26)S.


Usage Guidelines

Once the IP precedence bits are set, other QoS services such as weighted fair queueing (WFQ) and weighted random early detection (WRED) then operate on the bit settings.

The network gives priority (or some type of expedited handling) to marked traffic through the application of WFQ or WRED at points downstream in the network. Typically, you set IP precedence at the edge of the network (or administrative domain); data then is queued based on the precedence. WFQ can speed up handling for certain precedence traffic at congestion points. WRED can ensure that certain precedence traffic has lower loss rates than other traffic during times of congestion.

Examples

The following example sets the IP precedence to 5 for packets that satisfy the match criteria of class map class1:

Router(config)# policy-map policy1
Router(config-pmap)# class class1
Router(config-pmap-c)# set ip precedence 5


All packets that satisfy the match criteria of class1 are marked with the IP precedence value of 5. How packets marked with the IP precedence value of 5 are treated is determined by the network configuration.

The set ip precedence command is applied when you create a service policy in policy map configuration mode. This service policy is not yet attached to an interface or to an ATM virtual circuit. For information on attaching a service policy to an interface, see the Modular Quality of Service Command-Line Interface document.

Related Commands

Command
Description

policy-map

Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy.

service-policy

Displays the configuration of classes configured for service policies on the specified interface or PVC.

show policy-map

Displays the configuration of all classes comprising the specified service policy map or all classes for all existing policy maps.

show policy-map interface

Displays the configuration of classes configured for service policies on the specified interface or PVC.


set qos-group

To set a quality of service (QoS) group identifier (ID) that can be used later to classify packets, use the set qos-group command in policy-map class configuration mode. To remove the group ID, use the no form of this command.

set qos-group {group-id }

no set qos-group {group-id }

Syntax Description

group-id

Group ID number in the range from 0 to 99.


Defaults

Disabled

No group ID is specified.

Command Modes

Policy-map class configuration

Command History

Release
Modification

11.1 CC

This command was introduced.

12.0(5)XE

This command was integrated into Cisco IOS Release 12.0(5)XE.

12.0(26)S

This command was integrated into Cisco IOS Release 12.0(26)S.


Usage Guidelines

The set qos-group command allows you to associate a group ID with a packet. The group ID can be used later to classify packets into QoS groups based as prefix, autonomous system, and community string.

A QoS group and discard class are required when the input per-hop behavior (PHB) marking will be used for classifying packets on the output interface.

Examples

The following example sets the QoS group to 1 for all packets that match the class map called "class1". These packets are then rate limited on the basis of the QoS group ID.

Router(config)# policy-map policy1 
Router(config-pmap)# class class1 
Router(config-pmap-c)# set qos-group 1


Note The set qos-group command is applied when you create a service policy in policy-map configuration mode and then attach the service policy to an interface or ATM virtual circuit (VC). For information on attaching a service policy, refer to the "Modular Quality of Service Command-Line Interface Overview" chapter of the Cisco IOS Quality of Service Solutions Configuration Guide.


Related Commands

Command
Description

match qos-group

Identifies a specified QoS group value as a match criterion.

policy-map

Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy.

service-policy

Attaches a policy map to an input interface or VC, or an output interface or VC, to be used as the service policy for that interface or VC.

show policy-map

Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.

show policy-map interface

Displays the configuration of all classes configured for all service policies on the specified interface or displays the classes for the service policy for a specific PVC on the interface.