Classifying Network Traffic

First Published: May 02, 2005
Last Updated: May 29, 2009

Classifying network traffic allows you to organize traffic (that is, packets) into traffic classes or categories on the basis of whether the traffic matches specific criteria. Classifying network traffic is the foundation for enabling many quality of service (QoS) features on your network. This module contains conceptual information and the configuration tasks for classifying network traffic.

Finding Feature Information

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 Classifying Network Traffic" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE 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

•Information About Classifying Network Traffic

•How to Classify Network Traffic

•Configuration Examples for Classifying Network Traffic

•Additional References

•Feature Information for Classifying Network Traffic

Information About Classifying Network Traffic

•Purpose of Classifying Network Traffic

•Benefits of Classifying Network Traffic

•MQC and Network Traffic Classification

•Network Traffic Classification match Commands and Match Criteria

•Traffic Classification Compared with Traffic Marking

Purpose of Classifying Network Traffic

Classifying network traffic allows you to organize traffic (that is, packets) into traffic classes or categories on the basis of whether the traffic matches specific criteria. Classifying network traffic is the foundation for enabling other QoS features such as traffic shaping and traffic policing on your network.

The goal of network traffic classification is to group traffic based on user-defined criteria so that the resulting groups of network traffic can then be subjected to specific QoS treatments. The QoS treatments might include faster forwarding by intermediate routers and switches or reduced probability of the traffic being dropped due to lack of buffering resources.

Identifying and categorizing network traffic into traffic classes (that is, classifying packets) enables distinct handling for different types of traffic, effectively separating network traffic into different categories. This classification can be associated with a variety of match criteria such as the IP Precedence value, differentiated services code point (DSCP) value, class of service (CoS) value, source and destination MAC addresses, input interface, or protocol type. You classify network traffic by using class maps and policy maps with the Modular Quality of Service Command-Line Interface (MQC). For example, you can configure class maps and policy maps to classify network traffic on the basis of the QoS group, Frame Relay DLCI number, Layer 3 packet length, or other criteria that you specify.

Benefits of Classifying Network Traffic

Classifying network traffic allows you to see what kinds of traffic you have, organize the various kinds of network traffic into traffic classes, and treat some types of traffic differently than others. Identifying and organizing network traffic is the foundation for applying the appropriate QoS feature to that traffic, enabling you to allocate network resources to deliver optimal performance for different types of traffic. For example, high-priority network traffic or traffic matching specific criteria can be singled out for special handling, and thus, help to achieve peak application performance.

MQC and Network Traffic Classification

To configure network traffic classification, you use the Modular Quality of Service Command-Line Interface (MQC).

The MQC is a CLI structure that allows you to complete the following tasks:

•Specify the matching criteria used to define a traffic class.

•Create a traffic policy (policy map). The traffic policy defines the QoS policy actions to be taken for each traffic class.

•Apply the policy actions specified in the policy map to an interface, subinterface, or ATM permanent virtual circuit (PVC) by using the service-policy command.

Network Traffic Classification match Commands and Match Criteria

Network traffic classification allows you to group or categorize traffic on the basis of whether the traffic meets one or more specific criteria. For example, network traffic with a specific IP precedence can be placed into one traffic class, while traffic with a specific DSCP value can be placed into another traffic class. The network traffic within that traffic class can be given the appropriate QoS treatment, which you can configure in a policy map later.

You specify the criteria used to classify traffic with a match command. Table 1 lists the available match commands and the corresponding match criterion.

Table 1 match Commands and Corresponding Match Criterion 

match Commands 1
Match Criterion

match access group

Access control list (ACL) number

match any

Any match criteria

match atm clp

ATM cell loss priority (CLP)

match class-map

Traffic class name

match cos

Layer 2 class of service (CoS) value

match destination-address mac

MAC address

match discard-class

Discard class value

match dscp

DSCP value

match field

Fields defined in the protocol header description files (PHDFs)

match fr-de

Frame Relay discard eligibility (DE) bit setting

match input-interface

Input interface name

match ip rtp

Real-Time Transport Protocol (RTP) port

match mpls experimental

Multiprotocol Label Switching (MPLS) experimental (EXP) value

match mpls experimental topmost

MPLS EXP value in the topmost label

match not

Single match criterion value to use as an unsuccessful match criterion

match packet length (class-map)

Layer 3 packet length in the IP header

match port-type

Port type

match precedence

IP precedence values

match protocol

Protocol type

match protocol (NBAR)

Protocol type known to network-based application recognition (NBAR)

match protocol citrix

Citrix protocol

match protocol fasttrack

FastTrack peer-to-peer traffic

match protocol gnutella

Gnutella peer-to-peer traffic

match protocol http

Hypertext Transfer Protocol

match protocol rtp

RTP traffic

match qos-group

QoS group value

match source-address mac

Source Media Access Control (MAC) address

match start

Datagram header (Layer 2) or the network header (Layer 3)

match tag (class-map)

Tag type of class map

match vlan (QoS)

Layer 2 virtual local-area network (VLAN) identification number

1 Cisco IOS match commands can vary by release and platform. For more information, see the command documentation for the Cisco IOS release and platform that you are using.


Traffic Classification Compared with Traffic Marking

Traffic classification and traffic marking are closely related and can be used together. Traffic marking can be viewed as an additional action, specified in a policy map, to be taken on a traffic class.

Traffic classification allows you to organize into traffic classes on the basis of whether the traffic matches specific criteria. For example, all traffic with a CoS value of 2 is grouped into one class, and traffic with DSCP value of 3 is grouped into another class. The match criterion is user-defined.

After the traffic is organized into traffic classes, traffic marking allows you to mark (that is, set or change) an attribute for the traffic belonging to that specific class. For instance, you may want to change the CoS value from 2 to 1, or you may want to change the DSCP value from 3 to 2.

The match criteria used by traffic classification are specified by configuring a match command in a class map. The marking action taken by traffic marking is specified by configuring a set command in a policy map. These class maps and policy maps are configured using the MQC.

Table 2 compares the features of traffic classification and traffic marking.

Table 2 Traffic Classification Compared with Traffic Marking

 
Traffic Classification
Traffic Marking
Goal

Groups network traffic into specific traffic classes on the basis of whether the traffic matches the user-defined criteria.

After the network traffic is grouped into traffic classes, modifies the attributes for the traffic in a particular traffic class.

Configuration Mechanism

Uses class maps and policy maps in the MQC.

Uses class maps and policy maps in the MQC.

CLI

In a class map, uses match commands (for example, match cos) to define the traffic matching criteria.

Uses the traffic classes and matching criteria specified by traffic classification.

In addition, uses set commands (for example, set cos) in a policy map to modify the attributes for the network traffic.

If a table map was created, uses the table keyword and table-map-name argument with the set commands (for example, set cos precedence table table-map-name) in the policy map to establish the to-from relationship for mapping attributes.


How to Classify Network Traffic

Creating a Class Map for Classifying Network Traffic

Note In the following task, the match fr-dlci command is shown in Step 4. The match fr-dlci command matches traffic on the basis of the Frame Relay DLCI number. The match fr-dlci command is just an example of one of the match commands that can be used. For a list of other match commands, see Table 1.

SUMMARY STEPS

1. enable

2. configure terminal

3. class-map class-map-name [match-all | match-any]

4. match fr-dlci dlci-number

5. 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 

class-map class-map-name [match-all | match-any]

Example:

Router(config)# class-map class1

Creates a class map to be used for matching traffic to a specified class, and enters class-map configuration mode.

•Enter the class map name.

Step 4 

match fr-dlci dlci-number

Example:

Router(config-cmap)# match fr-dlci 500

(Optional) Specifies the match criteria in a class map.

Note The match fr-dlci command classifies traffic on the basis of the Frame Relay DLCI number. The match fr-dlci command is just an example of one of the match commands that can be used. For a list of other match commands, see Table 1.

Step 5 

end

Example:

Router(config-cmap)# end

(Optional) Returns to privileged EXEC mode.

Creating a Policy Map for Applying a QoS Feature to Network Traffic

Note In the following task, the bandwidth command is shown at Step 5. The bandwidth command configures the QoS feature class-based weighted fair queuing (CBWFQ). CBWFQ is just an example of a QoS feature that can be configured. Use the appropriate command for the QoS feature that you want to use.

Note Configuring bandwidth on policies that have the class-default class is supported on physical interfaces such as Gigabit Ethernet (GigE), Serial, Mobile Location Protocol (MLP), and Multilink Frame-Relay (MFR), but it is not supported on logical interfaces such as Virtual Access Interface (VAI), Subinterface, and Frame-Relay on Virtual Circuits (FR-VC).

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map policy-map-name

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

5. bandwidth {bandwidth-kbps | remaining percent percentage | percent percentage}

6. end

7. show policy-map

or

show policy-map policy-map class class-name

8. exit

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 policy1

Specifies the name of the policy map to be created and enters policy-map configuration mode.

•Enter the policy map name.

Step 4 

class {class-name | class-default}

Example:

Router(config-pmap)# class class1

Specifies the name of the class and enters policy-map class configuration mode. This class is associated with the class map created earlier.

•Enter the name of the class or enter the class-default keyword.

Step 5 

bandwidth {bandwidth-kbps | remaining percent percentage | percent percentage}

Example:

Router(config-pmap-c)# bandwidth percent 50

(Optional) Specifies or modifies the bandwidth allocated for a class belonging to a policy map.

•Enter the amount of bandwidth as a number of kbps, a relative percentage of bandwidth, or an absolute amount of bandwidth.

Note The bandwidth command configures the QoS feature class-based weighted fair queuing (CBWFQ). CBWFQ is just an example of a QoS feature that can be configured. Use the appropriate command for the QoS feature that you want to use.

Step 6 

end

Example:

Router(config-pmap-c)# end

Returns to privileged EXEC mode.

Step 7 

show policy-map

(Optional) Displays all configured policy maps.

 

or

or

 

show policy-map policy-map class class-name


(Optional) Displays the configuration for the specified class of the specified policy map.

•Enter the policy map name and the class name.

 
Example:

Router# show policy-map

 
 

or

 
 
Example:

Router# show policy-map policy1 class class1

 

Step 8 

exit

Example:

Router# exit

(Optional) Exits privileged EXEC mode.

What to Do Next

Create and configure as many policy maps as you need for your network. To create and configure additional policy maps, repeat the steps in the "Creating a Policy Map for Applying a QoS Feature to Network Traffic" section. Then attach the policy maps to the appropriate interface, following the instructions in the "Attaching the Policy Map to an Interface" section.

Attaching the Policy Map to an Interface

Note Depending on the needs of your network, policy maps can be attached to an interface, a subinterface, or an ATM PVC.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface type number [name-tag]

4. pvc [name] vpi/vci [ilmi | qsaal | smds | l2transport]

5. exit

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

7. end

8. show policy-map interface type number

9. exit

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 number [name-tag]

Example:

Router(config)# interface serial4/0/0

Configures an interface type and enters interface configuration mode.

•Enter the interface type and number.

Step 4 

pvc [name] vpi/vci [ilmi |qsaal |smds | l2transport]

Example:

Router(config-if)# pvc cisco 0/16

(Optional) Creates or assigns a name to an ATM PVC, specifies the encapsulation type on an ATM PVC, and enters ATM virtual circuit configuration mode.

•Enter the PVC name, the ATM network virtual path identifier, and the network virtual channel identifier.

Note This step is required only if you are attaching the policy map to an ATM PVC. If you are not attaching the policy map to an ATM PVC, advance to Step 6.

Step 5 

exit

Example:

Router(config-atm-vc)# exit

(Optional) Returns to interface configuration mode.

Note This step is required only if you are attaching the policy map to an ATM PVC and you completed Step 4. If you are not attaching the policy map to an ATM PVC, advance to Step 6.

Step 6 

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

Example:

Router(config-if)# service-policy input policy1

Attaches a policy map to an input or output interface.

•Enter the policy map name.

Note Policy maps can be configured on ingress or egress routers. They can also be attached in the input or output direction of an interface. The direction (input or output) and the router (ingress or egress) to which the policy map should be attached varies according your network configuration. When using the service-policy command to attach the policy map to an interface, be sure to choose the router and the interface direction that are appropriate for your network configuration.

Step 7 

end

Example:

Router(config-if)# end

Returns to privileged EXEC mode.

Step 8 

show policy-map interface type number

Example:

Router# show policy-map interface serial4/0/0

(Optional) Displays the traffic statistics of all traffic classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface.

•Enter the type and number.

Step 9 

exit

Example:

Router# exit

(Optional) Exits privileged EXEC mode.

Configuring QoS When Using IPsec VPNs

Note This task is required only if you are using IPsec Virtual Private Networks (VPNs). Otherwise, this task is not necessary. For information about IPsec VPNs, see the "Configuring Security for VPNs with IPsec" module.

Restrictions

This task uses the qos pre-classify command to enable QoS preclassification for the packet. QoS preclassification is not supported for all fragmented packets. If a packet is fragmented, each fragment might receive different preclassifications.

SUMMARY STEPS

1. enable

2. configure terminal

3. crypto map map-name seq-num

4. exit

5. interface type number [name-tag]

6. qos pre-classify

7. 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 

crypto map map-name seq-num

Example:

Router(config)# crypto map mymap 10

Enters crypto map configuration mode and creates or modifies a crypto map entry.

•Enter the crypto map name and sequence number.

Step 4 

exit

Example:

Router(config-crypto-map)# exit

Returns to global configuration mode.

Step 5 

interface type number [name-tag]

Example:

Router(config)# interface serial4/0/0

Configures an interface type and enters interface configuration mode.

•Enter the interface type and number.

Step 6 

qos pre-classify

Example:

Router(config-if)# qos pre-classify

Enables QoS preclassification.

Step 7 

end

Example:

Router(config-if)# end

(Optional) Returns to privileged EXEC mode.

Configuration Examples for Classifying Network Traffic

Example: Creating a Class Map for Classifying Network Traffic

The following is an example of creating a class map to be used for traffic classification. In this example, a traffic class called class1 has been created. Traffic with a Frame Relay DLCI value of 500 will be put in this traffic class.

Router> enable

Router# configure terminal

Router(config)# class-map class1

Router(config-cmap)# match fr-dlci 500

Router(config-cmap)# end


Note This example uses the match fr-dlci command. The match fr-dlci command is just an example of one of the match commands that can be used. For a list of other match commands, see Table 1.

Example: Creating a Policy Map for Applying a QoS Feature to Network Traffic

The following is an example of creating a policy map to be used for traffic classification. In this example, a policy map called policy1 has been created, and the bandwidth command has been configured for class1. The bandwidth command configures the QoS feature CBWFQ. 

Router> enable

Router# configure terminal

Router(config)# policy-map policy1

Router(config-pmap)# class class1

Router(config-pmap-c)# bandwidth percent 50 

Router(config-pmap-c)# end

Router# show policy-map policy1 class class1

Router# exit

Note This example uses the bandwidth command. The bandwidth command configures the QoS feature class-based weighted fair queuing (CBWFQ). CBWFQ is just an example of a QoS feature that can be configured. Use the appropriate command for the QoS feature that you want to use.

Example: Attaching the Policy Map to an Interface

The following is an example of attaching the policy map to an interface. In this example, the policy map called policy1 has been attached in the input direction of serial interface 4/0. 

Router> enable

Router# configure terminal

Router(config)# interface serial4/0/0

Router(config-if)# service-policy input policy1 

Router(config-if)# end

Router# show policy-map interface serial4/0/0

Router# exit

Example: Configuring QoS When Using IPsec VPNs

The following is an example of configuring QoS when using IPsec VPNs. In this example, the crypto map command specifies the IPsec crypto map (mymap 10) to which the qos pre-classify command is applied. 

Router> enable

Router# configure terminal

Router(config)# crypto map mymap 10 

Router(config-crypto-map)# exit

Router(config)# interface serial4/0/0

Router(config-if)# qos pre-classify

Router(config-if)# end

Additional References

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples

Cisco IOS Quality of Service Solutions Command Reference

MQC

"Applying QoS Features Using the MQC" module

Marking network traffic

"Marking Network Traffic" module

IPsec and VPNs

"Configuring Security for VPNs with IPsec" module

NBAR

"Classifying Network Traffic Using NBAR" module


Standards

Standard
Title

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

—


MIBs

MIB
MIBs Link

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

To locate and download MIBs for selected platforms, Cisco IOS XE 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, and support for existing RFCs has not been modified.

—


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 Classifying Network Traffic

Table 3 lists the features in this module.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE 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 3 lists only the Cisco IOS XE Software release that introduced support for a given feature in a given Cisco IOS XE Software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE Software release train also support that feature.

Table 3 Feature Information for Classifying Network Traffic  

Feature Name
Releases
Feature Information

Class-Based Ethernet CoS Matching & Marking (802.1p & ISL CoS)

Cisco IOS XE Release 2.1

This feature was introduced on Cisco ASR 1000 Series Routers.

The following sections provide information about this feature:

•Information About Classifying Network Traffic.

•How to Classify Network Traffic.

Class-Based Marking

Cisco IOS XE Release 2.1

This feature was introduced on Cisco ASR 1000 Series Routers.

The following sections provide information about this feature:

•Information About Classifying Network Traffic.

•How to Classify Network Traffic.

Packet Classification Using Frame Relay DLCI Number

Cisco IOS XE Release 2.1

The Packet Classification Using the Frame Relay DLCI Number feature allows customers to match and classify traffic based on the Frame Relay data-link connection identifier (DLCI) number associated with a packet. This new match criteria is in addition to the other match criteria, such as the IP Precedence, differentiated services code point (DSCP) value, class of service (CoS), currently available.

The following sections provide information about this feature:

•Information About Classifying Network Traffic.

•How to Classify Network Traffic.

QoS: Local Traffic Matching Through MQC

Cisco IOS XE Release 2.1

This feature was introduced on Cisco ASR 1000 Series Routers.

The following sections provide information about this feature:

•Information About Classifying Network Traffic

•How to Classify Network Traffic.

QoS: Match ATM CLP

Cisco IOS XE Release 2.3

The QoS: Match ATM CLP features allows you to classify traffic on the basis of the ATM cell loss priority (CLP) value.

The following sections provide information about this feature:

•Information About Classifying Network Traffic.

•How to Classify Network Traffic.

The following command was introduced or modified: match atm-clp.

QoS: Match VLAN

Cisco IOS XE Release 2.1

This feature was introduced on Cisco ASR 1000 Series Routers.

The following sections provide information about this feature:

•Information About Classifying Network Traffic.

•How to Classify Network Traffic.

QoS: MPLS EXP Bit Traffic Classification

Cisco IOS XE Release 2.3

The QoS: MPLS EXP Bit Traffic Classification feature allows you to classify traffic on the basis of the Multiprotocol Label Switching (MPLS) experimental (EXP) value.

The following sections provide information about this feature:

•Information About Classifying Network Traffic.

•How to Classify Network Traffic.

The following command was introduced or modified: match mpls experimental.

QoS: Traffic Pre-classification

Cisco IOS XE Release 2.1

This feature was introduced on Cisco ASR 1000 Series Routers.

The following sections provide information about this feature:

•Configuring QoS When Using IPsec VPNs.

QoS Group: Match and Set for Classification and Marking

Cisco IOS XE Release 2.1

This feature was introduced on Cisco ASR 1000 Series Routers.

The following sections provide information about this feature:

•Information About Classifying Network Traffic.

•How to Classify Network Traffic


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