Table Of Contents

Marking Network Traffic

Finding Feature Information

Contents

Restrictions for Marking Network Traffic

Information About Marking Network Traffic

Purpose of Marking Network Traffic

Benefits of Marking Network Traffic

Method for Marking Traffic Attributes

Using a set Command

MQC and Network Traffic Marking

Traffic Classification Compared with Traffic Marking

How to Mark Network Traffic

Creating a Class Map for Marking Network Traffic

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

Restrictions

What to Do Next

Attaching the Policy Map to an Interface

Configuring QoS When Using IPsec VPNs

Restrictions

Configuration Examples for Marking Network Traffic

Creating a Class Map for Marking Network Traffic: Example

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

Attaching the Policy Map to an Interface: Example

Configuring QoS When Using IPsec VPNs: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Marking Network Traffic

Glossary

Marking Network Traffic

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First Published: May 2, 2005

Last Updated: March 2, 2009

Marking network traffic allows you to set or modify the attributes for traffic (that is, packets) belonging to a specific class or category. When used in conjunction with network traffic classification, marking 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 marking 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 Marking 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

•Restrictions for Marking Network Traffic

•Information About Marking Network Traffic

•How to Mark Network Traffic

•Configuration Examples for Marking Network Traffic

•Additional References

•Feature Information for Marking Network Traffic

•Glossary

Restrictions for Marking Network Traffic

Traffic marking can be configured on an interface, a subinterface, or an ATM permanent virtual circuit (PVC). Marking network traffic is not supported on the following interfaces:

•ATM switched virtual circuit (SVC)

•Fast EtherChannel

•PRI

•Tunnel

Information About Marking Network Traffic

To mark network traffic, you should understand the following concepts:

•Purpose of Marking Network Traffic

•Benefits of Marking Network Traffic

•Method for Marking Traffic Attributes

•MQC and Network Traffic Marking

•Traffic Classification Compared with Traffic Marking

Purpose of Marking Network Traffic

Traffic marking is a method used to identify certain traffic types for unique handling, effectively partitioning network traffic into different categories.

After the network traffic is organized into classes by traffic classification, traffic marking allows you to mark (that is, set or change) a value (attribute) for the traffic belonging to a specific class. For instance, you may want to change the class of service (CoS) value from 2 to 1 in one class, or you may want to change the differentiated services code point (DSCP) value from 3 to 2 in another class. In this module, these values are referred to as attributes.

Attributes that can be set and modified include the following:

•Cell loss priority (CLP) bit

•CoS value of an outgoing packet

•Discard eligible (DE) bit setting in the address field of a Frame Relay frame

•Discard-class value

•DSCP value in the type of service (ToS) byte

•MPLS EXP field value in the topmost label on either an input or an output interface

•Multiprotocol Label Switching (MPLS) experimental (EXP) field on all imposed label entries

•Precedence value in the packet header

•QoS group identifier (ID)

•ToS bits in the header of an IP packet

Benefits of Marking Network Traffic

Improved Network Performance

Traffic marking allows you to fine-tune the attributes for traffic on your network. This increased granularity helps single out traffic that requires special handling, and thus, helps to achieve optimal application performance.

Traffic marking allows you to determine how traffic will be treated, based on how the attributes for the network traffic are set. It allows you to segment network traffic into multiple priority levels or classes of service based on those attributes, as follows:

•Traffic marking is often used to set the IP precedence or IP DSCP values for traffic 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 traffic can be marked with a particular IP precedence or DSCP and a queueing mechanism can then be configured to put all packets of that mark into a priority queue.

•Traffic marking can be used to identify traffic for any class-based QoS feature (any feature available in policy-map class configuration mode, although some restrictions exist).

•Traffic marking can be used to assign traffic to a QoS group within a router. The router can use the QoS groups to determine how to prioritize traffic 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 markings, as opposed to DSCP and Precedence, which have 64 and 8, respectively.

–If changing the Precedence or DSCP value is undesirable.

•If a packet (for instance, in a traffic flow) 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 traffic, because the switch can process the Layer 2 CoS header marking. Alternatively, the Layer 2 CoS value of the traffic leaving a switch can be mapped to the Layer 3 IP or MPLS value.

Method for Marking Traffic Attributes

You specify and mark the traffic attribute by using a set command.

With this method, you configure individual set commands for the traffic attribute that you want to mark.

Using a set Command

You specify the traffic attribute you want to change with a set command configured in a policy map. Table 1 lists the available set commands and the corresponding attribute. Table 1 also includes the network layer and the network protocol typically associated with the traffic attribute.

Table 1 set Commands and Corresponding Traffic Attribute, Network Layer, and Protocol 

set Commands1	Traffic Attribute	Network Layer	Protocol
set cos	Layer 2 CoS value of the outgoing traffic	Layer 2	ATM, Frame Relay
set discard-class	discard-class value	Layer 2	ATM, Frame Relay
set dscp	DSCP value in the ToS byte	Layer 3	IP
set fr-de	DE bit setting in the address field of a Frame Relay frame	Layer 2	Frame Relay
set ip tos (route-map)	ToS bits in the header of an IP packet	Layer 3	IP
set mpls experimental imposition	MPLS EXP field on all imposed label entries	Layer 3	MPLS
set mpls experimental topmost	MPLS EXP field value in the topmost label on either an input or an output interface	Layer 3	MPLS
set precedence	precedence value in the packet header	Layer 3	IP
set qos-group	QoS group ID	Layer 3	IP, MPLS

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

If you are using individual set commands, those set commands are specified in a policy map. The following is a sample of a policy map configured with one of the set commands listed in Table 1.

In this sample configuration, the set cos command has been configured in the policy map (policy1) to mark the set the CoS value.

 policy-map policy1

  class class1

  set cos 1

  end

For information on configuring a policy map, see the "Creating a Policy Map for Applying a QoS Feature to Network Traffic" section.

The final task is to attach the policy map to the interface. For information on attaching the policy map to the interface, see the "Attaching the Policy Map to an Interface" section.

MQC and Network Traffic Marking

To configure network traffic marking, you use the Modular Quality of Service (QoS) Command-Line Interface (CLI) (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 PVC by using the service-policy command.

For more information about the MQC, see the "Applying QoS Features Using the MQC" module.

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 criterion.	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 criterion.	Uses the traffic classes and matching criterion 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.

How to Mark Network Traffic

This section contains the following procedures.

•Creating a Class Map for Marking Network Traffic (required)

•Creating a Policy Map for Applying a QoS Feature to Network Traffic (optional)

•Creating a Policy Map for Applying a QoS Feature to Network Traffic (required)

•Attaching the Policy Map to an Interface (required)

•Configuring QoS When Using IPsec VPNs (optional)

Creating a Class Map for Marking Network Traffic

In this procedure, you create a class map to define traffic classes. Within the class map, the appropriate match command is used to specify the matching criteria for the traffic classes.

To create the class map and specify the matching criteria, complete the following steps.

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Note The match protocol command is included in the steps below. The match protocol command is just an example of one of the match commands that can be used. See the command documentation for the Cisco IOS release that you are using for a complete list of match commands.

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SUMMARY STEPS

1. enable

2. configure terminal

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

4. match protocol protocol-name

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 protocol protocol-name Example: Router(config-cmap)# match protocol ftp	(Optional) Configures the match criterion for a class map on the basis of the specified protocol. The match protocol command is just an example of one of the match commands that can be used. The match commands vary by Cisco IOS XE release. See the command documentation for the Cisco IOS XE release that you are using for a complete list of match commands.
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

In this procedure, you create and configure a policy map to use the class map (or the table map). The policy map applies the appropriate QoS feature to the network traffic based on the traffic classification.

To create a policy map, complete the following steps.

Restrictions

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

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

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Note The set cos command is shown in the steps that follow. The set cos command is an example of a set command that can be used when marking traffic. Other set commands can be used. For a list of other set commands, see Table 1.

---

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map policy-map-name

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

5. set cos cos-value

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 created earlier 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 whose policy you want to create 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	set cos cos-value	(Optional) Sets the CoS value in the type of service (ToS) byte. Note The set cos command is an example of one of the set commands that can be used when marking traffic. Other set commands can be used. For a list of other set commands, see Table 1.
	Example: Router(config-pmap-c)# set cos 2
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

After you create the policy map, you must attach it to an interface. Policy maps can be attached to either the input or output direction of the interface.

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

---

To attach the policy map, complete the following steps.

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 permanent virtual circuit (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 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 interface type and number.
Step 9	exit Example: Router# exit	(Optional) Exits privileged EXEC mode.

Configuring QoS When Using IPsec VPNs

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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.

---

To configure QoS when using IPsec VPNs, complete the following steps.

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 received 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) Exits interface configuration mode and returns to privileged EXEC mode.

Configuration Examples for Marking Network Traffic

This section contains the following examples:

•Creating a Class Map for Marking Network Traffic: Example

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

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

•Attaching the Policy Map to an Interface: Example

•Configuring QoS When Using IPsec VPNs: Example

Creating a Class Map for Marking Network Traffic: Example

The following is an example of creating a class map to be used for marking network traffic. In this example, a class called class1 has been created. The traffic with a protocol type of ftp will be put in this class.

Router> enable

Router# configure terminal

Router(config)# class-map class1

Router(config-cmap)# match protocol ftp

Router(config-cmap)# end

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

Policy Map Configured to Use set Command

The following is an example of creating a policy map to be used for traffic marking. In this example, a policy map called policy1 has been created, and the set dscp command has been configured for class1.

Router> enable

Router# configure terminal

Router(config)# policy-map policy1

Router(config-pmap)# class class1

Router(config-pmap-c)# set dscp 2

Router(config-pmap-c)# end

Attaching the Policy Map to an Interface: Example

The following is an example of attaching the policy map to the interface. In this example, the policy map called policy1 has been attached in the input direction of the Serial4/0 interface.

Router> enable

Router# configure terminal

Router(config)# interface serial4/0/0

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

Router(config-if)# end

Configuring QoS When Using IPsec VPNs: Example

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 will be 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

The following sections provide references related to marking network traffic.

Related Documents

Related Topic	Document Title
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
Classifying network traffic	"Classifying Network Traffic" module
IPsec and VPNs	"Configuring Security for VPNs with IPsec" 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 website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport

Feature Information for Marking Network Traffic

Table 3 lists the features in this module and provides links to specific configuration information.

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.

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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.

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Table 3 Feature Information for Marking Network Traffic 

Feature Name	Software Releases	Feature Configuration Information
Class Based Ethernet CoS Matching & Marking (802.1p & ISL CoS)	Cisco IOS XE Release 2.1	This feature was implemented on Cisco ASR 1000 Series Routers. The following sections provide information about this feature: •Information About Marking Network Traffic •How to Mark Network Traffic
Class-Based Marking	Cisco IOS XE Release 2.1	This feature was implemented on Cisco ASR 1000 Series Routers. The following sections provide information about this feature: •Information About Marking Network Traffic •How to Mark Network Traffic
Frame Relay DE Bit Marking	Cisco IOS XE Release  2.1	This feature was implemented on Cisco ASR 1000 Series Routers. The following sections provide information about this feature: •Information About Marking Network Traffic •How to Mark Network Traffic
IP DSCP marking for Frame-Relay PVC	Cisco IOS XE Release 2.1	This feature was implemented on Cisco ASR 1000 Series Routers. The following sections provide information about this feature: •Information About Marking Network Traffic •How to Mark Network Traffic
QoS Group: Match and Set for Classification and Marking	Cisco IOS XE Release 2.1	This feature was implemented on Cisco ASR 1000 Series Routers. The following sections provide information about this feature: •Information About Marking Network Traffic •How to Mark Network Traffic
QoS Packet Marking	Cisco IOS XE Release  2.1	This feature was implemented on Cisco ASR 1000 Series Routers. The following sections provide information about this feature: •Information About Marking Network Traffic •How to Mark Network Traffic
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
Class-Based Marking	Cisco IOS XE Release 2.2	This feature was integrated into Cisco IOS XE Software Release 2.2. The following sections provide information about this feature: •Information About Marking Network Traffic •How to Mark Network Traffic
QoS Packet Marking	Cisco IOS XE Release 2.2	This feature was integrated into Cisco IOS XE Software Release 2.2. The following sections provide information about this feature: •Information About Marking Network Traffic •How to Mark Network Traffic

Glossary

ATM—Asynchronous Transfer Mode. The international standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells. Fixed-length cells allow cell processing to occur in hardware, thereby reducing transit delays. ATM is designed to take advantage of high-speed transmission media, such as E3, SONET, and T3.

CoS—class of service. An indication of how an upper-layer protocol requires a lower-layer protocol to treat its messages. A CoS definition comprises a virtual route number and a transmission priority field.

DLCI—data-link connection identifier. A value that specifies a PVC or a switched virtual circuit (SVC) in a Frame Relay network. In the basic Frame Relay specification, DLCIs are locally significant (connected devices might use different values to specify the same connection). In the Local Management Interface (LMI) extended specification, DLCIs are globally significant (DLCIs specify individual end devices).

IPsec—IP Security. A framework of open standards that provides data confidentiality, data integrity, and data authentication between participating peers. IPsec provides these security services at the IP layer. IPsec uses Internet Key Exchange (IKE) to handle the negotiation of protocols and algorithms based on local policy and to generate the encryption and authentication keys to be used by IPsec. IPsec can protect one or more data flows between a pair of hosts, between a pair of security gateways, or between a security gateway and a host.

LER—label edge router. LERs are typically used in a Multiprotocol Label Switching network.

MPLS—Multiprotocol Label Switching. A switching method that forwards IP traffic using a label. This label instructs the routers and the switches in the network where to forward the packets based on preestablished IP routing information

PVC—permanent virtual circuit (or connection). A virtual circuit that is permanently established. PVCs save bandwidth associated with circuit establishment and tear down in situations where certain virtual circuits must exist all the time. In ATM terminology, called a permanent virtual connection.

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