- Configuring Multiprotocol Label Switching (MPLS)
- Configuring eBGP and iBGP Multipath
- Configuring EIGRP MPLS VPN PE-CE Site of Origin
- Configuring Ethernet-over-MPLS and Pseudowire Redundancy
- Configuring IPv6 Provider Edge over MPLS (6PE)
- Configuring IPv6 VPN Provider Edge over MPLS (6VPE)
- Configuring MPLS Layer 3 VPN
- Configuring MPLS QoS
- Configuring MPLS Static Labels
- Configuring Virtual Private LAN Service (VPLS) and VPLS BGP-Based Autodiscovery
- Configuring MPLS VPN Route Target Rewrite
- Configuring Multicast Virtual Private Network
Multiprotocol Label Switching (MPLS) Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
- Updated:
- August 9, 2017
Chapter: MPLS QoS: Classifying and Marking EXP
- Classifying and Marking MPLS EXP
- Finding Feature Information
- Prerequisites for Classifying and Marking MPLS EXP
- Restrictions for Classifying and Marking MPLS EXP
- Information About Classifying and Marking MPLS EXP
- How to Classify and Mark MPLS EXP
- Configuration Examples for Classifying and Marking MPLS EXP
- Additional References
- Feature Information for QoS MPLS EXP
MPLS QoS: Classifying and Marking EXP
Classifying and Marking MPLS EXP
The QoS EXP Matching feature allows you to classify and mark network traffic by modifying the Multiprotocol Label Switching (MPLS) experimental bits (EXP) field. This module contains conceptual information and the configuration tasks for classifying and marking network traffic using the MPLS EXP field.
- Finding Feature Information
- Prerequisites for Classifying and Marking MPLS EXP
- Restrictions for Classifying and Marking MPLS EXP
- Information About Classifying and Marking MPLS EXP
- How to Classify and Mark MPLS EXP
- Configuration Examples for Classifying and Marking MPLS EXP
- Additional References
- Feature Information for QoS MPLS EXP
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Classifying and Marking MPLS EXP
Restrictions for Classifying and Marking MPLS EXP
-
MPLS classification and marking can only occur in an operational MPLS Network.
-
MPLS EXP classification and marking is supported only on MPLS enabled interfaces or MPLS traffic on other interfaces.
-
If a packet is classified by IP type of service (ToS) or class of service (CoS) at ingress, it cannot be reclassified by MPLS EXP at egress (imposition case). However, if a packet is classified by MPLS at ingress it can be reclassified by IP ToS, CoS, or Quality of Service (QoS) group at egress (disposition case).
-
To apply QoS on traffic across protocol boundaries, use QoS-group. You can classify and assign ingress traffic to the QoS-group. Thereafter, you can the QoS-group at egress to classify and apply QoS.
-
If a packet is encapsulated in MPLS, the MPLS payload cannot be checked for other protocols such as IP for classification or marking. Only MPLS EXP marking affects packets encapsulated by MPLS.
Information About Classifying and Marking MPLS EXP
- Classifying and Marking MPLS EXP Overview
- MPLS Experimental Field
- Benefits of MPLS EXP Classification and Marking
Classifying and Marking MPLS EXP Overview
The QoS EXP Matching feature allows you to organize network traffic by setting values for the MPLS EXP field in MPLS packets. By choosing different values for the MPLS EXP field, you can mark packets so that packets have the priority that they require during periods of congestion. Setting the MPLS EXP value allows you to:
- Classify traffic
The classification process selects the traffic to be marked. Classification accomplishes this by partitioning traffic into multiple priority levels, or classes of service. Traffic classification is the primary component of class-based QoS provisioning. For more information, see the “Classifying Network Traffic” module.
- Police and mark traffic
Policing causes traffic that exceeds the configured rate to be discarded or marked to a different drop level. Marking traffic is a way to identify packet flows to differentiate them. Packet marking allows you to partition your network into multiple priority levels or classes of service. For more information, see the “Marking Network Traffic” module.
MPLS Experimental Field
The MPLS experimental bits (EXP) field is a 3-bit field in the MPLS header that you can use to define the QoS treatment (per-hop behavior) that a node should give to a packet. In an IP network, the DiffServ Code Point (DSCP) (a 6-bit field) defines a class and drop precedence. The EXP bits can be used to carry some of the information encoded in the IP DSCP and can also be used to encode the dropping precedence.
By default, Cisco IOS Software copies the three most significant bits of the DSCP or the IP precedence of the IP packet to the EXP field in the MPLS header. This action happens when the MPLS header is initially imposed on the IP packet. However, you can also set the EXP field by defining a mapping between the DSCP or IP precedence and the EXP bits. This mapping is configured using the set mpls experimental or police commands. For more information, see the “How to Classify and Mark MPLS EXP” section.
You can perform MPLS EXP marking operations using table-maps. It is recommended to assign QoS-group to a different class of traffic in ingress policy and translate QoS-group to DSCP and EXP markings in egress policy using table-map.
Benefits of MPLS EXP Classification and Marking
If a service provider does not want to modify the value of the IP precedence field in packets transported through the network, they can use the MPLS EXP field value to classify and mark IP packets.
By choosing different values for the MPLS EXP field, you can mark critical packets so that those packets have priority if network congestion occurs.
How to Classify and Mark MPLS EXP
- Classifying MPLS Encapsulated Packets
- Marking MPLS EXP on the Outermost Label
- Marking MPLS EXP on Label Switched Packets
- Configuring Conditional Marking
Classifying MPLS Encapsulated Packets
You can use the match mpls experimental topmost command to define traffic classes based on the packet EXP values, inside the MPLS domain. You can use these classes to define services policies to mark the EXP traffic using the police command.
Marking MPLS EXP on the Outermost Label
Perform this task to set the value of the MPLS EXP field on imposed label entries.
In typical configurations, marking MPLS packets at imposition is used with ingress classification on IP ToS or CoS fields.
 Note | For IP imposition marking, the IP precedence value is copied to the MPLS EXP value by default. |
Note | The set mpls experimental imposition command works only on packets that have new or additional MPLS labels added to them. |
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable
Example: Switch> enable |
Enables privileged EXEC mode. |
| Step 2 |
configure
terminal
Example: Switch# configure terminal |
Enters global configuration mode. |
| Step 3 |
policy-map
policy-map-name
Example: Switch(config)# policy-map mark-up-exp-2 |
Specifies the name of the policy map to be created and enters policy-map configuration mode. |
| Step 4 |
class
class-map-name
Example: Switch(config-pmap)# class prec012 |
Creates a class map to be used for matching traffic to a specified class, and enters class-map configuration mode. |
| Step 5 |
set mpls experimental imposition
mpls-exp-value
Example: Switch(config-pmap-c)# set mpls experimental imposition 2 |
Sets the value of the MPLS EXP field on all imposed label entries. |
| Step 6 |
end
Example: Switch(config-pmap-c)# end |
(Optional) Returns to privileged EXEC mode. |
Marking MPLS EXP on Label Switched Packets
Perform this task to set the MPLS EXP field on label switched packets.
Note | The set mpls experimental topmost command marks EXP for the outermost label of MPLS traffic. Due to this marking at ingress policy, the egress policy must include classification based on the MPLS EXP values. |
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable
Example: Switch> enable |
Enables privileged EXEC mode. |
| Step 2 |
configure
terminal
Example: Switch# configure terminal |
Enters global configuration mode. |
| Step 3 |
policy-map
policy-map-name
Example: Switch(config)# policy-map mark-up-exp-2 |
Specifies the name of the policy map to be created and enters policy-map configuration mode. |
| Step 4 |
class
class-map-name
Example: Switch(config-pmap)# class-map exp012 |
Creates a class map to be used for matching traffic to a specified class, and enters class-map configuration mode. |
| Step 5 |
set mpls experimental topmost
mpls-exp-value
Example: Switch(config-pmap-c)# set mpls experimental topmost 2 |
Sets the MPLS EXP field value in the topmost label on the output interface. |
| Step 6 |
end
Example: Switch(config-pmap-c)# end |
(Optional) Returns to privileged EXEC mode. |
Configuring Conditional Marking
To conditionally set the value of the MPLS EXP field on all imposed label, perform the following task:
Note | The set-mpls-exp-topmost-transmit action affects MPLS encapsulated packets only. The set-mpls-exp-imposition-transmit action affects any new labels that are added to the packet. |
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable
Example: Switch> enable |
Enables privileged EXEC mode. |
| Step 2 |
configure
terminal
Example: Switch# configure terminal |
Enters global configuration mode. |
| Step 3 |
policy-map
policy-map-name
Example: Switch(config)# policy-map ip2tag |
Specifies the name of the policy map to be created and enters policy-map configuration mode. |
| Step 4 |
class
class-map-name
Example: Switch(config-pmap)# class iptcp |
Creates a class map to be used for matching traffic to a specified class, and enters policy-map class configuration mode. |
| Step 5 |
police cir
bps
bc pir
bps
be
Example: Switch(config-pmap-c)# police cir 1000000 pir 2000000 |
Defines a policer for classified traffic and enters policy-map class police configuration mode. |
| Step 6 |
conform-action
transmit
Example: Switch(config-pmap-c-police)# conform-action transmit 3 |
Defines the action to take on packets that conform to the values specified by the policer. |
| Step 7 |
exceed-action
set-mpls-exp-topmost-transmit dscp table
dscp-table-value
Example: Switch(config-pmap-c-police)# exceed-action set-mpls-exp-topmost-transmit dscp table dscp2exp |
Defines the action to take on packets that exceed the values specified by the policer. |
| Step 8 |
violate-action
drop
Example: Switch(config-pmap-c-police)# violate-action drop |
Defines the action to take on packets whose rate exceeds the peak information rate (pir) and is outside the bc and be ranges. |
| Step 9 |
end
Example: Switch(config-pmap-c-police)# end |
(Optional) Returns to privileged EXEC mode. |
Configuration Examples for Classifying and Marking MPLS EXP
- Example: Classifying MPLS Encapsulated Packets
- Marking MPLS EXP on the Outermost Label
- Example: Marking MPLS EXP on Label Switched Packets
- Example: Configuring Conditional Marking
Example: Classifying MPLS Encapsulated Packets
Defining an MPLS EXP Class Map
The following example defines a class map named exp3 that matches packets that contains MPLS experimental value 3:
Switch(config)# class-map exp3 Switch(config-cmap)# match mpls experimental topmost 3 Switch(config-cmap)# exit
Defining a Policy Map and Applying the Policy Map to an Ingress Interface
The following example uses the class map created in the example above to define a policy map. This example also applies the policy map to a physical interface for ingress traffic.
Switch(config)# policy-map change-exp-3-to-2 Switch(config-pmap)# class exp3 Switch(config-pmap-c)# set mpls experimental topmost 2 Switch(config-pmap)# exit Switch(config)# interface GigabitEthernet 0/0/0 Switch(config-if)# service-policy input change-exp-3-to-2 Switch(config-if)# exit
Defining a Policy Map and Applying the Policy Map to an Egress Interface
The following example uses the class map created in the example above to define a policy map. This example also applies the policy map to a physical interface for egress traffic.
Switch(config)# policy-map WAN-out Switch(config-pmap)# class exp3 Switch(config-pmap-c)# shape average 10000000 Switch(config-pmap-c)# exit Switch(config-pmap)# exit Switch(config)# interface GigabitEthernet 0/0/0 Switch(config-if)# service-policy output WAN-out Switch(config-if)# exit
Marking MPLS EXP on the Outermost Label
Perform this task to set the value of the MPLS EXP field on imposed label entries.
In typical configurations, marking MPLS packets at imposition is used with ingress classification on IP ToS or CoS fields.
Note | For IP imposition marking, the IP precedence value is copied to the MPLS EXP value by default. |
Note | The set mpls experimental imposition command works only on packets that have new or additional MPLS labels added to them. |
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable
Example: Switch> enable |
Enables privileged EXEC mode. |
| Step 2 |
configure
terminal
Example: Switch# configure terminal |
Enters global configuration mode. |
| Step 3 |
policy-map
policy-map-name
Example: Switch(config)# policy-map mark-up-exp-2 |
Specifies the name of the policy map to be created and enters policy-map configuration mode. |
| Step 4 |
class
class-map-name
Example: Switch(config-pmap)# class prec012 |
Creates a class map to be used for matching traffic to a specified class, and enters class-map configuration mode. |
| Step 5 |
set mpls experimental imposition
mpls-exp-value
Example: Switch(config-pmap-c)# set mpls experimental imposition 2 |
Sets the value of the MPLS EXP field on all imposed label entries. |
| Step 6 |
end
Example: Switch(config-pmap-c)# end |
(Optional) Returns to privileged EXEC mode. |
Example: Marking MPLS EXP on Label Switched Packets
Defining an MPLS EXP Label Switched Packets Policy Map
The following example defines a policy map that sets the MPLS EXP topmost value to 2 according to the MPLS EXP value of the forwarded packet:
Switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Switch(config)# class-map exp012 Switch(config-cmap)# match mpls experimental topmost 0 1 2 Switch(config-cmap)# exit Switch(config-cmap)# policy-map mark-up-exp-2 Switch(config-pmap)# class exp012 Switch(config-pmap-c)# set mpls experimental topmost 2 Switch(config-pmap-c)# exit Switch(config-pmap)# exit
Applying the MPLS EXP Label Switched Packets Policy Map to a Main Interface
The following example shows how to apply the policy map to a main interface:
Switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Switch(config)# interface GigabitEthernet 0/0/0 Switch(config-if)# service-policy input mark-up-exp-2 Switch(config-if)# exit
Example: Configuring Conditional Marking
The example in this section creates a policer for the iptcp class, which is part of the ip2tag policy map, and attaches the policy map to the Gigabit Ethernet interface.
Switch(config)# policy-map ip2tag Switch(config-pmap)# class iptcp Switch(config-pmap-c)# police cir 1000000 pir 2000000 Switch(config-pmap-c-police)# conform-action transmit Switch(config-pmap-c-police)# exceed-action set-mpls-exp-imposition-transmit 2 Switch(config-pmap-c-police)# violate-action drop Switch(config-pmap-c-police)# exit Switch(config-pmap-c)# exit Switch(config-pmap)# exit Switch(config)# interface GigabitEthernet 0/0/1 Switch(config-if)# service-policy input ip2tag
Additional References
Related Documents
|
Related Topic |
Document Title |
|---|---|
|
Cisco IOS commands |
|
|
QoS commands |
Cisco IOS Quality of Service Solutions Command Reference |
Standards and RFCs
|
Standard/RFC |
Title |
|---|---|
|
No new or modified standards are supported, and support for existing standards 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. |
Feature Information for QoS MPLS EXP
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.|
Release |
Modification |
|---|---|
|
Cisco IOS XE Everest 16.5.1a |
This feature was introduced. |
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