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The switch must be configured as a Multiprotocol Label Switching (MPLS) provider edge (PE) or provider (P) router, which includes the configuration of a valid label protocol and underlying IP routing protocols.
MPLS classification and marking can only occur in an operational MPLS network.
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 use 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 that are encapsulated by MPLS.
The short pipe mode is not supported to transport packets through the MPLS network. You can transport packets using any one of the following modes—uniform mode or pipe mode.
MPLS classification and marking is not supported on SVI. User needs to apply the policy on either Physical or Port-channel interfaces.
This section provides detailed information about MPLS QoS.
The MPLS QoS functionality enables network administrators to provide differentiated services across an MPLS network. Network administrators can satisfy a wide range of networking requirements by specifying the CoS applicable to each transmitted IP packet. Different classes of service can be established for IP packets by setting the IP precedence bit in the header of each packet. Classification, remarking, and queuing on an MPLS network is performed over MPLS EXP bits. In the MPLS network, the packets are differentiated by the MPLS EXP field marking, and are treated accordingly, depending on the weighted early random detection (WRED) configuration.
The MPLS EXP field in MPLS packet allows you to:
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 “Classifying Network 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 “Marking Network Traffic”.
Queueing helps prevent traffic congestion. This includes priority level queueing, weighted tail drop (WTD), scheduling, shaping and weighted random early detection (WRED) features.
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.
 Note |
A policy map configured with set ip dscp is not supported on the provider edge device because the policy action for MPLS label imposition node should be based on set mpls experimental imposition value. However, a policy map with action set ip dscp is supported when both the ingress and egress interfaces are Layer 3 ports. |
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.
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.
WRED monitors network traffic to anticipate and prevent congestion at common network and internetwork bottlenecks. WRED can selectively discard lower priority traffic when an interface becomes congested. This feature can also provide differentiated performance characteristics for different classes of service.
There are two ways to transport packets through the MPLS network:
Uniform mode: Uniform mode of transferring packets operates on one layer of QoS. The Provider Edge at ingress copies the DSCP information from the incoming IP packet into the MPLS EXP bits of the imposed labels and the IP precedence bits are mapped to the MPLS EXP field . As the EXP bits travel through the core, they may or may not be modified by the intermediate devices on the network. The Provider Edge at egress copies the EXP bits to the DSCP bits of the newly exposed IP packet.
Pipe mode: Pipe mode of transferring packets operates on two layers of QoS. An underlying QoS for the data that remains unchanged when traversing the core. A per-core QoS, which is separate from that of the underlying IP packets. The DSCP information is saved and stored as the packet travels through the MPLS network. The MPLS EXP label is applied by the PE at ingress but the IP precedence bits are not stored. At egress, the original IP precedence value is preserved.
The QoS EXP Matching feature allows you to classify, mark and queue network traffic by modifying the Multiprotocol Label Switching (MPLS) experimental bits (EXP) field. 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.
This section provides information about how to configure MPLS QoS:
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.
| Command or Action | Purpose | |||
|---|---|---|---|---|
|
Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
||
|
Step 2 |
configure terminal Example: |
Enters global configuration mode. |
||
|
Step 3 |
class-map [match-all | match-any ] class-map-name Example: |
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 mpls experimental topmost mpls-exp-value Example: |
Specifies the match criteria.
|
||
|
Step 5 |
end Example: |
(Optional) Returns to privileged EXEC mode. |
Perform this task to set the value of the MPLS EXP field on imposed label entries.
Marking MPLS packets at imposition is used with ingress classification on IP ToS or CoS fields.
Note |
|
| Command or Action | Purpose | |
|---|---|---|
|
Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
|
Step 2 |
configure terminal Example: |
Enters global configuration mode. |
|
Step 3 |
policy-map policy-map-name Example: |
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-map-name Example: |
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 5 |
set mpls experimental imposition mpls-exp-value Example: |
Sets the value of the MPLS EXP field on top label. |
|
Step 6 |
end Example: |
(Optional) Returns to privileged EXEC mode. |
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. |
Perform this task to set the MPLS EXP field on label switched packets.
| Command or Action | Purpose | |
|---|---|---|
|
Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
|
Step 2 |
configure terminal Example: |
Enters global configuration mode. |
|
Step 3 |
policy-map policy-map-name Example: |
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-map-name Example: |
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 5 |
set mpls experimental topmost mpls-exp-value Example: |
Sets the MPLS EXP field value in the topmost label on the output interface. |
|
Step 6 |
end Example: |
(Optional) Returns to privileged EXEC mode. |
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: |
Enables privileged EXEC mode.
|
|
Step 2 |
configure terminal Example: |
Enters global configuration mode. |
|
Step 3 |
policy-map policy-map-name Example: |
Specifies the name of the policy map to be created and enters policy-map configuration mode.
|
|
Step 4 |
class class-map-name Example: |
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: |
Defines a policer for classified traffic and enters policy-map class police configuration mode. |
|
Step 6 |
conform-action transmit Example: |
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 exp table table-map-name Example: |
Defines the action to take on packets that exceed the values specified by the policer. |
|
Step 8 |
violate-action drop Example: |
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: |
(Optional) Returns to privileged EXEC mode. |
Perform this task to enable WRED for MPLS EXP.
| Command or Action | Purpose | |
|---|---|---|
|
Step 1 |
enable Example: |
Enables privileged EXEC mode.
|
|
Step 2 |
configure terminal Example: |
Enters global configuration mode. |
|
Step 3 |
policy-map policy-map-name Example: |
Specifies the name of the policy map to be created and enters policy-map configuration mode.
|
|
Step 4 |
class class-map-name Example: |
Creates a class map to be used for matching traffic to a specified class, and enters class-map configuration mode.
|
|
Step 5 |
bandwidth{ kbps| remainingpercentage| percentperce ntage} Example: |
Specify either the bandwidth allocated for a class belonging to a policy map or the traffic shaping. |
|
Step 6 |
random-detect{ aggregate| dscp-based| cos-based| dscp| dscp-based| exp| mpls-exp-based| prec-based| precedence| precedence-based} Example: |
Configures WRED to use the MPLS EXP value when it calculates the drop probability for the packet. |
|
Step 7 |
random-detectexpexp-valuepercentmin-threshold max-threshold Example: |
Specifies the MPLS EXP value, minimum and maximum thresholds, in percentage. |
|
Step 8 |
end Example: |
(Optional) Returns to privileged EXEC mode. |
This section provides configuration examples for MPLS QoS.
The following example shows how to define a class map named exp3 that matches packets that contains MPLS experimental value 3:
Device(config)# class-map exp3
Device(config-cmap)# match mpls experimental topmost 3
Device(config-cmap)# exit
The following example shows how to use the class map created in the example above to define a policy map. This example also shows how to applys the policy map to a physical interface for ingress traffic.
Device(config)# policy-map change-exp-3-to-2
Device(config-pmap)# class exp3
Device(config-pmap-c)# set mpls experimental topmost 2
Device(config-pmap)# exit
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# service-policy input change-exp-3-to-2
Device(config-if)# exit
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.
Device(config)# policy-map WAN-out
Device(config-pmap)# class exp3
Device(config-pmap-c)# shape average 10000000
Device(config-pmap-c)# exit
Device(config-pmap)# exit
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# service-policy output WAN-out
Device(config-if)# exit
The following example defines a policy map that sets the MPLS EXP imposition value to 2 based on the IP precedence value of the forwarded packet:
Device# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Device(config)# class-map prec012
Device(config-cmap)# match ip prec 0 1 2
Device(config-cmap)# exit
Device(config)# policy-map mark-up-exp-2
Device(config-pmap)# class prec012
Device(config-pmap-c)# set mpls experimental imposition 2
Device(config-pmap-c)# exit
Device(config-pmap)# exit
The following example applies a policy map to Gigabit Ethernet interface 0/0/0:
Device# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# service-policy input mark-up-exp-2
Device(config-if)# exit
The following example shows how to define a policy map that sets the MPLS EXP top-most value to 2 according to the MPLS EXP value of the forwarded packet:
Device# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Device(config)# class-map exp012
Device(config-cmap)# match mpls experimental topmost 0 1 2
Device(config-cmap)# exit
Device(config-cmap)# policy-map mark-up-exp-2
Device(config-pmap)# class exp012
Device(config-pmap-c)# set mpls experimental topmost 2
Device(config-pmap-c)# exit
Device(config-pmap)# exit
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.
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# service-policy input mark-up-exp-2
Device(config-if)# exit
The following example shows how to create a policer for the iptcp class, which is part of the ip2tag policy map, and attaches the policy map to the Gigabit Ethernet interface:
Device(config)# policy-map ip2tag
Device(config-pmap)# class iptcp
Device(config-pmap-c)# police cir 1000000 pir 2000000
Device(config-pmap-c-police)# conform-action transmit
Device(config-pmap-c-police)# exceed-action set-mpls-exp-imposition-transmit 2
Device(config-pmap-c-police)# violate-action drop
Device(config-pmap-c-police)# exit
Device(config-pmap-c)# exit
Device(config-pmap)# exit
Device(config)# interface GigabitEthernet 0/0/1
Device(config-if)# service-policy input ip2tag
The following example shows how to enable WRED for MPLS EXP:
Device# configure terminal
Device(config)# policy-map wred_exp
Device(config-pmap-c)# bandwidth percent 30
Device(config-pmap-c)# random-detect mpls-exp-based
Device(config-pmap-c)# random-detect exp 1 10 20
Device(config-pmap-c)# random-detect exp 2 30 40
Device(config-pmap-c)# random-detect exp 2 40 80The show policy-map policy-map-name command verifies the WRED configuration for MPLS EXP.
The following sample output displays WRED threshold labels:
Device# show policy-map wred_exp
Policy Map wred_exp
Class exp
bandwidth 30 (%)
percent-based wred, exponential weight 9
exp min-threshold max-threshold
--------------------------------------
0 - -
1 10 20
2 30 40
3 40 80
4 - -
5 - -
6 - -
7 - -
The following example shows how to enable WRED for MPLS EXP on the Cisco Catalyst 9500X Series Switches.
Device(config)#table-map exp2tc
Device(config-tablemap)#map from 0 to 0
Device(config-tablemap)#map from 1 to 1
Device(config-tablemap)#map from 2 to 2
Device(config-tablemap)#map from 3 to 3
Device(config-tablemap)#map from 4 to 4
Device(config-tablemap)#map from 5 to 5
Device(config-tablemap)#map from 6 to 6
Device(config-tablemap)#map from 7 to 7
Device(config-tablemap)#end
Device(config)#table-map exp2discard
Device(config-tablemap)#map from 0 to 0
Device(config-tablemap)#map from 1 to 0
Device(config-tablemap)#map from 2 to 0
Device(config-tablemap)#map from 3 to 0
Device(config-tablemap)#map from 4 to 0
Device(config-tablemap)#map from 5 to 1
Device(config-tablemap)#map from 6 to 1
Device(config-tablemap)#map from 7 to 1
Device(config)#exit
Device(config)#policy-map p1
Device(config-pmap)#cla
Device(config-pmap)#class class-default
Device(config-pmap-c)# set traffic-class mpls experimental imposition table exp2tc
Device(config-pmap-c)# set discard-class mpls experimental imposition table exp2discard
Device(config-pmap-c)#end
Device(config)#class-map tc7
Device(config-cmap)#match traffic-class 7
Device(config-cmap)#exit
Device(config)#policy-map type queueing p2
Device(config-pmap)#class tc7
Device(config-pmap-c)#shape average 1000000000
Device(config-pmap-c)# queue-limit 300000000 bytes
Device(config-pmap-c)# random-detect discard-class-based
Device(config-pmap-c)# random-detect discard-class 0 percent 40 90 1
Device(config-pmap-c)# random-detect discard-class 1 percent 40 90 1
Device(config-pmap-c)#end
The following example displays the running policy configuration of WRED for MPLS EXP on the Cisco Catalyst 9500X Series Switches.
Device#show running-config policy-map WRED
Building configuration...
Current configuration : 1723 bytes
!
policy-map type queueing WRED
class tc7
shape average 1000000000
queue-limit 300000000 bytes
random-detect discard-class-based
random-detect discard-class 0 percent 40 90 1
random-detect discard-class 1 percent 40 90 1
class tc6
shape average 1000000000
random-detect discard-class-based
random-detect discard-class 0 percent 50 90 1
random-detect discard-class 1 percent 20 50 1
queue-limit 300000000 bytes
class tc5
shape average 1000000000
queue-limit 300000000 bytes
random-detect discard-class-based
random-detect discard-class 0 percent 40 90 1
random-detect discard-class 1 percent 30 90 1
class tc4
shape average 1000000000
queue-limit 300000000 bytes
random-detect discard-class-based
random-detect discard-class 0 percent 30 90 1
random-detect discard-class 1 percent 20 80 1
class tc3
shape average 1000000000
queue-limit 300000000 bytes
random-detect discard-class-based
random-detect discard-class 0 percent 60 90 1
random-detect discard-class 1 percent 20 50 1
class tc2
shape average 1000000000
queue-limit 300000000 bytes
random-detect discard-class-based
random-detect discard-class 0 percent 40 90 1
random-detect discard-class 1 percent 30 90 1
class tc1
shape average 1000000000
queue-limit 300000000 bytes
random-detect discard-class-based
random-detect discard-class 0 percent 40 90 1
random-detect discard-class 1 percent 30 90 1
class class-default
shape average 1000000000
queue-limit 300000000 bytes
random-detect discard-class-based
random-detect exponential-weighting-constant 3
random-detect discard-class 0 percent 20 90 1
random-detect discard-class 1 percent 20 70 1
!
end
The following example shows how to enable Priority Queue for MPLS EXP on the Cisco Catalyst 9500X Series Switches.
Device(config)#table-map exp2tc
Device(config-tablemap)#map from 0 to 0
Device(config-tablemap)#map from 1 to 1
Device(config-tablemap)#map from 2 to 2
Device(config-tablemap)#map from 3 to 3
Device(config-tablemap)#map from 4 to 4
Device(config-tablemap)#map from 5 to 5
Device(config-tablemap)#map from 6 to 6
Device(config-tablemap)#map from 7 to 7
Device(config-tablemap)#end
Device(config)#policy-map p1
Device(config-pmap)#class class-default
Device(config-pmap-c)# set traffic-class mpls experimental imposition table exp2tc
Device(config)#policy-map type queueing p2
Device(config-pmap)#class tc7
Device(config-pmap-c)#priority level 1
The following example displays the Priority Queue for MPLS EXP on the Cisco Cisco Catalyst 9500X Series Switches.
Device#sh policy-map type queueing p2
Policy Map type queueing p2
Class tc7
priority level 1
Class tc6
priority level 2
Class tc5
Average Rate Traffic Shaping
cir 20%
interface Port-channel30
no switchport
ip address 30.30.30.1 255.255.255.0
mpls ip
bfd interval 750 min_rx 750 multiplier 3
service-policy input p1
end
interface FiftyGigE6/0/47
no switchport
ip address 31.31.31.1 255.255.255.0
mpls ip
service-policy type queueing output p2
end
Device#sh policy-map int po30 in
Port-channel30
Service-policy input: p1
Class-map: class-default (match-any)
1203656 packets
Match: any
QoS Set
traffic-class mpls experimental imposition table exp2tc
Device#sh policy-map type queueing interface fif6/0/47 out
FiftyGigE6/0/47
Service-policy queueing output: p2
queue stats for all priority classes:
Queueing
priority level 1
queue limit 96000 bytes
(total drops) 0
(bytes output) 145201
queue stats for all priority classes:
Queueing
priority level 2
queue limit 96000 bytes
(total drops) 0
(bytes output) 870
Class-map: tc7 (match-all)
1074 packets
Match: traffic-class 7
Priority: Strict,
Priority Level: 1
Class-map: tc6 (match-all)
12 packets
Match: traffic-class 6
Priority: Strict,
Priority Level: 2
Class-map: tc5 (match-all)
2183538 packets
Match: traffic-class 5
Queueing
queue limit 7500000 bytes
(total drops) 0
(bytes output) 2192272152
shape (average) cir 2000000000, bc 20000000, be 20000000
target shape rate 2000000000
Class-map: class-default (match-any)
17584359 packets
Match: any
queue limit 7500000 bytes
(total drops) 0
(bytes output) 17654601516
|
Related Topic |
Document Title |
|---|---|
|
QoS commands |
Cisco IOS Quality of Service Solutions Command Reference |
This table provides release and related information for features explained in this module.
These features are available on all releases subsequent to the one they were introduced in, unless noted otherwise.
|
Release |
Feature |
Feature Information |
|---|---|---|
|
Cisco IOS XE Everest 16.5.1a |
QoS MPLS EXP |
The QoS EXP Matching feature allows you to classify, mark and queue network traffic by modifying the Multiprotocol Label Switching (MPLS) experimental bits (EXP) field. |
|
Cisco IOS XE Amsterdam 17.3.1 |
MPLS QoS - WRED |
Introduces support for weighted random early detection (WRED) in MPLS Quality of Service (QoS). This feature configures WRED to use the MPLS experimental bits (EXP) to calculate the drop probability of a packet. |
|
Cisco IOS XE Cupertino 17.7.1 |
QoS MPLS EXP |
This feature was implemented on the C9500X-28C8D model. |
| Cisco IOS XE Dublin 17.10.1b |
QoS MPLS EXP |
This feature was implemented on the C9500X-60L4D model. |
Use Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to https://cfnng.cisco.com/.
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