MPLS LDP Autoconfiguration

The MPLS LDP Autoconfiguration feature enables you to globally configure Label Distribution Protocol (LDP) on every interface associated with a specified Interior Gateway Protocol (IGP) instance.

Restrictions for MPLS LDP Autoconfiguration

  • If the Label Distribution Protocol (LDP) is disabled globally, the mpls ldp autoconfig command fails and generates a console message explaining that LDP must first be enabled globally by using the mpls ip global configuration command.

  • If the mpls ldp autoconfig command is configured for an IGP instance, you cannot enter the no mpls ip global configuration command. To disable LDP, you must first issue the no mpls ldp autoconfig command.

  • For interfaces running Intermediate System-to-Intermediate System (IS-IS) processes, you can enable Multiprotocol Label Switching (MPLS) for each interface, using the router mode command mpls ldp autoconfig or the mpls ldp igp autoconfig interface configuration command.

  • You specify that the default label distribution protocol is LDP for a device or for an interface. Tag Distribution Protocol (TDP) is not supported.

  • The MPLS LDP Autoconfiguration feature is not supported on traffic engineering tunnel interfaces.

Information About MPLS LDP Autoconfiguration

MPLS LDP Autoconfiguration on OSPF and IS-IS Interfaces

The MPLS LDP Autoconfiguration feature enables you to globally enable Label Distribution Protocol (LDP) on every interface associated with an Interior Gateway Protocol (IGP) instance. This feature is supported on Open Shortest Path First (OSPF) and Intermediate System-to-Intermediate System (IS-IS) IGPs. It provides a means to block LDP from being enabled on interfaces that you do not want enabled. The goal of the MPLS LDP Autoconfiguration feature is to make configuration easier, faster, and error free.

You issue the mpls ldp autoconfig command to enable LDP on each interface that is running an OSPF or IS-IS process. If you do not want some of the interfaces to have LDP enabled, you can issue the no mpls ldp igp autoconfig command on those interfaces.

How to Configure MPLS LDP Autoconfiguration

Configuring MPLS LDP Autoconfiguration with OSPF Interfaces

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. mpls ip
  4. mpls label protocol ldp
  5. interface type number
  6. ip address prefix mask
  7. mpls ip
  8. exit
  9. router ospf process-id
  10. network ip-address wildcard-mask area area-id
  11. mpls ldp autoconfig [area area-id]
  12. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

mpls ip

Example:


Device(config)# mpls ip

Globally enables hop-by-hop forwarding.

Step 4

mpls label protocol ldp

Example:


Device(config)# mpls label protocol ldp

Specifies the Label Distribution Protocol (LDP) as the default protocol.

Step 5

interface type number

Example:


Device(config)# interface gigabitethernet 0/0/0

Specifies the interface to configure, and enters interface configuration mode.

Step 6

ip address prefix mask

Example:


Device(config-if)# ip address 10.25.0.11 255.255.255.255

Assigns an IP address to the interface.

Step 7

mpls ip

Example:


Device(config-if)# mpls ip

Enables hop-by-hop forwarding on the interface.

Step 8

exit

Example:


Device(config-if)# exit

Returns to global configuration mode.

Step 9

router ospf process-id

Example:


Device(config)# router ospf 1

Enables Open Shortest Path First (OSPF) routing, and enters router configuration mode.

Step 10

network ip-address wildcard-mask area area-id

Example:


Device(config-router)# network 10.0.0.0 0.255.255.255 area 3

Defines an interface on which OSPF runs and defines the area ID for that interface.

Step 11

mpls ldp autoconfig [area area-id]

Example:


Device(config-router)# mpls ldp autoconfig area 3

Enables the MPLS LDP Autoconfiguration feature to enable LDP on interfaces belonging to the OSPF process.

  • If no area is specified, the command applies to all interfaces associated with the OSPF process. If an area ID is specified, then only interfaces associated with that OSPF area are enabled with LDP.

Step 12

end

Example:


Device(config-router)# end

Returns to privileged EXEC mode.

Disabling MPLS LDP Autoconfiguration from Selected OSPF Interfaces

When you issue the mpls ldp autoconfig command, all the interfaces that belong to an Open Shortest Path First (OSPF) area are enabled for the Label Distribution Protocol (LDP). To remove LDP from some interfaces, use the no mpls ldp igp autoconfig command on those interfaces. The following configuration steps show how to disable LDP from some of the interfaces after they were configured with the MPLS LDP Autoconfiguration feature with the mpls ldp autoconfig command.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. no mpls ldp igp autoconfig
  5. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:


Device(config)# interface POS 3/0

Specifies the interface to configure and enters interface configuration mode.

Step 4

no mpls ldp igp autoconfig

Example:


Device(config-if)# no mpls ldp igp autoconfig

Disables LDP for that interface.

Step 5

end

Example:


Device(config-if)# end

Returns to privileged EXEC mode.

Verifying MPLS LDP Autoconfiguration with OSPF

SUMMARY STEPS

  1. enable
  2. show mpls interfaces [type number | vrf vpn-name] [all] [detail] [internal]
  3. show mpls ldp discovery [vrf vpn-name | all] [detail]

DETAILED STEPS

Step 1

enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

show mpls interfaces [type number | vrf vpn-name] [all] [detail] [internal]

Displays the method used to enable the Label Distribution Protocol (LDP) on an interface:

  • If LDP is enabled by the mpls ldp autoconfig command, the output displays:

Example:


IP labeling enabled (ldp):
   IGP config

  • If LDP is enabled by the mpls ip command, the output displays:

Example:


IP labeling enabled (ldp):
  Interface config

  • If LDP is enabled by the mpls ip command and the mpls ldp autoconfig command, the output displays:

Example:


IP labeling enabled (ldp):
  Interface config
  IGP config

The following example shows that LDP was enabled on the interface by both the mpls ip and mpls ldp autoconfig commands:

Example:

Step 3

show mpls ldp discovery [vrf vpn-name | all] [detail]

Displays how LDP was enabled on the interface. In the following example, LDP was enabled by both the mpls ip and mpls ldp autoconfig commands:

Example:

Configuring MPLS LDP Autoconfiguration with IS-IS Interfaces

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ip address prefix mask
  5. ip router isis
  6. exit
  7. mpls ip
  8. mpls label protocol ldp
  9. router isis
  10. mpls ldp autoconfig [level-1 | level-2]
  11. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:


Device(config)# interface POS 0/2

Specifies the interface to configure and enters interface configuration mode.

Step 4

ip address prefix mask

Example:


Device(config-if)# ip address 10.50.72.4 255.0.0.0

Assigns an IP address to the interface.

Step 5

ip router isis

Example:


Device(config-if)# ip router isis

Enables the Intermediate System-to-Intermediate System (IS-IS) for IP on the interface.

Step 6

exit

Example:


Device(config-if)# exit

Returns to global configuration mode.

Step 7

mpls ip

Example:


Device(config)# mpls ip

Globally enables hop-by-hop forwarding.

Step 8

mpls label protocol ldp

Example:


Device(config)# mpls label protocol ldp

Specifies the Label Distribution Protocol (LDP) as the default protocol.

Step 9

router isis

Example:


Device(config)# router isis

Enables an IS-IS process on the device and enters router configuration mode.

Step 10

mpls ldp autoconfig [level-1 | level-2]

Example:


Device(config-router)# mpls ldp autoconfig

Enables the LDP for interfaces that belong to an IS-IS process.

Step 11

end

Example:


Device(config-router)# end

Returns to privileged EXEC mode.

Disabling MPLS LDP Autoconfiguration from Selected IS-IS Interfaces

When you issue the mpls ldp autoconfig command, all the interfaces that belong to an Intermediate System-to-Intermediate System (IS-IS) process are enabled for the Label Distribution Protocol (LDP). To remove LDP from some interfaces, use the no mpls ldp igp autoconfig command on those interfaces. The following configuration steps show how to disable LDP from some of the interfaces after they were configured with the MPLS LDP Autoconfiguration feature with the mpls ldp autoconfig command.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. no mpls ldp igp autoconfig
  5. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:


Device(config)# interface POS 3/0

Specifies the interface to configure and enters interface configuration mode.

Step 4

no mpls ldp igp autoconfig

Example:


Device(config-if)# no mpls ldp igp autoconfig

Disables LDP for that interface.

Step 5

end

Example:


Device(config-if)# end

Returns to privileged EXEC mode.

Verifying MPLS LDP Autoconfiguration with IS-IS

SUMMARY STEPS

  1. enable
  2. show isis mpls ldp

DETAILED STEPS

Step 1

enable

Enables privileged EXEC mode.

Step 2

show isis mpls ldp

Shows that the Intermediate System-to-Intermediate System (IS-IS) is configured on the interface and that the Label Distribution Protocol (LDP) is enabled:

Example:


Device# show isis mpls ldp

Interface: POS0/2; ISIS tag null enabled
 ISIS is UP on interface
 AUTOCONFIG Information :
   LDP enabled: YES
 SYNC Information :
   Required: NO

The output shows:

  • IS-IS is up.

  • LDP is enabled.

If the MPLS LDP Autoconfiguration feature is not enabled on an interface, the output looks like the following:

Example:


Interface: Ethernet0; ISIS tag null enabled
 ISIS is UP on interface
 AUTOCONFIG Information :
   LDP enabled: NO
 SYNC Information :
   Required: NO

Troubleshooting Tips

You can use the debug mpls ldp autoconfig command to display events that are related to the MPLS LDP Autoconfiguration feature.

Configuration Examples for MPLS LDP Autoconfiguration

Example: MPLS LDP Autoconfiguration with OSPF

The following configuration commands enable the Label Distribution Protocol (LDP) for Open Shortest Path First (OSPF) process 1 area 3. The mpls ldp autoconfig area 3 command and the OSPF network commands enable LDP on POS interfaces 0/0, 0/1, and 1/1. The no mpls ldp igp autoconfig command on POS interface 1/0 prevents LDP from being enabled on POS interface 1/0, even though OSPF is enabled for that interface. 


configure terminal
 interface POS 0/0
  ip address 10.0.0.1 255.0.0.0
!
 interface POS 0/1
  ip address 10.0.1.1 255.0.0.1
!
 interface POS 1/1
  ip address 10.1.1.1 255.255.0.0
!
 interface POS 1/0
  ip address 10.1.0.1 0.1.0.255
  exit
!
 router ospf 1
  network 10.0.0.0 0.0.255.255 area 3
  network 10.1.0.0 0.0.255.255 area 3
  mpls ldp autoconfig area 3
  end
 interface POS 1/0
  no mpls ldp igp autoconfig

Example: MPLS LDP Autoconfiguration with IS-IS

The following example shows the configuration of the MPLS LDP Autoconfiguration feature on POS0/2 and 0/3 interfaces, which are running Intermediate System-to-Intermediate System (IS-IS) processes: 


configure terminal
 interface POS 0/2
  ip address 10.0.0.1 255.0.0.1
  ip router isis
!
 interface POS 0/3
  ip address 10.1.1.1 255.0.1.0
  ip router isis
  exit
mpls ip
mpls label protocol ldp
router isis
mpls ldp autoconfig

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

MPLS commands

Cisco IOS Multiprotocol Label Switching Command Reference

MPLS LDP

“MPLS Label Distribution Protocol” module in the MPLS Label Distribution Protocol Configuration Guide

The MPLS LDP IGP Synchronization feature

“MPLS LDP IGP Synchronization” module in the MPLS Label Distribution Protocol Configuration Guide

The MPLS LDP Session Protection feature

“MPLS LDP Session Protection” module in the MPLS Label Distribution Protocol Configuration Guide

Configuring integrated IS-IS

“Integrated IS-IS Routing Protocol Overview” module in the IP Routing: ISIS Configuration Guide

MIBs

MIB

MIBs Link

MPLS LDP MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mib

RFCs

RFC

Title

RFC 3036

LDP Specification

RFC 3037

LDP Applicability

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 MPLS LDP Autoconfiguration

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.