MPLS LDP--VRF-Aware Static Labels
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MPLS LDP-VRF-Aware Static Labels

Table Of Contents

MPLS LDP-VRF-Aware Static Labels

Finding Feature Information

Contents

Information About MPLS LDP-VRF-Aware Static Labels

Overview of MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels

Labels Reserved for Static Assignment

How to Configure MPLS LDP-VRF-Aware Static Labels

Reserving Labels to Use for MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels

Configuring MPLS Static Labels in the MPLS VPN Provider Core

Prerequisites

Configuring MPLS Static Cross Connects

Prerequisites

Restrictions

Configuring MPLS LDP-VRF-Aware Static Labels at the Edge of the VPN

Restrictions

Prerequisites

Troubleshooting Tips

Configuration Examples for MPLS LDP-VRF-Aware Static Labels

Reserving Labels to Use for MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels: Example

Configuring MPLS Static Labels in the MPLS VPN Provider Core: Example

Configuring MPLS Static Cross Connects: Example

Configuring MPLS LDP-VRF-Aware Static Labels at the VPN Edge: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Feature Information for MPLS LDP-VRF-Aware Static Labels


MPLS LDP-VRF-Aware Static Labels


First Published: October 28, 2002
Last Updated: September 25, 2008

This document explains how to configure the MPLS LDP-VRF-Aware Static Labels feature and Multiprotocol Label Switching (MPLS) static labels. Virtual Private Network routing and forwarding (VRF)-aware static labels can be used at the edge of an MPLS Virtual Private Network (VPN), whereas MPLS static labels can be used only in the MPLS VPN provider core.

Finding Feature Information

Your software release may not support all the features documented in this module. 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 MPLS LDP-VRF-Aware Static Labels" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS 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 MPLS LDP-VRF-Aware Static Labels

How to Configure MPLS LDP-VRF-Aware Static Labels

Configuration Examples for MPLS LDP-VRF-Aware Static Labels

Additional References

Command Reference

Feature Information for MPLS LDP-VRF-Aware Static Labels

Information About MPLS LDP-VRF-Aware Static Labels

To configure and use VRF-aware static labels, you should understand the following concepts:

Overview of MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels

Labels Reserved for Static Assignment

Overview of MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels

Label switch routers (LSRs) dynamically learn the labels they should use to label-switch packets by means of the following label distribution protocols:

Label Distribution Protocol (LDP), the Internet Engineering Task Force (IETF) standard used to bind labels to network addresses

Resource Reservation Protocol (RSVP) used to distribute labels for traffic engineering (TE)

Border Gateway Protocol (BGP) used to distribute labels for MPLS VPNs

The LSR installs the dynamically learned label into its Label Forwarding Information Base (LFIB).

You can configure static labels for the following purposes:

To bind labels to IPv4 prefixes to support MPLS hop-by-hop forwarding through neighbor routers that do not implement LDP label distribution. MPLS static labels allow you to configure entries in the MPLS forwarding table and assign label values to forwarding equivalence classes (FECs) learned by LDP. You can manually configure an LSP without running an LDP between the endpoints.

To create static cross connects to support MPLS label switched path (LSP) midpoints when neighbor routers do not implement the LDP or RSVP label distribution, but do implement an MPLS forwarding path.

To statically bind a VRF-aware label on a provider edge (PE) router to a customer network prefix (VPN IPv4 prefix). VRF-aware static labels can be used with nonglobal VRF tables, so the labels can be used at the VPN edge. For example, with the Carrier Supporting Carrier (CSC) feature, the backbone carrier can assign specific labels to FECs it advertises to the edge routers of customer carriers. Then, backbone carrier can monitor backbone traffic coming from particular customer carriers for billing or other purposes. Depending on how you configure VRF-aware static labels, they are advertised one of the following ways:

By LDP between PE and customer edge (CE) routers within a VRF instance

In VPNv4 BGP in the service provider's backbone

Labels Reserved for Static Assignment

Before you can manually assign labels, you must reserve a range of labels to be used for the manual assignment. Reserving the labels ensures that the labels are not dynamically assigned. If you are running Cisco IOS Release 12.0S or an older release, you may need to reload the router for the range of labels you reserve to take effect.

How to Configure MPLS LDP-VRF-Aware Static Labels

This section contains the following tasks:

Reserving Labels to Use for MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels (required)

Configuring MPLS Static Labels in the MPLS VPN Provider Core (optional)

Configuring MPLS Static Cross Connects (optional)

Configuring MPLS LDP-VRF-Aware Static Labels at the Edge of the VPN (optional)

Reserving Labels to Use for MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels

The following procedure explains how to reserve the labels that are to be statically assigned so that the labels are not dynamically assigned.

SUMMARY STEPS

1. enable

2. configure terminal

3. mpls label range minimum-value maximum-value [static minimum-static-value maximum-static-value]

4. end

5. show mpls label range

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 

mpls label range minimum-value maximum-value
[static minimum-static-value maximum-static-value]

Example:

Router(config)# mpls label range 200 100000 static 16 199

Reserves a range of labels for static labels assignment. The default is that no labels are reserved for static assignment.

Note You might need to reload the router for the range of labels you reserve to take effect.

Step 4 

end

Example:

Router(config)# end

Exits global configuration mode.

Step 5 

show mpls label range
Example:
Router# show mpls label range

Displays information about the range of values for local labels, including those available for static assignment.

Configuring MPLS Static Labels in the MPLS VPN Provider Core

MPLS static labels allow you to configure entries in the MPLS forwarding table and assign label values to FECs learned by LDP. You can manually configure an LSP without running a label distribution protocol between the endpoints. In MPLS VPN networks, static labels can be used only in the MPLS VPN provider core.

Prerequisites

Globally enable MPLS on each LSR.

Enable Cisco Express Forwarding on each LSR.

SUMMARY STEPS

1. enable

2. configure terminal

3. mpls static binding ipv4 prefix mask {label | input label | output nexthop {explicit-null | implicit-null | label}}

4. end

5. show mpls static binding ipv4

6. show mpls forwarding-table

 
Command
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 and returns to privileged EXEC mode.

Step 3 

mpls static binding ipv4 prefix mask 
{label | input label | output nexthop 
{explicit-null | implicit-null | label}}
Example:

Router(config)# mpls static binding ipv4 10.2.2.0 255.255.255.255 input 17

Specifies static binding of labels to IPv4 prefixes.

Specified bindings are installed automatically in the MPLS forwarding table as routing demands.

Step 4 

end

Example:

Router(config)# end

Exits global configuration mode and enters privileged EXEC mode.

Step 5 

show mpls static binding ipv4

Example:

Router# show mpls static binding ipv4

Displays the configured static labels.

Step 6 

show mpls forwarding-table

Example:

Router# show mpls forwarding-table

Displays the static labels used for MPLS forwarding.

DETAILED STEPS

Configuring MPLS Static Cross Connects

You can configure MPLS static cross connects to support MPLS LSP midpoints when neighbor routers do not implement either the LDP or RSVP label distribution, but do implement an MPLS forwarding path.

Prerequisites

Globally enable MPLS on each LSR.

Enable Cisco Express Forwarding on each LSR.

Restrictions

MPLS static cross connect functionality is supported in Cisco IOS Releases 12.0(23)S and 12.3(14)T and later releases. It is not supported in Cisco IOS Release 12.4(20)T.

MPLS static cross-connect labels remain in the LFIB even if the router to which the entry points goes down.

MPLS static cross-connect mappings remain in effect even with topology changes.

SUMMARY STEPS

1. enable

2. configure terminal

3. mpls static crossconnect inlabel out-interface nexthop {outlabel | explicit-null | implicit-null}

4. end

5. show mpls static crossconnect

 
Command
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 

mpls static crossconnect inlabel 
out-interface nexthop {outlabel | 
explicit-null | implicit-null}
Example:

Router(config)# mpls static crossconnect 45 pos5/0 45 explicit-null

Specifies static cross connects.

Note The nexthop argument is required for multiaccess interfaces.

Step 4 

end

Example:

Router(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Step 5 

show mpls static crossconnect

Example:

Router# show mpls static crossconnect

Displays the configured static cross connects.

DETAILED STEPS

Configuring MPLS LDP-VRF-Aware Static Labels at the Edge of the VPN

You can statically bind a VRF-aware label on a PE router to a customer network prefix (VPN IPv4 prefix). VRF-aware static labels can be used with nonglobal VRF tables, so the labels can be used at the VPN edge.

Restrictions

The MPLS LDP-VRF-Aware Static Labels feature is supported only with MPLS VPN Carrier Supporting Carrier networks that use MPLS LDP.

Prerequisites

Globally enable MPLS on each LSR.

Enable Cisco Express Forwarding on each LSR.

Ensure the MPLS VPN is configured. See MPLS VPN Carrier Supporting Carrier Using LDP and IGP for information about configuring the VPN and VRFs.

Ensure that the provider network has MPLS LDP installed and running. See MPLS VPN Carrier Supporting Carrier Using LDP and IGP for information about configuring LDP.

SUMMARY STEPS

1. enable

2. configure terminal

3. mpls static binding ipv4 vrf vpn-name prefix mask {input label | label}

4. end

5. show mpls static binding ipv4 vrf vpn-name

DETAILED STEPS

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 

mpls static binding ipv4 vrf vpn-name prefix mask {input label | label}

Example:
Router(config)# mpls static binding ipv4 vrf 
vpn100 10.2.0.0 255.255.0.0 input 17

Binds a prefix to a local label.

Specified bindings are installed automatically in the MPLS forwarding table as routing demands.

Note You must configure the MPLS VPN and VRFs before creating VRF-aware static labels.

Step 4 

end

Example:

Router(config)# end

Exits global configuration mode and enters privileged EXEC mode.

Step 5 

show mpls static binding ipv4 vrf vpn-name

Example:

Router(config)# show mpls static binding ipv4 vrf vpn100

Displays the configured MPLS static bindings.

Troubleshooting Tips

To display information related to static binding events, use the debug mpls static binding vrf command.

Configuration Examples for MPLS LDP-VRF-Aware Static Labels

This section provides the following configuration examples:

Reserving Labels to Use for MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels: Example

Configuring MPLS Static Labels in the MPLS VPN Provider Core: Example

Configuring MPLS Static Cross Connects: Example

Configuring MPLS LDP-VRF-Aware Static Labels at the VPN Edge: Example

Reserving Labels to Use for MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels: Example

In the following example, the mpls label range command reserves a generic range of labels from 200 to 100000 and configures a static label range of 16 to 199:

Router(config)# mpls label range 200 100000 static 16 199
 
   
% Label range changes take effect at the next reload.

In this example, the output from the show mpls label range command indicates that the new label ranges do not take effect until a reload occurs:

Router# show mpls label range 
 
   
Downstream label pool: Min/Max label: 16/100000
   [Configured range for next reload: Min/Max label: 200/100000]
Range for static labels: Min/Max/Number: 16/199

In the following output, the show mpls label range command, executed after a reload, indicates that the new label ranges are in effect:

Router# show mpls label range 
 
   
Downstream label pool: Min/Max label: 200/100000
Range for static labels: Min/Max/Number: 16/199

Configuring MPLS Static Labels in the MPLS VPN Provider Core: Example

The following example configures input and output labels for several prefixes:

Router(config)# mpls static binding ipv4 10.0.0.0 255.0.0.0 55
Router(config)# mpls static binding ipv4 10.0.0.0 255.0.0.0 output 10.0.0.66 167
Router(config)# mpls static binding ipv4 10.66.0.0 255.255.0.0 input 17 
Router(config)# mpls static binding ipv4 10.66.0.0 255.255.0.0 output 10.13.0.8 
explicit-null

The show mpls static binding ipv4 command displays the configured static labels:

Router# show mpls static binding ipv4 
 
   
10.0.0.0/8: Incoming label: 55 
  Outgoing labels:
      10.0.0.66   167
10.66.0.0/24: Incoming label: 17
  Outgoing labels:
     10.13.0.8  explicit-null

Configuring MPLS Static Cross Connects: Example

In the following example, the mpls static crossconnect command configures a cross connect from incoming label 45 to outgoing label 46 on the POS interface 5/0:

Router(config)# mpls static crossconnect 45 pos5/0 46

The show mpls static crossconnect command displays information about cross connects that have been configured:

Router# show mpls static crossconnect
 
   
Local  Outgoing    Outgoing   Next Hop    
label  label       interface              
45     46          pos5/0     point2point  (in LFIB)

Configuring MPLS LDP-VRF-Aware Static Labels at the VPN Edge: Example

In the following example, the mpls static binding ipv4 vrf commands configure static label bindings. They also configure input (local) labels for various prefixes.

Router(config)# mpls static binding ipv4 vrf vpn100 10.0.0.0 10.0.0.0 55
Router(config)# mpls static binding ipv4 vrf vpn100 10.66.0.0 255.255.0.0 input 17
 
   

In the following output, the show mpls static binding ipv4 vrf command displays the configured VRF-aware static bindings:

Router# show mpls static binding ipv4 vrf vpn100 
 
   
10.0.0.0/8:   (vrf: vpn100)  Incoming label: 55
  Outgoing labels:  None
10.66.0.0/16:   (vrf: vpn100)  Incoming label: 17
  Outgoing labels:  None

Additional References

The following sections provide references related to the MPLS LDP-VRF-Aware Static Labels feature.

Related Documents

Related Topic
Document Title

MPLS VPN CSC with LDP and IGP

MPLS VPN Carrier Supporting Carrier Using LDP and IGP


Standards

Standard
Title

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


MIBs

MIB
MIBs Link

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

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


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


Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS Multiprotocol Label Switching Command Reference at http://www.cisco.com/en/US/docs/ios/mpls/command/reference/mp_book.html. For information about all Cisco IOS commands, use the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or the Cisco IOS Master Command List, All Releases, at http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html.

debug mpls static binding

mpls label range

mpls static binding ipv4

mpls static binding ipv4 vrf

show mpls label range

show mpls static binding ipv4

show mpls static binding ipv4 vrf

Feature Information for MPLS LDP-VRF-Aware Static Labels

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS 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 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.


Table 1 Feature Information for MPLS LDP-VRF-Aware Static Labels 

Feature Name
Releases
Feature Information

MPLS LDP-VRF-Aware Static Labels

12.0(23)S
12.0(26)S
12.3(14)T
12.2(33)SRA
12.2(33)SXH
12.2(33)SB

The MPLS LDP-VRF-Aware Static Labels feature explains how to configure the MPLS LDP-VRF-Aware Static Labels feature and MPLS static labels. VVRF-aware static labels can be used at the edge of an MPLS VPN, whereas MPLS static labels can be used only in the MPLS VPN provider core.

In 12.0(23)S, MPLS static labels were introduced, but they supported only global routing tables.

In 12.0(26)S, the MPLS LDP—VRF-Aware Static Labels feature was introduced, allowing MPLS static labels to be used for VRF traffic at the VPN edge.

In 12.3(14)T, this feature was integrated.

In 12.2(33)SRA, this feature was integrated.

In 12.2(33)SXH, this feature was integrated.

In 12.2(33)SB, support was added for the Cisco 10000 series router.