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VRF Aware MPLS Static Labels
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VRF Aware MPLS Static Labels

Table Of Contents

VRF Aware MPLS Static Labels

Contents

Prerequisites for VRF Aware MPLS Static Labels

Restrictions for VRF Aware MPLS Static Labels

Information About VRF Aware MPLS Static Labels

Carrier Supporting Carrier

Static Bindings Between Labels and IPv4 Prefixes

VRF Aware Static Labels Can be Used at the VPN Edge

How to Configure VRF Aware MPLS Static Labels

Configuring MPLS Static Label Range

Verifying MPLS Static Label Range

Configuring MPLS Static Bindings

Verifying MPLS Static Bindings

Configuration Examples for VRF Aware MPLS Static Labels

Configuring MPLS Static Labels Range: Example

Verifying MPLS Static Labels Range: Example

Configuring MPLS Static Bindings: Example

Verifying MPLS Static Bindings: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

debug mpls static binding

mpls static binding ipv4 vrf

show mpls static binding ipv4 vrf

Glossary


VRF Aware MPLS Static Labels

The VRF Aware Cisco Multiprotocol Label Switching (MPLS) Static Labels feature allows MPLS static labels to be used for VPN routing and forwarding (VRF) traffic.

When static labels software is not vrf-aware, it can only be used for the following purposes:

•Configure MPLS forwarding table entries for the global routing table

•Assign label values to forwarding equivalence classes (FECs) learned by the Label Distribution Protocol (LDP) for the global routing table

Those limitations mean that in MPLS virtual private network (VPN) environments, the software can be used only in the provider core.

The VRF Aware MPLS Static Labels feature provides the following benefits:

•Static labels can be used at the VPN edge.

•Static bindings between labels and IPv4 prefixes can be configured statically.

Note This feature is supported only in carrier supporting carrier (CSC).

Feature History for the VRF Aware MPLS Static Labels Feature

Release
Modification

12.0(23)S

MPLS Static labels were introduced, but they only supported global routing tables.

12.0(26)S

This feature was introduced. Static labels can be used for VRF traffic at the VPN edge.

12.3(14)T

This feature was integrated into Cisco IOS Release 12.3(14)T.


Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

Contents

• Prerequisites for VRF Aware MPLS Static Labels

• Restrictions for VRF Aware MPLS Static Labels

• Information About VRF Aware MPLS Static Labels

• How to Configure VRF Aware MPLS Static Labels

• Configuration Examples for VRF Aware MPLS Static Labels

• Additional References

• Command Reference

• Glossary

Prerequisites for VRF Aware MPLS Static Labels

•MPLS is enabled globally on each label switching router (LSR).

•Cisco Express Forwarding (CEF) is enabled on the LSRs.

•CSC is enabled.

Restrictions for VRF Aware MPLS Static Labels

•The Cisco IOS software must support MPLS VPNs.

•The provider network must have MPLS Label Distribution Protocol (LDP) installed and running.

Information About VRF Aware MPLS Static Labels

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

• Carrier Supporting Carrier

• Static Bindings Between Labels and IPv4 Prefixes

• VRF Aware Static Labels Can be Used at the VPN Edge

Carrier Supporting Carrier

Carrier supporting carrier (CSC) is a situation where one service provider allows another service provider to use a segment of its backbone network. The service provider that provides the segment of the backbone network to the other provider is called the backbone carrier. The service provider that uses the segment of the backbone network is called the customer carrier. VRF aware MPLS static labels are supported only in a CSC environment.

Static Bindings Between Labels and IPv4 Prefixes

A static binding is the assignment of a particular label to an IPv4 prefix. With a regular binding, labels are randomly assigned.

Static bindings between labels and IPv4 prefixes can be configured to support MPLS hop-by-hop forwarding through neighbor routers that do not implement LDP label distribution.

VRF Aware Static Labels Can be Used at the VPN Edge

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 CSC feature, the backbone carrier can assign specific labels to forwarding equivalence classes (FECs) it advertises to the edge routers of customer carriers. This makes it easier to monitor backbone traffic coming from particular customer carriers for billing or other purposes.

How to Configure VRF Aware MPLS Static Labels

This section contains the following procedures:

• Configuring MPLS Static Label Range (required)

• Verifying MPLS Static Label Range (optional)

• Configuring MPLS Static Bindings (required)

• Verifying MPLS Static Bindings (optional)

Configuring MPLS Static Label Range

SUMMARY STEPS

1. enable

2. configure terminal

3. mpls label range min-label max-label [static min-static-label max-static-label]

4. 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 

mpls label range min-label max-label
[static min-static-label max-static-label]

Example:

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

Specifies a range of labels for use with the MPLS Static Labels feature. The default is that no labels are reserved for static assignment.

Step 4 

end

Example:

Router(config)# end

Exits the current mode and enters privileged EXEC mode.

Verifying MPLS Static Label Range

To verify the MPLS static label range, perform the following steps.

SUMMARY STEPS

1. show mpls label range

DETAILED STEPS

Step 1 show mpls label range

Use this command to display information about the range of values for local labels, including those available for static assignment. 

Router# show mpls label range

Configuring MPLS Static Bindings

SUMMARY STEPS

1. enable

2. configure terminal

3. mpls static binding ipv4 vrf vpn-name prefix mask [[input] label]

4. end

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]

Example: 
Router(config)# mpls static binding ipv4 vrf 
vpn100 130.66.0.0.255.255.0.0 input 17

Binds a prefix to a local label.

Bindings specified are installed automatically in the MPLS forwarding table as routing demands.

Step 4 

end

Example:

Router(config)# end

Exits the current mode and enters privileged EXEC mode.

Verifying MPLS Static Bindings

To verify MPLS static bindings, perform the following steps.

SUMMARY STEPS

1. show mpls static binding ipv4 vrf vpn-name

DETAILED STEPS

Step 1 show mpls static binding ipv4 vrf vpn-name

Use this command to display the configured static bindings. 

Router# show mpls static binding ipv4 vrf vpn100

Troubleshooting Tips

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

Configuration Examples for VRF Aware MPLS Static Labels

This section provides the following configuration examples:

• Configuring MPLS Static Labels Range: Example

• Verifying MPLS Static Labels Range: Example

• Configuring MPLS Static Bindings: Example

• Verifying MPLS Static Bindings: Example

Configuring MPLS Static Labels Range: 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# configure terminal


Enter configuration commands, one per line.  End with CNTL/Z.

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


% Label range changes take effect at the next reload.

Router(config)# end

Verifying MPLS Static Labels Range: Example

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 Bindings: 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# configure terminal


Enter configuration commands, one per line.  End with CNTL/Z.


Router(config)# mpls static binding ipv4 vrf vpn100 107.0.0.0 255.0.0.0 55


Router(config)# mpls static binding ipv4 vrf vpn100 130.66.0.0 255.255.0.0 input 17


Router(config)# end

Verifying MPLS Static Bindings: Example

In the following output, the show mpls static binding ipv4 command displays the configured static bindings: 

Router# show mpls static binding ipv4 vrf vpn100 


59.0.0.0/8: Incoming label: none;

  Outgoing labels:

     165.13.0.8           explicit-null

107.0.0.0/8: Incoming label: 55 (in LIB)

  Outgoing labels:

     166.0.0.66              2607

130.66.0.0/16: Incoming label: 17 (in LIB)

  Outgoing labels:  None

Additional References

The following sections provide references related to VRF Aware MPLS Static Labels.

Related Documents

Related Topic
Document Title

Carrier Supporting Carrier

MPLS VPN Carrier Supporting Carrier, Release 12.2(8)T

VRF

Cisco IOS Switching Services Configuration Guide, Release 12.0, Part 3

VPN

Cisco IOS Switching Services Configuration Guide, Release 12.0, Part 3


Standards

Standards
Title

None

—


MIBs

MIBs
MIBs Link

None

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

RFCs
Title

None

—


Technical Assistance

Description
Link

Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/public/support/tac/home.shtml


Command Reference

This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.

• debug mpls static binding

• mpls static binding ipv4 vrf

• show mpls static binding ipv4 vrf

debug mpls static binding

To display information related to static binding events, use the debug mpls static binding command in privileged EXEC mode. To disable debugging output, use the no form of this command.

debug mpls static binding [vrf vpn-name]

no debug mpls static binding [vrf vpn-name]

Syntax Description

vrf vpn-name

Displays information only for the specified VPN routing and forwarding instance (vpn-name).


Defaults

This command is disabled by default.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.0(23)S

This command was introduced.

12.0(26)S

This command was incorporated into Release 12.0(26)S. You can enable debug only for a VRF.

12.3(14)T

This command was integrated into Cisco IOS Release 12.3(14)T.


Usage Guidelines

Use the debug mpls static binding command to troubleshoot problems related to MPLS static labels or VRF aware MPLS static labels. If you specify the vrf keyword, debug is enabled only for a specified VRF.

Examples

The following is sample output from the debug mpls static binding command: 

Router# debug mpls static binding vrf vpn100


MPLS Static label bindings debugging is on


00:15:13: mpls: Add remote static binding: 59.0.0.0/8; label 0; nexthop 165.13.0.8:0

00:15:13: mpls: Add static label binding for 59.0.0.0/8

00:15:13: mpls: Add static label binding for 107.0.0.0/8

00:15:13: mpls: Add remote static binding: 107.0.0.0/8; label 2607; nexthop 166.0.0.66:0

00:15:13: mpls: Add static label binding for 130.66.0.0/16

00:15:18: mpls: Periodic static label adjust

00:15:18: mpls: Static label update: 59.0.0.0/8

00:15:18:       Add remote label: nexthop: 165.13.0.8:0; label: 0

00:15:18: mpls: Periodic static label adjust

00:15:18: mpls: Static label update: 107.0.0.0/8

00:15:18:       Waiting for withdrawal of dynamic local label 55

00:15:18:       Add remote label: nexthop: 166.0.0.66:0; label: 2607

00:15:18: mpls: Periodic static label adjust

00:15:18: mpls: Static label update: 130.66.0.0/16

00:15:18:       Waiting for withdrawal of dynamic local label 17

00:15:28: mpls: Periodic static label adjust

00:15:28: mpls: Periodic static label adjust

00:15:28: mpls: Static label update: 107.0.0.0/8

00:15:28:       Local label 55 added to tib

00:15:28:       Signal route tag change, in label 55;out label 8388611; nh 199.44.44.77

00:15:28: mpls: Periodic static label adjust

00:15:28: mpls: Static label update: 130.66.0.0/16

00:15:28:       Local label 17 added to tib

00:15:28:       Signal route tag change, in label 17;out label 8388611; nh 199.44.44.66

00:15:38: mpls: Periodic static label adjust

00:15:38: mpls: Periodic static label adjust

00:15:38: mpls: Periodic static label adjust

Related Commands

Command
Description

mpls static binding ipv4 vrf

Binds a prefix to a local label.

show debug

Displays active debug output.


mpls static binding ipv4 vrf

To bind a prefix to a local label, use the mpls static binding ipv4 vrf command in global configuration mode. To remove static prefix/label bindings, use the no form of this command.

mpls static binding ipv4 vrf vpn-name prefix mask [[input] label]

no mpls static binding ipv4 vrf vpn-name prefix mask [[input] label]

Syntax Description

vpn-name

Specifies the VPN routing and forwarding instance (vpn-name).

prefix mask label

Binds a prefix or a mask to a local label.

Note These arguments are optional for the no form of the command.

input label

(Optional) Binds the specified label to the prefix/mask as a local (incoming) label.


Defaults

Label bindings are dynamically assigned.

Command Modes

Global configuration

Command History

Release
Modification

12.0(26)S

This command was introduced.

12.3(14)T

This command was integrated into Cisco IOS Release 12.3(14)T.


Usage Guidelines

The vrf keyword can be used only when you configure input labels.

Depending on how you configure VRF aware MPLS static labels, static labels are advertised one of the following ways:

•By Label Distribution Protocol (LDP) between provider edge (PE) and customer edge (CE) routers within a virtual routing and forwarding (VRF)

•In VPNv4 Border Gateway Protocol (BGP) in the service provider's backbone

If you do not specify the input keyword, an input (local) label is assumed.

The no form of the command functions as follows:

•Omitting the prefix and the subsequent parameters removes all static bindings.

•Specifying the prefix and mask but no other parameters removes all static bindings for that prefix or mask.

Examples

The following example binds a prefix to local label 17: 

Router(config)# mpls static binding ipv4 vrf vpn100 130.66.0.0 255 255.0.0 input 17

Related Commands

Command
Description

show mpls static binding ipv4 vrf

Displays configured static bindings.


show mpls static binding ipv4 vrf

To display configured static bindings, use the show mpls static binding ipv4 vrf command in privileged EXEC mode.

show mpls static binding ipv4 vrf [vpn-name] [prefix {mask-length | mask}] local

Syntax Description

vpn-name

(Optional) Displays the static label bindings for the specified VPN routing and forwarding instance.

prefix {mask-length | mask}

(Optional) Specifies the labels for a specific prefix.

local

Displays local (incoming) labels.


Defaults

No default behavior or values

Command Modes

Privileged EXEC

Command History

Release
Modification

12.0(26)S

This command was introduced.

12.3(14)T

This command was integrated into Cisco IOS Release 12.3(14)T.


Examples

The following example displays statically assigned label bindings: 

Router# show mpls static binding ipv4 vrf vpn100


2.2.2.2/32: (vrf: vpn100) Incoming label: 100020 

Outgoing labels: None 

212.166.0.29/32: Incoming label: 100003 (in LIB) 

Outgoing labels: None

Related Commands

Command
Description

mpls static binding ipv4 vrf

Binds a prefix to a local label.


Glossary

CEF—Cisco Express Forwarding. An advanced Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns.

edge router—A router that classifies IP packets. The edge router defines the boundary of the MPLS network.

FEC—forwarding equivalence class. A collection of destinations that are mapped to an MPLS LSP.

label binding—The label value that represents a forwarding equivalence class. Each LSR informs its neighbors of the label bindings it has made. This awareness of label bindings by neighboring routers is facilitated by the following protocols:

•TDP—Used to support MPLS forwarding along normally routed paths

•Resource Reservation Protocol (RSVP)—Used to support MPLS traffic engineering

LDP—label distribution protocol. A standard protocol used by MPLS-enabled routers to assign the labels (addresses) used to forward packets.

LSP—label switched path. A configured connection between two routers, in which MPLS is used to carry packets. A path created by the concatenation of one or more label switched hops, allowing a packet to be forwarded by swapping labels from an MPLS node to another MPLS node.

LSR—label switch router. A Layer 3 router that forwards a packet based on the value of an identifier encapsulated in the packet.

static binding—The assignment of a particular label to an IPv4 prefix.

VPN—virtual private network. A secure IP-based network that shares resources on one or more physical networks. A VPN contains geographically dispersed sites that can communicate securely over a shared backbone.

VRF—VPN routing and forwarding instance. A per-Virtual Private Network (VPN) routing information repository that defines the VPN membership of a customer's site attached to the NAS. A VRF consists of an IP routing table, a derived Cisco Express Forwarding (CEF) table, a set of interfaces that use the forwarding table, and a set of rules and routing protocol parameters that control the information that is included in the routing table.

VRF-aware—For an MPLS VPN, the software can distinguish between two destinations with the same IP address using information stored in the VRF.

Note Refer to the Internetworking Terms and Acronyms for terms not included in this glossary.

Copyright © 2005 Cisco Systems, Inc. All rights reserved.