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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.
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 XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
•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
•Feature Information for MPLS LDP-VRF-Aware Static Labels
•Overview of MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels
•Labels Reserved for Static Assignment
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
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.
•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 LDP-VRF-Aware Static Labels at the Edge of the VPN (optional)
To reserve the labels that are to be statically assigned so that the labels are not dynamically assigned, perform the following task.
1. enable
2. configure terminal
3. mpls label range minimum-value maximum-value [static minimum-static-value maximum-static-value]
4. exit
5. show mpls label range
To configure MPLS static labels in the MPLS VPN provider core, perform the following task.
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.
•Globally enable MPLS on each LSR.
•Enable Cisco Express Forwarding on each LSR.
1. enable
2. configure terminal
3. mpls static binding ipv4 prefix mask {label | input label | output nexthop {explicit-null | implicit-null | label}}
4. exit
5. show mpls static binding ipv4
6. show mpls forwarding-table
To configure the MPLS LDP—VRF-Aware Static Labels feature at the edge of the VPN, perform the following task.
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.
•The MPLS LDP-VRF-Aware Static Labels feature is supported only with MPLS VPN Carrier Supporting Carrier networks that use MPLS LDP.
•Globally enable MPLS on each LSR.
•Enable Cisco Express Forwarding on each LSR.
•Ensure the MPLS VPN is configured.
•Ensure that the provider network has MPLS LDP installed and running.
1. enable
2. configure terminal
3. mpls static binding ipv4 vrf vpn-name prefix mask {input label | label}
4. exit
5. show mpls static binding ipv4 vrf vpn-name
To display information related to static binding events, use the debug mpls static binding vrf command.
•Example: 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 LDP-VRF-Aware Static Labels at the VPN Edge
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
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
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
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Cisco IOS commands |
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MPLS commands |
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MPLS VPN configuration information |
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
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Table 1 lists the features in this module and provides links to specific configuration information.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE 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 XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.
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MPLS LDP-VRF-Aware Static Labels |
Cisco IOS XE Release 2.1 |
The MPLS LDP-VRF-Aware Static Labels feature explains how to configure the MPLS LDP-VRF-Aware Static Labels feature and MPLS static labels. VRF-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 Cisco IOS XE Release 2.2, this feature was implemented on the Cisco ASR 1000 Series Aggregation Services Routers. The following sections provide information about this feature: •Overview of MPLS Static Labels and MPLS LDP-VRF-Aware Static Labels •Labels Reserved for Static Assignment •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 •Configuring MPLS LDP-VRF-Aware Static Labels at the Edge of the VPN The following commands were introduced or modified: 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, and show mpls static binding ipv4 vrf. |