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Contents
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.
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table at the end of this module.
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.
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 Multiprotocol Label Switching (MPLS) virtual private networks (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 devices 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 devices do not implement the LDP or RSVP label distribution, but do implement an MPLS forwarding path.
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.
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 virtual private network (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 forwarding equivalence classes (FECs) learned by the Label Distribution Protocol (LDP). You can manually configure a label switched path (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.
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
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable
Example: Device> enable |
Enables privileged EXEC mode. |
Step 2 |
configure terminal
Example: Device# configure terminal |
Enters global configuration mode. |
Step 3 |
mpls static binding ipv4
prefix
mask {label |
input
label |
output
nexthop {explicit-null |
implicit-null |
label}}
Example: Device(config)# mpls static binding ipv4 10.2.2.0 255.255.255.255 input 17 |
Specifies static binding of labels to IPv4 prefixes. |
Step 4 |
exit
Example: Device(config)# exit |
Returns to privileged EXEC mode. |
Step 5 | show mpls static binding ipv4
Example: Device# show mpls static binding ipv4 |
Displays the configured static labels. |
Step 6 | show mpls forwarding-table
Example: Device# show mpls forwarding-table |
Displays the static labels used for MPLS forwarding. |
You can configure MPLS static cross connects to support MPLS LSP midpoints when neighbor devices do not implement either the Label Distribution Protocol (LDP) or Resource Reservation Protocol (RSVP) label distribution, but do implement an MPLS forwarding path.
Globally enable Multiprotocol Label Switching (MPLS) on each label switch router (LSR).
Enable Cisco Express Forwarding on each LSR.
Note |
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 or Action | Purpose | |||
---|---|---|---|---|
Step 1 |
enable
Example: Device> enable |
Enables privileged EXEC mode. | ||
Step 2 |
configure terminal
Example: Device# configure terminal |
Enters global configuration mode. | ||
Step 3 |
mpls static crossconnect
inlabel out-interface nexthop
{outlabel |
explicit-null |
implicit-null}
Example: Device(config)# mpls static crossconnect 45 pos5/0 45 explicit-null |
Specifies static cross connects.
| ||
Step 4 |
end
Example: Device(config)# end |
Returns to privileged EXEC mode. | ||
Step 5 |
show mpls static crossconnect
Example: Device# show mpls static crossconnect |
Displays the configured static cross connects. |
You can statically bind a virtual routing and forwarding (VRF)-aware label on a provider edge (PE) device 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.
Globally enable Multiprotocol Label Switching (MPLS) on each label switch router (LSR).
Enable Cisco Express Forwarding on each LSR.
Ensure the MPLS virtual private network (VPN) is configured.
Ensure that the provider network has the MPLS Label Distribution Protocol (LDP) installed and running.
Note | The MPLS LDP VRF-Aware Static Labels feature is supported only with MPLS VPN Carrier Supporting Carrier networks that use MPLS LDP. |
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
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 |
enable
Example: Device> enable |
Enables privileged EXEC mode. | ||
Step 2 |
configure terminal
Example: Device# configure terminal |
Enters global configuration mode. | ||
Step 3 |
mpls static binding ipv4 vrf
vpn-name
prefix
mask {input
label |
label}
Example: Device(config)# mpls static binding ipv4 vrf vpn100 10.2.0.0 255.255.0.0 input 17 |
Binds a prefix to a local label.
| ||
Step 4 |
exit
Example: Device(config)# exit |
Returns to privileged EXEC mode. | ||
Step 5 |
show mpls static binding ipv4 vrf
vpn-name
Example: Device(config)# show mpls static binding ipv4 vrf vpn100 |
Displays the configured MPLS static bindings. |
To display information related to static binding events, use the debug mpls static binding vrf command.
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:
Device(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:
Device# 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:
Device# 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:
Device(config)# mpls static binding ipv4 10.0.0.0 255.0.0.0 55 Device(config)# mpls static binding ipv4 10.0.0.0 255.0.0.0 output 10.0.0.66 167 Device(config)# mpls static binding ipv4 10.66.0.0 255.255.0.0 input 17 Device(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:
Device# 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 command configures static label bindings. They also configure input (local) labels for various prefixes.
Device(config)# mpls static binding ipv4 vrf vpn100 10.0.0.0 10.0.0.0 55 Device(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:
Device# 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
Related Topic |
Document Title |
---|---|
Cisco IOS commands |
|
MPLS commands |
|
MPLS VPN CSC with LDP and IGP |
“MPLS VPN Carrier Supporting Carrier Using LDP and IGP” module in the MPLS Layer 3 VPNs Inter-AS and CSC Configuration Guide |
Description |
Link |
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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.
Feature Name |
Releases |
Feature Information |
---|---|---|
MPLS LDP VRF-Aware Static Labels |
12.0(23)S 12.0(26)S 12.2(33)SRA 12.2(33)SXH 12.2(33)SB 12.3(14)T Cisco IOS XE Release 2.1 Cisco IOS XE Release 3.5S |
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 12.0(23)S, MPLS static labels were introduced, but they supported only global routing tables. The MPLS static cross connect functionality is supported in Cisco IOS Releases 12.0(23)S, 12.3(14)T, and later releases. It is not supported in Cisco IOS Release 12.4(20)T. 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. In Cisco IOS XE Release 2.1, this feature was implemented on the Cisco ASR 1000 Series Aggregation Services Routers. In Cisco IOS XE Release 3.5S, support was added for the Cisco ASR 903 Router. 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, show mpls static binding ipv4 vrf. |