Table Of Contents
MPLS High Availability: Command Changes
First Published: August 11, 2004Last Updated: August 21, 2007
This feature module details changes to commands that are required to support updates to the Multiprotocol Label Switching (MPLS) High Availability (HA) feature.
In Cisco IOS Releases 12.2(25)S, 12.2(28)SB, 12.2(33)SRA, and 12.2(33)SXH, the MPLS control plane software is enhanced to work in MPLS HA environments. The changes made the control plane software more modular, which helps MPLS support MPLS HA applications. Some of the control plane software changes also made MPLS more scalable and flexible.
Changes to the MPLS Forwarding Infrastructure (MFI) and the Cisco Express Forwarding component introduced new commands and changed other existing commands. MFI replaced the Label Forwarding Information Base (LFIB) and is responsible for managing MPLS data structures used for forwarding.
Finding Feature Information in This Module
Your Cisco IOS software release may not support all of the features documented in this module. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for MPLS High Availability: Command Changes" section.
Finding Support Information for Platforms and Cisco IOS and Catalyst OS Software Images
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.
Information About MPLS High Availability: Command Changes
Before using MPLS High Availability features, you should understand the following concepts:
MPLS Replacement Commands for Tag-Switching Commands
Starting with Cisco IOS Releases 12.2(25)S, 12.2(28)SB, 12.2(33)SRA and 12.2(33)SXH, all tag-switching commands are obsoleted and are replaced with MPLS command versions. When you enter an obsolte tag-switching command, such as tag-switching ip, you receive the following message:% Command accepted but obsolete, unreleased, or unsupported; see documentation
Use the MPLS version of the command instead, such as mpls ip.
Support for the tag-switching versions of commands will cease in a future release.
Configuration files that use the tag-switching version of the commands continue to operate. However, running configurations will display the new MPLS versions of the commands.
New Command Defaults
Starting with Cisco IOS Releases 12.2(25)S, 12.2(28)SB, 12.2(33)SRA and 12.2(33)SXH, Label Distribution Protocol (LDP) is the default protocol. In other releases and trains, the default label distribution protocol is Tag Distribution Protocol (TDP). See the mpls label protocol (global configuration) command in the NSF/SSO—MPLS LDP and MPLS LDP Graceful Restart feature for more information.
MPLS MTU Command Changes
The mpls mtu command has changed over the course of the several releases, starting in Cisco IOS Release 12.2(25)S. This section documents the changes implemented in Cisco IOS Release 12.2(25)S. For information about the changes implemented in Cisco IOS Releases 12.2(27)SBC and later releases, see the MPLS MTU Command Changes feature.
In Cisco IOS Release 12.2(25)S, if the interface MTU is less than 1524 bytes, you can set the maximum MPLS MTU to 24 bytes more than the interface MTU. For example, if the interface MTU is set to
1510 bytes, then you can set the maximum MPLS MTU to 1534 bytes (1510 + 24).
Note Although you can set the MPLS MTU to a value greater than the MPLS MTU, it is recommended that you keep the MPLS MTU less than or equal to the interface MTU to prevent the hardware from dropping packets. A best practice is to set the interface MTU of the core-facing interface to a value greater than either the IP MTU or interface MTU of the edge-facing interface.
If the interface MTU is greater than or equal to 1524 bytes, then you can set the maximum MPLS MTU as high as the interface MTU. For example, if the interface MTU is set to 1600 bytes, then you can set the MPLS MTU to a maximum of 1600 bytes. If you set the MPLS MTU higher than the interface MTU, traffic is dropped.
For interfaces that do not allow you to configure the interface MTU value and the interface MTU is
1500 bytes, the MPLS MTU range is 64 to 1524 bytes.
If you upgrade to Cisco IOS Release 12.2(25)S from an earlier release and you have an MPLS MTU setting that does not conform to these guidelines, the MPLS MTU setting is not accepted by the system. If this happens, reconfigure the MPLS MTU setting to conform to the guidelines.
The following commands are no longer available in Cisco IOS Releases 12.2(25)S, 12.2(28)SB, 12.2(33)SRA, and 12.2(33)SXH:
•debug mpls adjacency
•debug mpls lfib cef
•debug mpls lfib enc
•debug mpls lfib lsp
•debug mpls lfib state
•debug mpls lfib struct
•debug mpls lfib fast-reroute
Table 1 lists the commands that use the term tag-switching. Starting with Cisco IOS Releases 12.2(25)S, 12.2(28)SB, 12.2(33)SRA, and 12.2(33)SXH, these commands have been updated with MPLS terminology. Although the tag-switching versions of the commands are obsoleted, the tag-switching commands continue to work, but are not documented.
Please use the MPLS versions of the commands. If you issue a tag-switching command, you receive the following error:% Command accepted but obsolete, unreleased, or unsupported; see documentation
For information about any of the MPLS commands in Table 1 and Table 2, see the
Cisco IOS Multiprotocol Label Switching Command Reference.
Table 1 alphabetically lists the MPLS commands used by the Cisco 7500 series routers that replaced the tag-switching commands.
Table 2 alphabetically lists the MPLS commands used by the Cisco 10000 series routers that replaced the tag-switching commands.
How to Configure MPLS High Availability: Command Changes
There are no cofiguration tasks for this feature.
Configuration Examples for MPLS High Availability: Command Changes
There are no configuration examples for this feature.
The following sections provide references related to the MPLS High Availability feature.
MIB MIBs Link
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL:
Feature Information for MPLS High Availability: Command Changes
Table 3 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.
Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. 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.
Note Table 3 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.
Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
© 2007 Cisco Systems, Inc. All rights reserved.