Configuring MPLS TE Verbatim Paths

This chapter describes how to configure a Multiprotocol Label Switching (MPLS) traffic engineering (TE) verbatim path on Cisco NX-OS devices.

This chapter includes the following sections:

Finding Feature Information

Your software release might not support all the features documented in this module. For the latest caveats and feature information, see the Bug Search Tool at https://tools.cisco.com/bugsearch/ and the release notes for your 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 “New and Changed Information” chapter or the Feature History table below.

Information About MPLS TE Verbatim Paths

Verbatim paths allow network nodes to support Resource Reservation Protocol (RSVP) extensions without supporting Interior Gateway Protocol (IGP) extensions for TE, thereby bypassing the topology database verification process.

MPLS TE label switched paths (LSPs) usually require that all the nodes in the network are TE aware, which means that they have IGP extensions to TE in place. However, some network administrators want to be able to build TE LSPs to traverse nodes that do not support IGP extensions to TE but that do support RSVP extensions to TE.

Verbatim LSPs are helpful when all or some of the intermediate nodes in a network do not support IGP extensions for TE.

When you enable a verbatim path, the IP explicit path is not checked against the TE topology database. Because the TE topology database is not verified, a message with IP explicit path information is routed using the shortest path first (SPF) algorithm for IP routing.

Licensing Requirements for MPLS TE Verbatim Paths

 

Product
License Requirement

Cisco NX-OS

Verbatim paths require an MPLS license. For a complete explanation of the Cisco NX-OS licensing scheme and how to obtain and apply licenses, see the Cisco NX-OS Licensing Guide.

Prerequisites for MPLS TE Verbatim Paths

Verbatim paths have the following prerequisites:

  • You must enable the MPLS TE feature. See the “Configuring MPLS TE”.
  • You must globally configure an MPLS TE tunnel.
  • You must enable MPLS TE on all links that will be used for LSPs.

Guidelines and Limitations for MPLS TE Verbatim Paths

Verbatim paths have the following configuration guidelines and limitations:

  • You can only use verbatim paths on an LSP that is configured with the explicit path option.
  • Verbatim LSPs do not support reoptimization.
  • You cannot configure MPLS TE over the logical generic routing encapsulation (GRE) tunnel interface.

Configuring MPLS TE Verbatim Paths

You can configure verbatim paths on MPLS TE tunnels by using the verbatim path option.

Prerequisites

You must have the MPLS TE feature enabled (see the “Configuring MPLS TE”).

Ensure that you are in the correct VDC (or use the switchto vdc command).

SUMMARY STEPS

1.blank.gif configure terminal

2.blank.gif interface tunnel-te number

3.blank.gif path-option number { dynamic | explicit { name path-name | path-number } [ verbatim ]} [ attributes string ] [ bandwidth kbps ] [ lockdown ]}

4.blank.gif (Optional) show interface tunnel-te number

5.blank.gif (Optional) copy running-config startup-config

DETAILED STEPS

 

Command
Purpose

Step 1

configure terminal

 

Example:

switch# configure terminal

switch(config)#

Enters global configuration mode.

Step 2

interface tunnel-te number

 

Example:

switch(config)# interface tunnel-te 1

Enters TE interface configuration mode.

The number argument identifies the tunnel number to be configured.

Step 3

path-option number { dynamic | explicit { name path-name | path-number } [ verbatim ]} [ attributes string ] [ bandwidth kbps ] [ lockdown ]

 

Example:

switch(config-if-te)# path-option 1 dynamic attributes 1

 

Adds an LSP attribute list to specify LSP-related parameters for path options for an MPLS TE tunnel. The arguments are as follows:

  • The number argument identifies the path option.
  • The dynamic keyword indicates that the path option is dynamically calculated (the switch figures out the best path).
  • The explicit keyword indicates that the path option is specified. You specify the IP addresses of the path.
  • The name path-name keyword argument combination identifies the name of the explicit path option.
  • The path-number argument identifies the number of the explicit path option.
  • The verbatim keyword bypasses the topology database verification.

Note You can use the verbatim keyword only with the explicit path option.

  • The attributes string keyword argument combination names an attribute list to specify path options for the LSP.
  • The bandwidth keyword specifies LSP bandwidth.
  • The kbps argument is the number of kilobits per second set aside for the path option. The range is from 1 to 4294967295.
  • The lockdown keyword disables reoptimization of the LSP.

Step 4

show interface tunnel-te number

 

Example:

switch(config-if-te)# show interface tunnel-te 1

(Optional) Displays information about the TE tunnel.

Step 5

copy running-config startup-config

 

Example:

switch(config-if-te)# copy running-config startup-config

(Optional) Copies the running configuration to the startup configuration.

Verifying the MPLS TE Verbatim Path Configuration

To display the MPLS TE verbatim path configuration, perform the following task:

 

Command
Purpose

show mpls traffic-eng tunnels tunnel-interface [ brief ]

Displays information about MPLS TE tunnel attributes and path options.

For detailed information about the fields in the output from these commands, see the Cisco NX-OS MPLS Command Reference.

Configuration Example for MPLS TE Verbatim Paths

This section provides the following configuration example:

Example: Verbatim Path

The following example shows how to configure a tunnel with an explicit path option using verbatim paths:

configuration terminal
feature mpls traffic-engineering
interface tunnel-te 1
ip unnumbered loopback 1
destination 10.10.100.100
bandwidth 1000
path-option 1 explicit name path1 verbatim
no shutdown

Additional References for MPLS TE Verbatim Paths

The following sections provide references related to the verbatim path feature.

Related Documents

Related Topic
Document Title

CLI commands

Cisco Nexus 7000 Series NX-OS MPLS Command Reference

MIBs

MIB
MIBs Link
  • CISCO-IETF-FRR-MIB
  • MPLS TE-STD-MIB

To locate and download Cisco MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

https://cfnng.cisco.com/mibs

Feature History for MPLS TE Verbatim Paths

Table 15-1 lists the release history for this feature.

 

Table 15-1 Feature History for Verbatim Path

Feature Name
Releases
Feature Information

Verbatim path

5.2(1)

This feature was introduced.