IS-IS Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

PDF

IS-IS Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

MPLS Traffic Engineering

Updated: June 9, 2026

Want to summarize with AI?

Log in

Introduces MPLS traffic engineering support, guiding users through the configuration of MPLS TE features for IS-IS environments to optimize network path selection and resource utilization.

Multiprotocol Label Switching Traffic Engineering (MPLS TE) is a set of network capabilities that

  • replicates and expands the traffic engineering abilities of traditional Layer 2 ATM and Frame Relay networks

  • integrates Layer 2 and Layer 3 technologies to optimize resource management, and

  • enables IS-IS to automatically establish and maintain label-switched paths using protocols like Resource Reservation Protocol (RSVP).

Table 1. Feature History Table

Feature Name

Release Name

Description

Multiprotocol Label Switching Traffic Engineering

Release 25.4.1

Introduced in this release on: Fixed Systems (8700 [ASIC: K100])(select variants only*)

*This feature is supported on Cisco 8711-48Z-M routers.

Multiprotocol Label Switching Traffic Engineering

 Release 25.1.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*)

*This feature is supported on Cisco 8011-4G24Y4H-I routers.

Multiprotocol Label Switching Traffic Engineering

Release 24.4.1

Introduced in this release on: Fixed Systems (8200 [ASIC: P100], 8700 [ASIC: P100, K100])(select variants only); Modular Systems (8800 [LC ASIC: P100])(select variants only*)

This feature enhances network efficiency by using RSVP to automatically establish and maintain label-switched paths, selecting routes based on resource requirements and available bandwidth.

*This feature is supported on:

  • 8212-48FH-M

  • 8711-32FH-M

  • 8712-MOD-M

  • 88-LC1-36EH

  • 88-LC1-12TH24FH-E

  • 88-LC1-52Y8H-EM

MPLS TE allows the MPLS backbone to emulate and extend the traffic engineering methods used in ATM and Frame Relay. With IS-IS, MPLS TE uses RSVP to automatically build and maintain label-switched paths (LSPs) across the backbone. The path selection depends on each LSP’s resource requirements and the current network conditions, such as bandwidth availability. IS-IS advertises available resources through special TLV extensions. The label-switched paths are explicit routes, commonly called traffic engineering (TE) tunnels.

Configure MPLS TE for IS-IS

Enable MPLS Traffic Engineering (TE) within the IS-IS routing protocol to allow the network to support scalable and efficient path management for traffic engineering.

MPLS TE support in IS-IS lets routers advertise traffic engineering information, which is critical for creating and maintaining MPLS TE Label Switched Paths (LSPs). You should configure these settings on every IS-IS router participating in MPLS TE.

Before you begin

  • Make sure your devices support the MPLS feature.

  • Do not configure MPLS TE over unnumbered IP links, as it is not supported.

Procedure

1.

Enter IS-IS router configuration mode, and specify the address family (IPv4 or IPv6).

Example:


Router(config)# router isis isp
Router(config-isis)# address-family ipv4 unicast
2.

Enable MPLS TE link-state flooding in the desired IS-IS level.

Example:


Router(config-isis-af)# mpls traffic-eng level 1
3.

Set the MPLS TE router identifier.

Example:


Router(config-isis-af)# mpls traffic-eng router-id loopback0
4.

Configure wide metrics (required for MPLS TE).

Example:


Router(config-isis-af)# metric-style wide level 1

Configures a router to generate and accept only wide link metrics in the Level 1 area.

5.

Use the show isis instance isp mpls traffic-eng tunnel command to verify MPLS TE tunnel information.

Example:


Router# show isis instance isp mpls traffic-eng tunnel
6.

Use the show isis instance isp mpls traffic-eng adjacency-log command to view MPLS TE IS-IS adjacency logs.

Example:


Router# show isis instance isp mpls traffic-eng adjacency-log
7.

Use the show isis instance isp mpls traffic-eng advertisements command to view the latest MPLS TE flooded advertisements.

Example:


Router# show isis instance isp mpls traffic-eng advertisements