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

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

IID-TLV behavior in IS-IS protocol instances

Updated: June 9, 2026

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Explains IID-TLV behavior in IS-IS protocol instances, including its role in uniquely identifying instances, controlling PDU applicability to topologies, and recent feature updates that enable disabling IID-TLV and relevant CLI and YANG data model enhancements.

IID-TLV is a protocol attribute that

  • uniquely identifies IS-IS protocol instances when multiple instances are configured

  • defines how the Instance Identifier Type-Length-Value (IID-TLV) is included in Hello and LSP packets, and

  • allows granular control over protocol data unit (PDU) applicability to specific topologies.

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

Disable IID-TLV of IS-IS Protocol Instance

 Release 25.1.1

Introduced in this release on: Fixed Systems (8700 [ASIC: K100], 8010 [ASIC: A100])(select variants only*)

*This feature is supported on:

  • 8712-MOD-M

  • 8011-4G24Y4H-I

Disable IID-TLV of IS-IS Protocol Instance

 Release 24.4.1

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

*This feature is supported on:

  • 8212-48FH-M

  • 8711-32FH-M

  • 88-LC1-36EH

  • 88-LC1-12TH24FH-E

  • 88-LC1-52Y8H-EM

Disable IID-TLV of IS-IS Protocol Instance

 Release 7.10.1

You can now disable Instance Identifier Type-Length-Value (IID-TLV) in the Hello and LSP packets when multiple IS-IS protocol instances are configured on the router.

Each IS-IS instance has a unique instance-ID set, the TLV of which is sent in the Hello and LSP packets. The IID-TLV attribute helps in uniquely identifying the IS-IS protocol instance as well as the topologies to which the Protocol Data Units (PDUs) apply.

The feature introduces these changes:

CLI

New Command:

iid disable

Modified Commands:

The hello-padding command is extended to IS-IS process configuration mode.

The disable (IS-IS) command is modified with a new level keyword, and also extended to interface configuration mode.

YANG Data Model

New XPaths for openconfig-isis.yang (refer to GitHub and YANG Data Models Navigator)

The IID-TLV attribute provides a way to distinguish between multiple IS-IS protocol instances on the same device and the specific topologies to which their protocol data units (PDUs) apply. By disabling IID-TLV in Hello and LSP packets, you can control how instances are identified and ensure proper isolation in complex configurations.