Modular QoS Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

PDF

Modular QoS Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

QoS policy inheritance

Updated: June 9, 2026

Want to summarize with AI?

Log in

Explains the QoS policy inheritance feature, which allows a single policy applied to a main interface to be automatically enforced on all attached subinterfaces. It describes how this model simplifies configuration management and provides cumulative statistics for the entire interface hierarchy.

QoS policy inheritance is a QoS classification feature that

  • applies a single QoS policy on a main interface and automatically enforces it on all attached subinterfaces

  • supports all QoS operations including classification, marking, policing, and shaping, and

  • supports cumulative policy-map statistics visibility for the main interface that includes its subinterfaces.

Running the show policymap interface command displays the cumulative statistics for an interface, and these numbers include the subinterfaces as well.

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

QoS Policy Inheritance

Release 25.4.1

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

*This feature is supported on:

  • 8011-32Y8L2H2FH

  • 8011-12G12X4Y-A/D

QoS Policy Inheritance

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

QoS Policy Inheritance

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-LC1-52Y8H-EM

  • 88-LC1-12TH24FH-E

QoS Policy Inheritance

 Release 7.3.15

To create QoS policies for subinterfaces, you had to apply the policy on each subinterface manually. From this release, all you do is create and apply a single QoS policy on the main interface and the subinterfaces automatically inherit the policy.

The inheritance model provides an easily maintainable method for applying policies, enabling you to create targeted policies for a group of interfaces and their subinterfaces. This model saves your time and resources while creating QoS policies.

Limitations of the QoS policy inheritance model

  • ECN marking and egress marking policies cannot be used simultaneously on a main interface and its subinterfaces.

    Avoid configuring ECN-enabled policies and egress marking policies across the same main interface–subinterface hierarchy to prevent ECN marking failures.

  • The inheritance model is the default option; policy inheritance cannot be selectively overridden on individual subinterfaces.

    To prevent policy inheritance on specific subinterfaces, remove the policy from the main interface and explicitly configure policies on the required subinterfaces.