Interfaces and Hardware Component Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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Interfaces and Hardware Component Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

Preconfigure a physical interface

Updated: September 8, 2026

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Provides the steps to preconfigure a physical interface and verify the resulting running configuration.

Use this task for the most basic preconfiguration of an interface that is not yet present in the router.

Before you begin

Before preconfiguring physical interfaces, ensure that you meet the following conditions:

  • Preconfiguration drivers and files are installed. Although it might be possible to preconfigure physical interfaces without a preconfiguration driver installed.

  • Ensure the preconfiguration files are configured to define the interface definition file, as this file is required to supply the strings for valid interface names.

Procedure

  1. Use the interface preconfigure command in global configuration mode to preconfigure interfaces that are not yet present in the system.

    The command places the router in interface configuration mode, where you can add the supported interface commands for the preconfigured interface. The verifiers registered for the preconfigured interfaces verify the configuration. The preconfiguration is complete when you enter the end command, or any matching exit or global configuration mode command.

  2. Enter global configuration mode.

    Example:

    Router:hostname# configure

  3. Enter interface preconfiguration mode for an interface by using the interface preconfigure type interface-path-id command, where type specifies the supported interface type that you want to configure and interface-path-id specifies the location where the interface is located in rack/slot/module/port notation.

    Example:

    Router(config)# interface preconfigure HundredGigE 0/3/0/2

  4. Assign an IP address and mask to the interface. Use one of the following commands:

    • ipv4 address ip-address subnet-mask
    • ipv4 address ip-address/prefix

    Example:

    Router(config-if-pre)# ipv4 address 192.168.1.2/31

  5. End or save your changes.

    Example:

    Router(config-if-pre)# end
or
Router(config-if-pre)# commit

  • When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting (yes/no/cancel)?

  • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

  • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

  • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit best-effort command to save the configuration changes to the running configuration file and remain within the configuration session. The commit best-effort command merges the target configuration with the running configuration and commits only valid changes (best effort). Some configuration changes might fail due to semantic errors.