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

Configure Layer 2 AC interfaces

Updated: July 31, 2026

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This topic describes how to configure the Layer 2 attachment circuit (AC) interfaces for routing by a Bridge-Group Virtual Interface (BVI), including enabling Layer 2 transport mode, applying IEEE 802.1Q encapsulation, and rewriting ingress tags.

Before you begin

The interfaces to be configured as Layer 2 ACs in the bridge domain and routed by a BVI must be located on the Cisco 8000 Series Router.

To configure the Layer 2 AC interfaces for routing by a BVI, complete the following steps.

Procedure

1.

Run the configure command to enter the global configuration mode.

Example:


Router#configure
2.

Run the interface [HundredGigE] interface-path-id[ .subinterface] l2transport command to enable Layer 2 transport mode on a HundredGigE interface or subinterface and enter the interface or subinterface configuration mode.

Example:

Router(config)#interface HundredGigE 0/1/0/0.1 l2transport

The interface-path-id is specified as the rack/slot/module/port location of the interface and .subinterface is the optional subinterface number.
3.

(Optional) Run the encapsulation dot1q vlan-id [exact] orencapsulation dot1ad vlan-id dot1q vlan-id command to configure the IEEE 802.1Q encapsulation on the specified VLAN only.

Example:

Router(config-if)#encapsulation dot1q 1 exact
4.

(Required if VLAN tagging configured) Specify the one or two tags (depending on the network configuration) that should be removed from frames arriving at the ingress interface to the bridge domain.

Example:

Router(config-if)#rewrite ingress tag pop 1 symmetric
Note

When you configure double tags using dot1ad and dot1q encapsulation, you must use the rewrite ingress tag pop 2 symmetric command.
5.

Run the end or commit commands to save the configuration changes.

Example:

Router(config-if)#end

or

Router(config-if)#commit

  • When you issue the end command, the system prompts you to commit changes:

    
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[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 command to save the configuration changes to the running configuration file and remain within the configuration session.