BGP Configuration Guidelines > Advertising an Explicit Null Label

You can advertise an explicit null label (label 0) out of the egress for a label-switch path (LDP). By default, the router advertises label 3. Enabling explicit null allows the router to send out label 0. Advertising explicit null labels is used for peers in the same BGP group.

Configure the labeled-unicast statement with the explicit-null option. As with regular BGP configuration, the family statement can be specified.

Configure the labeled-unicast statement as follows:

family inet {

    labeled-unicast {

        aggregate-label {

            community community-name:

        }

        explicit-null {

            connected-only;

        }

    }

}

For a list of hierarchy levels at which you can configure this statement, see the statement summary section for this statement.

Specify the connected-only statement to advertise explicit null labels between connectly routes only (direct routes and loopback routes).

NOTE: The connected-only statement is required to advertise explicit null labels.

NOTE: Explicit null labels are supported for the IPv4 (inet) family only.