This object indicates the way to specify the interface that the Transport Address is assigned to.
Value: 0..2147483647
The default value of the object for the public interface is the interface that the LDP LSR ID is assigned to.
If the LDP LSR ID is not assigned to any interface, then the value of the object is 0, and 0 cannot be set.
The default value of the object for the private interface is the private interface itself.
Based on mplsL3VpnIfConfRowStatus of mplsL3VpnIfConfTable, you can find which interface belongs to the VPN.
The interface must be bound with the same VPN instance.