In accordance with an example embodiment, there is provided an apparatus, comprising a receiver configured to receive from a second apparatus over a first radio interface a first message comprising a registration request, a transmitter configured to transmit a second message to the second apparatus over the first radio interface, the second message comprising an acknowledgement of the registration request, and a processor configured to reserve an interface identifier for the second apparatus, wherein the processor is configured to not allow the reserved interface identifier to be used by further nodes over at least one further radio interface.