Network mobility for multi-level networks

There are disclosed measures of address assignment for a network element being operable in a multi-level network, comprising retrieving a network prefix of said multi-level network and network prefix information including at least one of a top-level indication, a suffix length parameter and a maximum prefix length parameter, generating a first address in accordance with a topology of said multi-level network on the basis of said retrieved network prefix and network prefix information, and assigning said generated address to an egress interface of said network element.