The invention relates to a method, a network management unit for assigning virtual addresses and a network termination unit for determining virtual addresses of a terminal unit that is connected by means of a terminal connection and a subscriber-side network termination unit of a virtual network. A network management unit transmits a second identifier assigned to the terminal connection together with virtual addresses of the network termination unit in order to assign virtual addresses of the network termination unit in response to its address request messages. A virtual address requested with said second identifier is used as virtual address of the terminal unit.