Abstract: The aim of the invention is to exchange data between an external device and applications installed on network elements of a packet-switching network by means of at least one tunnel connection. Said aim is achieved by connecting each network element to a network node device that is part of the tunnel connection while a global address is unambiguously assigned to the terminal point of the tunneled connection, which is located at the network end. The network node device forms the terminal point of the tunnel connection, which is located at the network end, if several network elements jointly utilize said tunnel connection, one of the network elements establishing a tunnel connection and forming the terminal point at the network end thereof if said network element requires a global address for executing an application, a time during which said tunnel connection is used exclusively by said one network element while all data is routed through the network node device.