A packet-based data network includes a packet-based network switch, and a plurality of packetised data sources coupled to the network, where the packetised data includes at least one of audio data or video data. The data network further includes at least one destination, being a data handling device for handling packetised data sources, coupled to the network, and a network control arrangement coupled to the network, the network arrangement being arranged to provide virtual circuit-switched connections for transfer of packetised data from sources to destinations via the network switch by assigning multicast group identifiers to the sources, so that the sources launch packetised data onto the network as multicast data packets identified by the multicast group identifiers, and instructing a destination to issue a request to the network switch to join the multicast group of a source so as to receive data packets from that source.