Abstract: In order to allow a data network, for example around the home, to carry real-time data such as digital video and digital audio, in addition to carrying data for example between a PC and a printer or ISDN router, and in order to permit the latter data to be handled in accordance with known protocols, such as the IEEE 802.3 CSMA/CD Ethernet protocol, the real-time data is handled on a high-priority basis. The high-priority stations, such as a digital television set, digital TV set-top box, digital VTR and CD player employ a contention resolution process which ensures that they succeed in accessing the network bus over any low-priority stations, and the high priority stations employ a fairness process which ensures that they take it in turns to access the bus.