RTnet is a distributed real-time network protocol, to be used on fully-connected local area networks with a broadcast capability. It supports on-the-fly addition and removal of network nodes, resource-lavish and resourcelean devices, streaming real-time and regular non-realtime traffic. It allows the use of standard real-time scheduling paradigms to control network traffic, allows dynamic scheduling and is flexible in stream handling. The design is presented, together with measurement results of an experiment with an implementation on top of Ethernet.