A method and system is described for delivering data streams in a network comprising devices connected to the network via adapters and wherein at least some of the devices are programmed to indicate priority of a data stream using priority parameter values of respective priority parameter types. One device in the network operates as a controller and the accompanying controller adapter is configured to perform priority enforcement on data streams according to all priority parameter types used within the datastreams in the network. A controller is also described and the controller can be a gateway configured to allow data streams into and out of the network. The method, system and controller find particular application in networks based on shared network segments, for example power line communication or networks based on coaxial cable.