A network interface device capable of communication with a data processing system supporting an operating system and at least one application, the network interface device supporting communication with the operating system by means of: two or more data channels, each data channel being individually addressable by the network interface device and being capable of carrying application-level data between the network interface device and the data processing device; and a control channel individually addressable by the network interface device and capable of carrying control data between the network interface device, the control data defining commands and the network interface being responsive to at least one command sent over the control channel to establish at least one additional data channel.