Abstract: A data processing system comprising: a host processing device supporting a host transport engine operable to establish one or more transport streams over a network with a remote peer, the host transport engine maintaining state for each transport stream; and device hardware comprising: a device application; a device transport engine operable to perform transport processing of a transport stream on behalf of the device application; wherein the host transport engine is configured to, on establishing a first transport stream for termination at the device application, pass sufficient state to the device transport engine so as to permit the device transport engine to perform transport processing of the first transport stream.