A split protocol transmission method for transmitting data and a communication thread identifier for said data along a communication path from a source functional unit (SFU) to a destination functional unit (DFU) via zero or more intermediate functional units (IFU) is described. A data consuming functional unit (CFU) and a data producing functional unit (PFU) in the communication path directly communicate to each other by means of a handshake procedure wherein the data consuming functional unit (CFU) indicates a communication thread identifier (TID) to the data producing functional unit. The data producing functional unit provides data related to said communication thread identifier to said data consuming functional unit. Likewise a data processing system using this method is described.