A system for managing a data stream between first and second networks is described in which a node entity transmits a data stream addressed to a destination device in the second network and a gateway entity receives the data stream from the first network. The gateway entity identifies at least one characteristic of the destination device and transmits it to the node entity in the first network in such a way that the characteristic is relatable to the data stream. The node entity receives the characteristic of the destination device from the gateway entity and relates it to the data stream and performs Quality of Service management on the data stream based on the at least one characteristic. A gateway device and a method of managing a data stream are also described. The system, gateway, node and method extend the application of QoS performance and management.