Multimedia and real-time applications have peculiar requirements in terms of the quality of data transmission services, that are not satisfied by the best effort nature of IP. Moreover, many of the multimedia applications are characterized by a multicast communication pattern. In this work, we propose a functional architecture aiming at providing a common framework to deploy network protocols supporting QoS. The architecture is compliant with the main standards proposed in the literature. We discuss two possible implementations of the architecture modules for the service set-up, in either the int-serv model or the diff-serv model. We present some performance evaluations obtained by performing experiments with those two implementations.