I. Introduction
Future generations of computer and communication systems are mainly driven by the users needs. The industry following customers expectations, foresees services supporting anyone, at anytime, anywhere in a seamless and secure way. In particular, personalized services provisioning is widely acknowledged as a key feature of the emerging large multi-service broadband networks. Indeed, these networks will have to support many disparate service classes, each with different traffic characteristics and requirements for networking functions dealing with security, billing, QoS (Quality of Service), mobility, etc. These heterogeneous service requests should be served in a way that it will both assure the qualitative provision of the particular requested service and make efficient and economical usage of network resources, so as to minimize operational costs and maximize network availability.