IP is clearly emerging as the networking paradigm for the integration of the tr- ?c ?ows generated by a variety of new applications (IP telephony, multimedia multicasting, e-business, ...), whose performance requirements may be extremely di?erent. This situation has generated a great interest in the development of te- niques for the provision of quality of service (QoS) guarantees in IP networks. Two proposals have already emerged from the IETF groups IntServ and Di?- Serv, but research and experiments are continuing, in order to identify the most e?ective architectures and protocols. The...