In recent years, Internet has known an unprecedented growth, which, in turn, has lead to an
increased demand for real-time and multimedia applications that have high Quality-of-Service
(QoS) demands. This evolution lead to di±cult challenges for the Internet Service Providers
(ISPs) to provide good QoS for their clients as well as for the ability to provide di®erentiated
service subscriptions for those clients who are willing to pay more for value added services.