While the Internet is tremendously scalable, it is based on simplistic design that provides only egalitarian best effort service for all traffic types. Two architectural extensions have been proposed, namely Intserv and Diffserv, to enhance the service architecture. While Integrated Services (Intserv) can provide hard Quality of Service (QoS) requirements (delay and bandwidth) to individual flows end to end, its per-flow mechanisms and signaling overhead make it too complex to be readily deployed in the Internet core. On the other hand, Differentiated Services (Diffserv) restores the scalability of the Internet by dropping per flow mechanisms and merging of flows into aggregates. The price paid is the lack of flexible and powerful services at flow granularity levels.