Decoupling QoS control from core routers: A novel bandwidth broker architecture for scalable support of guaranteed services

We present a novel bandwidth broker architecture for scalable support of gu aranteed services that decouples the QoS control plane from the packet forw arding plane. More specifically, under this architecture, core routers do n ot maintain any QoS reservation states, whether per-flow or aggregate. Inst ead, QoS reservation states are stored at and managed by bandwidth broker(s ). There are several advantages of such a bandwidth broker architecture. Am ong others, it relieves core renters of QoS control functions such as admis sion control and QoS state management, and thus enables a network service p rovider to introduce new (guaranteed) services without necessarily requirin g software/hardware upgrades at core routers. Furthermore, it allows us to design efficient admission control algorithms without incurring any overhea d at core routers. The proposed bandwidth broker architecture is designed b ased on a core stateless virtual time reference system developed in [20]. In this paper we focus on the design of efficient admission control algorit hms under the proposed bandwidth broker architecture. We consider both per- flow guaranteed delay services and class-based guaranteed delay services wi th flow aggregation. We demonstrate how admission control can be done on an entire path basis, instead of on a "hop-by-hop" basis. Such an approach ma y significantly reduce the complexity of the admission control algorithms. We also study the impact of dynamic flow aggregation on the design of class -based admission control algorithms. Based on the proposed bandwidth broker architecture, we devise effective mechanisms to circumvent the problem cau sed by dynamic flow aggregation.