An architecture for noncooperative QoS provision in many-switch systems

With the proliferation of high-speed networks and networked services, provisioning differentiated services to a diverse user base with heterogeneous QoS requirements has become an important problem. The traditional approach of resource reservation and admission control provides both guarantees and graded services, however, at the cost of potentially underutilized resources and limited scalability. We describe a WAN QoS provision architecture that adaptively organizes best-effort bandwidth into stratified services with graded QoS properties such that the QoS needs of a diverse user base can be effectively met. This architecture-SBS (stratified best-effort service)-promotes a simple user/simple network realization where neither the user nor the network is burdened with complex computational responsibilities. SBS is scalable, efficient, and adaptive, and it complements the guaranteed service architecture, sharing a common network substrate comprised of GPS routers. It is also a functional complement, provisioning QoS efficiently commensurate with user needs, albeit at the cost of weaker protection. SBS is suited to noncooperative network environments where users behave selfishly and resource contention resolution is mediated by the principle of competitive interaction. A principal feature of SBS is the transformation of user-centric QoS provision mechanisms-a defining characteristic of competitive interaction entailing intimate user control of internal network resources-into network-centric mechanisms while preserving the former's resource allocation paradigm. End-to-end QoS control is facilitated by decentralized control based on Lagrangian optimization-achieve a target end-to-end QoS at minimum cost or resource usage-which, in turn, is amenable to distributed implementation. SBS achieves per-flow QoS control with zero per-flow state at routers and a packet header whose size is independent of hop count. SBS, in spite of foregoing both resource reservation and admission control, is able to provision stable, graded QoS.