A QoS architecture for quantitative service differentiation

For the past decade, a lot of Internet research has been devoted to providing different levels of service to applications. Initial proposals for service differentiation provided strong service guarantees, with strict per-flow bounds on delays, loss rates, and throughput, but required high overhead in terms of computational complexity and memory, both of which raise scalability concerns. Recently, the interest has shifted to class-based service architectures with low overhead. However, these newer service architectures only provide weak service guarantees, which do not always address the needs of applications. In this article we introduce a service architecture that supports strong per-class service guarantees, can be implemented with low computational complexity, and only requires maintenance of a little state information. A key mechanism of the proposed service architecture is that service rate allocation to classes is adaptive, and combined with buffer management. Furthermore, instead of using admission control or traffic policing, the proposed architecture exploits explicit congestion notification for the purpose of regulating the traffic entering the network.