The Differentiated Services (DiffServ) model is a potential solution for providing quality of service (QoS) on the Internet. In this paper, we propose a scalable architecture that fulfills the design philosophy of the DiffServ model. In contrast to other existing architectures, our proposed architecture puts complexity on edge routers so that core routers do not need to support any specific function for service differentiation. Further, the proposed architecture only needs a few additional functions in edge routers. Thus its deployment is simpler than most existing architectures. We also address how to achieve weighted proportional fairness solely by edge routers.