The recommended policy-based management system by the IETF is a two-tiered architectural design. It exhibits several observable fundamental limitations, for example, system scalability and cross-vendor hardware compatibility problems. In this article, a multitiered architecture, the unified policy-based management system, is proposed. The middle-tier agents, introduced between policy managers and network routers, offer flexibility and scalability to the design. A dynamic unified information model can be achieved between the policy decision and enforcement points of the system by properly extending network protocols, by installing or removing hardware interpretation modules on the fly, and by interpreting and translating request/decision messages at the agents. To complete the UPM design, novel load sharing and balancing communication protocols are implemented to improve system scalability. The system performances of the UPM are compared to the recommended PBM system of the IETF through extensive experiments. The results indicate that the UPM is a high-performance and scalable policy-based management design.