Policy-based network management is a necessity in managing large scale environments. As the network size increases the need for automated tools to perform management increases rapidly. Specifically, configuring routers and network devices to achieve Quality of Service goals is a challenging task. Using Differentiated Services to dynamically perform this configuration involves defining policies on different network nodes along multiple domains. The aggregation of??such policies across several domains requires a unified policy model that can overcome the challenge of conflict detection and resolution. In this work, we propose a unified model to represent and encode QoS policies that will result in efficient and flexible conflict analysis ability. The representation utilizes a bottom-up approach, from basic policy parameters to the aggregation of the overall policy across domains with respect to traffic classes. We also present a classification of these conflicts and a simple analysis method for measuring the severity of the conflict.