This paper describes a hierarchical architecture of active policies that performs the management of a differentiated services (DiffServ) network. These policies monitor quality of service (QoS) parameters and dynamically optimize some aspects of the existing equipment and services to provide the best possible QoS to users. This helps the enforcement of a Service Level Agreement (SLA) between a provider and users. The results show that the use of active policies improves the service offered to users, by constantly adapting to the network state, and helping to fulfill SLAs with minimum costs to the service provider.