Network convergence is becoming increasingly important for cost reduction and management simplification. However, this convergence requires strict performance isolation while keeping fine-grained control of each service (e.g. VoIP, video conference etc.). It is difficult to guarantee the performance requirements for various serviceswith manual configuration of the Quality-of-Service (QoS) knobs on a per-device basis as is prevalent today. We propose a network QoS control framework for converged fabrics that automatically and flexibly programs a network of devices with the necessary QoS parameters, derived from a high level set of application requirements. The controller leverages our QoS extensions of OpenFlow APIs, including per-flow rate-limiters and dynamic priority assignment. We also present some results from a testbed implementation to validate the performance of our controller.