In the next generation Internet, the network should not only be considered as a communication medium, but also as an endless source of services available to the end-systems. These services (i.e. Overlay Applications) would be composed of multiple cooperative distributed software elements that dynamically build an ad hoc communication mesh (i.e. an Overlay Association). In this paper we propose and evaluate a collaborative distributed method to provide enhanced QoS between end-points within an overlay association.