This book constitutes the refereed proceedings of the 6th IFIP/IEEE International Conference on the Management of Multimedia Networks and Services, MMNS 2003, held in Belfast, Northern Ireland in September 2003. The 39 revised full papers presented were carefully reviewed and selected from numerous submissions. The papers are organized in topical sections on stream control and management, management and control of multicast communications, ad-hoc and sensor networks, QoS and mobility management in wireless networks, traffic engineering and routing, differentiated network services, on-demand networking issues and policies, multimedia QoS management, security management, and (corresponding to an associated workshop) end-to-end monitoring techniques and services.