This paper presents a multimedia transport service based on distributed QoS (quality of service) management mechanisms acting along the communication path. The distribution model is supported by a simple active networking paradigm for IP based networks. On demand QoS adaptation is performed by transport agents located along the network path when required by receivers. The transport service provided, targets tolerant/adaptive multimedia applications using network services with QoS fluctuations. It is on wide area networking scenarios (high delay*bandwidth products) that important QoS optimisation can be achieved for application layer parameters.