In a DiffServ Domain, several marking mechanisms for packets have been proposed. They make it possible to downgrade or to remove the packets from flows which are not in conformity with the traffic contract. However, all these mechanisms are adapted to operate in intra-domain rather than in multi-domain marking.

In this paper, we propose a multi-domain marking mechanism MDM for flows crossing one or more DiffServ domains in order to reduce the impact of the losses on the packets which have significant semantic value. The marking is carried out at the entrance to the DiffServ domain and at the exit where the initial priority of the downgraded packets is restored. Simulation results show a reduction in the losses of the significant packets. We compare this mechanism to already existing mechanisms by measurements of QoS parameters (delay, jitter, packet losses) of the various real-time flows.