In this paper we propose a new scheme named DQM (Differentiated QoS Multicast) based on the Source Specific Multicast (SSM) [7] model in order to provide limited and qualitative QoS channels to support heterogeneous end users. Similar to the DiffServ paradigm, in DQM the network is configured to provide finite QoS service levels to both content provider and receivers. Based on the Service Level Agreement, both the content provider and group members should select a specific QoS channel available from the network for data transmission, and in this case arbitrarily quantitative QoS states are eliminated. Moreover, we use the group address G contained in the (S, G) tuple in SSM service model to encode QoS channels, and data packets that belong to the same QoS channel identified by a common class D address can be treated aggregately, and this can be regarded as an overlay solution to Differentiated Services, specifically for source specific multicast applications.
