An Adaptive Differentiated Service Multicast Gateway

This paper proposes a DiffServ-based multicast media gateway, called Adaptive Differentiated Service Multicast Gateway (ADMG), to guarantee QoS and scalability for multimedia presentation. The two goals of the ADMG system are (1) to increase bandwidth utilization by reserving statistical multiplexing bandwidth based on layered-media aggregation and (2) to improve the quality of presentation of the received layered media streams by dynamically modifying the sending rates of various service queues when the network passes heavy traffic. To reach these two goals, the proposed statistical layered aggregation model exploits the traffic-burst regularity of each layered aggregating flow, including I-frame, P-frame and B-frame flows, to determine the approximate reserved bandwidth. Additionally, the ADMG system dynamically changes the sending rates of various service queues to ensure that layered media packets with higher priority are always sent before those with lower priority. The proposed aggregation model, which is inconsistent with unaware GOP-based layered-media aggregation methods, has been experimentally tested on several layered-video streams. The results reveal that the proposed scheme outperforms others with a substantial reduction of bandwidth reservation even given tight delay bounds. The experimental results of the ADMG system on DiffServ networks also reveal the capability for dynamic bandwidth adjustment in various networking situations.