Bridge-node selection and loss recovery in island multicast

Island multicast (IM) has been recently proposed to achieve efficient global multicast, where IP multicast is used within multicast-capable domains (the so-called islands) while overlay connections are used to bridge islands. In the previously proposed scheme, the number of ping measurement to find good bridge-nodes is at least proportional to island size, and a leader needs to keep track of all its members in the island. In this paper, we improve the system scalability by presenting a bridge-node selection algorithm where both the numbers of ping measurements and members to keep track of are greatly reduced to some constants. We further propose a recovery scheme for packets lost across islands. Our scheme uses a number of recovery meshes formed by overlays of some randomly chosen nodes. Simulation results show that our bridge-node selection is efficient in terms of control overhead and achieves scalability with little cost in network stress and delay. As compared to traditional source and parent recoveries, our loss recovery scheme substantially reduces both the recovery delay and bandwidth overhead to achieve reliability.