Island multicast: The combination of IP multicast with application-level multicast

The Internet nowadays consists of multicast-capable domains or "islands" interconnected by multicast-incapable routers. In order to achieve efficient global multicast, we propose and study Island Multicast (IM) where overlay connections are used between islands while IP multicast is used within an island. IM may use any existing application-level multicast protocol to build island overlay. We describe how to elect a representative (or leader) in each island for such a purpose. We also present the mechanisms for electing the bridging nodes for overlay connections. Using Internet-like topologies, we show that IM achieves much higher bandwidth efficiency as compared to using application-level multicast alone, at the cost of a small increase in end-to-end delay.