An enhanced application-level multicast protocol: a QoS perspective

Ubicast, an enhanced application-level multicast protocol, is presented in this paper. It is built upon Pastry, a robust and self-organizing peer-to-peer substrate overlay, and leverages its merits of reliable application-level routing and object location. Ubicast is mainly applied to real-time multimedia applications with QoS heterogeneity. It tries to minimize the delay radius of the multicast tree, while meeting different bandwidth requirements. It extends traditional degree-bound model and satisfies nodes´ heterogeneous QoS requirements to provide customizable multicast services. Besides, Priority Joining Algorithm based on the concept of potential parents is proposed to limit the number of nodes that a participant needs to probe. The join cost is decreased substantially to guarantee the scalability for a potentially large network topology. Simulation and experimental analysis over large-scale topology confirm the performance improvement of Ubicast which is especially suited for small sized multicast groups.