Topology Optimization for DHT-Based Application Layer Multicast

In recent years, Distributed Hash Tables (DHTs) attract a lot of attentions since they have many advantages such as good routing performance, scalability, fault tolerance, load balancing. Those properties make DHTs are suitable for deploying multicast services at application layer. However, early DHT-based multicast systems are insufficient in addressing a number of technical issues such as heterogeneous node capacity, large-scale multicast and dynamic membership. In this paper, we propose BAM-Chord: Bandwidth Adaptive Multicast over Chord, a DHT-based multicast system that focuses on host heterogeneity, scalability and fault tolerance. In our system, when a node joins into the system, it will And out an appropriate position (i.e. node identifier) on a BAM-Chord ring and create links to neighbor nodes based on node's bandwidth capacity such that the multicast tree can be built efficiently and balanced. Therefore, our system can utilize bandwidth of every node to reduce the depth of the multicast tree and take advantages of DHTs in maintaining the multicast tree.