Scaling Bloom Filter Based Multicast with Hierarchical Tree Splitting

Bloom Filter based multicast has been proposed as a source-specific multicast solution to eliminate the multicast state requirements in the routers. However, the inherent limitation, the false positives, in the Bloom filter data structure amplifies the bandwidth wastage when the multicast tree scales to a large number of receivers. In this paper, we propose an algorithm which enhances the performance of the Bloom filter based multicast. It keeps the bandwidth waste below an acceptable upper bound while scaling the multicast tree for a large number of receivers. The large multicast tree is split into multiple smaller ones which are encoded into separate Bloom filters. Our algorithm enables multicast forwarding to be efficient - with careful setting of some parameters - for a hundreds of receivers as compared to the 20-30 receivers per group in the original technique. Furthermore, our algorithm, while slightly increasing the state requirements in the multicast sources, retains the desired property of statelessness in the intermediate routers.