Multicast routing in heterogeneous wireline/wireless environments

We present the BTLA (Base Tree Link Augmentation) multicast routing infrastructure for heterogeneous wireless/wireline networks. BTLA has two goals: (a) to reduce the latency and overhead of joins, leaves, and handoffs in regions that experience high group dynamics and mobility, and (b) to optimize the multicast tree for stable regions that do not experience frequent group dynamics. BTLA consists of two components: (a) pre-computed minimum height spanning trees of the multicast network called base trees that are used to generate and update multicast trees with low latency and overhead under dynamic network conditions, and (b) link augmentation-based optimization of the multicast tree using additional links in the multicast network that are not a part of the base tree, in order to reduce the size of the multicast tree. BTLA uses the base tree approach in dynamic regions and refines it with the link augmentation approach in stable regions. Initial performance evaluation shows that BTLA is able to effectively support multicast communication involving both static and mobile hosts.