Date Added: Nov 2012
Recent developments in router level topology discovery have suggested the introduction of IGMP probing in addition to standard techniques such as traceroute and alias resolution. With a single IGMP probe, one can obtain all multicast interfaces and links of a multicast router. If such a probing is a promising approach, the authors noticed that IGMP probes are subject to filtering, leading so to the fragmentation of the collected multicast graph into several disjoint connected components. In this paper, they cope with the fragmentation issue. Their contributions are threefold: they experimentally quantify the damages caused by IGMP filtering on collected topologies of large tier-1 ISPs; using traceroute data, they construct a hybrid graph and estimate how far each IGMP fragment is from each other.