For the last several years, the Internet multicast backbone has been a growing part of the Internet infra structure, and of strategic interest to the network research community experimenting with multicast technologies. In particular, the MBONE has been a deployment testbed for scalable distribution of group audio and video streams. Rapid growth in topology and traffic volume of the multicast infrastructure has brought inevitable scaling problems, not the least of which is the increased negative impact incurred by accidental misconfiguration of MBONE nodes. In pursuit of insight into the MBONE topology, its growth characteristics, and the extent of the transition from the tu nnel-based architecture to the deployment of native multicast, we developed and applied visualization tools to the database of connectivity information collected with the mwatch [MWAT] utility from University College London. We have used two separate visualization tools for this task: MantaRay [MANTA], for geographic-map based depiction of MBONE data collected by mrinfo queries; and otter [OTTER], for topological visualizations of the same data.

MantaRay and Otter are part of the fleet of tools from the Cooperative Association for Internet Data Anal ysis (CAIDA) for visualizing various sets of Internet data. Both tools are Java-based and allow users to select parts of the data, focus or zoom in on particular areas, color by various param eters, and generally explore multicast topologies.