We present a case study of visualizing the global topology of the Internet MBone. The MBone is the Internet's multicast backbone. Multicast is the most efficient way of distributing data from one sender to multiple receivers with minimal packet duplication. Developed and initially deployed by researchers within the Internet community, the MBone has been extremely popular for efficient transmission across the Internet of real-time video and audio streams such as conferences, meetings, congressional sessions, and NASA shuttle launches. The MBone, like the Internet itself, grew exponentially with no central authority. The resulting suboptimal topology is of growing concern to network providers and the multicast research community.

We create a geographic representation of the tunnel structure as arcs on a globe by resolving the latitude and longitude of MBone routers. The interactive 3D maps permit an immediate understanding of the global structure unavailable from the data in its original form as lines of text with only hostnames and IP addresses. Data visualization techniques such as grouping and thresholding allow further analysis of specific aspects of the MBone topology. We distribute the interactive 3D maps through the World-Wide Web using the VRML file format, thus allowing network maintainers throughout the world to analyze the structure more effectively than would be possible with still pictures or pre-made videos.