Monitoring reachability in the global multicast infrastructure

The multicast infrastructure has transitioned to a topology that now supports hierarchical routing. Instead of a flat virtual topology originally called the Multicast Backbone (MBone) there now exists a hierarchy where routing information is exchanged between autonomous systems (ASes). In today´s multicast infrastructure reachability problems are common. Unlike in the MBone, the possibility of limited connectivity between domains is now possible. We present a system called sdr-monitor. This tool collects session directory information from numerous places around the world and presents an application layer view of reachability. Using data collected over the last year, we present an analysis of long term reachability characteristics for the global multicast infrastructure. Our findings are that overall reachability is generally quite poor. However, having identified some of the reasons, we believe there is not a fundamental infrastructure problem, but rather protocol bugs and a lack of management tools