Supporting the Need for Inter-Domain Multicast
Kamil Sarac & Kevin C. Almeroth
University of California Santa Barbara
Internet multicast is transitioning from the flat, virtual
topology known as the Multicast Backbone (MBone) to a
hierarchical, globally deployed service. This transition introduces
a number of important management issues. In
particular, it is believed that the success of multicast on
a large scale partly depends on the availability of good
management tools. In this paper, we address the specific
management problem of monitoring multicast reachability.
We first define the semantics of multicast reachability and
how they differ from unicast reachability. We then motivate
the importance of being able to monitor multicast reachability.
Based on this discussion, we have developed a system,
called sdr-monitor, to monitor reachability on a global
scale. Using sdr-monitor we have collected almost a year
of reachability data. In analyzing the data, we first process
it to remove artifacts caused by using sdr. We then analyze
the data to calculate a percentage of reachability in the
multicast infrastructure. While we find that the current infrastructure
is significantly unstable, the main reasons are
likely the newness of inter-domain multicast and the challenge
of developing "in-the-network" services on top of IP.