"... Multicast Beacon is a multicast diagnostic tool written in Perl which uses the RTP protocol (RFC3550) to provide useful statistics and diagnostic information about a given multicast group's connectivity characteristics.Multicast is a way of distributing IP packets to a set of machines which have expressed an interest in receiving them. It is a one-to-many distribution model suitable for video conferencing and other forms of data sharing over the network."see h**p://beacon.dast.nlanr.net