All things related to multicast

[Bill Fenner <>]

One common reason for this kind of failure is an IGMP problem at the
receiver.  When the system first joins the group, a couple of unsolicited
IGMP reports are sent to cause traffic to flow immediately.  However,
continuing membership info should be learned by the routers sending
Queries and the system responding to the Queries.  My impression is
that IGMP-snooping switches and the like sometimes tend to be able to
drop, lose or block Query messages, causing this kind of failure.

  Bill