I have a router R with interface FastEthernet 0/0 connected to a switch SW. R is running PIM in dense mode on all interfaces and from inerface Fa0/0 igmp queries are sent. When I turn on a host which injects a high level of broadcast traffic into SW, many queries are lost (they don't reach the hosts connected to SW. Consequently, some hosts which want to reiceve multicast traffic, stop to receive it.
Now, if I disable igmp snooping on SW (which is on by deafault), everything becomes normal again (queries are no longer lost anf multicast traffic is received by everyone connected to SW).
So, to sum up:
- igm snooping on, no broadcast -> OK
- igmp snooping off, broadcast on -> OK
- igmp snooping on, broadcast on -> PROBLEMS
From show processes cpu and show processes memory, SW does not seem to be overloaded.
Thanks in advance.