switch in the mcast tree

Experts,
if there is a switch, let's say Cat3750 between the last hop router and
the mcast receiver, the switch snoops igmp by default and based on that
knows on which ports to forward mcast frames; that is clear.
But let's say that the switch is between two mcast routers of the mcast
tree, or between the source and the first-hop router, then there is no
IGMP to snoop. How does it behave then?
- floods mcast frame towards all ports as if it was bcast
- doesn't forward mcast at all
- something else

Thanks a lot,
Bit.

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Received on Mon Dec 28 2009 - 23:36:37 ART