The Cat 3550 supports IGMP Snooping of IGMP v2.  What happens in the
situation where the hosts are running IGMPv3 or a combination of v2 and v3?

I also have an old switch that can perform IGMP snooping of IGMP version 1
only.  If the router and the hosts are all using IGMPv2 would this work? ie.
Is IGMPv2 a superset of IGMPv1?

Many thanks for your thoughts,

Ross

yes