Hello. We have to differentiate two different protocols : ethernet and IPv6.
What you said is correct. IPv6 doesn't have broadcast , instead of that IPv6 uses multicasts.
On the other hand Ethernet does support both broadcasts and multicasts, but Ethernet in order to recognize multicasts it needs extra configuration (IGMP snooping to work with IPv4 multicast and MLD snooping to work with IPv6 multicast).
So when you send an IPv6 multicast it will be encapsulated by default within a "broadcast" Ethernet frame and will be sent out all switchports, unless you configure MLD snooping.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...