I've been trying to familiarize myself with IPv6 and one thing that's left me hanging is the benefit of multicasting over broadcasting in IPv6. To use Neighbor Discovery Address Resolution as an example, I understand that nodes will use the solicited-node multicast address when trying to map an IP address to its corresponding MAC address, but how this actually reduces unnecessary processing by other nodes on the same link is not immediately clear to me.
It seems that to fully maximize the utility of multicasting, we need both a router that speaks Multicast Listener Discovery (MLD) AND a switch supporting MLD snooping. We need the router so that MLD is active on the network and the "smart" switch to keep track of which interfaces are associated with which multicast addresses.
Otherwise, if we do NOT have a router speaking MLD or our switch does NOT support MLD snooping, then, sure, neighbor solicitations will be directed at the solicited-node multicast address, but any potential savings in network chatter will be negated when the switch just broadcasts out all ports.
And if what I say is true, does this mean that for almost all networks, especially consumer/soho networks, there will be virtually no benefit by switching over from ARP-based broadcast to ND-based multicast?
Does a network with switches that do not include MLD snooping treat multicast the same as broadcast and therefore negate the benefits of multicast? As for your second point, forgive me as I am pretty new to all this, but why would an unwanted multicast be less disruptive than a broadcast? If we take the example of ARP, another node sees the broadcast ARP frame, sees it is not referring to itself, and drops it. In ND, the neighbor sees the multicasted solicitation (because it has been broadcasted by the switch), and drops?