When multicast is supported at IPv6 level, it is often broadcasted at lower levels. For example an Ethernet switch will broadcast multicast traffic on all ports, even if only one host wants to receive it. As it is not acceptable that an entire Ethernet segment gets flooded, the MLD snooping solution was proposed and is already implemented in some Ethernet switches. This solution is similar to IGMP snooping proposed for IPv4.

When the switch implements IGMP snooping, it will detect all MLD messages exchanged on the link and will maintain a table indicating for each of the interfaces, what IPv6 multicast groups should be forwarded. This simple solution easily prevents multicast flooding on an Ethernet link, but this requires complex processing on switches, that were not initially designed for this kind of task.