An IPv6 router uses the Multicast Listener Discovery (MLD) protocol to discover the presence of multicast listeners (clients) on its directly attached links and to specifically learn which multicast address the clients are interested in joining.
MLD: Select the option to create an instance for a selected interface.
MLD Enable: Select this option to enable MLD on a selected interface.
After you enable MLD, the MLD interface is in host mode by default.