The IPv6 neighbor discovery (ND) multicast suppress feature stops as
many ND multicast neighbor solicit (NS) messages as possible by dropping them
(and responding to solicitations on behalf of the targets) or converting them
into unicast traffic. This feature runs on a layer 2 switch or a wireless
controller and is used to reduce the amount of control traffic necessary for
proper link operations.
When an address is inserted into the binding table, an address
resolution request sent to a multicast address is intercepted, and the device
either responds on behalf of the address owner or, at layer 2, converts the
request into a unicast message and forwards it to its destination.