IPv6 Neighbor Advertisement messages have a flag called
Override, see RFC4861. It toggles, whether the receiver of the message should remove other link-layer addresses for the same IPv6 target address from its cache. If the
Override flag is not set, the receiver will continue to use the link-layer address of the first matching Neighbor Advertisement it received. To avoid congestion, such Neighbor Advertisements should be delayed by a random amount of time, with a fixed upper bound.
This makes link-scope anycast addresses possible.
It looks to me like a mechanism for active-passive redundancy, but with no control (due to the random delay) over which link-layer address becomes the active destination, which makes it seem more like load-balancing. It reminds me of VRRP, but with less deterministic/controllable behavior.
My questions is: For what does it make sense to use such link-scope anycast addresses?