Neighbor Discovery

The Neighbor Discovery Protocol is the name of a series of processes used by IPv6 for the purposes of Neighbor Discovery (a bit of recursive naming there, sorry!), Router Discovery and Neighbor Unreachability Detection (NUD). The actual act of Neighbor Discovery is how IPv6 nodes determine the L2 address (e.g. - MAC) for a known L3 address (e.g. - IPv6); very analogous to the function performed by ARP in IPv4.