ND allows mapping between network-layer IPv6 address and link-layer MAC addresses to ensure communication on an Ethernet.
The Neighbor Discovery (ND) protocol is an important part of the Internet Protocol suite used with IPv6. NDP in IPv6 is a replacement of Address Resolution Protocol (ARP) and ICMP Router Discovery (RD) in IPv4. NDP uses ICMPv6 packets to implement functions including RD, duplicate address detection (DAD), address resolution, neighbor unreachability detection (NUD), and redirection.