Neighbor Discovery Protocol (NDP), as defined in RFC 2461, Neighbor Discovery for IP Version 6 (IPv6), is a key protocol of IPv6. Moreover, Figure 3-3 illustrates that NDP is an umbrella that defines these mechanisms:
Replacement of ARP— Because ARP has been removed in IPv6, IPv6 provides a new way to determine link-layer addresses of nodes on the local link. This new mechanism uses a mix of ICMPv6 messages and multicast addresses.
Stateless autoconfiguration— This mechanism allows nodes on the local link to configure their IPv6 addresses by themselves by using a mix of ICMPv6 messages and multicast addresses.
Router redirection— The router sends ICMPv6 messages to an IPv6 node to inform it of the presence of ...