The Neighbor Discovery (ND) protocol enables hosts and routers to discover the presence of neighboring IPv6 hosts and routers. ND also helps in identifying the link-layer address of hosts and routers and in performing Duplicate Address Detection (DAD). ND replaces the IPv4 protocols, such as the Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP) Router Discovery, and ICMP Redirect.
| Mechanism | Description |
|---|---|
| Router discovery | How hosts find routers that reside on an attached link. |
| Prefix discovery | How hosts discover the set of address prefixes that define which destinations are on-link for an attached link. |
| Parameter discovery | How hosts discover operating parameters such as link MTU and default hop limit for outgoing packets. |
| Address autoconfiguration | How hosts and routers automatically configure an address for an interface |
| Address resolution | How hosts and routers determine the link-local address of a neighbor by using the IPv6 address of the neighbor. |
| Next-hop determination | How hosts and routers determine the IPv6 address of a neighbor to which a packet should be sent, by using the destination address. The next hop can be either the destination address or a router address. |
| Neighbor Unreachability Detection | How hosts and routers determine that a neighbor is no longer reachable. |
| Duplicate Address Detection | How hosts and routers determine that an address considered for use is not already in use by a neighbor. |
| Redirect | How a router informs a host of a better first-hop router to reach a particular destination. |