Neighbor Discovery Protocol (NDP) for IPv6 is defined in RFC 2461 as part of the Stateless Address Autoconfiguration protocol. It replaces the Address Resolution Protocol used with IPv4. It defines mechanisms for solving the following problems:
- Router Discovery: hosts can locate routers residing on link.
- Prefix Discovery: hosts can discover address prefixes for the link.
- Parameter Discovery
- Address Autoconfiguration: configuration of addresses for an interface.
- Address Resolution: mapping from IP address to link-layer address.
- Next-hop Determination
- Neighbor Unreachability Detection (NUD): determine that a neighbour is no longer reachable on the link.
- Duplicate Address Detection (DAD): allows a node to check whether a proposed address is already in use.
- Redirect: router can inform node about better first-hop.
It makes use of the following five ICMPv6 packet types in its implementation.
- Router Solicitation
- Router Advertisement
- Neighbor Solicitation
- Neighbor Advertisement
- Redirect
