Neighbor Discovery Protocol (NDP)

Neighbor Discovery Protocol, or NDP, is a fundamental protocol for communication in IPv6 networks. It is based on the Internet Control Message Protocol for IPv6, or ICMPv6, and provides several functions that are handled by ARP and additional mechanisms in IPv4. NDP enables devices to determine the link-layer addresses of neighbouring systems, discover available routers and obtain network prefixes and other configuration information. It also supports neighbour reachability detection and Duplicate Address Detection to identify IPv6 addresses that are already in use. Key message types include Neighbor Solicitation, Neighbor Advertisement, Router Solicitation and Router Advertisement. NDP is therefore an essential component of automatic configuration and communication within modern IPv6 networks.