Neighbor Discovery Protocol

Protocol in the Internet Protocol Suite used with IPv6 / From Wikipedia, the free encyclopedia

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The Neighbor Discovery Protocol (NDP), or simply Neighbor Discovery (ND), is a protocol of the Internet protocol suite used with Internet Protocol Version 6 (IPv6).[1] It operates at the link layer of the Internet model,[2][3] and is responsible for gathering various information required for network communication, including the configuration of local connections and the domain name servers and gateways.[4]

Quick facts: Purpose, Developer(s), Introduction, OSI laye...
Neighbor Discovery Protocol
Communication protocol
When defining its messages, NDP follows ICMPv6 message format.
PurposeAuxiliary protocol for IPv6
Developer(s)Internet Engineering Task Force
IntroductionMarch 1996; 27 years ago (1996-03)
OSI layerNetwork layer

The protocol defines five ICMPv6 packet types to perform functions for IPv6 similar to the Address Resolution Protocol (ARP) and Internet Control Message Protocol (ICMP) Router Discovery and Router Redirect protocols for IPv4. It provides many improvements over its IPv4 counterparts (RFC 4861, section 3.1). For example, it includes Neighbor Unreachability Detection (NUD), thus improving robustness of packet delivery in the presence of failing routers or links, or mobile nodes.

The Inverse Neighbor Discovery (IND) protocol extension (RFC 3122) allows nodes to determine and advertise an IPv6 address corresponding to a given link-layer address, similar to Reverse ARP for IPv4.

The Secure Neighbor Discovery Protocol (SEND), a security extension of NDP, uses Cryptographically Generated Addresses (CGA) and the Resource Public Key Infrastructure (RPKI) to provide an alternative mechanism for securing NDP with a cryptographic method that is independent of IPsec. Neighbor Discovery Proxy (ND Proxy) (RFC 4389) provides a service similar to IPv4 Proxy ARP and allows bridging multiple network segments within a single subnet prefix when bridging cannot be done at the link layer.