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Neighbor discovery protocol

Neighbor discovery protocol

(also NDP)

Neighbor discovery protocol definition

Neighbor discovery protocol (NDP) is a network protocol used in IPv6-based networks to discover and manage neighboring devices. It replaces the address resolution protocol used in IPv4 networks. NDP is a fundamental part of IPv6 networking. It has several essential functions, including neighbor discovery, address autoconfiguration, and router discovery.

See also: address resolution protocol cache, IPv4

Here’s a short summary of what it does:

  • When a device (like your computer or smartphone) joins a network, it uses NDP to find out who else is connected to the same network.
  • NDP helps devices find each other, exchange data, and keep the connection — this way, they can collaborate and communicate faster in the future.
  • NDP enables devices to automatically configure their IPv6 addresses, so there’s no need for you to configure it manually.
  • NDP helps identify routers on the local link, allowing devices to pick the best gateway for outgoing traffic.
  • NDP ensures that no two devices on the same network use the same IPv6 address.

However, NDP does have some disadvantages:

  • NDP is rather tricky to configure and troubleshoot in larger networks.
  • It has limited backward compatibility — IPv4 devices cannot directly use NDP. If the network at your enterprise uses both IPv4 and IPv6, you will need to use transition technologies.
  • If not properly secured, NDP has some vulnerabilities that can be exploited by cybercriminals, including neighbor spoofing and denial-of-service attacks.

Further reading

Ultimate digital security