NDP (Neighbor Discovery Protocol)

NDP is IPv6’s mechanism for neighbor discovery, address resolution, and router discovery.

Updated: 2026-03-05

Definition

Neighbor Discovery Protocol (NDP) replaces ARP in IPv6 and uses ICMPv6 messages.

It supports neighbor discovery, router discovery, and address resolution on local links.

Key points

Uses ICMPv6
Replaces ARP for IPv6
Includes Router Advertisements and Neighbor Solicitation

Common mistakes

Filtering ICMPv6 too aggressively and breaking IPv6 functionality.
Ignoring IPv6 local-link security issues (RA spoofing).

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Related terms

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