Users Guide

Neighbor Discovery Protocol (NDP)

The neighbor discovery protocol for IPv6 is dened in RFC 2461 as part of the Stateless Address Autoconguration protocol. It replaces the

Address Resolution Protocol used with IPv4. NDP denes mechanisms for solving the following problems:

• Router discovery — hosts can locate routers residing on a link

• Prex discovery — hosts can discover address prexes for the link

• Parameter discovery

• Address autoconguration — conguration 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 neighbor is no longer reachable on the link.

• Duplicate address detection (DAD) — allow a node to check whether a proposed address is already in use.

• Redirect — the router can inform a node about a better rst-hop.

NDP uses the following ve ICMPv6 packet types in its implementation:

• Router Solicitation

• Router Advertisement

• Neighbor Solicitation

• Neighbor Advertisement

• Redirect

Topics:

• clear ipv6 neighbors

• ipv6 neighbor

• show ipv6 neighbors

• IPv6 Router Advertisement (RA) Guard

clear ipv6 neighbors

Delete all entries in the IPv6 neighbor discovery cache or neighbors of a specic interface. Static entries are not removed using this

command.

Syntax

clear ipv6 neighbors [vrf vrf-name] [ipv6-address | interface]

Parameters

vrf vrf-name (OPTIONAL) Enter the keyword vrf followed by the name of the VRF to clear the

neighbor corresponding to that VRF.

NOTE: If you do not specify this option, the neighbors in the default VRF are

cleared.

964 Neighbor Discovery Protocol (NDP)