Discovering Neighbor Link Addresses with NDP NS and NA

NDP defines a second pair of matched solicitation and advertisement messages: the neighbor solicitation (NS) and neighbor advertisement (NA) messages. Basically, the NS acts like an IPv4 ARP request, asking the host with a particular unicast IPv6 address to send back a reply. The NA message acts like an IPv4 ARP Reply, listing that host’s MAC address.

The process of sending the NS and NA messages follows the same general process as RS and RA: The NS message asks for information and the NA supplies the information. The most obvious difference is that while RS/RA focuses on information held by routers, NS/NA focuses on information that could be held by any IPv6 host. Also, note that the NS ...

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