Neighbor Discovery Protocol (NDP) for IPv6 performs functions similar to those provided by Address Resolution Protocol (ARP) for IPv4.
Neighbor Discovery for IP version 6 (IPv6). Hosts, routers, and firewalls use NDP to determine the link-layer addresses of neighbors on connected links, to keep track of which neighbors are reachable, and to update neighbors’ link-layer addresses that have changed. Peers advertise their own MAC address and IPv6 address, and they also solicit addresses from peers.
Palo Alto Networks firewalls support NDP and NDP Proxy on their interfaces. When you configure the firewall to act as an NDP Proxy for addresses, it allows the firewall to send Neighbor Discovery (ND) advertisements and respond to ND solicitations from peers that are asking for MAC addresses of IPv6 prefixes assigned to devices behind the firewall. You can also configure addresses for which the firewall will not respond to proxy requests (negated addresses).
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