Neighbor Discovery Protocol (NDP) for IPv6 (RFC 4861) performs functions similar to ARP functions for IPv4. The firewall by default runs NDP, which uses ICMPv6 packets to discover and track the link-layer addresses and status of neighbors on connected links.

Enable NDP Monitoring so you can view the IPv6 addresses of devices on the link local network, their MAC address, associated username from User-ID (if the user of that device used the directory service to log in), reachability Status of the address, and Last Reported date and time the NDP monitor received a Router Advertisement from this IPv6 address. The username is on a best-case basis; there can be many IPv6 devices on a network with no username, such as printers, fax machines, servers, etc.

If you want to quickly track a device and user who has violated a security rule, it is very useful to have the IPv6 address, MAC address and username displayed all in one place. You need the MAC address that corresponds to the IPv6 address in order to trace the MAC address back to a physical switch or Access Point.

NDP monitoring also monitors Duplicate Address Detection (DAD) packets from clients and neighbors. You can also monitor IPv6 ND logs to make troubleshooting easier.

NDP monitoring is supported for Ethernet interfaces, subinterfaces, Aggregated Ethernet interfaces, and VLAN interfaces on all PAN-OS models.