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 is not guaranteed to discover all devices
because there could be other networking devices between the firewall
and the client that filter out NDP or Duplicate Address Detection
(DAD) messages. The firewall can monitor only the devices that it
learns about on the interface.
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