Technical Tip: How to add static ARP entry in IPv4 and Neighbor Cache in IPv6

[athirat]

Description

This article describes the commands to add the ip-mac address binding in both IPv4 and IPv6.

Scope

FortiGate.

Solution

Using the FortiGate CLI.

For IPv4:

config system arp-table

    edit %value%
        set interface <interface-name>
        set IP
        set mac
    end

For example:

config system arp-table

    edit  1
        set interface internal
        set ip 192.168.1.50
        set mac 00:50:5A:20:14:1E
    end

For IPv6:

diagnose ipv6 neighbor-cache add <interface-name> <ipv6 address> <mac-address>

For example:

diagnose ipv6 neighbor-cache add port1 2001:660:7220:83cf:172:20:0:102 78:48:59:61:52:3d

Verification of Configuration and Troubleshooting:
To verify the existing ARP entries in IPv4:

get system arp

Address            Age(min)         Hardware Addr               Interface
192.168.1.50            -                00:50:5a:20:14:1e           internal   <-----
10.1.1.2                     0               04:09:ff:09:c6:23            wan

To verify the existing Neighbor Cache entries in IPv6:

diagnose ipv6 neighbor-cache list

ifindex=3 ifname=port1 2001:660:7220:83cf:172:20:0:102 78:48:59:61:52:3d state=00000080 use=942 confirm=942 update=942 ref=0