Querying IPv6 prefix delegation status

Hi Steve,

From your post I understand that you have IPv6 configuration with DHCPv6 prefix delegation and you want to find out what prefix lenght you receive from the delegation ? Prefix hint is set to /60 but you suspect that the interfaces receive a different one.

There has been a change between FortiOS 7.0.1 and 7.0.2 where the prefix-delegation is set on different config sub-menu. You can check the CLI reference here:

https://docs.fortinet.com/document/fortigate/7.0.2/cli-reference/8620/config-system-interface

The new menu is called "config dhcp6-iapd-list". So if you are using 7.0.2 or later you have to configure the prefix-hint in that menu. Normally following the upgrade path this configuration is migrated to the new firmware.

I guess your wan1 configuration looks right now similar to the example below?

config system interface
    edit "wan1"
        config ipv6
            set ip6-mode dhcp
            set ip6-allowaccess ping
            set dhcp6-prefix-delegation enable
            set dhcp6-prefix-hint ::/60
            end

You can use CLI command below to list all details you need:

config system interface

edit wan1

get

.... (truncated for brevity)

delegated-domain :
    dhcp6-prefix-hint : ::/60
    dhcp6-prefix-hint-plt: 604800
    dhcp6-prefix-hint-vlt: 2592000
    vrrp-virtual-mac6 : disable
    vrip6_link_local : ::
    ip6-dns-server-override: enable 

Here you can see the prefix delegation details etc.

Please let me know if there is something else or this was the right solution you are looking for.

Best regards,

Vasil

My customer who has the questionable configuration won't be back until next week, but I'd be disappointed if FortiGate reported the *actual* prefix as a "hint", which is what I think you're suggesting. We'll find out in a day or two.