TL;DR - how can I tell the *actual* IPv6 prefix delegated from the upstream?
A customer's 60E is running FortiOS 7, the prefix-hint asks for a /60 from the WAN1 upstream, but it doesn't seem to be getting that prefix, but I can't find any place where I can discover what was actually provided by the upstream other than to see it's not working.
I have a 60F at home, I believe I'm actually getting the /56 I ask for, but I can't find that anywhere either.
I have been all over the CLI and cannot find any place to show what's going on with prefix delegation. Is there a place to do this without diving into debug mode and restarting the interface to see whatever might negotiate? There has to be a way.
Note that "diagnose ipv6 address list" does *not* show this information as far as I can tell.
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:
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:
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.