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Can the fe80 link-local address be determined by other means? Just thinking about anyone not using pfSense/OPNSense routers (me as an example - I'm using a UDM-Pro)
Lit Fibre
- Thread starter bimbleuk
- Start date
I'm not too familar with Ubiquity equipment (although I'd very much like to get the chance to). I'm sure you'll have the ability on your router to perform a network capture on a particular network interface. If you turn off DHCPv6 on your WAN interface, start the network capture and then turn DHCPv6 back on again you should be able to capture the detail.
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Thanks @pingloss - I'll leave this to someone who knows how. I wouldn't know where to start! 
Is the method of picking up the IPv6 gateway based on where the DHCP response came from even an RFC? I'm wondering how the Lit-supplied router is doing it and whether it's a DHCPv6 fallback method or whether they've just lucked out with having two non-standard ways of doing something work together.
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Thanks! I'll take a look
I've been reading here: https://www.rfc-editor.org/rfc/rfc4861#section-6 and can't find anything that references a DHCPv6 fallback method
@Caged I wonder if they're doing something similar to this
DHCPv6 client and default gateway - MikroTik
forum.mikrotik.com
Edit: it seems it's exactly what they are doing. A quick and dirty out of RFC spec workaround
Odhcp6c installs bogus default route via DHCPv6 server
When booting OpenWrt 23.05.2 using a DHCPv6 server on the network segment, it appears that odhcp6c installs a default route via the interface on the DHCPv6 server (ending :f20a) when the address first eth0.2 bound (as per a dump using /etc/odhcp6c.user)...
forum.openwrt.org
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If the Lit-supplied router uses odhcp6c then I think we have the answer - presumably someone can packet capture the WAN port and see if it mentions that in the DHCPv6 request. The maintainers of that project are clear that it's a workaround for broken implementations.
There's nothing specific in the request and response but that's not to say these MitraStar routers aren't doing something similar where the logic is
If ICMPv6 RA exists then use this for default gateway
else
use DHCPv6 server address for default gateway
I've sent my email off to LitFibre asking why ICMPv6 isn't seemingly being used correctly.
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Interestingly I encountered the same problem as Lit changed my static IPv4 last night and at the same time broke IPv6 connectivity. @pingloss Great work on identifying the GW address, this worked for me also but its interesting to note that we both share the same fe80 link-local gateway address (fe80::a05:e2ff:feb0:9e8f). IPv6 is confusing but as this is a link local address, my guess is that this can be the same for multiple customers and therefore may well be the same for everyone on Lit's network. I have also contacted support but they completely ignored my question but did confirm that we have now all been allocated a /48 instead of a /62.
@JameZUK I’m guessing it’s going to the same DHCP server link local address for particular segments of their network.
I’m hoping that enough users log tickets for them to take notice. I’ve not had a response as yet to my email explicitly asking why the correct standards aren’t being implemented.
I’m hoping that enough users log tickets for them to take notice. I’ve not had a response as yet to my email explicitly asking why the correct standards aren’t being implemented.
Just received the following reply from the LitFibre support team:
Since our recent maintenance a few changes were introduced in our network to ensure flexibility, scalability and robustness. As part of this we slightly changed the way our IPv6 allocation works. For one, our prefix delegation is /48 rather than /62.
As a whole all the IPv6 related changes are designed to be transparent for the local routers and they should continue to obtain all their settings automatically. While RA is widely used for neighbor discovery and route advertisement, it is not the only applicable way to achieve this in general. Our Engineering team did some fine tuning on our network that should allow you to get the correct IPv6 settings moving forward. All you need to do is reboot your equipment to pick up the new config.
Currently we don't have a specific guide on how to set IPv6 on a third party router (as mentioned, it should have been picked automatically), but we'll work to get this done.
Please let us know if this answers your questions. Also, if you continue experiencing problems even after rebooting your equipment, do let us know if you would be available for a call so we can troubleshoot (at a convenient time for you when you would have access to restart your devices again).
Since our recent maintenance a few changes were introduced in our network to ensure flexibility, scalability and robustness. As part of this we slightly changed the way our IPv6 allocation works. For one, our prefix delegation is /48 rather than /62.
As a whole all the IPv6 related changes are designed to be transparent for the local routers and they should continue to obtain all their settings automatically. While RA is widely used for neighbor discovery and route advertisement, it is not the only applicable way to achieve this in general. Our Engineering team did some fine tuning on our network that should allow you to get the correct IPv6 settings moving forward. All you need to do is reboot your equipment to pick up the new config.
Currently we don't have a specific guide on how to set IPv6 on a third party router (as mentioned, it should have been picked automatically), but we'll work to get this done.
Please let us know if this answers your questions. Also, if you continue experiencing problems even after rebooting your equipment, do let us know if you would be available for a call so we can troubleshoot (at a convenient time for you when you would have access to restart your devices again).
As you say it shows as "we haven’t planned your area at the moment". I'll check after the 14th to see.
Snap, not been with them 3 years yet but this will be my third static IP address. Wonder what defines static these days
Same "not planned" from the checker. I'm in North Wilts
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