Debug IPv6 issues after PPPoE reconnect (LAN loses IPv6)

[norg]

I updated to 19.7 and so far everything quite nice, thanks. But this issue is still the same for me, so quoting myself from  (https://forum.opnsense.org/index.php?topic=13375.0):

Hi,

I have a VDSL Telekom uplink with a static IPv4 and IPv6 where the latter offers me a /56 IPv6 network. This works very well if I start the OPNSense or after I configure the LAN interface. So the LAN interface takes care of requesting the IPv6 network information and forwards this to the client.
Sometimes when the VDSL uplink is gone (power outage, other issues) and reconnects the VDSL uplink interface receives the IPv4 and also the IPv6 for the WAN side but it doesn't update the LAN interface which has lost the IPv6 information in the meantime.

My workaround for now is to go to the LAN interface in the WebUI, don't change anything, just click save and apply changes (although none have happened) and thus the interface is reconfigured again and IPv6 works again.

So there seems to be an issue with the LAN interface noticing the WAN interface gone and back online. Can you give me any hints how I could further debug this, increase log messages or which parts are involved?
If anyone know a solution even better
But I guess I need to dig into this deeper to provide you with necessary details to properly fix this issue.
So it would be helpful for me to know which parts/scripts/services are involved so I can try if I can fix it myself.

Thanks

So any hints how to solve/fix/patch it myself are welcome

[bartjsmit]

Do you have the LAN interface on a static IPv6 address with its own /64 internal subnet?

Do you run RADVD to send out router advertisements on your LAN subnet?

Bart...

[norg]

Do you have the LAN interface on a static IPv6 address with its own /64 internal subnet?

No, I did set the current options:

• IPv6 Interface: VDSL (my primary WAN uplink)
• IPv6 Prefix ID: 0x24
• Manual Configuration: Allow manual adjustments of DHCPv6 and RA (checked)

And I have range defined at the DHCPv6 section.
[/list]

Do you run RADVD to send out router advertisements on your LAN subnet?

Services: RA for the LAn is set to:

• RA: Stateless
• Priority: Normal
• Advertise Default Gateway

[Maurice]

Since you always get the same prefix from your ISP, you don't really need tracking and can just configure the LAN interface(s) statically. That should work more reliably.

OPNsense unfortunately is still quite fuzzy when it comes to IPv6 prefix tracking. You might want to check the various related issues on GitHub and comment there. For example, #3415 has been closed, but never really resolved.

Cheers

Maurice

[bartjsmit]

Since you always get the same prefix from your ISP, you don't really need tracking and can just configure the LAN interface(s) statically. That should work more reliably.

Exactly that 

I use subnets within my range for the various internal networks and have clients craft SLAAC addresses with RA.

Bart...

[norg]

Since you always get the same prefix from your ISP, you don't really need tracking and can just configure the LAN interface(s) statically. That should work more reliably.

Didn't thought of that, I w ill try this out.

Thanks

Nevertheless it would be nice to know more about the internals, but I guess I have to dig into the code a bit more.