IPv6 on Deutsche Telekom very unstable, PPPoE reload dyfunctional since 23.1

[sbellon]

Hi all,

I have a virtual OPNsense running on Proxmox VE connected to a Draytek Vigor 167 on a VDSL100 from Deutsche Telekom running with dual stack.

Every few days there's a disconnect and sometimes afterwards IPv6 is dysfunctional (DHCPv6 is not runnig). With 22.7 I could use the DHCPv6 Reload button in Interfaces -> Overview -> WAN, but now with 23.1_6 this does not work for my any more. Even Reload PPPoE does not work reliably and I have to reboot everything.

My configuration:

WAN:
IPv4: PPPoE
IPv6: DHCPv6
Request only an IPv6 prefix
Prefix delegation size 56
Send IPv6 prefix hint
Use IPv4 connectivity

LAN:
IPv4: Static IP
IPv6: Track interface (WAN)

What kind of logs should I provide to further track this down? Pressing a "DHCPv6 Reload" button every now and then was "ok", but the situation right now is really starting to get a nuisance, I have to say. :-(

Edit: To clarify, my last sentence was not meant as a complaint against the developers. I understand how hard it is to cater for all scenarios, especially without the exact setup to reproduce the issues. It was rather meant to express how desperate I am and that I am willing to debug it in order to come to a solution once and for all.

[franco]

23.1_6 should work as 22.7 did. A problem with Telekom is that they seem to require a Dual-dual stack where you get an IPv6 via PPPoE and then you have to use that address to get a DHCPv6 delegated prefix.

Did you reboot since applying 23.1_6?


Cheers,
Franco

[sbellon]

Yes, I rebooted several times because that's currently how I can get back the IPv6 address.

[franco]

So it works for a while and then stops? Logs would be useful. Let's start with System: Log Files: General with "notice" level.

I think the main problem might be there is some sort of soft reset and afterwards you get the same address and some parts of the system do not reload although they should.


Cheers,
Franco

[sbellon]

It stops when there was a forced disconnect (mostly at night, sometimes daily, sometimes after two weeks, I have not yet detected a pattern).

Can I also just post /var/log/system/latest.log? Post it here or send it to you?

[meyergru]

23.1_6 should work as 22.7 did. A problem with Telekom is that they seem to require a Dual-dual stack where you get an IPv6 via PPPoE and then you have to use that address to get a DHCPv6 delegated prefix.

I do not have Telekom, my ISP really only gives me an IPv6 prefix, so if I request more, I get nothing at all.

However: If it is like you describe, then @sbellon should probably disable "request IPv6 prefix only" in order to be able to get the prefix for delegation.

[franco]

Prefix is always delegated if given, unless using advanced options. The actual IPv6 cones from PPPoE as I said. Assuming Telekom didn't change anything in the same time frame.

It would probably be beneficial to use Interfaces: Settings: Prevent release. Usually the infamous "Zwangstrennung" disconnects the line, but not the leases...


Cheers,
Franco

[meyergru]

What I meant is that if the IPv6 for the WAN interface itself comes from PPPoE, and in a second step the delegation prefix is fetched via IPv6, then in order to get that via IPv6, you must ask for a WAN IPv6 and exactly that is not being done when "Request only an IPv6 prefix" is checked on the WAN interface, as @sbellon wrote.

But as I said, I have a different ISP.

[sbellon]

Isn't there a "definitive" way of how to configure it for Deutsche Telekom dual stack? I think there must be some people out there using the intersection of Deutsche Telekom and OPNsense. ;-)

[franco]

I don't understand. If it worked before it should still work with PD and unchecking "Request only an IPv6 prefix" might not make it work at all with Telekom since they already funnel the address through PPPoE.

So: if you request an address and a prefix you get nothing.

[Patrick M. Hausen]

Deutsche Telekom, DSL/PPPoE - I get e.g.

Single address: 2003:a:d7f:d938:3eec:efff:fe00:5432 with a /64 prefix length on pppoe0
Prefix: 2003:a:d59:3800::/56

Kind regards,
Patrick

[sbellon]

And what IPv6 related settings are mandatory to have ticked or unticked to make it work reliably?

Remember: It's not that I do not get IPv6 at all. It's just that often after a "Zwangstrennung" I'm IPv4 only. With 22.7 a "Reload DHCPv6" in Interfaces Overview cured it, now with 23.1 it doesn't.

I now have additionally checked "Prevent release" - which I hadn't before, let's see whether that makes a difference.

[Patrick M. Hausen]

That's all I have:

[bringha]

Hi there

@sbellon I have exactly the same set up as you have and still the good old description of

https://forum.opnsense.org/index.php?topic=21839.0

fits also for 23.1 in so far. From my view close to the "definitive" way you seem to look for.

However, "Zwangstrennung" due to the many different reasons it is carried out from network side is a somewhat different animal which is hard to be addressed from client side in all its (often unknown and intransparent) cases. Zwangstrennung is done for maintenance, new customers on the same line bundle and after-optimization, incident resolution, construction work, and many more. Btw. also all my fritzboxes lost ipv6 after Zwangstrennung pretty often.

I can confirm that I saw also in several old versions of Opnsense that IPv6 did not come up properly after Zwangstrennung. I could then recover ipv6 by manually storing the WAN config again and ipv6 was back. Other than that, playing around with the settings on the client side did not bring any improvement for the Zwangstrennung case.

I also did not see that I got the same ipv6 prefix after a Zwangstrennung that I had before - was always different. 

Br br

[sbellon]

What puzzles me is this: @pmhausen says he has "Request only an IPv6 prefix" unticked, @bringha links to a thread where "Request only an IPv6 prefix" is ticked. @meyerguru says I should untick, @franco says it should stay ticked.

Surely there must be a definitive answer and not a 50:50 arm wrestling ... :-|