No request for Prefix Delegation after WAN upstream fail

[k6tu]

I apologize in advance if this should have been added to another thread such as this one:

pfSense fails to restore IPV6 after WAN side service interruption

but the referenced bug tracker item is marked as resolved in 21.02-RELEASE-p1 which I am running.

If the WAN modem gets rebooted (either by the ISP or by me), no Prefix gets requested and ipv6 has no connectivity from the LAN side.

If I take the WAN interface down and back up, connectivity is immediately restored.

I have taken packet captures after a modem reboot and also after toggling the WAN interface on pfSense but can't see any different behavior from the modem.

As referenced in some other similar threads, I have removed my ipv6 configuration from pfSense, rebooted then reconfigured a couple of times but the behavior remains the same - 100% reproducible on a modem reboot.

I have a v6 address assigned as a monitor IP on the v6 WAN route.

My DHCP v6 Server/RA is configured as Managed.

Does anyone have any recommendations or pointers to get to the bottom of this?

I have static IPv4 addresses from the ISP and the v4 connectivity starts back up correctly on a modem reboot - but the v6 behaves as described above.

Thanks
Stu

[JKnott]

@k6tu

If the modem is rebooted, then the Ethernet disconnect should be noticed by pfsense and DHCPv6 restarted when it's reconnected.

[k6tu]

@jknott From looking at the pfSense System/general log, it does BUT...

When the modem reboots, the Ethernet is disconnected for about 90 seconds. When it comes back, the modem "bounces" the interface...

t0 - modem reboots, Ethernet goes DOWN for ~90 seconds
(t1) t0 + 90 - Ethernet event UP
(t2) t1 + 32 - Ethernet event DOWN
(t3) t2 + 3 - Ethernet event UP

from the log the clean up process on the link DOWN doesn't get to complete before the interface comes back up after the bounce.

You can see this in the screen capture of this portion of the log... this is the only thing I can see that is different from the interface toggle...

Stu

[k6tu]

Well, with apologies for the noise level, I found a "fix" - I enabled "Do not wait for a RA" on the WAN interface, rebooted the modem and now recovery is complete without having to toggle the interface.

I am stumped why this makes any difference as the modem clearly is sending out RAs after its reboot.

I can see from the System logs that dhcp6 client is started without RA mode - consistent with how its now configured! :-) and sends a solicit and gets an advertise back - which then kicks the PD process off.

Stu