Re: ipv6 connectivity issues after update to 20260707 userland

[Greg Troxel <gdt%lexort.com@localhost>]

Thomas Klausner <wiz%netbsd.org@localhost> writes:

> After updating my NetBSD kernel + userland to 20260707, one of the new
> problems I saw was that I had no IPv6 connectivity any longer.
>
> Replacing the kernel with the previous one didn't change anything.
>
> So now I also tried replacing the userland with the 20260626 one, and
> my IPv6 connectivity is back (directly after a reboot, and previous
> reboots with kernel changes didn't change anything).
>
> I've compared 'ifconfig -a' between working and non-working, the only
> difference is for tap0 and the order of the inet6 entries for my main
> network interface changed.
>
> 'route show' shows two more hosts on the newer kernel+userland, and
> the 'default' Gateway has a different address, the XXXX:XX bytes
> differ in the "fe80::XXXX:XXff:fe".

Two debugging paths:

  shut down all daemons to make traffic minimal
  Run tcpdump -n on the main interface
  run it also on another machine on the same link (that's the v6 term; ethernet)
  ping6 the configured address of the other machine
  ping6 the link-local addr (flipping %wm0 as necessary)
  grovel over tcpdump output

  bisect to find the breaking commit


(I don't have a current box this minute; I'm about to give up on 9/amd64
and re-assign the domU resources to current.)