IPv6: 6to4 tunnel randomly cutting out on 2.6.8.1 - any patches?

Philip Pemberton
2007-05-17T21:15:33Z

Hi,
I'm currently trying to set IPv6 up on a Linux-based router. The
aforementioned router runs kernel 2.6.8.1, and just about all the hardware
driver modules are binary modules. For the record, I'd love to upgrade the
router to one of the newer kernels, but AIUI I can't do it because I don't
have the source to the bmods. But anyway...

What I've done is set up an IPv6 subnet via the SixXS tunnel broker (and
I've also tried the BT Exact tunnel broker, which has the same problem). This
tunnel is then routed onto my LAN and set up router advertisement (with radvd)
so the machines can get access to the IPv6 side of the Internet.

The problem is that every 10 minutes or so, the IPv6 link (apparently the
routing side as the router can still ping kame.net, but the other machines on
the LAN can't) stops working for a few seconds (between 5 and 60) and comes
back up of its own free will. Running the tunnel on another machine (with a
2.6.16 kernel) stops the problem completely - IPv6 works perfectly. But being
the energy-conscious person I am, I'd prefer to have as few machines powered
up as possible.

When IPv6 stops working, ping returns the error "sendmsg: Network is
unreachable". The intermittent nature of this issue, and the fact that IPv6
works fine when I move routing to a machine with a later kernel, leads me to
believe that this may be an old kernel bug that got fixed in a later release,
but evidently not this one...

There appear to be a number of IPv6 related fixes in 2.6.9, but the patches
are all globbed together in a single "patch-2.6.9.bz2" file - I'd like to
apply some of the more promising ones directly, and try and fix the problem
that way. The problem being that I can't find these patches as individual
"this fixes X" releases, just as one huge 'go from 2.6.8.1 to 2.6.9' glob, and
the git repository on kernel.org only seems to go back to 2.6.11.

So what I'm wondering is, does anyone know if a bug like I've described was
ever found between 2.6.8.1 and 2.6.16, and if so how it can be fixed?