Apr 21 21:24 2014, Michiel van der Vlist wrote to Markus Reschke:
MvdV> There must be more to it than just a temporary bad line or MvdV> congestion. The problem is persistent. I can not make an IPv6 MvdV> connection with BjЎrn via my SixXs tunnel. Ever since 18 April, MvdV> early in the morning. That coяncides with the time that his tunnels MvdV> were flagged as down by SixXs, but actually still working.
Has he reset the tunnel already? If a reset fixes the problem it would be an IGP problem caused by a forgotten tunnel.