Hello, My tunnel containing 2001:16d8:ee1c::/48 seems to have two problems that may or may not be related. First: Path MTU discovery from the outside (2001:700:300:1880::2, for instance) is broken. I'm SSH-ing to a host (from which I have working connectivity to from several different places around the world), and when I'm trying to connect to my screen the connection freezes. tcpdump on the sender shows the machine sending packets like this: 00:25:13.209037 IP6 2001:700:300:1880::2.22 > 2001:16d8:ee1c:0:213:2ff:feaa:9cd8.48591: . 1891122625:1891124053(1428) ack 2699540521 win 107 <nop,nop,timestamp 650949801 4294933753> However, the receiving router sees no such packets on its sixxs interface, and no ICMPv6 Packet Too Big packets are returned either. Second, the PoP seems to have a routing loop somewhere. For instance, ping6 www.sixxs.net gives: PING www.sixxs.net(noc.sixxs.net) 56 data bytes From 2001:16d8:1:1334::69 icmp_seq=1 Time exceeded: Hop limit From 2001:16d8:1:1334::69 icmp_seq=2 Time exceeded: Hop limit From 2001:16d8:1:1334::69 icmp_seq=3 Time exceeded: Hop limit and a tracepath6 shows: fugl:~> tracepath6 www.sixxs.net 1?: [LOCALHOST] pmtu 1500 1: 2001:16d8:ee1c::1 2.305ms 1: 2001:16d8:ee1c::1 2.354ms 2: 2001:16d8:ee1c::1 2.247ms pmtu 1280 2: gw-46.osl-01.no.sixxs.net 5.450ms 2: gw-46.osl-01.no.sixxs.net 5.357ms 3: 2002-sixxs.cr0-r23.ver-osl.no.ip6.p80.net 5.880ms 4: no reply 5: 2001:16d8:1:1334::65 20.604ms asymm 3 6: no reply 7: 2001:16d8:1:1334::65 21.947ms asymm 3 8: no reply 9: 2001:16d8:1:1334::65 29.863ms asymm 3 10: 2001:16d8:1:1334::69 34.915ms asymm 4 11: 2001:16d8:1:1334::65 35.705ms asymm 3 12: 2001:16d8:1:1334::69 41.789ms asymm 4 13: 2001:16d8:1:1334::65 41.816ms asymm 3 14: 2001:16d8:1:1334::69 48.922ms asymm 4 15: 2001:16d8:1:1334::65 48.960ms asymm 3 16: 2001:16d8:1:1334::69 56.502ms asymm 4 17: 2001:16d8:1:1334::65 56.415ms asymm 3 ^C This may or may not be the reason for the ICMPv6 Packet Too Big packets not coming back. Could you please take a look?