Dear Sir, The tunnel seems to be enabled and up but we can not ping6 the PoP IPv6 (error : Destination unreachable: Address unreachable). The tcpdump (see logs behind) shows the echo request (packet IPv6 in IPv4 with proto 41) goes out but in response we have an ICMP error from the PoP IPv4 (protocol 41 unreachable). It seemes that everything is ok on our side Could you help us please ? Thank you Regards David Lamotte Please find my configuration : ---------------------------- Username : DLX1-SIXXS Tunnel ID : T16349 PoP Name : bebru02 PoP Location : Brussels, Belgium PoP IPv4 : 193.190.198.32 Your Location : mons, Belgium Your IPv4 : 193.190.194.194 IPv6 Prefix : 2001:6a8:200:1d::1/64 PoP IPv6 : 2001:6a8:200:1d::1 Your IPv6 : 2001:6a8:200:1d::2 Created : 2008-07-30 09:04:09 CEST State : Enabled OS type : ------- Debian GNU/Linux 4.0 (etch) Linux fw 2.6.18-6-686 #1 SMP Fri Jun 6 22:22:11 UTC 2008 i686 GNU/Linux interface : --------- sixxs Lien encap:IPv6-dans-IPv4 adr inet6: 2001:6a8:200:1d::2/64 Scope:Global adr inet6: fe80::c1be:c2c2/128 Scope:Lien UP POINTOPOINT RUNNING NOARP MTU:1280 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:27 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 lg file transmission:0 RX bytes:0 (0.0 b) TX bytes:3348 (3.2 KiB) routing table : ------------- fw:~# ip -6 route show 2001:6a8:200:1d::/64 via :: dev sixxs metric 256 expires 21332930sec mtu 1280 advmss 1220 hoplimit 4294967295 fe80::/64 dev eth0 metric 256 expires 17518501sec mtu 1500 advmss 1220 hoplimit 4294967295 fe80::/64 dev eth1 metric 256 expires 17518501sec mtu 1500 advmss 1220 hoplimit 4294967295 fe80::/64 dev eth2 metric 256 expires 17518501sec mtu 1500 advmss 1220 hoplimit 4294967295 fe80::/64 via :: dev sixxs metric 256 expires 21332930sec mtu 1280 advmss 1220 hoplimit 4294967295 ff00::/8 dev eth0 metric 256 expires 17518501sec mtu 1500 advmss 1220 hoplimit 4294967295 ff00::/8 dev eth1 metric 256 expires 17518501sec mtu 1500 advmss 1220 hoplimit 4294967295 ff00::/8 dev eth2 metric 256 expires 17518501sec mtu 1500 advmss 1220 hoplimit 4294967295 ff00::/8 dev sixxs metric 256 expires 21332930sec mtu 1280 advmss 1220 hoplimit 4294967295 default via 2001:6a8:200:1d::1 dev sixxs metric 1024 expires 21332930sec mtu 1280 advmss 1220 hoplimit 4294967295 ping PoP IPv4 (OK) : ------------- w:~# ping 193.190.198.32 PING 193.190.198.32 (193.190.198.32) 56(84) bytes of data. 64 bytes from 193.190.198.32: icmp_seq=1 ttl=58 time=5.46 ms 64 bytes from 193.190.198.32: icmp_seq=2 ttl=58 time=6.38 ms ping my IPv6 (OK) : ------------ fw:~# ping6 2001:6a8:200:1d::2 PING 2001:6a8:200:1d::2(2001:6a8:200:1d::2) 56 data bytes 64 bytes from 2001:6a8:200:1d::2: icmp_seq=1 ttl=64 time=0.096 ms 64 bytes from 2001:6a8:200:1d::2: icmp_seq=2 ttl=64 time=0.073 ms ping PoP IPv6 (NO) : ------------- fw:~# ping6 2001:6a8:200:1d::1 PING 2001:6a8:200:1d::1(2001:6a8:200:1d::1) 56 data bytes fw:~# tcpdump -n -i eth2 proto 41 ---------------------------------- 08:48:12.210088 IP 193.190.194.194 > 193.190.198.32: IP6 2001:6a8:200:1d::2 > 2001:6a8:200:1d::1: ICMP6, echo request, seq 1, length 64 08:48:13.210961 IP 193.190.194.194 > 193.190.198.32: IP6 2001:6a8:200:1d::2 > 2001:6a8:200:1d::1: ICMP6, echo request, seq 2, length 64 08:48:14.210863 IP 193.190.194.194 > 193.190.198.32: IP6 2001:6a8:200:1d::2 > 2001:6a8:200:1d::1: ICMP6, echo request, seq 3, length 64 08:48:15.210749 IP 193.190.194.194 > 193.190.198.32: IP6 2001:6a8:200:1d::2 > 2001:6a8:200:1d::1: ICMP6, echo request, seq 4, length 64 08:48:16.210644 IP 193.190.194.194 > 193.190.198.32: IP6 2001:6a8:200:1d::2 > 2001:6a8:200:1d::1: ICMP6, echo request, seq 5, length 64 fw:~# tcpdump -n -i eth2 icmp ------------------------------ 08:58:14.378523 IP 193.190.198.32 > 193.190.194.194: ICMP 193.190.198.32 protocol 41 unreachable, length 132 08:58:15.378118 IP 193.190.198.32 > 193.190.194.194: ICMP 193.190.198.32 protocol 41 unreachable, length 132 08:58:16.377438 IP 193.190.198.32 > 193.190.194.194: ICMP 193.190.198.32 protocol 41 unreachable, length 132 08:58:17.378103 IP 193.190.198.32 > 193.190.194.194: ICMP 193.190.198.32 protocol 41 unreachable, length 132