We have switched tunnel T19624 from dynamic AICCU to static 6in4 configuration. State says 'Enabled' on site, but I don't get any traffic back from IPv4 PoP address in other words - tunnel is not working :( On my side there is Debian box (everything was the same / only aiccu has been shutdown and 6in4 has been configured) <configuration> auto sixxs iface sixxs inet6 v4tunnel address 2001:15c0:65ff:20b::2 netmask 64 endpoint 212.18.63.73 local 89.143.223.18 ttl 64 gateway 2001:15c0:65ff:20b::1 up ip link set mtu 1480 dev sixxs </configuration> Interface 'sixxs' is up & running sixxs Link encap:IPv6-in-IPv4 inet6 addr: 2001:15c0:65ff:20b::2/64 Scope:Global inet6 addr: fe80::598f:df12/128 Scope:Link UP POINTOPOINT RUNNING NOARP MTU:1480 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:2885 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:357660 (349.2 KiB) routing table: 2001:15c0:65ff:20b::1 dev sixxs metric 1024 mtu 1480 advmss 1420 hoplimit 4294967295 2001:15c0:65ff:20b::/64 via :: dev sixxs metric 256 mtu 1480 advmss 1420 hoplimit 4294967295 fe80::/64 via :: dev sixxs metric 256 mtu 1480 advmss 1420 hoplimit 4294967295 default via 2001:15c0:65ff:20b::1 dev sixxs metric 1024 mtu 1480 advmss 1420 hoplimit 4294967295 when ICMP pinging IPv6 POP gateway (2001:15c0:65ff:20b::1) I don't get any reply what so ever. <tcpdump uplink interface> 23:07:06.998590 IP 89.143.223.18 > 212.18.63.73: IP6 2001:15c0:65ff:20b::2 > 2001:15c0:65ff:20b::1: ICMP6, echo request, seq 2974, length 64 23:07:07.998612 IP 89.143.223.18 > 212.18.63.73: IP6 2001:15c0:65ff:20b::2 > 2001:15c0:65ff:20b::1: ICMP6, echo request, seq 2975, length 64 23:07:08.998608 IP 89.143.223.18 > 212.18.63.73: IP6 2001:15c0:65ff:20b::2 > 2001:15c0:65ff:20b::1: ICMP6, echo request, seq 2976, length 64 23:07:09.998609 IP 89.143.223.18 > 212.18.63.73: IP6 2001:15c0:65ff:20b::2 > 2001:15c0:65ff:20b::1: ICMP6, echo request, seq 2977, length 64 23:07:10.998610 IP 89.143.223.18 > 212.18.63.73: IP6 2001:15c0:65ff:20b::2 > 2001:15c0:65ff:20b::1: ICMP6, echo request, seq 2978, length 64 23:07:11.998614 IP 89.143.223.18 > 212.18.63.73: IP6 2001:15c0:65ff:20b::2 > 2001:15c0:65ff:20b::1: ICMP6, echo request, seq 2979, length 64 </tcpdump> Thank you in advance.