IPv6 tunnel suddenly stops working. AICCU tunnel is up and running. However I cant receive any IPv6 packets. IPv4 encapsulated packets leave the system, but no replies from dedus01... Heartbeat is sent every minute, but no reply from 91.184.37.9 ifconfig aiccu aiccu Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet6 addr: 2a01:198:200:5e7::2/64 Scope:Global inet6 addr: fe80::98:200:5e7:2/64 Scope:Link UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1420 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:2187 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:0 (0.0 b) TX bytes:442187 (431.8 Kb) tcpdump -n -i ppp0 udp and host 91.184.37.98 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 224 bytes 15:04:45.961854 IP 95.115.72.90.25282 > 91.184.37.98.5072: UDP, length 44 15:05:45.962094 IP 95.115.72.90.25282 > 91.184.37.98.5072: UDP, length 44 15:06:45.962373 IP 95.115.72.90.25282 > 91.184.37.98.5072: UDP, length 44 From another IPv6 enabled network which is working: merlin@babylon:~$ ping6 2a01:198:200:5e7::1 PING 2a01:198:200:5e7::1(2a01:198:200:5e7::1) 56 data bytes From 2a01:198:200:680::1 icmp_seq=1 Destination unreachable: No route From 2a01:198:200:680::1 icmp_seq=2 Destination unreachable: No route From 2a01:198:200:680::1 icmp_seq=3 Destination unreachable: No route ^C --- 2a01:198:200:5e7::1 ping statistics --- 3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2002ms merlin@babylon:~$ ping6 2a01:198:200:5e7::2 PING 2a01:198:200:5e7::2(2a01:198:200:5e7::2) 56 data bytes From 2a01:198:200:680::1 icmp_seq=1 Destination unreachable: No route From 2a01:198:200:680::1 icmp_seq=2 Destination unreachable: No route ^C --- 2a01:198:200:5e7::2 ping statistics --- 2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 1001ms merlin@babylon:~$ ping6 2a01:198:485::1 PING 2a01:198:485::1(2a01:198:485::1) 56 data bytes From 2a01:198:200:680::1 icmp_seq=1 Destination unreachable: No route From 2a01:198:200:680::1 icmp_seq=2 Destination unreachable: No route ^C --- 2a01:198:485::1 ping statistics --- 2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 1001ms