I have read and followed the "Reporting Problems" section on the Contact page and am providing the following details for this report based on the list of items stated there: I am having a problem that occurred earlier and then magically went away and seems similar to problems reported by others in the forum (thread: My tunnel suddenly stopped working). This was working fine for tunnel T14140 for over a year and then, without a reboot, a config change, or a IPv4 change, it stopping working two days ago. The local endpoint is an ARM evaluation board running FreeBSD and connecting to an AT&T DSL line over PPPoE. There are no NATs and no firewalls, and the time on the local endpoint was off by less than 30 seconds (now corrected). I can ping the POP fine over IPv4, but not over IPv6. The SixXS web page indicates that the POP knows the correct IPv4 client address of my router. I have other machines on a static tunnel (T13922) on the same POP, which continues to work without issue, and used that to conduct the following tests: 1. Attempted to ping the working static tunnel endpoint over IPv6 from the broken heartbeat tunnel end. Running tcpdump on the end of the working static tunnel shows that the echo request packets make it to the remote host. The echo replies are somehow lost on the way back. 2. To eliminate a possible firewall change by my ISP (AT&T), I hand-configured a tunnel between my heartbeat endpoint and several other machines on the internet. Bidirectional traffic worked flawlessly over the temporary tunnels. 3. tcpdump -i gif0 on my local endpoint shows no packets ever being received from anywhere, though it does show packets leaving. 4. Trying to do a traceroute to a machine on my tunnel from a remote host returns address unreachable: [nwhitehorn@freefall ~]$ traceroute6 trantor.tachypleus.net traceroute6 to trantor.tachypleus.net (2001:4978:137:1:2e0:81ff:fe62:52b1) from 2001:4f8:fff6::28, 64 hops max, 12 byte packets 1 ipv6gw 0.469 ms 0.363 ms 0.415 ms 2 freebsd.r7.pao1.isc.org 2.025 ms 1.850 ms 1.881 ms 3 gig-2-0-0.r1.pao1.isc.org 2.170 ms 1.713 ms 1.886 ms 4 paix.ipv6.he.net 1.727 ms 1.562 ms 1.882 ms 5 10gigabitethernet4-1.core1.sjc2.he.net 2.611 ms 2.291 ms 2.464 ms 6 10gigabitethernet1-1.core1.chi1.he.net 70.198 ms 59.770 ms 64.523 ms 7 2001:470:0:7f::2 60.238 ms 60.016 ms 60.150 ms 8 unassigned.v6.your.org 89.596 ms 65.249 ms 84.641 ms 9 unassigned.v6.your.org 65.028 ms !A 73.190 ms !A 68.568 ms !A 5. More interestingly, trying to ping or traceroute the remote endpoint of my tunnel from ISC *also* gives address unreachable: [nwhitehorn@freefall ~]$ traceroute6 2001:4978:f:98::1 traceroute6 to 2001:4978:f:98::1 (2001:4978:f:98::1) from 2001:4f8:fff6::28, 64 hops max, 12 byte packets 1 ipv6gw 0.365 ms 0.321 ms 0.265 ms 2 freebsd.r7.pao1.isc.org 2.017 ms 9.019 ms 1.876 ms 3 gig-2-0-0.r1.pao1.isc.org 1.877 ms 1.863 ms 1.725 ms 4 paix.ipv6.he.net 12.990 ms 2.005 ms 1.883 ms 5 10gigabitethernet4-1.core1.sjc2.he.net 2.313 ms 2.441 ms 2.318 ms 6 10gigabitethernet1-1.core1.chi1.he.net 59.806 ms 66.929 ms 60.221 ms 7 2001:470:0:7f::2 60.519 ms 60.065 ms 60.229 ms 8 unassigned.v6.your.org 65.049 ms 64.879 ms 64.770 ms 9 unassigned.v6.your.org 65.080 ms !A 64.749 ms !A 64.759 ms !A The last two, numerically, are: 8 2001:4978:1:400:202:b3ff:feb4:5974 64.908 ms 64.760 ms 64.772 ms 9 2001:4978:1:400:202:b3ff:feb4:5974 65.123 ms !A 65.277 ms !A 65.066 ms !A Alternatively, from my static tunnel machine on POP uschi02: [nwhitehorn@banshee ~]$ traceroute6 -n 2001:4978:f:98::1 traceroute6 to 2001:4978:f:98::1 (2001:4978:f:98::1) from 2001:4978:11f:d600::d610, 64 hops max, 12 byte packets 1 2001:4978:11f:d600::1 0.384 ms 0.259 ms 0.413 ms 2 2001:4978:f:69::1 7.731 ms 7.585 ms 7.738 ms 3 2001:4978:f:69::1 8.535 ms !A 8.218 ms !A 8.526 ms !A Next, my system information, routing tables, and aiccu test output: FreeBSD cepheid.tachypleus.net 7.0-CURRENT FreeBSD 7.0-CURRENT #4: Sat Sep 8 23 :56:34 CDT 2007 root@mail.rh:/usr/obj/arm/usr/home/nathanw/src/sys/LIMULUS arm gif0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1450 tunnel inet 76.204.99.187 --> 216.14.98.22 inet6 fe80::202:6fff:fe45:19c9%gif0 prefixlen 64 scopeid 0x6 inet6 2001:4978:f:98::2 --> 2001:4978:f:98::1 prefixlen 128 Routing tables Internet6: Destination Gateway Flags Netif Expire ::/96 ::1 UGRS lo0 => default 2001:4978:f:98::1 UGS gif0 ::1 ::1 UHL lo0 ::ffff:0.0.0.0/96 ::1 UGRS lo0 2001:4978:f:98::1 link#6 UHL gif0 2001:4978:f:98::2 link#6 UHL lo0 2001:4978:137:1::/64 link#2 UC npe0 2001:4978:137:1::1 00:d0:12:02:76:48 UHL lo0 2001:4978:137:1:2e0:81ff:fe62:52b1 00:e0:81:62:52:b1 UHLW npe0 2001:4978:137:2::/64 link#1 UC ath0 2001:4978:137:2::1 00:02:6f:45:19:c9 UHL lo0 fe80::/10 ::1 UGRS lo0 fe80::%ath0/64 link#1 UC ath0 fe80::202:6fff:fe45:19c9%ath0 00:02:6f:45:19:c9 UHL lo0 fe80::223:12ff:fe1e:cc89%ath0 00:23:12:1e:cc:89 UHLW ath0 fe80::%npe0/64 link#2 UC npe0 fe80::2d0:12ff:fe02:7648%npe0 00:d0:12:02:76:48 UHL lo0 fe80::2e0:81ff:fe62:52b1%npe0 00:e0:81:62:52:b1 UHLW npe0 fe80::%npe1/64 link#3 UC npe1 fe80::2d0:12ff:fe12:7648%npe1 00:d0:12:12:76:48 UHL lo0 fe80::%lo0/64 fe80::1%lo0 U lo0 fe80::1%lo0 link#4 UHL lo0 fe80::%ng0/64 link#5 UC ng0 fe80::202:6fff:fe45:19c9%ng0 link#5 UHL lo0 fe80::%gif0/64 link#6 UC gif0 fe80::202:6fff:fe45:19c9%gif0 link#6 UHL lo0 ff01:1::/32 link#1 UC ath0 ff01:2::/32 link#2 UC npe0 ff01:3::/32 link#3 UC npe1 ff01:4::/32 ::1 UC lo0 ff01:5::/32 link#5 UC ng0 ff01:6::/32 link#6 UC gif0 ff02::/16 ::1 UGRS lo0 ff02::%ath0/32 link#1 UC ath0 ff02::%npe0/32 link#2 UC npe0 ff02::%npe1/32 link#3 UC npe1 ff02::%lo0/32 ::1 UC lo0 ff02::%ng0/32 link#5 UC ng0 ff02::%gif0/32 link#6 UC gif0 route to: 2001:4860:0:2001::68 destination: :: mask: default gateway: gw-153.chi-02.us.sixxs.net interface: gif0 flags: <UP,GATEWAY,DONE,STATIC> recvpipe sendpipe ssthresh rtt,msec rttvar hopcount mtu expire 0 0 0 0 0 0 1450 0 cepheid# sixxs-aiccu version AICCU 2007.01.15-console-kame by Jeroen Massa cepheid# sixxs-aiccu test ifconfig: SIOCIFCREATE2: File exists route: writing to routing socket: File exists add net default: gateway 2001:4978:f:98::1: route already in table ####### ####### AICCU Quick Connectivity Test ####### ####### [1/8] Ping the IPv4 Local/Your Outer Endpoint (76.204.99.187) ### This should return so called 'echo replies' ### If it doesn't then check your firewall settings ### Your local endpoint should always be pingable ### It could also indicate problems with your IPv4 stack PING 76.204.99.187 (76.204.99.187): 56 data bytes 64 bytes from 76.204.99.187: icmp_seq=0 ttl=63 time=63.719 ms 64 bytes from 76.204.99.187: icmp_seq=1 ttl=63 time=111.636 ms 64 bytes from 76.204.99.187: icmp_seq=2 ttl=63 time=126.076 ms --- 76.204.99.187 ping statistics --- 3 packets transmitted, 3 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 63.719/100.477/126.076/26.652 ms ###### Did this work? [Y/n] Y ####### [2/8] Ping the IPv4 Remote/PoP Outer Endpoint (216.14.98.22) ### These pings should reach the PoP and come back to you ### In case there are problems along the route between your ### host and the PoP this could not return replies ### Check your firewall settings if problems occur PING 216.14.98.22 (216.14.98.22): 56 data bytes 64 bytes from 216.14.98.22: icmp_seq=0 ttl=58 time=142.170 ms 64 bytes from 216.14.98.22: icmp_seq=1 ttl=58 time=19.314 ms 64 bytes from 216.14.98.22: icmp_seq=2 ttl=58 time=48.149 ms --- 216.14.98.22 ping statistics --- 3 packets transmitted, 3 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 19.314/69.878/142.170/52.456 ms ###### Did this work? [Y/n] Y ####### [3/8] Traceroute to the PoP (216.14.98.22) over IPv4 ### This traceroute should reach the PoP ### In case this traceroute fails then you have no connectivity ### to the PoP and this is most probably the problem traceroute to 216.14.98.22 (216.14.98.22), 64 hops max, 44 byte packets 1 76.204.99.254 (76.204.99.254) 30.691 ms 13.643 ms 33.571 ms 2 dist1-vlan60.mdsnwi.ameritech.net (65.42.115.242) 31.929 ms 32.835 ms 31.635 ms 3 bb2-g1-0.mdsnwi.ameritech.net (65.42.115.100) 33.696 ms 31.795 ms 32.752 ms 4 151.164.94.41 (151.164.94.41) 28.734 ms 31.717 ms 32.676 ms 5 asn4436-nlayer.eqchil.sbcglobal.net (151.164.249.110) 32.636 ms 46.333 ms 44.281 ms 6 as19255.po1-106.ar1.ord1.us.nlayer.net (69.31.111.22) 53.281 ms 46.275 ms 54.185 ms 7 sixxs.cx01.chi.bb.your.org (216.14.98.22) 46.884 ms 71.625 ms 46.761 ms ###### Did this work? [Y/n] Y ###### [4/8] Checking if we can ping IPv6 localhost (::1) ### This confirms if your IPv6 is working ### If ::1 doesn't reply then something is wrong with your IPv6 stack PING6(56=40+8+8 bytes) ::1 --> ::1 16 bytes from ::1: Echo Request 16 bytes from ::1, icmp_seq=0 hlim=64 dst=::1%4 time=3.163 ms 16 bytes from ::1: Echo Request 16 bytes from ::1, icmp_seq=1 hlim=64 dst=::1%4 time=0.866 ms 16 bytes from ::1: Echo Request 16 bytes from ::1, icmp_seq=2 hlim=64 dst=::1%4 time=0.860 ms --- ::1 ping6 statistics --- 3 packets transmitted, 3 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 0.860/1.630/3.163/1.084 ms ###### Did this work? [Y/n] Y ###### [5/8] Ping the IPv6 Local/Your Inner Tunnel Endpoint (2001:4978:f:98::2) ### This confirms that your tunnel is configured ### If it doesn't reply then check your interface and routing tables PING6(56=40+8+8 bytes) 2001:4978:f:98::2 --> 2001:4978:f:98::2 16 bytes from 2001:4978:f:98::2: Echo Request 16 bytes from 2001:4978:f:98::2, icmp_seq=0 hlim=64 dst=2001:4978:f:98::2%6 time=1.712 ms 16 bytes from 2001:4978:f:98::2: Echo Request 16 bytes from 2001:4978:f:98::2, icmp_seq=1 hlim=64 dst=2001:4978:f:98::2%6 time=0.951 ms 16 bytes from 2001:4978:f:98::2: Echo Request 16 bytes from 2001:4978:f:98::2, icmp_seq=2 hlim=64 dst=2001:4978:f:98::2%6 time=0.945 ms --- 2001:4978:f:98::2 ping6 statistics --- 3 packets transmitted, 3 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 0.945/1.203/1.712/0.360 ms ###### Did this work? [Y/n] Y ###### [6/8] Ping the IPv6 Remote/PoP Inner Tunnel Endpoint (2001:4978:f:98::1) ### This confirms the reachability of the other side of the tunnel ### If it doesn't reply then check your interface and routing tables ### Don't forget to check your firewall of course ### If the previous test was succesful then this could be both ### a firewalling and a routing/interface problem PING6(56=40+8+8 bytes) 2001:4978:f:98::2 --> 2001:4978:f:98::1 32 bytes from 2001:4978:137:1:2e0:81ff:fe62:52b1: Neighbor Solicitation --- 2001:4978:f:98::1 ping6 statistics --- 3 packets transmitted, 0 packets received, 100.0% packet loss ###### Did this work? [Y/n] n Please let me know if you need more information or would like me to run more tests. Thanks, -Nathan