Hi,
I'm running FreeBSD 7.0-RELEASE with an IPv6 tunnel through gif(4):
gif0: flags=8151<UP,POINTOPOINT,RUNNING,PROMISC,MULTICAST> metric 0 mtu 1280
tunnel inet 82.70.152.20 --> 77.75.104.126
inet6 fe80::20d:b9ff:fe14:1d18%gif0 prefixlen 64 scopeid 0x6
inet6 2a01:348:6:13a::2 --> 2a01:348:6:13a::1 prefixlen 128
The tunnel works correctly for much of the time. Periodically, however,
it appears to stop routing inbound packets (outbound remains fine) for
hours at a time before beginning to work again with no intervention. I
initially suspected a problem with the tunnel endpoint but I now have a
packet capture providing evidence to the contrary.
For a ping6 to an IP routed through the tunnel these are the packets
passing over the external (IPv4) interface:
17:10:51.640317 IP 82.70.152.20 > 77.75.104.126: IP6 2a01:348:6:13a::2 >
2001:4860:0:1001::68: ICMP6, echo request, seq 0, length 16
17:10:51.691653 IP 77.75.104.126 > 82.70.152.20: IP6
2001:4860:0:1001::68 > 2a01:348:6:13a::2: ICMP6, echo reply, seq 0,
length 16
17:10:52.640631 IP 82.70.152.20 > 77.75.104.126: IP6 2a01:348:6:13a::2 >
2001:4860:0:1001::68: ICMP6, echo request, seq 1, length 16
17:10:52.683821 IP 77.75.104.126 > 82.70.152.20: IP6
2001:4860:0:1001::68 > 2a01:348:6:13a::2: ICMP6, echo reply, seq 1,
length 16
Looks correct. Now the same packet capture on the gif0 interface:
17:10:51.640267 IP6 2a01:348:6:13a::2 > 2001:4860:0:1001::68: ICMP6,
echo request, seq 0, length 16
17:10:52.640587 IP6 2a01:348:6:13a::2 > 2001:4860:0:1001::68: ICMP6,
echo request, seq 1, length 16
It appears, for reasons beyond my understanding, that the tunnel is not
aware of the return packets. No firewall is enabled that could be
filtering the missing packets.
Shortly after the ping6 is sent my endpoint appears to be trying to find
the remote endpoint:
17:10:56.639517 IP6 2a01:348:6:13a::2 > 2a01:348:6:13a::1: ICMP6,
neighbor solicitation, who has 2a01:348:6:13a::1, length 24
17:10:57.639513 IP6 2a01:348:6:13a::2 > 2a01:348:6:13a::1: ICMP6,
neighbor solicitation, who has 2a01:348:6:13a::1, length 24
17:10:58.639499 IP6 2a01:348:6:13a::2 > 2a01:348:6:13a::1: ICMP6,
neighbor solicitation, who has 2a01:348:6:13a::1, length 24
But I am not sure if this is related as it successfully sends the ping6
outbound regardless. radvd is running on the host if that makes a
difference. To my knowledge its routing table is correct:
default 2a01:348:6:13a::1 UGS gif0
2a01:348:6:13a::1 link#6 UHL gif0
2a01:348:6:13a::2 link#6 UHL lo0
Am I missing something?
--
Jay L. T. Cornwall
http://www.jcornwall.me.uk/
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