2.4.21+ - IPv6 over IPv4 tunneling b0rked

[CaT <cat@zip.com.au>]

With 2.4.21-pre2 I can get a nice tunnel going over my ppp connection
and as such get ipv6 connectivity. I think went to 2.4.21 and then to
2.4.22-pre4 and bringing up the tunnel fails as follows:

[01:37:04] root@nessie:/usr/src/linux>> ifup --verbose sit1
Configuring interface sit1=sit1 (inet6)
run-parts /etc/network/if-pre-up.d
ip tunnel add sit1 mode sit remote 138.25.6.14
ip link set sit1 up
ip addr add 3ffe:8001:000c:ffff::37/127 dev sit1
 ip route add ::/0 via 3ffe:8001:000c:ffff::36 
RTNETLINK answers: Invalid argument

Basically nothing gets through. Any attempts to ping/connect past my
gw fail and pinging the external gw results in packets coming back from
my gw (though with the eth0 IP addy) as if I were pinging it instead.

ie:

15 [01:41:34] hogarth@theirongiant:/home/hogarth>> ping6 3ffe:8001:000c:ffff::36PING 3ffe:8001:000c:ffff::36(3ffe:8001:c:ffff::36) from 3ffe:8002:1005::2 : 56 data bytes
64 bytes from 3ffe:8002:1005::1: icmp_seq=1 ttl=64 time=0.159 ms
64 bytes from 3ffe:8002:1005::1: icmp_seq=2 ttl=64 time=0.118 ms
64 bytes from 3ffe:8002:1005::1: icmp_seq=3 ttl=64 time=0.109 ms
64 bytes from 3ffe:8002:1005::1: icmp_seq=4 ttl=64 time=0.116 ms
64 bytes from 3ffe:8002:1005::1: icmp_seq=5 ttl=64 time=0.114 ms

--- 3ffe:8001:000c:ffff::36 ping statistics ---
5 packets transmitted, 5 received, 0% loss, time 3999ms
rtt min/avg/max/mdev = 0.109/0.123/0.159/0.019 ms

Mind you, the same exact config works beautifully under 2.4.21-pre2.

If there are any patches you want me to try or help in any other way
(as far as debugging goes anyways :) then holler. :)

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