(usagi-users 00319) linux as gateway router (6to4 in particular)

[Roger Venning <r.venning@xxxxxxxxxxx>]

Greetings all,

I've been playing with my the linux 6to4 capability, trying to use a linux
box as a six to four gateway for a ipv6 network behind it. However, although
the gateway has access to both the 6bone & the six to four world, if I 
try to
get it to act as gateway, weird stuff happens.

To be specific, the clients cannot access hosts on the 6bone _UNTIL_ 
something
special happens while the gateway does a tracepath. For instance, while

ping6 -n www.kame.net from a client, a bunch of Destination unreachables are
received, but then while the gateway did a tracepath, at about hop 3, 
the icmp started
getting through...
...
From 2002:8b86:5733:1:240:5ff:fe33:2d25: Destination unreachable: 
Address unreachable
...
64 bytes from 3ffe:501:4819:2000:5054:ff:fedc:50d2: icmp_seq=36 hops=53 
time=710.707 msec

[root@zooropa sit0]# tracepath6 www.kame.net
1?: [LOCALHOST]                      pmtu 1480
1:  2002:836b:4179::836b:4179                629.524ms
2:  2002:836b:4179::836b:4179                asymm  1 709.959ms pmtu 1280
2:  6bone.merit.edu                          689.978ms
3:  3ffe:401:0:1::16:2                       779.897ms
4:  pc1.losangeles.wide.ad.jp                asymm  8 1040.156ms
5:  pc7.otemachi.wide.ad.jp                  asymm  7 1079.884ms
5:  pc7.otemachi.wide.ad.jp                  asymm  7 1050.150ms
6:  pc2.fujisawa.wide.ad.jp                  asymm  8 1069.909ms
6:  pc2.fujisawa.wide.ad.jp                  asymm  8 1010.157ms
7:  paradise.v6.kame.net                     asymm  9 1019.915ms
7:  paradise.v6.kame.net                     asymm  9 1029.917ms
8:  pine.v6.kame.net                         asymm 10 1029.922ms reached
   Resume: pmtu 1280 hops 8 back 10


Do people have any ideas about this? The routing tables etc.
are as below.

On the gateway:
-----------------
[root@zooropa sit0]# ip -6 route show
::/96 via :: dev sit0  metric 256  mtu 1480
2002:8b86:5733:1::/64 dev eth0  metric 1024  mtu 1500
2002::/16 dev sit0  metric 1024  mtu 1480
fe80::/10 dev eth0  proto kernel  metric 256  mtu 1500
fe80::/10 dev sit0  proto kernel  metric 256  mtu 1480
fec0:0:0:1::/64 dev eth0  metric 1024  mtu 1500
ff00::/8 dev eth0  proto kernel  metric 256  mtu 1500
ff00::/8 dev sit0  proto kernel  metric 256  mtu 1480
default via ::131.107.65.121 dev sit0  metric 1024  expires 428sec mtu 1480
unreachable default dev lo  metric -1  error -101
[root@zooropa sit0]# ip -6 addr show
1: lo: <LOOPBACK,UP> mtu 3856 qdisc noqueue
  inet6 ::1/128 scope host
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
  inet6 fec0:0:0:1::1/128 scope site
  inet6 fe80::240:5ff:fe33:2d25/10 scope link
  inet6 2002:8b86:5733:1:240:5ff:fe33:2d25/128 scope global
3: sit0@NONE: <NOARP,UP> mtu 1480 qdisc noqueue
  inet6 2002:8b86:5733::1/128 scope global
  inet6 ::127.0.0.1/96 scope host
  inet6 ::10.0.0.1/96 scope global
  inet6 ::139.134.87.51/96 scope global

On the client:
----------------
[root@fartlek /root]# ip -6 route show
2002:8b86:5733:1::/64 dev eth0  metric 1024  mtu 1500 advmss 1440
fe80::/10 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
fec0:0:0:1::/64 dev eth0  metric 1  mtu 1500 advmss 1440
ff00::/8 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
default via 2002:8b86:5733:1:240:5ff:fe33:2d25 dev eth0  metric 1024  
mtu 1500 advmss 1440
unreachable default dev lo  metric -1  error -101
[root@fartlek /root]# ip -6 addr show 
1: lo: <LOOPBACK,UP> mtu 3856 qdisc noqueue
  inet6 ::1/128 scope host
2: eth0: <BROADCAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
  inet6 2002:8b86:5733:1:200:e8ff:fee2:2b24/128 scope global
  inet6 fec0:0:0:1::2/0 scope site
  inet6 fe80::200:e8ff:fee2:2b24/10 scope link


Thanks,

Roger.

--
-------------------------------------------------------------
Roger Venning	\ Do not go gentle into that good night
Melbourne        \ Rage, rage against the dying of the light.
Australia <r.venning@xxxxxxxxxx>                 Dylan Thomas