we have set up a small IPv6 Testing network. The setup looks like this:

    ::/0
+----------+
| Firewall | Router to the public net
+----------+
     |           2001:...::/106
     |       +----------+
     +-------|  SIT GW  | sit Tunnel gatway to the some test users
     |       +----------+
     |
+----------+
| Test Sys |  Testsystem
+----------+

The idea is to advertise the default route from the firewall and the route for the SIT subnets from the sit gateway. The configurations for radvd are:

# Firewall
interface eth0
{
   AdvSendAdvert on;
   route ::/0 
   {
   };
};


# SIT Gatway
interface eth0
{
   AdvSendAdvert on;
   route 2001:...::/106
   {
   };
};

We have captured the adv. packages with tcpdump and the packages looks good. We see a default route from the fw, and the subnet route from the SIT gatway.

But if we look on the testsystem there are two default routes over both gateways. There is no subnet route. The routing does not work of course. Here the routes we get:

2001:.....::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
default via fe80::baac:6fff:fe8e:XXXX dev eth0  proto kernel  metric 1024  expires 0sec mtu 1500 advmss 1440 hoplimit 64
default via fe80::e415:aeff:fe12:XXXX dev eth0  proto kernel  metric 1024  expires 0sec mtu 1500 advmss 1440 hoplimit 64

Any Idea?