Changes
Added notes on IPv6 autoconfiguration problems when CT0 is a router.
==Additional VEs==
12. For each additional VE, start at step #5.
==Notes on IPv6 autoconfiguration==
If your CT0 is also performing routing duties, you might chance upon the problem that IPv6 stateless autoconfiguration using radvd is not working for the CT's. The description below is specific for a Debian (Lenny) CT0 and Debian (Squeeze) CT.
First check if your CT is actually receiving any router advertisements (RA's). This can be done by installing radvd (apt-get install radvd) and running radvdump. Simply wait for the next round of RA's from radvd, or trigger it (by restarting radvd on CT0, for example). If you do not receive any RA's there is a more fundamental problem. The following only concerns the scenario where the CT receives RA's but does not configure the network interfaces accordingly. Do not forget to remove the radvd package after checking.
Because CT0 is performing routing services, all or some values under /proc/sys/net/ipv6/conf/*/forwarding and under /proc/sys/net/ipv6/conf/*/mc_forwarding are set to 1. This appears to override the defaults for these values in the /proc filesystems for the CT's. Unless you explicitly disable forwarding in /etc/sysctl.conf, your CT will also use these values. This means that, to the IPv6 Neighbour Discovery Protocol (NDP) responsible for router advertisements and autoconfiguration, your CT is a router and therefore not allowed to use the RA's to configure the interfaces. To fix this, add or change the following lines to /etc/sysctl.conf '''''on the CT, not on CT0''''':
<pre>
net.ipv6.conf.all.forwarding=0
net.ipv6.conf.all.mc_forwarding=0
</pre>
You may also want to explicitly disable IPv4 forwarding since the CT is not a router. To do this, also change the line:
<pre>
net.ipv4.ip_forward=0
</pre>
Now reload sysctl on the CT by executing
<pre>
sysctl -p
</pre>
and you will be good to go. The CT will now autoconfigure the network interfaces the next time it sees an RA.
==See also==
