IPv6: Local LAN configuration

Putting the router on the LAN

The first thing that needed to be done was to put the router on the network that was going to used for the internal LAN. It looks like there is meant to be some automatic way of doing this but whatever it is is either broken or impossible to figure out, hence the manual method.

In this case all subnets were made /64 (the minimum), the subnet number used is 1 and the IP address used is 1 on that subnet for the router. This makes the routers IP address:

• 2002:cbd9:1d86:1::1/64

where

• 2002:cbd9:1d86 is the 6to4 prefix 1 is the subnet 1 is the IP address on the subnet.

The internal LAN interface eth0 was manually configured with this IP address and subnet by adding:

    IPV6INIT=yes
    IPV6ADDR="2002:cbd9:1d86:1::1/64"

to /etc/sysconfig/network-scripts/ifcfg-eth0

Running radvd

The Routing Advertisment Daemon (radvd) is used to advertise the subnet prefix to the rest of the LAN. This is configured via the /etc/radvd.conf file. The documentation is not 100% clear in a few places so it stick with it if it first doesn't work ;)

A basic configuration is:

    interface eth0
    {
        AdvSendAdvert on;
        MinRtrAdvInterval 3;
        MaxRtrAdvInterval 10;
        prefix 0:0:0:1::/64
        {
            Base6to4Interface eth1;
            AdvPreferredLifetime 120;
            AdvValidLifetime 300;
            AdvRouterAddr on;
        };
    };

Where eth0 is the internal lan and eth1 is the 6to4 interface (could also be ppp5 for a ppp connection for example).

Note the prefix value:

• 0:0:0:1::/64

in which:

• 0:0:0 will be automatically replaced with the 6to4 address prefix * 1 is the subnet that was selected to use.

The idea of this is that if the 6to4 interface is dynamic, then this will automatically notice when it's IP address changes and advertise that fact to the rest of the LAN. The fact that I hardcoded an address on eth0 in this subnet breaks this assumption though. (And since I don't have a dynamic IP address I've given up trying to resolve this issue for now.)

Other LAN machines:

For each other machine on the LAN all that is required is to enable IPV6 and auto configuration. This was done for eth0 by adding:

    IPV6INIT=yes
    IPV6_AUTOCONF=yes

to /etc/sysconfig/network-scripts/ifcfg-eth0 for example.