We will be setting up the machine that runs bird as a router so therefore we need to make your Linux kernel's network stack not drop IPv6 packets that it receives (addressed to it via Ethernet) but are not addressed to it via IPv6 address - in other words it must try do something with these packets, namely attempt to forward them one hop closer to their initial destination.
However, after reboot it won't be saved and will go back to its defaults. Therefore what you need to do is to enable forwarding on boot-up, this can be done by adding an additional line to your `/etc/sysctl.conf` (which holds a bunch of these statements), it should look like this:
