docs/docs/home-network/radv.md

# Radv

This document is for setting up radv on Bird 2.0.

## General syntax

You will want to add one of these to one of your Bird configuration files:

```
protocol radv
{
    # Stuff goes here
}
```

## Advertising your prefix

If you would like to advertise your prefix to hosts on your LAN that have set their address acquisition for IPv6 to _'Automatic'_ such that they will assign themselves an address within that prefix then you will want to add a `prefix` block as so:

```
protocol radv
{
    # Advertise your prefix
    prefix fd40:ec65:5b4c::/64 {
        # TODO: Add anything that needs to be in here
    };

    # Interfaces to run radv on
    interface "eth0";

}
```

In the above example I am advertising a `/64` within my `/48`/ULA (`fd40:ec65:5b4c::/48`), `fd40:ec65:5b4c::/64`, and only on interface `eth0` will radv run.

## Advertising route(s)

You can advertise a default route, to `fd00::/8` or simply all routes in your router's routing table, to your hosts using the following.
The advantage of announcing only a single `fd00::/8` is that this needs less advertisement updates and thus consumes less traffic. Furthermore, the end devices do not have to maintain such large routing tables.

### Advertising a single `fd00::/8`

In order not to have the default route in our normal routing table, it is recommended to make an extra routing table for the radv routes. There we define the default route.

```
ipv6 table radv_routes;

protocol static {
        ipv6 {
            table radv_routes;
            export all;
        };

        route fd00::/8 unreachable;
}

protocol radv
{
    # Enable propagating of routes exported to us via radv to hosts
    propagate routes yes;

    ipv6 {
        # Export ula default routes into the radv advertisement
        export all;
        table radv_routes;
    };

    # Interface to run radv on - only eth0 (change to what you want)
    interface "eth0" {
        # Advertise your prefix
        prefix fd40:ec65:5b4c::/64 {
            # Defaults are fine
        };

        # Prevent advertising of default route
        default lifetime 0;
    };
}
```

### Advertising all known routes

This will advertise all the routes your Bird router knows (those in the `crxn` table) such that your, laptop for example, will add all of them to its routing table.

```
protocol radv
{
    # Enable propagating of routes exported to us via radv to hosts
    propagate routes yes;

    ipv6 {
        # Export all your routes into the radv advertisement
        export filter crxn6;
        table crxn;
    };

    # Interface to run radv on - only eth0 (change to what you want)
    interface "eth0" {
        # Advertise your prefix
        prefix fd40:ec65:5b4c::/64 {
            # Defaults are fine
        };

        # Prevent advertising of default route
        default lifetime 0;
    };
}
```