How can I set krt_realm in the kernel protocol by gw (nexthop) value?

[Alexander Zubkov]

You have to update krt_realm attribute in your filter, like that:

function gw_realms() {
        if gw = 1.1.1.1 then return 1;
        if gw = 2.2.2.2 then return 2;
        if gw = 3.3.3.3 then return 3;
        return 0;
}

filter peer_realms {
        krt_realm = gw_realms();
        accept;
}

protocol kernel kernel_ipv4 {
    ipv4 {
        export filter peer_realms;
    };
}

On Fri, Jul 30, 2021 at 6:05 AM Eric Wheeler <bird at lists.ewheeler.net> wrote:
>
> Hello all,
>
> I would like to put routes in realms for traffic accounting based on the
> peer IP provided by a BGP route server on an exchange.  I was thinking I
> could do something like this, but bird gives errors like "syntax error,
> unexpected KRT_REALM":
>
>         filter gw_realms {
>                 if gw = 1.1.1.1 then return 1;
>                 if gw = 2.2.2.2 then return 2;
>                 if gw = 3.3.3.3 then return 3;
>                 return 0;
>         }
>
>         protocol kernel kernel_ipv4 {
>             ipv4 {
>                 krt_realm filter peer_realms;
>             };
>         }
>
>
> What is a proper way to dynamically set the krt_realm attribute per gw?
>
> Thank you for your help!
>
> --
> Eric Wheeler