Relaxed handling of OTC attribute

[Maria Matejka]

Hello André,

(with my BIRD Team hat on)

On Thu, Jun 26, 2025 at 12:27:04PM +0200, André Grüneberg wrote:

> We have now (silently) implemented OTC handling in our route servers
> without setting the role in the protocol.

Oh nice!

> For the reference, we extended the ingress filter with:
> 
>   define IXP_LC_FILTERED_ROUTE_LEAK_DETECTED      = ( routeserverasn, 1101,
> 50 );
>     if defined( bgp_otc ) then {
>         bgp_large_community.add( IXP_LC_FILTERED_ROUTE_LEAK_DETECTED );
>     }
> 
> The egress filter (which already implicitly rejects routes with the
> community above) was enhanced with:
>     if ! defined( bgp_otc ) then {
>         bgp_otc = routeserverasn;
>     }

Looks feasible and correct on first sight.

> I'd really love to also announce the roles capability, but we'd need some
> way in Bird to say "do not treat-as-withdraw". Is there any chance we can
> get this functionality?

We are expecting to implement this. Considering current short-term
planning, it may come back to our table in the late autumn.
(This is not a deadline promise.) We could obviously implement this
as a non-systematic hack like tomorrow or so, but that would make
our code much less maintainable.

Thank you for the feature request, have a nice summer!  
Maria

-- 
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.
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