Re: BGP Community - AS0 is de-facto "no-export-to" marker - Any ASN reserved to "export-only-to"?'

[Tom Beecher via NANOG <nanog () nanog org>]

BGP Large Communities ( https://tools.ietf.org/html/rfc8195 ) already
provides for anyone to define the exact handling you wish.



On Tue, Sep 8, 2020 at 11:57 AM Douglas Fischer via NANOG <nanog () nanog org>
wrote:

> Most of us have already used some BGP community policy to no-export some
> routes to some where.
>
> On the majority of IXPs, and most of the Transit Providers, the very
> common community tell to route-servers and routers "Please do no-export
> these routes to that ASN" is:
>
>  -> 0:<TargetASN>
>
> So we could say that this is a de-facto standard.
>
>
> But the Policy equivalent to "Please, export these routes only to that
> ASN" is very varied on all the IXPs or Transit Providers.
>
>
> With that said, now comes some questions:
>
> 1 - Beyond being a de-facto standard, there is any RFC, Public Policy, or
> something like that, that would define 0:<TargetASN> as "no-export-to"
> standard?
>
> 2 - What about reserving some 16-bits ASN to use <ExpOnlyTo>:<TargetASN>
> as "export-only-to" standard?
> 2.1 - Is important to be 16 bits, because with (RT) extended communities,
> any ASN on the planet could be the target of that policy.
> 2.2 - Would be interesting some mnemonic number like 1000 / 10000 or so.
>
> --
> Douglas Fernando Fischer
> Engº de Controle e Automação