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

Wed Sep 9 08:03:26 UTC 2020

De-facto standards are as good as people implementing them, however in order to enforce non ambiguous implementations, it has to be de-jure (e.g. a standard track RFC).
While I’m sympathetic to the idea, I’m quite skeptical about its viability.
A well written BCP would be much more valuable, and perhaps when we get to a critical mass, codification would be a natural process, rather than artificially enforcing people doing stuff they don’t see value (ROI) in, discussion here perfectly reflects the state of art.

Cheers,
Jeff

> On Sep 8, 2020, at 17:57, Douglas Fischer via NANOG <nanog at 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
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