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

Owen DeLong owen at delong.com
Sun Oct 4 02:21:22 UTC 2020


Yes, but with large communities, that’s called RFC-8092 and in general, RFC-8642 has some good data.

There’s also BGP extended communities (RFC-7153 and the IANA registry it creates).

Creating an ad hoc BCP vs. using the existing RFC process seems ill-advised.

Owen

> On Sep 8, 2020, at 11:35 AM, Mike Hammett via NANOG <nanog at nanog.org> wrote:
> 
> How I see the OP's intent is to create a BCP of what defined communities have what effect instead of everyone just making up whatever they draw out of a hat, simplifying this process for everyone.
> 
> 
> 
> -----
> Mike Hammett
> Intelligent Computing Solutions
> http://www.ics-il.com
> 
> Midwest-IX
> http://www.midwest-ix.com
> 
> From: "Tom Beecher via NANOG" <nanog at nanog.org>
> To: "Douglas Fischer" <fischerdouglas at gmail.com>
> Cc: "NANOG" <nanog at nanog.org>
> Sent: Tuesday, September 8, 2020 1:30:19 PM
> Subject: Re: BGP Community - AS0 is de-facto "no-export-to" marker - Any ASN reserved to "export-only-to"?'
> 
> BGP Large Communities ( https://tools.ietf.org/html/rfc8195 <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 at nanog.org <mailto: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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