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>]

I also get that intent from the OP. However I disagree that there should be
a 'de facto' standard created for such things. All flavors of BGP community
specifications are designed to be flexible so that different networks can
design a system that is tailored to their needs.

Having 'de facto' standards does not simplify in my opinion. I believe it
just creates more work for operators trying to navigate around different
opinions of what 'de facto' means.




On Tue, Sep 8, 2020 at 2:35 PM Mike Hammett <nanog () ics-il net> 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 () nanog org>
> *To: *"Douglas Fischer" <fischerdouglas () gmail com>
> *Cc: *"NANOG" <nanog () 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 ) 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