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

[Mike Hammett via NANOG <nanog () nanog org>]

Is there more desire to be flexible because people are snowflakes and their idea is the only way it should be or real, 
document-able reasons? 




----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest-IX 
http://www.midwest-ix.com 

----- Original Message -----

From: "Tom Beecher" <beecher () beecher cc> 
To: "Mike Hammett" <nanog () ics-il net> 
Cc: "NANOG" <nanog () nanog org>, "Douglas Fischer" <fischerdouglas () gmail com> 
Sent: Tuesday, September 8, 2020 3:02:37 PM 
Subject: Re: BGP Community - AS0 is de-facto "no-export-to" marker - Any ASN reserved to "export-only-to"?' 


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: 

<blockquote>


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 




</blockquote>