Re: [GROW] a quick reminder about large communities and "well known"

[Job Snijders <[e-mail]>]

On Thu, Jul 28, 2022 at 05:59:36PM -0400, Jeffrey Haas wrote:
> [In the context of the anycast community at-mic discussion during IETF-114]
> 
> Grow WG,
> 
> As part of the RFC process for Large BGP Communities, there was strong
> objection to having any large communities set aside for special purposes.  
> 
> As a result of this, there are no designated ASes that are part of the
> rather large deployment of BGP code that understands these communities for
> "magic numbers" that is typical of various implementations for well known
> communities.
> 
> While there has been a few attempts to start discussion about designating
> well known large communities, the above point means there is a fair amount
> of resistance to the idea and inertia to overcome in IDR.
> 
> Extended Communities, if they can hold the data in question, are effectively
> free.  Feel free to grab them at whim!
> 
> -- Jeff (speaking partially as IDR chair and minimally as an IDR historian)

Yes. Especially if the objective is to signal the 'community setting
AS'; extended communities are an appropriate tool as they have
sufficient room for both 16-bit and 32-bit ASNs. Thanks for the
reminder, Jeff! :-)

A question to the working group: is signaling the 'sending ASN' a
critical characteristic of the concept outlined in the anycast-community
draft?

If not, a simple RFC 1997 well-known community is probably more suitable.

Kind regards,

Job