nanog mailing list archives
Re: Best practices for BGP Communities
From: Job Snijders <job () instituut net>
Date: Wed, 6 Mar 2019 10:16:02 +0900
On Wed, Mar 6, 2019 at 8:32 Smith, Courtney <Courtney_Smith () comcast com> wrote:
On 3/5/19, 6:04 PM, "NANOG on behalf of Job Snijders" <nanog-bounces+courtney_smith=comcast.com () nanog org on behalf of job () instituut net> wrote: On Sun, Mar 03, 2019 at 08:42:02PM -0500, Joshua Miller wrote: > A while back I read somewhere that transit providers shouldn't delete > communities unless the communities have a specific impact to their > network, but my google-fu is failing me and I can't find any sources. > > Is this still the case? Does anyone have a source for the practice of > leaving unknown communities alone or deleting them? https://tools.ietf.org/html/rfc7454#section-11 Remember policies between two peers may not be same as customer policies. Example: Customers_of_transit_X >>> Transit X >>> Peer_A >> Customers_of_Peer_A Customers_of_Peer_A may use community A:50 to set local pref to 50 in Peer_A network. But that doesn’t not mean Customers_of_transit_X can send A:50 to set lpref on their routes in Peer_A's network. Peer_A's policy with Transit X likely does not take action on customer communities since they are 'peers' not customers. Transit X can send A:50 to Peer_A but nothing would happen. What's the benefit of Transit X preserving A:50 from its customers if it means nothing in Transit X?
OP didn’t specify what kind of BGP communities they were referring to. In general we can separate communities into two categories: “Informational” and “Action”. You are right that preserving/propagating “action” communities (such as in your example) probably isn’t that interesting. “informational” communities on the other hand can be very valuable. See https://tools.ietf.org/html/rfc8195 for more information on how the two types differ. Kind regards, Job
Current thread:
- Best practices for BGP Communities Joshua Miller (Mar 04)
- Re: Best practices for BGP Communities Job Snijders (Mar 05)
- Re: Best practices for BGP Communities Smith, Courtney (Mar 05)
- Re: Best practices for BGP Communities Job Snijders (Mar 05)
- Re: Best practices for BGP Communities Joshua Miller (Mar 06)
- Re: Best practices for BGP Communities Randy Bush (Mar 06)
- Re: Best practices for BGP Communities Christopher Morrow (Mar 06)
- Re: Best practices for BGP Communities Smith, Courtney (Mar 05)
- Re: Best practices for BGP Communities Job Snijders (Mar 05)
- <Possible follow-ups>
- Re: Best practices for BGP Communities John Kristoff (Mar 04)
- Re: Best practices for BGP Communities Arnold Nipper (Mar 06)
- RE: Best practices for BGP Communities adamv0025 (Mar 07)
- Re: Best practices for BGP Communities Arnold Nipper (Mar 06)