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 Kind regards, Job 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?