I believe that Jason is asking about an ISP BGP community to prepend their AS when the BGP routes are received from the customer (not when advertising to a peer). I don't see a functional difference between the two and I suspect that ISPs added support for convenience. If you already send BGP communities to your ISP for other BGP route manipulation, you can add another community for ISP AS prepending rather than modifying your local policies to add AS prepending. You are 1. ISP is 2. 1 1 2 - You prepend 1 2 2 - ISP prepends -- Clinton Work Airdrie, AB On Thu, Oct 26, 2017, at 01:19 PM, Leo Bicknell wrote:
In a message written on Thu, Oct 26, 2017 at 02:47:44PM -0400, Jason Lixfeld wrote:
I understand how prepends fit in the context of best path selection, but my question was more the difference between a customer signalling the ISP to prepend their AS using a BGP community stamped to a prefix vs. the customer prepending their own AS instead.