On Wed, 18 Aug 2021 11:33:09 +0200 Lars Prehn <lprehn@mpi-inf.mpg.de> wrote:
As I understand by now, it is highly recommended to set a max-prefix limit for peering sessions. Yet, I can hardly find any recommendations on how to arrive at a sensible limit.
Maybe because there isn't a simple, universal approach to setting it. Probably like a lot of people, historically I'd set it to some % over the current stable count and then manually adjust when the limits were about to be breached, or often was the case when they were and I wasn't ready for it. Not ideal. I've never felt the automation of this setting however was worth the effort. Of course I am not usually responsible for hundreds of routers and thousands of peering sessions. At the risk of advocating for more junk in BGP or the RPKI, a max prefix setting might be something that could be set by the announcing peer in a BGP message, or possibly as an RPKI object with an associated ASN. I'll let the masses debate how that would work and all the reasons that isn't ideal, but I'm not sure there is a one-size-fit all solution for this in the near term. John