On Wed, 12 Oct 2022, Andrey Kostin wrote:
Matthew Petach писал(а) 2022-10-11 20:33:
My point is that it's not a feature of BGP, it's a purely human convention, arrived at through the intersection of pain and laziness. There's nothing inherently "right" or "wrong" about where the line was
drawn, so for networks to decide that /24 is causing too much pain, and moving the line to /23 is no more "right" or "wong" than drawing the line at /24. A network that *counts* on its non-connected sites being reachable because they're over a mythical /24 limit is no more right than a customer upset that their /25 announcements aren't being listened to.
IMO this line wasn't arbitrary, it was (and it still is) a smallest possible network size allocated by RIRs. So it's just a common sense to receive everything down to /24 to have the complete data about all Internet participants.
Nope. I first did some work on this topic in early 2008 and remembered writing a blog entry about it. https://web.archive.org/web/20060926140659/https://www.ripe.net/ripe/docs/ri... RIPE, at least back in 2008, would allocate as long as /29 from several /8s. I have no idea how many sub-/24 allocations they did or what the recipients tried doing with the space. Even then, despite RIPE saying "we'll allocate as long as /29", I set the filter cut-off [arbitrarily] at /24 and made sure we had defaults pointing at ISPs that had "fuller" tables. And just for the record, despite having been bitten by it more than once, I'm very much in the camp of "if you advertise a covering aggregate, you're offering to get packets there, regardless of whether or not more specifics exist." You have no business demanding what routes someone else's network receives/accepts. All you can reasonably control is what you advertise and what you accept. ---------------------------------------------------------------------- Jon Lewis, MCP :) | I route StackPath, Sr. Neteng | therefore you are _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________