On Wed, Dec 3, 2025 at 8:32 PM Frank Habicht via NANOG <[email protected]> wrote: > if you're a customer, using only my PA space, and multihomed: > I'll do BGP with you -- you can be AS64512. > I'll do strict uRPF with a fail-filter allowing all my PA space sourced > by you. > > Is there a problem with that?
Most likely, yes there is. I can drop my announcement without dropping the BGP session. There are lots of reasons to do so. If you're doing strict URPF, you'll start blackholeing packets I send to you on the link based on the routes you're still sending to me, even though they're from the address space you assigned to me. URPF will show the return route transiting the other link. It's even more dicey if the multihoming isn't two links with you but rather a link with you and another with someone else. Regards, Bill Herrin -- For hire. https://bill.herrin.us/resume/ _______________________________________________ NANOG mailing list https://lists.nanog.org/archives/list/[email protected]/message/EZCTHWNTZNMRCI7A6A2ET4WS3WA3LVAK/
