On Mon, Apr 6, 2026 at 11:32 AM William Herrin <bill@herrin.us> wrote:

My ISP is your customer and you appear to be incorrectly applying strict reverse path filtering on their BGP managed link. If that's accurate, congratulations: you broke the Internet. Or at least the part of it encompassing 199.33.224.0/23. Please contact me so we can figure this out.

The RPF filter was removed and all is working as it should be. My thanks to everyone involved. For the list: let this be your annual reminder that BGP and strict RPF are incompatible with each other. Strict RPF just doesn't handle asymmetric routing. If you try it, you'll inevitably create some black holes. And you won't find them. Your customer will. When you have a multihomed downstream customer, use static lists or an API to build your BCP 38 filter instead. And kudos to both Free Range and Edgoo for caring about BCP 38. Even if it did cause me a little inconvenience. Regards, Bill Herrin -- For hire. https://bill.herrin.us/resume/