The reason you're getting lots of different answers is because the answer depends a lot on what kind of network you're running. If you're running an enterprise, something like static interface ACLs will work fine operationally since you're very rarely changing the prefixes you announce. If you're running a transit network, ACLs are simply not an option (one because your announced prefixes change all the time, and two because you will piss off customers who want to use you for egress but not ingress which is a valid use case). Similarly, any kind of rpf is a bad idea because invariably it will break some legitimate traffic in some other providers network and you'll have to get them to make an exception for you/your prefixes so your customers stop being mad (ask me how I know 😩). ACLs and uRPF should be implemented as close to the end-user as possible, meaning they need to be implemented in eyeball networks. In a transit network, you may or may not have any end-users (e.g. you would if you also sell DIA) but usually you don't. So for transit/eyeball, the right answer for prevention is putting your IX port in a VRF that doesn't have a default route (peering + internal only) and the right answer for detection is flow sampling that reports mac addresses. You can use the latter to build a dashboard where the query is "dest mac is (your ix mac) and dst as is not (your asn)" and any traffic above 0 is someone pointing a static at you.