This is a big reason why providers don't implement BCP38. A customer has one block of addresses from provider A and another from provider B. In general each provider only knows about its own address block, but the traffic comes from both blocks, and the customers get rather annoyed if a provider doesn't accept their traffic. ("If you don't want our $20K/month, we're sure we can find someone else who does.") Trying to keep track of what customer has what block of someone else's address space is hopeless, so they just turn off the filters for the multihomed customers.BCP38 should be automatable at the edge even with multihoming. We do have the technology to provide each customer with a CERT that says they have been assigned this block of addresses.
We do? References, please, preferablyt with the commands I type into my router to automatically import and handle the certs.
R's, John