NSPs filter?

Stephen Stuart wrote:
> Let's say the customer operates some big enterprise network, runs
> their infrastructure in RFC1918 space ("for security," hah)

Like Abovenet's OOB right?

I made what I consider to be non-trivial progress toward stamping that
out before my time at the helm of 6461 ended. I happen to know that
the people still there are trying to continue making progress on that
front, what is going on around them.

Would you care to take a shot at answering my question, or is
contributing productively too much to ask?