BCP38 is hard, was TWC (AS11351) blocking all NTP?

Wed Feb 5 00:23:01 UTC 2014

On 04/02/14 15:24, John R. Levine wrote:
>> If ISP has customer A with multiple *known* valid networks --doesn't
>> matter if ISP allocated them to customer or not-- and ISP lets them
>> all out, but filters everything else, ISP is still complying with BCP 38.
>
> Of course.  The question is how the ISP knows what the customer's
> address ranges are, without demanding vast amounts of nitpicky manual
> work on both sides.

The same way BGP outbound prefix filters are applied nowadays, would be 
a good start. Some have BGP filtering but don't have ACLs.