We are finally making progress on this. It turns out that one of AT&Ts customers is announcing the 66.205.64.0/24 net block. AT&T is not willing to remove/block the announcement without first talking to their customer that is making the announcement.
It would appear that AT&T did not perform the proper validation of IP space ownership before setting their filters to allow the IP ranges in the announcements. Poor network administration to say the least. When ever we want to announce a new route we have to provide proof that we own the space and are eligible to announce it before the upstream providers will accept what we announce. We encounter this even at the Tier 2 and Tier 3 providers that we have worked with. AT&T being a Tier 1 provider would cause us to expect more.
