I worked at EISA, when they had just received their ATM backbone link.
Problem with an ISP, when you start thrashing/testing their bandwidth from a local machine at the ISP, your thrashing affects all their clients and triggers alarms to all the admins - they go off at you for hammering the link.
This happened at EISA, thankfully not to me... but I heard the head dude go off at the leech.