| 1) Provider X can announce the aggregate outside of the area & thus | give free transit to the whole area; or | | 2) Provider X can announce just provider X's customers outside of the | area, thus defeating the gain from aggregation; or | | 3) Provider X can be paid by everyone else in the area to provide | transit to the entire area to where ever else Provider X connects to. Just to be vicious, I think I should mention option #4: Provider X can announce the aggregate outside of the area and drop packets bound for people in the area who do not pay Provider X for transiting packets to them. I think you will find that if a system were set up such that there were many touchdowns of this nature (announcing a single prefix), people would be screaming that they were at the mercies of the decisions about to whom in each local aggregate each long-distance carrier would be willing to deliver traffic. One could also view this as a way to push the problems of CIDRization out to the edges -- it would then be the end sites which would have to learn and be able to route towards the exceptions in the local aggregates, rather than the long-haul carriers. Sean.