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.
Option 5: Provider X can announce nothing outside the area, except
to people who are paying X for transit to all X-reachable sites
This would work great if all the backbones touch down in the area.
Customers out in the Rest of the World get transit through their
backbone to all the area sites. Other regional networks or areas
get transit to it via whomever they get global transit from.
It only gets really touchy if few of the backbones touch down
in the area. I think that the intended target area (SF Bay Area)
already has everyone of interest... getting this to work would merely
require getting everyone to play in the party, not having anyone
bring wires to the house. They're already here.