There are 437 cities of 1 million or more population. There are roughly 5,000 cities of over 100,000 population. And there are 3,047,000 named communities in the world.
Seems to me that the number of routes in the global routing table should logically be closer to 5,000 than to 3,000,000.
If there is an exchange point per city over 100,000 (the route goes to the IXP and then to the actual provider)... Otherwise, there is a flaw in your calculation.
I didn't calculate those numbers. They come from various demographic sources. And I would expect that many of these cities will have more than one exchange point. In fact, one could argue that a city should have no less than 3 central switching points for resiliency, and that major intercity providers should have no less than three paths into each city. However, if the addresses for everything in the city come from a single netblock, then sites in a neighboring city will only need one aggregate route route in the majority of cases. Even if there are enough special cases for an average of 5 routes per city, you still have only 25,000 global routes. It is still far from the projection of one million routes that some people have made and it is still less than today's routing table size. --Michael Dillon