Again: A STM-1 between Frankfurt and London will be typically less expensive than between Frankfurt and Wiesbaden.
This is not about cost. Does an STM-1 between Wiesbaden and London cost less than one between Wiesbaden and Frankfurt? Or does it pass through Frankfurt because it is a neighbouring city? If we did use a geotopological allocation scheme for another 1/8th of the IPv6 address space, this is an example of an area where there is a logical clustering of cities into a larger geographical aggregate. Wiesbaden, Mainz, Darmstadt and Frankfurt are all over 100,000 population. It is logical to reserve a single aggregate for them that covers all 4 city aggregates. That way, providers can choose to accept all city-level aggregate routes or to only see the single regional aggregate. Chances are that North American providers will only use the one regional aggregate while man Europeans will distinguish all 4 cities.
And then every ISP puts in a prefix for his part of the geopolitical address range of every city in which it shows presence, thus giving us an enormous growth in the number of routing table prefixes.
That's not how IP routing works. Anyone can announce any route that they want, but network providers filter incoming route announcements based on some sort of logical view of the network topology. In other words, they refuse to see details that they believe are unimportant to them. Geotopological addressing provides a nice framework for ISP filtering because they can ignore longer prefixes within a city aggregate if it makes sense for them to treat the entire city as a single destination. Geotop addressing doesn't mandate how filtering is done, it is just an enabler. --Michael Dillon