[ipv6-wg] Re: [address-policy-wg] Re: 200 customer requirements for IPv6

> 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