North American Network Operators Group

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Re: IPv6 news

  • From: Michael.Dillon
  • Date: Mon Oct 17 09:57:09 2005

> > 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