Alan Hannan said:
Physical topology is likely to map to geographic topology.
Circuits certainly do take odd L1 paths to connect L1 endpoints,
but these are exceptions, not he rule.Accordingly, not allocating in a geographic fashion lends to
deaggregation, which is bad.A good sentiment, but not neccessarily practical. The one constant we
can count on is that things change.
So, if I look at my crystal ball, and predict that I will need n
addresses in a particular physical location, using your planning
exemplar I will allocate n addresses in an aggregate. The fact that I
only need 1/2 n now means that I will temporarily waste 1/2 n. But what
happens when I need n + 1 addresses in that city? Which is the lesser of
two evils?
So there is also a good argument to *not* rely on a congruence
of physical and geographic topology.
Some form of NAT still appears preferable.
Rodney Joffe
Chief Technology Officer
Genuity Inc., a Bechtel company
http://www.genuity.net