Thus spake "Keith Moore" <moore(_at_)cs(_dot_)utk(_dot_)edu>
What's the problem with locally significant addresses? Having
thousands of
10 networks will never present a problem unless those networks at
some point
would like to talk to each other.
right. if net 10 networks stay completely isolated from one another,
then there's no problem. the problem only exists when people want to
tie those networks together. but it's inevitable that the vast
majority
of private networks *will* want to communicate with the public
Internet
in ways that NAT does not facilitate.
In my experience, the addressing problem hasn't even been with people
trying to communicate across the Internet... It's private corporate
connections.
Imagine there are n companies using 10/8. Now, each of these n
companies wants to talk (privately) with the other n-1 companies. Since
each company uses the same addresses, they must put a pair of NAT
devices facing each other at each boundary, resulting in 2n(n-1) NATs
(more for redundancy). Also, since each company must see non-10/8
addresses for each of its n-1 peers, you will need locally-unique blocks
of address space for each NAT-NAT link.
Now, this address space can be private, requiring extensive coordination
between all n companies on who can use what where, or it can be public,
requiring n(n-1) blocks of space from ARIN/RIPE/APNIC.
When n was small, NAT was feasible. At today's value for n, it is
conceivable that we may consume fewer address blocks without NAT.
Keith
S
| | Stephen Sprunk, K5SSS, CCIE #3723
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