quietly....

Owen DeLong owen at delong.com
Tue Feb 1 20:03:38 CST 2011


On Feb 1, 2011, at 3:41 PM, Karl Auer wrote:

> On Tue, 2011-02-01 at 13:38 -0800, Owen DeLong wrote:
>> NAT solves exactly one problem. It provides a way to reduce address
>> consumption to work around a shortage of addresses.
> 
> Devil's advocate hat on: NAT (in its most common form) also permits
> internal addressing to be independent of external addressing.
> 
Which is a bug, not a feature.

> The side effects of that are not necessarily desirable (loss of
> end-to-end connectivity, performance issues, limitations on simultaneous
> connections etc etc).
> 
Exactly.

> It seems to me that it is this property of NAT that people are most
> loath to lose. And why ULA looks tantalisingly delicious.
> 
Yeah, but, if we take a step back and look for what they actually want
that they are willing to give up everything else to get, it usually boils
down to two things:

	1.	Obfuscation of host addresses
	2.	Ability to move an entire topology from one number space to
		another without reconfiguring the topology.

IPv6 solves 1 with privacy addresses. These are horrible and I hope
nobody really uses them, but, they're better than NAT.

The solution to number 2 depends again on the circumstance. IPv6
offers a variety of tools for this problem, but, I have yet to see an
environment where the other tools can't offer a better solution than
NAT.

Owen





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