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