On Tue, Oct 02, 2007 at 09:50:09PM +0200, Iljitsch van Beijnum wrote:
On 2-okt-2007, at 16:55, Mark Newton wrote:
So everyone will deploy IPv6 applications, which require no ALGs, instead. Isn't that a solution that everyone can be happy with?
Well, I can think of a couple of things that make me unhappy:
Doubtless.
- IPv4 vs IPv6 is completely invisible to the user. I regularly run netstat or tcpdump to see which I'm using, I doubt many people will do that. So if IPv6 works and IPv4 doesn't, that will look like random breakage to the untrained user rather than something they can do something about.
With respect, that's why a bunch of us have been suggesting using techniques such as NAT-PT to make sure taht IPv6 works _and_ IPv4 works. If the mechanisms used lack sufficient quantities of perfection, they'll be modified until they're "good enough."
- If we do NAT-PT and the ALGs are implemented and then the application workarounds around the ALGs, it's only a very small step to wide scale IPv6 NAT.
And thus the sky falls. Perhaps it's a perspective issue, but I really don't see a problem with that. If the network works, who cares? Perhaps you'd be happier if, in recognition of the fact that NAT appears to be a dirty word, we called it something else. The IPv6 people have already jumped on this bandwagon, so it shouldn't be a huge gulf to bridge: SHIM6 is basically wide-scale highly automated NAT, in which layer-3 addresses are transparently rewritten for policy purposes (a "SHIM6 middlebox," if it ever existed, would be indistinguishable from a NAT box), so we have a start here: If we rename NAT, it becomes acceptable to IPv6 proponents. So my proposal is this: Instead of saying, "NAT," from now on we should say, "Layer-4 switch." I don't know about you, but I feel comfortable deploying a network which has layer-4 switches in it. I already have layer-2 and layer-3 switches, so I might as well collect the whole set. That solution to this quagmire also solves the other great problem that you seem to have in gaining acceptance: There are legitimate uses for NAT right now, and there will be in the future, so arguing for the elimination of a useful tool before we can move the Internet forward strikes me as a fundamentally regressive argument. Perhaps in years to come we'll look at the people who argue for the elimination of layer-4 switches in the same way that we look at 1980's campus network administrators who thought the whole organization should be one big broadcast domain, with no place for layer-3 switches. "Ah, look at that, he doesn't like NAT. How... quaint." :-) - mark -- Mark Newton Email: newton@internode.com.au (W) Network Engineer Email: newton@atdot.dotat.org (H) Internode Systems Pty Ltd Desk: +61-8-82282999 "Network Man" - Anagram of "Mark Newton" Mobile: +61-416-202-223