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Comment Re:First, a question: Can v4 devices talk to v6? (Score 1) 191 191

So first, a question: Can v4 devices talk to v6 devices?

Not without one of the transition mechanisms (NAT64, 6to4, Teredo). There's no space for a v6 address in the v4 dest header field.

If I have an older device, such as a printer, that can only talk v4, then in order to talk to it, I need a v4 address.
Given that there will be some devices out there that can only talk v4, then there needs to be some way for v4 machines to talk to v6 machines.

Generally this is done by not removing the v4 address from your v6-capable machines. The v6-capable machines are inevitably also capable of talking v4, and they're hooked up to the same ethernet segment as your v4-only devices, so they'll also be getting v4 addresses. They just use those when they want to talk to a v4-only machine.

So, is it possible for a v6 host to initiate a connection to a v4 device by using some magic prefix to indicate "the bottom 4 bytes contain a v4 address, and you, router, are supposed to pretend that you are talking v4 using that"?

This is roughly what NAT64 does. (I will note however that NAT64 has all of the problems that NAT44 does, plus a few extra of its own.)

If so, the next question is: when the v4 device wants to respond, what does it put into it's destination IP field to get back to the v6 device?

It uses whatever was in the source field, which will be the v4 address of the NAT64 gateway. The gateway is responsible for maintaining state for each connection, so it knows what the original v6 src address was.

If I cannot talk to a v4-only device from a v6-only host, then I need to have a mixed 4/6 machine.

Yep. Dual stack is the expected (and easiest) migration method.

The need for routers to be able to translate between v4 and v6 to support old hardware leads into the question about V8.

This isn't really necessary. As I say: dual stack is the expected way to deal with old hardware.

Comment Re:wft ever dude! (Score 1) 191 191

This already happens automatically. With privacy addresses enabled (which is the default on pretty much everything), your system will automatically generate itself a new random address every 24 hours. The GP's worry about being able to trivially identify which device was using each IP will not actually happen (unless you've specifically gone and disabled privacy addresses...).

Comment Re:Slashdot crying wolf again... (Score 1) 191 191

An IP is not a "digital fingerprint". Knowing the v6 address won't let you figure out who was using it at the time, or even what device it was assigned to.

With privacy extensions (which are on by default in basically everything), knowing the v6 address is about as useful as knowing the v4 address. Removing NAT from your network doesn't affect governments or media cartels -- but meanwhile it makes your own life much easier, so you're being dumb if you insist on using it when it's not necessary.

Comment Re:The Segway problem (Score 1) 45 45

Something like the iBot, a wheelchair that could pop up onto (and balance on) two wheels to bring you to standing eye height? Developed by the guy who would later make the Segway?

(Unfortunately, insurance companies declared it "not medically necessary" and refused to pay for it, so nobody has ever heard of it and it ended up failing.)

Comment Re:It won't work that way (Score 1) 307 307

I would've initially accepted steps towards a v6 deployment, e.g. if you've just got your v6 allocation and you're turning up BGP next week? Fine, but when you come back for more v4 in 3 months then you'd best have made some more progress or you aren't getting any.

Instead we got... a discount on your v6 allocations if you already have v4 allocations. Which has since been phased out. Woo.

Comment Re:It won't work that way (Score 1) 307 307

The fact that there are still providers that haven't finished (or even started) their deployments is exactly why extra time wouldn't be helpful. They've had years and years to deploy v6; the only reason for not being done by now is that they've been procrastinating.

We've already bought these people an extra 10-20 years with pervasive NAT and over-aggressive address conservation. Buying them an extra 2 years would just lead to another 2 years of procrastination. Enough is enough. It's time they got a move on, and if they have to suffer through some (more) pain to get there then they only have themselves to blame.

I'd've loved to see ARIN put a "you can only get v4 space if you show us that you're doing a serious v6 deployment too" policy on their last /8. Bit late for that now though.

Comment Re:It won't work that way (Score 1) 307 307

None of this will fix anything, because the v4 space just plain isn't big enough. It doesn't matter how you slice and dice it: there ain't enough of it.

You might be able to buy some extra time this way, but we've had more than enough time already. "More time" isn't what we need at this point.

Comment Re:Fricking finally. (Score 1) 307 307

Not really:

"What's the DNS IP?"

"It's at 53"

"Got it!"

and everybody involved in the conversation understands that the IP is 2001:db8:42::53, since the company's allocation is 2001:db8:42::/48. Heck, this is less bits to remember than 203.0.113.42 + 10.10.10.1, so if anything you're describing a problem with v4, not v6.

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