I think that's meant to be covered by the "IPv4x when we can. NAT when we must" part, in particular "ISPs used carrier‑grade NAT as a compatibility shim rather than a lifeline: if you needed to reach an IPv4‑only service, CGNAT stepped in while IPv4x traffic flowed natively and without ceremony."

It seemed strange that the need for CGNAT wasn't mentioned until after the MIT story. The "Nothing broke" claim in that story seems unlikely; I was on a public IP at University at the end of the 90s and if I'd suddenly been put behind NAT, some things I did would have broken until the workarounds were worked out.

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lxgr 3 hours ago | parent [-]

> "ISPs used carrier‑grade NAT as a compatibility shim rather than a lifeline: if you needed to reach an IPv4‑only service, CGNAT stepped in while IPv4x traffic flowed natively and without ceremony."

What's the difference between that and dual stack v4/v6, though? Other than not needing v6 address range assignments, of course.

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tocitadel an hour ago | parent [-]

Try an IPv6-only VPS and see how quickly something breaks for you. Dual-stack fails miserably when the newer stack is incompatible with the older one. With a stack that extends the old stack, you always have something to fallback to.

To replace something, you embrace it and extend it so the old version can be effectively phrased out.

	▲	lxgr an hour ago \| parent [-]
		> Try an IPv6-only VPS and see how quickly something breaks for you. Who's arguing for that? That would be completely non-viable even today, and even with NAT64 it would be annoying. > Dual-stack fails miserably when the newer stack is incompatible with the older one. Does it? All my clients and servers are dual stack. > With a stack that extends the old stack, you always have something to fallback to. Yes, v4/v6 dual stack is indeed great! > To replace something, you embrace it and extend it so the old version can be effectively phrased out. Some changes unfortunately really are breaking. Sometimes you can do a flag day, sometimes you drag out the migration over years or decades, sometimes you get something in between. We'll probably be done in a few more decades, hopefully sooner. I don't see how else it could have realistically worked, other than maybe through top-down decree, which might just have wasted more resources than the transition we ended up with.