[zinekeller]

> Nothing about IPv6 forbids the existence of IPv4.

Which is now the reality, but at the time IPv6 was created IPv4 was planned to be killed permanently.

Which while impossible in hindsight, the way IPv6 were designed (without even a semblance of a "private" network, even just two IPv6 addresses*) actually raises the question if IPv6 were really that well-designed.

* Okay, link-local addresses do exist, but they're not amenable or even map to how IPv4-style private networks work.

[stephen_g]

Not link local addresses - there’s a whole space for ‘Unique Local Addresses’ [1]. It’s basically analogous to the private IPv4 space (apart from the fact that you need a separate globally routable address to access the internet from, but that’s not hard).

1. https://en.wikipedia.org/wiki/Unique_local_address

[Dagger2]

The general plan was, and is still, to stop using v4 once it stops being useful, in much the same way that people stopped using IPX when it stopped being useful. (By which I mean: people still use IPX today, but in general you don't need to think about it.)

You can do private networks on v6; there's a massive range allocated for them (fc00::/7).

In general, v6 is designed just fine. Most of the complaints you see are from people that either don't know what v6 can do ("why didn't they just implement <thing that v6 already does>?") or don't realize that what they want is impossible ("why not just ignore the pigeonhole principle?").