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Comment by zamadatix | Hacker News Reader

Dual stack (run both and try to use v6 first) and NAT64 (run IPv6 only and NAT to v4 at the edge) are the main methods today. The former is more common inside homes/enterprises while the latter is more common in modern large carrier networks such as mobile phones since the alternative would be to CGNAT (double NAT) anyways and that creates more problems for clients than NAT64 (+more work to deploy).

Not to say CGNAT is unheard of, particularly if the network was large, old, and needed to expand.

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CGNAT is default in our largest home ISP and on all mobile ISPs here in Brazil.

How do v4 clients (dual stacked) connected to the Internet with v4 talk to a v6 server?

Some v6 networks are able to convert your v4 to a v6 address, but that's pretty spotty.

If you are v4 only, and the server is v6 only, you really don't have much hope of connecting.

And so we must rely on v4 addresses to cater for v4 only connected hosts. This is the point the article is trying to make - for a transition to actually happen there needs to be interoperability between v4 and v6, that is v4-only clients need to talk to v6-only servers, and v6-only servers need to talk to v4-only clients. That is a fundamental requirement for a transition plan which provides a straight-forward path from v4 to v6.

Which is dual-stack with a grandual phaseout of v4. We already pay for the bloat of the v4 routing tables, but nobody can even think of phasing them out until stuff actually starts using v6. But nobody wants to deploy v6 because everyone has this mistaken belief that it’s easier to stretch v4 out with more hacks to preserve addresses.

v4 only hosts are rarer than you would think. ISPs have been dual stacking for a while.

The Internet is mostly v4-only. What do you mean?

Do you have anything to back that up? I work in the Telco industry. The vast majority of ISPs and carriers both provide dual stacking at least, with some carriers making as much of their network v6 only.

Really the only thing that is largely stuck on v4 is large (and poorly maintained) corporate networks and cloud providers.

As I stated earlier v4 only means a network connected to the Internet via v4 without connectivity to v6.

This is the majority of networks on the Internet. Otherwise we’d see adoption greater than 20% or whatever it is.

My cloud servers from major players all have v6 address attached on launch.

There are multiple types of NAT which are simply named after what it is they NAT:

- NAT44 (what everyone is used to)

- NAT64 (what I just described)

- NAT46 (the opposite of what I just described)

- NAT66 (bad)

In this case NAT46.

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