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Comment by avidiax | Hacker News Reader

I have not "reinvented CGNAT". It is hierarchal public addressing similar to IPv4 and IPv6.

The edge router has an IPv4+ subnet (either a classic v4 address, or part of a v4+ address). It maintains an L2 routing table with ARP+, and routes IPv4+ packets to the endpoint without translation. Private subnetting and NAT is only needed to support legacy IPv4 clients.

CGNAT pools IPv4 public addresses and has an expanded key for each connection, and translates either 4 to 6 or into a private IPv4 subnet. My proposal needs no pooling and only requires translation if the remote host is IPv4 classic and the edge router is not assigned a full IPv4+/24.

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Not just the edge router. Every router between the ISP edge and the destination edge.

And since the goal is “backwards-compatability”, you’d always need to poll, because a “legacy” IPv4 client would also be unable to send packets to the IPv4+ destination. Or receive packets with an IPv4+ source address.

And it would be an absolute nightmare to maintain. CGNAT + a quasi backwards-compatible protocol where the backwards-compatability wouldn’t work in practice.

So you would have exactly the same problem as IPv6. I can say the same about v4 and v6 today. You could just turn off IPv4 on the internet, and we’d only need to do translation on the edge for the legacy clients that would still use IPv4. You can even put IPv4 addresses in IPv6 packets!

I think you've actually reinvented 6to4, or something morally very close to it.

Each v4 address has a corresponding /48 of IPv6 tunnelled to it. The router with that IP receives the tunnelled v6 packets, extracts them and routes them on natively to the end host. This is something that v6 already does, so you don't need to make posts complaining about how dumb they were for not doing it.

That's quite true, but in this counterfactual, IPv4+ doesn't pretend that 6to4 is just a transition mechanism to an all-IPv6 future. That is, IPv4+ is as-if 6to4 was the default, preferred, or only mechanism, and core routers were never demanded to upgrade.

It's an edge based solution similar to NAT, but directly addressable. And given that it extends IPv4, I think it would have been much more "marketable" than IPv6 was.

But again, this is all counterfactual. The IETF standardized IPv6, and 30 years on it's still unclear that we will deprecate IPv4 anytime soon.

But we do want a v6-only future, right? We don't want to be running both protocols forever, which is what you'd be asking for.

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