> Only the edge equipment would need to be IPv4+ aware. And even that awareness could be quite gradual, since you would have NAT to fall back on when receiving an IPv4 classic packet at the network. It can even be customer deployed. Add an IPv4+ box on the network, assign it the DMZ address, and have it hand out public IPV4+ addresses and NAT them to the local IPv4 private subnet.

Congratulations, you’ve re-invented CGNAT, with none of the benefits, and the additional hassle of it being an entirely new protocol!

No. No “extra bits” on an IPv4 address would have ever worked. NAT itself is a bug. Suggesting that as an intentional design is disingenuous.

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avidiax 2 hours ago | parent [-]

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.

	▲	sgjohnson an hour ago \| parent [-]
		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!