Absolutely not. Existing IPv4 hardware and software expects addresses to be 4 bytes long. They expect packets to have a 4 byte source address at offset 12 in the header, then a 4 byte destination address at offset 16. Everything breaks if you try to give them a header with an 8 byte source address at offset 12 and an 8 byte destination address at offset 20.

IIRC something like that was considered when IPv6 was first being designed, be deemed insufficient for the long-term future. 64-bits is thought to be enough to stave off address starvation though, which is why IPv6 address ranges are usually assigned as /64s (my homer link has a /48 range should I wish to use it all!), so I can see your reasoning on that level.

You still need to have routers, clients, and absolutely everything to understand the new scheme to use those new addresses.

The entire ipv4 space is already mapped to reserved subsets of ipv6, by the way. e.g. ::ffff:0:0/96 (i.e. 0.0.0.0.0.0.0.0.0.0.255.255.w.x.y.z) or 64:ff9b::/96. v6 devices can already "talk to" v4. The problem is the ipv6 space is obviously not a subset of ipv4, so v4 doesn't have a clean way to talk to or even about v6.

Most of the time, this results in people thinking the big problems are one set like "if only there was a way to translate" while the real remaining problems are another set like "and how do you get people to want to transition when it works well enough for those clients in the translated state".

Yeah, about that part. This is a "now draw the rest of the fucking owl" type of idea.

Dual-stack is also the default, and CG-NAT exists as a fallback. For IPv6 only websites there is still the option to use a HTTP proxy.

How is this different from ::192.168.0.1? :)

That being said, we should take the time to understand why IPv4 is still hanging around when IPv6 has been around since before most people got internet access. What is really holding IPv6 back?

There is no "just" extending the address length:

      So it's a matter of mathematical and physical fact that to expand
      the address size, you must change the protocol, and that means 
      [three] things immediately:

            You have to change the version number.

            You have to add new code to handle the new version.

      […]

            You need a coexistence technique so that updated systems, 
            with the new protocol, can connect to old systems that know 
            nothing of the new protocol.

      Two minutes of thought show that this third requirement has only 
      two solutions:

            (3A) Dual stack, in which the new machines speak both 
                 the old (IPv4) and new (IPng) protocol.

            (3B) Translation, in which something translates addresses
                 between the old and new protocols.

* https://datatracker.ietf.org/doc/html/rfc1671

> Keeps all the nice parts of IPv4, doesn’t require everyone to switch to an entirely new system, backwards compatible with existing hardware/software. Problem solved.

You have to ship new code to every 'network element' to support your "IPv4+" plan. Just like with IPv6.

You also have to update DNS to create new resource record types ("A" is hard-coded to 32-bits) to support the new longer addresses, and have all user-land code start asking for, using, and understanding the new record replies. Just like with IPv6. (A lot of legacy code did not have room in data structures for multiple reply types: sure you'd get the "A" but unless you updated the code to get the "A+" address (for "IPv4+" addresses) you could never get to the longer with address… just like IPv6 needed code updates to recognize AAAA, otherwise you were A-only.)

You need to update socket APIs to hold new data structures for longer addresses so your app can tell the kernel to send packets to the new addresses. Just like with IPv6. In any 'address extension' plan the legacy code cannot use the new address space; you have to:

* update the IP stack (like with IPv6)

* tell applications about new DNS records (like IPv6)

* set up translation layers for legacy-only code that cannot be update to reach IPv4+-only destination (like IPv6 with DNS64/NAT64, CLAT, etc)

You're updating the exact same code paths in both the "IPv4+" and IPv6 scenarios: dual-stack, DNS, socket address structures, dealing with legacy-only code that is never touched to deal with the larger address space.

"Just adding more bits" means updating a whole bunch of code (routers, firewalls, DNS, APIs, userland, etc) to handle the new data structures. There is no "just": it's the same work for IPv6 as with any other idea.

the thing is that it does require a switch similar to ipv6. but maybe there’s a subnet that maps 1 to 1 with the legacy block?

something like this could theoretically be pinned onto ipv6 AND anyone could do it, just select a 98 bit prefix you own, and the rest of the 32 bits you can map to ipv4.

phase -1 could be tunneling traffic through a single zone proxy which would be inefficient and is purely conceptual

phase 0 would be the same, but with an anycast ipv6,same ip that resolves differently based on location, like 8.8.8.8

phase 1 would be the mapping prefix to ipv4 (and viceversa?) being distributed to the routing tables like, which could be done via application logic (most efficient), or via some deep arcane isp routing conf files, or just a hell of a lot of routing table entries for each ipv4 but duplicated, possibly programatically controlled by an application that generates router table files as a target, thus avoiding desyncs and effectively becoming the first option of application level implementation

maybe something like this already exists though

of course it’s horrible hacking (as hacking in the non crime sense often is), but it allows for a purely technical solution to issues of political and administrative nature.. which is all the rage nowadays

https://xkcd.com/927/

But the big big problem isn't windows/Linux/mac. Writing drivers for those are "easy".

The problem lies in all the networking gear speaks only IPv4 and/or 6. LLM assisted hacks can get into maintenance areas, but these devices are also built to support the least amount of things. Like, there may not be enough ram or storage to even run it.

And 20 years in, you see how well IPv6 has taken off :eyeroll:

And even on my network, I disabled IPv6. My upstream ISP is doing something that makes '6 unstable, but '4 is fine. And I find most network engineers don't have to maintain '6, so they never really learn it.