All IPv4 addresses can already be represented in the IPv6 address space, by the same method you describe here.
As for “backwards compatible with IPv4”, I’m afraid that’s not possible for the same reason IPv6 isn’t getting major traction. Right now, we literally CANNOT upgrade our entire networking infrastructure. What you’re proposing requires updating every switch and middlebox to support routing using additional bytes, which is physically impossible. The biggest problem would be middleboxes, which includes NAT router, firewalls, etc. For context: most middleboxes drop anything that is not IPv4/TCP or IPv4/UDP. This is why QUIC is encapsulated inside a UDP header (and funny enough, these vendors STILL didn’t learn, trying to match a “QUIC header” despite Google themselves saying there is no fixed QUIC header), and RoCEv2 using a header that looks like UDP. There is absolutely no way a new L3 protocol that is not IPv4 (and in some cases, IPv6) can be supported by these boxes.
The only time we successfully replaced the L3 protocol was with the adaption of IPv4. In which networks were much smaller, and networking research was under the US DoD. The DoD basically gave an ultimatum that “if you don’t switch to IP by this date we will cut your funding”. That won’t fly now that the Internet is managed by a cluster of ISPs.
Also: IPv6 is stupid simple. It’s basically IPv4, with everything not commonly used stripped out (and added back with “optional headers”, and a much larger address field. Since the address field is much larger, it is recommended to write them in hexadecimal, which looks more scary than IPv4.
Side note: I don’t think any of these IP protocols is the solution here. If you only keep extending the address field, you’re still gonna run into IP problems (routing, ddos, caching). The future of the Internet should be something like NDN. But for the same reason I described above, I don’t think that’s going to happen unless the Internet is a pile of smoldering ruins.
Networking researcher here chiming in.
All IPv4 addresses can already be represented in the IPv6 address space, by the same method you describe here.
As for “backwards compatible with IPv4”, I’m afraid that’s not possible for the same reason IPv6 isn’t getting major traction. Right now, we literally CANNOT upgrade our entire networking infrastructure. What you’re proposing requires updating every switch and middlebox to support routing using additional bytes, which is physically impossible. The biggest problem would be middleboxes, which includes NAT router, firewalls, etc. For context: most middleboxes drop anything that is not IPv4/TCP or IPv4/UDP. This is why QUIC is encapsulated inside a UDP header (and funny enough, these vendors STILL didn’t learn, trying to match a “QUIC header” despite Google themselves saying there is no fixed QUIC header), and RoCEv2 using a header that looks like UDP. There is absolutely no way a new L3 protocol that is not IPv4 (and in some cases, IPv6) can be supported by these boxes.
The only time we successfully replaced the L3 protocol was with the adaption of IPv4. In which networks were much smaller, and networking research was under the US DoD. The DoD basically gave an ultimatum that “if you don’t switch to IP by this date we will cut your funding”. That won’t fly now that the Internet is managed by a cluster of ISPs.
Also: IPv6 is stupid simple. It’s basically IPv4, with everything not commonly used stripped out (and added back with “optional headers”, and a much larger address field. Since the address field is much larger, it is recommended to write them in hexadecimal, which looks more scary than IPv4.
Side note: I don’t think any of these IP protocols is the solution here. If you only keep extending the address field, you’re still gonna run into IP problems (routing, ddos, caching). The future of the Internet should be something like NDN. But for the same reason I described above, I don’t think that’s going to happen unless the Internet is a pile of smoldering ruins.