Comment by throw0101a
14 hours ago
> Yes it's 3A. They didn't need to make the new protocol have separate state from the old one.
Except there will be a period of time when many 'network elements' (routers, firewalls, servers (web, SMTP, DNS, etc), clients) will not be updated for the new protocol so you may also need 3B.
And this will be true for any IPng, and not just the one that just happened to be chosen to be for "IPv6" (which was SIPP, over CATNIP and TUBA; see RFC 1752).
> Let me keep my old address on the new protocol.
You can/could. You can encourage people who have addresses in the older protocol to use the new one with "free" "automatic" address assignments in the new one to encourage translation and tunnelling:
> For any 32-bit global IPv4 address that is assigned to a host, a 48-bit 6to4 IPv6 prefix can be constructed for use by that host (and if applicable the network behind it) by appending the IPv4 address to 2002::/16.
> For example, the global IPv4 address 192.0.2.4 has the corresponding 6to4 prefix 2002:c000:0204::/48. This gives a prefix length of 48 bits, which leaves room for a 16-bit subnet field and 64 bit host addresses within the subnets.
* https://en.wikipedia.org/wiki/6to4
And the 'old' IPv4 addresses are available in the new IPv6 world:
> Addresses in this group consist of an 80-bit prefix of zeros, the next 16 bits are ones, and the remaining, least-significant 32 bits contain the IPv4 address. For example, ::ffff:192.0.2.128 represents the IPv4 address 192.0.2.128. A previous format, called "IPv4-compatible IPv6 address", was ::192.0.2.128; however, this method is deprecated.[5]
* https://en.wikipedia.org/wiki/IPv6#IPv4-mapped_IPv6_addresse...
There is no way around this limitation: you must have a separate network space because of physical limitations.
Your supposed solution, and many others, have been thought of already. Have been tried. You are not thinking of anything new in your proposal.
6to4 and NAT64 are not what I'm saying. Those involve a relay server and v4 translation, and there's an entire memo on why that's unreliable and abandoned. I want to switch to fully native IPv6 without changing any of my addresses. There's no reason this should be impossible.
> I want to switch to fully native IPv6 without changing any of my addresses. There's no reason this should be impossible.
… except for the fact that you have to have completely new data structures and packet format to fit more address bits, and once you change the structures you need a new version field so any gear that sees a packet knows where to use the old code paths or new ones.
Then you're at the point where you have to push new code everywhere to handle these changes, and some nodes will have only the old code and some the new code, so now you're into translation and/or tunnelling to make sure the old addresses can talk to new addresses. Depending on their risk tolerance, some operators will enable the new code and some will not.
You also have to update DNS with new records, as A records are hard-coded to 32 bits. So now you're updating DNS libraries and user land.
There is no way to expand address space without going through all the same issues as what we call "IPv6" (originally SIPP) has gone through.
* https://github.com/becarpenter/misc/blob/main/why6why.md
I know. All these things were possible and completed for IPv6, but that's only part of the battle. The rest is making it easy for users at various levels to migrate. IPv6 didn't do that, that's why we're stuck in today's situation.
I want the minimum initial migration to just be a toggle to use v6 with your old v4 address, not a full network restructuring upfront. There's no requirement to change DNS upfront if your IPv6 addresses are 32-bit. V6 translation to/from v4 should be doable at any hop instead of relying on a flaky anycast relay. You shouldn't need a different DNS or DHCP server for IPv6 either, only one that supports both protocols (also shouldn't be forced to use SLAAC).
IPv6 also had an upfront requirement to change all existing routes, which is huge. That shouldn't even be needed in the final step. It should just be that people start using longer addresses given that both ends are v6. Even still there should be no requirement for every hop along the route to be v6, only the ones that go deeper than /32 near the ends.