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> The new players would each get a /24 and everyone would say that's "enough". From where? All then-existing IPv4 addresses would get all the bits behind them

> The new players would each get a /24 and everyone would say that's "enough". From where? All then-existing IPv4 addresses would get all the bits behind them. There would, at the time, still be IPv4 addresses available that could be given out, and as people got them they would also get the extend "IPv4x" address associated with them. But at some point IPv4 addresses would all be allocated… along with all the extended addresses 'behind' them. Then what? The extended IPv4x addresses are attached to the legacy IPv4 addressed they are 'prefixed' by, so once the legacy bits are assigned, so are the new bits. If someone comes along post-legacy-IPv4 exhaustion, where do new addresses come from? You're in the exact same situation as we are now: legacy code is stuck with 32-bit-only addresses, new code is >32-bits… just like with IPv6. Great you managed to purchase/rent a legacy address range… but you still need a translation box for non-updated code… like with CG-NAT and IPv6.

wmf 7mo ago
ISPs can still get /24 of IPv4 today for free even after it "ran out". This comes from space that was set aside before runout. https://www.arin.net/participate/policy/nrpm/#4-10-dedicated-ipv4-allocation-to-facilitate-ipv6-deployment https://www.arin.net/participate/policy/nrpm/#4-10-dedicated... This IPv4x thing is bullshit but we should be accurate about how it would play out.
- throw0101d 7mo ago
  So under this IPv4x proposal one gets an IPv4 /24, and receives a whole bunch of extended address space 'for free'. But right now you can get an IPv4 /24 (as you say), but you can get an IPv6 allocation 'for free' as we speak. In both cases 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 to reach extended-only destination (like IPv6 with DNS64/NAT64, CLAT, etc) You're updating the exact same code paths in both the IPv4x 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.
  - zadikian 7mo ago
    The point of IPv4x and similar proposals is to avoid a dual-stack scenario by reducing the risk of switching. Going from v4 to v4x doesn't mean changing all your routes and addresses (and possibly blacklists), you just enable it and everything still works. Network components can get updated/replaced with the longer addr field behind the scenes without user impact, then once the world is ready, ISPs can finally start using the extra address space.
    - Dagger2 7mo ago
      But like the similar proposals, it fails to avoid a dual-stack scenario. Note that going from v4 to v6 also doesn't mean changing all your routes and addresses; you just enable it and everything still works. Network components can get updated behind the scenes without user impact. There's no flag day though; ISPs can start using the new address space as soon as they want, rather than being forced to wait until everybody else is ready.
      - zadikian 7mo ago
        You do have to change everything to actually use v6 rather than having v4 on the side. Re: flag day, I guess you could use the new address space of v4x before everyone is ready, provided the other side supports it.
        throw0101d 7mo ago
        Having partial deployment of IPv4x is no different than having partial deployment of IPv6: you have islands of it and have to fall back to the 'legacy' IPv4-plain protocol when the new protocol fails to connect: * https://en.wikipedia.org/wiki/Happy_Eyeballs https://en.wikipedia.org/wiki/Happy_Eyeballs Getting "free" new-protocol addresses is also nothing new: > 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 https://en.wikipedia.org/wiki/6to4 Translation boxes and tunnels are still needed for both IPv4x and IPv6.

wmf 7mo ago

ISPs can still get /24 of IPv4 today for free even after it "ran out". This comes from space that was set aside before runout. https://www.arin.net/participate/policy/nrpm/#4-10-dedicated-ipv4-allocation-to-facilitate-ipv6-deployment https://www.arin.net/participate/policy/nrpm/#4-10-dedicated... This IPv4x thing is bullshit but we should be accurate about how it would play out.

throw0101d 7mo ago
So under this IPv4x proposal one gets an IPv4 /24, and receives a whole bunch of extended address space 'for free'. But right now you can get an IPv4 /24 (as you say), but you can get an IPv6 allocation 'for free' as we speak. In both cases 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 to reach extended-only destination (like IPv6 with DNS64/NAT64, CLAT, etc) You're updating the exact same code paths in both the IPv4x 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.
- zadikian 7mo ago
  The point of IPv4x and similar proposals is to avoid a dual-stack scenario by reducing the risk of switching. Going from v4 to v4x doesn't mean changing all your routes and addresses (and possibly blacklists), you just enable it and everything still works. Network components can get updated/replaced with the longer addr field behind the scenes without user impact, then once the world is ready, ISPs can finally start using the extra address space.
  - Dagger2 7mo ago
    But like the similar proposals, it fails to avoid a dual-stack scenario. Note that going from v4 to v6 also doesn't mean changing all your routes and addresses; you just enable it and everything still works. Network components can get updated behind the scenes without user impact. There's no flag day though; ISPs can start using the new address space as soon as they want, rather than being forced to wait until everybody else is ready.
    - zadikian 7mo ago
      You do have to change everything to actually use v6 rather than having v4 on the side. Re: flag day, I guess you could use the new address space of v4x before everyone is ready, provided the other side supports it.
      - throw0101d 7mo ago
        Having partial deployment of IPv4x is no different than having partial deployment of IPv6: you have islands of it and have to fall back to the 'legacy' IPv4-plain protocol when the new protocol fails to connect: * https://en.wikipedia.org/wiki/Happy_Eyeballs https://en.wikipedia.org/wiki/Happy_Eyeballs Getting "free" new-protocol addresses is also nothing new: > 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 https://en.wikipedia.org/wiki/6to4 Translation boxes and tunnels are still needed for both IPv4x and IPv6.