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When the options are: let them profit awkwardly from a windfall, claw it back against their will, or make their IPv4 assets obsolete, focusing on the latter see

When the options are: let them profit awkwardly from a windfall, claw it back against their will, or make their IPv4 assets obsolete, focusing on the latter seems most productive. The UK’s largest mobile provider now gives me an IPv6 only connection and I didn’t even notice.

JimDabell 7y ago
Apple have made it a hard requirement for apps to operate correctly on IPv6-only connections for a few years now. If your app doesn't work unless it's on IPv4, Apple will reject it.
- tyingq 7y ago
  Pretty sure that doesn't mean all distant API endpoints need ipv6 addresses. Just means no hardcoded ipv4 or incompatible API calls. So that ipv6 to ipv4 gateways work. So, the app is ready, but apple isn't dictating much about your backend.
  - WorldMaker 7y ago
    Apple's mandate happened because a couple US Telecoms asked them to. The US has plenty of cell towers that are IPv6-only, and at least a couple US carriers are now IPv6-only or IPv6-primarily, with more planning to switch. All the carriers have big NAT64 gateways of course to keep the internet from entirely breaking, but that's still an avoidable bottleneck from a backend perspective. Apple themselves may not be dictating what the backend is doing, but they are doing a lot of Happy Eyeballs [1] tests on your backend and IPv6 without NAT64 proxies in the way is likely the fastest experience for a lot of real mobile users today. [1] https://en.wikipedia.org/wiki/Happy_Eyeballs https://en.wikipedia.org/wiki/Happy_Eyeballs
- bifrost 7y ago
  That can't be totally true, Twitter doesn't work on v6.
  - WorldMaker 7y ago
    Apps can't request IPv4 addresses directly (ie, no hardcoded IPv4 addresses allowed), but DNS may still return them for indirect use (via the Happy Eyeballs [1] approach that heavily favors IPv6 because an increasing number of mobile carriers are IPv6-only or IPv6-primarily and IPv4 addresses must get sent to NAT64 gateways). [1] https://en.wikipedia.org/wiki/Happy_Eyeballs https://en.wikipedia.org/wiki/Happy_Eyeballs
  - rstuart4133 7y ago
    Not only can it be true I've done it at a conference, which is to say I've implemented an IPv6 only network for conference delegates and had zero connectivity complaints. The ingredient you are missing is while the clients only talk IPv6, the gateway they go through (must) have both IPv6 and IPv4 addresses. There is a well defined mapping from IPv4 to IPv6 addresses, so if the IPv6 clients need to communicate with a IPv4 only host they use it's mapped IPv6 address. The gateway then NAT's all those mapped IPv6 addresses to it's IPv4 address. Which only leave the problem of does an IPv6 client know to use an mapped IPv4 address, given it is supposed to know nothing about the IPv4 world. The answer is you make it use a DNS server that lies. I'll leave it to you to figure out exactly how it lies, but it isn't hard to figure out given it has clients that only understand AAAA records, and some hosts (such as twitter) that only resolve to A records.
    - bifrost 7y ago
      > The gateway then NAT's all those mapped IPv6 addresses to it's IPv4 address. Right, then its not a pure v6 network, its got v4 somewhere patched in. When I'm on my pure v6 network at home, Twitter does not work.
philjohn 7y ago
And yet one of the largest UK ISP's by customer count (Virgin Media) still haven't managed to roll out DS-LITE ... 6 years after announcing it.
ryacko 7y ago
The major browser currently hides "www" and " https:// https:// " by default. Now it has to hide port numbers and IPV4 space will suddenly be multiplied by less than 2^16.

JimDabell 7y ago

Apple have made it a hard requirement for apps to operate correctly on IPv6-only connections for a few years now. If your app doesn't work unless it's on IPv4, Apple will reject it.

tyingq 7y ago
Pretty sure that doesn't mean all distant API endpoints need ipv6 addresses. Just means no hardcoded ipv4 or incompatible API calls. So that ipv6 to ipv4 gateways work. So, the app is ready, but apple isn't dictating much about your backend.
- WorldMaker 7y ago
  Apple's mandate happened because a couple US Telecoms asked them to. The US has plenty of cell towers that are IPv6-only, and at least a couple US carriers are now IPv6-only or IPv6-primarily, with more planning to switch. All the carriers have big NAT64 gateways of course to keep the internet from entirely breaking, but that's still an avoidable bottleneck from a backend perspective. Apple themselves may not be dictating what the backend is doing, but they are doing a lot of Happy Eyeballs [1] tests on your backend and IPv6 without NAT64 proxies in the way is likely the fastest experience for a lot of real mobile users today. [1] https://en.wikipedia.org/wiki/Happy_Eyeballs https://en.wikipedia.org/wiki/Happy_Eyeballs
bifrost 7y ago
That can't be totally true, Twitter doesn't work on v6.
- WorldMaker 7y ago
  Apps can't request IPv4 addresses directly (ie, no hardcoded IPv4 addresses allowed), but DNS may still return them for indirect use (via the Happy Eyeballs [1] approach that heavily favors IPv6 because an increasing number of mobile carriers are IPv6-only or IPv6-primarily and IPv4 addresses must get sent to NAT64 gateways). [1] https://en.wikipedia.org/wiki/Happy_Eyeballs https://en.wikipedia.org/wiki/Happy_Eyeballs
- rstuart4133 7y ago
  Not only can it be true I've done it at a conference, which is to say I've implemented an IPv6 only network for conference delegates and had zero connectivity complaints. The ingredient you are missing is while the clients only talk IPv6, the gateway they go through (must) have both IPv6 and IPv4 addresses. There is a well defined mapping from IPv4 to IPv6 addresses, so if the IPv6 clients need to communicate with a IPv4 only host they use it's mapped IPv6 address. The gateway then NAT's all those mapped IPv6 addresses to it's IPv4 address. Which only leave the problem of does an IPv6 client know to use an mapped IPv4 address, given it is supposed to know nothing about the IPv4 world. The answer is you make it use a DNS server that lies. I'll leave it to you to figure out exactly how it lies, but it isn't hard to figure out given it has clients that only understand AAAA records, and some hosts (such as twitter) that only resolve to A records.
  - bifrost 7y ago
    > The gateway then NAT's all those mapped IPv6 addresses to it's IPv4 address. Right, then its not a pure v6 network, its got v4 somewhere patched in. When I'm on my pure v6 network at home, Twitter does not work.

philjohn 7y ago

And yet one of the largest UK ISP's by customer count (Virgin Media) still haven't managed to roll out DS-LITE ... 6 years after announcing it.

ryacko 7y ago

The major browser currently hides "www" and " https:// https:// " by default. Now it has to hide port numbers and IPV4 space will suddenly be multiplied by less than 2^16.