5 ms·

(First I want to make a point/clarification. When I say v4-only, I mean a dual stacked host connected to Internet only via v4. Likewise for v6.) If you don't h

(First I want to make a point/clarification. When I say v4-only, I mean a dual stacked host connected to Internet only via v4. Likewise for v6.) If you don't have v4 and v6 interoperability - that is v4-only cannot connect to v6-only and vice-versa, how does the Internet (mostly v4-only hosts) go to v6?

snuxoll 7y ago
NAT64/DNS64 allow a v6-only host to connect to v4-only hosts. If you are a T-Mobile US customer this is literally how you have all IPv4 connectivity. Here are AAAA records I get for amazon.com from my T-Mobile iPhone: amazon.com. 2S IN AAAA 2607:7700::19:0:1:cdfb:f267 amazon.com. 2S IN AAAA 2607:7700::19:0:1:b020:67cd amazon.com. 2S IN AAAA 2607:7700::19:0:1:b020:62a6 These are NAT64 addresses within TMoUS’ prefix, if I try to ping an IPv4 address it is rewritten automatically as well (though this is a feature of iOS). If you get people to v6 they can continue to access v4 with numerous transition tools like this, even if dual-stack isn’t an option. You can’t go the other way though.
- commandersaki 7y ago
  So NAT64/DNS64 is really about connectivity to v4-only. This only adds more value to the v4 network by giving it more reach. If you want to reach the v6 Internet, the best way is to have a transition mechanism for v4-only hosts to talk to v6.
  - snuxoll 7y ago
    Unfortunately that’s not possible, v6 has plenty of address space so you can carve a /96 out of your network to implement a transition layer so clients can be v6-only before the larger internet. There’s no way to represent the v6 network in 32-bit v4 addresses, so you have to start getting clients to v6 first.
    - commandersaki 7y ago
      v4-only means (as specified earlier) that connectivity is over a routable v4 address; a v4 host in a v4-only network can be dual stack, so it's possible to talk to v6 addresses, which this proposal actually addresses.
jcranmer 7y ago
For all practical purposes, every OS networking stack is dual-stacked, so v4-only/v6-only is taken to mean that there is only a routable IPv4/IPv6 address. v4-only and v6-only cannot in general talk to each other. There needs to be some intermediary to convert between IPv4 and IPv6 somehow. The transition from IPv4 to IPv6 is mostly progressing by having servers dual-stack (give them both IPv4 and IPv6 addresses) and dual-stacking the residential networks, or giving up on IPv4 for your internal network and using NAT64. You could in principle do the same thing for servers, but doing that 4-to-6 translation for the initial recipient of a connection request (i.e., the server) is more difficult than the initial sender (i.e., the client).

snuxoll 7y ago

NAT64/DNS64 allow a v6-only host to connect to v4-only hosts. If you are a T-Mobile US customer this is literally how you have all IPv4 connectivity. Here are AAAA records I get for amazon.com from my T-Mobile iPhone: amazon.com. 2S IN AAAA 2607:7700::19:0:1:cdfb:f267 amazon.com. 2S IN AAAA 2607:7700::19:0:1:b020:67cd amazon.com. 2S IN AAAA 2607:7700::19:0:1:b020:62a6 These are NAT64 addresses within TMoUS’ prefix, if I try to ping an IPv4 address it is rewritten automatically as well (though this is a feature of iOS). If you get people to v6 they can continue to access v4 with numerous transition tools like this, even if dual-stack isn’t an option. You can’t go the other way though.

commandersaki 7y ago
So NAT64/DNS64 is really about connectivity to v4-only. This only adds more value to the v4 network by giving it more reach. If you want to reach the v6 Internet, the best way is to have a transition mechanism for v4-only hosts to talk to v6.
- snuxoll 7y ago
  Unfortunately that’s not possible, v6 has plenty of address space so you can carve a /96 out of your network to implement a transition layer so clients can be v6-only before the larger internet. There’s no way to represent the v6 network in 32-bit v4 addresses, so you have to start getting clients to v6 first.
  - commandersaki 7y ago
    v4-only means (as specified earlier) that connectivity is over a routable v4 address; a v4 host in a v4-only network can be dual stack, so it's possible to talk to v6 addresses, which this proposal actually addresses.

jcranmer 7y ago

For all practical purposes, every OS networking stack is dual-stacked, so v4-only/v6-only is taken to mean that there is only a routable IPv4/IPv6 address. v4-only and v6-only cannot in general talk to each other. There needs to be some intermediary to convert between IPv4 and IPv6 somehow. The transition from IPv4 to IPv6 is mostly progressing by having servers dual-stack (give them both IPv4 and IPv6 addresses) and dual-stacking the residential networks, or giving up on IPv4 for your internal network and using NAT64. You could in principle do the same thing for servers, but doing that 4-to-6 translation for the initial recipient of a connection request (i.e., the server) is more difficult than the initial sender (i.e., the client).