4 ms·

> Having two internets suggests that it's totally different, in the sense that there is no address space overlap between IPv4 and IPv6 That's not at all what I

> Having two internets suggests that it's totally different, in the sense that there is no address space overlap between IPv4 and IPv6 That's not at all what I'm suggesting, I'm saying "two internets" because there are two internets: IPv4 and IPv6. You need two internet stacks on every host to deal with this, hence two internets. If everything in the IPv6 protocol suite was literally identical to IPv4, but just with some extra bytes in every address, there would still be two internets, because they are not mutually compatible. Saying "two internets" is not a judgement call on whether IPv6 changed too much or is too different. It's just the literal truth. There are two internets, because one can't communicate with the other.

Dagger2 2y ago
Well, that's just not true: $ ip -4 addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever $ ping -6 ipv4.google.com PING ipv4.google.com(sof04s06-in-f14.1e100.net (64:ff9b::142.251.140.78)) 56 data bytes 64 bytes from 64:ff9b::8efb:8c4e: icmp_seq=1 ttl=55 time=27.9 ms This is a v6-only machine (no v4 address other than lo), talking to a v4-only hostname. If it was truly not possible to communicate, this wouldn't work. > If everything in the IPv6 protocol suite was literally identical to IPv4, but just with some extra bytes in every address, because they are not mutually compatible. This part is true though. v6 is backwards compatible in rather a lot of ways, but v4 isn't forwards compatible, and it's important to note that this comes entirely from the larger address size -- no amount of making v6 more identical to v4 than it already is would make v4 any more compatible with it, unless you undermined the entire point and made the addresses 32 bits.
- ninkendo 2y ago
  Now try that on an ipv4-only host trying to talk to an IPv6-only address. You can’t, hence, 2 internets. (Yes, I understand there is no other way for a larger address space to exist that doesn’t have this problem. We are in violent agreement here. But that doesn’t mean there aren’t 2 internets. Let’s call a spade a spade.)
  - Dagger2 2y ago
    I can do it with a moral equivalent of a port forward. This situation was inevitable, but it's not like they just gave up and said "welp, guess they're separate then". We've developed basically every single method of communicating between v4 and v6 that are possible to develop. There's two address spaces, but they're linked into one Internet. (Or really, with NAT in the picture, it's millions of overlapping address spaces, but we still consider that to be one Internet.)

Dagger2 2y ago

Well, that's just not true: $ ip -4 addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever $ ping -6 ipv4.google.com PING ipv4.google.com(sof04s06-in-f14.1e100.net (64:ff9b::142.251.140.78)) 56 data bytes 64 bytes from 64:ff9b::8efb:8c4e: icmp_seq=1 ttl=55 time=27.9 ms This is a v6-only machine (no v4 address other than lo), talking to a v4-only hostname. If it was truly not possible to communicate, this wouldn't work. > If everything in the IPv6 protocol suite was literally identical to IPv4, but just with some extra bytes in every address, because they are not mutually compatible. This part is true though. v6 is backwards compatible in rather a lot of ways, but v4 isn't forwards compatible, and it's important to note that this comes entirely from the larger address size -- no amount of making v6 more identical to v4 than it already is would make v4 any more compatible with it, unless you undermined the entire point and made the addresses 32 bits.

ninkendo 2y ago
Now try that on an ipv4-only host trying to talk to an IPv6-only address. You can’t, hence, 2 internets. (Yes, I understand there is no other way for a larger address space to exist that doesn’t have this problem. We are in violent agreement here. But that doesn’t mean there aren’t 2 internets. Let’s call a spade a spade.)
- Dagger2 2y ago
  I can do it with a moral equivalent of a port forward. This situation was inevitable, but it's not like they just gave up and said "welp, guess they're separate then". We've developed basically every single method of communicating between v4 and v6 that are possible to develop. There's two address spaces, but they're linked into one Internet. (Or really, with NAT in the picture, it's millions of overlapping address spaces, but we still consider that to be one Internet.)