Why would CGNAT be deployed as a response to IPv6 on mobile? I don't understand ...

AtlasBarfed · 2026-01-03T03:48:46 1767412126

Because the internet as a whole is ipv4. The mobiles are IPv6. The ipv4 internet does not care about any server running on any mobile device.

Thus, CG Nat was invented so that IPv6 could talk to IPv4 and get the information from it.

aragilar · 2026-01-03T04:22:14 1767414134

No, CGNAT (Carrier-Grade NAT - https://en.wikipedia.org/wiki/Carrier-grade_NAT) is an IPv4 only thing. https://www.rfc-editor.org/rfc/rfc6598 specifies they should use 100.64.0.0/10 for it, to avoid conflicting with the pre-existing private-use ranges. IPv6 removes the need for using CGNAT, as each home router is allocated a public IP (rather than a CGNAT IP) on its public link.

AtlasBarfed · 2026-01-07T02:10:56 1767751856

Oh so cgnat exists for ipv4 addresses to talk to IPv6 servers? Is that what you are telling me?

Because all of the www is in IPv6, and cgnat actually excuses for ipv4 cable users to use the bedrock internet servers and services?

Bullshit. Cgnat is a hack for ipv6 to talk to the ipv4 universe.

Because if there were magically enough iov4 addresses for mobiles, would cgnat exist? No, it wouldn't.

aragilar · 2026-01-07T10:12:41 1767780761

No, CGNAT has absolutely nothing to do with IPv6. CGNAT is nothing more than ISPs not providing a public IP to the gateway on your LAN (i.e. your router). To avoid conflicts with existing ranges, a new ranges for that purpose was allocated. There are different technologies to enable IPv4<->IPv6, none of which care about the existence of CGNAT.

nulbyte · 2026-01-03T12:16:55 1767442615

No, NAT64 was invented so v6-only hosts could access v4-only resources. CGNAT was invented so v4 hosts can have a v4 address without having to purchase limited public address space.