For a feel for some of reasons your question sounds naïve, see Geoff Huston's presentation on IPv6 and CGNs at APNIC 32 all the way back in 2011 (trust me, it's entertaining, as Geoff usually is):
Slides: <http://labs.apnic.net/presentations/store/2011-08-30-exhaustion.pdf>
Recording: <http://webcast.apnic.net/meetings/32/opening-hinted.mov>Slides: <http://labs.apnic.net/presentations/store/2011-08-30-exhaustion.pdf>
On Fri, Nov 22, 2013 at 11:59 AM, Ted Lemon <ted.lemon@xxxxxxxxxxx> wrote:
On Nov 22, 2013, at 11:46 AM, Noel Chiappa <jnc@xxxxxxxxxxxxxxxxxxx> wrote:That's almost certainly true now. I'm not talking about now. Really, the big problem with CGNs is that they don't scale—this is why lw4over6 and MAP represent a significant and useful innovation.
>> CGNs are expensive. Why would people prefer to maintain them if the
>> IPv6 infrastructure was working?
>
> Cheaper than customer service calls.
What I expect to see happen in the market is that in the next decade, CGN will start to seem old-fashioned, and more and more what will be deployed will be stateless port-sharing NAT hardware in the core, supported by stateful NATs at the CP, just like we were doing before the CGN idea got popular.
The nice thing about stateless NATs in the core is that they can be scaled up and down according to need. So as more traffic is carried over the native IPv6 network, you can start switching off boxes in the core. You can track the demand, so you don't switch off boxes that are needed. You can even goose the switchover by running your IPv4 NATs closer to capacity, forcing traffic that could go over either transport to go over v6, because it's working better, and Happy Eyeballs can tell.