On 9 feb 2011, at 20:21, Scott Helms wrote: > IPv6 for some ISPs will be extraordinarily painful because of legacy layer 2 > gear (usually DSLAMs that drop any frame with IPv6 in the EtherType field), > inability to upgrade customer gear efficiently
[...] > For ISPs in this circumstance the choice will be CGNAT rather than IPv6 for a > number of years because the cost is much lower and according to the vendors > selling CGNAT solutions the impact to end users is (almost) unnoticeable. The good thing is that as an ISP, you don't have to give everyone the same thing. For the content people, it's either an AAAA record in the DNS or no AAAA record in the DNS. But as an ISP, you can keep your existing customers on existing IPv4 using existing hardware, while you roll out CGNAT + IPv6 for new customers using new gear. (Yes, that's still going to be annoying, but annoying in the sort of "I wish I didn't have to but I guess I do" kind of way rather than the "this will bankrupt the company" kind of way.) As long as your "legacy" users have an IPv4 address they can always use tunneling to get IPv6 (you may want to set up a tunnel termination box for this) if they need IPv6. But they won't really _need_ IPv6 (at least not very soon) because they can set up port mappings etc and everything they need can work over IPv4. For the new users, there are no port mappings behind the CGNAT so they do need IPv6 for hosting services and for VoIP and peer-to-peer file sharing. They also can't get a protocol 41 tunnel so you, their ISP, has to provide them with IPv6. But just CGNAT with no IPv6 is going to be very bad. Maybe 95% of your users won't notice, but do you really want the other 5% to tie up your support lines?
