Level Up to IPv6 with Ubuntu 10.10 on Comcast (Linux.com)

I'd bet what you really *like* is that it's behind a central firewall. That your firewall also does NAT is a bit unfortunate, as it just makes it more difficult to poke any desired holes in it. There's no security benefit in NAT.

This element of the transition is sometimes called "regime change" because it involves a change in the RIR allocation regime. You are correct, in a limited sense, that you will be able to arrange to transfer addresses. RIRs will (for a fee) arrange to update the allocation records once exhaustion occurs. Obviously you would have to negotiate (perhaps in an open market, perhaps behind closed doors) for the other party to be willing to transfer their existing allocation.

However that will only be for large aggregatable blocks (maybe a /24 but quite likely larger) because otherwise they aren't routeable. Unlike IPv6, which has already been deployed on a wide scale in production, this "market of IP addresses" is untested. If your business depends on it then you are in a rather uncomfortable position, such a market may never actually emerge in production scale, or the price may be far higher than you anticipated (consider, the legal overhead alone of agreeing such a deal could make a /24 cost many thousands of dollars, while your competitors have obtained all their addresses for free)

It doesn't say anything sad about IPv6. Businessmen would like things to continue as they are, long after that ceases to make sense. That's a commercial reality whether you're installing asbestos home insulation, delivering goods by horse and cart or selling worthless securities. No conceivable protocol to fix the address exhaustion problem (nor "tweak" to the existing IPv4) could have done better than IPv6 has in this environment.

Everybody who actually cares already migrated to dual-stack. Whole businesses, entire systems. But they represent a tiny, informed, minority. Some people's experience will be that their ISP mysteriously goes out of business after introducing new "better" service (the carrier grade NAT you're so enthusiastic about) and losing all its well informed customers to an ISP still actually providing Internet service. Most countries now have at least one home ISP that already provides native IPv6 (a step up from what Comcast are currently doing) and those companies know they're well placed to eat the other guys' breakfast.

NAT has held back service development in the network for at least a decade. That's why VoIP isn't more common than it is and why we're stuck with things like Skype which won't develop further. That's why real time gaming is limited to geeks who forward their TCP ports.

Carriers need v6 too, to keep the service innovation alive in the network, not limited to stateless HTTP. They just hope the cost of transitioning will go down if they wait. Carrier grade NAT is not really an option in the bigger picture.

Things get complicated because some people confuse their NAT and their stateful firewalling. It is the latter you really want to make sure you can only reach your network via VPN. (Please remember that IPsec for IPv4 is really a backport of what originated as IPv6 technology.) In fact, security will improve when you get rid of NAT since you don't have to use port forwarding (which especially with UPnP is not a good idea security wise).

I wonder if the time is right for someone to demonstrate an extended IPv4 stack that skips some of the transitional issues of IPv6 and modestly fails to fancy itself so innately pure and beautiful as to compel all ordinary internet denizens to sail away with it, leaving the bulk of the .com domain stranded on the IPv4 island?