[Dagger2]

Hm... according to that draft, TUBA's transition story is dual stack, which is the same as the main transition approach for v6. How come it's sane for TUBA but not sane when v6 does it?

> As for current v6 being interoperable with v4, that is patently false.

This machine is v6-only and can reach the entire Internet, including v4-only hosts. It clearly has more interoperability than you're claiming or this wouldn't be possible.

[commandersaki]

Interoperability would be the ability to use either IPv4 or IPv6 and talk to each other seamlessly. This is clearly not the case for IPv4 clients talking to IPv6 servers. This is clearly not the case for IPv6 servers accepting IPv4 connections.

As for TUBA, the transition plan incorporated tunneling, with a bit more thought put into this we could've had something similar to AutoIPv6. That document was just a starting point and outlined some important aspects of the criteria such as low administrative overhead for transitioning IPv4 networks to IPng, something which IPv6 falls completely flat on.

[Dagger2]

I've talked from v4 clients to v6 servers before, and I've accepted v4 connections to v6 servers. How can it be so clear that it's not possible when I've done it before?

> As for TUBA, the transition plan incorporated tunneling

The transition plan for v6 also incorporates tunneling (6in4 is the same thing as the EON tunneling described in the draft you linked), so again I ask why TUBA counts as having a sane transition plan when doing the same things in v6 doesn't.

There's not much administrative overhead involving in transitioning a network to v6. For most people it involves doing exactly no extra work beyond what they already do to deploy v4. Of course, you do need to reconfigure anything that's been configured such that it can only work with v4 (and this might be quite a lot of stuff), but that was always going to be necessary no matter what you're transitioning to.