--On Tuesday, November 12, 2013 13:12 -0500 Michael Richardson <mcr+ietf@xxxxxxxxxxxx> wrote: >... > I'll bet if we had a single IPv4 over IPv6 solution which had > a clear operating cost savings over Dual-Stack, and also over > IPv4-only+CGN, that we'd be at universal deployment of IPv6 > already. Since we are engaged in a counterfactual guessing / betting game, I'd bet that would be true had we defined such a solution a decade ago, that it were realistic, and that we had stuck to it. At this stage, the cartoon is relevant -- not only would we be likely to add another method to the list when existing ones already have their advocates, but dropping two or three would not be enough to make a significant difference. john