> In short, any IPv6 transition plan involves everyone having an IPv4 address, right up until everyone has an IPv6 address, at which point we can start dropping

> In short, any IPv6 transition plan involves everyone having an IPv4 address, right up until everyone has an IPv6 address, at which point we can start dropping IPv4, which means IPv6 will start being useful. Sigh, no. Not correct -- in the last 8 or 9 years, engineers have been cooking up various ways to bridge the gap. The transition landscape looks a lot different today than it does in 2003. Comcast (the largest MSO in the US) has detailed their transition plans here (tl;dr, it's v6-only customer addressing, with v4 reachability via DS-lite and CGN): http://www.comcast6.net/ http://www.comcast6.net/ Summary here: http://en.wikipedia.org/wiki/IPv6_transition_mechanisms http://en.wikipedia.org/wiki/IPv6_transition_mechanisms