I’ve had some helpful feedback on the post Who Is Using IPv6?. One of the Google IPv6 researchers, Erik Kline, pointed out “from 2008 onward, the single largest deployment of IPv6 in the world was Free Telecom in France. I think part of the dip may also align with the yearly July/August French migration to vacation destinations.”
Yes, I did wonder whether the IPv6 usage dip was due to workers or students going on holidays, but inclined more to students as the dips begin in June, when they usually start three months of vacation. A fall in usage because of the five weeks French workers receive would be shorter (but if leave periods were staggered over June to September, the dip would certainly appear longer over time).
Looking more closely at the graph (green line, native IPv6), it’s clear that in 2011 the dip began in mid-June and ended in mid-August, then IPv6 usage climbed rapidly over the last two weeks of August. Students catching up with late assignments? Workers emailing their holiday snaps? This year’s graph, as it unfolds, should be interesting.