There was always more pressing work to do than migrate, and CDNs have changed the rules

The chief scientist of the Asia Pacific Network Information Center has a theory about why the world hasn't moved to IPv6.

In a lengthy post to the center's blog, Geoff Huston recounts that the main reason for the development of IPv6 was a fear the world would run out of IP addresses, hampering the growth of the internet.

But IPv6 represented evolution – not revolution.

"The bottom line was that IPv6 did not offer any new functionality that was not already present in IPv4. It did not introduce any significant changes to the operation of IP. It was just IP, with larger addresses," Huston wrote.

IPv6's designers assumed that the protocol would take off because demand for IPv4 was soaring.

But in the years after IPv6 debuted, Huston observes, "There was no need to give the transition much thought." Internetworking wonks assumed applications, hosts, and networks would become ...