Unlike some others, I'm still not convinced that there is anything
fundamentally wrong with the IPv6 design
although I believe that we could have made it either easier to deploy or
that we could have offered more incentives for deployment.
IPv6 is, fundamentally, IPv4 with bigger addresses. I am hearing two kinds of
critics. On one hand, some regret the lost opportunity to break from the IPv4
design and do something more radical, e.g. ID/locator separation. On the other
hand there are those who wish that IPv6 was even more like IPv4, including the
use of NAT and other such practices, so network administrators could keep a
familiar setting. Of course, the two critics are contradictory, as a radical
change in design would indeed require administrators to learn radically new
methods.
Thinking back, I do not regret the opportunity lost. The Internet grew
tremendously between 1992 and 2012, and that very growth proves that the IPv4
design was pretty good. We could do much worse than keeping that design for
IPv6. I have much more sympathy for the other side of the critic, that IPv6 is
in some ways too different from IPv4. We may want to take a deep look there!
-- Christian Huitema