ipv6 compatibility, are there any pitfalls?

Question

i don't know if this question fits perfect on superuser but i'll ask anyways feel free to move.

are there any pitfalls with ipv6? we are planning to move our webservers to an ipv6 only machine, is there a possibility that users can't access their sites anymore?

for example if their provider doesn't support ipv6 yet or if their browser doesn't ?

should we consider to get an additional ipv4 address or is everyone fine when we just use ipv6?

Answer 1

Many machines are fine with IPv6 (the major operating systems have handled it natively just fine for a few years, it is normally enabled by default now), but very, very few use it. I'd be surprised to see a home ISP giving out IPv6 addresses; oldish WiFi routers don't handle it, network technicians/admins know their way inside out with IPv4 and know zilch of IPv6, ... I'd strongly advise against pure IPv6 right now. Google's IPv6 use statistics show around a 1% of the queries they get are IPv6...

Answer 2

There is DEFINATELY a problem.

Only about 1% (as an order of magnitude) of the traffic on the Internet is IPV6 - and many (most?) ISP's don't provide IPV6 addresses by default. Even if the ISP does provide an IPV6 address, go down to your local hardware store to see what percentage of gear supports it - you will see that it is comparatively little.

While IPV6 is a cool technology, the net is a LONG way away from being IPV6 capable.

If this is of real interest to you, you should seriously consider multihoming your website so that it can handle both IPV4 and IPV6 traffic (which is practical, and done with DNS). This is the way big providers (like Google) are going. [ To show how backward some places in the world are, here in New Zealand, I CAN'T GET IPV6 on my home connection from my provider - even if I ask - neither can I get it on 1 of my expensive pipes, with the other providers dragging their feet ].