All,

I've written another blog post about World IPv6 Day:

<http://webmedia.company.ja.net/edlabblogs/developmenteye/2011/06/02/22000-users/>

You may well be tired of my ramblings, I wouldn't blame you, but we have had some interesting information from Google about the percentage of 'broken' hosts on JANET.  They estimate that as things stand we will be one of the top 10 'most affected' networks next Wednesday, and that means calls to your helpdesks.

Google claim that most of the brokenness comes from Macs running Mac OS 10.6.4 or earlier which did not deprefer 6to4 automatic tunnels (2002::/16).  The recommended solution is to upgrade if at all possible, or failing that to disable IPv6 on the Macs, or mask the problem by using a recent version of 'Chrome' as your browser which tries IPv4 and IPv6 in parallel and uses whichever works.  Mac OS 10.6.5 and later are fine as they do not prefer 6to4 addresses.

The ARIN wiki has some details of the suggested fixes:
<http://www.getipv6.info/index.php/Customer_problems_that_could_occur#Apple_Mac_OS_X>

We have a list of some of the 'top 20' DNS resolvers with the highest percentage of broken systems behind them, and we'll be contacting those sites shortly, but for the rest of you, watch out for old Macs!

Feel free to forward this as you feel appropriate.

All the best,
Rob