The following was originally published June 8, 2011 at http://en.blog.wordpress.com/2011/06/08/world-ipv6-day/
To show our support for IPv6, and as part of our IPv6 migration plan, we have enabled dual stack connectivity on our blog on this occasion of World IPv6 Day. If you view this site over IPv6, you will see a visual indicator confirming access from IPv6:
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What’s IPv6?

For those of you who don’t know, IPv6 is the next-generation Internet protocol, which offers a large number of IP addresses, 296 (= 79228162514264337593543950336) times of what IPv4 has to offer. A typical IPv6 address looks like 2001:db8:cafe::1, compared to an IPv4 address 192.168.148.1. IPv4 space is quickly becoming exhausted, necessitating the migration to IPv6. You can read more about IPv6 in its Wikipedia entry or in the free book, The Second Internet. You can use IPv6 tunnels if your ISP does not offer IPv6 connectivity yet. Using http://test-ipv6.com/, you can verify IPv6 connectivity.
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Behind the Scenes

This is powered by 2 load-balancers running nginx, and connectivity to IPv6 internet is through IPv6 6in4 tunnels provided by Hurricane Electric Tunnelbroker, as our datacenters have not enabled IPv6 yet.

Plans

This is not the end. Once we have native IPv6 connectivity, we are planning to roll out IPv6 connectivity for all sites on WordPress.com, and maybe all Automattic sites as well. Stay tuned for more IPv6 announcements…

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