IPv6 (tutorial)
From DD-WRT Wiki
Introduction
There are too many devices in the world for 232≈4.3 x 109 IP addresses to be enough. The next version of the TCP/IP protocol, IPv6 offers 128bit address space, or 2128 ≈ 3.4 x 1038 IP addresses.
IPv6 is currently supported on DD-WRTv22 prefinal5, and will be in the final version of DD-WRTv22 when released.
The sconk.se guide offers some pretty nice instructions on how enable this feature starting out with obtaining an IPv6 address.
External Links
http://sconk.se/dd-wrt_ipv6_guide/
http://en.wikipedia.org/wiki/Ipv6
10 easy steps to IPv6