From my FaceBook post:
It took a bit of noodling to figure out exactly HOW Comcast envisioned the deployment of IPv6, but I finally got all the pieces to fit together and figured out how to deploy IPv6 from my cable modem through my firewall into my LAN. If the support folks at Comcast actually took a few minutes to put together a real document describing what their vision is, this would have been a whole lot faster and easier.
In essence, the Cable modem has to be set to enable DHCPv6 and prefix delegation. If you have a firewall, it must be set on the WAN side to ask for a DHCPv6 assignment and be prepared to accept the prefix delegation. My Cable modem delegated XXXX:YYYY:ZZZZ:28f0::/64 as my prefix. Once I knew that I was able to address all my LAN devices and have them pass IPv6.
CAVEAT!!! I have a business class account and I pay for static IP addresses (originally IPv4, and received a static IPv6 delegation). If you have a residential account, things may work somewhat differently. If you do not need the intervening firewall (like I do), you may want to consider allowing the Comcast Cable Modem to handle IPv4 and IPv6 addressing as DHCP for both protocols.
So, after some requests, I uploaded a PDF version of my document to this blog post, the URL is below.
Hope everyone finds it useful.
Comcast IPv6 with Netgear FVS318Gv2