This is correct. More specifically, Comcast will be using 6-to-4. If you're wondering if your router is compatible, Wikipedia does maintain a reasonably up-to

This is correct. More specifically, Comcast will be using 6-to-4. If you're wondering if your router is compatible, Wikipedia does maintain a reasonably up-to-date list of known compatible routers: http://en.wikipedia.org/wiki/Comparison_of_IPv6_support_in_routers http://en.wikipedia.org/wiki/Comparison_of_IPv6_support_in_r... The weak link of Comcast for a while was their lack of not providing IPv4 forwarders on IPv6 DNS servers. Many public DNS servers (including Google DNS) are also in the same boat. On a somewhat unrelated hardware note, Comcast actually supports IPv6 on the Motorola Surfboard 6121, contrary to what their compatibility list suggests. The 6121 is simply a revision of the 6120, and typically they provision 6121s as a 6120 with 6120 firmware.