http://blog.comcast.com/2011/11/ipv6-deployment.html Deployment of IPv6 Begins Posted by Jason Livingood, Vice President, Internet Systems, in Network and Operations Comcast has been conducting IPv6 technical trials in our production network for more than a year, and we've been working diligently on IPv6 deployment for over 6 years. After so many years of challenging preparatory work, significant technology investment, internal skills development, and close collaboration with our technology partners, I am incredibly pleased to announce that we've achieved another critical milestone in our transition to IPv6 â€” we have started the pilot market deployment of IPv6 to customers in selected markets! We're now the first large ISP in North America to start deploying IPv6. This is a significant milestone not just inside our own company but also in the industry, particularly given the chicken and egg relationship between the availability of content and software that supports IPv6 and the deployment of IPv6 to end users. In no small part this is due to our belief and firm commitment that there is value in long-term, strategic investment in technologies such as IPv6, and that this has benefits beyond our company and customers, across the Internet ecosystem. It is also due to those of our technology partners that have been willing to "learn by doing" in our various labs and our technical trials, and have been willing to break a few things and take prudent risks with us in a quest to move quickly to execute on our technical vision. Lastly, over the past 6 years of testing, development, and deployment, thousands of employees from around Comcast Cable have directly played a part in getting us to where we are today, whether that was developing technical training, conducting quality testing, deploying new gear on our fiber backbone, upgrading our access network, upgrading our back office systems, and countless other tasks both big and small. This first phase will support certain types of directly connected CPE, where a single computer is connected directly to a cable modem. Subsequent phases in 2011 and 2012 will support home gateway devices and variable length prefixes. Critically, our approach is "native dual stack" which means customers will get both IPv4 and IPv6 addresses. Some other ISPs that are less prepared may be using tunneling or large scale NAT in the network. Those approaches are likely to result in some applications (such as some real-time applications) breaking or seeming slow. Native dual stack, the approach we are using, avoids breaking or slowing applications and maintains a better and faster broadband Internet experience. Our customers buy Xfinity Internet service in large part for our great speeds, and they can rest assured that they won't have to slow down as the world transitions to IPv6, as we've "just said no to NAT" in this phase of our IPv6 transition. Finally, it is worth noting that this is the start of pilot market deployments as opposed to full national deployment. As such, it is possible that this will not be without technical bugs in the near term. Our focus is in identifying any final IPv6 transition issues quickly and fixing them rapidly, so we can soon begin a national deployment. For all the key technical details, check out this complementary blog post from John Brzozowski.