Comcast Announces Participation in World IPv6 Launch Event

We are pleased to announce our participation in a second Internet Society - organized global IPv6 event, World IPv6 Launch. We have released the following statement from one of our executives: "IPv6 deployment is a key priority for Comcast in 2012, and we're excited to participate in this ISOC event that will help catalyze action around the world on this important transition."

IPv6 Pilot Market Deployment Begins

Comcast has started our first pilot market deployment of IPv6 in a limited part of California. This first phase supports directly connected CPE, where a single computer is directly connected to a cable device. A subsequent phase will support home gateway devices. To learn more, check out FAQs on the pilot market deployment and the announcement and technical details on our blog.

IPv6-Based DNS Servers Available

We now have IPv6-based DNS servers available for customers to use as their recursive DNS servers. These are Anycast-based and so you need only use two IP addresses, no matter where in our network you are located. These are now available for use on a beta testing basis at the IP addresses 2001:558:FEED::1 and 2001:558:FEED::2

World IPv6 Day Begins This Evening

World IPv6 Day begins this evening in the U.S. Comcast will be continuously monitoring our network and customer contact volume closely during this event, from an IPv6 command center in Philadelphia. We anticipate that the overwhelming majority of our customers should not experience any difficulty accessing participating web sites. Nevertheless, if a customer does have difficulty, they can run a simple test to see if World IPv6 Day is the cause, by visiting If a problem is discovered, instructions are be provided on that page. In addition, for Windows users that experience a problem, Microsoft has released a special fix. If customers need additional help, they should visit our customer forums.

DOCSIS-Based Native Dual Stack Trial Expands

We have recently expanded our DOCSIS-based IPv6 Native Dual Stack trials to select locations in the following metropolitan areas: San Francisco, CA, Philadelphia, PA, Miramar, FL, and Chicago, IL. This round of expansion includes the addition of home network equipment from D-Link. The successful expansion of our trials is a clear indicator of Comcast’s and the cable industry’s readiness for IPv6. One important benefit of this event is to continue to exercise and prepare the infrastructure that we will use to deliver IPv6 to our subscribers.

Comcast Testing Our IPv6-Enabled SMTP Email Server

Our IPv6 trials now include not just IPv6-enabled networks and websites, but also SMTP mail servers. We have just started testing outbound mail servers with IPv6 from our current vendor, Cloudmark, and hope to learn more about how to prepare our email platform for IPv6. Participation is limited to our technical trial participants for now.

Test Your Readiness for World IPv6 Day

World IPv6 Day begins the evening of June 7th in the U.S., to test the readiness of the Internet to move to IPv6. Popular sites like Google, Facebook, and Yahoo will be testing that day. When they do so, the overwhelming majority of our customers should not experience any difficulty accessing those and other participating sites. Nevertheless, a small fraction of our customers may experience problems due to issues with your computer or home network (estimated at roughly 0.05% of users worldwide). So please take a moment to run a simple test to see if your computer and home network is ready.

All you need to do in order to test your readiness is visit our special test website at and in less than a minute the results will tell you if there are any items that you need to fix. Be sure you run this from each computer in your home, especially older computers. If you need help fixing any issues, please visit our customer forums.

6RD Deactivation Planned

On June 30, 2010, we activated 6RD border relays in our network as part of our testing of “Phase 1” of the expected transition to IPv6 (see figure below). On the one year anniversary of this activation, June 30, 2011, these 6RD border relays will be turned off, as they are no longer needed given the advanced state of our IPv6 testing and our Native Dual Stack strategy. Trial users testing 6RD can find directions on what to do next on our trial web forum. This date will of course enable our 6RD trial users to participate in World IPv6 Day on June 8, 2011. The other transition mechanism we are testing is 6to4, for which we will assess future support at a later time.