Comcast Flips IPv6 Switch

Comcast has officially put the next-generation IPv6 protocol into service, with an initial “pilot market deployment” of 100 customers in San Francisco’ East Bay area.

That lets Comcast boast that it’s the first large ISP in North America to start deploying IPv6, according to Jason Livingood, vice president of Internet systems in Comcast’s Network and Operations group.

“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,” Livingood wrote in a blog post Wednesday, noting that the MSO has been preparing for the IPv6 transition for more than six years.

Of course, all Internet service providers will need to start deploying IPv6 — very soon. The Internet’s pool of approximately 4.3 billion IPv4 addresses is virtually depleted. ARIN, the address registry for North America, is expected to run out of IPv4 blocks by the end of this year or early in 2012, and after that ISPs will need to start recycling old IPv4 addresses or move to the new address space.

Here’s the big issue: Without some kind of translation layer, websites or other Internet servers hosted on IPv6 are invisible to users with IPv4 end devices. Similarly, IPv6-only end devices can’t access existing IPv4 resources.

For now Comcast is rolling out IPv6 in a “native dual stack” approach, which means subscribers will get both IPv4 and IPv6 addresses. The MSO is not implementing large-scale network-address translation at this point, with Livingood noting that those approaches “are likely to result in some applications (such as some real-time applications) breaking or seeming slow.”

Comcast has “‘just said no to NAT’ in this phase of our IPv6 transition,” he wrote.

Just three DOCSIS 3.0 cable modems currently are certified by Comcast for IPv6: Arris’s Touchstone WBM760A, Motorola’s SURFboard SB6120 and D-Link’s DCM-301. The cable operator lists supported modems at, and the list of IPv6-certified models “will expand in the coming weeks and months as we complete testing of other devices,” according to John Brzozowski, Comcast’s distinguished engineer and chief architect for IPv6, who provided additional technical details.

Here are links to our past coverage of IPv6:

* Internet Runs Out of Addresses

* Comcast Kicks Off IPv6 Over DOCSIS Test

* What Happened on World IPv6 Day

* On World IPv6 Day ‘The Needle Moved’ On Adoption Of Next-Gen Protocol

* Comcast, Time Warner Cable To Join ‘World IPv6 Day’ Test

* SCTE Creates IPv6 Working Group


Programming Note! Don’t miss the Multichannel News breakfast panel discussion at SCTE Cable-Tec Expo 2011 in Atlanta, Video’s Next Act: Setting the Multiscreen Stage, on Tuesday, Nov. 15, prior to the opening general session. Click here for more info: