The basics of the story -- the inadequate long-term supply of IPv4 addresses and the need to upgrade just about every link of the distribution chain in order to support IPv6 -- seem to have been with us for some time.
The year coming to a close marked two milestones that suggest that the true beginning of the end of the transition finally is upon us: The last batch of fresh IPv4 addresses was allocated in February, and World IPv6 day -- a day to drive home the importance of the transition and get content providers and network owners to turn up IPv6 services that could only be undertaken when many content providers and network operators are up to snuff -- was held on June 8.
The cable industry clearly has a lot riding on its state of readiness, since it is perhaps the preeminent transporter of Internet content. Experts now say that the real end of IPv4 availability in North America -- when even those addresses held by the American Registry for Internet Numbers (ARIN) beyond the allocations given to it by the Internet Assigned Number Authority (IANA) are exhausted -- is expected anywhere from the middle to the end of next year.
The cable industry is getting what best can be described as good to excellent grades from observers on its preparation, with Comcast getting special credit. "Comcast is hands down the leader in IPv6 adoption," wrote Dr. Ciprian Popoviciu, president/CEO of Nephos6 in response to emailed questions. "They started early, so they had the time to make the right architectural choices and to drive their vendors to make products ready for what they needed (both in the core of the network and at the cable-specific edge: cable modems, CMTS, etc."
Nephos6, which helps organizations deal with the IPv6 transition, has worked with Comcast and other cable operators. Popoviciu credits Rogers as also being proactive.
Operators face some tricky choices in their preparations for IPv6. Comcast -- which began production rollouts of IPv6 services last month in the San Francisco Bay area -- opts for an approach known as "native dual stack," in which the two addresses sit in parallel and serve end user devices that demand either format. John Brzozowski, Comcast's distinguished engineer and chief architect for IPv6, said rollouts of similar services were launched in the Chicago and Miami metropolitan areas shortly after the San Francisco Bay rollout and that nationwide deployment is slated for early next year.
The challenge for cable operators and other service providers is that IPv4 must be supported in addition to IPv6. Native dual stack is one of three approaches to meeting this challenge, according to Chris Donley, CableLabs' project director for network protocols. The second, NAT 444, enables the sharing of IPv4 addresses through a technique similar to network address translation (NAT) techniques that have been used for a long time to stretch the IPv4 soup. The third option is Dual Stack Lite, which encapsulates the IPv4 address in an IPv6 wrapper and, in combination with carrier-grade NAT, allows subscriber devices to use either IPv4 and Ipv6 addresses.
The industry seems to be forming a line behind Comcast. "Native dual stack is the leading approach, where operators continue to support v4 with an additional v6 address," wrote Steve Harris, the director of advanced network technologies for the SCTE, in response to emailed questions. "Native dual stack offers performance benefits over network address translation and tunneling."
The cycle of launches Comcast is undertaking now only is the primary stage of the full rollout of IPv6, Brzozowski said. The current phase focuses on a relatively simple connection between a cable modem and a PC. The next step is a more sophisticated phase in which a subnet is appended to the basic Internet connection in a way that more elegantly supports homes with multiple and mixed IPv4 and IPv6 devices.
It's clear that the tier 1 operators, those with the expertise and the money to throw at the problem, are addressing the issue. This is not new to the cable industry: The Comcasts and Time Warner Cables of the world often are out ahead, while the other operators lay back. The potential problem is that IPv6 rollout is a long-term project that takes much preplanning.
However, it is not certain that that challenge will come to pass. Todd Kessler, the vice president of product management for ARRIS, suggested that the smaller operators are still on solid ground. "They are waiting, letting some of the other activities progress," he said. "They are interested in talking about what options they have. They are not burying their heads in the sand. Smaller operators have a bit easier time because their networks are somewhat smaller. They can make changes faster when they need to."
Carl Weinschenk is the Senior Editor for Broadband Technology Report. Reach him at email@example.com.