Comcast says it will meet its 2012 deadline of transitioning its network to support IPv6, the long anticipated upgrade to the Internet's main communications schedule. The ISP is halfway through a nine-month public trial of IPv6 that has attracted 7,000 of its business and residential customers nationwide.
Comcast also says it will soon begin the next phase of its trial, which involves running IPv6 and IPv4 side-by-side in what's called a dual-stack configuration for the cable industry telecommunication standards known as DOCSIS.
Overall, Comcast says it is on schedule with its IPv6 trial, which began in April and will continue through the end of the year.
"I wouldn't say IPv6 is easy, but it's not impossibly difficult either," says Jason Livingood, executive director of Internet systems engineering at Comcast. "IPv6 is something you have to start working on and plugging away at day by day to understand the technical issues, the bugs and the systems integration problems. If you uncover the problems early, you can fix them while you still have time."
Carriers such as Comcast are upgrading to IPv6 because the Internet is running out of IPv4 address space.
IPv4 uses 32-bit addresses and can support 4.3 billion devices connected directly to the Internet. IPv6, on the other hand, uses 128-bit addresses and supports a virtually unlimited number of devices -- 2 to the 128th power.
The regional Internet registries said in early September that less than 6% of IPv4 addresses remain unallocated. Experts say IPv4 addresses could run out as early as this December but will certainly be gone by the end of 2011.
The need for U.S. carriers and corporations to upgrade to IPv6 was highlighted yesterday by the White House, which issued a directive requiring all federal agencies to support IPv6 on their public facing Web sites by fall 2012.
"Networks are starting to move to IPv6. Now it's time for content owners and content producers to step up their efforts and start moving to IPv6. The government announcement was key and shows that they are sensing [this trend] as well. It was a welcome announcement," Livingood says.
Comcast is testing three IPv6 transition mechanisms in its ongoing trial:* Dual-stack, which involves supporting native IPv4 and IPv6 traffic running side-by-side.* 6rd, a technique developed by French ISP Free that allows for rapid deployment of IPv6 by tunneling IPv6 traffic over IPv4 addresses.* Dual-Stack Lite, an approach developed by Comcast that uses network address translation to share one IPv4 address among many customers.
What Comcast has learned so far from its IPv6 trial is that it's better to adopt native dual stack than to use translation mechanisms such as 6rd or Dual-Stack Lite.
"The best option for us and others is native dual stack," Livingood says. "Not going through a middle box means IPv6 should be faster, less costly and less difficult to troubleshoot."
One key issue for ISPs is upgrading the home gateways that residential customers use to access the Internet to support IPv6.Comcast officials said they will announce on Friday that they are providing software to the OpenWrt community, which develops Linux-based software for residential gateways from Linksys, Netgear and others. The Comcast-developed software will allow home gateway devices to support 6rd and Dual-Stack Lite.
"The software will help users that have only IPv4 addresses to tunnel over IPv6, and it will help those who only have IPv6 addresses and want to tunnel over IPv4," Livingood explains. "We will be posting the software on SourceForge …The community can benefit from it by directly using the software or studying how we've done it."
This represents the second time that Comcast has shared open source code with the Internet engineering community that was developed during its IPv6 trial. In March, Comcast and ISC released another IPv6 transition tool called Address Family Transition Router.
Next up for Comcast is starting its DOCSIS test.
"The DOCSIS trial hasn't kicked off as fast as we would have liked, but we're still fine and we can still manage in the timeframe we have left," Livingood says, adding that "we will have our network ready by 2012."
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