Comcast Embraces IPv6

Comcast is making a move to IPv6, making IPv6 transit services available to its wholesale customers.

This a significant development because in less than two years, the IPv4 address space will be exhausted, but it doesn’t mean there won’t be any more Internet addresses. IPv4 has a 32-bit address size, allowing for only 4.3 billion addresses. In contrast, IPv6 is a 128-bit address space allowing for a staggering 340,282,366,920,938,463,463,374,607,431,768,211,456 possible addresses.

“IPv6 is beginning to become a requirement, although usage is relatively low today,” Barry Tishgart, VP of Internet Services for Comcast (NASDAQ: CMCSA, CMCSK) told “Some customers are making decisions on the basis of future traffic growth and that’s why IPv6 is increasingly important.”

There have been some questions raised about the business case for IPv6 in the Internet community. The U.S. Government has also begun to transition to IPv6 with an IPv6 ready mandate that was instituted in 2008.

For Comcast’s wholesale customers, which include Web hosting providers, the business case is one of choice and availability. The new IPv6 services from Comcast are being offered at the same price as Comcast’s existing IPv4 services. Tishgart explained that wholesale transit pricing is usage-based regardless of whether v4 or v6 protocols are used. He added that billing is based on the aggregate traffic.

While IPv6 represents the future of the Internet, Comcast will not be transitioning any part of its network entirely away from IPv4 anytime soon.

“For the foreseeable future Comcast will support IPv4 and IPv6,” Tishgart said. “Our backbone is dual stack in that it supports IPv4 and IPv6 traffic simultaneously.”

While IPv4 address space as a whole is nearly depleted, it doesn’t mean that Comcast doesn’t still have IPv4 addresses.

“Comcast has sufficient IPv4 addresses for its current needs,” Tishgart said. “We may issue requests for IPv4 address allocations as governed by current ARIN policies.”

ARIN (American Registry for Internet Numbers) is the body that distributes IPv4 and IPv6 address space in North America. They are currently actively promoting IPv6 in an effort to help the transition from IPv4.

Residential IPv6

With wholesale availability of IPv6 on the Comcast network, the next steps include making IPv6 available to Comcast’s business and residential broadband customers.

“Comcast plans to enter into broadband IPv6 technical trials later this year and into 2010,” Tishgart said. “Planning for general deployment is underway.”

There are some key challenges however that will need to be overcome before IPv6 becomes pervasive in the residential broadband space. One of those challenges is the availability of home networking gear that supports IPv6.

“Much of the equipment that broadband subscribers use at home today may not support IPv6,” Tishgart said. “The advancement of IPv6 in the broadband home networking space will be critical to the long term deployment of IPv6.”

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