Comcast has scheduled for early June the trials of various IPv6 technologies it first announced back in January. The announcements reveal the different status in terms of IPv6 preparedness of various cable industry vendors, including Cisco, Arris, Motorola, Juniper and Netgear.

IPv4 Internet address space is expected to be completely exhausted by the latter half of 2011, forcing a transition to IPv6. In addition to promising address space far beyond the capacity anyone can imagine ever needing (enough to give a permanent IP address to every atom on the face of the earth, by some calculations), IPv6 also has features that should help operators improve QoS and support mobility applications, among other benefits.

Everybody involved with Internet communications must begin to upgrade their networks to support IPv6. Among U.S. MSOs, Comcast is widely considered to be at the forefront of the transition; other MSOs are expected to follow Comcast’s lead when it comes to IPv6 technology.

Over the last two days, Comcast has released a slew of details about its trials on its IPv6 blog.

One trial aims to evaluate tunneling IPv6 over IPv4, using 6RD technology, which was designed to enable service providers to provide IPv6 service to customers who have only been issued IPv4 addresses.

Comcast said it will start with Linksys home gateways that will either be loaded with software from both Linksys and Xavient, an IT specialist. Traffic destined for IPv6 hosts will be sent through a 6RD relay, initially through Cisco 7200 routers loaded with 6RD relay software. Comcast may use other home gateway devices and other 6RD relays later.

Whether the company will be able to commence in June will be subject to the availability of the home gateways and the installation and operational readiness of the Cisco routers.

Comcast said it plans to begin with up to 50 customers to validate functionality of the technology, and then it will expand this to at least several hundred participants.

The second trial is to evaluate a native Dual-Stack IPv6 deployment, specifically as it applies to supporting DOCSIS customers.

Dual-Stack essentially means supporting both IPv4 and IPv6 in native format, in parallel. Of all the means of dealing with the transition, this is the one preferred by most standards organizations and industry groups, including CableLabs.

This trial depends on a cable modem termination system (CMTS) being upgraded to support IPv6. Arris has software ready for IPv6 testing on its C4. Comcast said Cisco is expected to have IPv6 CMTS software ready by the fall, and Motorola sometime in 2011. Since Arris is apt to be ready first, initial trial areas might include the San Francisco/Bay Area, Chicago and Philadelphia, Comcast said.

Customers in the trial will have to have an Arris DOCSIS 3.0 modem capable of supporting IPv6; if they have one that doesn’t, Comcast will ship them a new one that does. Otherwise, Comcast will supply trial participants with one of the following IPv6-supporting gateways: the Apple Airport Extreme, the Netgear WNR3500 or the Netgear WNR1000. Comcast said it may use other home gateways later.

The third trial Comcast announced was designed to evaluate tunneling IPv4 over IPv6, using "Dual-Stack Lite" technology (aka DS-Lite). Comcast described DS-Lite “as the mirror image of 6RD; 6RD enables IPv6 service to IPv4 customers, whereas DS-Lite enables IPv4 service to IPv6 customers.”

Comcast had published no details about this third trial as of press time.

The fourth trial was set to evaluate how to deploy IPv6 to Comcast’s Business Class customers using native Dual-Stack IPv6.

Of this trial, Comcast said little. It has selected its first group of business-class trial participants, and the participants will all be fiber-based Ethernet customers. The equipment involved will include both the Cisco 7600 and some of Juniper’s MX series routers.

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