Apple came under fire for back-pedaling on its support for IPv6, the next-generation Internet Protocol at this week’s North American IPv6 Summit, a gathering of experts held in Denver, reports “Network World” (http://macte.ch/sQdC9).

Presenters were annoyed that the latest version of Apple’s AirPort Utility, version 6.0, is no longer compatible with IPv6. The previous version, 5.6, offered IPv6 service by default.

Comcast is urging its subscribers that are interested in using IPv6 not to upgrade to AirPort Utility Version 6.0 if they use Mac OS X 10.7 (“Lion”) operating system because of incompatibilities with IPv6.

“Apple has taken the ability to seamlessly support IPv6 away from the AirPort Utility,” John Brzozowski, chief architect for IPv6 and distinguished engineer with Comcast, told “Network World.” “It’s a little concerning. We hoped to see more IPv6 support, not less, among [customer premises equipment] vendors.”

IPv6 is needed because IPv4 is running out of addresses to connect new users and new devices to the Internet. IPv6 solves this problem with a vastly expanded address space, but it’s not backwards-compatible with IPv4. While home networking vendors like Cisco and D-Link are adding IPv6 across their product lines, Apple appears to be the only vendor that is removing this feature, says “Network World.”