Broersma said that two federal network security efforts -- the Trusted Internet Connect (TIC) Initiative and (MTIPS) -- also are behind on deploying IPv6.

Broersma said other challenges for federal agencies trying to deploy IPv6 are the lack of feature parity between IPv4- and IPv6-based network hardware and software, as well as the lack of support for Dynamic Host Configuration Protocol for IPv6 (DHCPv6).

"Existing security products lack IPv6 support. Mainstream intrusion detection systems are not ready," he added. "But we have a much better story for doing over IPv6 than two years ago."

MORE:

One federal agency that's successfully deployed IPv6 is the Department of Veterans Affairs, which has IPv6 deployed on 99% of its websites. Steve Pirzchalski, IPv6 transition manager for the VA, said the agency has IPv6 support for its DNS, SMTP/mail and Web services for all of the websites under its va.gov domain.