The migration date of 2013 was set after an extensive review balancing the drivers against the possible risks and extra costs incurred in transitioning too early.

"Many of the risks that Defence faces in transitioning will be managed by incorporating the lessons learnt by the US in its transition to IPv6, which should be completed by 2008," Richards said.

By transitioning incrementally over eight years, Richards hopes to minimize costs and exposure to potential risk.

"By 2013, we expect most of our hardware and software to be replaced as part of our normal refresh cycle, so we actually expect a great deal of our information environment will be IPv6-ready well before 2013, as it would not be cost-effective or feasible to continue running IPv4 in many areas," he said.

There will be some applications and hardware that have replacement cycles extending beyond 2013, but will be IPv6 enabled when they are replaced.