If you think migrating to IPv6 is as simple as upgrading to Microsoft Windows Vista, think again.

Vista is the first operating system from Microsoft that automatically installs and enables IPv6, the long-anticipated next generation of IPv4, the Internet's main communications protocol. Even the biggest proponents of Vista, however, say enterprise customers will find rolling out the software's IPv6 capabilities is difficult and time-consuming.

That's why Microsoft executives are urging corporate network managers to start testing Vista's dual-TCP/IP-stack IPv6 implementation, which supports both IPv4 and IPv6 traffic, at least a year before putting it on a production network.

"This is a large upgrade. We're really looking at a lot of different moving parts. It's not just a matter of flipping a switch and everything works," says Sean Siler, IPv6 program manager for Microsoft. "Not everything supports IPv6 throughout the entire network infrastructure. You have to make sure you have the right management tools and the right security tools. It's a good thing to do a network inventory."