We've all heard it: Cloud computing is "the next big thing." And while that’s probably true, it’s not at all clear how we’re going to get there. The actual build-out of cloud computing is as difficult, tough, and problematic as its namesake is light and fluffy.

So what’s the problem? Cost, for one. And scalability. Plus security. And don’t forget performance. IT managers from around the world cite these four concerns (and more besides) as the worries that keep them up at night.

Read how the merging benefits of networking and computing resources are being used by service providers to build the "Carrier Cloud".