(FORTUNE Magazine) - Imagine for a moment that you're O'Brien.

You're a vice president, running a division; life looks good from your lofty perch in the hierarchy. But then the company surveys everyone about communication, collaboration, and backup options, and plugs the data into a network mapping program. The results are startling: The software spits out a diagram that exiles you, O'brien, to the outer corner of a very tangled web.

At the center, meanwhile, is an underling: Cole. A technical specialist with no management responsibilities, Cole is still one of only two people with direct access to the boss - Jones - and has links to seemingly everyone else.

Official job title be damned, the network analysis shows that Cole is an influential hub of information. Managers need to identify office Coles to prevent networks from collapsing when that key person leaves. Companies facing looming boomer retirements, take note.