Dependency tree of switches

I'm afraid this is not possible.

May be you proposal some middleware that can do it?

@Gennady: I don't know of a really good one. I haven't seen/tried one that was able to map out our own office and lab net correctly. We believe that no software can create a map of a network that even remotely matches the picture what the admins "have in their head". That's one of the main reasons that we have not implemented such a feature in PRTG yet.