1. ask your customers to sketch out the standard, and the gnarly, pieces of their network on a 4*6 index card and mail them to you.
2. look at the pictures and see how you could determine the dependencies.
3. offer thwack points for each card.
It would take me less than 10 minutes to write the cards, and you could see how Dependancy mapping might work..
In my world for example if all the interfaces on the routers connected to the root bridge in a broadcast domain are down, then everything in the broadcast domain should be unreachable
If the root bridge in a broadcast domain is down, then its likely that all of the other nodes in the broadcast domain are unreachable.
[Our routers do not participate in spanning tree, the root bridge is supposed to be the one the routers are plugged into]
If the switch the UPS is plugged into is down then the UPS is unreachable