> OS2 single mode duplex throughout the house, all converging to a trunk which is available in three locations for equipment.
What do you mean by "trunk which is available in three locations"?
Usually cabling is home-run to a single, central patch panel. A cable (fibre, copper) would usually have one end in a room's wall outlet, with the other end at a patch panel: how would you have a cable one end at three locations? Do you have three patch panels? I.e., three hubs, with the room cables going to one hub and then you can have hub-to-hub runs?