A method for creating a full duplex fiber optic network using one single fiber optic cable of the multimode fiber type for simultaneous transmission and reception is described. The method includes the steps of equipping end user devices and switches with bidirectional transceivers utilizing multi-frequency lasers, allocation of wavelengths to the end user devices to assure interoperability of redundant systems, and connecting the elements with multimode fiber optic cable. The network components include multi-frequency bidirectional transceivers, switches, and multimode fiber optic cable. This full duplex fiber optic network can be created as a single-backbone network or multiple-backbone network operating in series or in parallel to provide backup redundancy. Various embodiments are disclosed to show the versatility and scalability of the network.