Edge-wavelength-switching system, associated optical network, and failover recovery method thereof

A failover recovery method for an optical network including a central edge wavelength switching system (EWSS) having an optical switch, a wavelength-selective switch (WSS) connected to a plurality of local ports in operable communication with a plurality of optical transceivers, respectively, disposed throughout the optical network, the method comprising steps of:

• monitoring, by the EWSS, bit-error rates (BERs) received from one or more of the plurality of optical transceivers at respective local ports of the plurality of local ports;
• determining a BER severity from a temporal sequence of BERs generated from a first transceiver of the plurality of optical transceivers at a first premise host equipment optically coupled to a first port of the plurality of ports, wherein the EWSS is disposed at a network node of the optical network, and wherein the network node optically coupled to a hub of the optical network by way of a first optical-fiber path;
• and
• rerouting optical signals transmitted between the first premise host equipment and the hub, when the BER severity exceeds a predetermined value, by causing the optical switch to change between a parallel mode and a crossed mode, such that the optical signals travel along a second optical-fiber path differing from the first optical-fiber path.