Patent ID: 6839514

Claim:
An optical switching node for use at nodes in an optical network, the network including terminal equipment connected by network links, the optical switching node comprising: first and second sets of working and protection network ports for coupling to respective first and second network links, each of said first and second network links including a first fiber and a second fiber, said first and second fibers being capable of carrying signals in a first and a second direction respectively; first and second sets of working and protection terminal equipment ports for coupling to first and second portions of terminal equipment, each set of terminal equipment for sending and receiving data to and from said first and second network links; a set of switch elements connected to said sets of network and terminal equipment ports for establishing span and ring switching in the event of a failure in the network; and control logic configured to perform functions including: (a) monitoring respective said first and second fibers of said first and second network links; (b) controlling the set of switch elements to establish span and ring switching in the event one or more of said first and second fibers fails; (c) generating supervisory messages for output onto said first and second fibers; (d) processing incoming supervisory messages received from said first and second fibers; and (e) controlling the set of switch elements based on the supervisory messages received and the supervisory messages expected but not received.