Patent ID: 6331906
Filing Date: 2001-12-18
Classification: H04J,H04Q

Abstract:
In an optical ring network having nodes coupled by bidirectional optical links wherein at least one bidirectional optical link between a given pair of nodes includes first and second fibers that carry upstream and downstream network traffic between the given pair of nodes, apparatus comprising, at each of the given pair of nodes:control electronics operating to (a) generate supervisory messages for output onto said first and second fibers, (b) process incoming supervisory messages received from said first and second fibers, and (c) control at least one optical switching element associated with that node based on the supervisory messages received and the supervisory messages expected but not received;first and second transmitters placing outgoing supervisory messages onto said first and second fibers;first and second receivers receiving incoming supervisory messages from said first and second fibers; andWDM couplers interfacing said first and second transmitters and said first and second receivers to said first and second fibers;whereby supervisory messages are sent in both directions on each of said first and second fibers, notwithstanding the fact that each of said first and second fibers carries network traffic in only one direction.