Method and system for detecting optical faults within the optical domain of a fiber communication network

A method for performing testing and fault isolation of a fiber fault within an optical domain of a fiber communications network, wherein the fiber communications network includes a fiber link having at least one optical fiber for carrying optical network communication signals between a first node and a second node, each node having an optical cross connect switch, wherein at each node the optical cross-connect switch has a first and a second set of ports, comprising the steps of:

• dedicating at least one port in said first set of ports for fault detection;
• introducing an optical fault detection signal separate from network communication, having at least one characteristic distinguishable from the optical network communication signals, wherein said optical fault detection signal has a wavelength different from a wavelength of the optical network communication signals and said optical fault detection signal capable of being transmitted along the same fiber link as the optical network communication signals, said optical fault detection signal, said introducing step comprises optically coupling a transmitter to at least one dedicated port in said first set of ports in the optical cross-connect switch at the first node within the optical domain of the network;
• removing said optical fault detection signal, said removing step comprises optically coupling a receiver to at least one dedicated port in said first set of ports in the optical cross-connect switch at the first node within the optical domain of the network, wherein said optical fault detection signal is introduced and removed entirely within the optical domain of the communications network;
• and
• processing said optical fault detection signal to detect and isolate the fiber fault in the fiber link.

An apparatus for performing testing and fault isolation of a fiber fault within an optical domain of a fiber communications network, wherein the fiber communications network includes a fiber link having at least one optical fiber for carrying optical data communications traffic between first and second nodes, each node having an optical cross-connect switch, comprising:

• means for introducing an optical fault detection signal to a first location between a first optical cross connect switch and the fiber link, said introducing means including means for emitting said optical fault detection signal along the same fiber link as the optical data communications traffic, and means for coupling the optical fault detection signal to at least one optical fiber in the fiber link, said optical fault detection signal having at least one characteristic distinguishable from the optical data communications traffic, wherein said optical fault detection signal has a wavelength different from a wavelength of the optical data communications traffic;
• means for removing said optical fault detection signal at a second location between the fiber link and the second optical cross-connect switch after said optical fault detection signal has traveled in at least one fiber in the fiber link, wherein said optical fault detection signal is introduced and removed entirely within the optical domain of the communications network;
• and
• means for processing said optical fault detection signal to isolate the fiber fault in the fiber link.

An apparatus for performing testing and fault isolation of a fiber fault within an optical domain of a fiber communications network, wherein the fiber communications network includes a fiber link for carrying optical network communication signals between first and second nodes, the first node having a first optical cross-connect switch, and the second node a second optical cross-connect switch, comprising:

• a transmitter optically coupled to a first location between the first optical cross-connect switch and the fiber link that emits an optical fault detection signal separate from the network communication, and which travels along the same fiber link as the optical network communication signals, said optical fault detection signal having at least one characteristic distinguishable from the optical network communication signals, wherein said optical fault detection signal has a wavelength different from a wavelength of the optical network communication signals;
• a receiver optically coupled to a second point between the fiber link and the second optical cross-connect switch to detect said emitted optical fault detection signal and to provide an output signal representative thereof, wherein said optical fault detection signal is introduced and removed entirely within the optical domain of the communications network;
• and
• a fault processor connected to said receiver to evaluate said receiver output to isolate the fiber fault.

An apparatus for detecting a fiber fault within an optical domain of a fiber communications network, wherein the fiber communications network includes a fiber link for carrying network communication between first and second nodes, the first node having a first light terminal element and a first optical cross-connect switch, and the second node having a second light terminal element and a second optical cross-connect switch, comprising:

• a first optical cross-connect switch controller located at the first node, said first optical cross-connect switch controller including a first transmitter/receiver unit and a first fault processor;
• and
• a second optical cross-connect switch controller located at the second node, said second optical cross-connect switch controller including a second transmitter/receiver unit and a second fault processor;
• wherein said first optical cross-connect switch controller and said second optical cross-connect switch controller are optically coupled to a line side of the respective optical cross-connect switches within the optical domain of the network to the fiber link to process an optical fault detection signal separate from the network communication traffic, said optical fault detection signal having at least one characteristic distinguishable from the network communications traffic, wherein said optical fault detection signal has a wavelength different from a wavelength of the network communications traffic, and wherein said optical fault detection signal is introduced and removed entirely within the optical domain of the communications network.