A method of monitoring a communications network by monitoring packet errors in one of the paths having at least two optical sections coupled in series with a break in continuity of optical transmission monitoring between the optical sections, and monitoring a transmission quality of each of these optical sections. A state is detected in which the monitored packet errors do exceed an acceptable threshold, but at the same time the transmission quality of each of the optical sections is acceptable, and an indication is transmitted of the detection. This can cause a request for an alternative path for the packets, or cause adapting of these optical sections to reduce bit errors. This can enable handling of potential conflict between packet and optical layers, when the packet layer sees errors but the optical layer indicates no problem.

Techniques are provided for identifying and monitoring connections in an optical system. A plurality of optical ports is configured to receive a plurality of optical links that couple with one or more remote optical devices. At least one light source generates identification (ID) signals. At least one optical element configured to direct the ID signals into transmission paths from the source optical device to the remote optical device/s over the plurality of optical links. The remote optical device/s include one or more optical elements that direct the ID signals through a set of WDM filters and returns the ID signals. At least one optical element directs returned ID signals to an optical channel monitor. At least one microprocessor configured to execute control instructions to generate the ID signals and process one or more outputs of the optical channel monitor in response to the returned ID signals to identify the plurality of optical links.

A system and method is disclosed in which circuitry of a first controller of a first node on a first path within a transport network receives a first signal indicating a failure within the first path from a second controller. The first node is an end node of the first path. A first client signal failure clear signal is received from a second node upstream of the first node on the first path. The first client signal failure clear signal indicates that a non-restorable fault has been resolved such that the first path can be considered for carrying data traffic. The non-restorable fault is a failure at the source. Subsequent to receiving the first signal indicating the failure within the first path, a backward defect indication clear signal is transmitted to the second node, the backward defect indication clear signal indicating an absence of a failure in the first path.

Systems and methods include, responsive to a fault affecting an optical service on an active path in an optical network operating at a frequency μ1 via an optical transceiver and having optical line protection via an optical protection switch, switching to an inactive path that now becomes the active path and finding a new route in the optical network for the inactive path that has the fault; responsive to being unable to find a route at the frequency μ1, switching the inactive path to a new route at a different frequency μ2; and implementing spectrum coordination relative to the inactive path to either determine the frequency μ1 is available on the new route or to find another new route for the inactive path where the frequency μ1 is available.

An optical network having a first terminal node, a second terminal node, and a network service system is described. The first terminal node has a plurality of ports and a signal restoration component to create a restored path. The second terminal node has a plurality of ports and a failure monitor to issue a path failure notice. A working path, a protection path, and the restored path are each fiber optic lines optically coupling the first terminal node to the second terminal node to enable a service, each path requiring a quantity of exclusive licenses. The network service system receives a path failure notice indicating a working path failure, calculates the quantity of licenses required by the restored path, releases the quantity of licenses required by the working path and applies at least a portion of the quantity of licenses to the quantity of licenses required by the restored path.

A method for assigning spectral resources comprises assigning spectral resources for a plurality of communication channels. The spectral resources for the plurality of communication channels comprise excess resources that are at least tentatively kept unoccupied. The excess resources of a plurality of communication channels are assigned to be spectrally contiguous.

Systems and methods include, responsive to a fault affecting an optical service on an active path in an optical network operating at a frequency μ1 via an optical transceiver and having optical line protection via an optical protection switch, switching to an inactive path that now becomes the active path and finding a new route in the optical network for the inactive path that has the fault; responsive to being unable to find a route at the frequency μ1, switching the inactive path to a new route at a different frequency μ2; and implementing spectrum coordination relative to the inactive path to either determine the frequency μ1 is available on the new route or to find another new route for the inactive path where the frequency μ1 is available.

A fiber loop includes a plurality of processors coupled to each other and a controller coupled to each of the plurality of processors. The controller is configured to: assign to each of the plurality of processors a number of wavelengths for interconnect communications between the plurality of processors; receive, from a first processor of the plurality of processors, a request for one or more additional wavelengths; determine whether an interconnect bandwidth utilization on the fiber loop is less than a threshold; and in response to determining that the interconnect bandwidth utilization on the fiber loop is less than the threshold, reassign, to the first processor, one or more wavelengths that are assigned to a second processor of the plurality of processors.

The present invention proposes a new method for solving the problem of fault tolerance. This new approach obtains all secondary routes assigned to each possible connection (user). The secondary routes replace the main routes when these are affected by at least one fault, which keeps the users connected as long as, for each connection, there is at least one route with operative links for reaching the destination nodes thereof. This new approach solves the general case of an arbitrary set of simultaneous link failures. The method also assesses the number of wavelengths for each link of the network, so that the probability of any connection request from a determined user c being blocked is less than a predefined threshold β.sub.c, despite the possible occurrence of the fault scenario.

Systems and methods for managing a list or restoration paths are provided. A method, according to one implementation, includes obtaining a list of restoration paths used for restoring transmission in a network when a home path between an originating node and a termination node is unavailable. The restoration paths are listed in a specific order based on ongoing transmission costs, where the ongoing transmission cost for each restoration path is based on characteristics associated with transmitting signals along the respective restoration path. The method also includes the step of reordering the restoration paths in the list based on restoration costs and the ongoing transmission costs. The restoration cost for each restoration path is based on a procedure for switching from the home path to the respective restoration path.