Abstract: A reconfigurable multi-channel (WDM) optical ring network with optical shared protection. Preferably, the shared protection is based on a channel optical shared protection ring. The reconfigurable multi-channel (WDM) ring network connects signals between add/drop nodes with reconfigurable optical add/drop multiplexers (ROADM). The ring architecture is used to provide redundant paths between any transmitter and receiver so that failure on one side of the ring does not cut the service. The optical shared protection ring supports full redundancy. The shared protection supports wavelength reuse and availability of protection bandwidth for low-priority traffic. The shared protection implementation can also provide full equipment redundancy including transponders if desired. The ROADM components allow for reconfiguration of the multiplexer from a remote site and can be used in a network having both shared and dedicated protection.

Abstract: The present invention relates to an optical fiber access network and a communication protection method thereof. The optical fiber access network comprises an optical fiber communication system, a wireless communication system, a communication service switch device, a second optical network unit and a protection optical fiber. The wireless communication system is introduced to protect the optical fiber between the optical branching divider and the optical network unit in the optical fiber communication system. The protection optical fiber or the wireless communication system is used to protect the communication service respectively when there is a broken failure between the optical line terminal and the optical network unit in the optical fiber communication system. This invention overcomes the limit of the resource, protects communication service of the optical fiber communication system and improves the bandwidth utility of the communication system.

Abstract: The present invention discloses a method and system for group optical channel shared protection. In the invention, when a failure occurs, operations are performed on an optical wavelength group, and four actions are accomplished at the time of switching: switching the affected optical wavelength group on the working fiber to a backup fiber (Steer); switching the optical wavelength group whose destination node is the current node on the backup fiber to the working fiber (Copy); making the optical wavelength group whose destination node is not the current node on the backup fiber transparently pass through the current node (Pass Through); and blocking or stripping the backup wavelength group transferred on the backup fiber (Strip). In addition, the invention further discloses a plurality of node structures for realizing the above operations.

Abstract: The present invention provides optical network methods and systems. In one example, a method for handling packets in a node coupled to a ring and star subnetwork may include (a) receiving in the given node a data packet on the ring subnetwork, (b) detecting a failure on the ring subnetwork, (c) determining a new transmission path to the destination node, and (d) sending the data packet along the new transmission path. In another example, an EPON may include (a) a root coupled to a ring and star subnetwork, (b) ONUs coupled to the root via a splitter/combiner and a first fiber link, (c) a second fiber link coupled to a subset of ONUs and the star subnetwork, and (d) a WDM coupler on the first fiber link that separates a first waveband of wavelengths from a second waveband of wavelengths and guides the first waveband to the star.

Abstract: A method or system including implementing one or more indicators to specify traffic ordering associated with an optical networking protocol and ordering traffic according to the one or more indicators.

Abstract: An object of the present invention is to continue to send and receive to/from a host when a failure has occurred in a storage device interface. A storage system includes a host and a storage device connected to the host via a communication line, wherein the storage device comprises a communication controller performing data communication with the host by using optical modules, and wherein the communication controller is provided with first optical modules performing data communication with the host; a second optical module performing data communication with the host, in place of a first optical module; and a controller switching, when a failure has occurred in any of the first optical modules, the first optical module in which the failure has occurred to the second optical module.

Abstract: Interworking an Ethernet Ring network with an Ethernet network with traffic engineered trunks (PBT network) enables traffic engineered trunks to be dual homed to the Ethernet ring network to enable for protection switching between active and backup trunk paths in the PBT network. In one embodiment, the active path will terminate at a first bridge node on the Ethernet ring network and the backup path will terminate at a second bridge node on the Ethernet ring network. Trunk state information is exchanged between the bridge nodes to enable the bridge nodes to determine which of the active and backup paths should be used to forward data on the trunk. Upon a change in trunk state, a flush message is transmitted on the Ethernet ring network to enable the nodes on the Ethernet ring network to relearn the path to the new responsible bridge node.

Abstract: It is an objective to provide a video transmission system enabling easy acquisition and addition of any video signal. According to the ring network, optical wavelength multiplexing and transmission of video signal to be utilized for this network is carried out, so that it is possible to implement an environment, in which all necessary video signals flow on the network. Consequently, by acquiring any video signal from the video signals flowing on the network, it is possible to acquire new video source, or by adding new video source to the network, it is possible to utilize the added video source by all apparatuses connected to the network.

Abstract: An optical transmission apparatus includes redundant line cards each having a plurality of ports, a hardware unit and a CPU. The hardware unit obtains failure information on redundant lines for each port. The CPU determines switching control of the redundant lines based on the failure information. Then, the hardware unit switches the redundant lines based on the switching control determined by the CPU, so as to transmit an SDH/SONET optical signal in a ring network. The CPU of one of the line cards is set as a master CPU on the corresponding line card to control switching of the redundant lines. Further, the CPU of the other line card is set as a slave CPU.

Abstract: A 3 fiber line switched ring (3FLSR) provides protection for (optical) transmission networking wherein N nodes are connected via 3 lines (or optical fibers) in a ring topology. Two of the three fibers form a main transmission line and may transmit in one direction in the ring whereas the third might transmit in the opposite direction. This architecture of the 3FLSR provides a dual protection scheme, including a bi-directional line switching coupled with a unidirectional line switching. Traffic is categorized based on the level of protection available for the particular traffic type. The first two transmitting fibers form a bi-directional ring, carrying primary and secondary traffic which can survive 2 and 1 failures on the ring respectively. The third fiber may form a unidirectional ring, carrying additional traffic that can be pre-empted in case of multiple failures in the bi-directional ring. The 3FLSR enables reconfiguration of existing 2/4 fiber rings and conforms to applicable standards.

Abstract: A flexible open ring optical network includes a plurality of nodes connected by twin or other suitable optical rings. Each node is operable to passively add and passively drop traffic from the rings. The nodes may include a transport element for each ring. The transport elements include an optical splitter element and an optical combiner element. The optical splitter element is operable to passively combine an add signal including local add traffic and a first transport signal including ingress traffic from a coupled optical ring to generate a second transport signal including egress traffic for transmission on the coupled optical ring. The optical combiner element is coupled to the optical splitter element and is operable to passively split a third transport signal including the ingress traffic to generate a drop signal including local drop traffic and a fourth transport signal including the ingress traffic.

Abstract: This invention discloses a method for mesh restoration, which includes the steps of: a) reserving channel resource for restoration path in the link by which the path passes and assigning discriminator for each channel, and determining the associated signaling channels for transporting the discriminator; b) when detecting the work path fails, activating the restoration path of the work path according to the discriminator which is transported by the associated signaling channel and whose value corresponds to a restoration. Using the method of the invention, the problem in rapid mesh restoration can be solved, and the speed of mesh restoration is comparable to that of the ring network protection.

Abstract: A ship includes a network, integrating services for security and control services and/or for multimedia and infotainment services on board the ship. The service-integrating network includes services for security-related systems as well as services for non-security-related systems. The conventional situation for network solutions on board cruise ships is characterized by a number of service functions and individual networks distributed over the entire ship. In at least one embodiment, the service-integrating network is embodied as a redundant ring both for services for security-relevant systems as well as for services for non-security-related systems. As such, the number of security functions and service functions and the number of individual networks can be advantageously reduced to a common high-security network.

Abstract: Disclosed is a method and node apparatus for traffic protection of Optical Transport Network (OTN), including: setting a part of channels in one fiber as working channels used for carrying traffic in need of protection, and setting a part of channels in the other fiber with a reverse transmission direction as protection channels, the number of which is equal to that of the working channels, to form a one-to-one protection for the working channels; when a failure in an optical line of OTN is detected, determining a bridging node and a switching node in accordance with pre-designated protection strategy, bridging and switching the traffic to be transmitted through the failed optical line between the working channels and the protection channels at the determined bridging node and switching node. This invention can realize OTN protection based on two-Fiber OMS shared protection ring, and improve the transmission reliability of optical networks.

Abstract: An operational optical transceiver configured to initiate operation in loop back mode. The optical transceiver includes transmit and receive signal paths, a memory capable of having microcode written to it, and a configurable switch array that is used to connect and disconnect the two signal paths as appropriate for a desired loop back mode. The microcode is structured to cause the optical transceiver to control the configurable switch array. This allows for analysis and diagnostics of the signal data.

Abstract: A static pulse bus circuit and method having dynamic power supply rail selection reduces static and dynamic power consumption over that of static pulse bus designs with fixed power supply rail voltages. Every other (even) bus repeater is operated with a selectable power supply rail voltage that is selected in conformity with a state of the input signal of the bus repeater. The odd bus repeaters are operated from the lower of the selectable power supply voltages supplied to the even repeaters. The odd bus repeaters may also be operated from a selectable power supply rail voltage opposite the selectable-voltage power supply rail provided to the even bus repeaters, in which case the opposing rail of the even bus repeaters is set to the higher of the voltages selectable in the odd bus repeaters.

Abstract: A method and system provide capacity-efficient restoration within an optical fiber communication system. The system includes a plurality of nodes each interconnected by optical fibers. Each optical fiber connection between nodes includes at least three channel groups with different priority levels for restoration switching in response to a connection failure. The system maintains and restores full-capacity communication services by switching at least a portion of the channel groups from a first optical fiber connection to a second optical fiber connection system based on the priority levels assigned to the channel groups. Service reliability is effectively maintained without to incurring additional costs for dedicated spare optical fiber equipment by improving idle capacity utilization.

Abstract: A technique for carrying out protection of data traffic in a multi-channel multi-section optical communications network by simultaneously using Optical Multiplexed Section (OMS) protection and Optical Channel (OCH) protection; the technique comprises selection of a working optical signal in an OCH protected optical channel, in case of a fault in a section of the network, by relying on an indication associated with OMS switching functionality that is required to overcome the mentioned fault.

Abstract: Wavelength division multiplex ring communication network equipment comprises a first multiplexer connected to a first optical fiber portion dedicated to transporting multiplexed signals and a second multiplexer connected to a second optical fiber portion. The equipment comprises signal protection circuitry connected to the first and second multiplexers and to a terminal which, in the event of local detection of interruption of signal transmission at a first wavelength on the first optical fiber portion, send the signals coming from the terminal to the second multiplexer at a second wavelength so that it communicates them to the second optical fiber portion, and sends to the terminal the signals that are addressed to it and that come from the second optical fiber portion at the second wavelength.

Abstract: A PON ring system and a method for realizing primary and backup link protection in a passive optical network (PON) are provided. A PON ring is established between at least two optical line terminations (OLTs) through at least two user side edge nodes or network side edge nodes. Each of the OLTs is coupled to any other OLT through the at least two edge nodes. Two links respectively in a clockwise direction and a counterclockwise direction exist in the PON ring, in which one link is a primary link and the other is a backup link. Node of the links adopt the transmission mode of “multiple sending and selective receiving”. Therefore, the present invention reduces the impact on the PON caused by single link failure in the network.

Abstract: An optical ring network has one or more working wavelengths and multiple protection wavelengths adapted to support the working wavelength(s). Routing tables may be used in network nodes to assign traffic of a failed working wavelength to a protection wavelength. The protection technique may be applied to networks employing, for example, Dense Wave Division Multiplexing (DWDM).

Abstract: Providing protection for a network includes establishing a light-trail through a sequence of nodes of an optical network, where the sequence of nodes is coupled by a first fiber and by a second fiber. Traffic is communicated through a plurality of connections of the light-trail, where a connection is operable to communicate traffic from a source node of the sequence of nodes to one or more destination nodes of the sequence of nodes. A failure of the light-trail is detected. A protection light-trail corresponding to the light-trail is established. The traffic of the plurality of connections is communicated through the protection light-trail.

Abstract: An appropriate ring topology is selected by searching network topology information on the basis of given information about client signal paths on a predetermined condition, and a wavelength ring accommodating the client signal paths and having an optimal transmission characteristic is designed on the basis of the selected ring topology. Accordingly, accommodation of client signal paths in an optical network is efficiently designed.

Abstract: An optical ring network has one or more working wavelengths and multiple protection wavelengths adapted to support the working wavelength(s). Routing tables may be used in network nodes to assign traffic of a failed working wavelength to a protection wavelength. The protection technique may be applied to networks employing, for example, Dense Wave Division Multiplexing (DWDM).

Abstract: A radio base station has a baseband unit (BB) and multiple RF heads (RH1, RH2), which are interconnected by means of a bi-directional two-fiber optical ring (R). Each RF head (RH1, RH2) has a delay counter (31) for determining a propagation delay (tL) on the ring (R) and a variable delay circuit (16, 26) for compensating a difference between the propagation delay on the ring and a predefined target delay (tRR). The delay counter counts (31) the delay between a test signal sent on the first fiber (F1) of the ring to the baseband unit and a received test signal looped back by the baseband unit on the second fiber (F2) of the ring.

Abstract: The invention provides an optical shutter (400) for a communication system of a type comprising first (B1, B2) and second (A1, A2) communication paths along which information-bearing radiation propagates in opposite directions. The shutter (400) comprises: an optical tap (440) and a power monitor (430) for monitoring power of information-bearing radiation propagating along the first path (B1, B2) and for generating a corresponding radiation power indicative signal; a control unit (420) for comparing the indicative signal with a threshold value to generate a control signal (control); and shutter switch (410) for selectively substantially transmitting or blocking radiation propagating along the second path (A1, A2) in response to the control signal.

Abstract: The synchronization of trunk failover between two FC-AL switches when a primary trunk failure occurs is disclosed. If primary trunk T1 should fail, S1 bypasses the cascade port and sends a MaRK (MRK) ordered set out over duplicate trunk T2 to switch S2. In response, S2 sends an acknowledgement MRK ordered set over T2 back to S1. S1 then reconfigures the switch to establish T2 as the primary trunk, and acts as a masters in the failover process and initiates LIP ordered sets which are communicated to all devices in the system to initialize them. Note that when S2 receives the MRK ordered set and acknowledges it by sending an acknowledgement MRK back to S1, it acts as a slave in the failover process and does not attempt to initiate LIPs, thereby eliminating the possibility of multiple Loop Initialization cycles and reducing the time in which data cannot be transmitted.

Abstract: Optical safety functions are incorporated into protection switching modules which maintain redundant pathways to avoid interruptions in optical network connections. The optical safety functions which lower optical power levels upon interruptions of optical connections are effectively combined with protection switching procedures which are also triggered by interruptions in optical network connections. The interoperation of protection and safety processes keep optical power levels below hazardous levels at system points which might be accessible to human operators.

Abstract: Techniques are disclosed for generating a hitless migration plan to optimal state, given an optimal routing and wavelength assignment for demands. For example, a technique for use in performing a circuit transition in accordance with an optical ring-based network comprises obtaining a first (e.g., initial) circuit layout and a second (e.g., final) circuit layout for a given set of demands to be routed on the optical ring-based network. The technique then comprises calculating a transition sequence plan useable to transition the network from the first circuit layout to the second circuit layout such that substantially no network service disruption occurs due to the circuit transition. The transition sequence plan is calculated by determining a minimum set of circuits that when moved from first positions in the first circuit layout result in a feasible transition sequence for remaining circuits in the first circuit layout.

Abstract: A fault protection method for optical networks is provided. The method includes monitoring intensity of downstream optical signals transmitted through a first route from a rear terminal of a primary optical channel, so as to determine if there occurs any fault; and activating a second route to transmit optical signals when a fault in the primary optical channel is detected, in which the second route is counter to the first route. The present invention also includes a system performing the fault protection method.

Abstract: A bi-directional line switched mesh includes at least one bi-directional line switched ring (BLSR) sharing a common section with a partial bi-directional line switched ring (PBLSR). The partial bi-directional line switched ring has no working traffic along the common section, but may utilize the protection bandwidth associated with the common section of the BLSR in the event of a span failure of the PBLSR. Both electrical and optical PBLSR networks are also disclosed including methods of operating the asymmetrical ring nodes having unconfigured working ports (spans).

Abstract: An optical network includes an optical ring that is capable of transmitting, between two or more nodes, a plurality of working traffic streams that include traffic transmitted in one of a plurality of wavelengths. A node is capable of transmitting, in a first wavelength, a first protection traffic stream associated with a first working traffic stream, in response to an interruption of the first working traffic stream. A node is also capable of transmitting, in a second wavelength, a second protection traffic stream associated with a second working traffic stream, in response to an interruption of the second working traffic stream. The optical network also includes a regeneration element capable of selectively regenerating the first protection traffic stream. The regeneration element is also capable of tuning the regeneration element to receive traffic in the second wavelength and of selectively regenerating the second protection traffic stream.

Abstract: Techniques are disclosed for generating a hitless migration plan to optimal state, given an optimal routing and wavelength assignment for demands. For example, a technique for use in performing a circuit transition in accordance with an optical ring-based network comprises the following steps/operations. First, a first (e.g., initial) circuit layout and a second (e.g., final) circuit layout for a given set of demands to be routed on the optical ring-based network are obtained. Then, a minimum number of free wavelengths required to transition the network from the first circuit layout to the second circuit layout is determined such that substantially no network service disruption occurs due to the circuit transition.

Abstract: Transmissions over a unidirectional optical fiber coupling multiple nodes are compensated for temperature-induced effects. A round-trip delay time is determined for a signal sent from a first node to travel around the unidirectional optical fiber loop and be received back at the first node. That measured round-trip delay time is then used to account for temperature-induced effects on signal transmissions over the unidirectional optical fiber loop. This temperature compensation is particularly beneficial in applications that require a high level of timing accuracy.

Abstract: A network managing apparatus is connected to one of multiple OADM nodes that execute optical communication on an optical ring network configured by a two-line transmission path including of an active line and a backup line. The apparatus includes a storing unit that stores arrangement information of the OADM nodes and operating wavelength information of optical signals transmitted by the nodes. A controlling unit updates the operating wavelength information retained in the storing unit based on fault information from the OADM nodes and distributes the updated operating wavelength information to the OADM nodes.

Abstract: This invention discloses a method for mesh restoration, which includes the steps of: a) reserving channel resource for restoration path in the link by which the path passes and assigning discriminator for each channel, and determining the associated signaling channels for transporting the discriminator; b) when detecting the work path fails, activating the restoration path of the work path according to the discriminator which is transported by the associated signaling channel and whose value corresponds to a restoration. Using the method of the invention, the problem in rapid mesh restoration can be solved, and the speed of mesh restoration is comparable to that of the ring network protection.

Abstract: The present invention provides multi-channel protection switching systems and methods for increased reliability and reduced cost. Advantageously, the multi-channel protection switching systems and methods of the present invention use pre-FEC rate measurements, and changes in pre-FEC rate measurements, to detect and avoid potential link failures before they occur. The multi-channel protection switching systems and methods of the present invention also use “wavelength-hopping” and other protection schemes to alleviate wavelength and time-dependent optical propagation impairments.

Abstract: A node in a first ring stores therein connection information about connecting nodes between a second ring and a third ring. Upon receiving a route of a working path by a signaling, the node determines any one of nodes composing the second ring as a branch node. If the working path is not terminated on an end node that the working path ends in the second ring thereon, and also if no node composing the second ring stores therein connection information between the end node and any one of the connecting nodes in the third ring that is connected to the second ring, the node compares each condition of selectable routes of a backup path between the end node and the branch node, and selects any one of the selectable routes as the backup path based on a result of comparison.

Abstract: A method for remotely restoring inoperative data communications is disclosed. The method includes generating a predetermined sequence of signals at a first Communications unit. The method further includes keying an output of a transmitter on and off at the first communications unit with the predetermined sequence of signals and conveying a transmission of the predetermined sequence of signals to a second communications unit. The method also includes recognizing the predetermined sequence of signals at the second communications unit as indicative of inoperability of the second communications unit and, responsive to the recognized predetermined sequence of signals, outputting a signal to attempt to restore inoperative data communications at said second communications unit.

Abstract: A communication network comprising at least one first terminal, at least one second terminal, a plurality of links, and at least first and second nodes. The first node is bidirectionally coupled to the first terminal through at least a first one of the links, and also is bidirectionally coupled to the second terminal through at least a second link and the second node. Preferably, the first node comprises a plurality of communication paths, each of which is coupled at a first end thereof to at least one corresponding first link. Second ends of the communication paths are all coupled to the second link, through a multiplexing device, and route signals between the first and second links. The first node also preferably comprises at least one alternate communication path having a first end coupled through the multiplexing device to the second link, at least one switch that is coupled to the alternate communication path, and a detector for detecting a failure in at least one of the communication paths.

Abstract: A protection system protects paths of internetwork communication between WDM ring networks, and includes a plurality of optical wavelength multiplexing networks having a plurality of nodes and a network management system for monitoring conditions of the plurality of nodes. The nodes include a first node having add/drop functions of adding/dropping wavelength-multiplexed optical signals; a second node having a signal transfer function as well as the add/drop functions; and a third node having an internetwork connection function between the networks. Each first, second and third nodes further includes optical path cross-connect switches and a table for indicating conditions of the optical path cross-connect switches and a detected node fault condition. The network management system controls to set the optical path cross-connect switches in the first, second and third nodes so that the optimal optical path connection may be obtained according to the detected node fault condition indicated in the node tables.

Abstract: A single, normally inactive, protection channel provides protection against transponder failure in a fiber optic ring network. The protection channel is established and put into operation by a series of steps that are triggered by the detection of loss of light from one transponder by the other transponder. Each node reacts to a loss of light from another node in the same way: by rerouting incoming traffic from external sources from a working input-output interface to a protection interface, to establish a path for the protection signal, and by sending a signal enabling the two nodes to resume communication.

Abstract: The present invention relates to a method for protecting an optical telecommunication network against possible failures and signal degrades, the network comprising at least two nodes; working resources and protecting resources connecting the nodes; a first protection mechanism operating at a first protection layer; and a second protection mechanism operating at a second protection layer, characterized by a) the step, carried out by a node detecting a failure that could be managed by said first mechanism, of sending downstream an in-band Forward Protection Indication signalling in order to instruct the second protection mechanism not to operate, or b) the step, carried out by a node detecting a Bit Error Rate between a certain range, of sending downstream an in-band Link Degradation Indication signalling in order to instruct the second protection mechanism to operate.

Abstract: A communication system comprises a first communication device coupled to a first optical switch by a first link, a second communication device coupled to a second optical switch by a second link, and a third link and back-up links coupling the first and second optical switches. During normal operation, the optical switches connect the third link to the first and second links. The back-up links have various costs and latencies. In response to a fault on the third link, the first optical switch and the second optical switch automatically select an available one of the back-up links having a lowest cost and an acceptable latency, and in response to the selection, automatically disconnect the first link and the second link from the third link and automatically connect the first link and the second link to the selected back-up link.

Abstract: The present invention discloses a method and system for group optical channel shared protection. In the invention, when a failure occurs, operations are performed on an optical wavelength group, and four actions are accomplished at the time of switching: switching the affected optical wavelength group on the working fiber to a backup fiber (Steer); switching the optical wavelength group whose destination node is the current node on the backup fiber to the working fiber (Copy); making the optical wavelength group whose destination node is not the current node on the backup fiber transparently pass through the current node (Pass Through); and blocking or stripping the backup wavelength group transferred on the backup fiber (Strip). In addition, the invention further discloses a plurality of node structures for realizing the above operations.

Abstract: A method of obtaining information for use in a smart antenna system is provided. The method includes monitoring an interface between a base station controller and a base station transceiver to receive signaling information being communicated via the interface. The method further includes extracting from the signaling information a subset of the signaling information operable to be used as input for selecting one or more of a plurality of beams for wireless communications.

Abstract: In an optical communication system, optical communications are transferred over a first ring and a second ring. A fault is detected on the first ring or the second ring. If the fault is detected on the first ring, a shared optical protect link is used for ring-based restoration of the first ring if the link is available, and restoration overhead for the first ring is transferred in an active location of the shared optical protect link. If the fault is detected on the second ring, the shared optical protect link is used for ring-based restoration of the second ring if the link is available, and restoration overhead for the second ring is transferred in the active location of the shared optical protect link.

Abstract: A method, system and storage medium for monitoring power control loops in an optical communication network. The method includes polling network elements to obtain power management information for the network elements. A set of power management rules is selected based on the power management information along with network configuration, channel types, etc. The power management rules are applied to determine the validity of open and closed power control loop in the network elements.

Abstract: A data transmission apparatus for implementing multiple service flow in a multiple service ring is described. The apparatus includes a trunk pipe and at least two nodes each with at least one flow. The apparatus also includes a flow Rx framer for converting data received from the flow into data packets of a predetermined protocol, a transmission setup device for setting up information for packets of the predetermined protocol to be transmitted, and a Tx framer for encapsulating the information into frames of the MSR and transmitting the same along the trunk pipe to a downstream neighbor node along the ring.

Abstract: Techniques, apparatus and systems for optical communications, including fiber ring networks with protection switching to maintain optical communications when an optical failure occurs and to automatically revert to normal operation when the optical failure is corrected, fiber ring networks that provide a circulating optical probe signal at an optical probe wavelength within the gain spectral range of optical amplifiers used in a fiber ring network to detect an optical failure, and fiber ring networks that support broadcast-and-select optical WDM signals carrying communication traffic to the optical ring nodes without regeneration at each optical ring node and one or more overlaid in-band node-to-node optical signals carrying communication traffic with regeneration at each node.