Abstract: A multi-switching device and a multi-switching method thereof perform the following steps. A first control signal and a second control signal are received. Whether the first control signal and the second control signal are received is determined. When the first control signal and the second control signal are received, whether the first control signal and the second control signal specify any control requests is determined. When the first control signal and the second control signal respectively specify a control request, a control signal protection procedure is performed to control a first bus to communicate with one of second buses, and an error warning signal is outputted. When the first control signal and the second control signal do not respectively specify any control requests, a backup processing procedure is performed, and the error warning signal is outputted.

Abstract: A method, a network, and a node each implement the transmission of Automatic Protection Switching (APS) switching coordination bytes across an OTN network. A working signal and a protection signal are received, one of which is designated as an active signal. The active signal is encapsulated in an Optical channel Data Unit (ODU) signal. APS switching coordination bytes from the working and protection signals are placed in an overhead segment of the ODU signal. The ODU signal is transmitted into and received from an Optical Transport Network (OTN) network. The working and protection signals are recreated based on the active signal encapsulated in the ODU signal and the APS switching coordination bytes in the overhead segment. The recreated working and protection signals are transmitted. In this manner, a single ODU signal may be used to transmit both the working and protection signals.

Abstract: A method and apparatus for determining if an optical input signals has been interrupted and responsively replacing an interrupted optical input signal with a replacement optical signal having a similar optical profile (e.g., such as a loopback between OADMs within a backbone network), thereby insuring that transient-induced high speed optical amplifier adjustments are avoided.

Abstract: In accordance with embodiments of the present disclosure, a method may include for each particular working demand in a communication network, calculating a dedicated backup path for a working path of the particular working demand such that each particular backup path does not include links present in the working path. The method may also include, for each particular working demand: (i) assigning to the backup path a wavelength associated with the particular working demand; and (ii) assign to the backup path a transponder at each of the source and destination of the backup path associated with the wavelength; such that the backup path for at least one particular working demand is assigned a transponder that is also assigned to the backup path for at least one other particular working demand.

Abstract: A method of restoration for an optical network, the network comprising a plurality of nodes (40, 50) interconnected with each other by optical links (130), a subset of the nodes (40) each comprising a regenerator, the method comprising: storing 160) a quality of transmission parameter and a regenerator availability at each of the plurality of nodes (40, 50); notifying (170) a branch node (110) in response to detecting a failure (140) within a link (130) forming part of the path between a source node (20) and a destination node (30), wherein the branch node (110) is the neighbouring upstream node (40, 50) upstream of the link failure (140), the branch node (110) having a regenerator; the branch node (110) computing (190) a restoration segment (100) to a merge node (120) having a regenerator which is a neighbouring downstream node which is downstream of the link failure (140), the restoration path (100) being based on the quality of transmission parameter and regenerator availability information; restoring (180

Abstract: This concerns a protected long-reach PON having a plurality of terminals connected to a distribution network that is fed by both a main and back up feed, each feed including a head end and a repeater. The back up head end had access to a ranging table with data previously obtained by the main head end, thereby speeding up the switch over in the event of a fault with the main feed. In one embodiment, the repeater has a virtual ONU therein, allowing the back up repeater to be ranged by the back up head end, thereby yet further speeding up the ranging procedure. The main and back up repeaters are sufficiently equidistant from the distribution network to allow the back up head to perform normal scheduling without performing a ranging operation on each of the terminals, even if the different terminals transmit at slightly different wavelengths. This is achieved using the ranging information obtained with regard to the back up repeater.

Abstract: Systems and methods for distributing signals in an optical network are disclosed. In accordance with one embodiment of the present disclosure a method for distributing signals in an optical network comprises combining input signals into one or more output signals, determining, an availability status of optical lanes for carrying the output signals and distributing the output signals to optical transmitters associated with the optical lanes if the availability status indicates that the optical lanes are available.

Abstract: A relay station has an optical switch that switches a reception path of an optical signal. The relay station generates a subsignal that has a wavelength different from the wavelength of a data signal corresponding to a signal to be transmitted and transmits an optical signal obtained by multiplexing the generated subsignal and the data signal. In this state, when the data signal is not included in the received optical signal, the relay station determines whether the subsignal is included in the optical signal. When it is determined that the subsignal is included, the relay station maintains a connection path of the optical switch without switching the connection path.

Abstract: Extender apparatus for an optical network includes first and second extender units having an network-facing port for connection to a backhaul fiber and a subscriber-facing port for connection to a feeder fiber. Each extender unit includes a gain assembly and is operable selectively either in an enabled state, in which the gain assembly amplifies a signal received at either port of the extender unit and couples it to the other port of the extender unit, or in a disabled state, in which the gain assembly blocks coupling of a signal from either port of the extender unit to the other port of the extender unit. A failover unit is operable when the first extender unit is in the enabled state and the second extender unit is in the disabled state to detect occurrence of at least one fault condition in the first extender unit. The failover unit is responsive to the fault condition in the first extender unit to switch the first extender unit to the disabled state and the second extender unit to the enabled state.

Abstract: A multiple conductor optical cable may be coupled to an undersea device, such as a cable joint, branching unit, or repeater, with one or more isolated bypass conductive paths being provided across the undersea device. At least one conductor may be terminated within a housing of the undersea device and at least one conductor may be coupled to a conductive bridge member that provides the isolated bypass conductive path across the device. Multiple conductor optical cables may be coupled to undersea devices in optical networks using independent power paths, for example, to deliver power to different powered components at different voltage potentials.

Abstract: A device may include a component, a first switch, a repeater, and a second switch. The component may configure optical paths between ports. The component may comprise a first pair of optical ports connected to a first pair of optical fibers, and a second pair of optical ports connected to a second pair of optical fibers. The first switch may be configured to output one of two optical signals received by the first pair of optical ports from the first pair of optical fibers. The repeater may reshape or amplify the outputted optical signal. The second switch may be configured to direct the reshaped or amplified signal to one of the second pair of optical ports.

Abstract: A method for realizing service protection in the automatically switched optical network includes following steps: after any defect occurs on the working paths that carry the service, the first node and the last node of the working paths sends the requests to restore the paths setup in opposite directions, respectively; at least one intermediate node in the restoration path establishes a connection according to the restoration path setup request, and forwards the restoration path setup request hop by hop, until the setup of the recovering path is finished; the service is switched from the working paths to the restoration paths. A system for realizing service protection and a node device in an ASON is also provided. The paths restoration process can be faster obviously using this invention, and the restoration time can be shortened, and the work efficiency and reliability can be improved, and the service can be ensured to be restored.

Abstract: An amplifier node, in an optical network, includes a first switch connected to a working path from which network traffic is received; a second switch connected to the working path to which the network traffic is transmitted; and two amplifiers that interconnect the first switch and the second switch, where the network traffic travels from the first switch to the second switch via a first amplifier. The amplifier node also includes a controller to receive an instruction to switch the network traffic from the first amplifier to a second amplifier that enables the first amplifier to be repaired; send, to the first switch and the second switch, another instruction to switch the network traffic from the first amplifier to the second amplifier; receive an indication that the network traffic is traveling via the second amplifier; and send a notification that the first amplifier can be repaired based on the indication.

Abstract: A data relay apparatus R (e.g., one included in an ONU) that performs data transfer from one port to another port reduces power consumption by performing control to limit a receive function of a receiving unit 1 at the one port under at least one of conditions that a control instruction is received from a communication partner (e.g., an OLT) connected to the one port (port 2), and that information about control is notified to the communication partner; and allows the receive function to recover when a predetermined recovery condition is satisfied (e.g., a lapse of a predetermined period of time or arrival of a predetermined time). In this case, since recognition that the receive function is limited can be shared with the communication partner, the communication partner can prevent itself from performing data transmission to the data relay apparatus R when the receive function is limited.

Abstract: A method, system and device for protecting a Long Reach Passive Optical Network (LR-PON) system are provided. The Electrical Relay (E-R) device receives the optical signal transmitted on two fiber transmission paths by the Optical Line Terminal (OLT) or Optical Network Unit (ONU) on one side, performs optical-to-electrical (O/E) conversion, signal regeneration, and electrical-to-optical (E/O) conversion for the optical signal, and sends the signal to the ONU or the OLT on the other side through the two fiber transmission paths. Through backup of the fiber transmission path, an LR-PON system protection method is provided to improve the reliability of the LR-PON system. The method, system, and device for protecting the LR-PON system under the present invention all support and are compatible with the existing functions of all devices in the existing LR-PON system.

Abstract: Schemes are provided for starting up optical transmission links where, after a link interruption, endpoints switch into a startup mode original detection state, and a query-transmit pulse goes out at both end points at given time intervals. In a “TRANSMITTED” handshake mode, in a loop to be passed through n times, and at least once, after the transmission of a transmit pulse, it is detected whether a received pulse is received within a given time span. If no received pulse is received, then the mode is ended and the system is returned to the original detection state. If a received pulse is received, it is answered with another transmit pulse. After the last transmit pulse, if another received pulse occurs within a given time span, the link is activated. If not, the “TRANSMITTED” handshake mode ends and the system enters the original detection state.

Abstract: A method for handling a fiber line fault is provided. The method includes: loading, by a station, an indication signal carrying alarm suppression information onto an optical signal to be output to a downstream fiber of the station upon detection of a fault on upstream fiber line; keeping in a normal working status, by a downstream station upon a receipt of the optical signal with the indication signal. The various embodiments of the present disclosure suppress alarms from downstream amplifier stations which are not adjacent to the failure link and further suppress APR or APSD procedures according to the alarms.

Abstract: Systems and methods are described for restoring wavelength services in mesh networks using pre-configured, standby lightpaths. The standby lightpaths are pre-cross-connected lightpaths that provide connectivity between switching nodes having a fiber link of degree-2 or higher. The restoration method overcomes the problem of optical impairments for long haul connections, avoids wavelength power balancing delays, provides wavelength conversion for capacity efficiency, and allows sharing of links across nonsimultaneous failures.

Abstract: A system and method for fault identification in optical communication networks. One or more repeaters in the system includes a loop back path that couples an output a first amplifier for amplifying signals carried in a first direction through a repeater to an input of a second amplifier for amplifying signals carried in a second direction through said repeater. Fault analysis is conducted using loop gain data associated with test signals transmitted on the first or second paths and returned on the opposite path through the loop back paths.

Abstract: An economical optical network is constituted by effectively using network resources by using the minimum number of, or minimum capacity of 3R repeaters. 3R section information corresponding to topology information on the optical network to which an optical node device itself belongs is stored, and the 3R section information stored is referred so as to autonomously determine whether or not the optical node device itself is an optical node device for implementing the 3R relay when setting an optical path passing through the optical node device itself. Alternatively, when the optical node device itself is a source node, another optical node device for implementing the 3R relay among the other optical node devices through which the optical path from the optical node device itself to the destination node passes is identified, and this identified optical node device is requested to implement the 3R relay when setting an optical path in which the optical node device itself is a source node.

Abstract: Methods and apparatuses for automatic restoration detection and automatic restoration of optical communication system are disclosed. In the methods, a first station sends an automatic restoration detection message to a second station at the opposite side of a failed link; in response to receiving an automatic restoration request message, determines that the link has been repaired in two directions, and sends an automatic restoration confirmation message to the second station; or in response to receiving the automatic restoration detection message, determines that the link from the second station to the first station has been repaired, and sends the automatic restoration request message to the second station; in response to receiving the automatic restoration confirmation message, determines that the link has been repaired in two directions; and switching to normal working states. The safety problem that the laser leakage occurs in the failed link is solved.

Abstract: A method and apparatus for restoration of operating conditions of a WDM optical ring network comprising a plurality of amplifiers linked together in a ring after a break or fault has occurred in the network. The method comprises in response to repair of the break or other fault, increasing output power or/and pump power of an amplifier in the network such that the output power or/and pump power increases substantially in accordance with a ramp function.

Abstract: An economical optical network is constituted by effectively using network resources by using the minimum number of, or minimum capacity of 3R repeaters. 3R section information corresponding to topology information on the optical network to which an optical node device itself belongs is stored, and the 3R section information stored is referred so as to autonomously determine whether or not the optical node device itself is an optical node device for implementing the 3R relay when setting an optical path passing through the optical node device itself. Alternatively, when the optical node device itself is a source node, another optical node device for implementing the 3R relay among the other optical node devices through which the optical path from the optical node device itself to the destination node passes is identified, and this identified optical node device is requested to implement the 3R relay when setting an optical path in which the optical node device itself is a source node.

Abstract: An output light intensity monitor unit of an optical repeater monitors an output light of an output point of the optical repeater. A reflected light intensity monitor unit monitors a reflected light returning from an optical fiber to the output point, An optical fiber transmission line loss from the apparatus output point to an optical fiber open end and a light intensity emitted from the open end are estimated from a monitored reflected light intensity, and a reflection abnormality detection threshold for detecting the reflection abnormality if the light intensity emitted from the open end exceeds a reference light intensity is prescribed. An output light intensity lowering amount and a reflection abnormality recovery threshold are prescribed from an output light intensity monitored at the apparatus output point and the reflected light intensity so that an open end output light intensity may be lowered to the reference light intensity.

Abstract: A bridge controller, which controls relay between terminals including emission units and addresses assigned to the terminals, acquires coordinates of a light-received element in an light receiving unit at which light emitted from an emission unit is received, and stores the acquired coordinates in a location information table memory in association with a logical location on the network. Thereafter, it is determined whether or not the stored coordinates differ from newly acquired coordinates. When it is determined that the stored coordinates differ from the newly acquired coordinates, the logical location associated with the coordinates stored in the storage unit is controlled to be changed and stored.

Abstract: Transport network interfaces operate to transport for Optical Transport Unit frames over an Optical Transport Network. Besides FEC bits for the Optical Transport Unit frames, the transmitting transport network interface provides sequences of error-determining bits for the Optical Transport Unit frames sent on working and protection communications channels. There is at least one sequence for each Optical Transport Unit frame, the number of bits in the at least one sequence much smaller than the number of bits in the Optical Transport Unit frame. The receiving transport network interface determines the bit error rates for the working and protection channels from the sequences of error-determining bits without decoding said Forward Error Correction bits and can select the working and protection channels accordingly.

Abstract: An object of the invention is to provide a wireless communication apparatus which can correct error flexibly without wasting consumed resources while maintaining the improvement of reliability resulted from error correction.

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: This concerns a protected long-reach PON having a plurality of terminals connected to a distribution network that is fed by both a main and back up feed, each feed including a head end and a repeater. The back up head end had access to a ranging table with data previously obtained by the main head end, thereby speeding up the switch over in the event of a fault with the main feed. In one embodiment, the repeater has a virtual ONU therein, allowing the back up repeater to be ranged by the back up head end, thereby yet further speeding up the ranging procedure. The main and back up repeaters are sufficiently equidistant from the distribution network to allow the back up head to perform normal scheduling without performing a ranging operation on each of the terminals, even if the different terminals transmit at slightly different wavelengths. This is achieved using the ranging information obtained with regard to the back up repeater.

Abstract: An object of the invention is to provide a wireless communication apparatus which can correct error flexibly without wasting consumed resources while maintaining the improvement of reliability resulted from error correction.

Abstract: A method and apparatus for initializing an end-to-end link in a fiber optic communications system in which a pair of nodes interconnect a pair of end devices. A first node, upon initializing a device link segment with an end device to which the node is coupled, sends a signal to the other node over a network link segment indicating that the sending node has initialized its device link segment. The first node completes initialization of the end-to-end link upon receiving a signal from the other node over the network link segment indicating that the other node has initialized its device link segment. In an alternative initialization scheme, a node momentarily operates its data channel in a loopback mode to allow its end device to initialize the device link segment in accordance with a predetermined protocol before returning to a transparent mode.

Abstract: An optical apparatus is disclosed wherein increase of the number of wavelength selective switches provided for a standby system can be suppressed. The optical apparatus includes a plurality of upstream side optical devices and a plurality of downstream side optical devices configured such that a plurality of output ports to be set as output destinations of light from a plurality of input ports can be changed over for each wavelength. An upstream side standby switch connected at a plurality of inputs thereof individually to the input ports and can change over an output of light from the inputs for each wavelength. A downstream side standby switch is connected at an input thereof to the output of the upstream side standby switch and at a plurality of outputs thereof individually to the output ports and can output light from the input to the plural outputs thereof.

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 present invention provides an automatic power restoring method capable of reliably detecting continuity by the dissolution of a line fault, to restore the optical power, even in a structure including an optical amplification medium on an optical transmission path and an optical communication system using the method. To this end, in an optical communication system to which the automatic power restoring method of the invention is applied, a pilot signal having a low transmission rate, a wavelength of which is set based on loss wavelength characteristics obtained by combining loss wavelength characteristics of an optical fiber used for the optical transmission path and loss wavelength characteristics of the optical amplification medium on the optical transmission path, is transmitted and received between an optical transmitting station and an optical receiving station when a line fault occurs, and a detection of continuity is thus performed.

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: A method, apparatus, and system for evaluation of a faulty point in a multi-stage optical amplifying and repeating transmission line which provides a totally new technique for searching for faults neither of the typical “command response type” or the “DCR method”. When a fault occurs in an optical submarine cable, the profile exhibited by the optical spectral characteristics of the optical noise signal (ASE) successively amplified through the chain of optical amplifying repeaters at the downstream side of the faulty point changes in accordance with the number of the repeaters. The technique finds the number of the repeaters until the faulty point based on the change in the profile so as to evaluate the location of the faulty point and has a step (S11) of monitoring the optical spectrum at the light receiving end and a step (S12) of determining the location of the faulty point from the monitored optical spectrum.

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 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 system and method for fault identification in optical communication networks. One or more repeaters in the system includes a loop back path that couples an output a first amplifier for amplifying signals carried in a first direction through a repeater to an input of a second amplifier for amplifying signals carried in a second direction through said repeater. Fault analysis is conducted using loop gain data associated with test signals transmitted on the first or second paths and returned on the opposite path through the loop back paths.

Abstract: An apparatus comprises an optical level controller for autonomously controlling an optical device such that an optical level of the supplied optical signal becomes an objective level, and a controlled variable storer for storing a controlled variable in storage if a restart is required, the optical level controller providing the controlled variable to control the optical signal, wherein the optical level controller starts the control of optical device after the restart while the controlled variable stored in the storage by the controlled variable storer is set at an initial value.

Abstract: In an optical transmission node network in which a first optical transmission node is connected with a second optical transmission nodes through an optical fiber cable and automatic optical output (APSD: Automatic Power Shut-Down) control is activated, after the APSD control is brought into an inhibited status, if an optical conduction to the second optical transmission node is detected, the APSD control inhibited status is canceled. In this way, if an optical transmission fiber is resorted (reconnected) after optical output power measurement or the like is carried out, the APSD control inhibition status (invalid status) is canceled for automatically restoring the APSD control activated status. Thus, optical output can be prevented from being inadvertently emitted at a high energy level from the optical fiber cable.

Abstract: Where each of switches opposed to each other detects optical-signal shutoff or optical-signal deterioration on the reception side of its port, the switch brings a link of the port down and outputs an auto-negotiation configuration code, as an LAN signal. Upon receiving the LAN signal transmitted from the switch, a repeating-transmission apparatus transmits the transmitted signal to an auto-negotiation monitor. The auto-negotiation monitor performs code analysis for the transmitted LAN signal. Where the auto-negotiation monitor detects that the transmitted LAN signal is the auto-negotiation configuration code, it notifies a monitor apparatus that “The switch detects a failure and the link is down.”, as an alarm.

Abstract: The present invention provides an automatic power restoring method capable of reliably detecting continuity by the dissolution of a line fault, to restore the optical power, even in a structure including an optical amplification medium on an optical transmission path and an optical communication system using the method. To this end, in an optical communication system to which the automatic power restoring method of the invention is applied, a pilot signal having a low transmission rate, a wavelength of which is set based on loss wavelength characteristics obtained by combining loss wavelength characteristics of an optical fiber used for the optical transmission path and loss wavelength characteristics of the optical amplification medium on the optical transmission path, is transmitted and received between an optical transmitting station and an optical receiving station when a line fault occurs, and a detection of continuity is thus performed.

Abstract: A joint “packet-optical” layer restoration mechanism protects against single, packet-layer router failures by managing network resources from both the packet layer and the optical transport layer in a synergistic manner. It reuses packet-layer router service-ports and/or transport-layer service wavelengths associated with optical switch-ports instead of reserving additional standby packet-layer router service-ports. It can reuse resources from primary paths that are unaffected by router failures and paths that exist for link-failure protection at the optical layer. Embodiments feature a modified node structure that includes both an IP router and a dynamically reconfigurable OXC, which dynamically establishes connectivity between IP-router ports and transport-layer optical fibers. The joint-layer router provides fine-granularity grooming at the IP layer and full-fledged wavelength networking via dynamic wavelength switching and/or wavelength translation at the optical layer.

Abstract: A network node includes a system enabling high-speed protection switching of traffic between respectively associated working and protection channels of a communications network. The node comprises a multi-stage switch fabric, an interface, and a toggle. The multi-stage switch fabric has a first stage including a respective plurality of stage-1 switch elements. The interface is operatively coupled to a set of one or more stage-1 switch elements, and is adapted to aggregate the working and protection channels of the communications network on a selected one of the set of stage-1 switch elements. Finally, the toggle is adapted to control the selected stage-1 switch element to map traffic between a middle stage of the switch fabric and a selected one of the working and protection channels.

Abstract: The present invention provides an optical wavelength multiplexing transmission apparatus and an optical output control method for an optical wavelength multiplexing transmission apparatus in an optical wavelength multiplexing transmission system using a main signal light and an OSC light. The optical wavelength multiplexing transmission apparatus (10a) is made up of a first transmitting/receiving section (52a) a second transmitting/receiving section (52b) and an apparatus supervisory control unit (54). This can not only achieve quick restoration from troubles, but also stably calculate an optical output level even if a change of the number of wavelengths to be multiplexed takes place in a main signal light, and even save troublesome adjustments for the improvement of reliability of a transmission line while eliminating the need for a signal source for the adjustment of a receive optical level at the initial installation.

Abstract: In a router with redundant central arbiters, a set of control processors (CPs) determines which arbiter is active, which is standby, and when to switch between them. In normal operation ingress ASICs issue requests to the active central arbiter ASIC and keep-alive requests cyclically once per chunk period to the passive arbiter ASIC, which then returns keep-alive grants through the same links to the ingress ASICs and sends standby configuration information to the optical switch ASICs. The arbiter ASICs pass a switch-over decision simultaneously to the optical switch ASICs and ingress ASICs, which empty all queues of outstanding requests, and then resend all of those requests to the new active central arbiter after all queues are empty, such that no router traffic is lost. Mechanisms ensure that during the transition the ASICs properly recognize which data links are healthy and which arbiter is active.

Abstract: The present invention relates to an optical level control method for use in an optical transmission system. In the system, a WDM terminal comprises a multiplexing/demultiplexing unit, an amplifier, an up-direction OSC light transmitting/receiving unit, an up-direction multiplexer, an up-direction branching unit, an amplifier and an APR control unit, and a repeater comprises an up-direction branching unit, an OSC light transmitting/receiving unit, an amplifier, an up-direction multiplexer, a down-direction branching unit, an amplifier, a down-direction multiplexer and an APR control unit. In this configuration, a flexible optical output level control in connection with variation in WDM light level, a selective value irrespective of occurrence of an error stemming from the passage of time and avoidable malfunctions are respectively capable. In addition, a trouble retrieving operator can eliminate the possibility of being exposed to the WDM light.

Abstract: A first transmitting section frequency-multiplexes a data signal and a monitor signal, and then converts the resultant signal to an optical signal for output. A first receiving section converts the optical signal transmitted via a first optical transmission path and a wavelength demultiplexer into an electrical signal, and then extracts the monitor signal. A difference detector compares a monitor signal level with a predetermined reference level, and then outputs wavelength information to a second optical transmission path. Based on the wavelength information transmitted via the second optical transmission path, a first wavelength controller adjusts the wavelength of the optical signal for stabilization at a predetermined wavelength. Thus, it is possible to achieve a wavelength division multiplex transmission system capable of controlling the wavelength of the optical signal at low cost.

Abstract: A signal router is described. The signal router includes a switching matrix, an error detector and a controller. The switching matrix includes a first number of inputs and a second number of outputs, and is configured to receive an information stream. The error detector is coupled to one of the second number of outputs, and is configured to generate error information by virtue of being configured to detect errors in the information stream. Likewise, the controller is coupled to the switching matrix and error detector. The controller is configured to select one of the first number of inputs, receive error information from the error detector, and configure the switching matrix to couple the selected input to one of the outputs.