Abstract: The failure isolation method includes: a first step of performing a predetermined action for the monitoring target, collecting a failure event which is a result of the action, applying the failure event to a failure cause analysis rule, and narrowing down the root cause events together with certainty factors; a second step of determining whether the root cause event and the certainty factor narrowed down in the first step satisfy a predetermined requirement and whether the narrowing-down has been completed; and a third step of, when it is determined in the second step that the narrowing-down has not been completed, performing a predetermined additional action for the monitoring target, collecting an additional failure event which is a result of the additional action, applying the additional failure event to the failure cause analysis rule, and narrowing down the root cause events together with the certainty factors.

Abstract: The failure isolation method includes: a first step of performing a predetermined action for the monitoring target, collecting a failure event which is a result of the action, applying the failure event to a failure cause analysis rule, and narrowing down the root cause events together with certainty factors; a second step of determining whether the root cause event and the certainty factor narrowed down in the first step satisfy a predetermined requirement and whether the narrowing-down has been completed; and a third step of, when it is determined in the second step that the narrowing-down has not been completed, performing a predetermined additional action for the monitoring target, collecting an additional failure event which is a result of the additional action, applying the additional failure event to the failure cause analysis rule, and narrowing down the root cause events together with the certainty factors.

Abstract: It is provided an optical receiver comprising a compensator, a compensation controller and a clock extractor. The optical receiver selects first and second values, and obtains a stabilization time necessary to change the dispersion value and a transition time shorter than the stabilization time, compensates the received optical signal using the selected first value, changes the dispersion value from the first value into the second value, compensates the received optical signal using the dispersion value when the transition time has passed since starting to change the dispersion value, creates second extraction information of the dispersion value after the transition time, compensates for dispersion of the optical signal using an dispersion value calculated based on the second value and the difference between the dispersion value after the transition time and the second value in a case where the created second extraction information indicates that the clock extraction is available.

Abstract: It is provided an optical receiver comprising a compensator, a compensation controller and a clock extractor. The optical receiver selects first and second values, and obtains a stabilization time necessary to change the dispersion value and a transition time shorter than the stabilization time, compensates the received optical signal using the selected first value, changes the dispersion value from the first value into the second value, compensates the received optical signal using the dispersion value when the transition time has passed since starting to change the dispersion value, creates second extraction information of the dispersion value after the transition time, compensates for dispersion of the optical signal using an dispersion value calculated based on the second value and the difference between the dispersion value after the transition time and the second value in a case where the created second extraction information indicates that the clock extraction is available.

Abstract: Disclosed is an optical cross connect apparatus that is applicable to an end office node and relay node in a path. The optical cross connect apparatus includes an optical switch for generating plural optical output signals from plural optical input signals; an optical level monitor section for detecting the optical levels of the optical input signals; and a control section that is connected to the optical switch and the optical level monitor section, includes a path switching management section for retaining a path switching management table, references the path switching management table when the optical input signals detected by the optical level monitor section are found to be OFF, and judges whether the optical switch should be operated.

Abstract: An optical communication network system is disclosed, which includes an optical switching apparatus. The optical switching apparatus includes an optical switch for switching and setting routes of an optical signal without being converted, a control unit for instructing the optical switch to execute a route switching operation, and a performance monitor for detecting performance of the optical signal having a route set by the optical switch. The performance monitor issues an alarm when the performance detected is deteriorated from predetermined performance. The control unit includes an alarm masking unit for masking the alarm issued from the performance monitor at least for a predetermined masking period from a starting time of a switching operation by the optical switch, and thus preventing the alarm from being issued.

Abstract: A medium-scale IP telecommunications network is configured in a low-cost optical network with good reliability and expandability. A physical configuration example has a center node 2-1 and eight local nodes 2-11 through 2-18 connected in one OADM ring 2-21/2-22. The logical configuration is a star configuration with the central node 2-1 at its origin with all traffic passing through the center node 2-1. The local nodes 2-11 through 2-18 are connected to the central node 2-1 by wavelength-unit optical channels or optical paths ?1 through ?8. Channels are added as required. Initially, for example, the center node 2-1 and the local node 2-5 are connected by ?5, but ?13 can added when the need arises. Since the logical star network is limited to approximately two add/drop optical channels at local nodes, costs are reduced by using inexpensive filters (e.g., dielectric interference film filters or fiber Bragg reflectors) that are capable of extracting only the specific wavelength of the optical channel.

Abstract: In an optical switching apparatus having redundantly-arranged optical switches, a route switching operation mode, an autonomic redundant switching operation mode and a compulsory redundant switching operation mode are discriminated from one another so that these operation modes are prevented from being executed at the same time, and also proper mask processing is performed at every switching operation mode. Therefore, emission of an undesired alarm and thus occurrence of malfunction when each switching operation is carried out can be prevented.

Abstract: An optical transmission apparatus, an optical repeater using the optical transmission apparatus, and an optical cross-connect equipment for controlling switches depending on supervisory information, comprising: a doped fiber for amplifying an optical signal of wavelength ?d; a wavelength multiplexer for outputting a pumping light to the doped fiber; a wavelength multiplexer for multiplexing an amplified optical signal and a supervisory optical signal to as to output it to an optical fiber at downstream side; a pumping and supervisory light source; an optical coupler for distributing the light from the light source at a ratio of N:1 to the wavelength multiplexers; and a driver for controlling the light source by adding the supervisory information and a direct current signal.

Abstract: Disclosed is an optical cross connect apparatus that is applicable to an end office node and relay node in a path. The optical cross connect apparatus includes an optical switch for generating plural optical output signals from plural optical input signals; an optical level monitor section for detecting the optical levels of the optical input signals; and a control section that is connected to the optical switch and the optical level monitor section, includes a path switching management section for retaining a path switching management table, references the path switching management table when the optical input signals detected by the optical level monitor section are found to be OFF, and judges whether the optical switch should be operated.

Abstract: An optical communication network system is disclosed, which includes an optical switching apparatus. The optical switching apparatus includes an optical switch for switching and setting routes of an optical signal without being converted, a control unit for instructing the optical switch to execute a route switching operation, and a performance monitor for detecting performance of the optical signal having a route set by the optical switch. The performance monitor issues an alarm when the performance detected is deteriorated from predetermined performance. The control unit includes an alarm masking unit for masking the alarm issued from the performance monitor at least for a predetermined masking period from a starting time of a switching operation by the optical switch, and thus preventing the alarm from being issued.

Abstract: An optical one-to-one protection switching apparatus exchanges signals between a transmit node and a receive node. If a fault is detected in the first transmission line (down-stream), a controller in the node controls a drive circuit so as to shut off a gate. Then, the controller in the transmit node upon receiving a switching request from the receive node, controls the drive circuit so as to shut off the gate. Thereby, the optical switch is switched. The transmitter of the client terminal is thus connected to the second transmission line (down-stream). Upon receiving the switching request from the transmit node, the optical switch in the receive node is switched. Thereby the receiver in the client terminal is connected to the second transmission line (down-stream).

Abstract: The optical switching equipment is basically configured as a single configuration without protection as a basic unit and to split the optical signal into one signal passing through the equipment and the other signal to be added and dropped in the equipment and execute the adding and dropping process in a redundant portion. The optical transport network is configured to locate a plurality of optical switching equipments and optical transmission routes so as to allow the optical signals processed in the equipment for adding the optical signals to pass through the different optical transmission routes and equipments respectively. The optical signal allowed to pass through the equipment is processed in the single configuration portion of the equipment. The setting of the routes of the optical switching equipment and the optical transmission route makes it possible for the overall optical transport network to transmit the redundant optical signal.

Abstract: An optical communication network system is disclosed, which includes an optical switching apparatus. The optical switching apparatus includes an optical switch for switching and setting routes of an optical signal without being converted, a control unit for instructing the optical switch to execute a route switching operation, and a performance monitor for detecting performance of the optical signal having a route set by the optical switch. The performance monitor issues an alarm when the performance detected is deteriorated from predetermined performance. The control unit includes an alarm masking unit for masking the alarm issued from the performance monitor at least for a predetermined masking period from a starting time of a switching operation by the optical switch, and thus preventing the alarm from being issued.

Abstract: In an optical switching apparatus having redundantly-arranged optical switches, a route switching operation mode, an autonomic redundant switching operation mode and a compulsory redundant switching operation mode are discriminated from one another so that these operation modes are prevented from being executed at the same time, and also proper mask processing is performed at every switching operation mode. Therefore, emission of an undesired alarm and thus occurrence of malfunction when each switching operation is carried out can be prevented.

Abstract: In an optical switching apparatus having redundantly-arranged optical switches, a route switching operation mode, an autonomic redundant switching operation mode and a compulsory redundant switching operation mode are discriminated from one another so that these operation modes are prevented from being executed at the same time, and also proper mask processing is performed at every switching operation mode. Therefore, emission of an undesired alarm and thus occurrence of malfunction when each switching operation is carried out can be prevented.

Abstract: A medium-scale IP telecommunications network is configured in a low-cost optical network with good reliability and expandability. A physical configuration example has a center node 2-1 and eight local nodes 2-11 through 2-18 connected in one OADM ring 2-21/2-22. The logical configuration is a star configuration with the central node 2-1 at its origin with all traffic passing through the center node 2-1. The local nodes 2-11 through 2-18 are connected to the central node 2-1 by wavelength-unit optical channels or optical paths &lgr;1 through &lgr;8. Channels are added as required. Initially, for example, the center node 2-1 and the local node 2-5 are connected by &lgr;5, but &lgr;13 can added when the need arises. Since the logical star network is limited to approximately two add/drop optical channels at local nodes, costs are reduced by using inexpensive filters (e.g.

Abstract: An optical transmission apparatus, an optical repeater using the optical transmission apparatus, and an optical cross-connect equipment for controlling switches depending on supervisory information, comprising: a doped fiber for amplifying an optical signal of wavelength &ogr;d; a wavelength multiplexer for outputting a pumping light to the doped fiber; a wavelength multiplexer for multiplexing an amplified optical signal and a supervisory optical signal to as to output it to an optical fiber at downstream side; a pumping and supervisory light source; an optical coupler for distributing the light from the light source at a ratio of N:1 to the wavelength multiplexers; and a driver for controlling the light source by adding the supervisory information and a direct current signal.

Abstract: In an optical switching apparatus having redundantly-arranged optical switches, a route switching operation mode, an autonomic redundant switching operation mode and a compulsory redundant switching operation mode are discriminated from one another so that these operation modes are prevented from being executed at the same time, and also proper mask processing is performed at every switching operation mode. Therefore, emission of an undesired alarm and thus occurrence of malfunction when each switching operation is carried out can be prevented.

Abstract: A wavelength tunable optical transmitter is used in a protection system of a WDM network, and its conventional wavelength tuning process has to perform steps of tuning intermediate wavelengths which are used by other optical transmission equipment in the network. Thus the conventional system interferes with normal communications in the other optical transmission equipment. To prevent the interference, wavelength tunable optical transmission equipment is provided with an optical gate for selectively on and off an optical signal output. A controller closes the optical gate while wavelength tunable optical transmission equipment and opens the optical gage to pass the signal through the optical gate once the target wavelength is attained and virtually stabilized.