Optical node apparatus, optical communication system, and abnormality determination method

Abstract

This optical node apparatus comprises: a distribution device that distributes inputted optical signals; and an optical cross-connect unit that is connected to two or more paths. The distribution device comprises: a plurality of first ports to which a plurality of subscriber devices is connected; a plurality of second ports that is connected to the optical cross-connect unit; and a control unit that sets a detection optical path between a first port, to which at least one newly connected new subscriber device is connected, among the plurality of first ports, and an unused second port among the plurality of second ports, and determines whether or not the wavelength of the optical signal transmitted from the at least one new subscriber device is abnormal on the basis of the power of the optical signal in each of the first port and the unused second port between which the detection optical path is set.　

Description

Optical node device, optical communication system, and abnormality determination method

[0001] The present invention relates to an optical node device, an optical communication system, and an abnormality determination method.

[0002] Conventionally, optical communication systems have been proposed that can connect subscriber devices located at arbitrary points end-to-end on a wavelength-by-wavelength basis (see, for example, Patent Document 1). In optical communication systems, it is necessary to open an optical path between subscriber devices that communicate. Here, a method for opening an optical path for a subscriber device to connect to a subscriber device with which it will communicate via an optical transmission line and one or more optical node devices will be described with reference to FIG. 7 .

[0003] Fig. 7 is a diagram for explaining an optical path opening method in an optical communication system. As shown in Fig. 7, the optical communication system S comprises multiple optical node devices 1-1 to 1-2 and multiple control units 2-1 to 2-2. A subscriber device 3 is connected to the optical node device 1-1 via an optical transmission path L. A subscriber device 4 is connected to the optical node device 1-2 via an optical transmission path L. The optical node devices 1-1 and 1-2 are connected by a relay network NW including multiple optical transmission paths. Hereinafter, when there is no need to distinguish between the subscriber devices 3 and 4, they will simply be referred to as subscriber devices.

[0004] The control unit 2-1 controls the optical node device 1-1 and the subscriber device 3 connected to the optical node device 1-1. The control unit 2-2 controls the optical node device 1-2 and the subscriber device 4 connected to the optical node device 1-2. The control unit 2 includes a subscriber device management control unit 6 and a node control unit 7. The subscriber device management control unit 6 controls the subscriber devices connected to the optical node device 1 (for example, allocating wavelengths). The node control unit 7 controls routes in the optical node device 1 so that the subscriber devices can communicate with other subscriber devices.

[0005] The optical node device 1-1 accommodates one or more subscriber devices 3. The optical node device 1-2 accommodates one or more subscriber devices 4. The optical node device 1-1 and the optical node device 1-2 have the same configuration, so branch numbers will be omitted in the description. The optical node device 1 comprises multiple optical distribution units 8 and a WXC unit 9. The optical distribution unit 8 distributes one or more input optical signals. Specifically, the optical distribution unit 8 performs add and drop operations. The add operation is an operation in which, based on optical signals transmitted from multiple subscriber devices, optical signals having the same output route are multiplexed and output to the WXC unit 9 for each route. The drop operation is an operation in which optical signals input from multiple routes and addressed to each subscriber device are output so that they reach the subscriber device in question.

[0006] The WXC unit 9 wavelength-multiplexes or wavelength-demultiplexes optical signals for each path. The WXC unit 9 includes a plurality of wavelength multiplexing units 91 and a plurality of wavelength demultiplexing units 92. The WXC unit 9 includes a combination of one wavelength multiplexing unit 91 and one wavelength demultiplexing unit 92 for at least each path. Since FIG. 7 shows an example in which there are two paths, the WXC unit 9 includes at least two wavelength multiplexing units 91 and two wavelength demultiplexing units 92. Here, the combination of one wavelength multiplexing unit 91 and one wavelength demultiplexing unit 92 will be described as a wavelength multiplexing / demultiplexing unit.

[0007] The wavelength multiplexing / demultiplexing unit multiplexes the optical signals input from each optical distribution unit 8 and outputs the multiplexed optical signals to the optical transmission line L side, demultiplexes the wavelength-multiplexed optical signals from the optical transmission line L side according to wavelength, and demultiplexes and outputs the demultiplexed optical signals of each wavelength according to wavelength to the optical distribution unit 8 that accommodates the subscriber device that is the destination of each optical signal. Note that the wavelength multiplexing / demultiplexing unit outputs, among the wavelength-multiplexed optical signals input from the optical transmission line L side, optical signals addressed to subscriber devices accommodated in optical node devices at other bases to the wavelength multiplexing / demultiplexing unit of the path to that base.

[0008] When a subscriber device is newly connected to an optical node device via an optical transmission path L, information necessary for authentication and registration of the new subscriber device is exchanged between the newly connected subscriber device (hereinafter referred to as "new subscriber device") and the subscriber device management and control unit 6. The new subscriber devices are assumed to be subscriber devices 3-1 and 3-2. The subscriber device management and control unit 6 also instructs the new subscriber devices to allocate and set an emission wavelength so that the wavelength does not overlap with that of other optical paths along the transmission route. This allows the new subscriber device to set the wavelength to be used for communication. The new subscriber device then transmits an optical signal at the wavelength instructed by the subscriber device management and control unit 6.

[0009] Upon completion of the authentication and registration of the new subscriber device and the wavelength setting, the node control unit 7 performs internal forwarding settings in the optical distribution unit 8 and WXC unit 9 constituting the optical node device 1 so that the optical signal transmitted from the new subscriber device is forwarded to the subscriber device with which it will communicate. As a result, it is possible to open an optical path that directly connects subscriber device 3-1 to subscriber device 4-1 with which it will communicate, and an optical path that directly connects subscriber device 3-2 to subscriber device 4-2 with which it will communicate.

[0010] International Publication No. 2023 / 135737

[0011] When a new optical path is opened in the conventional optical communication system S, it is possible that the new subscriber device will transmit an optical signal (hereinafter referred to as an "illegal optical signal") having a wavelength different from the emission wavelength instructed by the subscriber device management control unit 6. For example, if a subscriber device fails or malfunctions, or if a subscriber intentionally sets an illegal wavelength, it is conceivable that the new subscriber device will transmit an illegal optical signal.

[0012] In this case, when an optical distribution unit including a wavelength selective switch (WSS) or an arrayed waveguide grating (AWG) is used, the optical signal is blocked in the wavelength selective switch or arrayed waveguide grating, making it impossible to open an optical path. However, conventional techniques have been unable to detect an abnormality in the transmission wavelength of a subscriber device when opening an optical path, making it impossible to identify that the wavelength transmitted by the subscriber device is different from the specified wavelength, which is the cause of the optical path not being able to be opened.

[0013] In view of the above circumstances, an object of the present invention is to provide a technique capable of detecting an abnormality in the transmission wavelength of a subscriber device when an optical path is opened.

[0014] One aspect of the present invention is an optical node device comprising: a distribution device that distributes input optical signals; and an optical cross-connect unit that connects to two or more routes, wherein the distribution device comprises a plurality of first ports to which a plurality of subscriber devices are connected; a plurality of second ports that connect to the optical cross-connect unit; a control unit that sets a detection optical path between a first port among the plurality of first ports to which at least one newly connected new subscriber device is connected and an unused second port among the plurality of second ports; and that determines whether the wavelength of the optical signal transmitted from the one or more new subscriber devices is abnormal based on the power of the optical signal at each of the first port to which the detection optical path is set and the unused second port.

[0015] One aspect of the present invention is an optical communications system comprising a subscriber device management and control unit that allocates wavelengths to be used for communications to one or more newly connected new subscriber devices, a node control unit that controls at least the connections of the ports to which the new subscriber devices are connected, and an optical node device that operates under the control of the node control unit, wherein the optical node device comprises: a distribution device that distributes input optical signals in accordance with instructions from the node control unit; and an optical cross-connect unit that connects to two or more routes, the distribution device comprising: a plurality of first ports to which a plurality of subscriber devices are connected; a plurality of second ports that connect to the optical cross-connect unit; and a control unit that sets a detection optical path between a first port among the plurality of first ports to which at least one newly connected new subscriber device is connected and an unused second port among the plurality of second ports, and measures the power of the optical signal at each of the first port to which the detection optical path is set and the unused second port, and wherein the node control unit or the control unit determines whether the wavelength of the optical signal transmitted from the one or more new subscriber devices is abnormal based on the measured power of the optical signal.

[0016] One aspect of the present invention is an anomaly determination method that sets up a detection optical path between a first port to which at least one newly connected new subscriber device is connected, among a plurality of first ports to which a plurality of subscriber devices are connected, and an unused second port among a plurality of second ports connected to an optical cross-connect unit that connects to two or more routes, and determines whether the wavelength of the optical signal transmitted from the one or more new subscriber devices is abnormal based on the power of the optical signal at each of the first port to which the detection optical path is set and the unused second port.

[0017] According to the present invention, it is possible to detect an abnormality in the transmission wavelength of a subscriber device when an optical path is opened.

[0018] FIG. 1 is a diagram illustrating an example of the configuration of an optical communication system in a first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of an optical distribution unit in the first embodiment. FIG. 3 is a diagram for explaining a method of determining whether a wavelength set by a new subscriber device is normal. FIG. 4 is a sequence diagram illustrating the flow of an optical path opening process in the optical communication system in the first embodiment. FIG. 5 is a diagram illustrating an example of the configuration of an optical distribution unit in a second embodiment. FIG. 6 is a diagram illustrating an example of the configuration of an optical distribution unit in a third embodiment. FIG. 7 is a diagram for explaining a method of opening an optical path in an optical communication system.

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] First Embodiment FIG. 1 is a diagram illustrating an example of the configuration of an optical communication system 100 according to a first embodiment. The optical communication system 100 includes multiple optical node devices 10 and multiple control units 20. For example, the optical communication system 100 includes two optical node devices 10-1 to 10-2 and two control units 20-1 to 20-2. The number of optical node devices 10 and control units 20 included in the optical communication system 100 is not particularly limited. One or more subscriber devices 30 are connected to the optical node device 10-1 via an optical transmission path L. The optical transmission path L is, for example, an optical fiber. One or more subscriber devices 40 are connected to the optical node device 10-2 via the optical transmission path L. The optical transmission path L is, for example, an optical fiber. The optical node device 10-1 and the optical node device 10-2 are connected via a trunk network NW. The trunk network NW is composed of multiple optical transmission paths connected to different paths.

[0021] In the following description, the direction from the subscriber device 30 toward the control unit 20 is referred to as the upstream direction, and the direction from the control unit 20 toward the subscriber device 30 is referred to as the downstream direction. The number of subscriber devices 30 and 40 is not particularly limited.

[0022] The optical node device 10-1 accommodates one or more subscriber devices 30. The optical node device 10-1 comprises a plurality of optical distribution units 11-1 and 12-1, and a WXC unit 13-1. The optical node device 10-2 accommodates one or more subscriber devices 40. The optical node device 10-2 comprises a plurality of optical distribution units 11-2 and 12-2, and a WXC unit 13-2. Here, the functional units of the optical node device 10-1 and the functional units of the optical node device 10-2 will be described together because they perform the same processing.

[0023] The optical distribution unit 11 is used when transmitting an optical signal from the subscriber device 30 to the subscriber device 40, or when transmitting an optical signal from the subscriber device 40 to the subscriber device 30. The optical distribution unit 11 distributes one or more input optical signals. Specifically, the optical distribution unit 11 performs an add operation and a drop operation. The add operation is an operation of multiplexing optical signals having the same output route based on optical signals transmitted from multiple subscriber devices and outputting the multiple multiplexed optical signals to the WXC unit 9 for each route. The drop operation is an operation of outputting optical signals input from multiple routes and addressed to each subscriber device so that they reach the relevant subscriber device.

[0024] Furthermore, when an optical path is opened, the optical distribution unit 11 sets a detection optical path between the port to which the new subscriber device is connected and an unused port. The unused port is a port that is not used for communication between the subscriber device 30 and the subscriber device 40. The unused port does not have to be connected to, for example, the WXC unit 13. The detection optical path is an optical path set to forward an optical signal transmitted from the new subscriber device to an unused port. The detection optical path is an optical signal path that exclusively uses the wavelength assigned to the new subscriber device. Therefore, by setting the detection optical path, the optical signal transmitted from the new subscriber device can be forwarded to an unused port. As a result, when an optical path is opened, the optical signal transmitted from the new subscriber device is input to the optical distribution unit 11 and then input to an unused port via the detection optical path.

[0025] In the present invention, the optical distribution unit 11 determines whether the wavelength set by the new subscriber device is normal by setting a detection optical path between the port to which the new subscriber device is connected and an unused port. Specifically, the optical distribution unit 11 measures the power of the optical signal transmitted from the new subscriber device when it is input and when it is input to the unused port. Based on the measurement results of the optical signal power, the optical distribution unit 11 determines whether the wavelength set by the new subscriber device is abnormal.

[0026] If the optical distribution unit 11 determines that the wavelength set by the new subscriber device is abnormal, it transmits a control signal indicating the determination result that the wavelength is abnormal to the control unit 20. If the optical distribution unit 11 determines that the wavelength set by the new subscriber device is not abnormal, it transmits a control signal indicating the determination result that the wavelength is normal to the control unit 20. The specific configuration of the optical distribution unit 11 will be described later.

[0027] The optical distribution unit 12 is used when receiving an optical signal in a direction from the subscriber device 30 to the subscriber device 40, or when receiving an optical signal in a direction from the subscriber device 40 to the subscriber device 30. The optical distribution unit 12 distributes one or more input optical signals. Specifically, the optical distribution unit 12 performs an add operation and a drop operation.

[0028] The WXC unit 13 wavelength-multiplexes or wavelength-demultiplexes optical signals for each path. The WXC unit 13 includes multiple wavelength multiplexers 14 and multiple wavelength demultiplexers 15. The WXC unit 13 includes a combination of one wavelength multiplexer 14 and one wavelength demultiplexer 15 for at least each path. Since FIG. 1 shows an example in which there are two paths, the WXC unit 13-1 includes at least two wavelength multiplexers 14-1-1 to 14-1-2 and two wavelength demultiplexers 15-1-1 to 15-1-2, and the WXC unit 13-2 includes at least two wavelength multiplexers 14-2-1 to 14-2-2 and two wavelength demultiplexers 15-2-1 to 15-2-2. It is sufficient for the WXC unit 13 to include two or more combinations of wavelength multiplexers 14 and wavelength demultiplexers 15.

[0029] The wavelength multiplexing unit 14 multiplexes the optical signals input from the optical distribution unit 11 and outputs the multiplexed optical signals to the backbone network NW side. The wavelength demultiplexing unit 15 demultiplexes the wavelength-multiplexed optical signals input from the backbone network NW side according to wavelength, and outputs the demultiplexed optical signals of each wavelength to the optical distribution unit 11. Note that the wavelength demultiplexing unit 15 outputs, among the wavelength-multiplexed optical signals input from the backbone network NW side, optical signals addressed to subscriber devices accommodated in optical node devices at other bases to the wavelength multiplexing / demultiplexing unit of the path to that base.

[0030] The control unit 20-1 controls the optical node device 10-1 and the subscriber device 30. Here, the control of the optical node device 10-1 includes, for example, connection settings between the ports of the optical distribution units 11-1 and 12-1 and the WXC unit 13-1 (for example, setting a transfer path or instructing to set an optical path). The control of the subscriber device 30 includes, for example, when a subscriber device 30 is newly connected to the optical node device 10-1, processing such as authentication and registration with the new subscriber device 30, allocation of an emission wavelength to the subscriber device 30 (for example, including subscriber devices 30 already connected to the optical node device 10-1 and new subscriber devices), instructions to stop light, instructions to change wavelength, etc.

[0031] The control unit 20-1 includes a subscriber device management control unit 21-1 and a node control unit 22-1. The subscriber device management control unit 21-1 performs the above-described control on the subscriber devices 30 connected to the optical node device 10-1 (including, for example, subscriber devices 30 already connected to the optical node device 10-1 and new subscriber devices). Furthermore, if the determination result output from the optical distribution unit 11-1 indicates an abnormality, the subscriber device management control unit 21-1 may instruct the new subscriber device to emit light at a wavelength again, or may assign a wavelength different from the assigned wavelength that is not being used for communication.

[0032] The node control unit 22-1 performs path control and the like in the optical node device 10-1 so that the subscriber device 30 can communicate with the subscriber device with which it is communicating. For a new subscriber device, the node control unit 22-1 sets up an internal port-to-port connection in the optical distribution unit 11-1 so that an optical signal output from the new subscriber device is forwarded to an unused port. For example, when an optical path is opened for the new subscriber device, the node control unit 22-1 sets up a detection optical path between a port to which the new subscriber device is connected and an unused port so that an optical signal output from the new subscriber device is forwarded to the unused port.

[0033] If the determination result output from the optical distribution unit 11-1 indicates normality, the node control unit 22-1 sets the internal port connections of the optical distribution unit 11-1 so that the optical signal transmitted from the new subscriber device is output to the WXC unit 13-1, which outputs the optical signal to the route assigned to the newly opened optical path. Furthermore, the node control unit 22-1 performs internal forwarding settings of the WXC unit 13-1. For example, the node control unit 22-1 performs route control in the optical node device 10-1 so that the new subscriber device can communicate with the subscriber device with which it is to communicate. This makes it possible to open an optical path so that the optical signal transmitted from the new subscriber device is forwarded to the subscriber device with which it is to communicate.

[0034] On the other hand, if the determination result output from the optical distribution unit 11-1 indicates an abnormality, the node control unit 22-1 sets the port connections of the optical distribution unit 11-1 so that the optical signal transmitted from the new subscriber device is not output to the WXC unit 13-1. For example, the node control unit 22-1 maintains the port connections of the optical distribution unit 11-1 so that the optical signal transmitted from the new subscriber device continues to be forwarded to unused ports. In this way, the node control unit 22-1 controls the optical signal transmitted from the new subscriber device so that it does not affect the communications of other subscriber devices to which optical paths have already been opened until the set wavelength of the new subscriber device is set to a normal wavelength. This makes it possible to prevent an optical signal with a wavelength different from the originally assigned wavelength from being forwarded to the WXC unit 13-1.

[0035] The control unit 20-2 controls the optical node device 10-2 and the subscriber device 40. Here, the control of the optical node device 10-2 includes, for example, connection settings between the ports of the optical distribution units 11-2, 12-2 and the WXC unit 13-2 (for example, setting a forwarding path). The control of the subscriber device 40 includes, for example, when the subscriber device 40 is newly connected to the optical node device 10-2, processing such as authentication and registration with the new subscriber device 40, allocation of an emission wavelength to the subscriber device 40 (including, for example, subscriber devices 40 already connected to the optical node device 10-2 and new subscriber devices), and instructions to stop light and change wavelength.

[0036] The control unit 20-2 includes a subscriber device management control unit 21-2 and a node control unit 22-2. The subscriber device management control unit 21-2 performs the above-described control on subscriber devices 40 connected to the optical node device 10-2 (including, for example, subscriber devices 40 already connected to the optical node device 10-2 and new subscriber devices). Furthermore, if the determination result output from the optical distribution unit 11 indicates an abnormality, the subscriber device management control unit 21-2 may again instruct the new subscriber device to emit light at a wavelength, or may assign a wavelength different from the assigned wavelength that is not being used for communication.

[0037] The node control unit 22-2 performs routing control in the optical node device 10-2 so that the subscriber device 40 can communicate with the subscriber device with which it is to communicate. For a new subscriber device, the node control unit 22-2 sets up an inter-port connection within the optical distribution unit 11 so that an optical signal output from the new subscriber device is transferred to an unused port.

[0038] If the determination result output from the optical distribution unit 11 indicates normality, the node control unit 22-2 sets the internal port connections of the optical distribution unit 11 so that the optical signal transmitted from the new subscriber device is output to the WXC unit 13-2, which outputs the optical signal to the route assigned to the newly opened optical path. Furthermore, the node control unit 22-1 performs internal forwarding settings of the WXC unit 13-2. For example, the node control unit 22-2 performs route control in the optical node device 10-2 so that the new subscriber device can communicate with the subscriber device with which it will communicate. This allows an optical path to be opened so that the optical signal transmitted from the new subscriber device is forwarded to the subscriber device with which it will communicate.

[0039] On the other hand, if the determination result output from the optical distribution unit 11-2 indicates an abnormality, the node control unit 22-2 sets the port connections of the optical distribution unit 11-2 so that the optical signal transmitted from the new subscriber device is not output to the WXC unit 13-2. For example, the node control unit 22-2 maintains the port connections of the optical distribution unit 11-2 so that the optical signal transmitted from the new subscriber device continues to be forwarded to unused ports. In this way, the node control unit 22-2 controls the optical signal transmitted from the new subscriber device so that it does not affect the communications of other subscriber devices to which optical paths are already open until the set wavelength of the new subscriber device is set to a normal wavelength. This makes it possible to prevent an optical signal with a wavelength different from the originally assigned wavelength from being forwarded to the WXC unit 13-2.

[0040] The subscriber device 30 is equipped with an optical transceiver. The optical transceiver is, for example, a coherent transceiver. The subscriber device 30 transmits and receives optical signals such as main signals and control signals using the optical transceiver. When a subscriber device 30 before an optical path is opened is newly connected to the optical communication system 100, it exchanges information necessary for registration, authentication, and optical path opening with the control unit 20-1. The information necessary for optical path opening includes, for example, information on the wavelength used for transmission and reception, and information on the subscriber device with which communication is to be performed.

[0041] The subscriber device 30 outputs an upstream control signal light to the control unit 20-1 as an optical signal with a wavelength different from that of the main signal light. The subscriber device 30 is, for example, an ONU (Optical Network Unit) installed in a subscriber's home.

[0042] The subscriber device 40 includes an optical transceiver. The optical transceiver is, for example, a coherent transceiver. The subscriber device 40 transmits and receives optical signals such as main signals and control signals using the optical transceiver. When a subscriber device 40 before an optical path is opened is newly connected to the optical communication system 100, it exchanges information necessary for registration, authentication, and optical path opening with the control unit 20-2.

[0043] The subscriber device 40 outputs an upstream control signal light to the control unit 20-2 as an optical signal with a wavelength different from that of the main signal light. The subscriber device 40 is, for example, an ONU installed in a subscriber's home.

[0044] Next, the configuration of the optical distribution unit 11 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the optical distribution unit 11 in the first embodiment. The optical distribution unit 11 includes N (N is an integer of 2 or more) subscriber device side ports 111, M (M is an integer of 2 or more) trunk NW side ports 112, N optical detection units 113, N 1xM optical switches 114, M 1xN WSSs 115, M optical detection units 116, and a control unit 117.

[0045] A subscriber device 30 is connected to each subscriber device side port 111 via an optical transmission path L. The subscriber device side port 111 accepts input of an optical signal transmitted from the subscriber device 30. The optical signal input to the subscriber device side port 111 is output to the 1×M optical switch 114 via an optical detection unit 113. The subscriber device side port 111 also accepts input of an optical signal output from the 1×M optical switch 114. The optical signal input to the subscriber device side port 111 is output to the subscriber device 30 connected via the optical transmission path L. The subscriber device side port 111 is one aspect of a plurality of first ports.

[0046] At least one port of the M backbone network side ports 112 is used for detecting an optical signal transmitted by a new subscriber device. The WXC unit 13 is connected to at least some of the backbone network side ports 112 (excluding the port used for detection described above). An optical signal input to the backbone network side port 112 is output to the WXC unit 13 or not output anywhere. As described above, the optical distribution unit 11 sets a detection optical path between an unused backbone network side port 112 and a subscriber device side port 111 to which a new subscriber device is connected, in response to an instruction from the control unit 20. Therefore, since the unused backbone network side port 112 is not connected anywhere, an optical signal input to the unused backbone network side port 112 is not output anywhere. Furthermore, the backbone network side port 112 accepts input of an optical signal output from the WXC unit 13. The optical signal input to the optical detection unit 113 is output to one of the 1×M optical switches 114. The trunk NW side port 112 is one aspect of a plurality of second ports.

[0047] The optical detector 113 detects the optical signal output from the subscriber device port 111 and measures the power of the detected optical signal. The optical detector 113 outputs information indicating the measured optical signal power to the controller 117. The optical detector 113 may be provided on the path between the subscriber device port 111 and the 1×M optical switch 114, or may be provided inside the 1×M optical switch 114. The optical detector 113 is one aspect of the first measuring unit.

[0048] The 1xM optical switch 114 has one first port and M second ports. The subscriber device side port 111 is connected to the first port of the 1xM optical switch 114 via the optical detection unit 113. M 1xN WSSs 115 are connected to the second port of the 1xM optical switch 114. The 1xM optical switch 114 switches the connection between the first port and any of the second ports in response to instructions from the control unit 117. This allows the 1xM optical switch 114 to output an optical signal to a specific output destination. By setting the connection between the first port and the second port, the 1xM optical switch 114 outputs an input optical signal from another port regardless of wavelength. The 1xM optical switch 114 is one aspect of one or more first distribution units.

[0049] The 1xN WSS 115 has one first port and N second ports. The 1xN WSS 115 has a wavelength selectivity function. Having wavelength selectivity means having the ability to select a specific wavelength and output it from any output destination. The first port of the 1xN WSS 115 is connected to a relay network side port 112 via an optical detection unit 116. N 1xM optical switches 114 are connected to the second port of the 1xN WSS 115. The 1xN WSS 115 outputs an optical signal of a specific wavelength to any output destination in response to an instruction from the control unit 117. For example, the 1xN WSS 115 outputs an optical signal of a wavelength assigned to a new subscriber device to an unused relay network side port 112. The 1xN WSS 115 is one aspect of one or more second distribution units.

[0050] The optical detection unit 116 detects the optical signal output from the 1×N WSS 115 and measures the power of the detected optical signal. The optical detection unit 116 outputs information indicating the power of the measured optical signal to the control unit 117. The optical detection unit 116 may be provided on the path between the relay NW side port 112 and the 1×N WSS 115, or may be provided inside the 1×N WSS 115. The optical detection unit 116 is one aspect of a second measurement unit.

[0051] As described above, in the upstream direction, optical signals input from multiple subscriber devices 30 or 40 are forwarded to the destination path by the 1×M optical switch 114, and the optical signals of the same path are wavelength-multiplexed and output for each path by the 1×N WSS 115. Furthermore, the 1×M optical switch 114 and the 1×N WSS 115 are configured to set up detection optical paths from each subscriber device side port 111 to an unused port among the relay network side ports 112. In the downstream direction, wavelength-multiplexed optical signals input from multiple paths are output to each subscriber device 30, 40 by the optical detector 116 and the 1×N WSS 115.

[0052] In response to an instruction from the control unit 20, the control unit 117 sets up a detection optical path between the subscriber device-side port 111 to which the new subscriber device is connected and the unused backbone network-side port 112. Furthermore, the control unit 117 controls the connection between the ports of the 1×M optical switch 114 and the 1×N WSS 115. For example, the control unit 117 controls the 1×M optical switch 114 and the 1×N WSS 115 so that an optical signal input to the subscriber device-side port 111 to which the new subscriber device is connected is directed to the unused backbone network-side port 112. The control unit 117 controls the 1×M optical switch 114 so as to connect the 1×N WSS 115 connected to the unused backbone network-side port 112 to the subscriber device-side port 111 to which the new subscriber device is connected. Furthermore, the control unit 117 controls the 1×M optical switch 114 connected to the unused repeater NW port 112 so that the wavelength assigned to the new subscriber device is output to the unused repeater NW port 112. In this way, the control unit 117 controls the 1×M optical switch 114 and the 1×N WSS 115 so that the optical signal input to the subscriber device port 111 to which the new subscriber device is connected is directed to the unused repeater NW port 112.

[0053] In this case, the control unit 117 needs to know the wavelength assigned to the new subscriber device in order to transfer the optical signal of the wavelength assigned to the new subscriber device to the unused backbone NW side port 112 in the 1×N WSS 115. Therefore, the control unit 20 transmits information indicating the wavelength assigned to the new subscriber device to the optical node device 10 at the timing of transmitting the switching instruction. This allows the control unit 117 to know the wavelength assigned to the new subscriber device. Figure 2 shows an example in which the 1×M optical switch 114 and the 1×N WSS 115 are controlled so that the optical signal input to the subscriber device side port 111-N is directed to the backbone NW side port 112-M.

[0054] Furthermore, the control unit 117 determines whether the wavelength set by the new subscriber device is normal or not based on the information indicating the power of the optical signal notified by each of the optical detection units 113 and 116. If the control unit 117 determines that the wavelength set by the new subscriber device is normal, it transmits a control signal indicating the determination result that the wavelength is normal to the control unit 20. If the control unit 117 determines that the wavelength set by the new subscriber device is abnormal, it transmits a control signal indicating the determination result that the wavelength is abnormal to the control unit 20.

[0055] Here, the determination method performed by the control unit 117 will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining a method for determining whether the wavelength set by a new subscriber device is normal. In the example shown in Fig. 3, the subscriber device 30-2 is the new subscriber device, and the determination is made based on the optical signal transmitted from the subscriber device 30-2. For example, Fig. 3 shows an example in which a detection optical path is set between the subscriber device side port 111-2 and the 1xN WSS 115-M.

[0056] By setting the detection optical path to pass only the wavelength set for the subscriber device 30, the amount of attenuation of the optical signal in the 1×N WSS 115 increases as the amount by which the optical signal from the subscriber device 30 deviates from the set wavelength increases. Therefore, if both the optical signal power measured by the optical detector 113 and the optical signal power measured by the optical detector 116 are equal to or greater than a threshold, the control unit 117 determines that there is no abnormality in the wavelength of the optical signal transmitted from the new subscriber device (i.e., the wavelength set by the new subscriber device is not abnormal). On the other hand, if at least one of the optical signal power measured by the optical detector 113 or the optical signal power measured by the optical detector 116 is less than the threshold, the control unit 117 determines that there is an abnormality in the wavelength of the optical signal transmitted from the new subscriber device (i.e., the wavelength set by the new subscriber device is abnormal).

[0057] (Flow of optical path opening process in optical communication system 100) Fig. 4 is a sequence diagram showing the flow of optical path opening process in the optical communication system 100 in the first embodiment. In Fig. 4, the new subscriber device is subscriber device 30-2, and in a state where an optical path is opened for subscriber device 30-1 to connect with subscriber device 40-1, which will be the communication partner, via the optical transmission line L and the optical node device 10, subscriber device 30-2 opens an optical path for connecting with subscriber device 40-2, which will be the communication partner.

[0058] Assume that a user connects subscriber device 30-2 to the optical node device 10-1 via the optical transmission path L. As a result, subscriber device 30-2 is connected to the optical node device 10-1 via the optical transmission path L (step S101). Subscriber device 30-2 generates an upstream control signal including instructions requesting authentication, registration, etc. Subscriber device 30-2 converts the generated upstream control signal into an optical signal and transmits it as upstream control signal light. The upstream control signal light transmitted from subscriber device 30-2 is forwarded to the control unit 20 by the optical node device 10-1. When connecting a new subscriber device, an existing method may be used to forward the optical signal transmitted from the new subscriber device to the control unit 20.

[0059] The subscriber device management control unit 21-1 of the control unit 20-1 exchanges control signal light with the subscriber device 30-2, including information necessary for authentication, registration, and optical path opening (step S102). As a result, the subscriber device management control unit 21-1 recognizes the new subscriber device and instructs the subscriber device 30-2, the recognized new subscriber device, to allocate and set an emission wavelength so that the wavelength does not overlap with other optical paths on the transmission route. The subscriber device management control unit 21-1 transmits an optical signal including an emission wavelength allocation and setting instruction to the subscriber device 30-2 via the optical node device 10-1.

[0060] The node control unit 22-1 sets up an internal port connection within the optical distribution unit 11-1 so that the optical signal output from the subscriber device 30-2 is forwarded to the unused relay NW port 112 (step S103). Specifically, the node control unit 22-1 generates a switching instruction for the 1×M optical switch 114-2 and the 1×N WSS 115-M so that the subscriber device port 111-2 to which the subscriber device 30-2 is connected is connected to an unused relay NW port 112 (e.g., relay NW port 112-M) among the multiple subscriber device ports 111 included in the optical distribution unit 11-1, and generates a control signal including the generated switching instruction. Note that the node control unit 22-1 may include information indicating the wavelength assigned to the new subscriber device in the control signal. The node control unit 22-1 transmits the generated control signal to the optical node device 10-1 via an electrical line (not shown) (step S104).

[0061] The optical node device 10-1 receives the control signal transmitted from the control unit 20-1. The control unit 117 controls the transfer paths of the 1×M optical switch 114-2 and the 1×N WSS 115-M in accordance with the switching instruction contained in the received control signal (step S105). Furthermore, the control unit 117 sets a detection optical path for the subscriber device side port 111-2 and the relay NW side port 112-M.

[0062] The subscriber device 30-2 receives the optical signal including the emission wavelength allocation and setting instruction transmitted from the control unit 20-1. The subscriber device 30-2 sets the wavelength specified by the emission wavelength allocation contained in the received optical signal. The subscriber device 30-2 transmits an optical signal of the set wavelength (step S106). If the subscriber device 30-2 does not have a failure or malfunction, or if the subscriber has intentionally set an incorrect wavelength, the optical signal of the set wavelength is transmitted. On the other hand, if the subscriber device 30-2 has a failure or malfunction, or if the subscriber has intentionally set an incorrect wavelength, the set wavelength λ ２ In some cases, optical signals having wavelengths different from those of the optical signals transmitted.

[0063] The optical signal transmitted from the subscriber device 30-2 is input to the subscriber device-side port 111-2 of the optical distribution unit 11-1 via the optical transmission line L. The optical signal input to the subscriber device-side port 111-2 is input to the 1×M optical switch 114-2 via the optical detection unit 113-2. At this time, the optical detection unit 113-2 measures the power of the optical signal input to the subscriber device-side port 111-2 (step S107). The optical detection unit 113-2 outputs information including the measurement result of the optical signal power and identification information of the optical detection unit 113-2 to the control unit 117.

[0064] In step S105, 1×M optical switch 114-2 performs port connection control so that the first port is connected to the second port to which 1×N WSS 115-M is connected. Therefore, the optical signal input to 1×M optical switch 114-2 is output to 1×N WSS 115-M. 1×N WSS 115-M accepts the input of the optical signal output from 1×M optical switch 114-2.

[0065] The optical signal input to the second port of the 1×N WSS 115-M is output from the first port. The optical signal output from the first port of the 1×N WSS 115-M is input to the relay NW side port 112-M via the optical detection unit 116-M. At this time, the optical detection unit 116-M measures the power of the optical signal output from the first port of the 1×N WSS 115-M (step S107). The optical detection unit 116-M outputs information including the measurement result of the optical signal power and identification information of the optical detection unit 116-M to the control unit 117.

[0066] The control unit 117 determines whether the wavelength set by the subscriber unit 30-2 is abnormal based on the information output from the optical detection unit 113-2 and the information output from the optical detection unit 116-M (step S108). The determination made by the control unit 117 is as described in FIG. 3. If the wavelength set by the subscriber unit 30-2 is normal, the control unit 117 generates a control signal including a determination result indicating "normal." If the wavelength set by the subscriber unit 30-2 is abnormal, the control unit 117 generates a control signal including a determination result indicating "abnormal." The control unit 117 transmits the generated control signal to the control unit 20-2 via an electric line (not shown) (step S109).

[0067] The node control unit 22-1 of the control unit 20-1 receives the control signal transmitted from the optical node device 10-1. The node control unit 22-1 performs control according to the determination result contained in the received control signal (step S110). Specifically, if the determination result contained in the control signal indicates normal, the node control unit 22-1 sets the internal port connections of the optical distribution unit 12 so that the optical signal transmitted from the subscriber device 30-2 is output to the WXC unit 13, which outputs the optical signal to the route assigned to the newly opened optical path. Furthermore, the node control unit 22-1 performs internal forwarding settings of the WXC unit 13-1. This allows the optical path to be opened so that the optical signal transmitted from the subscriber device 30-2 is forwarded to the subscriber device with which it is communicating.

[0068] On the other hand, if the determination result included in the control signal indicates an abnormality, the node control unit 22-1 sets the port connection of the optical distribution unit 11-1 so that the optical signal output from the subscriber device 30-2 is not output to any of the optical distribution units 12. For example, the node control unit 22-1 maintains the port connection so that the optical signal output from the subscriber device 30-2 continues to be forwarded to the relay NW side port 112-M (unused port), or performs control such as not internally connecting the port to which the subscriber device 30-2 is connected to any other port. Furthermore, the subscriber device management and control unit 21-1 again instructs the subscriber device 30-2 to change the emission wavelength. Note that when re-setting the emission wavelength, the subscriber device management and control unit 21-1 may instruct the subscriber device 30-2 to set a wavelength different from the previous one.

[0069] According to the optical communication system 100 configured as described above, the optical node device 10 includes an optical distribution unit 11 that distributes input optical signals and a WXC unit 13 that connects to two or more routes. The optical distribution unit 11 includes a plurality of subscriber device-side ports 111 to which a plurality of subscriber devices 30, 40 are connected, a plurality of backbone NW-side ports 112 that are connected to the WXC unit 13, and a control unit 117 that sets a detection optical path between the subscriber device-side port 111 to which the new subscriber device is connected and an unused backbone NW-side port 112 among the plurality of backbone NW-side ports 112, and determines whether the wavelength of the optical signal transmitted from the new subscriber device is abnormal based on the power of the optical signal at the subscriber device-side port 111 to which the detection optical path is set and the unused backbone NW-side port 112.

[0070] This allows the optical node device 10 to detect an abnormality in the transmission wavelength of a new subscriber device when an optical path is opened, and as a result, it is possible to identify that the reason the optical path cannot be opened is that the wavelength of the optical signal transmitted by the new subscriber device is different from the specified wavelength.

[0071] Furthermore, in the optical communication system 100, it is possible to identify that the cause of the inability to open an optical path is a new subscriber device, and therefore it is possible to control the correction of the emission wavelength of the new subscriber device, thereby improving the problem of opening an optical path caused by a new subscriber device.

[0072] (Modification) Note that the optical distribution unit 11 may be configured with 1×N couplers that do not have wavelength selectivity, instead of the 1×N WSS 11, for the unused relay NW side ports 112 out of the multiple relay NW side ports 112.

[0073] Second Embodiment In the second embodiment, an embodiment having a different configuration from the light distribution unit shown in the first embodiment will be described. Note that in the second embodiment, the system configuration and the configuration other than the light distribution unit are the same as those in the first embodiment. The following description will focus on the differences from the first embodiment.

[0074] 5 is a diagram illustrating an example of the configuration of the optical distribution unit 11a according to the second embodiment. The optical distribution unit 11a includes N subscriber device-side ports 111, N relay network-side ports 112, N optical detection units 113, two 1×N WSSs 118-1 to 118-2, N optical detection units 116, and a control unit 117.

[0075] The 1xN WSS 118-1 has N first ports and one second port. The 1xN WSS 118-1 has a wavelength selectivity function. The N second ports of the 1xN WSS 118-1 are each connected to a subscriber device side port 111 via an optical detection unit 113. The 1xN WSS 118-1's first port is connected to the 1xN WSS 118-2. In response to instructions from the control unit 117, the 1xN WSS 118-1 wavelength-multiplexes an optical signal input from the first port and outputs the multiplexed signal from the second port. The 1xN WSS 118-1 is one aspect of one or more first distribution units.

[0076] The 1xN WSS 118-2 has N first ports and one second port. The 1xN WSS 118-2 has a wavelength selectivity function. The N second ports of the 1xN WSS 118-2 are each connected to a relay network side port 112 via an optical detection unit 116. The 1xN WSS 118-1 is connected to the first port of the 1xN WSS 118-2. The 1xN WSS 118-2 outputs an optical signal of a specific wavelength to an arbitrary output destination in response to an instruction from the control unit 117. For example, the 1xN WSS 118-2 outputs an optical signal of a wavelength assigned to a new subscriber device to an unused relay network side port 112. The 1xN WSS 118-2 is one aspect of one or more second distribution units.

[0077] In the upstream direction, optical signals input from multiple subscriber devices 30 and 40 are wavelength-multiplexed in the 1×N WSS 118-1, and optical signals are output for each path in the 1×N WSS 118-2. Furthermore, the two 1×N WSSs 118-1 and 118-2 are configured to establish detection optical paths from the respective subscriber device side ports 111 to the relay network side ports 112.

[0078] In response to an instruction from the control unit 20, the control unit 117 sets up a detection optical path between the subscriber device-side port 111 to which the new subscriber device is connected and the unused backbone network-side port 112. Furthermore, the control unit 117 controls the connections between the ports of the 1×N WSSs 118-1 to 118-2. For example, in response to an instruction from the control unit 20, the control unit 117 controls the 1×N WSSs 118-1 to 118-2 so that an optical signal input to the subscriber device-side port 111 to which the new subscriber device is connected is directed to the unused backbone network-side port 112. The control unit 117 controls the 1×N WSS 118-1 so as to connect the 1×N WSS 118-2 connected to the unused backbone network-side port 112 to the subscriber device-side port 111 to which the new subscriber device is connected. Furthermore, the control unit 117 controls the 1×N WSS 118-2 connected to the unused repeater NW port 112 so that the wavelength assigned to the new subscriber device is output to the unused repeater NW port 112. In this way, the control unit 117 controls the 1×N WSS 118-1 and the 1×N WSS 118-2 so that the optical signal input to the subscriber device port 111 to which the new subscriber device is connected is directed to the unused repeater NW port 112.

[0079] In this case, the control unit 117 needs to know the wavelength assigned to the new subscriber device in order to have the 1×N WSS 118-2 transfer the optical signal of the wavelength assigned to the new subscriber device to the unused backbone NW side port 112. Therefore, the control unit 20 transmits information indicating the wavelength assigned to the new subscriber device to the optical node device 10 at the timing of transmitting the switching instruction. This allows the control unit 117 to know the wavelength assigned to the new subscriber device. The control unit 117 controls the 1×N WSS 118-2 so that the optical signal of the wavelength assigned to the new subscriber device is transferred to the unused backbone NW side port 112.

[0080] Furthermore, the control unit 117 determines whether the wavelength set by the new subscriber device is normal or not based on the information indicating the power of the optical signal notified by each of the optical detection units 113 and 116. If the control unit 117 determines that the wavelength set by the new subscriber device is normal, it transmits a control signal indicating the determination result that the wavelength is normal to the control unit 20. If the control unit 117 determines that the wavelength set by the new subscriber device is abnormal, it transmits a control signal indicating the determination result that the wavelength is abnormal to the control unit 20.

[0081] (Flow of optical path opening process in the optical communication system 100 in the second embodiment) Next, a flow of optical path opening process in the optical communication system 100 in the second embodiment will be described. Here, the description will be made assuming that the new subscriber device is the subscriber device 30-2, and that the subscriber device 30-1 has an opened optical path to connect to the subscriber device 40-1, which will be the communication partner, via the optical transmission line L and the optical node device 10, and that the subscriber device 30-2 opens an optical path to connect to the subscriber device 40-2, which will be the communication partner.

[0082] Assume that a user connects subscriber device 30-2 to the optical node device 10-1 via the optical transmission path L. As a result, subscriber device 30-2 is connected to the optical node device 10-1 via the optical transmission path L. Subscriber device 30-2 generates an upstream control signal including instructions requesting authentication, registration, etc. Subscriber device 30-2 converts the generated upstream control signal into an optical signal and transmits it as upstream control signal light. The upstream control signal light transmitted from subscriber device 30-2 is forwarded to the control unit 20 by the optical node device 10-1. When connecting a new subscriber device, an existing method may be used to forward the optical signal transmitted from the new subscriber device to the control unit 20.

[0083] The subscriber device management control unit 21-1 of the control unit 20-1 exchanges control signal light with the subscriber device 30-2, including information necessary for authentication, registration, and optical path opening. This allows the subscriber device management control unit 21-1 to recognize a new subscriber device, and instructs the subscriber device 30-2, the recognized new subscriber device, to allocate and set an emission wavelength so that the wavelength does not overlap with other optical paths along the transmission route. The subscriber device management control unit 21-1 transmits an optical signal including an emission wavelength allocation and setting instruction to the subscriber device 30-2 via the optical node device 10-1.

[0084] The node control unit 22-1 sets up a connection between ports within the optical distribution unit 11a-1 so that the optical signal output from the subscriber device 30-2 is forwarded to the unused relay NW-side port 112. Specifically, the node control unit 22-1 generates a switching instruction for the 1×N WSS 118-1 and the 1×N WSS 118-2 so that the subscriber device-side port 111-2 to which the subscriber device 30-2 is connected and the unused relay NW-side port 112 (e.g., relay NW-side port 112-N) are connected, among the multiple subscriber device-side ports 111 included in the optical distribution unit 11a-1, and generates a control signal including the generated switching instruction. Note that the node control unit 22-1 may include information indicating the wavelength assigned to the new subscriber device in the control signal. The node control unit 22-1 transmits the generated control signal to the optical node device 10-1 via an electrical line (not shown).

[0085] The optical node device 10-1 receives the control signal transmitted from the control unit 20-1. The control unit 117 controls the forwarding paths of the 1×N WSS 118-1 and the 1×N WSS 118-2 in accordance with the switching instruction contained in the received control signal. Furthermore, the control unit 117 sets a detection optical path for the subscriber device side port 111-2 and the trunk NW side port 112-N.

[0086] The subscriber device 30-2 receives the optical signal including the emission wavelength assignment and setting instruction transmitted from the control unit 20-1. The subscriber device 30-2 sets the wavelength specified by the emission wavelength assignment contained in the received optical signal. The subscriber device 30-2 transmits the optical signal with the set wavelength.

[0087] The optical signal transmitted from the subscriber device 30-2 is input to the subscriber device-side port 111-2 of the optical distribution unit 11a-1 via the optical transmission line L. The optical signal input to the subscriber device-side port 111-2 is input to the 1×N WSS 118-1 via the optical detection unit 113-2. At this time, the optical detection unit 113-2 measures the power of the optical signal input to the subscriber device-side port 111-2. The optical detection unit 113-2 outputs information including the measurement result of the optical signal power and identification information of the optical detection unit 113-2 to the control unit 117.

[0088] The 1xN WSS 118-1 wavelength-multiplexes optical signals input to its first port and outputs the multiplexed signal from its second port. The multiplexed signal output from the second port of the 1xN WSS 118-1 is input to the 1xN WSS 118-2. The multiplexed signal input to the second port of the 1xN WSS 118-2 is output from a specific first port according to the wavelength. For example, the 1xN WSS 118-2 is configured to output the wavelength assigned to the new subscriber device by the control unit 117 from the first port connected to the intermediate network side port 112-N, which is an unused intermediate network side port 112. Therefore, the 1xN WSS 118-2 outputs the optical signal of the wavelength assigned to the new subscriber device from the first port connected to the intermediate network side port 112-N, out of the optical signals included in the multiplexed signal input to the second port of the 1xN WSS 118-2.

[0089] The optical signal output from the first port of the 1×N WSS 118-2 is input to the relay NW side port 112-N via the optical detection unit 116-N. At this time, the optical detection unit 116-N measures the power of the optical signal output from the second port of the 1×N WSS 118-2. The optical detection unit 116-N outputs information including the measurement result of the optical signal power and identification information of the optical detection unit 116-N to the control unit 117.

[0090] The control unit 117 determines whether the wavelength set by the subscriber unit 30-2 is abnormal based on the information output from the optical detection unit 113-2 and the information output from the optical detection unit 116-N. If the wavelength set by the subscriber unit 30-2 is normal, the control unit 117 generates a control signal including a determination result indicating normality, and if the wavelength set by the subscriber unit 30-2 is abnormal, the control unit 117 generates a control signal including a determination result indicating abnormality. The control unit 117 transmits the generated control signal to the control unit 20-2 via an electrical line (not shown). Thereafter, the same processing as in the first embodiment is performed.

[0091] According to the optical communication system 100 of the second embodiment configured as described above, the same effects as those of the first embodiment can be obtained even in a configuration in which the light distribution unit 11 includes two 1×N WSSs 118-1 to 118-2.

[0092] (Third Embodiment) In the third embodiment, an embodiment having a different configuration from the light distribution unit shown in the first and second embodiments will be described. Note that in the third embodiment, the system configuration and the configuration other than the light distribution unit are the same as those of the first and second embodiments. The following description will focus on the differences from the first and second embodiments.

[0093] 6 is a diagram illustrating an example of the configuration of the optical distribution unit 11b according to the third embodiment. The optical distribution unit 11b includes N subscriber device-side ports 111, M relay network-side ports 112, N optical detection units 113, M optical detection units 116, a control unit 117, a large-scale optical switch 119, and M AWGs 120.

[0094] The large-scale optical switch 119 has N first ports and (number of wavelengths × M) second ports. Here, the number of wavelengths is, for example, the number of wavelengths available to both the subscriber devices 30 and 40. The first ports of the large-scale optical switch 119 are each connected to a subscriber device-side port 111 via an optical detection unit 113. The second ports of the large-scale optical switch 119 are each connected to an AWG 120. For example, one second port of the large-scale optical switch 119 is connected to one AWG 120 by optical wiring equal to the number of wavelengths. The large-scale optical switch 119 switches the connections between the ports in response to instructions from the control unit 117. The large-scale optical switch 119 is one aspect of one or more first distribution units.

[0095] The AWG 120 is a device that multiplexes or demultiplexes wavelengths. The AWG 120 has first ports, the number of which corresponds to the number of wavelengths, and one second port. The AWG 120 has a wavelength selectivity function. A large-scale optical switch 119 is connected to each first port of the AWG 120. A relay NW side port 112 is connected to the second port of the AWG 120 via an optical detection unit 116. The AWG 120 is one aspect of one or more second distribution units.

[0096] In the upstream direction, optical signals input from multiple subscriber devices 30, 40 are forwarded to the destination route by the large-scale optical switch 119, and the optical signals for the same route are wavelength-multiplexed and output for each route by the AWG 120. Furthermore, the large-scale optical switch 119 and the AWG 120 are set up so that detection optical paths can be set up from the respective subscriber device side ports 111 to the relay network side ports 112.

[0097] In response to an instruction from the control unit 20, the control unit 117 sets up a detection optical path between the subscriber device-side port 111 to which the new subscriber device is connected and the unused backbone network-side port 112. Furthermore, the control unit 117 controls the connection between ports in the large-scale optical switch 119. For example, in response to an instruction from the control unit 20, the control unit 117 controls the large-scale optical switch 119 so that an optical signal input to the subscriber device-side port 111 to which the new subscriber device is connected is directed to the unused backbone network-side port 112.

[0098] In this case, the control unit 117 needs to know the wavelength assigned to the new subscriber device in order to cause the large scale optical switch 119 to transfer an optical signal of the wavelength assigned to the new subscriber device to an unused backbone network side port 112. Therefore, the control unit 20 transmits information indicating the wavelength assigned to the new subscriber device to the optical node device 10 at the timing of transmitting the switching instruction. This allows the control unit 117 to know the wavelength assigned to the new subscriber device. The control unit 117 controls the large scale optical switch 119 so that the optical signal of the wavelength assigned to the new subscriber device is transferred to the unused backbone network side port 112. The control unit 117 sets up a detection optical path between the subscriber device side port 111 to which the new subscriber device is connected and the unused backbone network side port 112.

[0099] Furthermore, the control unit 117 determines whether the wavelength set by the new subscriber device is normal or not based on the information indicating the power of the optical signal notified by each of the optical detection units 113 and 116. If the control unit 117 determines that the wavelength set by the new subscriber device is normal, it transmits a control signal indicating the determination result that the wavelength is normal to the control unit 20. If the control unit 117 determines that the wavelength set by the new subscriber device is abnormal, it transmits a control signal indicating the determination result that the wavelength is abnormal to the control unit 20.

[0100] (Flow of optical path opening process in the optical communication system 100 in the third embodiment) Next, a flow of optical path opening process in the optical communication system 100 in the third embodiment will be described. Here, the description will be made assuming that the new subscriber device is the subscriber device 30-2, and that the subscriber device 30-1 has an opened optical path to connect to the subscriber device 40-1, which will be the communication partner, via the optical transmission line L and the optical node device 10, and that the subscriber device 30-2 opens an optical path to connect to the subscriber device 40-2, which will be the communication partner.

[0101] Assume that a user connects subscriber device 30-2 to the optical node device 10-1 via the optical transmission path L. As a result, subscriber device 30-2 is connected to the optical node device 10-1 via the optical transmission path L. Subscriber device 30-2 generates an upstream control signal including instructions requesting authentication, registration, etc. Subscriber device 30-2 converts the generated upstream control signal into an optical signal and transmits it as upstream control signal light. The upstream control signal light transmitted from subscriber device 30-2 is forwarded to the control unit 20 by the optical node device 10-1. When connecting a new subscriber device, an existing method may be used to forward the optical signal transmitted from the new subscriber device to the control unit 20.

[0102] The subscriber device management control unit 21-1 of the control unit 20-1 exchanges control signal light with the subscriber device 30-2, including information necessary for authentication, registration, and optical path opening. This allows the subscriber device management control unit 21-1 to recognize a new subscriber device, and instructs the subscriber device 30-2, the recognized new subscriber device, to allocate and set an emission wavelength so that the wavelength does not overlap with other optical paths along the transmission route. The subscriber device management control unit 21-1 transmits an optical signal including an emission wavelength allocation and setting instruction to the subscriber device 30-2 via the optical node device 10-1.

[0103] The node control unit 22-1 sets up a connection between ports within the optical distribution unit 11b-1 so that the optical signal output from the subscriber device 30-2 is forwarded to the unused relay NW-side port 112. Specifically, the node control unit 22-1 generates a switching instruction for the large-scale optical switch 119 so that the subscriber device-side port 111-2 to which the subscriber device 30-2 is connected and an unused relay NW-side port 112 (e.g., relay NW-side port 112-M) are connected, among the multiple subscriber device-side ports 111 included in the optical distribution unit 11b-1, and generates a control signal including the generated switching instruction. Note that the node control unit 22-1 may include information indicating the wavelength assigned to the new subscriber device in the control signal. The node control unit 22-1 transmits the generated control signal to the optical node device 10-1 via an electrical line (not shown).

[0104] The optical node device 10-1 receives a control signal transmitted from the control unit 20-1. The control unit 117 controls the transfer path of the large-scale optical switch 119 in accordance with the switching instruction included in the received control signal. Specifically, the control unit 117 controls the large-scale optical switch 119 to connect a first port connected to the subscriber device-side port 111-2 and a second port connected to the relay NW-side port 112-M. Note that in the large-scale optical switch 119, there are as many second ports connected to the relay NW-side port 112-M as there are wavelengths. Therefore, based on information indicating the wavelength assigned to the subscriber device 30-2 by the control unit 20-1, the control unit 117 controls the large-scale optical switch 119 to connect the second port corresponding to the wavelength assigned to the subscriber device 30-2 and the first port connected to the subscriber device-side port 111-2. Furthermore, the control unit 117 sets a detection optical path for the subscriber device-side port 111-2 and the relay NW-side port 112-M.

[0105] The subscriber device 30-2 receives the optical signal including the emission wavelength assignment and setting instruction transmitted from the control unit 20-1. The subscriber device 30-2 sets the wavelength specified by the emission wavelength assignment contained in the received optical signal. The subscriber device 30-2 transmits the optical signal with the set wavelength.

[0106] The optical signal transmitted from the subscriber device 30-2 is input to the subscriber device-side port 111-2 of the optical distribution unit 11b-1 via the optical transmission line L. The optical signal input to the subscriber device-side port 111-2 is input to the large scale optical switch 119 via the optical detection unit 113-2. At this time, the optical detection unit 113-2 measures the power of the optical signal input to the subscriber device-side port 111-2. The optical detection unit 113-2 outputs information including the measurement result of the optical signal power and identification information of the optical detection unit 113-2 to the control unit 117.

[0107] The large-scale optical switch 119 outputs the optical signal input to the first port from the second port to which the relay NW side port 119-M is connected. The AWG 120-M wavelength-multiplexes the optical signal output from the large-scale optical switch 119 and outputs it to the relay NW side port 112-M. Note that here, control is performed so that only the optical signal transmitted from the subscriber device 30-2 is forwarded to the AWG 120-M. Therefore, the AWG 120-M outputs the optical signal output from the large-scale optical switch 119 (the optical signal transmitted from the subscriber device 30-2) to the relay NW side port 112-M.

[0108] The optical signal output from the AWG 120-M is input to the relay NW side port 112-M via the optical detection unit 116-M. At this time, the optical detection unit 116-M measures the power of the optical signal output from the AWG 120-M. The optical detection unit 116-M outputs information including the measurement result of the power of the optical signal and identification information of the optical detection unit 116-M to the control unit 117.

[0109] The control unit 117 determines whether the wavelength set by the subscriber unit 30-2 is abnormal based on the information output from the optical detection unit 113-2 and the information output from the optical detection unit 116-M. If the wavelength set by the subscriber unit 30-2 is normal, the control unit 117 generates a control signal including a determination result indicating normality, and if the wavelength set by the subscriber unit 30-2 is abnormal, the control unit 117 generates a control signal including a determination result indicating abnormality. The control unit 117 transmits the generated control signal to the control unit 20-2 via an electrical line (not shown). Thereafter, the same processing as in the first embodiment is performed.

[0110] According to the optical communication system 100 of the third embodiment configured as described above, even in a configuration including the large-scale optical switch 119 and a plurality of AWGs 120, it is possible to obtain the same effects as in the first embodiment.

[0111] (Modification common to the first to third embodiments) In each of the above embodiments, the optical distribution units 11, 11a, and 11b measure the power of an optical signal at the unused backbone NW-side port 112 in which a detection optical path is set and at the subscriber device-side port 111 to which the new subscriber device is connected, and determine whether the wavelength set by the new subscriber device is normal based on the measurement results. Alternatively, the control unit 20 may be configured to determine whether the wavelength set by the new subscriber device is normal. In this configuration, the optical distribution units 11, 11a, and 11b measure the power of an optical signal at the unused backbone NW-side port 112 in which a detection optical path is set and at the subscriber device-side port 111 to which the new subscriber device is connected, and transmit the measurement results to the control unit 20. The control unit 20 determines whether the wavelength set by the new subscriber device is normal based on the measurement results transmitted from the optical distribution units 11, 11a, and 11b. The control unit 20 then performs an operation according to the determination result. Specifically, if the judgment result indicates an abnormality, the control unit 20 may again instruct the new subscriber device to emit light at a wavelength, or may assign a wavelength different from the assigned wavelength that is not being used for communication.

[0112] Some of the functional units of the control unit 20 in the above-described embodiment may be implemented by a computer. In this case, a program for implementing the functions may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed. Note that the term "computer system" here includes hardware such as an OS (Operating System) and peripheral devices.

[0113] Furthermore, "computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs (Read Only Memory), and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording media" may also include devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, or devices that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as servers or clients. Furthermore, the programs may be designed to realize some of the aforementioned functions, or may be capable of realizing the aforementioned functions in combination with programs already stored in the computer system, or may be realized using programmable logic devices such as FPGAs (Field Programmable Gate Arrays).

[0114] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0115] The present invention can be applied to a technique for opening an optical path.

[0116] 10, 10-1 to 10-2... optical node devices, 11, 11-1 to 11-2, 12, 11-2 to 12-2... optical distribution units, 13, 13-1 to 13-2... WXC units, 14, 14-1-1 to 14-1-2, 14-2-1 to 14-2-2... wavelength multiplexing units, 15, 15-1-1 to 15-1-2, 15-2-1 to 15-2-2... wavelength demultiplexing units, 20, 20-1 to 20-2... control units, 21, 21-1 to 21-2... customer device management and control units, 22, 22-1 to 22-2... node control units, 100... optical communication system, 111, 111-1 to 111-N... customer device side ports, 112, 112-1 to 112-M, 112-1 to 112-N... relay NW side ports, 113, 113-1 to 113-N, 116, 116-1 to 116-M... optical detection units, 114, 114-1 to 114-N... 1×M optical switches, 115, 118-1 to 118-2... 1×N WSS, 117... control unit, 119... large-scale optical switch, 120, 120-1 to 120-M... AWG

Claims

1. An optical node device comprising: a distribution device that distributes input optical signals; and an optical cross-connect unit that connects to two or more routes, wherein the distribution device comprises: a plurality of first ports to which a plurality of subscriber devices are connected; a plurality of second ports that connect to the optical cross-connect unit; and a control unit that sets a detection optical path between a first port among the plurality of first ports to which at least one newly connected new subscriber device is connected and an unused second port among the plurality of second ports, and determines whether the wavelength of the optical signal transmitted from the one or more new subscriber devices is abnormal based on the power of the optical signal at each of the first port to which the detection optical path is set and the unused second port.

2. The optical node device according to claim 1, further comprising: one or more first distribution units connected to at least one of the plurality of first ports to which at least one newly connected new subscriber device is connected, and which forwards optical signals transmitted from the one or more new subscriber devices to unused second ports among the plurality of second ports; and one or more second distribution units having a wavelength selectivity function and which forward the optical signals distributed by the one or more first distribution units to unused second ports.

3. An optical node device as described in claim 1 or 2, further comprising: a first measurement unit that measures the power of an optical signal input to a first port to which the one or more new subscriber devices are connected; and a second measurement unit that measures the power of an optical signal input to the unused second port, wherein the control unit determines whether or not the wavelength of the optical signal transmitted from the one or more new subscriber devices is abnormal based on the measurement results of the first measurement unit and the second measurement unit.

4. The optical node device according to claim 3, wherein the control unit determines that the wavelength of the optical signal transmitted from the one or more new subscriber devices is normal when both the power of the optical signal indicated by the measurement result of the first measurement unit and the power of the optical signal indicated by the measurement result of the second measurement unit are equal to or greater than a threshold, and determines that the wavelength of the optical signal transmitted from the one or more new subscriber devices is abnormal when either the power of the optical signal indicated by the measurement result of the first measurement unit or the power of the optical signal indicated by the measurement result of the second measurement unit is less than a threshold.

5. The distribution device comprises: as the one or more first distribution units, a combination of N 1xM optical switches connected to first ports to which the one or more new subscriber devices are connected, and outputting optical signals transmitted from the one or more new subscriber devices from one of M (M is an integer of 2 or more) routes; as the one or more second distribution units, a combination of M 1xN wavelength selective switches that input optical signals output from any of the N 1xM optical switches from any of N (N is an integer of 2 or more) routes and output them to an unused second port; as the one or more first distribution units, a single 1xN wavelength selective switch connected to N first ports and outputting optical signals transmitted from the one or more new subscriber devices from one route; as the one or more second distribution units, a combination of a single 1xN wavelength selective switch that inputs optical signals output from the single 1xN wavelength selective switch and outputs the input optical signals from a route connected to an unused second port of the N routes; or 3. The optical node device according to claim 1, wherein the one or more first distribution units are a large-scale optical switch connected to a first port to which the one or more new subscriber devices are connected, and which outputs the optical signals transmitted from the one or more new subscriber devices from one of (number of wavelengths×M) routes corresponding to the wavelengths of the optical signals transmitted by the one or more new subscriber devices; and the one or more second distribution units are a combination of M AWGs (Arrayed Waveguide Gratings) which input the optical signals output from the large-scale optical switch and output the input optical signals to an unused second port.

6. An optical communications system comprising: a subscriber device management and control unit that allocates wavelengths to be used for communications to one or more newly connected new subscriber devices; a node control unit that controls at least the connections of ports to which the new subscriber devices are connected; and an optical node device that operates under the control of the node control unit, wherein the optical node device comprises: a distribution device that distributes input optical signals in accordance with instructions from the node control unit; and an optical cross-connect unit that connects to two or more routes, wherein the distribution device comprises: a plurality of first ports to which a plurality of subscriber devices are connected; a plurality of second ports that connect to the optical cross-connect unit; and a control unit that sets a detection optical path between a first port among the plurality of first ports to which at least one newly connected new subscriber device is connected and an unused second port among the plurality of second ports, and measures the power of the optical signal at each of the first port to which the detection optical path is set and the unused second port, wherein the node control unit or the control unit determines whether the wavelength of the optical signal transmitted from the one or more new subscriber devices is abnormal based on the measured power of the optical signal.

7. The optical communication system according to claim 6, wherein the subscriber device management control unit instructs the one or more new subscriber devices to emit light at a wavelength different from that of the previous time when the judgment result of the node control unit or the control unit indicates an abnormality.

8. A method for determining an abnormality, comprising: setting a detection optical path between a first port to which at least one newly connected new subscriber device is connected, among a plurality of first ports to which a plurality of subscriber devices are connected, and an unused second port among a plurality of second ports connected to an optical cross-connect unit that is connected to two or more routes; and determining whether or not the wavelength of the optical signal transmitted from the one or more new subscriber devices is abnormal based on the power of the optical signal at each of the first port to which the detection optical path is set and the unused second port.

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