Optical communication system and optical communication path opening method

Abstract

An optical communication system comprising: a first optical multiplexing / demultiplexing unit that branches and outputs uplink control signal light and main signal light that are transmitted at different wavelengths from one or more newly connected subscriber devices; a subscriber device management and control unit that transmits downlink control signal light to the one or more newly connected subscriber devices in accordance with the branched uplink control signal light; an optical distribution unit that has a plurality of first ports and a plurality of second ports, receives through any first port of the plurality of first ports input of the main signal light which has been branched after being transmitted from the one or more newly connected subscriber devices in accordance with the downlink control signal light, and outputs the main signal light from any second port of the plurality of second ports; a detection unit that detects the main signal light input through the first port; and an optical distribution control unit that controls the connection between the ports of the optical distribution unit so as to connect the first port through which the main signal light has been detected to any second port of the plurality of second ports to which the subscriber device serving as the communication partner of the one or more newly connected subscriber devices is connected.　

Description

Optical communication system and method for opening an optical communication route

[0001] The present invention relates to an optical communication system and an optical communication path opening method. This application claims priority to PCT / JP2023 / 029519, filed in Japan on August 15, 2023, the contents of which are incorporated herein by reference.

[0002] In a conventional optical communication system, a subscriber device needs to open an optical path to connect with a subscriber device with which it will communicate in order to communicate. Figures 19 and 20 are diagrams for explaining a method for opening an optical path in a conventional optical communication system 100. As shown in Figure 19, the conventional optical communication system 100 includes a plurality of subscriber devices 200-1 to 200-3, a plurality of subscriber devices 300-1 to 300-3, a plurality of control units 400-1 to 400-2, a plurality of optical distribution units 500-1 to 500-2, and a plurality of wavelength multiplexing / demultiplexing units 550-1 to 550-2.

[0003] It is assumed that subscriber device 200-1 is not connected to the optical distribution unit 500-1, subscriber devices 200-2 to 200-3 are connected to the optical distribution unit 500-1 via optical transmission paths, and subscriber devices 300-1 to 300-3 are connected to the optical distribution unit 500-2 via optical transmission paths. The optical distribution unit 500-1 and the optical distribution unit 500-2 are connected to an optical communication NW 600 configured by optical transmission paths via wavelength multiplexing / demultiplexing units 550-1 to 550-2. The control unit 400-1 manages subscriber device 200 and controls the operation of the optical distribution unit 500-1. The control unit 400-2 manages subscriber device 300 and controls the operation of the optical distribution unit 500-2.

[0004] Assume that when a user attempts to start communication via the subscriber device 200-1, the subscriber device 200-1 is newly connected to the optical distribution unit 500-1. When the subscriber device 200-1 is initially connected, the optical distribution control unit 410 sets up a connection between the ports of the optical distribution unit 500-1 so that the subscriber device 200-1 communicates with the subscriber device management and control unit 420. This allows the subscriber device 200-1 and the subscriber device management and control unit 420 to exchange information necessary for registering and authenticating the subscriber device 200-1, and allows the subscriber device management and control unit 420 to instruct the subscriber device 200-1 on the emission wavelength to be used for transmission and reception. A control signal called an Auxiliary Management and Control Channel (AMCC) can be used as a signal for managing and controlling the subscriber devices. The AMCC signal includes status information indicating, for example, the transmission and reception wavelengths, transmission optical intensity, and temperature of the optical transceiver.

[0005] When the registration and authentication of the subscriber device 200-1 and the wavelength setting are completed, the optical distribution control unit 410 changes the setting of the port connection of the optical distribution unit 500-1 so that the optical signal transmitted from the subscriber device 200-1 is forwarded to the subscriber device 300 (e.g., subscriber device 300-1) that is the communication partner, as shown in Figure 20. Similarly, the control unit 400-2 changes the setting of the port connection of the optical distribution unit 500-2 so that the optical signal transmitted from the subscriber device 200-1 is forwarded to the subscriber device 300 (e.g., subscriber device 300-1) that is the communication partner. This makes it possible to open an optical path connecting the subscriber device 200-1 and the subscriber device 300-1, as shown in Figure 20.

[0006] However, in the configuration of the optical communication system 100 shown in Figures 19 and 20, once an optical path is opened, there is no control channel for transmitting control signals between the control unit 400 and the subscriber devices 200, 300. In contrast, the configuration of the optical communication system 150 shown in Figure 21 makes it possible for the control unit 400 to exchange control signals with the multiple subscriber devices 200, 300 even after an optical path is opened.

[0007] Fig. 21 is a diagram showing an example of the configuration of a conventional optical communication system 150. As shown in Fig. 21, the conventional optical communication system 150 includes a plurality of subscriber units 200-1 to 200-3, a plurality of subscriber units 300-1 to 300-3, a plurality of control units 400-1 to 400-2, a plurality of optical distribution units 500-1 to 500-2, a plurality of wavelength multiplexing / demultiplexing units 550-1 to 550-2, a plurality of first optical multiplexing / demultiplexing units 610-1 to 610-3, a second optical multiplexing / demultiplexing unit 620, a plurality of first optical multiplexing / demultiplexing units 630-1 to 630-3, and a second optical multiplexing / demultiplexing unit 640. The optical communication system 150 has a configuration in which a plurality of first optical multiplexing / demultiplexing units 610-1 to 610-3, a second optical multiplexing / demultiplexing unit 620, a plurality of first optical multiplexing / demultiplexing units 630-1 to 630-3, and a second optical multiplexing / demultiplexing unit 640 are added to the optical communication system 100 shown in Figures 19 and 20.

[0008] The plurality of first optical multiplexing / demultiplexing units 610-1 to 610-3 are provided between the plurality of subscriber devices 200-1 to 200-3 and the optical distribution unit 500-1. The second optical multiplexing / demultiplexing unit 620 is provided between the plurality of first optical multiplexing / demultiplexing units 610-1 to 610-3 and the control unit 400-1. The plurality of first optical multiplexing / demultiplexing units 630-1 to 630-3 are provided between the plurality of subscriber devices 300-1 to 300-3 and the optical distribution unit 500-2. The second optical multiplexing / demultiplexing unit 640 is provided between the plurality of first optical multiplexing / demultiplexing units 630-1 to 630-3 and the control unit 400-2.

[0009] The subscriber units 200-1 to 200-3 output upstream control signals for the control unit 400-1 at a wavelength different from that of the optical carrier (hereinafter referred to as "main signal light") that carries the main signal. The multiple first optical multiplexing / demultiplexing units 610-1 to 610-3 forward the upstream control signal light transmitted from the subscriber units 200-1 to 200-3 to the second optical multiplexing / demultiplexing unit 620. The second optical multiplexing / demultiplexing unit 620 multiplexes the upstream control signal light forwarded from the multiple first optical multiplexing / demultiplexing units 610-1 to 610-3 and outputs the multiplexed signal to the control unit 400-1. The control unit 400-2 outputs downstream control signals for the multiple subscriber units 300-1 to 300-3 at a wavelength different from that of the main signal light. The second optical multiplexing / demultiplexing unit 640 splits the downstream control signal light output from the control unit 400-2 and outputs the multiplexed signal to the multiple first optical multiplexing / demultiplexing units 630-1 to 630-3. The first optical multiplexing / demultiplexing sections 630-1 to 630-3 wavelength-multiplex the downstream control signal light and the main signal light, and output the multiplexed signals to the subscriber units 300-1 to 300-3.

[0010] With the above configuration, the control units 400-1 to 400-2 exchange information necessary for registration and authentication and for opening an optical path with the subscriber devices 200 and 300 before the optical path is opened, via the plurality of first optical multiplexing / demultiplexing units 610-1 to 610-3 and the second optical multiplexing / demultiplexing unit 620, or the plurality of first optical multiplexing / demultiplexing units 630-1 to 630-3 and the second optical multiplexing / demultiplexing unit 640. Similarly, the control units 400-1 to 400-2 can exchange control information with the subscriber devices 200 and 300 after the optical path is opened, via the plurality of first optical multiplexing / demultiplexing units 610-1 to 610-3 and the second optical multiplexing / demultiplexing unit 620, or the plurality of first optical multiplexing / demultiplexing units 630-1 to 630-3 and the second optical multiplexing / demultiplexing unit 640.

[0011] Takuya Kanai, Kazuaki Honda, Yasunari Tanaka, Makoto Kaneko, Kazutaka Hara, Junichi Kani, and Tomoaki Yoshida, "Photonic Gateway Supporting All-Photonics Networks," IEICE General Conference, B-8-20, March 2021.

[0012] In order to open an optical path for a newly connected subscriber device, once the registration, authentication, wavelength setting, etc. of the newly connected subscriber device are completed, the optical distribution control unit must set the inter-port connection of the optical distribution unit so that the main signal light transmitted from the newly connected subscriber device is forwarded to the subscriber device with which it will communicate. At this time, in order for the optical distribution control unit to appropriately change the inter-port connection setting of the optical distribution unit, the control unit must recognize which port of the optical distribution unit the newly connected subscriber device is connected to via the optical transmission line. However, in the conventional configuration shown in Figure 21, the control unit cannot recognize which port of the optical distribution unit the newly connected subscriber device is connected to via the optical transmission line, which causes a problem that the optical path, which is an optical route, cannot be opened.

[0013] In view of the above circumstances, the present invention aims to provide a technology that can open an optical path that connects a newly connected subscriber device to a subscriber device with which it is to communicate in an optical communication system that has an optical multiplexing / demultiplexing unit between an optical distribution unit or control unit and a subscriber device, so that they can communicate with each other.

[0014] One aspect of the present invention is a subscriber equipment management and control unit that includes a first optical multiplexer / demultiplexer that splits and outputs upstream control signal light and main signal light transmitted at different wavelengths from one or more newly connected subscriber equipment, a subscriber equipment management and control unit that transmits control signal light to the one or more newly connected subscriber equipment instructing the one or more newly connected subscriber equipment to output at least the main signal light in response to the upstream control signal light split by the first optical multiplexer / demultiplexer, a plurality of first ports, and a plurality of second ports, and that splits and outputs the main signal light transmitted from the one or more newly connected subscriber equipment in response to the control signal light and split by the first optical multiplexer / demultiplexer. an optical distribution unit that receives input from any one of a plurality of first ports and outputs from any one of the plurality of second ports; a detection unit that detects the main signal light input to any one of the plurality of first ports of the optical distribution unit; and an optical distribution control unit that controls connections between ports of the optical distribution unit so as to connect the first port at which the main signal light is detected by the detection unit to any one of the plurality of second ports to which a subscriber device that will be a communication partner of the one or more newly connected subscriber devices is connected.

[0015] One aspect of the present invention is a method for opening an optical communication path, comprising: branching and outputting upstream control signal light and main signal light transmitted at different wavelengths from one or more newly connected subscriber devices; transmitting control signal light to the one or more newly connected subscriber devices in response to the branched upstream control signal light, instructing the one or more newly connected subscriber devices to output at least the main signal light; an optical distribution unit having a plurality of first ports and a plurality of second ports inputting the branched main signal light transmitted from the one or more newly connected subscriber devices in response to the control signal light from any one of the plurality of first ports; detecting the main signal light input to any one of the plurality of first ports of the optical distribution unit; and controlling a connection between ports of the optical distribution unit so as to connect the first port where the main signal light is detected to any one of the plurality of second ports to which a subscriber device that will be a communication partner of the one or more newly connected subscriber devices is connected.

[0016] According to the present invention, in an optical communication system having an optical multiplexing / demultiplexing unit between an optical distribution unit or control unit and a subscriber device, it is possible to open an optical path that connects a newly connected subscriber device to a subscriber device with which it is to communicate so that they can communicate with each other.

[0017] FIG. 1 is a diagram illustrating an example of a configuration of an optical communication system according to a first embodiment. FIG. 2 is a sequence diagram illustrating a flow of an optical path establishment process (part 1) of the optical communication system according to the first embodiment. FIG. 3 is a sequence diagram illustrating a flow of an optical path establishment process (part 2) of the optical communication system according to the first embodiment. FIG. 4 is a sequence diagram illustrating a flow of an optical path establishment process (part 3) of the optical communication system according to the first embodiment. FIG. 5 is a diagram illustrating an example of a configuration of an optical communication system according to a first modification of the first embodiment. FIG. 6 is a diagram illustrating an example of a configuration of an optical communication system according to a second embodiment. FIG. 7 is a diagram illustrating an example of a configuration of an optical communication system according to a third embodiment. FIG. 8 is a sequence diagram illustrating a flow of an optical path establishment process (part 1) of the optical communication system according to the third embodiment. FIG. 9 is a sequence diagram illustrating a flow of an optical path establishment process (part 1) of the optical communication system according to the third embodiment. FIG. 10 is a sequence diagram illustrating a flow of an optical path establishment process (part 2) of the optical communication system according to the third embodiment. FIG. 10 is a sequence diagram showing the flow of optical path opening processing (part 2) in the optical communication system according to the third embodiment. FIG. 11 is a sequence diagram showing the flow of optical path opening processing (part 3) in the optical communication system according to the third embodiment. FIG. 12 is a sequence diagram showing the flow of optical path opening processing (part 3) in the optical communication system according to the third embodiment. FIG. 13 is a sequence diagram showing the flow of optical path opening processing (part 3) in the optical communication system according to the third embodiment. FIG. 14 is a diagram showing an example of the configuration of an optical communication system according to a first modified example of the third embodiment. FIG. 15 is a diagram for explaining a method of opening an optical path in a conventional optical communication system. FIG. 16 is a diagram for explaining a method of opening an optical path in a conventional optical communication system. FIG. 17 is a diagram showing an example of the configuration of a conventional optical communication system.

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] 1 is a diagram illustrating an example of the configuration of an optical communication system 1 according to a first embodiment. The optical communication system 1 includes a plurality of subscriber devices 10 (e.g., subscriber devices 10-1 to 10-3), a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing / demultiplexing units 20 (e.g., first optical multiplexing / demultiplexing units 20-1 to 20-3), a second optical multiplexing / demultiplexing unit 30, a plurality of optical distribution units 40 (e.g., optical distribution units 40-1 to 40-2), a plurality of wavelength multiplexing / demultiplexing units 50 (e.g., wavelength multiplexing / demultiplexing units 50-1 to 50-2), a plurality of first optical multiplexing / demultiplexing units 60 (e.g., first optical multiplexing / demultiplexing units 60-1 to 60-3), a second optical multiplexing / demultiplexing unit 70, and a management and control device 80. In the first embodiment, an example will be described in which the subscriber device 10 transmits an optical signal and the subscriber device 15 receives the optical signal transmitted from the subscriber device 10 .

[0020] In the following description, the direction from the subscriber devices 10 and 15 toward the management and control device 80 is referred to as the upstream direction, and the direction from the management and control device 80 toward the subscriber devices 10 and 15 is referred to as the downstream direction. The numbers of subscriber devices 10 and 15, first optical multiplexing and demultiplexing units 20 and 60, second optical multiplexing and demultiplexing units 30 and 70, optical distribution units 40, and wavelength multiplexing and demultiplexing units 50 included in the optical communication system 1 are not limited to the numbers shown in FIG.

[0021] Optical transmission paths are used to connect between the subscriber device 10 and the first optical multiplexing / demultiplexing unit 20, between the first optical multiplexing / demultiplexing unit 20 and the second optical multiplexing / demultiplexing unit 30, between the second optical multiplexing / demultiplexing units 30, 70 and the management and control device 80, between the first optical multiplexing / demultiplexing unit 20 and the optical distribution unit 40-1, between the optical distribution unit 40-1 and the wavelength multiplexing / demultiplexing unit 50-1, between the wavelength multiplexing / demultiplexing unit 50-1 and the wavelength multiplexing / demultiplexing unit 50-2, between the wavelength multiplexing / demultiplexing unit 50-2 and the optical distribution unit 40-2, between the optical distribution unit 40-2 and the first optical multiplexing / demultiplexing unit 60, between the first optical multiplexing / demultiplexing unit 60 and the subscriber device 15, and between the first optical multiplexing / demultiplexing unit 60 and the second optical multiplexing / demultiplexing unit 70. The optical transmission paths are, for example, optical fibers. An optical communication network 75 is provided between the wavelength multiplexing / demultiplexing unit 50-1 and the wavelength multiplexing / demultiplexing unit 50-2.

[0022] The subscriber device 10 includes an optical transceiver. The optical transceiver is, for example, a coherent transceiver. The subscriber device 10 transmits and receives optical signals such as main signals and control signals using the optical transceiver. Before the optical path is opened, the subscriber device 10 transmits light of a wavelength that reaches the optical distribution unit 40-1 in response to instructions from the management and control device 80. After receiving control signal light from the management and control device 80 instructing the output of main signal light, for example, the subscriber device 10 before the optical path is opened transmits light of a wavelength that reaches the optical distribution unit 40-1. The wavelength used here is notified to the subscriber device 10 before the optical path is opened in response to the exchange of information necessary for registration, authentication, and optical path opening between the subscriber device 10 and the management and control device 80.

[0023] The information required to open an optical path includes, for example, information on the wavelength used for transmission and reception, information on the subscriber device 15 to be communicated with, etc. The light of the wavelength that reaches the optical distribution unit 40-1 is light within the wavelength range that is transmitted from the port on the subscriber device 10 side to the port on the optical distribution unit 40-1 side among the input / output ports of the first optical multiplexing / demultiplexing unit 20.

[0024] The subscriber device 10 outputs an upstream control signal light to the management and control device 80 as an optical signal with a wavelength different from that of the main signal light. The main signal light is light with a wavelength that reaches the optical distribution unit 40-1. The wavelength of the upstream control signal light transmitted by the subscriber device 10 is within the wavelength range that is transmitted from the port on the subscriber device 10 side to the port on the second optical distribution unit 30 side among the input / output ports of the first optical multiplexing / demultiplexing unit 20. Note that the wavelengths of the upstream control signal light transmitted by each subscriber device 10 may all be the same. The subscriber device 10 is, for example, an ONU (Optical Network Unit) installed in a subscriber's premises. In the following description, an example will be given in which the subscriber device 10-1 is a subscriber device newly connected to the optical distribution unit 40-1, and the subscriber device newly connected to the optical distribution unit 40 will be referred to as a new subscriber device.

[0025] The subscriber device 15 is a device that communicates with the subscriber device 10. The subscriber device 15 is equipped with an optical transceiver. The subscriber device 15 transmits and receives optical signals such as main signals and control signals using the optical transceiver. The subscriber device 15 also performs the same processing as the subscriber device 10 before opening an optical path. The subscriber device 15 receives downstream control signal light transmitted from the management control device 80 and main signal light transmitted over the optical transmission path 86. The subscriber device 15 is, for example, an ONU installed in a subscriber's premises.

[0026] The first optical multiplexing / demultiplexing unit 20 is provided between the subscriber devices 10 and the optical distribution unit 40-1. The first optical multiplexing / demultiplexing unit 20 branches and outputs upstream control signal light and main signal light, which are transmitted from each subscriber device 10 at different wavelengths. In the following description, the branching performed by the first optical multiplexing / demultiplexing unit 20 includes a case where the upstream control signal light and the main signal light are separated, and a case where the upstream control signal light and the main signal light are separated at a predetermined ratio. When separating the upstream control signal light and the main signal light, the first optical multiplexing / demultiplexing unit 20 separates the upstream control signal light and the main signal light by wavelength, outputs the separated upstream control signal light to the second optical multiplexing / demultiplexing unit 30, and outputs the separated main signal light to the optical distribution unit 40-1. When the upstream control signal light and the main signal light are to be branched at a predetermined ratio, the first optical multiplexing / demultiplexing unit 20 branches both the upstream control signal light and the main signal light at a predetermined ratio and outputs them to the second optical multiplexing / demultiplexing unit 30 and the optical distribution unit 40-1. The first optical multiplexing / demultiplexing unit 20 in the first embodiment is, for example, an optical multiplexer / demultiplexer with wavelength selectivity (for example, a wavelength filter).

[0027] The second optical multiplexing / demultiplexing unit 30 is provided between the first optical multiplexing / demultiplexing unit 20 and the control unit 81-1. The second optical multiplexing / demultiplexing unit 30 multiplexes the upstream control signal light transferred from each first optical multiplexing / demultiplexing unit 20 and outputs the multiplexed signal to the control unit 81-1. The second optical multiplexing / demultiplexing unit 30 is, for example, an optical coupler.

[0028] The light distribution unit 40-1 has P (P is an integer equal to or greater than 2) ports 41-1, Q (Q is an integer equal to or greater than 2) ports 42-1, and a light detection unit 43-1. Because the light distribution unit 40-2 has a similar configuration to the light distribution unit 40-1, the configuration of the light distribution unit 40-1 will be used as an example. An optical signal input to a port of the light distribution unit 40 is output from another port. For example, an optical signal input to port 41-1 of the light distribution unit 40 is output from port 42-1. The light distribution unit 40 in the first embodiment is a fiber cross connect (FXC) that outputs light input from each port to a port that is set as a connection port for that port, regardless of wavelength. The light distribution unit 40 in the first embodiment may be, for example, a spatial optical switch using a MEMS (microelectromechanical systems) or a piezoelectric actuator. The port 41-1 is one aspect of the first port, and the port 42-1 is one aspect of the second port.

[0029] The optical detection unit 43-1 detects an optical signal input to the port 41-1. When the optical detection unit 43-1 detects an optical signal, it notifies the management control device 80 of the detection result, including the port that detected the optical signal. The notification from the optical detection unit 43-1 to the management control device 80 may be sent via an electrical line connecting the management control device 80 and the optical distribution unit 40-1. The notification sent from the optical detection unit 43-1 enables the management control device 80 to recognize the input of light to the port to which a new subscriber device 10 is connected.

[0030] The wavelength multiplexing / demultiplexing unit 50 multiplexes or demultiplexes the input optical signals according to their wavelengths. For example, the wavelength multiplexing / demultiplexing unit 50-1 multiplexes optical signals of multiple wavelengths output from the optical distribution unit 40-1 to generate multiplexed signal light. The wavelength multiplexing / demultiplexing unit 50-1 outputs the generated multiplexed signal light to an optical transmission path. For example, the wavelength multiplexing / demultiplexing unit 50-2 demultiplexes the multiplexed signal light input via the optical transmission path according to wavelength and outputs the demultiplexed signal light. The wavelength multiplexing / demultiplexing unit 50 is, for example, an AWG (Arrayed Waveguide Grating) or a WSS (Wavelength Selective Switch).

[0031] The first optical multiplexing / demultiplexing unit 60 is provided between the subscriber device 15 and the optical distribution unit 40-2. The first optical multiplexing / demultiplexing unit 60 wavelength-multiplexes the main signal light transmitted through the optical transmission path and the downstream control signal light output from the second optical multiplexing / demultiplexing unit 70, and outputs the multiplexed signal to the subscriber device 15. The first optical multiplexing / demultiplexing unit 60 in the first embodiment uses an optical multiplexer / demultiplexer with wavelength selectivity (for example, a wavelength filter).

[0032] The second optical multiplexing / demultiplexing unit 70 is provided between the first optical multiplexing / demultiplexing unit 60 and the control unit 81-2. The second optical multiplexing / demultiplexing unit 70 branches the downstream control signal light output from the control unit 81-2 and outputs it to each first optical multiplexing / demultiplexing unit 60. The second optical multiplexing / demultiplexing unit 70 is, for example, an optical coupler.

[0033] The management and control device 80 controls at least the subscriber devices 10 and 15 and the optical distribution unit 40. Here, the control of the subscriber devices 10 and 15 includes, for example, control of the transmission timing of the main signal light, allocation of emission wavelengths to the subscriber devices 10 and 15, and instructions to stop light and change wavelengths. The control of the optical distribution unit 40 includes, for example, switching the connections between ports of the optical distribution unit 40. The management and control device 80 includes multiple control units 81 (for example, control units 81-1 to 81-2). Each control unit 81 controls each optical distribution unit 40 and the subscriber devices 10 and 15 accommodated in each optical distribution unit 40. For example, the control unit 81-1 controls the optical distribution unit 40-1 and the subscriber device 10 accommodated in the optical distribution unit 40-1. For example, the control unit 81-2 controls the optical distribution unit 40-2 and the subscriber device 15 accommodated in the optical distribution unit 40-2.

[0034] The control unit 81-1 includes an optical distribution control unit 82-1 and a subscriber device management control unit 83-1. The control unit 81-2 has the same configuration as the control unit 81-1. The control units 81-1 and 81-2 perform similar processing except for the objects they control, so the optical distribution control unit 82-1 and the subscriber device management control unit 83-1 will be used as examples for explanation.

[0035] The optical distribution control unit 82-1 sets the route of the optical path by setting and switching the connection between the ports of the optical distribution unit 40. The optical distribution control unit 82-1 controls the connection between the ports of the optical distribution unit 40 so as to connect, for example, the port 41-1 where the optical main signal is detected by the optical detection unit 43-1 with the port 42-1 to which the subscriber device 15, which will be the communication partner of the new subscriber device, is connected.

[0036] When a new subscriber device is connected, the subscriber device management and control unit 83-1 transmits to the new subscriber device at least a control signal optical signal instructing the new subscriber device to output a main signal optical signal. After transmitting the control signal optical signal, the subscriber device management and control unit 83-1 identifies which port of the optical distribution unit 40 the new subscriber device is connected to based on the detection result transmitted from the optical distribution unit 40. For example, the subscriber device management and control unit 83-1 prevents subscriber devices 10 other than the new subscriber device, which is the destination of the control signal optical signal, from starting to transmit the main signal optical signal for a predetermined period of time after transmitting the control signal optical signal, so that the optical distribution unit 40 newly detects only the main signal optical signal transmitted from the new subscriber device, which is the destination of the control signal optical signal. By associating the detection result obtained from the optical distribution unit 40 with the new subscriber device, which is the destination of the control signal optical signal, the subscriber device management and control unit 83-1 identifies which port of the optical distribution unit 40 the new subscriber device is connected to. In this method, while optical detection continues at the port of the optical distribution unit 40 to which the subscriber device 10 for which an optical path has already been opened is connected, the subscriber device management control unit 83-1 recognizes the port where new optical detection has been performed by the optical detection unit 43 as the port to which the new subscriber device will be connected.

[0037] In addition, if there are multiple new subscriber devices, the subscriber device management and control unit 83-1 will not transmit a control signal optical signal instructing the other new subscriber devices to output an optical main signal until it has completed associating one new subscriber device with a port 41-1 of the optical distribution unit 40. This makes it possible to control multiple new subscriber devices so that they do not each transmit an optical main signal at the same time. As a result, the optical distribution unit 40 newly detects only the optical main signal transmitted from the new subscriber device that is the destination of the optical control signal. By associating the detection result obtained from the optical distribution unit 40 with the new subscriber device that is the destination of the optical control signal, it is possible to identify which port of the optical distribution unit 40 the new subscriber device is connected to.

[0038] The subscriber device management control unit 83-1 performs the process of opening an optical path by switching the connection relationship of the optical distribution unit 40 so that the identified port and the port to which the subscriber device 15 to be communicated is connected can communicate.

[0039] Furthermore, the subscriber equipment management and control unit 83-1 measures the round trip time (RTT) between the new subscriber equipment and the subscriber equipment management and control unit 83-1 by transmitting and receiving control signal light to and from the new subscriber equipment.

[0040] The subscriber device management control unit 83-1 performs photoelectric conversion on the upstream control signal light transmitted from the subscriber device 10, and then uses an identifier included in the upstream control signal to identify the subscriber device 10 that is the sender of the received upstream control signal light. Examples of the identifier include an ID assigned to the subscriber device 10 by the subscriber device management control unit 83-1, and the MAC (Media Access Control) address of the subscriber device 10.

[0041] When upstream control signal light is transmitted from multiple subscriber devices 10 simultaneously, the upstream control signal light may collide. Therefore, to enable the subscriber device management and control unit 83-1 to exchange control signal light with multiple subscriber devices 10, for example, a PON (Passive Optical Network) system can be applied. The subscriber devices 10 output upstream control signal light containing a control signal only during a time period permitted by the subscriber device management and control unit 83-1, and stop outputting the upstream control signal light during other time periods. In other words, the upstream control signal light is a burst signal light.

[0042] The subscriber device management control unit 83-1 recognizes the RTT between each subscriber device 10 and the subscriber device management control unit 83-1. Therefore, the subscriber device management control unit 83-1 refers to the RTT value and gives each subscriber device 10 permission to transmit an upstream control signal light so that the upstream control signal light from a subscriber device 10, which is a burst signal light, does not arrive at the subscriber device management control unit 83-1 in the same time period as the upstream control signal light from another subscriber device 10.

[0043] With the above configuration, the subscriber device management control unit 83-1 exchanges information necessary for registration, authentication, and optical path opening with a new subscriber device (e.g., subscriber device 10-1) via the first optical multiplexing / demultiplexing unit 20 and the second optical multiplexing / demultiplexing unit 30. Furthermore, the subscriber device management control unit 83-1 exchanges control information with the subscriber device 10 after the optical path has been opened via the first optical multiplexing / demultiplexing unit 20 and the second optical multiplexing / demultiplexing unit 30.

[0044] The control unit 81-2 transmits downstream control signal light addressed to the subscriber device 15. The wavelength of the downstream control signal light transmitted by the control unit 81-2 is within the wavelength range that is transmitted from the port on the second optical multiplexing / demultiplexing unit 70 side of the input / output ports of the first optical multiplexing / demultiplexing unit 60 to the port on the subscriber device 15 side. The downstream control signal light is signal light in which downstream control signals addressed to each subscriber device 15 are time-multiplexed. After photoelectrically converting the downstream control signal light, the subscriber device 15 selectively receives a downstream control signal addressed to itself from the time-multiplexed downstream control signals using an identifier included in the downstream control signal. Examples of the identifier include an ID assigned to the subscriber device 15 by the subscriber device management control unit 83-2 provided in the control unit 81-2 and the MAC address of the subscriber device 15. The functions of the control unit 81 may be implemented by one or more processors executing a program.

[0045] (Flow of Optical Path Establishment Processing (Part 1) in Optical Communication System 1) Fig. 2 is a sequence diagram showing the flow of optical path establishment processing (Part 1) in the optical communication system 1 in the first embodiment. Note that Fig. 2 will be described assuming that the new subscriber device is subscriber device 10-1.

[0046] Assume that a user connects the subscriber device 10-1 to the optical distribution unit 40-1 via the optical transmission path 85-1. As a result, the subscriber device 10-1 is connected to the optical distribution unit 40-1 via the optical transmission path 85-1 (step S101). The subscriber device management control unit 83-1 included in the control unit 81-1 recognizes the subscriber device 10-1 that has been newly connected to the optical distribution unit 40-1 (step S102).

[0047] The subscriber device management control unit 83-1 exchanges information necessary for opening an optical path with the subscriber device 10-1 (step S103). While exchanging the information necessary for opening an optical path, the subscriber device management control unit 83-1 measures the RTT between the subscriber device management control unit 83-1 and the subscriber device 10-1. The subscriber device management control unit 83-1 stores the measured RTT value in association with the identifier of the subscriber device 10-1.

[0048] The subscriber device management and control unit 83-1 generates a control signal instructing the output of the optical main signal (step S104). The subscriber device management and control unit 83-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-1 as a downstream control signal (step S105). The downstream control signal transmitted from the subscriber device management and control unit 83-1 is input to the second optical multiplexing and demultiplexing unit 30. The second optical multiplexing and demultiplexing unit 30 branches and outputs the input downstream control signal. The downstream control signal branched by the second optical multiplexing and demultiplexing unit 30 is input to each first optical multiplexing and demultiplexing unit 20. Each first optical multiplexing and demultiplexing unit 20 outputs the input downstream control signal to the connected subscriber device 10 via the optical transmission path 85. As a result, each subscriber device 10 receives the downstream control signal instructing the output of the optical main signal transmitted from the subscriber device management and control unit 83-1.

[0049] In response to receiving the downstream control signal light transmitted from the subscriber device management and control unit 83-1, the subscriber device 10-1 transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1 (step S106). The subscriber device 10-1 transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1, for example, immediately after receiving the downstream control signal light or after a predetermined period has elapsed since receiving it. The main signal light transmitted from the subscriber device 10-1 is input to the first optical multiplexing and demultiplexing unit 20-1 via the optical transmission line 85-1.

[0050] The first optical multiplexing / demultiplexing unit 20-1 outputs the input optical main signal to the optical dividing unit 40-1. Because the wavelength of the optical main signal transmitted by the subscriber device 10-1 is within the wavelength range of the input / output ports of the first optical multiplexing / demultiplexing unit 20 that are transmitted from the port on the subscriber device 10 side to the port on the optical dividing unit 40-1 side, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-1 is output to the optical dividing unit 40-1. The optical detector 43-1 of the optical dividing unit 40-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 (step S107). For example, the optical detector 43-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 at port 41-1-1. The optical detector 43-1 transmits a detection result indicating that light has been detected at port 41-1-1 to the control unit 81-1 (step S108).

[0051] The subscriber device management control unit 83-1 included in the control unit 81-1 acquires the detection result transmitted from the optical detection unit 43-1. Based on the acquired detection result, the subscriber device management control unit 83-1 recognizes the port to which the subscriber device 10-1 newly connected to the optical distribution unit 40-1 is connected (step S109). Specifically, the subscriber device management control unit 83-1 associates the port included in the detection result (e.g., port 41-1-1) with the subscriber device 10-1 to which the downstream control signal light is to be transmitted. As a result, the subscriber device management control unit 83-1 recognizes that the subscriber device 10-1 newly connected to the optical distribution unit 40-1 is connected to the port included in the detection result (e.g., port 41-1-1).

[0052] The optical distribution control units 82-1 and 82-2 set the connection relationship between the ports of the optical distribution units 40-1 and 40-2 based on the recognized ports and information about the subscriber device 15 (e.g., subscriber device 15-1) with which the subscriber device 10-1 communicates (step S110). Specifically, the optical distribution control unit 82-1 sets the connection relationship of the optical distribution unit 40-1 so as to connect the port 41-1-1 to which the subscriber device 10-1 is connected and the port 42-1-2 to which the subscriber device 15-1 is connected. The optical distribution control unit 82-1 generates a control signal for connecting the port 41-1-1 and the port 42-1-2. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1 (step S111).

[0053] Similarly, the optical distribution control unit included in the control unit 81-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port to which the subscriber device 15-1 is connected with the port connected to the optical distribution unit 40-1 to which the subscriber device 10-1 is connected. The optical distribution control unit included in the control unit 81-2 generates a control signal for connecting the port to which the subscriber device 15-1 is connected with the port connected to the optical distribution unit 40-1 to which the subscriber device 10-1 is connected. The optical distribution control unit included in the control unit 81-2 transmits the generated control signal to the optical distribution unit 40-2.

[0054] The optical distribution units 40-1 and 40-2 set the connection relationship between the ports based on the control signal transmitted from the management and control device 80 (step S112). As a result, an optical path is opened between the subscriber device 10-1 and the subscriber device 15-1. As a result, communication between the subscriber device 10-1 and the subscriber device 15-1 becomes possible.

[0055] The subscriber device management and control unit 83-1 may issue transmission permission to each subscriber device 10 for which an optical path has been opened, by referring to the RTT values ​​of the subscriber devices 10 for which an optical path has been opened, so that the main signal light from another subscriber device 10 is not transmitted during the period during which the main signal light transmitted by the subscriber device 10-1 in response to the downstream control signal light can reach the optical distribution unit 40-1. Here, the period during which the main signal light transmitted by the subscriber device 10-1 in response to the downstream control signal light can reach the optical distribution unit 40-1 is set in advance. With this method, the subscriber device management and control unit 83-1 recognizes the port where light is detected by the optical detection unit 43 as the port to which the new subscriber device will be connected, while optical detection is stopped at the port of the optical distribution unit 40 to which the subscriber device 10 for which an optical path has been opened is connected. This makes it possible to prevent optical signals other than the main signal light transmitted from the subscriber device 10-1 from being input to the optical distribution unit 40-1. As a result, it is possible to avoid incorrect association in the subscriber device management and control unit 83-1.

[0056] (Flow of optical path opening process (part 2) in optical communication system 1) In FIG. 2, the flow of optical path opening process when there is one new subscriber device has been described. Therefore, the flow of optical path opening process when there are multiple new subscriber devices will be described using FIG. 3 and FIG. 4. FIG. 3 and FIG. 4 are sequence diagrams showing the flow of optical path opening process (part 2) in optical communication system 1 in the first embodiment. Note that in FIG. 3 and FIG. 4, the description will be given assuming that the new subscriber devices are subscriber devices 10-1 and 10-2.

[0057] Assume that a first user connects subscriber device 10-1 to the optical distribution unit 40-1 via the optical transmission path 85-1. As a result, subscriber device 10-1 is connected to the optical distribution unit 40-1 via the optical transmission path 85-1 (step S201). Assume that a second user connects subscriber device 10-2 to the optical distribution unit 40-1 via the optical transmission path 85-2. As a result, subscriber device 10-2 is connected to the optical distribution unit 40-1 via the optical transmission path 85-2 (step S202).

[0058] The subscriber device management control unit 83-1 included in the control unit 81-1 recognizes the subscriber devices 10-1 and 10-2 newly connected to the optical distribution unit 40-1 (step S203). The subscriber device management control unit 83-1 exchanges information necessary for opening an optical path with the subscriber device 10-1 (step S204). While exchanging information necessary for opening an optical path, the subscriber device management control unit 83-1 measures the RTT between the subscriber device management control unit 83-1 and the subscriber device 10-1. The subscriber device management control unit 83-1 stores the measured RTT value in association with the identifier of the subscriber device 10-1.

[0059] Furthermore, the subscriber device management control unit 83-1 exchanges information necessary for opening an optical path with the subscriber device 10-2 (step S205). While exchanging information necessary for opening an optical path, the subscriber device management control unit 83-1 measures the RTT between the subscriber device management control unit 83-1 and the subscriber device 10-2. The subscriber device management control unit 83-1 stores the measured RTT value in association with the identifier of the subscriber device 10-2.

[0060] The subscriber device management and control unit 83-1 generates a control signal instructing the output of the main signal light (step S206). The subscriber device management and control unit 83-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-1 as a downstream control signal light (step S207). The downstream control signal light transmitted from the subscriber device management and control unit 83-1 is input to the second optical multiplexing and demultiplexing unit 30. The second optical multiplexing and demultiplexing unit 30 branches and outputs the input downstream control signal light. The downstream control signal light branched by the second optical multiplexing and demultiplexing unit 30 is input to each first optical multiplexing and demultiplexing unit 20. Each first optical multiplexing and demultiplexing unit 20 outputs the input downstream control signal light to the connected subscriber device 10 via the optical transmission path 85. As a result, each subscriber device 10 receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1.

[0061] In response to receiving the downstream control signal light transmitted from the subscriber device management and control unit 83-1, the subscriber device 10-1 transmits the main signal light of the wavelength that reaches the optical distribution unit 40-1 to the optical transmission path 85-1 (step S208). The subscriber device 10-2 also receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1. However, because the destination of the control signal is not the subscriber device 10-2, the subscriber device 10-2 discards the control signal included in the received downstream control signal light.

[0062] The subscriber device 10-1 transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1, for example, immediately after receiving the downstream control signal light or after a predetermined period has elapsed since receiving the downstream control signal light. The main signal light transmitted from the subscriber device 10-1 is input to the first optical multiplexing / demultiplexing unit 20-1 via the optical transmission line 85-1.

[0063] The first optical multiplexing / demultiplexing unit 20-1 outputs the input optical main signal to the optical dividing unit 40-1. Because the wavelength of the optical main signal transmitted by the subscriber device 10-1 is within the wavelength range of the input / output ports of the first optical multiplexing / demultiplexing unit 20 that are transmitted from the port on the subscriber device 10 side to the port on the optical dividing unit 40-1 side, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-1 is output to the optical dividing unit 40-1. The optical detector 43-1 of the optical dividing unit 40-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 (step S209). For example, the optical detector 43-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 at port 41-1-1. The optical detector 43-1 transmits a detection result indicating that light has been detected at port 41-1-1 to the control unit 81-1 (step S210).

[0064] The subscriber device management control unit 83-1 included in the control unit 81-1 acquires the detection result transmitted from the optical detection unit 43-1. Based on the acquired detection result, the subscriber device management control unit 83-1 recognizes the port to which the subscriber device 10-1 newly connected to the optical distribution unit 40-1 is connected (step S211). Specifically, the subscriber device management control unit 83-1 associates the port included in the detection result (e.g., port 41-1-1) with the subscriber device 10-1 to which the downstream control signal light is to be transmitted. As a result, the subscriber device management control unit 83-1 recognizes that the subscriber device 10-1 newly connected to the optical distribution unit 40-1 is connected to the port included in the detection result (e.g., port 41-1-1).

[0065] The optical distribution control units 82-1 and 82-2 set the connection relationship between the ports of the optical distribution units 40-1 and 40-2 based on the recognized ports and information about the subscriber device 15 (e.g., subscriber device 15-1) with which the subscriber device 10-1 communicates (step S212). Specifically, the optical distribution control unit 82-1 sets the connection relationship of the optical distribution unit 40-1 so as to connect the port 41-1-1 to which the subscriber device 10-1 is connected and the port 42-1-2 to which the subscriber device 15-1 is connected. The optical distribution control unit 82-1 generates a control signal for connecting the port 41-1-1 and the port 42-1-2. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1 (step S213).

[0066] Similarly, the optical distribution control unit included in the control unit 81-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port to which the subscriber device 15-1 is connected with the port connected to the optical distribution unit 40-1 to which the subscriber device 10-1 is connected. The optical distribution control unit included in the control unit 81-2 generates a control signal for connecting the port to which the subscriber device 15-1 is connected with the port connected to the optical distribution unit 40-1 to which the subscriber device 10-1 is connected. The optical distribution control unit included in the control unit 81-2 transmits the generated control signal to the optical distribution unit 40-2.

[0067] The optical distribution units 40-1 and 40-2 set the connection relationship between the ports based on the control signal transmitted from the management and control device 80 (step S214). As a result, an optical path is opened between the subscriber device 10-1 and the subscriber device 15-1. As a result, communication between the subscriber device 10-1 and the subscriber device 15-1 becomes possible.

[0068] Thereafter, the subscriber device management and control unit 83-1 regenerates a downstream control signal instructing the output of the main signal light (step S215). The subscriber device management and control unit 83-1 converts the generated downstream control signal into an optical signal and transmits it to the subscriber device 10-2 as a downstream control signal light (step S216). The downstream control signal light transmitted from the subscriber device management and control unit 83-1 is input to the second optical multiplexing and demultiplexing unit 30. The second optical multiplexing and demultiplexing unit 30 branches and outputs the input downstream control signal light. The downstream control signal light branched by the second optical multiplexing and demultiplexing unit 30 is input to each first optical multiplexing and demultiplexing unit 20. Each first optical multiplexing and demultiplexing unit 20 outputs the input downstream control signal light to the connected subscriber device 10 via the optical transmission path 85. As a result, each subscriber device 10 receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1.

[0069] In response to receiving the downstream control signal light transmitted from the subscriber device management and control unit 83-1, the subscriber device 10-2 transmits the main signal light of the wavelength that reaches the optical distribution unit 40-1 to the optical transmission path 85-2 (step S217). Here, the subscriber device 10-1 also receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1. However, because the destination of the control signal is not the subscriber device 10-1, the subscriber device 10-1 discards the control signal included in the received control signal light.

[0070] The subscriber device 10-2 transmits the main signal light having a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-2, for example, immediately after receiving the downstream control signal light or after a predetermined period has elapsed since receiving the downstream control signal light. The main signal light transmitted from the subscriber device 10-2 is input to the first optical multiplexing / demultiplexing unit 20-2 via the optical transmission line 85-2.

[0071] The first optical multiplexing / demultiplexing unit 20-2 outputs the input optical main signal to the optical dividing unit 40-1. Because the wavelength of the optical main signal transmitted by the subscriber device 10-2 is within the wavelength range of the input / output ports of the first optical multiplexing / demultiplexing unit 20 that are transmitted from the port on the subscriber device 10 side to the port on the optical dividing unit 40-1 side, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-2 is output to the optical dividing unit 40-1. The optical detector 43-1 of the optical dividing unit 40-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-2 (step S218). For example, the optical detector 43-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-2 at port 41-1-2. The optical detector 43-1 transmits a detection result indicating that light has been detected at port 41-1-2 to the control unit 81-1 (step S219).

[0072] The subscriber device management control unit 83-1 included in the control unit 81-1 acquires the detection result transmitted from the optical detection unit 43-1. Based on the acquired detection result, the subscriber device management control unit 83-1 recognizes the port to which the subscriber device 10-2 newly connected to the optical distribution unit 40-1 is connected (step S220). Specifically, the subscriber device management control unit 83-1 associates the port included in the detection result (e.g., port 41-1-2) with the subscriber device 10-2 to which the downstream control signal light is to be transmitted. As a result, the subscriber device management control unit 83-1 recognizes that the subscriber device 10-2 newly connected to the optical distribution unit 40-1 is connected to the port included in the detection result (e.g., port 41-1-2).

[0073] The optical distribution control units 82-1 and 82-2 set the connection relationship between the ports of the optical distribution units 40-1 and 40-2 based on the recognized ports and information about the subscriber device 15 (e.g., subscriber device 15-2) with which the subscriber device 10-2 communicates (step S221). Specifically, the optical distribution control unit 82-1 sets the connection relationship between the ports of the optical distribution units 40-1 so as to connect the port 41-1-2 to which the subscriber device 10-2 is connected and the port 42-1-3 to which the subscriber device 15-2 is connected. The optical distribution control unit 82-1 generates a control signal for connecting the port 41-1-2 and the port 42-1-3. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1 (step S222).

[0074] Similarly, the optical distribution control unit included in the control unit 81-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port to which the subscriber device 15-2 is connected with the port connected to the optical distribution unit 40-1 to which the subscriber device 10-2 is connected. The optical distribution control unit included in the control unit 81-2 generates a control signal for connecting the port to which the subscriber device 15-2 is connected with the port connected to the optical distribution unit 40-1 to which the subscriber device 10-2 is connected. The optical distribution control unit included in the control unit 81-2 transmits the generated control signal to the optical distribution unit 40-2.

[0075] The optical distribution units 40-1 and 40-2 set the connection relationship between the ports based on the control signal transmitted from the management and control device 80 (step S223). As a result, an optical path is opened between the subscriber device 10-2 and the subscriber device 15-2. As a result, communication between the subscriber device 10-2 and the subscriber device 15-2 becomes possible.

[0076] 3 and 4, the description is given of the flow in which, after an optical path between one new subscriber device and the communication partner is opened, the subscriber device management and control unit 83-1 transmits downstream control signal light to other new subscriber devices. Here, since it is sufficient for the subscriber device management and control unit 83-1 to recognize the port to which the new subscriber device is connected, the subscriber device management and control unit 83-1 may execute the process of step S215 after completing the process of step S211. That is, the subscriber device management and control unit 83-1 may recognize the port to which the subscriber device 10-1 newly connected to the optical distribution unit 40-1 is connected, and then transmit a downstream control signal light to the subscriber device 10-2 instructing it to output at least the main signal light. In this case, after recognizing the ports to which each of the multiple new subscriber devices is connected, the subscriber device management and control unit 83-1 instructs the optical distribution control unit 82-1 to control the connection between the ports of the optical distribution unit 40. In this specification, the subscriber device management and control unit 83-1 may sequentially set the port-to-port connection of the optical distribution unit 40 for each optical path.

[0077] 3 and 4, the subscriber device management control unit 83-1 may refer to the RTT values ​​of the subscriber devices 10 for which an optical path has been opened and issue a transmission permission to each of the subscriber devices 10 for which an optical path has been opened, so that the main signal light from another subscriber device 10 is not transmitted during the period in which the main signal light transmitted by the subscriber device 10-1 or 10-2 in response to the downstream control signal light can reach the optical distribution unit 40-1. This makes it possible to prevent optical signals other than the main signal light transmitted from the subscriber device 10-1 or 10-2 from being input to the optical distribution unit 40-1. As a result, it is possible to prevent incorrect association in the subscriber device management control unit 83-1.

[0078] 3 and 4, when there are multiple new subscriber devices, there is a restriction that until processing for one new subscriber device is completed, downstream control signal light instructing the other new subscriber devices to output at least the main signal light is not transmitted. In contrast, by further including information indicating the transmission timing of the main signal light in the downstream control signal light instructing the output of the main signal light, it is possible to control the transmission timing of the main signal light of each new subscriber device without imposing any restriction.

[0079] The flow of the optical path opening process in such a configuration will be described using Figures 5 and 6. Figures 5 and 6 are sequence diagrams showing the flow of the optical path opening process (part 3) in the optical communication system 1 in the first embodiment. Note that in Figures 5 and 6, the explanation will be given assuming that the new subscriber devices are subscriber devices 10-1 and 10-2. In Figures 5 and 6, the same processes as in Figures 3 and 4 are assigned the same reference numerals as in Figures 3 and 4, and the explanation will be omitted.

[0080] After the processes from step S201 to step S205 are completed, the subscriber device management and control unit 83-1 generates a control signal including an instruction to output the optical main signal and information indicating the timing of transmission of the optical main signal by the subscriber device 10-1 (step S301). The subscriber device management and control unit 83-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-1 as a downstream control signal (step S302). The downstream control signal transmitted from the subscriber device management and control unit 83-1 is input to the second optical multiplexing and demultiplexing unit 30. The second optical multiplexing and demultiplexing unit 30 branches and outputs the input downstream control signal. The downstream control signal branched by the second optical multiplexing and demultiplexing unit 30 is input to each first optical multiplexing and demultiplexing unit 20.

[0081] Each first optical multiplexing / demultiplexing unit 20 outputs the input downstream control signal light to the connected subscriber device 10 via the optical transmission path 85. As a result, each subscriber device 10 receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1. Subscriber device 10-1 waits until the transmission timing indicated by the control signal included in the downstream control signal light transmitted from the subscriber device management and control unit 83-1. At this point, subscriber device 10-2 also receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1 in the processing of step S302. However, because the destination of the downstream control signal light is not subscriber device 10-2, subscriber device 10-2 discards the control signal included in the received downstream control signal light.

[0082] After the processing of step S302, the subscriber device management and control unit 83-1 generates a control signal including an instruction to output the optical main signal and information indicating the timing of transmission of the optical main signal by the subscriber device 10-2 (step S303). Here, the subscriber device management and control unit 83-1 determines the transmission timing so that the timing of transmission of the optical main signal by the subscriber device 10-1 and the timing of transmission of the optical main signal by the subscriber device 10-2 do not overlap. Preferably, the subscriber device management and control unit 83-1 determines the timing of transmission of the optical main signal by the subscriber device 10-2 so that the period during which the optical main signal transmitted by the subscriber device 10-1 in response to the downstream control signal can reach the optical distribution unit 40-1 does not overlap with the period during which the optical main signal transmitted by the subscriber device 10-2 in response to the downstream control signal can reach the optical distribution unit 40-1.

[0083] The subscriber device management and control unit 83-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-2 as downstream control signal light (step S304). The downstream control signal light transmitted from the subscriber device management and control unit 83-1 is input to the second optical multiplexing and demultiplexing unit 30. The second optical multiplexing and demultiplexing unit 30 branches and outputs the input downstream control signal light. The downstream control signal light branched by the second optical multiplexing and demultiplexing unit 30 is input to each first optical multiplexing and demultiplexing unit 20.

[0084] Each first optical multiplexing / demultiplexing unit 20 outputs the input downstream control signal light to the connected subscriber device 10 via the optical transmission path 85. As a result, each subscriber device 10 receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1. Subscriber device 10-2 waits until the transmission timing indicated by the control signal included in the downstream control signal light transmitted from the subscriber device management and control unit 83-1. Here, subscriber device 10-1 also receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1 in the processing of step S304. However, because the destination of the downstream control signal light is not subscriber device 10-1, subscriber device 10-1 discards the control signal included in the received downstream control signal light.

[0085] When the transmission timing indicated by the control signal included in the received downstream control signal arrives, the subscriber device 10-1 transmits the optical main signal having the wavelength reaching the optical distribution unit 40-1 to the optical transmission path 85-1 (step S305). The optical main signal transmitted from the subscriber device 10-1 is input to the first optical multiplexing / demultiplexing unit 20-1 via the optical transmission path 85-1. The first optical multiplexing / demultiplexing unit 20-1 outputs the input optical main signal to the optical distribution unit 40-1. Since the wavelength of the optical main signal transmitted by the subscriber device 10-1 is within the wavelength range transmitted from the port on the subscriber device 10-1 side to the port on the optical distribution unit 40-1 side among the input / output ports of the first optical multiplexing / demultiplexing unit 20-1, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-1 is output to the optical distribution unit 40-1. Then, the processes from step S209 to step S214 are executed.

[0086] When the transmission timing indicated by the control signal included in the received downstream control signal arrives, the subscriber device 10-2 transmits the optical main signal having the wavelength reaching the optical distribution unit 40-1 to the optical transmission path 85-2 (step S306). The optical main signal transmitted from the subscriber device 10-2 is input to the first optical multiplexing / demultiplexing unit 20-2 via the optical transmission path 85-2. The first optical multiplexing / demultiplexing unit 20-2 outputs the input optical main signal to the optical distribution unit 40-1. Since the wavelength of the optical main signal transmitted by the subscriber device 10-2 is within the wavelength range transmitted from the port on the subscriber device 10-2 side to the port on the optical distribution unit 40-1 side among the input / output ports of the first optical multiplexing / demultiplexing unit 20-2, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-2 is output to the optical distribution unit 40-1. Then, the processes from step S218 to step S223 are executed.

[0087] 5 and 6, the subscriber device management control unit 83-1 may refer to the RTT values ​​of the subscriber devices 10 for which an optical path has been opened and issue a transmission permission to each of the subscriber devices 10 for which an optical path has been opened, so that the main signal light from another subscriber device 10 is not transmitted during the period in which the main signal light transmitted by the subscriber device 10-1 or 10-2 in response to the downstream control signal light can reach the optical distribution unit 40-1. This makes it possible to prevent optical signals other than the main signal light transmitted from the subscriber device 10-1 or 10-2 from being input to the optical distribution unit 40-1. As a result, it is possible to prevent incorrect association in the subscriber device management control unit 83-1.

[0088] The optical communication system 1 configured as described above includes a first optical multiplexing / demultiplexing unit 20 that splits and outputs upstream control signal light and main signal light transmitted at different wavelengths from one or more newly connected subscriber units 10, a subscriber unit management control unit 83 that transmits downstream control signal light to the one or more newly connected subscriber units 10 instructing them to output at least the main signal light in response to the upstream control signal light split by the first optical multiplexing / demultiplexing unit 20, and a subscriber unit management control unit 84 that controls and outputs downstream control signal light from the one or more newly connected subscriber units 10 in response to the downstream control signal light. an optical distribution unit 40 that inputs the main signal light transmitted from the optical fiber 10 and branched by the first optical multiplexing / branching unit 20 from port 41-1 and outputs it from port 42-1; an optical detection unit 43 that detects the main signal light input to port 41-1 of the optical distribution unit 40; and an optical distribution control unit 82 that controls the connection between the ports of the optical distribution unit 40 so as to connect port 41-1 at which the main signal light is detected by the optical detection unit 43 with port 42-1 to which is connected a subscriber device that will be a communication partner of one or more newly connected subscriber devices 10.

[0089] In this way, the subscriber device management and control unit 83 transmits at least a downstream control signal optical signal to the new subscriber device that is to transmit the main signal optical signal, instructing it to output the main signal optical signal. The subscriber device management and control unit 83 then identifies the port of the optical distribution unit 40 to which the new subscriber device that transmitted the main signal optical signal in response to the downstream control signal is connected, based on the detection result of the optical detection unit 43. This allows the control unit 81 to identify which port of the optical distribution unit 40 the new subscriber device is connected to via the optical transmission path. As a result, the optical distribution control units 82-1 and 82-2 set the inter-port connection of the optical distribution units 40-1 and 40-2 so that the main signal optical signal transmitted from the new subscriber device is forwarded to the subscriber device 15 with which it is communicating. This makes it possible to open an optical path that communicatively connects the newly connected subscriber device and the subscriber device with which it is communicating, in an optical communication system that includes an optical multiplexing and demultiplexing unit between the optical distribution unit or control unit and the subscriber device.

[0090] Furthermore, in the optical communication system 1, when there are multiple new subscriber devices, as a first method, downstream control signal light instructing the other new subscriber devices to output the main signal light is not transmitted to the other new subscriber devices until the correspondence between one of the multiple new subscriber devices and the port 41-1 of the optical distribution unit 40 is completed. In this manner, the optical communication system 1 controls the transmission timing so that the main signal light is not transmitted from multiple new subscriber devices at the same time. This allows the source of the main signal light detected by the optical detection unit 43 to be narrowed down to the single new subscriber device that is the destination of the downstream control signal light. As a result, the control unit 81 can recognize which port of the optical distribution unit 40 each of the multiple new subscriber devices is connected to via the optical transmission path. Therefore, in an optical communication system equipped with an optical multiplexing / demultiplexing unit between the optical distribution unit or the control unit and the subscriber devices, it is possible to open an optical path that communicatively connects the newly connected subscriber device and the subscriber device with which it will communicate.

[0091] Furthermore, in the optical communication system 1, when there are multiple new subscriber devices, a second method is used in which the transmission timing of the optical main signal is notified to each of the multiple new subscriber devices. In this way, the optical communication system 1 controls the transmission timing so that multiple new subscriber devices do not transmit the optical main signal at the same time. This allows the source of the optical main signal detected by the optical detector 43 to be narrowed down to a single new subscriber device that is the destination of the downstream control signal. As a result, the control unit 81 can recognize which port of the optical distribution unit 40 each of the multiple new subscriber devices is connected to via the optical transmission path. Therefore, in an optical communication system equipped with an optical multiplexing / demultiplexing unit between the optical distribution unit or the control unit and the subscriber devices, it is possible to open an optical path that communicatively connects the newly connected subscriber device and the subscriber device with which it will communicate.

[0092] (Variation 1 of the First Embodiment) FIG. 7 is a diagram showing an example of the configuration of an optical communication system 1a according to Variation 1 of the first embodiment. The optical communication system 1a includes a plurality of subscriber devices 10 (e.g., subscriber devices 10-1 to 10-3), a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing / demultiplexing units 20 (e.g., first optical multiplexing / demultiplexing units 20-1 to 20-3), a second optical multiplexing / demultiplexing unit 30, a plurality of optical distribution units 40 (e.g., optical distribution units 40-1 to 40-2), a plurality of first optical multiplexing / demultiplexing units 60 (e.g., first optical multiplexing / demultiplexing units 60-1 to 60-3), a second optical multiplexing / demultiplexing unit 70, and a management and control device 80. The optical communication system 1a differs in configuration from the optical communication system 1 in that it does not include a wavelength multiplexing / demultiplexing unit 50. The differences from the optical communication system 1 are described below.

[0093] In the configuration shown in Fig. 7, the light distribution unit 40 has a function of being able to set a transmission path for each wavelength. For example, a WSS can be used as the light distribution unit 40. This makes it possible to eliminate the need for the wavelength multiplexing / demultiplexing unit 50. Furthermore, in the configuration shown in Fig. 7, a multicast switch can also be used as the light distribution unit 40.

[0094] In the configurations shown in Figures 1 and 7, the main signal light transmitted from the subscriber unit 10 to the subscriber unit 15 and the main signal light transmitted from the subscriber unit 15 to the subscriber unit 10 flow through the core wire of the same optical transmission line. In contrast, a configuration may be made in which there is a section in which the main signal light transmitted from the subscriber unit 10 to the subscriber unit 15 and the main signal light transmitted from the subscriber unit 15 to the subscriber unit 10 flow through different core wires of the optical transmission line. When there is a section in which the signal light of different directions flows through the core wire of the same optical transmission line, the subscriber unit management and control unit 83-1 sets the wavelengths of the signal light of different directions to different wavelengths or issues transmission permission to the signal light of different directions at different timings to prevent deterioration of the reception characteristics of the signal light of the opposite direction due to reflection in the optical transmission line. When there is no section in which the signal light of different directions flows through the core wire of the same optical transmission line, the wavelengths of the signal light of different directions can be the same wavelength.

[0095] (Second Modification of the First Embodiment) In the optical communication system 1, the first optical multiplexing / demultiplexing unit 20, the second optical multiplexing / demultiplexing unit 30, the optical distribution unit 40-1, the wavelength multiplexing / demultiplexing unit 50-1, and the control unit 81-1 may be configured as an optical communication device. Similarly, the first optical multiplexing / demultiplexing unit 60, the second optical multiplexing / demultiplexing unit 70, the optical distribution unit 40-2, the wavelength multiplexing / demultiplexing unit 50-2, and the control unit 81-2 may be configured as an optical communication device.

[0096] In the optical communication system 1a, the first optical multiplexing / demultiplexing unit 20, the second optical multiplexing / demultiplexing unit 30, the optical distribution unit 40-1, and the control unit 81-1 may be configured as an optical communication device. Similarly, the first optical multiplexing / demultiplexing unit 60, the second optical multiplexing / demultiplexing unit 70, the optical distribution unit 40-2, and the control unit 81-2 may be configured as an optical communication device.

[0097] (Third Modification of the First Embodiment) In the above-described embodiment, a configuration has been shown in which the light detection unit 43 is provided inside the light distribution unit 40, but the light detection unit 43 may also be provided outside the light distribution unit 40. In such a configuration, the light distribution unit 40-1 does not include the light detection unit 43-1. The light detection unit 43-1 is connected to port 42-1-1 of the light distribution unit 40-1. Note that the port to which the light detection unit 43-1 is connected may be any of the ports 42-1. Note that the same applies to the light distribution unit 40-2 as to the light distribution unit 40-1.

[0098] The optical distribution unit 40-1 switches the connection relationship between ports in accordance with the control of the optical distribution control unit 82-1 so that each port 41-1 to which an optical path has not yet been established is sequentially connected to the port 42-1-1 to which the optical detection unit 43-1 is connected. The optical detection unit 43-1 detects an optical signal output from the port 42-1-1 to which it is connected. When the optical detection unit 43-1 detects an optical signal, it notifies the management control device 80 of the detection result indicating that an optical signal has been detected.

[0099] The configuration and processing of the management control device 80 are basically the same as those in the above-described embodiment. For example, after a downstream control signal light instructing the output of a main signal light is transmitted, the optical distribution control unit 82-1 of the management control device 80 controls the connection relationship between the ports of the optical distribution unit 40-1 so that, among the ports 41-1 of the optical distribution unit 40-1, each port 41-1 for which an optical path has not yet been opened is sequentially connected to the port 42-1-1 to which the optical detection unit 43-1 is connected.

[0100] When the subscriber device management control unit 83-1 acquires the detection result from the optical detection unit 43-1, at the time of acquiring the detection result, it recognizes that the port 41-1 connected to the port 42-1-1 to which the optical detection unit 43-1 is connected is the port to which the newly connected subscriber device 10 is connected.

[0101] With the above configuration, even if the light detection unit 43 is provided outside the light distribution unit 40, the same effects as those of the above-described embodiment can be obtained.

[0102] Second Embodiment In a second embodiment, a configuration will be described in which one subscriber unit 10 has a plurality of ports and transmits and receives an optical main signal at each port.

[0103] 8 is a diagram showing an example of the configuration of an optical communication system 1b according to the second embodiment. The optical communication system 1b includes one or more subscriber devices 10b, a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing / demultiplexing units 20 (e.g., first optical multiplexing / demultiplexing units 20-1 to 20-3), a second optical multiplexing / demultiplexing unit 30, a plurality of optical distribution units 40 (e.g., optical distribution units 40-1 to 40-2), a plurality of wavelength multiplexing / demultiplexing units 50 (e.g., wavelength multiplexing / demultiplexing units 50-1 to 50-2), a plurality of first optical multiplexing / demultiplexing units 60 (e.g., first optical multiplexing / demultiplexing units 60-1 to 60-3), a second optical multiplexing / demultiplexing unit 70, and a management and control device 80.

[0104] The optical communication system 1b differs in configuration from the optical communication system 1 in that it includes a subscriber device 10b instead of the subscriber device 10. Other configurations of the optical communication system 1b are basically the same as those of the optical communication system 1. The following description will focus on the differences from the optical communication system 1.

[0105] The subscriber device 10b has multiple ports 11-1 to 11-3 and one or more optical transceivers. The subscriber device 10b may have two or more ports 11. One optical transceiver is provided for each port 11. The optical transceiver is, for example, a coherent transceiver. The subscriber device 10b transmits and receives optical signals such as main signals and control signals using the optical transceiver.

[0106] The subscriber device 10b transmits and receives main signal light of different wavelengths via each port 11. An optical transmission line 85-1 is connected to port 11-1, an optical transmission line 85-2 is connected to port 11-2, and an optical transmission line 85-3 is connected to port 11-3. The subscriber device 10b transmits and receives control signal light to and from the management control device 80 via any one of the multiple ports 11. In this case, the subscriber device 10b uses a port identifier for identifying each port 11 in addition to the identifier of the subscriber device 10b.

[0107] In response to an instruction from the management and control device 80, the subscriber device 10b before the optical path is opened transmits light of a wavelength that reaches the optical distribution unit 40-1 via a specific port 11. After receiving, for example, downstream control signal light that instructs the output of the main signal light from the management and control device 80, the subscriber device 10b before the optical path is opened transmits light of a wavelength that reaches the optical distribution unit 40-1.

[0108] A specific processing flow in the second embodiment will be described. Assume that a user connects each port 11-1 to 11-3 of a subscriber device 10b to the optical distribution unit 40-1 via optical transmission paths 85-1 to 85-3. As a result, the subscriber device 10b is connected to the optical distribution unit 40-1 via the optical transmission paths 85-1 to 85-3. The subscriber device management and control unit 83-1 included in the control unit 81-1 recognizes the subscriber device 10b newly connected to the optical distribution unit 40-1. The subscriber device management and control unit 83-1 exchanges information necessary to open an optical path with the subscriber device 10b. At this time, the subscriber device 10b transmits an upstream control signal light including the identifier of the subscriber device 10b and the port identifier of each port 11 to the subscriber device management and control unit 83-1. This allows the subscriber device management and control unit 83-1 to recognize each port 11 of the subscriber device 10b.

[0109] Furthermore, when allocating wavelengths to subscriber device 10b, subscriber device management control unit 83-1 allocates wavelengths for each port 11. Subscriber device management control unit 83-1 notifies subscriber device 10b of information about the wavelengths allocated for each port 11 while exchanging information necessary for opening an optical path.

[0110] The subscriber device management and control unit 83-1 generates a control signal including an output instruction for the optical main signal and the port identifier of port 11. The subscriber device management and control unit 83-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10b as downstream control signal light. The downstream control signal light transmitted from the subscriber device management and control unit 83-1 is input to the second optical multiplexing and demultiplexing unit 30. The second optical multiplexing and demultiplexing unit 30 branches and outputs the input downstream control signal light. The downstream control signal light branched by the second optical multiplexing and demultiplexing unit 30 is input to each first optical multiplexing and demultiplexing unit 20. Each first optical multiplexing and demultiplexing unit 20 outputs the input downstream control signal light to the connected subscriber device 10b via the optical transmission path 85. As a result, the subscriber device 10b receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1.

[0111] In response to receiving the downstream control signal light transmitted from the subscriber device management and control unit 83-1, the subscriber device 10b transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission path 85 via the port 11 identified by the port identifier included in the downstream control signal light. For example, if the port 11 identified by the port identifier is port 11-1, the subscriber device 10b transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission path 85-1 via port 11-1. Here, the description will be given assuming that the port 11 identified by the port identifier is port 11-1.

[0112] The subscriber device 10b transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1 via the port 11-1, for example, immediately after receiving the downstream control signal light or after a predetermined period has elapsed since receiving the downstream control signal light. The main signal light transmitted from the subscriber device 10b is input to the first optical multiplexing / demultiplexing unit 20-1 via the optical transmission line 85-1.

[0113] The first optical multiplexing / demultiplexing unit 20-1 outputs the input optical main signal to the optical dividing unit 40-1. Since the wavelength of the optical main signal transmitted by the subscriber device 10b is within the wavelength range of the input / output ports of the first optical multiplexing / demultiplexing unit 20-1 that are transmitted from the port on the subscriber device 10 side to the port on the optical dividing unit 40-1 side, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-1 is output to the optical dividing unit 40-1. The optical detection unit 43-1 of the optical dividing unit 40-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1. For example, the optical detection unit 43-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 at port 41-1-1. The optical detection unit 43-1 transmits a detection result indicating that light has been detected at port 41-1-1 to the control unit 81-1.

[0114] The subscriber device management control unit 83-1 included in the control unit 81-1 acquires the detection result sent from the optical detection unit 43-1. Based on the acquired detection result, the subscriber device management control unit 83-1 recognizes the port to which the subscriber device 10b newly connected to the optical distribution unit 40-1 is connected. Specifically, the subscriber device management control unit 83-1 associates the port included in the detection result (e.g., port 41-1-1) with port 11-1 of the subscriber device 10b, which is the destination of the downstream control signal light. As a result, the subscriber device management control unit 83-1 recognizes that port 11-1 of the subscriber device 10b newly connected to the optical distribution unit 40-1 is connected to the port included in the detection result (e.g., port 41-1-1).

[0115] The optical distribution control units 82-1 and 82-2 set the connection relationship between the ports of the optical distribution units 40-1 and 40-2 based on the recognized ports and information about the subscriber device 15 (e.g., subscriber device 15-1) with which the subscriber device 10b communicates. Specifically, the optical distribution control unit 82-1 sets the connection relationship of the optical distribution unit 40-1 so as to connect the port 41-1-1, to which the port 11-1 of the subscriber device 10b is connected, with the port 42-1-2, to which the subscriber device 15-1 is connected. The optical distribution control unit 82-1 generates a control signal for connecting the port 41-1-1 and the port 42-1-2. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1.

[0116] Similarly, the optical distribution control unit included in the control unit 81-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port to which the subscriber device 15-1 is connected with the port connected to the optical distribution unit 40-1 to which port 11-1 of the subscriber device 10b is connected. The optical distribution control unit included in the control unit 81-2 generates a control signal for connecting the port to which the subscriber device 15-1 is connected with the port connected to the optical distribution unit 40-1 to which port 11-1 of the subscriber device 10b is connected. The optical distribution control unit included in the control unit 81-2 transmits the generated control signal to the optical distribution unit 40-2.

[0117] The optical distribution units 40-1 and 40-2 set the connection relationship between the ports based on the control signal transmitted from the management and control device 80. As a result, an optical path is opened between the port 11-1 of the subscriber device 10b and the subscriber device 15-1. As a result, communication becomes possible between the subscriber device 10b and the subscriber device 15-1.

[0118] Thereafter, the subscriber device management and control unit 83-1 generates a control signal including an output instruction for the optical main signal and the port identifier of port 11. The subscriber device management and control unit 83-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10b as downstream control signal light. The downstream control signal light transmitted from the subscriber device management and control unit 83-1 is input to the second optical multiplexing and demultiplexing unit 30. The second optical multiplexing and demultiplexing unit 30 branches and outputs the input downstream control signal light. The downstream control signal light branched by the second optical multiplexing and demultiplexing unit 30 is input to each first optical multiplexing and demultiplexing unit 20. Each first optical multiplexing and demultiplexing unit 20 outputs the input downstream control signal light to the connected subscriber device 10b via the optical transmission path 85. As a result, the subscriber device 10b receives the downstream control signal light transmitted from the subscriber device management and control unit 83-1.

[0119] In response to receiving the downstream control signal light transmitted from the subscriber device management and control unit 83-1, the subscriber device 10b transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission path 85 via the port 11 identified by the port identifier included in the downstream control signal light. For example, if the port 11 identified by the port identifier is port 11-2, the subscriber device 10b transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission path 85-2 via port 11-2. Here, the description will be given assuming that the port 11 identified by the port identifier is port 11-2.

[0120] The subscriber device 10b transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-2 via the port 11-2, for example, immediately after receiving the downstream control signal light or after a predetermined period has elapsed since receiving the downstream control signal light. The main signal light transmitted from the subscriber device 10b is input to the first optical multiplexing / demultiplexing unit 20-1 via the optical transmission line 85-2.

[0121] The first optical multiplexing / demultiplexing unit 20-1 outputs the input optical main signal to the optical dividing unit 40-1. Since the wavelength of the optical main signal transmitted by the subscriber device 10b is within the wavelength range of the input / output ports of the first optical multiplexing / demultiplexing unit 20-2 that are transmitted from the port on the subscriber device 10 side to the port on the optical dividing unit 40-1 side, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-2 is output to the optical dividing unit 40-1. The optical detection unit 43-1 of the optical dividing unit 40-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-2. For example, the optical detection unit 43-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-2 at port 41-1-2. The optical detection unit 43-1 transmits a detection result indicating that light has been detected at port 41-1-2 to the control unit 81-1.

[0122] The subscriber device management control unit 83-1 included in the control unit 81-1 acquires the detection result transmitted from the optical detection unit 43-1. Based on the acquired detection result, the subscriber device management control unit 83-1 recognizes the port to which the subscriber device 10b newly connected to the optical distribution unit 40-1 is connected. Specifically, the subscriber device management control unit 83-1 associates the port included in the detection result (e.g., port 41-1-1) with port 11-2 of the subscriber device 10b, which is the destination of the downstream control signal light. As a result, the subscriber device management control unit 83-1 recognizes that port 11-2 of the subscriber device 10b newly connected to the optical distribution unit 40-1 is connected to the port included in the detection result (e.g., port 41-1-1).

[0123] The optical distribution control units 82-1 and 82-2 set the connection relationships between the ports of the optical distribution units 40-1 and 40-2 based on the recognized ports and information about the subscriber device 15 (e.g., subscriber device 15-2) with which the subscriber device 10b communicates. Specifically, the optical distribution control unit 82-1 sets the connection relationships between the ports of the optical distribution units 40-1 and 40-2 so as to connect the port 41-1-2, to which the port 11-2 of the subscriber device 10b is connected, with the port 42-1-3, to which the subscriber device 15-2 is connected. The optical distribution control unit 82-1 generates a control signal for connecting the port 41-1-2 and the port 42-1-3. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1.

[0124] Similarly, the optical distribution control unit included in the control unit 81-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port to which the subscriber device 15-2 is connected with the port connected to the optical distribution unit 40-1 to which port 11-2 of the subscriber device 10b is connected. The optical distribution control unit included in the control unit 81-2 generates a control signal for connecting the port to which the subscriber device 15-2 is connected with the port connected to the optical distribution unit 40-1 to which port 11-2 of the subscriber device 10b is connected. The optical distribution control unit included in the control unit 81-2 transmits the generated control signal to the optical distribution unit 40-2.

[0125] The optical distribution units 40-1 and 40-2 set the connection relationship between the ports based on the control signal transmitted from the management and control device 80. As a result, an optical path is opened between the port 11-2 of the subscriber device 10b and the subscriber device 15-2. As a result, communication becomes possible between the subscriber device 10b and the subscriber device 15-2.

[0126] According to the second embodiment configured as described above, even if one subscriber device 10b has multiple ports 11, the control unit 81 can recognize which port of the optical distribution unit 40 the new subscriber device is connected to via the optical transmission path, as in the first embodiment. As a result, the optical distribution control units 82-1 and 82-2 set the inter-port connection of the optical distribution units 40-1 and 40-2 so that the main signal light transmitted from the new subscriber device is forwarded to the subscriber device 15 with which it will communicate. This makes it possible to open an optical path that communicatively connects the newly connected subscriber device and the subscriber device with which it will communicate, in an optical communication system that includes an optical multiplexing / demultiplexing unit between the optical distribution unit or control unit and the subscriber device.

[0127] (Variation 1 of the Second Embodiment) In the optical communication system 1b, the downstream control signal light that instructs the output of the main signal light may further include information indicating the transmission timing of the main signal light, thereby controlling the transmission timing of the main signal light of each new subscriber device without imposing any restrictions. The specific processing is the same as in Figures 5 and 6, except that instead of multiple new subscriber devices, one new subscriber device has multiple ports 11. Therefore, it is sufficient to replace the multiple new subscriber devices with multiple ports 11.

[0128] (Variation 2 of the Second Embodiment) In the optical communication system 1b, the first optical multiplexing / demultiplexing unit 20, the second optical multiplexing / demultiplexing unit 30, the optical distribution unit 40-1, the wavelength multiplexing / demultiplexing unit 50-1, and the control unit 81-1 may be configured as an optical communication device. Similarly, the first optical multiplexing / demultiplexing unit 60, the second optical multiplexing / demultiplexing unit 70, the optical distribution unit 40-2, the wavelength multiplexing / demultiplexing unit 50-2, and the control unit 81-2 may be configured as an optical communication device.

[0129] (Variation 3 of the Second Embodiment) In the above-described embodiment, the configuration in which the light detection unit 43 is provided inside the light distribution unit 40 has been described, but the light detection unit 43 may be provided outside the light distribution unit 40. The specific processing is as described in the first embodiment.

[0130] (Variation 1 common to the first and second embodiments) The first and second embodiments may be combined to form an optical communication system including the subscriber device 10 shown in FIG. 1 and a subscriber device 10b including a plurality of ports 11.

[0131] (Variation 2 common to the first and second embodiments) In each of the above-described embodiments, when a new subscriber device is connected, if a main signal light is being output from a subscriber device 10 for which an optical path has already been opened, the subscriber device management and control unit 83-1 may generate a control signal including an instruction to increase or decrease the power of the main signal light or an instruction to change the wavelength of the main signal light in addition to an instruction to output the main signal light. The instruction to increase or decrease the power of the main signal light is an instruction to increase or decrease the power of the main signal light output by the new subscriber device.

[0132] (Third embodiment) In the third embodiment, a configuration will be described in which, in a configuration in which the subscriber device management control unit of the management control device has multiple control ports, it is possible to recognize to which port of the optical distribution unit 40 a new subscriber device is connected via an optical transmission path.

[0133] 9 is a diagram illustrating an example of the configuration of an optical communication system 1c according to the third embodiment. The optical communication system 1c includes a plurality of subscriber devices 10 (e.g., subscriber devices 10-1 to 10-3), a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing / demultiplexing units 20 (e.g., first optical multiplexing / demultiplexing units 20-1 to 20-3), a plurality of optical distribution units 40 (e.g., optical distribution units 40-1 to 40-2), a plurality of wavelength multiplexing / demultiplexing units 50 (e.g., wavelength multiplexing / demultiplexing units 50-1 to 50-2), a plurality of first optical multiplexing / demultiplexing units 60 (e.g., first optical multiplexing / demultiplexing units 60-1 to 60-3), and a management and control device 80c. In the third embodiment, an example will be described in which a subscriber device 10 transmits an optical signal and a subscriber device 15 receives the optical signal transmitted from the subscriber device 10.

[0134] In the following description, the direction from the subscriber devices 10 and 15 toward the management control device 80c is referred to as the upstream direction, and the direction from the management control device 80c toward the subscriber devices 10 and 15 is referred to as the downstream direction. The numbers of subscriber devices 10, 15, first optical multiplexing / demultiplexing units 20 and 60, optical distribution units 40, and wavelength multiplexing / demultiplexing units 50 included in the optical communication system 1c are not limited to the numbers shown in FIG.

[0135] Optical transmission paths are used to connect the subscriber device 10 and the first optical multiplexing / demultiplexing unit 20, between the first optical multiplexing / demultiplexing unit 20 and the management and control device 80c, between the first optical multiplexing / demultiplexing unit 20 and the optical distribution unit 40-1, between the optical distribution unit 40-1 and the wavelength multiplexing / demultiplexing unit 50-1, between the wavelength multiplexing / demultiplexing unit 50-1 and the wavelength multiplexing / demultiplexing unit 50-2, between the wavelength multiplexing / demultiplexing unit 50-2 and the optical distribution unit 40-2, between the optical distribution unit 40-2 and the first optical multiplexing / demultiplexing unit 60, between the first optical multiplexing / demultiplexing unit 60 and the subscriber device 15, and between the first optical multiplexing / demultiplexing unit 60 and the management and control device 80c. The optical transmission paths are, for example, optical fibers. The optical communication network 75 is configured between the wavelength multiplexing / demultiplexing unit 50-1 and the wavelength multiplexing / demultiplexing unit 50-2.

[0136] The optical communication system 1c differs in configuration from the optical communication system 1 in that it includes a management control device 80c instead of the management control device 80. The other configurations of the optical communication system 1c are the same as those of the optical communication system 1. The following description will focus on the differences from the optical communication system 1.

[0137] The management control device 80c controls at least the subscriber devices 10 and 15 and the optical distribution unit 40. The management control device 80c includes a plurality of control units 81c (e.g., control units 81c-1 to 81c-2). Each control unit 81c controls each optical distribution unit 40 and the subscriber devices 10 and 15 accommodated in each optical distribution unit 40. For example, the control unit 81c-1 controls the optical distribution unit 40-1 and the subscriber device 10 accommodated in the optical distribution unit 40-1. For example, the control unit 81c-2 controls the optical distribution unit 40-2 and the subscriber device 15 accommodated in the optical distribution unit 40-2.

[0138] The control unit 81c-1 includes an optical distribution control unit 82-1 and a subscriber device management control unit 83c-1, and the control unit 81c-2 includes an optical distribution control unit 82-2 and a subscriber device management control unit 83c-2.

[0139] The optical distribution control unit 82-1 sets the route of the optical path by setting and switching the connection between the ports of the optical distribution unit 40-1. The optical distribution control unit 82-1 controls the connection between the ports of the optical distribution unit 40-1 so as to connect, for example, the port 41-1-p (1≦p≦P) where the optical main signal is detected by the optical detection unit 43-1 with the port 42-1-q (1≦q≦Q) to which the subscriber device 15, which will be the communication partner of the new subscriber device, is connected.

[0140] In this embodiment, the optical distribution control unit 82-1 recognizes the port 41-1-p of the optical distribution unit 40-1 to which the new subscriber device is connected based on the result of the association by the subscriber device management control unit 83c-1. Then, the optical distribution control unit 82-1 controls the connection between the ports of the optical distribution unit 40-1 so as to connect the recognized port 41-1-p with the port 42-1-q (1≦q≦Q) to which the subscriber device 15, which will be the communication partner of the new subscriber device, is connected.

[0141] The subscriber equipment management and control unit 83c-1 has multiple control ports 84-1. While FIG. 9 illustrates an example in which the subscriber equipment management and control unit 83c-1 has three control ports 84-1-1 to 84-1-3, the number of control ports 84-1 of the subscriber equipment management and control unit 83c-1 is not particularly limited. A different first optical multiplexing and demultiplexing unit 20 is connected to each control port 84-1 of the subscriber equipment management and control unit 83c-1. In the example shown in FIG. 9, the control port 84-1-1 is connected to the first optical multiplexing and demultiplexing unit 20-1 via an optical transmission line, the control port 84-1-2 is connected to the first optical multiplexing and demultiplexing unit 20-2 via an optical transmission line, and the control port 84-1-3 is connected to the first optical multiplexing and demultiplexing unit 20-3 via an optical transmission line.

[0142] When a new subscriber device is connected to the optical distribution unit 40-1, the upstream control signal light transmitted from the new subscriber device is input to one of the control ports 84-1 of the subscriber device management and control unit 83c-1. The subscriber device management and control unit 83c-1 performs a new subscriber device connection port identification process based on the upstream control signal light input to one of the control ports 84-1 of the subscriber device management and control unit 83-1.

[0143] The new subscriber device connection port identification process performed by the subscriber device management control unit 83c-1 is a process for identifying the port 41-1 of the optical distribution unit 40-1 to which the new subscriber device is to be connected. The new subscriber device connection port identification process is performed by the following six steps.

[0144] (First step) Detect the control port 84-1 that has been linked up by the input of an upstream control signal light. (Second step) Recognize the new subscriber device by exchanging control signal light with the new subscriber device, including information necessary for authentication, registration, and optical path opening. (Third step) Associate the recognized new subscriber device with the control port 84-1 that detected the input of the upstream control signal light. (Fourth step) Send a downstream control signal light that includes an instruction to output the main signal light to the recognized new subscriber device. (Fifth step) Obtain information about the port 41-1 of the optical distribution unit 40-1 where the input of the optical signal was detected by the optical detection unit 43-1. (Sixth step) Associate the recognized new subscriber device with the detected port 41-1 of the optical distribution unit 40-1.

[0145] Using the result of the new subscriber device connection port identification process, the optical distribution control unit 82-1 can set the connection between the ports of the optical distribution unit 40-1 so that the main signal light transmitted by the new subscriber device is forwarded to the subscriber device with which it will communicate. Specifically, the optical distribution control unit 82-1 sets the connection between the ports of the optical distribution unit 40-1 so that the optical distribution unit 40-1 outputs the main signal light transmitted from the new subscriber device to a port on the optical distribution unit 40-1 side of the wavelength multiplexing / demultiplexing unit 50-1 that is connected to a path for transmitting wavelength-multiplexed signal light to a route assigned to the newly opened optical path, and that can forward the light of the wavelength assigned to the newly opened optical path to the path.

[0146] Using the result of the new subscriber device connection port identification process, the subscriber device management control unit 83c-1 can transmit the downstream control signal light addressed to the new subscriber device only from the control port 84-1 connected to the new subscriber device via the optical transmission line and the first optical multiplexing / demultiplexing unit 20. As a result, it is no longer necessary to broadcast the downstream control signal light addressed to all subscriber devices 10 monitored and controlled by the control unit 81c-1 from all control ports 84-1. This makes it possible to avoid an increase in the signal bandwidth of the downstream control signal light.

[0147] Furthermore, the subscriber equipment management and control unit 83c-1 can measure the round-trip propagation time between the new subscriber equipment and the subscriber equipment management and control unit 83c-1 by transmitting and receiving control signal light to and from the new subscriber equipment.

[0148] The control unit 81c-2 performs the same processing as the control unit 81c-1. The light distribution control unit 82-2 included in the control unit 81c-2 sets the route of the optical path by setting and switching the connection between the ports of the light distribution unit 40-2. The light distribution control unit 82-2 controls the connection between the ports of the light distribution unit 40-2 so as to connect, for example, the port to which the subscriber device 15 is connected to the port to which the subscriber device 10, which is the communication partner of the subscriber device 15, is connected.

[0149] The subscriber equipment management and control unit 83c-2 has multiple control ports 84-2. While FIG. 9 illustrates an example in which the subscriber equipment management and control unit 83c-2 has three control ports 84-2-1 to 84-2-3, the number of control ports 84-2 of the subscriber equipment management and control unit 83c-2 is not particularly limited. A different first optical multiplexing and demultiplexing unit 60 is connected to each control port 84-2 of the subscriber equipment management and control unit 83c-2. In the example shown in FIG. 9, the control port 84-2-1 is connected to the first optical multiplexing and demultiplexing unit 60-1 via an optical transmission line, the control port 84-2-2 is connected to the first optical multiplexing and demultiplexing unit 60-2 via an optical transmission line, and the control port 84-2-3 is connected to the first optical multiplexing and demultiplexing unit 60-3 via an optical transmission line. The functions of the control unit 81c may be implemented by one or more processors executing a program.

[0150] (Flow of optical path opening process (part 1) of optical communication system 1c) Figures 10 and 11 are sequence diagrams showing the flow of optical path opening process (part 1) of optical communication system 1c in the third embodiment. Note that in Figures 10 and 11, the explanation will be given assuming that the new subscriber device is subscriber device 10-1.

[0151] Assume that a user connects the subscriber device 10-1 to the optical distribution unit 40-1 via the optical transmission path 85-1. As a result, the subscriber device 10-1 is connected to the optical distribution unit 40-1 via the optical transmission path 85-1 (step S401). The subscriber device 10-1 generates an upstream control signal including instructions requesting authentication, registration, etc. The subscriber device 10-1 converts the generated upstream control signal into an optical signal and transmits it as upstream control signal light (step S402). The upstream control signal light transmitted from the subscriber device 10-1 is input to the first optical multiplexing / demultiplexing unit 20-1. The first optical multiplexing / demultiplexing unit 20-1 branches and outputs the input upstream control signal light. The upstream control signal light branched by the first optical multiplexing / demultiplexing unit 20-1 is input to the control port 84-1-1 of the subscriber device management and control unit 83c-1.

[0152] The subscriber device management and control unit 83c-1 detects the control port 84-1-1 that has been linked up due to the input of the upstream control signal light (step S403). Thereafter, the subscriber device management and control unit 83c-1 exchanges information necessary for opening an optical path with the subscriber device 10-1 (step S404). At this time, the subscriber device management and control unit 83c-1 exchanges information necessary for opening an optical path with the subscriber device 10-1 via the linked-up control port 84-1-1.

[0153] The subscriber device management control unit 83c-1 can also measure the RTT between the subscriber device management control unit 83c-1 and the subscriber device 10-1 while exchanging information necessary to open the optical path. The subscriber device management control unit 83c-1 stores the measured RTT value in association with the identifier of the subscriber device 10-1.

[0154] The subscriber device management control unit 83c-1 recognizes a new subscriber device by exchanging control signal light with the subscriber device 10-1, which includes information necessary for authentication, registration, and optical path opening. The subscriber device management control unit 83c-1 then associates the recognized new subscriber device (subscriber device 10-1) with the control port 84-1 that detected the input of the upstream control signal light (step S405). For example, if the control port 84-1 that detected the input of the upstream control signal light is the control port 84-1-1, the subscriber device management control unit 83c-1 associates the recognized new subscriber device (subscriber device 10-1) with the control port 84-1-1.

[0155] Next, the subscriber device management and control unit 83c-1 generates a control signal instructing the output of the main signal light (step S406). The subscriber device management and control unit 83c-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-1 as a downstream control signal light (step S407). At this time, the subscriber device management and control unit 83c-1 associates the new subscriber device (subscriber device 10-1) with the control port 84-1-1, so the downstream control signal light is transmitted via the control port 84-1-1.

[0156] The downstream control signal light transmitted from the subscriber device management and control unit 83c-1 is input to the first optical multiplexing and demultiplexing unit 20-1. The first optical multiplexing and demultiplexing unit 20-1 outputs the input downstream control signal light to the subscriber device 10-1 via the optical transmission path 85. As a result, the subscriber device 10-1 receives the downstream control signal light transmitted from the subscriber device management and control unit 83c-1, which instructs the output of the main signal light.

[0157] In response to receiving the downstream control signal light transmitted from the subscriber device management and control unit 83c-1, the subscriber device 10-1 transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1 (step S408). The subscriber device 10-1 transmits the main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1, for example, immediately after receiving the downstream control signal light or after a predetermined period has elapsed since receiving it. The main signal light transmitted from the subscriber device 10-1 is input to the first optical multiplexing and demultiplexing unit 20-1 via the optical transmission line 85-1.

[0158] The first optical multiplexing / demultiplexing unit 20-1 outputs the input optical main signal to the optical dividing unit 40-1. Because the wavelength of the optical main signal transmitted by the subscriber device 10-1 is within the wavelength range of the input / output ports of the first optical multiplexing / demultiplexing unit 20 that are transmitted from the port on the subscriber device 10 side to the port on the optical dividing unit 40-1 side, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-1 is output to the optical dividing unit 40-1. The optical detector 43-1 of the optical dividing unit 40-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 (step S409). For example, the optical detector 43-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 at port 41-1-1. The optical detector 43-1 transmits a detection result indicating that light has been detected at port 41-1-1 to the control unit 81c-1 (step S410).

[0159] The subscriber device management control unit 83c-1 included in the control unit 81c-1 acquires the detection result transmitted from the optical detection unit 43-1. Based on the acquired detection result, the subscriber device management control unit 83c-1 recognizes the port 41-1 of the optical distribution unit 40-1 to which the new subscriber device (subscriber device 10-1) is connected (step S411). The subscriber device management control unit 83c-1 then associates the port included in the detection result (e.g., port 41-1-1) with the new subscriber device (subscriber device 10-1) recognized in the processing of step S404 (step S412). As a result, the subscriber device management control unit 83c-1 recognizes that the new subscriber device (subscriber device 10-1) is connected to the port included in the detection result (e.g., port 41-1-1).

[0160] The optical subscriber device management and control unit 83c-1 instructs the optical distribution control unit 82-1 to switch the connections between the ports based on the result of the association. The optical distribution control unit 82-1 sets the connection relationships between the ports of the optical distribution unit 40-1 by referring to the result of the association by the optical subscriber device management and control unit 83c-1 (step S413).

[0161] Specifically, the optical distribution control unit 82-1 sets the connection relationship of the optical distribution unit 40-1 so as to connect port 41-1-1 of the optical distribution unit 40-1, to which the subscriber device 10-1 is connected, with port 42-1-2 of the optical distribution unit 40-1, to which the subscriber device 10-1 is communicating (e.g., subscriber device 15-1) is connected. The optical distribution control unit 82-1 generates a control signal for connecting port 41-1-1 and port 42-1-2. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1 (step S414).

[0162] Similarly, the optical distribution control unit 82-2 included in the control unit 81c-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port of the optical distribution unit 40-2 connected to the subscriber device 15-1 with the port of the optical distribution unit 40-2 connected to the optical distribution unit 40-1 connected to the subscriber device 10-1 (step S413). Specifically, the optical distribution control unit 82-2 generates a control signal for connecting the port of the optical distribution unit 40-2 connected to the subscriber device 15-1 with the port of the optical distribution unit 40-2 connected to the optical distribution unit 40-1 connected to the subscriber device 10-1. The optical distribution control unit 82-2 transmits the generated control signal to the optical distribution unit 40-2 (step S414).

[0163] The optical distribution units 40-1 and 40-2 set the connection relationship between the ports based on the control signal transmitted from the management and control device 80c (step S415). As a result, an optical path is opened between the subscriber device 10-1 and the subscriber device 15-1. As a result, communication between the subscriber device 10-1 and the subscriber device 15-1 becomes possible.

[0164] The subscriber device management and control unit 83c-1 may issue transmission permission to each subscriber device 10 for which an optical path has been opened, by referring to the RTT values ​​of the subscriber devices 10 for which an optical path has been opened, so that the main signal light from another subscriber device 10 is not transmitted during the period during which the main signal light transmitted by the subscriber device 10-1 in response to the downstream control signal light can reach the optical distribution unit 40-1. Here, the period during which the main signal light transmitted by the subscriber device 10-1 in response to the downstream control signal light can reach the optical distribution unit 40-1 is set in advance. With this method, the subscriber device management and control unit 83c-1 recognizes the port where light is detected by the optical detection unit 43 as the port to which the new subscriber device will be connected, while optical detection is stopped at the port of the optical distribution unit 40 to which the subscriber device 10 for which an optical path has been opened is connected. This makes it possible to prevent optical signals other than the main signal light transmitted from the subscriber device 10-1 from being input to the optical distribution unit 40-1. As a result, it is possible to avoid incorrect association in the subscriber device management and control unit 83-1.

[0165] (Flow of optical path establishment process (part 2) in optical communication system 1) In Fig. 10 and Fig. 11, the flow of optical path establishment process when there is one new subscriber device has been described. Therefore, the flow of optical path establishment process when there are multiple new subscriber devices will be described using Fig. 12 to Fig. 14. Fig. 12 to Fig. 14 are sequence diagrams showing the flow of optical path establishment process (part 2) in optical communication system 1c in the third embodiment. Note that Fig. 12 to Fig. 14 will be described assuming that the new subscriber devices are subscriber devices 10-1 and 10-2.

[0166] Assume that a first user connects the subscriber device 10-1 to the optical distribution unit 40-1 via the optical transmission path 85-1. As a result, the subscriber device 10-1 is connected to the optical distribution unit 40-1 via the optical transmission path 85-1 (step S501). The subscriber device 10-1 generates an upstream control signal including instructions requesting authentication, registration, etc. The subscriber device 10-1 converts the generated upstream control signal into an optical signal and transmits it as upstream control signal light (step S502). The upstream control signal light transmitted from the subscriber device 10-1 is input to the first optical multiplexing / demultiplexing unit 20-1. The first optical multiplexing / demultiplexing unit 20-1 branches and outputs the input upstream control signal light. The upstream control signal light branched by the first optical multiplexing / demultiplexing unit 20-1 is input to the control port 84-1-1 of the subscriber device management and control unit 83c-1.

[0167] The subscriber device management and control unit 83c-1 detects the control port 84-1-1 that has been linked up due to the input of the upstream control signal light (step S503). Thereafter, the subscriber device management and control unit 83c-1 exchanges information necessary for opening an optical path with the subscriber device 10-1 (step S504). At this time, the subscriber device management and control unit 83c-1 exchanges information necessary for opening an optical path with the subscriber device 10-1 via the linked-up control port 84-1-1.

[0168] The subscriber device management control unit 83c-1 may measure the RTT between the subscriber device management control unit 83c-1 and the subscriber device 10-1 while exchanging information necessary for opening the optical path. The subscriber device management control unit 83c-1 stores the measured RTT value in association with the identifier of the subscriber device 10-1.

[0169] The subscriber device management and control unit 83c-1 recognizes the first new subscriber device by exchanging control signal light with the subscriber device 10-1, which includes information necessary for authentication, registration, and optical path opening. The subscriber device management and control unit 83c-1 then associates the recognized first new subscriber device (subscriber device 10-1) with the control port 84-1 that detected the input of the upstream control signal light (step S505). For example, since the control port 84-1 that detected the input of the upstream control signal light is the control port 84-1-1, the subscriber device management and control unit 83c-1 associates the recognized first new subscriber device (subscriber device 10-1) with the control port 84-1-1.

[0170] Assume that a second user connects the subscriber device 10-2 to the optical distribution unit 40-1 via the optical transmission path 85-2. As a result, the subscriber device 10-2 is connected to the optical distribution unit 40-1 via the optical transmission path 85-2 (step S506). The subscriber device 10-2 generates an upstream control signal including instructions requesting authentication, registration, etc. The subscriber device 10-2 converts the generated upstream control signal into an optical signal and transmits it as upstream control signal light (step S507). The upstream control signal light transmitted from the subscriber device 10-2 is input to the first optical multiplexing / demultiplexing unit 20-2. The first optical multiplexing / demultiplexing unit 20-2 branches and outputs the input upstream control signal light. The upstream control signal light branched by the first optical multiplexing / demultiplexing unit 20-2 is input to the control port 84-1-2 of the subscriber device management and control unit 83c-1.

[0171] The subscriber device management and control unit 83c-1 detects the control port 84-1-2 that has been linked up due to the input of the upstream control signal light (step S508). Thereafter, the subscriber device management and control unit 83c-1 exchanges information necessary for opening an optical path with the subscriber device 10-2 (step S509). At this time, the subscriber device management and control unit 83c-1 exchanges information necessary for opening an optical path with the subscriber device 10-2 via the linked-up control port 84-1-2.

[0172] The subscriber device management control unit 83c-1 may measure the RTT between the subscriber device management control unit 83c-1 and the subscriber device 10-2 while exchanging information necessary for opening the optical path. The subscriber device management control unit 83c-1 stores the measured RTT value in association with the identifier of the subscriber device 10-2.

[0173] The subscriber device management and control unit 83c-1 recognizes the second new subscriber device by exchanging control signal light with the subscriber device 10-2, including information necessary for authentication, registration, and optical path opening. The subscriber device management and control unit 83c-1 then associates the recognized second new subscriber device (subscriber device 10-2) with the control port 84-1 that detected the input of the upstream control signal light (step S510). For example, since the control port 84-1 that detected the input of the upstream control signal light is the control port 84-1-2, the subscriber device management and control unit 83c-1 associates the recognized second new subscriber device (subscriber device 10-2) with the control port 84-1-2.

[0174] The subscriber device management and control unit 83c-1 generates a control signal instructing the output of the main signal light (step S511). The subscriber device management and control unit 83c-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-1 as a downstream control signal light (step S512). Note that the subscriber device management and control unit 83c-1 associates the first new subscriber device (subscriber device 10-1) with the control port 84-1-1, and therefore transmits the downstream control signal light via the control port 84-1-1.

[0175] The downstream control signal light transmitted from the subscriber device management and control unit 83c-1 is input to the first optical multiplexing and demultiplexing unit 20-1. The first optical multiplexing and demultiplexing unit 20-1 outputs the input downstream control signal light to the subscriber device 10-1 via the optical transmission path 85-1. As a result, the subscriber device 10-1 receives the downstream control signal light transmitted from the subscriber device management and control unit 83c-1, which instructs the output of the main signal light.

[0176] In response to receiving the downstream control signal light transmitted from the subscriber device management and control unit 83c-1, the subscriber device 10-1 transmits the main signal light of the wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1 (step S513). The subscriber device 10-1 transmits the main signal light of the wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1, for example, immediately after receiving the downstream control signal light or after a predetermined period has elapsed since receiving it. The main signal light transmitted from the subscriber device 10-1 is input to the first optical multiplexing and demultiplexing unit 20-1 via the optical transmission line 85-1.

[0177] The first optical multiplexing / demultiplexing unit 20-1 outputs the input optical main signal to the optical dividing unit 40-1. Because the wavelength of the optical main signal transmitted by the subscriber device 10-1 is within the wavelength range of the input / output ports of the first optical multiplexing / demultiplexing unit 20-1 that are transmitted from the port on the subscriber device 10 side to the port on the optical dividing unit 40-1 side, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-1 is output to the optical dividing unit 40-1. The optical detector 43-1 of the optical dividing unit 40-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 (step S514). For example, the optical detector 43-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-1 at port 41-1-1. The optical detector 43-1 transmits a detection result indicating that light has been detected at port 41-1-1 to the control unit 81c-1 (step S515).

[0178] The subscriber device management control unit 83c-1 included in the control unit 81c-1 acquires the detection result transmitted from the optical detection unit 43-1. Based on the acquired detection result, the subscriber device management control unit 83c-1 recognizes the port 41-1 of the optical distribution unit 40-1 to which the first new subscriber device (subscriber device 10-1) is connected (step S516). The subscriber device management control unit 83c-1 then associates the port included in the detection result (e.g., port 41-1-1) with the first new subscriber device (subscriber device 10-1) recognized in the processing of step S504 (step S517). As a result, the subscriber device management control unit 83c-1 recognizes that the first new subscriber device (subscriber device 10-1) is connected to the port included in the detection result (e.g., port 41-1-1).

[0179] The optical subscriber device management and control unit 83c-1 instructs the optical distribution control unit 82-1 to switch the connections between the ports based on the result of the association. The optical distribution control unit 82-1 sets the connection relationships between the ports of the optical distribution unit 40-1 by referring to the result of the association by the optical subscriber device management and control unit 83c-1 (step S518).

[0180] Specifically, the optical distribution control unit 82-1 sets the connection relationship of the optical distribution unit 40-1 so as to connect port 41-1-1 of the optical distribution unit 40-1, to which the subscriber device 10-1 is connected, with port 42-1-2 of the optical distribution unit 40-1, to which the subscriber device 10-1 is communicating (e.g., subscriber device 15-1) is connected. The optical distribution control unit 82-1 generates a control signal for connecting port 41-1-1 and port 42-1-2. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1 (step S519).

[0181] Similarly, the optical distribution control unit 82-2 included in the control unit 81c-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port of the optical distribution unit 40-2 connected to the subscriber device 15-1 with the port of the optical distribution unit 40-2 connected to the optical distribution unit 40-1 connected to the subscriber device 10-1 (step S518). Specifically, the optical distribution control unit 82-2 generates a control signal for connecting the port of the optical distribution unit 40-2 connected to the subscriber device 15-1 with the port of the optical distribution unit 40-2 connected to the optical distribution unit 40-1 connected to the subscriber device 10-1. The optical distribution control unit 82-2 transmits the generated control signal to the optical distribution unit 40-2 (step S519).

[0182] The optical distribution units 40-1 and 40-2 set the connection relationship between the ports based on the control signal transmitted from the management and control device 80c (step S520). This opens an optical path between the subscriber device 10-1 and the subscriber device 15-1. As a result, communication becomes possible between the subscriber device 10-1 and the subscriber device 15-1.

[0183] Thereafter, the subscriber device management and control unit 83c-1 again generates a downstream control signal that instructs the output of the optical main signal (step S521). The subscriber device management and control unit 83c-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-2 as a downstream control signal (step S522). Note that the subscriber device management and control unit 83c-1 associates the second new subscriber device (subscriber device 10-2) with the control port 84-1-2, so it transmits the downstream control signal via the control port 84-1-2.

[0184] The downstream control signal light transmitted from the subscriber device management and control unit 83c-1 is input to the first optical multiplexing and demultiplexing unit 20-2. The first optical multiplexing and demultiplexing unit 20-2 outputs the input downstream control signal light to the subscriber device 10-2 via the optical transmission path 85-2. As a result, the subscriber device 10-2 receives the downstream control signal light transmitted from the subscriber device management and control unit 83c-1, which instructs the output of the main signal light.

[0185] In response to receiving the downstream control signal light transmitted from the subscriber device management and control unit 83c-1, the subscriber device 10-2 transmits the main signal light of the wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-2 (step S523). The subscriber device 10-2 transmits the main signal light of the wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-2, for example, immediately after receiving the downstream control signal light or after a predetermined period has elapsed since receiving it. The main signal light transmitted from the subscriber device 10-2 is input to the first optical multiplexing and demultiplexing unit 20-2 via the optical transmission line 85-2.

[0186] The first optical multiplexing / demultiplexing unit 20-2 outputs the input optical main signal to the optical dividing unit 40-1. Because the wavelength of the optical main signal transmitted by the subscriber device 10-2 is within the wavelength range of the input / output ports of the first optical multiplexing / demultiplexing unit 20-2 that are transmitted from the port on the subscriber device 10 side to the port on the optical dividing unit 40-1 side, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-2 is output to the optical dividing unit 40-1. The optical detector 43-1 of the optical dividing unit 40-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-2 (step S524). For example, the optical detector 43-1 detects the optical main signal output from the first optical multiplexing / demultiplexing unit 20-2 at port 41-1-2. The optical detector 43-1 transmits a detection result indicating that light has been detected at port 41-1-2 to the control unit 81c-1 (step S525).

[0187] The subscriber device management control unit 83c-1 included in the control unit 81c-1 acquires the detection result transmitted from the optical detection unit 43-1. Based on the acquired detection result, the subscriber device management control unit 83c-1 recognizes the port 41-1 of the optical distribution unit 40-1 to which the second new subscriber device (subscriber device 10-2) is connected (step S526). The subscriber device management control unit 83c-1 then associates the port included in the detection result (e.g., port 41-1-2) with the second new subscriber device (subscriber device 10-2) recognized in the processing of step S509 (step S527). As a result, the subscriber device management control unit 83c-1 recognizes that the second new subscriber device (subscriber device 10-2) is connected to the port included in the detection result (e.g., port 41-1-2).

[0188] The optical subscriber device management and control unit 83c-1 instructs the optical distribution control unit 82-1 to switch the connections between the ports based on the result of the association. The optical distribution control unit 82-1 sets the connection relationships between the ports of the optical distribution unit 40-1 by referring to the result of the association by the optical subscriber device management and control unit 83c-1 (step S528).

[0189] Specifically, the optical distribution control unit 82-1 sets the connection relationship of the optical distribution unit 40-1 so as to connect port 41-1-2 of the optical distribution unit 40-1, to which the subscriber device 10-2 is connected, with port 42-1-3 of the optical distribution unit 40-1, which is connected to the subscriber device 15 (e.g., subscriber device 15-2), with which the subscriber device 10-2 is communicating. The optical distribution control unit 82-1 generates a control signal for connecting port 41-1-1 and port 42-1-3. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1 (step S529).

[0190] Similarly, the optical distribution control unit 82-2 included in the control unit 81c-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port of the optical distribution unit 40-2 connected to the subscriber device 15-2 with the port of the optical distribution unit 40-2 connected to the optical distribution unit 40-1 connected to the subscriber device 10-2 (step S528). Specifically, the optical distribution control unit 82-2 generates a control signal for connecting the port of the optical distribution unit 40-2 connected to the subscriber device 15-2 with the port of the optical distribution unit 40-2 connected to the optical distribution unit 40-1 connected to the subscriber device 10-2. The optical distribution control unit 82-2 transmits the generated control signal to the optical distribution unit 40-2 (step S529).

[0191] The optical distribution units 40-1 and 40-2 set the connection relationship between the ports based on the control signal transmitted from the management and control device 80c (step S530). As a result, an optical path is opened between the subscriber device 10-2 and the subscriber device 15-2. As a result, communication becomes possible between the subscriber device 10-1 and the subscriber device 15-1.

[0192] 12 to 14, the description is given of the flow in which, after an optical path between one new subscriber device and the communication partner is opened, the subscriber device management and control unit 83c-1 transmits downstream control signal light to the other new subscriber devices. Here, since it is sufficient for the subscriber device management and control unit 83c-1 to recognize the port to which the new subscriber device is connected, the subscriber device management and control unit 83c-1 may execute the process of step S521 after completing the process of step S517. That is, the subscriber device management and control unit 83c-1 may recognize the port to which the subscriber device 10-1, newly connected to the optical distribution unit 40-1, is connected, and then transmit a downstream control signal light to the subscriber device 10-2 instructing it to output at least the main signal light. In this case, after recognizing the ports to which each of the multiple new subscriber devices is connected, the subscriber device management and control unit 83c-1 instructs the optical distribution control unit 82-1 to control the connection between the ports of the optical distribution unit 40. In this specification, the subscriber device management and control unit 83c-1 may sequentially set the inter-port connections of the optical distribution unit 40 for each optical path.

[0193] 12 to 14, the subscriber device management control unit 83c-1 may refer to the RTT values ​​of the subscriber devices 10 for which an optical path has been opened and issue a transmission permission to each of the subscriber devices 10 for which an optical path has been opened, so that the main signal light from another subscriber device 10 is not transmitted during the period in which the main signal light transmitted by the subscriber device 10-1 or 10-2 in response to the downstream control signal light can reach the optical distribution unit 40-1. This makes it possible to prevent optical signals other than the main signal light transmitted from the subscriber device 10-1 or 10-2 from being input to the optical distribution unit 40-1. As a result, it is possible to prevent incorrect association in the subscriber device management control unit 83c-1.

[0194] 12 to 14, when there are multiple new subscriber devices, there is a restriction that until processing for one new subscriber device is completed, at least a downstream control signal light instructing the other new subscriber devices to output the main signal light is not transmitted. In contrast, by further including information indicating the transmission timing of the main signal light in the downstream control signal light instructing the output of the main signal light, it is possible to control the transmission timing of the main signal light of each new subscriber device without imposing any restriction.

[0195] The flow of the optical path opening process in such a configuration will be described using Figures 15 to 17. Figures 15 to 17 are sequence diagrams showing the flow of the optical path opening process (part 3) of the optical communication system 1c in the third embodiment. Note that in Figures 15 to 17, the explanation will be given assuming that the new subscriber devices are subscriber devices 10-1 and 10-2. In Figures 15 to 17, the same processes as in Figures 12 to 14 are assigned the same reference numerals as in Figures 12 to 14, and the explanation will be omitted.

[0196] After the processes from step S501 to step S510 are completed, the subscriber device management and control unit 83c-1 generates a control signal including an instruction to output the optical main signal and information indicating the timing of transmission of the optical main signal by the subscriber device 10-1 (step S601). The subscriber device management and control unit 83c-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-1 as a downstream control signal (step S602). Note that, since the subscriber device management and control unit 83c-1 associates the first new subscriber device (subscriber device 10-1) with the control port 84-1-1, the subscriber device management and control unit 83c-1 transmits the downstream control signal via the control port 84-1-1.

[0197] The downstream control signal light transmitted from the subscriber device management and control unit 83c-1 is input to the first optical multiplexing and demultiplexing unit 20-1. The first optical multiplexing and demultiplexing unit 20-1 outputs the input downstream control signal light to the subscriber device 10-1 via the optical transmission path 85-1. As a result, the subscriber device 10-1 receives the downstream control signal light transmitted from the subscriber device management and control unit 83c-1.

[0198] The subscriber device 10-1 waits until the transmission timing indicated by the control signal included in the downstream control signal transmitted from the subscriber device management and control unit 83c-1. After the processing of step S602, the subscriber device management and control unit 83c-1 generates a control signal including an instruction to output the main signal light and information indicating the transmission timing of the main signal light by the subscriber device 10-2 (step S603). Here, the subscriber device management and control unit 83c-1 determines the transmission timing so that the transmission timing of the main signal light by the subscriber device 10-1 does not overlap with the transmission timing of the main signal light by the subscriber device 10-2. Preferably, the subscriber device management and control unit 83c-1 determines the transmission timing of the main signal light by the subscriber device 10-2 so that the period during which the main signal light transmitted by the subscriber device 10-1 in response to the downstream control signal can reach the optical distribution unit 40-1 does not overlap with the period during which the main signal light transmitted by the subscriber device 10-2 in response to the downstream control signal can reach the optical distribution unit 40-1.

[0199] The subscriber device management and control unit 83c-1 converts the generated control signal into an optical signal and transmits it to the subscriber device 10-2 as a downstream control signal light (step S604). Note that the subscriber device management and control unit 83c-1 associates the second new subscriber device (subscriber device 10-2) with the control port 84-1-2, so it transmits the downstream control signal light via the control port 84-1-2.

[0200] The downstream control signal light transmitted from the subscriber device management and control unit 83c-1 is input to the first optical multiplexing and demultiplexing unit 20-2. The first optical multiplexing and demultiplexing unit 20-2 outputs the input downstream control signal light to the subscriber device 10-2 via the optical transmission path 85-2. As a result, the subscriber device 10-2 receives the downstream control signal light transmitted from the subscriber device management and control unit 83c-1.

[0201] The subscriber device 10-2 waits until the transmission timing indicated by the control signal included in the downstream control signal transmitted from the subscriber device management and control unit 83c-1. When the transmission timing indicated by the control signal included in the received downstream control signal arrives, the subscriber device 10-1 transmits the main signal light of the wavelength that will reach the optical distribution unit 40-1 to the optical transmission path 85-1 (step S605). The main signal light transmitted from the subscriber device 10-1 is input to the first optical multiplexing and demultiplexing unit 20-1 via the optical transmission path 85-1. The first optical multiplexing and demultiplexing unit 20-1 outputs the input main signal light to the optical distribution unit 40-1. Since the wavelength of the main signal light transmitted by the subscriber device 10-1 is within the wavelength range that is transmitted from the port on the subscriber device 10-1 side to the port on the optical distribution unit 40-1 side among the input / output ports of the first optical multiplexing and demultiplexing unit 20-1, the main signal light input to the first optical multiplexing and demultiplexing unit 20-1 is output to the optical distribution unit 40-1. Thereafter, the processes from step S514 to step S520 are executed.

[0202] When the transmission timing indicated by the control signal included in the received downstream control signal arrives, the subscriber device 10-2 transmits the optical main signal having the wavelength reaching the optical distribution unit 40-1 to the optical transmission path 85-2 (step S606). The optical main signal transmitted from the subscriber device 10-2 is input to the first optical multiplexing / demultiplexing unit 20-2 via the optical transmission path 85-2. The first optical multiplexing / demultiplexing unit 20-2 outputs the input optical main signal to the optical distribution unit 40-1. Since the wavelength of the optical main signal transmitted by the subscriber device 10-2 is within the wavelength range transmitted from the port on the subscriber device 10-2 side to the port on the optical distribution unit 40-1 side among the input / output ports of the first optical multiplexing / demultiplexing unit 20-2, the optical main signal input to the first optical multiplexing / demultiplexing unit 20-2 is output to the optical distribution unit 40-1. Then, the processes from step S524 to step S530 are executed.

[0203] 15 to 17, the subscriber device management and control unit 83c-1 may refer to the RTT values ​​of the subscriber devices 10 for which an optical path has been opened and issue a transmission permission to each of the subscriber devices 10 for which an optical path has been opened, so that the main signal light from another subscriber device 10 is not transmitted during the period in which the main signal light transmitted by the subscriber device 10-1 or 10-2 in response to the downstream control signal light can reach the optical distribution unit 40-1. This makes it possible to prevent optical signals other than the main signal light transmitted from the subscriber device 10-1 or 10-2 from being input to the optical distribution unit 40-1. As a result, it is possible to prevent incorrect association in the subscriber device management and control unit 83-1.

[0204] According to the optical communication system 1c configured as described above, when the subscriber device management control unit 83 has multiple control ports 84, even when a new subscriber device 10 is connected, it is possible to recognize to which port 41-1 of the optical distribution unit 40-1 the newly connected subscriber device 10 is connected via the optical transmission path. As a result, the optical distribution control unit 82 can set the inter-port connection of the optical distribution unit 40 so that the main signal light transmitted from the newly connected subscriber device 10 is transferred to the subscriber device 15 with which it is communicating, thereby opening a new optical path.

[0205] In the optical communication system 1c, the subscriber device management and control unit 83c-1 executes six steps as a new subscriber device connection port identification process. However, at least the correspondence process in the third step may not be performed. Here, the process of the subscriber device management and control unit 83c-1 is described as an example, but the process is similar for the subscriber device management and control unit 83c-2. Specifically, as shown in the first step, the subscriber device management and control unit 83c-1 first detects the linked-up control port 84-1 by receiving an upstream control signal transmitted from the new subscriber device. Next, as shown in the second step, the subscriber device management and control unit 83c-1 recognizes the new subscriber device by exchanging control signal light with the new subscriber device, including information necessary for authentication, registration, and optical path opening. Next, as shown in the fourth step, the subscriber device management and control unit 83c-1 transmits a downstream control signal light including an instruction to output the main signal light to the recognized new subscriber device. Note that the downstream control signal light includes identification information for identifying the new subscriber device. The subscriber device management and control unit 83c-1 may transmit downstream control signal light from all control ports 84-1, or may transmit downstream control signal light from the specific control port 84-1 detected in (the first step).

[0206] Through the above process, the new subscriber device receives the downstream control signal light and transmits the main signal light in response to the received downstream control signal light. The main signal light transmitted from the new subscriber device is detected by the optical detector 43-1 of the optical distribution unit 40-1. As shown in (step 5), the subscriber device management and control unit 83c-1 acquires information about the port 41-1 of the optical distribution unit 40-1 at which the input of the optical signal was detected. Then, as shown in (step 6), the subscriber device management and control unit 83c-1 associates the new subscriber device recognized in (step 2) with the port 41-1 of the optical distribution unit 40-1 included in the information acquired in (step 5). In this way, in the optical communication system 1c, by associating the subscriber device 10, which is the destination of the downstream control signal light including an instruction to output the main signal light, with the port 41-1 of the optical distribution unit 40-1 at which the input of the optical signal was detected, it becomes possible to recognize to which port 41-1 of the optical distribution unit 40-1 the newly connected subscriber device 10 is connected via the optical transmission path. Therefore, when opening an optical path that connects a newly connected subscriber device and a subscriber device that will be the communication partner, as in the above-described embodiment, it is not necessary to physically link the control port that is linked up by the input of upstream control signal light with the new subscriber device that is recognized through the exchange of control signal light.Since the control port is not physically managed, if there is an abnormality in the control port, it can be quickly disseminated by simply switching to another control port.In addition, the transfer of control signals in the subscriber device management control units 83c-1 and 83c-2 can use, for example, VID (Virtual LAN IDentifier).

[0207] 9, when the subscriber device management and control unit 83c-1 has multiple control ports 84-1, the following problem may occur. Specifically, in order for the downstream control signal light sent by the subscriber device management and control unit 83c-1 to reach the subscriber device 10 that is the destination of the downstream control signal light, the downstream control signal light must be sent from at least one of the multiple control ports 84-1 included in the subscriber device management and control unit 83c-1, the control port 84-1 connected to the destination subscriber device 10 via the optical transmission line and the first optical multiplexing and demultiplexing unit 20. If the control unit 81c-1 cannot recognize the control port 84-1 of the subscriber device management and control unit 83c-1 that is connected to the subscriber device 10 that is the destination of the downstream control signal light via the optical transmission line and the first optical multiplexing and demultiplexing unit 20, the subscriber device management and control unit 83c-1 must send the downstream control signal light addressed to that subscriber device 10 from all of the control ports 84-1 in order to ensure that the downstream control signal light reaches the destination subscriber device 10.

[0208] Therefore, in the configuration shown in FIG. 9 , downstream control signal light addressed to all of the subscriber devices 10 monitored and controlled by the subscriber device management and control unit 83c-1 must be broadcast from all control ports 84-1, which may result in an increase in the signal bandwidth of the downstream control signal light. The same applies to the subscriber device management and control unit 83c-2. To address this problem, the optical communication system 1c of the third embodiment identifies the control port 84-1 or 84-2 to which the new subscriber device is connected by associating the control port 84-1 or 84-2 linked up by the input of the upstream control signal light with the new subscriber device recognized through the exchange of control signal light. This allows the subscriber device management and control units 83c-1 or 83c-2 to transmit downstream control signal light addressed to the subscriber devices 10 that it monitors and controls from the identified control port 84-1 or 84-2. Therefore, the subscriber device management and control units 83c-1 or 83c-2 do not need to broadcast downstream control signal light addressed to the subscriber devices 10 that it monitors and controls from all control ports 84-1 or 84-2. Therefore, it is possible to avoid an increase in the signal band of the downstream control signal light.

[0209] 9 is a configuration in which the optical main signal transmitted from the subscriber unit 10 to the subscriber unit 15 and the optical main signal transmitted from the subscriber unit 15 to the subscriber unit 10 flow through the core wire of the same optical transmission line. In contrast, a configuration may be adopted in which there are sections in which the optical main signal transmitted from the subscriber unit 10 to the subscriber unit 15 and the optical main signal transmitted from the subscriber unit 15 to the subscriber unit 10 flow through core wires of different optical transmission lines.

[0210] 18 is a diagram illustrating an example of the configuration of an optical communication system 1d according to a first modification of the third embodiment. The optical communication system 1d includes a plurality of subscriber devices 10 (e.g., subscriber devices 10-1 to 10-3), a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing / demultiplexing units 20 (e.g., first optical multiplexing / demultiplexing units 20-1 to 20-3), a plurality of optical distribution units 40 (e.g., optical distribution units 40-1 to 40-2), a plurality of first optical multiplexing / demultiplexing units 60 (e.g., first optical multiplexing / demultiplexing units 60-1 to 60-3), and a management and control device 80c. The optical communication system 1d differs in configuration from the optical communication system 1c in that it does not include a wavelength multiplexing / demultiplexing unit 50. The differences from the optical communication system 1c are described below.

[0211] A plurality of optical transmission paths 87-1 and 87-2 are provided between the optical distribution unit 40-1 and the optical distribution unit 40-2. The optical transmission path 87-1 is a transmission path used, for example, when transmitting an optical main signal transmitted from the subscriber device 10 to the subscriber device 15. The optical transmission path 87-2 is a transmission path used, for example, when transmitting an optical main signal transmitted from the subscriber device 15 to the subscriber device 10.

[0212] The optical distribution unit 40-1 is controlled by the optical distribution control unit 82-1 so as to output the main signal light transmitted from each of the subscriber devices 10-1 to 10-3 to the optical transmission path 87-1. For example, the optical distribution control unit 82-1 sets the optical distribution unit 40-1 so that the main signal light transmitted from each of the subscriber devices 10-1 to 10-3 is output to the optical transmission path 87-1 based on the wavelengths assigned to each of the subscriber devices 10-1 to 10-3.

[0213] The optical distribution unit 40-2 is controlled by the optical distribution control unit 82-2 so as to output the main signal light transmitted from each of the subscriber devices 15-1 to 15-3 to the optical transmission path 87-2. For example, the optical distribution control unit 82-2 sets the optical distribution unit 40-2 so that the main signal light transmitted from each of the subscriber devices 15-1 to 15-3 is output to the optical transmission path 87-2 based on the wavelengths assigned to each of the subscriber devices 15-1 to 15-3.

[0214] With the above configuration, main signal light transmitted from different directions can be transmitted via different optical transmission paths.

[0215] As shown in Figure 9, when there is a section in which signal light beams of different directions flow through the core of the same optical transmission line, the subscriber device management and control units 83c-1 and 83c-2 either use different wavelengths for the signal light beams of different directions or issue transmission authorizations to the signal light beams of different directions at different times to prevent deterioration of the reception characteristics of the signal light beams of opposite directions due to reflection in the optical transmission line. As shown in Figure 18, when there is no section in which signal light beams of different directions flow through the core of the same optical transmission line, the wavelengths of the signal light beams of different directions can be the same. Figure 18 shows an example in which multiple optical transmission lines 87-1 and 87-2 are provided between the optical distribution unit 40-1 and the optical distribution unit 40-2, but multiple optical transmission lines may be provided in the section between the subscriber device 10 and the optical distribution unit 40-1 and the section between the subscriber device 15 and the optical distribution unit 40-2 to prevent signal light beams of different directions from flowing through the core of the same optical transmission line.

[0216] (Variation 2 of the Third Embodiment) When the light distribution units 40-1 and 40-2 have a function capable of setting a transmission path for each wavelength, it is possible to eliminate the need for the wavelength multiplexing / demultiplexing unit 50, as shown in Fig. 18. As the light distribution units 40-1 and 40-2 capable of setting a transmission path for each wavelength, for example, a WSS or a multicast switch can be used.

[0217] (Variation 3 of the Third Embodiment) In the optical communication system 1c, the first optical multiplexing / demultiplexing unit 20, the optical distribution unit 40-1, the wavelength multiplexing / demultiplexing unit 50-1, and the control unit 81c-1 may be configured as an optical communication device. Similarly, the first optical multiplexing / demultiplexing unit 60, the optical distribution unit 40-2, the wavelength multiplexing / demultiplexing unit 50-2, and the control unit 81c-2 may be configured as an optical communication device.

[0218] In the optical communication system 1d, the first optical multiplexing / demultiplexing unit 20, the optical distribution unit 40-1, and the control unit 81c-1 may be configured as an optical communication device. Similarly, the first optical multiplexing / demultiplexing unit 60, the optical distribution unit 40-2, and the control unit 81c-2 may be configured as an optical communication device.

[0219] (Variation 4 of the Third Embodiment) In the above-described embodiment, a configuration has been shown in which the light detection unit 43 is provided inside the light distribution unit 40, but the light detection unit 43 may also be provided outside the light distribution unit 40. In such a configuration, the light distribution unit 40-1 does not include the light detection unit 43-1. The light detection unit 43-1 is connected to port 42-1-1 of the light distribution unit 40-1. Note that the port to which the light detection unit 43-1 is connected may be any of the ports 42-1. Note that the same applies to the light distribution unit 40-2 as to the light distribution unit 40-1.

[0220] The optical distribution unit 40-1 switches the connection relationship between ports in accordance with the control of the optical distribution control unit 82-1 so that each port 41-1 to which an optical path has not yet been established is sequentially connected to the port 42-1-1 to which the optical detection unit 43-1 is connected. The optical detection unit 43-1 detects an optical signal output from the connected port 42-1-1. When the optical detection unit 43-1 detects an optical signal, it notifies the management control device 80c of the detection result indicating that an optical signal has been detected.

[0221] The configuration and processing of the management control device 80c are basically the same as those of the above-described embodiment. For example, after a downstream control signal light instructing the output of a main signal light is transmitted, the optical distribution control unit 82-1 of the management control device 80c controls the connection relationship between the ports of the optical distribution unit 40-1 so that, among the ports 41-1 of the optical distribution unit 40-1, each port 41-1 for which an optical path has not yet been opened is sequentially connected to the port 42-1-1 to which the optical detection unit 43-1 is connected.

[0222] When the subscriber device management control unit 83c-1 acquires the detection result from the optical detection unit 43-1, it recognizes that the port 41-1 connected to the port 42-1-1 to which the optical detection unit 43-1 is connected at the time of acquiring the detection result is the port to which the newly connected subscriber device 10 is connected.

[0223] With the above configuration, even if the light detection unit 43 is provided outside the light distribution unit 40, the same effects as those of the above-described embodiment can be obtained.

[0224] (Variation 5 of the Third Embodiment) In the third embodiment, when a new subscriber device is connected, if a main signal light is already being output from a subscriber device 10 for which an optical path has already been opened, the subscriber device management and control unit 83c-1 may generate a control signal including an instruction to increase or decrease the power of the main signal light or an instruction to change the wavelength of the main signal light in addition to an instruction to output the main signal light. The instruction to increase or decrease the power of the main signal light is an instruction to increase or decrease the power of the main signal light output by the new subscriber device.

[0225] (Variation 6 of the Third Embodiment) In the above-described embodiment, a configuration has been shown in which the new subscriber device and the control ports 84-1 and 84-2 are associated with each other based on the control ports 84-1 and 84-2 that are linked up by input of an upstream control signal light transmitted from the new subscriber device. The method of associating the new subscriber device with the control ports 84-1 and 84-2 is not limited to this method.

[0226] For example, the subscriber device management control units 83c-1 and 83c-2 may associate the new subscriber device with the control ports 84-1 and 84-2 using a transfer rule list that associates "subscriber device IDs" with "control ports." The transfer rule list is a list that defines transfer rules within the control units 81-1 and 81-2, and is, for example, a MAC address table or an IP routing table. The following describes the new subscriber device connection port identification process when the subscriber device management control unit 83c-1 associates the new subscriber device with the control port 84-1 using the transfer rule list. The new subscriber device connection port identification process in this case is performed by the following six steps.

[0227] (First step) Recognizing a new subscriber device by exchanging control signal light containing information necessary for authentication, registration, and optical path opening with the new subscriber device. (Second step) Detecting the control port 84-1 to which the new subscriber device is connected by referring to the transfer rule list held in the control unit 81c-1. (Third step) Associating the recognized new subscriber device with the detected control port 84-1 based on the transfer rule list. (Fourth step) Sending a downstream control signal light containing an instruction to output the main signal light to the recognized new subscriber device. (Fifth step) Obtaining information on port 41-1 of the optical distribution unit 40-1 where input of an optical signal was detected by the optical detection unit 43-1. (Sixth step) Associating the recognized new subscriber device with the detected port 41-1 of the optical distribution unit 40-1.

[0228] Some of the functional units of the management control devices 80 and 80c in the above-described embodiments may be implemented by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Note that the term "computer system" here includes hardware such as an operating system (OS) and peripheral devices.

[0229] 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).

[0230] Although an embodiment of the present invention has been described above in detail 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.

[0231] The present invention can be applied to a technique for opening an optical path.

[0232] 1, 1a, 1b, 1c, 1d...Optical communication system, 10, 10b, 10-1 to 10-3, 15, 15-1 to 15-3...Subscriber equipment, 20, 20-1 to 20-3, 60, 60-1 to 60-3...First optical multiplexing / demultiplexing section, 30, 70... Second optical multiplexing / demultiplexing section, 40-1, 40-2...Light distribution unit, 43-1...Light detection unit, 50-1, 50-2...Wavelength multiplexing / demultiplexing unit, 80, 80c...Management control device, 81-1, 81-2, 81c-1, 81c-2...Control unit, 82-1 to 82-2...Light distribution control unit, 83-1, 83c-1 to 83c-2...Subscriber equipment management control unit, 85-1 to 85-3, 86-1 to 86-3...Optical transmission line

Claims

1. A first optical multiplexing / demultiplexing unit that branches and outputs upstream control signal light and main signal light transmitted at different wavelengths from one or more newly connected subscriber devices; a subscriber device management and control unit that transmits downstream control signal light to the one or more newly connected subscriber devices in response to the upstream control signal light branched by the first optical multiplexing / demultiplexing unit, the downstream control signal light instructing the one or more newly connected subscriber devices to output at least the main signal light; an optical distribution unit having a plurality of first ports and a plurality of second ports, which receives the main signal light transmitted from the one or more newly connected subscriber devices in response to the downstream control signal light and branched by the first optical multiplexing / demultiplexing unit from a first port of any of the plurality of first ports, and outputs it from a second port of any of the plurality of second ports; a detection unit that detects the main signal light input to a first port of any of the plurality of first ports of the optical distribution unit; an optical distribution control unit that controls a connection between ports of the optical distribution unit so as to connect a first port at which the main signal light is detected by the detection unit and any second port of the plurality of second ports to which a subscriber device that is a communication partner of the one or more newly connected subscriber devices is connected.

2. The optical communication system according to claim 1, wherein, when the one or more newly connected subscriber devices are multiple subscriber devices, the subscriber device management control unit controls transmission timing so that main signal light is not transmitted from each of the multiple subscriber devices at the same timing.

3. The optical communication system of claim 2, wherein the subscriber device management control unit controls the transmission timing by not transmitting the downstream control signal light to other subscriber devices included in the plurality of subscriber devices until correspondence between one subscriber device included in the plurality of subscriber devices and any one of the first ports of the plurality of first ports possessed by the optical distribution unit is completed.

4. The optical communications system of claim 2, wherein the subscriber equipment management and control unit controls the transmission timing by further including information instructing the transmission timing of the main signal light in the downstream control signal light and transmitting the downstream control signal light to each of the plurality of subscriber equipment.

5. The optical communications system of claim 1, wherein at least one of the one or more newly connected subscriber devices has a plurality of ports, and the subscriber device management and control unit controls the transmission timing so that the main signal light is not transmitted at the same timing from each port of the one subscriber device by transmitting the downstream control signal light to the one subscriber device, further including a port identifier indicating one of the ports of the one subscriber device in the downstream control signal light.

6. The optical communication system according to any one of claims 1 to 5, wherein the subscriber device management and control unit associates a first port at which the main signal light is detected by the detection unit after transmission of the downstream control signal light with the one or more newly connected subscriber devices to which the downstream control signal light is to be transmitted, and notifies the optical distribution control unit of combination information of the associated first port and the one or more newly connected subscriber devices, and the optical distribution control unit controls connection between ports of the optical distribution unit so as to connect a second port of any one of the plurality of second ports to which a subscriber device that is to communicate with the one or more newly connected subscriber devices included in the combination information notified from the subscriber device management and control unit is connected, to a first port included in the combination information.

7. The optical communication system according to any one of claims 1 to 5, wherein the subscriber equipment management and control unit has a plurality of control ports for communicating with each of the one or more subscriber equipment, transmits downstream control signal light instructing the output of at least main signal light via each of the plurality of control ports or via a control port to which a subscriber equipment which is the destination of the downstream control signal light is connected, and when the main signal light is detected by the detection unit after transmitting the downstream control signal light instructing the output of at least the main signal light, associates a first port at which the main signal light was detected by the detection unit with the subscriber equipment which is the destination of the downstream control signal light, and the optical distribution control unit controls a connection between the ports of the optical distribution unit based on a result of the association by the subscriber equipment management and control unit.

8. The optical communications system of claim 7, wherein the subscriber device management control unit identifies a control port among the plurality of control ports to which the one or more newly connected subscriber devices are connected based on the upstream control signal light transmitted from the one or more newly connected subscriber devices, associates the identified control port with the one or more newly connected subscriber devices, and when transmitting a downstream control signal addressed to the one or more newly connected subscriber devices, transmits a downstream control signal light from the associated control port.

9. The optical communications system of claim 8, wherein the subscriber device management and control unit detects a control port among the plurality of control ports that has been linked up by input of the upstream control signal light branched off by the one or more optical multiplexing and demultiplexing units, and associates the detected control port with the one or more newly connected subscriber devices that are the source of the upstream control signal light.

10. The optical communications system of claim 8, wherein the subscriber device management control unit recognizes the one or more newly connected subscriber devices by transmitting and receiving control signal light to and from the one or more newly connected subscriber devices, detects a control port to which the recognized one or more newly connected subscriber devices are connected by referring to a transfer rule list in which identification information identifying the one or more newly connected subscriber devices is associated with one control port among the plurality of control ports, and associates the recognized one or more newly connected subscriber devices with the detected control port.

11. An optical communication system as claimed in any one of claims 1 to 5, wherein the subscriber device management control unit, when main signal light is being transmitted from an already connected subscriber device before the newly connected one or more subscriber devices transmit main signal light, transmits the downstream control signal light to the newly connected one or more subscriber devices, further including in the downstream control signal light information instructing an increase or decrease in the power of the main signal light, or an instruction to change the wavelength of the main signal light.

12. A method for opening an optical communication path, comprising: branching and outputting upstream control signal light and main signal light transmitted at different wavelengths from one or more newly connected subscriber devices; transmitting downstream control signal light to the one or more newly connected subscriber devices in response to the branched upstream control signal light, instructing the one or more newly connected subscriber devices to output at least the main signal light; an optical distribution unit having a plurality of first ports and a plurality of second ports inputting the branched main signal light transmitted from the one or more newly connected subscriber devices in response to the downstream control signal light from a first port of any one of the plurality of first ports; detecting the main signal light input to a first port of any one of the plurality of first ports owned by the optical distribution unit; and controlling connection between ports of the optical distribution unit to connect the first port where the main signal light is detected to a second port of any one of the plurality of second ports to which a subscriber device that is a communication partner of the one or more newly connected subscriber devices is connected.

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