Communication method and communication system

Abstract

A communication method, according to the present invention, comprising: a switching step where, in a condition in which a first information apparatus and second information apparatus are communicatively connected via an optical switch and an optical communication network, an optical switch to which the first information apparatus is connected switches the connection destination of the first information apparatus from an input / output port connected to the optical communication network to a control port to which a control device is connected, in accordance with a prescribed operation of the first information apparatus; a receiving step in which the control device receives, from the first information apparatus, information indicating a third information apparatus, which is a communication connection destination that is different from the second information apparatus, via the control port of the optical switch; an assigning step in which the control device assigns a wavelength used in communication to the first information apparatus and third information apparatus, on the basis of the information indicating the communication connection destination; and a connecting step in which the control device communicably connects the first information apparatus to the third information apparatus by controlling the connection of the input / output port of the optical switch.

Description

[Technical Field]

[0001] The present invention relates to the technology of a communication method and a communication system. This application claims priority to PCT / JP2021 / 017700, filed May 10, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] FIG. 18 is a diagram illustrating an example of the configuration of a conventional optical communication system 900. The optical communication system 900 has multiple optical switches (SWs). Although only two optical switches are shown in FIG. 18, the number of optical switches is arbitrary. The optical SWs are connected to a control device. A subscriber device communicates with other subscriber devices via an optical communication network. For example, a WDM (Wavelength Division Multiplexing) network including various topologies can be applied to the optical communication network. One or more subscriber devices are connected to the optical SW. The subscriber devices are connected to the optical SW via an optical access network such as a PON (Passive Optical Network). The subscriber device has an optical transceiver (TRx). The optical TRx is an example of the configuration of an optical transmitter and an optical receiver in a subscriber device. The optical TRx has an optical transmitter (Tx) and an optical receiver (Rx). The optical TRx is a wavelength-tunable optical transceiver. As the optical TRx, for example, a conventional optical TRx with an AMCC (Auxiliary Management and Control Channel) function can be used.

[0003] The control device has a control light TRx. The control light TRx is an example of the configuration of an optical transmitting section and an optical receiving section in the control device. The control light TRx has an optical transmitter (Tx) and an optical receiver (Rx). The control light TRx is a tunable wavelength optical transceiver. The control device stores a wavelength management table. The wavelength management table is data indicating the wavelengths assigned to each subscriber device. The control device uses the AMCC function to assign wavelengths to be used for communication to each subscriber device according to the destination.

[0004] To assign a wavelength to a subscriber device according to its destination, the optical TRx of the subscriber device and the control optical TRx of the control device first communicate using AMCC. The control device refers to a wavelength table and selects a wavelength to assign to the subscriber device from among available wavelengths according to the destination. The control device notifies the subscriber device of the selected wavelength using a control signal using AMCC.

[0005] Furthermore, the control device stores an optical path management table. The optical path management table is data indicating the route (optical path) within the optical communication network that each subscriber device uses for communication. After setting the wavelength, the control device switches the optical SW so that routing is performed according to the destination indicated by the wavelength of the optical signal transmitted from the subscriber device. As a result, each subscriber device is connected to the opposing subscriber device via the specified optical path. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Takuya Kanai and six others, “Photonic Gateway Supporting All-Photonics Network,” 2021 Institute of Electronics, Information and Communication Engineers General Conference Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional optical communication system 900, once an optical path between subscriber devices is opened, it is not possible to switch the optical path at the request of the subscriber device. This problem is common to all information devices (e.g., subscriber devices) connected to the optical SW. In view of the above circumstances, an object of the present invention is to provide a technique that can change an optical path between information devices in accordance with the operation of the information devices connected to an optical switch. [Means for solving the problem]

[0008] One aspect of the present invention is a communication method performed by a communication system including a plurality of optical switches connecting information devices to an optical communication network and a control device that controls the optical switches, the method comprising: a switching step in which, when a first information device and a second information device are communicatively connected via the optical switch and the optical communication network, the optical switch to which the first information device is connected switches the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected, in accordance with a predetermined operation of the first information device; a receiving step in which the control device receives, from the first information device, information indicating a third information device that is a communication connection destination different from the second information device, via the control port of the optical switch; an allocation step in which the control device allocates wavelengths to be used in communication to the first information device and the third information device based on the information indicating the communication connection destination; and a connection step in which the control device controls the connection of the input / output ports of the optical switch to communicably connect the first information device to the third information device by controlling the connection of the input / output ports of the optical switch.

[0009] One aspect of the present invention is a communication method performed by a communication system comprising a plurality of optical switches connecting an optical communication network and information devices, a control device that controls the optical switches, and a branching device that branches an optical signal output from the optical switch toward the optical communication network toward the control device, the communication method comprising: a receiving step in which, when a first information device and a second information device are communicatively connected via the optical switch and the optical communication network, the control device receives, from the first information device, information indicating a third information device that is a communication connection destination different from the second information device, via the branching device; an allocation step in which the control device allocates wavelengths to be used in communication to the first information device and the third information device based on the information; and a connection step in which the control device controls the connection of the input / output ports of the optical switch to communicably connect the first information device to the third information device.

[0010] One aspect of the present invention is a communications system comprising a plurality of optical switches connecting information devices to an optical communications network, and a control device controlling the optical switches, wherein the control device, when a first information device and a second information device are communicatively connected via the optical switches and the optical communications network, comprises an optical SW management unit that, in accordance with a predetermined operation of the first information device, controls the optical switch to which the first information device is connected to switch the connection destination of the first information device from an input / output port connected to the optical communications network to a control port connected to the control device, an optical receiver that receives information from the first information device indicating a third information device that is a communications destination different from the second information device via the control port of the optical switch, and a wavelength management unit that assigns wavelengths to be used in communications to the first information device and the third information device based on the information indicating the communications destination, and the optical SW management unit controls the connection of the input / output ports of the optical switch to communicatively connect the first information device to the third information device.

[0011] One aspect of the present invention is a communications system comprising a plurality of optical switches connecting an optical communication network and information devices, a control device controlling the optical switches, and a branching device that branches an optical signal output from the optical switch toward the optical communication network toward the control device, wherein the control device comprises an optical receiver that receives, via the branching device, information from the first information device indicating a third information device that is a communication connection destination different from the second information device when a first information device and a second information device are communicatively connected via the optical switch and the optical communication network, the control device comprising: an allocation management unit that allocates wavelengths to be used in communications to the first information device and the third information device based on the information; and an optical SW management unit that connects the first information device to the third information device so that they can communicate with each other by controlling the connection of the input / output ports of the optical switch.

[0012] One aspect of the present invention is a communication method performed by a communication system comprising a plurality of optical switches connecting an optical communication network and information devices, and a control device controlling the optical switches, the method comprising: a switching step in which, when a first information device is communicatively connected to other information devices via the optical switch and the optical communication network, the optical switch to which the first information device is connected switches the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected; an allocation step in which the control device allocates a new wavelength to be used in communication to the first information device via the control port; and a connection step in which the control device controls the connection of the input / output ports of the optical switch to connect the first information device so that it can communicate with other information devices via a new communication path.

[0013] One aspect of the present invention is a communications system comprising a plurality of optical switches connecting an optical communications network and information devices, and a control device controlling the optical switches, wherein the control device comprises an optical SW management unit that controls the optical switch to which the first information device is connected, when the first information device is communicatively connected to other information devices via the optical switch and the optical communications network, to switch the connection destination of the first information device from an input / output port connected to the optical communications network to a control port to which the control device is connected, and a wavelength management unit that assigns a new wavelength to be used in communications to the first information device via the control port, and the optical SW management unit controls the connection of the input / output ports of the optical switch, thereby connecting the first information device to other information devices so that it can communicate with them via a new communications path.

[0014] One aspect of the present invention is a communications system comprising a plurality of optical switches connecting an optical communications network and information devices, a control device controlling the optical switches, a multiplexing device that multiplexes a signal output from the control device with an optical signal input to the optical switch from the optical communications network, and an optical path switching determination unit that determines to switch a communication path between the information devices in response to a predetermined condition being satisfied in the optical communications network, wherein the control device comprises an optical SW management unit that controls the optical switches, and a wavelength management unit that assigns new wavelengths to be used in communication to a first information device and a second information device communicating via the optical switch and the optical communications network, via the multiplexing device, in response to the operation of the optical path switching determination unit, and the optical SW management unit controls the connection of the input / output ports of the optical switch, thereby connecting the first information device to the second information device so that they can communicate with each other via the new communication path. [Effects of the Invention]

[0015] According to the present invention, it becomes possible to change the optical path between information devices in accordance with the operation of the information devices connected to the optical SW. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing an example of a system configuration (first embodiment) of a communication system 100 according to the present invention. [Figure 2] FIG. 2 is a diagram illustrating a specific example of the hardware configuration of a control device 20. [Figure 3] 10 is a diagram showing a specific example of the configuration of a control signal superimposition / extraction unit 14 and a control TRx 26. FIG. [Figure 4] 4 is a flowchart showing a specific example (first operation example) of the operation of the communication system 100 in the first embodiment. [Figure 5] 6 is a flowchart showing a specific example (second operation example) of the operation of the communication system 100 in the first embodiment. [Figure 6] 10 is a flowchart showing a specific example (third operation example) of the operation of the communication system 100 in the first embodiment. [Figure 7] FIG. 10 is a diagram illustrating an example of a system configuration of a modified example (communication system 100a) of the communication system in the first embodiment. [Figure 8] 10 is a diagram showing a specific example of the configuration of a control signal extractor 16 and a control TRx 27. FIG. [Figure 9] FIG. 10 is a diagram illustrating an example of a system configuration of a modified example (communication system 100b) of the communication system in the first embodiment. [Figure 10] FIG. 10 is a diagram showing a second system configuration example (communication system 100c) of the communication system 100 of the present invention. [Figure 11] 10 is a flowchart showing a specific example (fourth operation example) of the operation of the communication system 100c in the second embodiment. [Figure 12] 10 is a flowchart showing a specific example (fifth operation example) of the operation of the communication system 100c in the second embodiment. [Figure 13] 10 is a flowchart showing a specific example (sixth operation example) of the operation of the communication system 100c in the second embodiment. [Figure 14] 10 is a flowchart showing a specific example (seventh operation example) of the operation of the communication system 100c in the second embodiment. [Figure 15] FIG. 10 is a diagram illustrating an example of a system configuration of a modified example (communication system 100d) of the communication system of the second embodiment. [Figure 16] FIG. 10 is a diagram illustrating an example of a system configuration of a modified example (communication system 100e) of the communication system according to the second embodiment. [Figure 17] FIG. 11 is a diagram showing a specific configuration for determining a line fault in the second embodiment shown in FIG. [Figure 18] FIG. 9 is a diagram illustrating an example of the configuration of a conventional optical communication system 900. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. [First embodiment] FIG. 1 is a diagram showing a first system configuration example (first embodiment) of a communication system 100 of the present invention. First, a configuration example and an operation example of the communication system 100 in the first embodiment will be described. The communication system 100 includes a plurality of optical SWs 13, a control signal superimposing / extracting unit 14, a wavelength multiplexing / demultiplexing unit 15, and a control device 20. One or more subscriber devices 11 can be connected to the optical SWs 13. The subscriber device 11 is a specific example of information equipment connected to the optical SW. The subscriber device 11 is connected to the optical SW 13 via a wavelength filter 12. The optical SW 13 and other optical SWs 13 are connected via the control signal superimposing / extracting unit 14, the wavelength multiplexing / demultiplexing unit 15, and an optical transmission line. The optical SW 13 includes a plurality of input / output ports 131. The input / output port 131 on the subscriber device 11 side is connected to the wavelength filter 12. The input / output port 131 on the optical transmission line side is connected to the wavelength multiplexing / demultiplexing unit 15 and a control TRx 26. The optical SW13 changes the connection between the input / output ports 131 under the control of the control device 20. In the example of FIG. 1, the input / output port 131 on the optical transmission line side is connected to the wavelength multiplexing / demultiplexing unit 15 and the control TRx 26 via the control signal superimposing / extracting unit 14. When an optical signal is output from the optical SW13 to the optical transmission line, signals of multiple wavelengths are multiplexed in the wavelength multiplexing / demultiplexing unit 15. When an optical signal is input from the optical transmission line to the optical SW13, signals of multiple wavelengths are demultiplexed in the wavelength multiplexing / demultiplexing unit 15.

[0018] The optical SW13 is communicatively connected to the control device 20. The optical SW13 is communicatively connected to the control device 20, for example, via a control port 132. The control port 132 is connected to a control optical TRx 25 of the control device 20 via a communication path. The optical SW13 is also communicatively connected to the control device 20, for example, via a control signal superimposing / extracting unit 14. The control signal superimposing / extracting unit 14 is connected to a control TRx 26 of the control device 20 via a communication path. The control device 20 has the same number of control TRx 26 as the control signal superimposing / extracting units 14 connected to the optical SW13 to which the control device 20 is connected.

[0019] Each subscriber device 11 is connected to one of the optical SWs 13 and is communicatively connected to the opposite subscriber device 11 via the optical SWs 13 and the optical transmission path. In the example of Fig. 1, subscriber device 11_1 (hereinafter referred to as "subscriber device #1") is connected to optical SW 13_1 (hereinafter referred to as "optical SW #1"), and subscriber device 11_A (hereinafter referred to as "subscriber device #A") and subscriber device 11_B (hereinafter referred to as "subscriber device #B") are connected to optical SW 13_2 (hereinafter referred to as "optical SW #2"). In the example of Fig. 1, subscriber device #A and subscriber device #B are connected to the same optical SW 13 (optical SW #2), but they may be connected to different optical SWs 13.

[0020] A signal output from subscriber device #1 is input to optical SW #1 via wavelength filter 12 and input / output port 131. The signal is input to control signal superimposing / extracting unit 14 from input / output port 131 after being switched by optical SW 13. The signal is output from control signal superimposing / extracting unit 14 to the optical transmission line via wavelength multiplexing / demultiplexing unit 15, and input to the opposing optical SW 13 via the optical transmission line, wavelength multiplexing / demultiplexing unit 15, control signal superimposing / extracting unit 14, and input / output port 131. The signal is input to subscriber device #A or #B via wavelength filter 12 from input / output port 131 after being switched by optical SW 13.

[0021] 1 shows a simplified configuration in which an optical SW13 is directly connected to an opposing optical SW13 via an optical transmission line. However, a WDM network or the like including various topologies can be applied to the optical communication network between the optical SW13, as in the example shown in FIG. The control device 20 is configured using an information processing device. The control device 20 includes an optical path management table storage unit 21, an optical SW management unit 22, a wavelength management table storage unit 23, a wavelength management unit 24, a control optical TRx 25, and a control TRx 26. The optical path management table storage unit 21 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The optical path management table storage unit 21 stores an optical path management table. The optical path management table has data for each subscriber device 11 indicating the route (optical path) in the optical communication network that the subscriber device 11 uses for communication.

[0022] The optical SW management unit 22 determines an optical path between one subscriber device 11 and another subscriber device 11, and records the determined optical path in the optical path management table. The optical SW management unit 22 controls the optical SW 13 to which each subscriber device 11 is connected so that the determined optical path is formed.

[0023] The wavelength management table storage unit 23 is configured using a storage device such as a magnetic hard disk drive or a semiconductor storage device. The wavelength management table storage unit 23 stores a wavelength management table. The wavelength management table has data indicating the wavelength assigned to each subscriber device 11. The subscriber device 11 communicates using light of the wavelength assigned to that device.

[0024] The wavelength management unit 24 allocates wavelengths to the subscriber devices 11. The wavelength management unit 24 may allocate wavelengths according to, for example, the device (destination) with which the subscriber device 11 communicates. The wavelength management unit 24 records data indicating the wavelengths allocated to each subscriber device 11 in the wavelength management table storage unit 23. The wavelength management unit 24 notifies each subscriber device 11 of the allocated wavelengths.

[0025] The control light TRx 25 is an example of a configuration of an optical transmitter and an optical receiver in the control device 20. The control light TRx 25 has an optical transmitter and an optical receiver. The control light TRx 25 may be configured using, for example, a variable wavelength optical transceiver.

[0026] The control TRx 26 includes an optical receiver (optical Rx 261) and a transmitter (Tx 262). The control TRx 26 transmits and receives control signals to and from the optical SW 13 via the control signal superimposing / extracting unit 14.

[0027] FIG. 2 is a diagram showing a specific example of the hardware configuration of the control device 20. The control device 20 includes, for example, a communication interface 1, an auxiliary storage device 2, a memory 3, and a processor 4, as shown in FIG. 2. The communication interface 1 inputs and outputs data between the control device 20 and external devices. The communication interface 1 functions, for example, as a control optical TRx 25 and a control TRx 26. The auxiliary storage device 2 is configured using a magnetic hard disk device or a semiconductor storage device. The auxiliary storage device 2 functions, for example, as an optical path management table storage unit 21 and a wavelength management table storage unit 23. The memory 3 and the processor 4 function, for example, as an optical SW management unit 22 and a wavelength management unit 24.

[0028] All or part of the functions of the control device 20 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The above program may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and semiconductor storage devices (e.g., SSDs: Solid State Drives), as well as storage devices such as hard disks and semiconductor storage devices built into computer systems. The above program may be transmitted via a telecommunications line.

[0029] 3 is a diagram showing a specific example of the configuration of the control signal superimposing / extracting unit 14 and the control TRx 26. The control signal superimposing / extracting unit 14 includes an optical branching unit 141 and an optical modulation unit 142. The optical branching unit 141 is one aspect of a branching device. The optical branching unit 141 may be configured using, for example, a power splitter. The optical branching unit 141 branches an optical signal transmitted through the optical transmission path between the optical SW 13 and the wavelength multiplexing / demultiplexing unit 15, and outputs the branched signal to the optical Rx 261 in the control TRx 26. The optical Rx 261 demodulates the control signal (e.g., an AMCC signal) superimposed on the main signal. The optical Rx 261 performs demodulation by, for example, a low-pass filter or signal processing.

[0030] The optical modulation unit 142 may be configured using, for example, a high-speed variable optical attenuator (VOA). The optical modulation unit 142 superimposes an electrical signal output by the Tx 262 in the control TRx 26 as a control signal (e.g., an AMCC signal) onto the main signal in the optical stage. The subscriber device 11 establishes communication with the control TRx 26 via the control signal superimposition / extraction unit 14. Since the control signal superimposition / extraction unit 14 is provided between the optical SW 13 and the wavelength multiplexing / demultiplexing unit 15, the subscriber device 11 can superimpose the control signal on the main signal and communicate with the control device 20 via the control signal superimposition / extraction unit 14.

[0031] (First operation example) Fig. 4 is a flowchart showing a specific example (first operation example) of the operation of the communication system 100 in the first embodiment. More specifically, Fig. 4 shows the operation (optical path switching sequence) of changing the connected subscriber device 11 from subscriber device #A to subscriber device #B when subscriber device #1 is communicating with subscriber device #A. A specific example of the optical path switching sequence will be described below.

[0032] First, an action occurs in subscriber device #1 that triggers a change in the destination subscriber device 11. This action may be of any type. For example, an information device (e.g., a personal computer) connected to subscriber device #1 may input a switch request command to subscriber device #1 indicating that the destination subscriber device 11 should be changed from subscriber device #A to subscriber device #B. Alternatively, subscriber device #1 may decide to change the destination subscriber device 11 from subscriber device #A to subscriber device #B on its own initiative, based on information received from the optical communication network or the satisfaction of conditions set in a program or the like pre-programmed in the subscriber device.

[0033] In response to the triggering operation described above, the subscriber device #1 transmits a disconnection request to the subscriber device #A and the control device 20. The disconnection request is a signal indicating that the communication connection will be subsequently disconnected. The disconnection request to the subscriber device #A may be transmitted in a main signal. In this case, the disconnection request is transmitted to the subscriber device #A via the optical communication network and the optical SW #2. The disconnection request to the subscriber device #A may be transmitted in a control signal. In this case, the disconnection request is transmitted to the subscriber device #A via the control signal superimposition / extraction unit 14 and the control device 20. The disconnection request to the control device 20 may be transmitted superimposed on an optical signal as a control signal. In this case, the optical signal on which the control disconnection request is superimposed is branched to the control TRx 26 by the optical branching unit 141 of the control signal superimposition / extraction unit 14. The optical Rx 261 of the control TRx 26 demodulates the control signal (disconnection request) from the branched optical signal. The demodulated disconnection request is acquired, for example, by the optical SW management unit 22. In response to the disconnection request, subscriber device #A and the control device 20 transmit an ACK to subscriber device #1, which receives the ACK (step S101).

[0034] In response to the transmission of the disconnection request, subscriber device #1 stops emitting light onto the communication path. In response to the reception of the disconnection request, subscriber device #A stops emitting light onto the communication path (step S102).

[0035] The control device 20 recognizes that the light emissions of the subscriber devices #1 and #A have stopped. The control device 20 may, for example, monitor the input light intensity at the input / output port 131 of the optical SW 13, and recognize that the light emissions have stopped when the input light intensity drops below a threshold. Then, the optical SW management unit 22 of the control device 20 opens both the input / output port 131 of the optical SW #1 connected to the subscriber device #1 and the input / output port 131 of the optical SW #2 connected to the subscriber device #A (step S103).

[0036] Opening the input / output port 131 of the optical SW 13 means, for example, putting the input / output port 131 of the optical SW 13 into a state where it is not connected to other input / output ports 131. The opened input / output port 131 can be used by other subscriber devices 11.

[0037] Next, when a predetermined time has passed since the subscriber device #1 stopped emitting light, the subscriber device #1 resumes emitting light to the communication path. When the optical SW 13 detects light at the input / output port 131 to which no light had been input for a predetermined time, the optical SW 13 connects the input / output port 131 where the light was detected to the control port 132. In this case, in response to the subscriber device #1 starting to emit light, the optical SW 13 connects the input / output port 131 to which the subscriber device #1 is connected to the control port 132. The subscriber device #1 transmits a connection switch request to the control device 20 via the control port 132.

[0038] The connection switching request includes information indicating the subscriber device 11 that will be the new connection destination. For example, a connection switching request indicating "change the connection destination to subscriber device #B" may be transmitted. When the optical SW management unit 22 of the control device 20 receives the connection switching request, it transmits an ACK to the subscriber device #1 that is the sender. Subscriber device #1 receives the ACK from the control device 20 (step S104). Through this operation, starting from the operation of subscriber device 11, subscriber device 11 is connected to the control device 20 and can transmit the connection switching request.

[0039] Next, the optical SW management unit 22 and wavelength management unit 24 of the control device 20 respectively determine the optical path and wavelength to be used in the communication between the subscriber device #1 and the subscriber device #B (step S105). Note that if the subscriber device 11 can select signal parameters such as modulation method, baud rate, and transmission light intensity from multiple candidates for its own communication, the control device 20 may further determine such signal parameters in addition to the optical path and wavelength.

[0040] Next, the control device 20 switches the optical SW #2 to connect the subscriber device #B to the control port 132 (step S106).

[0041] Next, the control device 20 notifies subscriber device #1 of the determined wavelength via the control port 132. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #1 of the determined signal parameters. Upon receiving the notification, subscriber device #1 transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #1.

[0042] In accordance with the notification received from the control device 20, subscriber device #1 switches the wavelength used for communication by itself to the notified wavelength. The control device 20 notifies subscriber device #B of the determined wavelength via the control port 132. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #B of the determined signal parameters. Upon receiving the notification, subscriber device #B transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives an ACK from subscriber device #B. In accordance with the notification received from the control device 20, subscriber device #B switches the wavelength used for communication by itself to the notified wavelength (step S107).

[0043] The optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #1 to connect the subscriber device #1 from the control port 132 to the input / output port 131 on the full-mesh side (optical communication network side). Also, the optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #2 to connect the subscriber device #B from the control port 132 to the input / output port 131 on the full-mesh side (optical communication network side) (step S108).

[0044] Thereafter, the subscriber devices #1 and #B start communication via the optical SW13 and the inside of the optical communication network (step S109).

[0045] In a first operation example of the communication system 100 configured as above, it is possible to change the optical path between the subscriber devices 11 in accordance with the operation of the subscriber devices 11. Specifically, it is as follows. In the communication system 100, the subscriber device 11 temporarily stops emitting light in the communication path. When the subscriber device 11 subsequently starts emitting light again, the optical SW 13 connects the subscriber device 11 that has started emitting light again to the control port 132. Thereafter, the subscriber device 11 can transmit a connection switching request (information indicating the subscriber device 11 to be the new connection destination) to the control device 20 via the control port 132. Therefore, in the communication system 100, even after an optical path between the subscriber devices 11 has been established, it is possible to change the communication (change the optical path) in accordance with the operation of the subscriber devices 11.

[0046] (Second operation example) Fig. 5 is a flowchart showing a specific example (second operation example) of the operation of the communication system 100 in the first embodiment. More specifically, Fig. 5 shows the operation (optical path switching sequence) of changing the connected subscriber device 11 from subscriber device #A to subscriber device #B when subscriber device #1 is communicating with subscriber device #A. In this respect, Fig. 5 is identical to Fig. 4. However, there are differences in the specific processing between Fig. 4 and Fig. 5. The second operation example shown in Fig. 5 will be described below. The operation that triggers the change of the connected subscriber device 11 is the same as in the first operation example.

[0047] First, subscriber device #1 transmits a disconnection request to subscriber device #A and the control device 20 (step S201). This process is the same as step S101 in FIG.

[0048] Next, in response to the disconnection request, the control device 20 controls the optical SW #1 and the optical SW #2 to connect the input / output ports 131 of the subscriber device #1 and the subscriber device #A to the control port 132. The subscriber device #1 transmits a connection switching request to the control device 20 via the control port 132. The connection switching request includes information indicating the subscriber device 11 that will be the new connection destination. For example, a connection switching request indicating "change the connection destination to subscriber device #B" may be transmitted. Upon receiving the connection switching request, the optical SW management unit 22 of the control device 20 transmits an ACK to the subscriber device #1 that is the sender. The subscriber device #1 receives the ACK from the control device 20 (step S202). Through these operations, the operation of the subscriber device 11 serves as a starting point, and the subscriber device 11 is connected to the control device 20 and can transmit a connection switching request.

[0049] The optical SW management unit 22 of the control device 20 instructs subscriber device #A to stop emitting light via the control port 132. Subscriber device #A, which has received the instruction to stop emitting light, sends an ACK to the control device 20. Subscriber device #A stops emitting light to the transmission path in response to the instruction to stop emitting light. The optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of optical SW #2, and opens the input / output port 131 of optical SW #2 connected to subscriber device #A (step S203).

[0050] Next, the control device 20 switches the optical SW #2 to connect the subscriber device #B to the control port 132 (step S204).

[0051] Next, the optical SW management unit 22 and wavelength management unit 24 of the control device 20 respectively determine the optical path and wavelength to be used in the communication between the subscriber device #1 and the subscriber device #B (step S205). Note that if the subscriber device 11 can select signal parameters such as modulation method, baud rate, and transmission light intensity from multiple candidates for its own communication, the control device 20 may further determine such signal parameters in addition to the optical path and wavelength.

[0052] Next, the processes of steps S206 to S208 are executed. The processes of steps S206 to S208 are the same as the processes of steps S107 to S109 in FIG.

[0053] In a second operation example of the communication system 100 configured as above, it is possible to change the optical path between the subscriber devices 11 in accordance with the operation of the subscriber devices 11. Specifically, it is as follows. In the communication system 100, the subscriber devices 11 can transmit information regarding the disconnection of communication (disconnection request) to the control device 20 via the control signal superimposition / extraction unit 14. In response to the disconnection request, the control device 20 controls the optical SW 13 to connect the requesting subscriber device 11 to the control port 132. Thereafter, the subscriber device 11 can transmit a connection switch request (information indicating the subscriber device 11 to be the new connection destination) to the control device 20 via the control port 132. Therefore, in the communication system 100, even after an optical path between the subscriber devices 11 has been established, it is possible to change the communication (change the optical path) in accordance with the operation of the subscriber devices 11.

[0054] (Third operation example) Fig. 6 is a flowchart showing a specific example (third operation example) of the operation of the communication system 100 in the first embodiment. More specifically, Fig. 6 shows the operation (optical path switching sequence) of changing the connected subscriber device 11 from subscriber device #A to subscriber device #B when subscriber device #1 is communicating with subscriber device #A. In this respect, Fig. 6 coincides with Fig. 4. However, there are differences in the specific processing between Fig. 4 and Fig. 6. The third operation example shown in Fig. 6 will be described below. The operation that triggers the change of the connected subscriber device 11 is the same as in the first operation example.

[0055] First, subscriber device #1 transmits a connection switching request to the control device 20. The connection switching request includes information indicating the subscriber device 11 that will be the new connection destination. For example, a connection switching request indicating "change the connection destination to subscriber device #B" may be transmitted. The connection switching request to the control device 20 may be superimposed on an optical signal as a control signal and transmitted. In this case, the optical signal on which the control switching request is superimposed is branched to the control TRx 26 by the optical branching unit 141 of the control signal superimposing / extracting unit 14. The optical Rx 261 of the control TRx 26 demodulates the control signal (connection switching request) from the branched optical signal. The demodulated connection switching request is acquired, for example, by the optical SW management unit 22. In response to the connection switching request, the control device 20 transmits an ACK to subscriber device #1. Subscriber device #1 receives the ACK (step S301). Furthermore, subscriber device #1 transmits a disconnection request to subscriber device #A. The transmission of the disconnection request to subscriber device #A is the same process as step 101 in FIG. 4, and therefore a description thereof will be omitted. By this operation, it becomes possible to transmit a connection switching request from the subscriber device 11 to the control device 20, with the operation of the subscriber device 11 as the starting point.

[0056] Next, the optical SW management unit 22 and wavelength management unit 24 of the control device 20 respectively determine the optical path and wavelength to be used in the communication between the subscriber device #1 and the subscriber device #B (step S302). Note that if the subscriber device 11 can select signal parameters such as modulation method, baud rate, and transmission optical power from multiple candidates for its own communication, the control device 20 may further determine such signal parameters in addition to the optical path and wavelength.

[0057] Next, the control device 20 switches the optical SW #2 to connect the subscriber device #B to the control port 132 (step S303).

[0058] Next, the control device 20 notifies the subscriber device #1 of the determined wavelength via the control signal superimposition / extraction unit 14. At this time, if the control device 20 has determined signal parameters, it may also notify the subscriber device #1 of the determined signal parameters. Upon receiving the notification, the subscriber device #1 transmits an ACK to the control device 20 via the control signal superimposition / extraction unit 14 in response to the received notification. The control device 20 receives the ACK from the subscriber device #1. In accordance with the notification received from the control device 20, the subscriber device #1 switches the wavelength used for communication within its own device to the notified wavelength. Note that, in order to transmit the wavelength notification from the control device 20 to the subscriber device #1 as AMCC, it is necessary to superimpose an AMCC signal on the optical signal transmitted from the subscriber device #A to the subscriber device #1. Therefore, prior to this process, it is preferable to avoid opening the port connected to the subscriber device #A or extinguishing the subscriber device #A, as in step S305 described below.

[0059] The control device 20 notifies subscriber device #B of the determined wavelength via the control port 132. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #B of the determined signal parameters. Upon receiving the notification, subscriber device #B transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #B. In accordance with the notification received from the control device 20, subscriber device #B switches the wavelength used for communication by its own device to the notified wavelength (step S304).

[0060] The optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #2, and opens the input / output port 131 of the optical SW #2 connected to the subscriber device #A (step S305). This operation prevents light from the subscriber device #A, which is not connected to any subscriber device 11, from being input to the optical transmission line (optical communication network) and becoming noise in other optical signals.

[0061] The optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #1 to connect the subscriber device #1 to the input / output port 131 of the path directed to the subscriber device #B. The optical SW management unit 22 of the control device 20 also switches the connection between the input / output ports 131 of the optical SW #2 to connect the subscriber device #B from the control port 132 to the input / output port 131 on the full-mesh side (optical network side) (step S306).

[0062] Thereafter, the subscriber devices #1 and #B start communication via the optical SW13 and the inside of the optical communication network (step S307).

[0063] In a third operation example of the communication system 100 configured as above, it becomes possible to change the optical path between the subscriber devices 11 in accordance with the operation of the subscriber devices 11. Specifically, it is as follows. In the communication system 100, the subscriber devices 11 can transmit information (connection switching request) regarding a new connection destination for communication to the control device 20 via the control signal superimposition / extraction unit 14. In response to the connection switching request, the control device 20 controls the optical SW 13 to connect the requesting subscriber device 11 to the subscriber device 11 that will be the new connection destination in accordance with the request. Therefore, in the communication system 100, even after an optical path between the subscriber devices 11 has been established, it becomes possible to change the communication (change the optical path) in accordance with the operation of the subscriber devices 11.

[0064] Furthermore, in the process of changing the optical path, there is no need to take the trouble of connecting the subscriber device 11 (subscriber device #1), which is the requester of the change, to the control port 132. This makes it possible to change the optical path with a smaller amount of processing. As a result, for example, it becomes possible to change the optical path in a shorter time.

[0065] (Modified Operation) Next, modified examples of the operations shown in Fig. 4 to Fig. 6 will be described. First, a modified example of the first operation example shown in Fig. 4 will be described. In step S102, subscriber device #1 (the sender of the communication disconnection request) stops emitting light, but subscriber device #A (the recipient of the communication disconnection request) may be configured not to stop emitting light.

[0066] In step S101, the communication disconnection request does not necessarily have to be transmitted from subscriber device #1 to subscriber device #A. In this case, subscriber device #1 may stop emitting light in step S102 without transmitting the communication disconnection request.

[0067] Furthermore, in the first operation example and each of the modified examples described above, the subscriber device #1 may be configured not to send a disconnection request to the control device 20. Even with this configuration, the subscriber device #1 stops emitting light in step S103, and in response to the subscriber device #1 restarting light emission in step S104, the subscriber device #1 is connected to the control port 132. Therefore, starting from the operation of the subscriber device 11, the subscriber device 11 is connected to the control device 20 and can send a connection switch request.

[0068] Also, the subscriber device #1 may be configured not to send a disconnection request to the control device 20 and the subscriber device #A. In this case, the process of step S101 may be omitted in the first place.

[0069] The order of the processes of steps S105 and S106 may be reversed. Furthermore, the operations of transmitting and receiving ACK may be omitted in the processes of each step. Furthermore, an in-band method in which control signals are transmitted and received within the overhead of a protocol may be used for transmitting and receiving control signals between the subscriber device #1 and the subscriber device #A. Similarly, an in-band method in which control signals are transmitted and received within the overhead of a protocol may be used for transmitting and receiving control signals between the subscriber device 11 and the control TRx 26. Furthermore, the in-band method described above may also be employed in a configuration in which a control signal is transmitted from the subscriber device 11 and received by the control TRx 26. For example, an area called a Generic Communications Channel (GCC) in the overhead for network monitoring in an OTN (Optical Transport Network) widely adopted in high-capacity long-distance optical transmission networks may be used as the in-band method. For example, the method disclosed in the following document may be applied to such a configuration. Reference: ITU-T G.709 available at https: / / www.itu.int / rec / T-REC-G.709 /

[0070] The subscriber device 11 may stop emitting light or restart emitting light by, for example, turning the power of the subscriber device 11 off or on.

[0071] Next, a modified example of the second operation example shown in Fig. 5 will be described. A communication disconnection request does not necessarily have to be transmitted from subscriber device #1 to subscriber device #A. The order of the processes of steps S203, S204, and S205 may be changed. Furthermore, in the processes of each step, the operation of transmitting and receiving an ACK may be omitted.

[0072] Next, a modified example of the third operation example shown in Fig. 6 will be described. In step S301, a communication disconnection request does not have to be transmitted from subscriber device #1 to subscriber device #A. After input / output port 131 of optical SW #2 is opened, subscriber device #A may be configured to autonomously stop light emission (turn off light) in response to, for example, the absence of a received signal for a certain period of time or more. The order of steps S302 and S303 may be reversed.

[0073] Up until the processing of step S304, the subscriber device #A is emitting light and is connected to the optical transmission line. Therefore, it is desirable that the processing order of steps S305 and S306 is not reversed. For example, assume that the subscriber device #B, which is the new connection partner, is instructed to set the same optical transmission line and the same wavelength as the subscriber device #A. In this case, the settings of the input / output port 131 of the optical SW13 will be the same for the subscriber devices #A and #B. Therefore, the setting of the optical SW13 cannot be completed. Therefore, in order to correctly complete the setting of the optical SW13, the order of steps S305 and S306 must be as stated. Furthermore, the ACK sending and receiving operations may be omitted in the processing of each step.

[0074] (Variations of the configuration) Fig. 7 is a diagram showing an example of a system configuration of a modified example of the communication system (communication system 100a). The communication system 100a shown in Fig. 7 includes a control signal extracting unit 16 instead of the control signal superimposing / extracting unit 14. Furthermore, the communication system 100a shown in Fig. 7 includes a control Rx 27 instead of the control TRx 26.

[0075] 8 is a diagram showing a specific example of the configuration of the control signal extractor 16 and the control TRx 27. The control signal extractor 16 includes an optical branching unit 141. The control signal extractor 16 differs from the control signal superimposing / extracting unit 14 in that it does not include an optical modulation unit 142. The optical branching unit 141 can be, for example, a power splitter. The power splitter branches an optical signal transmitted through the optical transmission path and outputs it to an optical Rx 261 in the control Rx 27.

[0076] The control TRx 27 includes an optical Rx 261. The control TRx 27 differs from the control TRx 26 in that it does not include a Tx 262. The optical Rx 261 demodulates a control signal (e.g., an AMCC signal) superimposed on the main signal. The optical Rx 261 performs demodulation using, for example, a low-pass filter or signal processing.

[0077] 9 is a diagram showing an example of a system configuration of a modified example of the communication system (communication system 100b). The communication system 100b shown in FIG. 9 does not include the control signal superimposing / extracting unit 14, the control signal extracting unit 16, the control TRx 26, and the control TRx 27.

[0078] The first operation example shown in Fig. 4 may be executed in the communication system 100a shown in Fig. 7. The second operation example shown in Fig. 6 may be executed in the communication system 100a shown in Fig. 7. In the first operation example shown in Fig. 4, when a configuration is adopted in which a connection cutoff request is not sent to the control device 20 as described above and a configuration in which the processing of step S101 is not executed, the first operation example may be executed in the communication system 100b shown in Fig. 9.

[0079] When applied to the above-described operational example, each of the communication systems (communication system 100a and communication system 100b) of these modified configurations can also achieve the same technical effects as those of communication system 100.

[0080] [Second embodiment] Fig. 10 is a diagram showing a second system configuration example (second embodiment: communication system 100c) of the communication system 100 of the present invention. The communication system 100c shown in Fig. 10 differs from the first embodiment in that it further includes an optical path switching determining unit 17. Below, the differences from the first embodiment among the configuration and operation examples of the communication system 100c in the second embodiment will be described.

[0081] The optical path switching determination unit 17 is an information device capable of communicating with the control device 20. When a predetermined connection destination switching condition is satisfied, the optical path switching determination unit 17 determines to change the connection destination of a certain subscriber device 11 to another subscriber device 11. A specific example of the connection destination switching condition is, for example, a decision to switch the connection destination from a working system to a redundant system. When it is decided to change the connection destination, the optical path switching determination unit 17 instructs the control device 20 to change the connection destination.

[0082] When a predetermined optical path switching condition is satisfied, the optical path switching determination unit 17 determines to change the optical path from a certain subscriber device 11 to a destination device without changing the destination subscriber device 11. A specific example of an optical path switching condition is when a decision is made to switch from a working path to a redundant path due to a line failure, equipment replacement, or the like. When a decision is made to change the optical path, the optical path switching determination unit 17 instructs the control device 20 to change the optical path.

[0083] When the control device 20 is instructed by the optical path switching determining unit 17 to change the connection destination, it controls the optical SW 13 in accordance with the instruction to change the connection destination of the target subscriber device 11. When the control device 20 is instructed by the optical path switching determining unit 17 to change the optical path, it controls the optical SW 13 in accordance with the instruction to change the optical path of the target subscriber device 11.

[0084] (Fourth operation example) Fig. 11 is a flowchart showing a specific example (fourth operation example) of the operation of the communication system 100c in the second embodiment. More specifically, Fig. 11 shows the operation (optical path switching sequence) of changing the connected subscriber device 11 from subscriber device #A to subscriber device #B when subscriber device #1 is communicating with subscriber device #A. A specific example of the optical path switching sequence will be described below.

[0085] First, the connection destination switching condition is satisfied for subscriber device #1. As a result, the optical path switching determination unit 17 determines to change the subscriber device 11 to which subscriber device #1 is connected from subscriber device #A to subscriber device #B. Then, the optical path switching determination unit 17 instructs the control device 20 to change the subscriber device 11 to which subscriber device #1 is connected from subscriber device #A to subscriber device #B and to switch the optical path (step S401).

[0086] Next, the optical SW management unit 22 and wavelength management unit 24 of the control device 20 respectively determine the optical path and wavelength to be used in the communication between the subscriber device #1 and the subscriber device #B (step S402). Note that if the subscriber device 11 can select signal parameters such as modulation method, baud rate, and transmission light intensity from multiple candidates for its own communication, the control device 20 may further determine such signal parameters in addition to the optical path and wavelength.

[0087] Next, the control device 20 controls the optical SW #1 to connect the input / output port 131 to which the subscriber device #1 is connected to the control port 132. The control device 20 controls the optical SW #2 to connect the input / output port 131 to which the subscriber device #A is connected to the control port 132 (step S403).

[0088] The control device 20 instructs subscriber device #A to stop light emission via the control port 132. In response to the instruction to stop light emission, subscriber device #A sends an ACK to the control device 20. The control device 20 receives the ACK. In response to the instruction to stop light emission, subscriber device #A stops emitting light to the communication path. The control device 20 recognizes that subscriber device #A has stopped light emission. The control device 20 may, for example, monitor the input optical intensity at the input / output port 131 of the optical SW 13, and recognize that light emission has stopped when the input optical intensity drops below a threshold. Then, the optical SW management unit 22 of the control device 20 opens the input / output port 131 of optical SW #2 connected to subscriber device #A (step S404).

[0089] Next, the control device 20 switches the optical SW #2 to connect the subscriber device #B to the control port 132 (step S405).

[0090] Next, the control device 20 notifies subscriber device #1 of the determined wavelength via the control port 132. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #1 of the determined signal parameters. Upon receiving the notification, subscriber device #1 transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #1. Subscriber device #1 switches the wavelength used for communication by itself to the notified wavelength in accordance with the notification received from the control device 20.

[0091] The control device 20 notifies subscriber device #B of the determined wavelength via the control port 132. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #B of the determined signal parameters. Upon receiving the notification, subscriber device #B transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #B. In accordance with the notification received from the control device 20, subscriber device #B switches the wavelength used for communication by itself to the notified wavelength (step S406).

[0092] The optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #1 to connect the subscriber device #1 from the control port 132 to the input / output port 131 on the full-mesh side (optical communication network side). Also, the optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #2 to connect the subscriber device #B from the control port 132 to the input / output port 131 on the full-mesh side (optical communication network side) (step S407).

[0093] Thereafter, the subscriber devices #1 and #B start communication via the optical SW13 and the inside of the optical communication network (step S408).

[0094] In a fourth operation example of the communication system configured in this manner, it becomes possible to change the optical path between the subscriber devices 11 in accordance with the operation of the optical path switching determination unit 17. Specifically, it is as follows. In the communication system 100c, the optical path switching determination unit 17 connects each subscriber device 11 to the control port 132 in response to the satisfaction of the connection destination switching condition. The control device 20 can instruct each subscriber device 11 to switch the connection via the control port 132. Therefore, in the communication system 100, it becomes possible to change the communication (change the optical path) in accordance with the operation of the optical path switching determination unit 17 even after the optical path between the subscriber devices 11 has been established.

[0095] (5th operation example) Fig. 12 is a flowchart showing a specific example (fifth operation example) of the operation of the communication system 100c in the second embodiment. More specifically, Fig. 12 shows the operation (optical path switching sequence) of changing the connected subscriber device 11 from subscriber device #A to subscriber device #B when subscriber device #1 is communicating with subscriber device #A. A specific example of the optical path switching sequence will be described below.

[0096] First, the connection destination switching condition is satisfied for subscriber device #1. As a result, the optical path switching determination unit 17 determines to change the subscriber device 11 to which subscriber device #1 is connected from subscriber device #A to subscriber device #B. Then, the optical path switching determination unit 17 instructs the control device 20 to change the subscriber device 11 to which subscriber device #1 is connected from subscriber device #A to subscriber device #B and to switch the optical path (step S501).

[0097] Next, the optical SW management unit 22 and wavelength management unit 24 of the control device 20 respectively determine the optical path and wavelength to be used in the communication between the subscriber device #1 and the subscriber device #B (step S502). Note that if the subscriber device 11 can select signal parameters such as modulation method, baud rate, and transmission light intensity from multiple candidates for its own communication, the control device 20 may further determine such signal parameters in addition to the optical path and wavelength.

[0098] Next, the control device 20 controls the optical SW #2 to connect the input / output port 131, to which the subscriber device #B is connected, to the control port 132 (step S503).

[0099] The control device 20 instructs subscriber device #1 of the wavelength determined in step S502 via the control signal superimposition / extraction unit 14. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #1 of the determined signal parameters. Upon receiving the notification, subscriber device #1 transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #1. In accordance with the notification received from the control device 20, subscriber device #1 switches the wavelength used for communication by its own device to the notified wavelength.

[0100] This instruction may use, for example, light emitted by subscriber device A. More specifically, for example, an AMCC signal indicating the wavelength instruction may be superimposed on the optical signal transmitted from subscriber device A. In this case, the port connected to subscriber device A must not be opened or the light from subscriber device A must not be turned off before this process.

[0101] The control device 20 instructs subscriber device #B of the wavelength determined in step S502 via the control port 132. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #B of the determined signal parameters. Upon receiving the notification, subscriber device #B transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #B. In accordance with the notification received from the control device 20, subscriber device #B switches the wavelength used for communication by itself to the notified wavelength (step S504).

[0102] The optical SW management unit 22 of the control device 20 opens the input / output port 131 of the optical SW #2 connected to the subscriber device #A (step S505). After this, the subscriber device #A may stop emitting light when a predetermined condition indicating that a communication partner does not exist is satisfied (for example, when an optical signal is not received for a predetermined period of time).

[0103] The optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #1 to connect the subscriber device #1 from the control port 132 to the input / output port 131 on the full-mesh side (optical communication network side). Also, the optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #2 to connect the subscriber device #B from the control port 132 to the input / output port 131 on the full-mesh side (optical communication network side) (step S506).

[0104] Thereafter, the subscriber devices #1 and #B start communication via the optical SW13 and the inside of the optical communication network (step S507).

[0105] In a fifth operation example of the communication system configured as above, it becomes possible to change the optical path between the subscriber devices 11 in accordance with the operation of the optical path switching determination unit 17. Specifically, it is as follows. In the communication system 100c, the optical path switching determination unit 17 connects the new subscriber device 11 to the control port 132 in response to the satisfaction of the connection destination switching condition. The new subscriber device 11 is instructed about the wavelength, etc., via the control port 132. The subscriber device 11 (subscriber device #1) that maintains optical communication even after switching is instructed about the wavelength, etc., via the control signal superimposition / extraction unit 14. Therefore, in the communication system 100, even after the optical path between the subscriber devices 11 has been established, it is possible to change the communication (change the optical path) in accordance with the operation of the optical path switching determination unit 17.

[0106] Furthermore, in the process of changing the optical path, there is no need to take the trouble of connecting the subscriber device 11 (e.g., subscriber device #1) to the control port 132. This makes it possible to change the optical path with a smaller amount of processing. As a result, for example, it becomes possible to change the optical path in a shorter time.

[0107] (Sixth operation example) Fig. 13 is a flowchart showing a specific example (sixth operation example) of the operation of the communication system 100c in the second embodiment. More specifically, Fig. 13 shows an operation (optical path switching sequence) for changing the optical path between subscriber device #1 and subscriber device #A without changing the destination subscriber device 11 from subscriber device #A when subscriber device #1 is communicating with subscriber device #A. A specific example of the optical path switching sequence will be described below.

[0108] First, the optical path switching condition is satisfied for subscriber device #1. As a result, the optical path switching determining unit 17 determines to change the optical path between subscriber device #1 and subscriber device #A. Then, the optical path switching determining unit 17 instructs the control device 20 to change the optical path between subscriber device #1 and subscriber device #A (step S601).

[0109] Next, the optical SW management unit 22 and wavelength management unit 24 of the control device 20 respectively determine the optical path and wavelength to be used in the communication between the subscriber device #1 and the subscriber device #A (step S602). Note that if the subscriber device 11 can select signal parameters such as modulation method, baud rate, and transmission optical power from multiple candidates for its own communication, the control device 20 may further determine such signal parameters in addition to the optical path and wavelength.

[0110] Next, the control device 20 controls the optical SW #1 to connect the input / output port 131 to which the subscriber device #1 is connected to the control port 132. The control device 20 controls the optical SW #2 to connect the input / output port 131 to which the subscriber device #A is connected to the control port 132 (step S603).

[0111] Next, the control device 20 notifies subscriber device #1 of the determined wavelength via the control port 132. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #1 of the determined signal parameters. Upon receiving the notification, subscriber device #1 transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #1. Subscriber device #1 switches the wavelength used for communication by itself to the notified wavelength in accordance with the notification received from the control device 20.

[0112] The control device 20 notifies subscriber device #A of the determined wavelength via the control port 132. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #A of the determined signal parameters. Upon receiving the notification, subscriber device #A transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #A. In accordance with the notification received from the control device 20, subscriber device #A switches the wavelength used for communication by itself to the notified wavelength (step S604).

[0113] The optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #1 to connect the subscriber device #1 from the control port 132 to the input / output port 131 on the full-mesh side (optical communication network side). Also, the optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #2 to connect the subscriber device #A from the control port 132 to the input / output port 131 on the full-mesh side (optical communication network side) (step S605).

[0114] Thereafter, the subscriber devices #1 and #A start communication on a new optical path via the optical SW13 and the inside of the optical communication network (step S606).

[0115] In a sixth operation example of the communication system configured as above, it becomes possible to change the optical path between the subscriber devices 11 in accordance with the operation of the optical path switching determination unit 17. Specifically, it is as follows. In the communication system 100c, the optical path switching determination unit 17 connects each subscriber device 11 to the control port 132 in response to the satisfaction of the optical path switching condition. The control device 20 can instruct each subscriber device 11 to switch the wavelength via the control port 132. Therefore, in the communication system 100, it becomes possible to change the communication (change the optical path) in accordance with the operation of the optical path switching determination unit 17 even after the optical path between the subscriber devices 11 has been established.

[0116] (7th operation example) Fig. 14 is a flowchart showing a specific example (seventh operation example) of the operation of the communication system 100c in the second embodiment. More specifically, Fig. 14 shows an operation (optical path switching sequence) for changing the optical path between subscriber device #1 and subscriber device #A without changing the destination subscriber device 11 from subscriber device #A when subscriber device #1 is communicating with subscriber device #A. A specific example of the optical path switching sequence will be described below.

[0117] First, the optical path switching condition is satisfied for subscriber device #1. As a result, the optical path switching determining unit 17 determines to change the optical path between subscriber device #1 and subscriber device #A. Then, the optical path switching determining unit 17 instructs the control device 20 to change the optical path between subscriber device #1 and subscriber device #A (step S701).

[0118] Next, the optical SW management unit 22 and wavelength management unit 24 of the control device 20 respectively determine the optical path and wavelength to be used in the communication between the subscriber device #1 and the subscriber device #A (step S702). Note that if the subscriber device 11 can select signal parameters such as modulation method, baud rate, and transmission light intensity from multiple candidates for its own communication, the control device 20 may further determine such signal parameters in addition to the optical path and wavelength.

[0119] Next, the control device 20 instructs subscriber device #1 of the wavelength determined in step S702 via the control signal superimposition / extraction unit 14. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #1 of the determined signal parameters. Upon receiving the notification, subscriber device #1 transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #1. In accordance with the notification received from the control device 20, subscriber device #1 switches the wavelength used for communication by itself to the notified wavelength.

[0120] The control device 20 instructs subscriber device #A of the wavelength determined in step S702 via the control signal superimposition / extraction unit 14. At this time, if the control device 20 has determined signal parameters, it may also notify subscriber device #A of the determined signal parameters. Upon receiving the notification, subscriber device #A transmits an ACK to the control device 20 in response to the received notification. The control device 20 receives the ACK from subscriber device #A. In accordance with the notification received from the control device 20, subscriber device #A switches the wavelength used for communication by its own device to the notified wavelength (step S703).

[0121] The optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #1 to connect the subscriber device #1 to the input / output port 131 corresponding to the optical path determined in step S702. Also, the optical SW management unit 22 of the control device 20 switches the connection between the input / output ports 131 of the optical SW #2 to connect the subscriber device #A to the input / output port 131 corresponding to the optical path determined in step S702 (step S704).

[0122] Thereafter, the subscriber devices #1 and #A start communication on a new optical path via the optical SW13 and the inside of the optical communication network (step S705).

[0123] In a seventh operation example of the communication system configured in this manner, it is possible to change the optical path between the subscriber devices 11 in accordance with the operation of the optical path switching determination unit 17. Specifically, it is as follows. In the communication system 100c, in response to the satisfaction of the optical path switching condition, the control device 20 transmits a wavelength instruction to each subscriber device 11 via the control signal superimposition / extraction unit 14. Therefore, in the communication system 100, even after the optical path between the subscriber devices 11 has been established, it is possible to change the communication (change the optical path) in accordance with the operation of the optical path switching determination unit 17.

[0124] Furthermore, in the process of changing the optical path, there is no need to take the trouble of connecting each of the subscriber devices 11 (subscriber device #1 and subscriber device #A) to the control port 132. This makes it possible to change the optical path with a smaller amount of processing. As a result, for example, it becomes possible to change the optical path in a shorter time.

[0125] (Modified Operation) Next, a description will be given of modified examples of the operations shown in Figures 11 to 14. First, a modification of the fourth operation example shown in Figure 11 will be described.

[0126] The order of the processes of steps S402 and S403 may be reversed. The process of step S405 may be performed before step S402, before step S403, or before step S404. In addition, in the process of each step, the operation of sending and receiving an ACK may be omitted. Furthermore, after the process of step S401 or step S402, the control device 20 may notify the subscriber device 11 via the control signal superimposition extraction unit 14 that optical path switching will be performed thereafter. With this configuration, each subscriber device 11 can distinguish between a main signal interruption caused by switching of the optical SW in step S403 and a fault (i.e., determine that it is not a fault).

[0127] Furthermore, an in-band method may be used for transmitting and receiving control signals between subscriber device #1 and subscriber device #A, in which the signals are transmitted within the overhead of a protocol. Similarly, an in-band method may be used for transmitting and receiving control signals between subscriber device 11 and the control TRx 26, in which the signals are transmitted within the overhead of a protocol. The in-band method may also be used in a configuration in which a control signal is transmitted from subscriber device 11 and received by the control TRx 26. For example, an area called GCC in the network monitoring overhead in OTN, which is widely used in high-capacity long-distance optical transmission networks, may be used as the in-band method. For example, the method disclosed in the above-mentioned reference may be applied to such a configuration.

[0128] Next, a modified example of the fifth operation example shown in Fig. 12 will be described. The order of the processes of step S502 and step S503 may be reversed. Furthermore, in the processes of each step, the operation of sending and receiving an ACK may be omitted. Furthermore, after the process of step S501 or step S502, the control device 20 may notify the subscriber device 11 via the control signal superimposition extraction unit 14 that optical path switching will be performed thereafter. With this configuration, the subscriber device 11 (subscriber device #A) can distinguish between a main signal interruption caused by switching of optical SW #2 in step S505 and a fault (i.e., determine that it is not a fault).

[0129] Next, a modified example of the sixth operation example shown in Fig. 13 will be described. The order of the processes of step S602 and step S603 may be reversed. Furthermore, in the processes of each step, the operation of sending and receiving an ACK may be omitted. Furthermore, after the process of step S601 or step S602, the control device 20 may notify each subscriber device 11 via the control signal superimposition extraction unit 14 that optical path switching will be executed thereafter. With this configuration, each subscriber device 11 can distinguish between a main signal interruption caused by switching of the optical SW in step S603 and a fault (i.e., determine that it is not a fault).

[0130] Next, a modified example of the seventh operation example shown in Fig. 14 will be described. In the processing of each step, the operation of sending or receiving an ACK may be omitted. Furthermore, after the processing of step S701 or step S702, the control device 20 may notify each subscriber device 11 via the control signal superimposition extraction unit 14 that optical path switching will be performed thereafter. With this configuration, each subscriber device 11 can distinguish between the main signal interruption caused by switching of the optical SW in step S704 and a fault (i.e., determine that it is not a fault).

[0131] The instruction to the subscriber device #1 in step S703 may use, for example, light emitted by the subscriber device #A. More specifically, for example, an AMCC signal indicating the wavelength instruction may be superimposed on the optical signal transmitted from the subscriber device #A. This process cannot be performed if a failure or the like occurs in the optical transmission path between the subscriber device #1 and the subscriber device #A.

[0132] The instruction to the subscriber device #A in step S703 may use, for example, light emitted by the subscriber device #1. More specifically, for example, an AMCC signal indicating the wavelength instruction may be superimposed on the optical signal transmitted from the subscriber device #1. This process cannot be performed if a failure or the like occurs in the optical transmission path between the subscriber device #1 and the subscriber device #A.

[0133] (Variations of the configuration) Fig. 15 is a diagram illustrating an example of a system configuration of a modified example (communication system 100d) of the communication system of the second embodiment. The communication system 100d illustrated in Fig. 15 has a configuration in which an optical path switching determining unit 17 is provided in the communication system 100a illustrated in Fig. 7.

[0134] 16 is a diagram illustrating an example of a system configuration of a modified example (communication system 100e) of the communication system of the second embodiment. The communication system 100e illustrated in FIG. 16 has a configuration in which an optical path switching determining unit 17 is provided in the communication system 100b illustrated in FIG.

[0135] The fourth operation example shown in Fig. 11 may be executed in the communication system 100d shown in Fig. 15, or may be executed in the communication system 100e shown in Fig. 16. The sixth operation example shown in Fig. 13 may be executed in the communication system 100d shown in Fig. 15, or may be executed in the communication system 100e shown in Fig. 16.

[0136] When applied to the above-described operational example, each of the communication systems (communication system 100d and communication system 100e) according to these modified configurations can also achieve the same technical effects as those of communication system 100.

[0137] Next, the operation of the optical path switching determining unit 17 will be described in more detail. As described above, the optical path switching determining unit 17 determines the connection destination switching conditions and the optical path switching conditions. Specific examples of these conditions include the satisfaction of the conditions related to switching to a backup path (redundant path), the satisfaction of the conditions related to switching for load balancing, and the occurrence of a line failure. As a specific example of these conditions, the details of the determination process for the conditions related to a line failure will be described.

[0138] The line fault may be detected in the subscriber device 11. For example, the subscriber device 11 determines whether the received signal can be correctly decoded. If the signal cannot be correctly decoded, the subscriber device 11 determines that a line fault has occurred. In this case, the subscriber device 11 may notify the control device 20 of the line fault via the control port 132. The subscriber device 11 may also notify the optical path switching determination unit 17 of the line fault. With this configuration, it is possible to detect, as a line fault, a case in which an optical signal of sufficient strength is input but sufficient receiving sensitivity is not obtained due to the influence of noise or the like.

[0139] Other configurations for detecting a line fault are possible. A specific example of such a configuration will be described with reference to FIG. 17. FIG. 17 is a diagram showing a specific configuration for determining a line fault in the second embodiment shown in FIG. 10. In FIG. 17, the communication system 100c further includes an inline power monitor 18. The optical SW 13 further includes a power monitor 133. The inline power monitor 18 is provided for each line between the optical SW 13 and the wavelength multiplexing / demultiplexing unit 15. Each inline power monitor 18 outputs a signal indicating the intensity of an optical signal passing through the line on which the inline power monitor 18 is provided to the optical path switching determiner 17. The power monitor 133 outputs a signal indicating the intensity of an optical signal passing through the optical SW 13 to the optical path switching determiner 17. For example, the power monitor 133 may output a signal indicating the intensity of an optical signal for each input / output port 131 to the optical path switching determiner 17.

[0140] The optical SW 13 may detect a line fault based on a signal output from the power monitor 133. That is, the optical SW 13 may determine that a line fault has occurred when the received optical intensity of the optical signal received by the optical SW 13 is lower than a threshold value based on the signal output from the power monitor 133. The optical SW 13 may notify the optical path switching determiner 17 of the line fault.

[0141] The optical path switching determining unit 17 may detect a line fault based on a signal output from the inline power monitor 18. That is, the optical path switching determining unit 17 may determine that a line fault has occurred when the received optical intensity of the optical signal is lower than a threshold based on the signal output from the inline power monitor 18. The installation location of the inline power monitor 18 does not need to be limited to the installation location shown in FIG. 17. For example, the inline power monitor 18 may be installed between the subscriber device 11 and the optical SW 13. Furthermore, when a configuration is adopted that allows optical signals to be demultiplexed into wavelengths and then detected, the inline power monitor 18 may be installed somewhere along the optical transmission lines 1 to 3.

[0142] 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. [Industrial Applicability]

[0143] The present invention is applicable to an optical communication network using optical switches. [Explanation of symbols]

[0144] 100, 100a, 100b...communication system, 11...subscriber device, 12...wavelength filter, 13...optical SW, 133...power monitor, 14...control signal superimposition / extraction unit, 141...optical branching unit, 142...optical modulation unit, 15...wavelength multiplexing / demultiplexing unit, 16...control signal extraction unit, 17...optical path switching determination unit, 18...inline power monitor, 20...control device, 21...optical path management table storage unit, 22...optical SW management unit, 23...wavelength management table storage unit, 24...wavelength management unit, 25...control optical TRx, 26...control TRx, 261...optical Rx, 262...Tx

Claims

1. A communication method performed by a communication system including a plurality of optical switches connecting an optical communication network and information devices, and a control device that controls the optical switches, comprising: a switching step in which, in a state in which a first information device and a second information device are communicatively connected via the optical switch and the optical communication network, the optical switch to which the first information device is connected switches the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected, which allocates wavelengths used for communication to each information device according to its destination, in response to a predetermined operation of the first information device; a receiving step in which the control device receives, from the first information device, information indicating a third information device that is a communication connection destination different from the second information device, via the control port of the optical switch; an allocation step in which the control device allocates wavelengths to be used in communication to the first information device and the third information device based on the information indicating the communication connection destination; a connecting step in which the control device controls a connection of an input / output port of the optical switch to communicably connect the first information device to the third information device; and the predetermined operation is that the first information device stops emitting light onto the communication path and starts emitting light onto the communication path after at least a predetermined time has elapsed; the first information device transmits a disconnection request to the second information device and the control device before performing the predetermined operation, and thereafter the first information device stops emitting light onto the communication path as part of the predetermined operation, and the second information device stops emitting light onto the communication path in response to the disconnection request; the control device opens input / output ports connected to the first information device and the second information device in response to the stop of light emission of the first information device and the second information device; The first information device restarts emitting light onto the communication path after at least a predetermined time has elapsed since the first information device stopped emitting light onto the communication path.

2. A communication method performed by a communication system including a plurality of optical switches connecting an optical communication network and information devices, a control device that controls the optical switches, and a branching device that branches an optical signal output from the optical switches toward the optical communication network toward the control device, the method comprising: a receiving step in which, in a state in which a first information device and a second information device are communicatively connected via the optical switch and the optical communication network, the control device, which assigns wavelengths used for communication to each information device according to a destination, receives, from the first information device, information indicating a third information device that is a communication connection destination different from the second information device, via the branching device; an allocation step in which the control device allocates wavelengths to be used in communication to the first information device and the third information device based on the information; a step of instructing the control device to stop light emission of another information device different from the first information device via a control port; a connecting step in which the control device controls a connection of an input / output port of the optical switch to communicably connect the first information device to the third information device; A communication method comprising:

3. A system including a plurality of optical switches that connect an optical communication network and information devices, and a control device that controls the optical switches, The control device an optical SW management unit that controls, in a state where a first information device and a second information device are communicatively connected via the optical switch and the optical communication network, in accordance with a predetermined operation of the first information device, the optical switch to which the first information device is connected to switch the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected, which allocates wavelengths used for communication to each information device according to its destination; an optical receiver that receives, from the first information device, information indicating a third information device that is a communication connection destination different from the second information device, via the control port of the optical switch; the control device comprises a wavelength management unit that allocates wavelengths to be used in communication to the first information device and the third information device based on the information indicating the communication destination; the optical SW management unit controls a connection of an input / output port of the optical switch to communicably connect the first information device to the third information device; the predetermined operation is that the first information device stops emitting light onto the communication path and starts emitting light onto the communication path after at least a predetermined time has elapsed; the first information device transmits a disconnection request to the second information device and the control device before performing the predetermined operation, and thereafter the first information device stops emitting light onto the communication path as part of the predetermined operation, and the second information device stops emitting light onto the communication path in response to the disconnection request; the control device opens input / output ports connected to the first information device and the second information device in response to the stop of light emission of the first information device and the second information device; The first information device resumes emitting light onto the communication path after at least a predetermined time has elapsed since the first information device stopped emitting light onto the communication path.

4. a branching device that branches an optical signal output from the optical switch toward the optical communication network toward the control device; 4. The communication system according to claim 3, wherein the predetermined operation is for the first information device to transmit information indicating that communication with the second information device is to be terminated to the control device via the branching device.

5. a plurality of optical switches connecting an optical communication network and information devices; a control device controlling the optical switches; and a branching device branching an optical signal output from the optical switches toward the optical communication network toward the control device; The control device an optical receiver configured to receive, via the branching device, information indicating a third information device that is a communication connection destination different from the second information device, from the first information device, in a state in which a first information device and a second information device are communicatively connected via the optical switch and the optical communication network, the control device allocating a wavelength used for communication to each information device according to a destination; an allocation management unit that allocates wavelengths to be used in communication to the first information device and the third information device based on the information; an optical SW management unit that controls connections of input / output ports of the optical switch to communicably connect the first information device to the third information device; Equipped with The control device instructs other information devices different from the first information device to stop emitting light via a control port.

6. A communication method performed by a communication system including a plurality of optical switches connecting an optical communication network and information devices, and a control device that controls the optical switches, comprising: a switching step in which, in a state in which a first information device is communicatively connected to other information devices via the optical switch and the optical communication network, the optical switch to which the first information device is connected switches the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected, which allocates wavelengths used for communication to each information device according to its destination; a step of instructing the control device to stop light emission of the other information device via a control port; an allocation step in which the control device allocates a new wavelength to be used in communication to the first information device via the control port; a connecting step in which the control device controls connections of input / output ports of the optical switch to connect the first information device to another information device via a new communication path so that the first information device can communicate with another information device; A communication method comprising:

7. A system including a plurality of optical switches that connect an optical communication network and information devices, and a control device that controls the optical switches, The control device an optical SW management unit that controls, in a state in which a first information device is communicatively connected to other information devices via the optical switch and the optical communication network, the optical switch to which the first information device is connected so as to switch the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected, which allocates wavelengths used for communication to each information device according to its destination; the control device comprises a wavelength management unit that allocates a new wavelength to be used in communication to the first information device via the control port; the optical SW management unit controls connections of input / output ports of the optical switch to connect the first information device to other information devices via a new communication path so that the first information device can communicate with other information devices; the optical SW management unit controls, in accordance with a predetermined operation of the first information device, an optical switch to which the first information device is connected, to switch a connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected; the predetermined operation is that the first information device stops emitting light onto the communication path and starts emitting light onto the communication path after at least a predetermined time has elapsed; the first information device transmits a disconnection request to the other information device and the control device before performing the predetermined operation, and thereafter the first information device stops emitting light onto the communication path as part of the predetermined operation, and the other information device stops emitting light onto the communication path in response to the disconnection request; the control device opens input / output ports connected to the first information device and the other information device in response to the stop of light emission of the first information device and the other information device; The first information device resumes emitting light onto the communication path after at least a predetermined time has elapsed since the first information device stopped emitting light onto the communication path.

8. The optical communication network further includes an optical path switching determination unit that determines to switch the communication path of the first information device when a predetermined condition is satisfied, The communication system described in claim 7, wherein the optical SW management unit controls, in accordance with the operation of the optical path switching determination unit, an optical switch to which the first information device is connected to switch the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected.

9. 9. The communication system according to claim 8, wherein the optical path switching determining unit determines whether the condition is satisfied based on the intensity of an optical signal passing through the optical communication network or the optical switch.

10. the optical SW management unit, in a state in which the first information device and the second information device are communicatively connected via the optical switch and the optical communication network, controls the optical switch to which the first information device is connected to switch the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected, and controls the optical switch to which a third information device that will be a new communication destination of the first information device is connected to switch the connection destination of the third information device to the control port to which the control device is connected; 10. The communication system according to claim 8, wherein the wavelength management unit allocates wavelengths to be used in communication to the first information device and the third information device via the control port.

11. a multiplexing device that multiplexes a signal output from the control device with an optical signal input from the optical communication network to the optical switch; the optical SW management unit controls an optical switch to which a third information device that will be a new communication destination of the first information device is connected, in a state in which the first information device and the second information device are communicatively connected via the optical switch and the optical communication network, so as to switch the connection destination of the third information device to a control port to which the control device is connected; 10. The communication system according to claim 8, wherein the wavelength management unit assigns a wavelength to be used in communication to the first information device via the multiplexing device, and assigns a wavelength to be used in communication to the third information device via the control port.

12. the optical SW management unit, in a state in which the first information device and the second information device are communicatively connected via the optical switch and the optical communication network, controls the optical switch to which the first information device is connected to switch the connection destination of the first information device from an input / output port connected to the optical communication network to a control port to which the control device is connected, and controls the optical switch to which the second information device is connected to switch the connection destination of the second information device to the control port to which the control device is connected; 10. The communication system according to claim 8, wherein the wavelength management unit allocates wavelengths to be used in communication to the first information device and the second information device via the control port.

13. a plurality of optical switches connecting an optical communication network and information devices; a control device for controlling the optical switches; a multiplexing device for multiplexing signals output from the control device, which allocates wavelengths used for communication to each information device according to its destination, with optical signals input from the optical communication network to the optical switches; and an optical path switching determination unit for determining switching of communication paths between information devices when a predetermined condition is satisfied in the optical communication network; The control device an optical SW management unit that controls the optical switch; a wavelength management unit that allocates, via the multiplexing device, new wavelengths to be used in communication to a first information device and a second information device communicating via the optical switch and the optical communication network in response to an operation of the optical path switching determination unit; the optical SW management unit controls connections of input / output ports of the optical switch to communicably connect the first information device to the second information device via a new communication path; The control device instructs other information devices different from the first information device to stop emitting light via a control port.

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