Branch device and control method of the branch device

Abstract

To provide a branch device capable of reducing the number of optical switches for establishing a path of optical communication between end stations, and provide a control method of the branch device.SOLUTION: A branch device 100 of the present disclosure, comprises an optical driving circuit 20 containing a first optical switch SW1 and a second optical switch SW2. A first input port 11 of the first optical switch SW1 is connected to a first transmission path A1 connected to a first end station A. A second input port 12 is connected to a first transmission path C1 connected to a third end station C. A first output port 13 is connected to a first input port 21 of the second optical switch SW2. A second output port 14 is connected to a first transmission path B1 connected to a second end station B. A second input port 22 of the second optical switch SW2 is connected to a second transmission path B2 connected to the second end station B. A first output port 23 is connected to a second transmission path A2 connected to the first end station A. A second output port 24 is connected to a second transmission path C2 connected to the third end station C.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a branching device and a method for controlling the branching device. [Background technology]

[0002] In a submarine optical cable system, optical transmission devices installed at land terminal stations transmit wavelength-multiplexed optical signals via a submarine optical cable. A branching device is installed in the middle of the submarine optical cable connecting the first terminal station and the second terminal station, and is further connected to a third terminal station via the submarine optical cable. The branching device branches the optical signal transmitted between the first terminal station and the second terminal station to the third terminal station, enabling the first terminal station or the second terminal station to optically communicate with the third terminal station.

[0003] Patent document 1 discloses a branching device having a circuit in which 1×2 optical switches and 2×2 optical switches are connected in multiple stages to establish a path for branching an optical signal transmitted between a first terminal station and a second terminal station to a third terminal station. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 194842 Summary of the Invention [Problem to be solved by the invention]

[0005] The branching device according to Patent Document 1 has a problem of reducing the number of optical switches for establishing paths of optical communication between terminal stations. For example, the branching device according to Patent Document 1 has a limit on the number of fiber pairs connected to terminal stations due to the upper limit on the number of optical switches mounted in the branching device's housing. In addition, the branching device according to Patent Document 1 needs to secure space within the housing because there is a possibility that other information processing devices will be accommodated in the branching device's housing.

[0006] In consideration of such problems, the present disclosure aims to provide a branching device and a control method for a branching device that can reduce the number of optical switches for establishing optical communication paths between terminal stations. [Means for solving the problem]

[0007] The branching device of the present disclosure is a first optical switch having a first input port and a second input port for inputting an optical signal and a first output port and a second output port for outputting an optical signal, the first optical switch being capable of switching a transmission path of the optical signal between the input port and the output port; a first input port of the first optical switch is connected to a first transmission line connected to a first terminal station, a second input port of the first optical switch is connected to a first transmission line connected to a third terminal station, a first output port of the first optical switch is connected to a transmission line connected to a first input port of the second optical switch, and a second output port of the first optical switch is connected to a first transmission line connected to a second terminal station; The second optical switch includes an optical switch drive circuit, the first input port of which is connected to a transmission line connected to a first output port of the first optical switch, the second input port of which is connected to a second transmission line connected to the second terminal station, the first output port of which is connected to a second transmission line connected to the first terminal station, and the second output port of which is connected to a second transmission line connected to the third terminal station.

[0008] The method for controlling a branching device according to the present disclosure includes: a first optical switch having a first input port and a second input port for inputting an optical signal and a first output port and a second output port for outputting an optical signal, the first optical switch being capable of switching a transmission path of the optical signal between the input port and the output port; a first input port of the first optical switch is connected to a first transmission line connected to a first terminal station, a second input port of the first optical switch is connected to a first transmission line connected to a third terminal station, a first output port of the first optical switch is connected to a transmission line connected to a first input port of the second optical switch, and a second output port of the first optical switch is connected to a first transmission line connected to a second terminal station; an optical switch drive circuit, a first input port of the second optical switch connected to a transmission line connected to a first output port of the first optical switch, a second input port of the second optical switch connected to a second transmission line connected to the second terminal station, a first output port of the second optical switch connected to a second transmission line connected to the first terminal station, and a second output port of the second optical switch connected to a second transmission line connected to the third terminal station; The switching of the transmission paths in the first and second optical switches is controlled. Effect of the Invention

[0009] The present disclosure makes it possible to provide a branching device and a method for controlling a branching device that can reduce the number of optical switches for establishing paths for optical communication between terminal stations. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing an example of a configuration of an optical switch driver circuit 20 of a branching device 100 according to the present disclosure. [Diagram 2] 2 is a block diagram showing an example of a configuration of a branching device 200 according to the present disclosure. FIG. [Diagram 3] 2 is a diagram showing an outline of a path configuration established in an optical switch driver circuit 20 of a branching device 200 according to the present disclosure. FIG. [Figure 4] 2 is a diagram showing an example of a path configuration state established in an optical switch driver circuit 20 of a branching device 200 according to the present disclosure. FIG. [Diagram 5] 10 is a diagram illustrating an example of the configuration of the optical switch driver circuit 20 of the branching device 200 according to the present disclosure in State 2. FIG. [Figure 6] 11 is a diagram illustrating an example of the configuration of the optical switch driver circuit 20 of the branching device 200 according to the present disclosure in State 3. FIG. [Figure 7] 13 is a diagram illustrating an example of the configuration of the optical switch driver circuit 20 of the branching device 200 according to the present disclosure in State 5. FIG. [Figure 8]11 is a diagram illustrating an example of the configuration of an optical switch driver circuit 20R of a branching device 200R according to a first comparative example in State 2. FIG. [Figure 9] 11 is a diagram illustrating an example of the configuration of an optical switch driver circuit 20R of a branching device 200R according to a first comparative example in State 3. FIG. [Figure 10] 13 is a diagram illustrating an example of the configuration of an optical switch driver circuit 20R of a branching device 200R according to a first comparative example in State 5. FIG. [Figure 11] 1 is a block diagram showing an example of a configuration of a computer 1000 according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the following, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In each drawing, the same elements are given the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0012] (First embodiment) First, the configuration of a branching device 100 according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the configuration of an optical switch driver circuit 20 of the branching device 100 according to the first embodiment.

[0013] The branching device 100 of the present disclosure includes an optical switch driving circuit 20. The optical switch driving circuit 20 has first and second input ports to which an optical signal is input and first and second output ports to which an optical signal is output, and includes a first optical switch SW1 and a second optical switch SW2 that are capable of switching the transmission path of the optical signal between the input port and the output port.

[0014] The first optical switch SW1 has a first input port 11, a second input port 12, a first output port 13, and a second output port 14. The first input port 11 of the first optical switch SW1 is connected to a first transmission line A1 that connects to a first terminal station A. The second input port 12 is connected to a first transmission line C1 that connects to a third terminal station C. The first output port 13 is connected to a transmission line that connects to the first input port 21 of the second optical switch SW2. The second output port 14 is connected to a first transmission line B1 that connects to a second terminal station B.

[0015] The second optical switch SW2 has a first input port 21, a second input port 22, a first output port 23, and a second output port 24. The first input port 21 of the second optical switch SW2 is connected to a transmission line connected to the first output port 13 of the first optical switch SW1. The second input port 22 is connected to a second transmission line B2 connected to the second terminal station B. The first output port 23 is connected to a second transmission line A2 connected to the first terminal station A. The second output port 24 is connected to a second transmission line C2 connected to the third terminal station C.

[0016] The branching device 100 according to the first embodiment configures an optical switch driving circuit 20 using an optical switch SW of a 2×2 optical switch instead of a 1×2 optical switch. In this way, the branching device 100 can reduce the number of optical switches SW required to establish a path of optical communication between terminal stations.

[0017] Second embodiment Next, the configuration of a branching device 200 according to the second embodiment will be described with reference to FIGS.

[0018] Fig. 2 is a block diagram showing an example of the configuration of a branching device 200 according to the present disclosure. As shown in Fig. 2, the branching device 200 is a branching device installed on the seabed in a submarine optical cable system. The branching device 200 includes an optical switch driving circuit 20 and a control unit 10.

[0019] The control unit 10 controls the optical switch driving circuit 20. For example, the control unit 10 controls the optical switch driving circuit 20 based on a control signal from an external device located remote from the branching device 200.

[0020] The optical switch driving circuit 20 is connected to the transmission lines (optical submarine cables) connected to the first terminal station A, the second terminal station B, and the third terminal station C, respectively. The first terminal station A, the second terminal station B, and the third terminal station C are terminal station devices installed on land and terminating the transmission lines. The first terminal station A and the second terminal station B are trunk stations. The third terminal station C is a branch station. Specifically, the optical switch driving circuit 20 is connected to the first transmission line A1 and the second transmission line A2 connected to the first terminal station A. The branching device 200 is connected to the first transmission line B1 and the second transmission line B2 connected to the second terminal station B. The branching device 200 is also connected to the first transmission line C1 and the second transmission line C2 connected to the third terminal station C. Here, each transmission line is composed of an input / output fiber pair.

[0021] The optical switch driver circuit 20 then branches a wavelength-multiplexed optical signal (hereinafter, optical signal) transmitted and received between the first terminal station A and the second terminal station B, which are trunk stations, to the third terminal station C, which is a branch station, so that the first terminal station A or the second terminal station B can optically communicate with the third terminal station C. Specifically, as shown below, the optical switch driver circuit 20 establishes routes for all possible combinations between two branches among the three branches of the first terminal station A, the second terminal station B, and the third terminal station C.

[0022] FIG. 3 is a diagram showing an overview of the path configuration established in the optical switch drive circuit 20 of the branching device 200 of the present disclosure. FIG. 4 is a diagram showing an example of the path configuration state established in the optical switch drive circuit 20 of the branching device 200 of the present disclosure. As shown in FIGS. 3 and 4, the optical switch drive circuit 20 establishes optical paths in State2, State3, and State5 among the path configuration states from State1 to State5. In State2, the optical switch drive circuit 20 establishes optical paths between the first transmission line A1 and the first transmission line B1, between the second transmission line A2 and the first transmission line C1, and between the second transmission line B2 and the second transmission line C2. Also, in State3, the optical switch drive circuit 20 establishes optical paths between the first transmission line A1 and the first transmission line B1 and between the second transmission line A2 and the second transmission line B2. Also, in State5, the optical switch drive circuit 20 establishes optical paths between the first transmission line B1 and the first transmission line C1 and between the second transmission line B2 and the second transmission line C2.

[0023] Subsequently, with reference to FIGS. 5 to 7, the specific configuration of the optical switch drive circuit 20 of the branching device 200 of the present disclosure will be described.

[0024] FIG. 5 is a diagram showing an example of the configuration in State2 of the optical switch drive circuit 20 of the branching device 200 of the present disclosure. FIG. 6 is a diagram showing an example of the configuration in State3 of the optical switch drive circuit 20 of the branching device 200 of the present disclosure. FIG. 7 is a diagram showing an example of the configuration in State5 of the optical switch drive circuit 20 of the branching device 200 of the present disclosure.

[0025] <Configuration of the optical switch drive circuit 20 common to State2, 3, and 5> 5 to 7, the optical switch driving circuit 20 of the branching device 200 includes a first optical switch SW1, a second optical switch SW2, a third optical switch SW3, and a fourth optical switch SW4 (collectively referred to as optical switch SW). Each optical switch SW is a 2×2 optical switch. The optical switch SW is, for example, an optical waveguide switch, a mechanical switch, or a MEMS (micro electro mechanical systems) switch. Each optical switch SW includes two input ports for optical signals and two output ports for optical signals, and switches a connection between a predetermined input port and an output port to a connection between another input port and an output port.

[0026] The first optical switch SW1 has a first input port 11, a second input port 12, a first output port 13, and a second output port 14. The first input port 11 of the first optical switch SW1 is connected to the first transmission line A1. The second input port 12 of the first optical switch SW1 is connected to the first transmission line C1. The first output port 13 of the first optical switch SW1 is connected to a transmission line that is connected to the first input port 21 of the second optical switch SW2. The second output port 14 of the first optical switch SW1 is connected to the first transmission line B1.

[0027] The second optical switch SW2 has a first input port 21, a second input port 22, a first output port 23, and a second output port 24. The first input port 21 of the second optical switch SW2 is connected to the first output port 13 of the first optical switch SW1. The second input port 22 of the second optical switch SW2 is connected to the second transmission path B2. The first output port 23 of the second optical switch SW2 is connected to the second transmission path A2. The second output port 24 of the second optical switch SW2 is connected to the second transmission path C2.

[0028] The third optical switch SW3 has a first input port 31, a second input port 32, a first output port 33, and a second output port 34. The first input port 31 of the third optical switch SW3 is connected to the first output port 43 of the fourth optical switch SW4. The second input port 32 of the third optical switch SW3 is connected to the first transmission line B1. The first output port 33 of the third optical switch SW3 is connected to the first transmission line A1. The second output port 34 of the third optical switch SW3 is connected to the first transmission line C1.

[0029] The fourth optical switch SW4 has a first input port 41, a second input port 42, a first output port 43, and a second output port 44. The first input port 41 of the fourth optical switch SW4 is connected to the second transmission line A2. The second input port 42 of the fourth optical switch SW4 is connected to the second transmission line C2. The first output port 43 of the fourth optical switch SW4 is connected to the first input port 31 of the third optical switch SW3. The second output port 44 of the fourth optical switch SW4 is connected to the second transmission line B2.

[0030] <Configuration of the optical switch drive circuit 20 for each of State2, 3, and 5> In State 2, as shown in FIG. 5, the first optical switch SW1 and the third optical switch SW3 of the optical switch driving circuit 20 are connected to the horizontal path. The second optical switch SW2 and the fourth optical switch SW4 are connected to the vertical path. Specifically, the first optical switch SW1 connects the first input port 11 to the second output port 14, and also connects the second input port 12 to the first output port 13. The second optical switch SW2 connects the first input port 21 to the first output port 23, and also connects the second input port 22 to the second output port 24. The third optical switch SW3 connects the second input port 32 to the first output port 33, and also connects the first input port 31 to the second output port 34. The fourth optical switch SW4 connects the first input port 41 to the first output port 43, and also connects the second input port 42 to the second output port 44. In this way, the optical switch driver circuit 20 realizes bidirectional optical communication between the first transmission line A1 and the first transmission line B1, between the second transmission line A2 and the first transmission line C1, and between the second transmission line C2 and the second transmission line B2. When an optical communication path is established between the first transmission line C1 and the second transmission line C2 in the third terminal station C, the optical switch driver circuit 20 realizes bidirectional optical communication between the second transmission line A2 and the second transmission line B2.

[0031] In State 3, as shown in FIG. 6, the first optical switch SW1, the second optical switch SW2, the third optical switch SW3, and the fourth optical switch SW4 of the optical switch driving circuit 20 are connected to the horizontal path. Specifically, the first optical switch SW1 connects the first input port 11 to the second output port 14, and also connects the second input port 12 to the first output port 13. The second optical switch SW2 connects the first input port 21 to the second output port 24, and also connects the second input port 22 to the first output port 23. The third optical switch SW3 connects the first input port 31 to the second output port 34, and also connects the second input port 32 to the first output port 33. The fourth optical switch SW4 connects the first input port 41 to the second output port 44, and also connects the second input port 42 to the first output port 43. In this way, the optical switch driver circuit 20 realizes bidirectional optical communication between the first transmission line A1 and the first transmission line B1 and between the second transmission line A2 and the second transmission line B2.

[0032] In State 5, as shown in FIG. 7, the first optical switch SW1, the second optical switch SW2, the third optical switch SW3, and the fourth optical switch SW4 of the optical switch driving circuit 20 are each connected to a vertical path. Specifically, the first optical switch SW1 connects the first input port 11 to the first output port 13, and also connects the second input port 12 to the second output port 14. The second optical switch SW2 connects the first input port 21 to the first output port 23, and also connects the second input port 22 to the second output port 24. The third optical switch SW3 connects the first input port 31 to the first output port 33, and connects the second input port 32 to the second output port 34. The fourth optical switch SW4 connects the first input port 41 to the first output port 43, and also connects the second input port 42 to the second output port 44. In this way, the optical switch driver circuit 20 realizes bidirectional optical communication between the first transmission line B1 and the first transmission line C1 and between the second transmission line B2 and the second transmission line C2.

[0033] In States 2, 3, and 5, the control unit 10 controls switching between the horizontal path connection and the vertical path connection in the first optical switch SW1 to the fourth optical switch SW4 of the optical switch driver circuit 20.

[0034] As described above, the branching device 200 according to the second embodiment configures the optical switch driving circuit 20 using the optical switches SW of the 2×2 optical switches instead of the 1×2 optical switches. In this way, the branching device 200 can reduce the number of optical switches SW required to establish a path of optical communication between the first terminal station A, the second terminal station B, and the third terminal station C.

[0035] For example, the branching device 200 can reduce the number of optical switches SW required to establish an optical communication path between the first terminal station A and the third terminal station C to half that of the branching device of Patent Document 1. The branching device of Patent Document 1 requires eight 1×2 optical switches for two transmission lines connected respectively from the first terminal station A, the second terminal station B, and the third terminal station C. On the other hand, the branching device 200 of this embodiment requires four 2×2 optical switches for two transmission lines connected respectively from the first terminal station A, the second terminal station B, and the third terminal station C. Therefore, the branching device 200 can reduce the number of optical switches SW required to half.

[0036] Furthermore, the branching device 200 can reduce the number of optical switches SW required to establish an optical communication path between the first terminal station A and the third terminal station C to half that of the optical switch driving circuit 20R of the branching device 200R according to the first comparative example shown in the following Figs. 8 to 10. Fig. 8 shows an example of the configuration of the optical switch driving circuit 20R of the branching device 200R according to the first comparative example in State 2. Fig. 9 shows an example of the configuration of the optical switch driving circuit 20R of the branching device 200R according to the first comparative example in State 3. Fig. 10 shows an example of the configuration of the optical switch driving circuit 20R of the branching device 200R according to the first comparative example in State 5. As shown in Figs. 8 to 10, the branching device 200R of the first comparative example requires eight 1x2 optical switches (optical switches SW1R to SW8R) for two transmission lines connected from the first terminal station A, the second terminal station B, and the third terminal station C, respectively. On the other hand, the branching device 200 of this embodiment requires four 2×2 optical switches for two transmission lines respectively connected from the first terminal station A, the second terminal station B, and the third terminal station C. Therefore, the branching device 200 can reduce the number of required optical switches SW by half.

[0037] Therefore, the branching device 200 can reduce the number of optical switches SW required to establish a path. Therefore, the branching device 200 can secure space in the housing of the branching device 200 by the reduced number of optical switches SW. Therefore, the branching device 200 can increase the number of transmission paths connecting to terminal stations and optical switches SW. Furthermore, the branching device 200 can increase the number of optical switches SW that can be mounted in the housing. Furthermore, the branching device 200 can increase the number of other information processing devices that can be mounted in the housing. Furthermore, the branching device 200 can reduce the necessary costs by the reduced number of optical switches SW.

[0038] <Hardware configuration> Next, an example of a hardware configuration of the computer 1000 will be described with reference to FIG. 11. In FIG. 11, the computer 1000 has a processor 1001 and a memory 1002. The processor 1001 may be, for example, a microprocessor, a micro processing unit (MPU), or a central processing unit (CPU). The processor 1001 may include multiple processors. The memory 1002 is configured by a combination of a volatile memory and a non-volatile memory. The memory 1002 may include a storage located away from the processor 1001. In this case, the processor 1001 may access the memory 1002 via an I / O interface not shown.

[0039] The functions (processing) of each component (e.g., control unit 10) of branching device 100 and branching device 200 in the above-described embodiments may be realized by computer 1000. For example, a program for performing the method in the embodiment may be stored in memory 1002, and each function may be realized by executing the program stored in memory 1002 by processor 1001. Also, each component in the above-described embodiments may be configured by hardware or software, or both, and may be configured by one piece of hardware or software, or may be configured by multiple pieces of hardware or software.

[0040] These programs include instructions (or software codes) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disc (DVD), Blu-ray® disk or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The programs may be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, a transitory computer-readable medium or a communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0041] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present invention.

[0042] In the above embodiment, the optical switch driver 20 of the branching device 200 establishes optical paths in State 2, State 3, and State 5 among the path configuration states of State 1 to State 5 in order to establish an optical communication path centered on the second terminal station B, which is a trunk station. When establishing an optical communication path centered on the first terminal station A, which is the other trunk station, the branching device 200 includes an optical switch driver 20 in which the first terminal station A is the second terminal station B and the second terminal station B is the first terminal station A.

[0043] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes. (Appendix 1) a first optical switch having a first input port and a second input port for inputting an optical signal and a first output port and a second output port for outputting an optical signal, the first optical switch being capable of switching a transmission path of the optical signal between the input port and the output port; a first input port of the first optical switch is connected to a first transmission line connected to a first terminal station, a second input port of the first optical switch is connected to a first transmission line connected to a third terminal station, a first output port of the first optical switch is connected to a transmission line connected to a first input port of the second optical switch, and a second output port of the first optical switch is connected to a first transmission line connected to a second terminal station; an optical switch drive circuit for connecting a first input port of the second optical switch to a transmission line connected to a first output port of the first optical switch, a second input port of the second optical switch to a second transmission line connected to the second terminal station, a first output port of the second optical switch to a second transmission line connected to the first terminal station, and a second output port of the second optical switch to a second transmission line connected to the third terminal station; Branching device. (Appendix 2) When establishing optical signal transmission paths between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, between a second transmission line connected to the first terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the third terminal station and a second transmission line connected to the second terminal station, the first optical switch connects the first input port and the second output port, and connects the second input port and the first output port; The second optical switch connects the first input port and the first output port, and connects the second input port and the second output port. 2. The branching device of claim 1. (Appendix 3) When establishing transmission paths of optical signals between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, and between a second transmission line connected to the first terminal station and a second transmission line connected to the second terminal station, the first optical switch connects a first input port to a second output port and connects the second input port to the first output port; The second optical switch connects the first input port and the second output port, and also connects the second input port and the first output port. 2. The branching device of claim 1. (Appendix 4) When establishing optical signal transmission paths between a first transmission line connected to the second terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the second terminal station and a second transmission line connected to the third terminal station, the first optical switch connects a first input port to a first output port and connects a second input port to a second output port; The second optical switch connects a first input port to a first output port, and connects a second input port to a second output port. 2. The branching device of claim 1. (Appendix 5) The optical switch drive circuit includes: a third and fourth optical switch having first and second input ports to which an optical signal is input and first and second output ports to which an optical signal is output, the third and fourth optical switches being capable of switching a transmission path of the optical signal between the input ports and the output ports; a first input port of a third optical switch is connected to a first output port of a fourth optical switch, a second input port of the third optical switch is connected to a first transmission line connected to the second terminal station, a first output port of the third optical switch is connected to a first transmission line connected to the first terminal station, and a second output port of the third optical switch is connected to a first transmission line connected to the third terminal station; A first input port of the fourth optical switch is connected to a second transmission line connected to the first terminal station, a second input port of the fourth optical switch is connected to a second transmission line connected to the third terminal station, a first output port of the fourth optical switch is connected to a transmission line connected to the first input port of the third optical switch, and a second output port of the fourth optical switch is connected to a second transmission line connected to the second terminal station. 2. The branching device of claim 1. (Appendix 6) When establishing optical signal transmission paths between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, between a second transmission line connected to the first terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the third terminal station and a second transmission line connected to the second terminal station, the third optical switch connects the first input port and the second output port, and connects the second input port and the first output port; The fourth optical switch connects the first input port and the first output port, and connects the second input port and the second output port. 6. The branching device according to claim 5. (Appendix 7) When establishing transmission paths of optical signals between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, and between a second transmission line connected to the first terminal station and a second transmission line connected to the second terminal station, the third optical switch connects the first input port and the second output port, and connects the second input port and the first output port; The fourth optical switch connects the first input port and the second output port, and also connects the second input port and the first output port. 6. The branching device according to claim 5. (Appendix 8) When establishing transmission paths of optical signals between a first transmission line connected to the second terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the second terminal station and a second transmission line connected to the third terminal station, the third optical switch connects a first input port to a first output port and connects a second input port to a second output port; The fourth optical switch connects the first input port and the first output port, and connects the second input port and the second output port. 6. The branching device according to claim 5. (Appendix 9) a first optical switch having a first input port and a second input port for inputting an optical signal and a first output port and a second output port for outputting an optical signal, the first optical switch being capable of switching a transmission path of the optical signal between the input port and the output port; a first input port of the first optical switch is connected to a first transmission line connected to a first terminal station, a second input port of the first optical switch is connected to a first transmission line connected to a third terminal station, a first output port of the first optical switch is connected to a transmission line connected to a first input port of the second optical switch, and a second output port of the first optical switch is connected to a first transmission line connected to a second terminal station; an optical switch drive circuit, a first input port of the second optical switch connected to a transmission line connected to a first output port of the first optical switch, a second input port of the second optical switch connected to a second transmission line connected to the second terminal station, a first output port of the second optical switch connected to a second transmission line connected to the first terminal station, and a second output port of the second optical switch connected to a second transmission line connected to the third terminal station; Controlling switching of the transmission paths in the first and second optical switches A method for controlling a branching device. (Appendix 10) When establishing optical signal transmission paths between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, between a second transmission line connected to the first terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the third terminal station and a second transmission line connected to the second terminal station, controlling the first optical switch so as to connect the first input port to the second output port and to connect the second input port to the first output port; The second optical switch is controlled so as to connect the first input port to the first output port and to connect the second input port to the second output port. A method for controlling a branching device according to claim 9. (Appendix 11) When establishing transmission paths of optical signals between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, and between a second transmission line connected to the first terminal station and a second transmission line connected to the second terminal station, controlling the first optical switch so as to connect a first input port to a second output port and to connect the second input port to the first output port; The second optical switch is controlled so as to connect the first input port and the second output port, and also to connect the second input port and the first output port. A method for controlling a branching device according to claim 9. (Appendix 12) When establishing transmission paths of optical signals between a first transmission line connected to the second terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the second terminal station and a second transmission line connected to the third terminal station, controlling the first optical switch so that the first optical switch connects a first input port to a first output port and connects a second input port to a second output port; The second optical switch is controlled so as to connect the first input port to the first output port and to connect the second input port to the second output port. A method for controlling a branching device according to claim 9. (Appendix 13) The optical switch drive circuit includes: a third and fourth optical switch having first and second input ports to which an optical signal is input and first and second output ports to which an optical signal is output, the third and fourth optical switches being capable of switching a transmission path of the optical signal between the input ports and the output ports; a first input port of a third optical switch is connected to a first output port of a fourth optical switch, a second input port of the third optical switch is connected to a first transmission line connected to the second terminal station, a first output port of the third optical switch is connected to a first transmission line connected to the first terminal station, and a second output port of the third optical switch is connected to a first transmission line connected to the third terminal station; a first input port of the fourth optical switch is connected to a second transmission line connected to the first terminal station, a second input port of the fourth optical switch is connected to a second transmission line connected to the third terminal station, a first output port of the fourth optical switch is connected to a transmission line connected to the first input port of the third optical switch, and a second output port of the fourth optical switch is connected to a second transmission line connected to the second terminal station; Controlling switching of the transmission paths in the third and fourth optical switches A method for controlling a branching device according to claim 9. (Appendix 14) When establishing optical signal transmission paths between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, between a second transmission line connected to the first terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the third terminal station and a second transmission line connected to the second terminal station, controlling the third optical switch so that the third optical switch connects the first input port and the second output port and connects the second input port and the first output port; The fourth optical switch is controlled so as to connect the first input port to the first output port and to connect the second input port to the second output port. A method for controlling a branching device according to claim 13. (Appendix 15) When establishing transmission paths of optical signals between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, and between a second transmission line connected to the first terminal station and a second transmission line connected to the second terminal station, controlling the third optical switch so as to connect the first input port to the second output port and to connect the second input port to the first output port; The fourth optical switch is controlled so as to connect the first input port to the second output port and to connect the second input port to the first output port. A method for controlling a branching device according to claim 13. (Appendix 16) When establishing transmission paths of optical signals between a first transmission line connected to the second terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the second terminal station and a second transmission line connected to the third terminal station, controlling the third optical switch so that the third optical switch connects the first input port to the first output port and connects the second input port to the second output port; The fourth optical switch is controlled so as to connect the first input port to the first output port and to connect the second input port to the second output port. A method for controlling a branching device according to claim 13. (Appendix 17) a first optical switch having a first input port and a second input port for inputting an optical signal and a first output port and a second output port for outputting an optical signal, the first optical switch being capable of switching a transmission path of the optical signal between the input port and the output port; a first input port of the first optical switch is connected to a first transmission line connected to a first terminal station, a second input port of the first optical switch is connected to a first transmission line connected to a third terminal station, a first output port of the first optical switch is connected to a transmission line connected to a first input port of the second optical switch, and a second output port of the first optical switch is connected to a first transmission line connected to a second terminal station; an optical switch drive circuit, a first input port of the second optical switch connected to a transmission line connected to a first output port of the first optical switch, a second input port of the second optical switch connected to a second transmission line connected to the second terminal station, a first output port of the second optical switch connected to a second transmission line connected to the first terminal station, and a second output port of the second optical switch connected to a second transmission line connected to the third terminal station; A process for controlling switching of the transmission paths in the first and second optical switches is performed by a computer. program. (Appendix 18) When establishing optical signal transmission paths between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, between a second transmission line connected to the first terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the third terminal station and a second transmission line connected to the second terminal station, controlling the first optical switch so as to connect the first input port to the second output port and to connect the second input port to the first output port; and further causing the computer to execute a process of controlling the second optical switch so that the second optical switch connects the first input port and the first output port and connects the second input port and the second output port. 18. The program according to claim 17. (Appendix 19) When establishing transmission paths of optical signals between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, and between a second transmission line connected to the first terminal station and a second transmission line connected to the second terminal station, controlling the first optical switch so that the first optical switch connects a first input port to a second output port and connects the second input port to the first output port; and further causing the computer to execute a process of controlling the second optical switch so that the second optical switch connects the first input port and the second output port and also connects the second input port and the first output port. 18. The program according to claim 17. (Appendix 20) When establishing optical signal transmission paths between a first transmission line connected to the second terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the second terminal station and a second transmission line connected to the third terminal station, controlling the first optical switch so that the first optical switch connects a first input port to a first output port and connects a second input port to a second output port; and further causing the computer to execute a process of controlling the second optical switch so that the second optical switch connects a first input port to a first output port and connects a second input port to a second output port. 18. The program according to claim 17. (Appendix 21) The optical switch drive circuit includes: a third and fourth optical switch having first and second input ports to which an optical signal is input and first and second output ports to which an optical signal is output, the third and fourth optical switches being capable of switching a transmission path of the optical signal between the input ports and the output ports; a first input port of a third optical switch is connected to a first output port of a fourth optical switch, a second input port of the third optical switch is connected to a first transmission line connected to the second terminal station, a first output port of the third optical switch is connected to a first transmission line connected to the first terminal station, and a second output port of the third optical switch is connected to a first transmission line connected to the third terminal station; a first input port of the fourth optical switch is connected to a second transmission line connected to the first terminal station, a second input port of the fourth optical switch is connected to a second transmission line connected to the third terminal station, a first output port of the fourth optical switch is connected to a transmission line connected to the first input port of the third optical switch, and a second output port of the fourth optical switch is connected to a second transmission line connected to the second terminal station; and further causing the computer to execute a process of controlling switching of the transmission paths in the third and fourth optical switches. 18. The program according to claim 17. (Appendix 22) When establishing optical signal transmission paths between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, between a second transmission line connected to the first terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the third terminal station and a second transmission line connected to the second terminal station, controlling the third optical switch so that the third optical switch connects the first input port and the second output port and connects the second input port and the first output port; and further causing the computer to execute a process of controlling the fourth optical switch so that the fourth optical switch connects the first input port and the first output port and connects the second input port and the second output port. 22. The program according to claim 21. (Appendix 23) When establishing transmission paths of optical signals between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, and between a second transmission line connected to the first terminal station and a second transmission line connected to the second terminal station, controlling the third optical switch so as to connect the first input port to the second output port and to connect the second input port to the first output port; and further causing the computer to execute a process of controlling the fourth optical switch so that the fourth optical switch connects the first input port and the second output port and connects the second input port and the first output port. 22. The program according to claim 21. (Appendix 24) When establishing optical signal transmission paths between a first transmission line connected to the second terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the second terminal station and a second transmission line connected to the third terminal station, controlling the third optical switch so that the third optical switch connects the first input port and the first output port and connects the second input port and the second output port; and further causing the computer to execute a process of controlling the fourth optical switch so that the fourth optical switch connects the first input port to the first output port and connects the second input port to the second output port. 22. The program according to claim 21. [Explanation of symbols]

[0044] 100, 200 Branching Device 10 Control section 20 Optical switch driver circuit 11, 21, 31, 41 First input port 12, 22, 32, 42 Second input port 13, 23, 33, 43 First output port 14, 24, 34, 44 Second output port 1000 Computers 1001 Processor 1002 Memory A 1st terminal station A1 First transmission line A2 Second transmission line B 2nd terminal station B1 First transmission line B2 Second transmission line C 3rd terminal station C1 First transmission line C2 Second transmission line SW1 First optical switch SW2 Second optical switch SW3 Third optical switch SW4 4th optical switch

Claims

1. a first optical switch having a first input port and a second input port for inputting an optical signal and a first output port and a second output port for outputting an optical signal, the first optical switch being capable of switching a transmission path of the optical signal between the input port and the output port; a first input port of the first optical switch is connected to a first transmission line connected to a first terminal station, a second input port of the first optical switch is connected to a first transmission line connected to a third terminal station, a first output port of the first optical switch is connected to a transmission line connected to the first input port of the second optical switch, and a second output port of the first optical switch is connected to a first transmission line connected to a second terminal station; an optical switch drive circuit for connecting a first input port of the second optical switch to a transmission line connected to a first output port of the first optical switch, a second input port of the second optical switch to a second transmission line connected to the second terminal station, a first output port of the second optical switch to a second transmission line connected to the first terminal station, and a second output port of the second optical switch to a second transmission line connected to the third terminal station; Branching device.

2. When establishing optical signal transmission paths between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, between a second transmission line connected to the first terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the third terminal station and a second transmission line connected to the second terminal station, the first optical switch connects the first input port and the second output port, and connects the second input port and the first output port; The second optical switch connects the first input port and the first output port, and connects the second input port and the second output port. The branching device according to claim 1 .

3. When establishing transmission paths of optical signals between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, and between a second transmission line connected to the first terminal station and a second transmission line connected to the second terminal station, the first optical switch connects a first input port to a second output port and connects the second input port to the first output port; The second optical switch connects the first input port and the second output port, and also connects the second input port and the first output port. The branching device according to claim 1 .

4. When establishing transmission paths of optical signals between a first transmission line connected to the second terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the second terminal station and a second transmission line connected to the third terminal station, the first optical switch connects a first input port to a first output port and connects a second input port to a second output port; The second optical switch connects a first input port to a first output port, and connects a second input port to a second output port. The branching device according to claim 1 .

5. The optical switch drive circuit includes: a third and fourth optical switch having first and second input ports to which an optical signal is input and first and second output ports to which an optical signal is output, the third and fourth optical switches being capable of switching a transmission path of the optical signal between the input port and the output port, a first input port of a third optical switch is connected to a first output port of a fourth optical switch, a second input port of the third optical switch is connected to a first transmission line connected to the second terminal station, a first output port of the third optical switch is connected to a first transmission line connected to the first terminal station, and a second output port of the third optical switch is connected to a first transmission line connected to the third terminal station; A first input port of the fourth optical switch is connected to a second transmission line connected to the first terminal station, a second input port of the fourth optical switch is connected to a second transmission line connected to the third terminal station, a first output port of the fourth optical switch is connected to a transmission line connected to the first input port of the third optical switch, and a second output port of the fourth optical switch is connected to a second transmission line connected to the second terminal station. The branching device according to claim 1 .

6. When establishing optical signal transmission paths between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, between a second transmission line connected to the first terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the third terminal station and a second transmission line connected to the second terminal station, the third optical switch connects the first input port and the second output port, and connects the second input port and the first output port; The fourth optical switch connects the first input port and the first output port, and connects the second input port and the second output port. The branching device according to claim 5.

7. When establishing transmission paths of optical signals between a first transmission line connected to the first terminal station and a first transmission line connected to the second terminal station, and between a second transmission line connected to the first terminal station and a second transmission line connected to the second terminal station, the third optical switch connects the first input port and the second output port, and connects the second input port and the first output port; The fourth optical switch connects the first input port and the second output port, and also connects the second input port and the first output port. The branching device according to claim 5.

8. When establishing transmission paths of optical signals between a first transmission line connected to the second terminal station and a first transmission line connected to the third terminal station, and between a second transmission line connected to the second terminal station and a second transmission line connected to the third terminal station, the third optical switch connects a first input port to a first output port and connects a second input port to a second output port; The fourth optical switch connects a first input port to a first output port, and connects a second input port to a second output port. The branching device according to claim 5.

9. a first optical switch having a first input port and a second input port for inputting an optical signal and a first output port and a second output port for outputting an optical signal, the first optical switch being capable of switching a transmission path of the optical signal between the input port and the output port; a first input port of the first optical switch is connected to a first transmission line connected to a first terminal station, a second input port of the first optical switch is connected to a first transmission line connected to a third terminal station, a first output port of the first optical switch is connected to a transmission line connected to the first input port of the second optical switch, and a second output port of the first optical switch is connected to a first transmission line connected to a second terminal station; an optical switch drive circuit, a first input port of the second optical switch connected to a transmission line connected to a first output port of the first optical switch, a second input port of the second optical switch connected to a second transmission line connected to the second terminal station, a first output port of the second optical switch connected to a second transmission line connected to the first terminal station, and a second output port of the second optical switch connected to a second transmission line connected to the third terminal station; Controlling switching of the transmission paths in the first and second optical switches A method for controlling a branching device.

10. The optical switch drive circuit includes: a third and fourth optical switch having first and second input ports to which an optical signal is input and first and second output ports to which an optical signal is output, the third and fourth optical switches being capable of switching a transmission path of the optical signal between the input port and the output port, a first input port of a third optical switch is connected to a first output port of a fourth optical switch, a second input port of the third optical switch is connected to a first transmission line connected to the second terminal station, a first output port of the third optical switch is connected to a first transmission line connected to the first terminal station, and a second output port of the third optical switch is connected to a first transmission line connected to the third terminal station; a first input port of the fourth optical switch is connected to a second transmission line connected to the first terminal station, a second input port of the fourth optical switch is connected to a second transmission line connected to the third terminal station, a first output port of the fourth optical switch is connected to a transmission line connected to the first input port of the third optical switch, and a second output port of the fourth optical switch is connected to a second transmission line connected to the second terminal station; Controlling switching of the transmission paths in the third and fourth optical switches The method for controlling a branching device according to claim 9.

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