Optical communication controllers and optical communication systems

Abstract

To improve the stability and availability of the APN network system and minimize service interruptions in the event of a failure. [Solution] The optical communication controller (APN-C) 100 manages and controls each APN-T and APN-G device under the APN network. The APN-C 100 acquires control signal B, which includes the status of each APN-T and APN-G device and the status of the transmission path, via a transmission path different from the transmission path of the main signal A. If the APN-C 100 cannot acquire control signal B, it includes a control unit that searches for an alternative communication path, acquires control signal B using the alternative path, and continues the management and control of the APN network.

Description

Technical Field

[0001] The present invention relates to an optical communication controller and an optical communication system.

Background Art

[0002] The concept of IWON (Innovative Optical and Wireless Network) includes an All Photonics Network (APN) in which all node transceivers and the network perform optical transmission. In addition, an OSC (Optical Supervisor Channel) signal is used for status monitoring of main signals transmitted between node transceivers.

[0003] As technologies related to status monitoring of optical transmission networks, for example, there is a technology that has a working optical line and a protection optical line, and when a failure of the working optical line is detected using a periodically transmitted test optical signal, the optical signal is relayed in a detour between the upstream protection optical line and the downstream working optical line to maintain transmission and reception of optical signals. There is also a technology in which an amplifier node provided between switching nodes detects a Loss of Signal (LOS) state via the OSC, and performs a switching operation to bypass a failed switching node. There is also a technology in which when an abnormality is detected at a primary network node, an optical switch switches the connection from the primary network node to a standby network node to perform communication backup using the standby network node. There is also a technology that suppresses the influence of operations against the intention of a communication carrier by accepting authenticated user operations for changeable settings of transceivers (see, for example, Patent Documents 1 to 4 below).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] Traditionally, because the OSC signal was superimposed on the main signal and the OSC signal was monitored, it was not possible to correctly grasp the actual fault condition causing an OSC failure. For example, it was not possible to distinguish between a fault in a node's equipment, a main signal failure, or a failure of the OSC signal alone. In this case, the fault condition could only be determined by having a worker check the actual situation at the site where the failure occurred each time an OSC failure occurred, making the work cumbersome. As a result, conventionally, the optical communication controller (APN-C) could not correctly manage the status of each device and transmission line under the APN network, nor could it remotely control appropriate countermeasures for failures.

[0006] In one aspect, the present invention aims to improve the stability and availability of optical transmission network systems and minimize service interruptions in the event of failures. [Means for solving the problem]

[0007] According to one aspect of the present invention, the optical communication controller is an optical communication controller that manages and controls a plurality of devices under an optical transmission network, and is required to include a control unit that acquires control signals including the status of each device and the status of the transmission line via a transmission path different from the transmission path of the main signal, searches for a communicationable alternative path if the control signals cannot be acquired, acquires the control signals using the alternative path, and continues the management and control of the optical transmission network. [Effects of the Invention]

[0008] According to one aspect of the present invention, the stability and availability of optical transmission network systems are improved, and service interruptions in the event of a failure are minimized. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows an example of a network configuration of an optical communication system including an optical communication controller according to an embodiment. [Figure 2] Figure 2 is an explanatory diagram illustrating an example of connection work for the transmission path of the main signal using background technology. (Part 1) [Figure 3] Figure 3 is an explanatory diagram illustrating an example of the connection work for the transmission path of the main signal using background technology. (Part 2) [Figure 4] Figure 4 shows an example of transmission of the main signal and control signal according to the embodiment. [Figure 5] Figure 5 is an explanatory diagram illustrating an example of information managed by APN-C. [Figure 6] Figure 6 is a diagram showing an example of information for monitoring and control. [Figure 7] Figure 7 shows the E2E connection status of APN-T. [Figure 8] Figure 8 shows an example of the hardware configuration of the control unit of APN-C. [Figure 9] Figure 9 shows an example of the process when APN-T is installed. [Figure 10] Figure 10 shows an example of processing during main signal communication in an APN network. [Figure 11] Figure 11 shows the state when a control signal failure occurs. [Figure 12] Figure 12 shows alternative routes corresponding to the location of a control signal failure. (Part 1) [Figure 13] Figure 13 shows alternative routes corresponding to the location of a control signal failure. (Part 2) [Figure 14] Figure 14 shows an example of control signal path switching processing when a control signal failure occurs. (Part 1) [Figure 15] Figure 15 shows an example of control signal path switching processing when a control signal failure occurs. (Part 2) [Figure 16] Figure 16 is an explanatory diagram illustrating an example of data compression for a control signal superimposed on the main signal. [Figure 17] Figure 17 is a flowchart illustrating an exemplary processing procedure of APN-C. [Figure 18] Figure 18 is a flowchart illustrating another exemplary processing procedure of APN-C. [Figure 19] Figure 19 is a diagram illustrating another exemplary configuration of a transmission line according to the embodiment. [Figure 20] Figure 20 is a diagram illustrating Exemplary Configuration 1 of APN-T. [Figure 21] Figure 21 is a diagram illustrating an exemplary path switching processing procedure for control signals corresponding to Exemplary Configuration 1 of APN-T. [Figure 22] Figure 22 is a diagram illustrating Exemplary Configuration 2 of APN-T. [Figure 23] Figure 23 is a diagram illustrating an exemplary path switching processing procedure for control signals corresponding to Exemplary Configuration 2 of APN-T. [Figure 24] Figure 24 is a diagram illustrating Exemplary Configuration 3 of APN-T. [Figure 25] Figure 25 is a diagram illustrating a failure scenario in Exemplary Configuration 3 of APN-T. [Figure 26] Figure 26 is a diagram illustrating an exemplary path switching processing procedure for control signals corresponding to Exemplary Configuration 3 of APN-T. [Figure 27] Figure 27 is a diagram illustrating Exemplary Connection Configuration 1 of a plurality of APN-Ts and an APN-G. [Figure 28] Figure 28 is a diagram illustrating an exemplary path switching processing procedure at the time of a failure in Exemplary Connection Configuration 1 of a plurality of APN-Ts and an APN-G. [Figure 29] Figure 29 is a diagram illustrating Exemplary Connection Configuration 2 of a plurality of APN-Ts and an APN-G. [Figure 30] Figure 30 is a diagram illustrating an exemplary path switching processing procedure at the time of a failure in Exemplary Connection Configuration 2 of a plurality of APN-Ts and an APN-G. [Figure 31] Figure 31 illustrates an exemplary configuration of another APN network and an exemplary path switching processing procedure at the time of a failure. [Mode for Carrying Out the Invention]

[0010] Embodiments of the disclosed optical communication controller and optical communication system will be described in detail below with reference to the drawings. The optical communication system of the embodiment manages and controls each device on an optical transmission network. The APN network described in the embodiment is an example of an optical transmission network. Each device in the APN network includes an optical transceiver (APN-T), a monitoring gateway (APN-G), and an optical communication controller (APN-C).

[0011] The APN-C in this embodiment manages and controls each device under the APN network. The APN-C acquires control signals, including the status of each device and the status of the transmission path, via a transmission path different from the transmission path of the main signal. If the APN-C is unable to acquire control signals due to a failure in any of the devices or the transmission path, it acquires control signals via other devices by searching for an alternative communication path and continues to manage and control the APN network.

[0012] Figure 1 is a diagram showing an example of the network configuration of an optical communication system including an optical communication controller according to the embodiment. First, the overall configuration of the embodiment will be explained using Figure 1. APN-G is provided as multiple nodes on the optical network (APN network) and relays and transmits the main signal. The APN network shown in Figure 1 is an example of a ring network in which multiple APN-G are connected in a ring. APN-T is a node connected to the APN-G and transmits (sends and receives) the main optical signal.

[0013] APN-T is positioned as a node at an End-to-End (E2E) location on the APN network, that is, at a pair of terminal stations that transmit the main signal optically. For example, one APN-T (1) transmits the main signal A to the other APN-T (2) via a transmission path (optical fiber) through multiple APN-Gs.

[0014] The optical communication controller (APN-C) 100 manages and remotely controls the status of devices and transmission paths across the entire optical network of the APN network, including APN-T and APN-G. Details of the information (data) managed by the APN-C will be described later. The APN-C monitors the transmission status of the main signal A using control signal B, identifies fault locations on the transmission path of the main signal A, and performs bypass control of the transmission path of the main signal A to avoid fault locations. The APN-C uses control signal B (uplink) to acquire the status of each device and transmission path with each device in the APN network, and uses control signal B (downlink) to perform control on each device that has acquired this status. In this embodiment, the explanation is basically based on the assumption that the uplink and downlink transmission paths of the control signal B are the same, but the uplink and downlink transmission paths of the control signal B may be different.

[0015] In this embodiment, the transmission path for the main signal A and the transmission path for the control signal B are separate paths. In the example shown in Figure 1, the transmission path for the main signal A between APN-T(1) and APN-T(2) is APN-T(1)~APN-G(1)~APN-G(2)~APN-G(3)~APN-G(4)~APN-T(2).

[0016] In contrast, the transmission path for control signal B from APN-T(1) acquired by APN-C is APN-T(1)~APN-G(1)~APN-C. Also, the transmission path for control signal B from APN-T(2) acquired by APN-C is APN-T(2)~APN-G(4)~APN-C.

[0017] In addition to this, APN-C can also obtain control signals B from APN-T(1) and APN-T(2) via other nodes located on the transmission path of main signal A, such as APN-G(2) or APN-G(3).

[0018] Furthermore, in order to set the transmission path of main signal A as shown in Figure 1, APN-C outputs a path selection signal using control signal B to APN-G(2) and APN-G(3) which are placed along the transmission path of main signal A.

[0019] The main signal A and the control signal B can each use wavelengths that are commonly used. For example, the main signal A may have a predetermined bandwidth such as the C-band or L-band, and the control signal B may use an OSC (1511 nm) that is different from the wavelength bandwidth of the main signal A.

[0020] As described above, in this embodiment, the transmission path for the main signal A and the transmission path for the control signal B are different. Therefore, even if a fault (location X1) such as a break occurs on the transmission path for the main signal A, the APN-C can acquire the control signal B via a transmission path different from that of the main signal A. Based on the acquired control signal B, the APN-C continues monitoring each device via a transmission path that bypasses the location of the fault in the control signal B.

[0021] Furthermore, as will be explained in more detail later, APN-C centrally controls all nodes (APN-G, APN-T) in the entire APN network, and control signal B can also be obtained through bypassing or other means.

[0022] Furthermore, according to this embodiment, even if a failure occurs in the transmission path of control signal B, APN-C can perform various controls to prevent interruption of the transmission service of main signal A. For example, when control signal B becomes unavailable at location X2 in Figure 1, the transmission state of main signal A itself on the transmission path is not affected, so APN-C does not stop communication of main signal A (it maintains the transmission state as is without performing bypass control of main signal A). In this case, when control signal B is unavailable at location X2, APN-T(1) can transmit control signal B to APN-C via another APN-T, for example, the opposing APN-T(2), by superimposing control signal B on main signal A. Examples of various failures and corresponding control examples will be described later.

[0023] According to this embodiment, it is possible to eliminate the need for on-site verification work by a worker U (APN-T, etc.) during route setting or when a failure occurs, and remote control can be performed via APN-C.

[0024] (Explanation of technical background) Here, I will explain the technical background and its challenges.

[0025] Figures 2 and 3 are explanatory diagrams illustrating an example of connection work for the transmission path of the main signal according to the background technology. The APN network defined in IWON shown in Figure 2 has an interchange (APN-I) installed. The APN-I does not control the APN-T, but only performs monitoring and control based on OSC on the same transmission path as the main signal A. In Figure 2, when setting up the transmission path of the main signal A in the same way as in Figure 1, it was necessary to place a worker U at each of the pair of APN-T(1) and APN-T(2), and the workers U would have to manually communicate with each other to perform the setup and connection work, which was time-consuming.

[0026] Figure 3 shows the E2E connection status of the pair of APN-Ts shown in Figure 2. APN-T(1) and APN-T(2) are configured such that multiple parent modules 302 (only one module is shown in Figure 3) can be inserted into and removed from slots inside the host (shelf enclosure) 301, for example.

[0027] The CPU 311 of the host 301 controls each parent module 302. Each parent module 302 includes a CPU 312, a DSP (Digital Signal Processor) 313, a Layer 2 switch (L2SW) 314, and an OSC unit 315. The CPU 312 controls the parent modules 302. In the data transmission side processing of the bidirectional transmission of APN-T(1), the DSP 313 transmits the main signal A, which is an optical signal obtained by converting the electrical signal of the transmitted data, to the transmission path. An optical DAC can also be used for the DSP 313. The L2SW 314 controls the packet transmission of the main signal A and transmits the OSC by wavelength multiplexing the main signal A. In the data reception side processing of APN-T(2), the DSP 313, L2SW 314, and OSC unit 315 each perform reception processing on the received main signal A and perform monitoring control based on the OSC.

[0028] In the background technology shown in Figure 3, it is necessary to place worker U on each of the APN-T(1) and APN-T(2) hosts 301 to perform E2E connection work. During this process, worker U had to confirm the transmission path information obtained in advance and the transmission path status at the time of connection. Furthermore, whenever a connection failure occurred due to an OSC failure or other fault, worker U had to perform on-site verification work.

[0029] In contrast, in this embodiment, as shown in Figure 1, in the IWON APN network, APN-C acquires control signal B from APN-T, which transmits main signal A, via a transmission path different from main signal A, and performs route setting and fault control. In this embodiment, the verification work by workers U at the site (APN-T, etc.) during transmission path connection and fault occurrence, which occurs in the background technology, can be omitted, and APN-C performs remote control of each node (APN-T, APN-G, etc.) in the APN network.

[0030] (Example of transmission of main signal and control signal in the embodiment) Figure 4 shows an example of transmission of main signals and control signals according to the embodiment. Similar to Figure 3, the APN-T(1) host 401 includes a CPU 411. The APN-T(1) parent module 402 includes each component (CPU 412, DSP 413, L2SW 414, OSC unit 415) and is removable from the host 401. In addition, a multiplexer / demultiplexer 416 is provided on the downstream / upstream transmission path of the main signals transmitted and received by the DSP 413.

[0031] The "parent" of the APN-T(1) parent module 402 is a module that has an OSC unit 415 capable of communicating OSC signals internally. As will be described later, the "child" of the APN-T(1) child module is a module that does not have an OSC unit 415 capable of communicating OSC signals internally.

[0032] In the transmission example shown in Figure 4, the multiplexer 416a transmits an optical signal (A+B) obtained by wavelength multiplexing the main signal output by the DSP 413 and the control signal B (OSC) output by the OSC unit 415 to the downstream transmission path. The multiplexer 416b wavelength-separates the optical signal (A+B) received in the upstream transmission path, outputs the main signal A to the DSP 413, and outputs the control signal B to the OSC unit 415.

[0033] APN-G also has a multiplexer / demultiplexer 420 on the transmission path of the main signal A. A multiplexer 420a, located on the upstream transmission path, transmits the control signal B (OSC), which has been wavelength-separated from the main signal A, to APN-C. A multiplexer 420b, located on the downstream transmission path, wavelength-multiplexes the control signal B (OSC) output from APN-C with the main signal A and transmits it to APN-T(1)401.

[0034] This allows APN-T(1) to send and receive control signal B (OSC) with APN-C via APN-G. Figure 4 shows an example of control signal B transmission, and the control signal B between APN-G and APN-C may be transmitted as an electrical signal, not just an optical signal. Furthermore, the OSC unit 415 of APN-T(1) may transmit control signal B between APN-C and other APN-C devices as an electrical signal or an optical signal.

[0035] (Examples of information managed by APN-C) Figure 5 is an explanatory diagram illustrating an example of information managed by APN-C. Using control signal B, APN-C acquires individual identification information 501, installation information 502, and transmission path (fiber) information 503 for all devices connected to the APN network, records them in the recording unit, and manages them for the control of each device. In the example in Figure 5, the devices controlled by APN-C correspond to APN-T and APN-G.

[0036] Individual identification information 501 includes information such as the equipment type and S / N (signal-to-noise ratio). Installation information 502 includes information such as the equipment installation site (location, etc.), connection device, and installation port. Transmission path (fiber) information 503 includes information such as the LOSS (loss), transmission capacity (number of fibers), and noise status of the optical fibers connecting each site.

[0037] (Example of information used for monitoring and control of APN-T) Figure 6 is a diagram showing an example of monitoring and control information. APN-C uses monitoring and control information 600 which includes individual identification information of APN-T, monitoring information of APN-T, control information of APN-T, and monitoring and control information of the APN network. Monitoring and control information 600 includes the information managed by APN-C as shown in Figure 5 and information during APN network operation.

[0038] The individual identification information for APN-T includes the device model, serial number (S / N), and installation location. The monitoring information for APN-T includes monitoring alarms (Warning Alarms) and various other information (such as device startup status, temperature, optical transmission / reception power, BER, SOP, PMD, and PDL). BER stands for Bit Error Rate, SOP for State of Polarization, MD for Polarization Mode Dispersion, and PDL for Polarization Dependent Loss.

[0039] APN-T control information includes optical transmission wavelength, optical output power, and optical modulation mode (QPSK, 16QAM, etc., 100G / 200G / 400G, etc.). APN network monitoring and control information includes path connection relationship information between APN-Ts in E2E via APN-G.

[0040] (Example of E2E connection using APN-T) Figure 7 shows the E2E connection status of APN-T. Although the main signal A and control signal B can be transmitted using the example described in Figure 4, for convenience, the main signal A and control signal B are shown separately in the explanations following Figure 7. E2E connected APN-T(1) and APN-T(2) transmit the main signal A via a transmission path through APN-G. Control signal B is transmitted to APN-C via APN-G. APN-C remotely controls APN-T(1) and APN-T(2) by acquiring control signal B from APN-T(1) and APN-T(2) via APN-G.

[0041] (Example hardware configuration for the APN-C control unit) Figure 8 shows an example of the hardware configuration of the control unit of APN-C. Control of the APN network in APN-C can be configured, for example, by the hardware shown in the control unit 800 in Figure 8.

[0042] The control unit 800 includes a processor 801 such as a CPU (Central Processing Unit), a memory 802, a network interface 803, a recording medium interface 804, and a recording medium 805. Each component is connected by a bus 810.

[0043] Here, the processor 801 is responsible for controlling the entire control unit 800. The processor 801 may have multiple cores. The memory 802 includes, for example, ROM (Read Only Memory), RAM (Random Access Memory), and flash ROM. Specifically, for example, the flash ROM stores the control program, the ROM stores the application program, and the RAM is used as the work area for the processor 801. The program stored in the memory 802 is loaded into the processor 801, causing the processor 801 to execute the coded process.

[0044] The network IF803 controls the interface between the network (APN network) and the inside of the device, and controls the input and output of information.

[0045] The recording medium IF804 controls the reading and writing of data to the recording medium 805 according to the control of the processor 801. The recording medium 805 stores the data written under the control of the recording medium IF804.

[0046] In addition to the components described above, the control unit 800 may also be configured to allow connection of, for example, an input device, a display, etc., via an interface (IF).

[0047] The processor 801 shown in Figure 8, through program execution, for example, acquires information from each device in the APN network and controls each device. For example, the control unit 800 acquires the information 501 to 503 and 600 shown in Figures 5 and 6 from each device connected to the network (APN network) via the transmission path of control signal B. Then, based on the monitoring and control results, the control unit 800 performs control on each device via the transmission path of control signal B.

[0048] Other devices (APN-T, APN-G) installed on the APN network also have control units with a configuration similar to the control unit 800 shown in Figure 8.

[0049] (Example of processing when installing APN-T) Figure 9 shows an example of the process during APN-T installation. Figure 9(a) is a flowchart showing the process during APN-T installation, and Figure 9(b) is a sequence diagram of the information sent and received between each device in the APN network corresponding to each process in Figure 9(a). Each process shown in Figure 9 is executed by the control unit of the corresponding device (CPU 801 in Figure 8).

[0050] As shown in Figure 9(a), the APN-T is installed (step S901). For example, suppose a new APN-T(1) parent (module) is installed on the APN-T(1) host described above. Next, the APN-T(1) starts up the device (step S902). Next, the APN-G performs device authentication of the APN-T (step S903). Then, the control signal B is communicated between the APN-T and the APN-C (step S904), and the above installation process is completed.

[0051] The processing of each device will be explained using Figure 9(b). First, after installation, the APN-T(1) host sends a status to the APN-T(1) parent via polling (step S921), and the APN-T(1) parent starts up according to the startup sequence and notifies the APN-T(1) host of the startup status (step S922).

[0052] Next, the APN-T(1) host performs device authentication of the APN-T(1) parent (step S931), and the APN-T(1) parent transmits main signal A to the APN-G (step S932). Next, the APN-G requests information / authentication from the APN-T(1) parent (step S933), and the APN-T(1) parent sends an information / authentication response to the APN-G using control signal B (step S934). The APN-C receives this information / authentication response.

[0053] After this, APN-C requests APN-T(1) to open the OSC control path (step S941). The APN-T(1) host sends a monitoring and control response to APN-C via OSC (step S942). From this point onward, APN-C performs monitoring and control over APN-T(1) (step S943).

[0054] (Example of processing when the main signal is transmitted) Figure 10 shows an example of processing during main signal communication in an APN network. After the processing shown in Figure 9, each device on the APN network performs the processing shown in Figure 10. Figure 10(a) is a flowchart showing the processing content during main signal A communication between APN-T, and Figure 10(b) is a sequence diagram of the information sent and received between each device on the APN network corresponding to each processing content in Figure 10(a).

[0055] As shown in Figure 10(a), when the main signal A is transmitted, APN-C first performs the process of enabling the transmission of main signal A between APN-T(1) and APN-T(2) (step S1001). Next, APN-C sends optical settings to APN-T (step S1002). Next, APN-T performs the optical settings (step S1003). Then, APN-T transmits main signal A, and APN-C starts monitoring the line (step S1004).

[0056] Using Figure 10(b) to explain the processing of each device, first, the APN-T(1) host authenticates the APN-T(1) parent (step S1011). If authentication is successful, the APN-T(1) parent sends a path setting request to APN-C using control signal B (step S1012). The path setting request includes information such as the bandwidth, delay, jitter, and redundancy of the pair with APN-T(2).

[0057] Next, APN-C uses control signal B to set the wavelength / transmission mode for APN-T(1) (step S1021). APN-C also uses control signal B to set the wavelength path for APN-G(1) and APN-G(2) (step S1022).

[0058] Next, APN-T(1) and APN-T(2), whose wavelength paths have been set, transmit and receive the main signal A between them (step S1031). At this time, APN-T(1) and APN-T(2) each notify APN-C of the reception status of the main signal A using control signal B (step S1032). Based on the reception status notification, APN-C sets the optimal control settings for APN-T(1) and APN-T(2) (step S1033).

[0059] Next, APN-T(1) transmits data to APN-T(2) using control signal B with settings modified by optimal control (step S1041), establishing transmission and reception communication between APN-T(1) and APN-T(2) (step S1042). APN-T(2) notifies APN-T(1) of the transmission quality (QoT) using control signal B (step S1043). APN-T(1) and APN-T(2) each perform monitoring information (ALM / PM) notification processing using control signal B (step S1044), and APN-T(1) and APN-T(2) notify APN-C of the reception status of the monitoring information using control signal B (step S1045), and APN-C performs ALM / PM monitoring.

[0060] (Examples of processing depending on the location of the failure) Next, we will explain an example of how to handle a failure in control signal B on the APN network.

[0061] Figure 11 shows the state when a control signal failure occurs. In the example in Figure 11, a failure in control signal B occurs at point X2 between APN-T(1) and APN-G(1). For example, suppose a failure occurs in the OSC unit 415 and the transmission of control signal B (OSC) stops. As a result, APN-C is unable to communicate control signal B with APN-T(1). However, since there is no problem with the transmission of main signal A between APN-T(1) and APN-T(2) as shown in Figure 11, APN-C does not stop the communication of main signal A.

[0062] Figures 12 and 13 show alternative routes corresponding to the location of a control signal failure. Figure 12 shows an alternative route corresponding to the failure of control signal B at location X2 shown in Figure 11. In the example in Figure 12, APN-T(1) connects to APN-C via the opposite APN-T(2) by loading control signal B (e.g., OSC) onto the overhead of the transmission path of main signal A, without going through location X2.

[0063] In this case, the CPU 411 of the APN-T(1) host 401 outputs the control signal to the CPU 412 of the APN-T(1) parent 402, and the DSP 413 loads the control signal onto the overhead of the downstream main signal A and transmits it to the opposite APN-T(2). The APN-T(2) extracts the control signal (OSC) from the received main signal A using wavelength separation and transmits the control signal to the APN-C via the OSC unit 415.

[0064] As described above, by rerouting control signal B, even if control signal B fails at location X2, control signal B can be transmitted to APN-C via APN-T(2) using the transmission path of main signal A. APN-C can then control APN-T(1) using the upstream transmission path of main signal A on the rerouted path.

[0065] Figure 13 shows the case where, in addition to location X2, a communication failure occurs at location X3 between the CPU 411 of the APN-T(1) host 401 and the CPU 412 of the APN-T(1) parent 402 within APN-T(1).

[0066] In communication between APN-T(1) host 401 and APN-T(1) parent 402, if either the communication via L2SW414 or the direct access between CPU411 and CPU412 fails, the control signal B can be circumvented. If one of the points X3 between CPU411 and CPU412 shown in Figure 13 fails, CPU411 can output the control signal B to DSP413 via L2SW414, and transmit it to APN-C via the opposing APN-T(2).

[0067] Figures 14 and 15 show examples of control signal path switching processes in the event of a control signal failure. First, Figure 14 is an explanatory diagram of the processing performed by each device on the APN network when a failure occurs in control signal B (outage at location X2) as shown in Figure 12, during operation after the main signal A is successfully transmitted. Figure 14(a) is a flowchart showing the processing content when the control signal is out of service at location X2, and Figure 14(b) is a sequence diagram of the information sent and received between each device on the APN network corresponding to each processing content in Figure 14(a).

[0068] As shown in Figure 14(a), during operation, APN-C enters a periodic monitoring state for APN-T using control signal B (step S1401). Now, suppose a communication interruption occurs between APN-C and APN-T (step S1402). In this case, APN-C switches the transmission path of control signal B to monitoring control from main signal A (or another system) (step S1403).

[0069] Then, APN-C identifies the fault location (step S1404). After this, APN-C and APN-T return to the periodic monitoring state of control signal B (step S1405).

[0070] The processing of each device will be explained using Figure 14(b). During operation, APN-C periodically polls the APN-T(1) parent using control signal B, and the APN-T(1) parent responds to APN-C (step S1411). Now, suppose that control signal B between the APN-T(1) parent and APN-C becomes unavailable (disconnection at location X2 in Figure 12). In this case, even if APN-C periodically polls the APN-T(1) parent, the APN-T(1) parent will not respond to APN-C (step S1421).

[0071] In this case, APN-C asks APN-T(2), the counterpart to the transmission of main signal A, to check the status of APN-T(1) (a status inquiry) (step S1431). In the state shown in Figure 12, main signal A is communicable (live) between APN-T(1) and APN-T(2). Then, APN-T(2) replies to APN-C that APN-T(1) is communicable (live) (step S1432).

[0072] As a result, APN-C switches to controlling and monitoring APN-T(1) using control signal B via APN-T(2) (step S1433). At this time, APN-T(2) transmits a control monitoring signal (control signal B) for APN-T(1) to APN-T(1) via main signal A (or another system) (step S1434). In the example in Figure 12, APN-T(2) superimposes the control monitoring signal (control signal B) onto main signal A and transmits it to APN-T(1). At this time, APN-T(2) compresses the control monitoring signal (control signal B) as needed and superimposes it onto main signal A (step S1435).

[0073] Upon receiving the control monitoring signal, the APN-T(1) host collects information to identify the fault location (step S1441). For example, the APN-T(2) host obtains information about the faulty location X2 by collecting information from an intermediate device (APN-G(1) in Figure 12) on the transmission path of the control signal B. The APN-T(1) host then superimposes the estimated fault location information (control signal B) for the faulty location X2 onto the main signal A and transmits it to the opposing APN-T(2) (step S1442). At this time, the APN-T(1) compresses the control signal B as needed before superimposing it onto the main signal A (step S1443).

[0074] APN-T(2) transmits fault location estimation information to APN-C using control signal B (step S1444). This allows APN-C to identify the location X2 where control signal B is not working. From there, APN-C transmits and receives the control monitoring signal (control signal B) to and from APN-T(1) via a transmission path that avoids the location X2 (transmission path APN-C~APN-T(2)~APN-T(1)) (step S1451). APN-T(1) and APN-T(2) compress the control monitoring signal (control signal B) as needed and superimpose it on the main signal A (step S1452).

[0075] Next, Figure 15 is an explanatory diagram of the processing performed by each device on the APN network when a failure occurs in control signal B (outage at locations X2 and X3) as shown in Figure 13, during operation after the main signal A is transmitted. Figure 15(a) is a flowchart showing the processing content when the control signal is out of service at locations X2 and X3, and Figure 15(b) is a sequence diagram of the information sent and received between each device on the APN network corresponding to each processing content in Figure 15(a).

[0076] The overall process shown in Figure 15(a) is the same as in Figure 14(a). In the sequence diagram shown in Figure 15(b), the same processes as in Figure 14(b) are denoted by the same symbols. The difference in Figure 15(b) is the addition of a point X3 where the control signal B is not transmitted. Therefore, in step S1434, the control monitoring signal (control signal B) from APN-T(2) to APN-T(1) via the main signal A is only transmitted up to the parent APN-T(1).

[0077] In this case, the APN-T(1) parent performs a status check (liveness check) via an alternative route for the control monitoring signal (control signal B) (step S1435). As seen in Figure 13, direct access between CPU411 and CPU412 is unavailable, and the APN-T(1) parent collects information to identify the fault location (step S1441). In the example in Figure 15(b), information is collected from the APN-G(1) and APN-T(1) hosts.

[0078] Based on the information gathered, the APN-T(1) parent checks whether the path via L2SW414 (CPU411~L2SW412~DSP413) is communicable (live). Based on this, the APN-T(1) parent superimposes the fault location estimation information (control signal B) for fault location X3 onto the main signal A and transmits it to the opposing APN-T(2) (step S1442). Although not shown in Figure 15(b), the APN-T(1) parent may, if necessary, compress the control signal B before superimposing it onto the main signal A.

[0079] As a result, APN-C identifies location X3 in addition to location X2 where the control signal B is not transmitted. From then on, APN-C transmits and receives the control monitoring signal (control signal B) to and from APN-T(1) via a transmission path that avoids the locations X2 and X3 (the transmission path APN-C~APN-T(2)~APN-T(1) (step S1451).

[0080] Figure 16 is an explanatory diagram illustrating an example of data compression for a control signal superimposed on a main signal. In Figure 16, the point X2 where control signal B is not transmitted, as shown in Figure 12, is used as an example. If control signal B is uncompressed, it requires a transmission capacity equivalent to up to GbE. Therefore, when transmitting control signal B superimposed on the OSC of main signal A, it is desirable to compress the data to prevent delay in control signal B and bandwidth compression of the main signal.

[0081] On the other hand, compressing the data of control signal B increases the power consumption of the APN-T(1) host's CPU 411. Therefore, if the transmission capacity of control signal B is small (for example, below the threshold), the transmitting APN-T(1) performs data compression of control signal B on the APN-T(1) parent's CPU 412. On the other hand, if the transmission capacity of control signal B is large (above the threshold), the APN-T(1) host's CPU 411 performs data compression of control signal B. Furthermore, if control signal B is large, it is transmitted to APN-C via Ethernet (registered trademark) through L2SW414. On the other hand, if control signal B is small, CPUs 411 and 412 communicate with each other using I2C (Inter-Integrated Circuit) / SPI (Serial Peripheral Interface), etc.

[0082] In response to the data compression of control signal B performed by each component of the transmitting APN-T(1), each component of the receiving APN-T(2) decompresses the data and transmits control signal B to APN-C.

[0083] Under normal circumstances, when there are no problems with the transmission of control signal B, transmitting control signal B to APN-C via a different transmission path (e.g., Ethernet) from the main signal A without data compression can suppress increased power consumption at APN-T(1) and the impact of bandwidth congestion on the main signal A. Furthermore, only when a problem occurs in the transmission of control signal B, data compression of control signal B and superimposition on the main signal A can be used to transmit control signal B to APN-C while minimizing increased power consumption at APN-T(1) and the impact of bandwidth congestion on the main signal A. In addition, by switching the CPU performing data compression according to the transmission capacity of control signal B, the increase in CPU power consumption due to data compression can be minimized.

[0084] (APN-C processing example) Figure 17 is a flowchart showing an example of APN-C processing. The processing shown in Figure 17 is performed by the control unit 800 (CPU 801) of APN-C. Using Figure 17, we will explain the process of identifying the fault location when the control signal B is not transmitted, and an example of the transmission process of control signal B that avoids the fault location.

[0085] First, APN-C periodically polls each device in the APN network to monitor its status (step S1701). First, APN-C determines whether or not there is a response to the polling from APN-T(1) (step S1702). If there is a response from APN-T(1) (step S1702: yes), APN-C returns to the process in step S1701 and polls the other devices.

[0086] On the other hand, if the assessment shows no response from APN-T(1) (step S1702: none), APN-C contacts the APN-T(2) host. APN-C then determines whether APN-T(2) is able to communicate with the APN-T(1) parent / APN-T(1) host (step S1703).

[0087] Then, APN-C determines whether the response from APN-T(2) indicates main signal communication with APN-T(1) (step S1704). If APN-T(2) has communicated the main signal with APN-T(1) (step S1704: yes), APN-C proceeds to step S1705. On the other hand, if APN-T(2) has not communicated the main signal with APN-T(1) (step S1704: no), APN-C proceeds to step S1706.

[0088] In step S1705, APN-C contacts the APN-T(1) parent and APN-T(1) host via the APN-T(2) host and APN-T(2) parent (step S1705), and then proceeds to step S1707. In step S1706, APN-C determines that the APN-T(1) parent or host has failed (step S1706), and terminates the above process.

[0089] In step S1707, APN-C determines whether or not there is a response to the control signal B(OSC) from APN-T(1). If there is a response to the control signal B(OSC) from APN-T(1) (step S1707: yes), APN-C proceeds to the process in step S1709. On the other hand, if there is no response to the control signal B(OSC) from APN-T(1) (step S1707: no), APN-C determines that there is a fault in the transmission of the control signal B(OSC) from APN-T(1) (step S1708), and terminates the above process.

[0090] In step S1709, APN-C determines that there is a path failure in the control signal B (OSC) between APN-T(1) and APN-C (step S1709). Then, APN-C communicates control signal B with APN-T(1) via APN-T(2) (step S1710).

[0091] Next, APN-C checks the communication between APN-C and APN-G (step S1711). APN-C determines whether or not there is a response from the communication unit of APN-G to control signal B (step S1712). If there is a response from APN-G to control signal B (step S1712: yes), APN-C proceeds to the process in step S1713. On the other hand, if there is no response from APN-G to control signal B (step S1712: no), APN-C proceeds to the process in step S1714.

[0092] In step S1713, APN-C determines that there is a failure between APN-T and APN-G (step S1713), and terminates the above process. In step S1714, APN-C determines that there is a failure between APN-C and APN-G (step S1714), and terminates the above process.

[0093] Through the above process, APN-C can identify the location of the fault (failure) in each device (transmission path) of the APN network. Furthermore, it becomes possible to communicate control signal B with each device while avoiding this fault (failure) location, enabling continuous monitoring and control of the transmission status of the APN network.

[0094] Figure 18 is a flowchart showing another example of APN-C processing. The processing shown in Figure 18 is almost the same as that in Figure 17, with the only difference being the processing of data compression for control signal B (step S1705a). In step S1705a, depending on the transfer capacity, control signal B transmitted from APN-C to APN-T(1) is either sent from the APN-T(2) parent, or the APN-T(2) host compresses the data before sending it to APN-T(2). Then, APN-T(2) notifies the APN-T(1) parent / -T(1) host of control signal B.

[0095] The process shown in Figure 18 corresponds to Figures 14 and 15, where the APN-T(1) parent CPU 412 performs a search (information gathering). The APN-T(1) parent CPU 412 outputs the search result LOG to the APN-T(1) host CPU 411. The APN-T(1) host CPU 411 compresses the control signal B and transmits it to the APN-C. The APN-C analyzes the received LOG and instructs the APN-T(1) host on the control content.

[0096] (Other transmission line configurations) Figure 19 shows another example of the transmission path configuration in the embodiment. As shown in Figure 19, the main signal A may use a single-core bidirectional optical transmission path (optical fiber). Similarly, the path for the control signal B can also use a single-core bidirectional optical transmission path.

[0097] (Examples of APN-T configurations) The following describes various APN-T configuration examples and an example of switching the transmission path of control signal B in the event of a failure in APN-T.

[0098] Figure 20 shows an example configuration of APN-T 1. The APN-T(1) host 401 can accommodate multiple APN-T(1) parent a(402a) to APN-T(1) parent d(402d) in its internal slots. Although the internal configuration of the multiple APN-T(1) parent a(402a) to APN-T(1) parent d(402d) is omitted in Figure 20, each is capable of optical transmission using the main signal A.

[0099] Furthermore, APN-T(1) parent a(402a) to APN-T(1) parent d(402d) each have an OSC unit 415(415a to 415d) and can communicate control signal B using the OSC.

[0100] Now, let's assume that communication of control signal B using the OSC by the OSC unit 415b of APN-T(1) parent b(402b) is interrupted at location X4. In this case, the control of APN-C as described above will switch the path so that the control signal B of APN-T(1) parent b(402b) is connected to APN-C via the OSC unit 415c of another APN-T parent c(402c).

[0101] Figure 21 is a diagram showing an example of control signal path switching processing corresponding to APN-T configuration example 1. The example of path switching processing corresponding to configuration example 1 in Figure 20 will be explained using Figure 21. Figure 21(a) is a flowchart showing the processing content when there is a failure at control signal location X4, and Figure 21(b) is a sequence diagram of information sent and received between each device corresponding to each processing content in Figure 21(a).

[0102] As shown in Figure 21(a), during operation, APN-C enters a periodic monitoring state for each APN-T(1) parent using control signal B (step S2101). If a communication failure occurs at location X4 in Configuration Example 1, communication between APN-C and APN-T(1) parent b is interrupted (step S2102). In this case, APN-C switches the transmission path of control signal B to monitoring control from another APN-T(1) parent c (step S2103). After this, APN-C and APN-T return to the periodic monitoring state of control signal B (step S2105).

[0103] The processing of each device will be explained using Figure 21(b). APN-C performs periodic status monitoring polling with each parent a to d of APN-T(1) using control signal B (step S2111). If a point of failure X4 occurs, even if APN-C performs periodic status monitoring polling with parent b of APN-T(1), parent b of APN-T(1) will not respond to APN-C (step S2121).

[0104] In this case, APN-C checks the status of APN-T(1) parent c (checking if main signal A is alive in a liveness query) with another parent of APN-T(1), for example, APN-T(1) host (step S2131). Assume that in the state shown in Figure 20, main signal A of APN-T(1) parent c is in a communicable state. As a result, APN-T(1) host checks the status of APN-T(1) parent b (step S2132).

[0105] Then, the APN-T(1) host switches the control signal B from APN-T(1) parent b to APN-C via APN-T(1) parent c. As a result, APN-C receives the control signal B from APN-T(1) parent b via APN-T(1) parent c and performs monitoring and control of APN-T(1) parent b.

[0106] Figure 22 shows an example configuration of APN-T 2. In the example configuration of Figure 22, the APN-T(1) host 401 accommodates an APN-T(1) parent (402A) and multiple APN-T(1) children a (402a) to g (402g) in its internal slots. Only the APN-T(1) parent (402A) has an OSC unit 415, while the APN-T(1) children do not have an OSC unit (they are not installed).

[0107] The CPU 411 of the APN-T(1) host 401 collects information from multiple APN-T(1) children a (402a) to g (402g) and notifies APN-C via the APN-T(1) parent 402A.

[0108] Now, let's assume that APN-T(1) child d (402d) fails. In this case, the CPU 411 of the APN-T(1) host 401 notifies APN-C via the OSC unit 415 of the APN-T(1) parent 402A that there is information that APN-T(1) child d (402d) cannot communicate due to failure. However, in Configuration Example 1, since information from multiple APN-T(1) children a (402a) to g (402g) is collected and notified to APN-C, the processing load on the CPU 411 of the APN-T(1) host is large.

[0109] Figure 23 is a diagram showing an example of control signal path switching processing corresponding to APN-T configuration example 2. The example of path switching processing corresponding to configuration example 2 in Figure 22 will be explained using Figure 23. Figure 23(a) is a flowchart showing the processing content when APN-T(1) child d(402d) fails, and Figure 23(b) is a sequence diagram of information sent and received between each device corresponding to each processing content in Figure 23(a).

[0110] As shown in Figure 23(a), during operation, APN-C periodically monitors the status of the parent and child APN-T(1) using control signal B (step S2301). If a failure occurs in child d in Configuration Example 2, communication between the APN-T(1) parent and APN-T(1) child d is interrupted (step S2302). In this case, the APN-T(1) host detects the failure of APN-T(1) child d (step S2303). The APN-T(1) host then notifies APN-C of the failure of APN-T(1) child d via the APN-T(1) parent, and APN-C returns to periodic status monitoring of control signal B (step S2305).

[0111] The processing of each device will be explained using Figure 23(b). APN-C performs periodic status monitoring polling with the APN-T(1) host 401 using control signal B (step S2311). At this time, the APN-T(1) host 401 communicates with APN-C via the OSC unit 415 of the APN-T(1) parent 402A.

[0112] The APN-T(1) parent 402A communicates with multiple APN-T(1) children a(402a) to g(402g) via the APN-T(1) host 401 (step S2321).

[0113] Now, let's assume that APN-T(1) child d(402d) has failed. In this case, the communication signal between APN-T(1) host 401 and APN-T(1) child d(402d) will be interrupted, and APN-T(1) child d(402d) will not respond to APN-T(1) host 401 (step S2322).

[0114] In this case, the APN-T(1) host 401 can notify APN-C via the OSC unit 415 of the APN-T(1) parent 402A that the APN-T(1) child d(402d) has failed (step S2351).

[0115] Figure 24 shows an example configuration of APN-T 3. In this example configuration, similar to example configuration 2 (Figure 21), the APN-T(1) host 401 accommodates an APN-T(1) parent (402A) and multiple APN-T(1) children a (402a) to g (402g) in its internal slots. In addition, only the APN-T(1) parent (402A) has an OSC unit 415, while the APN-T(1) children do not have an OSC unit (they are not equipped with one).

[0116] In configuration example 3, the APN-T(1) 402A and multiple APN-T(1) child devices a(402a) to g(402g) are connected via pass-through (daisy-chain) connections between adjacent devices. The APN-T(1) host 401 transmits the data (control signal B) that has been passed through multiple children to the APN-C via the OSC unit 415 of the APN-T(1) parent 402A. The APN-T(1) parent 402A also outputs the data (control signal B) received from the APN-C by the OSC unit 415 to the adjacent APN-T(1) child device a(402a) via the pass-through connection.

[0117] Then, multiple APN-T(1) children a(402a) to g(402g) extract (or add) only their own data, and pass the other data to the neighboring devices. According to Configuration Example 3, the CPU 411 of the APN-T(1) host 401 does not need to collect information from multiple children a to g, thus reducing the processing load.

[0118] Figure 25 shows the failure scenario in APN-T configuration example 3. Each of the multiple APN-T(1) children a(402a) to APN-T(1) child g(402g) has an information path to the CPU 411 of the APN-T(1) host 401, but this is not used under normal circumstances.

[0119] If APN-T(1) child d(402d) fails, the following steps (1) to (4) are performed. (1) APN-T(1) child e (402e), which is adjacent to the pass-through connection of child d, notifies CPU 411 of APN-T(1) host 401. (2) The APN-T(1) host 401 notifies the CPU 411 to send information about the adjacent APN-T(1) child c (402c) to the passthrough connection preceding child d. (3) The APN-T(1) child c(402c) sends control signal B to the CPU 411 of the APN-T(1) host 401. (4) The APN-T(1) host 401 sends control signal B to the APN-T(1) child e.

[0120] Through the above process, the APN-T(1) host can transmit information (control signals B) from multiple APN-T(1) children a to g to the APN-C, excluding information from children that are unable to communicate due to failure. Furthermore, according to Configuration Example 3, even if there are multiple children that do not have an OSC unit and a failure occurs in a child, the information of each normal child can be transmitted to the APN-C without increasing the processing load on the CPU.

[0121] Figure 26 is a diagram showing an example of control signal path switching processing corresponding to APN-T configuration example 3. The example of path switching processing corresponding to configuration example 3 in Figure 25 will be explained using Figure 26. Figure 26(a) is a flowchart showing the processing content when APN-T(1) child d(402d) fails, and Figure 26(b) is a sequence diagram of information sent and received between each device corresponding to each processing content in Figure 26(a).

[0122] As shown in Figure 26(a), during operation, APN-C periodically monitors the status of the parent and child APN-T(1) using control signal B (step S2601). If a failure occurs in child d in Configuration Example 3, a communication failure occurs between the APN-T(1) parent and APN-T(1) child d (step S2602). In this case, the APN-T(1) host searches for the location of the failure (step S2603). Then, the APN-T(1) host excludes the location of the failure (child) and sends status monitoring information (control signal B) to APN-C (step S2605).

[0123] The processing of each device will be explained using Figure 23(b). In Figure 23(b), for convenience, some of the multiple children of APN-T(1) (child b, child g) are omitted from the description. Each time periodic status monitoring (polling) is performed by APN-C using control signal B, the APN-T parent performs communication to collect information by circulating through the multiple children a to g connected via pass-through and returning to the APN-T parent (step S2611).

[0124] If APN-T(1) child d fails, communication patrols from APN-T(1) child e(402e) onward cannot be performed, and APN-T host 401 times out due to signal failure. The APN-T(1) host notifies APN-C of the timeout information (control signal B) via APN-T(1) (step S2621).

[0125] The APN-T(1) parent then requests the APN-T(1) host to perform a route check to locate the fault (step S2631). The APN-T(1) host outputs route check signals to multiple children a-g (step S2632). Multiple children a-g respond to the APN-T(1) host in response to the route check.

[0126] Here, APN-T(1) child d is unable to respond to APN-T(1) host due to a malfunction (step S2632d). As a result, APN-T(1) host outputs information (control signal B) indicating the location of the malfunction determined by APN-T(1) child d to the APN-T(1) parent (step S2633).

[0127] Subsequently, the APN-T(1) parent collects information on each child a to g via a route that excludes child d, the location of the failure (see Figure 25) (step S2651). The APN-T(1) host transmits the collected information (control signal B) for each child a to g (excluding child d) to the APN-C via the OSC unit 415 of the APN-T(1) parent (step S2652). Subsequently, the APN-C performs monitoring and control of the APN-T(1) parent and multiple children (a to g, excluding child d).

[0128] (Example of connection configuration with multiple APN-T and APN-G connections) The following describes example connection configurations for APN-T and APN-G, as well as an example of the switching process for the transmission path of control signal B in the event of a failure in APN-T.

[0129] Figure 27 shows an example of a connection configuration 1 between multiple APN-T and APN-G networks. In connection configuration 1 in Figure 27, two APN-T(1) hosts and one APN-T(2) host (401) are connected to one APN-G network for the transmission path of control signal B.

[0130] The APN-T(1) host and the APN-T(2) host (401) each accommodate one parent 402A and multiple child devices 402a to 402c. The APN-T(1) host and the APN-T(2) host (401) each transmit information (control signals B) from the multiple child devices 402a to 402c to the APN-G via the OSC unit 415 of the parent 402A, and transmit it to the APN-C (not shown).

[0131] From the APN-G's perspective, it will send multiple (two) control signals B to the APN-T(1) host and the APN-T(2) host (401). In this case, the wavelengths of control signal B1 between APN-G and APN-T(1) and control signal B2 between APN-G and APN-T(2) (the wavelengths of the OSC signals) should be different. If control signals B1 and B2 have the same wavelength, they should be in a format that allows APN-T(1) and APN-T(2) to be distinguished.

[0132] Figure 28 shows an example of route switching processing in the event of a failure in connection configuration example 1 of multiple APN-T and APN-G connections. In connection configuration example 1 shown in Figure 27, communication is established between APN-T(1) host and APN-T(2) host via their respective CPUs 411.

[0133] Now, let's assume a failure occurs at location X5 in APN-T(2). In this case, the APN-T(2) host forwards the control signal B2, which is used for communication with APN-G (APN-C), to the APN-T(1) host via inter-CPU communication. The APN-T(1) host can then send the control signal B2 along with the control signal B1 from the OSC unit 415 of APN-T(1) to APN-G.

[0134] Figure 29 shows an example of a connection configuration 2 between multiple APN-T and APN-G networks. In the example in Figure 29, for the transmission path of control signal B, two APN-T(1) hosts and one APN-T(2) host (401) are connected to one APN-G network. Also, as shown in Figure 4, the control signal B is wavelength-multiplexed with the main signal A by a multiplexer 416.

[0135] In this connection configuration example 2, the wavelengths of control signals B1 and B2 cannot simply be the same. For example, one of the two control signals B1 and B2 can be set to the OSC wavelength (1511 nm), and the other to a different wavelength other than the OSC wavelength. In addition, various formats may be used for transmission, such as assigning an identifier that can distinguish multiple control signals B1 and B2 to a single OSC wavelength OSC signal.

[0136] Figure 30 shows an example of route switching processing in the event of a failure in Connection Configuration Example 2, which involves multiple APN-T and APN-G connections. In Connection Configuration Example 2, as in Connection Configuration Example 1, communication is established between the APN-T(1) host and the APN-T(2) host via their respective CPUs 411.

[0137] Now, let's assume a failure occurs at location X5 in APN-T(2). In this case, the APN-T(2) host forwards control signal B2, which is used for communication with APN-G (APN-C), to the APN-T(1) host via inter-CPU communication. The APN-T(1) host then transmits control signal B2 along with control signal B1 from the OSC unit 415 of APN-T(1) to APN-G. Control signals B1 and B2 have different OSC wavelengths. Alternatively, control signals B1 and B2 can be transmitted in an OSC signal format that allows for identification.

[0138] (Examples of other APN network configurations and routing switching processes in case of failure) Figure 31 shows an example of another APN network configuration and an example of route switching processing in the event of a failure. In the APN network shown in Figure 31, multiple (3) APN-C(a) to APN-C(c) manage and control the ring-shaped APN networks A, B, and C, respectively.

[0139] APN-C(a) to APN-C(c) transmit control information B to other adjacent APN-Cs. Additionally, APN-G(b), which is located on the APN network (transmission path), can switch the transmission of the main signal between APN network A and APN network B. Furthermore, APN-G(c) can switch the transmission of the main signal between APN network B and APN network C.

[0140] In the example shown in Figure 31, APN-T(1) and APN-T(2), which are connected via E2E, transmit the main signal via APN-G(b) and APN-G(c) of APM networks A, B, and C.

[0141] Each APN-C(a) to APN-C(c) monitors and controls the status of each device located in the APN networks A to C under its control, as well as the transmission status of the main signal, based on control signal B.

[0142] Now, suppose a fault occurs at point X6 between APN-C(a) and APN-G(b), making it impossible to transmit control signal Bb. In this case, APN-G(b) can superimpose control signal Bb onto the main signal of APN network A and forward it to APN-G(a), and APN-G(a) can then transmit control signal Bb along with control signal Ba to APN-C(a). Alternatively, APN-G(b) can forward control signal Bb along with control signal Bc to APN-C(b), and APN-C(b) can then forward control signal Bb to APN-C(a).

[0143] Thus, even with various APN network configurations, control signals can be transmitted to APN-C via each device on the APN network.

[0144] By the way, regarding the control unit 800 (see Figure 8) of the optical communication controller (APN-C), we have explained it using the CPU 801 as an example, but it is not limited to this; a dedicated DSP, ASIC, or FPGA for high-speed signal processing can also be used. ASIC stands for Application Specific Integrated Circuit, and FPGA stands for Field Programmable Gate Array.

[0145] The optical communication controller (APN-C) of the embodiment described above manages and controls multiple devices under the optical transmission network. The APN-C includes a control unit that acquires control signals, including the status of each device and the status of the transmission path, via a transmission path different from the main signal transmission path, searches for an alternative communication path if control signals cannot be acquired, acquires control signals using the alternative path, and continues to manage and control the optical transmission network. This improves the stability and availability of the APN network system and minimizes service interruptions in the event of a failure.

[0146] Furthermore, in this embodiment, when the control unit of APN-C obtains a control signal including the location of a failure from any of the devices, it searches for an alternative route that bypasses the failure path and continues to communicate control signals with the device that experienced the failure. As a result, APN-C can always obtain control signals and manage and control the APN network with stability and availability.

[0147] Furthermore, in this embodiment, if the control unit cannot obtain a control signal, the APN-C searches for the location of the fault on a different transmission path. This allows the APN-C to immediately detect the location of the fault in the APN network, minimizing service interruptions during a failure.

[0148] Furthermore, the control unit of the APN-C in this embodiment includes an alternative path as part of the transmission path for the main signal. This allows the APN-C to acquire control signals through various transmission paths, enabling immediate detection of failures in each device of the APN network and minimizing service interruptions during failures.

[0149] Furthermore, in this embodiment, the APN-C's control unit checks the status of each device when searching for an alternative path and sets a transmission path that bypasses the path where the failure occurred by sending control signals via a device capable of communication. As a result, the APN-C can obtain control signals via a device capable of communication, immediately detect failures in each device of the APN network, and minimize service interruptions during failures.

[0150] Furthermore, the optical communication system of this embodiment includes a plurality of devices (APN-T, APN-G) under the APN network, and an optical communication controller APN-C that manages and controls the plurality of devices. The APN-C has a control unit that acquires control signals, including the status of each device and the status of the transmission path, via a transmission path different from the transmission path of the main signal, searches for a communicationable alternative path if it is not possible to acquire control signals, acquires control signals using the alternative path, and continues to manage and control the optical transmission network. This improves the stability and availability of the APN network system and minimizes service interruptions in the event of a failure.

[0151] Furthermore, in the optical communication system of this embodiment, the control signals between APN-C and each device include a transmission path for electrical or optical signals that directly connects APN-C and each device. As a result, APN-C can acquire control signals not only as main signals (optical signals) but also as electrical signals such as Ethernet with each device, thereby immediately detecting failures in each device of the APN network and minimizing service interruptions during failures.

[0152] Furthermore, each device in the optical communication system of this embodiment includes a monitoring gateway APN-G located on the APN network, and a pair of optical transceivers APN-T connected via APN-G to transmit the main signal. As a result, APN-C can obtain control signals via any APN-T or APN-G on the APN network, and can always obtain control signals regardless of the location of the failure, minimizing service interruptions in the event of a failure.

[0153] Furthermore, the APN-T of the optical communication system in this embodiment has a control unit that wavelength-multiplexes the control signal with the main signal when the alternative path for the control signal between it and the APN-C includes the transmission path for the main signal. As a result, the APN-C can utilize the path for the main signal as part of the transmission path for the control signal, and can always acquire the control signal regardless of the location of the fault.

[0154] Furthermore, the APN-T control unit of the optical communication system in this embodiment compresses the control signals. This makes it possible to transmit the control signals while preventing delays in the control signals and bandwidth congestion of the main signals, when the main signal is used in part of the control signal transmission path.

[0155] Furthermore, the optical communication system in this embodiment may also have an optical transmission path on the control signal transmission path that performs bidirectional communication with a single core. In this way, control signals can be transmitted via various optical transmission paths.

[0156] Furthermore, in the optical communication system of this embodiment, the APN-T has multiple modules that can be inserted and removed from the host, and when a module fails, the host notifies the optical communication controller of information about the failed module using a control signal. This allows the APN-T to notify the APN-C of module-specific failures.

[0157] Furthermore, the APN-T modules of the optical communication system in this embodiment include a parent module having an OSC unit capable of sending OSC signals, and a plurality of child modules (402b to 402d) that do not have an OSC unit. When a child module fails, the host notifies the optical communication controller of information about the failed module via the OSC unit of the parent module using a control signal. In this way, even if a child module that cannot send OSC signals fails, the host can use the OSC signal of the parent module to notify the APN-C of the control signal including the failure.

[0158] Furthermore, in the embodiment of the optical communication system, multiple APN-T modules circulate and transfer control signals between adjacent parent modules and multiple child modules via pass-through connections. When a child module fails, the APN-T allows the host to transfer control signals via a transfer path that avoids the failed child module, and the host notifies the optical communication controller of information about the failed module via the control signal through the OSC unit of the parent module. In this way, by connecting multiple parent and child modules via pass-through connections and circulating and transferring control signals, the processing load on the host can be reduced.

[0159] Furthermore, the optical communication system of this embodiment can also be configured in which multiple APN-T(1) and APN-T(2) are connected to APN-G. If a failure occurs in the transmission of control signals between one APN-T(2) and APN-G, one APN-T(2) will forward the control signal through communication with the other APN-T(1), and the other APN-T(1) will notify APN-C of the failure at one APN-T(2) via the APN-G using the control signal. As a result, even in a configuration in which multiple APN-T(1) and APN-T(2) are connected to APN-G, failures at multiple APN-T(1) and APN-T(2) can be notified to APN-C via APN-G.

[0160] Furthermore, in the optical communication system of this embodiment, when multiple control signals B1 and B2 between the APN-G and multiple APN-Ts are wavelength-multiplexed into the main signal, the multiple APN-Ts communicate the multiple control signals using different OSC signal wavelengths for each optical APN-T, or communicate using a single wavelength OSC signal that allows for APN-T identification. This makes it possible to transmit control signals between multiple APN-Ts and the APN-G in a way that allows for the identification of multiple APN-Ts using the main signal's OSC signal.

[0161] Furthermore, in this embodiment, the optical communication system is managed by multiple APN networks, each managed by a corresponding APN-C. In this system configuration, if a failure occurs in the transmission path of a control signal in one APN network A, the control signal, including information about the failure, is transferred to the APN-C of one APN network A via an alternative path through the APN-C of the other APN network B. In this way, control signals can be transferred across multiple APN networks, enabling the transfer of control signals between various APN networks.

[0162] With regard to the embodiments described above, the following additional information is disclosed.

[0163] (Note 1) In an optical communication controller that manages and controls multiple devices under an optical transmission network, A control signal, including the status of each device and the status of the transmission line, is acquired via a transmission path different from the transmission path of the main signal. If the aforementioned control signal cannot be obtained, a communication alternative path is searched for, and the aforementioned control signal is obtained using the alternative path. A control unit that continues to manage and control the optical transmission network, An optical communication controller characterized by having the following features.

[0164] (Note 2) The control unit is, When the control signal including the location of the fault is obtained from any of the above devices, The system searches for an alternative route that bypasses the route through which the fault occurred, and continues to communicate the control signal with the faulty device. The optical communication controller described in Appendix 1, characterized by the features described herein.

[0165] (Note 3) The control unit is, If the aforementioned control signal cannot be obtained, the system searches for the location of the fault on the different transmission path. The optical communication controller described in Appendix 1, characterized by the features described herein.

[0166] (Note 4) The control unit is, The alternative path includes a portion of the transmission path for the main signal and communicates. The optical communication controller described in Appendix 1, characterized by the features described herein.

[0167] (Note 5) The control unit is, During the search for the alternative route, the status of each device is checked. The control signal is transmitted via the communicationable device, and a transmission path is set that bypasses the path where the fault occurs. The optical communication controller described in Appendix 1, characterized by the features described herein.

[0168] (Note 6) In an optical communication system including a plurality of devices under an optical transmission network and an optical communication controller that manages and controls the plurality of devices, The aforementioned optical communication controller is A control signal, including the status of each device and the status of the transmission line, is acquired via a transmission path different from the transmission path of the main signal. If the aforementioned control signal cannot be obtained, a communication alternative path is searched for, and the aforementioned control signal is obtained using the alternative path. A control unit that continues to manage and control the optical transmission network, An optical communication system characterized by comprising the following features.

[0169] (Note 7) The control signals between the optical communication controller and each of the devices include an electrical or optical signal transmission path that directly connects the optical communication controller and each of the devices. The optical communication system described in Appendix 6, characterized by the features described herein.

[0170] (Note 8) Each of the above devices is connected to a monitoring gateway located on the optical transmission network, A pair of optical transceivers connected via the monitoring gateway and transmitting the main signal, The optical communication system according to Appendix 6, characterized by including the following:

[0171] (Note 9) If the alternative path for the control signal between the optical transceiver and the optical communication controller includes the transmission path for the main signal, The control signal is wavelength-multiplexed with the main signal. The optical communication system according to Appendix 8, characterized by having a control unit.

[0172] (Note 10) The control unit of the optical transceiver is The aforementioned control signals are compressed using data compression. The optical communication system described in Appendix 8, characterized by the features described herein.

[0173] (Note 11) The optical transmission path on the transmission path of the control signal shall be a single-core bidirectional communication path. The optical communication system described in Appendix 6, characterized by the features described herein.

[0174] (Note 12) The optical transceiver has multiple modules that can be inserted and removed from the host, When the module fails, the host notifies the optical communication controller of information about the failed module using the control signal. The optical communication system described in Appendix 8, characterized by the features described herein.

[0175] (Note 13) The multiple modules are, A parent module having an OSC section capable of sending OSC signals, It includes a plurality of child modules that do not have the OSC section, When the child module fails, the host notifies the optical communication controller of information about the failed module via the OSC unit of the parent module using the control signal. The optical communication system described in Appendix 12, characterized by the features described herein.

[0176] (Note 14) Multiple modules transfer the control signals between adjacent parent modules and multiple child modules via pass-through connections. When the child module fails, the host transmits the control signal via a transmission path that avoids the failed child module. The host notifies the optical communication controller of information about the faulty module via the OSC unit of the parent module using the control signal. The optical communication system described in Appendix 13, characterized by the features described herein.

[0177] (Note 15) In a configuration in which multiple optical transceivers are connected to the monitoring gateway, if a failure occurs in the transmission of the control signal between one of the optical transceivers and the monitoring gateway, One optical transceiver transmits the control signal through communication with the other optical transceiver, and via the other optical transceiver, notifies the optical communication controller of the failure occurring in one of the optical transceivers via the monitoring gateway using the control signal. The optical communication system described in Appendix 8, characterized by the features described herein.

[0178] (Note 16) When multiple control signals between the monitoring gateway and multiple optical transceivers are wavelength-multiplexed into the main signal, Multiple optical transceivers communicate multiple control signals using different OSC signal wavelengths for each optical transceiver, or communicate using a single-wavelength OSC signal that allows each optical transceiver to be identified. The optical communication system described in Appendix 15, characterized by performing the following:

[0179] (Note 17) Multiple optical transmission networks are managed by multiple corresponding optical communication controllers. If a failure occurs in the transmission path of the control signal in the optical transmission network, The control signal, including information about the occurrence of a fault, is transferred to the optical communication controller of the first optical transmission network via an alternative path that passes through the optical communication controller of the other optical transmission network. The optical communication system described in Appendix 6, characterized by the features described herein. [Explanation of Symbols]

[0180] 100 Optical Communication Controller (APN-C) 401 APN-T Host 402 APN-T Parent 411,412,801 CPU 413 DSP 414 L2SW 415 OSC Department 420 Multiplexer / Demultiplexer 600 Monitoring control information 800 Control Unit 802 memory 805 Recording media 810 Bus APN-T Optical Transceiver APN-G Monitoring Gateway A Main signal B Control signal X(X1~X6) Location of the outage (service failure)

Claims

1. In an optical communication controller that manages and controls multiple devices under an optical transmission network, A control signal, including the status of each device and the status of the transmission line, is acquired via a transmission path different from the transmission path of the main signal. If the aforementioned control signal cannot be obtained, a communication alternative path is searched for, and the aforementioned control signal is obtained using the alternative path. A control unit that continues to manage and control the optical transmission network, An optical communication controller characterized by having the following features.

2. The control unit, When the control signal including the location of the fault is obtained from any of the above devices, The system searches for an alternative route that bypasses the route through which the fault occurred, and continues to communicate the control signal with the faulty device. The optical communication controller according to feature 1.

3. The control unit, If the aforementioned control signal cannot be obtained, the system searches for the location of the fault on the different transmission path. The optical communication controller according to feature 1.

4. The control unit, The alternative path includes a portion of the transmission path for the main signal and communicates. The optical communication controller according to feature 1.

5. The control unit, During the search for the alternative route, the status of each device is checked. The control signal is transmitted via the communicationable device, and a transmission path is set that bypasses the path where the fault occurs. The optical communication controller according to feature 1.

6. In an optical communication system including multiple devices under an optical transmission network and an optical communication controller that manages and controls the multiple devices, The aforementioned optical communication controller is A control signal, including the status of each device and the status of the transmission line, is acquired via a transmission path different from the transmission path of the main signal. If the aforementioned control signal cannot be obtained, a communication alternative path is searched for, and the aforementioned control signal is obtained using the alternative path. A control unit that continues to manage and control the optical transmission network, An optical communication system characterized by comprising the following features.

7. The control signals between the optical communication controller and each of the devices are A transmission path for electrical or optical signals that directly connects the optical communication controller and each of the devices, The optical communication system according to feature 6.

8. Each of the above devices includes a monitoring gateway located on the optical transmission network, A pair of optical transceivers connected via the monitoring gateway and transmitting the main signal, The optical communication system according to claim 6, characterized by including the following:

9. If the alternative path for the control signal between the optical transceiver and the optical communication controller includes the transmission path for the main signal, The control signal is wavelength-multiplexed with the main signal. The optical communication system according to claim 8, characterized by having a control unit.

10. The control unit of the optical transceiver is The aforementioned control signals are compressed using data compression. The optical communication system according to feature 8.

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