Monitoring device, monitoring method, and monitoring program

Abstract

A data acquisition unit (11) of a monitoring device (1) acquires, from an optical channel monitor (106) for measuring the power value of an optical signal outputted by each of nodes (110 to 140), a power value (IV1) in a range (Ra) including all wavelengths of a target channel (TCh), and acquires power values (IV2, IV3) in ranges (Rb, Rc) each including some of the wavelengths of the target channel (Tch). A determination unit (12) determines an abnormality in each node (110 to 140) by comparing the power values (IV1, IV2, IV3) respectively with threshold values (TH1, TH2, TH3) based on the power value in a stationary state of the node (110 to 140).

Description

[Technical Field]

[0001] The present invention relates to a monitoring device, a monitoring method, and a monitoring program. [Background technology]

[0002] In an optical transmission system, a lightpath, which is a communication path for optical signals, is constructed by multiple nodes interconnected by optical fibers. In the lightpath, a sending end node and a receiving end node are connected via multiple relay nodes.

[0003] If an abnormality occurs in any of the multiple nodes that make up the optical path, it will affect the quality of the optical signal transmitted over the optical path, so it is necessary to identify the node where the abnormality occurred. For example, it has been proposed to provide each node with a high-resolution monitor such as an OSA (Optical Spectrum Analyzer), and to accurately grasp the waveform shape of the optical signal output from the node in a monitoring device, thereby determining whether there is an abnormality in the node (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Behnam Shariati, et al. "Learning From the Optical Spectrum: Failure Detection and Identification" JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 37, NO. 2 (2019) Summary of the Invention [Problem to be solved by the invention]

[0005] However, providing a high-resolution monitor at each node increases the installation cost of the optical transmission system, and also increases the amount of data transmitted from each monitor to the monitoring device, thereby increasing the communication load.

[0006] There is a demand for a monitoring device that can improve the accuracy of determining abnormalities in nodes while reducing the installation costs of the monitors and the communication load with the monitors. [Means for solving the problem]

[0007] The monitoring device according to the present invention acquires a first power value in a first range including all wavelengths of the channel from a monitor that measures the power value of the optical signal output from the transmission device, and only and a determination unit that compares the first power value and the second power value with thresholds based on power values ​​in a steady state of the transmission device to determine whether there is an abnormality in the transmission device. [Effects of the Invention]

[0008] According to the present invention, it is possible to improve the accuracy of determining abnormalities in nodes while reducing the installation cost of the monitor and the communication load with the monitor. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a conceptual diagram of an optical transmission system to which a monitoring device according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a node. [Figure 3] 10A and 10B are diagrams illustrating waveforms of optical signals of a plurality of channels output from a WSS. [Figure 4] FIG. 2 is a functional block diagram showing the configuration of a monitoring device. [Figure 5] 10A and 10B are diagrams illustrating a range in which a data acquisition unit acquires power values; [Figure 6]10A and 10B are diagrams illustrating an example of an abnormal waveform caused by an abnormality in the filter function of a WSS. [Figure 7] 10A and 10B are diagrams illustrating a manner in which a power value is acquired for a waveform in which an abnormality has occurred. [Figure 8] FIG. 10 is a diagram illustrating an example of threshold setting. [Figure 9] FIG. 10 is a diagram illustrating an example of an abnormality determination process. [Figure 10] 10 is a flowchart showing the flow of an abnormality determination process. [Figure 11] 10 is a flowchart showing the flow of a threshold setting process. [Figure 12] FIG. 2 is a hardware configuration diagram illustrating an example of a computer that realizes the functions of the monitoring device according to the present embodiment. [Figure 13] 10 is a diagram illustrating a range for acquiring a power value in Modification 1. FIG. [Figure 14] FIG. 10 is a diagram illustrating a comparative example. [Figure 15] 10 is a flowchart showing the flow of an abnormality determination process according to Modification 1. [Figure 16] FIG. 10 is a diagram illustrating a range for acquiring a power value in Modification 2. [Figure 17] FIG. 11 is a functional block diagram showing the configuration of a monitoring device according to a third modification. [Figure 18] 11 is a flowchart showing the flow of a threshold correction process according to Modification 3. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described with reference to the drawings. In the present embodiment, an example in which a monitoring device is applied to an optical transmission system will be described. FIG. 1 is a conceptual diagram of an optical transmission system to which a monitoring device according to this embodiment is applied. FIG. 2 is a diagram illustrating the configuration of a node.

[0011] As shown in Fig. 1, an optical transmission system 100 has a plurality of nodes interconnected by an optical fiber fb, which is an optical transmission path. Fig. 1 shows an example in which an optical path OP, which is a communication path for an optical signal, is configured by four nodes 110, 120, 130, and 140. In the optical path OP, an optical signal is transmitted from node 110 to node 140. That is, node 110 is a transmitting end node, node 140 is a receiving end node, and nodes 120 and 130 are relay nodes. 1 shows an example in which multiple nodes 110, 120, 130, and 140 are connected in series in the optical transmission system 100, but the nodes may be connected in a mesh or ring configuration. That is, each node can be connected to other nodes (not shown) and can output and input optical signals to and from other nodes.

[0012] Each of the nodes 110, 120, 130, and 140 is configured as a transmission device. The transmission device may be, for example, an optical cross connect (OXC) device. Each of the nodes 110, 120, 130, and 140 transmits an optical wavelength multiplexed signal in which optical signals of multiple channels are wavelength-multiplexed. Although not shown, an inline amplifier (ILA) for amplifying the optical wavelength multiplexed signal may be provided between each of the nodes 110, 120, 130, and 140 of the optical path OP.

[0013] The transmitting end node 110 and the receiving end node 140 are respectively equipped with transponders (TPDs) 111 and 141, which are transmitters and receivers. Although not shown, the nodes 120 and 130, which are relay nodes, may also be equipped with transponders, and the nodes 120 and 130 may be transmitting end nodes or receiving end nodes in another optical path OP.

[0014] The transmitting end node 110 wavelength-multiplexes the optical signals input from the transponder 111 and outputs an optical wavelength-multiplexed signal. The relay nodes 120 and 130 demultiplex the optical signals included in the input optical wavelength-multiplexed signal. The relay nodes 120 and 130 wavelength-multiplex the demultiplexed optical signals again and output an optical wavelength-multiplexed signal. The receiving end node 140 demultiplexes the optical signals included in the input optical wavelength-multiplexed signal and receives them at the transponder 141.

[0015] Although the nodes 110 to 140 have the same configuration, FIG. 2 shows the configuration of the node 120 as a representative. 2, the node 120 includes a pre-amplifier 101, a coupler (CPL) 102, a wavelength selective switch (hereinafter also referred to as "WSS") 103, a post-amplifier 104, a selector (SEL) 105, and an optical channel monitor (OCM) 106. The node 120 also includes a node controller 152 that controls the operation of the node 120.

[0016] The output side of pre-amplifier 101 is connected to the input side of post-amplifier 104 via coupler 102 and WSS 103. Selector 105 selects one of the outputs of pre-amplifier 101, coupler 102, and WSS 103, and outputs it to optical channel monitor 106.

[0017] The optical channel monitor 106 (monitor) measures the output power of the pre-amplifier 101, the coupler 102, or the WSS 103 input from the selector 105. The measured value of the output power of the WSS 103 is used in the abnormality determination process of the monitoring device 1, which will be described later. The measured value is input to the node controller 152.

[0018] The preamplifier 101 amplifies the wavelength-multiplexed optical signal input from the optical fiber fb, which is an optical transmission line, and inputs the amplified signal to the WSS 103 .

[0019] The WSS 103 separates the optical wavelength multiplexed signal into optical signals of multiple channels. The WSS 103 outputs the separated optical signals to the set output destinations. The WSS 103 outputs the optical signal to be dropped to a transponder (not shown). The WSS 103 inputs the optical signal to be added input from the transponder to the set channel, multiplexes it with the optical signal to be passed through, generates an optical wavelength multiplexed signal, and inputs it to the post-amplifier 104. The post-amplifier 104 amplifies the optical wavelength multiplexed signal and outputs it to the optical fiber fb.

[0020] Although not shown, the WSS 103 includes an array-type optical beam deflection element such as LCOS (Liquid Crystal on Silicon). LCOS has a two-dimensional matrix structure with millions of pixels, allowing multiple control pixels to be assigned to an optical signal. This allows the WSS 103 to change the passband of the optical signal for each channel under the control of the node controller 152, regardless of the hardware configuration. In other words, the WSS 103 has a filter function that filters the optical signal of each channel into a wavelength band set by the node controller 152.

[0021] Fig. 3 is a diagram showing the waveforms of optical signals on multiple channels Ch1, Ch2, and Ch3 output from the WSS 103. Although three channels Ch1, Ch2, and Ch3 are shown in Fig. 3, the number of channels is arbitrary.

[0022] The node controller 152 divides the entire available wavelength band by the grid width and assigns each wavelength band BW to channels Ch1, Ch2, and Ch3. The grid width is variable, with 12.5 GHz as the minimum unit, to 12.5 GHz, 25 GHz, 50 GHz, and 100 GHz. In other words, the node controller 152 can change the number of channels and the width of each wavelength band BW by changing the grid width.

[0023] 3 shows waveforms in a steady state where the filter function of the WSS 103 is functioning normally. In the steady state, the waveforms of channels Ch1, Ch2, and Ch3 are roughly symmetrical and have a gentle peak in the center. In the following description, when there is no need to distinguish between channels Ch1, Ch2, and Ch3, they will simply be referred to as channels Ch.

[0024] Although not shown, the WSS 103 is equipped with a variable optical attenuator. The WSS 103 attenuates and multiplexes the optical signals of channels Ch1 to Ch3. The attenuation amount in the variable optical attenuator is controlled by the node controller 152. The node controller 152 acquires a measured value of optical power for each channel Ch from the optical channel monitor 106. The node controller 152 controls the attenuation amount in the variable optical attenuator based on the measured value. The node controller 152 performs power control to compensate for power loss that occurs when the optical signal of each channel Ch is filtered by the WSS 103.

[0025] The optical channel monitor 106 measures the power value of the optical signal of each channel Ch. The optical channel monitor 106 extracts the optical signal of each channel Ch input from the selector 105 using a filter, and measures the total value of the power in the extracted range. The optical channel monitor 106 can change the extraction range of the optical signal by changing the resolution setting of the filter. The resolution setting of the optical channel monitor 106 is controlled by the node controller 152. During the abnormality determination process of the monitoring device 1, which will be described later, the node controller 152 measures the power values ​​in multiple ranges while changing the resolution of the optical channel monitor 106.

[0026] 1, the nodes 110, 120, 130, and 140 are equipped with node controllers 151, 152, 153, and 154, respectively. The monitoring device 1 is connected to each of the node controllers 151, 152, 153, and 154 via a communication network. The monitoring device 1 is also connected to transponders 111 and 141 provided in the transmitting end node 110 and the receiving end node 140 via the communication network.

[0027] The transponders 111 and 141 include a digital signal processing (DSP) chip internally and utilize surplus resources to monitor the quality of the optical signal transmitted through the optical path OP. The monitoring method may be, for example, a known method described in Japanese Patent Application Laid-Open No. 2020-088628. When the transponders 111 and 141 detect degradation in signal quality, they input a notification to the monitoring device 1. The notification includes information identifying the optical signal for which degradation has been detected. Furthermore, if an abnormality in the transponders 111 and 141 themselves is identified as the cause of the degradation, the notification includes information indicating the abnormality in the transponders 111 and 141.

[0028] FIG. 4 is a functional block diagram showing the configuration of the monitoring device 1. The monitoring device 1 can be configured, for example, as a network controller that manages the entire optical transmission system 100. That is, the monitoring device 1 communicates with the node controllers 151, 152, 153, and 154 and the transponders 111 and 141 to control them and monitor the optical transmission system 100 for abnormalities. As shown in FIG. 4, the monitoring device 1 includes a control unit 10, an input / output unit 15, and a storage unit 16.

[0029] The input / output unit 15 inputs and outputs data between the node controllers 151, 152, 153, and 154 and the transponders 111 and 141. The input / output unit 15 is composed of a communication interface that transmits and receives information via a communication line, and an input / output interface that inputs and outputs information between an input device such as a keyboard (not shown) and an output device such as a display.

[0030] The storage unit 16 further stores a program (monitoring program) for executing each functional unit of the control unit 10, and information necessary for the processing of the control unit 10. As an example, the storage unit 16 stores identification information and configuration information of the nodes 110, 120, 130, and 140. Furthermore, the storage unit 16 stores route information including channel allocation information for each optical signal transmitted through the optical path OP. The storage unit 16 also stores information such as thresholds used in the abnormality determination processing described below.

[0031] The control unit 10 is in charge of all the processes executed by the monitoring device 1. When a notification of degradation in signal quality is input from the transponders 111 and 141 and the notification does not include any abnormality in the transponders 111 and 141 themselves, the control unit 10 performs abnormality determination processing on the nodes 110, 120, 130, and 140. The control unit 10 thereby identifies the node in which the abnormality has occurred.

[0032] The control unit 10 includes a data acquisition unit 11, a determination unit 12, and a threshold setting unit 13. The data acquisition unit 11 identifies the optical signal in which degradation has been detected from the notification from the transponder 141. The data acquisition unit 11 refers to the route information stored in the storage unit 16 and identifies the channel Ch (hereinafter referred to as the "target channel Tch") that is the route of the degraded optical signal. The data acquisition unit 11 communicates with the node controllers 151, 152, 153, and 154, and causes the optical channel monitor 106 of each of the nodes 110, 120, 130, and 140 to measure the power value of the target channel Tch. The node controllers 151, 152, 153, and 154 control the optical channel monitor 106 and the selector 105 (see FIG. 2) to cause the optical channel monitor 106 to measure the power value of the target channel Tch output by the WSS 103. The node controllers 151, 152, 153, and 154 acquire the measurement values ​​of the optical channel monitor 106 and input them to the data acquisition unit 11.

[0033] FIG. 5 is a diagram illustrating the range from which the data acquiring unit 11 acquires power values. The data acquisition unit 11 acquires, from the optical channel monitor 106, power values ​​IV1, IV2, and IV3 in three ranges Ra, Rb, and Rc for the target channel Tch. As shown in the diagram of reference numeral 51 in FIG. 5, the data acquisition unit 11 acquires power values ​​IV1 in a range Ra that includes all wavelengths of the optical signal of the target channel Tch. As shown in the diagram of reference numeral 52 in FIG. 5, the data acquiring unit 11 acquires power values ​​IV2 in a range Rb that includes part of the wavelength of the optical signal of the target channel Tch. As shown in the diagram of reference numeral 53 in FIG. 5, the data acquisition unit 11 acquires power values ​​IV3 in a range Rc that includes part of the wavelength of the optical signal of the target channel Tch and is shifted in position from the range Rb. The power value IV1 corresponds to the first power value, and the power values ​​IV2 and IV3 correspond to the second power value.

[0034] The optical channel monitor 106 changes the filter resolution to extract light in ranges Ra, Rb, and Rc from the optical signal and measures the respective power values ​​IV1, IV2, and IV3. The power values ​​are the sum of the power in each range, i.e., the integrated power values. The widths of the ranges Ra, Rb, and Rc are determined according to the wavelength band BW (see FIG. 3) assigned to each channel Ch. In FIG. 5, as an example, when the grid width is 50 GHz, the widths of the ranges Ra, Rb, and Rc are set to 0.42 nm. Note that the widths of the ranges Rb and Rc may be the same as or different from the range Ra.

[0035] The ranges Rb and Rc may be set at positions offset from each other, and their positions are not limited. The ranges Rb and Rc may be positioned symmetrically with respect to the range Ra. The ranges Rb and Rc may be set so that they partially overlap each other, or so that there is a gap between them. In FIG. 5, as an example, when the position of the range Ra is (X), the position of the range Rb is (X+0.315 nm), and the position of the range Rc is (X-0.315 nm).

[0036] The determination unit 12 compares the power values ​​IV1, IV2, and IV3 acquired by the data acquisition unit 11 with threshold values ​​TH1, TH2, and TH3, respectively. The threshold values ​​TH1, TH2, and TH3 are set in advance by a threshold setting unit 13 (described later) and stored in the storage unit 16. The threshold values ​​TH1, TH2, and TH3 are set based on the power values ​​in the ranges Ra, Rb, and Rc in the steady state, respectively.

[0037] The determination unit 12 calculates the differences D1, D2, and D3 between the power values ​​IV1, IV2, and IV3 and the threshold values ​​TH1, TH2, and TH3 as absolute values. If any of the differences D1, D2, and D3 exceeds a predetermined value PD, the determination unit 12 determines that an abnormality has occurred in that node. The determination unit 12 notifies the user of the determination result via the input / output unit 15.

[0038] The power values ​​IV1 to IV3 are acquired to detect abnormalities in the nodes 110, 120, 130, and 140. In particular, the power values ​​IV2 and IV3 are acquired to detect abnormalities in the waveform of the optical signal caused by an abnormality in the filter function of the WSS 103. FIG. 6 is a diagram illustrating an example of an abnormal waveform caused by an abnormality in the filter function of the WSS 103. In FIG. In the diagrams denoted by reference numerals 61 to 63 in FIG. 6, waveforms in a steady state are indicated by solid lines, and waveforms in which an abnormality has occurred are indicated by dashed lines. As described above, in the steady state, the waveform has a roughly symmetrical shape with a gentle peak in the center. If an abnormality occurs in the filter function of the WSS 103, distortion may occur in the waveform. The diagram indicated by reference numeral 61 in Figure 6 shows a waveform abnormality known as filter shift. As shown in the diagram indicated by reference numeral 61, the waveform of filter shift is asymmetric, with the peak protruding more significantly to the left of the center than in the steady state. Diagrams 62 and 63 show waveform abnormalities known as pixel defects. A pixel defect refers to a state in which a pixel defect occurs in the LCOS that filters the optical signal in the WSS 103. While a steady-state waveform has a gentle peak in the center, as shown in diagrams 62 and 63, the waveform of a pixel defect has a large, sudden drop in power at the peak. As shown in diagram 62, the sudden drop in power can occur in the center of the waveform, or, as shown in diagram 63, it can occur to the right or left of the center.

[0039] Such waveform abnormalities lead to deterioration in the quality of the optical signal, and therefore the monitoring device 1 is required to identify the node that is causing the waveform abnormality. For example, by using a high-resolution monitor such as an OSA, it is possible to accurately grasp waveform abnormalities such as those shown by reference numerals 61 to 63 in FIG. 6 and determine the node abnormality. However, providing an OSA at each node 110, 120, 130, and 140 increases installation costs. Furthermore, the amount of data transmitted from the OSA to the monitoring device 1 increases, which increases the communication load.

[0040] In this embodiment, the optical channel monitor 106 provided in each node 110, 120, 130, and 140 measures the power value at a resolution set according to the wavelength band BW of the target channel Ch, as described above. That is, the optical channel monitor 106 measures the power value at a lower resolution than an OSA. By lowering the resolution of the optical channel monitor 106, the installation cost and communication load are reduced compared to an OSA. However, the power value measured by the optical channel monitor 106 cannot accurately identify waveform abnormalities such as those shown in the diagrams 61 to 63 in FIG. 6.

[0041] In this embodiment, in order to determine whether a node is abnormal using an optical channel monitor 106 set to a low resolution, the power values ​​IV1, IV2, and IV3 obtained from multiple ranges Ra, Rb, and Rc are compared with thresholds TH1, TH2, and TH3, respectively.

[0042] First, if the power value IV1 measured from the range Ra covering all wavelengths is significantly different from the threshold value TH1 based on the steady state, it can be determined that an abnormality has occurred in the nodes 110, 120, 130, and 140. However, waveform abnormalities caused by abnormalities in the filter function of the WSS 103, such as those shown by reference numerals 61 to 63 in FIG. 6, may not be detected by comparing the power value IV1 with the threshold value TH1.

[0043] As described above, the node controllers 151, 152, 153, and 154 perform power control to compensate for the loss caused by filtering in the WSS 103. When a loss occurs due to an abnormality in the filtering function of the WSS 103, the same power control is performed. As shown in the diagram indicated by the reference numeral 61 in Figure 6, the waveform of the filter shift shows that the power peak on the left side is larger than that in the steady state, while the power on the right side is smaller than that in the steady state. In other words, power control is performed so that the power across the entire wavelength is the same. In this case, there is a possibility that the difference D1 between the power value IV1 in the range Ra covering the entire wavelength and the threshold value TH1 will not be large enough to exceed the predetermined value PD. As shown in the diagrams 62 and 63 in Figure 6, the waveform of the pixel defect also has higher power on both sides of the point where the power suddenly drops than in the steady state. In other words, power control is performed so that the power is the same across the entire wavelength. In this case, there is a possibility that the difference D1 between the power value IV1 in the range Ra covering the entire wavelength and the threshold value TH1 will not be large enough to exceed the predetermined value PD.

[0044] FIG. 7 is a diagram illustrating how power values ​​IV2 and IV3 are obtained from ranges Rb and Rc for a waveform in which an abnormality has occurred. As shown in the diagrams of reference numerals 71 to 73 in FIG. 7, by setting ranges Rb and Rc that include part of the wavelength, it becomes easier to include a portion where there is a large difference in power between the waveform where an abnormality occurs and the steady state. For example, as shown in the diagram indicated by the reference numeral 71, the range Rb includes a portion on the right side of the filter shift waveform where the power is lower than in the steady state. Therefore, the difference D2 between the power value IV2 in the range Rb and the threshold value TH2 tends to be large. The range Rc includes a portion on the left side of the filter shift waveform where the power is higher than in the steady state. Therefore, the difference D2 between the power value IV3 in the range Rc and the threshold value TH3 tends to be large.

[0045] The diagram denoted by reference numeral 72 in Figure 7 shows a pixel defect where a sudden drop in power occurs in the center of the waveform, but the ranges Rb and Rc each include areas where the power increases on both ends. As a result, the differences D2 and D3 between the power values ​​IV2 and IV3 in the ranges Rb and Rc and the threshold values ​​TH2 and TH3 tend to be large.

[0046] The diagram labeled 73 in Figure 7 shows a pixel defect with a sudden drop in power on the right side of the waveform, but range Rb spans both the point where the sudden drop in power occurred and the point where the power increased. In this case, the difference D2 between the power value IV2 in range Rb and the threshold value TH2 may not be large. However, range Rc includes only the point where the power increased, so the difference D3 between the power value IV3 in range Rc and the threshold value TH3 is likely to be large.

[0047] In this way, by setting ranges Rb and Rc that include part of the wavelength, it becomes easier to capture areas where the power difference from the steady state is large. As shown in the diagram indicated by reference numeral 73 in Figure 7, even if the range Rb includes part of the wavelength, if compensation for power loss is performed within that range, the power difference from the steady state may not be large. Even in this case, by setting multiple ranges Rb and Rc, it is possible to increase the possibility of capturing areas where the power difference from the steady state is large. By using such a method, it is possible to improve the accuracy of determining abnormalities in the nodes 110, 120, 130, and 140 even when using measurements acquired from the optical channel monitor 106 with low resolution.

[0048] Furthermore, as described above, if an abnormality is determined based on the power value IV1, it can be determined that the cause is an abnormality in a component other than the WSS 103, and if an abnormality is determined based on the power values ​​IV2 and IV3, it can be determined that the cause is an abnormality in the WSS 103. In other words, by acquiring the power values ​​IV1, IV2, and IV3, it is possible to identify the node where the abnormality occurred and also to isolate the location of the abnormality in the node.

[0049] FIG. 8 is a diagram illustrating an example of setting the threshold value. The thresholds TH1, TH2, and TH3 can be set in the same way, so in FIG. 8, the thresholds TH1, TH2, and TH3 are collectively represented as the threshold TH. When an optical signal transmitted through the optical path OP is switched, such as increased or decreased in wave length or route change, fluctuations occur in the steady-state power value of the channel along the route of the switched optical signal. Therefore, the threshold setting unit 13 updates the thresholds TH1, TH2, and TH3 in response to the switching of the optical signal. The threshold setting unit 13 stores the updated thresholds TH1, TH2, and TH3 in the storage unit 16. The storage unit 16 stores the thresholds TH1, TH2, and TH3 set for each channel.

[0050] The threshold setting unit 13 acquires time-series data for each channel by acquiring measured values ​​of the output power of the WSS 103 measured by the optical channel monitor 106 for a certain period of time via the node controllers 151, 152, 153, and 154 of each node 110, 120, 130, and 140. The threshold setting unit 13 acquires time-series data for each of the ranges Ra, Rb, and Rc. As an example, Figure 8 shows time-series data obtained when the grid width is changed from 50 GHz to 12.5 GHz. The threshold setting unit 13 can set the median power value as the threshold value TH, for example. Furthermore, the fluctuation range is set as a predetermined value PD. This reduces erroneous determinations because an abnormality is not detected if the difference between the threshold value TH and the power value is within the range of the fluctuation range in the steady state. When the fluctuation range in the time-series data is large, half the value of the fluctuation range may be set as the predetermined value PD. Furthermore, the threshold value TH is not limited to the median value, and for example, the average value may be set as the threshold value TH. The method for setting the threshold value TH is not limited to these examples, and can be changed as appropriate depending on the environment of the optical transmission system 100.

[0051] When an optical signal is switched, the channel Ch that is the path of the switched optical signal and the adjacent channels Ch on both sides are subject to updating. Although not shown in Figures 5 and 7, the ranges Rb and Rc also include the waveforms of the adjacent channels Ch. Therefore, when the steady-state power value of the optical signal of one channel Ch fluctuates, the power value measured from the ranges Rb and Rc of the adjacent channels Ch also fluctuates. Therefore, the adjacent channels Ch are also subject to updating. For example, when the optical signal of channel Ch2 shown in Fig. 3 is switched, the threshold setting unit 13 updates the thresholds TH1, TH2, and TH3 of channel Ch2. The threshold setting unit 13 also updates the threshold TH3 of channel Ch1, which is adjacent to the left of channel Ch2. The threshold setting unit 13 also updates the threshold TH1 of channel Ch3, which is adjacent to the right of channel Ch2. In other words, the threshold setting unit 13 updates a total of five thresholds.

[0052] The following describes the process performed by the control unit 10 of the monitoring device 1. FIG. 9 is a diagram illustrating an example of the abnormality determination process. FIG. 10 is a flowchart showing the flow of the abnormality determination process. FIG. 9 illustrates an example in which the transponder 141 of the receiving end node 140 notifies the deterioration of the signal quality.

[0053] 10, when the transponder 141 detects deterioration in the quality of the optical signal, a notification is input to the monitoring device 1 (step S01). If the notification includes an abnormality in the transponder 141 itself (step S02: Yes), the control unit 10 determines that the abnormality in the transponder 141 exists (step S13). The abnormality in the transponder 141 is notified via the input / output unit 15. If the notification does not include any abnormality in the transponder 141 itself (step S02: No), the control unit 10 proceeds to step S03.

[0054] The data acquisition unit 11 identifies the target channel Tch, which is the path of the optical signal in which degradation has been detected (step S03). The data acquisition unit 11 acquires the power values ​​IV1, IV2, and IV3 of the target channel Tch of the i-th node (step S04). The initial value of i is set to the number of nodes n, and the i-th node is the number counted from the transmitting end node 110 side. In the example of Fig. 9, n=4. As shown in Fig. 9, the abnormality determination process is performed in reverse order of the numbers, going back from the receiving end node 140 side to the transmitting end node 110 side. In the example of Fig. 9, the abnormality determination process is performed starting from the fourth receiving end node 140. The data acquisition unit 11 controls the optical channel monitor 106 via the node controller 154 of the receiving end node 140 to acquire the power values ​​IV1, IV2, and IV3 measured in the ranges Ra, Rb, and Rc, respectively.

[0055] As shown in FIG. 10, the decision unit 12 calculates a difference D1 between the power value IV1 and the threshold value TH1, a difference D2 between the power value IV2 and the threshold value TH2, and a difference D3 between the power value IV2 and the threshold value TH3 (step S05).

[0056] If the difference D1 exceeds the predetermined value PD (step S06: Yes), the determination unit 12 determines whether a component of the i-th node other than the WSS 103 is abnormal (step S09). The determination unit 12 notifies the user of the determination result via the input / output unit 15. If the difference D1 does not exceed the predetermined value PD (step S06: No), the determination unit 12 proceeds to step S07. If at least one of the difference D2 and the difference D3 exceeds the predetermined value PD (step S07: Yes), the determination unit 12 determines that the WSS 103 of the i-th node is abnormal (step S08). The determination unit 12 notifies the user of the determination result via the input / output unit 15.

[0057] If neither the difference D2 nor the difference D3 exceeds the predetermined value PD (step S07: No), the determination unit 12 ends the abnormality determination process for the i-th node and sets "i=i-1" (step S10).

[0058] If i is not 1 (step S11: No), the determination unit 12 returns to step S04 and performs abnormality determination processing for the i-th node. That is, the determination unit 12 moves on to a node adjacent to the node on the transmitting end side of the node that has completed the abnormality determination processing, and performs the abnormality determination processing in the same manner.

[0059] If i is 1 (step S11: Yes), the determination unit 12 determines that the first node (transmitting end node 110) has an abnormality (step S12) and leaves the determination result to the user. In other words, when the abnormality determination process for node 120 is completed in step S10, it means that no abnormality has been determined in nodes 140, 130, and 120. In this case, since an abnormality has occurred in the remaining transmitting end node 110, it is possible to determine the abnormality of the transmitting end node 110 by a process of elimination without performing the abnormality determination process. The determination unit 12 can notify the user of the abnormality of the transmitting end node 110 via the input / output unit 15. Note that the abnormality determination process may also be performed on the transmitting end node 110 to determine whether the cause of the abnormality is the WSS 103 or a factor other than the WSS 103.

[0060] FIG. 11 is a flowchart showing the flow of the threshold setting process. The threshold setting unit 13 determines whether there is a change in the path of the optical signal transmitted through the optical path OP, such as an increase, decrease, or change in path (step S21). If there is a change (step S21: Yes), the threshold setting unit 13 identifies the channel to be updated (step S22). The update target channels are the channel (switching channel) that is the path of the switched optical signal and the channels adjacent to both sides of the channel. The threshold setting process can be performed in the same manner as the abnormality determination process, working backward from the receiving end node 140 side to the transmitting end node 110 side. The threshold setting unit 13 controls the optical channel monitor 106 via the node controller 154 of the i-th node to acquire the power value of the channel Ch to be updated (step S23). For the switching channel, the threshold setting unit 13 acquires power values ​​in the ranges Ra, Rb, and Rc. For the adjacent channel, the threshold setting unit 13 acquires a power value in either the range Rb or Rc that includes the waveform of the switching channel. The threshold setting unit 13 acquires each power value for a certain period of time to acquire each time series data.

[0061] The threshold setting unit 13 sets thresholds TH1, TH2, TH3 and a predetermined value PD from the time-series data of the ranges Ra, Rb, Rc (step S24). The threshold setting unit 13 stores the thresholds TH1, TH2, TH3 and the predetermined value PD in the storage unit 16 and updates them. The threshold setting unit 13 ends the threshold setting process for the i-th node and sets "i=i-1" (step S25).

[0062] If i is not 0 (step S26: No), the threshold setting unit 13 returns to step S23 and proceeds to threshold setting processing for the i-th node. That is, the process proceeds to a node adjacent to the transmitting end side of the node that has completed the threshold setting processing, and similarly performs threshold setting processing. If i is 0 (step S26: Yes), the threshold setting unit 13 ends the process because the threshold setting process for all the nodes 110, 120, 130, and 140 has been completed.

[0063] <Hardware configuration> The monitoring device 1 according to this embodiment is realized by a computer 900 as shown in FIG. 12, for example. FIG. 12 is a hardware configuration diagram showing an example of a computer 900 that realizes the functions of the monitoring device 1 according to this embodiment. The computer 900 has a CPU (Central Processing Unit) 901, a ROM (Read Only Memory) 902, a RAM (Random Access Memory) 903, a HDD (Hard Disk Drive) 904, an input / output I / F (Interface) 905, a communication I / F 906, and a media I / F 907.

[0064] The CPU 901 operates based on a program (monitoring program) stored in the ROM 902 or the HDD 904, and performs control by the control unit 10 of the monitoring device 1 shown in Fig. 4. The ROM 902 stores a boot program executed by the CPU 901 when the computer 900 is started up, programs related to the hardware of the computer 900, and the like.

[0065] The CPU 901 controls an input device 910 such as a mouse or keyboard, and an output device 911 such as a display, via an input / output I / F 905. The CPU 901 acquires data from the input device 910 via the input / output I / F 905, and outputs generated data to the output device 911. Note that a GPU (Graphics Processing Unit) or the like may be used as a processor together with the CPU 901.

[0066] The HDD 904 stores programs executed by the CPU 901, data used by the programs, etc. The communication I / F 906 receives data from other devices such as node controllers 151, 152, 153, and 154 (see FIG. 1) via a communication network (for example, NW (Network) 920) and outputs the data to the CPU 901, and also transmits data generated by the CPU 901 to other devices via the communication network.

[0067] The media I / F 907 reads a program or data stored in the recording medium 912 and outputs it to the CPU 901 via the RAM 903. The CPU 901 loads a program related to a target process from the recording medium 912 onto the RAM 903 via the media I / F 907, and executes the loaded program. The recording medium 912 is an optical recording medium such as a DVD (Digital Versatile Disc) or a PD (Phase Change Rewritable Disc), a magneto-optical recording medium such as an MO (Magneto Optical disc), a magnetic recording medium, a conductive memory tape medium, a semiconductor memory, or the like.

[0068] For example, when the computer 900 functions as the monitoring device 1 according to this embodiment, the CPU 901 of the computer 900 executes a program loaded onto the RAM 903 to realize the functions of the monitoring device 1. Furthermore, the HDD 904 stores data in the RAM 903. The CPU 901 reads and executes a program related to a target process from the recording medium 912. Alternatively, the CPU 901 may read a program related to a target process from another device via a communication network (NW 920).

[0069] <Configuration and Effects of the Above-described Embodiment> (1) The monitoring device 1 monitors transmission devices (nodes 110, 120, 130, 140) that transmit optical wavelength multiplexed signals including optical signals on a plurality of channels Ch1, Ch2, and Ch3. The monitoring device 1 includes a data acquisition unit 11 and a determination unit 12. The data acquisition unit 11 acquires a power value IV1 (first power value) of a range Ra (first range) including all wavelengths of the target channel Tch (channel) from an optical channel monitor 106 (monitor) that measures the power values ​​of optical signals output by nodes 110, 120, 130, and 140, and acquires power values ​​IV2 and IV3 (second power values) of ranges Rb and Rc (second ranges) including some of the wavelengths of the target channel Tch. The determination unit 12 compares the power values ​​IV1, IV2, and IV3 with thresholds TH1, TH2, and TH3 based on the power values ​​of the nodes 110, 120, 130, and 140 in the steady state, respectively, to determine whether the nodes 110, 120, 130, and 140 are abnormal.

[0070] According to the monitoring device 1 of this embodiment, even when using measurements acquired from the optical channel monitor 106 with low resolution, it is possible to improve the accuracy of abnormality determination in the nodes 110, 120, 130, and 140. This makes it possible to reduce installation costs compared to when a high-resolution monitor such as an OSA is provided at each node. Furthermore, since the amount of data acquired from the monitor is reduced, the communication load can be reduced.

[0071] Specifically, when a deterioration in the quality of an optical signal is detected by the transponder 141 of the receiving end node 140, the monitoring device 1 performs processing to identify the nodes 110, 120, 130, and 140 where an abnormality has occurred on the optical path OP, which is the communication path. The data acquisition unit 11 of the monitoring device 1 acquires, from the optical channel monitor 106 provided on the output side of each of the nodes 110, 120, 130, and 140, the power value of the optical signal of the target channel Tch in which an abnormality has been detected. The data acquisition unit 11 acquires a power value IV1 (first power value) in a range Ra (first range) that covers all wavelengths of the target channel Tch. The determination unit 12 compares the power value IV1 with a threshold TH1 that is set based on the power values ​​in the range Ra in a steady state. If an abnormality in the waveform of the target channel Tch causes a difference D1 between the power value IV1 and the threshold TH1 to exceed a predetermined value PD, the determination unit 12 can determine that an abnormality has occurred in the node that output the optical signal.

[0072] Here, it may not be possible to determine whether the filter function of the WSS 103 of the nodes 110, 120, 130, and 140 is abnormal simply by comparing the power value IV1 with the threshold value TH1. The node controllers 151, 152, 153, and 154 perform power control to compensate for waveform loss caused by filtering in the WSS 103. This also applies when loss occurs due to an abnormality in the filter function of the WSS 103. Therefore, the waveform caused by the filter abnormality of the WSS 103 may have the same power across the entire wavelength as the waveform in the steady state. In this case, the difference D1 between the power value IV1 acquired from the range Ra covering the entire wavelength and the threshold value TH1 may not be large enough to exceed the predetermined value PD. In this case, it is not possible to determine whether the nodes 110, 120, 130, and 140 are abnormal.

[0073] In this embodiment, the data acquiring unit 11 acquires, in addition to the power value IV1, power values ​​IV2 and IV3 (second power values) in ranges Rb and Rc (second ranges) that include part of the wavelength of the target channel Tch. The determining unit 12 also compares the power values ​​IV2 and IV3 with threshold values ​​TH2 and TH3 that are set based on the ranges Rb and Rc in the steady state, respectively. By setting ranges Rb and Rc that include part of the wavelength, it becomes easier to include areas where there is a large difference between the waveform where an abnormality occurs and the waveform in the steady state. Furthermore, because ranges Rb and Rc do not cover the entire wavelength, the possibility that the power values ​​within the ranges will end up being the same as in the steady state is lower than in range Ra. Therefore, it is possible to increase the possibility that the differences D2 and D3 between the power values ​​IV2 and IV3 in ranges Rb and Rc and the threshold values ​​TH2 and TH3 exceed the predetermined value PD, thereby determining an abnormality.

[0074] (2) Nodes 110, 120, 130, and 140 are equipped with WSS103 (wavelength selective switch) that multiplexes optical signals of multiple channels Ch1, Ch2, and Ch3 to generate an optical wavelength multiplexed signal and filters the optical signal according to the wavelength band BW assigned to each channel Ch1, Ch2, and Ch3. The determination unit 12 of the monitoring device 1 determines whether there is an abnormality in the components (elements) other than the WSS 103 in the nodes 110, 120, 130, and 140 based on a comparison between the power value IV1 and the threshold value TH1. The determination unit 12 determines whether there is an abnormality in the WSS 103 based on a comparison between the power values ​​IV2 and IV3 and the threshold values ​​TH2 and TH3.

[0075] If an abnormality is determined based on the power value IV1, it is highly likely that a component other than the WSS 103 is the cause, and if an abnormality is determined based on the power values ​​IV2 and IV3, it is highly likely that the cause is the WSS 103. By having the data acquisition unit 11 acquire multiple power values ​​IV1, IV2, and IV3 from different ranges Ra, Rb, and Rc, the determination unit 12 can also isolate the cause of the abnormality within the nodes 110, 120, 130, and 140. This can improve the usability of the monitoring device 1.

[0076] (3) The data acquisition unit 11 of the monitoring device 1 sets two ranges Rb and Rc that include part of the wavelength of the target channel Tch (channel) and are shifted from each other as second ranges, and acquires the power values ​​IV2 and IV3 in the ranges Rb and Rc, respectively, as second power values.

[0077] If only the power value IV2 in the range Rb is acquired as the second power value, waveform loss within the range Rb may be compensated for by power control, resulting in the power being the same as that in the steady state. In this case, the difference D2 between the power value IV2 and the threshold value TH2 does not exceed the predetermined value PD, and it may be impossible to determine whether the nodes 110, 120, 130, and 140 are abnormal. The data acquisition unit 11 sets two ranges Rb and Rc, which are offset from each other, as the second range, and acquires the power values ​​IV2 and IV3 from each of the ranges as the second power value. Setting multiple ranges covers a wide range of the channel Ch, increasing the likelihood of capturing a point in either the range Rb or Rc where the power difference from the steady state is large. The determination unit 12 can determine whether the nodes 110, 120, 130, and 140 are abnormal if at least one of the power values ​​IV2 and IV3 exceeds the threshold values ​​TH2 and TH3, thereby improving the accuracy of abnormality determination. The number of ranges set as the second ranges is not limited to two, but three or more ranges may be set and the power value of each range may be acquired as the second power value.

[0078] (4) The monitoring device 1 includes a threshold setting unit 13 that sets the thresholds TH1, TH2, and TH3. When an optical signal is switched, the threshold setting unit 13 acquires from the optical channel monitor 106 the power values ​​of the channel along the path of the switched optical signal and the adjacent channels, and sets thresholds TH1, TH2, and TH3.

[0079] When an optical signal is switched in the optical transmission system 100, fluctuations occur in the steady-state power values ​​of the channels along which the switched optical signal is routed. The threshold setting unit 13 updates the thresholds TH1, TH2, and TH3 at the timing of switching, so that the thresholds TH1, TH2, and TH3 reflect the steady-state power values, thereby improving the accuracy of determining abnormalities in the nodes 110, 120, 130, and 140.

[0080] The above-mentioned effects can also be applied to the monitoring method performed by the monitoring device 1 and the monitoring program for causing the computer 900 to function as the monitoring device 1.

[0081] <Variation 1> A first modification of this embodiment will be described with reference to the drawings. Detailed description of the configuration and processing of Modification 1 that are the same as those of this embodiment will be omitted. FIG. 13 is a diagram illustrating the range in which the power value is acquired in the first modification. FIG. 14 is a diagram illustrating a comparative example. In the above-described embodiment, an example was described in which a malfunction in the filter function of the WSS 103 causes distortion in the waveform of a specific channel (see FIG. 6), but a malfunction in the filter function can affect the waveforms of all channels Ch1, Ch2, and Ch3, as shown in FIG. 13. Modification 1 modifies the processing of the above-described embodiment to make it possible to determine whether an abnormality exists in the nodes 110, 120, 130, and 140 even when an abnormality occurs in the waveforms of all channels Ch1, Ch2, and Ch3.

[0082] Figure 13 shows an example in which an abnormality called filter tightening has occurred in the waveforms of all channels Ch1, Ch2, and Ch3. In Figure 13, the steady-state waveform is shown by the dotted line, and the filter-tightening waveform is shown by the solid line. Compared to the steady-state waveform, the filter-tightening waveform has a reduced power in the edge component C1 and an increased power in the center component C2.

[0083] The configuration of the control unit 10 of the monitoring device 1 in the first modification is the same as that in FIG. 4, and therefore will be described with reference to FIG. As in the embodiment, the control unit 10 performs the abnormality determination process when a notification that degradation of the optical signal has been detected is input from the transponders 111 and 141. The data acquisition unit 11 identifies the target channel Tch, which is the path of the optical signal in which degradation has been detected, and when all of the channels Ch1, Ch2, and Ch3 have been identified as the target channels Tch, the data acquisition unit 11 performs the abnormality determination process of Modification 1. The data acquisition unit 11 selects a terminal channel from among all channels Ch1, Ch2, and Ch3. A terminal channel is a channel that is not adjacent to any other channel at either end of the waveform. In the example of FIG. 13, channel Ch3 is selected as the terminal channel. Channel Ch3 is adjacent to channel Ch2 at the left end, but is not adjacent to any other channel at the right end. The data acquiring unit 11 may select channel Ch1 as the terminal channel. Channel Ch1 is adjacent to channel Ch2 at the right end, but is not adjacent to any other channel at the left end.

[0084] As in the embodiment, the data acquiring unit 11 acquires a power value IV1 in the range Ra that includes all wavelengths of the optical signal of channel Ch3. In Modification 1, the data acquiring unit 11 acquires power values ​​IV2' in a range Rb' including the right end of the wavelength of channel Ch3, which is not adjacent to any other channel. The range Rb' does not cover the entire wavelength, but includes only a portion of the wavelength. When the channel Ch1 is the terminal channel, the data acquiring unit 11 acquires the power value IV2' from a range Rb' including the left end of the channel Ch1 that is not adjacent to any other channel.

[0085] FIG. 14 shows, as a comparative example, a case in which ranges Ra and Rb are set for channel Ch2 adjacent to channels Ch1 and Ch3 at both ends, in the same way as in the embodiment. As described above, the node controllers 151, 152, 153, and 154 perform power control to compensate for losses caused by an abnormality in the filter function of the WSS 103. Therefore, as shown in Fig. 14, in the filter tightening waveform, the component C1 at the edge has less power than in the steady state, while the component C2 in the center has more power than in the steady state. In other words, even in the case of filter tightening, the difference D1 between the power value IV1 of the range Ra and the threshold TH1 does not become large, and it is possible that an abnormality in the nodes 110, 120, 130, and 140 will not be detected.

[0086] 14, if a range Rb is set for channel Ch2, the range Rb will also include the waveform of adjacent channel Ch3. Range Rb includes edge components C1 where the power of channels Ch2 and Ch3 has decreased, as well as a central component C2 where the power of channel Ch3 has increased. If the power increase and decrease within range Rb are close to each other, the difference D2 between the power value IV2 of range Rb and the threshold value TH2 may not exceed the predetermined value PD, and an abnormality may not be detected in nodes 110, 120, 130, and 140.

[0087] As shown in FIG. 13, in Modification 1, the data acquisition unit 11 sets ranges Ra and Rb' for the termination channel Ch3. Furthermore, the data acquisition unit 11 sets range Rb' so that it includes the right edge of the termination channel Ch3, where no other channels are adjacent. This ensures that range Rb' does not include the waveforms of adjacent channels. In other words, the power decrease due to component C1 at the edge of channel Ch3 is not offset by the increase in component C2 at the center of the adjacent channel. Therefore, the power value IV2' of range Rb' is reduced by the component C1 at the edge, and the difference D2' from threshold TH2' is more likely to exceed the predetermined value PD. This improves the accuracy of determining abnormalities in nodes 110, 120, 130, and 140. The threshold value TH2' can be set by performing the same processing as the threshold value setting processing of the embodiment when the optical signal of the termination channel Ch3 is switched.

[0088] FIG. 15 is a flowchart showing the flow of the abnormality determination process according to the first modification. Here, an example will be described in which the transponder 141 of the receiving end node 140 notifies the deterioration of the signal quality. 15, when the transponder 141 detects deterioration in the quality of the optical signal, a notification is input to the monitoring device 1 (step S101). If the notification includes an abnormality in the transponder 141 itself (step S102: Yes), the control unit 10 determines that the transponder 141 is abnormal (step S114) and notifies the abnormality of the transponder 141 via the input / output unit 15. If the notification does not include any abnormality in the transponder 141 itself (step S102: No), the control unit 10 proceeds to step S103.

[0089] The data acquiring unit 11 identifies the target channel Tch, which is the path of the optical signal in which the degradation is detected (step S103). If the target channels Tch are not all of the channels Ch1, Ch2, and Ch3 (step S104: No), the data acquiring unit 11 proceeds to the process of step S04 in FIG. 10 and performs the same abnormality determination process as in the embodiment.

[0090] If the target channels Tch are all channels Ch1, Ch2, and Ch3 (step S104: Yes), the data acquisition unit 11 selects the terminating channel Ch3. The data acquisition unit 11 acquires power values ​​IV1 and IV2' from the ranges Ra and Rb' of the terminating channel Ch3 of the i-th node (step S105).

[0091] As shown in FIG. 15, the decision unit 12 calculates a difference D1 between the power value IV1 and the threshold value TH1, and a difference D2' between the power value IV2' and the threshold value TH2' (step S106).

[0092] If the difference D1 exceeds the predetermined value PD (step S107: Yes), the determination unit 12 determines that an abnormality has occurred in a component of the node other than the WSS 103 (step S110). The determination unit 12 notifies the user of the determination result via the input / output unit 15. If the difference D1 does not exceed the predetermined value PD (step S107: No), the determination unit 12 proceeds to step S108. If the difference D2' exceeds the predetermined value PD (step S108: Yes), the determination unit 12 determines that the WSS 103 of the node is abnormal (step S109). The determination unit 12 notifies the user of the determination result via the input / output unit 15.

[0093] If the difference D2' does not exceed the predetermined value PD (step S108: No), the determination unit 12 ends the abnormality determination process for the i-th node and sets "i=i-1" (step S111).

[0094] If i is not 1 (step S112: No), the determination unit 12 returns to step S105 and performs abnormality determination processing for the i-th node. If i is 1 (step S112: Yes), the determination unit 12 determines that an abnormality has occurred in the transmitting end node 110, which is the first node (step S113).

[0095] <Configuration of Modification 1 and its Effects> (5) In variant example 1, the data acquisition unit 11 of the monitoring device 1 sets the range Rb' including the end of the wavelength of the termination channel Ch3 where no other channels are adjacent as the second range, and acquires the power value IV2' (second power value).

[0096] If filter tightening occurs in the wavelengths of all channels Ch1, Ch2, and Ch3, the range Rb, which is set to include a portion of the channel Ch, may include the wavelengths of adjacent channels Ch. Because filter tightening also occurs in the wavelengths of adjacent channels Ch, the difference D2 between the power value IV2 in the range Rb and the threshold value TH2 may not exceed the predetermined value PD, making it impossible to determine an abnormality in the nodes 110, 120, 130, and 140. In Variation 2, the range Rb' is set to include the ends of the terminal channels Ch1 and Ch3 where no other channels are adjacent. This prevents the power value IV2' in the range Rb' from being affected by adjacent channels. This increases the likelihood that the difference D2' between the power value IV2' and the threshold value TH2' will exceed the predetermined value PD when filter tightening occurs, thereby improving the accuracy of determining an abnormality in the nodes 110, 120, 130, and 140.

[0097] 15, when the target channels Tch are all channels Ch1, Ch2, and Ch3 (step S104: YES), an example has been described in which two power values ​​IV1 and IV2' are acquired from the termination channel Ch3 to perform the abnormality determination process. In the example of Fig. 15, since it is sufficient to acquire power values ​​at two points, the amount of data processing during the abnormality determination process can be reduced. Note that the present invention is not limited to the example of FIG. 15. Even when the target channels are all channels Ch1, Ch2, and Ch3, the process may proceed to step S04 of FIG. 10, and power values ​​IV1, IV2, and IV3 may be acquired from ranges Ra, Rb, and Rc for each channel in sequence, and anomaly determination processing may be performed. In this case, range Rb is set to include the ends of the channels. This results in acquisition of power value IV2 from range Rb in the terminal channel, resulting in acquisition of IV2' in range Rb', making it possible to determine whether a node is abnormal due to filter tightening. The determination unit 12 can terminate the anomaly determination processing when an abnormality is determined in any channel.

[0098] <Variation 2> FIG. 16 is a diagram illustrating the range in which the power value is acquired in the second modification. In the first modification, when filter tightening occurs, a range Rb' is set for the channel Ch3, which is the terminal channel, so that the waveforms of adjacent channels are not included. In Modification 2, when filter tightening occurs, the range Rb'' is set so that an abnormality can be detected even in a channel that has adjacent channels on both sides. FIG. 16 shows an example in which the range Rb'' is set for the channel Ch2. Specifically, the data acquiring unit 11 sets a range Rb'' that has a width different from the range Ra that covers all wavelengths and that includes the end of the wavelength of channel Ch2. The data acquiring unit 11 acquires a power value IV2'' of the range Rb'' from the optical channel monitor 106. In FIG. 16, the range Rb'' is set to include the right end, but it may also be set to include the left end. As in the embodiment, the determination unit 12 calculates a difference D2'' between the power value IV2'' in the range Rb'' and the threshold value TH2''. If the difference D2'' exceeds the predetermined value PD, the determination unit 12 determines that the node is abnormal. The threshold value TH2'' can be set by performing the same processing as the threshold value setting processing in the embodiment.

[0099] As shown in the diagram indicated by reference numeral 161 in FIG. 16, the width of range Rb'' may be narrower than range Ra. As a result, range Rb'' does not include central component C2, which is an increase in power of adjacent channel Ch3. As a result, the decrease in power due to component C1 at the ends of channels Ch2 and Ch3 is not offset by the increase due to central component C2, and therefore power value IV2'' in range Rb'' becomes smaller. As a result, difference D2'' between power value IV2'' and threshold value TH2'' becomes larger, making it easier to determine an abnormality.

[0100] As shown in the diagram indicated by reference numeral 162 in FIG. 16, the width of range Rb'' may be wider than range Ra. By widening range Rb'', the proportion of center component C2 of channel Ch3 included in range Rb'' increases. When the increase in power due to center component C2 in range Rb'' exceeds the decrease in power due to edge component C1, the power value IV2'' of range Rb'' becomes larger. This increases the difference D2'' between power value IV2'' and threshold value TH2'', making it easier to determine an abnormality.

[0101] The data acquisition unit 11 changes the width of the range Ra and the range Rb'' by changing the resolution setting of the optical channel monitor 106 via the node controllers 151, 152, 153, and 154. By setting the resolution of the optical channel monitor 106 at a finer setting, the width of the range Rb'' can be narrowed, as shown in the diagram of reference numeral 161 in FIG. 16. By setting the resolution of the optical channel monitor 106 at a coarser setting, the width of the range Rb'' can be widened, as shown in the diagram of reference numeral 162 in FIG. 16.

[0102] <Configuration of Modification 2 and its Effects> (6) The data acquisition unit 11 of the monitoring device 1 sets a range Rb'' as a second range, which has a width different from the range Ra (first range) and includes the end of the wavelength of the channel, and acquires a power value IV2'' (second power value).

[0103] By setting a range Rb'' with a different width from the range Ra that covers the entire wavelength range, it is possible to vary the ratio of the component whose power decreases (component C1) to the component whose power increases (component C2) contained within range Rb''. This increases the difference D2'' between the power value IV2'' and the threshold value TH2'', improving the accuracy of determining whether a node is abnormal. According to the second modification, it is possible to determine abnormalities in nodes not only in the terminal channel but also in channels Ch that have adjacent channels on both ends, thereby improving the convenience of the monitoring device 1.

[0104] The processing of Modification 2 can be performed when the target channels Tch are all channels Ch1, Ch2, and Ch3 (step S104: Yes), similarly to the processing shown in FIG. 15 in Modification 1. In this case, the data acquiring unit 11 can select any channel from all channels Ch1, Ch2, and Ch3, acquire power values ​​IV1 and IV2" at two points in ranges Ra and Rb" and perform abnormality determination processing. In this case, similarly to Modification 1, since it is only necessary to acquire power values ​​at two points, the amount of data processing in the monitoring device 1 can be reduced. Note that the data acquiring unit 11 may acquire both power values ​​with a wide width and power values ​​with a narrow width in range Rb".

[0105] Furthermore, without being limited to the example of FIG. 15, even when the target channels are not all channels Ch1, Ch2, and Ch3, the process may proceed to step S04 of FIG. 10 and perform the abnormality determination process for each channel in sequence. In this case, for each channel, in addition to obtaining power values ​​IV1, IV2, and IV3 from ranges Ra, Rb, and Rc, the power value IV2" from range Rb" is also obtained. The determination unit 12 can end the abnormality determination process when an abnormality is determined in any channel.

[0106] <Variation 3> FIG. 17 is a functional block diagram showing the configuration of a monitoring device 1A according to the third modification. As shown in FIG. 17, a monitoring device 1A according to the third modification includes a threshold correction unit 14 in addition to the configuration described in the embodiment. In the third modification, the data acquiring unit 11 acquires power values ​​IV1, IV2, and IV3 from each of the ranges Ra, Rb, and Rc in the target channel Tch of each node, as in the embodiment. At that time, the data acquiring unit 11 causes the optical channel monitor 106 to measure only the power value IV1 in the range Ra for a predetermined time T, and acquires data on the power value IV1 for the predetermined time T. The threshold setting unit 13 determines whether there is a fluctuation in the power value IV1 from the data for a predetermined time period T acquired by the data acquisition unit 11. If there is a fluctuation in the power value IV1, the threshold setting unit 13 determines an offset value based on the amount of the fluctuation. The threshold setting unit 13 corrects the thresholds TH1, TH2, and TH3 by adding the determined offset value to each of the thresholds TH1, TH2, and TH3. The determination unit 12 performs the abnormality determination process in the same manner as in the embodiment by comparing the power values ​​IV1, IV2, and IV3 with the corrected threshold values ​​TH1, TH2, and TH3.

[0107] Normally, if the grid width is not changed, the WSS 103 outputs a constant power value IV1, but the power value IV1 may fluctuate due to factors such as severe environmental conditions. The threshold setting unit 13 determines an offset value based on the amount of fluctuation in the power value IV1 and corrects the thresholds TH1, TH2, and TH3, thereby enabling abnormality determination processing to be performed according to the environmental conditions.

[0108] FIG. 18 is a flowchart showing the flow of the threshold correction process according to the third modification. The processing in steps S201 to S203 in FIG. 18 is the same as the processing in steps S01 to S03 in FIG. 10, and therefore a description thereof will be omitted. In step S204, the data acquisition unit 11 acquires power values ​​IV1, IV2, and IV3 from the ranges Ra, Rb, and Rc for the target channel Tch of the i-th node. The data acquisition unit 11 acquires data for the power value IV1 over a predetermined time period T.

[0109] The threshold correction unit 14 refers to the data of the power value IV1 for a predetermined time T and determines whether there is a fluctuation in the power value IV1 (step S205). If there is no fluctuation in the power value IV1 (step S205: No), the threshold correction unit 14 inputs the thresholds TH1, TH2, and TH3 to the determination unit 12 without correcting them. If there is a fluctuation in the power value IV1 (step S205: Yes), the threshold correction unit 14 determines an offset value from the amount of fluctuation and corrects the thresholds TH1, TH2, and TH3 by adding the offset value (step S206). The threshold correction unit 14 inputs the corrected thresholds TH1, TH2, and TH3 to the determination unit 12. The decision unit 12 calculates the differences D1, D2, and D3 between the power values ​​IV1, IV2, and IV3 and the threshold values ​​TH1, TH2, and TH3 input from the threshold correction unit 14, respectively (step S207). The processing in steps S208 to S215 is the same as the processing in steps S06 to S13 in FIG. 10, and therefore a description thereof will be omitted.

[0110] <Configuration of Modification 3 and its Effects> (7) The monitoring device 1A includes a threshold correction unit 14 that corrects the thresholds TH1, TH2, and TH3 based on the amount of fluctuation in the power value IV1 (first power value) at the predetermined time T acquired by the data acquisition unit 11. This makes it possible to improve the accuracy of node abnormality determination even in environmental conditions where the power values ​​IV1, IV2, and IV3 fluctuate.

[0111] In the above-described embodiment and modified example, an example has been described in which the monitoring device is applied to a network controller that manages the entire optical transmission system 100, but the present invention is not limited to this. The monitoring device may also be applied to the node controllers 151 to 154 that control the respective nodes 110 to 140. Alternatively, part of the functional configuration of the monitoring device 1 may be realized by the node controllers 151, 152, 153, and 154. For example, the threshold setting may be performed by the network controller, and the abnormality determination process may be performed by each of the node controllers 151, 152, 153, and 154.

[0112] The present invention is not limited to the above-described embodiments, and many modifications can be made by a person skilled in the art within the technical concept of the present invention. [Explanation of symbols]

[0113] 1 Monitoring device 11 Data Acquisition Section 12 Judgment section 13 Threshold setting section 14 Threshold correction unit 15 Input / output section 16 Memory section 110, 120, 130, 140 nodes (transmission equipment, OXC) 103 Wavelength Selective Switch (WSS) 106 Optical Channel Monitor (Monitor) Ra range (first range) Rb, Rb', Rb'', Rc range (second range) IV1 power value (first power value) IV2, IV2', IV2'', IV3 power value (second power value)

Claims

1. A monitoring device for a transmission device that transmits an optical wavelength multiplexed signal including optical signals of a plurality of channels, a data acquisition unit that acquires, from a monitor that measures a power value of the optical signal output from the transmission device, a first power value in a first range that includes all wavelengths of the channel and a second power value in a second range that includes only a portion of the wavelengths of the channel; a determination unit that compares the first power value and the second power value with thresholds based on power values ​​of the transmission device in a steady state, and determines an abnormality in the transmission device.

2. the transmission device includes a wavelength selective switch that multiplexes the optical signals of the plurality of channels to generate the optical wavelength multiplexed signal, and filters the optical signals in accordance with wavelength bands assigned to each channel; 2. The monitoring device according to claim 1, wherein the determination unit determines an abnormality in an element other than the wavelength selective switch in the transmission device based on a comparison between the first power value and the threshold value, and determines an abnormality in the wavelength selective switch based on a comparison between the second power value and the threshold value.

3. The monitoring device according to claim 1 or 2, characterized in that the data acquisition unit sets two ranges as the second ranges, each of which includes only a portion of the wavelength of the channel and is shifted from the other, and acquires the power values ​​in each of the two ranges as the second power values.

4. The data acquisition unit 3. The monitoring device according to claim 1, wherein the second power value is acquired by setting a range including an end of the wavelength of the channel where no other channel is adjacent as the second range.

5. The data acquisition unit 3. The monitoring device according to claim 1, wherein the second power value is acquired by setting the second range to a range having a width different from that of the first range and including an end of the wavelength of the channel.

6. a threshold setting unit that sets the threshold, The monitoring device according to claim 2, characterized in that, when the optical signal is switched, the threshold setting unit acquires from the monitor the power values ​​of the channel that is the path of the switched optical signal and the adjacent channel, and sets the threshold.

7. A monitoring method for a transmission device that transmits an optical wavelength multiplexed signal including optical signals of a plurality of channels, comprising: acquiring a first power value in a first range including all wavelengths of the channel and a second power value in a second range including only a portion of the wavelengths of the channel from a monitor that measures a power value of the optical signal output by the transmission device; and comparing the first power value and the second power value with thresholds based on power values ​​of the transmission device in a steady state to determine whether an abnormality exists in the transmission device.

8. A monitoring program for causing a computer to function as the monitoring device according to any one of claims 1 to 6.

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