JP3954072B2 - Optical level control method, optical level control apparatus, and wavelength division multiplexing optical network - Google Patents

Abstract

An optical level controller comprising variable optical attenuators for attenuating optical input signals of the wavelengths of a wavelength multiplex signal by variable attenuations and control units for automatically controlling the attenuations so that the optical output level of each variable optical attenuator may be a target level while the optical input signal is in a normal state, further comprising sensing units for detecting light beam cut-off and cut-off cancel of the optical input signal of each variable optical attenuator, wherein the control unit adjusts the attenuation to a first predetermined value when the sensing unit detects cut-off, and to a second predetermined value when the sensing unit detects cut-off cancel, and changes its control to automatic control.

Description

  The present invention relates to an optical level control device that performs level control of an optical signal so as to shorten the time required to return to the original normal level at the time of switching or recovery from a fault, and wavelength division multiplexing that includes a plurality of node devices having the optical level control device It relates to optical networks.

  Traffic is increasing with the increase in users such as the Internet and mobile phones, and services are diversifying from e-commerce, e-mail to video distribution, and broadband has become mainstream, and communication capacity has increased dramatically. is doing. Therefore, a large-capacity network is indispensable, and the introduction of an optical communication network is being promoted. Particularly, a wavelength division multiplexing network (WDM communication network) using WDM (Wavelength Division Multiplexing) technology has been rapidly constructed. . In addition, while increasing capacity, competition among carriers has intensified, and costs have become more severe than ever. Optical nodes that can handle wavelengths at the optical level (OADM (Optical Add Drop Multiplexing) and OXC (Optical) Cross Connect) has become an important technology. Among them, due to the characteristics of the fiber, the optical amplifier, and other optical components, the optical power level varies among the wavelength-multiplexed optical signals, and the transmission quality is deteriorated. In particular, when an optical node in which various optical components are combined is used, the variation becomes large, and thus a function for adjusting the optical level is required. An optical attenuator is introduced in order to adjust the light level, but it takes time until the original normal level is restored by the operation of the optical attenuator at the time of switching or restoration of a failure.

  FIG. 87 is a diagram showing a configuration example of an optical node having an optical signal level control function. The input wavelength multiplexed signals of wavelengths λ1 to λn are demultiplexed for each wavelength by a demultiplexer (WDMUX) 2 # i, and output to SW4 # i. When the own node is an Add node, a transponder (TRPN) transmitter 6 # i that is duplexed by a 0-system and a 1-system transmitters 6 # i0 and 6 # i1 is provided. TRPN6 # i is protected on the active side (work (W)), for example, the 0-system transmitter 6 # i0, and on the other side is the protection system (protection (P)), for example, the 1-system transmitter 6 # i1 is protected. It is said. The 0-system and 1-system transmitters 6 # i0 and 6 # i1 output subscriber optical signals from subscribers to the SW8 # i. SW8 # i selects the output optical signal of the current 0-system transmitter 6 # 0 and outputs it to SW4 # i. When a failure occurs in the active system of TRPN6 # i, the system is switched to the standby system.

  The SW4 # i receives the optical signal of each wavelength input from the duplexer 2 # i and SW8 # i as a transponder (TRNP) receiver 10 # i or a splitter (splitter: SPL) 12 # ij (j = 1, 2, ...). If the own node is a drop node, the optical signal is received by TRPN10 # i and transmitted to the subscriber side.

  The SPL 12 # ij branches the optical signal into two and outputs the optical signal to a variable optical attenuator (VOA (Variable Optical Attenuator)) 14 # ij and a monitor PD 16 # ij. The SPL 18 # ij is connected to the output side of the VOA 14 # ij. The SPL 18 # ij branches the output optical signal of the VOA 14 # ij into two and outputs it to the multiplexer (WMUX) 20 # i and the monitor PD 22 # ij. The monitor PDs 16 # ij and 22 # ij detect the light level and output a light level detection signal. The control circuit 24 # ij controls the VOA 14 # ij so that the level of the output optical signal of the VOA 14 # ij becomes the target level based on the optical level detection signals of the monitor PD 16 # ij and the monitor PD 22 # ij. The VOA 14 # ij attenuates the optical signal from the SPL 12 # ij by the attenuation controlled by the control circuit 24 # ij, and outputs the optical signal to the SPL 14 # ij. The WMUX 20 # i wavelength-multiplexes the optical signals having the wavelengths λ1 to λn and outputs them to the optical fiber.

  FIG. 88 is a diagram showing a normal time. Assume that node 30 # 1 is an Add node, nodes 30 # 2 and 30 # 3 are through nodes, and node 30 # 4 is Drop. In a state where no failure has occurred in the TRPN6 # i0 of the node 30 # 1, as shown in FIG. 88, the optical signal added at the node 30 # 1 goes to the target level at the VOA 14 # 11 via the SW4 # 1. Attenuated, attenuated to the target level by VOAs 14 # 21 and 14 # 31 via SW4 # 2 and 4 # 3 of nodes 30 # 2 and 30 # 3, and via SW4 # 4 of node 30 # 4 , Dropped by TRPN10 # 4 and transmitted to the subscriber side.

  FIG. 89 is a diagram showing when a failure occurs. When a failure occurs in the TRNP6 # 10 of the node 30 # 1 and the light is interrupted, the light is interrupted from the node 30 # 2 to the node 30 # 4. As a result, the attenuation amounts (ATT) of the VOAs 14 # 11, 14 # 21, and 14 # 31 become zero, and the VOAs 14 # 11, 14 # 21, and 14 # 31 are fully opened. After that, when SW8 # 1 is switched to the standby system, VOAs 14 # 11, 14 # 21, and 14 # 31 are fully opened, and TRNP10 # 4 at the receiving end enters more light than usual, and TRNP10 # 4 is destroyed. May occur. Further, in the case of a WDM signal, the optical signal level of a channel (ch) related to a failure becomes higher than usual at the time of restoration, and therefore it may affect other channels.

  Also, if the ATT amount of the VOA is increased due to optical signal interruption and the VOA is closed, there will be no significant level difference between normal and failure recovery, but after failure recovery, the VOA will be level adjusted in order from the node 30 # 1 To start.

  Prior art documents include the following.

Patent Document 1 detects that an optical signal is interrupted, increases the attenuation of the variable optical attenuator when the optical signal is interrupted, and decreases the attenuation of the variable optical attenuator when the input optical signal is restored. Disclosure.
Japanese Patent Laid-Open No. 11-112435

  However, there have been the following problems in the past.

  Since the variable optical attenuator starts up in order from node 1, if the preceding node does not properly output the optical signal at the target level, the attenuation of the next node cannot be controlled properly. Therefore, it takes time in proportion to the number of nodes until the variable optical attenuators of all the nodes on the network are appropriately controlled. In addition, it is difficult to control the variable optical attenuator stably at each node and shorten the rise time. For this reason, there is a problem that the recovery time becomes very long at the time of failure.

  Also, if the optical signal temporarily returns to the momentary interruption while the optical signal is in communication, according to the constant output control of the variable optical attenuator, the variable optical attenuation can be adjusted to adjust the amount of decrease in the optical level. In the worst case, the attenuation amount of the variable optical attenuator becomes the minimum attenuation amount. Then, since the amount of attenuation is smaller than usual due to an operation delay or the like when returning from a momentary interruption, the optical level of the optical signal output from the variable optical attenuator increases, and an optical surge is induced. For this reason, it takes time to return to the target level. Similarly, when the variable optical attenuator has a function of shutting down (closing) when the optical signal is interrupted, the attenuation must be adjusted from the maximum (closed) state to the target level. There was a problem that it took time like the recovery operation.

  Further, in Patent Document 1, since the attenuation is increased when the optical signal is interrupted, it takes time for the output optical signal of the variable optical attenuator to return to a certain level when the optical interrupt is restored. There was a point.

  The object of the present invention is to reduce the recovery time from a failure, to prevent the optical server from being triggered by an instantaneous interruption of an optical signal, and to reduce the recovery time at the time of releasing the instantaneous interruption. A control method, an apparatus thereof, and a wavelength division multiplexing optical network are provided.

According to an aspect of the present invention, there is provided an optical level control method in which an input optical signal is level-adjusted with a variable optical attenuator and controlled so that an output level of the variable optical attenuator becomes a constant value. When a signal interruption is detected from a decrease in the input signal light level of the optical attenuator, and the signal interruption is detected, the attenuation amount of the variable optical attenuator is set to a preset fixed value, and a predetermined value is detected from the detection of the signal interruption. An optical level control method is provided in which the output level of the variable optical attenuator is controlled to become a constant value after a lapse of time.

  According to another aspect of the present invention, a variable optical attenuator for attenuating an optical input signal of each wavelength of a wavelength multiplexed signal with a variable attenuation amount and light of the variable optical attenuator in a normal state where the optical input signal is normal. An optical level control device having a control unit that automatically controls the amount of attenuation so that an output level becomes a target level, comprising a detection unit that detects disconnection and release of an optical input signal of the variable optical attenuator. The control unit controls the fixed amount of attenuation with the amount of attenuation immediately after the light break when the detection unit detects the light break, and transitions to the automatic control when the detection unit detects the light break release. A light level control device is provided.

  According to still another aspect of the present invention, a variable optical attenuator for attenuating an optical input signal of each wavelength of a wavelength multiplexed signal with a variable attenuation amount and the variable optical attenuator in a normal state in which the optical input signal is normal. A control unit that automatically controls the attenuation amount so that the optical output level becomes a target level, wherein the control unit is configured to release the optical input signal after the optical input signal is interrupted. There is provided an optical level control device characterized by performing automatic control in a long cycle so that the attenuation amount does not become a predetermined value or less within a time predicted to be required.

  According to the present invention, it is possible to reduce the time for the VOA output level to return to the original normal level after the light break is released, and the attenuation at the time when the light break is released does not become below a certain level. At this point, the VOA output level will not become too high.

  Before describing the embodiment of the present invention, the principle of the present invention will be described. FIG. 1A is a principle diagram of the present invention. FIG. 2 is a diagram showing the amount of optical attenuator ATT. FIG. 3 is a diagram showing the VOA output level. As shown in FIG. 1, the light level control device includes a detection unit 50, a VOA 52, and a control unit 54. The VOA 52 attenuates the input optical signal by the amount of ATT controlled by the control unit 54. The detection unit 50 detects the light interruption of the optical signal and the release from the light interruption based on the optical level of the input optical signal of the VOA 52. When the light detection unit 50 has not detected a light break, the control unit 54 performs automatic level adjustment control so that the output light level of the VOA 52 becomes the target level as shown in FIGS. When the light detection unit 50 detects a light break, the control unit 54 transitions to ATT fixing control 1 for setting the ATT amount to a fixed value other than zero, as shown in FIGS. In this way, when the light is interrupted, the ATT amount is not a non-zero value but a fixed value, so that when the light is restored, the light level is too high and no problem occurs. Further, when the detection unit 50 detects the cancellation of the light break, the control unit 54 sets the ATT amount to a fixed value close to the average ATT amount at the normal level, as shown in FIGS. 2 and 3. After the transition, automatic level adjustment is performed. As described above, when the light break is canceled, the transition to the ATT amount fixing control 2 and then the automatic level adjustment is performed, so that the convergence to the target level becomes faster.

  FIG. 1B is another principle diagram of the present invention. As shown in FIG. 1B, the detection unit 54 may have detection points for light breakage and light break release before and after the VOA 52, or may have points only behind the VOA 52.

First Embodiment FIG. 4 is a diagram showing a node device according to the first embodiment of the present invention, are denoted by the same reference numerals to components substantially the same elements in FIG. 86. This node device has an add-drop function. In FIG. 4, an input WDM signal is demultiplexed for each wavelength by a demultiplexer (WDMUX) 2 # i. Each wavelength λ1 to λn is supplied to a variable optical attenuator (VOA) 14 # ij (j = 1, 2,..., N) through an optical switch (SW) 4 # i for each wavelength. The output of the variable optical attenuator 14 # ij is supplied to the multiplexer (WMUX) 20 # i through the branching unit 18 # ij.

  The optical signal of each wavelength branched by the branching device 18 # ij is detected by the monitor PD 22 # ij and supplied to the control circuit 60 # ij. The control circuit 60 # ij performs optical variable attenuation control processing, which will be described later, and performs feedback control that varies the attenuation amount of the variable optical attenuator 14 # ij in accordance with the optical level output from the variable optical attenuator 14 # ij. The level of the optical signal output from the variable optical attenuator 14 # ij is adjusted to a constant value.

  FIG. 5 is a flowchart of the first embodiment of the optical variable attenuation control process executed by the control circuit 60 # ij. This process is repeatedly executed at regular time intervals.

  In the figure, it is determined whether or not a protection instruction or failure notification is received in step S10. When the protection instruction or the failure notification is received, the process proceeds to step S12, the fixed attenuation amount stored in the internal memory of the control circuit 60 # ij is read, and this fixed attenuation value is read to the variable optical attenuator (VOA) 14 # ij. Set. Thereby, the ancestor adjustment of the variable optical attenuator 14 # ij is performed. If a protection instruction or failure notification has not been received in step S10, this processing cycle ends.

  Subsequent to step S12, it is determined whether or not a predetermined time has elapsed since the reception of the protection instruction or the failure notification in step S14. Only when the predetermined time has elapsed, the process proceeds to step S16, feedback control is started, fine adjustment of the variable optical attenuator 14 # ij is performed, and the processing cycle ends. The predetermined time is set to a time sufficiently longer than the time until an optical signal is input to the variable optical attenuator 14 # ij at all nodes.

  Here, FIGS. 6 to 8 show operations when a failure occurs in the work route. The optical signal added by the transponder 6 # 1 of the node 1 shown in FIG. 6 is transmitted from the node 1 to the node 4, and a state where a failure has occurred between the node 1 and the node 4 is shown.

  In this case, as shown in FIG. 7, in order to divert the signal through the protection route passing through the nodes 1, 2, 3, and 4, the node (for example, the node 4) that detects the failure is connected to each of the nodes 1 and 2 in the protection route. , 3 are sent protection instructions (or fault notifications). Note that the protection instruction or the failure notification is realized by transmitting an APS (Automatic Protection Switch) through a monitoring OSC (Optical Supervisor Channel).

  With the protection instruction (or failure notification) as a trigger, as shown in FIG. 8, the control circuits 60 # 11, 60 # 11, 60 # 21, and 60 # 31 of each of the nodes 1, 2, and 3 of the protection route are built-in memory. Are set in the variable optical attenuators 14 # 11, 14 # 21, and 14 # 31. Each node performs this setting regardless of whether an optical signal is input. The fixed attenuation amounts of the nodes 1, 2, and 3 are not necessarily the same. For example, the node 1 is 10 dB, the node 2 is 11 dB, and the node 3 is 9 dB. At the same time, the node 1 supplies the optical signal added by the transponder 6 # 1 to the optical switch 4 # 1, and the node 4 supplies the optical signal from the optical switch 4 # 4 to the transponder 10 # 4.

  Thereafter, after an optical signal is input to the variable optical attenuator 14 # ij of each node i, the control circuit 60 # ij of each node switches to feedback control of the variable optical attenuator 14 # ij, and the variable optical attenuator 14 #. The level of the optical signal output by ij is adjusted to be constant.

  9A and 9B show temporal changes in the attenuation amount of the variable optical attenuator 14 # ij in each node and the optical level of the output optical signal by the optical variable attenuation control in FIG. In the figure, T0 indicates the trigger reception time point of the protection instruction (or failure notification), and T1 indicates the time point when a predetermined time has elapsed since the trigger reception. Here, T1-T0 is, for example, 10 msec. Further, the predetermined ATT amount in FIG. 9A is, for example, 10 dB, the target is 9 dB, the target in FIG. 9B is 0 dB, and the predetermined ATT amount is, for example, −1 dB.

  As a result, as long as the trigger is applied, the variable optical attenuator 14 # ij of each node starts to operate simultaneously, so the time is shortened and the control is simplified. Further, since the variable optical attenuator 14 # ij also adjusts the signal to an approximate level, the signal can be communicated to the last node early. Further, since light is input to the variable optical attenuator 14 # ij, constant output control can be performed quickly and fine adjustment can be performed quickly.

Second Embodiment FIG. 10A is a flowchart of failure detection processing executed by the control circuit 60 # ij according to the second embodiment of the present invention, and FIG. 10B is a flowchart of optical variable attenuation processing executed by the control circuit 60 # ij. is there. This process is repeatedly executed at regular time intervals. In the figure, the same parts as those in FIG.

  In FIG. 10A, a failure of the transmission path connected to the own node is detected in step S20. The above-mentioned transmission line failure detection is performed by detecting line alarms such as LOL (Loss Of Light), LOS (Loss Of Signal), LOF (Loss Of Frame), AIS-L (Alarm Indication Signal-Line), and AIS-P (Alarm). This is done by detecting Indication Signal-Path).

  If a transmission line failure is detected, the process proceeds to step S22, and a protection instruction or failure notification is transmitted to at least each node of the protection route. Thereafter, after waiting for a predetermined time in step S24, the second trigger is transmitted to each node of the protection route. Note that the second trigger is also realized by transmitting APS or the like by OSC.

  In FIG. 10B, it is determined whether or not a protection instruction or failure notification is received in step S10. When the protection instruction or the failure notification is received, the process proceeds to step S12, the fixed attenuation value stored in the built-in memory of the control circuit 60 # ij is read, and this fixed attenuation value is changed to the variable optical attenuator (VOA) 14 # ij. Set to. Thereby, the ancestor adjustment of the variable optical attenuator 14 # ij is performed. If no protection instruction or failure notification is received in step S10, this processing cycle is terminated.

  Following step S12, it is determined whether or not the second trigger is received in step S18. When the second trigger is received, the process proceeds to step S16, feedback control is started, fine adjustment of the variable optical attenuator 14 # ij is performed, and the processing cycle is ended.

  11A and 11B show temporal changes in the attenuation amount of the variable optical attenuator 14 # ij in each node and the optical level of the output optical signal by the optical variable attenuation control process in FIG. 10B. In the figure, T0 indicates the trigger reception time point of the protection instruction (or failure notification), and T2 indicates the second trigger reception time point.

  As a result, regardless of the number of nodes and the form of the network, state transition is possible in an optimal time, and flexible optical variable attenuation control is possible. In other words, failure recovery can be shortened if network control or node control is fast.

Third Embodiment FIG. 12 is a flowchart of an optical variable attenuation control process executed by a control circuit 60 # ij according to a third embodiment of the present invention. This process is repeatedly executed at regular time intervals.

  In the figure, it is determined whether or not a protection instruction or failure notification is received in step S20. When the protection instruction or the failure notification is received, the process proceeds to step S22 to determine whether or not the own node is an add node. When the own node is an add node, the process proceeds to step S28, feedback control is started, and the processing cycle is ended. If no protection instruction or failure notification has been received in step S20, this processing cycle ends.

  If the own node is not an add node, the process proceeds to step S24, the fixed attenuation value stored in the built-in memory of the control circuit 60 # ij is read, and this fixed attenuation value is set in the variable optical controller (VOA) 14 # ij. . Thereby, the ancestor adjustment of the variable optical attenuator 14 # ij is performed. Next, in step S26, it is determined whether or not a predetermined time has elapsed after receiving the protection instruction or the failure notification. Only when the predetermined time has elapsed, the process proceeds to step S28, feedback control is started, fine adjustment of the variable optical attenuator 14 # ij is performed, and the processing cycle is ended. The predetermined time is set to a time sufficiently longer than the time until the optical signal starts to be input to the variable optical attenuators 14 # ij of all nodes.

  In this case, with the protection instruction (or failure notification) as a trigger, as shown in FIG. 13, the control circuits 60 # 21 and 60 # 31 of the nodes 2 and 3 as the through nodes in the protection route are stored in the built-in memory. The fixed attenuation value is set in the variable optical attenuators 14 # 21 and 14 # 31. However, at node 1, which is an add node in the protection route, the control circuit 60 # 11 starts feedback control from the beginning, and the level of the optical signal output from the variable optical attenuator 14 # 11 is adjusted to be constant.

  14A and 14B are diagrams illustrating temporal changes in the attenuation amount of the variable optical attenuator 14 # ij of the add node and the optical level of the output optical signal by the optical variable attenuation control process of FIG. In the figure, T0 indicates the trigger reception time point of the protection instruction (or failure notification).

  Here, in the add node, as shown in FIG. 15, the optical switch 70 corresponding to the optical switch 4 # i for the counterclockwise path and the optical switch 71 corresponding to the optical switch 4 # i for the clockwise path Transponders 72 and 73 and optical switches 74 and 75 are provided. In this configuration, for example, between the optical signal supplied from the demultiplexer (WDMUX) to the optical switch 71 and the optical signal supplied from the transponders 72 and 73 through the optical switch 75, the optical switch 75 loses the optical power. There is a level difference.

  Even in such a case, in the present embodiment, since the add node performs feedback control from the beginning, it is possible to absorb the level difference after switching due to variations in path loss within the add node. In each node, there are two cases, depending on the path path and failure location in the network, when the local node becomes an add node and other nodes, and each node is required to have data. However, this need is eliminated by applying this control.

Fourth Embodiment FIG. 16 is a flowchart of the instantaneous interruption control process executed by the control circuit 60 # ij according to the fourth embodiment of the present invention. In the figure, in step S30, it is determined whether or not a signal loss (LOL (Loss Of Light)) is detected in the own node. If a signal interruption is detected, the control circuit 60 # ij holds the attenuation value of the variable optical attenuator (VOA) 14 # ij that is performing feedback control in step S32 in the built-in memory, and this held attenuation value is stored in the variable light. Set to attenuator 14 # ij.

  Thereafter, in step S34, it is determined whether or not a predetermined time has elapsed. If the predetermined time has not elapsed, the process proceeds to step S32, and steps S32 and S34 are repeated. If the predetermined time has elapsed, the fixed attenuation value ATT-L (a value larger than the attenuation value of normal feedback control) is set in the variable optical attenuator 14 # ij in step S36, and the process proceeds to step S36.

  On the other hand, if no signal interruption is detected in step S36, feedback control is executed in step S40, and the process proceeds to step S30.

  For example, in the state where the client signal supplied to the transponder 72 shown in FIG. 15 is supplied to the optical switch 71 through the optical switch 75, when a failure occurs on the client side, the client signal from the transponder 72 is transmitted by the optical switch 75. Is switched to the client signal from the transponder 73, the optical signal is interrupted due to the switching time of the optical switch 75.

  17A, 17B, and 17C are diagrams illustrating an operation when an instantaneous interruption of an optical signal occurs in the present embodiment. When an optical signal interruption occurs in the work route including the nodes 1, 2, 3, and 4 shown in FIG. 17A, the control circuit 60 # ij (i = 1, 2, 3) of each of the nodes 1, 2, and 3 is used. ) Detects signal loss independently.

  Then, as shown in FIG. 17B, the control circuit 60 # ij (i = 1, 2, 3, 4) of each of the nodes 1, 2, 3 is connected to the variable optical attenuator 14 # ij (i = 1, 2, 3). ) Is held in the built-in memory, and this held attenuation value is set in the variable optical attenuator 14 # ij (i = 1, 2, 3).

  Thereafter, if the instantaneous interruption of the optical signal is canceled, as shown in FIG. 17C, the control circuit 60 # ij (i = 1, 2, 3) of each of the nodes 1, 2, 3 is changed to the variable optical attenuator 14 #. Shifting to feedback control of ij (i = 1, 2, 3), the level of the optical signal output from the variable optical attenuator 14 # ij (i = 1, 2, 3) is adjusted to be constant.

  18A and 18B are diagrams showing temporal changes in the attenuation amount of the variable optical attenuator 14 # ij in each node and the optical level of the output optical signal by the instantaneous interruption control process in FIG. This figure shows a case where the time from the start of the instantaneous interruption to the cancellation of the instantaneous interruption is within a predetermined time.

  19A and 19B are diagrams showing another example of the temporal change in the attenuation amount of the variable optical attenuator 14 # ij of each node and the optical level of the output optical signal by the instantaneous interruption control process of FIG. This figure shows a case where a time-out has occurred after a predetermined time has elapsed since the start of instantaneous interruption.

  As a result, the variable optical attenuator 14 # ij inadvertently reduces the attenuation when the signal is interrupted, and prevents an optical surge in which the light level increases due to insufficient attenuation when the signal is restored again. If there is no significant change in the level when the signal is restored, the amount of fine adjustment is small and the optical power can be adjusted to the target level quickly.

Fifth Embodiment FIG. 20 is a flowchart of the control processing at the momentary interruption executed by the control circuit 60 # ij according to the fifth embodiment of the present invention. In the figure, the same parts as those in FIG. In FIG. 20, it is determined in step S30 whether or not a signal interruption is detected in the own node. If a signal interruption is detected, it is determined in step S42 whether or not the own node is an add node. When the own node is an add node, the process proceeds to step S38, and the fixed attenuation value ATT-L is set in the variable optical attenuator 14 # ij.

  When the own node is an add node, the process proceeds to step S32, and the control circuit 60 # ij holds the attenuation value of the variable optical attenuator (VOA) 14 # ij performing feedback control in the built-in memory, and this holding attenuation. The value is set to the variable optical attenuator 14 # ij.

  Thereafter, in step S34, it is determined whether or not a predetermined time has elapsed. If the predetermined time has not elapsed, the process proceeds to step S32, and steps S32 and S34 are repeated. If the predetermined time has passed, it is determined whether or not a signal loss is detected in step S36. If a signal loss is detected, the fixed attenuation value ATT-L is set to the variable optical attenuator 14 # ij in step S38. Then, the process proceeds to step S36.

  On the other hand, if no signal interruption is detected in step S36 (signal interruption release), feedback control is executed in step S40, and the process proceeds to step S30. 21A and 21B are diagrams showing temporal changes in the attenuation amount of the variable optical attenuator 14 # ij of the add node and the optical level of the output optical signal by the control processing at the momentary interruption in FIG.

  As described above, the add node sets a fixed attenuation value ATT-L that is close to the maximum value in the variable optical attenuator 14 # ij due to the signal disconnection, so that an optical signal having a large optical level is generated when the signal disconnection is canceled. When it is input, it is possible to prevent an optical surge from being induced.

  16 and 20, steps S36 and S38 may be deleted, and step S34 may be repeated when the signal interruption is not canceled in step S34. 22A and 22B show changes in the attenuation amount of the variable optical attenuator 14 # ij and the optical level of the output optical signal due to the control processing at the moment of interruption.

  As described above, during the signal interruption period, the holding attenuation value when the signal interruption is detected is set in the variable optical attenuator 14 # ij, thereby shortening the adjustment time when the signal interruption is released and recovered. Can do.

  FIG. 23 is a diagram for explaining a method for obtaining a fixed attenuation value stored in the internal memory of the control circuit 60 # ij of each node. Before operating the system in advance, or periodically (using a timer) or irregularly (manually), the dummy light output from the dummy light source 80 # 1 provided in the node 1 as an add node is input to the optical switch 4 # 1, and the node It is transmitted through 2, 3, and 4 routes.

  With the dummy light supplied, the control circuits 60 # 11, 60 # 21 and 60 # 31 of the nodes 1, 2 and 3 execute feedback control, and the variable optical attenuators 14 # 11, 14 # 21 and 14 #. 31. After adjusting the level of the optical signal output from 31 to a constant value, the attenuation values of the variable optical attenuators 14 # 11, 14 # 12, and 14 # 13 at that time are fixed attenuation values, and the control circuits 60 # 11 and 60 # 21. , 60 # 31. It should be noted that the dummy light source may be dedicated or shared with other signal sources.

Sixth Embodiment FIG. 24 is a block diagram of a node according to the sixth embodiment of the present invention. Components that are substantially the same as those shown in FIG. 86 are given the same reference numerals. The nodes are WDMUX2 # i, SW4 # i, TNPN transmitter 6 # i, SW8 # i, TRPN receiver 10 # i, SPL12 # ij (j = 1 to n), VOA 14 # ij (j = 1 to n) , PD16 # ij (j = 1 to n), SPL18 # ij (j = 1 to n), WMUX 20 # i, PD22 # j (j = 1 to n), control device 100 # i and control circuit 102 # ij ( j = 1 to n).

  The control device 100 # i controls and monitors the entire node device, and controls all failure information, all SWs, and other functional units, and specifically has the following functions. . (1) Manage fault information that has occurred in its own node and fault information notified from other nodes. (2) SW8 # i is controlled to perform switching control between the active system and the standby system based on the failure information. (3) Notify the control circuit 102 # ij which one of the add node and the through node of the optical signal involved in the ATT amount control of each control circuit 102 # ij.

  FIG. 25 is a block diagram of the control circuit 102 # ij in the drawing. As illustrated in FIG. 25, the control circuit 102 # ij includes a detection unit 150 # ij, a memory 152 # ij, a DSP 154 # ij, and a drive circuit 156 # ij. The detection unit 150 # ij has the following functions. (1) A light break is detected from a signal or information obtained by electrically converting the optical signal level output from the PDs 16 # ij and 22 # ij, and a break detection signal is output. (2) The light break release is detected from a signal or information obtained by electrically converting the optical signal levels output from the PDs 16 # ij and 22 # ij, and a break release detection signal is output. (3) During automatic level adjustment, the difference between the optical signal level and the target level is detected. However, the DSP 154 # ij may detect the difference.

  The memory 152 # ij stores an ATT amount fixed value at the time of light interruption and an ATT amount fixed value at the time of light interruption cancellation when the own node is an add node of an optical signal related to optical level control. This is a memory for storing the ATT amount and the target value immediately after disconnection. However, these values may be incorporated in the memory in the DSP 154 # ij. In addition, the memory in the memory 152 # ij or the DSP 154 # ij may store information on whether an add node or a through node, a threshold level for optical signal interruption, a threshold level for restoration, and the like. The drive circuit 156 # ij drives the VOA 14 # ij according to the control of the DSP 154 # ij.

  FIG. 26 is an operation flowchart of the DSP 154 # ij when the own node is an add node. FIG. 27 is an operation flowchart of the DSP 154 # ij when the own node is a through node. The control device 102 # i notifies whether the own node is an add node or a through node. The DSP 154 # ij can also be realized by MPU, software that operates on the MPU, or hardware such as FPGA or ASIC.

(1) In the case of an add node In step S50, in the normal state where the disconnection detection signal and the disconnection recovery detection signal are not output, the output optical signal of the VOA 14 # ij from the optical output level output from the PD16 # ij and PD22 # ij The level is automatically adjusted so that the target level becomes the target level. In step S52, it is determined whether or not a break detection signal is output to indicate a light break. If there is a light break, the process returns to step S52. If it is not light interruption, it will return to step S50 and automatic level adjustment will be performed. In step S54, the ATT amount fixing control (ATT amount fixing control 1) is performed with the first fixed attenuation amount stored in advance in the memory 152 # ij. The first fixed attenuation amount is set to a value that does not cause the above-described problem because the output light level of the VOA 14 # ij is too high when the light is recovered from the light interruption.

  In step S56, it is determined whether the disconnection release detection signal is output and the optical disconnection is released. If the light break is not released, the process returns to step S54, and the ATT amount fixing control 1 is continued. If the light break is released, the process proceeds to step S58. In step S58, the ATT amount fixing control fixing control (ATT amount fixing control 2) is performed using the second fixed attenuation amount stored in advance in the memory 152 # ij. The second fixed attenuation amount is an attenuation amount close to the average attenuation amount in a state where the attenuation amount has converged during automatic level adjustment. This is because when the light break is canceled, the level is converged in the automatic level adjustment at high speed by forcibly shifting to the second fixed attenuation amount before shifting to the automatic level adjustment.

(2) In the case of a through node In step S100 in FIG. 27, processing similar to that in step S50 in FIG. 26 is performed. In step S102, it is determined whether a light interruption has occurred. If light interruption has not occurred, the process returns to step S100 to continue automatic level control. When the light break occurs, the ATT amount immediately after the light break is stored in the memory 152 # ij, and the process proceeds to step S104. In step S104, the ATT amount fixing control fixing control (ATT amount fixing control 3) is performed based on the ATT amount immediately after the light input interruption held in the memory 154 # ij. In step S106, it is determined whether or not the light break is released. If the light break is not released, the process returns to step S104 and the ATT amount fixing control 3 is continued. When the light break is released, the process returns to step S100 to perform automatic level adjustment.

  Hereinafter, the control method of the optical attenuator in the failure recovery will be described. Here, a case will be described in which node 200 # 1 is an add node, nodes 200 # 2 and 200 # 3 are through nodes, and node 200 # 4 is a drop node.

  FIG. 28 is a diagram illustrating the normal state. FIG. 29 is a diagram illustrating when a failure occurs. FIG. 30 is a diagram showing a state immediately after the failure recovery. FIG. 31 is a diagram showing a normal state after recovery. FIGS. 32 and 33 are diagrams showing the optical attenuator ATT amount and VOA output level at the add node, where the horizontal axis represents time (T) and the vertical axis represents the optical attenuator ATT amount and VOA output level. FIG. 34 is a diagram showing the amount of optical attenuator ATT and the VOA output level at the through node.

(1) Normal state In the add node 200 # 1, as shown in FIG. 28, the optical signal transmitted by the TRNP 6 # 10 is transmitted to the VOA 14 # 11 via the SW 8 # 1 and 4 # 1 as shown in FIG. Automatic control is performed as shown in FIG. In the through nodes 200 # 2 and 200 # 3, as shown in FIG. 28, the automatic level adjustment is performed via the SW4 # 2 and 4 # 3 in the VOAs 14 # 21 and 14 # 31 as shown in FIGS. Has been. In the automatic level adjustment, as shown in FIGS. 22 and 24, control is performed with an attenuation of about 10 dB, and the VOA output level is about −10 dBm. In the drop node 200 # 4, as shown in FIG. 28, it is received by TRNP16 # 4 via SW4 # 4 and dropped to the subscriber side.

(2) At the time of failure When the light interruption is detected in the add node 200 # 1, as shown in FIGS. 28 and 32, the optical attenuator ATT amount is set to a predetermined value 1, for example, 40 dB (or Max) in the VOA 14 # 11. ) And control (ATT fixed amount control 1). This prevents the ATT amount from becoming zero. At this time, as shown in FIG. 33, the light power is low due to light interruption and is set to a fixed attenuation amount, and the VOA output level decreases to, for example, −60 dBm or less. In the through nodes 200 # 2 and 200 # 3, when a light break is detected, as shown in FIGS. 28 and 34, the optical attenuator ATT amount is fixed to an attenuation amount immediately after the light break, for example, 10 dB (ATT). For fixed quantity control 3). The amount of attenuation is almost the same as before the light break was detected. This prevents the ATT amount from becoming zero. As shown in FIG. 25, the light power is low due to light interruption and is set to a fixed attenuation amount, and the VOA output level decreases to, for example, −60 dBm or less.

(3) Immediately after failure recovery When the light break cancellation is detected in the add node 200 # 1, as shown in FIG. 28 and FIG. 32, the attenuation is temporarily fixed at a predetermined value 2 by the VOA 14 # 11 (ATT amount). After the fixed control 2), the process proceeds to automatic level adjustment. As a result, as shown in FIG. 33, the VOA output level immediately after recovery rapidly rises to about -10 dBm, which is an average value in automatic level adjustment. In the through nodes 200 # 2 and 200 # 3, when the light break cancellation is detected, the attenuation amount is shifted to the automatic level adjustment as shown in FIGS. 28 and 34. As described above, the VOA output level rapidly rises to about −10 dBm of the target in the automatic level adjustment.

(4) Normal state (after recovery)
In the add node 200 # 1, as shown in FIGS. 28 and 32, the attenuation is automatically controlled by the VOA 14 # 11. At this time, as shown in FIG. 33, the VOA output level has risen rapidly around the target level of −10 dBm immediately after the recovery, and the variation in the ATT amount is small, so that the VOA output level is rapidly increased to −10 dBm of the target. Converge. The through nodes 200 # 2 and 200 # 3 perform automatic control as shown in FIGS. At this time, immediately after the failure recovery, as shown in FIG. 35, the VOA output level is close to the target −10 dBm, and therefore converges to the target −10 dBm at high speed by automatic control.

  In the present embodiment described above, since the ATT amount fixing control is performed with the fixed value 1 at the time of light interruption to prevent it from becoming zero, it is possible to prevent the optical power from becoming too large when the light interruption is released. Further, when the light break is released, the ATT amount fixed control is performed with a fixed value 2 close to the average ATT amount in the automatic level adjustment, and then the automatic control is performed. Therefore, the VOA output level converges to the target at high speed.

Seventh Embodiment FIG. 36 is a node block diagram according to a seventh embodiment of the present invention, are denoted by the same reference numerals to components substantially the same elements in FIG. 24. Since there is no difference in the control of the attenuation amount of the control circuit 302 # ij at the add node and the through node at the time of light interruption and restoration, the control device 300 # i has an add / thru node for each optical signal. Do not notify. The control circuit 302 # i performs ATT amount control with a longer cycle than conventional control. In the conventional ATT amount control, since the attenuation amount of the VOA 14 # ij becomes zero and completely opens between the occurrence of a light interruption and switching between the active system and the standby system and recovery, the control circuit 302 # ij In order to avoid this, the ATT amount control is performed in a long cycle so that it does not become zero between the light interruption and the recovery.

  37 to 39 are diagrams showing the optical attenuation amount ATT amount, VOA input level, and VOA output level at the add node and through node. The horizontal axis represents time (T), the vertical axis represents optical attenuation amount ATT amount, and the VOA input level. And VOA output levels are shown.

(1) Normal state In the normal state, the optical attenuator ATT amount is automatically controlled in a long cycle. For example, the average value of the optical attenuator ATT amount is 10 dB, and the VOA input level is The 0 dBm, VOA output level converges at -11 dBm of the target.

(2) When a failure occurs Even if a light interruption occurs, the ATT amount of the optical attenuator is automatically controlled in a long cycle, so the attenuation amount is not reduced immediately, but the optical attenuator attenuation amount ( The amount of ATT decreases to about 1 dB before the light break is released. However, since it is a long cycle, as shown in FIG. 37, it does not drop to near zero level until the light break is released. In the meantime, the VOA input level has dropped to about -50 dBm, and the VOA output level has dropped to a light interruption level, for example, about -60 dBm. That is, even if the input light level fluctuates, the amount of attenuation does not immediately follow, and the control is performed slowly. Therefore, if the light interruption time is sufficiently shorter than the control speed, the amount of ATT hardly changes. It will not be zero.

(3) Failure recovery When the light break is released, the ATT that was slowly reduced at the time of the light break is returned again to the original 10 dB vicinity again. The VOA output level at the time of recovery from the light interruption is larger than the target -11 dBm because the attenuation is reduced.

(4) Normal state Since the ATT amount is gradually returned to the original state, the VOA output level converges to the optical power level of the target, for example, -11 dBm.

  According to the present embodiment described above, since the attenuation amount is controlled in a long cycle, the attenuation amount does not decrease so much between the light interruption and the light interruption cancellation. Therefore, when the light interruption is released, the VOA output level is reduced. Will return to the target level without becoming too large.

Eighth Embodiment FIG. 40 is a node configuration diagram according to the eighth embodiment of the present invention. Components that are substantially the same as those shown in FIG. 30 are given the same reference numerals. The control circuit 350 # ij performs automatic level control in which the reaction speed is different between the normal time and the light interruption time.

  FIG. 41 is an operation flowchart of the control time 350 # i.

(1) Normal time In step S200, since light interruption has not occurred, automatic level adjustment (automatic level adjustment 2) is performed. At this time, for example, the average value of the optical attenuator ATT amount is 10 dB, the VOA input level is 0 dBM, and the VOA output level is converged to -11 dBm which is the target.

(2) When a failure occurs In step S202, it is determined whether or not there is a light interruption. If it is light interruption, the process proceeds to step S204. If light is not interrupted, the process returns to step S202. In step S204, when a light interruption failure occurs, the optical power level is adjusted by applying automatic level adjustment 1 having a reaction speed different from that of automatic level adjustment 2. At this time, the relationship of the reaction speed between the automatic level adjustment 2 and the automatic level adjustment 1 will be described.

(A) When the reaction speed of the automatic level adjustment 1 is slower than the automatic level adjustment 2 FIGS. 42 to 44 show the light attenuation amount ATT amount, VOA input level, and VOA input level when the reaction speed of the automatic level adjustment 1 is slower than the automatic level adjustment 2. It is a figure which shows a VOA output level, and the horizontal axis shows time (T), and the vertical axis | shaft has shown the optical attenuation amount ATT amount, the VOA input level, and the VOA output level. When a light break is detected, the speed of level adjustment becomes slow as shown in FIGS. As a result, the optical attenuator ATT amount is reduced by about 1 dB until the light break is released, and becomes about 9 dB. During the light break, the fluctuation of the attenuation amount is suppressed to be small, and the follow-up property to the fluctuation in the normal state. Is expensive.

(B) When the reaction speed of the automatic level adjustment 1 is faster than the automatic level adjustment 2 FIGS. 45 to 47 show the light attenuation amount ATT amount, the VOA input level and the VOA input level when the reaction speed of the automatic level adjustment 1 is faster than the automatic level adjustment 2. It is a figure which shows a VOA output level, and the horizontal axis shows time (T), and the vertical axis | shaft has shown the optical attenuation amount ATT amount, the VOA input level, and the VOA output level. In the normal state, the level adjustment speed is slowed down, and when a light break is detected, the level adjustment speed is fastened. At this time, the followability of the VOA ATT amount becomes higher with respect to the VOA input level fluctuation shown in FIG. 46, and the VOA output becomes similar as shown in FIG. Furthermore, compared to FIG. 42, since the ATT amount opens (zero) when there is a light break, it is considered that a slight overshoot occurs from the operation of FIG. However, although the amount of optical attenuator ATT decreases from the time when light breakage is released to the time when light breakage is released, the adjustment speed that does not become zero in the time from normal light breakage to recovery is reduced to, for example, about −53 dBm.

(3) Failure recovery In step S206, it is determined whether or not the light break is released. If the light break is released, the process returns to step S200, and automatic level adjustment 2 is performed.

(A) When the reaction speed of the automatic level adjustment 1 is slower than that of the automatic level adjustment 2 When the light break is released, the optical attenuator ATT amount is adjusted by the automatic level adjustment 2 having a fast level adjustment speed. At this time, the optical attenuator ATT amount is reduced by about 1 dB and is about 9 dB during the period from the light interruption to the light interruption cancellation. However, since the fluctuation is small from the average attenuation amount of 10 dB in the automatic level adjustment 2, it is in the normal state. The followability becomes high with respect to the fluctuation of the time.

(B) When the reaction speed of the automatic level adjustment 1 is faster than the automatic level adjustment 2 When the light break is released, the amount of light attenuator ATT is adjusted once with the automatic level adjustment 1 with a high level adjustment speed. The rise is quicker. Thereafter, the ATT amount is automatically controlled by automatic level adjustment 2 having a slow level adjustment speed.

(4) Normal state ATT amount is automatically controlled by automatic level adjustment 2.

  According to the embodiment described above, since the adjustment speed is changed between the automatic level adjustment 2 in the normal state and the automatic level adjustment 1 at the time of light interruption, the light level at the time of light interruption does not become zero, depending on the situation. By providing the optimum control speed, the power level can be controlled with high accuracy and the switching time can be shortened.

Ninth Embodiment FIG. 48 is a block diagram of a node according to the ninth embodiment of the present invention. Components that are substantially the same as those shown in FIG. 24 are given the same reference numerals. The control device 450 # i collects the failure information generated in the own node and detects that a failure has occurred in order to perform switching control between the active system and the standby system based on the failure that has occurred in the own node or another node. The failure information indicating that is cleared is transmitted to the other node, the failure information generated in the other node is received and relayed to the adjacent node. The failure information is not only the failure of the add node transponder but also the information related to the interruption of the optical input signal input to the VOA 14 #ij, and the failure other than the optical interruption or the detection of the optical interruption occurs itself. This information is also included. Therefore, the control device 450 # i notifies the control circuit 452 # ij of failure information related to the input optical signal of the VOA 14 # ij. The control circuit 452 # ij judges light breakage and light break release from the failure information related to the input of the VOA 14 # ij notified from the controller 450 # i, and the light attenuator ATT at the time of light break and light break release cancellation. Control the amount.

  FIG. 49 is an operation flowchart of the control circuit 452 # i. In step S300, automatic level adjustment (automatic level adjustment 2) is normally performed. In step S302, it is determined whether there is failure information. If there is failure information, the process proceeds to step S304. If there is no failure information, the process returns to step S300. In step S304, automatic level adjustment (automatic level adjustment 1) different from the adjustment speed of automatic level adjustment 2 is performed. In step S306, it is determined whether the failure information has been cleared. If the failure information is cleared, the process returns to step S300 and automatic level adjustment 2 is performed. If the failure information is not cleared, the process returns to step S304, and automatic level adjustment 1 is continued.

  50 to 52 are diagrams showing the optical attenuation amount ATT amount, VOA input level and VOA output level at the add node and the through node. The horizontal axis represents time (T), the vertical axis represents the optical attenuation amount ATT amount, and the VOA input level. And VOA output levels are shown. In FIGS. 50 to 52, the light break in FIGS. 42 to 44 is merely replaced with light break failure information detection, and light break release is replaced with light break release failure information detection.

  FIG. 53 is a diagram for explaining the operation in the normal state. FIG. 54 is an explanatory diagram of the operation when a failure occurs. FIG. 55 is a diagram for explaining the operation immediately after failure recovery. FIG. 56 is an explanatory diagram of the operation in the normal state after recovery.

(1) Normal state In the normal state, as shown in FIG. 54, the control circuit 452 # i1 (i = 1, 2, 3) of the node 500 # i sets the ATT amount of the VOA 14 # i1 to a constant reaction rate. The automatic control (automatic control 1) is performed for the automatic level adjustment 2 in FIG.

(2) When a failure occurs The controller 450 # 1 of the add node 500 # 1 collects failure information related to the input optical signal of the VOA 14 # 11, such as the hardware of the active TPND 6 # 10, and the control circuit 452 # 11 and the node 500 # 2. When receiving the failure information from the node 500 # 1, the control device 450 # 2 of the node 500 # 2 notifies the control circuit 452 # 21 as failure information of the VOA input of the VOA 14 # 21 and also notifies the node 500 # 3. . Similarly to the node 500 # 2, the node 500 # 3 notifies the control circuit 14 # 31 of the received failure information and notifies the node 500 # 4.

  When a failure occurs in TRPN6 # 10, control circuit 452 # i1 (i = 1, 2, 3) shown in FIG. 54 is notified of the failure information from control device 450 # i (i = 1, 2, 3). When the control circuit 452 # i1 receives the failure information notification from the control device 450 # i, the control circuit 452 # i1 determines that the input optical signal of the VOA 14 # i1 is disconnected, and the automatic level adjustment of the reaction speed different from the automatic level adjustment 2 1 to automatically control the ATT amount (automatic control 1).

(3) Immediately after the failure is restored When the light interruption is restored by switching from TRPN6 # 10 to TRPN6 # 11, the control circuit 452 # i1 (i = 1, 2, 3) is controlled by the controller 450 # i (i = 1, 2, 3) The failure information is cleared. When the control circuit 452 # i1 receives clearing of the failure information from the control device 450 # i, the control circuit 452 # i1 determines that the disconnection of the input optical signal of the VOA 14 # i1 has been released, and the automatic level adjustment 1 sets the ATT amount of the VOA 14 # i1. Automatic control (automatic control 1) is performed.

(4) Normal state (after recovery)
As shown in FIG. 56, the control circuit 452 # i1 automatically controls the ATT amount of the VOA 14 # i1 continuously with automatic level adjustment 1.

  According to the present embodiment described above, the occurrence of failure information or the clearing of failure information is notified to the control circuit, and the amount of ATT is controlled by clearing the failure information and the failure information. The same effect can be obtained.

Tenth Embodiment FIG. 57 is a node configuration diagram according to the tenth embodiment of the present invention. Components that are substantially the same as those shown in FIG. 48 are given the same reference numerals. The control circuit 550 # ij judges light breakage and light breakage release from the failure information related to the input of the VOA 14 # ij notified from the control device 450 # i, and determines the amount of light attenuator ATT at the time of light breakage and light breakage release. Control.

  FIG. 58 is an operation flowchart of the control circuit 500 # ij. In step S400, automatic level adjustment (normal level adjustment) is normally performed. In step S402, it is determined whether there is failure information. If there is failure information, the process proceeds to step S404. If there is no failure information, the process returns to step S400. In step S404, the optical attenuator ATT amount is fixed, for example, the VOA 14 # ij is controlled by the ATT amount immediately after the light interruption (ATT amount fixed control 3). In step S406, it is determined whether the failure information has been cleared. If the failure information is cleared, the process returns to step S400 and normal automatic level adjustment is performed. If the failure information is not cleared, the process returns to step S404, and the ATT amount fixing control 1 is performed.

  59 and 60 are diagrams showing the optical attenuation amount ATT amount and the VOA output level at the add node and the through node. The horizontal axis indicates time (T), and the vertical axis indicates the optical attenuation amount ATT amount and the VOA output level. Yes. In FIGS. 59 and 60, the light break in FIGS. 34 and 35 is simply replaced with light break failure information detection, and the light break release is replaced with light break release failure information detection.

  FIG. 61 is a diagram for explaining the operation in the normal state. FIG. 62 is a diagram for explaining the operation when a failure occurs. FIG. 63 is a diagram for explaining the operation immediately after failure recovery. FIG. 64 is a diagram for explaining the operation in the normal state after recovery.

  Hereinafter, the control method of the optical attenuator in the failure recovery will be described. Here, a case will be described in which node 600 # 1 is an add node, nodes 600 # 2 and 600 # 3 are through nodes, and node 600 # 4 is a drop node.

(1) In the normal state In the normal state, as shown in FIG. 61, the control circuit 452 # i1 (i = 1, 2, 3) of the node 500 # i automatically controls the ATT amount of the VOA 14 # i1. ing.

(2) When a failure occurs When a failure occurs in the TRPN6 # 10, the control circuit 500 # i1 (i = 1, 2, 3) is notified of the failure information from the control device 450 # i (i = 1, 2, 3). The Upon receiving notification of failure information from the control device 500 # i, the control circuit 450 # i1 determines that the input optical signal of the VOA 14 # i1 is disconnected, and fixes the ATT amount immediately after the light interruption to the VOA 14 # i1. Controls the amount of ATT.

(3) Immediately after the failure is restored When the light interruption is restored by switching from TRPN6 # 10 to TRPN6 # 11, the control circuit 500 # i1 (i = 1, 2, 3) is controlled by the controller 450 # i (i = 1, 2, 3). The failure information is cleared more clearly. When the control circuit 500 # i1 receives clearing of the fault information from the control device 450 # i, the control circuit 500 # i1 determines that the disconnection of the input optical signal of the VOA 14 # i1 has been released, and automatically determines from the ATT amount fixed immediately after the light interruption. Control is passed to control the VOA 14 # i1.

(4) Normal state (after recovery)
The control circuit 500 # i1 automatically controls the ATT amount of the VOA 14 # i1.

  According to the present embodiment described above, the occurrence of failure information or the clearing of failure information is notified to the control circuit, and the ATT amount is controlled by clearing the failure information and the failure information. The same effect can be obtained.

Eleventh Embodiment FIG. 65 is a node configuration diagram according to the eleventh embodiment of the present invention. Components that are substantially the same as those shown in FIG. 48 are given the same reference numerals.

  FIG. 66 is an operation flowchart of the control circuit 650 # ij in the add node. In step S500, automatic level adjustment (automatic level adjustment) is normally performed. In step S502, it is determined whether or not there is a light interruption. If light is interrupted, the process proceeds to step S504. If there is no light break, the process returns to step S500. In step S504, the optical attenuator ATT amount is fixed, for example, the VOA 14 # ij is controlled by the ATT amount immediately after the light interruption (ATT amount fixed control 1). In step S506, it is determined whether or not the light break is released. If the light break is released, the process proceeds to step S508. In step S508, the ATT amount is controlled to a fixed value (ATT amount fixing control 2), and then the process returns to step S500 to perform automatic level adjustment. If the light break is not released, the process returns to step S504, and the ATT amount fixing control 1 is performed.

  FIG. 67 is an operation flowchart of the control circuit 650 # ij in the through node. In step S550, automatic level adjustment (automatic level adjustment) is normally performed. In step S552, it is determined whether a light break has been detected. If a light break is detected, the timer is started, and then the process proceeds to step S554. If no light break is detected, the process returns to step S550. In step S554, the optical attenuator ATT amount is fixed, for example, the VOA 14 # ij is controlled by the ATT amount immediately after the light interruption (ATT amount fixing control 3). In step S556, it is determined whether or not the timer has timed out. It is assumed that the timer times out at a time required for canceling the light break from a normal light break (a time for switching from the active system to the standby system), for example, 500 ms. In other words, when the timer times out, the time is such that the light break is released. If the timer has timed out, the process returns to step S550 to perform automatic level adjustment. If the timer has not timed out, the process returns to step S554, and the ATT amount fixing control 3 is performed.

  FIG. 68 is an operation flowchart of the control circuit 650 # ij in another through node. Instead of the timeout in FIG. 67, the failure information release is used as a trigger. The reason why failure information is received from the outside is that there may be a case where failure cannot be detected by the detection unit in the control circuit 650 # ij. For example, VOA14 # ij is opened due to a failure of the detection unit or a failure of VOA14 # ij, the original optical signal is cut off, but the light level light breakage is determined by the accumulation of light noise by the optical amplifier, etc. Because there are things that cannot be done. In step S600, automatic level adjustment (automatic level adjustment) is normally performed. In step S602, it is determined whether a light break has been detected. If a light break is detected, the process proceeds to step S604. If no light break is detected, the process returns to step S600. In step S604, the optical attenuator ATT amount is fixed, for example, the VOA 14 # ij is controlled by the ATT amount immediately after the light interruption (ATT amount fixed control 3). In step S606, it is determined whether or not the failure information has been cleared. If the failure information is cleared, the process returns to step S600 to perform automatic level adjustment, and if the failure information is not cleared, the process returns to step S604 to perform ATT amount fixing control 3. In the through node, FIG. The flow in FIG. 68 and FIG. 68 can be arbitrarily selected.

  69 and 70 are diagrams showing the optical attenuator ATT amount and the VOA output level in the add node. The horizontal axis shows time (T), and the vertical axis shows the optical attenuator ATT amount and VOA output level. 71 and 72 are diagrams showing the optical attenuation amount ATT amount and the VOA output level in the through node adopting the flow of FIG. As shown in FIG. 69, when automatic light level adjustment is performed in the vicinity of 10 dB at the add node, if light interruption is detected, the attenuation is fixed at 40 dB and the VOA 14 #ij is controlled (ATT amount fixed control 1). . When recovering from the light break, the attenuation is set to 5 dB (ATT amount fixing control 2), and further automatic control (automatic level adjustment) is performed. In the through node, when the light break is detected, the light attenuation is fixed to 10 dB immediately after the light break (ATT amount fixing control 3). From there, the passage of time is monitored, and when a 500 msec timer is provided, the control returns to automatic level control (automatic level adjustment) after 500 msec. Here, in the case where the light interruption lasted for 400 msec, the light interruption was recovered before the time-out, and when the output of the VOA 14 # ij of the through node is recovered from the light interruption, the light level is also recovered.

  73 and 74 are diagrams showing the optical attenuation amount ATT amount and the VOA output level in the add node. 75 and 76 are diagrams showing the optical attenuation amount ATT amount and the VOA output level in the through node adopting the flow of FIG. The time chart in the add node is the same as that shown in FIGS. The time chart in the through node is different in that the timer release in FIGS. 71 and 72 is replaced with the failure information release.

  According to the present embodiment described above, since the attenuation amount is fixed immediately after the light interruption, even if the automatic control at the normal time is performed using the timer timeout as a trigger, the light interruption is released before and after the timeout. However, the VOA output can be converged to the target at high speed.

Twelfth Embodiment FIG. 77 is a block diagram of a node according to a twelfth embodiment of the present invention. Components that are substantially the same as those shown in FIG. 24 are given the same reference numerals.

  FIG. 78 is an operation flowchart of the control circuit 700 # ij in the add node. In step S650, automatic level adjustment (long-cycle automatic level adjustment) is performed in a long cycle at normal times. In step S652, it is determined whether or not light is interrupted. If the light break is detected, the timer is started when the light break is detected. If the timer has already been started, nothing is done and the process proceeds to step S654. If there is no light interruption, the process returns to step S650. In step S654, it is determined whether the timer has timed out. If the timer has not timed out, the process returns to step S652. In other words, when the light break is released, the long period automatic level adjustment is restored even before the timer times out. If the timer times out, the process proceeds to step S656.

  In step S656, it is determined whether or not light is interrupted. If it is a light break, the process proceeds to step S658. If it is not light interruption, it will return to step S650 and long period automatic level adjustment will be performed. That is, if the light break is released at the time of timeout, the long cycle automatic level adjustment is performed. In step S658, the VOA 14 # ij is controlled with the ATT amount fixed (ATT amount fixed control 2). That is, when the timer times out, if the light break is not released, the ATT amount fixing control 1 is performed. In step S660, it is determined whether or not there is a light interruption. If it is a light break, the process returns to step S658. That is, the ATT amount fixing control 1 is performed until the light break is released. If the light break is released, the process proceeds to step S662. In step S666, the VOA 14 # ij is controlled with the ATT amount fixed (ATT amount fixed control 2), and then the process returns to step S650, and the long cycle automatic level adjustment is performed.

  79 to 81 are diagrams showing the optical attenuation amount ATT amount, VOA input level, and VOA output level in the add node. Normally, the optical attenuator ATT amount is controlled in the vicinity of 10 dB. When a light break is detected, a timer that times out at 500 msec is started. When the light interruption recovers continuously for 400 msec before the timer times out, the ATT amount is shifted by about 1 dB at the long cycle level, but 500 msec has not elapsed since the light interruption, and the fixed control (ATT fixed control 1) The long period adjustment is continued without transition to.

  82 and 83 are diagrams showing the optical attenuation amount ATT amount and the VOA output level in the add node. On the other hand, if the light interruption continues for 500 msec or longer, the light interruption is maintained when the timer times out. Therefore, the ATT amount fixing control 1 is performed when the timer times out, and the ATT amount is fixed to 40 dB. This usually keeps the ATT amount at a fixed value even if the light break occurs beyond the time when the light break is detected after the light break is detected, and it is not possible to predict when the light break will be released. Therefore, even if light is interrupted for a long time, the attenuation amount does not become zero. As long as the light break is not released, the ATT amount is maintained. When the light break is restored, the process shifts to ATT amount fixing control 2 to set the ATT amount to 5 dB. Thereafter, the process shifts to automatic level adjustment. On the other hand, the through node is always kept in the long cycle automatic level adjustment.

  According to the present embodiment described above, since the add node performs long-period automatic level control from the time when the light break is detected until the out node is output, the same effect as that of the sixth embodiment is obtained and the timer is timed out. Then, since the fixed level control is performed, even if light is interrupted for a long time for some reason, the attenuation amount does not become zero when the through-node light disconnection is canceled, and the add node can block the light.

Thirteenth Embodiment FIG. 84 is a node configuration diagram according to the thirteenth embodiment of the present invention. Components that are substantially the same as those shown in FIG. 24 are given the same reference numerals.

  FIG. 85 is an operation flowchart of the control circuit 750 # ij in the add node and the through node. Steps S700 to S704 are the same as steps S650 to S654 in FIG. In step S706, the VOA 14 # ij is controlled with the ATT amount fixed (ATT amount fixed control 1). That is, when the timer times out, the ATT amount fixing control 1 is performed regardless of whether the light interruption is canceled or not. Steps S708 to S710 are the same as steps S660 to S662 in the figure.

  Waveforms of the optical attenuator ATT amount, VOA input level, and VOA output level at the add node and through node are released after the timeout in FIG. 79 to FIG. Is the same as FIG. 82 and FIG. In FIG. 79, it is the time when the ATT amount fixing control 1 is released from the timer (500 msec). As a result, in all nodes, when time has elapsed since the detection of light breakage, the process proceeds to ATT amount fixing control 1, and thereafter, when recovery from light interruption occurs, long-term automatic level control is performed via ATT amount fixing control 2. Move.

  According to the present embodiment described above, the same effect as that of the add node of the twelfth embodiment can be obtained in all nodes.

14th Embodiment FIG. 8 6 is an operation flowchart of the control circuit in the add node according to a fourteenth embodiment of the present invention. This flowchart is a modification of the control flow shown in FIG. The processing from step S750 to step S758 in FIG. 84 is the same as the processing from step S500 to step S508 in FIG. However, in step S756, a timer is started when light break cancellation is detected.

  Then, when the ATT amount fixing control 2 is performed in step S758, it is not immediately shifted to automatic level adjustment, but in step S760, it is determined whether or not the timer has timed out. If the timer does not time out, the process returns to step S758, and the ATT amount fixing control 2 is performed. If the timer has timed out, the process returns to step S750 to perform automatic level adjustment. That is, after the ATT amount fixing control 2 is continuously controlled for the timer time, the process proceeds to automatic level adjustment. Thereby, the ATT amount fixing control 2 can be continuously performed for an optimum time. Note that the operations at the time of occurrence of light breakage and release of light breakage of the through node are the same as those in the eleventh embodiment, for example.

  According to the present embodiment described above, the same effect as that of the eleventh embodiment can be obtained, and the ATT amount fixing control 2 can be continuously performed for an optimum time. Can be converged to.

FIG. 1 is a principle block diagram of the present invention; FIG. 2 is a diagram for explaining the principle of the present invention; FIG. 3 is a diagram for explaining the principle of the present invention; FIG. 4 is a block diagram of a node according to the first embodiment of the present invention; FIG. 5 is a flowchart of optical variable attenuation processing according to the first embodiment of the present invention; FIG. 6 is a diagram for explaining the operation of each node at the time of failure recovery; FIG. 7 is a diagram for explaining the operation of each node at the time of failure recovery; FIG. 8 is a diagram for explaining the operation of each node at the time of failure recovery; FIG. 9A is a diagram showing the time change of the attenuation amount of the variable optical attenuator at each node, and FIG. 9B is a diagram showing the time change of the optical level of the output optical signal of the variable optical attenuator at each node; FIG. 10A is a flowchart of failure detection processing according to the second embodiment of the present invention, and FIG. 10B is a flowchart of optical variable attenuation control processing according to the second embodiment of the present invention; FIG. 11A is a diagram showing the time change of the attenuation amount of the variable optical attenuator at each node; FIG. 11B is a diagram showing the time change of the optical level of the output optical signal of the variable optical attenuator at each node; FIG. 12 is a flowchart of failure detection processing according to the third embodiment of the present invention; FIG. 13 is a diagram for explaining the operation of each node at the time of failure; FIG. 14A is a diagram showing the time change of the attenuation amount of the variable optical attenuator of the add node, and FIG. 14B is a diagram showing the time change of the optical level of the output optical signal of the variable optical attenuator of the add node; FIG. 15 is a diagram showing the configuration of an add node; FIG. 16 is a flowchart of instantaneous interruption control processing according to the fourth embodiment of the present invention; FIG. 17A is a diagram illustrating an operation when an optical signal is momentarily interrupted in the instantaneous interruption control process, FIG. 17B is a diagram illustrating an operation when an optical signal is momentarily interrupted in the instantaneous interruption control process, and FIG. Is a diagram showing an operation when an optical signal interruption occurs in the control processing at the moment of interruption; FIG. 18A is a diagram showing a change over time of the attenuation amount of the variable optical attenuator at each node by the control processing at the momentary interruption, and FIG. 18B is an optical level of the output optical signal of the variable optical attenuator at each node by the control processing at the momentary interruption. Figure showing time change; FIG. 19A is a diagram showing a time change of the attenuation amount of the variable optical attenuator at each node by the control processing at the momentary interruption, and FIG. 19B is an optical level of the output optical signal of the variable optical attenuator at each node by the control processing at the momentary interruption. Figure showing time change; FIG. 20 is a flowchart of control processing at momentary interruption according to the fifth embodiment of the present invention; FIG. 21A is a diagram showing a time change of the attenuation amount of the variable optical attenuator at each node by the control processing at the momentary interruption, and FIG. 21B is an optical level of the output optical signal of the variable optical attenuator at each node by the control processing at the momentary interruption. Figure showing time change; FIG. 22A is a diagram showing a change over time in the attenuation amount of the variable optical attenuator at each node by the instantaneous interruption control process, and FIG. 22B is an optical level of the output optical signal of the variable optical attenuator at each node by the instantaneous interruption control process. Figure showing time change; FIG. 23 is a diagram for explaining a method of acquiring a fixed attenuation value; FIG. 24 is a block diagram of a node according to the sixth embodiment of the present invention; 25 is a block diagram of the control circuit in FIG. FIG. 26 is an operation flowchart of the control circuit in the add node; FIG. 27 is an operation flowchart of the control circuit in the through node; FIG. 28 is a diagram for explaining the operation in the normal state; FIG. 29 is an operation explanatory diagram when a failure occurs; FIG. 30 is an operation explanatory diagram immediately after the failure recovery; FIG. 31 is an operation explanatory diagram in a normal state (after recovery); FIG. 32 is a diagram showing the amount of optical attenuation ATT at the add node; FIG. 33 is a diagram showing the VOA output level at the add node; FIG. 34 is a diagram showing the amount of optical attenuation ATT in the through node; FIG. 35 shows the VOA output level at the through node; FIG. 36 is a block diagram of a node according to the seventh embodiment of the present invention; FIG. 37 is a diagram showing the amount of optical attenuation ATT at the add node and through node; FIG. 38 is a diagram showing VOA input levels at an add node and a through node; FIG. 39 is a diagram showing VOA output levels at an add node and a through node; FIG. 40 is a block diagram of a node according to the eighth embodiment of the present invention; FIG. 41 is an operation flowchart of the control circuit in the add and through nodes; FIG. 42 is a diagram showing the amount of optical attenuation ATT in add nodes and through nodes; FIG. 43 is a diagram showing VOA input levels at an add node and a through node; 44 is a diagram showing VOA output levels at the add node and the through node; FIG. 45 is a diagram showing the amount of optical attenuation ATT in add nodes and through nodes; FIG. 46 is a diagram showing VOA input levels at an add node and a through node; FIG. 47 is a diagram showing VOA output levels at an add node and a through node; FIG. 48 is a block diagram of a node according to the ninth embodiment of the present invention; FIG. 49 is an operation flowchart of the control circuit in the add and through nodes; FIG. 50 is a diagram showing the amount of optical attenuation ATT at the add node and through node; FIG. 51 is a diagram showing VOA input levels at an add node and a through node; FIG. 52 is a diagram showing VOA output levels at an add node and a through node; FIG. 53 is an operation explanatory diagram in a normal state; FIG. 54 is an operation explanatory diagram when a failure occurs; FIG. 55 is an operation explanatory diagram immediately after the failure recovery; FIG. 56 is a diagram for explaining the operation in the normal state (after recovery); FIG. 57 is a block diagram of a node according to the tenth embodiment of the present invention; FIG. 58 is an operation flowchart of the control circuit in the add and through nodes; FIG. 59 is a diagram showing the amount of optical attenuation ATT at the add node and through node; FIG. 60 is a diagram showing VOA output levels at an add node and a through node; 61 is an operation explanatory diagram in a normal state; FIG. 62 is an operation explanatory diagram when a failure occurs; FIG. 63 is an operation explanatory diagram immediately after failure recovery; FIG. 64 is a diagram for explaining the operation in the normal state (after recovery); FIG. 65 is a block diagram of a node according to the eleventh embodiment of the present invention; FIG. 66 is an operation flowchart of the control circuit in the add node; FIG. 67 is an operation flowchart of the control circuit in the through node; FIG. 68 is an operation flowchart of the control circuit in the through node; FIG. 69 is a diagram showing the amount of optical attenuation ATT at the add node; FIG. 70 shows a VOA output level at the add node; FIG. 71 is a diagram showing the amount of optical attenuation ATT in the through node; 72 is a diagram showing the VOA output level at the through node; FIG. 73 is a diagram showing the amount of optical attenuation ATT at the add node; FIG. 74 is a diagram showing the VOA output level at the add node; FIG. 75 is a diagram showing the amount of optical attenuation ATT in the through node; FIG. 76 is a diagram showing the VOA output level at the through node; FIG. 77 is a block diagram of a node according to the twelfth embodiment of the present invention; FIG. 78 is an operation flowchart of the control circuit in the add node; FIG. 79 is a diagram showing the amount of optical attenuation ATT at an add node; FIG. 80 is a diagram showing the VOA input level at the add node; FIG. 81 is a diagram showing the VOA output level at the add node; FIG. 82 is a diagram showing the amount of optical attenuation ATT at the add node; FIG. 83 shows the VOA output level at the add node; FIG. 84 is a block diagram of a node according to the thirteenth embodiment of the present invention; FIG. 85 is an operation flowchart of the control circuit in the add node and through; FIG. 86 is an operation flowchart of the control circuit in the add node according to the fourteenth embodiment of the present invention; FIG. 87 is a block diagram of a conventional node; 88 is a diagram for explaining the operation in the conventional normal state; FIG. 89 is a diagram for explaining the operation when a conventional failure occurs.

Claims (27)

An optical level control method for adjusting the level of an input optical signal with a variable optical attenuator and controlling the output level of the variable optical attenuator to be a constant value,
Detecting a signal break from a decrease in the input signal light level of the variable optical attenuator,
When the signal loss is detected, the attenuation of the variable optical attenuator is set to a fixed value set in advance,
An optical level control method comprising: controlling the output level of the variable optical attenuator to be a constant value after a predetermined time has elapsed since detection of the signal interruption . An optical level control method for adjusting the level of an input optical signal with a variable optical attenuator and controlling the output level of the variable optical attenuator to be a constant value,
Detecting a signal break from a decrease in the input optical signal level of the variable optical attenuator ,
An optical level control method characterized by holding and controlling the attenuation of the variable optical attenuator immediately after detecting the signal interruption. A node device constituting a network having a work route and a protection route,
A demultiplexer for demultiplexing an input wavelength multiplexed optical signal for each wavelength;
A variable optical attenuator provided for each demultiplexed wavelength;
A branching device for branching the output of the variable optical attenuator;
A multiplexer that multiplexes one optical signal branched for each wavelength;
A monitor PD for detecting the optical level of the other branched optical signal;
A control circuit for adjusting a level of an optical signal output from the variable optical attenuator to a constant value according to the detected light level;
When a failure occurs in the work route, the control circuit sets a fixed attenuation amount in the variable optical attenuator using a protection instruction or a failure notification from a node device that detects the failure as a trigger,
Thereafter, the level of the optical signal output from the variable optical attenuator is adjusted to a constant value. The control circuit sets a fixed attenuation amount in the variable optical attenuator using a protection instruction or a failure notification from a node device that detects the failure as a trigger when a failure occurs in the work route,
Wherein the second trigger receiving from the detected node device failure, the variable optical attenuator at the output node device according to claim 3, wherein adjusting the level of the optical signal constant value. In a node device of an optical network that adjusts the level of a wavelength-multiplexed optical signal for each wavelength with a variable optical attenuator, and controls the output level of the variable optical attenuator to be a constant value,
Fixed attenuation amount setting means for receiving a predetermined trigger caused by a failure and setting the attenuation amount of the variable optical attenuator to a fixed value set in advance;
Timer means for starting the control operation of the control circuit after a predetermined time has elapsed,
In an add node that inputs an optical signal to the optical network, when a predetermined trigger due to the failure is received, forced control that forcibly starts the control operation of the control circuit by disabling the fixed attenuation setting means A node device comprising operation control means. In a node device of an optical network that adjusts the level of an input optical signal with a variable optical attenuator and controls it with a control circuit so that the output level of the variable optical attenuator becomes a constant value.
A signal break detection means for detecting a signal break from a decrease in the optical signal level;
Attenuation amount holding means for holding the attenuation amount of the variable optical attenuator when the signal interruption is detected,
The node device according to claim 1, wherein when the signal interruption is detected, the held attenuation amount is set in the variable optical attenuator. After setting the held attenuation amount in the variable optical attenuator, the control circuit starts a second control operation for starting a control operation for adjusting the output level of the variable optical attenuator to be constant when the signal interruption is released. 7. The node device according to claim 6 , further comprising means. An attenuation amount increasing means is provided for setting the held attenuation amount in the variable optical attenuator and increasing the attenuation amount set in the variable optical attenuator to a predetermined value after a predetermined time has elapsed. The node device according to claim 6 or 7 . The add node that inputs an optical signal to the optical network includes a forced attenuation increasing means that forcibly operates the attenuation increasing means with the attenuation holding means not operating when the signal disconnection is detected. The node device according to claim 8 . Input a dummy optical signal from the add node that inputs the optical signal to the optical network,
2. The optical level control method according to claim 1, wherein the fixed value is obtained by controlling the output level of the variable optical attenuator to be a constant value at each node constituting the optical network. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A light level control device having a plurality of control units for automatically controlling the attenuation amount,
Comprising a detector for detecting light breakage and light break release of the optical input signal of the variable optical attenuator;
When the detection unit detects the light break, the control unit performs a first attenuation amount fixed control so that the attenuation amount becomes a first predetermined value, and when the detection unit detects the light break release, A light level control apparatus, wherein the second attenuation amount is fixedly controlled so that the attenuation amount becomes a second predetermined value, and then the control is shifted to the automatic control. The variable optical attenuator for attenuating the optical input signal of each wavelength of the wavelength multiplexed signal by a variable attenuation amount, and the attenuation so that the optical output level of the variable optical attenuator becomes a target level in a normal state where the optical input signal is normal. A light level control device having a control unit for automatically controlling the amount,
Comprising a detector for detecting light breakage and light break release of the optical input signal of the variable optical attenuator;
When the detection unit detects the light break, the control unit performs attenuation fixed control with an attenuation amount immediately after the light break, and when the detection unit detects the light break release, the control unit shifts to the automatic control. A light level control apparatus characterized by the above. The variable optical attenuator for attenuating the optical input signal of each wavelength of the wavelength multiplexed signal by a variable attenuation amount, and the attenuation so that the optical output level of the variable optical attenuator becomes a target level in a normal state where the optical input signal is normal. A light level control device having a control unit for automatically controlling the amount,
The control unit performs automatic control in a long cycle so that the attenuation amount does not become a predetermined value or less within a time predicted to be required from the time when the optical input signal is interrupted to the time when the optical input signal is released. A light level control device. The variable optical attenuator for attenuating the optical input signal of each wavelength of the wavelength multiplexed signal by a variable attenuation amount, and the attenuation so that the optical output level of the variable optical attenuator becomes a target level in a normal state where the optical input signal is normal. A light level control device having a control unit for automatically controlling the amount,
Comprising a detector for detecting light breakage and light break release of the optical input signal of the variable optical attenuator;
When the detection unit detects the light break, the control unit has the variable optical attenuator having an attenuation amount of a second adjustment speed different from the first adjustment speed that converges to the target level in the automatic control. The light level control device is configured to shift to the automatic control when the detection unit detects the light break release. The second adjustment speed is slower than the first adjustment speed, and the amount of attenuation is less than or equal to a certain level within a time period that is expected to be required from the time when the optical input signal is interrupted until the optical interruption is released. 15. The light level control device according to claim 14 , wherein the light level control device is not. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A light level control device having a plurality of control units for automatically controlling the attenuation amount,
A plurality of detection units for detecting light breakage and light break release of the optical input signal of each variable optical attenuator;
A timer that times out when measuring a certain time,
When the detection unit detects the light break, the control unit activates the timer and controls the amount of attenuation fixed by an attenuation amount immediately after the light break, and before the timer times out, the detection unit When the light break release is detected, the process shifts to the automatic control. When the detection unit does not detect the light break release before the timer times out, the attenuation amount fixing control is performed until the timer times out. Then, after the time-out, the light level control device shifts to the automatic control. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A light level control device having a plurality of control units for automatically controlling the attenuation amount,
A plurality of detection units for detecting light breakage and light break release of the optical input signal of each variable optical attenuator;
A timer that times out when measuring a certain time,
When the detection unit detects the light break, the control unit starts the timer and performs the automatic control until the timer times out,
When the detection unit does not detect the cancellation of the light break before the timer times out, a first attenuation amount fixing control is performed so that the attenuation amount becomes a first predetermined value after the timer times out, and then the When the detection unit detects the light break cancellation, the light level control device shifts to the automatic control after performing a second attenuation amount fixed control so that the attenuation amount becomes a second predetermined value. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A light level control device having a plurality of control units for automatically controlling the attenuation amount,
A plurality of detection units for detecting light breakage and light break release of the optical input signal of each variable optical attenuator;
A timer that times out when measuring a certain time,
The control unit starts the timer when the detection unit detects the light break, performs long-period automatic level control so that the optical output level of the variable optical attenuator becomes the target level,
When the detection unit does not detect the light break release before the timer times out, the long period automatic level control is performed until the timer times out, and then the attenuation amount after the timer times out A first attenuation amount fixed control so that the first predetermined value is set, and then the second attenuation amount fixed control is performed so that the attenuation amount becomes the second predetermined value when the detection unit detects the light break release,
The long-period automatic level control is characterized in that the amount of attenuation of the variable optical attenuator does not fall below a certain level before the timer times out. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A wavelength division multiplexing optical network composed of a plurality of optical node devices having a plurality of control units for automatically controlling the attenuation amount,
When the own node is an add node that adds an optical input signal from a subscriber side to the wavelength division multiplexed signal, a first detection unit provided in the add node that detects optical interruption and cancellation of optical interruption of the optical input signal;
When the own node is a through node that passes through an optical input signal wavelength-multiplexed with the wavelength-multiplexed signal from the subscriber side, it is provided in the through node that detects optical interruption and cancellation of the optical interruption of the optical input signal. A second detection unit,
The control unit provided in the add node performs a first attenuation amount fixed control so that the attenuation amount becomes a first predetermined value when the first detection unit detects the light interruption, and the first detection unit When detecting the light break cancellation, the second attenuation amount fixed control is performed so that the attenuation amount becomes a second predetermined value, and then the automatic control is performed.
When the second detection unit detects the light break, the control unit provided in the through node performs a third attenuation amount fixing control with an attenuation amount immediately after the light break, and the light break release is detected. A wavelength division multiplexing optical network, wherein the automatic control is shifted to. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A wavelength division multiplexing optical network composed of a plurality of optical node devices having a plurality of control units for automatically controlling the attenuation amount,
When the own node is an add node that adds an optical input signal from a subscriber side to the wavelength division multiplexed signal, a first detection unit provided in the add node that detects optical interruption and cancellation of optical interruption of the optical input signal;
When the own node is a through node that passes through an optical input signal wavelength-multiplexed with the wavelength-multiplexed signal from the subscriber side, a second detection provided in the through node that detects optical interruption of the optical input signal And comprising
The controller provided in the add node has a second adjustment speed different from a first adjustment speed that causes the attenuation to converge to the target level in the automatic control when the first detection unit detects the light break. Controlling the variable optical attenuator with the amount of attenuation, when the detection unit detects the light break cancellation, transition to the automatic control,
The control unit provided in the through node has a fourth adjustment speed different from a third adjustment speed at which the attenuation amount converges to the target level in the automatic control when the second detection unit detects the light break. The variable optical attenuator is controlled by an attenuation amount of the wavelength multiplex optical network, and when the second detector detects the release of the light break, the automatic multiplexing control is performed. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength included in the wavelength multiplexed signal by a variable attenuation amount, and the optical output level of the variable optical attenuator is a target level in a normal state where the optical input signal is normal. A wavelength division multiplexing optical network composed of a plurality of optical node devices having a plurality of control units for automatically controlling the attenuation amount,
Each of the node devices that transmits failure information indicating optical interruption of the optical input signal of the variable optical attenuator and failure cancellation information indicating optical interruption cancellation to the optical transmission line, and receives the failure information and failure cancellation information from the optical transmission line Comprising the control device provided in
The control unit provided in an add node that adds an optical input signal from a subscriber side to the wavelength multiplexed signal is the failure information indicating the optical interruption of the optical input signal of the variable optical attenuator to be controlled. In some cases, the variable optical attenuator is controlled with an attenuation amount of a second adjustment speed different from the first adjustment speed for the attenuation amount to converge to the target level in the automatic control, and the failure information is cleared by the failure release information. Transition to the automatic control,
The control unit provided in a through node through which an optical input signal wavelength-multiplexed with the wavelength-multiplexed signal from the subscriber side transmits a light interruption of the optical input signal of the variable optical attenuator to be controlled. The variable optical attenuator is controlled with an attenuation amount of a fourth adjustment speed different from a third adjustment speed that causes the attenuation amount to converge to the target level in the automatic control when the failure information indicates, A wavelength division multiplexing optical network, wherein when the failure information is cleared, transition is made to the automatic control. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength included in the wavelength multiplexed signal by a variable attenuation amount, and the optical output level of the variable optical attenuator is a target level in a normal state where the optical input signal is normal. A wavelength division multiplexing optical network composed of a plurality of optical node devices having a plurality of control units for automatically controlling the attenuation amount,
Each of the node devices that transmits failure information indicating optical interruption of the optical input signal of the variable optical attenuator and failure cancellation information indicating optical interruption cancellation to the optical transmission line, and receives the failure information and failure cancellation information from the optical transmission line Comprising the control device provided in
The control unit provided in an add node that adds an optical input signal from a subscriber side to the wavelength multiplexed signal is the failure information indicating the optical interruption of the optical input signal of the variable optical attenuator to be controlled. When the failure information is generated, the fixed attenuation amount control is performed with the attenuation amount immediately after the occurrence of the failure information is detected, and when the failure information is cleared by the failure release information, transition to the automatic control is performed.
The control unit provided in a through node through which an optical input signal wavelength-multiplexed with the wavelength-multiplexed signal from the subscriber side transmits a light interruption of the optical input signal of the variable optical attenuator to be controlled. When the failure information is indicated, the fixed attenuation amount control is performed with the attenuation amount immediately after the occurrence of the failure information is detected, and when the failure information is cleared by the failure release information, the control shifts to the automatic control. A wavelength division multiplexing optical network. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A wavelength division multiplexing optical network composed of a plurality of optical node devices having a plurality of control units for automatically controlling the attenuation amount,
When the own node is an add node that adds an optical input signal from a subscriber side to the wavelength division multiplexed signal, a first detection unit provided in the add node that detects optical interruption and cancellation of optical interruption of the optical input signal;
When the own node is a through node that passes through an optical input signal wavelength-multiplexed with the wavelength-multiplexed signal from the subscriber side, it is provided in the through node that detects optical interruption and cancellation of the optical interruption of the optical input signal. A second detection unit;
A timer provided in the through node that times out when measuring a certain time; and
The control unit provided in the add node performs a first attenuation amount fixed control so that the attenuation amount becomes a first predetermined value when the first detection unit detects the light interruption, and the first detection unit When detecting the light break cancellation, the second attenuation amount fixed control is performed so that the attenuation amount becomes a second predetermined value, and then the automatic control is performed.
When the second detection unit detects the light break, the control unit provided in the through node activates the timer to perform a third attenuation fixed control with an attenuation immediately after the light break, When the second detection unit detects the light break release before the timer times out, the state shifts to the automatic control, and the second detection unit detects the light break release before the timer times out. If not, the wavelength division multiplexing optical network is characterized in that the third attenuation amount fixing control is performed until the timer times out, and the automatic control is shifted to after the timeout. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A wavelength division multiplexing optical network composed of a plurality of optical node devices having a plurality of control units for automatically controlling the attenuation amount,
A first detection unit provided in the add node for detecting optical breakage of the optical input signal and release of the breakage of light when the own node is an add node for adding an optical input signal from a subscriber side to the wavelength multiplexed signal; ,
When the own node is a through node that passes through an optical input signal wavelength-multiplexed with the wavelength-multiplexed signal from the subscriber side, it is provided in the through node that detects optical interruption and cancellation of the optical interruption of the optical input signal. A second detection unit;
A first timer provided in the add node that times out when measuring a certain time;
A second timer provided in the through node that times out when measuring a predetermined time;
The control unit provided in the add node performs a first attenuation amount fixed control so that the attenuation amount becomes a first predetermined value when the first detection unit detects the light interruption, and the first detection unit When the light break release is detected, the first timer is started and the second attenuation amount is fixedly controlled so that the attenuation amount becomes a second predetermined value. After the first timer times out, the control shifts to the automatic control. And
The control unit provided in the through node activates the second timer when the second detection unit detects the light interruption, and controls a third attenuation amount fixing with an attenuation amount immediately after the light interruption. When the second detection unit detects the light break release before the timer times out, the control shifts to the automatic control, and the second detection unit releases the light break release until the second timer times out. When the second timer is not detected, the third attenuation amount fixing control is performed until the second timer times out, and the automatic control is shifted to after the timeout. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A wavelength division multiplexing optical network composed of a plurality of optical node devices having a plurality of control units for automatically controlling the attenuation amount,
When the own node is an add node that adds an optical input signal from a subscriber side to the wavelength division multiplexed signal, a first detection unit provided in the add node that detects optical interruption and cancellation of optical interruption of the optical input signal;
When the own node is a through node that passes through an optical input signal wavelength-multiplexed with the wavelength-multiplexed signal from the subscriber side, it is provided in the through node that detects optical interruption and cancellation of the optical interruption of the optical input signal. A second detection unit,
A timer provided in the add node that times out when measuring a certain time,
The control unit provided in the add node performs a first attenuation amount fixed control so that the attenuation amount becomes a first predetermined value when the first detection unit detects the light interruption, and the first detection unit When the light break release is detected, the timer is started and the second attenuation amount is fixed and controlled so that the attenuation amount becomes a second predetermined value. After the timer times out, the control shifts to the automatic control.
When the second detection unit detects the light break, the control unit provided in the through node performs a third attenuation amount fixing control with an attenuation amount immediately after the light break, and the failure release information causes the failure. When the information is cleared, the wavelength division multiplexing optical network is shifted to the automatic control. A plurality of variable optical attenuators for attenuating an optical input signal of each wavelength of the wavelength multiplexed signal with a variable attenuation amount, and an optical output level of the variable optical attenuator at a normal state in which the optical input signal is normal A wavelength division multiplexing optical network composed of a plurality of optical node devices having a plurality of control units for automatically controlling the attenuation amount,
When the own node is a through node that passes through an optical input signal that is wavelength-multiplexed with the wavelength-multiplexed signal from the subscriber side, it is provided in the through node that detects optical interruption and cancellation of the optical interruption of the optical input signal. A detection unit;
A first timer provided in the through node that times out when timed for a fixed time,
When the detection unit detects the light break, the control unit provided in the through node performs the automatic control until the first timer expires after starting the first timer. When the detection unit has not detected the light break release before the timer times out, the first attenuation amount is fixedly controlled so that the attenuation amount becomes a first predetermined value after the first timer times out, A wavelength division multiplexing optical network characterized in that when the detecting unit detects the cancellation of the light break, the second attenuation amount is fixedly controlled so that the attenuation amount becomes a second predetermined value, and then the automatic control is performed. A second detection unit for detecting light breakage and light breakage cancellation of the optical input signal provided in an add node where the own node adds the optical input signal from the subscriber side to the wavelength division multiplexed signal; A second timer provided in the add node, and the control unit provided in the add node activates the second timer and detects the second timer when the second detection unit detects the light interruption. The automatic control is performed until two timers time out, and when the second detection unit does not detect the cancellation of the light break until the second timer times out, the decay is performed after the second timer times out. The third attenuation amount fixing control is performed so that the amount becomes a third predetermined value, and the fourth attenuation value fixing control is performed so that the attenuation amount becomes the fourth predetermined value when the second detection unit detects the light break release. WDM optical network according to claim 26, wherein the transition to the automatic control after.

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