JP4966891B2 - Optical transmission equipment - Google Patents

Description

  The present invention relates to an optical transmission apparatus such as a WDM (Wavelength Division Multiplexing) apparatus or an OADM (Optical Add / Drop Multiplexer) apparatus, and more particularly to an optical transmission apparatus that keeps a record of fluctuation of an optical level monitor as a history.

  In recent years, broadband lines such as the Internet have spread to ordinary households, and the demand for lines has been increasing mainly for IP traffic. With such an increase in line demand, the depletion of optical fiber core lines that transmit these broadband lines has been called out. As a result, the major theme of the optical transmission apparatus in the metro network or the core network is how many various lines including the existing network can be accommodated in one optical fiber.

  Furthermore, in the optical transmission apparatus, a 10 Gbit / sec class line such as a line speed of 10 GbE is mainstream, and it is difficult to increase the fiber accommodation efficiency by electrical multiplexing. Therefore, the introduction of optical multiplex transmission devices such as WDM devices and OADM devices has been progressing in recent years.

  Such an optical multiplex transmission apparatus can perform large-capacity transmission. On the other hand, when a failure occurs in a multiplex section, the accommodated line has a large capacity and has a great influence. Until now, in a transmission apparatus using a SONET / SDH frame, the SONET / SDH frame is terminated at each node, and the nodes can be sufficiently monitored by the error detection function of the SONET / SDH frame.

  However, since an optical transmission device such as a WDM device or an OADM device is a multi-stage relay system using light, the presence or absence of a failure in the relay section can be monitored only by monitoring the optical level. The function of monitoring the optical level and leaving it as a history is defined by Telcordia and ITU-T for both SONET / SDH. These regulations only leave a history once every 15 minutes and once a day, and if the level changes during that time and a failure occurs in the accommodated line, the history of the change does not remain and the failure cause and failure section analysis is performed. It is in trouble. Against this background, in recent years, there has been an increasing demand for higher functionality in monitoring faults between nodes in an optical transmission apparatus.

  Patent Document 1 discloses an optical transmission system including means for detecting quality degradation of an optical signal by quality degradation detection means installed in an optical terminal station and the like, and transferring it as a monitoring signal to an optical repeater. Yes. Here, the optical repeater is an optical transmission system provided with level fluctuation detecting means for detecting the level of an optical signal and level fluctuation storing means for storing the detected information.

  In Patent Document 2, in the determination circuit 154, when the light reception level at the light receiving element 122 is lower than the reference level, the rate of decrease in the light reception level with respect to the average value for the past 10 days and the subsequent fixed period (for example, 30 minutes). A transmission failure determination device is disclosed that determines a decrease factor of a light reception level based on a mode of vertical fluctuation of the light reception level.

Non-Patent Document 1 defines a wavelength grid that is a spectrum arrangement of optical signals that can be used in a WDM transmission system.
Further, as a failure monitoring function in an optical transmission apparatus such as a WDM apparatus or an OADM apparatus, an optical interruption and an optical level history function (Performance Monitoring) are generally used and are defined in Non-Patent Document 2.

JP 2005-318567 A JP 2004-172741 A IUT-T G.694.1 Telcordia GR-253-CORE

  Since the light break detection defined in Non-Patent Document 2 does not give a false alarm, it is common to set a threshold value at the lower limit at which the function of the light receiving unit cannot be satisfied. In addition, the light interruption is notified when the failure continues for 2.5 ± 0.5 seconds or more, and an instantaneous failure below that cannot be displayed as an alarm on the alarm display terminal. The optical level history function is a function that constantly monitors the optical level and keeps the numerical value as a history. However, since it is recorded at a minimum period of 15 minutes, if a line failure occurs due to a level fluctuation during that period, The level at which the failure occurred cannot be left as a history.

Non-Patent Document 2 also shows a function of setting a threshold in advance as the light level history function and notifying as an alarm when the threshold is below or exceeded. However, it is difficult to uniquely determine the light level that affects the line, and the light level that affects each line varies depending on the speed of the line, variations in optical components used, and the like. Therefore, the threshold value is generally set to a level that reliably affects the line in order to prevent false alarms. As a result, even when a light level fluctuation that affects a certain line occurs, there are almost no cases where the alarm is notified.
In order to solve the higher problems, but also conceivable to leave always light level monitor result recorded history, realized amount recording becomes huge is not realistic.

The above-mentioned problems are caused by the fact that the failure below the alarm detection protection time or the light level fluctuation that does not reach the alarm detection level or the light level threshold is not recorded. In order to solve this, it can be solved by an optical transmission device that records the maximum and minimum levels fluctuated in a predetermined period, and also the time thereof. The optical signals of the multiplexed signals are optically amplified in a lump, and the monitoring unit of the optical level of the wavelength multiplexed optical signal at the receiving end of the wavelength multiplexed optical signal, the maximum value and minimum value of the optical level in a predetermined period, and the generation time thereof A storage unit for recording and a monitoring control unit are provided, and this monitoring control unit can be achieved by an optical transmission device that reads the maximum value, the minimum value, and the occurrence time from the storage unit for each predetermined period.

  Further, the wavelength multiplexed signal is optically amplified and transmitted in a lump, and the optical level monitor unit of the wavelength multiplexed optical signal amplified at the transmission end of the wavelength multiplexed signal, and the maximum and minimum values of the optical level in a predetermined period A storage unit for recording values and their generation times, and a monitoring control unit are provided, and the monitoring control unit reads the maximum value, the minimum value, and the generation time from the storage unit for each predetermined period. Can be achieved.

  By recording the maximum and minimum values and the time of the light level for a certain period, it is easy for the maintenance person to identify the section where the failure occurred for a line failure without detecting a light interruption alarm or exceeding the light level threshold. It becomes possible to do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 4 using examples. The same reference numerals are assigned to substantially the same parts, and the description will not be repeated. Here, FIG. 1 is a block diagram of an optical transmission system. FIG. 2 is a block diagram of the OADM device. FIG. 3 is a block diagram for explaining the optical line branching unit and the optical line inserting unit. FIG. 4 is a block diagram for explaining the light level monitoring unit and the monitoring control unit. In this embodiment, an OADM device will be described on behalf of an optical multiplex transmission device, but the optical multiplex transmission device is not limited to an OADM device.

  In FIG. 1, an optical transmission system 500 includes three OADM devices 100, two client devices 200 accommodated in the OADM devices 100-1 and 100-3, and the OADM devices 100-1 and 100-2. The relay apparatus 300 is provided. An inter-office optical transmission line (optical fiber) 50 is connected between the OADM device 100 and the relay device 300.

  The optical signal transmitted from the client apparatus 200-1 is inserted into the multiplexed optical signal by the OADM apparatus 100-1, and branched from the multiplexed optical signal by the 0ADM apparatus 100-3 via the relay apparatus 300 and the 0ADM apparatus 100-2. And received by the client device 200-2.

  The OADM device 100 includes a client line accommodating unit 170 connected to the client device 200, a received optical amplification unit 120 that optically amplifies the received multiplexed optical signal, and an optical line branching unit that branches the branched wavelength and the through wavelength. 130, an optical line inserting unit 140 that multiplexes the wavelength to be passed and the wavelength to be inserted, and a transmission optical amplifying unit 150 that optically amplifies the multiplexed optical signal output from the optical line inserting unit 140. The repeater 300 includes a repeater optical amplifier 310.

  In FIG. 2, the received light amplifying unit 120 accommodates the inter-station optical transmission line 50-1 and amplifies the optical level of the input optical multiplexed signal to a specified level. The optical line branching unit 130 accommodates the optical multiplexed signal from the received optical amplifying unit 120, and a line that drops by the OADM device (node) 100 and a line that passes through the node without being dropped according to the setting from the maintenance terminal 400. To separate.

  The optical line insertion unit 140 inserts / combines the optical signal from the client line accommodation unit 170 into the optical signal from the optical line branching unit 130 and outputs it to the transmission optical amplification unit 150. The transmission optical amplification unit 150 amplifies the optical level of the optical multiplexed signal input from the optical line insertion unit 140 to a prescribed optical level, and outputs the amplified optical level to the inter-station optical transmission line 50-2.

  The client line accommodation unit 170 is connected to the client device 200, the optical line branching unit 130, and the optical line insertion unit 140, and accommodates an optical signal input from the client device 200 in an OTN frame, and ITU-T G.694.1. The wavelength is converted to a wavelength for DWDM (Dense Wavelength Division Multiplexing) defined in, and transmitted to the optical line insertion unit 140. The client line accommodating unit 170 terminates the OTN frame of the optical signal having the DTN wavelength OTN frame input from the optical line branching unit 130, and converts it into optical power and optical wavelength for connection with the client device 200. And output to the client device 200.

  The monitoring control unit 190 is connected to the function units 120 to 170 in the apparatus and the maintenance terminal 400, and notifies the maintenance terminal 400 of the monitoring results including the optical level monitors of the function units 120 to 150. The monitoring control unit 190 also performs necessary settings for the function units 120 to 170 in accordance with control from the maintenance terminal 400. The maintenance terminal 400 is connected to the monitoring control unit 190 and displays the monitoring result from the monitoring control unit 190. The maintenance terminal 400 also sets setting information from the maintenance person in the monitoring control unit 190.

  Optical level monitoring units 110-1 and 110-2 are arranged at the input unit and the output unit of the received light amplification unit 120, respectively. Optical level monitor units 110-3 and 110-4 are arranged at the input unit and through output unit of the optical line branch unit 130, respectively. Optical level monitoring units 110-5 and 110-6 are arranged in the through input unit and the output unit of the optical line insertion unit 140, respectively. Optical level monitoring units 110-7 and 110-8 are arranged in the input unit and the output unit of the transmission light amplification unit, respectively.

  Note that the OADM device 100 may include only the optical level monitoring unit 110-1 of the reception light amplification unit 120 and the optical level monitoring unit 110-8 of the transmission light amplification unit. Further, the OADM device 100 may be only the optical level monitor unit 110-1 of the reception light amplification unit 120 or only the optical level monitor unit 110-8 of the transmission light amplification unit.

As shown in FIG. 2, the optical level monitoring unit 110 is placed at a point where the functional units 120 to 150 are optically connected to the other functional units 120 to 150. Of course, in the function units 120 to 150, a plurality of monitor points may be placed in the function units 120 to 150 for internal diagnosis of the function units 120 to 150. The monitoring result in each light level monitoring unit 110 is notified to the maintenance terminal 400 via the monitoring control unit 190.
1 and 2, only the signal direction from the inter-office optical transmission line 50-1 to the inter-office optical transmission line 50-2 is shown, but a functional unit in the reverse direction may be provided in the same apparatus. Good.

  In FIG. 3, the optical line branching unit 130 includes a 1: 1 optical branching unit 131 and a wavelength demultiplexing unit 135-1. The 1: 1 optical branching unit 131 branches the wavelength multiplexed optical signal into two. One through optical signal of the two branches is transmitted to the optical line insertion unit 140. The other drop optical signal is wavelength-separated into M wavelengths by the wavelength demultiplexing unit 135-1, and a part thereof is transmitted to the client line accommodating unit 170.

  On the other hand, the optical line insertion unit 140 includes a wavelength demultiplexing unit 135-2, an optical selector unit 142, and a wavelength multiplexing unit 145. The wavelength separation unit 135-2 separates the through optical signal into M wavelengths. The optical selector unit 142 is M two-input one-output (2 × 1) switches, and selects one of the output of the wavelength demultiplexing unit 135-1 and the add optical signal, and light of M wavelengths having different wavelengths. The signal is transmitted to the wavelength multiplexing unit 145. The wavelength multiplexing unit 145 wavelength-multiplexes the M wavelength optical signal.

  Note that the branching ratio of the 1: 1 light branching section 131 is not limited to 1: 1. The 1: 1 optical branching unit 131 and the wavelength demultiplexing unit 135-1 may be configured by a wavelength selective optical switch. Similarly, the wavelength demultiplexing unit 135-2, the optical selector unit 142, and the wavelength multiplexing unit 145 may be configured by a wavelength selective optical switch.

  4, only the optical level monitor unit 110-1 disposed at the next stage of the portion accommodating the inter-station optical transmission line 50-1 of the received optical amplifier unit 120 in FIG. 2 is connected to the monitoring control unit 190. Explain the relationship. The same applies to the other light level monitoring units 110-2 to 110-8.

  The optical level monitoring unit 110-1 includes an optical branching unit 111, an optical level monitoring result collection unit 112, and a maximum / minimum determination unit 113. The optical branching unit 111 is connected to the inter-station optical transmission line 50-1 and branches light for optical level monitoring from the optical multiplexed signal from the inter-office optical transmission line 50-1. The optical level monitor result collecting unit 112 is connected to the optical branching unit 111, monitors the optical signal intensity branched from the optical branching unit 111, and converts it into numerical information. The maximum / minimum determination unit 113 periodically collects light level numerical value information converted by the light level monitor result collection unit 112 at a relatively short period, and holds the collected numerical values and the maximum / minimum determination unit 113. Compare with the maximum and minimum values, update the values as necessary, and retain the time when updated.

  On the other hand, the monitoring control unit 190 includes a history information processing unit 191 and a maintenance terminal communication control unit 195. The history information processing unit 191 is connected to the maximum / minimum determination unit 113 and acquires the maximum value, the minimum value, and time information from the maximum / minimum determination unit 113 every certain history holding time interval (15 minutes and 1 day), Hold. The maintenance terminal communication control unit 195 manages communication control with the maintenance terminal 400.

  The OADM device 100 receives an optical multiplexed signal obtained by wavelength-multiplexing a plurality of lines from the OADM device 100 adjacent to the inter-office optical transmission line 50-1. The optical multiplexed signal is optically branched to the main signal line 116 and the optical monitor line 117 through the optical branching unit 111 at a ratio of N: 1 optical power. This optical branching does not separate the wavelengths but divides the light power into N: 1. Therefore, only the light power is N / (N + 1) in the main signal line without changing the signal information. Further, since it is common to minimize the loss of light on the main signal line, the value of N is a value greater than 1. N = 9 is most preferable.

  The optical multiplexed signal whose optical power is 1 / (N + 1) is input to the optical level monitor result collection unit 112. The optical level monitor result collecting unit 112 converts the optical power such as a photodiode into electrical information through an element that converts the electrical power into electrical strength, and the maximum / minimum determination unit 113 and the subsequent information processing are facilitated. Then, it is converted into digital information using an AD converter (Analog / Digital converter) or the like. Of course, the maximum / minimum determination unit 113 may process the data as electrical analog information.

  The maximum / minimum determination unit 113 includes a comparison unit 114 and two register units 115. Here, the register unit 115-1 is a register unit for a 15-minute cycle, and the register unit 115-2 is a register unit for a one-day cycle. Further, each register unit 115 has a current value register 1151, a maximum value register 1152, a minimum value register 1153, a maximum value time register 1154, and a minimum value time register 1155. Each of the registers 1151 to 1155 stores the current value, maximum value, minimum value, and maximum / minimum value of the light level detected. The maximum / minimum determination unit 113 periodically collects the monitor results to the light level monitor result collection unit 112. The shorter the collection cycle, the better. The collected light level information is stored in the current value register of the maximum / minimum determination unit 113 for each period, and at the same time, the maximum value and the minimum value stored in the maximum value register 1152 and the minimum value register 1153 in the comparison unit 114. If the light level collected from the light level monitor result collection unit 112 is larger than the maximum value, the maximum value register 1152 is updated as a new maximum value, and the value of the maximum value time register 1154 is updated to the time when the light level is collected. To do. When the light level collected from the light level monitor result collection unit 112 is small, the minimum value register 1153 is updated as a new minimum value, and further, the value of the minimum value time register 1155 is updated to the collected time.

  When the maximum value register 1152, the minimum value register 1153, the maximum value time register 1154, and the minimum value time register 1155 are cleared and no value is stored, the value of the light level collected from the light level monitor result collection unit 112 is maximized. The collection time is stored in the maximum value time register 1154 and the minimum value time register 1155 in the value register 1152 and the minimum value register 1153, respectively. When the current value register 1151, the maximum value register 1152, the minimum value register 1153, the maximum value time register 1154, and the minimum value time register 1155 are read from the history information processing unit 191 every history cycle (15 minutes and 1 day) Cleared. The trigger for clearing may be cleared by reading at a history cycle, or by a clear instruction from the history information processing unit 191.

  The history information processing unit 191 includes a history cycle timer 192, a register read control unit 193, and a history storage unit 194, and is further connected to the maintenance terminal communication control unit 195 of the monitoring control unit 109.

  The history cycle timer 192 has a timer of the history cycle (15 minutes and 1 day), and the register read control unit 193 and the maintenance terminal communication control unit 195 read from the register unit 115 to the history cycle timer 192 and perform maintenance. A notification trigger to the terminal 400 is given. The register read control unit 193 acquires the light level information from the register unit 115 for each history collection cycle based on the information of the history cycle timer 192. The acquired light level information is stored in the history storage unit 194 for each history collection period, and simultaneously sent to the maintenance terminal communication control unit 195 to be notified to the maintenance terminal 400. When a request for reading past history information is received from the maintenance terminal 400, the optical level history information for the designated time or time range is transmitted to the maintenance terminal communication control unit 195 and notified to the maintenance terminal 400. Thereby, the maintenance person can know the maximum value, the minimum value, and the time of the period for each history collection period in the past. When a current value read request is received from the maintenance terminal 400, the optical level information is acquired from the register read control unit 193 to the register unit 115, and the optical level information is sent to the maintenance terminal communication control unit 195. To be notified. Thereby, the maintenance person can know the value of the light level at the present time, the maximum value and the minimum value of the light level from the start of the current history collection period to the present time, and the time.

  Further, when a register value clear instruction is received from the maintenance terminal 400, the register read instruction is transmitted from the register read control unit 193 to the register unit 115, and the maximum value of the light level from the start of the current history collection period to the present time. Clear the minimum value and its time.

  According to the present embodiment, it is possible to leave the fluctuation value and time of the light level fluctuation, which is the main obstacle factor in the optical multiplexing section, as a history. With this function, it is possible to provide a maintenance person with information that is very effective for identifying a failure factor and a failure section when a failure such as an error occurs on a line. Moreover, if 15 minutes and 1 day are employed as the predetermined period, it is easy to use the conventional apparatus.

It is a block diagram of an optical transmission system. It is a block diagram of an OADM device. It is a block diagram explaining an optical line branch part and an optical line insertion part. It is a block diagram explaining an optical level monitor part and a monitoring control part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 50 ... Inter-station optical transmission line (optical fiber), 100 ... OADM apparatus, 110 ... Optical level monitoring part, 111 ... Optical branching part, 112 ... Optical level monitoring result collection part, 113 ... Maximum / minimum determination part, 120 ... Received light Amplifier 130 .. Optical line branching unit 131... Optical branching unit 135. Wavelength demultiplexing unit 140... Optical line insertion unit 142 142 Optical selector 145 .. Wavelength multiplexing unit 150. 190: Monitoring control unit, 191 ... History information processing unit, 195 ... Maintenance terminal communication control unit, 200 ... Client device, 300 ... Relay device, 310 ... Relay optical amplifier, 400 ... Maintenance terminal, 500 ... Optical transmission system .

Claims (3)

In an optical transmission device that receives a wavelength multiplexed optical signal and collectively amplifies the wavelength multiplexed signal,
At the receiving end of the wavelength-multiplexed optical signal, a monitoring unit for the optical level of the wavelength-multiplexed optical signal, a current value register for periodically collecting and holding the optical level from the monitoring unit, and a maximum value of the optical level are held A maximum / minimum determination unit having a maximum value register to hold and a minimum value register to hold the minimum value of the light level ;
A monitoring control unit,
The maximum / minimum determination unit compares the light level held in the current value register with the light level held in the maximum value register and the minimum value register, and the light level held in the current value register If it is greater than the light level held in the maximum value register, the value of the maximum value register is updated with the light level held in the current value register and the time when the light level is collected from the monitor unit is the maximum value. When the light level recorded in the time register and held in the current value register is smaller than the light level held in the minimum value register, the value of the minimum value register is held in the current value register. And having a comparison unit that records the time at which the light level is collected from the monitor unit in a minimum value time register, and
The monitoring control unit, for each of the predetermined periods, the light level held by the maximum value register, the time held by the maximum value time register, the light level held by the minimum value register, and the minimum value An optical transmission device characterized in that the time stored in the time register is read and stored as history information . The optical transmission device according to claim 1 ,
The optical transmission apparatus characterized in that the predetermined period is 15 minutes or one day. The optical transmission device according to claim 1 ,
The monitoring control unit transmits the history information to a maintenance terminal.

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