JP2011259129A - Optical transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission system capable of facilitating identification of a failure occurrence point.SOLUTION: The optical transmission system transmits an optical main signal via an optical transmission path between a plurality of OADM devices 10. Each of the OADM devices 10 includes: optical level monitors 16W, 16E for measuring an optical receiving level from the optical transmission path and an optical transmission level to the optical transmission path; a memory section 40 for memorizing, at every predetermined time, optical level information measured by the optical level monitors 16W, 16E; an acquiring section 41 for acquiring the optical level information of other nodes; and a history storage section 42 for storing the optical level information of each node as a history in the event that a code error is detected by transponders 14W, 14E.

Description

  The present invention relates to an optical transmission system that transmits and receives an optical signal through an optical transmission line.

  2. Description of the Related Art In recent years, with the rapid spread of the Internet, development and introduction of a wavelength division multiplexing (WDM) optical transmission system that transmits optical signals of a plurality of wavelengths all over a single optical fiber is progressing. At present, the transmission rate per wavelength is mainly from 2.4 Gbps to 10 Gbps, but a higher transmission rate such as 40 Gbps is beginning to be adopted in order to meet the ever-increasing information transmission demand.

  Since such a WDM optical transmission system is a system that relays signals in multiple stages without changing the light, the presence or absence of a failure in the transmission section is detected by monitoring the optical level of each node. In a WDM optical transmission system, generally, performance monitor information is collected at regular intervals of 15 minutes or 1 day. This performance monitor information includes the maximum value and minimum value of the light level within a certain period, and is stored at each node. When a transponder detects a code error (error) due to a decrease in the light level in the transmission section, the network maintainer checks the performance monitor information of each node near the code error detection time to determine the location of the failure. Can be identified. Patent Document 1 discloses an optical transmission apparatus in which the generation time is left as a history together with the maximum value and the minimum value for 15 minutes or one day.

JP 2009-210802 A

  However, in the conventional technology as described above, when a plurality of light level drops occur within 15 minutes or one day, it is not possible to confirm the exact relationship between the light level drop and a code error. It's not easy. In addition, since the maximum and minimum values of the optical level at each node and the history of the time of occurrence are stored in each node, if a code error occurs in a certain node, the network maintainer It was necessary to collect performance monitor information history for all nodes, and it took time to identify the location of the failure.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an optical transmission system capable of easily identifying a location where a failure has occurred.

  In order to solve the above problems, an optical transmission system according to an aspect of the present invention is an optical transmission system that transmits an optical main signal between a plurality of nodes via an optical transmission path. Each node has an optical level monitor that measures an optical reception level from the optical transmission line and an optical transmission level to the optical transmission line, and a storage unit that stores optical level information measured by the optical level monitor every predetermined time; An acquisition unit that acquires the optical level information of another node and a history storage unit that stores the optical level information of each node as a history when a code error of the optical main signal is detected.

  According to this aspect, since the history of the optical level information of each node at the time of detecting the code error is stored, the network maintainer easily confirms the relationship between the code error and the optical level with reference to the history. be able to. Also, for example, when a code error occurs in a certain node, the optical level information of each node can be collected simply by referring to the history stored in that node, so that the location of the failure can be identified quickly and easily. it can.

  The optical level information may be communicated between the nodes using a monitoring control signal having a wavelength different from that of the optical main signal.

  Each node may further include a transmission unit that transmits the optical level information of the own node stored in the storage unit to the acquisition unit of another node. In addition, each node is connected to two adjacent nodes, and the acquisition unit of each node may transfer the light level information acquired from one adjacent node to the other adjacent node. Thereby, each node can acquire the light level information of other nodes.

  The history storage unit may store the optical level information of each node in a predetermined period before and after the code error detection as a history. In this case, it is possible to identify whether a code error has occurred due to instantaneous light level fluctuations or whether a code error has occurred due to continuous light level fluctuations, and when information transfer delays occur at each node, It is possible to identify the location of failure.

  The optical level information may include a maximum value and a minimum value of the optical reception level and the optical transmission level at a predetermined time. As a result, failure analysis is possible even for instantaneous light level fluctuations.

  The acquisition unit of each node requests the optical level information from the other node when a code error of the optical main signal is detected, and the transmission unit of the other node receiving the request obtains the optical level information of the own node. You may send it. With such a configuration, unnecessary information is not transferred during normal operation, so that the load on the optical transmission line and the apparatus can be reduced.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between an apparatus, method, system, program, recording medium storing the program, etc. are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the optical transmission system which can make easy specification of the location where the failure generate | occur | produced can be provided.

It is a figure which shows the structure of the optical transmission system which concerns on embodiment of this invention. It is a figure which shows the structure of an OADM apparatus. It is a figure which shows the structure of a relay apparatus. It is a figure for demonstrating the structure of the control part of an OADM apparatus. It is a figure for demonstrating the transfer example of a specific optical level information. It is a figure which shows the specific example of light level information. It is a flowchart for demonstrating a process when the optical level information is received from another node. It is a figure which shows the example of a light level log | history. It is a figure which shows the data structure of the optical level information preserve | saved at the acquisition part of the 3rd OADM apparatus. It is a figure which shows another specific example of light level information.

  FIG. 1 is a diagram showing a configuration of an optical transmission system 100 according to an embodiment of the present invention. As shown in FIG. 1, an optical transmission system 100 includes a first OADM (Optical Add-Drop Multiplexer) device 10a, a second OADM device 10b, a third OADM device 10c, a repeater (ILA: In-Line Amplifier) 20, and the like. Is provided. These devices are connected in a ring shape using an optical transmission line 30 and constitute an optical ring network.

  In the present embodiment, as shown in FIG. 1, the devices are connected in a ring shape in the order of the second OADM device 10b, the third OADM device 10c, and the relay device 20 in the clockwise direction from the first OADM device 10a. Each device constituting the optical ring network is also called a “node”. In this embodiment, an OADM device and a relay device will be described as examples of nodes, but the types of nodes are not particularly limited.

  FIG. 2 is a diagram illustrating a configuration of the OADM apparatus. As shown in FIG. 2, the OADM device 10 includes optical amplifier units 11W and 11E, demultiplexing units 12W and 12E, switch units 13W and 13E, transponder units (TRPN) 14W and 14E, and an OSC (Optical Supervisory Channel). ) Units 15W and 15E, optical level monitor units 16W and 16E, and a control unit 17. Note that the reference numerals of the components of the OADM device 10 are “W” for those located on the west side when the upper side in FIG. 2 is north, and “E” for those located on the east side. Is attached. The OADM device 10 can communicate with a node connected to the West side and a node connected to the East side.

  The optical amplifier units 11W and 11E have functions of receiving and amplifying wavelength-multiplexed optical signals (hereinafter also referred to as WDM signals) and amplifying and transmitting WDM signals. The demultiplexing units 12W and 12E multiplex the narrow band light from the transponder units 14W and 14E and demultiplex the multiplexed light. The switch units 13W and 13E have a function of adding / dropping / through the narrowband light. The transponders 14W and 14E temporarily convert the client signal into an electrical signal, convert it into narrowband light, and convert the narrowband light into wideband light. The transponder units 14W and 14E have a function of measuring the code error of the received optical main signal. The OSC units 15W and 15E transmit and receive monitoring control signals to and from adjacent nodes. This monitoring control signal is a signal used for controlling and monitoring the apparatus. As the monitoring control signal, an optical signal having a wavelength different from that of the optical main signal is used. The optical level monitoring units 16W and 16E are located in the transmission / reception units of the optical amplifier units 11W and 11E, and determine the optical reception level of the WDM signal input to the OADM device 10 and the optical transmission level of the WDM signal output from the OADM device 10. taking measurement. In the following, “optical reception level” and “optical transmission level” will be collectively referred to as “optical level” where appropriate. The optical level monitoring units 16W and 16E can be configured using a photodiode and its driving circuit. The control unit 17 performs setting control and monitoring for each unit of the OADM device 10 and performs monitoring control communication with an adjacent node via a monitoring control signal.

  FIG. 3 is a diagram illustrating a configuration of the relay apparatus. The relay device 20 has a function of amplifying and relaying the WDM signal wavelength-multiplexed by the OADM device without electrical conversion. As shown in FIG. 3, the relay device 20 includes optical amplifier units 21W and 21E, OSC units 22W and 22E, optical level monitor units 23W and 23E, and a control unit 24. In FIG. 3, as in FIG. 2, “W” is added to the component located on the West side, and “E” is assigned to the component located on the East side.

  The optical amplifier units 21W and 21E have functions of receiving and amplifying WDM signals and amplifying and transmitting WDM signals. The OSC units 22W and 22E transmit and receive monitoring control signals to and from adjacent nodes. The optical level monitoring units 23W and 23E are located in the transmission / reception units of the optical amplifier units 21W and 21E, and determine the optical reception level of the WDM signal input to the relay device 20 and the optical transmission level of the WDM signal output from the relay device 20. taking measurement. The control unit 24 performs setting control and monitoring for each unit of the relay device 20, and performs monitoring control communication with an adjacent node via a monitoring control signal.

  FIG. 4 is a diagram for explaining the configuration of the control unit of the OADM device. As illustrated in FIG. 4, the control unit 17 of the OADM device 10 includes a storage unit 40, an acquisition unit 41, a history storage unit 42, and a transmission unit 43.

  The storage unit 40 stores the light levels detected by the light level monitoring units 16W and 16E every predetermined time (for example, 1 second). Further, the transmission unit 43 transmits the optical level information of the own node stored in the storage unit 40 to the other node 50 via the OSC units 15W and 15E.

  The acquisition unit 41 acquires the light level information transmitted as the monitoring control signal from the other node 50 via the OSC units 15W and 15E. The light level information of this other node 50 is stored in the memory of the acquisition unit 41. In addition, the acquisition unit 41 transfers the light level information acquired from one adjacent other node to the other other adjacent node via the OSC units 15W and 15E.

  The history storage unit 42 stores the optical level information of each node as a history based on the information stored in the storage unit 40 and the acquisition unit 41 when a code error of the optical main signal is detected by the transponders 14W and 14E. save. In addition, when the history of the light level information is stored, the history storage unit 42 notifies an alarm to a higher-level monitoring device (not shown).

  The network maintenance person who has confirmed the alarm notification by the host monitoring device can access the alarm notification source OADM device, refer to the history stored in the history storage unit 42, and perform the work of identifying the fault location. . For example, if a node in which a large light level fluctuation has occurred is known from the history of the light level information, it can be identified that a failure has occurred in the node or its surrounding transmission path.

  In FIG. 4, the configuration of the control unit 17 in the OADM device 10 has been described. However, the control unit 24 of the relay device 20 is substantially the same as the control unit of the OADM device 10 except that the history storage unit is not provided. It has a configuration.

  FIG. 5 is a diagram for explaining a specific example of transferring light level information. Here, an example in which the optical level information measured by the second OADM device 10b is transferred to another node will be described.

  FIG. 6 is a diagram illustrating a specific example of the light level information. The optical level information shown in FIG. 6 includes (0) transmission node name, (1) detection time, (2) optical transmission level of the East side optical amplifier unit, (3) optical reception level of the East side optical amplifier unit, (4 (1) The optical transmission level of the West side optical amplifier unit, (5) The optical reception level of the West side optical amplifier unit. Such light level information is stored in the storage unit 40 of the second OADM device 10b, for example, every second.

  The transmission unit 43 of the second OADM device 10b transmits the optical level information stored in the storage unit 40 to other adjacent nodes, that is, the first OADM device 10a and the third OADM device 10c.

  FIG. 7 is a flowchart for explaining processing when light level information is received from another node. The flowchart shown in FIG. 7 is repeatedly executed at predetermined time intervals.

  First, the acquisition unit 41 of the control unit 17 checks whether or not light level information has been received from an adjacent node (S10). If not received (No in S10), the process is temporarily terminated. On the other hand, if received (Yes in S10), the transmission source node and the detection time of the light level information are confirmed (S12).

  Next, the acquisition unit 41 confirms whether or not the received light level information is newer than the light level information stored in itself (S14). When the received light level information is older than or the same as the stored light level information (No in S14), the acquisition unit 41 discards the received light level information (S16). On the other hand, when the received light level information is newer than the stored light level information (Yes in S14), the acquisition unit 41 stores the received light level information (S18). Thereafter, the acquisition unit 41 transfers the received light level information to another adjacent node (S20). By performing the processing as described above at each node, the acquisition unit 41 of each node can accumulate the light level information of other nodes.

  The processing of the flowchart of FIG. 7 will be described with reference to a specific example of FIG. The transmission unit of the second OADM device 10b transmits the optical level information of the own node to adjacent nodes, that is, the first OADM device 10a and the third OADM device 10c at predetermined time intervals.

  The acquisition unit of the first OADM device 10a that has received the optical level information of the second OADM device 10b stores it and transfers it to the relay device 20 that is an adjacent node. Receiving the optical level information of the second OADM device 10b, the acquisition unit of the relay device 20 saves it and transfers it to the third OADM device, which is an adjacent node. Here, when the optical level information directly transmitted from the second OADM device 10b is already stored in the acquisition unit of the third OADM device 10c, the acquisition unit of the third OADM device 10c receives the second OADM device transferred from the relay device 20 Discard the light level information of 10b.

  As described above, the optical level information of the second OADM device 10b is stored in the acquisition unit of each node. The optical level information transmitted from the first OADM device 10a, the third OADM device 10c, and the relay device 20 every predetermined time is also stored in the acquisition unit of each node in the same manner.

  In the optical transmission system 100 shown in FIG. 5, for example, when a code error is detected in the transponder unit of the third OADM device 10c, the history storage unit of the third OADM device 10c is stored in the storage unit 40 and the acquisition unit 41 at that time. The optical level information of each node is stored as a history based on the stored information.

  FIG. 8 is a diagram illustrating an example of the light level history. FIG. 8 shows, as an example, an optical level history stored when a code error is detected in the transponder unit of the third OADM device 10c. The optical level history shown in FIG. 8 includes (1) error detection time, (2) detection error information, (3) optical level information of the first OADM device 10a, (4) optical level information of the second OADM device 10b, and (5). The optical level information of the third OADM device 10c and (6) the optical level information of the relay device 20 are included. (2) The detection error information includes a location where a code error is detected and occurrence / recovery information. The optical level information of each node includes the optical level information of the East side optical amplifier unit 21E and the optical level information of the West side optical amplifier unit 21W.

  In addition, when a code error is detected in the transponder unit of the third OADM device 10c and the optical level history is stored, the history storage unit of the third OADM device 10c notifies an upper monitoring device of an alarm. When the network maintenance person confirms this alarm, the network maintenance person accesses the history storage unit of the third OADM device 10c that issued the alarm, and collects the stored light level history. The network maintainer can confirm whether or not the optical level of each node is in the prescribed optical level state by referring to the optical level history. For example, when there is a large change in optical level at a certain node, it can be specified that some kind of failure has occurred in the optical transmission path around the node or its periphery.

  As described above, in the optical transmission system 100 according to the present embodiment, when a code error is detected in a certain OADM device 10, the OADM device 10 stores the optical level information of the own node and other nodes as a history. The network maintainer can confirm the optical level information of each node at the time of the code error at a time only by accessing the OADM device 10 in which the code error has occurred. Since it is not necessary to collect the light level information of each node, it is possible to quickly and easily identify the location where the failure has occurred.

  The history storage unit 42 may store the optical level information of each node in a predetermined period before and after the code error detection as a history. In this case, since the state of the light level before and after the occurrence of the code error can be confirmed, it is possible to specify whether the code error has occurred due to instantaneous light level fluctuation or whether the code error has occurred due to continuous light level fluctuation. Also, by checking the light level information over a certain period, it is possible to identify the location where the failure has occurred even when information transmission is delayed.

  Hereinafter, processing for storing the light level history as described above will be described. Here, as an example, an optical level history storage process when a code error is detected in the transponder unit of the third OADM apparatus 10c will be described. FIG. 9 shows the data structure of the light level information stored in the acquisition unit of the third OADM device 10c. In FIG. 9, each light level information includes light level information as shown in FIG.

  As shown in FIG. 9, the acquisition unit of the third OADM device 10c receives a plurality of pieces of optical level information received in the past for each of the first OADM device 10a, the second OADM device 10b, and the relay device 20 (five in FIG. 9). Holds minutes cyclically. The storage unit of the third OADM device 10c also holds the optical level information of the own node cyclically for a plurality of cases (similarly, five cases).

  When a code error is detected in the transponder unit of the third OADM device 10c, the history storage unit of the third OADM device 10c notifies the host monitoring device of an alarm and a predetermined wait time (for example, 2 seconds). After that, a history of the light level information of the own node and other nodes is created and stored based on the information stored in the acquisition unit and the storage unit. Thereby, the optical level information of each node in a predetermined period before and after the code error detection can be stored as a history.

  FIG. 10 is a diagram illustrating another specific example of the light level information. The optical level information shown in FIG. 10 includes (0) transmission node name, (1) detection time, (2) optical transmission level of the East side optical amplifier unit, (3) minimum optical transmission level of the East side optical amplifier unit, ( 4) Maximum optical transmission level of the East side optical amplifier unit, (5) Optical reception level of the East side optical amplifier unit, (6) Minimum optical reception level of the East side optical amplifier unit, and (7) Maximum of the East side optical amplifier unit. Optical reception level, (8) Optical transmission level of West side optical amplifier unit, (9) Maximum optical transmission level of West side optical amplifier unit, (10) Minimum optical transmission level of West side optical amplifier unit, (11) West side It includes the optical reception level of the optical amplifier unit, (12) the minimum optical reception level of the West side optical amplifier unit, and (13) the maximum optical reception level of the West side optical amplifier unit. As illustrated in FIG. 10, the light level information may include not only the light level at the detection time but also the maximum value and the minimum value of the light level during the detection cycle.

  The light level information as shown in FIG. 10 is stored in the storage unit of each node every predetermined time (for example, 2 seconds), and is transmitted to other nodes by the transmission unit. By creating a history using light level information as shown in FIG. 10, failure analysis can be performed even for instantaneous light level fluctuations.

  In the above-described embodiment, the transmission unit of each node always transmits the optical level information of its own node to other nodes every predetermined time. However, the transmission unit of each node may transmit the optical level information when there is a transmission request from another node.

  More specifically, the storage unit of each node stores the optical level measured by the optical level monitor unit at predetermined time intervals, but the transmission unit does not immediately transmit the optical level information to other nodes. For example, when a code error of the optical main signal is detected at a certain node, the acquisition unit of the node requests optical level information from another node. The transmission unit of the other node that has received the request transmits the optical level information of the own node to the acquisition unit of the requested node. The history storage unit of the node in which the code error is detected stores the optical level history using the optical level information of the other node acquired in this way. By adopting such a configuration, unnecessary information is not transferred during normal operation in which no code error occurs, so that the load on the OSC line and device can be reduced.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In the above-described embodiment, the optical level information is acquired for all the nodes constituting the ring network. However, the optical level information for some selected nodes is acquired, and the history information is generated. Also good. Further, history information may be created using all of the acquired light level information, or history information may be created using a part of the light level information.

  In the above description, the ring network is described as an embodiment of the present invention. However, the present invention is not limited to the ring network, and can be applied to, for example, a mesh network.

  10 OADM device, 17, 24 control unit, 20 relay device, 30 optical transmission path, 40 storage unit, 41 acquisition unit, 42 history storage unit, 42 history storage unit, 43 transmission unit, 100 optical transmission system.

Claims (7)

An optical transmission system that transmits an optical main signal between a plurality of nodes via an optical transmission line,
Each node
An optical level monitor for measuring an optical reception level from the optical transmission line and an optical transmission level to the optical transmission line;
A storage unit for storing the light level information measured by the light level monitor every predetermined time;
An acquisition unit for acquiring light level information of another node;
A history storage unit that stores optical level information of each node as a history when a code error of the optical main signal is detected;
An optical transmission system comprising:   2. The optical transmission system according to claim 1, wherein the optical level information is communicated between the nodes using a supervisory control signal having a wavelength different from that of the optical main signal.   The optical transmission system according to claim 1, wherein each node further includes a transmission unit that transmits the optical level information of the own node stored in the storage unit to an acquisition unit of another node. Each node is connected to two adjacent nodes,
The optical transmission system according to claim 3, wherein the acquisition unit of each node transfers optical level information acquired from one adjacent node to the other adjacent node.   5. The optical transmission system according to claim 1, wherein the history storage unit stores, as a history, optical level information of each node in a predetermined period before and after detection of a code error.   6. The optical transmission system according to claim 1, wherein the optical level information includes a maximum value and a minimum value of an optical reception level and an optical transmission level at the predetermined time. The acquisition unit of each node requests optical level information from other nodes when a code error of the optical main signal is detected,
The optical transmission system according to claim 1, wherein the transmission unit of the other node that has received the request transmits the optical level information of the own node.

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