JP5606405B2 - Branch location optical fiber fault location search apparatus and search method therefor - Google Patents

Description

  The present invention is applied to an optical communication system using a branched optical line network, and estimates a failed branch line from among branched optical lines below the optical splitter of the system (hereinafter referred to as a branch line). BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a branching optical line network fault location searching apparatus and a search method thereof for searching for a fault location on a track.

  In the conventional optical communication system, many systems (hereinafter referred to as PON communication systems) using a branched optical network (PON) have been introduced in order to construct an economical optical access network. . This system uses a network in which one optical line is branched into a plurality of optical lines by an optical splitter, and a plurality of external transmission units (ONU: Optical Network Unit) are provided by one in-house transmission unit (OLT: Optical Line Terminal). ) Can be communicated with each other. For this reason, OLT equipment costs can be reduced, and at the same time, optical line equipment can also be shared by a part of the line section (line above the optical splitter), so that the cost reduction of the entire communication equipment can be realized. It has become the mainstream of access communication systems.

  On the other hand, this PON communication system requires a large operation in terms of optical line maintenance. That is, as in the case of the conventional single star network, when the optical pulse test of the optical line is performed from the inside (above the optical splitter), the test light is equally distributed to all branch lines by the optical splitter, and each branch The return light generated on the line is superimposed again by the optical splitter, and the optical pulse test device receives it. For this reason, the present situation is that a technique for individually measuring the loss distribution of the branch line has not been established.

  Therefore, when a failure is assumed in the branch line, the test cannot be performed from the inside of the station, and it is necessary to check the outdoor equipment (for example, an aerial closure) connected to the branch line on site. At the same time, there is a possibility of equipment failure under the ONU installed in the user's home. For this reason, a large amount of operation is occurring in the fault investigation of communication facilities, and there is a serious problem of invalid dispatch.

  Currently, as a provisional countermeasure for the above problem, a method using a failure monitoring technique of an OSS (Operation Support System) in the function of the PON communication system is being studied. By using this monitoring technology, it is possible to grasp the communication state of each ONU. For example, as shown in Non-Patent Document 1, control using an OAM (Operations, Administration and Maintenance) frame defined in IEEE802.3ah, which is a standard of GE-PON (Gigabit Ethernet (registered trademark)-Passive Optical Network) The function enables notification of failure occurrence between the OLT and the ONU and monitoring of the link connection status. However, with this method alone, it is difficult to specify the failure location when there is a disconnection of an optical fiber or the like in the middle of the communication path.

  In addition, paying attention to the positional information of the reflected light from the test light blocking filter with reflection function installed at the far end of each branch line and the change in peak level, the equipment failure between the communication equipment and the user equipment at the time of failure occurs. There is a method of carving. However, also in this method, it is difficult to specify the failure position when there is a disconnection of an optical fiber or the like in the communication path.

  Furthermore, as shown in Non-Patent Document 2, when an optical pulse test is performed on a branch line on the lower side of the splitter, a method of performing a test by inputting test light from the user's home side has been attempted. In this case, there is a problem from the aspect of operational efficiency that an operator has to be dispatched to the user's house.

  Currently, as shown in Patent Document 1, a failure section is a combination of monitoring signals used in in-house and off-site transmission devices and optical fiber characteristic tests (for example, OTDR (Optical Time-domain Reflectometer) and optical power). The estimation technique is being studied. However, although this technique can also specify a rough section of the failure facility, it has not yet been able to clearly specify the failure position of the branch line.

Japanese Patent Application Laid-Open No. 2010-171652 “Optical Line Fault Section Estimation System and Fault Section Estimation Device”

NTT Technical Journal September 2005 pp91-94. Y. Koshikiya, et al. IEICE TRANS. COMMUN VOL. E90-B, NO.10 October 2007 pp.2739-2802. NTT Technical Journal May 2009 issue pp40-42.

As described above, in the branching optical line network used in the conventional optical communication system, when a failure occurs in the branching line, it is difficult to determine the fault core and identify the fault location from the inside.
The present invention has been made in view of the above problems, and even when a failure occurs in a branch line of a branch optical network, a branch type that can specify the core and the fault location from the inside. An object of the present invention is to provide an optical line network fault location search apparatus and a search method therefor.

(1) A branch transmission line in which one optical line is branched into a plurality of optical lines by an optical splitter is provided with one in-house transmission device at an end different from the optical splitter of the one optical line, An optical coupler that inputs and outputs communication light and test light is used in an optical communication system using a branched optical line network in which an off-site transmission device is installed at an end different from the splitter of the branch line, and the branch line is connected to the OTDR. (Optical Time-domain Reflectometer) Any one of an optical pulse test device to be tested, a link detection device for detecting a link state of burst signal light from the plurality of external transmission devices, the optical pulse test device, and the link detection device Measuring device selection device, OTDR waveform database for storing an OTDR waveform when the branch line is newly installed, a physical core number of the branch line, and the outside A facility state database for associating the status of the MAC address feeder owned individually, while managing the equipment state database and the OTDR waveform database, and the light pulse testing apparatus and the link controller for controlling the detecting device The control device receives the burst signal light transmitted from each of the off-site transmission devices by the link detection device via the optical coupler and the measuring device selection device, and the MAC of the signal light It is determined whether or not the outside transmission apparatus is in a link state by detecting an address, and information indicating a result of determining whether or not the outside transmission apparatus is in a link state is the state of the MAC address as, corresponding in association with the core wire number stored in the facility state database, referring to the equipment status database, the branch line The information connected off-site transmission device representing whether the link state, identifies the branch line a failure occurs, the OTDR waveform measured by the light pulse testing apparatus, the OTDR waveform and the OTDR waveform deriving a differential waveform of a normal OTDR waveform stored in the database, from the derived OTDR differential waveform, the manner of specifying the fault position of the identified failure branch line.

(2) A branch transmission line in which one optical line is branched into a plurality of optical lines by an optical splitter is provided with one in-house transmission device at an end different from the optical splitter of the one optical line, Used in an optical communication system based on a branched optical line network in which an off-site transmission device is installed at an end different from the splitter of the branch line, and an optical coupler for inputting / outputting communication light and test light, and testing the branch line And the burst signal light transmitted from the plurality of external transmission devices received by the internal transmission device to detect each link state, and the MAC address of the external transmission device in the link state OTDR waveform database that stores the OTDR (Optical Time-domain Reflectometer) waveform in the normal state when the branch line is newly installed, and the physical properties of the branch line Such a facility state database for associating the status of the MAC address core number and the off-site transmission device owned individually, while managing the equipment state database and the OTDR waveform database, the house transmission and the light pulse testing apparatus A control device for controlling the monitoring device, wherein the control device receives the burst signal light transmitted from each of the outside transmission devices by the in-house transmission monitoring device via the in-house transmission device, Information indicating the result of determining whether or not the outside transmission device is in a link state by detecting the MAC address of the signal light, and determining whether or not the outside transmission device is in a link state, as the state of the MAC address, the saved equipment state database in association with the corresponding cord number, by referring to the equipment status database, those The information branch lines connected to the off-site transmission device representing whether the link state, identifies the branch line a failure occurs, and measuring the OTDR waveform by said light pulse testing apparatus, and the OTDR waveform deriving a differential waveform of a normal OTDR waveform stored in the OTDR waveform database, from said derived OTDR differential waveform, the manner of specifying the fault position of the identified failure branch line.

(3) In the configuration of (1) or (2), the OTDR waveform database stores an OTDR waveform combined with the branch line at a normal time every time the branch line is newly installed .

The branching optical line network fault location searching method according to the present invention has the following configuration.
( 4 ) A branch transmission line in which one optical line is branched into a plurality of optical lines by an optical splitter is provided with one in-house transmission device at an end different from the optical splitter of the one optical line, Used in an optical communication system with a branch optical network in which an off-site transmission device is installed at an end different from the splitter of the branch line, receives the burst signal light transmitted from each of the off-site transmission devices, It is determined whether or not the outside transmission apparatus is in a link state by detecting a MAC address individually owned by the outside transmission apparatus from the signal light, and whether or not the outside transmission apparatus is in a link state. the information indicating the determination result whether the corresponding in association with the core wire number stored in the facility state database, referring to the equipment status database, off-site transmission device link state of being connected to the branch lines The information indicating whether to identify the branch line a failure occurs, the OTDR to branch lines performed (Optical Time-domain Reflectometer) test measures the OTDR waveform, the OTDR waveform and pre OTDR A differential waveform from the normal OTDR waveform stored in the waveform database is derived, and the failure location of the identified failure-occurring branch line is identified from the derived OTDR differential waveform.

In the method of (5) (4), the pre-OTDR waveform that will be stored in the OTDR waveform database is OTDR waveform multiplexing of the branch lines in a normal every time the branch line is established manner to.

  As described above, according to the present invention, when a problem occurs in the branch optical line of the branch type optical line network, the branch optical line can estimate the core number and specify the failure position from the inside. It is possible to provide a network fault location search apparatus and a search method therefor.

The block diagram which shows the structure of the PON communication system incorporating the failure location search apparatus of the branching type | mold optical line network which concerns on the 1st Embodiment of this invention. The flowchart which shows the flow of the failure location search procedure in the structure shown in FIG. The block diagram which shows the specific example at the time of investigating the failure position of the branch line which has a loss in the structure shown in FIG. The figure which shows the contents of the MAC address in FIG. 3, and the equipment state database (in the case of an 8th core line loss increase) of a branch line. When there is no failure in the branch line at normal time, (a) shows the OTDR waveform at the time of new installation, (b) shows the OTDR waveform at the time of new installation, (c) shows at the time of new installation and after the new installation The figure which shows OTDR difference waveform of. When a loss occurs in the branch line shown in FIG. 3 at normal time, (a) is a diagram showing an OTDR waveform at the time of new installation, (b) is a diagram showing an OTDR waveform after the new installation, and (c) is at the time of new installation. The figure which shows the OTDR difference waveform after the time of new installation. The block diagram which shows the specific example at the time of searching for the failure position of the branch line which has a fracture | rupture in the structure shown in FIG. The figure which shows the content of the equipment state database (in the case of a 4th core line fracture | rupture) of the MAC address and branch line in FIG. When the branch line shown in FIG. 7 breaks in the normal state, (a) shows the OTDR waveform at the time of new installation, (b) shows the OTDR waveform after the new installation, and (c) shows the figure at the time of new installation. The figure which shows the OTDR difference waveform after the time of new installation. The block diagram which shows the structure of the PON communication system incorporating the failure location search apparatus of the branching type | mold optical line network which concerns on the 2nd Embodiment of this invention. The flowchart which shows the flow of the failure location search procedure in the structure shown in FIG.

Embodiments of the present invention will be described in detail. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment.
(First embodiment)
FIG. 1 is a block diagram showing a configuration of a PON communication system in which a branching optical line network fault location searching apparatus according to a first embodiment of the present invention is incorporated. In FIG. 1, the PON communication system is configured as follows. First, the in-house transmission apparatus 2 arranged in the in-house 1 is connected to one end of a pre-branching optical line (hereinafter referred to as a pre-branch line) 5 connected to the outside, and the other end of the pre-branch line 5 is connected to the outside. Connected to the optical splitter 6. The optical splitter 6 branches one system into a plurality of systems (eight systems here), and each branch end is connected to the outside transmission devices 81 to 88 via branch lines 71 to 78, respectively.

  Here, test light blocking filters 31 to 39 are provided in the vicinity of the connection portion of the pre-branch line 5 with the in-house transmission device 2 and in the vicinity of the connection portions of the branch light lines 71 to 78 with the outside transmission devices 81 to 88, respectively. The optical coupler 4 for connecting to the input / output port of the fault location searching device 19 is arranged on the pre-branch line 5.

  The fault location inspection device 19 is a link between the optical pulse test device (OTDR) 12 for testing the branch optical lines 71 to 78 and the burst signal light 17 transmitted from the outside transmission devices (PON-ONU) 81 to 88. Link detection device 13 for detecting the state, measuring device selection device 10 for selecting one of these devices to connect to the input / output port 9, and storing the OTDR waveform when the branch optical line is newly installed (normal) OTDR waveform database 16 to be performed, equipment state database 15 for associating physical core numbers of branch lines 71 to 78 with MAC address states of external transmission devices 81 to 88, and an optical pulse test device while managing these databases 12 and a link detection device 13 and a computer 14 for controlling the measuring device selection device 10.

  Here, a communication light blocking filter 11 for blocking the burst signal light 17 that becomes noise in the OTDR measurement by the optical pulse testing device 12 is disposed on the connection line of the optical pulse testing device 12. The link detection device 13 is specifically configured as shown in Non-Patent Document 3, detects the link state of the burst signal light 17 transmitted from the off-site transmission devices 81 to 88, and is in the link state. The MAC addresses of the external transmission devices 81 to 88 are displayed.

  The OTDR waveform database 16 stores the combined OTDR waveform at the time of new installation (normal time) even when all the branch lines 71 to 78 are not connected during operation of the PON communication system. Has been. For example, when the branch lines 71 to 74 are connected at the time of new installation, the OTDR waveform is stored in the database 16, and thereafter, when the branch optical lines 75 to 78 are added, the OTDR waveform at the time of addition is updated as the latest information. It is stored in the database 16.

The equipment state database 15 includes the core numbers of the physical branch lines 71 to 78 corresponding to the MAC addresses of the external transmission devices 81 to 88 and the presence / absence of the MAC address signal obtained by the link detection device 13, that is, the link Manages the status of whether or not
Next, with reference to FIG. 2, the operation mode of the fault location searching device 19 will be described.
FIG. 2 is a flowchart showing a flow of a fault location search procedure by the computer 14 of the fault location searching apparatus 19. First, when a failure report is received from a user due to the occurrence of a failure, the link detection device 13 is connected to the input / output port 9 by the measuring device selection device 10. As a result, the upstream burst signal light 17 transmitted from the off-site transmission devices 81 to 88 is taken into the failure investigation device 19 through the optical coupler 4 and the optical input / output port 9 and is linked to the link detection device via the measuring device selection device 10. 13 and the link state of the signal light 17 is confirmed (step S11).

  The result obtained in step S11 is stored in the equipment state database 15 in association with the branch line equipment of the PON communication system. Here, the branch line (7N core line: 7N indicates the Nth branch line in the drawings 71 to 78) for which the failure is declared by the user is the contracted core line (that is, the maintenance target under service provision) ) And the MAC address can be detected, and it is determined whether or not the off-site transmission device (8N: 8N indicates the Nth outside transmission device in the numbers 81 to 88) is in the link state ( Step S21), when it is determined that the link state is established (Yes), there is no failure in the branch line (7N core wire), and there is a high possibility that the user equipment below the off-site transmission device (8N) has a failure. (Step S22). However, the loss increases for some reason on the branch line (7N core), and a link is established in the vicinity of the minimum receiving sensitivity of the in-house transmission device 2 and the off-site transmission device (8N) for which a failure is reported by the user. Therefore, the next step S41 (OTDR test) is also executed.

  On the other hand, in step S11 to step S21, the branch line (7N core wire) for which a failure is reported by the user is a contracted core wire, but the MAC address cannot be detected and the off-site transmission device (8N) If it is not in the link state (No), it is highly likely that the branch line (No. 7N core line) has failed. Therefore, it is determined that the branch line has failed, and the branch line connected to the reporting ONU (Nth line) (Core) is identified as a failure (step S31). However, since it is assumed that the user's off-site transmission device (8N) is turned off even for the contracted core wire, an OTDR test is performed on the branch line (No. 7N core wire) ( Step S41).

  The differential waveform between the OTDR waveform obtained in step S41 and the OTDR waveform acquired when the PON communication system stored in the OTDR waveform database 16 is newly installed (normal) is analyzed (step S51). At this time, it is determined whether or not there is a change in the differential waveform of the OTDR waveform (step S61). If there is no change in the differential waveform (No), the normal state of the branch line at the time of the new installation is maintained. It is determined that the user equipment is out of order (step S62). If there is a change in the differential waveform (Yes), it indicates that an abnormality has occurred in the branch line (No. 7N core line), and “There is a line fault at the first change point (X km) of the waveform. (Step S71), thereby completing the branch line failure location.

The results of trying to estimate the core number and specifying the fault location will be described below, specifically, while following the fault location search procedure described above and causing a fault in the branch line.
FIG. 3 is a block diagram showing a specific example when the failure location of the lossy branch line is searched in the configuration shown in FIG. 0.5km (1 line: 71), 1.0km (1 line: 73), 1.3km (1 line: 74), 3.0km (2 lines: 76, 78) by the optical splitter 6 on the pre-branch line 5 having a length of 1.0km ) Of the branch line, and the communication between the one in-house transmission device 2 and the five outside transmission devices (81, 83, 84, 86, 88), The failure location of the branch line was identified. The failure branch line was the 78th core line, and a loss of about 2.5 dB was generated at a point about 1 km from the optical splitter 6. This makes the distance from the optical splitter 6 to the failure position equal to the length of the 73rd branch line and intentionally matches the terminal reflection so that the failure position cannot be easily identified. The result is shown in FIG.

  FIG. 4 shows the result of estimating the core number of the failure branch line by reflecting the link detection result in the equipment address database 15 of the MAC address and the branch line. As shown in FIG. 4, the branch line 78 is “contracted core wire”, “failure is reported”, and “no MAC address is displayed (link is not established)”. It can be determined that the sex is “present”. However, the possibility of a failure cannot be ruled out even when “the core is under contract” as in the branch line 71 but “the MAC address is not displayed (the link is not established)”. The branch line 71 is not immediately determined to be abnormal because there is a possibility that the external transmission device 81 on the user side is in the OFF state.

Here, although it deviates from the operation explanation of the fault location searching device 19 (specification of the core number and fault location of the fault branch line), an OTDR test result in the case where no abnormality occurs in the branch lines 71 to 78 is shown for comparison. .
FIG. 5A is a diagram showing an OTDR waveform at the time of establishment (normal), and FIG. 5B is a diagram showing an OTDR waveform one week later. FIG. 5C shows the result of subtracting the OTDR waveform at the time of new installation from the OTDR waveform after one week in order to see the loss change of both. As can be seen from FIG. 5C, it is understood that no change in loss is observed in the branch line below the optical splitter 6 and the normal state is maintained. Therefore, if there is no abnormality in the branch lines 71 to 78, no change in loss is recognized in the OTDR differential waveform.

  Next, FIG. 6A is a diagram showing an OTDR waveform of the branch line when newly established (normal), and FIG. 6B is about 2.5 dB near the lower side of 1 km from the optical splitter in the branch line 78. It is a figure which shows the OTDR waveform at the time of generating the loss of. FIG. 6C shows a differential waveform obtained by subtracting the OTDR waveform at the time of installation from the OTDR waveform in which the loss is generated in order to obtain the loss change of both. As can be seen from FIG. 6C, a loss change due to a decrease in the level of the backscattered light from the branch line 78 is recognized in the vicinity of about 1 km downstream from the optical splitter 6, so that it can be determined that there is a failure at this point. In addition, although this point overlaps with the terminal reflection of the branch line 71, the significance of being confirmed as a loss change is very large.

Next, a description will be given of the result of attempting to estimate the fault core number and specify the fault location with the branch line failure state broken.
FIG. 7 is a block diagram showing a specific example in the case of searching for a failure position of a branch line having a break in the configuration shown in FIG. 0.5km (1 line: 71), 1.0km (1 line: 73), 1.8km (1 line: 74), 2.0km (1 line: 76) by the optical splitter 6 on the pre-branch line 5 with a length of 1.0km, 3.0km (1 line: 78) branch lines are connected, and the center of the failure branch line is communicated with one in-house transmission device 2 and five outside transmission devices (81, 83, 84, 86, 88). Line number estimation and fault location were performed. This time, the branch line 74 was used as a failure line, and the point about 1.3 km from the optical splitter 6 was broken. The following results are shown.

  FIG. 8 shows the result of estimating the core number of the failure branch line by reflecting the link detection result in the equipment address database 15 of the MAC address and the branch line. From FIG. 8, the branch line 74 is “contracted core wire”, “failure is reported”, and “MAC address is not displayed (link is not established)”, so that the failure is possible. It can be determined that the sex is “present”. However, the possibility of a failure cannot be ruled out even when “the core is under contract” as in the branch line 71 but “the MAC address is not displayed (the link is not established)”. The branch line 71 is not immediately determined to be abnormal because there is a possibility that the external transmission device 81 on the user side is in the OFF state.

  FIG. 9A is a diagram showing an OTDR waveform of a branch line at the time of new construction (normal state). FIG. 9B is a diagram showing a failure (breaking) of the branch line 74 near the lower 1.3 km from the optical splitter. It is a figure which shows the OTDR waveform at the time. FIG. 9 (c) shows a differential waveform obtained by subtracting the OTDR waveform at the time of installation from the OTDR waveform after fracture in order to derive the loss change of both. As can be seen from FIG. 9 (c), a loss change that is considered to be reflected from the break point is recognized about 1.3 km downstream from the optical splitter 6, so that it is understood that there is a branch line failure at this point.

(Second Embodiment)
FIG. 10 is a block diagram showing a configuration of a PON communication system in which a branching optical line network fault location searching apparatus according to the second embodiment of the present invention is incorporated. 10, parts that are the same as those in FIG. 1 are given the same reference numerals, and different parts will be described here.

  10, the basic configuration of the PON communication system is the same as the configuration shown in FIG. On the other hand, the fault location searching device 19 does not employ the measuring device selection device 10, and instead, burst signal light transmitted from a plurality of external transmission devices (PON-ONU) 81 to 88 received by the internal transmission device 2. 17 is provided so that each link state is detected, and a local transmission monitoring device (PON-OLT-OSS) 20 that displays the MAC addresses of the external transmission devices (PON-ONU) 81 to 88 in the link state is provided. This is different from the configuration shown in FIG.

  The optical pulse test apparatus (OTDR) 12, the equipment state database 15, and the OTDR waveform database 16 are the same as those in FIG. 1, and the computer 14 controls the optical pulse test apparatus 12 while managing the databases 15 and 16. This is the same as the case of 1. The communication light blocking filter 11 blocks the burst signal light 17 that becomes noise during the OTDR measurement by the optical pulse test device (OTDR) 12.

  Even when not all of the branch lines 71 to 78 are connected to the OTDR waveform database 16 during the operation of the PON communication system, the branch lines 71 to 78 are combined at the time of new installation (normal time). The obtained OTDR waveform is stored. For example, when the branch lines 71 to 74 are connected at the time of new installation, the OTDR waveform is recorded in the database 16, and thereafter, when the branch lines 75 to 78 are added, the OTDR waveform at the time of addition is the latest information. It is stored in the database 16.

The equipment state database 15 includes the core numbers of the physical branch lines 71 to 78 corresponding to the MAC addresses of the external transmission devices 81 to 88 and the presence / absence of the MAC address signal obtained by the link detection device 13, that is, the link To manage whether or not is established.
Next, with reference to FIG. 11, an operation mode of the fault location searching device 19 will be described.
FIG. 11 is a flowchart showing the flow of the fault location searching procedure by the computer 14 of the fault location searching apparatus 19. The MAC address information (link establishment information) included in the upstream burst signal light 17 is executed by the link detection device 13 in the first embodiment, whereas in the present embodiment, the local transmission monitoring device (PON-OLT-) is used. Except that the OSS) 20 fulfills its function, the core number of the fault branch line is estimated and the fault location is determined in substantially the same flow.

  First, when a failure report is received from the user, the link state of the upstream burst signal light 17 obtained by the in-house transmission monitoring device 20 is confirmed by the computer 14, and the failure branch line is specified (step S12). The result obtained in step S12 is added to the facility information of the PON communication system and stored in the facility state database 15. Here, the branch line (No. 7N core line) for which a failure is reported by the user is a contracted core line (under service provision), and the MAC address can be detected. It is determined whether or not the link state is established (step S22). If the link state is established (Yes), there is no failure in the branch line, and there is a high possibility that there is a failure in the user equipment except the off-site transmission devices 81 to 88. Judgment is made (step S23). However, the loss increases for some reason on the branch line, and the link may or may not be established in the vicinity of the minimum receiving sensitivity of the in-house transmission device 2 or the off-site transmission device (8N) for which a failure is reported by the user. Since there is a possibility, the next step S42 (OTDR test) is also executed.

  On the other hand, in step S12 to step S22, the branch line (7N core wire) for which the failure has been reported by the user is the contracted core wire, but the MAC address cannot be detected and the off-site transmission device (8N) If it is not in the link state (No), it is highly possible that the branch line (7N) has failed. Therefore, it is determined that the branch line has failed, and the branch line (Nth core) connected to the reporting ONU Is identified as a failure (step S32). However, since it is assumed that the power of the user's off-site transmission device (8N) is in an OFF state even for the contracted core wire, the user equipment immediately after the off-site transmission device (8N) is immediately out of order. Without determination, an OTDR test is performed on the branch line (7N) (step S42).

  The difference between the OTDR waveform obtained in step S42 and the OTDR waveform acquired when the PON communication system is newly installed (normal) recorded in the OTDR waveform database 16 is analyzed (step S52). At this time, if there is no change in the differential waveform (No), no change in loss is recognized in the branch line (7N), so it is determined that the user equipment is out of order (step S63). Here, it is determined whether or not there is a difference in the OTDR waveform due to a change in the difference waveform (step S62). If there is a difference (Yes), it indicates that an abnormality has occurred in the branch line (7N). In step S72, the first change point (X km) of the waveform is identified as “there is a line failure”. If it is determined in step S62 that there is no difference, it is processed as a failure of user equipment (step S63). This completes the identification of the branch line failure location.

  As described above, in the conventional PON communication system, in the optical line maintenance, when the optical pulse test of the optical line is performed from the inside (above the optical splitter), the test light is equally distributed to the branch line by the optical splitter, and each branch is performed. Since the return light generated on the line is superimposed again by the optical splitter and received by the optical pulse test device, the branch line cannot be individually tested. As a result, since it is not possible to test from the site for a failure that may cause a failure of the branch line, it is forced to rush to the outdoor facility with the branch line, and at the same time, the facility failure after the user-side ONU Because there is a possibility, a large operation has occurred in the failure investigation of communication equipment, and there was a serious problem of invalid dispatch.

This time, by using the fault location searching device according to the configuration of the first embodiment or the second embodiment, it becomes possible to specify the fault location of the branch line of the PON communication system, and speeds up fault repair and drastically Reduction of maintenance operation is expected.
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some configurations may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different example embodiments may be combined as appropriate.

  DESCRIPTION OF SYMBOLS 1 ... In-house, 2 ... In-house transmission apparatus (PON-OLT), 31-39 ... Test light cutoff filter, 4 ... Optical coupler, 5 ... Pre-branch line, 6 ... Optical splitter, 71-78 ... Branch line, 81-88 ... External transmission device (PON-ONU), 9 ... Optical input / output port, 10 ... Measurement device selection device, 11 ... Communication light blocking filter, 12 ... Optical pulse test device (OTDR), 13 ... Link detection device, 14 ... Computer, 15 ... Equipment status database, 16 ... OTDR waveform database, 17 ... Upstream burst signal light, 18 ... OTDR test light, 19 ... Fault location search device, 20 ... In-house transmission monitoring device (PON-OLT-OSS), 21 ... Loss increasing failure, 22 ... Breaking failure.

Claims (5)

A branch transmission line in which one optical line is branched into a plurality of optical lines by an optical splitter is provided with one in-house transmission device at an end different from the optical splitter of the one optical line. Used in an optical communication system with a branch optical network in which an off-site transmission device is installed at an end different from the splitter,
An optical coupler for inputting and outputting communication light and test light;
An optical pulse test device for testing the branch line with an OTDR (Optical Time-domain Reflectometer);
A link detection device for detecting a link state of burst signal light from the plurality of external transmission devices;
A measuring device selection device for selecting one of the optical pulse test device and the link detection device;
An OTDR waveform database for storing an OTDR waveform in a normal state when the branch line is newly installed;
A facility state database for associating the status of the MAC addresses physical core number and the off-site transmission device of the branched lines is individually owned,
A control device for controlling the optical pulse test device and the link detection device while managing the OTDR waveform database and the equipment state database;
Comprising
The controller is
The link signal light transmitted from each of the external transmission devices is received by the link detection device via the optical coupler and the measuring device selection device, and the external address is detected by detecting the MAC address of the signal light. Determine whether the transmission device is in a link state,
Information indicating the result of determining whether or not the off-site transmission device is in a link state, as the state of the MAC address, stored in the facility state database in association with the corresponding core number ,
With reference to the equipment state database, the information indicating whether or not the external transmission device connected to the branch line is in a link state, identifies the branch line where the failure has occurred,
Said OTDR waveform measured to derive a difference waveform between the normal OTDR waveform stored with the OTDR waveform to the OTDR waveform database by pre Symbol light pulse testing apparatus,
A fault location searching device for a branching optical line network , wherein a fault location of the specified fault occurrence branch line is specified from the derived OTDR differential waveform. A branch transmission line in which one optical line is branched into a plurality of optical lines by an optical splitter is provided with one in-house transmission device at an end different from the optical splitter of the one optical line. Used in an optical communication system with a branch optical network in which an off-site transmission device is installed at an end different from the splitter,
An optical coupler for inputting and outputting communication light and test light;
An optical pulse testing device for testing the branch line;
An in-house transmission monitoring device that receives burst signal light transmitted from a plurality of outside transmission devices received by the in-house transmission device, detects each link state, and displays the MAC address of the outside transmission device in the link state When,
An OTDR waveform database for storing an OTDR (Optical Time-domain Reflectometer) waveform in a normal state when the branch line is newly installed;
A facility state database for associating the status of the MAC addresses physical core number and the off-site transmission device of the branched lines is individually owned,
A control device for controlling the optical pulse test device and the in-house transmission monitoring device while managing the OTDR waveform database and the equipment state database;
Comprising
The controller is
The burst signal light transmitted from each of the external transmission devices is received by the local transmission monitoring device via the local transmission device, and the external transmission device is linked by detecting the MAC address of the signal light. Determine whether it is in a state,
Information indicating the result of determining whether or not the off-site transmission device is in a link state, as the state of the MAC address, stored in the facility state database in association with the corresponding core number ,
With reference to the equipment state database, the information indicating whether or not the external transmission device connected to the branch line is in a link state, identifies the branch line where the failure has occurred,
Said OTDR waveform measured to derive a difference waveform between the normal OTDR waveform stored with the OTDR waveform to the OTDR waveform database by pre Symbol light pulse testing apparatus,
A fault location searching device for a branching optical line network , wherein a fault location of the specified fault occurrence branch line is specified from the derived OTDR differential waveform.   3. The branching optical network according to claim 1, wherein the OTDR waveform database stores an OTDR waveform combined with the branch line in a normal state every time the branch line is newly installed. 4. Fault location device. A branch transmission line in which one optical line is branched into a plurality of optical lines by an optical splitter is provided with one in-house transmission device at an end different from the optical splitter of the one optical line. Used in an optical communication system with a branch optical network in which an off-site transmission device is installed at an end different from the splitter,
The external transmission device is in a link state by receiving the burst signal light transmitted from each of the external transmission devices and detecting a MAC address individually owned by the external transmission device from the signal light. Whether or not
Information indicating the result of determining whether or not the off-site transmission device is in a link state is stored in the equipment state database in association with the corresponding core number ,
With reference to the equipment state database, the information indicating whether or not the external transmission device connected to the branch line is in a link state, identifies the branch line where the failure has occurred,
Deriving the OTDR to branch lines performed (Optical Time-domain Reflectometer) test measures the OTDR waveform, differential waveform of the the OTDR waveform, the OTDR waveform during normal stored in OTDR waveform database before things And
A failure location search method for a branching optical line network, wherein a failure location of the identified failure occurrence branch line is identified from the derived OTDR differential waveform. The pre OTDR waveform that will be stored in the OTDR waveform database, branch of claim 4, wherein the branch lines are OTDR waveform multiplexing of the branch lines in a normal every time it is established Fault location search method for shaped optical line network.

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