WO2009094952A1

WO2009094952A1 - Method, optical network and network equipment for locating branch fiber event point

Info

Publication number: WO2009094952A1
Application number: PCT/CN2009/070310
Authority: WO
Inventors: Sulin Yang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2008-01-28
Filing date: 2009-01-23
Publication date: 2009-08-06

Abstract

A method for locating fiber event point includes determining the distance between the event point and an optical line termination (OLT). The optical line termination (OLT) measures the power of the uplink testing signal sent by the optical network unit (ONU) or optical network termination (ONT) at the opposite terminal of the measured fiber link. The measured power of the uplink testing signal is compared with a pre-saved normal power of the uplink testing signal to determine whether the event point is on the measured fiber link, and if so, the location of the event point on the measured fiber link is determined according to the distance between the event point and the OLT. An optical network and a network equipment are disclosed.

Description

Method, optical network and network device for locating event points of branch fiber

The present application claims priority to Chinese Patent Application No. 200810006992.3, entitled "A Method for Locating Branch Points of Optical Fibers, Optical Network and Network Equipment", filed on January 28, 2008, The entire contents are incorporated herein by reference. Technical field

The present invention relates to the field of communications, and in particular, to a method, an optical network, and a network device for locating event points of a branch fiber.

Background technique

At present, in the field of access networks, digital subscriber line (DSL) is fully developed, and optical access is booming, especially for point-to-multipoint optical access technology—passive optical network (Passive Optical Network). , referred to as PON), once again received attention. Compared with point-to-point access, the PON office can be divided into dozens or more optical fibers to connect users with one fiber, which can greatly reduce the cost of network construction. At present, representative PON technologies are Gigabit Passive Optical Network (GPON), and Ethernet Passive Optical Network (EPON), where GPON technology has a high line rate. The maintenance function is relatively complete, so it is widely used.

FIG. 1 is a schematic structural diagram of a PON system. As shown in the figure, the system includes the following three parts: an optical distribution network (ODN) 12 and other networks (eg, PSTN 14, Internet 15, and cable television network 16). Optical Line Termination (OLT) 11, optical distribution network 12, and Optical Network Unit (ONU) / Optical Network Termination (referred to as ΟΝΤ) 13 . In the PON system, the transmission from the OLT11 to the ONU/ONT13 direction is called downlink, and vice versa. The downlink data is broadcasted by the OLT11 to each ONU/ONT13 because of the characteristics of the optical. The downlink time division multiplexing mode, each ONU/ONT13 The uplink data transmission is allocated by the OLT 11 to the transmission space, and the uplink time division multiplexing multiple access.

The network side interface of the OLT 11 is a service node interface (SNI), and the user interface of the ONT is a user network interface (UNI, User Network Interface), and the optical interface of the OLT 11 and the ODN 12 is called For the PON interface, the ITU-T G.984 series of standards is named after the S/R reference point, and S/R is the downlink Send/upstream Receive. PON interface S/R connection one or more ODN12 function; ODN12 is a passive optical splitting device, which transmits downlink data of OLT11 to each ONU/ONT13, and simultaneously transmits uplink data of multiple ONU/ONT13 to OLT11; ONU provides user-side interface, ONU and ODN for PON system The 12-connected PON optical interface is called the R/S interface, and the R/S is the downlink Receive/uplink. That is, the PON interface R/S is connected to the ODN. If the ONU directly provides the user port function, such as the Ethernet user for the PC Internet access. The port is called ONT. ODN 12 is generally divided into three parts: a passive optical splitter (Splitter) 121, a trunk optical fiber 122, and a branch fiber 123.

During the operation of the PON system, the measurement of the optical fiber transmission characteristics is an important part of the maintenance of the PON system. The optical fiber line monitoring can automatically and continuously perform online remote monitoring of the optical fiber line, regularly maintain the optical fiber line of the PON system, and remotely identify the fault. A quick response to failures can be achieved to enable the underlying fast protection switching before the high-level network is affected.

Optical Time Domain Reflectometer (OTDR), related optical time domain reflectometer (C-OTDR, correlative calculation of excitation signal and reflected signal to obtain line characteristics), optical frequency domain reflectometer (OFDR, Optical Frequency-Domain Reflectometry, which transmits a specific frequency signal and detects the line characteristics at the corresponding frequency, is a measuring device that measures the transmission characteristics of the optical fiber. Taking an OTDR as an example, the OTDR provides attenuation details along the length of the fiber, including detecting, locating, and measuring events anywhere on the fiber optic cable link. An event is a defect in a fiber optic link that is caused by a splice, connector, adapter, jumper, bend, or break. The change in optical transmission characteristics caused by the defect can be measured by the OTDR, and the OTDR can locate the event based on the measured change in optical transmission characteristics. The OTDR works like a radar scan. The OTDR sends a test signal to monitor the strength and delay of the signal reflected back from the event point after the test signal reaches the event point, and determines the type of event and the location of the event point. The difference between OFDR and OTDR is that instead of using the time parameter as the OTDR to measure, the frequency is used.

However, in the point-to-multipoint network topology of the PON, the signal from the optical fiber detecting device such as the OTDR or the OFDR on the OLT side is reflected by the branches, and the optical fiber detecting equipment such as the OTDR or the OFDR is superimposed. It is not possible to distinguish the branch fiber where the event point is located. In view of this, there are two main solutions for optical fiber line monitoring in the prior art:

The first monitoring method is specifically to add a mirror at the end of each branch fiber to reflect the test signal, so that the waveform of the reflected light at the end of each branch fiber does not overlap, and the PON network needs to be overlapped. To make the length of each branch fiber different, the branch fiber can be monitored by monitoring the waveform of each branch fiber during the test. However, the precondition of the monitoring technology is to ensure that the length of each fiber in the PON system is different, which increases the difficulty of the actual networking wiring, and the practical applicability is poor.

The second example is shown in Figure 2. The PON network fiber is monitored from the ONU/ONT201 side, and a fiber detection device 220 (OTDR or OFDR, etc.), each fiber and trunk fiber, test data or result is integrated on each ONU/ONT201. Uploaded to the OLT 210 through the uplink channel. However, such a solution can cause high network monitoring costs.

Summary of the invention

The embodiments of the present invention provide a method for locating an event point of an optical fiber, an optical network, and a network device, so that the event can be located on the OLT side even if the event point occurs on the branch fiber.

The embodiment of the invention discloses a method for locating an event point of an optical fiber, comprising: determining a distance of an event point from an optical line terminal OLT; and determining, by the optical line terminal OLT, the received optical network link opposite optical network unit ONU or optical network The energy of the uplink test signal sent by the terminal ONT; comparing the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal, determining whether the event point is on the tested fiber link, if If yes, determine the location of the event point on the tested fiber link according to the distance of the event point from the OLT.

The embodiment of the present invention further discloses a network device, where the network device is an optical line terminal OLT, and includes: an energy measurement unit, configured to measure an uplink of an optical network unit ONU or an optical network terminal ONT sent by the opposite end of the tested optical fiber link. The energy of the test signal is used to compare the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal, and determine whether the event point is on the fiber link under test; a determining unit, configured to determine a distance between the event point and the OLT, and when the determining unit determines that the event point is on the tested fiber link, according to a distance of the event point from the OLT The location of the event point on the fiber link under test is determined.

The embodiment of the invention further discloses an optical network, comprising: an optical line terminal OLT, an optical network unit ONU/optical network terminal ONT, and an optical distribution network ODN connecting the OLT and the ONU/ONT; the OLT is the optical line terminal.

The technical solution of the embodiment of the present invention can be seen by measuring the fiber under test. The optical loss of the optical path between the OLT and the ONU/ONT on the link, and determining whether the event point is on the fiber link under test according to the measured optical loss of the optical path, if it is determined that the event point is The measured fiber link determines the specific location of the event point on the tested fiber link based on the distance of the event point from the OLT. Therefore, it is only necessary to use the fiber detecting device on the OLT side to determine the distance of the event point from the optical line terminal OLT, and then use the optical path loss measurement data to locate the event point on the tested fiber link on the OLT side even if the event point is The above method can also be employed on the branch fiber. The problem of high monitoring cost on the ONU/ONT side is avoided, and the second technical solution of the prior art greatly reduces the cost. In addition, the technical solution of the embodiment of the present invention does not require the wiring of the length of each branch fiber of the PON network, and is more applicable to the first technical solution of the prior art.

DRAWINGS

The drawings described herein are provided to provide a further understanding of the invention, and are not intended to limit the invention. In the drawing:

1 is a schematic structural diagram of an existing PON system;

2 is a schematic structural diagram of a system for monitoring a fiber detecting device on each ONU/UNT side in a second scheme of the prior art;

3 is a schematic flow chart of a method for locating event points of a branch fiber according to Embodiment 1 of the present invention;

4 is a schematic diagram of a method for positioning a branch fiber event point by using an OLT-side fiber detecting device, an OLT, and an energy measuring unit on an ONU/ONT side according to Embodiment 1 of the present invention;

FIG. 5 is a schematic diagram of a method for realizing a branch fiber incident point by using an OLT side optical fiber detecting device, an energy measuring unit, and an ONU/ONT side reflecting device according to Embodiment 1 of the present invention; FIG. 2 is a schematic diagram of an OLT structure provided in 2;

7 is a schematic structural diagram of another OLT provided in Embodiment 2 of the present invention;

FIG. 8 is a schematic structural diagram of a first optical network according to Embodiment 3 of the present invention; FIG.

9 is a schematic structural diagram of a second optical network provided in Embodiment 3 of the present invention;

FIG. 10 is a schematic structural diagram of a third optical network according to Embodiment 3 of the present invention; FIG.

11 is a schematic structural diagram of an ONU/ONT provided in Embodiment 4 of the present invention;

12A is a schematic flowchart of a method for locating event points of a branch fiber according to Embodiment 7 of the present invention; 12-B is a determination of whether an event point is determined on the fiber link under test according to Embodiment 7 of the present invention, and the flow test is performed.

13 is a schematic structural diagram of an OLT based on Embodiments 6 and 7;

Figure 14 is a schematic diagram showing the structure of an optical network based on Embodiments 6 and 7. detailed description

The invention will be described in detail below with reference to the drawings in conjunction with the embodiments. The illustrative embodiments of the present invention and the description thereof are intended to be illustrative of the present invention, but are not intended to limit the invention.

Example 1

FIG. 3 is a schematic flowchart of a method for locating event points of a branch fiber according to the embodiment. As shown in FIG. 3, the method in this embodiment includes the following steps:

Step 301: Determine the type of the event point and determine the distance of the event point from the OLT.

An OTDR, OFDR, or other fiber-detecting device or function can be set up on the OLT side of the PON to determine the event point through the OTDR, OFDR, or other fiber-detecting device, and the distance of the event point from the OLT where the OTDR is located. The function of determining the distance of the event point from the OLT can be completed by using an independent device such as an OTDR, OFDR, or other fiber detecting device, or a module having a function of determining the distance of the event point from the OLT through integration inside the OLT ( Such as OTDR,

OFDR or other fiber detection function is completed.

Take the OTDR as an example: As shown in Figure 4, an OTDR4011 is set on the OLT401 side. After the test signal 402 sent by the OTDR4011 reaches the event point 403, it is reflected back to the OTDR4011.

The OTDR4011 determines the type and location of the event point according to the characteristics and delay of the reflected test signal. The position can be determined according to the transmission speed and delay of the test signal.

The distance of the OLT. If the fiber-detecting device is an OFDR or other fiber-detecting device, it can be measured by referring to the measurement method of the prior art, and details are not described herein.

Step 302: Determine whether the event point is on the trunk fiber. If yes, go to step 303; otherwise, go to step 304.

If the distance of the event point from the OLT does not exceed the distance of the backbone fiber, it can be determined that the event point exists on the trunk fiber. Since there is only one backbone fiber, step 303 is performed, and the event point can be determined in the trunk by referring to the prior art. The specific location on the fiber. If the distance of the event point from the OLT exceeds the distance of the backbone fiber, it can be determined that the event point exists on the branch fiber of the OLT to the ONU/ONT, and step 304 is performed to locate the branch fiber where the event point is located.

Step 303: Determine the specific location of the event point on the backbone fiber.

It should be noted that, because the purpose of the embodiment of the present invention is to determine an event point on the branch fiber, if it is not necessary to determine whether the event point is on the trunk fiber and its specific location on the trunk fiber, step 302 may be omitted. The process of 303.

Step 304: Test the optical loss of the optical path between the OLT and the ONU/ONT.

For the implementation of this step, as shown in FIG. 4, a test device or function for testing signal energy (which can be represented by power) is respectively set on the OLT and each ONU/ONT, and the device or function is referred to as an energy measurement unit. As shown, the energy measuring unit 404 on the OLT 401 side measures the test signal sent by the OLT to the branch fiber of the ONU/ONT 405. The test signal may be: the currently transmitted data signal, or may be separately transmitted for the test. The power or energy of a particular test signal). After the ONU/ONT405 side receives the downlink test signal sent by the OLT (the downlink test signal may be a downlink data signal or other signal different from the downlink data signal), the received energy is measured by the energy measuring unit 406 disposed on the ONU/ONT 405 side. The energy of the signal (corresponding to the power can also be expressed), and the energy test result is uploaded back to the OLT 401 through the uplink channel; the OLT 401 is uploaded by the energy measurement unit 404 of the present side, and the received signal is uploaded by the ONU/ONT 405. The energy test results calculate the optical loss of the optical path between the OLT 401 and the ONU/ONT 405, which may be referred to as the optical loss in the downstream direction. The energy test result described above may be a single optical signal energy measurement result, or may be a result of data processing (such as average calculation, etc.) of multiple optical signal energy measurement results.

Determining the optical loss of the optical path between the ONU and the ONT 405 can also be obtained by calculating the optical loss of the optical path between the ONU/ONT 405 and the OLT 401. The optical loss can be referred to as the optical loss in the uplink direction. The specific test and calculation method can be referred to. The measurement method of the optical loss in the downlink direction is different. At this time, the energy of the test signal transmitted from the ONU/ONT 405 to the OLT 401 through the uplink channel is measured by the energy measuring unit 406 disposed on the ONU/ONT 405 side, and the energy test result is passed. The uplink channel is uploaded to the OLT 401. After receiving the test signal sent by the ONU/ONT 405 on the OLT 401 side, the energy measurement unit 404 measures the energy of the uplink test signal received on the OLT 401 side, and then according to the energy. The test result of the measuring unit 404, and the received energy measurement result of the test signal measured by the ONU/ONT 405 at the transmitting end, calculate the optical loss of the optical path between the ONU/ONT 405 and the OLT 401, and the optical loss can be referred to as the optical loss in the uplink direction. . The uplink test signal may be an uplink data signal or other signal than the uplink data signal. Here, the optical loss of the optical path can be calculated either on the OLT 401 side or on the ONU/ONT 405 side, and the calculation result can be uploaded back to the OLT 401. The calculation of the optical path loss by the ONU/ONT 405 is similar to the calculation of the optical path loss by the OLT 401. Only the energy of the test signal measured by the OLT side needs to be transmitted to the ONU/ONT 405 through the downstream channel, and the optical path loss is calculated by the ONU/ONT 405.

Generally, since the optical power transmitted by the laser does not change significantly within a certain period of time, the loss of the line can also be judged by measuring only the received optical power. For example, the received optical power of the uplink test signal can be measured only by the OLT side, and the received optical power of the measured uplink signal is compared with the received optical power of the uplink test signal stored in advance on the OLT side. To determine the optical loss in the uplink direction. Similarly, the ONT side can measure the received optical power in the downlink direction. By comparing: the measured received optical power of the downlink test signal and the downlink test signal stored in advance on the ONT side. The received optical power is normal to determine the optical loss in the downstream direction.

In general, when determining the optical loss of the optical path between the OLT and the ONU/ONT, it is only necessary to test the optical path.

On the optical path between ONU/ONT, the optical loss of the optical path in the two directions will be slightly different. If the test accuracy is high, the optical loss in both directions of the optical path can be tested separately and processed by the corresponding algorithm (such as weighted average algorithm). To remove the one-way imbalance, the optical path measurement results of the optical path are more accurate.

For the specific implementation of this step, as shown in FIG. 5, a test energy measurement unit 502 is disposed on the OLT 501 side, and a reflection unit 504 is respectively disposed at the front end of each ONU/ONT 503 side transceiver unit 506. When each reflection unit 504 is turned on, The signal arriving at the node will be reflected back to the signal transmitting end against the signal transmitting direction, and will not have any reflection function when turned off. Since the return loss of the signal to the connector and the splice point of the normal operation can be as high as 40 dB or more, the reflection unit 504 is not omitted.

As shown in FIG. 5, the OLT 501 sends control information to each ONU/ONT 503 to open the current test. The branch unit 504 on the ONU/ONT 503 side where the branch fiber is located is closed, and the reflection unit 504 on the other ONU/ONT 503 side is turned off. In addition, the test signal 505 is transmitted from the OLT 501 to the tested branch fiber, and the energy measuring unit 502 on the OLT 501 side measures the energy of the test signal transmitted by the OLT to the branch fiber, and the value is set to Ps. After the test signal 505 reaches each ONU/ONT 503, since only the reflection unit 504 of the branch fiber to be tested is turned on, only the ONU/ONT 503 side reflection unit 504 on the branch fiber to be tested reverses the test signal 505 against the original transmission direction of the test signal. , reflected back to the transmitting end OLT501. The other ONU/ONT 503 side reflection unit 504 does not reflect the test signal. After receiving the reflected test signal 505, the OLT 501 side measures the energy of the reflected test signal 505 and sets the value to Pr. The OLT 501 can refer to the calculation method in the prior art, and calculate the energy Ps of the transmitted test signal 505 and the energy Pr of the test signal 505 reflected back to calculate the OLT 501 and the ONU/ONT 503 on the test branch fiber. Optical path loss, including two-way optical loss and single-pass optical loss, where the single-pass optical loss is one-half of the two-way optical loss. By measuring the optical loss by measuring the two-way optical loss, it can eliminate the one-way measurement. The balance makes the optical loss measurement result of the optical path more accurate.

It should be noted that, by extension of the optical loss measuring method shown in FIG. 5, the energy measuring unit 502 can also be disposed on the ONU/UNT side of the PON terminal, and the reflecting unit 504 can be disposed on the OLT side, by being in the ONU/ The optical loss measured on the UNT side can be returned to the OLT side, but such a measurement method generally requires a relatively high cost with respect to the above-described measurement method. Step 305: Determine whether the event point is on the current branch fiber. If yes, go to step 306; otherwise, go to step 307.

As shown in FIG. 4, the relationship between the optical path between the OLT 401 and an ONU/ONT 405 (corresponding to the normal loss of one-way or two-way when a branch optical barrier is obtained) is determined whether the event point is on the current branch fiber: if the optical loss is greater than the normal loss Then, if the event point is determined to be on the current branch fiber, step 306 is further performed; if the optical loss is equal to the normal loss, it is determined that the event point is not on the current branch fiber, and step 307 is performed.

Step 306: Determine the location of the event point on the optical fiber according to the distance of the event point from the OLT. Obviously, after determining which branch fiber exists in the event point, according to the distance of the event point determined from step 301 from the OLT, the position of the event point on the branch fiber can be determined.

Step 307: Continue to monitor and determine if there are other branch fibers on the event point and the specific locations on the branch fiber.

The specific implementation of this step can be performed by referring to the process of step 304 to step 306, and details are not described herein. It should be noted that, according to the principle of the embodiment, when determining the position of the event point on the branch fiber, the optical loss of the optical path may also be determined first, and whether there is an event point on the optical path according to the optical loss of the optical path, if present, Then, determine the distance of the event point from the OLT, and determine the specific location of the event point on the branch fiber in this way.

It is worth noting that even if a fiber is too worn or broken, it will cause on the branch fiber.

The data of the ONU/ONT side cannot be uploaded, and the method of the embodiment of the present invention is applied, and the event point of the branch fiber can also be located by means of exclusion.

The following example shows how to combine the loss measurement and event point measurement to determine the branch where the event point is located.

On point-to-multipoint optical networks, when fiber optic detection equipment such as OTDRs or functions are used to measure optical fibers on the OLT side, the reflections of all branch fibers are superimposed. When the splitting ratio of the splitter is good, the relationship between the actual loss of the branch fiber and the attenuation measured by the OTDR is:

Where Lr is the actual loss on the branch, La is the loss detected by the fiber detection device or function such as OTDR, and N is the split ratio of the splitter.

If the loss measurement is performed first, it is found that the loss of the branch on the ONU is changed, the amount of change Lr is calculated, and La is calculated according to the above formula. When an optical test device or function such as an OTDR is used to actually test the line, it is found that there is an event point where the loss is La on the branch fiber, and it can be determined that the event point is on the branch fiber where the ONU is located, and the event can be determined. The type of point. If a fiber-optic detection device such as an OTDR or a function detects that there is an event point on the branch fiber, and the loss is La, the actual loss Lr on the branch fiber can be calculated according to the above formula, by passing between the OLT and each ONU. The link loss is measured. If the loss change on the link where an ONU is located is Lr, it can be determined that the event point is on the branch fiber where the ONU is located.

It can be seen from the above that, by using the method of this embodiment, only the OLT side located at the optical network office end needs to be set. An OTDR, OFDR or other fiber-detecting device or function, and a reflection device on the ONU/ONT side of the optical network terminal to reflect the measurement signal back to the OLT side of the central office, or an energy measurement unit on the ONU/ONT side. The end measures the energy of the test signal to position the event point on the branch fiber. There is no need to set expensive OTDR, OFDR or other fiber detecting devices or functions on the ONU/ONT side, so the method of the present embodiment greatly reduces the network monitoring cost compared to the second method of the prior art. In the meantime, the method of the embodiment does not need to impose any limitation on the optical fiber in the network, and the practical application feasibility of the solution is greatly improved compared with the first solution of the prior art.

Example 2:

FIG. 6 is a schematic structural diagram of an OLT according to the embodiment (corresponding to the method shown in FIG. 5). As shown, the OLT includes:

The optical loss measuring unit 602 is configured to measure optical loss of the optical path between the OLT and the ONU/ONT of the opposite end of the tested branch fiber. The optical loss determining unit 602 may include:

The energy measuring unit 6021 is configured to measure energy of the test signal, where the energy of the test signal comprises: energy of a test signal sent by the OLT side to the ONU/ONT side, reflected by the ONU/ONT side The energy of the test signal.

The calculating unit 6022 is configured to determine the optical loss of the optical path between the OLT and the ONU/ONT according to the energy of the transmitted test signal measured by the energy measuring unit 6021 and the energy of the reflected test signal.

The OLT also includes:

The determining unit 603 is configured to determine, according to the relationship between the optical loss of the optical path determined by the optical loss measuring unit 602 and the normal loss of the optical path, whether the event point is on the branch fiber. If the optical loss is greater than the normal loss, then the event point is determined to be on the current branch fiber, and if the optical loss is equal to the normal loss, then the event point is determined not to be on the current branch fiber.

Alternatively, when the optical path optical loss measured by the optical loss measuring unit 602 includes the optical loss of the upstream optical path and the optical loss of the downstream optical path, the determining unit 603 may be specifically configured to measure the optical loss variation of the single channel according to the optical loss. And a downstream optical path for measuring according to the optical loss measuring unit And determining whether an event point is on the fiber link under test according to a relationship between an amount of change in optical loss of the upstream optical path and an amount of change in optical loss of the downstream optical path.

Another possibility is that the optical path optical loss measured by the optical loss measuring unit 602 includes the optical loss of the upstream optical path or the optical loss of the downstream optical path. In this case, the determining unit 603 may also be specifically configured to measure according to the optical loss measuring unit. Obtaining an optical loss of the uplink optical path and a normal loss of the uplink optical path, determining an optical loss variation amount of the uplink optical path, and determining, according to the optical loss variation amount of the uplink optical path, whether an event point is on the optical fiber link under test. Or the determining unit 603 is further configured to determine, according to the optical loss of the downlink optical path measured by the optical loss measuring unit and the normal loss of the downlink optical path, the amount of change in optical loss of the downlink optical path, and further according to the The amount of change in optical loss of the downstream optical path determines whether the event point is on the fiber link under test.

The event point location determining unit 601 is configured to determine a distance between the event point and the OLT, and when the determining unit determines that the event point is on the branch fiber, according to the event point, the OLT is away from the OLT. Distance determines the location of the event point on the fiber.

The event point location determining unit 601 can be implemented by using an OTDR, OFDR or other fiber detecting device, or can be implemented by integrating a module implementing the same function of the OTDR inside the OLT, first determining the type of the event point and the distance of the event point from the OLT. If the event point location determining unit 601 determines that the distance of the event point from the OLT is less than or equal to the length of the backbone fiber, the event point is on the backbone fiber; otherwise, the event point is on the branch fiber connected to the backbone fiber.

For the case where the event point is on the branch fiber connected to the trunk fiber, when the determining unit 603 determines that the event point is on the current branch fiber, the distance of the event point from the OLT determined according to the event point location determining unit 601 is determined. , determining the location of the event point on the fiber.

Another possible case is: the fiber link to be tested includes the branch fiber in the fiber link under test; at this time, the determining unit 603 may be specifically configured to use the measured OLT and the tested fiber link to the opposite ONU or The optical loss of the optical path between the ONTs determines whether the event point is on the branch fiber in the fiber link under test; the event point location determining unit 601 is specifically configured to determine a distance between the event point and the OLT, And when the determining unit determines that the event point is on the branch fiber in the tested fiber link, determining, according to the distance of the event point from the OLT, that the event point is on the tested fiber link. The position on the branch fiber.

If the optical loss measuring unit 602 is further configured to measure the light of the main fiber in the fiber link under test Loss; then the determining unit 603 at this time may include:

a first unit, configured to: according to the measured optical loss of the OLT and the tested optical fiber link opposite ONU or the branched optical fiber in the tested optical fiber link;

a second unit, configured to determine, according to the measured relationship between the optical loss of the branch fiber in the tested fiber link and the normal loss of the branch fiber, whether the event point is in the fiber link under test On the branch fiber.

If the optical loss measuring unit 602 is further configured to measure the uplink optical loss and the downlink optical loss of the backbone optical fiber in the tested optical fiber link, the optical loss measuring unit 602 measures the OLT and the tested optical fiber link opposite the ONU or the ONT. The optical loss of the optical path between the optical path and the optical path of the downstream optical path between the OLT and the opposite ONU or ONT of the tested optical fiber link;

The judging unit 603 at this time may include:

a third unit, configured to determine, according to the measured OLT, the opposite ONU of the tested fiber link or the uplink optical loss of the branch fiber in the tested fiber link; and the fiber link according to the measurement Determining the downstream optical loss of the branch fiber in the tested fiber link;

a fourth unit, configured to determine an uplink optical loss of the branch fiber in the tested fiber link according to the measured uplink optical loss of the branch fiber in the measured fiber link and the normal uplink optical loss of the branch fiber And determining, according to the measured downlink optical loss of the branch fiber in the measured fiber link and the normal downlink optical loss of the branch fiber, determining the downlink optical loss of the branch fiber in the tested fiber link The amount of change; and the relationship between the amount of change in the downstream optical loss, determining whether the event point is on the branch fiber in the fiber link under test.

FIG. 7 is a schematic diagram of another OLT structure according to the embodiment (corresponding to the method shown in FIG. 4). As shown in FIG. 7, the OLT is different from the OLT shown in FIG. 6 in an optical loss measuring unit 702. The optical loss measuring unit 702 includes: The energy measuring unit 7021 is configured to measure energy of the test signal, where the energy of the test signal is: energy of a test signal sent by the OLT side to the ONU/ONT side of the opposite end of the tested branch fiber, and/or by the detected branch The test signal sent from the ONU/ONT side of the fiber optic end reaches the energy of the OLT.

The peer energy test result obtaining unit 7022 is configured to obtain the energy of the test signal measured at the opposite end of the tested branch fiber, wherein the energy of the test signal is: the test signal sent by the OLT side reaches the opposite end of the tested branch fiber The energy of the ONU/ONT side or the energy of the test signal (on the ONU/ONT side) transmitted from the ONU/ONT side of the opposite end of the tested branch fiber to the OLT side.

That is, if the energy of the test signal measured by the energy measuring unit 7021 is the energy of the test signal sent from the OLT side to the ONU/ONT side of the opposite end of the tested branch fiber, the test obtained by the peer energy test result obtaining unit 7022 The energy of the signal is the energy that the test signal sent by the OLT side reaches the ONU/ONT side of the opposite end of the tested branch fiber; if the energy of the test signal measured by the energy measuring unit 7021 is from the ONU/ONT side of the opposite end of the tested branch fiber If the sent test signal reaches the energy of the OLT, the energy of the test signal acquired by the peer energy test result obtaining unit 7022 is a test signal sent from the ONU/ONT side of the opposite end of the tested branch fiber to the OLT side. The energy of the ONU/ONT side).

This function can be used to set the energy value of the test signal arriving at the end of the ONU/ONT side of the tested branch fiber to test the energy value of the test signal arriving at the end, or to measure the test signal sent from the end to the OLT side of the opposite end of the fiber under test. (on the ONU/ONT side), and the test result is uploaded to the peer end energy test result obtaining unit 7022 of the OLT end, and the peer energy test result obtaining unit 7022 learns the branch fiber pair to be tested according to the uploaded result. The energy value measured at the ONU/ONT side of the terminal.

It is to be noted that even if the loss of a certain optical fiber is too large or the fiber is broken, the measurement data of the ONU/ONT side of the branch fiber cannot be uploaded to the OLT of the transmitting end, and the OLT of the embodiment can be used to eliminate the Locate the event point of the branch fiber.

The calculating unit 7023 is configured to determine an optical loss of an optical path between the OLT and the ONU/ONT according to the energy of the sent test signal, the energy of the test signal reaching the ON/ONT, or according to the received The energy of the test signal, the energy of the test signal sent by the ONU/ONT side, determines the optical loss of the optical path between the OLT and the ONU/ONT. The calculation unit 7023 can also calculate the optical loss of the uplink optical path according to the received optical power of the OLT. The optical loss of the downstream optical path can be calculated according to the received optical power obtained by the opposite-end energy test result acquiring unit 7022 from the ONU.

It can be seen that when the event point is not on the trunk fiber, the OLT provided in this embodiment can determine the optical loss of the optical path between the OLT and the ONU/ONT of the opposite end of the tested branch fiber by using the optical loss measuring unit 702, and then judge The unit 603 determines whether the event point is on the currently measured branch fiber according to the optical loss result obtained by the optical loss measuring unit 702, and compares with the normal loss. If yes, the event point position determining unit 601 may first determine the event point and The distance of the OLT, according to which the location of the event point on the branch fiber is located. It can be seen that the OLT provided in this embodiment can support the function of locating event points on the branch fiber compared with the OLT of the prior art, and realizes the function of monitoring and locating event points on the OLT side.

Example 3:

FIG. 8 is a schematic structural diagram of an optical network according to an embodiment of the present invention. As shown in the figure, the optical network mainly includes: an OLT 80, an ONU/ONT 81, and a passive optical splitter; the optical network specifically includes:

The optical loss measuring unit 802 is configured to measure optical loss of the optical path between the OLT and the ONU/ONT of the opposite end of the tested branch fiber. In the optical network, the optical loss measuring unit 802 may include: a transmitting energy measuring unit 8021 disposed on the OLT 80 side, configured to measure, at the transmitting end OLT 80, an optical path sent between the OLT 80 and the ONU/ONT 81 at the opposite end of the tested branch fiber. Test the energy of the signal.

The receiving energy measuring unit 8022, which is disposed on the ONU/ONT81 side of the opposite end of the tested branch fiber, is configured to measure the energy of the test signal to the receiving end at the receiving end, and after receiving the data measured by the receiving energy measuring unit 8022, The measurement result or the measurement result subjected to the corresponding processing (such as the average calculation) is uploaded back to the calculation unit 8023 on the OLT 80 side that transmits the test signal.

The calculating unit 8023 disposed on the OLT 80 side is configured to receive the optical test signal measured by the energy measuring unit 8022 and returned by the receiving end ONU/ONT 81 according to the energy of the optical test signal sent by the transmitting end measured by the transmitting energy measuring unit 8021. The energy determines the optical loss of the optical path between the OLT 80 and the ONU/ONT 81.

a judging unit 803 disposed on the OLT 80 side for determining light according to the optical loss measuring unit 802 The relationship between the loss and the normal loss, determining whether the event point is on the branch fiber: if the optical loss is greater than the normal loss, determining that the event point is on the current branch fiber, and if the optical loss is equal to the normal loss, determining the event The point is not on the current branch fiber.

An event point location determining unit 801 is disposed on the OLT 80 side, configured to determine a distance of the event point from an OLT where the current event point location determining unit is located, and when the determining unit determines that the event point is on the branch fiber And determining a location of the event point on the optical fiber according to a distance of the event point from the OLT.

Generally, the event point location determining unit 801 is disposed on the OLT 80 side based on cost considerations, and the event point location determining unit 801 can be implemented by using an OTDR, OFDR, or other fiber detecting device or a similar functional module to determine the type of the event point. And the distance from the event point to the OLT 80. If the event point location determining unit 801 determines that the distance of the event point from the OLT 80 is less than or equal to the length of the backbone fiber, the event point is on the trunk fiber; otherwise, the event point is The trunk fiber is connected to the branch fiber.

For the case where the event point is on the branch fiber connected to the trunk fiber, the determining unit 803 is configured to determine that the event point is determined on the branch fiber that is currently being measured, and the event point location determining unit 801 is used to determine the event point from the current point. The distance of the OLT 80 determines the location of the event point on the fiber.

In addition, as shown in FIG. 9, the optical loss measuring unit 902 in the optical network may also adopt the following structural manner. As shown, the optical loss measuring unit 902 includes:

The transmitting energy measuring unit 9021 disposed on the ONU/ONT 91 side is configured to measure the energy of the test signal sent to the optical path between the OLT 90 and the opposite end of the tested branch fiber at the transmitting end ONU/ONT 91 of the test signal, and send the energy measuring unit. After the data is measured by the 9021, the measurement result is uploaded to the computing unit 9023 on the OLT 90 side through the uplink channel.

The receiving energy measuring unit 9022 disposed on the OLT 90 side of the opposite end of the tested branch fiber is configured to measure the energy of the test signal to the receiving end at the receiving end.

The calculating unit 9023 disposed on the OLT 90 side is configured to receive, according to the energy of the optical test signal sent by the transmitting end measured by the transmitting energy measuring unit 9021, the energy of the optical test signal measured by the energy measuring unit 9022 at the receiving end OLT90, and determine Optical loss on the fiber link where the branch fiber is located.

In addition, the optical loss measuring unit can be realized by the structure shown in FIG. 8 and FIG. It can also be realized by the following structure: The transmitting energy measuring unit and the receiving energy measuring unit are respectively disposed on both sides of the tested branch fiber (OLT, ONU/ONT side), and the calculating unit is set on the ONU/ONT side, in the calculating unit After calculating the optical loss of the optical path between the OLT and the ONU/ONT according to the measurement result of the transmitting energy measuring unit and the receiving energy measuring unit, the computing unit on the ONU/ONT side uploads the calculation result to the OLT side through the uplink channel, and the OLT The side judging unit 803 and the event point position determining unit 804 perform corresponding judgment and positioning according to the optical path loss.

It is to be noted that, in the optical network provided by the foregoing, even if the loss of a certain fiber is too large or the fiber is broken, the measurement result or the calculation result of the one end of the branch fiber cannot be uploaded to the opposite end, and the optical network of the embodiment is applied. In the excluded way, the event point of the branch fiber can still be located.

FIG. 10 is a schematic structural diagram of another optical network according to the embodiment. As shown in the figure, the optical network structure is different from the optical network structure shown in FIG. 8 in that the internal structure of the optical loss measuring unit is different, as shown in FIG. 10 . As shown, the optical loss measuring unit 1002 includes:

a reflection unit 1021 disposed on the ONU/ONT101 side of the opposite end of the tested branch fiber for transmitting a test signal to the ONU/ONT 101 side on the receiving end ONU/ONT 101 side, and reflecting the test signal back to the transmitting end OLT100 side.

An energy measuring unit 1022 disposed on the OLT 100 side for measuring the energy of the test signal on the OLT 100 side. The energy of the test signal includes: energy of a test signal transmitted to an optical path between the OLT 100 and the ONU/ONT 101, and energy of a test signal reflected by the reflection unit 1021 back to the OLT 100 side. The energy measuring unit 1022 can be implemented by a general energy testing unit or directly by an optical return loss testing device (OLTS).

The computing unit 1023 disposed on the OLT 100 side determines the energy between the OLT 100 and the optical network unit ONU/ONT 101 according to the energy of the transmitted test signal measured by the energy measuring unit 1022 and the energy of the reflected test signal. Light loss of the optical path.

The other units are basically the same as those in FIG. 8, and are not described herein. In addition, the OLT described in Embodiment 2 can be applied to constitute an optical network in this embodiment. I will not repeat them here.

It can be seen that the optical network provided by this embodiment implements the function of locating event points on the branch fiber on the OLT side with respect to the prior art. Moreover, since the optical network of this embodiment does not need to specifically limit the length of each branch fiber in the network, it has strong application feasibility. At the same time, in this network, only expensive event point location determining unit (which can be used by OTDR, OFDR or other light) The fiber detection device is implemented on the OLT side, which greatly reduces the network cost.

Example 4:

FIG. 11 is a schematic structural diagram of an ONU/ONT according to the embodiment. As shown in the figure, the ONU/ONT in this embodiment further includes:

The energy measuring unit 1101 is configured to measure energy of the test signal, where the energy of the test signal includes: an energy of the test signal sent by the ONU/ONT to the OLT side of the opposite end of the tested branch fiber, or an OLT side of the opposite end of the tested branch fiber The emitted test signal reaches the energy of the ONU or ONT.

The sending unit 1102 is configured to send the measurement result of the energy measuring unit 1101 to the OLT of the optical fiber opposite end, so that the OLT can calculate the optical loss of the optical path according to the measurement result of the ONU/ONT side energy measuring unit 1101. The event point on the branch fiber is located on the OLT side to reduce the network monitoring cost.

Example 5

The structure of the ONU/ONT in this embodiment is specifically as shown in the ONU/ONT 101 in FIG. 10, and the ONU/ONT includes:

The reflection device 1021 is configured to reflect the test signal back to the OLT side of the test signal transmitting end, that is, the OLT side of the opposite end of the tested branch fiber, so that the OLT can reach the OLT side by measuring the reflection. The energy of the test signal, combined with the energy of the test signal at the time of transmission, calculates the optical loss of the optical path. The event point on the branch fiber is located on the OLT side to reduce the network monitoring cost.

Implementation example 6:

The attenuation L0 of the backbone fiber is obtained by the OTDR test on the OLT side. The optical power measurement function integrated on the OLT and ONU side can obtain the line attenuation Li of the link between the OLT and the i-th ONU. ( Li-L0 ) is the line attenuation of the branch fiber where the i-th ONU is located. By monitoring the line attenuation and attenuation changes of each branch fiber, it is judged whether the performance of the corresponding branch fiber changes (whether or not there is an event point). Combined with the test results of the OT-end OTDR, the location of the event point on the corresponding branch fiber can be obtained. That is, the distance of the event point measured by the OTDR from the OLT is used to determine the position of the event point on the branch fiber.

Implementation example 7:

The general laser transmitter changes the optical power of the transmitted optical signal under normal operating conditions. small. Therefore, it is also possible to determine whether an event point exists on the link where the corresponding ONU is located by the OLT single-ended test of the ONU uplink signal optical power. The specific method is: the OLT saves the ONU uplink test signal (the test signal can be: the currently transmitted uplink data signal, or can be a specific test signal separately transmitted for the test), and the normal value of the received optical power (ie, normal reception) The normal value of the received optical power may be a calculation result of the historical received optical power (such as an average value) or a value of the received ONU upstream optical power of the ODN link under normal conditions. The OLT measures the optical power of the ONU uplink time slot (ie, the actual received energy of the uplink test signal) through the integrated power measurement unit, and compares it with the normal value of the received ONU received optical power. If the measured optical power value of the ONU uplink time slot is measured, If the received optical power is smaller than the saved ONU, the attenuation of the optical link on the corresponding ONU is increased, that is, the event point appears on the corresponding fiber link. Combined with the location of the event point obtained by the OTDR test on the OLT side from the OLT side, the specific location of the branch fiber where the event point is located can be determined.

Specifically, as shown in FIG. 12-A, step 1201: determining the type of the event point and determining the distance of the event point from the OLT, the step is usually implemented by an OTDR or OFDR placed in the OLT; Step 1203: The OLT measurement is received The energy of the uplink test signal sent by the optical fiber link ONU or the optical network terminal ONT, that is, the OLT measures the energy of the uplink test signal in the tested fiber link; wherein step 1203 may also be before step 1201. Execution; the execution of step 1201 and step 1203 may also be in no particular order. Step 1205: Compare the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal, determine whether the event point is on the tested fiber link, and if yes, perform step 1207, otherwise perform step 1209; 1207: Determine, according to the distance of the event point measured from the OLT in step 1201, the location of the event point on the tested fiber link; Step 1209, continue to monitor and determine whether the event point exists on other fibers, and the specific fiber The specific location on the.

Specifically, the determining process of determining whether the event point is on the tested fiber link (ie, step 1205 in FIG. 12-A) may be specifically as shown in FIG. 12-B.

Step 1211: The OLT measures the energy of the uplink test signal sent by the received optical fiber link ONU or the optical network terminal ONT, and the measurement may be performed by using an existing optical power meter, or may be other existing Technical progress;

Step 1213, comparing the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal to obtain the attenuation/loss change amount Lr of the tested fiber link; Step 1215, the OLT measures the loss La of the event point, and the step may actually be performed in step 1201 in FIG. 12-A;

Step 1217, determining whether the relationship between Lr and La conforms to the formula ζ _α = - 51og ₁ ¹ ₍ ^U ₎

If yes, step 1207 in Figure 12-A is performed, otherwise 1209 is performed.

The specific structure of the OLT is as shown in FIG. 13. The OLT is: The measuring unit 1302 measures the received optical power of each ONU in the uplink direction, and the determining unit 1304 can obtain the received optical power of each ONU according to the actual measured and obtained from the storage unit 1308. The normal value of the received optical power calculates the attenuation/loss variation of the link between the OLT and each ONU.

Since the optical fiber detection equipment such as OTDR or the function is used to measure the optical fiber on the point-to-multipoint optical network, the backward reflection/scattering of all the branched optical fibers is superimposed. When the splitting ratio of the splitter is good, the relationship between the actual loss of the branch fiber and the attenuation measured by the OTDR is:

When the splitting ratio of the splitter is not good, the formula can be adjusted using the prior art. In the formula, Lr is the actual loss of the branch or the loss of the event point. La is the loss of the event point on the fiber-optic detection equipment such as OTDR or the branch fiber detected by the function. in

The OLT side can calculate the link attenuation/loss between the OLT and each ONU by measuring the received optical power of each ONU, and can obtain Lr according to the attenuation/loss variation.

When the branch fiber is tested, the event location determining unit 1306 (which may be a fiber detecting device or function such as an OTDR) measures the type of each event point on the branch fiber (referring to the branch fiber segment, not knowing a specific branch fiber). , distance, loss of event point La. The energy measurement unit and the calculation unit can measure the loss of each branch fiber loss or the event point on the branch fiber.

The determining unit 1304 compares the La, and Lr measured by the event position determining unit 1306 by the above formula, and determines that the event point on the branch fiber obtained by the event position determining unit 1306 is specific to a certain branch fiber.

Those skilled in the art can understand that the measurement generally has a certain error, so an allowable range less than the degree can be set in advance, and if the actual received energy is less than the normal received energy to be within the preset allowable range, It is considered to be caused by factors such as measurement error, so the event point is not judged to be on the fiber link under test; conversely, if the actual received energy is smaller than the normal received energy by more than the preset allowable range, the event is judged. Point on the fiber link under test. Based on the technical solutions of the foregoing embodiments 6 and 7, the present invention further discloses an embodiment of a method for locating an optical fiber event point, including: determining a distance of an event point from an optical line terminal OLT; and measuring an actual uplink signal of the ONU or the ONT Receiving energy; comparing a relationship between an actual received energy of the uplink test signal and a normal received energy of a pre-stored uplink test signal; determining, according to the comparison result, whether the event point is on the fiber link under test, If yes, determining the location of the event point on the fiber link under test according to the distance of the event point from the OLT.

In addition, based on the technical solutions of the foregoing embodiments 6 and 7, the present invention further discloses a network device, which is an optical line terminal OLT. As shown in FIG. 13, the method includes: a measuring unit 1302, configured to measure the ONU Or the actual received energy of the ONT uplink test signal; the determining unit 1304 is configured to compare a relationship between an actual received energy of the uplink test signal and a normal received energy of the pre-stored uplink test signal, and determine, according to the comparison result, Whether the event point is on the measured fiber link; the event point location determining unit 1306 is configured to determine the distance of the event point from the OLT, and when the determining unit determines that the event point is in the When the fiber link is tested, the location of the event point on the tested fiber link is determined according to the distance of the event point from the OLT.

In addition, the OLT may further include a storage unit 1308 for storing normal received energy of the uplink test signal.

In addition, based on the technical solutions of the foregoing embodiments 6 and 7, the present invention also discloses an optical network, as shown in FIG. 14, including an optical line terminal OLT1400, an optical network unit ONU/optical network terminal ONT1440, and an OLT and an ONU. /ONT optical distribution network ODN1420, wherein the optical line terminal 1400 is an OLT correspondingly described in FIG. 13 and the corresponding description, and includes a measuring unit 1302, configured to measure an actual receiving energy of the ONU or ONT uplink test signal; 1304, configured to compare a relationship between an actual received energy of the uplink test signal and a normal received energy of a pre-stored uplink test signal, and determine, according to the comparison result, whether the event point is on the tested fiber link. The event point location determining unit 1306 is configured to determine the distance of the event point from the OLT, and when the determining unit determines that the event point is on the tested fiber link, according to the event The distance from the point to the OLT determines the location of the event point on the fiber link under test.

A few additional points will be given below for each of the above embodiments of the present invention. First, the normal loss mentioned in the foregoing embodiments may represent different meanings according to actual conditions, for example, it may be a theoretical normal loss value, or may be a normal loss interval after considering factors such as measurement error. , It can also be a loss value measured when the fiber is normal or a loss interval after considering factors such as measurement error.

In addition, when the above and downlink data signals are used as test signals, that is, the optical loss of the optical paths in the upper and lower directions is calculated by measuring the transmission and reception energy of the uplink and downlink data signals by the OLT and the ONU/ONT, the single-fiber bidirectional PON system is used. The wavelengths of the data signals in the upper and lower directions are different, and some events on the fiber have different effects on different wavelengths. For example, when the fiber is severely bent, the attenuation of the optical signal with a long wavelength is shorter than the attenuation of the optical signal with a shorter wavelength. small. Therefore, it is also possible to determine whether an event (such as bending) is at the OLT to an ONU by combining the change in the optical attenuation in the upstream and downstream directions (ie, the relationship between the amount of change in the optical loss of the upstream optical path and the amount of change in the optical loss of the downstream optical path). /ONT's light path. In summary, the technical solution of the embodiment of the present invention can realize the function of locating and monitoring network event points on the OLT side, and locating event points on the branch fiber, thereby greatly reducing the cost; more suitable for practical application. In the meantime, the technical solution of the embodiment of the present invention is applied, even if the loss of a certain optical fiber is too large or the fiber is broken, the data on the ONU/ONT side of the branch fiber cannot be uploaded, and the event of the branch fiber can be located by the exclusion mode. point.

The method, the optical network, and the network device for locating the event point of the branch fiber provided by the embodiment of the present invention are described in detail. The principle and the implementation manner of the embodiment of the present invention are described in the following. The description of the embodiments is only for the purpose of facilitating the understanding of the embodiments of the present invention. For those of ordinary skill in the art, in accordance with the principles of the embodiments of the present invention, there may be changes in the specific embodiments and application scopes. The contents of this specification are not to be construed as limiting the invention.

Claims

Rights request

A method for locating an event point of an optical fiber, comprising:

Determining the distance of the event point from the optical line terminal OLT;

The optical line terminal OLT measures the received energy of the uplink test signal sent by the ONU or the optical network terminal ONT of the tested optical fiber link;

Comparing the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal, determining whether the event point is on the tested fiber link, and if so, according to the event point Describe the distance of the OLT to determine the location of the event point on the fiber link under test.

2. The method of claim 1 wherein:

Comparing the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal, determining whether the event point is on the tested fiber link includes:

Comparing the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal, if the measured energy of the uplink test signal is less than the normal received energy of the pre-stored uplink test signal, or the measured uplink test If the energy of the signal is less than the preset received range of the pre-stored uplink test signal, the event point is determined to be on the fiber link under test.

The method according to claim 1, wherein the comparing the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal, determining whether the event point is in the The test fiber link is specifically:

Comparing the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal to obtain the attenuation/loss variation Lr of the tested fiber link; comparing the attenuation/loss of the tested fiber link The variation Lr and the loss La of the event point measured by the OLT, if the relationship between Lr and La conforms to the formula Za = -51og ₁₍₎ [^ ₊ ^] ,

^1U LNN ” then determines that the event point is on the fiber link under test.

The method according to any one of claims 1-3, wherein the normal value of the received optical power is an average value of historical received optical power, or an ONU received by the ODN link under normal conditions. The value of the optical power.

5. A method according to any of claims 1-4, characterized in that The normal received energy of the uplink test signal is previously stored in the optical line terminal OLT.

The method according to any one of claims 1-5, wherein the uplink signal sent by the optical network unit ONU or the optical network terminal ONT is: an uplink data signal, or a specific test signal.

A network device, wherein the network device is an optical line terminal OLT, and the method includes: an energy measurement unit, configured to measure an uplink test sent by an optical network unit ONU or an optical network terminal ONT of the opposite end of the tested optical fiber link. The energy of the signal;

a determining unit, configured to compare the measured energy of the uplink test signal with a normal received energy of the pre-stored uplink test signal, and determine whether the event point is on the tested fiber link;

An event point location determining unit, configured to determine a distance between the event point and the OLT, and when the determining unit determines that the event point is on the fiber link under test, according to the event point

The distance of the OLT determines the location of the event point on the fiber link under test.

8. The network device according to claim 7, wherein:

The determining unit is configured to compare the measured energy of the uplink test signal with the normal received energy of the pre-stored uplink test signal, if the measured energy of the uplink test signal is less than the normal reception of the pre-stored uplink test signal. The energy, or the measured energy of the uplink test signal is less than the normal received energy of the pre-stored uplink test signal exceeds a preset range, and the event point is determined to be on the fiber link under test.

9. The network device according to claims 6-8, characterized in that:

A memory unit is further included for storing a normal received energy of the uplink test signal.

10. An optical network, characterized by comprising:

Optical line terminal OLT, optical network unit ONU/optical network terminal ONT, and optical distribution network ODN connecting OLT and ONU/ONT;

The OLT is an optical line termination as claimed in claims 6-9.