WO2007134520A1 - A method for maintaining the passive optical network, an optical network element and an optical line terminal - Google Patents

Abstract

A method for maintaining the passive optical network, an optical network element and an optical line terminal are used for solve the problem that it can not detect and insulate the failed optical module at the optical line terminal side in the prior art. In the said maintaining method, when the optical line terminal detects the continuously occupied time of the upstream communication line exceeds the preset threshold, it detects the failed optical network element continuously occupying the upstream communication line, and indicates the failed optical network unit to shut off the transmitting circuit power with control message or control signal. In order to realize the method, the optical line terminal of the invention includes a maintaining module for detecting the fault and performing the fault processing, the transmitting power and the receiving power of the optical network element are placed independently, and the transmitting power control module turns on or shuts off the transmitting power according to the control message or control signal of the optical line terminal. The technical scheme of the invention realizes the detect and the insulation of the failed optical network element.

Description

 " Passive optical network maintenance method, optical network unit and optical line terminal

 The present invention relates to a passive optical network, and more particularly to a passive optical network maintenance method, an optical network unit, and an optical line terminal. Background technique

 In larger and larger broadband access networks, most of the existing LANs operate on 100Mbit/s access networks, and many large-scale commercial companies are transitioning to Gigabit Ethernet (GE). On the metro core network and the metro edge network, the Synchronous Optical Network (SONET)/Synchronous Digital Hierarch (SDH)/GE bandwidth capacity is very abundant, which makes the access network part seriously. Bandwidth bottleneck. Compared with cable transmission, optical fiber transmission has the advantages of large capacity, low loss, and strong anti-electromagnetic interference capability. Therefore, as the transmission cost of optical fiber is gradually reduced, the fiberization of the access network is an inevitable development trend. Passive Optical Network (PON) is one of the main technologies for fiber access. According to the depth of fiber penetration, fiber access can be divided into fiber to the home (FTTH, Fiber to the Home), fiber to the building (FTTB). , Fiber to the Building/Curb ), Fiber to the Curb (FTTC, Fiber to the Cabinet), Fiber to the Prefess (FTTP), Fiber to the Premises, etc. To X (FTTX, Fiber to the X).

 According to the content of the bearer, the PON technology mainly includes APON (ATM (PON) PONs), EPON (Ethernet Based PONs), and GPON (Gigabit PONs). As shown in Figure 1, the PON network includes an optical line terminal (OLT) located at the central office. , Optical Line Terminal ) and a series of optical network units/terminals (ONU/ONT, Optical Network Unit/ Terminal) located at the customer premises, optical distribution between the OLT and the ONU/ONT via optical fibers, passive optical splitters or couplers Network (ODN, Optical Distribution Network) connection.

In a PON network, a single fiber can be pulled from the service switching office to a broadband service sub-area or office park, and then a passive splitter or coupler is used to separate several branches from the main fiber to each building. Or on a business device. This approach allows multiple users to share a relatively expensive fiber link from the exchange to the customer premises, thus greatly reducing the cost of using FTTB and FTTH.

 Passive optical networks do not have any active devices from the central switching office to the customer premises network. Instead, passive optical components are inserted into the network and power distribution is used to achieve single-point transmission to multiple points over the entire path. . This replacement eliminates the need for service providers to provide energy and maintenance to active devices in the transmission loop, which greatly reduces the cost of the service provider. Passive splitters and couplers only serve to transmit and limit light, eliminating the need for power and information processing, and reducing service provider maintenance costs.

 By using APON/BPON, EPON or GPON technology to be standardized, 155Mbit/s, 622Mbit/s, 1.25Gbit/s or 2.5Gbit/s can be supported on the PON backbone fiber. To support both voice, data, and video applications, each user's bandwidth allocation can be static or dynamic.

 The basic structure of the existing OLT is as shown in FIG. 2, and the basic structure of the ONU/ONT is as shown in FIG. 3, which includes an optical module, a service processing module, and a power module that receive the illuminating signal, where: the optical module includes:

 The receiving circuit is connected to the uplink channel for receiving the uplink signal and performing photoelectric conversion; the transmitting circuit is connected to the downlink channel for photoelectrically converting the electrical signal to be transmitted and transmitting through the downlink channel;

 SD (Signal Detect) signal monitoring circuit is used to monitor whether the uplink channel is continuously occupied, that is, whether an optical signal arrives, and the detection result is output through the SD terminal. If an optical signal arrives, the SD terminal output signal is High level, and vice versa output low level;

 The working power circuit is configured to provide working power to the optical module. In the prior art, the working power of the transmitting circuit and the receiving circuit are combined.

The service processing module of the OLT end (CNI, Central Network Interface) network connecting central office ^ ¹ carry an uplink port, ONU / ONT- end connected to the user equipment through a user network interface (UNI, User Network Interface) through the center of the network interface, of course, OLT The necessary structure of the ONU/ONT is also included in the basic structure. The downlink data stream in the PON network is broadcasted from the OLT to each ONU/ONT. Each ONU/ONT transmits the address information in the unit header through the matching protocol, and only processes the destination address and its own matching data. Uplink traffic transmission is relatively complicated. In a point-to-multipoint passive optical network system, each ONU/ONT terminal transmits to the OLT through Time Division Multiple Addressing (TDMA) mode due to the characteristics of the shared medium in the ODN. Data, in order to avoid the occurrence of conflicts, the OLT allocates different time slots (authorizations) to the registered ONUs/ONTs according to the buffering conditions of the data to be sent reported by the ONU/ONT. The ONUs only allocate time slots in the OLT (authorization) The optical module is turned on, so under normal circumstances, the uplink path is occupied by time division, and the SD signal of the OLT side optical module is a pulse signal.

 The OLT allocates time slots (authorizations) to each ONU to ensure that only one ONU can emit light at the same time, that is, a specific transmission time slice represents a specific ONU/ONT, and synchronization of these time slices can avoid generation of different ONU/ONT bursts. conflict. However, if an optical module of an ONU/ONT fails, it is in a constant lighting state, or a malicious user sets the optical module to be constantly illuminated, then other ONUs connected to the ONU under the same OLT port will be completely paralyzed, and the traditional Compared to the peer-to-peer system, such an impact is unacceptable. Summary of the invention

 The embodiments of the present invention provide a passive optical network maintenance method, an optical network unit, and an optical line terminal, to solve the problem that the faulty optical module cannot be detected and isolated on the optical line terminal side in the prior art.

 A method for maintaining a passive optical network, comprising:

 The optical line terminal monitors the continuous occupation time of the uplink path, and detects the faulty optical network unit that continuously occupies the uplink path when detecting that the persistent occupation time exceeds a set threshold;

 The optical line terminal instructs the faulty optical network unit to turn off the transmit circuit power.

 An optical network unit, including an optical module, further includes:

 Sending a power module, configured to provide a working power to the transmitting circuit of the optical module;

Sending a power control module, configured to turn the transmit power module on or off according to an external power control command. An optical line terminal includes an optical module, and the optical line terminal further includes:

 The fault maintenance module monitors the uplink path of the optical module for longer than the fault state of the set value, detects the fault source, and performs fault maintenance.

 In the method for maintaining a passive optical network according to the embodiment of the present invention, the optical line unit side monitors whether a normal illumination fault occurs, and performs detection and maintenance of the fault optical network unit, and the fault monitoring and detection mechanism realizes reliable single-unit, and realizes the common Isolation and fault maintenance of the illuminated faulty optical network unit. DRAWINGS

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

 2 is a schematic diagram of a structure of an existing OLT;

 Figure 3 is a schematic diagram of the existing ONU structure;

 4 and FIG. 5 are schematic diagrams of a process of detecting and maintaining a normal illumination fault according to an embodiment of the present invention; FIG. 6 is a schematic structural diagram of an OLT according to an embodiment of the present invention;

 FIG. 7 is a schematic structural diagram of an ONU according to an embodiment of the present invention. detailed description

 In order to ensure the normal operation of the network, when a certain ONU/ONT (hereinafter referred to as ONU) terminal is in the normal lighting state due to the failure of the burst function, it is necessary to isolate the faulty ONU so that it does not affect other A working OJ user.

 First, the ONU is required to detect and determine the ONU of the normal illumination fault. The embodiment of the present invention provides the following detection mechanism according to different types of normal illumination faults of the ONU/ONT optical module:

 Fault Type 1. Only one ONU optical module has a burst function that is in a normal lighting state, but can also send normal data.

In this case, since the OLT does not receive any information of other normal ONUs for a long time, it is considered that all other normal ONUs are dropped, causing all other normal ONUs to be unregistered, and the OJ that normally emits light can also be registered normally, and The OLT sends data or control signaling, so the SD signal of the OLT optical module must be always high (maintaining a high level). Under normal circumstances, if only one ONU is online and other ONUs are offline, for example, when the user is not powered on or powered off, the ONU on the line intermittently turns on the optical module in the time slot allocated by the OLT. The SD signal of the OLT optical module should be a pulse signal. .

 The OLT is registered in the ONT, and all other devices are offline. When the SD signal of the OLT optical module is always high, the OLT can determine that the currently registered ONU optical module is faulty and is in the normal light state. Since the information sent by the ONU can be correctly received, the fault ONU can be directly determined. At this time, if the fault ONU is turned off, the other ONUs can work normally.

 Fault type 2: Only one optical module has a burst function failure, is in a constant illumination state, and cannot transmit normal data, and the transmission is completely a messy noise signal;

 In this case, all ONUs (including ONUs with this optical module failure) will be dropped and not registered. Moreover, the SD signal of the OLT optical module must be always high (maintaining a high level).

 After this happens, the OLT can determine that a fault condition has occurred, but it cannot immediately determine the faulty ONU. In this case, all ONUs can be shut down first, then the OUs can be opened one by one, and the working status is detected. If an ONU cannot be registered normally, , then the optical module of the ONU has failed. After the faulty ONU is shut down, the system can be restored.

 Fault type 3, two or more optical modules have a burst function failure, and are in a constant light state (the transmission may be normal data or a noise signal);

 In this case, the OLT cannot receive any ONU information correctly. Therefore, all ONUs (including ONUs with optical module failures) will be dropped and not registered. At this time, the SD signal of the OLT optical module is also always high (maintaining high level). constant).

 After the above situation occurs, the OLT can not immediately determine the faulty ONU. At this time, all ONUs can be turned off first, and then the ONUs are turned on one by one to detect the working status. If an ONU cannot be registered normally, or it can be registered normally. If the SD signal is always high, then the optical module of the ONU has failed. The OLT sends a command to close the OJ optical module. When all ONUs are detected, the OLT can open other normal ONUs and the system returns to normal.

In the technical solution provided by the embodiment of the present invention, the OLT sends a shutdown command to the ONU to implement detection control. Although the optical module has an on/off control signal, the optical module is faulty. It may be that the external control signal is not responded, so a feasible method is to instruct the faulty ONU to turn off the transmission power of the optical module, so that the optical module can receive the signal normally. However, if the receiving part of the optical module of the faulty ONU fails to receive the shutdown command from the OLT, in this case, the OLT optical module can be continuously turned on and off several times, and the ONU end receives multiple consecutive pulse signals. The instruction is used as an alternative to turning off the power supply.

 In summary, the OLT can determine the fault state according to whether the output signal of the SD terminal of the optical module continues to be high level, and then send a control command to the ONU to detect the fault ONU and perform fault maintenance, and the specific maintenance process can be performed. The setting cycle is started periodically to realize the need of periodic monitoring, and can also be automatically cycled. The following is a detailed description of the cycle monitoring. The specific processing flow is shown in Figure 4, including the following steps:

 51. The OLT detects the continuous occupation time of the uplink channel;

 The OLT usually detects the output signal of the SD terminal of the optical module on the side of the optical module. When the optical signal arrives in the uplink path, the output signal of the SD terminal is at a high level. By detecting the duration of the high level, the uplink channel can be continuously occupied. time.

 52. Determine whether the persistent occupation time exceeds a set threshold. If yes, the OLT sends a compensation delay parameter to the optical network unit according to the set threshold. If the continuous occupation time cannot be changed, continue S3; otherwise, return to step S1. ; The set threshold is the range of time slots that the OLT authorizes to the ONU for upstream data.

 The compensation delay is the internal delay of the optical network unit, which is set and controlled by the optical line terminal. The purpose of this parameter is to delay the upstream transmission so that the upstream data of the ONU can reach the optical line terminal with the same phase. The arrival time of the optical network unit transmission may drift due to aging or temperature changes. Therefore, adjusting the compensation delay can solve this drift, but it is not valid for the normally-on fault ONU.

 Of course, the optical network unit can be directly sent to the optical network unit without issuing the compensation delay parameter, and the fault ONU can still be detected and maintained.

 53. Determine whether there is only one ONU currently registered, if yes, continue to S4; otherwise, go to step gland S6;

54. The OLT determines that the ONU is faulty, and sends a shutdown power transmission command to the ONU. After the OLT issues the power-off command, it determines whether the uplink channel is idle. If yes, the ONU receiving part is normal, and the power-off command is correctly executed. Otherwise, the ONU receiving part also fails, and the power-off command cannot be correctly executed. The OLT The optical module can be controlled to be continuously turned on and off several times, and a pulse command is sent to the ONU. After the ONU receives the pulse signal, the SD terminal simultaneously outputs a corresponding pulse detection signal, and the ONU terminal control device can turn off the optical module according to the pulse signal.

 55. The OLT reports the fault ONU information to the maintenance center and returns to step SI. If the monitoring is performed periodically, the step ends after the completion of the step, and waits for the next monitoring period.

 56, judging whether all ONUs are offline, that is, no ONU is currently registered, if yes, continue to S7; otherwise, go to step S9;

 57. The OLT detects and closes the fault ONU;

 58. After turning on other normal ONUs, returning to step S5;

 59. If the system is normal and the maintenance center is up, go back to step S1. If it is monitored periodically, this step will be completed and wait for the next monitoring period.

 As shown in FIG. 5, in the above step S7, the OLT detects and closes all the faults O U by the following specific steps:

 The S70K OLT broadcasts the control packet for sending power to all ONUs that are currently connected.

5702, determining whether the uplink path is idle, if yes, proceeding to step S704; otherwise, proceeding to step S703;

 5703. The OLT sends a pulse signal for forcibly turning off the power transmission to all the currently connected ONUs. If the receiving part of all the ONUs is normal, the ACK signal can be received and executed, and the uplink path is idle. Otherwise, the receiving part exists. For a faulty ONU, the ONU that receives the partial fault must be closed by a forced close command.

 The OLT controls the optical module to output the pulse signal by changing the transmission enable signal of the optical module to the pulse enable signal.

 In actual implementation, after step S703, the process may return to step S702 to confirm whether the uplink path is idle.

5704. Obtain information about all ONUs currently connected, and select an ONU to be tested. S705: Send an open power transmission command to the ONU to be tested and start detecting the continuous occupation time of the uplink channel;

 5706. Monitor whether the continuous occupation time of the uplink channel occupied by the ONU exceeds a set time threshold. If yes, further adjust the delay time of the abnormal optical network unit, and the compensation delay adjustment may be determined to be a constant illumination failure. Otherwise, go to step S708;

 When the ONU is normal, after the ONU's transmit circuit power is turned on, the normal registration process is performed and the uplink channel is occupied according to the allocated time slot. Otherwise, the uplink channel is continuously occupied after the transmit circuit power is turned on, so by monitoring the test. The ONU occupies the continuous occupation time of the uplink channel or further adjusts the compensation delay to determine whether a fault has occurred. It should be noted that even if the ONU to be tested cannot be registered, if the uplink channel occupancy time is zero, it has no influence on the uplink path, and is not a detection and maintenance range of the constant illumination fault.

 The uplink channel occupation time is still monitored by detecting the high-level duration of the output signal of the SD terminal of the optical module, and the set time width is equal to the uplink time slot range allocated by the OLT for each ONU, if the ONU to be tested is allocated according to the time interval. The gap continues to occupy the uplink path, and is automatically turned off at the end of the time slot. The duration of the uplink channel is less than the set time threshold. Otherwise, after the transmission power of the ONU to be tested is turned on, the uplink channel is continuously occupied. When the time exceeds the set time threshold, it may be determined that the ONU to be tested transmits a partial fault.

 5707. Record that the ONU to be tested is a fault ONU;

 S708: Send a power off control message to the ONU to be tested.

 The transmit power control message is extended by the control message or operation and maintenance message defined in the existing passive optical network, or defined according to the existing protocol.

 During the detection process, the transmission power of the detected normal ONU must also be turned off.

 5709, determining whether all the ONUs to be tested are detected, if yes, proceeding; otherwise, performing step S8;

5710. Select another ONU to be tested from all undetected ONUs, and then return to step S705. Through the above loop detection, the OLT can detect all faulty ONUs, including transmitting partial faults but receiving partial normal ONUs, and receiving and transmitting partial ONUs that are faulty.

During the above detection process, the OLT records and reports the fault ONU information, and closes all the The barrier ONU and all normal ONUs are turned on again to restore the PON network to normal operation. In the above monitoring and maintenance process, the ONU is often eliminated, and if it is necessary to detect the faulty ONU that cannot be registered at the same time, the method in the embodiment of the present invention may add query registration information to determine the ONU to be tested between step S705 and step S706. If the ONU is registered, the process proceeds to step S706 to monitor the uplink path occupation time. Otherwise, the ONU to be tested is recorded as the fault ONU, and then the process goes to step S708. The ONU of the to-be-tested device is not registered, indicating that the transmitting part of the ONU to be tested completely loses its function. Neither the normal signal nor the noise can be sent. Although the use of the upstream path is not affected, the faulty ONU should still be recorded and reported to the maintenance center.

 As shown in FIG. 6, the embodiment of the present invention further provides an OLT 60 structure, including an optical module 61 and a service processing module 62, and further includes:

 The fault maintenance module 63 is connected to the optical module 61, and monitors the uplink path of the optical module 61 to be continuously occupied for a time exceeding a set threshold, detects the fault source, and performs fault maintenance.

 The fault maintenance module 63 can further include:

 The fault monitoring sub-module 631 is connected to the optical module 61, configured to monitor the fault state and output a fault indication signal;

 The fault processing sub-module 632 performs fault source detection and performs fault maintenance according to the fault indication signal;

 The fault information reporting sub-module 633 is configured to report the detected fault source information to the maintenance center. The service module 62 is connected between the optical module 61 and the fault processing sub-module 632 for receiving the relevant fault processing instruction generated by the fault processing sub-module 632 and transmitting it through the optical module 61. The optical module 61 includes an SD terminal. The fault monitoring sub-module 631 is connected to the SD terminal and monitors the fault state according to an output signal of the SD terminal;

The fault processing sub-module 632 is connected to the transmitting enable signal Tx_disable (transmit enable/disable) receiving end of the optical module 61, and the pulse enable/disable signal is input to the Tx-disable receiving end of the optical module 61. The control light module 61 outputs a pulse signal. The fault maintenance module 63 can be set separately or in combination with an existing control module of the OLT. As shown in FIG. 7, the embodiment of the present invention further provides an ONU 70 that cooperates with the OLT 60, and includes an optical module 71 and a service processing module 72, and further includes:

 The sending power module 73 is connected to the optical module 71 for providing a working power to the transmitting circuit of the optical module 71.

 Transmit power control module 74, connected to the transmit power module 73, for turning on or off the transmit power module 73 according to an external power control command;

 The receiving power module 75 is connected to the optical module 71 for providing the receiving circuit working power to the optical module 71.

 The service processing module 72 is connected between the optical module 71 and the transmission power control module 74 for receiving the external power control command and forwarding to the transmission power control module 74;

 The service processing module 72 includes: an instruction identification sub-module 721, configured to identify the external power control command and forward the same to the power control module.

 The sending power control module 74 can specifically include:

 The instruction parsing sub-module 741 is connected to the instruction identifying sub-module 721 for parsing the external power control command;

 The instruction execution sub-module 742 is connected between the instruction analysis sub-module 741 and the transmission power module 73, and is configured to generate a corresponding control signal according to the analysis result and output the signal to the transmission power module 73.

 The optical module 71 includes an SD terminal for outputting a detection signal for whether an optical signal arrives. The transmit power control module 74 further includes: a pulse signal monitoring sub-module 743 connected between the SD terminal and the instruction execution sub-module 742 And when the detection signal of the SD terminal output signal is the set pulse signal, the instruction execution sub-module 742 is instructed to close the transmission power module 73.

In the above ONU, the transmission power and the reception power of the optical module are separately provided, and the transmission power can be turned on and off by the control module. When an abnormal situation occurs, the OLT can send an instruction to turn off the optical module to an ONU or all ONUs. After receiving the instruction, the ONU control module turns off the power transmission of the optical module. The specific shutdown command passes the existing control message, OAM (Operation And Maintenance, operation and maintenance) Packet extension, or customization according to existing protocols, specific extension and definition It is well known to those skilled in the art and will not be described here.

 The transmission power control module can be separately set, or can be combined with the existing control module of the OLT. By using the OLT and the ONU described above in the embodiment of the present invention, a fault maintenance system is formed in the PON network, which can realize the constant illumination of the PON network. Fault detection and maintenance.

 The technical solution of the embodiment of the present invention implements the single-sheet, and the detection mechanism on the OLT is not complicated, and can be easily realized. The ONU only needs to separate the power supply circuit of the optical module, and separately performs the opening/closing control of the transmission power. Compared with the existing passive optical network system, the cost is basically not increased, and the detection and isolation of the faulty ONU is realized, the reliability and stability of the PON system are greatly improved, and the maintainability of the ONU terminal is also improved.

 In the method for maintaining a passive optical network according to the embodiment of the present invention, the optical line unit side monitors whether a normal illumination fault occurs, and performs detection and maintenance of the fault optical network unit, and the fault monitoring and detection mechanism realizes reliable single-unit, and realizes the common The isolation and fault maintenance of the illuminating faulty optical network unit; further, the method described in the embodiment of the present invention can simultaneously detect the fault optical network unit that cannot be registered by querying the registration information, thereby further improving the reliability and stability of the passive optical network. The present invention also provides an optical line terminal that can perform fault monitoring and fault maintenance, in order to achieve the above-mentioned technical solutions. As well as supporting the use of optical network units, the cost has not increased substantially. The spirit and scope of the embodiments of the present invention are departed. Thus, it is intended that the present invention cover the modifications and modifications of the embodiments of the invention.

Claims

Rights request A method for maintaining a passive optical network, comprising:  The optical line terminal monitors the duration of the uplink path, and upon detecting the persistent occupancy, the optical line terminal instructs the faulty optical network unit to turn off the transmit circuit power.  2. The method according to claim 1, wherein the detecting the single unit of the fault optical network, and determining whether the compensation delay of the optical network unit can change the continuous occupation time of the uplink channel If yes, it is a normal optical network unit, otherwise it is a faulty optical network unit.  The method according to claim 1, wherein the detecting the faulty optical network unit that continuously occupies the uplink path, and instructing the faulty optical network unit to turn off the power of the transmitting circuit comprises:  Determining whether there is currently only one optical network unit in a registered state, and if so, recording the optical network unit to be tested as a fault optical network unit, indicating that the faulty optical network unit turns off the power of the transmitting circuit;  Determining whether all the optical network units currently connected are offline. If yes, respectively detect each optical network unit currently connected and determine the fault optical network unit therein, indicating that all faulty optical network units turn off the power of the transmitting circuit; otherwise, confirm the network operation. normal.  The method according to claim 3, wherein the detecting each optical network unit that is currently connected and determining the faulty optical network unit therein, the method for indicating that all the faulty optical network units turn off the power of the transmitting circuit specifically includes: : Broadcasting to close the control packet of the sending circuit power, and determining whether the uplink path is idle, and if so, selecting one optical network unit to be tested one by one from all currently connected optical network units; otherwise, to each optical network unit currently connected Sending a pulse signal command for instructing to turn off the power of the transmitting circuit, and then selecting one optical network unit to be tested one by one from all currently connected optical network units; sending a control message for turning on the power of the transmitting circuit for each optical network unit to be tested first And judge .^ ^ l3⁄4J1JL , ^口果是贝] Record the optical network unit to be tested as the fault optical network unit; otherwise, send a control message to the optical network unit to be tested to turn off the power of the transmitting circuit;  After all the optical network units are detected, a control message for turning on the power of the transmitting circuit is sent to each non-faulty optical network unit.  5. The method according to claim 4, wherein the method further comprises: when the light to be measured If yes, send a control packet to the optical network unit to be tested to turn off the power of the transmitting circuit; otherwise, record the optical network unit to be tested as a faulty optical network unit. .  6. The method of claim 1, 2, 4 or 5, wherein the set threshold is a range of uplink time slots authorized by the optical line terminal to the optical network unit.  The method according to claim 4 or 5, wherein, after each of the optical network units to be tested first sends a control message for turning on the power of the transmitting circuit, the system further queries whether the optical network unit to be tested is set. The value is abnormal, otherwise the optical network unit to be tested is recorded as a faulty optical network unit.  8. The method according to claim 4, wherein the optical line terminal controls the optical module to output the pulse signal by inputting a pulse transmission enable/disable signal to the optical module.  The method of claim 4, wherein the method further comprises: the step of reporting, by the optical line terminal, the network operation normal or faulty optical network unit information to the maintenance center.  An optical network unit, comprising: an optical module, wherein the optical network unit further includes:  Sending a power module, configured to provide a working power to the transmitting circuit of the optical module;  Sending a power control module for turning the transmit power module on or off according to an external power control command. The optical network unit of claim 10, wherein the optical network unit further comprises: a service processing module, connected between the optical module and the power control module, configured to receive the external power control command and forward the same to the transmit power control module;  The receiving power module is connected to the optical module, and is configured to provide a working power of the receiving circuit to the optical module.  The optical network unit according to claim 11, wherein the service processing module includes:  An instruction identification submodule for identifying the external power control command and forwarding to the transmission power control module.  The optical network unit according to claim 12, wherein the transmission power control module comprises:  An instruction parsing submodule, connected to the instruction identifying submodule, for parsing the external power control command;  The instruction execution submodule is connected between the instruction parsing submodule and the receiving power module, and is configured to generate a corresponding control signal according to the parsing result and output the signal to the transmitting power module.  14. The optical network unit of claim 13 wherein:  The optical module includes a signal detection SD terminal for outputting a detection signal indicating whether an optical signal arrives;  The transmit power control module further includes: a pulse signal monitoring submodule, when the detection signal of the SD terminal output signal is a set pulse signal, instructing the instruction execution submodule to close the transmit power module.  An optical line terminal, comprising: an optical module, wherein the optical line terminal further includes:  The fault maintenance module monitors the fault condition of the uplink path of the optical module for more than the set value of the fault value, detects the fault source end, and performs fault maintenance.  The optical line terminal according to claim 15, wherein the fault maintenance module comprises: a fault monitoring submodule, configured to monitor a fault state of the optical module and output a fault indication signal; The fault processing submodule performs fault source detection and performs fault maintenance according to the fault indication signal;  The fault information reporting sub-module is used to report the detected fault source information to the maintenance center. The optical line terminal according to claim 16, wherein the optical line terminal further comprises: a service processing module, configured to receive an relevant fault processing instruction generated by the fault processing submodule and send the same through the optical module.  The optical line terminal according to claim 16, wherein the optical module comprises: an SD terminal connected to the fault monitoring submodule for outputting a detection signal of an optical signal arrival; an enable/disable signal The terminal is connected to the fault processing submodule and receives a pulse enable/disable signal of the fault processing submodule.