Example 1
 When the backbone fiber of the main OLT in the PON network fails (or the main OLT fails), the PON network needs to perform a main-standby switchover to switch data to the standby OLT. This embodiment is based on figure 2 The schematic diagram of the active/standby switch provided is taken as an example. During the switchover of the active and standby OLTs, due to the difference in the length of the active and standby backbone fibers, the standby OLT is the new active OLT. The ONU performs re-ranging processing. In order to reduce the ranging time required for performing ranging processing on all the connected ONUs and reduce the service interruption time, an embodiment of the present invention provides a method for transmitting data on an optical network. See image 3 In this embodiment, the main-use OLT's backbone fiber fails and needs to be switched as an example for description. The content of the method is as follows:
 101: The active OLT detects the loss of signal LOS (Lost Of Signal) alarm and triggers the switchover of the active and standby OLTs; the original active OLT is transformed into a standby OLT, and the original standby OLT is transformed into a new active OLT (the following is convenient for description, in business Before the transmission resumes, the new active OLT is still called the standby OLT). Each ONU detects a LOS alarm and enters the POPUP state.
 Among them, when the main optical fiber of the main OLT fails, the main OLT and each ONU will detect the signal loss LOS alarm because the main OLT and each ONU cannot receive the signal from each other. The main OLT detects the LOS alarm and learns that the main main optical fiber is faulty. , Need to switch between the active and standby OLTs: switch the data flow of the connected ONU to the standby OLT, and use the standby backbone fiber provided by the standby OLT to communicate with each ONU; when each ONU device detects a LOS alarm, the normal working The OPERATION state switches to the suspended POPUP state. At this time, the service transmission of the standby OLT and each ONU is in an interrupted state.
 102: The active OLT sends the saved parameters of each ONU to the standby OLT through the communication link, and the standby OLT obtains the parameters of each ONU.
 Wherein, in this step 102, the standby OLT obtains each ONU parameter, which may occur after step 101, or at any time before step 101 (for example, when the PON system is deployed, the parameters of the connected ONUs are respectively The configuration is pre-stored in the active and standby OLTs. This embodiment of the invention does not limit the specific way and time for the standby OLT to obtain the parameters of the connected ONUs, but it must be ensured that the standby OLT has successfully obtained the access before step 106 is executed. The parameters of each ONU.
 Among them, the parameters of each ONU include: the round-trip delay Rtd value of the ONU obtained by the primary OLT, the identification of each connected ONU, and the like. Among them, Rtd = ONU processing delay value + branch fiber propagation delay value + backbone fiber propagation delay value + OLT processing delay value. In order to facilitate the description, the Rtd value of the ONU obtained by the main OLT can be called the main Rtd of the ONUi, which is expressed as Rtd (main) ONUi (among them, ONUi Indicates the i-th ONU among the connected ONUs).
 103: The standby OLT selects a ranging ONU from the connected ONUs, and performs ranging on the ranging ONU.
 Among them, because the number of ONUs connected to the PON network is more than one, and with the expansion of the OPN network capacity, the number of connected ONU devices will greatly increase, and the standby OLT is performing distance measurement of ONUs. When selecting, an ONU can be arbitrarily selected as the ranging ONU, and one of the connected ONUs can also be designated as the ranging ONU according to a preset rule. The embodiments of the present invention are not limited to specific methods and rules for selecting a ranging ONU.
 104: The standby OLT sends a Range Request message to the ranging ONU.
 105: After the ranging ONU receives the Range Request message, it returns a ranging response RangeResponse message to the standby OLT.
 Among them, since the ranging ONU is in the POPUP state before receiving the ranging request Range Request message sent by the standby OLT, after receiving the ranging request Range Request message, it switches from the POPUP state to the RANGING ranging state.
 106: After receiving the Range Response message returned by the ranging ONU, the standby OLT obtains the round trip delay Rtd value of the ranging ONU.
Wherein, the standby OLT obtains the round trip delay Rtd value of the ranging ONU according to the receiving of the ranging response Range Response message returned by the ranging ONU and sending the ranging request Range Request message to the ranging ONU.
 107: The standby OLT obtains the main and standby backbone optical fiber propagation according to the obtained Rtd value of the ranging ONU and the round-trip delay Rtd value of the primary OLT of the ranging ONU (that is, the Rtd (primary) value of the ranging ONU device) Delay difference Δ.
 Among them, the round-trip delay Rtd value of the primary OLT of the ranging ONU is specifically sent to the backup OLT through the communication link in step 101, or deployed on the backup OLT during OPN network deployment Set.
 For ease of presentation, correspondingly, the Rtd value of the ranging ONU obtained by the standby OLT is expressed as Rtd (standby). As described in step 102, the Rtd value of the ONU device is specifically the processing delay value of the ONU and the branch fiber The propagation delay value, the propagation delay value of the backbone fiber, and the OLT processing delay value are composed of the Rtd on the main and backup OLT devices when the ONU is switched from the main OLT device to the backup OLT device caused by the failure of the backbone fiber. The ONU processing delay value, branch fiber propagation delay value, and OLT processing delay value in the value remain unchanged, and the only change is the backbone fiber propagation delay value caused by the difference in the length of the main and standby backbone fibers. changes happened. Therefore, the difference between the Rtd values of the ONU on the active and standby OLTs is specifically the difference Δ between the main and standby backbone fiber propagation delays, namely: Rtd (main)-Rtd (standby) = Δ.
 108: The standby OLT calculates and obtains the Rtd (standby) value of each ONU device according to the acquisition of the propagation delay difference Δ of the main and standby backbone optical fibers and the prestored Rtd (primary) value of each other ONU.
 Among them, the way to obtain the Rtd (primary) value of the other ONUs pre-stored on the standby OLT is the same as the way to acquire the Rtd (primary) value of the ranging ONU obtained in step 107, specifically: the primary OLT communicates The link is sent to the standby OLT, or, when the OPN network is deployed, the settings are deployed on the standby OLT.
 Since the difference between the lengths of the main and backup backbone fibers is fixed, all ONUs under the primary and backup PON LT share a backbone fiber at the same time. Therefore, the propagation delay value of all ONUs in the main and backup backbone fiber sections is limited. The difference Δ is also fixed, namely:
 Δ=Rtd (main) ONU1 -Rtd (standby) ONU1 = Rtd (main) ONU2 -Rtd (standby) ONU2 =......=Rtd (Main) ONUn -Rtd (standby) ONUn
 Therefore, if the standby OLT obtains the difference Δ between the main and standby backbone optical fiber propagation delays of an ONU, it can use the obtained difference Δ according to the saved Rtd (primary) values of other ONUs to determine the difference Δ for other ONUs. Rtd (main) is compensated, and the Rtd (standby) of other ONUs can be obtained accordingly. which is:
 Rtd (standby) ONUi = Rtd (main) ONUi -Δ.
 109: The standby OLT obtains the equalization delay time EqD (standby) of each ONU according to the acquired Rtd (standby) of each ONU.
 When obtaining the equalization delay time EqD (standby) of each ONU according to the obtained Rtd (standby) of each ONU, the specific reference formula is:
 EqD ONUi =Teqd(Preparation)-Rtd ONUi =Teqd-(Rtd(Main) ONUi -Δ), where Teqd (standby) is a constant value, and its value can be the same as or different from Teqd (main).
 110: The standby OLT issues the acquired EqD (standby) of each ONU through the Ranging Time PLOAM message.
 Among them, when the standby OLT device delivers the acquired EqD (backup) of each ONU through the Ranging Time PLOAM message, it can be delivered in the form of broadcast or unicast in the specific implementation. The embodiment of the invention does not limit the specific manner of sending the Ranging Time PLOAM message.
 After each ONU receives the Ranging Time PLOAM message sent from the standby OLT, it sets the delay time according to the EqD (standby) carried therein, and triggers the entry into their respective OPERATION state to resume the transmission of the interrupted service. So far, the standby OLT has completed the ranging of all ONUs, and realized the rapid switching of the main and standby backbone fibers.
 Further, in order to ensure the correctness of the transmission, the number of times the Ranging Time PLOAM message is issued by the standby OLT can also be set, such as 3 times as follows.
 In particular, for the ranging ONU, the standby OLT may also obtain the Rtd value of the ranging ONU's round-trip delay in step 106, and at the same time obtain the EqD value of the ranging ONU device according to the Rtd value, and then At any time after step 106, the standby OLT can send the EqD (standby) of the ranging ONU to the ranging ONU through the Ranging Time PLOAM message, see Figure 4 The embodiment of the present invention provides a schematic diagram of information exchange of a method for sending data. As shown in the figure, the information exchange process is as follows:
 1. When the main trunk fiber fails, perform the main-standby switching operation. After detecting the LOS alarm, the standby OLT switches to the main OLT; each ONU under the main OLT switches from the normal OPEARATION state to POPUP because of the detection of the LOS alarm. Status, service transmission between OLT and ONU is interrupted.
 2. The standby OLT selects an ONU to perform the ranging process. After the ranging is completed, the ranging ONU changes from the RANGING state to the OPERATION state, and the interrupted service of the ranging ONU resumes.
 3. The standby OLT obtains the propagation delay difference Δ of the main and standby backbone optical fibers according to the ranging processing of the ranging ONU. According to the obtained Δ value and the Rtd(n) value on the primary OLT, the EqD(n) value of the remaining ONUs on the standby OLT is calculated.
 4. The standby OLT sets a new EqD(n) to other ONUs, and accordingly, the ONU changes from the POPUP state to the OPERATION state, interrupting the service to resume.
 As shown in the above interaction Figure 4 As shown, the ONU can be set to be in the POPUP state, and if the Rangingrequest message of the OLT is received, the POPUP state is converted to the RANGING state, and the ranging process is started. Set the ONU in the POPUP state. If a Ranging time PLOAM message that the OLT sets the ONU EqD value is received, the ONU sets a new EqD value according to the message, that is, changes from the POPUP state to the normal OPERATION state and resumes the interrupted service transmission.
 In the above embodiment of the present invention, the number of ranging ONUs acquired by the standby OLT is taken as an example for description. In particular, in specific implementation, the PON network can determine what to do on the premise of meeting service delay requirements as needed. In order to find the number of ONUs, the ranging ONUs are processed in sequence, and then the average value of the difference Δ is obtained according to the obtained main and standby Rtd difference Δ of each ranging ONU, thereby ensuring the accuracy of the calculation.
 In the above embodiment of the present invention, the main-backup fiber failure triggers the main-backup switchover in the PON network as an example. Similarly, due to the main-backup switchover of the PON network triggered by the main OLT failure, the processing method is similar and will not be repeated anymore. Go into details.
 In summary, in the method for transmitting data on the optical network provided by the embodiment of the present invention, when the main and standby OLTs are switched due to the failure of the backbone fiber in the PON network, the standby OLT does not need to re-range all ONUs, only ranging The Rtd value of one of the ONUs, according to the Rtd value of the ONU on the main OLT, the difference Δ between the main and standby Rtd can be obtained. For other ONUs connected, it is no longer necessary to perform ranging processing. According to the obtained difference Δ and The Rtd values of other ONUs on the original active OLT can be calculated to calculate the EqD values of the standby OLTs corresponding to other ONUs. Since only one ranging process is required, the service transmission can be resumed, which greatly saves the need to perform measurement on all ONUs. The time it takes to meet the time delay requirements of PON network bearer services.