A multi-port optical line protection state monitoring method for 400G system

Abstract

The application discloses a kind of multiport optical line protection state monitoring method for 400G system, specifically relates to optical communication network fault monitoring technical field, the method is by obtaining port-sharing protection resource mapping and the FEC unit identification of working line and protection line, decoding correction position and superframe receiving time, pairing homologous FEC unit;Coding correction position is converted into media symbol coordinates and determines receiving time, eliminates the common disturbance of working line and protection line, forms candidate physical disturbance interval and is back to shared protection resource reference section;According to the time compatible overlap of multiport back interval and link survival condition, generate shared protection resource latent unusable pre-diagnosis result and update health status, to realize the pre-diagnosis and health management of shared protection resource.

Description

Technical Field

[0001] This invention relates to the field of optical communication network fault monitoring technology, and more specifically, to a method for monitoring the status of multi-port optical line protection in a 400G system. Background Technology

[0002] With the application of 400G coherent optical transmission, optical line protection typically relies on optical power, signal-to-noise ratio, light loss, and bit error statistics to determine line status. These indicators can identify fiber breaks and continuous degradation, but short-term disturbances corrected by FEC may be masked within the statistical period. 400ZR employs cascaded FEC, and interleaving processing further disperses continuous errors. When multiple ports of protection lines share optical switches, amplifiers, or optical cable segments, the propagation and processing delays differ at each port, making it difficult to directly correlate and attribute receiver-side anomalies to shared protection resources.

[0003] Existing literature (Research on Novel Super-Strong FEC Technology in Optical Communication Systems, 2022) studies concatenated FEC and interleaving techniques in high-speed optical communication, pointing out that interleaved concatenated codes can discretize erroneous symbols in the channel to improve the ability to correct burst and random errors. However, this literature focuses on coding structure, redundancy, and error correction performance, without studying how to use the error location information formed during decoding to identify short-term physical disturbances in the line; furthermore, after interleaving, codeword mapping, and framing, the decoding position order is not consistent with the actual transmission order on the media side, making it difficult to directly use as a time basis for judging the status of protected resources.

[0004] Existing patent application CN119895750A proposes calculating the symbol error distribution in FEC frames and comparing it with the expected distribution to detect burst errors; it can also perform partial distribution statistics for multiple ports and complete distribution calculation for specific ports that meet a threshold. However, this scheme forms a statistical distribution based on the number of errors contained in the FEC codeword, mainly used to adjust the front and back cursors or signal amplitude of the optical transceiver. It cannot determine the media transmission time corresponding to a specific error, nor can it rule out common anomalies in the working line and the protection line, or eliminate the delay differences between different ports to determine whether the anomaly comes from the same shared protection resource.

[0005] Therefore, there is an urgent need in this field for a monitoring method that can reliably identify short-term anomalies and determine the potential unavailability of multi-port shared protection resources when the protected line still maintains its link and the conventional performance indicators have not yet significantly exceeded the limits. Summary of the Invention

[0006] To overcome the aforementioned deficiencies in the prior art, this invention provides a method for monitoring the protection status of multi-port optical lines in a 400G system. By pairing co-source FEC units of the working and protection lines, the decoding correction position is converted into media symbol coordinates. Common disturbance components are eliminated based on co-source matching and common disturbance similarity conditions. Then, candidate physical disturbance intervals for each port are projected back onto the shared protection resource reference section. A latent unavailability pre-diagnosis is formed based on multi-port time compatibility overlap and link survival conditions, and the health status of the shared protection resource is updated. This achieves pre-diagnosis and health management of the shared protection resource, thereby solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for monitoring the status of multi-port optical line protection in a 400G system includes the following steps: Step 1: Obtain the port-shared protection resource mapping, and obtain the FEC unit identifier, decoding correction position set and superframe reception time of each port working line and protection line under a unified time reference. Pair the same source FEC units according to the identifier and the time delay difference of the two lines. Step 2: Based on the FEC framing, interleaving, codeword to modulation symbol mapping, DSP framing, and channel mapping relationships at the transmitting end, convert the decoding correction position into media symbol coordinates and determine the media symbol reception time; Step 3: Delete the media symbol coordinates in the protection line that are from the same source as the working line, and cluster the remaining coordinates of the protection line and the coordinates of the working line according to the media symbol reception time; when the clustering interval of the working line after the time delay difference correction of the two lines meets the preset common disturbance similarity condition, deduct the time overlap section of the two from the clustering interval of the protection line to obtain the candidate physical disturbance interval of the protection line. Step 4: For the same shared protection resource, subtract the total calibration delay from the reference cross section of the shared protection resource to the corresponding monitoring and receiving channel from the start and end times of the candidate physical disturbance intervals at each downstream port to obtain the resource-side return interval. Step 5: When there is time-compatible overlap in the resource-side return intervals of at least two downstream ports, and the protection lines participating in the time-compatible overlap meet the preset link survival conditions, generate a latent unavailability pre-diagnosis result for the shared protection resources, and update their health status to latent unavailability.

[0008] As a further embodiment of the present invention, the FEC unit identifier includes an extended superframe number, an FEC block number, and an intra-block unit number; the calibration delay difference between the two lines is the difference between the total calibration delay of the protection line and the total calibration delay of the working line; after subtracting the calibration delay difference between the two lines from the superframe reception time of the protection line, it is paired with an FEC unit in the working line that has the same FEC unit identifier and whose reception time difference is not greater than the pairing tolerance.

[0009] As a further aspect of the present invention, the media symbol coordinates include media symbol sequence number and normalized logical channel identifier; the transformation includes coordinate transformation according to the address relationship of outer FEC block mapping, transmitter interleaving, inner codeword to modulation symbol mapping, symbol interleaving, DSP framing and channel normalization.

[0010] As a further aspect of the present invention, the address relationships are pre-combined into corresponding coordinate mapping tables for each channel mapping mode; the coordinate mapping table is selected according to the current channel mapping mode, and the corresponding media symbol sequence number and normalized logical channel identifier are output using the FEC unit identifier and the correction position within the unit as indexes.

[0011] As a further aspect of the present invention, the same-source matching means that the coordinates of two media symbols belong to the paired same-source FEC units, have the same normalized logical channel identifier, and the difference in media symbol sequence number does not exceed a preset tolerance; the remaining media symbol coordinates of the protection line and the media symbol coordinates of the working line are counted according to a predetermined time box, and the time boxes that meet the counting conditions and whose adjacent intervals are not greater than the merging threshold are merged into the corresponding clustering interval.

[0012] As a further aspect of the present invention, the total calibration delay includes the optical transmission delay from the reference section to the monitoring and receiving channel and the fixed processing delay of the monitoring and receiving channel; the return time uncertainty is determined based on the time reference error, the media symbol timing quantization error and the total calibration delay error, and the resource-side return interval is expanded according to the return time uncertainty; when the intersection length of the expanded resource-side return intervals of at least two downstream ports is not less than the preset duration, it is determined that the resource-side return interval has the time-compatible overlap.

[0013] As a further aspect of the present invention, the preset link survival conditions include that the port-shared protection resource mapping has not changed during the monitoring period, the protection lines participating in the time-compatible overlap have no continuous light loss, and the average bit error rate before error correction during the monitoring period is lower than the preset link degradation threshold.

[0014] As a further aspect of the present invention, the common disturbance similarity conditions include that the overlap ratio of the same source FEC units involved in the working line clustering interval and the protection line clustering interval is not less than a preset overlap threshold, the similarity of the normalized logic channel distribution is not less than a preset channel similarity threshold, and the correlation degree of the time box error density profile is not less than a preset correlation threshold.

[0015] The technical effects and advantages of the multi-port optical line protection status monitoring method for 400G systems of the present invention are as follows: This invention, based on the relationships between FEC framing, interleaving, codeword-to-modulation symbol mapping, DSP framing, and channel mapping at the transmitting end, restores the decoding correction position to media symbol coordinates with media transmission time meaning, avoiding the impact of interleaving-induced decoding position dispersion on short-term disturbance identification. By deleting co-originating media symbol coordinates and subtracting overlapping segments in clustering intervals, it reduces misjudgments caused by shared disturbances on the transmitting side. Through resource-side re-implementation, it eliminates differences in optical transmission delay and fixed processing delay between different downstream ports, enabling candidate physical disturbances from multiple ports to be correlated on a unified time axis of the shared protection resource reference section. When the protected line still meets the preset link survival conditions, this invention can generate a latent unavailability pre-diagnosis result for the shared protection resource and update its health status, improving the timeliness and accuracy of shared protection resource pre-diagnosis and health management. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a multi-port optical line protection system and a status monitoring structure in an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram illustrating the process of decoding correction position conversion, determination of candidate physical disturbance intervals for protected lines, resource-side re-implementation, and time compatibility overlap judgment in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The 400G system referred to in this invention refers to a 400G coherent optical transmission system in which the relationships of FEC framing, interleaving, codeword-to-modulation symbol mapping, DSP framing, and channel mapping at the transmitting end can be determined, and the receiving end can output the decoding and correction position of each FEC unit and the corresponding superframe reception time.

[0020] Example 1

[0021] This embodiment provides a method for monitoring the status of multi-port optical line protection in a 400G system, which is applied to a 1+1 optical line protection system consisting of four 400G service ports.

[0022] like Figure 1 As shown, the four 400G service ports are denoted as port P1, port P2, port P3, and port P4, respectively. Each port's transmitting side divides its 400G transmit optical signal into a working optical signal and a protection optical signal. The working optical signal is transmitted along working lines W1 to W4, and the protection optical signal is transmitted along protection lines B1 to B4. Protection lines B1 to B4 share a common protection resource R, which includes a protection-side wavelength selective switch, a protection-side fiber amplifier, and a protection optical cable segment. The entry point of the common protection resource R serves as the reference cross-section R0.

[0023] The port-shared protection resource mapping records the port identifier, working line identifier, protection line identifier, shared protection resource identifier, reference cross-section identifier, optical switch cross-connection status, and mapping version. In this embodiment, ports P1 to P4 are all mapped to the shared protection resource R, and the mapping version is V17. During monitoring, when protection switching, protection line rerouting, wavelength selection switch reconfiguration, or manual fiber jumpering occurs, the port-shared protection resource mapping version is updated. Candidate physical disturbance intervals of protection lines formed under the old mapping version but not yet judged will no longer participate in subsequent time compatibility overlap judgments to ensure that protection lines participating in the same judgment actually pass through the same shared protection resource during the corresponding monitoring period.

[0024] Each port has a working line monitoring receiving channel and a protection line monitoring receiving channel set up before the service routing position. Both the working line monitoring receiving channel and the protection line monitoring receiving channel complete coherent reception, DSP superframe synchronization, and FEC decoding, and output the FEC unit identifier, decoding correction position set, superframe reception time, and current channel mapping mode to the monitoring FPGA. The continuous light loss state and the average bit error rate before error correction during the monitoring period are read through the module management interface or the diagnostic interface of the coherent receiving digital signal processor; the decoding correction position set for each FEC unit is obtained through the FEC decoder hardware interface or the internal diagnostic interface of the coherent receiving digital signal processor. C-CMIS can provide performance monitoring quantities such as bit error rate before error correction, eSNR, OSNR, and received optical power. The FEC unit position data required in this embodiment is output by the internal diagnostic interface.

[0025] All ports use the same common time base. The monitoring FPGA is configured with a global time counter, a superframe timestamp latch module, an FEC unit pairing module, a coordinate mapping table storage module, a source matching module, a timebox clustering module, an interval subtraction module, a resource-side feedback module, a time compatibility overlap module, and a health status management module. This embodiment uses a 312.5MHz common reference clock with a counting period of 3.2ns. The global time count uses the nearest clock edge correction, and the upper bound of the time base error is half a counting period, i.e., 1.6ns; the fine time within the superframe is determined based on the media symbol sequence number and the media symbol period.

[0026] This embodiment employs a 400ZR media-side cascaded FEC and DSP framing structure. The outer SC-FEC encoded frame, together with six 119-bit synchronization or padding units, forms 10976 119-bit units. These 119-bit units undergo depth 16 convolutional interleaving and are then encoded using a systematic dual-extended (128, 119) Hamming code. Each 128-bit Hamming codeword is mapped to 16 DP-16QAM symbols, followed by 8-way symbol interleaving. A DSP superframe comprises 181888 dual-polarization media symbol moments, each media symbol moment having four normalized logical channel components: XI, XQ, YI, and YQ; equivalently, each polarization includes 181888 media symbols. The nominal media symbol rate is 59.84375 GBaud per polarization, the media symbol period is approximately 16.710 ps, ​​and the DSP superframe period is approximately 3.039 μs. The aforementioned FEC framing, convolutional interleaving, Hamming coding, symbol interleaving, and DSP framing processes establish a definite but non-continuous address relationship between the decoding correction position and the actual media symbol transmission order.

[0027] The working line monitoring and receiving channels and the protection line monitoring and receiving channels use the same type of time-stamped cross-section. This time-stamped cross-section is located after the coherent receiving digital signal processor completes channel de-skewing and identifies the first media symbol of the DSP superframe, and before FEC deinterleaving and FEC decoding. When the first media symbol of the DSP superframe is identified, the global time counter is latched to obtain the superframe reception time. The optical transmission delay and fixed processing delay before the time-stamped cross-section are included in the corresponding calibration total delay, while the FEC deinterleaving, FEC decoding, and monitoring data upload delay after the time-stamped cross-section are not included in the calibration total delay.

[0028] The total calibration delay used in this embodiment is divided into two groups according to the processing purpose. The first group is used to pair FEC units of the same source, including the total calibration delay of the working line and the total calibration delay of the protection line. Both are based on the same transmission time before the optical splitting on the transmitting side and end at the time-marked section of the corresponding working line monitoring and receiving channel or the protection line monitoring and receiving channel. The calibration delay difference between the two lines is the difference between the total calibration delay of the protection line and the total calibration delay of the working line.

[0029] The second set is used for resource-side feedback, starting from the reference section R0 of the shared protection resource R and ending at the time-marked section of the corresponding protection line monitoring and receiving channel. It includes the optical transmission delay and fixed processing delay from the reference section R0 to the monitoring and receiving channel. The total delay of the two sets is calibrated and stored separately and is not interchangeable.

[0030] The FEC unit identifier includes the extended superframe number, the FEC block number, and the intra-block unit number. The FEC block number identifies the corresponding outer FEC block in the DSP superframe, and the intra-block unit number identifies the 119-bit unit within the corresponding outer FEC block. Synchronization or padding units use reserved FEC block numbers and intra-block unit numbers to maintain address continuity, but these do not serve as the source of outer FEC decoding correction locations. The monitoring log also associates an FEC level identifier to indicate whether the corresponding decoding correction location originates from outer FEC decoding or inner Hamming codeword decoding; the FEC level identifier is an auxiliary attribute of the monitoring log and does not change the definition of the FEC unit identifier consisting of the extended superframe number, the FEC block number, and the intra-block unit number.

[0031] Extended superframe numbers are uniformly numbered based on a common time reference. When establishing or re-establishing an extended superframe number epoch, the receiving time of the protected line superframe is first corrected according to the time delay difference between the two lines. Then, the corrected sequence of received times of the protected line superframe is matched with the sequence of received times of the working line superframe. The integer superframe number offset is determined based on the time order of consecutive superframes and the FEC block order. When a predetermined number of consecutive superframes satisfy the FEC block order consistency and the corrected receiving time difference is not greater than the pairing tolerance, the integer superframe number offset is locked, ensuring that the same transmitting DSP superframe has the same extended superframe number in both the working line monitoring and receiving channels and the protected line monitoring and receiving channels. If the receiving channel is reset, the DSP superframe is unlocked, the FEC block order changes, or the line time delay changes abruptly, the current pairing is paused and the extended superframe number epoch is re-established.

[0032] For successfully decoded inner Hamming codewords, the hard-decision codeword before decoding and the legal codeword after decoding are compared, and the different positions are recorded as a set of decoding correction positions. For outer FEC, the correction flag vector output by the decoder is read first; if the decoder does not directly output the correction flag vector, after the decoding verification passes and the decoding state converges, the block data before decoding and the block data after decoding are compared, and the difference positions are assigned to the corresponding extended superframe number, FEC block number, intra-block cell number, and intra-cell correction position. FEC cells that fail to decode or fail verification only record an uncorrectable flag, do not generate a precise set of decoding correction positions, and do not participate in media symbol coordinate transformation.

[0033] When pairing FEC units of the same origin, the overframe reception time of the protected line is subtracted from the calibration time delay difference between the two lines to correct the overframe reception time of the protected line to the reception time axis of the working line. If the corrected protected line FEC unit and the working line FEC unit have the same extended overframe number, FEC block number, and intra-block unit number, and the absolute value of their reception time difference is no greater than 6.4 ns, they are paired as FEC units of the same origin. Each FEC unit participates in pairing at most once; when multiple candidate FEC units appear, the one with the smallest reception time difference is selected, and the sequence of consecutively paired FEC units must remain monotonic.

[0034] After completing the pairing of homologous FEC units, according to Figure 2 The data processing relationship shown converts the decoding correction position into media symbol coordinates and determines the media symbol reception time.

[0035] For each channel mapping mode supported by the 400G system, a corresponding coordinate mapping table is pre-generated. When generating the coordinate mapping table, a unique label is assigned to each valid position in the outer FEC block, and the corresponding FEC block number, intra-block cell number, and intra-cell position are determined according to the framing relationship of the outer FEC. Then, the unique label is replayed according to the 16-branch read / write timing specified by the transmitting end convolutional interleaver to determine the corresponding inner Hamming codeword address. Then, the inner codeword to DP-16QAM symbol mapping, 8-channel symbol interleaving address conversion, and DSP framing address conversion are performed sequentially to obtain the media symbol sequence number of the corresponding position in the DSP superframe.

[0036] A 128-bit Hamming codeword corresponds to 16 DP-16QAM symbols. Each position within the codeword is mapped to the XI, XQ, YI, and YQ logical channels according to a defined relationship. The DSP superframe position type table distinguishes between data or FEC symbols, frame alignment symbols, training symbols, pilot symbols, and reserved symbols. The coherent receiver digital signal processor identifies the current channel mapping mode based on the DSP superframe alignment status, monitors the FPGA to select the corresponding channel normalization table, and uniformly converts the received channels after polarization swapping and in-phase / quadrature component swapping into normalized logical channel identifiers.

[0037] The coordinate mapping table is formed by combining the outer FEC block address, the transmitter interleaving address, the inner codeword address, the symbol interleaving address, the DSP framing address, and the channel normalization address. The coordinate mapping table is indexed by the FEC unit identifier and the correction position within the unit; based on the FEC level identifier associated with the monitoring record, the corresponding outer FEC block mapping entry or inner codeword mapping entry is selected, and the media symbol sequence number and normalized logical channel identifier are output.

[0038] The internal mapping record also retains the bit sequence number within the logic channel or the bit position within the original codeword, used for forward and reverse consistency checks on all valid addresses. During the check, each valid FEC address is forward-converted into the internal mapping record, and then the original FEC address is restored based on the internal mapping record; after all valid addresses are restored to consistency, the coordinate mapping table is loaded into the monitoring FPGA. The bit sequence number within the logic channel is only used for internal verification and is not part of the media symbol coordinates.

[0039] After coordinate transformation is completed at each decoding correction position, a media symbol coordinate instance is first formed. The media symbol coordinate instance includes the media symbol sequence number and the normalized logical channel identifier, and is associated with the corresponding extended superframe number, FEC cell identifier, intra-cell correction position, and media symbol reception time. The media symbol reception time is determined by adding the intra-superframe time offset corresponding to the media symbol sequence number and the monitoring reception channel phase correction value to the superframe reception time. The upper bound of the media symbol time quantization error is taken as one media symbol period, approximately 0.017 ns.

[0040] After obtaining the media symbol coordinate instances of the working line and the protection line, same-source matching is performed within each pair of same-source FEC units. If the media symbol coordinate instances of the working line and the protection line have the same normalized logical channel identifier and the difference in media symbol sequence number does not exceed the preset tolerance, they are identified as same-source matching candidates.

[0041] When the DSP superframe boundary and channel deskew state are stable, the preset tolerance is zero; under confirmed superframe boundary quantization or channel deskew quantization conditions, the preset tolerance is one media symbol. In this embodiment, the preset tolerance is configured as one media symbol during operation. When there are one-to-many or many-to-one candidates, matching is performed one by one according to the media symbol sequence difference from smallest to largest, and each media symbol coordinate instance participates in matching at most once.

[0042] After source matching is completed, media symbol coordinate instances that have completed source matching are deleted from the protected lines. Then, the remaining instances in the protected lines with the same media symbol sequence number and normalized logical channel identifier are merged into a single media symbol coordinate record. The number of merged instances is used as the error support count, thus obtaining the remaining media symbol coordinates of the protected lines. Media symbol coordinate instances in the working lines are merged in the same way to form working line media symbol coordinate records for subsequent clustering.

[0043] The coordinates of the remaining media symbols on the protected line and the coordinates of the media symbols on the working line are counted according to 1ns timeboxes. After each port has been operating normally for 30 minutes, a normal baseline is established through an online histogram, and the counting conditions for the number of timebox error supports are determined based on the normal baseline. In this embodiment, the counting conditions for ports P1 to P4 are 12, 13, 12, and 14, respectively. The timebox also needs to involve at least three different inner Hamming codewords. Timeboxes that meet the counting conditions and whose adjacent interval is no greater than 2ns are merged into the corresponding cluster intervals, and cluster intervals with a duration of less than 8ns are deleted.

[0044] The working line and the protection line use the same timebox and clustering rules. When comparing cluster intervals, the start and end times of the working line cluster interval are respectively added to the corresponding time delay difference between the two lines, so that the working line cluster interval is corrected to the protection line receiving time axis. This correction direction is opposite to the direction of correcting the protection line receiving time to the working line receiving time axis when pairing with the same source FEC unit, but the same time delay difference between the two lines is used.

[0045] When the overlap ratio of the same source FEC units involved in the corrected working line cluster interval and the protection line cluster interval is not less than 0.6, the normalized logic channel distribution similarity is not less than 0.8, and the correlation of the time box error density profile is not less than 0.75, the time overlap of the two cluster intervals is determined as a common segment, and this common segment is deducted from the protection line cluster interval. This interval-level deduction is used to eliminate common disturbance components remaining due to media symbol sequence tolerance, time quantization error, or failure of some decoding correction positions to be completely matched at the coordinate level. After deduction, each continuous sub-interval is re-performed with minimum duration judgment, and continuous sub-intervals with a duration of 8ns are selected as candidate physical disturbance intervals for the protection line.

[0046] After obtaining the candidate physical disturbance range for the protected line, resource-side reconnection is performed for the shared protection resource R. The total calibration delay used for resource-side reconnection starts from the reference section R0 of the shared protection resource R and ends at the time-marked section of the monitoring and receiving channel of each port protection line, including the optical transmission delay from the reference section R0 to the corresponding monitoring and receiving channel and the fixed processing delay before the time-marked section.

[0047] In this embodiment, the uncertainty of the re-entry time is determined according to the conservative upper bound of the error. The absolute upper bound of the time base error, the media symbol timing quantization error, and the total calibration delay error used for resource-side re-entry is added together, and the result is used as the re-entry time uncertainty of the corresponding port. After calibration is completed in this embodiment, the calibration data of the monitoring and receiving channels of the protection line at each port are shown in Table 1.

[0048] Table 1. Total calibration delay and return-to-base time uncertainty of each port protection line monitoring and receiving channel in this embodiment.

[0049] As shown in Table 1, the total calibration delay of ports P1 and P4 differs by 45.765 μs, which is much greater than the duration of a nanosecond-level disturbance. Therefore, the abnormal moments monitored at the receiving side of each port cannot be directly compared. The uncertainty of the return time for each port is less than 4.1 ns, which is significantly less than the 50 ns disturbance duration set in this embodiment. After expanding the uncertainty of the return time, multiple ports can still form a common intersection of not less than 12 ns, which can balance error tolerance and time resolution capability for nanosecond-level events.

[0050] The resource-side re-intervention interval is obtained by subtracting the corresponding total calibration delay used for resource-side re-intervention from the start and end times of the candidate physical disturbance intervals for each downstream port protection line. The resource-side re-intervention intervals are then extended forward and backward according to the corresponding re-intervention time uncertainty. When the intersection length of the extended resource-side re-intervention intervals of at least two downstream ports is not less than 12 ns, the corresponding resource-side re-intervention intervals are determined to have time-compatible overlap. The preferred four-port operating condition of this embodiment requires at least three ports to participate in time-compatible overlap.

[0051] Using the time axis of the reference section R0 as the resource time axis, this embodiment sets a short-term disturbance lasting 50 ns at 1000.000000μs on the resource time axis. The candidate physical disturbance range and resource-side return range of the protection line obtained by the above processing for each port are shown in Table 2.

[0052] Table 2. Resource-side re-implementation results for short-term disturbances to shared protected resources in this embodiment.

[0053] As shown in Table 2, the candidate physical disturbance intervals of the protected lines observed at the monitoring receiving side of the four ports differ by tens of microseconds. After subtracting the total calibration delay used for resource-side re-intervention, the four resource-side re-intervention intervals converge to the same time range of the shared protection resource R. The common time length of the four unextended resource-side re-intervention intervals is 47 ns, accounting for 94% of the input disturbance duration, and the range of the re-intervention interval centers is 3.0 ns, indicating that resource-side re-intervention can eliminate the differences in optical transmission delay and fixed processing delay between different ports.

[0054] During the monitoring period, the port-shared protection resource mapping remained at V17. No continuous light loss occurred on any of the protection lines participating in time-compatible overlap, and the confirmation time for continuous light loss was 10ms. The average pre-correction bit error rate for ports P1 to P4 within a 1s monitoring period was 7.8 × 10⁻⁶. ³、8.2×10 ³、7.7×10 ³ and 8.4×10 ³, all below 1.10×10 The preset link degradation threshold is set at ². Therefore, all protection lines participating in time-compatible overlap meet the preset link survival conditions.

[0055] Under normal conditions of common time reference, superframe timestamp, coherent receiving digital signal processor, and monitoring buffer status, the resource-side feedback intervals of at least three downstream ports have time-compatible overlap. Furthermore, the protection lines participating in this time-compatible overlap meet the preset link survival conditions: the port-shared protection resource mapping has not changed during the monitoring period, there is no continuous light loss, and the average bit error rate before error correction during the monitoring period is lower than a preset link degradation threshold. Based on this, the monitoring FPGA generates a latent unavailability pre-diagnosis result for the shared protection resource R and updates the health status of the shared protection resource R to latent unavailability, thereby achieving pre-diagnosis and health management of the shared protection resource R.

[0056] To verify the effect of media symbol coordinate transformation, this embodiment sets up a control process without media symbol coordinate transformation and a process in this embodiment with media symbol coordinate transformation. The control process constructs an equivalent time axis for the decoding domain according to the FEC cell order, correction positions within the cells, and corresponding codeword output periods of the FEC decoder, and statistically analyzes the position clusters formed by the decoding correction positions on this equivalent time axis. The process in this embodiment converts the decoding correction positions into media symbol coordinates according to a coordinate mapping table and constructs a physical time axis based on the media symbol reception time. The equivalent time axis for the decoding domain is only used to compare the dispersion of decoding correction positions and is not used as the timing basis for resource-side re-projection.

[0057] This embodiment inputs a continuous media disturbance lasting 40 ns, and an input consisting of two media disturbances lasting 40 ns each, with a start time 120 ns apart. The processing results are shown in Table 3.

[0058] Table 3. Results of perturbation time structure recovery before and after media symbol coordinate transformation in this embodiment.

[0059] As shown in Table 3, convolutional interleaving and symbol interleaving alter the arrangement order of continuous media symbols in the FEC decoding coordinates. Directly processing according to the decoding correction position cannot form a stable physical time interval. After completing the media symbol coordinate transformation according to the transmitting end's FEC framing, interleaving, codeword-to-modulation symbol mapping, DSP framing, and channel mapping relationships, the dispersed FEC decoding positions can be restored to the media time interval corresponding to the input perturbation. The media symbol coordinate transformation thus constitutes the preprocessing for multi-port resource-side re-projection and time compatibility overlap judgment.

[0060] This embodiment also sets up separate verification methods for common disturbances on the transmitting side, disturbances in single-port protection branches, and disturbances in shared protection resources. When a common disturbance occurs before the optical splitter on the transmitting side, the coordinate instances of media symbols of the same source in the working line and the protection line are deleted from the protection line after being matched for the same source; common components that are not completely deleted at the coordinate level are further eliminated by subtracting overlapping segments in the clustering interval. When a disturbance occurs in the exclusive protection branch of port P1, only port P1 forms a resource-side re-feedback interval, which does not meet the time compatibility overlap condition of at least two downstream ports. When a disturbance occurs in the shared protection resource R, multiple downstream ports form candidate physical disturbance intervals for the protection line, and after performing resource-side re-feedback, they are concentrated into the same resource time range.

[0061] Therefore, the FEC unit identifier, the set of decoding correction positions, and the superframe reception time constitute the monitoring input; media symbol coordinate transformation restores the physical time relationship corresponding to the decoding correction positions; deletion of co-source media symbol coordinates and subtraction of overlapping segments in clustering intervals eliminate common disturbance components in the working line and the protection line; resource-side back-end eliminates the differences in optical transmission delay and fixed processing delay between each downstream port; multi-port time compatibility overlap and preset link survival conditions together form the latent unavailability pre-diagnosis result of shared protection resources, and the pre-diagnosis and health management of shared protection resources are realized through health status updates.

[0062] This embodiment adopts a 400ZR cascaded FEC structure. For 400G systems using other FEC structures or multi-physical channel structures, the coordinate mapping table is changed according to the corresponding FEC framing, interleaving, codeword to modulation symbol mapping, DSP framing, and channel mapping relationships; the processes of pairing of FEC units from the same source, deleting coordinates of media symbols from the same source, forming cluster intervals, deducting overlapping segments, resource-side re-projection, time-compatible overlap, and health status update remain consistent.

[0063] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0064] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for monitoring the protection status of multi-port optical lines in a 400G system, characterized in that, Includes the following steps: Step 1: Obtain the port-shared protection resource mapping, and obtain the FEC unit identifier, decoding correction position set and superframe reception time of each port working line and protection line under a unified time reference. Pair the same source FEC units according to the identifier and the time delay difference of the two lines. Step 2: Based on the FEC framing, interleaving, codeword to modulation symbol mapping, DSP framing, and channel mapping relationships at the transmitting end, convert the decoding correction position into media symbol coordinates and determine the media symbol reception time; Step 3: Delete the media symbol coordinates in the protection line that are from the same source as the working line, and cluster the remaining coordinates of the protection line and the coordinates of the working line according to the media symbol reception time; when the clustering interval of the working line after the time delay difference correction of the two lines meets the preset common disturbance similarity condition, deduct the time overlap section of the two from the clustering interval of the protection line to obtain the candidate physical disturbance interval of the protection line. Step 4: For the same shared protection resource, subtract the total calibration delay from the reference cross section of the shared protection resource to the corresponding monitoring and receiving channel from the start and end times of the candidate physical disturbance intervals at each downstream port to obtain the resource-side return interval. Step 5: When there is time-compatible overlap in the resource-side return intervals of at least two downstream ports, and the protection lines participating in the time-compatible overlap meet the preset link survival conditions, generate a latent unavailability pre-diagnosis result for the shared protection resources, and update their health status to latent unavailability.

2. The method for monitoring the status of multi-port optical line protection in a 400G system according to claim 1, characterized in that, The FEC unit identifier includes the extended superframe number, the FEC block number, and the intra-block unit number; the calibration delay difference between the two lines is the difference between the total calibration delay of the protection line and the total calibration delay of the working line; After subtracting the time delay difference between the two lines from the overframe reception time of the protection line, pair it with an FEC unit in the working line that has the same FEC unit identifier and whose reception time difference is not greater than the pairing tolerance.

3. The method for monitoring the protection status of a multi-port optical line in a 400G system according to claim 1, characterized in that, The media symbol coordinates include the media symbol sequence number and the normalized logical channel identifier; the transformation includes coordinate transformation according to the address relationships of outer FEC block mapping, transmitter interleaving, inner codeword to modulation symbol mapping, symbol interleaving, DSP framing and channel normalization.

4. The method for monitoring the status of multi-port optical line protection in a 400G system according to claim 3, characterized in that, For each channel mapping mode, the address relationships are pre-combined into corresponding coordinate mapping tables; the coordinate mapping table is selected according to the current channel mapping mode, and the corresponding media symbol sequence number and normalized logical channel identifier are output using the FEC unit identifier and the correction position within the unit as indexes.

5. The method for monitoring the status of multi-port optical line protection in a 400G system according to claim 1, characterized in that, The homogeneous matching is defined as two media symbol coordinates belonging to paired homogeneous FEC units, having the same normalized logical channel identifier, and the difference in media symbol sequence number not exceeding a preset tolerance; the remaining media symbol coordinates of the protected line and the media symbol coordinates of the working line are counted according to a predetermined time box, and the time boxes that meet the counting conditions and whose adjacent intervals are not greater than the merging threshold are merged into the corresponding cluster intervals.

6. The method for monitoring the protection status of a multi-port optical line in a 400G system according to claim 1, characterized in that, The total calibration delay includes the optical transmission delay from the reference section to the monitoring and receiving channel and the fixed processing delay of the monitoring and receiving channel; the return time uncertainty is determined based on the time reference error, the media symbol timing quantization error and the total calibration delay error, and the resource-side return interval is expanded according to the return time uncertainty; when the intersection length of the expanded resource-side return intervals of at least two downstream ports is not less than the preset duration, it is determined that the resource-side return interval has the time-compatible overlap.

7. The method for monitoring the status of multi-port optical line protection in a 400G system according to claim 1, characterized in that, The preset link survival conditions include that the port-shared protection resource mapping has not changed during the monitoring period, the protection lines participating in the time-compatible overlap have no continuous light loss, and the average bit error rate before error correction during the monitoring period is lower than the preset link degradation threshold.

8. The method for monitoring the status of multi-port optical line protection in a 400G system according to claim 1, characterized in that, The common disturbance similarity conditions include that the overlap ratio of the same source FEC units involved in the working line cluster interval and the protection line cluster interval is not less than a preset overlap threshold, the similarity of the normalized logic channel distribution is not less than a preset channel similarity threshold, and the correlation of the time box error density profile is not less than a preset correlation threshold.

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