JP4910624B2 - SDH transmission apparatus and path monitoring method thereof - Google Patents

Description

  The present invention relates to an SDH (Synchronous Digital Hierarchy) transmission apparatus and a path monitoring method thereof, and more particularly, to a path connection state monitoring technique.

  ITU-T Recommendation G. 707 and the like define a network node interface (NNI) of synchronous digital hierarchy (SDH). The STM (Synchronous Transfer Module) frame specified here is a section overhead (SOH: Section Overhead) which is a management information byte between a transmission terminal station and a relay terminal station, and an STM frame of each VC (Virtual Container). It consists of a pointer (PTR) that points to the head position and a payload that stores a plurality of VCs. Each VC includes a path overhead (POH: Path Overhead) composed of management information bytes such as J1 and B3. In the synchronous network, the J0, J1, and J2 bytes multiplexed in the section overhead (SOH) and path overhead (POH) of the STM-N frame are used as path trace bytes for the purpose of monitoring the path connection status. Yes.

  By the way, the SDH transmission system using such an STM frame is configured with redundancy (active system and standby system), and route switching control is performed to switch to the standby system when a failure occurs in the active system. ing. For example, in Patent Document 1, in order to monitor the connection state of a VC-3 (third-order group virtual container) path in a synchronous network (SDH) having a redundant configuration, a path trace pattern is inserted into the J1 byte and transmitted. A method is disclosed in which a connection state between a station and a receiving station is monitored to automatically control the upstream and downstream paths of the VC-3 path to be in-system selection.

  Further, as related technology, Patent Document 2 discloses an auxiliary signal transmission system having a redundant configuration capable of correctly transmitting an auxiliary signal even if a line failure occurs in an intermediate section. Further, Patent Document 3 relates to a path switch ring control device in a synchronous network (SDH), and in particular, a path for relieving a failure occurring in the latter when an asynchronous (PDH) subnetwork is included in the synchronous network (SDH). -A switch ring control device is described.

JP-A-8-204670 JP-A-8-331089 Japanese Patent Laid-Open No. 10-23053

  In a conventional synchronous communication system, path misconnection monitoring is performed using path trace bytes (J0, J1, J2) multiplexed as overhead data of an STM-N frame. However, when a failure occurs in the upstream (upstream) device or line, an AIS (Alarm Indication Signal) indicating that the upper section or path section is in an abnormal state is transferred to the downstream (downstream) device. ITU-T G. When the AIS defined in 707 is received, there is a possibility that path monitoring using the path trace byte cannot be performed.

  That is, ITU-T G.I. In 707, MS-AIS (Multiplex Section-AIS), MSF-AIS (Multiplex Section FEC Alarm Indication Signal), AU-AIS (Administrative Unit-AIS), and TU-AIS (TriVIS) (Virtual Container-AIS) is defined. For example, in MS-AIS, all STM-N frames other than RSOH (Regenerator Section Overhead) are masked with “1”. In AU-AIS, AU-n frames including AU pointers are masked. All are defined to be masked with “1”. For this reason, when a line failure or a device failure occurs, and the AIS is transferred to notify the subsequent device of the failure, for example, in VC-AIS, the entire VC frame including the VC pointer is masked with “1”. It has become. Therefore, when the AIS is transferred downstream in the synchronous network (SDH), the method using the path trace byte (J0, J1, J2) multiplexed as the overhead data of the STM-N frame detects the line misconnection. Could not be done and could forward the AIS to the wrong path.

  Accordingly, an object of the present invention is to enable monitoring of a path connection state when an AIS is transferred.

  An SDH transmission apparatus according to one aspect of the present invention includes a first overhead extraction circuit that extracts overhead information in a main signal transmitted from a preceding apparatus, and first path setting information included in the overhead information or the preceding stage. A path monitoring circuit that performs path connection monitoring using the second path setting information transmitted from the first apparatus using the first auxiliary signal, and when transferring an alarm display signal to the latter apparatus, And an auxiliary signal switching circuit that transfers the first or second path setting information using the second auxiliary signal to the apparatus.

  In the SDH transmission apparatus according to the first development mode, the path monitoring circuit includes a path determination circuit that compares the first or second path setting information with the third path setting information stored in advance, and includes a main signal in the main signal. May further include a cross-connect processing circuit that performs cross-connect processing in units of predetermined frames included in the data based on the determination result of the path determination circuit.

  In the SDH transmission apparatus of the second development form, the overhead information may include a path information transfer bit indicating whether or not the first or second path setting information is transferred using the first auxiliary signal.

  In the SDH transmission apparatus according to the third development form, a second overhead extraction circuit that extracts path trace information inserted in overhead in a predetermined frame in the output signal of the cross-connect processing circuit and outputs the extracted information to the path monitoring circuit. In addition, the path monitoring circuit may monitor the path trace information based on information on the input and output of the cross-connect processing circuit.

  In the SDH transmission apparatus of the fourth development form, either the main signal or the first or second auxiliary signal may be transmitted through a wireless line.

  The SDH transmission apparatus according to the fifth development mode includes a transmission unit and a reception unit, and each of the transmission unit and the reception unit includes a first overhead extraction circuit, a path monitoring circuit, and an auxiliary signal switching circuit. Good.

  In the SDH transmission apparatus according to the sixth development form, each of the transmission unit and the reception unit may further include a cross-connect processing circuit.

  In the SDH transmission device according to the seventh development form, each of the transmission unit and the reception unit may further include a second overhead extraction circuit.

  A path monitoring method for an SDH transmission apparatus according to an aspect of the present invention includes a step of extracting overhead information in a main signal transmitted from a preceding apparatus, and first path setting information included in the overhead information or the preceding path setting information. When the path connection monitoring is performed using the second path setting information transmitted from the device using the first auxiliary signal, and when the alarm display signal is transferred to the subsequent device, the device is connected to the subsequent device. Transferring path setting information using a second auxiliary signal.

  In the path monitoring method for the SDH transmission apparatus according to the second development mode, the step of comparing the first or second path setting information with the third path setting information stored in advance, and the main signal based on the comparison determination result And a step of performing a cross-connect process in a predetermined frame unit included therein.

  In a path monitoring method for an SDH transmission apparatus according to a third development mode, the method includes a step of extracting and outputting path trace information inserted in overhead in a predetermined frame in an output signal obtained by cross-connect processing, In the connection monitoring step, the path trace information may be monitored based on information before and after the cross-connect process.

  In the path monitoring method for the SDH transmission apparatus according to the fourth embodiment, in the step of monitoring the connection of the path, a step of detecting whether or not an alarm display signal from the preceding apparatus is transmitted, and an alarm display signal is transmitted And detecting whether the path information transfer bit indicates that the first or second path setting information is transferred, and transferring the first or second path setting information. And the step of extracting the first or second path setting information transferred using the first auxiliary signal may be included.

  According to the present invention, when the AIS is transferred to the subsequent apparatus, the path setting information is transferred using the auxiliary signal. Therefore, the overhead masked by the AIS process can be received by the subsequent apparatus. Therefore, the downstream apparatus can monitor the path connection when the AIS is transferred.

  Further, according to the present invention, since path control information is monitored before and after the cross-connect circuit, it is possible to detect a setting error or occurrence of a failure in the cross-connect circuit.

  The SDH transmission apparatus according to the embodiment of the present invention is applied to a synchronous network configured by a synchronous communication system having a cross-connect function at the AU-n / TU-n / VC-n level. The SDH transmission apparatus performs overhead processing on the main signal (STM-N signal) input from the preceding apparatus, and path setting information inserted in the overhead in the main signal and the path setting of the apparatus stored in advance. A path misconnection is detected by comparing and determining information. Further, when a failure or the like occurs in the preceding apparatus and an AIS is received along with the failure or the like, the path setting data is transferred using the band of the auxiliary signal. That is, when the AIS is transferred to a subsequent apparatus due to a line failure or the like, the path setting data corresponding to the path trace byte (J0, J1, J2) multiplexed as the overhead data of the STM-N frame is used as the bandwidth of the auxiliary signal. Is used to transmit to the subsequent device. By performing such transmission, the downstream apparatus extracts path setting data from the auxiliary signal band and receives path setting data corresponding to the path trace byte inserted in the overhead of the STM-N frame. be able to. Therefore, it is possible to monitor path misconnection during AIS transfer. Hereinafter, it will be described in detail with reference to the drawings in accordance with embodiments.

  FIG. 1 is a block diagram showing a configuration of an SDH transmission apparatus according to the first embodiment of the present invention. In FIG. 1, the SDH transmission apparatus includes a transmission unit 100 and a reception unit 200. First, the configuration of the transmission unit 100 will be described. The transmission unit 100 includes a clock extraction circuit 1, an overhead extraction circuit 2, a path monitoring circuit 3, a cross-connect processing circuit 4, an overhead insertion circuit 5, an auxiliary signal switching circuit 6, and a wireless transmission circuit 7.

  The clock extraction circuit 1 extracts a clock signal from the transmission STM-N signal 1a, and outputs it to the overhead extraction circuit 2 as a clock signal 1b.

  The overhead extraction circuit 2 extracts the overhead data in the STM-N frame from the transmission STM-N signal 1a using the clock signal 1b input from the clock extraction circuit 1, and passes the transmission STM-N overhead data 1c. Output to the monitoring circuit 3, perform demapping processing to a VC-4 frame, and output a transmission VC-4 signal 1 d to the cross-connect processing circuit 4. That is, the overhead extraction circuit 2 extracts the path trace byte (J0, J1, J2) and the path information transfer bit inserted in the STM-N frame. The path information transfer bit indicates that the path setting information is multiplexed in the band of the auxiliary signal when the AIS is transferred from the upstream apparatus to the downstream apparatus, and the RSOH empty bit of the STM-N frame. Is multiplexed. Since the path information transfer bit inserted here only indicates whether or not the path setting information is multiplexed in the band of the auxiliary signal, it is only necessary to secure a 1-bit multiplexing area in the vacant bits of RSOH. For example, when the auxiliary signal band is used, “1” is inserted into the transmission unit path information transfer bit 1f, and when the auxiliary signal band is not used, “0” may be multiplexed. Note that a receiver path information transfer bit 2i and an extracted path information transfer bit 3a described later also have contents corresponding to the transmitter path information transfer bit 1f.

  The path monitoring circuit 3 detects AIS and extracts path trace bytes from the transmission STM-N overhead data 1c. In addition, a path misconnection determination is performed from the transmission STM-N overhead data 1c or the transmission auxiliary signal 1g. Then, the transmission unit path setting data 1e is output to the cross-connect processing circuit 4, the overhead insertion circuit 5, and the auxiliary signal switching circuit 6, and the transmission unit path information transfer bit 1f is output to the overhead insertion circuit 5 and the auxiliary signal switching circuit 6. To do. Details of the path monitoring circuit 3 will be described later.

  The cross-connect processing circuit 4 performs cross-connect processing for each VC-4 frame on the transmission VC-4 signal 1d according to the transmission unit path setting data 1e, and outputs a transmission VC-4 (XC) signal 1h.

  The overhead insertion circuit 5 performs the mapping process to the STM-N frame for the transmission VC-4 (XC) signal 1h, and transmits the transmission unit path setting data 1e and the transmission unit path information transfer bit 1f to the STM-N frame. The transmission STM-N data signal 1 i is generated and output to the wireless transmission circuit 7. More specifically, the overhead insertion circuit 5 inserts the transmission unit path information transfer bit 1f into the RSOH empty bit in the STM-N frame, and transmits the transmission unit path setting data 1e to the path trace byte (J0) of the STM-N frame. , J1, J2).

  The auxiliary signal switching circuit 6 selects the transmission unit path setting data 1e and the transmission auxiliary signal 1g by the transmission unit path information transfer bit 1f and outputs the transmission auxiliary data signal 1j to the wireless transmission circuit 7. In this case, the auxiliary signal switching circuit 6 multiplexes the transmission unit path setting data 1e in the band of the auxiliary signal.

  The radio transmission circuit 7 multiplexes the transmission STM-N data signal 1i and the transmission auxiliary data signal 1j into a radio frame, and transmits the radio frame as a radio transmission signal 1k to a subsequent apparatus via a radio transmission path.

  Next, the receiving unit 200 will be described. The reception unit 200 includes a wireless reception circuit 11, a reception data extraction circuit 12, a frame synchronization circuit 13, an overhead extraction circuit 14, a path monitoring circuit 15, a cross-connect processing circuit 16, an overhead insertion circuit 17, and an auxiliary signal switching circuit 18.

  The wireless reception circuit 11 receives the wireless reception signal 2a from the preceding apparatus via the wireless transmission path, and outputs it to the reception data extraction circuit 12 and the frame synchronization circuit 13 as a wireless frame reception data signal 2b.

  The frame synchronization circuit 13 performs frame synchronization processing on the radio frame reception data signal 2 b and outputs a reception data extraction timing signal 2 c to the reception data extraction circuit 12.

  The reception data extraction circuit 12 extracts the STM-N data signal from the radio frame reception data signal 2b using the reception data extraction timing signal 2c, and outputs the reception STM-N data signal 2d to the overhead extraction circuit 14 as a main signal. Then, the reception auxiliary data signal 2 e is output as an auxiliary signal to the path monitoring circuit 15 and the auxiliary signal switching circuit 18.

  The overhead extraction circuit 14 extracts the overhead data in the STM-N frame from the received STM-N data signal 2d, outputs the received STM-N overhead data 2f to the path monitoring circuit 15, and outputs it to the VC-4 frame. Demapping processing is performed, and the received VC-4 signal 2 g is output to the cross-connect processing circuit 16. Overhead data extracted by the overhead extraction circuit 14 is a path trace byte (J0, J1, J2) and a path information transfer bit inserted in the STM-N frame, as in the overhead extraction circuit 2.

  The path monitoring circuit 15 performs path misconnection determination based on the received STM-N overhead data 2f or the received auxiliary data signal 2e, and receives the path setting data 2h of the receiving unit as a cross-connect processing circuit 16, an overhead insertion circuit 17, and an auxiliary signal switch. The signal is output to the circuit 18, and the reception unit path information transfer bit 2 i is output to the overhead insertion circuit 17 and the auxiliary signal switching circuit 18. The configuration and operation of the path monitoring circuit 15 are the same as those of the path monitoring circuit 3, and will be described later in detail.

  The cross-connect processing circuit 16 performs a cross-connect process for each VC-4 frame on the received VC-4 signal 2g in accordance with the reception unit path setting data 2h, and converts the received VC-4 (XC) signal 2j into an overhead insertion circuit 17. Output to.

  The overhead insertion circuit 17 performs mapping processing on the received VC-4 (XC) signal 2j to the STM-N frame, and receives the reception unit path setting data 2h and the reception unit path information transfer bit 2i to the overhead of the STM-N frame. The received STM-N signal 2k is output to the outside of the apparatus. That is, similarly to the overhead insertion circuit 5, the overhead insertion circuit 17 inserts the reception unit path information transfer bit 2i into the RSOH empty bit in the STM-N frame and the reception unit path setting data 2h to the path of the STM-N frame. Insert into trace bytes (J0, J1, J2).

  The auxiliary signal switching circuit 18 selects the reception unit path setting data 2h and the reception auxiliary data signal 2e by the reception unit path information transfer bit 2i, and outputs it as the reception auxiliary signal 2m to the outside of the apparatus. At this time, the auxiliary signal switching circuit 18 multiplexes the reception unit path setting data 2h with the reception auxiliary signal 2m, similarly to the auxiliary signal switching circuit 6.

  Next, the path monitoring circuit 3 and the path monitoring circuit 15 will be described in detail. Since the path monitoring circuit 3 and the path monitoring circuit 15 have the same configuration, the path monitoring circuit 3 will be described as an example here. FIG. 2 is a block diagram showing the configuration of the path monitoring circuit 3 (15). In FIG. 2, the path monitoring circuit 3 includes an overhead processing circuit 21, a memory 22, and a path determination circuit 23.

  The overhead processing circuit 21 performs AIS detection and overhead data separation processing from transmission STM-N overhead data 1c (reception STM-N overhead data 2f), and extracts extracted path information transfer bit 3a, AIS activation alarm 3b, and path trace byte. 3c is taken out and output to the path determination circuit 23. The memory 22 outputs the device path setting information 3 d held in advance to the path determination circuit 23. The path determination circuit 23 determines whether the device path setting information 3d matches the path trace byte 3c or the transmission auxiliary signal 1g (reception auxiliary data signal 2e) based on the extracted path information transfer bit 3a and the AIS activation alarm 3b, and transmits The unit path setting data 1e (receiving unit path setting data 2h) and the transmitting unit path information transfer bit 1f (receiving unit path information transfer bit 2i) are output.

  Next, the operation of the path monitoring circuit 3 will be described with reference to FIGS. FIG. 3 is a flowchart showing the operation of the path monitoring circuit 3. In FIG. 3, when the AIS trigger alarm 3b is not detected in the overhead processing circuit 21 (No in step A1), that is, when data transmission is normally performed, the path trace byte 3c is extracted from the overhead of the STM-N frame. (Step A2), and a match determination with the apparatus path setting information 3d is performed (Step A3).

  On the other hand, when the AIS activation alarm 3b is detected in the overhead processing circuit 21 (Yes in step A1), the path information transfer bit, that is, the extracted path information transfer bit 3a is extracted from the STM-N frame (step A4). Subsequently, the extracted path information transfer bit 3a is detected (step A5). If the extracted path information transfer bit 3a is not detected (No in step A5), a transmission unit path information transfer bit 1f is generated (step A6), and the generated transmission unit path information transfer bit 1f is used as the overhead of the STM-N frame. (Step A7). The transmission unit path information transfer bit 1f inserted here indicates that the path setting information is transferred using the band of the auxiliary signal, and as described above, it is only necessary to secure a 1-bit multiplexing area in the vacant bits of the RSOH. For example, when the auxiliary signal band is used, “1” is set to the transmission unit path information transfer bit 1f, and when the auxiliary signal band is not used, “0” is set. Then, the device path setting information 3d is multiplexed as the transmitter path setting data 1e in the auxiliary signal band (step A8).

  If the transmission unit path information transfer bit 1f is detected (Yes in step A5), the transmission auxiliary signal 1g is extracted from the band of the auxiliary signal (step A9), and the apparatus path setting information 3d and the transmission auxiliary signal 1g are extracted. A match determination is performed (step A10). After the match determination, the process proceeds to step A6.

  According to the SDH transmission apparatus configured as described above, path misconnection monitoring based on path setting data transferred using the path trace byte or auxiliary signal bandwidth inserted in the overhead of the STM-N frame. Is possible. In this case, even when a failure occurs in an upstream device or the like and the AIS is received, the path setting data is transferred using the band of the auxiliary signal. Therefore, path setting data corresponding to the path trace byte inserted in the overhead of the STM-N frame can be received in the downstream apparatus, and path misconnection monitoring can be performed. That is, when transferring the AIS to the downstream device, the path setting information is transferred using the auxiliary signal band for the overhead that would otherwise be masked by the AIS process. Can be received.

  FIG. 4 is a block diagram showing the configuration of the SDH transmission apparatus according to the second embodiment of the present invention. In FIG. 4, the same reference numerals as those in FIG. In FIG. 4, in the transmission unit 100a, an overhead extraction circuit 8 is added to FIG. 1, and the path monitoring circuit 3 ′ has an input from the overhead extraction circuit 8 added to the path monitoring circuit 3 of FIG. Yes. Further, in the receiving unit 200a, an overhead extraction circuit 19 is added, and the path monitoring circuit 15 'has an input from the overhead extraction circuit 19 added to the path monitoring circuit 15 of FIG.

  The overhead extraction circuit 8 extracts the path trace byte inserted in the overhead of the VC-4 frame with respect to the transmission VC-4 (XC) signal 1h, and transmits the transmission (XC) path trace byte 1m to the path monitoring circuit 3. Output to '. The path monitoring circuit 3 ′ performs path misconnection monitoring before and after the cross-connect processing circuit 4 by performing a match determination between the transmission (XC) path trace byte 1m and the path setting information stored in the memory 22. .

  The overhead extraction circuit 19 extracts a path trace byte inserted in the overhead of the VC-4 frame from the received VC-4 (XC) signal 2j, and performs path monitoring on the received (XC) path trace byte 2n. Output to circuit 15 '. The path monitoring circuit 15 ′ performs erroneous connection monitoring before and after the cross-connect processing circuit 16 by determining whether the received (XC) path trace byte 2 n matches the path setting information stored in the memory.

  The SDH transmission apparatus configured as described above can detect a setting error or a failure in the cross-connect process by monitoring the path control information before and after the cross-connect process circuit.

It is a block diagram which shows the structure of the SDH transmission apparatus which concerns on 1st Example of this invention. It is a block diagram which shows the structure of the path monitoring circuit in a transmission part and a receiving part. It is a flowchart showing operation | movement of a path | pass monitoring circuit. It is a block diagram which shows the structure of the SDH transmission apparatus which concerns on 2nd Example of this invention.

Explanation of symbols

1 clock extraction circuit 1a transmission STM-N signal 1b clock signal 1c transmission STM-N overhead data 1d transmission VC-4 signal 1e transmission unit path setting data 1f transmission unit path information transfer bit 1g transmission auxiliary signal 1h transmission VC-4 (XC ) Signal 1i Transmission STM-N data signal 1j Transmission auxiliary data signal 1k Transmission signal 1m Transmission (XC) Path trace byte 2 Overhead extraction circuit 2a Radio reception signal 2b Radio frame reception data signal 2c Reception data extraction timing signal 2d Reception STM- N data signal 2e Reception auxiliary data signal 2f Reception STM-N overhead data 2g Reception VC-4 signal 2h Reception unit path setting data 2i Reception unit path information transfer bit 2j Reception VC-4 (XC) signal 2k Reception STM-N signal 2m Reception auxiliary signal 2n reception (XC) Strace byte 3, 3 'Path monitoring circuit 3a Extracted path information transfer bit 3b AIS trigger alarm 3c Path trace byte 3d Device path setting information 4 Cross-connect processing circuit 5 Overhead insertion circuit 6 Auxiliary signal switching circuit 7 Wireless transmission circuit 8 Overhead extraction circuit 11 Radio reception circuit 12 Received data extraction circuit 13 Frame synchronization circuit 14 Overhead extraction circuit 15, 15 'Path monitoring circuit 16 Cross-connect processing circuit 17 Overhead insertion circuit 18 Auxiliary signal switching circuit 19 Overhead extraction circuit 21 Overhead processing circuit 22 Memory 23 Path Determination circuit 100, 100a transmitter 200, 200a receiver

Claims (14)

A first overhead extraction circuit for extracting overhead information in a main signal transmitted from the preceding apparatus;
A path monitoring circuit that performs path connection monitoring using the first path setting information included in the overhead information or the second path setting information transmitted using the first auxiliary signal from the preceding apparatus;
An auxiliary signal switching circuit for transferring the first or second path setting information using a second auxiliary signal to the latter apparatus when transferring an alarm display signal to the latter apparatus;
An SDH (Synchronous Digital Hierarchy) transmission apparatus. The path monitoring circuit includes a path determination circuit that compares the first or second path setting information with third path setting information stored in advance.
2. The SDH transmission apparatus according to claim 1, further comprising a cross-connect processing circuit that performs cross-connect processing in units of predetermined frames included in the main signal based on a determination result of the path determination circuit.   2. The SDH according to claim 1, wherein the overhead information includes a path information transfer bit indicating whether or not the first or second path setting information is transferred using the first auxiliary signal. Transmission equipment. A second overhead extraction circuit that extracts path trace information inserted in overhead in a predetermined frame in the output signal of the cross-connect processing circuit and outputs the information to the path monitoring circuit;
3. The SDH transmission apparatus according to claim 2, wherein the path monitoring circuit monitors the path trace information based on information on inputs and outputs of the cross-connect processing circuit.   2. The SDH transmission apparatus according to claim 1, wherein either one of the main signal and the first or second auxiliary signal is transmitted through a wireless line. A transmitter and a receiver,
2. The SDH transmission apparatus according to claim 1, wherein each of the transmission unit and the reception unit includes the first overhead extraction circuit, the path monitoring circuit, and the auxiliary signal switching circuit.   The SDH transmission apparatus according to claim 6, wherein each of the transmission unit and the reception unit further includes the cross-connect processing circuit according to claim 2.   The SDH transmission apparatus according to claim 7, wherein each of the transmission unit and the reception unit further includes the second overhead extraction circuit according to claim 4. Extracting overhead information in the main signal transmitted from the preceding apparatus;
Performing path connection monitoring using first path setting information included in the overhead information or second path setting information transmitted from the preceding apparatus using a first auxiliary signal;
Transferring the path setting information using a second auxiliary signal to the latter apparatus when transferring the alarm display signal to the latter apparatus;
A path monitoring method for an SDH (Synchronous Digital Hierarchy) transmission apparatus, comprising: Comparing the first or second path setting information with pre-stored third path setting information;
Performing a cross-connect process in a predetermined frame unit included in the main signal based on the comparison determination result;
The SDH transmission apparatus path monitoring method according to claim 9, further comprising:   10. The SDH according to claim 9, wherein the overhead information includes a path information transfer bit indicating whether or not the first or second path setting information is transferred using the first auxiliary signal. Transmission device path monitoring method. Extracting and outputting path trace information inserted in overhead in a predetermined frame in an output signal obtained by the cross-connect processing,
11. The path monitoring method for an SDH transmission apparatus according to claim 10, wherein in the step of monitoring the path connection, the path trace information is monitored based on information before and after the cross-connect process. In the step of monitoring the connection of the path,
Detecting whether an alarm display signal from the preceding apparatus is transmitted;
Detecting whether the path information transfer bit indicates transferring the first or second path setting information when the alarm indication signal is transmitted; and
Extracting the first or second path setting information being transferred using the first auxiliary signal when indicating that the first or second path setting information is being transferred;
The SDH transmission apparatus path monitoring method according to claim 9, further comprising:   The SDH transmission apparatus includes a transmission unit and a reception unit, and the path monitoring method according to any one of claims 9 to 13 is executed in each of the transmission unit and the reception unit. Method.

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