JP3811706B2 - Optical signal transmission device - Google Patents

Description

  The present invention relates to a configuration of a digital transmission device and a configuration of a communication network using the same, and more particularly to a configuration of a transmission device suitable for use in a high-speed synchronous digital hierarchy and a configuration of a communication network using the same.

  In today's digital transmission networks, synchronization technology has been developed and higher-speed transmission devices using optical transmission and communication networks are being synchronized. A global standard has been established for the functions and configurations of the digital synchronous transmission network and the transmission device, and high-quality transmission can be performed anywhere by introducing the transmission device and the communication network according to the standard. As an example of a specific standard, the International Telecommunications Union (hereinafter referred to as ITU-T) recommends G. A standard related to a transmission system called SDH (Synchronous Digital Hierarchy) (Established in 1988) defined by 707, etc., and a SONET (SONET) defined by the American Standardization Committee (hereinafter referred to as ANSI) in standard T1.105 There is a standard (established in 1991) regarding a transmission system called Synchronous Optical Network, which defines the configuration of the optical synchronous communication system and the function of the transmission apparatus.

  The SDH or SONET is a synchronous multiplexed signal (frame) in which a signal called overhead for performing monitoring and maintenance operation of a transmission apparatus or a communication network is added to a main signal part called a payload obtained by multiplexing a digitized main signal. The overhead is equipped with a pointer, and this pointer is used to perform stuff control for frame phase synchronization and frequency adjustment, thereby monitoring less transmission delay than conventional digital synchronous transmission equipment. It provides a transmission system with excellent maintenance and operation capabilities. FIG. 1 and FIG. 2 are frame configuration diagrams showing the frame configuration of the multiplexed signal defined by SONET, and the multiplexed signals of OC-12 (622.08 MHz) and OC-192 (9953.28 Mhz), respectively. The configuration is shown. FIG. 3 is an explanatory diagram showing the function of each overhead byte included in the multiplexed signal. In these figures, the signal of the 1st to 36th columns (OC-12) or the 1st to 576th columns (OC-192) is overhead (see FIG. 3 for the necessity of each byte. Also, the unused (undefined) bytes are 1 and FIG. 2, and the remaining portion is a payload portion in which the main signal is multiplexed. FIG. 4 is a network configuration diagram illustrating a configuration of a transmission network using SDH or SONET and an overhead transmission section. Among the overheads of multiplexed signals shown in FIGS. 1 and 2, lines 1 to 3 are called section overheads, and monitoring and maintenance is performed for each transmission line section (defined as a section) between transmission apparatuses and repeaters. The overhead generated by a certain device (including a repeater) is terminated at the next device when transmitted via the transmission line (see the thin arrow in FIG. 4A). Of the overhead, the 5th to 9th lines are called line overheads, and are overheads for performing monitoring and maintenance operations for each transmission section (defined as a line) between transmission apparatuses that process multiplexed main signals. The overhead generated by a certain transmission device is transmitted via a transmission line or a repeater and terminated at the next transmission device (see the thick arrow in FIG. 4A). Of the overhead, the fourth byte is a pointer. Such a frame configuration and function are all defined in the above standards.

  Examples of the configuration of a transmission apparatus or network using the SDH or SONET are those disclosed in Japanese Patent Application Laid-Open Nos. 4-79628 and 5-114892.

  In the transmission network shown in FIG. 4A, the multiplexing apparatus B (2001) and the multiplexing apparatus C (2004) are connected by an OC-12 transmission line through the repeaters 2002 and 2003. . For example, when it is desired to transmit and receive D bytes called data communication channels and E bytes called order wires for monitoring and maintenance operations between the multiplexers B (2001) and C (2004), one multiplexer ( For example, in B), data and audio signals necessary for maintenance operation are inserted and transmitted to the OC-12 transmission line for D4 to 12 bytes and E2 bytes of the line overhead. These line overheads are terminated between the multiplexing apparatuses B (2001) and C (2004) because they are terminated by the multiplexing apparatus (C in the figure) via the OC-12 transmission line and the repeater. Maintenance operation is performed.

  However, when the number of subscribers of the network increases or the amount of signals to be transmitted / received increases in the transmission network, a multiplexing device is added or a transmission line in the middle is replaced with a higher-speed transmission line to cope with this. The transmission network is expanded or changed. An example of this is shown in FIG. 4 (B). As the amount of communication increases, the number of multiplexing devices corresponding to the multiplexing devices B (2001) and C (2004) is increased (in FIG. 4B, simplified). For this reason, only one of them is shown), and instead of the repeaters 2002 and 2003, a plurality of multiplexers E (2008) and F are provided which accommodate a plurality of these multiplexers and process signals. (2009) is introduced, and the configuration of a transmission network changed to a transmission network connected by a high-speed transmission path OC-192 is shown.

  When the transmission network is changed from FIG. 4 (A) to FIG. 4 (B) as the amount of communication increases, the SDH and SONET standards are configured to terminate the line overhead for each transmission device as described above. After the addition of the multiplexing apparatuses E (2008) and F (2009) (B), the overhead from the multiplexing apparatus B (2001) is terminated at the multiplexing apparatus E (2008), and the multiplexing apparatus C (2004) Is terminated at the multiplexing apparatus F (2009), and if this is the case, the overhead is performed between the multiplexing apparatuses B (2001) and C (2004) before the addition of the multiplexing apparatus (A). Monitoring and maintenance operations will not be possible. In other words, the transmission capacity of the main signal is improved by changing the configuration of the transmission network, but the monitoring and maintenance operation capacity change of the transmission network occurs, such as the monitoring and maintenance operation between the transmission apparatuses that have been carried out until now can occur, A situation in which monitoring maintenance operation information that has been known so far cannot be obtained for a maintenance person of the transmission network occurs, which may be inconvenient for the maintenance person.

  An object of the present invention is to prevent the change in the monitoring and maintenance operation capability accompanying the change in the configuration of the transmission network as described above, and the monitoring and maintenance operation capability does not change even when the transmission network is changed, or more flexible and performance. It is an object of the present invention to provide a transmission apparatus and a transmission network that can perform superior monitoring and maintenance operations with a simple configuration.

  Specifically, in addition to the overhead processing standardized by SDH and SONET, a transmission apparatus having a function of passing overhead is provided. In addition, a flexible transmission network with excellent monitoring and maintenance operation performance and its configuration and operation method capable of transmitting and receiving an arbitrary overhead between arbitrary transmission apparatuses in the transmission network using such a transmission apparatus, and a configuration operation method thereof are provided. There is.

  More specifically, the present invention provides a means for selecting and editing received overhead in a digital transmission apparatus and transmitting the selected overhead to another digital transmission apparatus with a simple configuration. Further, for overhead that cannot be transmitted to the counterpart device simply by passing the overhead, a means for converting the overhead into information that can be used by the counterpart device is provided with a simple configuration. In particular, for a transmission error that occurs in a transmission section in which overhead is transmitted and received, there is a need to provide means with a simple configuration that can reliably transmit the number of errors and manage transmission quality.

  Another object of the present invention is to provide a method for selecting and editing overhead between selected transmission apparatuses in a digital transmission network, and a method for detecting and transmitting a transmission error occurring in a transmission section.

  In order to solve the above-described problem, a multiplexing transmission apparatus according to the present invention receives a multiplexed signal composed of a payload in which a plurality of main signals are multiplexed and a plurality of overhead bytes including maintenance information related to monitoring and maintenance operations. After performing maintenance information termination processing and payload main signal transmission processing, a plurality of overhead bytes including maintenance information related to monitoring and maintenance operations are added to the payload obtained by multiplexing the transmission-processed main signal and transmitted. The multiplex transmission apparatus includes means for selecting predetermined maintenance information from a plurality of maintenance information included in the received multiplexed signal and inserting the selected maintenance information into overhead bytes of the transmission side multiplexed signal.

  Specifically, means for extracting predetermined maintenance information from a plurality of maintenance information included in the multiplexed signal received by the multiplexed transmission apparatus and the extracted maintenance information as predetermined bytes of the overhead byte of the transmission side multiplexed signal Overhead passing means for passing maintenance information, which comprises insertion means for insertion at the position. Note that the passage means may be provided with editing means for editing the extracted maintenance information.

  The multiplexed transmission apparatus receives a plurality of multiplexed signals composed of a payload and a plurality of overhead bytes including maintenance information related to a plurality of monitoring and maintenance operations, and further performs a plurality of maintenance information termination processes and a plurality of payloads. It multiplexes into a payload with a large multiplicity, converts it to a multiplexed signal with a larger overhead byte than the transmission side including maintenance information related to a plurality of monitoring and maintenance operations, and transmits it. Passes maintenance information comprising means for extracting predetermined maintenance information from a plurality of maintenance information, editing means for editing the information extracted by the extraction means, and insertion means for inserting the output of the editing means at a predetermined position of the overhead byte Multiplexed transmission with overhead passing means for transferring maintenance information received from multiple transmission paths at once It was the location. Similarly, the multiplex transmission apparatus in the reverse direction similarly overheads the means for extracting predetermined maintenance information from a plurality of maintenance information, the editing means for editing the information extracted by the extraction means, and the output of the editing means. Overhead means for passing maintenance information comprising insertion means for inserting at a predetermined position of the byte, and when receiving signals that have been transferred through a collection of maintenance information, these signals are extracted and edited to obtain a plurality of transmission lines. The multiplexing transmission apparatus is inserted at the specified position of the overhead byte.

  Here, each of the above-described multiplexing transmission devices is the international telecommunications union recommendation G.3. 707 or the standard of the American National Standardization Committee. The system handles the multiplexed signal defined in 105, and the maintenance information to be passed is included in the section overhead and the line overhead. The information is transferred into the multiplexed signal line overhead. In addition, when such a multiplexing device is directly connected, more maintenance information is passed and transferred using the section overhead. When passing the E byte, the F byte, the D byte, the K byte, and the Z byte defined in the standard as maintenance information, these bytes are selected and passed as they are.

  On the other hand, when the number of error occurrences in the receiving transmission path is detected as a configuration for passing information on transmission path errors such as B bytes defined in the above standard, this error occurrence number is inserted into the overhead bytes of the multiplexed signal. And means for transferring the number of transmission path errors. In the multiplexed transmission apparatus that receives the transferred maintenance information, means for extracting the number of transmission path errors, means for adding the extracted number of transmission path errors and the number of transmission path errors detected by this apparatus, This addition result is further inserted into the overhead and transferred, or transmission path error transmission is performed by adding a transmission path error in advance to the error detection signal of another transmission apparatus to be transmitted by this multiplexing transmission apparatus. Means. The intermediate multiplexing transmission apparatus is configured to transfer the number of transmission path errors extracted by the extracting means as it is, and the number of transmission errors generated in the transmission section for transferring the information regarding the error to the final multiplexing apparatus. Detecting means, means for extracting the number of transmission path errors, means for adding the number of extracted transmission path errors and the number of transmission path errors detected by the detecting means, and errors of other transmission equipment transmitted by the multiplexing transmission equipment It may be configured to include transmission path error transmission means for adding a transmission path error in advance to the detection signal only for the addition result.

  In order to further solve the problem, the multiplex transmission network according to the present invention uses the above-described apparatus as a multiplex transmission apparatus, and allows any maintenance information to pass through the multiplex apparatus in the middle between any multiplex transmission apparatuses. The multiplexed transmission network is configured to transmit / receive arbitrary maintenance information between the arbitrary multiplexed transmission apparatuses.

  According to the multiplexing transmission apparatus and the transmission network of the present invention, the overhead for transmitting / receiving information related to the monitoring / maintenance operation terminated for each apparatus in the conventional transmission apparatus can be transmitted / received between desired transmission apparatuses in the network. Therefore, it is possible to provide a transmission apparatus and a transmission network that have excellent monitoring and maintenance operation capability that does not depend on a change in network configuration or a monitoring and maintenance operation method.

  Embodiments of a transmission apparatus and a transmission system or network using the transmission apparatus according to the present invention will be described below in detail with reference to the drawings. In the embodiment of the present invention, a transmission apparatus and a transmission system mainly used in SONET will be described as an example. However, the same applies to a transmission apparatus and a transmission system using SDH. The transmission system is monitored every time the overhead of the transmission frame is terminated, by allowing the transmission apparatus to pass the overhead and enabling transmission and reception of overhead between the desired apparatuses in the transmission system. An embodiment of a transmission apparatus capable of improving maintenance operation capability and an embodiment of a transmission system using the multiplexing apparatus will be described.

  FIG. 5 is a block diagram showing an embodiment of the multiplexing apparatus according to the present invention. The multiplexing apparatus of the present invention accommodates a low-speed multiplexed signal composed of a plurality of overheads and a multiplexed main signal and a high-speed multiplexed signal composed of a main signal multiplexed with one overhead. An apparatus for performing demultiplexing between a plurality of low-speed multiplexed main signals and a single high-speed multiplexed main signal while performing processing such as overhead termination and replacement of the multiplexed signal, , 16 OC-12 (622.08 MHz: see FIG. 1) are accommodated as low-speed multiplexed signals, and defined by SONET with high-speed multiplexed signal OC-192 (9953.28 MHz: see FIG. 2) While performing demultiplexing and overhead processing of the main signal, the overhead of the multiplexed signal input to the device according to the present invention is passed through for use in other multiplexing devices. Of course, the above description is an example, and the speed of the multiplexed signal to be accommodated may be other speeds such as OC-0 to 192 or the speed defined by SDH, and the number of multiplexed signals to be accommodated is This can be changed depending on the type of multiplexed signal to be accommodated.

  In FIG. 5, the multiplexing apparatus of the present invention includes a low-speed signal transmission / reception unit 10-1 to 10-M that inputs and outputs M sets of low-speed multiplexed signals and performs processing of overhead and main signals, A pair of high-speed transmission / reception units 11 that input / output multiplexed signals and process overhead and main signals, and perform demultiplexing conversion between main signals of low-speed multiplexed signals and main signals of high-speed multiplexed signals The main signal demultiplexing / conversion unit 100, and the overhead processing unit according to the present invention that edits and passes the overhead included in each signal between the low-speed multiplexed signal and the high-speed multiplexed signal so that it can be used in another multiplexing apparatus. 300 (300-1, 300-2) and a control unit 400 that controls the entire multiplexing apparatus, and performs signal demultiplexing conversion and overhead processing.

  More specifically, each of the low-speed signal transmission / reception units 10-1 to 10-M performs low-speed signal reception and reception section overhead processing, and passes some section overhead bytes to perform other transmissions. SOH (section overhead) termination units 20-1 to 20-M that extract section overhead bytes for transmission to a device or a multiplexed signal transmission / reception unit, receive line overhead processing, and part of line overhead bytes Lines transmitted from some other transmission devices and multiplexed signal transmission / reception units, with LOH (line overhead) termination units 30-1 to 30-M to be extracted in the same manner as overhead and transmission line overhead bytes. LOH insertion units 80-1 to 80-M for inserting overhead bytes, and transmission SOH insertion units 90-1 to 90-M for adding section overhead bytes and for inserting section overhead bytes and transmitting low-speed signals transmitted from some other transmission devices and multiplexed signal transmitting / receiving units. The high-speed transmission / reception unit 11 includes a high-speed signal SOH termination unit 60, an LOH termination unit 70, an LOH insertion unit 40, and an SOH insertion unit 50, similar to the low-speed signal transmission / reception unit. It was set as the structure provided. Each of the overhead processing units 300-1 and 300-2 includes an overhead multiplexing unit 110 that collects the overhead extracted from the transmission / reception units (10-1 to 10-M, 11) of the multiplexed signals. 130, spatial switch units 200 and 210 that edit the collected overhead according to a predetermined rule to send the collected overhead to another transmission device or a transmission / reception unit for multiplexed signals, and transmission / reception of the multiplexed overhead for each multiplexed signal The unit (10-1 to 10-M, 11) is composed of overhead separation units 120 and 140 that distribute the LOH insertion unit and the SOH insertion unit. With this configuration, the low-speed multiplexed signal and the high-speed multiplexed signal are accommodated to perform demultiplexing of the main signal, and a predetermined overhead is passed in the transmission system using this multiplexing apparatus or processing (termination / attachment) Thus, it is possible to provide a multiplexing device that can provide flexibility in an easy-to-use system configuration that is superior in monitoring and maintenance operation capability so that overhead can be used between desired transmission devices. .

  Hereinafter, in a multiplexing apparatus that accommodates OC-192 for high-speed multiplexed signals and OC-12 (16) for low-speed multiplexed signals, the overhead (order wires E1, E2,. The data channels D1 to D12, the transmission path switching control bytes K1 and K2, and the inter-line (inter-device) error monitoring byte B2) are passed between the 15 pairs of transmission devices (FIG. 4B) using the low-speed multiplexed signal. The configuration and operation of the multiplexing apparatus of the present invention and the operation of the transmission system will be described by taking as an example the case of use in the illustrated multiplexing apparatus B-C).

  6 and 7 are overhead configuration diagrams showing the configuration of the overhead of the high-speed signal passing through the overhead of the low-speed signal used in the multiplexing apparatus of this embodiment. FIG. 6 shows the overall configuration of the overhead and a part of the detailed configuration. FIG. 7 shows the remaining detailed configuration.

  First, the operation on the multiplexing side for receiving a low-speed multiplexed signal, converting it to a high-speed multiplexed signal, and transmitting this high-speed multiplexed signal will be described.

  The SOH termination units 20-1 to 20-M and the LOH termination units 30-1 to 30-M of the low-speed signal transmission / reception units 10-1 to 10-M terminate the overhead of the received multiplexed signal in the same manner as in a normal multiplexing device. The main signal is processed and sent to the main signal demultiplexing / conversion unit 100. Here, normal termination processing is to check the normality between sections and lines between the multiplexing device and the transmission device on the opposite side of the multiplexed signal transmission. Synchronize or check for signal errors with the B1 byte. The processing related to the monitoring and maintenance operation between devices or between transmission lines is performed by the overhead determined in 105. Further, the main signal is multiplexed into the main signal of the high-speed signal according to a predetermined multiplexing rule (for example, mapping from FIG. 1 to FIG. 2) by the main signal demultiplexing / conversion unit 100. On the other hand, in the multiplexing apparatus of the present invention, a part of these overheads are passed for use between desired transmission apparatuses, so that the SOH termination units 20-1 to 20-M and the LOH termination units 30-1 to 30-M The received overhead (other than the B2 byte) is transmitted as it is to the overhead processing unit 300-1 as it is branched. In addition, since the B2 byte cannot be simply passed as will be described later, the number of errors in the line section detected as normal B2 byte termination processing by each of the LOH termination units 30-1 to M is encoded. The converted signal is transmitted to the overhead processing unit 300-1.

  The overhead processing unit 300-1 selects an overhead and inserts it into an unused area of the multiplexed signal to be transmitted in order to pass a part of the overhead received by the multiplexing apparatus and transmit it to another transmission apparatus. The overhead multiplexing unit 110 collects overhead transmitted from each of the low-speed signal transmission / reception units 10-1 to 10-M. Specifically, if 16 low-speed multiplexed signals are accommodated in OC-12, overhead is sent in the format shown in FIG. 1 from each of the low-speed signal transmission / reception units 10-1 to 10-M. Therefore, by sequentially accessing each unit using a multiplexer, the overhead to be passed from each unit is selected, and multiplexing is performed so that the overhead types are collected. As an example, D4 bytes (see FIG. 1) in 6 rows and 1 column of each low-speed multiplexed signal are put together into 6 rows and 5 columns to 61 columns of the high-speed multiplexed signal (see FIGS. 6, 1000, and 1002). ) Since the overhead of the low-speed multiplexed signal is grouped for each type and inserted into unused bytes of the high-speed multiplexed byte so as to pass, each unit is accessed sequentially to collect the overhead for each type. That is, in the above example, multiplexing is performed so that only the D4 bytes of each low-speed multiplexed signal are collected. In addition, a buffer may be provided on the input side of the multiplexer so that multiplexing can be performed even if the phases of the respective low-speed multiplexed signals are different, or the phases of the signals transmitted to the overhead multiplexing unit 110 may be aligned in each unit. good. Further, the B2 byte has been described as being received by the LOH termination unit, but the B2 byte itself may be received from the LOH termination unit and the above processing performed by the overhead multiplexing unit 110. good.

The space switch unit 200 performs editing so that the overhead bytes sent from the overhead multiplexing unit 110 are further rearranged. In this embodiment, a space switch is used, but a time switch may of course be used. With either switch, editing can be performed by selecting the overhead or changing the order so that the overhead received from each low-speed multiplexed signal can be inserted into a predetermined byte of unused bytes of the high-speed multiplexed signal. Anything is fine. Specifically, in the present embodiment, the overhead of 15 multiplexed signals (1 to 15) is passed from 16 low-speed multiplexed signals OC-12, and the spatial switch 200 includes an overhead multiplexing unit. Only overhead for passing multiplexed signals (1 to 15) out of 110 outputs (order wires E1 and E2, data channels D1 to D12, transmission path switching control bytes K1 and K2, line-to-line (inter-device) error monitoring byte B2 ) Are selected and passed (see 1000 to 1004, 1100 to 1107, and 1200 to 1208 in FIGS. 6 and 7). Further, as shown in FIG. 1, in the low-speed multiplexed signal, the D1 byte that was on the head frame side from the D4 byte is inserted after the D4 byte in the high-speed multiplexed signal that has passed through the multiplexer (FIG. 6). 1000, 1001, 1004). That is, the space switch 200 also changes the order of the overheads that are passed through so that the designated type of overhead can be inserted into the previously designated bytes of the unused bytes in the overhead area.

  Since the overhead byte is sent from the space switch unit 200, the overhead separation unit 120 separates this overhead into a section overhead and a line overhead using a demultiplexer, or the high-speed multiplexed signal shown in FIGS. Are separated so as to be inserted into a predetermined byte in the overhead area, and transferred to the high-speed signal transmission / reception unit 11. As an example, if the D4 byte of the low-speed signal is given, as indicated by 1000 and 1002 in FIG. 6, the D4 byte of each low-speed multiplexed signal is 61 every 5 columns from 6 rows and 5 columns in the overhead area of the high-speed multiplexed signal. The D4 byte of each low-speed multiplexed signal is separated so as to be inserted up to the column.

  The high-speed signal transmission / reception unit 11 uses the SOH insertion unit 50 and the LOH insertion unit 40 to generate overhead bytes to be used in the section section and the line section of the transmission-side transmission line in the same manner as a normal multiplexing device, while the overhead separation section As shown in FIGS. 6 and 7, the overhead extracted by the low-speed signal receiving unit received from 120 is inserted into a predetermined unused byte of the line overhead of the high-speed signal to generate the overhead to be transmitted. The high-speed multiplexed signal added to the main signal of the high-speed signal multiplexed by the demultiplexing conversion unit 100 is transmitted. In this embodiment, if there is a repeater in the middle of the transmission path, the section overhead is terminated at this repeater. is there. Of course, if there is no repeater or the like in the transmission path on the way and the section overhead is not terminated up to the transmission apparatus of the transmission destination, unused bytes in this section overhead area may be used. In this case, the overhead of a large number of low-speed multiplexed signals can be passed.

  Next, the operation on the demultiplexing side that receives a high-speed multiplexed signal, converts it to a low-speed multiplexed signal, and then transmits this low-speed multiplexed signal will be described.

  Similar to the low-speed signal transmission / reception unit 10, the SOH termination unit 60 and the LOH termination unit 70 of the high-speed signal transmission / reception unit 11 terminate the overhead of the received multiplexed signal in the same manner as a normal demultiplexer. The main signal is sent to the main signal demultiplexing / conversion unit 100. The main signal is separated into a main signal of a low speed signal by the main signal demultiplexing / conversion unit 100. On the other hand, since the overhead to be passed between the desired transmission devices transmitted from the transmission device on the transmission side is inserted into the received overhead, the SOH termination unit 60 and the LOH termination unit 70 receive the received overhead. The overhead is branched and transmitted to the overhead processing unit 300-2.

  The overhead processing unit 300-2 selects and inserts overhead into a specified position of the overhead of each low-speed multiplexed signal to be transmitted and transmitted to another transmission apparatus through a part of the received overhead. Processing is performed, and processing similar to that of the overhead processing unit 300-1 on the multiplexing side is performed on the demultiplexing side with the processing direction reversed. That is, the overhead multiplexing unit 130 collects overhead that has passed through another transmission device received by the high-speed signal transmission / reception unit 11, and the space switch unit 210 receives the overhead bytes sent from the overhead multiplexing unit 130. Edit so that they can be rearranged. The overhead separation unit 140 separates the overhead sent from the space switch unit 210 into a section overhead and a line overhead, or separates the overhead so as to be inserted into a specified byte in the overhead area of the low-speed multiplexed signal shown in FIG. Then, transfer to each of the low-speed signal transmission / reception units 10-1 to 10-M.

  Each of the M sets of low-speed signal transmission / reception units 10-1 to M-1 low-speed signal transmission / reception units is transmitted in the same manner as a normal multiplexer by the SOH insertion units 80-1 to M and LOH insertion units 90-1 to M. While the overhead bytes used in the section section and line section of the side transmission path are generated, the overhead extracted by the high-speed signal receiving section received from the overhead separating section 140 is defined as the line overhead of the low-speed signal as shown in FIG. The overhead which should be inserted and transmitted is created, and the low-speed multiplexed signal added to the main signal of the low-speed signal separated by the main signal demultiplexing converter 100 is transmitted to the low-speed transmission path.

  Here, B2 byte passing processing in a transmission apparatus capable of passing the received overhead according to the present invention to another transmission apparatus will be described using the multiplexing apparatus used in the above embodiment.

  FIG. 8 is an operation explanatory diagram for explaining a B2 byte calculation area for detecting a transmission error in a line section in a transmission apparatus used in SONET or SDH. The transmission apparatus used in SONET or SDH uses the pointer (H byte in the fourth row) in the overhead area as shown in FIG. 1 to reduce the phase of the multiplexed signal in order to reduce the delay of the multiplexed signal. A device that performs identification and signal processing such as demultiplexing. In each transmission device, each device such as a conventional transmission device is re-identified by changing the pointer to the frame forming the multiplexed signal. No frame phase adjustment is performed. For this reason, as shown in FIG. 8, the B2 calculation area of the multiplexed signal received and the B2 calculation area of the multiplexed signal to be transmitted are shifted by changing the pointer, so that the received B2 byte is the same as other overhead bytes. Even if the data is passed through, the transmission device that receives the overhead cannot correctly detect the error due to the received B2 byte.

  That is, as described above, since the B2 byte cannot be directly passed, the multiplexing side of this multiplexing apparatus reads the B2 byte by each of the LOH termination units 30-1 to 30-M of the low-speed signal transmission / reception unit. In this configuration, the number of detected errors is obtained (terminated), and a signal in which the number of detected errors (j in the following description) is coded is transmitted and transmitted to the transmission apparatus on the other side. Specifically, a signal (number of errors j) created by terminating the B2 byte (FIG. 1: 5 rows 1 to 12 columns) of each low-speed multiplexed signal is used as an unused byte (see FIG. 7, 1103).

  On the other hand, on the demultiplexing side of this multiplexing apparatus, if the number of errors j sent from the transmitting side is sent as it is to the other side apparatus in the same manner as other overhead bytes, the configuration of the originally defined B2 byte Since different signals are transmitted, the other device cannot detect the number of errors. Further, what is desired to be transmitted / received is the number of errors occurring in the transmission path between desired transmission apparatuses (between the transmission apparatuses B and C in FIG. 4B), and the value of j indicates the transmission between the multiplexing apparatuses. Since the number of errors generated on the road is not included, correction is also necessary. Accordingly, the demultiplexing side of the multiplexing apparatus of the present embodiment is configured to perform the following processing in addition to the above description regarding the B2 byte processing.

  First, the LOH terminator 70 of the high-speed signal transmission / reception unit 11 detects the B2 byte for detecting a transmission error between the multiplexing devices (this is defined in the original high-speed multiplexed signal, as shown in FIG. 6 is read (B2 byte in 5 rows 1 to 192 columns) and the error detection number i is obtained (terminated). Further, the LOH termination unit 70 calculates the sum k of i and j by separating the encoded error detection number j from the line overhead (FIG. 6, 1103) of the high-speed signal.

  Next, the overhead multiplexing unit 130 of the overhead processing unit 300-2 multiplexes the k value and transfers it to the space switch unit 210. The space switch unit 210 rearranges these overhead bytes in units of low-speed signal transmission / reception units. The overhead separation unit 140 separates the overhead bytes sent from the space switch unit 210 into a section overhead and a line overhead and transfers them to M sets of low-speed signal transmission / reception units 10-1 to M, respectively.

  Then, the LOH insertion units 80-1 to 80-M generate the B2 parity of one frame to be transmitted here, and then invert the bit by an amount corresponding to the value of k, and insert the B2 byte as the overhead of the low-speed signal to perform the low-speed operation. By transmitting to the transmission line on the side, it is possible to detect an error in the transmission apparatus on the other side. Of course, the B2 byte operation on the demultiplexing side may be performed by the overhead multiplexing unit 130 as in the multiplexing side, or may be performed by the LOH insertion units 80-1 to 80-M. A configuration in which bit inversion is performed may be employed.

  In the multiplexing apparatus which is an embodiment of the transmission apparatus of the present invention described above, when information related to the system configuration is received from a network management apparatus or the like (not shown), the control unit 400 causes the overhead processing unit 300 and the multiplexed signal transmission / reception unit 10. By setting −1 to M, 11 or the like, it is possible to select the type of overhead to be passed through this apparatus to be passed and the position of unused bytes to insert overhead.

  FIG. 9 is a network configuration diagram showing a configuration example of a transmission network using the multiplexing apparatus of the present invention. As additional multiplexing apparatuses E and F in the network configuration diagram shown in FIG. The network configuration in the case of using the above-described multiplexing device is shown in detail. The figure shows an example of overhead transmission from the multiplexing apparatus B to the multiplexing apparatus C. The multiplexing apparatus of the present invention has only the multiplexing side and the demultiplexing side required for each multiplexing apparatus. Is shown.

  The transmission network using the multiplexing apparatus of the present invention includes a multiplexing apparatus B2001 that multiplexes a main signal and transmits a low-speed multiplexed signal to the low-speed transmission path 500, and a high-speed signal transmission path by further multiplexing the low-speed multiplexed signal. A multiplexing device E2006 that transmits a high-speed multiplexed signal to the high-speed signal transmission line 501, a multiplexing device F2007 that separates the high-speed multiplexed signal received from the high-speed signal transmission line 501 and transmits a low-speed multiplexed signal to the low-speed signal transmission line 502; It consists of a multiplexer C2004 that separates the low-speed multiplexed signal into a lower-speed main signal, and transmits the main signal to be processed by the multiplexer B2001 to the multiplexer C2004, and between the multiplexers B2001 and C2004. The overhead of the low-speed multiplexed signal is also transmitted to perform monitoring and maintenance operation of the transmission system.

  More specifically, when the multiplexer B2001 multiplexes the main signal and transmits the low-speed multiplexed signal to which the overhead is added to the low-speed signal transmission path 500, the multiplexer E2006 transmits the overhead termination and the main of the low-speed multiplexed signal. While performing signal multiplexing and high-speed multiplexed signal overhead generation, overhead passing processing, which is a feature of the present invention, is performed. As described above with reference to FIGS. 5 to 7, this passing process includes the SOH termination unit 20 and the LOH termination unit 30 for the low-speed signal, the overhead multiplexing unit 110, the spatial switch 200, and the overhead separation unit 120. The overhead processing unit 300-1 and the high-speed signal LOH insertion unit 40 and the SOH insertion unit 50 select and edit the overhead of the low-speed multiplexed signal specified by the control unit 400 to specify the overhead of the high-speed multiplexed signal. This is done by inserting it at the position (see FIGS. 6 and 7). When the designated overhead includes B2 bytes, the B2 byte processing as described above is also performed.

  The multiplexer F2007, which has received the high-speed multiplexed signal including overhead to be passed from the multiplexer E2006 via the high-speed transmission path 501, separates the overhead of the high-speed multiplexed signal, the main signal, and the low-speed multiplexed signal. The overhead passing process, which is a feature of the present invention, is performed. As described above, this passing process is the reverse of the passing process of the multiplexer E2006, and the SOH terminating unit 60 and the LOH terminating unit 70 for the high-speed signal, the overhead multiplexing unit 130, and the spatial switch 210 and overhead separation unit 140, and low-speed signal LOH insertion unit 80 and SOH insertion unit 90 allow low-speed multiplexing to be included in the high-speed multiplexed signal designated by control unit 400. This is done by selecting and editing the signal overhead and inserting it at a specified position in the overhead of the low-speed multiplexed signal. When the designated overhead includes B2 bytes, the B2 byte processing as described above is also performed.

  With the above configuration and operation, even in a transmission network in which other multiplexers E and F are inserted between the multiplexers B-C, transmission of the main signal between the multiplexers B-C In addition, the overhead transmission of the low-speed multiplexed signal is transmitted without being terminated by the multiplexers E and F.

  The transmission apparatus of the present invention can pass an arbitrary overhead of the multiplexed signal by the configuration and operation described in the above embodiments. That is, even when the transmission system as shown in FIG. 4A is changed to the new system as shown in FIG. 4B, the multiplexing device shown in this embodiment is added to the newly added multiplexing device. If used, the overhead used between the multiplexers B-C before the system change passes through without being terminated at the new multiplexer, so even between the multiplexers B-C of the system after the change. Can be used. Therefore, there is no change in the monitoring and maintenance operation capability between the multiplexing devices due to the change in the system configuration. Further, since overhead between desired transmission apparatuses can be used, it is possible to provide a multiplexing apparatus that is superior in monitoring and maintenance operation capability and that is easy to use and that allows flexibility in system configuration.

  Further, another embodiment of the transmission apparatus according to the present invention and an embodiment of a transmission system or network using the transmission apparatus will be described in detail below with reference to the drawings.

  FIG. 10 is a block diagram showing an embodiment of an add-drop multiplexer (hereinafter referred to as ADM) which is a transmission apparatus according to the present invention. FIG. 11 is a network configuration diagram showing a configuration example of a transmission network using the ADM of the present invention.

  The ADM of the present invention accommodates a low-speed multiplexed signal composed of a plurality of overheads and a multiplexed main signal and a high-speed multiplexed signal composed of two overheads and a multiplexed main signal. Performs processing such as termination and replacement of signal overhead, and inserts (adds) a plurality of low-speed multiplexed main signals into a high-speed multiplexed main signal or a plurality of high-speed multiplexed main signals. A demultiplexer for branching (dropping) a plurality of low-speed multiplexed main signals and for exchanging (cross-connecting) or passing (through) high-speed multiplexed main signals. Similarly, for example, the main signal processing and the overhead processing specified by SONET are performed with the low-speed multiplexed signal as OC-12 and the high-speed multiplexed signal as OC-192. The overhead of the multiplexed signal input to the device by those passing for use in another transmission apparatus. In the transmission network using this ADM, as shown in FIG. 11, the ADMs are stepped (FIG. 11 (A)) or looped (FIG. 11 (B)) with a high-speed transmission path (OC-192). In addition to connecting, a transmission apparatus such as a ADM low-speed transmission path (OC-12) multiplexer is connected, and the main signal between the transmission apparatuses is processed by the ADM as described above. In addition to performing transmission and reception, overhead transmission and reception of arbitrary low-speed multiplexed signals between arbitrary transmission devices is also performed by overhead passing processing according to the present invention, so that overhead can be freely transmitted and received between transmission devices in the network like the main signal. To build a flexible transmission system with superior monitoring and maintenance capability.

  The configuration of this ADM is almost the same as that of the multiplexing device described above, and a main signal insertion / separation unit 105 for performing the above-mentioned add / drop / cross-connect through is added to the main signal, and other functional blocks are added. Is a configuration in which the arrangement and the number are changed for ADM using the same multiplexing device (the same functional blocks as in FIG. 6 in FIG. 10 are given the same reference numerals). In the following description, only portions different from the previous multiplexing device will be described.

  Since the high-speed signal transmission / reception unit 11 is used so that the ADMs connect the ADMs through a high-speed transmission path (see FIG. 11), the WEST side 11-1 and the EAST side 11-2 are connected to the ADMs on both sides. The two high-speed signal transmission / reception units 11 are provided. In order to perform the main signal processing, the high-speed signal transmission / reception units 11-1 and 11-2 and the low-speed signal transmission / reception units 10-1 to M1 are connected or the high-speed signal transmission / reception unit 11 is connected. -1 and 11-2 can be connected to each other, a main signal insertion / separation unit 105 is added between the high-speed signal transmission / reception units 11-1 and 11-2 and the main signal demultiplexing / conversion unit 100.

  Further, in the present ADM, the overhead switch unit 200 of the overhead processing unit 300 receives data from one (for example, EAST side) from the high-speed signal transmission / reception unit via the overhead multiplexing unit 130 so that the overhead of the high-speed multiplexed signal also passes. A configuration in which the overhead to be passed is selectively edited, transmitted to the other (for example, the west side) high-speed signal transmission / reception unit via the overhead separation unit 120, and inserted into the designated byte of the overhead of the high-speed multiplexed signal It was.

  Furthermore, when the information about the B2 byte is included in the overhead passed between the high-speed multiplexed signals, the LOH insertion unit 40 of the high-speed signal transmission / reception unit 11 performs the LOH of the low-speed signal transmission / reception unit 10 of the previous multiplexing device The error number k obtained by adding the error number i (B2 byte termination result) generated in the reception high-speed transmission path to the received error number j is transmitted as it is without performing the bit inversion operation of the B2 byte as in the insertion unit 80. Made the configuration. In addition, as a configuration for detecting a transmission error in the overhead transmission / reception section, a configuration using a tandem connection described later may be employed.

  Also in this ADM, the control unit 400 indicates the type of overhead to be passed to each functional block and the insertion position, and each functional block edits, selects, and inserts these overheads. . The control device is configured to receive the control information from the network management device 2017 shown in FIG. In other words, the network management device 2017 appropriately indicates the overhead type to be passed to each ADM and the position to be inserted so that no collision or contradiction occurs, so that the overhead is transmitted to the transmission device in the network like the main signal. It was set as the structure which transmits / receives freely between.

  As described above, even in the ADM and the transmission network or transmission system using the ADM shown in this embodiment, according to the present invention, the overhead can be passed through any transmission device and used between any transmission devices. Therefore, it is possible to provide a flexible and easy-to-use transmission system that does not cause a change in the monitoring and maintenance operation capability due to a change in the system configuration, that is, has an excellent monitoring and maintenance operation capability.

  In the following, with respect to a configuration for detecting a transmission error that occurs in a transmission section between transmission devices that transmit and receive overhead, another embodiment different from the configuration described in the above embodiment will be described. This is a configuration of a transmission system using SONET or SDH that uses a tandem connection standardized by ANSI or ITU-T to notify a transmission error that has occurred in a receiving transmission device from an overhead transmission transmission device. This is equivalent to passing the B2 byte in the transmission apparatus. Therefore, any configuration may be used in the multiplexing apparatus and ADM described above.

  FIG. 12 is an operation explanatory diagram illustrating a configuration for detecting a transmission error using a tandem connection. FIG. 2A shows this configuration, and FIG. 2B shows a configuration for detecting a transmission error described in the previous multiplexer and ADM. FIG. 13 is a network configuration diagram showing a configuration of a transmission network using a tandem connection. Hereinafter, a configuration for detecting a transmission error using a tandem connection according to the present invention will be described using these drawings, in comparison with the embodiments described so far.

  In the embodiment described so far, as shown in FIG. 12B, in order to detect the error in the transmission section using the B2 byte between other transmission apparatuses by passing the B2 byte in a certain transmission apparatus. In the transmission device that passes the B2 byte, the transmission device transmits the termination of the B2 byte in the line section, the detection of the error number i, the addition of the error number j notified from the transmission source device, and the transmission of the added error number k. Overhead transmission is performed by inverting the B2 byte bits generated by the final transmission device by the number of errors finally added by the final transmission device that passes the overhead (k ′ in the figure). In this configuration, the transmission error is notified from the transmission device to the reception transmission device.

   In a transmission system using SONET or SDH, path management is basically performed between a transmission source and a reception destination. However, as shown in FIG. 13, the transmission apparatus 4000-1 of the transmission source and the reception destination When the path to the transmission device 4000-2 extends over networks with different management sources (in this embodiment, the network management areas 1 to 3), the path is managed for each management area, Need to be specified, ANSI standard T1.150 and ITU-T standard G.264. In 707, a management method is defined by defining a section continuously connected by a line with a plurality of transmission apparatuses up to the boundary (both ends) of the management area as a tandem connection. Specifically, one of a plurality of path overheads POH included in the payload shown in the frame configuration diagram of FIG. 1 is used, and for transmission errors, B3 for detecting a path error in the third row is detected. The transmission error of the tandem connection is managed using the byte and the Z5 byte which is the management byte of the tandem connection in the ninth line. As an example, the transmission error detection of the tandem connection in the management area 1 will be described. The transmission apparatus 4001 monitors the number of errors l generated in the path from the transmission source transmission apparatus 4000-1 to the transmission apparatus 4001 using the B3 byte, and this error is monitored. The number is inserted into the Z5 byte and transmitted to the transmission device 4002. The transmission apparatus 4002 again monitors the number of errors l ′ generated in the path from the transmission source transmission apparatus 4000-1 to the transmission apparatus 4002 using the B3 byte, and subtracts the number of errors l received in the Z5 byte from the number of errors l ′. By doing so, the number of errors generated in the tandem connection is managed.

  The configuration for detecting a transmission error occurring in a transmission section between transmission apparatuses that transmit and receive overhead described in this embodiment is the first transmission that passes the overhead of a low-speed multiplexed signal, as shown in FIG. The device 2030 is regarded as the transmission device at the entrance of the tandem connection, the last transmission device 2032 that passes the overhead of the low-speed multiplexed signal is regarded as the termination transmission device of the tandem connection, and the B3 byte and the Z5 byte as described above are used. In this configuration, the number of errors is transmitted using the tandem connection management method used.

  Specifically, in the transmission apparatus 2030, the number of errors (j) detected after termination of the B2 byte of the low-speed multiplexed signal is encoded and inserted into the designated byte in the overhead area of the high-speed multiplexed signal, as in the above-described embodiment. Then, the data is transmitted to the transmission line on the transmission apparatus side (3001, 3002). Further, the transmission apparatus 2030 checks the B3 byte as described above, and transmits the number of errors (l) in the path generated up to the transmission apparatus in the Z5 byte (3003).

  In the transmission apparatus 2031 in the middle of passing the overhead, only the number of received errors is passed (3004, 3002), and B2 detected on the line between the transmission apparatuses as in the previous embodiment (see FIG. 12B). The number of errors (i) is not added. Of course, the B2 byte termination process (error detection on the receiving side and parity generation on the transmitting side) is performed as usual (standard), but is performed independently of the overhead passing process described in this embodiment. In addition, since the B3 byte and the Z5 byte need only be checked between paths, the transmission apparatus simply passes it as a main signal and does not require other processing (such as checking the number of errors).

  The transmission apparatus 2032 extracts the number of errors (j) sent from the transmission apparatus 2030 (3004). Further, as described above, the B3 byte is checked again, and the received value (l) of the Z5 byte is subtracted from the number of errors (l ′) in the path generated up to this transmission apparatus, and the transmission apparatuses 2030 to 2032 are subtracted. The number of transmission line errors (l′−l: the number of errors equal to i + i ′ in FIG. 12B) occurring in the transmission line (tandem connection) is determined (3005). Then, the number of received errors (j) and the calculation result (l′−l) are added in the same manner as in the above-described embodiment, and the number of errors generated in the transmission section from the transmission apparatus on the transmission side to this transmission apparatus (k ') Is obtained (3001), and the generated B2 parity bit is inverted by this k' and transmitted to the receiving side transmission apparatus 2033 (3006).

  Even in the configuration and method as described above, it is the same as the case where the B2 byte is passed in the intermediate transmission apparatus as in the previous embodiment, and transmission errors occurring in the transmission section between the transmission apparatuses that transmit and receive overhead are transmitted to the partner apparatus. It becomes possible to convey. In addition, according to this configuration, it is not necessary to perform arithmetic processing in the transmission apparatus in the middle of passing overhead, and only the first and last transmission apparatuses need to perform arithmetic processing. Therefore, in a section where there are many transmission apparatuses that pass overhead. Will reduce the amount of hardware. Whether to use the above-described configuration (FIG. 12B) or the present configuration (FIG. 12A) may be selected according to the scale of the network or system.

  As described above, by constructing a transmission network with a multiplexing device or ADM having the function of passing the overhead according to the present invention, the monitoring / maintenance operation capability is changed by changing the network configuration as in the conventional transmission system. There is no. Since any overhead can be transmitted / received between any transmission apparatuses in the transmission network, a flexible transmission network having excellent monitoring and maintenance operation capability can be easily realized. Specifically, a call by a maintenance person's voice can be performed by transmitting / receiving order wires E1 and E2 between arbitrary transmission apparatuses. In addition, by transmitting and receiving the data communication channels D1 to D12, various settings of the transmission apparatus can be made, and the configuration can be easily changed and a flexible transmission network can be constructed. In particular, in SONET, D1-12 is transmitted from a network management device or the like to set each transmission device. However, if a configuration that allows a transmission device on the way like the present invention to pass is used, a conventional device is used. Then, it becomes possible to easily send the data necessary for setting up to the target transmission device without performing complicated processing involving the control unit of the transmission device such as once terminating and transmitting again for each transmission device, It is extremely effective for the maintenance and management of transmission networks. Furthermore, transmission / reception of transmission path switching control bytes K1 and K2 makes it possible to perform transmission path selection consistent between transmission apparatuses, so that a network configuration in the event of a transmission path failure can be quickly established. It can be changed and reconfigured, and is effective for maintenance and management of the transmission network. As for transmission errors, the B2 byte cannot be directly transferred between the transmission devices, but since the number of errors that have occurred is detected and reliably notified, the transmission device is in the middle between transmission devices. Therefore, it is possible to manage the error rate in the transmission section equivalent to the case where B2 bytes are transmitted and received when directly connected. Of course, other overheads shown in FIG. 3 can be used for monitoring and maintenance operations between transmission apparatuses by transferring them in the same manner as the overhead described above.

Further, in the present invention, an unused byte in the overhead area of the multiplexed signal specified by the above-described standard is selected, and the overhead that allows the transmission apparatus to pass is inserted into the selected unused byte for transmission. It is a configuration. That is, it is possible to transmit / receive after determining the byte to be used in advance in the transmission network or system, or to change the setting of the byte to be used by using the data communication channel described above, and to transmit / receive, As long as there are empty bytes, the transmission network can be set freely according to the number of data and the amount of monitoring and maintenance operation information, so even if the network configuration or monitoring and maintenance operation method changes or future standards change It is possible to provide a transmission apparatus and a transmission network that can flexibly cope with the situation and have excellent monitoring and maintenance capability.

It is a frame block diagram which shows the structure of a low-speed multiplexed signal (OC-12). It is a frame block diagram which shows the structure of a high-speed multiplexed signal (OC-192). It is a function explanatory drawing which shows the function of the overhead of a multiplexed signal. It is a network block diagram explaining the structure of a transmission network, and an overhead process area. It is a block block diagram which shows the structure of the transmission apparatus (multiplexing apparatus) by this invention. Similarly, it is an overhead configuration diagram for explaining how overhead passes. Similarly, it is an overhead configuration diagram for explaining how overhead passes. It is operation | movement explanatory drawing which shows the calculation area | region of overhead (B2 byte). It is a network block diagram which shows the structure of the transmission network using the transmission apparatus by this invention. It is a block block diagram which shows the structure of another transmission apparatus (ADM) by this invention. Similarly, it is a network block diagram which shows the structure of the transmission network which uses another transmission apparatus. It is operation | movement explanatory drawing explaining the structure of the transmission error detection using the tandem connection in the transmission network using the transmission apparatus by this invention. Similarly, it is a network block diagram which shows the structure of the transmission network using a tandem connection.

Explanation of symbols

10-1 to M: Low-speed signal transmission / reception processing unit,
11: High-speed signal transmission / reception processing unit,
20-1 to M: low-speed signal section overhead termination,
30-1 to M: low-speed signal line overhead termination,
40: High-speed signal line overhead insertion part,
50 ... High-speed signal section overhead insertion part,
60 ... high-speed signal section overhead termination,
70: High-speed signal line overhead termination,
80-1 to M: Low-speed signal line overhead insertion part,
90-1 to M: Low-speed signal section overhead insertion part,
100 ... main signal demultiplexing / conversion unit, 105 ... main signal insertion / separation unit,
110, 130 ... overhead multiplexing unit,
120, 140: Overhead separation unit, 200, 210: Switch unit 300: Overhead processing unit, 400: Control unit 1000-1004, 1100-1107: Passing overhead,
1200 to 1208 ... passing overhead,
2000 to 2033 ... transmission device,
3000 to 3006 ... transmission error processing unit,
OC-12, OC-192 ... multiplexed transmission line.

Claims (4)

An optical signal connected to the first optical transmission line and the second optical transmission line and having an overhead for storing maintenance information whose use is defined in accordance with the regulations of SONET or SDH in an area defined by the regulations. In the optical transmission device that relays from the optical transmission line to the second optical transmission line,
Means for extracting maintenance information for any application included in the overhead of the optical signal received from the first optical transmission line;
Means for storing the extracted arbitrary maintenance information in an area of the overhead of the optical signal transmitted through the second optical transmission line, in which information to be stored is not determined in advance by the rules;
Means for generating maintenance information of the same use as the extracted arbitrary maintenance information;
Means for storing the generated maintenance information in a region in an overhead of an optical signal transmitted through the second optical transmission line, which is defined by the regulation so as to store the maintenance information. Optical transmission equipment. An optical signal connected to the first optical transmission line and the second optical transmission line, and having overhead for storing maintenance information determined for use in a region defined by the rule according to the rule of SONET or SDH; In an optical transmission device relaying from two optical transmission lines to the first optical transmission line,
Means for extracting the maintenance information from the area defined by the regulation out of the overhead of the optical signal received from the second optical transmission line;
Means for processing the extracted maintenance information in accordance with the use defined by the regulations;
Means for extracting the maintenance information stored in an area in which information to be stored is not predetermined by the rules out of the overhead of the optical signal received from the second optical transmission line;
Means for storing the extracted maintenance information in an area defined by the regulation so as to store the maintenance information in an overhead of an optical signal transmitted through the first optical transmission line. Optical transmission equipment.   The information to be stored, which is connected to the optical transmission device according to claim 1 or 2 via a network and stores or extracts the maintenance information with respect to the optical transmission device, is determined in advance by the rules. A management apparatus characterized by indicating an area that is not provided. In the management device according to claim 3,
A management apparatus that instructs maintenance information to be stored or extracted in an area in which information to be stored is not determined in advance by the rules to the optical transmission apparatus.

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