JP5533433B2 - Transmission device with uninterruptible switching function and transmission path uninterrupted switching method - Google Patents

Description

  The present invention relates to a transmission apparatus and a transmission path uninterruptible switching method provided with an uninterruptible switching function for performing uninterrupted switching of a transmission path of a low-order path in an SDH / SONET transmission system.

  In an SDH / SONET (Synchronous Digital Hierarchy / Synchronous Optical Network) transmission system, when a transmission apparatus is connected to a PDH transmission apparatus that performs communication using a PDH (Plesiochronous Digital Hierarchy) signal, the SDH / SONET transmission apparatus performs PDH transmission. Multiple communications transmitted from the apparatus are multiplexed, and multiplexed SDH signals are transmitted through multiple transmission paths. In the transmission of the multiplexed SDH signal, when an error is detected on the transmission path, the transmission apparatus preferably switches the transmission path of the received SDH signal in the original communication unit before multiplexing.

  FIG. 6 is a block diagram illustrating a configuration of a transmission unit of a transmission apparatus in a general SDH / SONET transmission system. FIG. 7 is a block diagram illustrating a configuration of a receiving unit of a transmission apparatus in a general SDH / SONET transmission system. A configuration example of a transmission apparatus in a general SDH / SONET transmission system will be described with reference to FIGS. 6 and FIG. 7, the PDH signal is transmitted through a low-order path such as a VC (Virtual Container) -11 path, a VC-12 path, or a VC-2 path.

  In the transmission unit 401, for example, the reception interface unit 110 receives a PDH signal from a PDH transmission device (not shown). The OH insertion unit 120 adds POH (Path OverHead) to the received PDH signal and then maps it to the SDH signal. The low-order path POH includes a V5 byte 121, a J2 byte 122, an N2 byte 123, and a K4 byte 124. The OH insertion unit 120 inserts the data generated by the path trace function generation unit 140, the tandem connection function generation unit 141, and the switching control function generation unit 142 into the POH. Thereafter, the PDH signal to which POH is added is multiplexed with the SDH signal and output to the branching unit 150. The SDH signal output to the branching unit 150 is branched and sent from the transmission interface units 160 and 161 to different transmission paths.

  In the reception unit 402, for example, the reception interface units 210 and 211 receive the SDH signal via different transmission paths. The OH extraction unit 220 extracts data from the POH of the low-order path signal in the SDH signal received by the reception interface unit 210, and sends the data to the path trace function extraction unit 240, the tandem connection function extraction unit 241, and the switching control function extraction unit 242. Output the extracted data. Then, the OH extraction unit 220 outputs the received signal to the selection unit 260.

  The OH extraction unit 225 extracts data from the POH of the low-order path signal in the SDH signal received by the reception interface unit 211, and sends the data to the path trace function extraction unit 245, the tandem connection function extraction unit 246, and the switching control function extraction unit 247. Output the extracted data. Then, the OH extraction unit 225 outputs the received signal to the selection unit 260.

  The selection unit 260 selects one of the two signals input from the OH extraction units 220 and 225. The transmission interface unit 270 demaps the signal selected by the selection unit 260 to a PDH signal, and sends the demapped PDH signal to a PDH transmission device (not shown) connected to the transmission device.

  In such a transmission apparatus, when the line quality of a signal reception target transmission line (active transmission line) deteriorates, the reception target is set to the other transmission line (standby line) so that the continuity of the signal is not impaired. By switching to (transmission path), non-instantaneous switching of the transmission path is realized.

  Many triggers for switching the transmission path without instantaneous interruption are mixing errors on the transmission path. As an error detection function for detecting an error mixture on a transmission line, ITU-T Recommendation G. In 707, BIP (Bit Interleaved Parity) -8 is defined in the case of a high-order path, and BIP-2 is defined in the case of a low-order path. Patent Document 1 describes a transmission apparatus that performs high-speed path transmission line uninterrupted switching in an SDH / SONET transmission system.

  In the transmission unit of the transmission apparatus described in Patent Literature 1, the multi-frame identification data is added to the high-order path POH and the SDH signal is transmitted. In the receiving unit of the transmission apparatus described in Patent Document 1, the received signal is temporarily stored in the delay memory, and the multi-frame synchronization is performed based on the multi-frame identification data inserted into the high-order path POH. Performs non-instantaneous switching of the transmission path of the next path.

  Patent Document 2 discloses that an SDH signal is transmitted by adding multi-frame identification data to a higher-order path POH on the transmission side, and a multi-frame based on the multi-frame identification data inserted in the higher-order path POH on the reception side. A transmission system is described that performs synchronization and non-instantaneous transmission line switching using a parity calculation result set in the B3 byte in the POH of the higher-order path.

JP 2004-186980 A (paragraphs 0010-0012) Japanese Patent Laying-Open No. 2005-260820 (paragraphs 0038-0040)

  Japanese Patent Laid-Open No. 2004-228561 describes performing transmission line uninterruptible switching using multiframe identification data set in a delay memory and POH, but describes what triggers transmission line switching. It has not been. Patent Document 2 describes that an error is detected using a parity operation result set in POH as a trigger for transmission path switching, but the object of switching is a high level such as a VC-4 path. Next pass.

  Therefore, the present invention provides a transmission apparatus capable of surely performing uninterruptible switching to a transmission path having a better line quality for a low-order path in a transmission system having a first transmission path and a second transmission path. It is an object of the present invention to provide a transmission line uninterrupted switching method.

  The transmission apparatus according to the present invention is a transmission apparatus that transmits an SDH signal multiplexed with a PDH signal to two transmission lines, and includes multiframe identification data and path overhead added when mapping the PDH signal to the SDH signal. Data setting means for setting a BIP-8 calculation result based on a low-order path signal and BIP-8 calculation for a low-order path signal received via the first transmission path of the two transmission paths A first line quality determining means for determining the line quality by comparing the BIP-8 calculation result obtained by executing the BIP-8 calculation result set in the path overhead, and two transmission paths The BIP-8 calculation result obtained by executing the BIP-8 calculation on the low-order path signal received via the second transmission path and the path overhead are set. A second channel quality judging means for judging the channel quality by comparing the IP-8 operation result, a signal received via the first transmission path and a signal received via the second transmission path; Synchronizing means for outputting in synchronization using multi-frame identification data set in the path overhead, and selecting one of the signals output by the synchronizing means, the first line quality determining means and the second line A selection means for switching a signal to be selected to the other signal when the line quality determination means corresponding to the selected signal of the quality determination means detects deterioration of the line quality. Features.

  According to the present invention, the transmission path uninterruptible switching method sets multi-frame identification data and a BIP-8 calculation result based on a low-order path signal in a path overhead added when mapping a PDH signal to an SDH signal. BIP-8 calculation result obtained by executing BIP-8 calculation on a low-order path signal sent to two transmission paths and received via the first transmission path of the two transmission paths; A first line quality determination process is performed to determine the line quality by comparing with the BIP-8 calculation result set in the path overhead, and the signal is received via the second transmission path of the two transmission paths. By comparing the BIP-8 operation result obtained by executing the BIP-8 operation on the signal of the low-order path with the BIP-8 operation result set in the path overhead, the line quality is improved. Second line quality determination processing is performed, and the signal received via the first transmission path and the signal received via the second transmission path are converted into multi-frame identification data set in the path overhead. One of the outputted signals is selected, and the one corresponding to the selected signal in the first line quality determination process and the second line quality determination process is selected. When deterioration of the line quality is detected in the line quality determination process, the signal to be selected is switched to the other signal.

  According to the present invention, in a transmission system having a first transmission path and a second transmission path, it is possible to reliably perform uninterruptible switching to a transmission path with a better line quality for a low-order path.

It is a block diagram which shows the structural example of the transmission system which can apply the transmission apparatus by this invention. It is a block diagram which shows the structure of the transmission part of the transmission apparatus shown in FIG. It is a block diagram which shows the structure of the receiving part of the transmission apparatus shown in FIG. It is explanatory drawing which shows the example of a frame structure of VC. It is a block diagram which shows the principal part of the transmission apparatus by this invention. It is a block diagram which shows the structure of the transmission part of the transmission apparatus in a general SDH / SONET transmission system. It is a block diagram which shows the structure of the receiving part of the transmission apparatus in a general SDH / SONET transmission system.

  FIG. 1 is a block diagram showing a configuration example of a transmission system to which a transmission apparatus according to the present invention can be applied. FIG. 2 is a block diagram illustrating a configuration of a transmission unit of the transmission apparatus illustrated in FIG. FIG. 3 is a block diagram illustrating a configuration of a reception unit of the transmission apparatus illustrated in FIG. With reference to FIGS. 1-3, the structure of the transmission apparatus of this embodiment is demonstrated. In the transmission apparatus shown in FIGS. 1 and 2, the PDH signal is transmitted through a low-order path such as a VC-11 path, a VC-12 path, or a VC-2 path.

  A transmission apparatus 100 illustrated in FIG. 1 includes a transmission unit 101 and a reception unit 102. The transmission apparatus 200 includes a transmission unit 201 and a reception unit 202. The transmission apparatus 100 and the transmission apparatus 200 are opposed to each other via transmission lines 301 and 302 and transmit an SDH signal. Further, a PDH transmission device (not shown) that transmits and receives PDH signals is connected to the transmission devices 100 and 200.

  The configuration of the transmission unit 101 will be described with reference to FIG. The transmission unit 101 adds POH to the PDH signal received by the transmission apparatus 100 from the PDH transmission apparatus, maps it to the SDH signal, branches the SDH signal, and transmits it via different transmission paths 301 and 302. Send to device 200.

  The transmission unit 101 includes a reception interface unit 110, an OH insertion unit 120, an insertion control unit 130, a path trace function generation unit 140, a tandem connection function generation unit 141, a switching control function generation unit 142, a multiframe generation unit 143, and a BIP-8. A calculation unit 144, a branching unit 150, and transmission interface units 160 and 161 are provided.

  The reception interface unit 110 receives an SDH signal. The reception interface unit 110 outputs the received SDH signal to the OH insertion unit 120.

  FIG. 4 is an explanatory diagram showing an example of a VC frame configuration. The VC configuration shown in FIG. This is a frame configuration of VC-11, VC-12, and VC-2 defined by 707. The bytes V5, J2, N2, and K4 in the VC POH shown in FIG. 4 correspond to the V5 byte 121, J2 byte 122, N2 byte 123, and K4 byte 124 shown in FIG.

  The OH insertion unit 120 adds POH (including overhead bytes of V5 byte 121, J2 byte 122, N2 byte 123, and K4 byte 124) to the PDH signal input from the reception interface unit 110. The OH insertion unit 120 sets predetermined data in an overhead byte according to the control of the insertion control unit 130. Thereafter, the PDH signal to which POH is added is multiplexed with the SDH signal and output to the branching unit 150.

  The insertion control unit 130 converts the data input from the mapping path trace function generation unit 140, the tandem connection function generation unit 141, the switching control function generation unit 142, the multiframe generation unit 143, and the BIP-8 calculation unit 144 into POH overhead. Controls which byte of a byte is inserted. The insertion control unit 130 includes the data input from the mapping path trace function generation unit 140, the tandem connection function generation unit 141, the switching control function generation unit 142, the multiframe generation unit 143, and the BIP-8 calculation unit 144, and the data thereof. Is output to the insertion control unit 130 as to which overhead byte is set.

  The path trace function generation unit 140 generates data for the path trace function. The tandem connection function generation unit 141 generates data for the tandem connection function. The switching control function generation unit 142 generates data used for low-order path switching control. For example, the data used for low-order path switching control includes data that can specify where in the data frame the data from which low-order path is stacked. The multiframe generation unit 143 generates multiframe identification data (hereinafter referred to as multiframe). The multiframe generated by the multiframe generator 143 can be used by the receiver 102 to synchronize the SDH signal. Data generated by the mapping path trace function generation unit 140, the tandem connection function generation unit 141, the switching control function generation unit 142, and the multiframe generation unit 143 is output to the insertion control unit 130.

  The BIP-8 operation unit 144 performs BIP-8 error monitoring operation on the low-order path signal output from the OH insertion unit 120. BIP-8 is a parity check method used for monitoring errors in higher-order paths and sections, and generally has higher monitoring accuracy than BIP-2 used in lower-order paths. Data indicating the calculation result of the error monitoring calculation by the BIP-8 calculation unit 144 is output to the insertion control unit 130 as error monitoring data.

  The insertion control unit 130 determines in which overhead byte of the POH the multiframe generated by the multiframe generation unit 143 and the error monitoring data are to be inserted. As an example, when the tandem connection function is not used, it is determined to be inserted into the N2 byte. In addition, it is determined to insert the multiframe into an empty bit of K4 bytes.

  The branching unit 150 branches the SDH signal input from the OH insertion unit 120 and outputs the branched SDH signal to the transmission interface units 160 and 161.

  The transmission interface units 160 and 161 send the SDH signal input from the branching unit 150 to the transmission paths 301 and 302, respectively. For example, the transmission interface unit 160 transmits an SDH signal to the transmission path 301. The transmission interface unit 161 sends an SDH signal to the transmission path 302.

  The configuration of the receiving unit 102 will be described with reference to FIG. The receiving unit 102 receives an SDH signal from the transmission apparatus 200 via different transmission paths 301 and 302. Then, the SDH signal is demapped to the PDH signal and sent to the PDH transmission apparatus.

  The reception unit 102 includes reception interface units 210 and 211, OH extraction units 220 and 225, extraction control units 230 and 231, path trace function generation units 240 and 245, tandem connection function generation units 241 and 246, and a switching control function generation unit 242. 247, multi-frame generation units 243 and 248, BIP-8 operation units 244 and 249, uninterruptible switching unit 250, selection unit 260, and transmission interface units 270 and 271.

  Each of the reception interface units 210 and 211 receives the SDH signal via one of the transmission lines 301 and 302. For example, the reception interface unit 210 outputs the SDH signal received from the transmission path 301 to the OH extraction unit 220. The reception interface unit 211 outputs the SDH signal received from the transmission path 302 to the OH extraction unit 225.

  The OH extraction unit 220 extracts data from the overhead bytes (including the V5 byte 221, the J2 byte 222, the N2 byte 223, and the K4 byte 224) input from the reception interface unit 210. The OH extraction unit 220 outputs the extracted overhead byte data to the extraction control unit 230. The OH extraction unit 220 outputs the signal input from the reception interface unit 210 to the multiframe synchronization unit 251 and the delay memory 252 of the uninterruptible switching unit 250.

  The extraction control unit 230 converts the data input from the OH extraction unit 220 into a path trace function extraction unit 240, a tandem connection function extraction unit 241, a switching control function extraction unit 242, a multiframe extraction unit 243, and a BIP-8 operation extraction unit. The data is output to the portion of 244 that uses data.

  The path trace function extraction unit 240 extracts data for the path trace function from the data input by the extraction control unit 230. The switching control function extraction unit 242 extracts data used for the low-order path switching control function from the data input by the extraction control unit 230.

  For example, when BIP-8 error monitoring data is set in the N2 byte 221 of the POH in the signal received by the reception interface unit 211, the extraction control unit 230 extracts the N2 byte 221 extracted by the OH extraction unit 220. Is output to the BIP-8 calculation extraction unit 244. When the multiframe is set to K4 byte 224, the extraction control unit 230 outputs the data of the K4 byte 221 extracted by the OH extraction unit 220 to the multiframe extraction unit 243.

  The BIP-8 calculation extraction unit 244 extracts error monitoring data inserted at the SDH signal transmission source from the data input by the extraction control unit 230. The BIP-8 calculation extraction unit 244 performs BIP-8 calculation on the received low-order path signal. Then, the BIP-8 calculation extraction unit 244 compares the extracted error monitoring data with the calculation result, and a transmission path error (error) occurs in the low-order path signal received by the reception interface unit 210. Judge whether it is. The BIP-8 calculation extraction unit 244 outputs the error monitoring determination result to the selection unit 260. The multiframe extraction unit 243 detects the multiframe phase from the data input by the extraction control unit 230. The multiframe extraction unit 243 outputs the detection result of the multiframe phase to the multiframe synchronization unit 251.

  The OH extraction unit 225 extracts data from the overhead bytes (including V5 byte 226, J2 byte 227, N2 byte 228, and K4 byte 229) input from the reception interface unit 211. The OH extraction unit 225 outputs the extracted overhead byte data to the extraction control unit 231. Then, the OH extraction unit 225 outputs the signal input from the reception interface unit 211 to the multiframe synchronization unit 253 and the delay memory 254 of the uninterruptible switching unit 250.

  The extraction control unit 231 converts the data input from the OH extraction unit 220 into a path trace function extraction unit 245, a tandem connection function extraction unit 246, a switching control function extraction unit 247, a multiframe extraction unit 248, and a BIP-8 operation extraction unit. The data is output to the portion of H.249 that uses the data. The functions of the path trace function extracting unit 245, the tandem connection function extracting unit 246, the switching control function extracting unit 247, the multiframe extracting unit 248, and the BIP-8 operation extracting unit 249 are respectively the path trace function extracting unit 240 and the tandem connection function. The functions of the extraction unit 241, the switching control function extraction unit 242, the multiframe extraction unit 243, and the BIP-8 calculation extraction unit 244 are the same.

  The uninterruptible switching unit 250 includes multiframe synchronization units 251 and 253, delay memories 252 and 254, and a delay control unit 255. The uninterruptible switching unit 250 matches the multi-frame phases of the low-order path signals input from the OH extraction unit 220 and the OH extraction unit 225. The uninterruptible switching unit 250 transmits a low-order path signal in which the multiframe phases are matched to the selection unit 260.

  The multiframe synchronization unit 251 outputs multiframe phase information for the signal input from the OH extraction unit 220 to the delay control unit 255 based on the detection result of the multiframe phase detected by the multiframe extraction unit 243. The multiframe synchronization unit 253 outputs multiframe phase information for the signal input from the OH extraction unit 225 to the delay control unit 255 based on the detection result of the multiframe phase detected by the multiframe extraction unit 248.

  The delay memory 252 temporarily accumulates the signal output from the OH extraction unit 220. The delay memory 254 temporarily accumulates the signal output from the OH extraction unit 225. The signals stored in the delay memories 252 and 254 are output to the selection unit 260 according to the delay control by the delay control unit 255.

  Based on the two pieces of multiframe phase information input from the multiframe synchronization units 251 and 253, the delay control unit 255 delays the delay memories 252 and 254 so that the multiframe phases of the signals read from the delay memories 252 and 254 match. The delay amount of the signal stored in H.254 is controlled (delay control). For example, the delay control unit 255 adjusts the output timing of each signal stored in the delay memories 252 and 254 by delay control. For delay control of the signal delay amount by the delay control unit 255, control generally used as signal synchronization control using multiframe phase information can be used.

  Then, the delay control unit 255 outputs the signals stored in the delay memories 252 and 254 to the selection unit 260 at the adjusted output timing. As a result, the delay memories 252 and 254 absorb the delay difference between the two signals, and the two signals output to the selection unit 260 are in a state in which the multiframe phases are synchronized.

  The selection unit 260 receives two signals (a signal based on an SDH signal received via the transmission line 301 and a signal based on the SDH signal received via the transmission line 301) received from the uninterruptible switching unit 250 according to a predetermined transmission line switching condition. Of the SDH signal) is selected. Note that the predetermined transmission path switching conditions are, for example, the error monitoring determination result by the BIP-8 operation extraction unit 244 for the SDH signal received by the reception interface unit 210 and the BIP-8 for the SDH signal received by the reception interface unit 211. It is determined based on the error monitoring determination result by the operation extraction unit 249.

  For example, when the selection unit 260 selects and outputs a signal received via the transmission path 301 (specifically, when the output of the delay memory 252 is selected), the BIP-8 When the judgment result of error monitoring by the operation extraction unit 244 indicates deterioration of channel quality (for example, lower than a predetermined threshold value), a signal received via the transmission path 302 is selected. Switch to the output state. The selection unit 260 selects and outputs a signal received via the transmission path 302 (specifically, when selecting the output of the delay memory 254), the BIP-8. When the judgment result of error monitoring by the operation extraction unit 248 indicates deterioration of channel quality (for example, lower than a predetermined threshold value), a signal received via the transmission line 301 is selected. Switch to the output state. As a result, the selection unit 260 can switch the transmission path of the SDH signal received from the opposite transmission apparatus 200 to a transmission path where there is a high possibility that no error is detected. The predetermined transmission path switching condition may be determined according to existing control other than the error monitoring determination result by the BIP-8 calculation extraction units 244 and 249.

  The transmission interface unit 270 demaps the signal selected by the selection unit 260 to the PDH signal, and transmits the demapped PDH signal to the PDH transmission apparatus.

  As described above, in this embodiment, the transmission unit 101 of the transmission apparatus 100 adds a multiframe to the overhead byte added when mapping the PDH signal to the SDH signal with respect to the PDH signal received from the PDH transmission apparatus. The SDH signal is transmitted to the transmission apparatus 200 via different transmission paths 301 and 302. The receiving unit 202 of the transmission apparatus 200 synchronizes the multiframe extracted from the low-order path POH with respect to the low-order path signal received from the transmission apparatus 100 via the different transmission paths 301 and 302, Delay control is performed so that the phases match. As a result, it is possible to switch the transmission path of the low-order path without causing a momentary interruption (for example, switching the transmission line from the transmission line 301 to the transmission line 302 without a momentary interruption).

  In the present embodiment, in the receiving unit 102, the BIP-8 operation extraction units 244 and 249 perform error monitoring by BIP-8 using error monitoring data extracted from the low-order path POH. The accuracy of error monitoring can be improved as compared with error monitoring by BIP-2 defined for the next path.

  Further, in such a transmission apparatus, since the error monitoring accuracy is improved by the error monitoring calculation by BIP-8 as described above, the transmission path error can be detected more reliably. The selection unit 260 can reliably perform non-instantaneous switching to a transmission path having a better line quality for a low-order path.

  In this embodiment, the instantaneous switching of the low-order path is realized using the BIP-8 calculation result set in the POH of the low-order path. However, the low-order path of the low-order path is combined with the BIP-2 calculation result. Non-instantaneous switching may be realized. For example, either the line quality determination result based on the BIP-8 calculation or the line quality determination result based on the BIP-2 calculation set in the V5 byte is determined by deterioration of the line quality (for example, predetermined). When it indicates that the threshold value is lower than the threshold value, the selection unit 260 performs switching.

  Further, such a transmission apparatus is configured to include a common function arrangement with a transmission apparatus (for example, the transmission apparatus shown in FIGS. 6 and 7) in a general SDH / SONET transmission system. With respect to the transmission apparatus for the SDH / SONET transmission system, the function can be easily expanded to a transmission apparatus that supports non-instantaneous switching of a low-order path.

  FIG. 5 is a block diagram showing a main part of the transmission apparatus according to the present invention. As shown in FIG. 5, the transmission device 10 (e.g., corresponding to the transmission device 100 shown in FIG. 1) is a transmission device that sends an SDH signal multiplexed with a PDH signal to two transmission paths, and transmits the PDH signal. Data setting means 11 (for example, a multi-frame generating unit 143 shown in FIG. 2) sets multi-frame identification data and a BIP-8 calculation result based on a low-order path signal in a path overhead added when mapping to an SDH signal. , BIP-8 operation unit 144, OH insertion unit 120, and insertion control unit 130) and the first transmission path (for example, transmission path 301 shown in FIG. 1) of the two transmission paths. The BIP-8 operation result obtained by executing the BIP-8 operation on the low-order path signal is compared with the BIP-8 operation result set in the path overhead. The first line quality determining means 12 (for example, equivalent to the BIP-8 calculation extracting unit 244 shown in FIG. 3) and the second transmission path (for example, in FIG. BIP-8 operation result obtained by executing BIP-8 operation on the signal of the low-order path received via the transmission path 302 shown in FIG. 5 and the BIP-8 operation result set in the path overhead The second channel quality determination means 13 (for example, equivalent to the BIP-8 calculation extraction unit 249 shown in FIG. 3), and the signal received via the first transmission path and the first channel quality determination means 13 for determining the channel quality by comparing Synchronizing means 14 (for example, equivalent to the uninterruptible switching unit 250 shown in FIG. 3) that synchronizes and outputs a signal received via two transmission paths using multiframe identification data set in the path overhead. ) One of the signals output from the synchronizing means 14 is selected, and the line corresponding to the selected signal of the first line quality judging means 12 and the second line quality judging means 13 is selected. When the quality determination unit detects deterioration of the line quality, the selection unit 15 (for example, corresponding to the selection unit 260 shown in FIG. 3) that switches the signal to be selected to the other signal is provided.

  Further, in the above embodiment, transmission apparatuses as shown in the following (1) to (3) are also disclosed.

(1) The synchronization means 14 receives a first delay memory (for example, equivalent to the delay memory 252 shown in FIG. 3) that delays a signal received via the first transmission path, and a second transmission path. The second delay memory (for example, corresponding to the delay memory 254 shown in FIG. 3) that delays the received signal, and the multi-frame identification data set in the path overhead, the signal output timing of the first delay memory and the second delay A transmission apparatus including a delay control unit (e.g., corresponding to the delay control unit 255 shown in FIG. 3) that synchronizes the signal output timing of the memory.

(2) The data setting means 11 is a transmission apparatus that sets multiframe identification data and BIP-8 calculation results in empty overhead bytes in the path overhead (for example, realized by the operation of the insertion control unit 130).

(3) A transmission apparatus comprising multiplexing means (for example, equivalent to the OH insertion unit 120 shown in FIG. 2) for mapping the PDH signal to the SDH VC-11 path, VC-12 path, or VC-2 path.

  The present invention can be applied to a transmission apparatus connected to a PDH transmission apparatus.

DESCRIPTION OF SYMBOLS 10 Transmission apparatus 11 Data setting means 12 1st line quality determination means 13 2nd line quality determination means 14 Synchronization means 15 Selection means 100,200 Transmission apparatus 101,201,401 Transmission part 102,202,402 Reception part 110 Reception interface part 120 OH Insertion Unit 121 V5 Byte 122 J2 Byte 123 N2 Byte 124 K4 Byte 130 Insertion Control Unit 140 Path Trace Function Generation Unit 141 Tandem Connection Function Generation Unit 142 Switching Control Function Generation Unit 143 Multiframe Generation Unit 144 BIP-8 Operation Unit 150 Branch unit 160, 161 Transmission interface unit 210, 211 Reception interface unit 220, 225 OH extraction unit 221, 226 V5 byte 222, 227 J2 byte 223, 228 N2 byte 224, 229 4 bytes 230, 231 Extraction control unit 240, 245 Path trace function extraction unit 241, 246 Tandem connection function extraction unit 242, 247 Switching control function extraction unit 243, 248 Multiframe extraction unit 244, 249 BIP-8 operation extraction unit 250 None Instantaneous interruption switching unit 251,253 Multi-frame synchronization unit 252,254 delay memory 255 delay control unit 260 selection unit 270 transmission interface unit 301,302 transmission path

Claims (5)

A transmission device for sending an SDH signal multiplexed with a PDH signal to two transmission lines,
Data setting means for setting multi-frame identification data and a BIP-8 calculation result based on a low-order path signal in a path overhead added when mapping a PDH signal to an SDH signal;
The BIP-8 calculation result obtained by executing the BIP-8 calculation on the low-order path signal received via the first transmission path of the two transmission paths and the path overhead are set. First line quality determining means for determining the line quality by comparing the BIP-8 calculation result being present;
A BIP-8 operation result obtained by executing a BIP-8 operation on a low-order path signal received via the second transmission line of the two transmission lines and the path overhead are set. Second line quality determining means for determining the line quality by comparing the BIP-8 calculation result being present;
Synchronizing means for synchronizing and outputting the signal received via the first transmission path and the signal received via the second transmission path using multiframe identification data set in the path overhead When,
One of the signals output from the synchronizing means is selected, and the line quality corresponding to the selected signal of the first line quality judging means and the second line quality judging means is selected. A transmission apparatus comprising: selection means for switching a signal to be selected to the other signal when the determination means detects deterioration of channel quality. The synchronization means is set to a first delay memory for delaying a signal received via the first transmission path, a second delay memory for delaying a signal received via the second transmission path, and a path overhead. The transmission apparatus according to claim 1, further comprising: a delay control unit that synchronizes the signal output timing of the first delay memory and the signal output timing of the second delay memory by using the multiframe identification data. The transmission apparatus according to claim 1 or 2, wherein the data setting means sets the multi-frame identification data and the BIP-8 calculation result in empty overhead bytes in the path overhead. The transmission apparatus according to any one of claims 1 to 3, further comprising multiplexing means for mapping the PDH signal to a VC-11 path, a VC-12 path, or a VC-2 path of SDH. Set the multi-frame identification data and the BIP-8 calculation result based on the low-order path signal in the path overhead added when mapping the PDH signal to the SDH signal, and send it to the two transmission lines.
The BIP-8 calculation result obtained by executing the BIP-8 calculation on the low-order path signal received via the first transmission path of the two transmission paths and the path overhead are set. A first line quality determination process for determining the line quality by comparing the BIP-8 calculation result with
A BIP-8 operation result obtained by executing a BIP-8 operation on a low-order path signal received via the second transmission line of the two transmission lines and the path overhead are set. A second line quality determination process for determining the line quality by comparing the BIP-8 calculation result with
The signal received via the first transmission path and the signal received via the second transmission path are synchronized and output using multiframe identification data set in the path overhead,
One of the outputted signals is selected, and the line is determined by the line quality determination process corresponding to the selected signal of the first line quality determination process and the second line quality determination process. A switching method without instantaneous interruption of a transmission path, characterized in that when quality degradation is detected, the signal to be selected is switched to the other signal.

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