JP2014165818A - Optical transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost optical transmission system.SOLUTION: An optical transmission system 10 includes a plurality of nodes. Each node includes a plurality of transponders, a standby transponder, an OADM unit, and an optical switch disposed between the plurality of transponders and the standby transponder, and a plurality of terminal devices. At normal operation, the standby transponder in each node is connected to standby transponders in all the other nodes one after another. On the occurrence of a failure in a transponder in a certain node, the optical switch in the node of interest switches the connection destination of a terminal device, connected to the transponder of the failure occurrence, to the standby transponder in the certain node. Also, an optical switch in another node, to which an opposite transponder communicating with the transponder of the failure occurrence is subordinate, switches the connection destination of a terminal device, connected to the opposite transponder, to the standby transponder in the other node.

Description

  The present invention relates to an optical transmission system that transmits and receives an optical signal through an optical transmission line.

  2. Description of the Related Art In recent years, with the rapid spread of the Internet, development and introduction of a wavelength division multiplexing (WDM) optical transmission system that transmits optical signals of a plurality of wavelengths all over a single optical fiber is progressing. Currently, the transmission rate per wavelength is mainly 2.4 Gbps to 10 Gbps, but a higher transmission rate such as 40 Gbps has begun to be used in order to meet the ever-increasing information transmission demand (for example, Patent Document 1). reference).

  FIG. 1 shows an example of a conventional WDM optical transmission system. The optical transmission system 100 illustrated in FIG. 1 includes a first node 111A, a second node 111B, a third node 111C, and a fourth node 111D. These four nodes are OADM (Optical Add-Drop Multiplexer) devices and constitute an optical ring network.

  Since the first to fourth nodes 111A to 111D have the same configuration, the configuration of the first node 111A will be described here. The first node 111A includes an OADM unit 112A, first to fourth transponders 113A1 to 113A4, first to fourth spare transponders 114A1 ′ to 114A4 ′, first to fourth terminal devices 116A1 to 116A4, An optical switch 117 and four optical couplers 118 are provided.

  The first to fourth transponders 113A1 to 113A4 respectively convert a light signal having an arbitrary wavelength from the first to fourth terminal apparatuses 116A1 to 116A4 into an optical signal having wavelengths λ1 to λ4 suitable for wavelength multiplexing, It has a function of receiving and reproducing optical signals of wavelengths λ1 to λ4 from the coupler 118 and outputting them to the first to fourth terminal apparatuses 116A1 to 116A4.

  The first to fourth spare transponders 114A1 'to 114A4' are spare transponders when a failure occurs in the first to fourth transponders 113A1 to 113A4, respectively. The first to fourth spare transponders 114A1 'to 114A4' use the same wavelengths λ1 to λ4 as the first to fourth transponders 113A1 to 113A4, respectively.

  Each optical switch 117 selects one of the optical signals from the first to fourth transponders 113A1 to 113A4 and the optical signals from the first to fourth auxiliary transponders 114A1 ′ to 114A4 ′ and outputs the selected one to the OADM unit 112A. .

  Each optical coupler 118 branches the optical signals of wavelengths λ1 to λ4 from the OADM unit 112A into two, and first to fourth transponders 113A1 to 113A4 and first to fourth spare transponders 114A1 ′ to 114A4 ′. Output to.

  The OADM unit 112A performs insertion, branching, and multiplexing of the input optical signal. The OADM unit 112A includes a wavelength multiplexer, a wavelength demultiplexer, and an optical switch.

  In the optical transmission system 100 shown in FIG. 1, the optical switch 117 selects the optical signals from the first to fourth transponders 113A1 to 113A4 and outputs them to the OADM unit 112A during normal operation. When a failure occurs in the first to fourth transponders 113A1 to 113A4, the optical switch 117 selects an optical signal from the backup transponder corresponding to the transponder in which the failure has occurred, and outputs the optical signal to the OADM unit 112A. Thus, even when a failure occurs in the first to fourth transponders 113A1 to 113A4, communication can be performed using the first to fourth spare transponders 114A1 'to 114A4'.

JP2011-259129A

  However, in the conventional optical transmission system 100 as shown in FIG. 1, since it is necessary to prepare spare transponders having the same wavelength for one transponder, there is room for improvement in terms of cost.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an inexpensive optical transmission system.

  In order to solve the above-described problems, an optical transmission system according to an aspect of the present invention is an optical transmission system that transmits a wavelength-multiplexed optical signal between a plurality of nodes via an optical transmission path. Each node converts optical signals received from a plurality of terminal devices into optical signals of different wavelengths and transmits them, and transmits optical signals of different wavelengths demultiplexed from the wavelength multiplexed optical signals to the plurality of terminal devices. A plurality of transponders, and the input optical signal is converted to an optical signal having a backup wavelength different from the wavelength used by the plurality of transponders and transmitted, and an optical signal having a backup wavelength demultiplexed from the wavelength multiplexed optical signal is transmitted. A spare transponder, a wavelength multiplexing unit that multiplexes an optical signal of a plurality of different wavelengths, and an optical signal of a standby wavelength, and transmits the optical signal to an optical transmission line, and demultiplexes the wavelength-multiplexed optical signal and demultiplexes each wavelength Between the plurality of transponders and spare transponders, and the plurality of terminal devices. And an optical switch that is. During normal operation, the spare transponders of each node are connected to the spare transponders of all other nodes in a single stroke. When a failure occurs in a transponder of a certain node, the optical switch of the certain node switches the connection destination of the terminal device connected to the transponder in which the failure has occurred to the spare transponder of the certain node, The optical switch of the other node to which the opposite transponder that has been communicating belongs switches the connection destination of the terminal device connected to the opposite transponder to the spare transponder of the other node.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between an apparatus, a method, a system, a program, a recording medium storing the program, and the like are also effective as an aspect of the present invention.

  According to the present invention, an inexpensive optical transmission system can be provided.

It is a figure which shows an example of the conventional WDM optical transmission system. 1 is a diagram illustrating a configuration of an optical transmission system according to a first embodiment of the present invention. It is a figure which shows operation | movement of the optical transmission system when a failure generate | occur | produces in the 1st transponder of a 1st node. It is a figure which shows operation | movement of the optical transmission system when a failure generate | occur | produces in the 4th transponder of a 1st node. It is a figure which shows the structure of the optical transmission system which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the optical transmission system which concerns on 3rd Embodiment of this invention. It is a figure which shows the structure of the optical transmission system which concerns on 4th Embodiment of this invention. It is a figure which shows operation | movement of the optical transmission system when a failure generate | occur | produces in the 1st transponder of a 1st node. It is a figure which shows the structure of the optical transmission system which concerns on 5th Embodiment of this invention. It is a figure which shows operation | movement of the optical transmission system when the next failure generate | occur | produces in the 1st transponder of a 1st node. It is a figure which shows operation | movement of the optical transmission system when the next failure generate | occur | produces in the 4th transponder of a 1st node.

(First embodiment)
FIG. 2 is a diagram showing a configuration of the optical transmission system 10 according to the first embodiment of the present invention. The optical transmission system 10 illustrated in FIG. 2 includes a first node 11A, a second node 11B, a third node 11C, and a fourth node 11D. In the present embodiment, these four nodes are OADM (Optical Add-Drop Multiplexer) devices.

  In the optical transmission system 10 according to the present embodiment, the first to fourth nodes 11A to 11D constitute a ring network. That is, the first node 11A is connected to the second node 11B via the optical transmission lines 21a and 21b, and the second node 11B is connected to the third node 11C via the optical transmission lines 22a and 22b. The third node 11C is connected to the fourth node 11D via the optical transmission lines 23a and 23b, and the fourth node 11D is connected to the first node 11A via the optical transmission lines 24a and 24b. Yes.

  Since the first to fourth nodes 11A to 11D have the same configuration, the configuration of the first node 11A will be described here. The first node 11A includes an OADM unit 12A, first to fourth transponders 13A1 to 13A4, a spare transponder 14A, an optical switch 15A, and first to fourth terminal devices 16A1 to 16A4 on the client side.

  The first to fourth transponders 13A1 to 13A4 receive optical signals of arbitrary wavelengths from the first to fourth terminal apparatuses 16A1 to 16A4 received via the optical switch 15A, respectively, and have different wavelengths λ1 to λ4 suitable for wavelength multiplexing. A function of converting the optical signal into an OADM unit 12A and transmitting it to the OADM unit 12A; receiving an optical signal with wavelengths λ1 to λ4 demultiplexed by the OADM unit 12A and performing predetermined signal processing such as identification reproduction; It has a function of converting to an optical signal having a wavelength of 1 and sending it to the optical switch 15A.

  In the present embodiment, the first node 1 includes one spare transponder 14A. This spare transponder 14A is a spare transponder for when a failure occurs in any of the first to fourth transponders 13A1 to 13A4. The spare transponder 14A has a function of converting an input optical signal having an arbitrary wavelength into an optical signal having a spare wavelength λb different from the wavelengths λ1 to λ4 used by the first to fourth transponders 13A1 to 13A4 and transmitting the optical signal to the OADM unit 12A. Then, after receiving the optical signal having the spare wavelength λb demultiplexed by the OADM unit 12A and performing predetermined signal processing such as identification reproduction, the optical signal is converted into an optical signal having an arbitrary wavelength and sent to the optical switch 15A. It has a function.

  The OADM unit 12A has a function of wavelength multiplexing the optical signals having the wavelengths λ1 to λ4 from the first to fourth transponders 13A1 to 13A4 and the optical signal having the standby wavelength λb from the standby transponder 14A, and sending them to the optical transmission line. Have. Further, the OADM unit 12A demultiplexes the wavelength multiplexed optical signal received from the optical transmission path, and sends the demultiplexed optical signal to the first to fourth transponders 13A1 to 13A4 and the spare transponder 14A corresponding to each wavelength. It has the function to do. The OADM unit 12A has a function of adding / dropping / through an optical signal having an arbitrary wavelength. The OADM unit 12A includes, for example, a wavelength multiplexer, a wavelength demultiplexer, and an optical switch.

  The optical switch 15A is an (n + 1) × n optical switch (n = 4) provided between the first to fourth transponders 13A1 to 13A4 and the spare transponder 14A and the first to fourth terminal devices 16A1 to 16A4. It is.

  During normal operation, the optical switch 15A connects the first to fourth transponders 13A1 to 13A4 to the first to fourth terminal devices 16A1 to 16A4, respectively, as shown in FIG. Accordingly, the first to fourth transponders 13A1 to 13A4 can transmit and receive optical signals to and from the first to fourth terminal devices 16A1 to 16A4, respectively. In normal operation, the optical switch 15A loops back the output of the spare transponder 14A to the input of the same spare transponder 14A. At this time, an AIS (Alarm Indication Signal) is generated in the spare transponder 14A. This AIS occurrence state is set to the standby state of the spare transponder 14A.

  In the optical transmission system 10 according to the first embodiment, during normal operation, the spare transponders of each node are connected to the spare transponders of all other nodes in a single stroke. In other words, when following the signal path from the spare transponder of each node, it is possible to return to the original spare transponder via the spare transponders of all other nodes without going through the same path twice. The OADM unit and optical switch of each node are set.

  In FIG. 2, a one-stroke connection of the spare transponder is illustrated by a dotted line. For example, when the signal path is traced from the spare transponder 14A of the first node 11A, the OADM unit 12A, the optical transmission line 21a, the OADM unit 12B, the spare transponder 14B, the OADM unit 12B, the optical transmission line 22a, the OADM unit 12C, and the spare transponder 14C. The OADM unit 12C, the optical transmission line 23a, the OADM unit 12D, the backup transponder 14D, the OADM unit 12D, the optical transmission line 24a, and the OADM unit 12A can be returned to the backup transponder 14A of the original first node 11A. .

  In the optical transmission system 10 according to the present embodiment, each node includes a monitoring unit (not shown) that monitors the operating state of the first to fourth transponders. When this monitoring unit detects a failure in any of the first to fourth transponders, the optical switch of the node switches the connection destination of the terminal device connected to the transponder in which the failure has occurred to the spare transponder.

  Further, since the transponder (that is, the opposite transponder) that has been communicating with the transponder in which the failure has occurred detects an abnormality such as a code error or signal disconnection, the occurrence of the failure can be detected. In this case, the optical switch of the node to which the opposing transponder belongs switches the connection destination of the terminal device connected to the opposing transponder to the spare transponder.

  Next, the operation of the optical transmission system 10 configured as described above will be described.

  FIG. 3 shows the operation of the optical transmission system 10 when a failure occurs in the first transponder 13A1 of the first node 11A. In FIG. 3, a cross mark indicating that a failure has occurred in the first transponder 13A1. Here, it is assumed that the first transponder 13A1 of the first node 11A and the first transponder 13C1 of the third node 11C are communicating during normal operation. That is, it is assumed that the first transponder 13A1 of the first node 11A and the first transponder 13C1 (indicated by a circle in FIG. 3) of the third node 11C face each other.

  In this case, the optical switch 15A of the first node 11A switches the connection destination of the first terminal device 16A1 connected to the failed first transponder 13A1 to the spare transponder 14A. Further, the optical switch 15C of the third node 11C detects the occurrence of the failure of the first transponder 13A1 of the first node 11A, so that the connection destination of the terminal device 16C1 connected to the opposite transponder 13C1 of the first transponder 13A1 is determined. To the spare transponder 14C.

  As a result of the optical switch switching as described above, the first terminal device 16A1 of the first node 11A and the first terminal device 16C1 of the third node 11C can communicate.

  The optical signal transmitted from the first terminal device 16A1 of the first node 11A is converted into an optical signal of the standby wavelength λb by the standby transponder 14A, and is transmitted to the optical transmission line 21a via the OADM unit 12A. The optical signal having the backup wavelength λb is sent to the third node 11C via the backup transponder 14B of the second node 11B. The OADM unit 12C of the third node 11C outputs the received optical signal having the backup wavelength λb to the backup transponder 14C. The optical signal output from the spare transponder 14C is sent to the first terminal device 16C1.

  On the other hand, the optical signal transmitted from the first terminal device 16C1 of the third node 11C is converted into an optical signal of the standby wavelength λb by the standby transponder 14C, and is transmitted to the optical transmission line 23a via the OADM unit 12C. The optical signal having the backup wavelength λb is sent to the first node 11A via the backup transponder 14D of the fourth node 11D. The OADM unit 12A of the first node 11A outputs the received optical signal having the backup wavelength λb to the backup transponder 14A. The optical signal output from the spare transponder 14A is sent to the first terminal device 16A1.

  As described above, according to the optical transmission system 10 according to the present embodiment, even when a failure occurs in the first transponder 13A1 of the first node 11A, between the terminal devices facing each other using the spare transponder of each node Can communicate.

  In the optical transmission system 10 according to this embodiment, when communication is performed using the spare transponder of each node when a failure occurs, the AIS disappears in the spare transponder of each node, and the standby transponder is released from the standby state. Therefore, even if a failure occurs in another transponder thereafter, switching to the spare transponder does not occur.

  Further, a case where a failure occurs in another transponder will be described. FIG. 4 shows the operation of the optical transmission system 10 when a failure occurs in the fourth transponder 13A4 of the first node 11A. In FIG. 4, a cross mark indicating that a failure has occurred in the fourth transponder 13A4. Here, it is assumed that the fourth transponder 13A4 of the first node 11A communicates with the fourth transponder 13D4 of the fourth node 11D during normal operation. That is, it is assumed that the fourth transponder 13A4 of the first node 11A and the fourth transponder 13D4 (shown by a circle in FIG. 4) of the fourth node 11D face each other.

  In this case, the optical switch 15A of the first node 11A switches the connection destination of the fourth terminal device 16A4 connected to the failed fourth transponder 13A4 to the spare transponder 14A. Further, the optical switch 15D of the fourth node 11D detects the occurrence of the failure of the fourth transponder 13A4 of the first node 11A, so that the connection destination of the terminal device 16D4 connected to the opposite transponder 13D4 of the fourth transponder 13A4 is determined. To the spare transponder 14D.

  As a result of the optical switch switching as described above, the fourth terminal device 16A4 of the first node 11A and the fourth terminal device 16D4 of the fourth node 11D can communicate.

  The optical signal transmitted from the fourth terminal device 16A4 of the first node 11A is converted into an optical signal of the standby wavelength λb by the standby transponder 14A, and is transmitted to the optical transmission line 21a via the OADM unit 12A. The optical signal having the spare wavelength λb is sent to the fourth node 11D via the spare transponder 14B of the second node 11B and the spare transponder 14C of the third node 11C. The OADM unit 12D of the fourth node 11D outputs the received optical signal having the backup wavelength λb to the backup transponder 14D. The optical signal output from the spare transponder 14D is sent to the fourth terminal device 16D.

  On the other hand, the optical signal transmitted from the fourth terminal device 16D4 of the fourth node 11D is converted into an optical signal of the standby wavelength λb by the standby transponder 14D, and is transmitted to the optical transmission line 24a via the OADM unit 12D. The OADM unit 12A of the first node 11A outputs the received optical signal having the backup wavelength λb to the backup transponder 14A. The optical signal output from the spare transponder 14A is sent to the fourth terminal device 16A4.

  As described above, according to the optical transmission system 10 according to the present embodiment, it is possible to protect a communication line even when a failure occurs in an arbitrary transponder of an arbitrary node, and the reliability as the transmission system is improved. Can be improved.

  In the optical transmission system 10 according to the present embodiment, the spare transponder of each node can be a spare for all wavelength transponders, and therefore it is not necessary to prepare a spare transponder for each transponder. Therefore, since the number of spare transponders can be reduced, an inexpensive optical transmission system 10 can be realized.

  Further, in the optical transmission system 10 according to the present embodiment, the path switching on the network side that normally takes time to draw in the signal does not occur, and the path switching only occurs on the client side that does not take much time to pull in the signal. is there. Further, in the optical transmission system 10 according to the present embodiment, it is not necessary to notify another node that a failure has occurred when performing path switching. Therefore, the optical transmission system 10 according to the present embodiment can realize high-speed path switching.

(Second Embodiment)
FIG. 5 is a diagram showing a configuration of the optical transmission system 20 according to the second embodiment of the present invention. The optical transmission system 20 illustrated in FIG. 5 includes a first node 11A, a second node 11B, a third node 11C, a fourth node 11D, and a fifth node 11E. In the present embodiment, the first node 11A and the fifth node 11E are WDM devices, and the second node 11B, the third node 11C, and the fourth node 11D are relay devices (ILA: In-Line Amplifier).

  In the optical transmission system 20 according to the present embodiment, the first to fifth nodes 11A to 11E constitute a point-to-point network. That is, the first node 11A is connected to the second node 11B via two optical transmission lines, and the second node 11B is connected to the third node 11C via two optical transmission lines. The third node 11C is connected to the fourth node 11D via two optical transmission lines, and the fourth node 11D is connected to the fifth node 11E via two optical transmission lines. Yes.

  Since the first node 11A and the fifth node 11E have the same configuration, the configuration of the first node 11A will be described here. The first node 11A includes a wavelength multiplexing / demultiplexing unit 17A, first to fourth transponders 13A1 to 13A4, a spare transponder 14A, an optical switch 15A, and first to fourth terminal devices 16A1 to 16A4 on the client side. Prepare.

  The functions and operations of the first to fourth transponders 13A1 to 13A4, the spare transponder 14A, the optical switch 15A, and the first to fourth terminal devices 16A1 to 16A4 are the same as those in the first embodiment shown in FIG.

  The wavelength multiplexing / demultiplexing unit 17A wavelength-multiplexes the optical signals of the wavelengths λ1 to λ4 from the first to fourth transponders 13A1 to 13A4 and the optical signal of the standby wavelength λb from the backup transponder 14A, and sends them to the optical transmission line. It has the function to do. The wavelength multiplexing / demultiplexing unit 17A demultiplexes the wavelength multiplexed optical signal received from the optical transmission line, and the first to fourth transponders 13A1 to 13A4 and the spare transponders corresponding to the respective wavelengths of the demultiplexed optical signal. 14A. The wavelength multiplexing / demultiplexing unit 17A includes, for example, a wavelength multiplexer and a wavelength demultiplexer.

  The second node 11B, the third node 11C, and the fourth node 11D have a function of amplifying and relaying the wavelength multiplexed optical signal wavelength-multiplexed by the WDM apparatus without electrical conversion.

  Also in the optical transmission system 20 according to the second embodiment, during normal operation, the spare transponders of each node are connected to the spare transponders of all other nodes in a single stroke. In FIG. 5, the one-stroke connection of the spare transponder is illustrated by a dotted line. For example, when the signal path is traced from the spare transponder 14A of the first node 11A, the wavelength multiplexing / demultiplexing unit 17E of the second node 11B, the third node 11C, the fourth node 11D, and the fifth node 11E, the spare transponder 14E, and the wavelength multiplexing It is possible to return to the spare transponder 14A of the original first node 11A via the demultiplexing unit 17E, the fourth node 11D, the third node 11C, the second node 11B, and the wavelength multiplexing demultiplexing unit 17A.

  Next, the operation of the optical transmission system 20 configured as described above will be described. In the optical transmission system 20 according to the present embodiment, during normal operation, the first to fourth transponders 13A1 to 13A4 of the first node 11A face the first to fourth transponders 13E1 to 13E4 of the fifth node 11E, respectively. doing.

  For example, when a failure occurs in the first transponder 13A1 of the first node 11A, the optical switch 15A of the first node 11A determines the connection destination of the first terminal device 16A1 connected to the failed first transponder 13A1. Switch to spare transponder 14A. The optical switch 15E of the fifth node 11E detects the failure of the first transponder 13A1 of the first node 11A, so that the connection destination of the terminal device 16E1 connected to the opposite transponder 13E1 of the first transponder 13A1 is determined. To the spare transponder 14E.

  As a result of the optical switch switching as described above, the first terminal device 16A1 of the first node 11A and the first terminal device 16E1 of the fifth node 11E can communicate.

  As described above, even in the optical transmission system 20 that is a point-to-point network, a communication line can be protected even when a failure occurs in an arbitrary transponder of an arbitrary node. As a result, the reliability can be improved. Also in the optical transmission system 20, the spare transponder of each node can be a spare for all wavelength transponders, so it is not necessary to prepare a spare transponder for each transponder. Therefore, since the number of spare transponders can be reduced, an inexpensive point-to-point optical transmission system 20 can be realized.

(Third embodiment)
FIG. 6 is a diagram illustrating a configuration of an optical transmission system 30 according to the third embodiment of the present invention. The optical transmission system 30 illustrated in FIG. 6 includes a first node 11A, a second node 11B, a third node 11C, a fourth node 11D, and a fifth node 11E. In the present embodiment, the first node 11A, the third node 11C, and the fifth node 11E are OADM devices, and the second node 11B and the fourth node 11D are relay devices.

  In the optical transmission system 30 according to the present embodiment, the first to fifth nodes 11A to 11E constitute a linear network. That is, the first node 11A is connected to the second node 11B via two optical transmission lines, and the second node 11B is connected to the third node 11C via two optical transmission lines. The third node 11C is connected to the fourth node 11D via two optical transmission lines, and the fourth node 11D is connected to the fifth node 11E via two optical transmission lines. Yes.

  The configurations of the first node 11A, the third node 11C, and the fifth node 11E are the same as those of the OADM node of the first embodiment shown in FIG. The second node 11B and the fourth node 11D have a function of amplifying and relaying the wavelength multiplexed optical signal wavelength-multiplexed by the OADM device without electrical conversion.

  Also in the optical transmission system 30 according to the third embodiment, during normal operation, the spare transponders of each node are connected to the spare transponders of all other nodes in a single stroke. In FIG. 6, the one-stroke connection of the spare transponder is indicated by a dotted line. For example, when the signal path is traced from the spare transponder 14A of the first node 11A, the OADM unit 12C of the second node 11B, the third node 11C, the fourth node 11D, the OADM unit 12E of the fifth node 11E, the spare transponder 14E, and OADM It is possible to return to the spare transponder 14A of the original first node 11A via the unit 12E, the fourth node 11D, the OADM unit 12C of the third node 11C, the spare transponder 14C, the second node 11B, and the OADM unit 12A.

  Next, the operation of the optical transmission system 30 configured as described above will be described. For example, consider a case where a failure has occurred in the first transponder 13A1 of the first node 11A. Here, it is assumed that the first transponder 13A1 of the first node 11A and the first transponder 13E1 of the fifth node 11E are communicating during normal operation.

  In this case, the optical switch 15A of the first node 11A switches the connection destination of the first terminal device 16A1 connected to the failed first transponder 13A1 to the spare transponder 14A. The optical switch 15E of the fifth node 11E detects the failure of the first transponder 13A1 of the first node 11A, so that the connection destination of the terminal device 16E1 connected to the opposite transponder 13E1 of the first transponder 13A1 is determined. To the spare transponder 14E.

  As a result of the optical switch switching as described above, the first terminal device 16A1 of the first node 11A and the first terminal device 16E1 of the fifth node 11E can communicate.

  As described above, even in the optical transmission system 30 that is a linear network, a communication line can be protected even when a failure occurs in an arbitrary transponder of an arbitrary node, and the reliability as the transmission system is improved. Can be improved. Also in the optical transmission system 30, the spare transponder of each node can be a spare for all wavelength transponders, so there is no need to prepare a spare transponder for each transponder. Therefore, since the number of spare transponders can be reduced, an inexpensive linear optical transmission system 30 can be realized.

(Fourth embodiment)
FIG. 7 is a diagram showing a configuration of an optical transmission system 40 according to the fourth embodiment of the present invention. The optical transmission system 40 illustrated in FIG. 7 includes first to ninth nodes 11A to 11I. In the present embodiment, the first to ninth nodes 11A to 11I are OADM devices and have the same configuration as that of the first embodiment shown in FIG. In the optical transmission system 30 according to the present embodiment, the first to ninth nodes 11A to 11I form a mesh type network as shown in FIG. Each node is connected by two optical transmission lines.

  Also in the optical transmission system 40 according to the fourth embodiment, during normal operation, the spare transponders of each node are connected to the spare transponders of all other nodes in a single stroke. In FIG. 7, a one-stroke connection of the spare transponder is indicated by a dotted line. For example, when the signal path is traced from the spare transponder 14A of the first node 11A, the second node 11B, the fifth node 11E, the sixth node 11F, the third node 11C, the sixth node 11F, the seventh node 11G, and the eighth node It is possible to return to the spare transponder 14A of the original first node 11A via 11H, the ninth node 11I, and the fourth node 11D.

  Next, the operation of the optical transmission system 40 configured as described above will be described. FIG. 8 shows the operation of the optical transmission system 40 when a failure occurs in the first transponder of the first node 11A. In FIG. 8, a cross mark indicating that a failure has occurred in the first transponder is described. Here, it is assumed that the first transponder of the first node 11A and the first transponder of the sixth node 11F are communicating during normal operation. That is, it is assumed that the first transponder of the first node 11A and the first transponder (indicated by a circle in FIG. 8) of the sixth node 11F face each other.

  In this case, the optical switch of the first node 11A switches the connection destination of the first terminal device connected to the failed first transponder to the spare transponder. Further, the optical switch of the sixth node 11F switches the connection destination of the terminal device connected to the opposite transponder to the spare transponder when detecting the failure of the first transponder of the first node 11A.

  As a result of the optical switch switching as described above, the first terminal device of the first node 11A and the first terminal device of the sixth node 11F can communicate.

  The optical signal transmitted from the first terminal device of the first node 11A is converted into an optical signal of the standby wavelength λb by the backup transponder and sent to the optical transmission line via the OADM unit. The optical signal of the standby wavelength λb is transmitted to the standby transponder of the sixth node 11F via the second node 11B, the fifth node 11E, the sixth node 11F (here, only passing through the OADM unit), and the third node 11C. It is received and sent to the first terminal device of the sixth node 11F.

  On the other hand, the optical signal transmitted from the first terminal device of the sixth node 11F is converted into an optical signal of the standby wavelength λb by the backup transponder and sent to the optical transmission line via the OADM unit. The optical signal of the standby wavelength λb is received by the backup transponder of the first node 11A via the seventh node 11G, the eighth node 11H, the ninth node 11I, and the fourth node 11D, and the first node 11A receives the first signal. It is sent to the terminal device.

  As described above, even in the optical transmission system 40 that is a mesh network, a communication line can be protected even when a failure occurs in an arbitrary transponder of an arbitrary node, and the reliability as a transmission system is improved. Can be improved. Also in the optical transmission system 40, the spare transponder of each node can be a spare for all wavelength transponders, so that it is not necessary to prepare a spare transponder for each transponder. Since the mesh network has a large number of nodes, the cost of the optical transmission system 40 can be greatly reduced by reducing the number of spare transponders.

(Fifth embodiment)
FIG. 9 is a diagram showing a configuration of an optical transmission system 50 according to the fifth embodiment of the present invention. In the optical transmission system 50 illustrated in FIG. 9, a ring network is configured using the first to fourth nodes 11A to 11D, similarly to the optical transmission system 10 according to the first embodiment illustrated in FIG.

  Since the first to fourth nodes 11A to 11D have the same configuration, the configuration of the first node 11A will be described here. In the optical transmission system 50 according to the fifth embodiment, the first node 11A includes two spare transponders, a first spare transponder 14A1 and a second spare transponder 14A2. The first backup transponder 14A1 is a transponder that uses the first backup wavelength λb1, and the second backup transponder 14A2 is a transponder that uses a second backup wavelength λb2 different from the first backup wavelength λb1. The first backup wavelength λb1 and the second backup wavelength λb2 are different from the wavelengths λ1 to λ4 used by the first to fourth transponders 13A1 to 13A4.

  During normal operation, the optical switch 15A connects the first to fourth transponders 13A1 to 13A4 to the first to fourth terminal devices 16A1 to 16A4, respectively, as shown in FIG. Accordingly, the first to fourth transponders 13A1 to 13A4 can transmit and receive optical signals to and from the first to fourth terminal devices 16A1 to 16A4, respectively.

  In normal operation, the optical switch 15A loops back the output of the first spare transponder 14A1 to the input of the same first spare transponder 14A1. Further, the optical switch 15A loops back the output of the second spare transponder 14A2 to the input of the same second spare transponder 14A2. At this time, an AIS (Alarm Indication Signal) is generated in the first spare transponder 14A1 and the second spare transponder 14A2. This AIS occurrence state is a standby state of the first spare transponder 14A1 and the second spare transponder 14A2.

  In the optical transmission system 50 according to the fifth embodiment, during normal operation, the first spare transponder of each node is connected to the first spare transponders of all other nodes in a single stroke. In addition, the second spare transponder of each node is connected to the second spare transponders of all other nodes in a single stroke. In FIG. 9, the one-stroke writing connection of the first auxiliary transponder is illustrated by a dotted line, and the one-stroke writing connection of the second auxiliary transponder is illustrated by a one-dot chain line.

  In the optical transmission system 50 according to the fifth embodiment, when a monitoring unit (not shown) of each node detects a failure (primary failure) in any of the first to fourth transponders, the optical switch of the node Switches the connection destination of the terminal device connected to the transponder in which the primary failure has occurred to the first spare transponder. Further, the optical switch of the node to which the opposite transponder communicating with the transponder in which the primary failure has occurred switches the connection destination of the terminal device connected to the opposite transponder to the first spare transponder. As a result, since the optical signal communicates with the first spare transponder of each node, the AIS of the first spare transponder disappears and the standby state is released. Therefore, even if a failure occurs thereafter, switching to the first spare transponder does not occur. On the other hand, the second spare transponder has generated an AIS and is still in a standby state.

  Further, when the monitoring unit of each node detects a failure (secondary failure) in another transponder, the optical switch of the node determines the connection destination of the terminal device connected to the transponder in which the secondary failure has occurred. 2 Switch to spare transponder. In addition, the optical switch of the node to which the opposing transponder that is communicating with the transponder in which the secondary failure has occurred switches the connection destination of the terminal device connected to the opposing transponder to the second standby transponder. As a result, since the optical signal communicates with the second spare transponder of each node, the AIS of the second spare transponder disappears and the standby state is released. Therefore, even if a failure occurs thereafter, switching to the second spare transponder does not occur.

  Next, the operation of the optical transmission system 50 configured as described above will be described.

  FIG. 10 shows the operation of the optical transmission system 50 when a primary failure occurs in the first transponder 13A1 of the first node 11A. In FIG. 10, the first transponder 13A1 is marked with a cross indicating that a primary failure has occurred. Here, it is assumed that the first transponder 13A1 of the first node 11A and the first transponder 13C1 of the third node 11C are communicating during normal operation. That is, it is assumed that the first transponder 13A1 of the first node 11A and the first transponder 13C1 (indicated by a circle in FIG. 10) of the third node 11C face each other.

  In this case, the optical switch 15A of the first node 11A switches the connection destination of the first terminal device 16A1 connected to the first transponder 13A1 in which the primary failure has occurred to the first spare transponder 14A1. Further, the optical switch 15C of the third node 11C detects the occurrence of the primary failure of the first transponder 13A1 of the first node 11A, so that the terminal device 16C1 connected to the opposite transponder 13C1 of the first transponder 13A1 is connected. The destination is switched to the first spare transponder 14C1.

  As a result of the optical switch switching as described above, the first terminal device 16A1 of the first node 11A and the first terminal device 16C1 of the third node 11C can communicate.

  FIG. 11 shows the operation of the optical transmission system 50 when a secondary failure occurs in the fourth transponder 13A4 of the first node 11A. In FIG. 11, a cross mark indicating that a secondary failure has occurred is described in the fourth transponder 13A4. Here, it is assumed that the fourth transponder 13A4 of the first node 11A communicates with the fourth transponder 13D4 of the fourth node 11D during normal operation. That is, it is assumed that the fourth transponder 13A4 of the first node 11A and the fourth transponder 13D4 (shown by a circle in FIG. 11) of the fourth node 11D face each other.

  In this case, the optical switch 15A of the first node 11A switches the connection destination of the fourth terminal device 16A4 connected to the fourth transponder 13A4 in which the secondary failure has occurred to the second spare transponder 14A2. In addition, the optical switch 15D of the fourth node 11D detects the occurrence of the secondary failure of the fourth transponder 13A4 of the first node 11A, so that the terminal device 16D4 connected to the opposite transponder 13D4 of the fourth transponder 13A4 is connected. The destination is switched to the second spare transponder 14D2.

  As a result of the optical switch switching as described above, the fourth terminal device 16A4 of the first node 11A and the fourth terminal device 16D4 of the fourth node 11D can communicate.

  Thus, according to the optical transmission system 50 according to the fifth embodiment, by providing two spare transponders at each node, it is possible to realize two-stage communication line protection, and to improve the reliability as a transmission system. It can be further improved.

  In the optical transmission system 50 according to the fifth embodiment, the number of spare transponders provided in each node is two. However, three or more spare transponders may be provided in each transponder. In this case, an optical transmission system that can provide a more advanced protection function can be realized.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

    10, 20, 30, 40, 50 Optical transmission system, 11A to 11I 1st to 9th node, 12 OADM unit, 13 transponder, 14 backup transponder, 15 optical switch, 16 terminal device, 17 wavelength division multiplexing unit.

Claims (8)

An optical transmission system for transmitting wavelength multiplexed optical signals between a plurality of nodes via an optical transmission line,
Each node
A plurality of transponders that convert optical signals received from a plurality of terminal devices into optical signals of different wavelengths and transmit the signals, and transmit optical signals of different wavelengths demultiplexed from the wavelength multiplexed optical signal to the plurality of terminal devices. When,
A spare transponder that converts an input optical signal into an optical signal having a standby wavelength different from the wavelength used by a plurality of transponders and transmits the optical signal, and transmits an optical signal having a standby wavelength that is demultiplexed from the wavelength multiplexed optical signal;
A wavelength multiplexing unit that multiplexes an optical signal of a plurality of different wavelengths and an optical signal of a backup wavelength and transmits the optical signal to an optical transmission line;
A wavelength demultiplexing unit that demultiplexes the wavelength-multiplexed optical signal and sends the demultiplexed optical signals to the corresponding transponder and backup transponder;
An optical switch provided between a plurality of transponders and spare transponders and a plurality of terminal devices;
With
During normal operation, the spare transponder of each node is connected to the spare transponders of all other nodes in a single stroke.
When a failure occurs in a transponder of a certain node, the optical switch of the certain node switches the connection destination of the terminal device connected to the transponder in which the failure has occurred to the spare transponder of the certain node, An optical transmission system characterized in that an optical switch of another node to which the opposite transponder that has performed communication switches a connection destination of a terminal device connected to the opposite transponder to a spare transponder of the other node.   During normal operation, when the spare transponder of each node follows the signal path from each spare transponder, it does not go through the same path twice, but goes through the spare transponders of all other nodes to the original spare transponder. 2. The optical transmission system according to claim 1, wherein the optical transmission system is connected to backup transponders of all other nodes so as to be able to return.   3. The optical transmission system according to claim 1, wherein the optical switch of each node loops back the output of the spare transponder to the input of the same spare transponder during normal operation.   4. The optical transmission system according to claim 1, wherein each node includes a plurality of spare transponders.   The optical transmission system according to claim 1, wherein the plurality of nodes constitute a ring network.   The optical transmission system according to claim 1, wherein the plurality of nodes constitute a point-to-point network.   The optical transmission system according to claim 1, wherein the plurality of nodes form a linear network.   The optical transmission system according to claim 1, wherein the plurality of nodes constitute a mesh type network.

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