Patent ID: 12191905

DESCRIPTION OF EMBODIMENTS

Modes for carrying out the optical communication system and the protection method for the optical communication system according to the present disclosure will be described with reference to the drawings. In each figure, same numerals are assigned to identical or corresponding parts and repetition of description will be simplified or omitted. In the following description, for convenience, the positional relationship of each structure may be expressed with reference to the state shown in the figure. It should be noted that the present disclosure is not limited to the following embodiments, and within the scope not departing from the spirit of the present disclosure, any combination of the embodiments, any modification of component of the embodiments, or omission of any constituted component of the embodiments can be performed.

First Embodiment

Embodiment 1 of the present disclosure will be described with reference toFIGS.1to3.FIG.1is a diagram schematically showing an entire configuration of the optical communication system.FIG.2is a diagram showing an example of input/output characteristics of the wavelength routing device provided in the optical communication system.FIG.3is a diagram showing an example of an operation of the optical communication system.

The optical communication system according to this embodiment is a communication system for communicating an optical signal between the wavelength variable communication device10and the wavelength variable subscriber device20. As shown inFIG.1, the optical communication system includes the plurality of wavelength variable communication devices10and the plurality of wavelength variable subscriber devices20. In the shown example, N sets of wavelength variable communication devices10are provided. M sets of wavelength variable subscriber devices20are provided. N and M are integers that are 2 or more.

In order to distinguish the respective wavelength variable communication devices10, serial numbers are assigned to the respective wavelength variable communication devices10for convenience, and the respective wavelength variable communication devices10are assigned to the wavelength variable communication devices10#1, the wavelength variable communication device10#2, . . . , the wavelength variable communication device10#N−1, the wavelength variable communication device10#N. Similarly, in order to distinguish each wavelength variable subscriber device20, serial numbers are assigned to the respective wavelength variable subscriber devices20for convenience, and the respective wavelength variable subscriber devices20are assigned to the wavelength variable subscriber device20#1, the wavelength variable subscriber device20#2, . . . , the wavelength variable subscriber device20#M−1, the wavelength variable subscriber device20#M.

Each of the wavelength variable communication devices10is connected to, for example, one common master station device (not shown). Each of the wavelength variable subscriber devices20is connected to, for example, a respective slave station device (not shown).

In this embodiment, each of the wavelength variable communication devices10can change the wavelength of an optical signal to be transmitted toward the wavelength variable subscriber device20. Each wavelength variable communication device10can receive an optical signal of a preset specific wavelength. Here, it is assumed that the wavelength of the optical signal to be transmitted by the wavelength variable communication device10#1is set to λD_1, and the wavelength of the optical signal receivable by the wavelength variable communication device10#1is λU_1. Similarly, it is assumed that the wavelength of the optical signal to be transmitted by the wavelength variable communication device10#2is set to λD_2, and the wavelength of the optical signal receivable by the wavelength variable communication device10#2is set to λU_2. Then, itis assumed that the wavelength of the optical signal to be transmitted by the wavelength variable communication device10#N is set to λD_N, and the wavelength of the optical signal receivable by the wavelength variable communication device10#N is set to λU_N.

Each wavelength variable subscriber device20can change the wavelength of the optical signal to be transmitted and received. That is, each wavelength variable subscriber device20can change the wavelength of the optical signal to be transmitted toward the wavelength variable communication device10. Each wavelength variable subscriber device20can change the wavelength of the optical signal to be received. That is, each wavelength variable subscriber device20selectively receives signal light of one wavelength channel from a wavelength multiplexed signal (WDM signal) obtained by multiplexing a plurality of wavelength channels. Then, each wavelength variable subscriber device20can change and set a wavelength channel to be selectively received. Here, for example, it is assumed that the operating wavelength of the wavelength variable subscriber device20#1is λU_1in the upward direction and λD_1in the downward direction. In the same way, the operating wavelength is set for the other wavelength variable subscriber devices20.

The optical communication system includes a wavelength routing device30, an optical multiplexing/demultiplexing device40, and an optical fiber transmission path50. The wavelength variable communication device10and the wavelength variable subscriber device20are communicably connected through the wavelength routing device30, the optical multiplexing/demultiplexing device40and the optical fiber transmission path50. The wavelength routing device30is connected to each wavelength variable communication device10. The optical multiplexing/demultiplexing device40is connected to each wavelength variable subscriber device20. The wavelength routing device30and the optical multiplexing/demultiplexing device40are connected by the plurality of optical fiber transmission paths50. In the example of the configuration described here, two of a normal path51and a redundant path52are laid as the plurality of optical fiber transmission paths50.

The optical communication system further includes an optical distribution device100. In this embodiment, the optical distribution device100is provided between the wavelength routing device30and the optical multiplexing/demultiplexing device40. A port on the wavelength variable communication device10side of the optical distribution device100is connected to the wavelength routing device30via a first signal transmission path201and a second signal transmission path202which are signal transmission paths200. That is, the wavelength routing device30and the optical distribution device100are connected by the plurality of signal transmission paths200. The normal path51and the redundant path52, which are the plurality of optical fiber transmission paths50, are connected to a port on the wavelength variable subscriber device20side of the optical distribution device100.

In the shown example of the configuration, for the wavelength variable communication device10side of the optical multiplexing/demultiplexing device40, the port #1-1is connected to the normal path51of the optical fiber transmission path50, and the port #1-2is connected to the redundant path52of the optical fiber transmission path50. Further, ports #2-1, #2-2, . . . , #2-M on the wavelength variable subscriber device20side in the optical multiplexing/demultiplexing device40are connected to the wavelength variable subscriber device20#1, the wavelength variable subscriber device20#2, . . . , the wavelength variable subscriber device20#M, respectively.

Then, the optical multiplexing/demultiplexing device40branches the light inputted from the one side port and outputs it to each of the opposite side ports. For example, the light inputted to the port #1-1of the optical multiplexing/demultiplexing device40is branched regardless of the wavelength and outputted to each port of #2-1to #2-M. The light inputted to the port #2-1of the optical multiplexing/demultiplexing device40is branched regardless of the wavelength and outputted to each port of #1-1or #1-2.

In the shown example of the configuration, for the wavelength variable subscriber device20side of the optical distribution device100, the port #1-1is connected to the normal path51of the optical fiber transmission path50, and the port #1-2is connected to the redundant path52of the optical fiber transmission path50. For the wavelength variable communication device10side of the optical distribution device100, the first signal transmission path201is connected to the port #2-1, and the second signal transmission path202is connected to the port #2-2.

Then, the optical distribution device100outputs the optical signals inputted from the respective ports to the ports whose connection relation is set as connection ports to the ports. The connection relation between the ports in the optical distribution device100can be arbitrarily changed and set. As the optical distribution device100, for example, a spatial type optical switch using a micro electro mechanical systems (MEMS) or the like, a waveguide type optical switch using a planar lightwave circuit (PLC) or the like, etc. can be used.

In the shown example of the configuration, for the wavelength variable subscriber device20side of the wavelength routing device30, the port #1-1is connected to the first signal transmission path201and the port #1-2is connected to the second signal transmission path202. Furthermore, the port #2-1, #2-2, . . . , #2-N−1, #2-N on the wavelength variable communication device10side of the wavelength routing device30are connected to the wavelength variable communication device10#1, the wavelength variable communication device10#2, . . . , the wavelength variable communication device10#N−1, the wavelength variable communication device10#N, respectively.

Then, the wavelength routing device30outputs the optical signals inputted to the ports #1-1, #1-2on the wavelength variable subscriber device20side to the ports uniquely determined by a combination of a wavelength of the optical signal and the port to which the optical signal is inputted on the wavelength variable communication device10side. Further, the wavelength routing device30outputs the optical signals inputted to each of the ports #2-1to #2-N on the wavelength variable communication device10side to the ports uniquely determined by a combination of a wavelength of the optical signal and a port to which the optical signal is inputted on the wavelength variable subscriber device20side.FIG.2shows an example of input/output characteristics of the wavelength routing device30. As shown inFIG.2, the wavelength routing device30outputs, for example, light having a wavelength λU_1inputted from the port #1-1to the port #2-1. Then, the wavelength routing device30outputs the light of the wavelength λD_1inputted from the port #2-1to the port #1-1. In addition, for example, the wavelength routing device30outputs the light of the wavelength λU_2inputted from the port #1-2to the port #2-1. Then, the wavelength routing device30outputs the light of the wavelength λD_2inputted from the port #2-1to the port #1-2.

The optical communication system configured as the above description is so-called a PON (Passive Optical Network) system. Then, each wavelength variable subscriber device20sets the transmission wavelength and the reception wavelength to the assigned operating wavelength, thereby logically realizing point-to-point communication with the facing wavelength variable communication device10.

Next, the protection when communication between the wavelength variable subscriber device20and the wavelength variable communication device10is disconnected in the optical communication system of this embodiment will be described. In the optical communication system of this embodiment, at least the first protection and the second protection can be executed.

First, in the first protection, the wavelength of the optical signal to be transmitted and received is switched from the operating wavelength to the spare wavelength when the wavelength variable subscriber device20and the facing wavelength variable communication device10are disconnected. Here, the spare wavelength is different from the operating wavelength. In order to switch the wavelength to be transmitted and received to the spare wavelength by the wavelength variable subscriber device20, it is necessary for the wavelength variable subscriber device20to recognize the spare wavelength. Therefore, for example, by notifying the wavelength variable subscriber device20of the spare wavelength in advance, the transmission wavelength can be autonomously switched to the spare wavelength when the wavelength variable subscriber device20recognizes the communication interruption. That is, the wavelength variable subscriber device20can execute the first protection for switching the wavelength of an optical signal to be transmitted and received to the spare wavelength different from the operating wavelength when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected.

For example, when a state in which the wavelength variable subscriber device20does not receive an optical signal from the facing wavelength variable communication device10continues for a wavelength variable predetermined time period or longer, the wavelength variable subscriber device20switches a wavelength channel selectively received and then recognizes spare wavelength information carried on the wavelength channel, and the wavelength variable subscriber device20can recognize the spare wavelength. As the means for carrying the spare wavelength information on the wavelength channel, a control frame of the same frequency band as that of the client signal (for example, Ethernet OAM (Ethernet is a registered trademark)), or may be notified by using a control channel which does not interfere the frequency band of the client signal (for example, AMCC (Auxiliary Management and Control Channel)).

As described above, the wavelength routing device30outputs the optical signals inputted to the ports #1-1, #1-2on the wavelength variable subscriber device20side to the ports uniquely determined by a combination of a wavelength of the optical signal and a port to which the optical signal is inputted on the wavelength variable communication device10side. Therefore, when the wavelength variable subscriber device20executes the first protection and the transmission/reception wavelength of the wavelength variable subscriber device20is switched to the spare wavelength, the facing device of the wavelength variable subscriber device20becomes the wavelength variable communication device10different from the wavelength variable communication device10before switching. That is, the wavelength variable communication device10connected to a path through which the spare wavelength communicates in the wavelength routing device30becomes a new facing device of the wavelength variable subscriber device20in which communication is disconnected.

For example, when communication between the wavelength variable subscriber device20#1and the wavelength variable communication device10#1is disconnected, the wavelength variable subscriber device20#1executes the first protection, and thereby the wavelength variable subscriber device20#1switches the transmission/reception wavelength from the operating wavelength (λU_1and λD_1) to the spare wavelength (λU_2and λD_2). According to the input/output characteristics ofFIG.2, the optical signal of the spare wavelength (λU_2and λD_2) inputted/outputted from and to the port #1-1of the wavelength routing device30is inputted/outputted from the port #2-2of the wavelength routing device30to the wavelength variable communication device10#2. Therefore, the wavelength variable communication device10#2becomes a new facing device of the wavelength variable subscriber device #1.

Next, in the second protection, the optical distribution device100switches the optical fiber transmission path50to be used when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected. In the example of the configuration described here, there are the normal path51and the redundant path52as the optical fiber transmission path50. When the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected, the optical distribution device100can execute the second protection in which the connection port corresponding to the port to which an optical signa to be transmitted from the wavelength variable communication device10is switched from the port1#1connected to the normal path51to the port #1-2connected to the redundant path52.

Further, in the optical communication system of this embodiment, a third protection may be executed. In the third protection, the optical distribution device100switches the signal transmission path200to be used when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected. When the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected, the optical distribution device100can execute the third protection in which the optical distribution device100switches the connection port to which an optical signal to be transmitted from the wavelength variable communication device10from the port #2-1connected to the first signal transmission path201to the port #2-2connected to the second signal transmission path202.

The wavelength variable subscriber device20and the optical distribution device100are provided with a computer having, for example, a processor and a memory as hardware. The processor is also called a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer or a DSP. For the memory, for example, a RAM, a ROM, a flash memory, a non-volatile or volatile semiconductor memory such as EPROM and EEPROM, or a magnetic disc, an optical disc, a flexible disc, an optical disc, a compact disc, a mini disc, a DVD and the like are applicable.

A program as software is stored in the memories of the wavelength variable subscriber device20and the optical distribution device100. Then, the wavelength variable subscriber device20and the optical distribution device100execute preset processing by executing the program stored in the memory by the processor, and as a result of cooperation between hardware and software, a function of controlling execution of the first protection, the second protection and the third protection is realized.

Alternatively, the optical communication system may control execution of the first protection, the second protection and the third protection by a control unit (not shown). Also in this case, the control unit (not shown) is provided with a computer having, for example, a processor and a memory as hardware. Then, the processor executes a program stored in a memory of the control unit to perform preset processing, and as a result of cooperation of hardware and software, a function for controlling execution of the first protection, the second protection and the third protection is realized.

Next, a description will be given of an example of an operation procedure of the optical communication system that is configured as described above with reference toFIG.3. First, in a step S1, if no disconnection occurs between the wavelength variable communication device10and the wavelength variable subscriber device20, a series of operations are terminated. On the other hand, if there is a disconnection between the wavelength variable communication device10and the wavelength variable subscriber device20, the processing proceeds to a step S2, and the wavelength variable subscriber device20which has a disconnection with the facing wavelength variable communication device10executes the first protection.

In the following step S3, if the wavelength variable communication device10and the wavelength variable subscriber device20are not disconnected, it is determined that the communication is recovered, and a series of operations are terminated. On the other hand, when the disconnection between the wavelength variable communication device10and the wavelength variable subscriber device20is continued in the step S3, the processing proceeds to a step S4, and the optical distribution device100executes the second protection. Then, in the following step S5, if the wavelength variable communication device10and the wavelength variable subscriber device20are not disconnected, it is determined that the communication is recovered, and a series of operations are terminated. On the other hand, if the disconnection between the wavelength variable communication device10and the wavelength variable subscriber device20is still continued in the step S5, the processing proceeds to a step S6, and the optical distribution device100executes the third protection. When the processing of the step S6is terminated, a series of operations are terminated.

The execution order of the first protection of the step S2, the second protection of the step S4, and the third protection of the step S6is not limited to the example shown inFIG.3. That is, the first protection, the second protection, and the third protection may be executed in an arbitrary order.

In the protection method of the optical communication system described above, at least the first step of executing the first protection and the second step of executing the second protection are executed in an arbitrary order. Further, a third step of executing the third protection described above may be provided, and in this case, the first step, the second step, and the third step are executed in an arbitrary order.

In the optical communication system and the protection method for the optical communication system of the present embodiment, at least the first protection for switching the wavelength of an optical signal to be transmitted and received to the spare wavelength different from the operating wavelength by the wavelength variable subscriber device20and the second protection for switching the optical fiber transmission path50used for communication by the optical distribution device100can be executed when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected.

By executing such first protection, the wavelength variable communication device10facing the wavelength variable subscriber device20can be changed to a new one, and it is possible to cope with a disconnection due to an abnormality or the like of the facing wavelength variable communication device10. Further, by executing the second protection, the optical fiber transmission path50is switched from the normal path51to the redundant path52, and it is possible to cope with a disconnection due to the abnormality or the like of the optical fiber transmission path50.

Therefore, it is possible to cope with the disconnection due to the abnormality of both the wavelength variable communication device10and the optical fiber transmission path50. Therefore, in any case of when the wavelength variable communication device10is single-unit disabled, the optical fiber transmission path50is single-unit disabled, or the wavelength variable communication device10and the optical fiber transmission path50are multiple disabled, the communication can be restarted within a short time period. Specifically, for example, in not only disconnection of an optical fiber transmission path50between the optical multiplexing/demultiplexing device40and the optical distribution device100, but also failure, function upgrade, maintenance, and the like of the wavelength variable communication device10, the communication disconnection time period can be shortened. Furthermore, the number of wavelength variable subscriber devices20to be protection target can be minimized.

Further, in the optical communication system and the protection method for the optical communication system of this embodiment, the third protection for switching the signal transmission path200used for communication between the optical distribution device100and the wavelength routing device30may be executable when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected. By making it possible to execute such third protection, the communication path can be made redundant in addition to the optical fiber transmission path50between the optical multiplexing/demultiplexing device40and the optical distribution device100, and also in the section between the optical distribution device100and the wavelength routing device30.

Second Embodiment

A second embodiment of the present disclosure will be described with reference toFIGS.4and5.FIG.4is a diagram schematically showing an entire configuration of the optical communication system.FIG.5is a diagram showing an example of input/output characteristics of the wavelength routing device provided in the optical communication system.

In the second embodiment described here, the optical distribution device is provided between the wavelength routing device and each of the wavelength variable communication devices in the configuration of the first embodiment described above. The optical communication system and the protection method of the optical communication system according to the second embodiment will be described mainly with respect to the difference from the first embodiment. The structure in which the description is omitted is basically the same as that of the first embodiment. In the following description, structures similar to or corresponding to those of the first embodiment will be described with the same reference numerals as those used in the description of the first embodiment in principle.

As shown inFIG.4, the optical communication system according to this embodiment includes a plurality of wavelength variable communication devices10, a plurality of wavelength variable subscriber devices20, a wavelength routing device30, an optical multiplexing/demultiplexing device40and an optical distribution device100. In this embodiment, each of the wavelength variable communication devices10can change the wavelength of the optical signal to be transmitted. The wavelength routing device30and the optical multiplexing/demultiplexing device40are connected by a plurality of optical fiber transmission paths50. In the example of the configuration described here, two of a normal path51and a redundant path52are laid as a plurality of optical fiber transmission paths50.

In this embodiment, the optical distribution device100is provided between the wavelength routing device30and each of the wavelength variable communication devices10. A port on the wavelength variable subscriber device20side of the optical distribution device100is connected to a wavelength routing device30via a plurality of signal transmission paths200. A port on the wavelength variable communication device10side of the optical distribution device100is connected to each wavelength variable communication device10.

In the shown example of the configuration, for the wavelength variable subscriber device20side of the wavelength routing device30, the port #1-1is connected to the normal path51of the optical fiber transmission path50, and the port #1-2is connected to the redundant path52of the optical fiber transmission path50. The ports #2-1, #2-2, . . . , #2-M on the wavelength variable communication device10side of the wavelength routing device30are connected to the ports #1-1, #1-2, . . . , #1-M on the wavelength variable subscriber device20side of the optical distribution device100by M signal transmission paths200, respectively. Then, ports #2-1, #2-2, . . . , #2-N on the wavelength variable communication device10side of the optical distribution device100are connected to the wavelength variable communication device10#1, the wavelength variable communication device10#2, . . . , the wavelength variable communication device10#N, respectively.

The optical distribution device100outputs the optical signal inputted from the respective ports to a port in which a connection relation is set as a connection port to the port. The connection relation between the ports in the optical distribution device100can be arbitrarily changed and set.

The wavelength routing device30outputs the optical signals inputted to the ports #1-1, #1-2on the wavelength variable subscriber device20side to the ports uniquely determined by a combination of a wavelength of the optical signal and a port to which the optical signal is inputted on the wavelength variable communication device10. Further, the wavelength routing device30outputs the optical signals inputted to each of the ports #2-1to #2-M on the wavelength variable communication device10side to the ports uniquely determined by a combination of a wavelength of the optical signal and a port to which the optical signal is inputted on the wavelength variable subscriber device20side.FIG.5shows an example of input/output characteristics of the wavelength routing device30. As shown inFIG.5, the wavelength routing device30outputs, for example, light having a wavelength λU_1inputted from the port #1-1to the port #2-1. Then, the wavelength routing device30outputs the light of the wavelength λD_1inputted from the port #2-1to the port #1-1. In addition, for example, the wavelength routing device30outputs the light of the wavelength λU_2inputted from the port #1-2to the port #2-1. Then, the wavelength routing device30outputs the light of the wavelength λD_2inputted from the port #2-1to the port #1-2.

Next, protection when communication between the wavelength variable subscriber device20and the wavelength variable communication device10is disconnected in the optical communication system of this embodiment will be described. In the optical communication system of this embodiment, at least the first protection and the second protection can be executed.

First, in the first protection, the wavelength variable subscriber device20switches the wavelength of the optical signal to be transmitted and received from the operating wavelength to the spare wavelength when the wavelength variable subscriber device20and the facing wavelength variable communication device10are disconnected. Here, the spare wavelength is different from the operating wavelength. That is, the wavelength variable subscriber device20can execute the first protection for switching the wavelength of an optical signal to be transmitted and received to the spare wavelength different from the operating wavelength when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected.

As described above, the wavelength routing device30outputs the optical signals inputted to the ports #1-1, #1-2on the wavelength variable subscriber device20side to the ports #2-1to #2-M on the wavelength variable communication device10side according to the input/output characteristics shown inFIG.5. The input/output characteristics of the wavelength routing device30are set so that the output port when the operating wavelength is inputted to the port #1-1and the output port when the spare wavelength is inputted to the port #1-2are the same for each of the wavelength variable subscriber devices20. Therefore, when the wavelength of the optical signal to be transmitted and received by the wavelength variable subscriber device20is switched from the operating wavelength to the spare wavelength, if the second protection described later is not executed, the wavelength variable communication device10facing the wavelength variable subscriber device20is not changed, and the optical fiber transmission path50to be used can be switched from the normal path51to the redundant path52.

For example, when communication between the wavelength variable subscriber device20#1and the wavelength variable communication device10#1is disconnected, the wavelength variable subscriber device20#1executes the first protection, and thereby the wavelength variable subscriber device20#1switches the transmission/reception wavelength from the operating wavelength (λU_1and λD_1) to the spare wavelength (λU_2and λD_2). Then, according to the input/output characteristics ofFIG.5, the optical signals of the spare wavelengths (λU_2and λD_2) inputted/outputted to and from the port #1-2of the wavelength routing device30, are inputted/outputted from the port #2-1of the wavelength routing device30to the port #1-1of the optical distribution device100. Then, the optical signal inputted/outputted to and from the port #1-1of the optical distribution device100is inputted/outputted to and from the wavelength variable communication device101. Communication by the redundant path52can be started by switching the transmission and reception wavelength of the wavelength variable communication device10#1from the operating wavelength (λU_1and λD_1) to the spare wavelength (λU_2and λD_2).

Next, in the second protection, when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected, the optical distribution device100switches the connection destination of the disconnected wavelength variable subscriber device20to the wavelength variable communication device10different from the disconnected wavelength variable communication device10. For example, when communication between the wavelength variable subscriber device20#1and the wavelength variable communication device10#1is disconnected, the optical distribution device100executes the second protection and switches the connection destination of the port #1-1in the optical distribution device100to the port #2-2to switch the connection destination of the wavelength variable subscriber device20#1to the wavelength variable communication device10#2. Then, by setting the transmission and reception wavelength of the wavelength variable communication device10#2to the operating wavelength (λU_1and λD_1), the communication between the wavelength variable subscriber device20#1and the wavelength variable communication device10#2can be started.

Further, in the optical communication system of this embodiment, the third protection may be executable. In the third protection, as in the first embodiment, the optical distribution device100switches the signal transmission path200to be used when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected.

In the protection method of the optical communication system described above, at least the first step of executing the first protection and the second step of executing the second protection are executed in an arbitrary order. Further, the third step of executing the third protection described above may be provided, and in this case, the first step, the second step, and the third step are executed in an arbitrary order.

In the optical communication system and the protection method for the optical communication system of this embodiment, when the wavelength variable subscriber device20is disconnected from the wavelength variable communication device10, the first protection for switching the wavelength of the optical signal to be transmitted and received by the wavelength variable subscriber device20to a spare wavelength different from the operating wavelength and the second protection for switching the connection destination of the wavelength variable subscriber device20to the wavelength variable communication device10different from the disconnected wavelength variable communication device10can be executed.

By executing such first protection, the optical fiber transmission path50can be switched from the normal path51to the redundant path52to cope with the disconnection due to the abnormality or the like of the optical fiber transmission path50. Further, by executing the second protection, the wavelength variable communication device10facing the wavelength variable subscriber device20can be changed to a new one, and it is possible to cope with the disconnection due to the abnormality or the like of the facing wavelength variable communication device10.

Therefore, it is possible to cope with the disconnection due to the abnormality of both the wavelength variable communication device10and the optical fiber transmission path50. Therefore, in any cases of when the wavelength variable communication device10is single-unit disabled, the optical fiber transmission path50is single-unit disabled, or the wavelength variable communication device10and the optical fiber transmission path50are multiple disabled, the communication can be restarted within a short time period. Specifically, for example, in not only disconnection of an optical fiber transmission path50between the optical multiplexing/demultiplexing device40and the optical distribution device100, but also failure, function upgrade, maintenance, and the like of the wavelength variable communication device10, the communication disconnection time period can be shortened. Furthermore, the number of wavelength variable subscriber devices20to be protection target can be minimized. In other words, the optical communication system and the protection method for the optical communication system having the above-described structure can achieve the same effects as those of the first embodiment.

Further, in the optical communication system and the protection method for the optical communication system of this embodiment, the third protection for switching the signal transmission path200used for communication between the optical distribution device100and the wavelength routing device30may be executable when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected. By making it possible to execute such third protection, the communication path can be made redundant in addition to the optical fiber transmission path50between the optical multiplexing/demultiplexing device40and the optical distribution100, and also in the section between the optical distribution100and the wavelength routing device30.

Third Embodiment

The third embodiment of the present disclosure will be described with reference toFIG.6.FIG.6is a diagram schematically showing an entire configuration of the optical communication system.

In the third embodiment described here, the optical multiplexing/demultiplexing device on the wavelength variable subscriber device side is also changed to the wavelength routing device in the configuration of the second embodiment described above. The optical communication system and the protection method for the optical communication system according to the third embodiment will be described below mainly with respect to the difference from the second embodiment by taking the configuration of the second embodiment as an example. The structure in which the description is omitted is basically the same as that of the second embodiment.

As shown inFIG.6, the optical communication system according to this embodiment includes the plurality of wavelength variable communication devices10, the plurality of wavelength variable subscriber devices20, a first wavelength routing device31, a second wavelength routing device32and the optical distribution device100. In this embodiment, each of the wavelength variable communication devices10can change the wavelength of the optical signal to be transmitted. Each of the wavelength variable subscriber devices20can also change the wavelength of the optical signal to be transmitted.

The first wavelength routing device31is connected to each of the wavelength variable communication devices10. The second wavelength routing device32is connected to each of the wavelength variable subscriber devices20. The first wavelength routing device31and the second wavelength routing device32are connected by the plurality of optical fiber transmission paths50. In the example of the configuration described here, two of the normal path51and the redundant path52are laid as the plurality of optical fiber transmission paths50.

In this embodiment, the optical distribution device100is provided between the first wavelength routing device31and each of the wavelength variable communication devices10. The port on the wavelength variable subscriber device20side of the optical distribution device100is connected to the first wavelength routing device31via the plurality of signal transmission paths200. The port on the wavelength variable communication device10side of the optical distribution device100is connected to each of the wavelength variable communication devices10.

In the shown example of the configuration, for the wavelength variable communication device10side of the second wavelength routing device32, the port #1-1is connected to the normal path51of the optical fiber transmission path50, and the port #1-2is connected to the redundant path52of the optical fiber transmission path50. In addition, the ports #2-1, #2-2, . . . , #2-M on the wavelength variable subscriber device20side in the second wavelength routing device32are connected to the wavelength variable subscriber device20#1, the wavelength variable subscriber device20#2, . . . , the wavelength variable subscriber device20#M, respectively.

In addition, on the wavelength variable subscriber device20side of the first wavelength routing device31, the port #1-1is connected to the normal path51of the optical fiber transmission path50, and the port #1-2is connected to the redundant path52of the optical fiber transmission path50. The ports #2-1, #2-2, . . . , #2-M on the wavelength variable communication device10side in the first wavelength routing device31are connected to the port #1-1, #1-2, . . . , #1-M on the wavelength variable subscriber device20in the optical distribution device100by M signal transmission paths200, respectively. Then, the ports #2-1, #2-2, . . . , #2-N on the wavelength variable communication device10side in the optical distribution device100are connected to the wavelength variable communication device10#1, the wavelength variable communication device10#2, . . . , the wavelength variable communication device10#N, respectively.

The optical distribution device100outputs the optical signals inputted from the respective ports to the port in which a connection relation is set as a connection port to the port. The connection relation between the ports in the optical distribution device100can be arbitrarily changed and set.

The first wavelength routing device31outputs the optical signals inputted to the ports #1-1, #1-2on the wavelength variable subscriber device20side to the ports uniquely determined by a combination of the wavelength of the optical signal and the port to which the optical signal is inputted on the wavelength variable communication device10side. Further, the first wavelength routing device31outputs the optical signals inputted to each of the ports #2-1to #2-M on the wavelength variable communication device10side to the ports uniquely determined by a combination of the wavelength of the optical signal and the port to which the optical signal is inputted on the wavelength variable subscriber device20side.

The second wavelength routing device32outputs the optical signals inputted to the ports #1-1, #1-2on the wavelength variable communication device10side to the ports uniquely determined by a combination of the wavelength of the optical signal and the port to which the optical signal is inputted on the wavelength variable subscriber device20side. Further, the second wavelength routing device32outputs the optical signals inputted to each of the ports #2-1to #2-M on the wavelength variable subscriber device20side to the ports uniquely determined by a combination of the wavelength of the optical signal and the port to which the optical signal is inputted on the wavelength variable communication device10side. In this case, the input/output characteristics of the first wavelength routing device31and the second wavelength routing device32are the same as those shown inFIG.5described in the second embodiment, for example.

Next, the protection when communication between the wavelength variable subscriber device20and the wavelength variable communication device10is disconnected in the optical communication system of this embodiment will be described. In the optical communication system of this embodiment, the first protection and the second protection can be executed.

First, in the first protection, the wavelength variable subscriber device20and the wavelength variable communication device10switches the wavelength of an optical signal to be transmitted from the operating wavelength to a spare wavelength, when communication between the wavelength variable subscriber device20and the wavelength variable communication device10is disconnected. Here, the spare wavelength is different from the operating wavelength. That is, the wavelength variable subscriber device20and the wavelength variable communication device10can execute the first protection for switching the wavelength of the optical signal transmitted by each of them to the spare wavelength different from the operating wavelength when the communication is disconnected.

As described above, the first wavelength routing device31outputs the optical signals inputted to the port #1-1, #1-2on the wavelength variable subscriber device20side to the port #2-1to #2-M on the wavelength variable communication device10side according to the input/output characteristics shown inFIG.5. The input/output characteristics of the first wavelength routing device31are set so that the output port when the operating wavelength is inputted to the port #1-1and the output port when the spare wavelength is inputted to the port #1-2are the same for each of the wavelength variable subscriber devices20. Therefore, when the transmission and reception wavelengths of the wavelength variable subscriber device20and the wavelength variable communication device10are switched from the operating wavelength to the spare wavelength, the optical fiber transmission path50to be used can be switched from the normal path51to the redundant path52without changing the connection relation between the wavelength variable subscriber device20and the wavelength variable communication device10in the case of when the second protection described later is not executed.

For example, when communication between the variable wavelength subscriber device20#1and the variable wavelength communication device10#1is disconnected, the variable wavelength subscriber device20#1and the variable wavelength communication device10#1execute the first protection, thereby switching the transmission and reception wavelengths of both from the operating wavelength (λU_1and λD_1) to the spare wavelength (λU_2and λD_2). According to the input/output characteristics ofFIG.5, the optical signals of the spare wavelength (λU_2and λD_2) inputted and outputted from the wavelength variable subscriber device20#1to the port #2-1of the second wavelength routing device32are inputted and outputted from the port #1-2of the second wavelength routing device32to the redundant path52. On the other hand, the optical signals of the spare wavelength (λU_2and λD_2) inputted and outputted from the redundant path52to the port #1-2of the first wavelength routing device31are inputted and outputted from the port #2-1of the first wavelength routing device31to the port #1-1of the optical distribution device100. Then, the optical signal inputted and outputted to and from the port #1-1of the optical distribution device100is inputted and outputted to and from the wavelength variable communication device10#1. Therefore, communication by the redundant path52can be started between the wavelength variable subscriber device20#1and the wavelength variable communication device10#1.

Next, in the second protection, when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected, the optical distribution device100switches the disconnected connection destination of the wavelength variable subscriber device20to the wavelength variable communication device10different from the disconnected wavelength variable communication device10. For example, when communication between the wavelength variable subscriber device20#1and the wavelength variable communication device10#1is disconnected, the optical distribution device100executes the second protection and switches the connection destination of the port #1-1in the optical distribution device100to the port #2-2to switch the connection destination of the wavelength variable subscriber device20#1to the wavelength variable communication device10#2. Then, by setting the transmission and reception wavelength of the wavelength variable communication device10#2to the operating wavelength (λU_1and λD_1), the communication between the wavelength variable subscriber device20#1and the wavelength variable communication device10#2can be started.

In the protection method of the optical communication system described above, at least the first step of executing the first protection and the second step of executing the second protection are executed in an arbitrary order.

In the optical communication system and the protection method for the optical communication system of this embodiment, when the wavelength variable subscriber device20and the wavelength variable communication device10are disconnected, the first protection for switching the wavelength of then optical signal transmitted by each of the wavelength variable subscriber device20and the wavelength variable communication device10to the spare wavelength different from the operating wavelength, and the second protection for switching the connection destination of the wavelength variable describer device20to the wavelength variable communication device10different from the disconnected wavelength variable communication device10are executable.

By executing such first protection, the optical fiber transmission path50can be switched from the normal path51to the redundant path52to cope with the disconnection due to the abnormality or the like of the optical fiber transmission path50. Further, by executing the second protection, the wavelength variable communication device10facing the wavelength variable subscriber device20can be changed to a new one, and it is possible to cope with the disconnection due to the abnormality or the like of the facing wavelength variable communication device10.

Therefore, it is possible to cope with the disconnection due to the abnormality of both the wavelength variable communication device10and the optical fiber transmission path50. Therefore, in any case of the case when the wavelength variable communication device10is single-unit disabled, the optical fiber transmission path50is single-unit disabled, or the wavelength variable communication device10and the optical fiber transmission path50are multiple disabled, the communication can be restarted in a short time period. Specifically, for example, in not only disconnection of an optical fiber transmission path50between the second wavelength routing device32and the optical distribution device100, but also failure, function upgrade, maintenance, and the like of the wavelength variable communication device10, the communication disconnection time period can be shortened. Furthermore, the number of wavelength variable subscriber devices20to be protection target can be minimized. That is, the optical communication system and the protection method for the optical communication system having the above described configuration can achieve the same effects as those of the second embodiment.

INDUSTRIAL APPLICABILITY

The present disclosure can be used for the optical communication system and the protection method of the optical communication system, which perform communication between the plurality of wavelength variable communication devices and the plurality of wavelength variable subscriber devices via the plurality of optical fiber transmission paths.

REFERENCE SIGNS LIST

10Wavelength variable communication device20Wavelength variable subscriber device30Wavelength routing device31First wavelength routing device32Second wavelength routing device40Optical multiplexing/demultiplexing device50Optical fiber transmission path51Normal path52Redundant path100Optical distribution device200Signal transmission path201First signal transmission path202Second signal transmission path