Abstract:
An optical signal transmitted by another terminal device that was used for compensation could be received by a device that is not the intended destination of said optical signal, resulting in the problem that confidentiality cannot be guaranteed for the information in said optical signal. This optical reception device is characterized by the provision of the following: a receiving means via which wavelength-multiplexed signal light is inputted; and a transmitting means that, in accordance with an identifier in an optical signal of a prescribed wavelength in the inputted wavelength-multiplexed signal light, forwards said optical signal.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an optical reception apparatus, an optical transmission apparatus, an optical communication system, an optical communication method, and a storage medium storing a program. 
       BACKGROUND ART 
       [0002]    In recent years, as the traffic increases, it is desired to increase the bandwidth of the circuit (line) and achieve higher functionality of the network in the undersea cable system. Therefore, techniques such as OADM (Optical Add-Drop Multiplexer) and ROADM (Reconfigurable Optical Add-Drop Multiplexer) are applied to the undersea cable system. 
         [0003]    In the undersea ROADM system, a Wavelength Division Multiplexing (WDM) communication is used, and, for example, a transmission apparatus inputs a client signal as a wavelength multiplexed optical signal into an undersea cable, and multiple paths are accommodated in a single optical fiber, so that the flexibility of the network is improved. 
         [0004]    In the undersea cable system having the OADM function, the total power of the signal transmitted in the cable constituted by an optical fiber is configured to be at a constant level, and in a case where some of the wavelength component of the signal is lost because, e.g., the cable is disconnected, the other wavelength components of the signal is amplified, so that the total power of the signal is maintained at a constant level. 
         [0005]    However, when the power of only a particular wavelength component of the signal is increased, and the power becomes equal to or more than a predetermined value, a change occurs in the optical spectrum because of, e.g., degradation of the waveform of the signal due to nonlinear effect of the optical fiber, and the transmission quality of the signal is degraded. 
         [0006]    An optical communication system described in PTL 1 relates to a technique for ensuring the communication quality by correcting the total power of the signal with dummy light in a case where a fault occurs in a cable. In the optical communication system described in PTL 1, a terminal apparatus (optical transmission apparatus) includes a dummy light generation unit generating dummy light according to a portion where optical signal disconnection occurs, so that the strength (the power) of the transmitted signal is maintained at a constant level, in a case where a fault of cable disconnection occurs. 
       CITATION LIST 
     Patent Literature 
     [PTL 1] Japanese Patent Laid-Open No. 2010-98547 
     SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    As described above, the terminal apparatus (optical transmission apparatus) described in PTL 1 needs to generate dummy light in order to compensate the optical signal, and is required to have the dummy optical generation unit. 
         [0008]    Therefore, in order to compensate the optical signal without providing the dummy optical generation unit in the terminal apparatus (optical transmission apparatus), the lost optical signal may be considered to be compensated by the optical signal transmitted from another terminal apparatus. However, there is a problem in that, when the optical signal transmitted from another terminal apparatus used for the compensation is received by an apparatus which is not the authentic recipient of the optical signal, the confidentiality of the information included in the optical signal cannot be ensured. 
         [0009]    It is an object of the present invention to solve the above problems, and to provide an optical reception apparatus, an optical transmission apparatus, an optical communication system, an optical communication method, and a storage medium storing a program which can prevent an optical signal from being transferred to an apparatus that is not the intended transmission destination apparatus and can ensure the confidentiality of information included in the optical signal. 
       Solution to Problem 
       [0010]    An optical reception apparatus according to the present invention comprises: reception means for receiving wavelength multiplexed signal light; and transmission means for transferring an optical signal of a predetermined wavelength in accordance with an identifier included in the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light. 
         [0011]    An optical transmission apparatus according to present invention comprises: reception means for receiving an optical signal of a predetermined wavelength; transmission means for incorporating an identifier uniquely identifying the optical transmission apparatus into the optical signal of the predetermined wavelength received by the reception means, and transmitting the optical signal; and multiplex means for multiplexing and outputting the optical signal including the identifier and an optical signal of a wavelength different from the predetermined wavelength. 
         [0012]    An optical communication system according to the present invention comprises: an optical transmission apparatus including a first reception means for receiving an optical signal of a predetermined wavelength, a first transmission means for incorporating an identifier uniquely identifying the optical transmission apparatus into the optical signal of the predetermined wavelength received by the first reception means, and transmitting the optical signal, and a multiplex means for multiplexing and outputting the optical signal including the identifier and an optical signal of a wavelength different from the predetermined wavelength; and an optical reception apparatus including a second reception means for receiving wavelength multiplexed signal light transmitted by the optical transmission apparatus, and a second transmission means for transferring the optical signal of the predetermined wavelength in accordance with the identifier included in the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light. 
         [0013]    An optical communication method according to the present invention comprises: receiving wavelength multiplexed signal light; and transferring an optical signal of a predetermined wavelength in accordance with an identifier included in the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light. 
         [0014]    A storage medium according to the present invention stores a program for causing a computer to execute: processing for receiving wavelength multiplexed signal light; and processing for transferring optical signal of the predetermined wavelength in accordance with the identifier included in the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light. 
       Advantageous Effects of Invention 
       [0015]    The present invention has an advantage in that, in an optical reception apparatus, an optical transmission apparatus, an optical communication system, an optical communication method, and a storage medium storing a program, an optical signal is prevented from being transferred to an apparatus that is not the intended transmission destination apparatus, and the confidentiality of information included in the optical signal can be ensured. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0016]      FIG. 1  is a figure illustrating an example of a configuration of an optical communication system according to a first exemplary embodiment of the present invention. 
           [0017]      FIG. 2  is a figure illustrating an example of a configuration of the optical reception apparatus according to the first exemplary embodiment of the present invention. 
           [0018]      FIG. 3  is a flowchart illustrating an example of operation of the optical reception apparatus according to the first exemplary embodiment of the present invention. 
           [0019]      FIG. 4  is a figure illustrating an example of a configuration of an optical reception apparatus according to a second exemplary embodiment of the present invention. 
           [0020]      FIG. 5  is a flowchart illustrating an example of operation of the optical reception apparatus according to the second exemplary embodiment of the present invention. 
           [0021]      FIG. 6  is a figure illustrating another example of a configuration of the optical reception apparatus according to the second exemplary embodiment of the present invention. 
           [0022]      FIG. 7  is a flowchart illustrating another example of operation of the optical reception apparatus according to the second exemplary embodiment of the present invention. 
           [0023]      FIG. 8  is a figure illustrating another example of a configuration of an optical reception apparatus according to a third exemplary embodiment of the present invention. 
           [0024]      FIG. 9  is a flowchart illustrating another example of operation of the optical reception apparatus according to the third exemplary embodiment of the present invention. 
           [0025]      FIG. 10  is a figure illustrating an example of a configuration of an optical transmission apparatus according to a fourth exemplary embodiment of the present invention. 
           [0026]      FIG. 11  is a flowchart illustrating an example of operation of the optical transmission apparatus according to the fourth exemplary embodiment of the present invention. 
           [0027]      FIG. 12  is a figure illustrating an example of a configuration of an optical transmission apparatus according to the fifth exemplary embodiment of the present invention. 
           [0028]      FIG. 13  is a flowchart illustrating an example of operation of the optical transmission apparatus according to the fifth exemplary embodiment of the present invention. 
           [0029]      FIG. 14  is a figure illustrating an example of a configuration of an optical communication system according to a sixth exemplary embodiment of the present invention. 
           [0030]      FIG. 15  is a figure illustrating an example of a configuration of the terminal apparatus according to the sixth exemplary embodiment of the present invention. 
           [0031]      FIG. 16  is a figure illustrating an example of a configuration of a transponder according to the sixth exemplary embodiment of the present invention. 
           [0032]      FIG. 17  is a table illustrating a connection relationship of transponders of each base station and a used wavelength according to the sixth exemplary embodiment of the present invention. 
           [0033]      FIG. 18  is a table illustrating transponders provided in each base station, an identifier of the transponder, and an identifier of a transponder with which the transponder is communicating, according to the sixth exemplary embodiment of the present invention. 
           [0034]      FIG. 19  is a sequence diagram illustrating an example of operation of the transponder according to the sixth exemplary embodiment of the present invention. 
           [0035]      FIG. 20  is a sequence diagram illustrating another example of operation of the transponder according to the sixth exemplary embodiment of the present invention. 
           [0036]      FIG. 21  is a figure illustrating another example of a configuration of the transponder according to the sixth exemplary embodiment of the present invention. 
           [0037]      FIG. 22  is a figure illustrating an example of a configuration of a transponder according to a seventh exemplary embodiment of the present invention. 
           [0038]      FIG. 23  is a sequence diagram illustrating an example of operation of the transponder according to the seventh exemplary embodiment of the present invention. 
           [0039]      FIG. 24  is a figure illustrating another example of a configuration of the transponder according to the seventh exemplary embodiment of the present invention. 
           [0040]      FIG. 25  is a figure illustrating an example of a configuration of a transponder according to an eighth exemplary embodiment of the present invention. 
           [0041]      FIG. 26  is a sequence diagram illustrating an example of operation of the transponder according to the eighth exemplary embodiment of the present invention. 
           [0042]      FIG. 27  is a figure illustrating an example of a configuration of a communication system before a fault occurs in a transmission path, according to a ninth exemplary embodiment of the present invention. 
           [0043]      FIG. 28  is a table illustrating a connection relationship of transponder before a fault that has occurred in a transmission path, according to the ninth exemplary embodiment of the present invention. 
           [0044]      FIG. 29  is a figure illustrating an example of a configuration of a communication system after a fault that has occurred in a transmission path, according to the ninth exemplary embodiment of the present invention. 
           [0045]      FIG. 30  is a figure illustrating a table illustrating another connection relationship of a transponder after a fault that has occurred in a transmission path according to the ninth exemplary embodiment of the present invention. 
           [0046]      FIG. 31  is a table illustrating a connection relationship of a transponder after a connection relationship is changed, according to the ninth exemplary embodiment of the present invention. 
           [0047]      FIG. 32  is a figure illustrating an example of a configuration of an optical communication system according to a tenth exemplary embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Exemplary Embodiment 
       [0048]    Overview of the first exemplary embodiment of the present invention will be explained with reference to drawings. It should be noted that the reference symbols in the drawings appended to this overview are attached to the elements as an example for the sake of convenience in order to help understanding, and are not intended to limit, in any way, the description of this overview. 
         [0049]      FIG. 1  is an example of a configuration of an optical communication system according to the first exemplary embodiment of the present invention. As shown in  FIG. 1 , the optical communication system includes an optical reception apparatus  1 - 1  receiving a wavelength multiplexed signal light, an optical transmission apparatus  1 - 2  transmitting wavelength multiplexed signal light, and an optical transmission and reception apparatus  1 - 3  transmitting and receiving wavelength multiplexed signal light. Further, the optical communication system includes a transmission path  20  transmitting wavelength multiplexed signal light and a BU (Branch Unit: optical branch apparatus)  30  multiplexing and branching wavelength multiplexed signal light. 
         [0050]      FIG. 2  is a figure illustrating an example of a configuration of an optical reception apparatus  1 - 1 . The optical reception apparatus  1 - 1  includes a reception unit  11  and a transmission unit  12 . 
         [0051]    The reception unit  11  receives the wavelength multiplexed signal light from the transmission path  20 . Besides, the transmission unit  12  transfers an optical signal of a predetermined wavelength in the wavelength multiplexed signal light received by the reception unit  11  in accordance with an identifier included in the optical signal of the predetermined wavelength. 
         [0052]      FIG. 3  is a flowchart illustrating an example of operation of the optical reception apparatus  1 - 1  according to the first exemplary embodiment of the present invention. 
         [0053]    The reception unit  11  receives the wavelength multiplexed signal light received from the transmission path  20  (S 101 ). 
         [0054]    The transmission unit  12  transfers an optical signal of a predetermined wavelength in the wavelength multiplexed signal light received by the reception unit  11  in accordance with an identifier included in the optical signal of the predetermined wavelength (S 102 ). 
         [0055]    As described above, the optical reception apparatus  1 - 1  of the first exemplary embodiment of the present invention transfers the optical signal of the predetermined wavelength in accordance with the identifier included in the optical signal of the predetermined wavelength, and therefore, in a case where the optical signal is not the apparatus of the intended transmission destination, the optical signal is not transferred to an apparatus in a subsequent stage. Accordingly, this can prevent the optical signal from being transferred to an apparatus that is not the intended transmission destination, and the confidentiality of the information included in the optical signal can be ensured. 
       Second Exemplary Embodiment 
       [0056]    Overview of the second exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0057]    The example of a configuration of the optical communication system according to the second exemplary embodiment of the present invention is the same as that of  FIG. 1 . 
         [0058]      FIG. 4  is a figure illustrating an example of a configuration of the optical reception apparatus  1 - 1 . The configuration of optical reception apparatus  1 - 1  includes a transmission unit  12 , a comparison unit  13 , a storage unit  14 , an input unit  15 , and a demultiplexing unit  16 . 
         [0059]    The demultiplexing unit  16  demultiplexes the wavelength multiplexed signal light received from the transmission path  20 , and outputs the optical signal of the predetermined wavelength according to the input unit  15  to the input unit  15 . 
         [0060]    The reception unit  15  converts the optical signal received from the demultiplexing unit  16  into an electric signal, and outputs the electric signal to the comparison unit  13 . 
         [0061]    The comparison unit  13  compares an identifier (comparison information) stored in the storage unit  14  in advance and an identifier included in the electric signal which is received from the reception unit  15 . The comparison unit  13  outputs the electric signal to the transmission unit  12  in accordance with agreement between the identifier included in the electric signal and the comparison information. In contrast, the comparison unit  13  discards the electric signal in accordance with disagreement between the identifier included in the electric signal and the comparison information. 
         [0062]    The storage unit  14  stores, in advance, the identifier of the optical transmission apparatus  1 - 2  with which communication is to be performed, as the comparison information. 
         [0063]    The transmission unit  12  converts the electric signal received from the comparison unit  13  into an optical signal, and transfers the optical signal to the apparatus in a subsequent stage. 
         [0064]      FIG. 5  is a flowchart illustrating an example of operation of the optical reception apparatus  1 - 1  according to the second exemplary embodiment of the present invention. 
         [0065]    The demultiplexing unit  16  demultiplexes the received wavelength multiplexed signal light, and outputs the optical signal of the predetermined wavelength according to the input unit  15  to the input unit  15  (S 201 ). 
         [0066]    The input unit  15  converts the received optical signal into an electric signal, and outputs the electric signal into the comparison unit  13  (S 202 ). 
         [0067]    The comparison unit  13  compares the identifier (comparison information) stored in the storage unit  14  in advance and the identifier included in the electric signal received from the reception unit  15 , and outputs the electric signal to the transmission unit  12  (S 204 ) in accordance with agreement between both of the identifiers (YES in S 203 ). In contrast, the comparison unit  13  discards the electric signal (S 205 ) in accordance with disagreement between both of the identifiers (NO in S 203 ). 
         [0068]    The transmission unit  12  converts the electric signal received from the comparison unit  13  into the optical signal, and outputs the optical signal to the apparatus in a subsequent stage (S 206 ). 
         [0069]      FIG. 6  is a figure illustrating another example of a configuration of the optical reception apparatus  1 - 1 . The optical reception apparatus  1 - 1  has a branch unit  17  in place of the demultiplexing unit  16 . 
         [0070]    The branch unit  17  branches the wavelength multiplexed signal light received from the transmission path  20 , and outputs the wavelength multiplexed signal light to the input unit  15 . 
         [0071]    The input unit  15  selectively receives only the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light, converts the optical signal into an electric signal, and outputs the electric signal to the comparison unit  13 . In this case, the means for selectively receiving only the optical signal of the predetermined wavelength is, for example, means for receiving the light by causing the light of the wavelength, which is to be received, to interfere with the wavelength multiplexed signal light, such as, e.g., digital coherent reception. 
         [0072]      FIG. 7  is a flowchart illustrating another example of operation of the optical reception apparatus  1 - 1  according to the second exemplary embodiment of the present invention. 
         [0073]    The branch unit  17  branches the received wavelength multiplexed signal light, and outputs the wavelength multiplexed signal light to the input unit  15  (S 301 ). 
         [0074]    The input unit  15  selectively receives only the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light, converts the optical signal into an electric signal, and outputs the electric signal to the comparison unit  13  (S 302 ). 
         [0075]    It should be noted that, in  FIG. 7 , the processing in step  303  (S 303 ) to step  306  (S 306 ) is the same processing as the processing in step  203  (S 203 ) to step  206  (S 206 ) of  FIG. 5 . 
         [0076]    As described above, the optical reception apparatus  1 - 1  according to the second exemplary embodiment of the present invention compares the identifier included in the optical signal of the predetermined wavelength and the identifier (comparison information) stored in the storage unit  14 , and in a case where the identifiers of them both match each other, the optical reception apparatus  1 - 1  transfers the optical signal, and in a case where the identifiers of them both do not match each other, the optical reception apparatus  1 - 1  discards the optical signal in question. Therefore, in a case where the transmission destination of the optical signal is not the apparatus of the intended transmission destination, the optical reception apparatus  1 - 1  does not transfer the optical signal to the apparatus in a subsequent stage. Hence, this can prevent the optical signal from being transferred to an apparatus that is not the intended transmission destination, and the confidentiality of the information included in the optical signal can be ensured. 
       Third Exemplary Embodiment 
       [0077]    Overview of the third exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0078]      FIG. 8  is a figure illustrating an example of a configuration of the optical reception apparatus  1 - 1 . The optical reception apparatus  1 - 1  includes a transmission unit  12 , a comparison unit  13 , a storage unit  14 , an input unit  15 , a demultiplexing unit  16 , and a pattern generation unit  18 . 
         [0079]    It should be noted that the optical reception apparatus  1 - 1  may be the branch unit  17  in place of the demultiplexing unit  16 , but in the following explanation, a case where the optical reception apparatus  1 - 1  is the demultiplexing unit  16  will be explained as an example. 
         [0080]    The comparison unit  13  compares the identifier (comparison information) stored in advance in the storage unit  14  and the identifier included in the electric signal received from the input unit  15 . 
         [0081]    Further, in a case where the identifier included in the electric signal and the comparison information match each other, the comparison unit  13  outputs the electric signal to the transmission unit  12 . In contrast, in a case where the identifier included in the electric signal and the comparison information do not match each other, the comparison unit  13  outputs a notification signal including information indicating disagreement to the pattern generation unit  18 . 
         [0082]    In a case where the pattern generation unit  18  receives the notification signal from the comparison unit  13 , the pattern generation unit  18  generates an electric signal including a dummy pattern in which 0 and 1 are randomly arranged or a fixed pattern in which 0 and 1 are arranged in a particular pattern, and outputs the electric signal thus generated to the transmission unit  12 . 
         [0083]    In a case where the transmission unit  12  receives the electric signal from the comparison unit  13 , the transmission unit  12  converts the electric signal received from the comparison unit  13  into an optical signal, and outputs the optical signal to the apparatus in a subsequent stage. In contrast, in a case where the transmission unit  12  receives an electric signal including a dummy pattern or a fixed pattern from the pattern generation unit  18 , the transmission unit  12  converts, into an optical signal, the electric signal including the dummy pattern or the fixed pattern received from the pattern generation unit  18 , and outputs the optical signal to the apparatus in a subsequent stage. 
         [0084]    Here, in this case, instead of the generation of the dummy pattern and the fixed pattern, the pattern generation unit  18  may serve as a scrambler to randomly interchange the bit string of the electric signal received from the comparison unit  13  to the transmission unit  12 . 
         [0085]      FIG. 9  is a flowchart illustrating another example of operation of the optical reception apparatus  1 - 1  according to the third exemplary embodiment of the present invention. 
         [0086]    The demultiplexing unit  16  demultiplexes the received wavelength multiplexed signal light, and outputs the optical signal according to the input unit  15  to the input unit  15  (S 401 ). 
         [0087]    The input unit  15  converts the received optical signal into an electric signal, and outputs the electric signal to the comparison unit  13  (S 402 ). 
         [0088]    The comparison unit  13  compares the identifier (comparison information) stored in advance in the storage unit  14  and the identifier included in the electric signal received from the reception unit  15 , and in a case where the identifier included in the electric signal and the comparison information match each other (YES in S 403 ), the comparison unit  13  outputs the electric signal to the transmission unit  12  (S 404 ). The transmission unit  12  converts the electric signal received from the comparison unit  13  into an optical signal, and outputs the optical signal to the apparatus in a subsequent stage (S 405 ). 
         [0089]    In contrast, in a case where the identifier included in the electric signal and the comparison information do not match each other (NO in S 403 ), the comparison unit  13  outputs the notification signal including the information indicating disagreement to the pattern generation unit  18  (S 406 ). In a case where the pattern generation unit  18  receives the notification signal from the comparison unit  13 , the pattern generation unit  18  generates an electric signal including a dummy pattern in which 0 and 1 are randomly arranged or a fixed pattern in which 0 and 1 are arranged in a particular pattern, and outputs the electric signal to the transmission unit  12  (S 407 ). In a case where the transmission unit  12  receives the electric signal, the transmission unit  12  converts the electric signal received from the comparison unit  13  into an optical signal, and outputs the optical signal to the apparatus in a subsequent stage (S 408 ). 
         [0090]    As described above, in a case where the comparison result of the comparison unit  13  indicates disagreement, the optical reception apparatus  1 - 1  of the third exemplary embodiment of the present invention outputs, instead of the received optical signal, an optical signal obtained by randomly interchanging the dummy pattern, the fixed pattern, or the bit string to the apparatus in a subsequent stage. Therefore, this can prevent the optical signal from being transferred to an apparatus that is not the intended transmission destination, and the confidentiality of the information included in the optical signal can be ensured. 
       Fourth Exemplary Embodiment 
       [0091]    The fourth exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0092]      FIG. 10  is a figure illustrating an example of a configuration of the optical transmission apparatus  1 - 2 . The optical transmission apparatus  1 - 2  includes a reception unit  21 , an output unit  23 , and a multiplex unit  25 . 
         [0093]    The reception unit  21  receives an optical signal of a predetermined wavelength. Besides, the output unit  23  incorporates an identifier uniquely identifying the optical transmission apparatus  1 - 2  into the optical signal of the predetermined wavelength received by the reception unit  21 , and transmits the optical signal. It should be noted that the identifier may be an identifier uniquely identifying the output unit  23 . Further, the multiplex unit  25  multiplexes the optical signal including the identifier and an optical signal of a wavelength different from the optical signal received by the reception unit  21 , and outputs the multiplexed optical signal to the transmission path  20 . 
         [0094]      FIG. 11  is a flowchart illustrating an example of operation of the optical transmission apparatus  1 - 2  according to the fourth exemplary embodiment of the present invention. 
         [0095]    The reception unit  21  receives the optical signal of the predetermined wavelength (S 501 ). 
         [0096]    The output unit  23  incorporates an identifier uniquely identifying the optical transmission apparatus  1 - 2  into the optical signal of the predetermined wavelength received by the reception unit  21 , and transmits the optical signal (S 502 ). Then, the multiplex unit  25  multiplexes the optical signal including the identifier and an optical signal of a wavelength different from the optical signal received by the reception unit  21 , and outputs the optical signal (S 503 ). 
         [0097]    As described above, the optical transmission apparatus  1 - 2  according to the fourth exemplary embodiment of the present invention incorporates the identifier uniquely identifying the optical transmission apparatus  1 - 2  (or output unit  23 ) into the optical signal, which is to be transmitted, and transmits the optical signal. Therefore, the optical reception apparatus  1 - 1  receiving the transmitted optical signal can determine whether to transfer the optical signal of the predetermined wavelength or not in accordance with the identifier included in the optical signal, and this can prevent the optical signal from being transferred to an apparatus that is not the intended transmission destination. 
       Fifth Exemplary Embodiment 
       [0098]    Overview of the fifth exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0099]      FIG. 12  is a figure illustrating an example of a configuration of the optical transmission apparatus  1 - 2 . The optical transmission apparatus  1 - 2  includes a reception unit  21 , an output unit  23 , an insertion unit  24 , and a multiplex unit  25 . 
         [0100]    The output unit  23  incorporates the identifier notified by the insertion unit  24  into the optical signal of the predetermined wavelength received by the reception unit  21 , and outputs the optical signal to the multiplex unit  25 . 
         [0101]    The insertion unit  24  notifies the output unit  23  of the identifier uniquely identifying the optical transmission apparatus  1 - 2 . It should be noted that the identifier may also be the identifier uniquely identifying the output unit  23 . 
         [0102]    The multiplex unit  25  transmits the optical signal received from the output unit  23  to the transmission path  20 . It should be noted that the multiplex unit  25  multiplexes the optical signals of wavelengths different from each other received from multiple output units  23 , and transmits the multiplexed optical signal as the wavelength multiplexed signal light. 
         [0103]      FIG. 13  is a flowchart illustrating an example of operation of the optical transmission apparatus  1 - 2  according to the fifth exemplary embodiment of the present invention. 
         [0104]    The reception unit  21  receives the optical signal of the predetermined wavelength (S 601 ). 
         [0105]    The output unit  23  incorporates the identifier that has been notified from the insertion unit  24  into the optical signal of the predetermined wavelength received by the reception unit  21 , and outputs the optical signal to the multiplex unit  25  (S 602 ). 
         [0106]    The multiplex unit  25  multiplexes the optical signal including the identifier and an optical signal of a wavelength different from the optical signal received by the reception unit  21 , and outputs the multiplexed optical signal (S 603 ). 
         [0107]    As described above, the optical transmission apparatus  1 - 2  according to the fifth exemplary embodiment of the present invention incorporates the identifier that has been notified from the insertion unit  24  into the optical signal which is to be transmitted, and transmits the optical signal. Therefore, the optical reception apparatus  1 - 1  receiving the transmitted optical signal can determine whether to transfer the optical signal of the predetermined wavelength in accordance with the identifier included in the optical signal, and this can prevent the optical signal from being transferred to an apparatus that is not the intended transmission destination. 
       Sixth Exemplary Embodiment 
       [0108]    The sixth exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0109]      FIG. 14  is a figure illustrating an example of a configuration of a communication system according to the sixth exemplary embodiment of the present invention. 
         [0110]    As shown in  FIG. 14 , the communication system according to the sixth exemplary embodiment of the present invention includes an A base station  10 - 1 , a B base station  10 - 2 , a C base station  10 - 3 , and a D base station  10 - 4  (hereinafter referred to as a “base station  10 ” in a case where it is not particularly necessary to distinguish them from each other). 
         [0111]    Each of the base stations  10  is connected with an adjacent base station  10  via the transmission path  20 . Further, the base stations  10  are connected with each other via a BU (optical branch apparatus)  30 . 
         [0112]    The transmission path  20  is constituted by bundling multiple optical fibers. 
         [0113]    The BU  30  is an OADM-BU, and inserts or branches (Add/Drop) an optical signal of a predetermined wavelength in the wavelength multiplexed optical signal transmitted through the transmission path  20 . 
         [0114]      FIG. 15  is a figure illustrating an example of a configuration of the terminal apparatus  40  according to the sixth exemplary embodiment of the present invention. 
         [0115]    As shown in  FIG. 14 , the base station  10  includes a terminal apparatus  40  and a client apparatus  50 . The terminal apparatus  40  of the base station  10  includes transponders (Transponders)  41 - 1  to  41 - 5  (hereinafter referred to as a “transponder  41 ” in a case where it is not particularly necessary to distinguish from each other) and a wavelength separation multiplex unit  51 . 
         [0116]    The wavelength separation multiplex unit  51  performs wavelength multiplexing to multiplex multiple optical signals received from multiple client apparatuses  50 , and transmits the multiplexed signal as a WDM signal. Further, the wavelength separation multiplex unit  51  demultiplexes a WDM signal from an opposed base station  10 , and outputs the signal of each wavelength (wavelength band) to the transponder  41 . 
         [0117]    The transponder  41  performs predetermined processing on the optical signal received from the client apparatus  50 , and outputs the processed optical signal to the wavelength separation multiplex unit  51 . Further, the transponder  41  transmits the optical signal received from the wavelength separation multiplex unit  51  to the client apparatus  50  on the basis of the predetermined condition. 
         [0118]      FIG. 16  is a figure illustrating an example of a configuration of the transponder  41 . As shown in  FIG. 16 , the transponder  41  includes a client module  42 , a Framer LSI  43 , an insertion unit  44 , a line module  45 , a comparison unit  46 , and a storage unit  47 . 
         [0119]    First, the case where the transponder  41  transmits the optical signal will be explained. 
         [0120]    The client module  42  converts the optical signal received from the client apparatus  50  into an electric signal, and outputs the electric signal, as a client reception signal, to the Framer LSI  43 . 
         [0121]    The Framer LSI  43  accommodates the client signal received from the client module  42  into a line signal frame, stores an identifier for uniquely identifying the transponder  41  obtained from the insertion unit  44 , and outputs the line signal frame to the line module  45 . The Framer LSI  43  stores, in a predetermined area of the header of the line signal frame, the MAC address and the IP address of the transponder  43  as the identifier. 
         [0122]    The insertion unit  44  notifies an identifier uniquely identifying the transponder  41  to the Framer LSI  43 . In response to a request from the Framer LSI  43 , the insertion unit  44  notifies the identifier. 
         [0123]    The line module  45  converts the electric signal which is output by the Framer LSI  43  (i.e., line signal frame) into the optical signal of the predetermined wavelength, and outputs the optical signal to the wavelength separation multiplex unit  51 . 
         [0124]    Subsequently, a case where the transponder  41  receives the optical signal will be explained. 
         [0125]    The line module  45  converts the line reception signal (optical signal) received from the wavelength separation multiplex unit  51  into an electric signal, and outputs the electric signal into the Framer LSI  43 . 
         [0126]    The Framer LSI  43  extracts a client signal from the line signal frame received from the line module  45 , and outputs the client signal to the client module  42  as an electric signal. Further, the Framer LSI  43  extracts the identifier stored in the predetermined area of the header of the line signal frame, and notifies the extracted identifier to the comparison unit  46 . 
         [0127]    The comparison unit  46  refers to the storage unit  47  and determines whether the identifier that has been notified from the Framer LSI  43  and the stored identifier (comparison information) match each other or not. More specifically, the comparison unit  46  determines whether the optical signal (line signal frame) received by the transponder  41  is an optical signal transmitted from an apparatus with which the apparatus in question is to communicate (the transponder  41  which is set as the apparatus with which the apparatus in question is to communicate) or not. The comparison unit  46  notifies the determination result (notification signal including information indicating agreement or disagreement) to the client module  42 . 
         [0128]    The storage unit  47  stores, as the comparison information, the identifier of the transponder  41  with which the apparatus in question is to communicate. In the sixth exemplary embodiment of the present invention, a set of transponders  41  communicating with each other is set in advance, and the transponders  41  communicate with each other by using a predetermined wavelength.  FIG. 17  is a table illustrating a connection relationship of transponders  41  of each base station  10  in the communication system as shown in  FIG. 14  and the used wavelength. Likewise,  FIG. 18  is a table illustrating transponders  41  provided in each of the base stations  10  in the communication system as shown in  FIG. 14 , and the identifier of the transponder  41 , the identifier of a transponder  41  with which the transponder  41  in question communicates. 
         [0129]    The client module  42  converts the electric signal received from the Framer LSI  43  into an optical signal, and transmits the optical signal, as a client signal, to the client apparatus  50 . The client module  42  determines whether to transmit the client signal to the client apparatus  50  or not in accordance with a determination result received from the comparison unit  46 . More specifically, if the client module  42  receives a determination result indicating agreement from the comparison unit  46  (notification signal including information indicating agreement), the client module  42  transmits the client signal to the client apparatus  50 . In contrast, if the client module  42  receives a determination result indicating disagreement from the comparison unit  46  (notification signal including information indicating disagreement), the client module  42  discards the client signal. 
         [0130]      FIGS. 19 and 20  are sequence diagrams illustrating an example of operation of the transponder  41  according to the sixth exemplary embodiment of the present invention.  FIG. 19  is a sequence diagram in the case where the transponder  41  receives the optical signal. 
         [0131]    The line module  45  receives an input of an optical signal (line reception signal) from the wavelength separation multiplex unit  51  (S 701 ). The line module  45  converts the received optical signal (line reception signal) into an electric signal (line signal frame), and outputs the electric signal (line signal frame) to the Framer LSI  43  (S 702 ). 
         [0132]    The Framer LSI  43  extracts a client signal from the electric signal (line signal frame) received from the line module  45 , and outputs the client signal, as a client signal (electric signal), to the client module  42  (S 703 ). Further, the Framer LSI  43  extracts the identifier stored in the header of the received electric signal (line signal frame), and notifies the identifier to the comparison unit  46  (S 704 ). 
         [0133]    The comparison unit  46  compares the identifier that has been notified from the Framer LSI  43  and the stored identifier (comparison information) of the transponder  41  with which communication is to be performed, and determines whether the identifiers of them both match each other or not (S 705 ). The comparison unit  46  notifies the determination result to the client module  42  (S 706 ). 
         [0134]    In accordance with a determination result that has been notified from the comparison unit  46  (notification signal including information indicating agreement or disagreement), the client module  42  converts the electric signal (client signal) received from the Framer LSI  43  into an optical signal and outputs the optical signal, or discards the electric signal (client signal) (S 707 ). More specifically, in the case of a determination result indicating agreement (notification signal including information indicating agreement), the client module  42  converts the received electric signal into an optical signal, and transmits the optical signal to the client apparatus  50 . In contrast, in the case of a determination result indicating disagreement (notification signal including information indicating disagreement), the client module  42  discards the electric signal (client signal). 
         [0135]    Besides,  FIG. 20  is a sequence diagram in the case where the transponder  41  transmits an optical signal. 
         [0136]    The client module  42  receives an optical signal from the client apparatus  50  (S 801 ). The client module  42  converts the optical signal received from the client apparatus  50  into an electric signal, and outputs the electric signal, as a client reception signal, to the Framer LSI  43  (S 802 ). 
         [0137]    The insertion unit  44  notifies the identifier of the transponder  41  to the Framer LSI  43  (S 803 ). 
         [0138]    The Framer LSI  43  stores the identifier of the transponder  41  that has been notified from the insertion unit  44  into the line signal frame accommodating the client reception signal (S 804 ). 
         [0139]    The Framer LSI  43  outputs the line signal frame (electric signal) to the line module  45  (S 805 ). 
         [0140]    The line module  45  converts the electric signal which is output by the Framer LSI  43  (i.e., the line signal frame) into an optical signal of a predetermined wavelength, and outputs the optical signal to the wavelength separation multiplex unit  51  (S 806 ). 
         [0141]    It should be noted that in the sixth exemplary embodiment of the present invention, the transponder  41  may be a configuration as shown in  FIG. 21 . 
         [0142]    The Framer LSI  43  of the transponder  41  shown in  FIG. 21  extracts the client signal from the line signal frame received from the line module  45 , and outputs the client signal, as an electric signal, to the comparison unit  46 . 
         [0143]    The comparison unit  46  of the transponder  41  compares the identifier stored in the storage unit  47  in advance (comparison information) and the identifier included in the electric signal received from the Framer LSI  43 , and outputs the electric signal to the client module  42  in accordance with matching of the identifiers. In contrast, the comparison unit  46  discards the electric signal in accordance with disagreement of the identifiers. 
         [0144]    The client module  42  converts the electric signal received from the comparison unit  46  into an optical signal, and transmits the optical signal, as a client signal, to the client apparatus  50 . 
         [0145]    As described above, in the sixth exemplary embodiment of the present invention, the transponder  41  determines whether the received signal is transmitted from the apparatus with which communication is to be performed, and determines whether to transmit the signal to the client apparatus  50  on the basis of the result of the determination. As a result of the determination, the signal determined not to be transmitted from the apparatus with which communication is to be performed is discarded and is not transmitted to the client apparatus  50 . 
         [0146]    Therefore, in the sixth exemplary embodiment of the present invention, the transponder  41  can transmit only the signal received from the appropriate apparatus with which communication is to be performed (configured in advance) to the client apparatus  50 . More specifically, the transponder  41  according to the sixth exemplary embodiment of the present invention discards the optical signal received from an apparatus that is not the apparatus with which the apparatus in question is to communicate and does not transfer the optical signal to the client apparatus  50 . Therefore, the optical signal is prevented from being transferred to the client apparatus  50  that is not the intended transmission destination apparatus, and the client apparatus  50  does not receive the optical signal. As a result, the confidentiality of the information included in the optical signal can be ensured. 
       Seventh Exemplary Embodiment 
       [0147]    The seventh exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0148]      FIG. 22  is a figure illustrating an example of a configuration of the transponder  41  according to the seventh exemplary embodiment of the present invention. As shown in  FIG. 22 , the transponder  41  has a pattern generation unit  48 . 
         [0149]    First, a case where the transponder  41  receives an optical signal will be explained. 
         [0150]    The comparison unit  46  refers to the storage unit  47  to determine whether the identifier that has been notified from the Framer LSI  43  matches the stored identifier (comparison information) or not. The comparison unit  46  notifies the determination result (a notification signal including information indicating agreement or disagreement) to the pattern generation unit  48 . 
         [0151]    In a case where the pattern generation unit  48  receives the notification signal indicating agreement from the comparison unit  46 , the pattern generation unit  48  outputs the electric signal received from the Framer LSI  43  to the client module  42  as it is. In contrast, in a case where the pattern generation unit  48  receives the notification signal indicating disagreement from the comparison unit  46 , the pattern generation unit  48  outputs, instead of the electric signal, an electric signal including a dummy pattern in which 0 and 1 are randomly arranged or a fixed pattern in which 0 and 1 are arranged in a particular pattern or an electric signal in which a bit string is randomly interchanged to the client module  42 . 
         [0152]    The client module  42  converts the electric signal received from the Framer LSI  43  into an optical signal, and transmits the optical signal to the client apparatus  50  as a client signal. 
         [0153]    Subsequently, the case where the transponder  41  transmits an optical signal will be explained. 
         [0154]    The Framer LSI  43  extracts a client signal from the line signal frame received from the line module  45 , and outputs the client signal to the client module  42  as an electric signal. At this occasion, the Framer LSI  43  extracts the identifier stored in a predetermined area of the header of the line signal frame, and notifies the extracted identifier to the comparison unit  46 . 
         [0155]    Further, the Framer LSI  43  also extracts information about a processing result of the optical signal of the opposed apparatus (i.e., whether the optical signal is transferred to the apparatus in a subsequent stage or discarded) stored in the predetermined area of the header of the line signal frame. 
         [0156]    The Framer LSI  43  notifies the processing result of the optical signal extracted (the determination result of the comparison unit  46  of the opposed apparatus) to the pattern generation unit  48 . 
         [0157]    The pattern generation unit  48  receives an input of the client reception signal (electric signal) from the client module  42 . In accordance with the processing result that has been notified from the Framer LSI  43 , the pattern generation unit  48  determines whether to perform code conversion on the received client reception signal in accordance with a predetermined method. Further, the pattern generation unit  48  determines whether the output signal is replaced with a dummy signal not including any information. 
         [0158]    In accordance with the determination of performing the processing, the pattern generation unit  48  performs the processing on the client reception signal, and thereafter, outputs the processed client reception signal to the Framer LSI  43 . In contrast, in accordance with the determination of not performing the processing, the pattern generation unit  48  outputs the client reception signal to the Framer LSI  43  as it is. 
         [0159]    The pattern generation unit  48  receives a notification of the determination result of the comparison unit  46  of the opposed apparatus (a notification signal including information indicating agreement or disagreement) from, for example, the Framer LSI  43 . 
         [0160]    In a case where the determination result is “disagreement of the identifiers”, the pattern generation unit  48  performs predetermined processing on the signal which is to be transmitted. For example, the pattern generation unit  48  serves as a scrambler to perform code conversion on the client reception signal in accordance with a predetermined method so that it cannot be decoded by the apparatus with which communication is to be performed, and the pattern generation unit  48  outputs the client reception signal to the Framer LSI  43 . While, for example, the pattern generation unit  48  replaces the output signal with, for example, a dummy signal not including information, and outputs the client reception signal to the Framer LSI  43 . In contrast, in a case where the determination result is “agreement of the identifiers”, the pattern generation unit  48  outputs the client reception signal to the Framer LSI  43  as it is. 
         [0161]    Further, processing in which the transponder  41  notifies the processing result of the optical signal (i.e., whether the identifiers agree or not) to the opposed apparatus will be explained. 
         [0162]    In the seventh exemplary embodiment of the present invention, the comparison unit  46  compares the identifier notified from the Framer LSI  43  and the stored identifier of the transponder  41  with which communication is to be performed, and determines whether both of them match or not. The comparison unit  46  notifies the determination result (a notification signal including information indicating agreement or disagreement) to the client module  42  and the Framer LSI  43 . 
         [0163]    The determination result that has been notified from the comparison unit  46  to the Framer LSI  43  (a notification signal including information indicating agreement or disagreement) is notified to the apparatus which transmitted the optical signal (i.e., opposed apparatus). The Framer LSI  43  stores the determination result into the predetermined area of the header of the line signal frame which is to be output to the line module (a frame transmitted to the opposed apparatus) in order to notify the determination result to the opposed apparatus. Further, the Framer LSI  43  may notify it to the opposed apparatus (the transponder  41  with which communication is to be performed) via a communication path (not shown) other than the transmission path  20 . 
         [0164]      FIG. 23  is a sequence diagram illustrating an example of operation of the transponder  41  according to the seventh exemplary embodiment of the present invention. 
         [0165]    The line module  45  receives an input of the optical signal (line reception signal) from the wavelength separation multiplex unit  51  (S 1001 ). The line module  45  converts the received optical signal (line reception signal) into an electric signal (line signal frame), and outputs the electric signal (line signal frame) to the Framer LSI  43  (S 1002 ). 
         [0166]    The Framer LSI  43  extracts the client signal from the electric signal (line signal frame) received from the line module  45 , and outputs the electric signal to the client module  42  as a client signal (electric signal) (S 1003 ). Further, the Framer LSI  43  also extracts the identifier stored in the header of the received electric signal (line signal frame), and notifies the identifier to the comparison unit  46  (S 1004 ). Furthermore, the Framer LSI  43  extracts information about the processing result of the optical signal in the opposed apparatus (whether the identifiers match or not) stored in a predetermined area of the header of the line signal frame, and notifies the information to the pattern generation unit  48  (S 1005 ). It should be noted that  FIG. 23  shows an example where the information about the processing result is a determination result of the comparison unit  46  in the opposed apparatus (the transponder  41  of the communication apparatus). 
         [0167]    The comparison unit  46  compares the identifier notified from the Framer LSI  43  and the stored identifier, and determines whether both of them match each other or not (S 1006 ). The comparison unit  46  notifies the determination result (a notification signal including information indicating agreement or disagreement) to the pattern generation unit  48  (S 1007 ). Further, the comparison unit  46  also notifies the determination result (a notification signal including information indicating agreement or disagreement) to the Framer LSI  43  (S 1008 ). 
         [0168]    In accordance with the determination result that has been notified from the comparison unit  46  (a notification signal including information indicating agreement or disagreement), the pattern generation unit  48  outputs the electric signal (client signal) received from the Framer LSI  43  to the client module  42  as it is, or outputs the electric signal (client signal) to the client module  42  upon performing the predetermined processing (S 1009 ). 
         [0169]    The client module  42  converts the electric signal (client signal) received from the pattern generation unit  48  into an optical signal, and transmits the optical signal to the client apparatus  50  (S 1010 ). 
         [0170]    The client module  42  receives the optical signal from the client apparatus  50  (S 1011 ). The client module  42  converts the optical signal received from the client apparatus  50  into an electric signal, and outputs the electric signal to the pattern generation unit  48  as a client reception signal (S 1012 ). 
         [0171]    In the determination result notified in step  1005  (S 1005 ) (a notification signal including information indicating agreement or disagreement), the pattern generation unit  48  outputs the received client reception signal to the Framer LSI  43  as it is, or outputs the received client reception signal to the Framer LSI  43  (S 1014 ) upon predetermined processing of the received client reception signal (S 1013 ). 
         [0172]    The insertion unit  44  notifies the identifier of the transponder  41  to the Framer LSI  43  (S 1015 ). 
         [0173]    The Framer LSI  43  stores the identifier of the transponder  41  that has been notified from the insertion unit  44  and information about the determination result notified in step  1008  (S 1008 ) into the line signal frame accommodating the client reception signal (S 1016 ). 
         [0174]    The Framer LSI  43  outputs the line signal frame (electric signal) to the line module  45  (S 1017 ). 
         [0175]    The line module  45  converts the electric signal (i.e., line signal frame) that is output by the Framer LSI  43  into an optical signal of a predetermined wavelength, and outputs the optical signal to the wavelength separation multiplex unit  51  (S 1018 ). 
         [0176]    It should be noted that, in the seventh exemplary embodiment of the present invention, the transponder  41  may have a configuration as shown in  FIG. 24 . 
         [0177]    The Framer LSI  43  of the transponder  41  as shown in  FIG. 24  extracts the client signal from the line signal frame received from the line module  45 , and outputs the client signal to the comparison unit  46  as an electric signal. 
         [0178]    The comparison unit  46  compares the identifier (comparison information) stored in the storage unit  47  in advance and the identifier included in the electric signal received from the Framer LSI  43 , and outputs the electric signal to the client module  42  in accordance with agreement between the identifiers from each other. 
         [0179]    In contrast, in a case where the identifiers do not match each other, the comparison unit  46  outputs a notification signal including information indicating disagreement to the pattern generation unit  48 . 
         [0180]    In a case where the pattern generation unit  48  receives a notification signal from the comparison unit  46 , the pattern generation unit  48  generates an electric signal including a dummy pattern or a fixed pattern, and outputs the electric signal to the client module  42 . 
         [0181]    Here, in this case, instead of the generation of the dummy pattern and the fixed pattern, the pattern generation unit  48  may serve as a scrambler to randomly interchange the bit string of the electric signal that is input from the comparison unit  46  to the client module  42 . 
         [0182]    In a case where the client module  42  receives the electric signal from the comparison unit  46 , the client module  42  converts the electric signal received from the comparison unit  46  into the optical signal, and outputs the optical signal to the client apparatus  50  as a client signal. In contrast, in a case where the transmission unit  12  receives the electric signal including the dummy pattern or the fixed pattern from the pattern generation unit  48 , the transmission unit  12  converts the electric signal including the dummy pattern or the fixed pattern received from the pattern generation unit  48  into an optical signal, and outputs the optical signal to the client apparatus  50 . 
         [0183]    As described above, in the seventh exemplary embodiment of the present invention, the pattern generation unit  48  performs predetermined processing on the output signal in accordance with the predetermined condition. The optical reception apparatus  1 - 1  discards the optical signal transmitted from the apparatus with which communication is to be performed, and in addition, the predetermined processing is performed on the optical signal transmitted by the optical transmission apparatus  1 - 2 , and therefore, the confidentiality of the optical signal can be duplexed, and the confidentiality of the information included in the optical signal can be enhanced. 
       Eighth Exemplary Embodiment 
       [0184]    The eighth exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0185]    In the eighth exemplary embodiment of the present invention, the transponder  41  includes encryption means (an encoding unit  61  and a decoding unit  62 ), and performs the encryption processing on the optical signal which is to be transmitted. Then, only the apparatus with which the apparatus in question is to communicate (the transponder  41  which is set as the apparatus with which the apparatus in question is to communicate) is configured to be able to decode the encrypted optical signal, so that the confidentiality of the information included in the optical signal is ensured. 
         [0186]      FIG. 25  is a figure illustrating an example of a configuration of the transponder  41  according to the eighth exemplary embodiment of the present invention. As shown in  FIG. 25 , the transponder  41  includes an encoding unit  61  and a decoding unit  62 . 
         [0187]    First, processing in which the transponder  41  encrypts and transmits an optical signal will be explained. 
         [0188]    In the eighth exemplary embodiment of the present invention, the encoding unit  61  encrypts the client signal (electric signal) received from the client module  42 . 
         [0189]    The encryption method executed by the encoding unit  61  is the symmetric key encoding method. The symmetric key encoding method is a method using a key which is common to the encryption and the decoding. In a case where the encoding unit  61  encrypts the client signal in accordance with the symmetric key encoding method, both of the transponder  41  of the apparatus in question and the transponder  41  of the apparatus with which communication is to be performed hold the common key (hereinafter referred to as the “symmetric key”). The signal which is encrypted with the symmetric key can be decoded by only the apparatus having the symmetric key with which communication is to be performed, and therefore, even if the signal encrypted by the apparatus that is not the apparatus with which communication is to be performed is received, the information included in the signal cannot be extracted, and the confidentiality of the information included in the signal can be ensured. 
         [0190]    Instead of the symmetric key encoding method, a public key encoding method may be used as the encryption method executed by the encoding unit  61 . The public key encoding method is a method in which different keys are used for the encryption and the decoding. The key used for encryption (public key) is published, but the key used for decoding (secret key) is held by only the decoding apparatus. The signal which is encrypted with the public key can be decoded with only the secret key, and therefore, the apparatus that does not hold the secret key cannot decode the encrypted information, and the confidentiality of the signal can be ensured. 
         [0191]    In a case where the encoding unit  61  encrypts the client signal in accordance with the public key encoding method, the transponder  41  of the apparatus in question obtains, in advance, the public key from the transponder  41  of the apparatus with which communication is to be performed. The signal encrypted with the public key can be decoded by only the apparatus holding the secret key with which communication is to be performed, and therefore, even when an apparatus that is not the intended apparatus with which communication is to be performed receives the encrypted signal, the confidentiality of the information included in the signal can be ensured. 
         [0192]    First, processing in a case where the transponder  41  receives an encrypted optical signal will be explained. 
         [0193]    The decoding unit  62  executes decoding of the electric signal (client signal) received from the Framer LSI  43 . In a case of the symmetric key encoding method, the decoding unit  62  uses the symmetric key to execute the decoding of the client signal. In a case of the public key encoding method, the decoding unit  62  uses the secret key to execute the decoding of the client signal. 
         [0194]    The decoding unit  62  notifies the identifier included in the decoded signal to the comparison unit  46 . Further, the decoding unit  62  outputs the client signal to the client module  42  or the comparison unit  46 . 
         [0195]    The comparison unit  46  compares the identifier that has been notified from the decoding unit  62  and the stored identifier of the transponder  41  with which communication is to be performed, and determines whether both of them match each other or not. In a case where the decoding unit  62  was able to decode the client signal, and the identifier is the identifier of the transponder  41  of the apparatus with which communication is to be performed, the comparison unit  46  determines that the identifiers of both of them match each other. In cases other than the above, the comparison unit  46  determines disagreement therebetween. The comparison unit  46  notifies a determination result (a notification signal including information indicating agreement or disagreement) to the client module  42  and the Framer LSI  43 . 
         [0196]    The client module  42  transmits the client signal which is output from the decoding unit  62  or the comparison unit  46  to the client apparatus  50 . 
         [0197]    Subsequently, the case where the transponder  41  transmits an optical signal will be explained. 
         [0198]    In the eighth exemplary embodiment of the present invention, the encoding unit  61  encrypts the client reception signal (electric signal) received from the client module  42 . In the case of the symmetric key encoding method, the encoding unit  61  uses the symmetric key to encrypt the client reception signal. In the case of the public key encoding method, the encoding unit  61  encrypts the client reception signal by using the public key obtained in advance from the apparatus with which communication is to be performed. 
         [0199]    The encoding unit  61  outputs the encrypted client reception signal to the Framer LSI  43 . 
         [0200]      FIG. 26  is a sequence diagram illustrating an example of operation of the transponder  41  according to the eighth exemplary embodiment of the present invention. 
         [0201]    The line module  45  receives an input of the optical signal (line reception signal) from the wavelength separation multiplex unit  51  (S 1101 ). The line module  45  converts the received optical signal (line reception signal) into an electric signal (line signal frame), and outputs the electric signal (line signal frame) to the Framer LSI  43  (S 1102 ). 
         [0202]    The Framer LSI  43  extracts the client signal from the electric signal (line signal frame) received from the line module  45 , and outputs the client signal from the electric signal to the decoding unit  62  as a client signal (electric signal) (S 1103 ). 
         [0203]    The decoding unit  62  executes the decoding of the client signal received from the Framer LSI  43  (S 1104 ). The decoding unit  62  notifies the decoded electric signal to the client module  42  (S 1105 ), and notifies the identifier included in the decoded signal to the client module  42  (S 1106 ). 
         [0204]    The comparison unit  46  compares the identifier that has been notified from the decoding unit  62  and the stored identifier (comparison information), and determines whether both of them match each other or not (S 1107 ). The comparison unit  46  notifies the determination result (a notification signal including information indicating agreement or disagreement) to the client module  42  (S 1108 ), and also notifies the determination result (a notification signal including information indicating agreement or disagreement) to the encoding unit  61  (S 1109 ). 
         [0205]    In accordance with the determination result that has been notified from the comparison unit  46  (a notification signal including information indicating agreement or disagreement), the client module  42  transmits the electric signal (client signal) received from the decoding unit  62  upon converting the electric signal (client signal) into an optical signal, or discards the electric signal (client signal) (S 1110 ). 
         [0206]    The client module  42  receives the optical signal from the client apparatus  50  (S 1111 ). The client module  42  converts the optical signal received from the client apparatus  50  into an electric signal, and outputs the electric signal to the encoding unit  61  as a client reception signal (S 1112 ). 
         [0207]    The encoding unit  62  encrypts the client reception signal (electric signal) received from the client module  42  (S 1113 ), and outputs the client reception signal (electric signal) to the Framer LSI  43  (S 1114 ). 
         [0208]    The insertion unit  44  notifies the identifier of the transponder  41  to the Framer LSI  43  (S 1115 ). 
         [0209]    The Framer LSI  43  stores the identifier of the transponder  41  notified from the insertion unit  44  into the line signal frame accommodating the client reception signal (S 1116 ). 
         [0210]    The Framer LSI  43  outputs the line signal frame (electric signal) to the line module  45  (S 1117 ). 
         [0211]    The line module  45  converts the electric signal (i.e., line signal frame) which is output from the Framer LSI  43  into an optical signal of a predetermined wavelength, and outputs the optical signal to the wavelength separation multiplex unit  51  (S 1118 ). 
         [0212]    As described above, in the eighth exemplary embodiment of the present invention, the transponder  41  has encryption means (the encoding unit  61  and the decoding unit  62 ), and performs encryption processing on the optical signal which is to be transmitted. Then, only the apparatus with which the apparatus in question is to communicate (the transponder  41  which is set as the apparatus with which the apparatus in question is to communicate) is configured to be able to decode the encrypted optical signal, so that the confidentiality of the information included in the optical signal is ensured. 
       Ninth Exemplary Embodiment 
       [0213]    The ninth exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0214]    In the ninth exemplary embodiment of the present invention, in a case where a fault occurs in a part of the transmission path  20 , and an optical signal from some of the base stations is lost, a BU (optical branch apparatus)  30  switches the route, so that the lost optical signal is compensated by an optical signal from another base station. 
         [0215]    The total power of the optical signal transmitted through the transmission path  20  is configured to be set at a constant level, and in a case where some wavelength component of the optical signal is lost due to disconnection of the transmission path  20  and the like, the other wavelength components of the optical signal is amplified, so that the total power of the optical signal is maintained at a constant level. 
         [0216]    However, when only the power of a particular wavelength component of the optical signal is increased and the power becomes equal to or more than a predetermined value, the optical spectrum is changed due to, e.g., degradation of the waveform of the optical signal by the nonlinear effect of the optical fiber, and the transmission quality of the optical signal is degraded. 
         [0217]    Therefore, in the ninth exemplary embodiment of the present invention, in a case where the optical signal from some of the base stations is cut off, and some wavelength component of the optical signal transmitted in the transmission path  20  is lost, the lost wavelength component is compensated by the optical signal from another base station. Hence, the increase of only the power of a particular wavelength component of the optical signal is prevented, and the degradation of the transmission quality of the optical signal is suppressed. 
         [0218]    However, in the ninth exemplary embodiment of the present invention, the transponder  41  at the reception side discards the optical signal from an apparatus that is not the intended apparatus with which communication is to be performed, and therefore, the optical signal used for the compensation is discarded by the transponder  41 . Therefore, the client apparatus  50  that is not the intended apparatus to which the optical signal used for the compensation is transmitted would not receive the optical signal. Therefore, in the ninth exemplary embodiment of the present invention, some wavelength component that is lost can be compensated with regard to the optical signal transmitted in the transmission path  20 , and the optical signal used for the compensation is prevented from being received by the client apparatus  50 . 
         [0219]      FIG. 27  is a figure illustrating an example of a configuration of a communication system before a fault occurs in the transmission path  20  in the ninth exemplary embodiment of the present invention. As shown in  FIG. 27 , each base station  10  is mutually connected with the opposed base station  10  via the BU  30 . 
         [0220]      FIG. 28  is a table illustrating the optical signal transmitted in sections between the A base station  10 - 1  and the BU  30  and between the BU  30  and the B base station  10 - 2  of the communication system as shown in  FIG. 27 . No fault occurs in the transmission path  20 , and therefore, five sets of transponders  41  of each base station are communicating with each other in each of the sections between the A base station  10 - 1  and the BU  30  and between the BU  30  and the B base station  10 - 2 . 
         [0221]      FIG. 29  is an example of a configuration of a communication system in a case where a fault occurs in a part of the transmission path  20 , and the optical signal from some of the base stations  10  is lost, in the ninth exemplary embodiment of the present invention. 
         [0222]      FIG. 29  illustrates, for example, an example in a communication system in a case where a fault occurs in the transmission paths  20 - 2  and  20 - 3  between the C base station and the D base station and the BU, and the optical signal from the C base station and D base station to the BU is lost. More specifically, in the optical signal transmitted in a section between the A base station  10 - 1  and the BU  30  and a section between the BU  30  and the B base station  10 - 2 , the wavelength components of the optical signal transmitted and received between the A base station  10 - 1  and the C base station  10 - 3  and between the B base station  10 - 2  and the D base station  10 - 4  are lost. 
         [0223]      FIG. 30  is a table illustrating a connection relationship of the transponder  41  transmitting and receiving the optical signal in a section between the A base station  10 - 1  and the BU  30  and a section between the BU  30  and the B base station  10 - 2  in the communication system as shown in  FIG. 29 . As described above, since a fault occurs in the transmission path  20  between the C base station and the D base station and the BU, the connection between the A base station  10 - 1  and the C base station  10 - 2  and the connection between the B base station  10 - 2  and the D base station  10 - 4  are disconnected. Therefore, as shown in  FIG. 30 , in the section between the A base station  10 - 1  and the BU  30  and the section between the BU  30  and the B base station  10 - 2 , the connection remains only between the A base station  10 - 1  and the B base station  10 - 2 . 
         [0224]    However, the transmission quality of the optical signal continued to be transmitted in the state of  FIG. 29  and  FIG. 30  (in a state where some of the wavelength components are lost in the optical signal multiplexed by wavelength multiplex) is degraded as described above. Therefore, in the ninth exemplary embodiment of the present invention, the BU  30  switches the route, so that the lost optical signal is compensated by the optical signal from another base station. 
         [0225]    In the ninth exemplary embodiment of the present invention, the BU  30  switches the route so that the optical signals of the transponders  41 - 3 -A,  41 - 4 -A, and  41 - 5 -A of the A base station  10 - 1  are received by the transponders  41 - 3 -B,  41 - 4 -B, and  41 - 5 -B of the B base station  10 - 2 . 
         [0226]      FIG. 31  is a table illustrating a connection relationship of the transponders  41  transmitting and receiving optical signals in a section between the A base station  10 - 1  and the BU  30  and a section between the BU  30  and the B base station  10 - 2  after the BU  30  switches the route. The BU  30  switches the route, and accordingly, in the transponders  41  of the A base station  10 - 1 , the optical signals transmitted to and received from the transponders  41  of the C base station  10 - 3  are transferred to the transponders  41  of the B base station  10 - 2 , so that the lost optical signal is compensated. Further, in the transponders  41  of the B base station  10 - 1 , the optical signals transmitted to and received from the transponders  41  of the D base station  10 - 3  are transferred to the transponders  41  of the A base station  10 - 2 , so that the lost optical signal is compensated. 
         [0227]    The transponder  41  at the reception side discards the optical signal from an apparatus that is not the intended apparatus with which communication is to be performed. Therefore, the optical signal used for the compensation is discarded by the transponder  41  at the reception side. Hence, the client apparatus  50  would not receive the optical signal used for the compensation. 
         [0228]    For example, the optical signal transmitted from the transponder  41 - 3 -A of the A base station  10 - 1  is used for the compensation, and received by the transponder  41 - 3 -B of the B base station  10 - 2 . The apparatus of the intended recipient by which transmissions from the transponder  41 - 3 -B of the B base station  10 - 2  are to be received is the transponder  41 - 1 -D of the D base station  10 - 4 . Therefore, the transponder  41 - 3 -B of the B base station  10 - 2  discards the received optical signal on the basis of the fact that the identifier stored in the received optical signal is not the identifier of the transponder  41 - 1 -D. As described above, the transponder  41 - 3 -B of the B base station  10 - 2  would not transmit the optical signal used for the compensation (the optical signal transmitted from the transponder  41 - 3 -A of the A base station  10 - 1 ) to the client apparatus  50 . 
         [0229]    In the ninth exemplary embodiment of the present invention, as described above, in a case where a fault occurs in the transmission path  20 , and the optical signal from some of the base stations is lost, the BU  30  switches the route, and compensates the lost optical signal with an optical signal from another base station. Accordingly, the increase of only the power of a particular wavelength component of the optical signal is prevented, and the degradation of the transmission quality of the optical signal is suppressed. In addition, in the ninth exemplary embodiment of the present invention, the transponder  41  at the reception side discards the optical signal used for the compensation, and the client apparatus  50  is prevented from receiving the optical signal used for the compensation. Therefore, in the ninth exemplary embodiment of the invention of the present application, some of the lost wavelength components can be compensated with regard to the optical signal transmitted in the transmission path  20 , and the optical signal used for the compensation is prevented from being received by the client apparatus  50 . 
       Tenth Exemplary Embodiment 
       [0230]    The tenth exemplary embodiment of the present invention will be explained with reference to drawings. 
         [0231]      FIG. 32  is an example of a configuration of an optical communication system according to the tenth exemplary embodiment of the present invention. As shown in  FIG. 32 , the optical communication system includes an optical reception apparatus  1 - 1 , an optical transmission apparatus  1 - 2 , an optical transmission and reception apparatus  1 - 3 , a transmission path  20 , a BU  30 , and an EMS (Element Management System)  70 . 
         [0232]    The EMS  70  is an apparatus for performing network management of the optical communication system, and collects information about the communication route of the optical signal from an apparatus included in the optical communication system. The EMS  70  detects a fault that has occurred in the transmission path  20  on the basis of the information about the communication route thus collected, and requests the BU  30  to switch the route. As shown in  FIG. 29 , in a case where a fault occurs in the transmission path  20  between the C base station and the D base station and the BU, the EMS  70  requests the BU  30  to switch the route so that the optical signals transmitted from the transponders  41 - 3 -A,  41 - 4 -A, and  41 - 5 -A of the A base station  10 - 1  are received by the transponders  41 - 3 -B,  41 - 4 -B, and  41 - 5 -B of the B base station  10 - 2 . 
         [0233]    Further, in response to detection of a fault that has occurred in the transmission path  20 , the EMS  70  requests the pattern generation unit  48  of the transponder  41  that is included in the optical transmission apparatus  1 - 2  to perform predetermined processing on the optical signal. As shown in  FIG. 29 , in a case where a fault occurs in the transmission path  20  between the C base station and D base station and the BU, the EMS  70  requests the pattern generation unit  48  of the transponders  41 - 3 -A,  41 - 4 -A, and  41 - 5 -A of the A base station  10 - 1  to perform the predetermined processing on the optical signal. 
         [0234]    In response to a request from the EMS  70 , the pattern generation unit  48  having received a request from the EMS  70  outputs, instead of the received electric signal, an electric signal including a dummy pattern in which 0 and 1 are randomly arranged or a fixed pattern in which 0 and 1 are arranged in a particular pattern, or an electric signal obtained by randomly interchanging a bit string to the line module  42 . 
         [0235]    Further, in a case where the BU  30  switches the route (in a case where a fault that has occurred in the transmission path  20  is detected), the EMS  70  requests the pattern generation unit  48  of the transponder  41  included in the optical reception apparatus  1 - 1  to output an electric signal, including a dummy pattern in which 0 and 1 are randomly arranged or a fixed pattern in which 0 and 1 are arranged in a particular pattern or an electric signal obtained by randomly interchanging a bit string to the client module  42 . 
         [0236]    It should be noted that in a case where the BU  30  switches the route (in a case where a fault that has occurred in the transmission path  20  is detected), the EMS  70  may request the transponder  41  included in the optical reception apparatus  1 - 1  to discard the optical signal (or the electric signal) (i.e. not to transmit the optical signal). 
         [0237]    As described above, in the tenth exemplary embodiment of the present invention, the EMS  70  performs the network management, and requests the BU  30  to switch the route and requests the optical transmission apparatus  1 - 2  to transmit the optical signal upon performing the predetermined processing on the optical signal. Therefore, even in a case where the BU  30 , the optical reception apparatus  1 - 1 , and the optical transmission apparatus  1 - 2  cannot detect a fault of the transmission path  20 , some of the lost wavelength components can be compensated with regard to the optical signal transmitted in the transmission path  20 , and in addition, the optical signal used for the compensation can be prevented from being received by the client apparatus  50 . 
       Eleventh Exemplary Embodiment 
       [0238]    The eleventh exemplary embodiment of the present invention will be explained. In the eleventh exemplary embodiment, a computer, a CPU (Central Processing Unit), an MPU (Micro-Processing Unit) or the like of an optical transmission apparatus  1 , a terminal apparatus  40 , or a transponder  41  executes software (program) for realizing the functions of each exemplary embodiment explained above. It should be noted that in the eleventh exemplary embodiment of the present invention, the apparatus executing the software (program) is not limited to the optical transmission apparatus  1 , the terminal apparatus  40 , or the transponder  41 , and may be any other apparatus. 
         [0239]    In the eleventh exemplary embodiment of the present invention, the optical transmission apparatus  1 , the terminal apparatus  40 , or the transponder  41  obtains software (program) for realizing the functions of each exemplary embodiment explained above via various kinds of storage media or networks such as, e.g., a CD-R (Compact Disc Recordable). The programs obtained by the optical transmission apparatus  1 , the terminal apparatus  40 , or the transponder  41  or a storage medium storing the program constitute the present invention. It should be noted that the software (program) may be stored in advance to, for example, a predetermined storage unit included in the optical transmission apparatus  1 , the terminal apparatus  40 , or the transponder  41 . 
         [0240]    The computer, the CPU, the MPU, or the like of the optical transmission apparatus  1 , the terminal apparatus  40 , or the transponder  41  read and execute the program code of the software (program) thus obtained. Therefore, the same processing as the processing of the node  1  (open flow switch) or the control apparatus  3  (open flow controller) in each of the exemplary embodiments explained above is executed. 
         [0241]    According to the eleventh exemplary embodiment of the present invention can be applied for the purpose of, e.g., a program for realizing the computer, the CPU, the MPU, or the like of the optical transmission apparatus  1 , the terminal apparatus  40 , or the transponder  41 . 
         [0242]    As described above, the exemplary embodiment of the present invention has been explained, but the present invention is not limited to each of the exemplary embodiments explained above. The present invention can be carried out on the basis of a modification, a replacement, or an adjustment of each exemplary embodiment. 
         [0243]    It should be noted that the present invention can also be carried out by combining the exemplary embodiments in any manner. More specifically, the present invention includes various kinds of modifications and corrections that can be achieved in accordance with all the disclosed contents and the technical spirit in this description. 
         [0244]    The whole or part of the exemplary embodiments disclosed above can be described as, but not limited to, the following supplementary notes. 
       [Supplementary Note 1] 
       [0245]    An optical reception apparatus comprising: 
         [0246]    a reception unit for receiving wavelength multiplexed signal light; and 
         [0247]    a transmission unit for transferring an optical signal of a predetermined wavelength in accordance with an identifier included in the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light. 
       [Supplementary Note 2] 
       [0248]    The optical reception apparatus according to supplementary note 1, further comprising: 
         [0249]    a storage unit for storing comparison information in advance; and 
         [0250]    a comparison unit for determining whether the identifier and the comparison information match each other or not, 
         [0251]    wherein in a case where the comparison unit determines that the identifier and the comparison information match each other, the transmission unit transfers the optical signal of the predetermined wavelength. 
       [Supplementary Note 3] 
       [0252]    The optical reception apparatus according to supplementary note 1 or 2, wherein in a case where the comparison unit determines that the identifier and the comparison information do not match each other, the transmission unit discards the optical signal of the predetermined wavelength. 
       [Supplementary Note 4] 
       [0253]    The optical reception apparatus according to any one of supplementary notes 1 to 3, further comprising: 
         [0254]    a pattern generation unit for generating a predetermined pattern, 
         [0255]    wherein in a case where the comparison unit determines that the identifier and the comparison information do not match each other, the transmission unit outputs the optical signal of the predetermined wavelength including the predetermined pattern generated by the pattern generation unit. 
       [Supplementary Note 5] 
       [0256]    The optical reception apparatus according to any one of supplementary notes 1 to 4, wherein the reception unit includes: 
         [0257]    a demultiplexing unit for demultiplexing the received wavelength multiplexed signal light into the optical signal of the predetermined wavelength; and 
         [0258]    an input unit for receiving the optical signal of the predetermined wavelength demultiplexing by the demultiplexing unit, 
         [0259]    wherein the input unit outputs the optical signal of the predetermined wavelength to the comparison unit. 
       [Supplementary Note 6] 
       [0260]    The optical reception apparatus according to any one of supplementary notes 1 to 4, wherein the reception unit includes: 
         [0261]    a branch unit for branching the received wavelength multiplexed signal light; and 
         [0262]    an input unit for selectively receiving the optical signal of the predetermined wavelength in the wavelength multiplexed signal light branched by the branch unit, 
         [0263]    wherein the input unit outputs the received optical signal of the predetermined wavelength to the comparison unit. 
       [Supplementary Note 7] 
       [0264]    An optical transmission apparatus comprising: 
         [0265]    a reception unit for receiving an optical signal of a predetermined wavelength; 
         [0266]    a transmission unit for incorporating an identifier uniquely identifying the optical transmission apparatus into the optical signal of the predetermined wavelength received by the reception unit, and transmitting the optical signal; and 
         [0267]    a multiplex unit for multiplexing and outputting the optical signal including the identifier and an optical signal of a wavelength different from the predetermined wavelength. 
       [Supplementary Note 8] 
       [0268]    The optical transmission apparatus according to supplementary note 7, further comprising: 
         [0269]    a pattern generation unit for generating a predetermined pattern, 
         [0270]    wherein the transmission unit transmits the optical signal of the predetermined wavelength including the predetermined pattern in accordance with a predetermined condition. 
       [Supplementary Note 9] 
       [0271]    An optical communication system comprising: 
         [0272]    an optical transmission apparatus including a first reception unit for receiving an optical signal of a predetermined wavelength, a first transmission unit for incorporating an identifier uniquely identifying the optical transmission apparatus into the optical signal of the predetermined wavelength received by the first reception unit, and transmitting the optical signal, and a multiplex unit for multiplexing and outputting the optical signal including the identifier and an optical signal of a wavelength different from the predetermined wavelength; and 
         [0273]    an optical reception apparatus including a second reception unit for receiving wavelength multiplexed signal light transmitted by the optical transmission apparatus, and a second transmission unit for transferring the optical signal of the predetermined wavelength in accordance with the identifier included in the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light. 
       [Supplementary Note 10] 
       [0274]    The optical communication system according to supplementary note 9, further comprising: 
         [0275]    a relay apparatus for branching and multiplexing the optical signal of the predetermined wavelength in a wavelength multiplexed optical signal that is output by the optical transmission apparatus; and 
         [0276]    an optical transmission and reception apparatus for receiving an optical signal branched by the relay apparatus, and transmitting the optical signal of the predetermined wavelength to the relay apparatus, 
         [0277]    wherein in accordance with an occurrence of a fault in a transmission path between the relay apparatus and the optical transmission and reception apparatus, the relay apparatus switches the optical signal, which is to be output to the optical reception apparatus, from the optical signal of the predetermined wavelength transmitted by the optical transmission and reception apparatus to the optical signal of the predetermined wavelength transmitted by the optical transmission apparatus. 
       [Supplementary Note 11] 
       [0278]    The optical communication system according to supplementary note 9 or 10, wherein the optical transmission apparatus further includes a pattern generation unit generating a predetermined pattern, and 
         [0279]    the first transmission unit transmits the optical signal of the predetermined wavelength including the predetermined pattern generated by the pattern generation unit in accordance with a predetermined condition. 
       [Supplementary Note 12] 
       [0280]    The optical communication system according to supplementary note 11 further comprising: 
         [0281]    a control apparatus detecting a fault that has occurred in the transmission path and notifying the fault to the optical transmission apparatus, 
         [0282]    wherein the optical transmission apparatus transmits the optical signal of the predetermined wavelength including the predetermined pattern in accordance with the notification from the control apparatus. 
       [Supplementary Note 13] 
       [0283]    An optical communication method comprising: 
         [0284]    receiving wavelength multiplexed signal light; and 
         [0285]    transferring an optical signal of a predetermined wavelength in accordance with an identifier included in the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light. 
       [Supplementary Note 14] 
       [0286]    The optical communication method according to supplementary note 13, comprising: 
         [0287]    determining whether the identifier and comparison information stored in advance match each other or not; and 
         [0288]    transferring the optical signal of the predetermined wavelength in a case where the identifier and the comparison information are determined to match each other. 
       [Supplementary Note 15] 
       [0289]    The optical communication method according to supplementary note 14, wherein in a case, determining that the identifier and the comparison information do not match each other, discarding the optical signal of the predetermined wavelength. 
       [Supplementary Note 16] 
       [0290]    The optical communication method according to supplementary note 14 or 15, further comprising: 
         [0291]    generating a predetermined pattern, 
         [0292]    wherein in a case, determining that the identifier and the comparison information do not match each other, outputting the optical signal of the predetermined wavelength including the predetermined pattern generated. 
       [Supplementary Note 17] 
       [0293]    The optical communication method according to any one of supplementary notes 13 to 16, further including: 
         [0294]    demultiplexing the received wavelength multiplexed signal light into the optical signal of the predetermined wavelength; and 
         [0295]    receiving the optical signal of the predetermined wavelength which is demultiplexing; and 
         [0296]    outputting the optical signal of the predetermined wavelength. 
       [Supplementary Note 18] 
       [0297]    The optical communication method according to any one of supplementary notes 13 to 16, further including: 
         [0298]    branching the received wavelength multiplexed signal light; and 
         [0299]    selectively receiving the optical signal of the predetermined wavelength in the wavelength multiplexed signal light which is branched; and 
         [0300]    outputting the received optical signal of the predetermined wavelength. 
       [Supplementary Note 19] 
       [0301]    The optical transmission method according to any one of supplementary notes 13 to 18, further including: 
         [0302]    receiving an optical signal of a predetermined wavelength; 
         [0303]    incorporating an identifier uniquely identifying an apparatus itself into the optical signal of the predetermined wavelength which is received, and transmitting the optical signal; and 
         [0304]    multiplexing and outputting the optical signal including the identifier and an optical signal of a wavelength different from the predetermined wavelength. 
       [Supplementary Note 20] 
       [0305]    The optical transmission method according to supplementary note 19 further including: 
         [0306]    generating a predetermined pattern, and 
         [0307]    transmitting the optical signal of the predetermined wavelength including the predetermined pattern in accordance with a predetermined condition. 
       [Supplementary Note 21] 
       [0308]    A program for causing a computer to execute: 
         [0309]    processing for receiving wavelength multiplexed signal light; and 
         [0310]    processing for transferring optical signal of the predetermined wavelength in accordance with the identifier included in the optical signal of the predetermined wavelength in the received wavelength multiplexed signal light. 
       [Supplementary Note 22] 
       [0311]    The program according to supplementary note 21, further comprising: 
         [0312]    processing of determining whether the identifier and comparison information stored in advance match each other or not; and 
         [0313]    processing of transferring the optical signal of the predetermined wavelength in a case where the identifier and the comparison information are determined to match each other. 
       [Supplementary Note 23] 
       [0314]    The program according to supplementary note 22, 
         [0315]    wherein in a case, determining that the identifier and the comparison information do not match each other, outputting the optical signal of the predetermined wavelength including the predetermined pattern which is generated. 
       [Supplementary Note 24] 
       [0316]    The program according to supplementary note 22 or 23, further comprising: 
         [0317]    processing of generating a predetermined pattern, and 
         [0318]    processing of transmitting the optical signal of the predetermined wavelength including the predetermined pattern in accordance with a predetermined condition. 
       [Supplementary Note 25] 
       [0319]    The program according to any one of supplementary notes 21 to 24, further comprising: 
         [0320]    processing of demultiplexing the received wavelength multiplexed signal light into the optical signal of the predetermined wavelength, 
         [0321]    processing of receiving the optical signal of the predetermined wavelength which is demultiplexing, and 
         [0322]    processing of outputting the optical signal of the predetermined wavelength. 
       [Supplementary Note 26] 
       [0323]    The program according to any one of supplementary notes 21 to 24, further comprising: 
         [0324]    processing of branching the received wavelength multiplexed signal light, 
         [0325]    processing of selectively receiving the optical signal of the predetermined wavelength in the wavelength multiplexed signal light which is branched, and 
         [0326]    processing of outputting the received optical signal of the predetermined wavelength. 
       [Supplementary Note 27] 
       [0327]    The program according to any one of supplementary notes 21 to 26 further comprising: 
         [0328]    processing of receiving an optical signal of a predetermined wavelength; 
         [0329]    processing of incorporating an identifier uniquely identifying the optical transmission apparatus into the optical signal of the predetermined wavelength which is received, and transmitting the optical signal; and 
         [0330]    processing of multiplexing and outputting the optical signal including the identifier and an optical signal of a wavelength different from the predetermined wavelength. 
         [0000]    [Supplementary Note 28] The program according to supplementary note 27 further comprising: 
         [0331]    processing of generating a predetermined pattern, and 
         [0332]    processing of transmitting, in accordance with a predetermined condition, the optical signal of the predetermined wavelength including the predetermined pattern which is generated. 
         [0333]    While the invention has been particularly shown and described with reference to exemplary embodiments thereof, the invention is not limited to these embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the claims. 
         [0334]    This application is based upon and claims the benefit of priority from Japanese patent application No. 2013-199940, filed on Sep. 26, 2013, the disclosure of which is incorporated herein in its entirety by reference. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1 - 1  optical reception apparatus 
           1 - 2  optical transmission apparatus 
           1 - 3  optical transmission and reception apparatus 
           10 ,  10 - 1 ,  10 - 2 ,  10 - 3 ,  10 - 4  base station 
           11  reception unit 
           12  transmission unit 
           13  comparison unit 
           14  storage unit 
           15  input unit 
           16  demultiplexing unit 
           17  branch unit 
           18  pattern generation unit 
           20  transmission path 
           21  reception unit 
           23  output unit 
           24  insertion unit 
           25  multiplex unit 
           30  BU 
           40 ,  40 - 1 ,  40 - 2 ,  40 - 3 ,  40 - 4  terminal apparatus 
           41 ,  41 - 1 ,  41 - 2 ,  41 - 3 ,  41 - 4 ,  41 - 5  transponder 
           42  client module 
           43  Framer LSI 
           44  insertion unit 
           45  line module 
           46  comparison unit 
           47  storage unit 
           48  pattern generation unit 
           50 ,  50 - 1 ,  50 - 2 ,  50 - 3 ,  50 - 4 ,  50 - 5  client apparatus 
           51 ,  51 - 1 ,  51 - 2 ,  51 - 3 ,  51 - 4  wavelength separation multiplex unit 
           61  encoding unit 
           62  decoding unit 
           70  EMS