Abstract:
An information processing apparatus, including a plurality of information processing elements, includes a transmission unit, provided in a first information processing element newly connected to the information processing apparatus, that transmits identification information of the first information processing element to a second information processing element among the plurality of information processing elements; a first control unit, provided in the second information processing element, that assigns address information to identification information of the first information processing element, generates element information including address information corresponding to identification information of the first information processing element and each of already implemented information processing elements, and returns the element information to the first information processing element; and a second control unit, provided in the first information processing element, that performs communication with an already implemented information processing element by using address information included in the element information received from the second information processing element.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2013-169258, filed on Aug. 16, 2013, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    The embodiments discussed herein are related to an information processing apparatus, an information processing method, and an information processing program. 
       BACKGROUND 
       [0003]    A building block system (also referred to as a BB system hereinafter) that implements a large scale information processing apparatus by connecting a plurality of information processing elements is known. Each information processing element of a BB system includes a processor and a memory and is capable of processing information. In addition, each information processing element has a communication function and is capable of processing information in cooperation with another information processing element. Each information processing element is accommodated in a case independently. Accordingly, in the explanations below, an information processing element is also referred to as a “case”. 
         [0004]    An information processing apparatus of a BB system may achieve a greater scale by newly adding a case to a network including a case that is already operating. When a new case is added to a BB system, the administrator manually sets parameters etc. used for communications with the new case. Thereafter, the administrator performs the confirmation of accesses between the new case and the network of the BB system. 
         [0005]    As a technique related to registration of setting information, a technique is known that servers inquiry and register environmental definitions each other in a network in which a plurality of servers are connected (for example Patent Document 1). 
       RELATED ART DOCUMENT 
     Patent Document 
       [0000]    
       
         [Patent Document 1]: Japanese Laid-open Patent Publication No. 2000-29808 
       
     
       SUMMARY 
       [0007]    According to an aspect of the embodiments, an information processing apparatus including a plurality of information processing elements, the information processing apparatus includes a transmission unit, a first control unit, and a second control unit. The transmission unit is provided in a first information processing element newly connected to the information processing apparatus, and transmits identification information of the first information processing element to a second information processing element among the plurality of information processing elements. The first control unit is provided in the second information processing element, and assigns address information to identification information of the first information processing element, generates element information including address information corresponding to identification information of each information processing element already implemented in the information processing apparatus and identification information of the first information processing element, and returns the element information to the first information processing element, when identification information of the first information processing element is received from the first information processing element. The second control unit is provided in the first information processing element, and performs communication with an information processing element already implemented in the information processing apparatus by using, as a communication source, address information included in the element information received from the second information processing element. 
         [0008]    The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
         [0009]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1A  illustrates an example of a method of adding a case to a BB system; 
           [0011]      FIG. 1B  illustrates an example of a method of adding a case to a BB system; 
           [0012]      FIG. 2  illustrates an example of a hardware configuration of a case; 
           [0013]      FIG. 3A  is a sequence diagram illustrating an example of a method of adding a case to a BB system; 
           [0014]      FIG. 3B  is a sequence diagram illustrating an example of a method of adding a case to a BB system; 
           [0015]      FIG. 3C  is a sequence diagram illustrating an example of a method of adding a case to a BB system; 
           [0016]      FIG. 3D  is a sequence diagram illustrating an example of a method of adding a case to a BB system; 
           [0017]      FIG. 4  is a sequence diagram illustrating an example of a process of establishing an encrypted communication; 
           [0018]      FIG. 5  is a sequence diagram illustrating an example of a process of network setting; 
           [0019]      FIG. 6  illustrates an example of a process related to the detection of an additional case; 
           [0020]      FIG. 7  illustrates an example of setting information used in an encrypted communication; 
           [0021]      FIG. 8  is a flowchart that explains an example of a process of an additional case after turning on the power; 
           [0022]      FIG. 9  is a flowchart explaining an example of a process of forming a communication path; 
           [0023]      FIG. 10  is a flowchart that explains an example of a setting process of information related to a network of an additional case; 
           [0024]      FIG. 11  is a flowchart that explains an example of a process of assigning an IP address to an additional case; 
           [0025]      FIG. 12  is a flowchart that explains an example of an access confirmation process from an additional case; 
           [0026]      FIG. 13  is a flowchart that explains an example of an access confirmation process on the side of a case that belongs to a BB system; and 
           [0027]      FIG. 14  explains an example of a process in which a master case is replaced when a failure has occurred. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    Hereinafter, detailed explanations will be given for the present embodiment by referring to the drawings. 
         [0029]      FIG. 1A  illustrates an example of a method of adding a case to a BB system. An administration terminal  150  is used when an administrator performs some operations for a BB system  160 . The BB system  160  is a system into which cases  110   a  through  110   c  are incorporated. The cases  110   a  through  110   c  coordinate with each other via a network  140 . The network  140  is an encrypted communication path. An additional case  120  is a case to be incorporated into the BB system  160 . The additional case  120  communicates with any of the cases  110   a  through  110   c  and automatically performs the incorporation setting into the BB system. The additional case  120  illustrated in  FIG. 1A  is connected to the case  110   a  via a serial cable  130 . The additional case  120  illustrated in  FIG. 1  communicates with the case  110   a  so as to automatically perform the incorporation setting into the BB system. 
         [0030]    Cases include transmission and reception units  111  ( 111   a  through  111   d ), control units  112  ( 112   a  through  112   d ) and storage units  113  ( 113   a  through  113   d ). The transmission and reception unit  111  receives a signal input to the case and transmits a signal to be output. The control unit  112  controls the process of incorporation setting into the BB system of the additional case  120 . The storage unit  113  stores a case list  114 , IP address information, and a host authentication key. A case list includes information related to a case that has already been incorporated into the BB system. The case lists  114  ( 114   a  through  114   c ) included in the cases  110   a  through  110   c  include information of case IDs (Identifications), IP addresses, host public keys, access confirmation, etc. which are associated with the respective cases  110   a  through  110   c . Since the additional case  120  is not incorporated into the BB system, the additional case  120  does not have a case list, and an IP address is not set. Hereinafter, explanations will be sequentially given for an automation process of incorporation setting into the BB system. 
         [0031]    (1) The control unit  112   d  of the additional case  120  generates a prescribed signal when the power of the additional case  120  is turned on. The control unit  112   d  transmits a prescribed signal to the transmission and reception unit  111   d.    
         [0032]    (2) The transmission and reception unit  111   d  of the additional case  120  transmits a prescribed signal to the case  110   a  via the serial cable  130 . 
         [0033]    (3) The transmission and reception unit  111   a  of the case  110   a  receives the prescribed signal and transmits it to the control unit  112   a.    
         [0034]    (4) By receiving the prescribed signal from the additional case  120 , the control unit  112   a  of the case  110   a  detects a case that has been added newly to the BB system  160  (i.e., the additional case  120 ). Then, the control unit  112   a  of the case  110   a  and the control unit  112   d  of the additional case  120  construct a TCP/IP path by for example the PPP and share a common key for encrypted communication between the case  110   a  and the additional case  120 . 
         [0035]    (5) The control unit  112   d  transmits to the transmission and reception unit  111   d  information that includes the case ID and the host public key and that is related to the additional case  120 . 
         [0036]    (6) The transmission and reception unit  111   d  transmits the information related to the additional case  120  to the case  110   a  via communication that has been encrypted by using the common key. 
         [0037]    (7) The transmission and reception unit  111   a  receives the information related to the additional case  120  and transmits it to the control unit  112   a.    
         [0038]    (8) The control unit  112   a  assigns an IP address to the additional case  120 . 
         [0039]    (9) The control unit  112   a  associates the IP address, the case ID and the host public key of the additional case  120 , and adds and registers them in the case list  114   a  of the storage unit  113   a.    
         [0040]    (10) The control unit  112   a  transmits the case list  114   a  to the transmission and reception unit  111   a.    
         [0041]    (11) The transmission and reception unit  111   a  transmits the case list  114   a  to the additional case  120 . 
         [0042]    (12) When the transmission and reception unit  111   d  receives the case list  114   a , the transmission and reception unit  111   d  transmits it to the control unit  112   d.    
         [0043]    (13) The control unit  112   d  stores in the storage unit  113   d  information included in the case list  114   a . This process generates the case list  114   d.    
         [0044]    (14) The control unit  112   d  extracts IP address information corresponding to the additional case  120  included in the case list  114   d.    
         [0045]    (15) The control unit  112   d  sets the extracted IP address information in the storage unit  113 . 
         [0046]    Communications between the case  110   a  and the additional case  120  in processes (5) through (15) are communications encrypted by using a common key. By processes (1) through (15), the administrator can save the manual setting operations related to IP address and encryption for the additional case  120 . In the process in which the administrator accesses the additional case  120  or the case  110  so as to perform a setting related to IP addresses and host public keys, IP addresses and host public keys are communicated without an encryption. However, by transmitting public keys and case information in communications encrypted beforehand by sharing a common key, safer communications are realized. The case ID registered in (9) is identification information corresponding to the additional case. Identification information is different for each case. Also, the host public key registered in (9) is used for the host authentication when communications are performed between cases. A host public key is generated in association with a host secret key at the initial activation of a case. The host public key and the host secret key are hold in the case which generated them. When there is an instruction to update a host authentication key based on prescribed manipulations by a user, a new host public key and host secret key are generated. 
         [0047]    All cases belonging to the BB system share information related to case IDs in the case lists  114 . A case ID is identification information of case which corresponds to a case belonging to the BB system. All cases belonging to the BB system share information related to IP addresses in the case lists  114 . Information related to an IP address may include information related to a network such as a net mask. All cases belonging to the BB system share information related to host public keys in the case lists  114 . The host public keys are registered in association with case IDs in the case lists  114 . The host authentication key is different for each case. Accordingly, each case has a host public key that corresponds to all cases belonging to the BB system. Each case belonging to the BB system has access confirmation information in the case list  114 . As access confirmation information, a result of access confirmation between the case and other cases is stored. Access confirmation is updated upon the activation of the BB system, access confirmation between cases, and a communication failure during an operation. 
         [0048]      FIG. 1B  illustrates an example of a method of adding a case to the BB system. In  FIG. 1B , the same elements as those in  FIG. 1A  are denoted by the same numbers. When an IP address has been set in the additional case  120 , the additional case  120  starts being able to perform communications with the cases  110   a  through  110   c . The additional case  120  performs access confirmation with the cases  110   a  through  110   c . The process related to the access confirmation will be described below. 
         [0049]    (16) The control unit  112   d  transmits the case list  114   d  to the transmission and reception unit  111   d.    
         [0050]    (17) The transmission and reception unit  111   d  transmits the case list  114   d  to the cases  110   a  through  110   c  via encrypted communications. 
         [0051]    (18) The transmission and reception unit  111   a  of the case  110   a  transmits the received case list  114   d  to the control unit  112   a.    
         [0052]    (19) The control unit  112   a  extracts information related to the additional case  120  from information included in the received case list  114   d , and registers it in the case list  114   a . The control unit  112   a  transmits the case list  114   a  to the transmission and reception unit  111   a.    
         [0053]    (20) The transmission and reception unit  111   a  transmits the case list  114   a  to the additional case  120 . 
         [0054]    (21) The transmission and reception unit  111   d  receives the case list  114   a . The transmission and reception unit  111   d  transmits the received case list  114   a  to the control unit  112   d.    
         [0055]    (22) The control unit  112   d  registers in the case list  114   d  the fact that access confirmation with the case  110   a  was able to be performed. Further, the fact that the access confirmation was able to be performed is also registered in the case list  114   a.    
         [0056]    The additional case  120  also performs the processes of (18) through (22) together with the cases  110   b  and  110   c . In  FIG. 1B , the process between the additional case  120  and the case  110   a  is indicated by arrow  1 . In  FIG. 1B , the process between the additional case  120  and the case  110   b  is indicated by arrow  2 . In  FIG. 1B , the process between the additional case  120  and the case  110   c  is indicated by arrow  3 . 
         [0057]    (23) When access confirmation with all cases has been terminated, the additional case  120  terminates the process. 
         [0058]    When there are a great number of cases that belongs to the BB system, it is troublesome for an administrator to perform the operations of access confirmation manually. It is possible to automatically make a diagnosis that the additional case  120  has normally been incorporated into the BB system. In addition, by transmitting case lists bidirectionally, bidirectional diagnoses are made. 
         [0059]      FIG. 2  illustrates an example of a hardware configuration of a case. The cases  110   a  through  110   c  and the additional case  120  have a processor  11 , a memory  12 , a bus  13 , an external storage device  14  and a network connection device  15 , respectively. Further, the cases  110   a  through  110   c  and the additional case  120  may optionally include an input device  16 , an output device  17  and a media driving device  18 , respectively. The case  110   a  through  110   c  and the additional case  120  may sometimes be implemented by for example a computer etc. In addition, the cases  110   a  through  110   c  and the additional case  120  may sometimes be implemented by a system board etc. 
         [0060]    The processor  11  may be an arbitrary processing circuit that includes a Central Processing Unit (CPU). The processor  11  executes the respective processes that are executed by the control unit  112 . Also, the processor  11  may execute for example a program stored in the external storage device  14 . The memory  12  operates as the storage unit  113  and appropriately stores data obtained through the operations of the processor  11  and data used for processes performed by the processor  11 . The network connection device  15  is used for communications with other devices. 
         [0061]    The input device  16  is implemented by for example a button, a keyboard, a mouse, etc., and the output device  17  is implemented by a display device etc. The bus  13  connects the processor  11 , the memory  12 , the input device  16 , the output device  17 , the external storage device  14 , the media driving device  18 , and the network connection device  15  in such a manner that data exchange is possible between them. The external storage device  14  stores a program, data, etc. and appropriately provides stored information to the processor  11  etc. The media driving device  18  can output data in the memory  12  and the external storage device  14  to a portable storage medium  19 , and can also read a program, data, etc. from the portable storage medium  19 . The portable storage medium  19  may be an arbitrary portable storage medium including a floppy disk, a Magnet-Optical (MO) disk, a Compact Disc Recordable (CD-R), and a Digital Versatile Disk Recordable (DVD-R). 
         [0062]      FIG. 3A  is a sequence diagram illustrating an example of a method of adding a case to the BB system. The sequence diagram illustrated in  FIG. 3  illustrates a communication process among the additional case  120 , the case  110   a , and the case  110   b  in  FIG. 1 . The case  110   a  is set as a master case of the BB system so as to accommodate, as a representative, communications with a case to be added newly. Hereinafter, sequential explanations will be given for the process of adding a case to the BB system. 
       &lt;Detection and Setting of Additional Case&gt; 
       [0063]    The additional case  120  and the case  110   a  are connected via a serial cable. When the power of the additional case  120  is turned on, the additional case  120  transmits a prescribed signal to the case  110   a . When the case  110   a  receives the prescribed signal, the case  110   a  detects that the power of the additional case  120  has been turned on. When the case  110   a  detects that the power of the additional case  120  is turned on, the case  110   a  forms a TCP/IP path with the additional case  120  using the PPP (Point-to-Point Protocol). The case  110   a  and the additional case  120  share a common key for communications so that they can perform encrypted communications with each other. 
         [0064]    The additional case  120  transmits information related to the additional case  120  such as the case ID, a host public key, etc. to the case  110   a . The case ID and the host public key are transmitted in an encrypted state by using a common key for communications. Next, the case  110   a  assigns an IP address to the additional case  120 . The IP address assigned to the additional case  120  is not used by other cases in the BB system, and is selected from among prescribed addresses to be used in the BB system. 
         [0065]    The case  110   a  registers, in the case list, information in which the IP address, the case ID and the host public key of the additional case  120  are associated. The case  110   a  transmits the case list to the additional case  120 . The additional case  120  extracts the IP address corresponding to the additional case  120  from the received case list, and sets the address. 
         [0066]      FIGS. 3B through 3D  are a sequence diagram illustrating an example of a method of adding a case to the BB system. 
       &lt;Access Confirmation&gt; 
       [0067]    The process of access confirmation is performed after “detection and setting of additional case” explained in  FIG. 3A . The additional case  120  makes access confirmation for all cases incorporated into the BB system. The additional case  120  extracts information of a case incorporated into the BB system from the case list. In the example in  FIG. 3 , the cases  110   a  and  110   b  are cases incorporated into the BB system. Regarding the access confirmation process, the explanations will be given in the order of the cases  110   a  and  110   b , however, this does not limit the order of the processes. 
         [0068]    The additional case  120  transmits, to the case  110   a , a forming request of an encrypted communication path. For this encrypted communication path, a host public key and a host authentication key are used. The case  110   a  forms an encrypted communication path between the additional case  120  and the case  110   a . The additional case  120  distributes the case list to the case  110   a . The case  110   a  adds to the case list of the case  110   a  information of the IP address and the host public key of the additional case  120  from the received case list. In the case list of the case  110   a , the additional case  120  is registered as a case whose access has not been confirmed. Thereafter, the case  110   a  disconnects the encrypted communication path. The additional case  120  determines that the transmission confirmation to the case  110   a  is OK. 
         [0069]    Next, the case  110   a  transmits a forming request of an encrypted communication path to the additional case  120 . The additional case  120  forms an encrypted communication path between the additional case  120  and the case  110   a . The case  110   a  transmits a case list to the additional case  120 . The additional case  120  receives the case list. The additional case  120  determines that the reception confirmation from the case  110   a  is OK. The additional case  120  registers in the case list of the additional case  120  that the access confirmation of transmission and reception with the case  110   a  is OK. Thereby, it is possible to perform bidirectional access confirmation and to perform a test of whether the formation of an encrypted communication path is normal. 
         [0070]    The additional case  120  transmits a forming request of an encrypted communication path to the case  110   b . The case  110   b  forms an encrypted communication path between the additional case  120  and the case  110   b . The additional case  120  distributes the case list to the case  110   b . The case  110   b  adds to the case list of the case  110   b  information of the IP address and the host public key of the additional case  120  from the received case list. In the case list of the case  110   b , the additional case  120  is registered as a case whose access has not been confirmed. Thereafter, the case  110   b  disconnects the encrypted communication path. The additional case  120  determines that the transmission confirmation to the case  110   b  is OK. 
         [0071]    Next, the case  110   b  transmits a forming request of an encrypted communication path to the additional case  120 . The additional case  120  forms an encrypted communication path between the additional case  120  and the case  110   b . The case  110   b  transmits a case list to the additional case  120 . The additional case  120  receives the case list. The additional case  120  determines that the reception confirmation from the case  110   b  is OK. The additional case  120  registers in the case list of the additional case  120  that the access confirmation of transmission and reception with the case  110   b  is OK. 
         [0072]    The additional case  120  registers in the case list of the case  110   a  that the access confirmation of transmission and reception between the additional case  120  and the case  110   a  is OK. Further, the additional case  120  registers in the case list of the case  110   b  that access confirmation of transmission and reception between the additional case  120  and the case  110   b  is OK. Thereby, the hardware of the additional case is incorporated into the BB system. 
       &lt;System Setting Update&gt; 
       [0073]    When the additional case  120  has been incorporated into the BB system, the administrator pulls out the serial cable. When an administrator performs a system setting on the case  110   a , change information of setting is shared by the additional case  120  and the case  110   b  and the setting is reflected. 
         [0074]      FIG. 4  is a sequence diagram illustrating an example of a process of establishing an encrypted communication.  FIG. 4  illustrates an example of a process of establishing an encrypted communication between the additional case  120  and the case  110  illustrated in  FIG. 1 . The case  110  may be any cases belonging to the BB system and may be either the case  110   a  or the case  110   b  illustrated in  FIG. 1 . 
         [0075]    The additional case  120  performs status confirmation of the case  110 . The additional case  120  outputs to the case  110  a confirmation signal representing whether or not the case  110  has been activated. When the case  110  has been activated, the case  110  outputs to the additional case  120  a response signal representing that the case  110  is in operation. The additional case  120  receives a response signal representing that the case  110  is in operation. 
         [0076]    Next, the additional case  120  outputs to the case  110  a connection request. The case  110  transmits to the additional case  120  a host public key corresponding to the case  110 . The additional case  120  receives the host public key. The additional case  120  waits for the transmission of the host public key corresponding to the connection request for a prescribed period of time. When the prescribed period of time has elapsed, the additional case  120  determines that the connection to the case  110  has failed and terminates the connection process. 
         [0077]    When the additional case  120  receives the host public key of the case  110 , the additional case  120  confirms whether or not the case  110  has the host secret key. The confirmation of a host secret key is performed by using challenge response authentication. The additional case  120  generates random numbers. The additional case  120  encrypts the generated random numbers by using the host public key and reports the encrypted random numbers to the case  110 . The case  110  decrypts the encrypted random numbers by using the host secret key and reports the decrypted random numbers to the additional case  120 . The additional case  120  receives the random numbers reported from the case  110  and determines whether or not the received numbers are identical to the generated random numbers. The additional case  120  waits for the reception of the random numbers decrypted by the case  110  for a prescribed period of time, and when the prescribed period of time has elapsed, the additional case  120  determines that the connection to the case  110  has failed and terminates the process. 
         [0078]    The additional case  120  makes the additional case  120  and the case  110  share a common secret key for an encrypted communication. The additional case  120  generates a common secret key. The additional case  120  encrypts the generated common secret key by using the host public key, and transmits it to the case  110 . The case  110  decrypts the encrypted common secret key by using the host secret key. Thereby, the encrypted communication is made possible between the additional case  120  and the case  110 . 
         [0079]      FIG. 5  is a sequence diagram illustrating an example of a process of network setting.  FIG. 5  explains the process illustrated in  FIG. 3A  in more detail, and is a sequence diagram for a process executed after a TCP/IP path using the PPP is formed between the case  110  and the additional case  120 .  FIG. 5  explains a communication process between the additional case  120  and the case  110 . “MAGIC CODE” used for forming a PPP path in  FIG. 5  is the prescribed signal generated in the process of (1). 
         [0080]    The additional case  120  reports to the case  110  a request that case information related to the additional case  120  be registered. The request that the case information be registered includes a case ID, host public key, etc. The additional case  120  waits for a response to the request that the case information be registered. 
         [0081]    In response to the request that the case information be registered, the case  110  adds information related to the additional case to the case list. The case  110  transmits the updated case list to the additional case  120  as a response corresponding to the request that the case information be registered. The additional case  120  extracts the IP addresses associated with the case ID of the additional case  120  from the received case list. The additional case  120  sets the IP address. 
         [0082]      FIG. 6  illustrates an example of a process related to the detection of an additional case.  FIG. 6  illustrates an example related to a process in which the case  110  detects the additional case  120  when the additional case  120  is added to the BB system. The additional case  120  in  FIG. 6  includes a generation unit  211   a , a transmission and reception unit  212   a , a buffer  213   a , and a comparison unit  214   a . The case  110  includes a generation unit  211   b , a transmission and reception unit  212   b , a buffer  213   b , and a comparison unit  214   b.    
         [0083]    When the additional case  120  is added to the BB system, the generation unit  211   a  generates a prescribed signal including an expectation value. An expectation value is a parameter, a code, a value, etc. that are prescribed in accordance with the series, the model, and the manufacturer of the case. The generation unit  211   a  is included in the control unit  112  illustrated in  FIG. 1 . The additional case  120  and the case  110  are connected via a serial cable. The transmission and reception unit  212   a  transmits a prescribed signal to the transmission and reception unit  212   b  via a serial cable. Receiving the prescribed signal, the transmission and reception unit  212   b  stores the prescribed signal in the reception buffer  213   b . The comparison unit  214   b  reads the prescribed signal from the reception buffer  213   b  and compares the signal with an expectation value beforehand stored in the case  110 . The comparison unit  214   b  identifies the series, the model, the manufacturer, etc. of the case by using the comparison result. By these processes, the case  110  detects that the additional case  120  has been connected. 
         [0084]      FIG. 7  illustrates an example of setting information used in an encrypted communication. The host secret key of case #n is generated by case #n when a case is to be set initially. The host secret key is held by case #n. Next, the host public key of case #n is generated by case #n as a counterpart of the host secret key when the case is to be set initially. The host public key is held by all cases belonging to the BB system. The same host public key and host secret key are used until a new host key is generated. The random numbers of the challenge response authentication in  FIG. 4  are generated by case #m upon authentication. In addition, random numbers are held by case #m until the termination of the authentication. The common secret key between cases #m and #n is generated by case #m. The common secret key is held by cases #m and #n until the termination of the encrypted communications. 
         [0085]      FIG. 8  is a flowchart that explains an example of a process of an additional case after turning on the power. The processes in the respective steps in  FIG. 8  are executed by the control unit  112   d  of the additional case  120  illustrated in  FIG. 1 . Any cases belonging to the BB system may be the case  110  and either of the cases  110   a  and  110   b  can be the case  110 . The control unit  112   d  determines whether or not a setting regarding a network has been performed (step S 101 ). When the setting regarding the network of the additional case  120  has been completed, the control unit  112   d  activates the additional case  120  as a case belonging to the BB system (step S 102  and NO in step S 101 ). The control unit  112   d  generates a prescribed signal and transmits the prescribed signal (magic code) to a serial cable (step S 103  and YES in step S 101 ). The control unit  112   d  waits for a prescribed period of time until a forming request of a PPP path is transmitted from the case  110  (step S 104 ). The control unit  112   d  determines whether or not the prescribed period of time in S 104  has elapsed (step S 105 ). The control unit  112   d  terminates the process (step S 106  and YES in step S 105 ). 
         [0086]    The control unit  112   d  forms a TCP/IP path using the PPP for the data link layer between the additional case  120  and the case  110  (step S 107 ). The control unit  112   d  uses the Diffie-Hellman algorithm so as to make the additional case  120  and the case  110  share a common key for communications (step S 108 ). The control unit  112   d  starts encrypted communications using the common key between the additional case  120  and the case  110  (step S 109 ). 
         [0087]    Note that while the Diffie-Hellman algorithm is exemplified as a process of sharing a common key for communications in S 108 , methods of sharing a common key are not particularly limited. The prescribed period of time in S 105  may be changed by an administrator and is not limited to a particular period of time. 
         [0088]      FIG. 9  is a flowchart explaining an example of a process of forming a communication path. The processes in the respective steps in  FIG. 9  are executed by any of the control units  112   a  through  112   c  of the cases  110   a  through  110   c  illustrated in  FIG. 1 . The process in  FIG. 9  may be executed by a case that has already been incorporated into the BB system. In the example in  FIG. 9 , the case  110   a  performs communications with the additional case  120  as a representative of the BB system. 
         [0089]    The control unit  112   a  determines whether or not there is a signal input from the serial cable (step S 201 ). The control unit  112   a  executes the process in S 201  (NO in step S 201 ). The control unit  112   a  determines whether or not there is a prescribed signal in the receiving buffer of the case  110   a  (step S 202  and YES in step S 201 ). The control unit  112   a  terminates the process and executes the process under control of a console (step S 203  and NO in step S 202 ). The control unit  112   a  transmits a forming request of a PPP path to the additional case  120  (step S 204  and YES in step S 202 ). The control unit  112   a  forms a TCP/IP path that uses the PPP for the data link layer between the additional case  120  and the case  110  (step S 205 ). The control unit  112   a  uses the Diffie-Hellman algorithm so as to make the additional case  120  and the case  110  share a common key for communications (step S 206 ). The control unit  112   a  starts the encrypted communication using the common key between the additional case  120  and the case  110  (step S 207 ). 
         [0090]      FIG. 10  is a flowchart that explains an example of a setting process of information related to a network of an additional case.  FIG. 10  is a flowchart that explains a process executed by the additional case  120  after the process in S 109  in  FIG. 8 . The processes in the respective steps in  FIG. 10  are executed by the control unit  112   d  of the additional case  120  illustrated in  FIG. 1 . 
         [0091]    The control unit  112   d  reports to the case  110  a request that case information related to the additional case  120  be registered (step S 301 ). The control unit  112   d  waits for a response to the request that the case information be registered (step S 302 ). The control unit  112   d  determines whether or not a prescribed period of time has elapsed as a period of time for waiting for the request that the case information be registered (step S 303 ). The control unit  112   d  terminates the process (step S 304  and YES in step S 303 ). The control unit  112   d  obtains information which is related to the network corresponding to the additional case  120  and which is included in the response to the request that the case information be registered (step S 305  and NO in step S 303 ). The control unit  112   d  performs a network setting of the additional case  120  (step S 306 ). The control unit  112   d  completes the network setting of the additional case  120 . 
         [0092]    Note that the prescribed period of time in S 303  may be changed by an administrator and is not limited to a particular period of time. 
         [0093]      FIG. 11  is a flowchart that explains an example of a process of assigning an IP address to an additional case.  FIG. 11  is a flowchart that explains a process executed by the case  110  after the process in S 207  in  FIG. 9 . The processes in the respective steps in  FIG. 11  are executed by any of the control units  112   a  through  112   c  of the cases  110   a  through  110   c  illustrated in  FIG. 1 . The process in  FIG. 11  may be executed by a case that has already been incorporated into the BB system. In the example of  FIG. 11 , the case  110   a  performs communications with the additional case  120  as a representative of the BB system. 
         [0094]    The control unit  112   a  waits for a request that the case information related to the additional case  120  be registered (step S 401 ). The control unit  112   a  determines whether or not a prescribed period of time has elapsed as a period of time for waiting for the request that the case information be registered (step S 402 ). The control unit  112   a  terminates the process of assigning an IP address to the additional case  120  (step S 403  and YES in step S 402 ). The control unit  112   a  obtains the case ID and the host public key which are included in the request that the case information related to the additional case  120  be registered (step S 404  and NO in step S 402 ). The control unit  112   a  selects an IP address to be assigned to the additional case from a scope of IP addresses that has been set beforehand (step S 405 ). The control unit  112   a  registers information related to the IP address, the case ID, and the host public key of the additional case  120  in the case list of the case  110  (step S 406 ). The control unit  112   a  transmits the updated case list to the additional case  120  (step S 407 ). 
         [0095]    Note that the prescribed period of time in S 402  may be changed by an administrator and is not limited to a particular period of time. 
         [0096]      FIG. 12  is a flowchart that explains an example of an access confirmation process from an additional case.  FIG. 12  is a flowchart that explains a process executed by the additional case  120  after the process in S 306  illustrated in  FIG. 10 . The processes in the respective steps in  FIG. 12  are executed by the control unit  112   d  of the additional case  120  illustrated in  FIG. 1 . 
         [0097]    The control unit  112   d  executes a forming process of an encrypted path for the case  110  (step S 501 ). The control unit  112   d  determines whether or not the forming process of an encrypted path in S 501  failed (step S 502 ). The control unit  112   d  transmits the case list to the case  110  (step S 503 ). The control unit  112   d  disconnects the encrypted path (step S 504 ). The encrypted path is formed between the case  110  and the additional case  120  (step S 505 ). The control unit  112   d  waits for a response of the case list from the case  110  (step S 506 ). The control unit  112   d  determines whether or not the response of a case list is absent (step S 507 ). The control unit  112   d  determines whether or not the case list received in step S 507  and the case list transmitted in S 503  are different (step S 508  and NO in step S 507 ). The control unit  112   d  sets to success the status of the access confirmation with the case  110  in the held case list (step S 509  and NO in step S 508 ). The control unit  112   d  sets to failure the status of the access confirmation with the case  110  in the held case list (step S 511 , YES in step S 502 , YES in step S 507 , and YES in step S 508 ). The control unit  112   d  disconnects the encrypted path (step S 510 ). 
         [0098]      FIG. 13  is a flowchart that explains an example of an access confirmation process on the side of the case that belongs to the BB system.  FIG. 13  is a flowchart that explains a process executed by the case  110  after the process in S 407  in  FIG. 11 . The processes in the respective steps in  FIG. 13  are executed by any of the control units  112   a  through  112   c  of the cases  110   a  through  110   c  illustrated in  FIG. 1 . The process in  FIG. 13  may be executed by a case that has already been incorporated into the BB system. In the example in  FIG. 13 , the case  110   a  performs communications with the additional case  120  as the representative of the BB system. 
         [0099]    An encrypted path is formed between the case  110  and the additional case  120  (step S 601 ). The control unit  112   a  waits for a case list to be distributed (step S 602 ). The control unit  112   a  determines whether or not the case list held by the case  110   a  includes information related to the additional case  120  (step S 603 ). The control unit  112   a  registers information related to the additional case  120  in the case list (step S 604  and YES in step S 603 ). The control unit  112   a  disconnects the encrypted path (step S 605  and NO in step S 603 ). 
         [0100]    The control unit  112   a  performs a forming process of an encrypted path for the additional case  120  (step S 606 ). The control unit  112   a  determines whether or not the forming of the encrypted path failed (step S 607 ). The control unit  112   a  transmits the case list to the additional case  120  (step S 608  and NO in step S 607 ). The control unit  112   a  determines whether or not the transmission of the case list failed (step S 609 ). The control unit  112   a  sets to failure the status of the access confirmation with the additional case in the case list held by the case  110  (step S 610  and YES in step S 609 ). The control unit  112   a  sets to success the status of the access confirmation with the additional case in the case list held by the case  110  (step S 611  and NO in step S 609 ). The control unit  112   a  disconnects the encrypted path (step S 612 ). 
         [0101]    As described above, according to the method of an embodiment, the IP address of the additional case  120  is set automatically, and it is possible to automate processes up to the bidirectional access confirmation with all cases belonging to the BB system. 
       &lt;Others&gt; 
       [0102]      FIG. 14  explains an example of a process in which a master case is replaced when a failure has occurred. In  FIG. 14 , the same elements as in  FIG. 1  are denoted by the same symbols. In  FIG. 1 , the additional case  120  performs communications with the case  110   a . A case is illustrated in which the case  110   a  has failed so that communication between the additional case  120  and the case  110   a  is impossible via the serial cable  130 . When the case  110   a  has failed, the process of the case  110   a  is taken over by the case  110   b . Since the master case is in some cases replaced as illustrated in  FIG. 14 , the host public key is held by all cases. 
         [0103]    All examples and conditional language provided herein are intended for the pedagogical purpose of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the inventions. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.