Control device, communication control system, and control method

Abstract

A control device that transmits an instruction for switching path setting to a controlled device that transfers communication data between terminals, the control device comprising: a preparation start timing determination unit that, on the basis of the preparation time of the path setting in each controlled device, determines a timing at which the controlled device starts to prepare the path setting; and a path setting control unit that transmits a path setting switching instruction to the controlled device so that the controlled device starts to prepare the path setting at the timing.

Description

Control device, communication control system, and control method

[0001] The present invention relates to a control device, a communication control system, and a control method.

[0002] In conventional optical communication systems, the timing of switching route settings between multiple devices that relay communications between terminals is not synchronized, resulting in a problem of extended periods of time when communication data cannot be sent or received between terminals.

[0003] International Publication No. 2023 / 157399

[0004] In view of the above circumstances, an object of the present invention is to provide a technique that can shorten the time during which communication data cannot be transmitted or received between terminals.

[0005] One aspect of the present invention is a control device that transmits an instruction to switch route settings to a controlled device that transfers communication data between terminals, and includes: a preparation start timing determination unit that determines the timing at which the controlled device will start preparing for route setting based on the preparation time for the route setting in each of the controlled devices; and a route setting control unit that transmits a route setting switching instruction to the controlled device so that the controlled device will start preparing for route setting at the timing.

[0006] One aspect of the present invention is a communication control system comprising a controlled device that transfers communication data between terminals, and a control device that transmits an instruction to switch route settings to the controlled device, wherein the control device comprises a preparation start timing determination unit that adds information on the timing to start preparation for route switching to a route setting switch instruction, which is an instruction to switch route settings, based on the preparation time for the route setting in each of the controlled devices, and a route setting control unit that transmits the route setting switch instruction to the controlled device, and the controlled device starts preparation for route setting based on the timing indicated by the route setting switch instruction.

[0007] One aspect of the present invention is a communication control system comprising a controlled device that transfers communication data between terminals, and a control device that sends an instruction to switch route settings to the controlled device, wherein the control device comprises a preparation start timing determination unit that determines when the controlled device will start preparing for route setting based on an instruction response time, which is the time from the timing of sending a route setting switch instruction to the controlled device to the timing of receiving a switch start notification from the controlled device, and a route setting control unit that sends a route setting switch instruction to the controlled device so that the controlled device will start preparing for route setting at the timing, and the controlled device starts preparing for route setting based on the timing indicated by the route setting switch instruction, and sends a switch start notification to the control device at the timing to start switching.

[0008] One aspect of the present invention is a control method for sending an instruction to switch route settings to a controlled device that transfers communication data between terminals, the control method comprising: a preparation start timing determination step for determining the timing at which the controlled device starts preparing for route setting based on the preparation time for the route setting in each of the controlled devices; and a route setting control step for sending a route setting switching instruction to the controlled device so that the controlled device starts preparing for route setting at the timing.

[0009] According to the present invention, it is possible to reduce the time during which communication data cannot be transmitted or received between terminals.

[0010] FIG. 1 is an overall configuration diagram of an optical communication system 1 according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of a control device 300 according to a first embodiment. FIG. 3 is a diagram showing an example of the timing of transmission of a path setting switch instruction from the control device 300. FIG. 4 is a flowchart showing an example of the operation of a control system according to the first embodiment. FIG. 5 is a diagram showing an example of the timing of transmission of a path setting switch instruction from the control device 300. FIG. 6 is a flowchart showing an example of the operation of a control system according to a second embodiment. FIG. 7 is a diagram showing the configuration of a control device 300 according to a third embodiment. FIG. 8 is a flowchart showing an example of the operation of the control system according to the third embodiment. FIG. 9 is a flowchart showing a modified example of the operation of the control system according to the first embodiment.

[0011] Hereinafter, a control device and a control method according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0012] [Configuration of Optical Communication System] Fig. 1 is an overall configuration diagram of an optical communication system 1 according to one embodiment of the present invention. As shown in Fig. 1, the optical communication system 1 is configured to include terminals 100-1 and 100-2, control target devices 200-1 and 200-2, and a control device 300. In the following description, when it is not necessary to distinguish between the terminals 100-1 and 100-2, they may be simply referred to as "terminals 100." In the following description, when it is not necessary to distinguish between the control target devices 200-1 and 200-2, they may be simply referred to as "control target devices 200."

[0013] The control target device 200 is an example of a communication device of the present invention. The control device 300 is an example of a communication control device of the present invention. Furthermore, a control system including the control target device 200 and the control device 300 is an example of a communication control system of the present invention.

[0014] The optical communication system 1 illustrated in FIG. 1 has two terminals 100 and two control target devices 200, but may have more terminals 100 and control target devices 200.

[0015] The terminal 100 transmits and receives communication data to and from other terminals 100 via the control target device 200 .

[0016] The controlled device 200 is installed in a communication network between multiple terminals 100 that communicate with each other. The controlled device 200 is a device that transfers communication data sent and received between the multiple terminals 100. Communication data is input to the controlled device 200 from the terminals 100 or other controlled devices 200. The controlled device 200 outputs the communication data to the terminals 100 or other controlled devices 200.

[0017] Furthermore, the control target device 200 has a plurality of input / output ports. The control target device 200 switches the communication data path through which communication data is transmitted by performing path setting that switches the communication connection between the input / output ports inside the device itself. The control target device 200 prepares to switch the communication data path, and switches the communication data path after preparation is complete. Hereinafter, the time during which the control target device 200 makes preparations to switch the communication data path will be referred to as the "preparation time," and the time during which the communication data path is actually switched will be referred to as the "switching time." During the switching time during which the control target device 200 is switching the communication data path, the control target device 200 cannot transfer communication data received from the terminal 100 or other control target devices 200.

[0018] The control device 300 controls the path setting performed by the control target device 200. The control device 300 controls the path setting performed by one or more control target devices 200, thereby controlling switching of signal paths for communication data transmitted and received between multiple terminals 100.

[0019] 1, the optical communication system 1 is configured such that one control device 300 controls multiple control target devices 200, but the configuration is not limited to this. For example, the optical communication system 1 may be configured such that a separate control device 300 is installed for each control target device 200.

[0020] [Configuration of Control Device] The following provides a more detailed description of the control device 300. Fig. 2 is a diagram showing the configuration of the control device 300 according to the first embodiment.

[0021] As shown in FIG. 2, the control device 300 includes a control target device information acquisition unit 301 , a control target device information storage unit 302 , a preparation start timing determination unit 303 , and a path setting control unit 304 .

[0022] The control target device information acquisition unit 301 acquires information on the preparation time of each control target device 200 that has been notified from a higher-level device or input by an operator through an input operation.

[0023] The control target device information storage unit 302 stores the preparation time of each control target device 200 acquired by the control target device information acquisition unit 301 .

[0024] The preparation start timing determination unit 303 determines the timing to transmit a path setting switching instruction to the control-target device 200 based on the control-target device 200 that transmits the path setting switching instruction and the preparation time of the control-target device 200. The control-target device 200 that transmits the path setting switching instruction is specified by notification from a higher-level device or by input operation by an operator. The preparation time of the control-target device 200 is stored in the control-target device information storage unit 302. The preparation start timing determination unit 303, for example, reads the preparation time of the specified control-target device 200 from the control-target device information storage unit 302, and determines the timing to transmit a path setting switching instruction to the control-target device 200 based on the read preparation time.

[0025] The path setting control unit 304 controls path setting by transmitting a path setting switching instruction to the specified control-target device 200 at the transmission timing determined by the preparation start timing determination unit 303. When the control-target device 200 receives the path setting switching instruction, it prepares to switch the communication data path and switches the communication data path. By varying the transmission timing of the path setting switching instruction for each control-target device 200, the timing at which switching preparation is started in the control-target devices 200 can be varied.

[0026] A method for determining the transmission timing will be described below. The preparation start timing determination unit 303 sets the time between the timing at which a path setting switching instruction is transmitted to one control-target device 200 and the timing at which a path setting switching instruction is transmitted to another control-target device 200 to the difference in preparation time between the two control-target devices 200 that transmit the path setting switching instruction. The preparation start timing determination unit 303 also sets the timing at which the path setting switching instruction is transmitted so that the path setting switching instruction is transmitted first to the control-target device 200 that has had a longer preparation time.

[0027] 3 is a diagram showing an example of the timing of transmission of a path setting switch instruction from the control device 300. The example shown in FIG. 3 shows that the control target device 200-1 and the control target device 200-2 are designated to transmit a path setting switch instruction, and the control device 300 transmits the path setting switch instruction to the control target device 200-1 and the control target device 200-2. The preparation time in the control target device 200-1 is t １ The preparation time for the control target device 200-2 is t ２ and t ２ >t １ In this case, the preparation start timing determination unit 303 determines the time between the timing of transmitting a path setting switch instruction to the control target device 200-1 and the timing of transmitting a path setting switch instruction to the control target device 200-2 as the preparation time t １ and the preparation time t ２ The difference between ２ -t １ Furthermore, the preparation start timing determination unit 303 determines the timing to transmit the path setting switch instruction so that, out of the control target device 200-1 and the control target device 200-2, the path setting switch instruction is transmitted first to the control target device 200-2 which has a longer preparation time.

[0028] 4 is a flowchart showing an example of the operation of the control system in the first embodiment. First, the control target device information acquisition unit 301 of the control device 300 acquires information on the preparation time of each control target device 200 (step S001). The acquired information is stored in the control target device information storage unit 302 (step S002). The preparation start timing determination unit 303 determines the timing of transmitting a path setting switching instruction to each control target device 200 based on the preparation time of each control target device 200 stored in the control target device information storage unit 302 (step S003). As a result, the time difference between the transmission timings when the control device 300 transmits path setting switching instructions to two control target devices 200 is determined.

[0029] When controlling the path setting of the control target devices 200, the path setting control unit 304 transmits a path setting switching instruction to each control target device 200 at the transmission timing determined by the preparation start timing determination unit 303. As shown in FIG. 3, when the preparation time of the control target device 200-1 is t １ and the preparation time of the control target device 200-2 is t ２ When this is the case, the path setting control unit 304 transmits a path setting switching instruction to the control target device 200-2 (step S004-2), and ２ -t １ ) and then transmits a path setting switching instruction to the control target device 200-1 (step S004-1). When the control target device 200-1 and the control target device 200-2 each receive the path setting switching instruction, they start preparations for switching the communication data path (step S005). Thereafter, the control target device 200-1 and the control target device 200-2 take a predetermined time to complete switching of the communication data path.

[0030] Similarly, when three or more control-target devices 200 are specified as destinations of the path setting switching instruction, the time between the timings of transmitting the path setting switching instruction to two control-target devices 200 is set to the difference in preparation times of the two control-target devices 200, and the timing of transmitting the path setting switching instruction is set so that the path setting switching instruction is transmitted first to the control-target device 200 with the longer preparation time. In other words, the timing of transmitting the path setting switching instruction to the control-target devices 200 is set to a time delayed from the timing of transmitting the path setting switching instruction to the control-target device 200 with the longest preparation time by the difference between the longest preparation time of the specified control-target devices 200 and the preparation time of the control-target device 200 that is the transmission destination.

[0031] At this time, the control device 300 transmits a path setting switching instruction first to the control-target device 200 with a longer preparation time. Also, by setting the difference in timing for transmitting the path setting switching instruction to the difference in preparation time of each control-target device 200, the control-target devices 200 that transmitted the path setting switching instruction can be made to start switching the path setting at similar timing. This makes it possible to shorten the time during which communication data cannot be sent or received between the terminals 100.

[0032] Second Embodiment A second embodiment will be described below. In the second embodiment, the control device 300 determines the timing of transmitting a path setting switching instruction to each control-target device 200, taking into consideration not only the preparation time of each control-target device 200 but also the propagation time of the path setting switching instruction transmitted from the control device 300 to each control-target device 200. In the second embodiment, other configurations are the same as those of the first embodiment. Hereinafter, the sum of the preparation time of the control-target device 200 and the propagation time of the path setting switching instruction transmitted from the control device 300 to the control-target device 200 will be referred to as the "control time" of the control-target device 200.

[0033] In the second embodiment, the control target device information acquisition unit 301 acquires information on the control time of each control target device 200, which is notified from a higher-level device or input by an input operation by an operator. In the second embodiment, the control target device information acquisition unit 301 may acquire information on the preparation time of each control target device 200, which is notified from a higher-level device or input by an input operation by an operator, measure the propagation time of a path setting switching instruction transmitted from the control device 300 to each control target device 200, and acquire the control time of each control target device 200 by adding the acquired preparation time of each control target device 200 to the measured propagation time. The propagation time of the path setting switching instruction transmitted from the control device 300 to each control target device 200 is measured, for example, by transmitting a Ping or the like from the control device 300 to each control target device 200.

[0034] In the second embodiment, the control target device information storage unit 302 stores the control time of each control target device 200 acquired by the control target device information acquisition unit 301 .

[0035] In the second embodiment, the preparation start timing determination unit 303 determines the timing to transmit the path setting switching instruction to the control-target device 200 based on the control-target device 200 that transmits the path setting switching instruction and the control time of the control-target device 200. The control-target device 200 that transmits the path setting switching instruction is specified by notification from a higher-level device or by an input operation by an operator. The preparation start timing determination unit 303, for example, reads the control time of the specified control-target device 200 from the control-target device information storage unit 302, and determines the timing to transmit the path setting switching instruction to the control-target device 200 based on the read control time.

[0036] In the second embodiment, the preparation start timing determination unit 303 sets the time between the timing at which a path setting switching instruction is transmitted to one control-target device 200 and the timing at which a path setting switching instruction is transmitted to another control-target device 200 to the difference in control times of the two control-target devices 200 that transmit the path setting switching instruction. The preparation start timing determination unit 303 also sets the timing at which the path setting switching instruction is transmitted so that the path setting switching instruction is transmitted first to the control-target device 200 that has the longer control time.

[0037] 5 is a diagram showing an example of the timing of transmission of a path setting switch instruction from the control device 300. The example shown in FIG. 5 shows that the control target device 200-1 and the control target device 200-2 are designated to transmit a path setting switch instruction, and the control device 300 transmits the path setting switch instruction to the control target device 200-1 and the control target device 200-2. The preparation time in the control target device 200-1 is t １ The preparation time for the control target device 200-2 is t ２ The propagation time of the path setting switching instruction transmission from the control device 300 to the control target device 200-1 is u １ The propagation time of the path setting switching instruction transmission from the control device 300 to the control target device 200-2 is u ２ Here, t ２ +u ２ >t １ +u １ In this case, the preparation start timing determination unit 303 determines the time between the timing of transmitting a path setting switch instruction to the control target device 200-1 and the timing of transmitting a path setting switch instruction to the control target device 200-2 as the control time t １ +u １ and the control time t ２ +u ２ is the difference between ２ +u ２ )-(t １ +u １) In addition, the preparation start timing determination unit 303 determines the timing to transmit the path setting switching instruction so that, of the control target device 200-1 and the control target device 200-2, the path setting switching instruction is transmitted first to the control target device 200-2, which has a longer control time.

[0038] 6 is a flowchart showing an example of the operation of the control system in the second embodiment. First, the control target device information acquisition unit 301 of the control device 300 acquires information on the control time of each control target device 200 (step S101). The acquired information is stored in the control target device information storage unit 302 (step S102). The preparation start timing determination unit 303 determines the timing of transmitting a path setting switching instruction to each control target device 200 based on the control time of each control target device 200 stored in the control target device information storage unit 302 (step S103). As a result, the time difference between the transmission timings when the control device 300 transmits path setting switching instructions to two control target devices 200 is determined.

[0039] When controlling the path setting of the control target devices 200, the path setting control unit 304 transmits a path setting switching instruction to each control target device 200 at the transmission timing determined by the preparation start timing determination unit 303. As shown in FIG. 5, when the control time of the control target device 200-1 is t １ +u １ and the preparation time of the control target device 200-2 is t ２ +u ２ When this is the case, the path setting control unit 304 transmits a path setting switching instruction to the control target device 200-2 (step S104-2), and ２ +u ２ )-(t １ +u １ ) and then transmits a path setting switching instruction to the control target device 200-1 (step S104-1). When the control target device 200-1 and the control target device 200-2 each receive the path setting switching instruction, they start preparations for switching the communication data path (step S105). Thereafter, the control target device 200-1 and the control target device 200-2 take a predetermined time to complete switching of the communication data path.

[0040] Similarly, when three or more control-target devices 200 are specified as destinations of the path setting switching instruction, the time between the timings of transmitting the path setting switching instruction to two control-target devices 200 is set to the difference in control times of the two control-target devices 200, and the timing of transmitting the path setting switching instruction is set so that the path setting switching instruction is transmitted first to the control-target device 200 with the longer control time. In other words, the timing of transmitting the path setting switching instruction to the control-target devices 200 is set to a time delayed from the timing of transmitting the path setting switching instruction to the control-target device 200 with the longest control time by the difference between the longest control time of the specified control-target devices 200 and the control time of the control-target device 200 that is the transmission destination.

[0041] Compared to the control device 300 according to the first embodiment, the control device 300 according to the second embodiment determines the timing to transmit a path setting switching instruction by taking into consideration not only the preparation time of the control-target device 200 but also the propagation time of the path setting switching instruction to be transmitted to the control-target device 200. This makes it possible to ideally synchronize the times at which the control-target devices 200 that transmitted the path setting switching instruction start switching, thereby further shortening the time during which communication data cannot be transmitted or received between the terminals 100.

[0042] In the above description, in the second embodiment, the control target device information storage unit 302 stores the control time of each control target device 200, but it is sufficient if the control target device information storage unit 302 stores the preparation time of each control target device 200 and the propagation time of the path setting switching instruction transmitted from the control device 300 to each control target device 200. In this case, the preparation start timing determination unit 303 reads out the preparation time of the specified control target device 200 and the propagation time of the path setting switching instruction transmitted from the control device 300 to the specified control target device 200 from the control target device information storage unit 302, and calculates the sum of the read times, thereby obtaining the control time of the specified control target device 200.

[0043] (Third Embodiment) A third embodiment will be described below. In the third embodiment, the timing of transmitting a path setting switching instruction to the control-target device 200 is determined based on the time from when the control device 300 transmits a path setting switching instruction to the control-target device 200 to when it receives a switching start notification from the control-target device 200. Hereinafter, the time from when the control device 300 transmits a path setting switching instruction to the control-target device 200 to when it receives a switching start notification from the control-target device 200 will be referred to as the "instruction response time."

[0044] 7 is a diagram showing the configuration of a control device 300 according to the third embodiment. The control device 300 according to the third embodiment includes a time measurement unit 305 in addition to the components of the control device 300 according to the first embodiment. The control device 300 according to the third embodiment measures the instruction response time of the control target device 200 before operating control over the control target device 200. In the third embodiment, a path setting control unit 304 controls path setting by transmitting a path setting switching instruction to the control target device 200, which is the target for measuring the instruction response time.

[0045] In the third embodiment, when the control target device 200 receives a path setting switching instruction, the control target device 200 prepares to switch the communication data path and switches the communication data path. When the control target device 200 has completed preparation for switching the communication data path and starts switching the communication data path, the control target device 200 transmits a switching start notification to the control device 300.

[0046] In the third embodiment, the path setting control unit 304 receives a switching start notification from the control target device 200. The time measurement unit 305 calculates the time from when the path setting control unit 304 transmits a path setting switching instruction to the control target device 200 until when the path setting control unit 304 receives the switching start notification as the “instruction response time” of the control target device 200.

[0047] In the third embodiment, the control target device information acquisition unit 301 acquires the instruction response time of each control target device 200 from the time measurement unit 305. In the third embodiment, the control target device information storage unit 302 stores the instruction response time of each control target device 200 acquired by the control target device information acquisition unit 301. In this way, the instruction response time of each control target device 200 can be acquired in advance.

[0048] The process of specifying the control-target device 200 to which a path setting switching instruction is to be sent and sending the path setting switching instruction to the specified control-target device 200 is the same as in the first and second embodiments, except that the control device 300 uses the instruction response time. In the third embodiment, the preparation start timing determination unit 303 determines the timing of sending the path setting switching instruction to the control-target device 200 based on the control-target device 200 to which the path setting switching instruction is to be sent and the instruction response time of the control-target device 200. The control-target device 200 to which the path setting switching instruction is to be sent is specified by notification from a higher-level device or by input operation by an operator. The preparation start timing determination unit 303, for example, reads the instruction response time of the specified control-target device 200 from the control-target device information storage unit 302, and determines the timing of sending the path setting switching instruction to the control-target device 200 based on the read instruction response time.

[0049] In the third embodiment, the preparation start timing determination unit 303 sets the time between the timing of transmitting a path setting switching instruction to one control-target device 200 and the timing of transmitting a path setting switching instruction to the other control-target device 200 to the difference in instruction response time of the two control-target devices 200 that transmit the path setting switching instruction. Furthermore, the preparation start timing determination unit 303 sets the timing of transmitting the path setting switching instruction so that the path setting switching instruction is transmitted first to the control-target device 200 that has the longer instruction response time.

[0050] The path setting control unit 304 controls the path setting by transmitting a path setting switching instruction to the specified control target device 200 at the transmission timing determined by the preparation start timing determination unit 303 .

[0051] FIG. 8 is a flowchart showing an example of the operation of the control system according to the third embodiment. The path setting control unit 304 controls path setting by transmitting a path setting switching instruction to the control-target devices 200-1 and 200-2 (step S201). The control device 300 may transmit the path setting switching instructions simultaneously or at any timing. Upon receiving the path setting switching instruction, the control-target device 200-1 begins preparations for switching the communication data path (step S202-1), and upon completion of the preparations, initiates the path setting switching (step S203-1). The control-target device 200-1 transmits a switching start notification to the control device 300 at the timing of initiating the path setting switching. Similarly, upon receiving the path setting switching instruction, the control-target device 200-2 begins preparations for switching the communication data path (step S202-2), and upon completion of the preparations, initiates the path setting switching (step S203-2). The control-target device 200-2 transmits a switching start notification to the control device 300 at the timing of initiating the path setting switching.

[0052] The time measurement unit 305 calculates the instruction response time of each of the control-target devices 200-1 and 200-2 as the time from when the path setting switch instruction is transmitted in step S201 until when the switching start notification transmitted in steps S203-1 and 203-2 is received (step S204). The control-target device information acquisition unit 301 of the control device 300 acquires information on the instruction response times of the control-target devices 200-1 and 200-2 from the time measurement unit 305 (step S205). The acquired information is stored in the control-target device information storage unit 302 (step S206). The preparation start timing determination unit 303 determines the timing for transmitting a path setting switch instruction to each of the control-target devices 200 based on the instruction response times of each of the control-target devices 200 stored in the control-target device information storage unit 302 (step S207). As a result, the time difference between the transmission timings when the control device 300 transmits path setting switch instructions to the two control-target devices 200 is determined.

[0053] When controlling the path setting of the control target device 200, the path setting control unit 304 transmits a path setting switching instruction to the control target devices 200-1 and 200-2 at the transmission timing determined by the preparation start timing determination unit 303 (steps S208-1 and S208-2). When the control target device 200-1 and the control target device 200-2 each receive the path setting switching instruction, they start preparation for switching the communication data path (step S209). Thereafter, the control target device 200-1 and the control target device 200-2 complete switching of the communication data path after a predetermined time.

[0054] As described above, the control device 300 according to the third embodiment can shorten the time during which communication data cannot be sent or received between terminals 100 by acquiring the instruction response time, even if it is not possible to acquire information on the preparation time or switching time for each controlled device 200 through notification from a higher-level device or input operation by an operator.

[0055] The instruction response time is the sum of the preparation time of the control-target device 200, the propagation time of the path setting switching instruction transmitted from the control device 300 to the control-target device 200, and the propagation time of the switching start notification transmitted from the control-target device 200 to the control device 300. Therefore, compared to the control time in the second embodiment, the instruction response time is longer than the control time by the propagation time of the switching start notification transmitted from the control-target device 200 to the control device 300. Therefore, compared to the second embodiment, there is a possibility that a deviation in transmission timing will occur.

[0056] To solve this problem, in the third embodiment, the control device 300 may measure the RTT (Round Trip Time) between the control device 300 and each control target device 200, and subtract half of the measured RTT from the instruction response time. As a result, the propagation time of the switching start notification transmitted from the control target device 200 to the control device 300 is cancelled out from the instruction response time, making it the same length as the control time. As a result, the control device 300 in the third embodiment can further shorten the time during which communication data cannot be transmitted or received between the terminals 100.

[0057] When the control target device information acquisition unit 301 acquires an instruction response time of a control target device 200 whose instruction response time is stored in the control target device information storage unit 302, the control target device information acquisition unit 301 may replace the acquired instruction response time with the instruction response time stored in the control target device information storage unit 302. Furthermore, when the control target device information acquisition unit 301 acquires an instruction response time of a control target device 200 whose instruction response time is stored in the control target device information storage unit 302, the control target device information acquisition unit 301 may store the acquired instruction response time in the control target device information storage unit 302, and may store multiple instruction response times for one control target device 200.

[0058] When the control target device information storage unit 302 stores multiple instruction response times for one control target device 200, the preparation start timing determination unit 303 may read out the multiple instruction response times of the control target device 200, perform statistical processing on the multiple instruction response times, and calculate the instruction response time to be used in determining the transmission timing. The statistical processing is, for example, processing to calculate the average or median of the multiple instruction response times.

[0059] The instruction response time may be acquired and stored at a finer granularity, for example, the instruction response time may be acquired and stored for each connection port that is switched in each control-target device 200.

[0060] Other Embodiments In the first embodiment as well, when the control target device information acquisition unit 301 acquires the preparation time of a control target device 200 whose preparation time is stored in the control target device information storage unit 302, the control target device information acquisition unit 301 may replace the acquired preparation time with the preparation time stored in the control target device information storage unit 302. Furthermore, when the control target device information acquisition unit 301 acquires the preparation time of a control target device 200 whose preparation time is stored in the control target device information storage unit 302, the control target device information acquisition unit 301 may store the acquired preparation time in the control target device information storage unit 302, and may store multiple preparation times for one control target device 200.

[0061] In the first embodiment, when the control target device information storage unit 302 stores multiple preparation times for one control target device 200, the preparation start timing determination unit 303 may read out the multiple preparation times for the control target device 200, perform statistical processing on the multiple preparation times, and calculate the preparation time to be used in determining the transmission timing. The statistical processing is, for example, processing to calculate the average or median of the multiple preparation times.

[0062] Also in the second embodiment, when the control target device information acquisition unit 301 acquires the preparation time of a control target device 200 whose preparation time or control time is stored in the control target device information storage unit 302, the control target device information acquisition unit 301 may replace the acquired preparation time or control time with the preparation time or control time stored in the control target device information storage unit 302. Furthermore, when the control target device information acquisition unit 301 acquires the preparation time or control time of a control target device 200 whose preparation time or control time is stored in the control target device information storage unit 302, the control target device information acquisition unit 301 may store the acquired preparation time or control time in the control target device information storage unit 302, and may store multiple preparation times or control times for one control target device 200.

[0063] In the second embodiment, when the control target device information storage unit 302 stores multiple preparation times or control times for one control target device 200, the preparation start timing determination unit 303 may read out the multiple preparation times or control times for the control target device 200, perform statistical processing on the multiple preparation times or control times, and calculate the preparation time or control time to be used in determining the transmission timing. The statistical processing is, for example, processing to calculate the average value or median value of the multiple preparation times or control times.

[0064] In the first and second embodiments, the preparation time or control time of each control target device 200 is notified from a higher-level device or input by an operator through an input operation, and is acquired by the control target device information acquisition unit 301, but this is not limited to this. For example, the control target device 200 may transmit its own information to the control device 300, and the control target device information acquisition unit 301 may acquire the information of the control target device 200 from each control target device 200.

[0065] For example, the control target device 200 transmits its own information to the control device 300 when newly connecting to the control device 300. The control target device 200 transmits its own information to the control device 300 when updating firmware, for example. The control target device 200 transmits its own information to the control device 300 periodically, for example. For example, the control device 300 transmits an information inquiry to the control target device 200, and upon receiving the information inquiry, the control target device 200 transmits its own information to the control device 300.

[0066] In the above description, the control device 300 controls the timing at which each control-target device 200 starts preparing for path setting switching by varying the timing at which the path setting switching instruction is transmitted for each control-target device 200, but this is not limited to this. Furthermore, the control-target device 200 prepares for switching the communication data path and switches the communication data path immediately upon receiving the path setting switching instruction from the control device 300, but this is not limited to this. The preparation start timing determination unit 303 of the control device 300 may determine the timing at which the control-target device 200 starts preparing for path switching based on the control-target device 200 that transmits the path setting switching instruction and the preparation time, control time, or instruction response time of the control-target device 200. In this case, the preparation start timing determination unit 303 adds information about the timing at which preparation for path switching starts to the path setting switching instruction transmitted to each control-target device 200.

[0067] At this time, the path setting control unit 304 simultaneously transmits a path setting switching instruction to each of the control-target devices 200. The control-target devices 200 start preparations for switching the path setting and switch the communication data path at the timing to start preparations for path switching indicated by the received path setting switching instruction.

[0068] 9 is a flowchart showing a modified example of the operation of the control system in the first embodiment. First, the inter-device delay time acquisition unit 301 of the control device 300 acquires information on the preparation time of each control target device 200 (step S301). The acquired information is stored in the inter-device delay time storage unit 302 (step S302). The preparation start timing determination unit 303 determines the timing at which each control target device 200 starts preparing for path switching based on the preparation time of each control target device 200 stored in the inter-device delay time storage unit 302 (step S303).

[0069] When controlling the path setting of the control target devices 200, the path setting control unit 304 simultaneously transmits a path setting switching instruction to each of the control target devices 200 (step S304). After that, when the control target devices 200-1 and 200-2 receive the path setting switching instruction, they start preparing for path setting switching at the timing to start preparation for path switching indicated by the path setting switching instruction (steps S305-1 and S305-2). When the preparation time of the control target device 200-1 is t １ and the preparation time of the control target device 200-2 is t ２ When this is the case, the control target device 200-2 is (t ２ -t １ ) earlier, the system starts preparing to switch the route settings.

[0070] By the above procedure, the control device 300 can start switching the path setting at a timing close to that of the control target device 200, thereby shortening the time during which communication data cannot be sent or received between the terminals 100.

[0071] In the third embodiment, the control target device 200 transmits a switching start notification to the control device 300, but this is not limited to this. For example, the control target device 200 may transmit a setting completion notification to the control device 300 at the timing when switching of the communication data path is completed. The time from when the control device 300 transmits a path setting switching instruction to the control target device 200 to when it receives a setting completion notification from the control target device 200 is defined as the "setting completion response time."

[0072] In this case, the control device 300 may use the setting completion response time instead of the instruction response time to determine the timing of transmitting a path setting switching instruction to the control-target device 200. In this case, the control device 300 will experience a difference in the timing of transmitting a path setting switching instruction to each control-target device 200 by the difference in the switching time of the control-target device 200 compared to when the instruction response time is used, but the time during which communication data cannot be transmitted or received between the terminals 100 can be shortened compared to the conventional optical communication system.

[0073] In the above-described embodiments, some or all of the configurations of the control target device 200 and the control device 300 may be implemented by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" as used herein includes hardware such as an OS and peripheral devices. Furthermore, "computer-readable recording medium" refers to portable media such as floppy disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording medium" may also include media that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or telephone lines, or media that store programs for a fixed period of time, such as volatile memory within the computer system serving as the server or client. The program may be designed to implement some of the above-described functions, or may be capable of implementing the above-described functions in combination with programs already stored in the computer system, or may be implemented using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0074] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the present invention that do not deviate from the gist of the present invention.

[0075] 100 Terminal, 200 Control target device, 300 Control device, 301 Control target device information acquisition unit, 302 Control target device information storage unit, 303 Preparation start timing determination unit, 304 Path setting control unit, 305 Time measurement unit

Claims

1. A control device that transmits an instruction to switch route settings to a controlled device that transfers communication data between terminals, the control device comprising: a preparation start timing determination unit that determines the timing at which the controlled device starts preparing for route setting based on the preparation time for the route setting in each of the controlled devices; and a route setting control unit that transmits a route setting switching instruction to the controlled device so that the controlled device starts preparing for route setting at the timing.

2. The control device described in claim 1, wherein the preparation start timing determination unit determines the timing for sending a route setting switching instruction based on the route setting preparation time in each of the control target devices, and the route setting control unit transmits the route setting switching instruction to the control target devices at the determined timing.

3. The control device according to claim 1, wherein the preparation start timing determination unit adds information on the timing to start preparation for route switching to the route setting switching instruction based on the preparation time for the route setting in each of the control target devices.

4. The control device according to claim 1, wherein the preparation start timing determination unit determines the timing at which the control target device starts preparation for path setting based on the propagation time of a path setting switch instruction between the control target device and the control target device.

5. The control device according to claim 1, wherein the preparation start timing determination unit determines the timing at which the controlled device starts preparing for path setting based on an instruction response time, which is the time from the timing at which a path setting switching instruction is sent to the controlled device to the timing at which a switching start notification is received from the controlled device.

6. A communication control system comprising a controlled device that transfers communication data between terminals, and a control device that transmits an instruction to switch route settings to the controlled device, wherein the control device comprises: a preparation start timing determination unit that adds information on the timing to start preparation for route switching to a route setting switch instruction, which is an instruction to switch route settings, based on the preparation time for the route setting in each of the controlled devices; and a route setting control unit that transmits the route setting switch instruction to the controlled device, wherein the controlled device begins preparation for route setting based on the timing indicated by the route setting switch instruction.

7. A communication control system comprising a controlled device that transfers communication data between terminals, and a control device that sends an instruction to switch route settings to the controlled device, wherein the control device comprises: a preparation start timing determination unit that determines the timing at which the controlled device will start preparing for route setting based on an instruction response time that is the time from the timing at which a route setting switch instruction is sent to the controlled device to the timing at which a switch start notification is received from the controlled device; and a route setting control unit that sends a route setting switch instruction to the controlled device so that the controlled device will start preparing for route setting at the timing, wherein the controlled device starts preparing for route setting based on the timing indicated by the route setting switch instruction, and sends a switch start notification to the control device at the timing at which switching will start.

8. A control method for transmitting an instruction to switch route settings to a controlled device that transfers communication data between terminals, the control method comprising: a preparation start timing determination step for determining the timing at which the controlled device starts preparing for route setting based on the preparation time for the route setting in each of the controlled devices; and a route setting control step for transmitting a route setting switching instruction to the controlled device so that the controlled device starts preparing for route setting at the timing.

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