Relay device

Abstract

A relay device (10) according to the present disclosure is provided with: a plurality of user connection ports (Pu) for connection to a time source (1) or a time reception device (2); a plurality of relay connection ports (Pr) for connection to other relay devices (10); an identification unit (131) that identifies user information included in a received time signal for time synchronization and indicating a device that performs time synchronization on the basis of the time signal; a database unit (132) that stores a port that has received the time signal and the identified user information in association with each other; and a determination unit (133) that determines a port for transferring the received time signal on the basis of the correspondence relationship between the port and the user information stored in the database unit (12).

Description

relay device

[0001] The present disclosure relates to a relay device.

[0002] A relay network consisting of multiple relay devices may be connected to a time source and a time receiving device that synchronizes with the time source, for a number of users. Hereinafter, the time source and the time receiving device that synchronizes with the time source may be collectively referred to as "user device." Generally, when a signal is input to a relay device, the relay device reads the header information of the input signal and separates it into a time signal for time synchronization and a main signal other than the time signal for separate processing. The time signal is, for example, a signal used in PTP (Precision Time Protocol), which is a protocol for time synchronization between devices on a network (see Non-Patent Document 1).

[0003] For main signals, the relay device has the function of distributing and routing the main signal for each user. However, this function does not apply to time signals, so each user must specify the port to use and manually set the route from the time source to the time receiving device.

[0004] IEEE Std 1588TM-2019 “IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems”

[0005] In manual route configuration, the more user devices are installed, and the more relay devices are connected between the time source and the time receiving device, the more work and effort is required for configuration.In addition, there is a possibility of configuration errors due to human error.

[0006] The purpose of the present disclosure, made in consideration of the above-mentioned problems, is to provide a relay device that can more easily set a route for transferring a time signal between a time source and a time receiving device.

[0007] In order to solve the above problem, the relay device of the present disclosure is a relay device that forms a relay network consisting of a plurality of relay devices and relays signals between a time source connected to the relay network and a time receiving device that is time synchronized with the time source, and is equipped with a plurality of user connection ports connected to the time source or the time receiving device, a plurality of relay connection ports connected to other relay devices, an identification unit that identifies user information contained in a received time signal for time synchronization and indicating a device that is time synchronized by the time signal, a database unit that stores the port that received the time signal in correspondence with the identified user information, and a determination unit that determines a port to forward the received time signal based on the correspondence between the port and the user information stored in the database unit.

[0008] According to the relay device of the present disclosure, it is possible to more easily set a route for transferring a time signal between a time source and a time receiving device.

[0009] 1 is a diagram illustrating an example of a configuration of a relay device according to an embodiment of the present disclosure. FIG. 1 is a flowchart illustrating an example of operation of the relay device illustrated in FIG. 1. FIG. 2 is a diagram illustrating an example of transmission and reception of a time signal between a time source and a time receiving device. FIG. 3 is a diagram illustrating an operation of the relay device according to the present disclosure when a Sync signal is transmitted from the time source 1a illustrated in FIG. 3 to the time receiving device 2a. FIG. 4 is a diagram illustrating an operation of the relay device according to the present disclosure when a Req signal is transmitted from the time receiving device 2a illustrated in FIG. 3 to the time source 1a. FIG. 5 is a diagram illustrating an operation of the relay device according to the present disclosure when a Sync signal is transmitted from the time source 1b illustrated in FIG. 3 to the time receiving device 2b. FIG. 5 is a diagram illustrating an operation of the relay device according to the present disclosure when a Req signal is transmitted from the time receiving device 2b illustrated in FIG. 3 to the time source 1b. FIG. 6 is a diagram illustrating an operation of the relay device according to the present disclosure when a Sync signal is transmitted from the time source 1c illustrated in FIG. 3 to the time receiving device 2c. FIG. 7 is a diagram illustrating an operation of the relay device according to the present disclosure when a Req signal is transmitted from the time receiving device 2c illustrated in FIG. 3 to the time source 1c. FIG. 8 is a diagram illustrating an example of a configuration of a computer functioning as a relay device according to the present disclosure.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] FIG. 1 is a diagram illustrating an example configuration of a relay device 10 according to an embodiment of the present disclosure. The relay devices 10 according to the present disclosure form a relay network made up of a plurality of relay devices 10. A time source 1 and a time receiving device 2 that is time-synchronized with the time source 1, not shown in FIG. 1 , are connected to the relay network for a plurality of users. Users who use the time source 1 and the time receiving device 2 are, for example, mobile phone carriers. The relay device 10 relays signals between the time source 1 and the time receiving device 2.

[0012] As shown in FIG. 1, the relay device 10 according to this embodiment includes a plurality of user connection ports Pu (six user connection ports Pu1-Pu6 in the example shown in FIG. 1), a plurality of relay connection ports Pr (two relay connection ports Pr1 and Pr2 in the example shown in FIG. 1), a signal separation unit 11, a main signal processing unit 12, and a time signal processing unit 13.

[0013] The user connection port Pu is a port to which the time source 1 or the time receiving device 2 (user device) is connected. The relay connection port Pr is a port to which another relay device 10 is connected. Hereinafter, when there is no need to distinguish between the user connection port Pu and the relay connection port Pr, they may be simply referred to as "ports." Which of the ports provided in the relay device 10 is to be used as the user connection port Pu and which port is to be used as the relay connection port Pr is set in advance. This setting may be made, for example, by an administrator before connecting a user device, or may be made during the manufacturing stage of the relay device 10.

[0014] Based on the header information of a signal received via a port, the signal separator 11 separates the signal into a time signal for time synchronization between the time source 1 and the time receiving device 2, and a main signal other than the time signal. The signal separator 11 outputs the main signal to the main signal processor 12, and outputs the time signal to the time signal processor 13.

[0015] The main signal processing unit 12 transfers the main signal output from the signal separation unit 11. Routing of the main signal has been conventionally performed and is not directly related to the present disclosure, so detailed description thereof will be omitted.

[0016] The time signal processing unit 13 transfers the time signal output from the signal separation unit 11. As shown in FIG.

[0017] The identification unit 131 identifies user information that is included in the time signal (received time signal) output from the signal separation unit 11 and indicates a device (user device) that will be time-synchronized using the time signal. Specifically, the identification unit 131 identifies user information that indicates a user device that will be time-synchronized using the time signal based on header information of the time signal. For example, the identification unit 131 reads a domain number that is included in the header of the time signal and indicates a group of devices that will be time-synchronized, and identifies the user information.

[0018] The database unit 132 stores the port that received the time signal in association with the user information that is included in the time signal and that is identified by the identification unit 131 .

[0019] The determining unit 133 determines a port to which the received time signal should be transferred based on the correspondence between ports and user information stored in the database unit 132, and transfers the time signal from the determined port.

[0020] Next, the operation of the relay device 10 according to this embodiment will be described. Fig. 2 is a flowchart showing an example of the operation of the relay device 10 according to this embodiment, and is a diagram for explaining a relay method executed by the relay device 10 according to this embodiment.

[0021] The identification unit 131 identifies user information contained in the received time signal, which indicates a device (user device) that will be time-synchronized by the time signal (step S11).

[0022] The database unit 132 stores the port that received the time signal in association with the user information identified by the identification unit 131 (step S12).

[0023] The determination unit 133 determines the port to which the received time signal is to be transferred based on the stored correspondence between the port and the user information (step S13).

[0024] Next, the operation of the relay device 10 according to this embodiment will be described in more detail using a specific example. The following description will be given using an example in which three relay devices 10 (relay devices 10A, 10B, and 10C) connected in series form a relay network, as shown in FIG. 3, and time sources 1a to 1c and time receiving devices 2a to 2c are connected to the relay network. Specifically, the time source 1a, the time receiving device 2b, and the time source 1c are connected to the relay device 10A, the time receiving device 2c is connected to the relay device 10B, and the time receiving device 2a and the time source 1b are connected to the relay device 10C. In the following description, it is assumed that, according to the PTP protocol, the time source 1a and the time receiving device 2a used by user a are time-synchronized, the time source 1b and the time receiving device 2b used by user b are time-synchronized, and the time source 1c and the time receiving device 2c used by user c are time-synchronized.

[0025] In the following, we will explain an example in which time source 1a, time receiving device 2a, and time receiving device 2c are connected to a relay network, then time source 1b and time receiving device 2b are connected to a relay network, and then time source 1c is connected to the relay network.

[0026] When the time source 1a and the time reception device 2a are to be time-synchronized, the time source 1a transmits a Sync signal (first time signal). The Sync signal is relayed in this order by relay device 10A, relay device 10B, and relay device 10C, and is received by the time reception device 2a. When the time reception device 2a receives the Sync signal, it transmits a Req signal (second time signal). The Req signal is relayed in this order by relay device 10C, relay device 10B, and relay device 10A, and is received by the time source 1a. When the time source 1a receives the Req signal, it transmits a Resp signal (third time signal). The Resp signal is relayed in this order by relay device 10A, relay device 10B, and relay device 10C, and is received by the time reception device 2a. By transmitting and receiving the time signals as described above, the time source 1a and the time reception device 2a can be time-synchronized. Time synchronization is also possible between the time source 1b and the time receiving device 2b, and between the time source 1c and the time receiving device 2c by transmitting and receiving a similar time signal. The operation of the relay devices 10A-10C when a time signal is received will be described below with reference to Figures 4 to 9.

[0027] First, the operation of the relay devices 10A-10C when a Sync signal is transmitted from the time source 1a to the time receiving device 2a will be described with reference to Fig. 4. In the following, in order to separately describe the operation of the relay devices 10A-10C, the symbols "A"-[C] are added to the end of the configuration of each of the relay devices 10A-10C.

[0028] 4, the time source 1a is connected to the user connection port Pu1A of the relay device 10A, the time receiving device 2c is connected to the user connection port Pu4B of the relay device 10B, and the time receiving device 2a is connected to the user connection port Pu4C of the relay device 10C. The relay devices 10A and 10B are connected via the relay connection ports Pr2A and Pr1B, and the relay devices 10B and 10C are connected via the relay connection ports Pr2B and Pr1C. In FIGS. 4 to 9, of the ports of the relay device 10, ports connected to user devices (the time source 1 and the time receiving device 2) or other relay devices 10 (linked-up ports) are indicated by solid lines, and ports not connected to user devices or other relay devices (linked-down ports) are indicated by dotted lines.

[0029] The relay device 10 receives a Sync signal via the user connection port Pu or the relay connection port Pr. The identification unit 131 identifies the user information included in the received Sync signal, associates the port that received the Sync signal with the user information, and stores the association in the database unit 132.

[0030] The determination unit 133 determines the port to which the received Sync signal should be forwarded based on the correspondence between ports and user information stored in the database unit 132. Specifically, the determination unit 133 determines the port to which the Sync signal should be forwarded in accordance with the following conditions (1) to (3): (1) The Sync signal is not forwarded from a linked-down port. (2) The Sync signal is time-forwarded from a linked-up relay connection port Pr. (3) The Sync signal is forwarded from, among the linked-up user connection ports Pu, a user connection port Pu for which user information is not stored in association with the database unit 132, and a user connection port Pu that has received a time signal containing user information identical to the user information contained in the time signal.

[0031] That is, under condition (3), when the determination unit 133 receives a time signal, it determines, among the multiple user connection ports Pu, a port other than the port that received the time signal containing user information different from the user information contained in the time signal as the port to which the time signal will be transferred.

[0032] The operation of each of the relay devices 10A to 10C will be described in more detail using the example shown in Fig. 4. First, the operation of the relay device 10A will be described.

[0033] The relay device 10A receives a Sync signal transmitted from the time source 1a via the user connection port Pu1A. The identification unit 131A identifies the user information contained in the received Sync signal and stores the port that received the Sync signal and the user information in the database unit 132A. Specifically, the identification unit 131A stores in the database unit 132A the fact that "the Sync signal from the time source 1a was received at the user connection port Pu1A," that is, the fact that "the time source 1a is connected to the user connection port Pu1A."

[0034] The determination unit 133A determines the port to which the received Sync signal should be forwarded. Due to condition (1), the determination unit 133A does not forward the Sync signal from the linked-down relay connection port Pr1A and the user connection ports Pu2A-Pu6A. Because the relay connection port Pr2A is linked-up, the determination unit 133A forwards the Sync signal from the relay connection port Pr2A due to condition (2).

[0035] Next, the operation of the relay device 10B will be described. The relay device 10B receives the Sync signal transmitted from the relay device 10A via the relay connection port Pr1B. The identification unit 131B identifies the user information contained in the received Sync signal and stores the port that received the Sync signal and the user information in the database unit 132B. Specifically, the identification unit 131B stores in the database unit 132B that "the Sync signal from the time source 1a was received at the intermediate connection port Pr1B."

[0036] The determination unit 133B determines the port to which the received Sync signal should be forwarded. Under condition (1), the determination unit 133B does not forward the Sync signal from the user connection ports Pu1B-Pu3B and Pu5B-Pu6B, which are linked down. Because the relay connection port Pr2B is linked up, the determination unit 133B forwards the Sync signal from the relay connection port Pr2B under condition (2). Furthermore, because no user information associated with the user connection port Pu4B is stored in the database unit 132B, the determination unit 133B forwards the Sync signal from the user connection port Pu4B under condition (3).

[0037] The Sync signal transmitted from user connection port Pu4B is received by time receiving device 2c. Since the user information included in the received Sync signal differs from its own user information, time receiving device 2c discards the received Sync signal.

[0038] Next, the operation of the relay device 10C will be described. The relay device 10C receives the Sync signal transmitted from the relay device 10B via the relay connection port Pr1C. The identification unit 131C identifies the user information contained in the received Sync signal and stores the port that received the Sync signal and the user information in the database unit 132C. Specifically, the identification unit 131C stores in the database unit 132C that "the Sync signal from the time source 1a was received at the intermediate connection port Pr1C."

[0039] The determination unit 133C determines the port to which the received Sync signal should be forwarded. According to condition (1), the determination unit 133C does not forward the Sync signal from the linked-down relay connection port Pr2C and the user connection ports Pu1C-Pu3C and Pu5C-Pu6C. Furthermore, since no user information is stored in the database unit 132C in association with the linked-up user connection port Pu4C, the determination unit 133C forwards the Sync signal from the user connection port Pu4C according to condition (3). The Sync signal transmitted from the user connection port Pu4C is received by the time receiving device 2a. Since the user information included in the received Sync signal is identical to its own user information, the time receiving device 2a transmits a Req signal.

[0040] Next, the operation of the relay devices 10A to 10C when the time receiving device 2a transmits a Req signal to the time source 1a will be described with reference to FIG.

[0041] The relay device 10 receives the Req signal via the user connection port Pu or the relay connection port Pr. The identification unit 131 identifies the user information included in the received Req signal, associates the Req signal with the user information, and stores the association between the Req signal and the user information in the database unit 132.

[0042] The determination unit 133 determines a port to which the received Req signal should be transferred, based on the correspondence between ports and user information stored in the database unit 132. Specifically, the determination unit 133 determines a port to which the Req signal should be transferred, in accordance with the following conditions (4) to (6): (4) The Req signal is not transferred to a linked-down port. (5) The Req signal is transferred from a linked-up relay connection port Pr, and the database unit 132 stores therein that a Sync signal containing the same user information as the user information contained in the Req signal has been received. (6) The Req signal is transferred from a linked-up user connection port Pu, and the database unit 132 stores therein that a time source 2a containing the same user information as the user information contained in the Req signal is connected.

[0043] That is, under conditions (4) and (5), when the determination unit 133 receives a Req signal (second time signal) transmitted from the time receiving device 2 in response to the reception of a Sync signal (first time signal) transmitted from the time source 1, it determines the port that received the Sync signal containing the same user information as the user information contained in the Req signal as the port to transfer the Req signal. By doing so, only time signals containing the user information associated with the port stored in the database unit 132 are transferred. This makes it possible to prevent unnecessary traffic from flowing.

[0044] The operation of each of the relay devices 10A to 10C when receiving the Req signal will be described in more detail below. First, the operation of the relay device 10C will be described.

[0045] The relay device 10C receives the Req signal transmitted from the time reception device 2b via the user connection port Pu4C. The identification unit 131C identifies the user information contained in the received Req signal and stores the user information in the database unit 132C in association with the port that received the Req signal. Specifically, the identification unit 131C stores in the database unit 132C the fact that "the Req signal from the time reception device 2a was received at the user connection port Pu4C," that is, the fact that "the time reception device 2a is connected to the user connection port Pu4C."

[0046] The decision unit 133C decides the port P to which the received Req signal is to be forwarded. According to condition (4), the decision unit 133C does not forward the Req signal from the linked-down relay connection port Pr2C and the user connection ports Pu1C-Pu3C and Pu5C-Pu6C. The relay connection port Pr1C is linked-up. Furthermore, since the time source 1a and the time receiving device 2a are used by the same user a, the user information included in the Sync signal sent from the time source 1a is the same as the user information included in the Req signal sent from the time receiving device 2a. As described above, the database unit 132C stores the fact that "the Sync signal from the time source 1a was received at the intermediate connection port Pr1C." Therefore, according to condition (5), the decision unit 133C forwards the Req signal from the relay connection port Pr1C.

[0047] Next, the operation of the relay device 10B will be described. The relay device 10B receives the Req signal transmitted from the relay device 10C via the relay connection port Pr2B. The identification unit 131B identifies the user information included in the received Req signal and stores the port through which the Req signal was received and the user information in the database unit 132B. Specifically, the identification unit 131B stores in the database unit 132B that "the Req signal from the time receiving device 2a was received at the relay connection port Pr2B."

[0048] The decision unit 133B determines the port to which the received Req signal should be forwarded. According to condition (4), the decision unit 133B does not forward the Req signal from the user connection ports Pu1B-Pu3B and Pu5B-Pu6B, which are linked down. The relay connection port Pr1B is linked up. Furthermore, as described above, the time source 1a and the time reception device 2a are used by the same user a, and therefore the user information contained in the time source 1a and the user information contained in the time reception device 2a are identical. As described above, the database unit 132B stores information that "a Sync signal from the time source 1a has been received at the intermediate connection port Pr1B." Therefore, according to condition (5), the decision unit 133B forwards the Req signal from the relay connection port Pr1B. Furthermore, although the user connection port Pu4B is linked up, the database unit 132B does not store information that the user connection port Pu4B has received a Sync signal containing the same user information as the user information contained in the Req signal. Therefore, due to the condition (6), the decision unit 133C does not transfer the Req signal from the user connection port Pu4B.

[0049] Next, the operation of the relay device 10A will be described. The relay device 10A receives a Req signal transmitted from the relay device 10B via the relay connection port Pr2A. The identification unit 131A identifies the user information contained in the received Req signal and stores the port that received the Req signal and the user information in the database unit 132A. Specifically, the identification unit 131A stores in the database unit 132A that "the Req signal from the time receiving device 2a was received at the intermediate connection port Pr2A."

[0050] The decision unit 133A decides the port to which the received Req signal should be forwarded. Condition (4) determines that the decision unit 133A will not forward the Req signal from the linked-down relay connection port Pr1A and the user connection ports Pu2A-Pu6A. Furthermore, since the user connection port Pu1A is linked-up and the database unit 132A stores information that the time source 1a is connected to the user connection port Pu1A, the decision unit 133A forwards the Req signal from the user connection port Pu1A in accordance with condition (6). Upon receiving the Req signal, the time source 1a transmits a Resp signal. The Req signal transmitted from the user connection port Pu1A is received by the time source 1a. Since the user information included in the received Req signal is identical to its own user information, the time source 1a transmits a Resp signal.

[0051] The operation of the relay device 10 when receiving a Resp signal is the same as the operation of the relay device 10 when receiving a Req signal, which was described with reference to Figure 5, and can be achieved by replacing the Req signal with the Resp signal and the Sync signal with the Req signal. That is, when the determination unit 133 receives a Resp signal (third time signal) transmitted from the time source 1a in response to receiving a Req signal (second time signal), it determines the port that received the Req signal containing the same user information as the user information contained in the Resp signal as the port to forward the Resp signal. This makes it possible to uniquely determine a route for the Resp signal as well as for the Req signal.

[0052] Fig. 6 is a diagram showing the operation of the relay device 10 when a Sync signal is transmitted from the time source 1b to the time receiving device 2b, and Fig. 7 is a diagram showing the operation of the relay device 10 when a Req signal is transmitted from the time source 1b to the time receiving device 2b.

[0053] The operation of the relay device 10 when relaying the Sync signal shown in Fig. 6 is generally similar to the operation of the relay device 10 when relaying the Sync signal, which was described with reference to Fig. 4. Furthermore, the operation of the relay device 10 when relaying the Req signal shown in Fig. 7 is generally similar to the operation of the relay device 10 when relaying the Req signal, which was described with reference to Fig. 5. Therefore, a detailed description will be omitted, and only the main differences will be described.

[0054] 6, when the determination unit 133C of the relay device 10C receives the Sync signal transmitted from the time source 1b, it transfers the Sync signal from the relay connection port Pr1C among the linked-up ports, but does not transfer the Sync signal from the user relay port Pu4C, because it has already been registered in the database unit 132C that the time receiving device 2a is connected to the user relay port Pu4C.

[0055] 6, when the determination unit 133A of the relay device 10A receives the Sync signal transmitted from the relay device 10B, it transfers the Sync signal from the user connection port Pu2A among the linked-up ports, but does not transfer the Sync signal from the user repeat port Pu1A, because it has already been registered in the database unit 132A that the time source 1a is connected to the user repeat port Pu1A.

[0056] Fig. 8 is a diagram showing the operation of the relay device 10 when a Sync signal is transmitted from the time source 1c to the time receiving device 2c, and Fig. 9 is a diagram showing the operation of the relay device 10 when a Req signal is transmitted from the time source 1c to the time receiving device 2c.

[0057] The operation of the relay device 10 when relaying the Sync signal shown in Fig. 8 is generally similar to the operation of the relay device 10 when relaying the Sync, which was described with reference to Fig. 4. Furthermore, the operation of the relay device 10 when relaying the Req signal shown in Fig. 9 is generally similar to the operation of the relay device 10 when relaying the Req signal, which was described with reference to Fig. 5. Therefore, a detailed description will be omitted, and only the main differences will be described.

[0058] 8, when the determination unit 133A of the relay device 10A receives the Sync signal transmitted from the time source 1c, it transfers the Sync signal from the relay connection port Pr2A among the linked-up ports, and does not transfer the Sync signal from the user relay ports Pu1A and Pu2A. This is because it has already been registered in the database unit 132A that the time source 1a is connected to the user relay port Pu1A and the time receiving device 2b is connected to the user relay port Pu2A.

[0059] Furthermore, as shown in FIG. 9, when the decision unit 133B of the relay device 10B receives a Req signal transmitted from the time receiving device 2c, it transfers the Req signal from relay connection port Pr1B among the linked-up ports, but does not transfer the Req signal from relay connection port Pr2B. According to condition (5), the decision unit 133B transfers the Req signal from a port for which the database unit 132B stores information indicating that a Sync signal containing the same user information as the user information contained in the Req signal has been received. As is clear from FIG. 8, only relay connection port Pr1B is stored in the database unit 132B as having received a Sync signal from the time source 1c. Therefore, the decision unit 133B transfers the Req signal from relay connection port Pr1B.

[0060] As described above, the relay device 10 according to this embodiment includes a plurality of user connection ports Pu connected to the time source 1 or the time receiving device 2, a plurality of relay connection ports Pr connected to other relay devices 10, an identification unit 131, a database unit 132, and a determination unit 133. The identification unit 131 identifies user information contained in the received time signal and indicating the device with which time synchronization is performed using the time signal. The database unit 132 stores the port that received the time signal in association with the identified user information. Based on the association between the port and the user information stored in the database unit 132, the port to which the received time signal should be forwarded is determined.

[0061] By storing the port that received the time signal in association with the user information contained in the time signal and determining the port to which the time signal is to be transferred based on the correspondence between the port and the user information, the relay device 10 can determine the route for transferring the time signal without manual intervention. Therefore, the relay device 10 according to this embodiment can more easily set the route for transferring the time signal between the time source 1 and the time receiving device 2.

[0062] The relay device 10 described above can be realized by a computer 20 shown in FIG. 10. A program for causing the computer 20 to function as the relay device 10 may be provided. The program may be stored in a storage medium or provided via a network. FIG. 10 is a block diagram showing a schematic configuration of the computer 20 functioning as the relay device 10. The computer 20 may be a general-purpose computer, a dedicated computer, a workstation, a PC (Personal Computer), an electronic notepad, or the like. The program instructions may be program code, code segments, or the like for executing necessary tasks.

[0063] 10 , the computer 20 includes a processor 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, a storage 24, an input unit 25, and a communication interface (I / F) 27. Each component is communicably connected to one another via a bus 29. The processor 21 is specifically a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), a SoC (System on a Chip), or the like, and may be configured with multiple processors of the same or different types.

[0064] The processor 21 is a control unit that controls each component and performs various arithmetic processing. That is, the processor 21 reads a program from the ROM 22 or the storage 24 and executes the program using the RAM 23 as a work area. The processor 21 controls each component and performs various arithmetic processing in accordance with the program stored in the ROM 22 or the storage 24. In this embodiment, the ROM 22 or the storage 24 stores a program for operating the computer 20 as the relay device 10 according to the present disclosure. The processor 21 reads and executes the program, thereby realizing each component of the relay device 10.

[0065] The program may be provided in a form stored on a non-transitory storage medium such as a CD-ROM (Compact Disk Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), a USB (Universal Serial Bus) memory, etc. The program may also be provided in a form downloaded from an external device via a network.

[0066] The ROM 22 stores various programs and various data. The RAM 23 temporarily stores programs or data as a work area. The storage 24 is configured with an HDD (Hard Disk Drive) or SSD (Solid State Drive) and stores various programs including an operating system and various data. For example, the ROM 22 or the storage 24 constitutes a memory that stores the port that received the time signal and the user information included in the time signal in association with each other.

[0067] The input unit 25 includes a pointing device such as a mouse and a keyboard, and is used to input various types of information.

[0068] The communication interface 27 is an interface for communicating with other devices, for example, an interface for a LAN.

[0069] The following additional notes are provided regarding the above-described embodiments.

[0070] [Supplementary Item 1] A relay device that forms a relay network made up of a plurality of relay devices and relays signals between a time source connected to the relay network and a time receiving device that is time-synchronized with the time source, comprising: a plurality of user connection ports that connect to the time source or the time receiving device; a plurality of relay connection ports that connect to other relay devices; a processor; and a memory, wherein the processor is configured to: identify user information that is included in a received time signal for time synchronization and indicates a device that is time-synchronized with the time signal; associate the port that received the time signal with the identified user information and store it in the memory; and determine a port to forward the received time signal based on the correspondence between the port and the user information stored in the memory.

[0071] [Supplementary Item 2] In the relay device described in Supplementary Item 1, when the processor receives a second time signal transmitted from the time receiving device in response to receiving a first time signal transmitted from the time source, the processor determines the port that received the first time signal containing the same user information as the user information contained in the second time signal as the port to forward the second time signal.

[0072] [Supplementary Item 3] In the relay device described in Supplementary Item 2, when the processor unit receives a third time signal transmitted from the time source in response to receiving the second time signal, it determines the port that received the second time signal containing the same user information as the user information contained in the third time signal as the port to forward the third time signal.

[0073] [Supplementary Item 4] In the relay device described in Supplementary Item 1, when the processor receives the time signal, it determines, among the plurality of user connection ports, a port other than a port that received a time signal containing user information different from the user information contained in the time signal, as a port to which the time signal should be forwarded.

[0074] [Supplementary Item 5] A relay method executed by a relay device that forms a relay network made up of a plurality of relay devices and relays signals between a time source connected to the relay network and a time receiving device that synchronizes with the time source, wherein the relay device has: a plurality of user connection ports that connect to the time source or the time receiving device; a plurality of relay connection ports that connect to other relay devices; and a memory; the relay device identifies user information that is included in a received time signal for time synchronization and indicates a device that synchronizes with the time signal; associates the port that received the time signal with the identified user information and stores it in the memory; and determines a port to forward the received time signal based on the correspondence between the port and the user information stored in the memory.

[0075] [Supplementary Item 6] A program that causes a computer to operate as the relay device according to any one of Supplementary Items 1 to 4.

[0076] [Supplementary Item 7] A non-transitory storage medium storing a program executable by a computer, the non-transitory storage medium storing a program that causes the computer to operate as the relay device described in any one of Supplementary Items 1 to 4.

[0077] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present disclosure. Therefore, the present invention should not be interpreted as being limited by the above-described embodiments, and various modifications and alterations are possible without departing from the scope of the claims. For example, multiple building blocks shown in the block diagrams of the embodiments can be combined into one, or one building block can be divided.

[0078] REFERENCE SIGNS LIST 1 Time source 2 Time receiving device 10 Relay device 20 Computer 21 Processor 22 ROM 23 RAM 24 Storage 25 Input unit 27 Communication I / F 29 Bus 11 Signal separation unit 12 Main signal processing unit 13 Time signal processing unit 131 Identification unit 132 Database unit 133 Determination unit Pu User connection port Pr Relay connection port

Claims

1. A relay device that forms a relay network consisting of multiple relay devices and relays signals between a time source connected to the relay network and a time receiving device that synchronizes with the time source, the relay device comprising: multiple user connection ports that connect to the time source or the time receiving device; multiple relay connection ports that connect to other relay devices; an identification unit that identifies user information contained in a received time signal for time synchronization and that indicates a device that synchronizes with the time signal; a database unit that stores the port that received the time signal in association with the identified user information; and a determination unit that determines a port to forward the received time signal based on the correspondence between the port and the user information stored in the database unit.

2. A relay device according to claim 1, wherein the determination unit, upon receiving a second time signal transmitted from the time receiving device in response to receiving a first time signal transmitted from the time source, determines the port that received the first time signal containing the same user information as the user information contained in the second time signal as the port to forward the second time signal.

3. A relay device according to claim 2, wherein the determination unit, upon receiving a third time signal transmitted from the time source in response to receiving the second time signal, determines the port that received the second time signal containing the same user information as the user information contained in the third time signal as the port to forward the third time signal.

4. A relay device according to claim 1, wherein, upon receiving the time signal, the determination unit determines, among the plurality of user connection ports, a port other than the port that received a time signal containing user information different from the user information contained in the time signal, as the port to which the time signal should be forwarded.

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