Relay System

Abstract

This relay system (10) relays data to be transmitted to any one among a plurality of transmission destinations, the relay system comprising: a reception unit (11A) that receives the data; a conversion unit (11B) that converts the data received by the reception unit into an optical signal of a wavelength that differs depending on the transmission destination, to which the data is to be transmitted, among the plurality of transmission destinations; and an output unit (11C) that outputs the optical signal converted by the conversion unit to an optical transmission line (L2). The foregoing makes it possible to shorten the transmission time for all of the plurality of pieces of data of different transmission destinations.

Description

[Technical Field]

[0001] The present invention relates to a relay system. [Background technology]

[0002] As disclosed in Patent Document 1, optical communication networks (e.g., passive optical networks (PONs)) that transmit and receive data in the form of optical signals have been developed in recent years. In such optical communication networks, different data are transmitted by time division multiplexing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-198270 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when multiple data with different destinations are transmitted via an optical transmission path using time division multiplexing, the transmission time for all data (the time from the start of transmission to the end of transmission) is the sum of the transmission times for each data, which results in a long transmission time.

[0005] An object of the present invention is to shorten the overall transmission time of a plurality of pieces of data to different destinations. [Means for solving the problem]

[0006] In order to solve the above problem, the relay system of the present invention is a relay system that relays data to be transmitted to one of multiple destinations, and includes a receiving unit that receives the data, a converting unit that converts the data received by the receiving unit into an optical signal of a different wavelength depending on the destination among the multiple destinations to which the data is to be transmitted, and an output unit that outputs the optical signal converted by the converting unit to an optical transmission path. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the overall transmission time of a plurality of data sets having different destinations. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram of a relay system according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing the wavelengths of optical signals transmitted through the optical transmission lines of FIG. [Figure 3] FIG. 3 is a diagram showing an example of the configuration of a table included in the relay system of FIG. [Figure 4] FIG. 4 is a configuration diagram of a relay system according to the second embodiment. [Figure 5] FIG. 5 is a diagram showing an example of the configuration of a table included in the relay system of FIG. [Figure 6] FIG. 6 is a configuration diagram of a relay system according to the third embodiment. [Figure 7] FIG. 7 is a diagram showing an example of the configuration of a table in a normal state provided in the relay system of FIG. [Figure 8] FIG. 8 is a flowchart showing the operation when the contents of the table in FIG. 7 are changed. [Figure 9] FIG. 9 is a diagram showing an example of the structure of a table whose contents have been changed. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, elements having the same function, elements having different functions but corresponding to each other, etc. will be appropriately denoted by the same reference numerals. Also, in the drawings, for multiple elements having the same function or corresponding to each other, only some of the elements may be denoted by the same reference numerals. In the following, "wavelength" refers to not only a single wavelength, but also a wavelength band and a wavelength group which is a collection of multiple discrete wavelengths. When the wavelength is a wavelength band, different wavelengths mean that the wavelength bands do not overlap. When the wavelength is a wavelength group, different wavelengths mean that all of the wavelengths constituting the wavelength group are different from each other.

[0010] [First embodiment] 1, a relay system 10 according to the first embodiment of the present invention includes a conversion device 11 and a distribution device 12. The relay system 10 is configured to relay data transmitted from a plurality of clients C1 to Cn to any one of a first server S1 to a fourth server S4 as a plurality of destinations.

[0011] The clients C1 to Cn are composed of various client computers, etc. The first server S1 to the fourth server S4 are each a server computer that provides processing (services) for data from the clients C1 to Cn, respectively. In the following description, the clients C1 to Cn are collectively referred to as clients C, and the first server S1 to the fourth server S4 are collectively referred to as servers S.

[0012] The conversion device 11 is composed of various computers and the like, and is configured to convert data from a client C into an optical signal with a wavelength corresponding to the server S to which the data is to be sent. The conversion device 11 includes a receiving unit 11A, a converting unit 11B, and an output unit 11C. The receiving unit 11A includes a communication module and the like. The conversion unit 11B includes, for example, a control circuit and a conversion module that converts data into an optical signal with a desired wavelength under the control of the control circuit. The control circuit includes at least one or a combination of two or more of various integrated circuits, such as a processor such as a CPU (Central Processing Unit) that executes a program, an ASIC (Application Specific Integrated Circuit), and an FPGA (Field-Programmable Gate Array). The conversion unit 11B includes a table T (described below) and a storage unit that stores the program and the like. The output unit 11C includes an optical terminal and the like for outputting an optical signal to the outside.

[0013] The receiver 11A is connected to the client C via an optical transmission path L1, such as an optical fiber. The client C outputs, in the form of an optical signal, data to be processed by one of the servers S and destination information, which is attached to the data and specifies the server S to which the data is to be sent. The receiver 11A receives the data to be processed and the destination information output by the client C in the form of an optical signal via the optical transmission path L1. The wavelength of the optical signal may be any wavelength λ, as shown in FIG. 2A. The receiver 11A converts the data to be processed and the destination information into electrical signals and inputs them to the converter 11B. The optical signals may be transmitted wirelessly. In this case, the optical transmission path L1 becomes air. The client C may transmit the data to be processed and the destination information to the receiver 11A in the form of electrical signals via a predetermined signal transmission path. In this case, the receiver 11A is configured with a connector or the like that transmits the received electrical signals directly to the converter 11B without converting them.

[0014] The converter 11B converts the data to be processed from the receiver 11A into an optical signal with a different wavelength depending on the destination (server S) specified by the destination information. The converter 11B refers to table T stored in a storage unit to identify the wavelength of the optical signal to be converted. Note that table T can be located anywhere as long as it can be referenced by the converter 11B. Table T may be stored in a storage unit external to the converter 11.

[0015] 3, in table T, for example, wavelengths of "1291 nm," "1311 nm," "1331 nm," and "1351 nm" are assigned to destination information "00" to "11" (binary numbers) that respectively designate the first server S1 to the fourth server S4. Note that the wavelengths are not limited to those described above as long as they are different from one another.

[0016] The converter 11B refers to table T using the destination information from the receiver 11A as a key, and acquires the wavelength corresponding to the destination information. The converter 11B converts the data from the receiver 11A into an optical signal with the acquired wavelength. As a result, for example, if the destination information is "00", an optical signal of "1291 nm" is generated.

[0017] The output unit 11C outputs the optical signal converted by the conversion unit 11B to an optical transmission line L2 formed of an optical fiber or the like.

[0018] The receiving unit 11A may input the received data as an optical signal to the converting unit 11B without converting it into electronic data. The converting unit 11B may convert the input optical signal into an optical signal with a wavelength corresponding to the destination information using a wavelength conversion element or the like.

[0019] The optical transmission path L2 transmits the optical signal output by the output unit 11C to the distribution device 12. The optical transmission path L2 is configured to be able to transmit multiple types of superimposed optical signals with different wavelengths. As shown in FIG. 2B, the wavelengths that the optical signals that can be transmitted through the optical transmission path L2 can take include "1291 nm," "1311 nm," "1331 nm," and "1351 nm," which correspond to the first server S1 to the fourth server S4, respectively.

[0020] The distribution device 12 is connected to the optical transmission path L2 and the first server S1 to the fourth server S4. The distribution device 12 is connected to the first server S1 to the fourth server S4 via four optical transmission paths L3, respectively. The distribution device 12 distributes the optical signal input from the optical transmission path L2 to one of the first server S1 to the fourth server S4, which is the destination, according to the wavelength of the optical signal. For example, if the wavelength of the optical signal is "1291 nm," the optical signal is distributed to the first server S1.

[0021] The distribution device 12 is composed of a passive wavelength demultiplexer and the like. The distribution device 12 includes, for example, a demultiplexer that demultiplexes an optical signal from the optical transmission line L2 into optical signals with wavelengths of "1291 nm," "1311 nm," "1331 nm," and "1351 nm" that can be output from the conversion device 11, and four output terminals that output each of the demultiplexed optical signals. The four output terminals are connected to the first server S1 to the fourth server S4, respectively, via four optical transmission lines L3 formed of optical fibers or the like. With this configuration, the optical signal from the optical transmission line L2 is distributed and transmitted to the destination server S according to the wavelength of the optical signal. The optical signal is transmitted to the server S via the transmission line L3. As a result of the above distribution, the wavelength of the optical signal transmitted by the transmission line L3 connected to the first server S1 becomes "1291 nm," as shown in FIG. 2(C). Similarly, as shown in Figures 2(D) to (F), the wavelengths of the optical signals transmitted through the three transmission paths L4 connected to the second server S2 to the fourth server S4 are "1311 nm," "1331 nm," or "1351 nm," respectively.

[0022] Each of the first server S1 to the fourth server S4 receives the optical signals distributed by the distribution device 12, converts them into electronic data, etc., and processes them. The data resulting from the processing is returned to, for example, the client C that sent the original data to be processed.

[0023] The method of returning the processing result data to the client is arbitrary. For example, data from client C is attached with the identification information of the client C. The server S returns the identification information and the processing result data in the form of an optical signal to the distribution device 12 via the optical transmission line L3 or another transmission line. The distribution device 12 has the same function as the conversion device 11, converts the processing result data from the server S into an optical signal with a wavelength corresponding to the identification information (which may be different from the wavelength corresponding to the destination information), and transmits it to the conversion device 11 via the optical transmission line L2 or another transmission line. The conversion device 11 has the same function as the distribution device 12, and transmits the received optical signal to client C according to the wavelength via the optical transmission line L1 or another transmission line.

[0024] The C-plane signal exchanged between client C and server S may be an optical signal of any wavelength.

[0025] In this embodiment, the processing target data is converted into an optical signal with a wavelength corresponding to the destination of the data, i.e., one of the first server S1 to the fourth server S4, and output to the optical transmission path L2. Therefore, even if the output timings of processing target data with different destinations overlap partially or completely in time series, the conversion unit 11B converts the processing target data into optical signals with different wavelengths, and transmits each converted optical signal to the optical transmission path L2 via the output unit 11C using wavelength multiplexing. This shortens the overall transmission time of multiple data with different destinations by the amount that time division multiplexing is not used. Furthermore, when transmitting data with different destinations, congestion due to time division multiplexing does not occur, and data transmission delays are also reduced. Furthermore, to avoid congestion, in PONs and the like, devices competing for data transmission and reception perform bandwidth control by negotiating with each other to control bandwidth. However, delays in data transmission occur due to the round-trip data transmission time required for negotiation. In this embodiment, such negotiation is unnecessary, and therefore such delays are avoided.

[0026] The optical signal is suitably transmitted to its destination by a distribution device 12 that distributes the optical signal received from the optical transmission line L2 to a server S according to the wavelength of the optical signal. Note that the distribution device 12 may not be provided, and the server S may be directly connected to the optical transmission line L2 via an optical coupler or the like. In this case, the server S must be provided with an optical filter or the like that transmits only the optical signal of the wavelength corresponding to the server S from the light coming from the optical transmission line L2. On the other hand, if the distribution device 12 is provided, there is no need to provide an optical filter or the like, and a general-purpose server that can receive optical signals can be used as the server S. If the distribution device 12 is not provided, the relay system 10 may be composed of only the conversion device 11.

[0027] Furthermore, conversion to an optical signal is performed by referring to Table T, which associates destination information with wavelengths, so that conversion of the optical signal is performed in a simple process. Furthermore, since the contents of Table T can be easily changed (see also the third embodiment described later), it is easy to change the correspondence between destinations and wavelengths.

[0028] [Second embodiment] 4, in this embodiment, the first server S1 to the fourth server S4 are constructed using computer resources provided in a disaggregated computer DC (hereinafter also simply referred to as computer DC). Examples of the computer resources include a CPU, a GPU (Graphics Processing Unit), an FPGA, and an ASIC. As in this embodiment, the first server S1 to the fourth server S4 as data destinations may be functional units provided within a single device.

[0029] In the relay system 110 according to this embodiment, the distribution device 12 is disposed in the computer DC. In such a case, the relay system 10 may be considered to be composed only of the conversion device 11. The configuration of the distribution device 12 is arbitrary, and may be configured using an optical path or the like.

[0030] The first server S1 to the fourth server S4 have service levels as shown in Table T of FIG. 5. The first server S1 is configured as a tightly coupled server with a broadband / low-latency service level. The second server S2 is configured as a first data flow server with a broadband / low-latency service level. The third server S3 is configured as a second data flow server with a low-latency service level. The first data flow server and the second data flow server are configured as different servers with different resources. The fourth server S4 is configured as a best-effort CPU server. In this embodiment, the first server S1 to the fourth server S4, which are destinations of data from client C, provide different service levels, and the data destinations also indicate the service target level required for the data processing. Therefore, the destination information in this embodiment can be considered a service tag that specifies the service or the service target level. The services provided by the first server S1 to the fourth server S4 may be the same or different services. The service level may include unavailability, etc.

[0031] When "00" is assigned as destination information to data to be processed from client C1, the data to be processed is converted by converter 11 into an optical signal with a wavelength of 1291 nm and supplied to distributor 12. Distributor 12 distributes the supplied optical signal as is to first server S1, which is a tightly coupled server. First server S1 is designed to be tuned for wideband and low latency, and provides a service at a target service level specified by the destination information (service tag).

[0032] When "11" is assigned as destination information to data to be processed from client C2, the data to be processed is converted by converter 11 into an optical signal with a wavelength of 1351 nm and supplied to distributor 12. Distributor 12 distributes the supplied optical signal directly to fourth server S4, which is a CPU server. Fourth server S4 calculates the data represented by the supplied optical signal using a general-purpose CPU. At this time, the service level of fourth server S4 is set to best effort, and fourth server S4 processes the distributed optical signal on a best effort basis.

[0033] The other configurations of this embodiment are the same as those of the first embodiment.

[0034] According to this embodiment, a dedicated wavelength can be assigned to a client C that requires low latency, thereby ensuring the target level of service desired by the user. For example, one client C (client C1 in the above) of a user that requires low-latency service can be assigned to the first server S1 that operates with low latency. In this case, by assigning the destination information of the first server S1, i.e., the wavelength corresponding to the first server S1, only to that client C, the source of the data to be processed that is sent to the first server S1 is limited, ensuring low latency. Note that multiple clients C that output data to be processed at different timings may be assigned to the first server S1. The same explanation applies to the second server S2 that also has low latency.

[0035] Furthermore, multiple clients C may be assigned to the third server S3 and the fourth server S4, which operate on a best-effort basis, and multiple pieces of processing target data may be simultaneously input to the conversion device 11 from the multiple clients C. In other words, multiple pieces of processing target data, each with the same destination information and at least partially overlapping in time series, may be supplied to the conversion device 11. In this case, the conversion unit 11B converts the multiple pieces of processing target data received by the receiving unit 11A into multiple optical signals of the same wavelength, and transmits the converted optical signals to the optical transmission system L2 via the output unit 11C using time division multiplexing. In this case, delays in data transmission due to time division multiplexing may occur for the third server S3 and the fourth server S4. However, by assigning dedicated wavelengths to clients C using the first server S1 or the second server S2, which require low latency, the impact of delays is reduced for these servers. Therefore, the transmission time for multiple pieces of data to different destinations is shorter than when all pieces of data are transmitted using time division multiplexing.

[0036] In this manner, the converter 11B may convert multiple pieces of data received by the receiver 11A as data to be processed, which have different senders but the same destination (e.g., the third server S3 or the fourth server S4), into a first optical signal of the same wavelength, and send the converted first optical signal to the optical transmission line L2 via the output unit 11C by time division multiplexing. The converter 11B may convert data received by the receiver 11A as data to be processed, which has a destination different from the destination of the multiple pieces of data (e.g., the first server S1), into a second optical signal of a different wavelength from the first optical signal, and wavelength-multiplex the converted second optical signal with the first optical signal and send it to the optical transmission line L2 via the output unit 11C. This shortens the transmission time of multiple pieces of data to different destinations, as described above. Furthermore, since the first optical signal enables simultaneous transmission of multiple pieces of data by time division multiplexing, the number of pieces of data that can be simultaneously transmitted, with a certain degree of delay allowed, is increased, and transmission delays are suppressed by not performing time division multiplexing on the second optical signal.

[0037] The computer DC can dynamically change the server S (service) built in itself to reduce power consumption, etc. Such changes include changes to the hardware that constitutes the server S and changes to the mode of the server S (for example, changing from a tightly coupled server to a data flow server). Such changes are made within a predetermined range that does not degrade the service level of the server S.

[0038] [Third embodiment] As shown in FIG. 6, a relay system 210 according to the third embodiment includes three conversion devices 11. Clients C1 to Cn are designated as clients C1 to C3. Each conversion device 11 is connected to a corresponding client C on a one-to-one basis. The conversion device 11 and the client C are connected wirelessly (using millimeter waves, for example). This configuration has the advantage that congestion does not occur in communication between the client C and the conversion device 11. The conversion device 11 may be disposed within the client C. The number of conversion devices 11 and the number of clients C are arbitrary. The conversion device 11 and the client C may be connected by wire.

[0039] Table T according to this embodiment has common content among the three conversion devices 11. As shown in FIG. 7, table T has best-effort CPU servers set as the second server S2 to the fourth server S4 in destination information "01" to "11." Under normal circumstances, client C1 outputs "01" as destination information, client C2 outputs "10" as destination information, and client C3 outputs "11" as destination information. Therefore, clients C1 to C3 receive best-effort services from the second server S2 to the fourth server S4, respectively. This state is referred to as a normal computation state. The second server S2 to the fourth server S4 may be configured with the same computation resources and process data from clients C1 to C3 sequentially. The second server S2 to the fourth server S4 may be configured with different computation resources. Furthermore, each of clients C1 to C3 may output "11" as destination information. In this case, the conversion unit 11B of each conversion device 11 may convert the data to be processed from clients C1 to C3 into optical signals of the same wavelength, and transmit the converted optical signals to the optical transmission line L2 via the output unit 11C by time division multiplexing.

[0040] The clients C1 to C3 are assumed to be automobiles traveling on a highway, and the data to be processed is measurement data indicating the measurement results obtained by various sensors (including cameras) mounted on the automobiles. A large number of conversion devices 11 are installed on the highway. It is also possible to provide a plurality of conversion devices 11 at fixed points on the highway so as to enable one-to-one communication with a plurality of clients C. Of the many conversion devices 11, three conversion devices 11 located close to the clients C1 to C3 are connected to the clients C1 to C3, respectively. The computer DC processes the measurement data transmitted from the clients C1 to C3 using the server S, generates autonomous driving data for controlling the driving of each of the clients C1 to C3, and returns the data to the clients C1 to C3. Thus, this embodiment assumes autonomous driving of automobiles. Under normal circumstances, autonomous driving control is provided at a service effort level.

[0041] In this embodiment, the contents of table T are dynamically changed, so that even if the services required change over time, the changes can be flexibly accommodated. This point will be explained below with reference to Figs. 6 to 9.

[0042] Suppose that the computer DC (e.g., the control unit DC1) detects that an abnormality (or an increased possibility of an abnormality) has occurred in client C3, one of the three clients C1 to C3 in FIG. 6, requiring emergency automatic driving control, such as to avoid a collision accident (step S11 in FIG. 8). This detection method is arbitrary. For example, when client C1, which is an automobile, detects (including predicting) using its own camera or the like that there is an abnormality in the behavior of client C3 traveling ahead of it (e.g., the client C1 is traveling out of its lane and heading toward the median strip), client C1 transmits information to that effect to the computer DC as a type of the measurement data. The control unit DC1 of the computer DC detects the abnormality by receiving the information to that effect.

[0043] When the abnormality is detected, the computer DC (e.g., the control unit DC1) sends a C-plane signal to the conversion device 11 (hereinafter also referred to as the conversion device 11-3) connected to the client C3 to instruct the conversion device 11-3 to change the contents of the table T (FIG. 7) of the conversion device 11-3 (step S12). This instruction is to change the wavelength 1351 nm corresponding to the destination information "11" to the low-latency service wavelength of 1291 nm. Based on this instruction, the conversion unit 11B of the conversion device 11-3 changes the destination information "00" corresponding to the wavelength "1291 nm" in the table T (FIG. 7) to "11" and blanks out the destination information "11" that previously corresponded to the wavelength "1351 nm" (see the table in FIG. 8). The table T after this change is shown in FIG. 9. From this point on, data from the client C3 is converted to a 1291 nm optical signal and processed with low latency by the first server S1 in the computer DC. This allows emergency autonomous driving control for client C3 to be performed with low latency in an attempt to avoid an accident.

[0044] When the computer DC (e.g., the control unit DC1) detects that the client C3 has recovered from the abnormality (step S13), it supplies the conversion device 11-3 with a C-plane signal instructing it to restore the current table T (FIG. 9) to the table T before the abnormality (FIG. 7) (step S14). The abnormality recovery may be determined based on various information from the client C1 or C3. The conversion unit 11B of the conversion device 11-3 receives this instruction and changes the contents of its own table T. From this point on, the client C3 receives best-effort service, just like the other clients C1 and C2.

[0045] The other configurations are omitted here because they are the same as those in the first and second embodiments. Note that the first server S1 to the fourth server S4 may be configured as separate server computers as shown in FIG.

[0046] The clients C1 to C3 may be drones or the like. The server S acquires various measurement data from the clients C1 to C3 as the data to be processed, and controls the operations of the clients C1 to C3 based on the acquired measurement data. The clients C1 to C3 as drones or the like monitor each other's behavior, and supply information about a client C whose behavior is determined to be abnormal to the computer DC, and emergency operation control processing may be performed by changing the destination information or wavelength as described above.

[0047] As described above, it is preferable that the conversion unit 11B changes the table T in response to an instruction from outside the conversion device 11 (particularly the conversion unit 11B) (which may be from a source other than the computer DC). This makes it possible to flexibly respond to service requests that change over time, particularly to changes from a service effort that tolerates delays to a low-delay service that does not tolerate delays.

[0048] As in this embodiment, a relay system 210 that relays data to be processed transmitted from multiple transmission sources (clients C) may include multiple conversion devices 11, each of which includes a receiver 11A, a converter 11B, and an output unit 11C. The multiple conversion devices 11 may be connected to the multiple transmission sources wirelessly or via wires. This allows each conversion device 11 to perform wavelength conversion, thereby allocating the wavelength of the converted optical signal to each conversion device 11. Furthermore, in a first case (such as normal operation), the respective converters 11B of two or more of the multiple conversion devices 11 (clients C1 to C3 in the above example) convert the data to be processed received by the receiver 11A into an optical signal with the same first wavelength (for example, 1351 nm corresponding to the above "11"). In a second case (such as an emergency) different from the first case, the converter 11B of one of the two or more conversion devices 11 (client C3 in the above example) may change the wavelength of the optical signal to be converted from the first wavelength to a second wavelength. This makes it possible to suppress transmission delays of a specific optical signal (an optical signal of the second wavelength) in special cases such as emergencies, etc. The trigger for switching between the first case and the second case is arbitrary, and may be manual, for example.

[0049] In this embodiment, an example has been given in which table T of conversion device 11 is dynamically changed, but a control signal (C-plane signal) instructing client C to change the destination information to be transmitted together with the data to be processed may be supplied from an external device such as computer DC. For example, an instruction to change the destination information to be transmitted from "11" to "01" may be supplied to client C3 without changing table T. This type of configuration may also be applied to a configuration in which one conversion device 11 is provided for multiple clients C, as shown in FIG. 1 or FIG. 4.

[0050] [Scope of the present invention] The present invention is not limited to the above-described embodiments and modifications. For example, the present invention includes various modifications to the above-described embodiments and modifications that are understandable to those skilled in the art within the scope of the technical concept of the present invention. The configurations described in the above-described embodiments and modifications can be combined as appropriate to the extent that there is no contradiction. The relay system may be a system in which all of its elements are housed in a single housing, such as when the relay system consists only of a conversion device. The destination of data relayed by the relay system may not be a server, but may be a client computer, etc. The relay system may include at least one of a source that transmits data to be processed (data to be relayed), such as client C, and multiple servers that are the destinations of the data. [Explanation of symbols]

[0051] 10...relay system, 11...conversion device, 11-3 conversion device, 11A...receiving unit, 11B...conversion unit, 11C...output unit, 12...distribution device, 110...relay system, 210...relay system, L1 to L3...optical transmission path, S1...first server, S2...second server, S3...third server, S4...fourth server.

Claims

1. A relay system that relays data to be transmitted to any one of a plurality of destinations, a receiving unit that receives the data; a conversion unit that converts the data received by the receiving unit into an optical signal with a different wavelength depending on a destination of the data among the plurality of destinations; an output unit that outputs the optical signal converted by the conversion unit to an optical transmission line, each wavelength of the optical signal is assigned to each of the plurality of destinations; the plurality of destinations include a delay-tolerant server that provides a data processing service that tolerates delays, and a low-delay server that provides a low-delay data processing service that does not tolerate delays; The conversion unit In a first case, converting the data having predetermined destination information into the optical signal of a first wavelength assigned to the delay-tolerant server; In a second case different from the first case, converting the data having the predetermined destination information into the optical signal having a second wavelength assigned to the low-latency server and different from the first wavelength. Relay system.

2. a distribution device connected to the optical transmission line and the plurality of destinations, for distributing the optical signals to destinations among the plurality of destinations according to wavelengths of the optical signals; The relay system according to claim 1 .

3. The conversion unit converting a plurality of pieces of data received by the receiving unit as the data, which have different senders and the same destination, into first optical signals of the same wavelength, and transmitting the converted first optical signals to the optical transmission line via the output unit by time division multiplexing; converting data received by the receiving unit as the data and having a destination different from the destination of the plurality of data into a second optical signal having a wavelength different from that of the first optical signal, and transmitting the converted second optical signal to the optical transmission line via the output unit by wavelength-superimposing the second optical signal on the first optical signal; 3. The relay system according to claim 1 or 2.

4. The data is provided with destination information that specifies the destination, the pre-conversion unit refers to a table in which destination information and wavelengths are associated with each other, acquires a wavelength corresponding to the destination information assigned to the data, and converts the data into an optical signal of the acquired wavelength; The relay system according to any one of claims 1 to 3.

5. the conversion unit changes the contents of the table in response to an instruction from outside the conversion unit. The relay system according to claim 4.

6. the data relayed by the relay system includes data transmitted from a plurality of transmission sources; the relay system includes a plurality of conversion devices, each of which includes the receiving unit, the converting unit, and the output unit; the plurality of conversion devices are connected to the plurality of transmission sources wirelessly or by wire, respectively; The relay system according to any one of claims 1 to 5.

7. In the first case, the conversion unit of each of two or more of the plurality of conversion devices converts the data received by the receiving unit into an optical signal of the same first wavelength, In the second case, the conversion unit of one of the two or more conversion devices changes the wavelength of the optical signal to be converted from the first wavelength to the second wavelength. The relay system according to claim 6.

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