Transmission system, transmitting device, receiving device, transmission method, and program

Abstract

To provide a transmission technique that can ensure reliability while reducing communication delay.SOLUTION: In a transmission system, a transmitting device 1A includes a duplicating unit 12 that duplicates transmission data including a plurality of frames to generate duplicated data, and a transmitting adjustment unit 13 that delays the transmission timing of each frame of the duplicated data by a predetermined time from the transmission timing of a corresponding frame of the transmission data and transmits the transmission data and the duplicated data over a single transmission path, and a receiving device 1B includes a receiving unit 21 that receives the transmission data and the duplicated data over the transmission path, and a selecting unit 23 that selects a frame of the transmission data or a frame of the duplicated data for each sequence number based on sequence numbers that indicate the same transmission order and are assigned to each frame of the transmission data and each frame of the duplicated data.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a transmission system, a transmitting device, a receiving device, a transmission method, and a program. [Background technology]

[0002] In an environment where frame (or packet) loss, which is the unit of data transmission, occurs, there is a technology to improve reliability by retransmitting lost frames. However, frame retransmission increases communication delays when frame loss occurs.

[0003] There is also a technology that adds redundant frames to frames before transmitting them and performs error correction on the receiving side, so that even if a frame loss occurs, the lost frame can be restored using the redundant frames, thereby increasing reliability.This technology reduces communication delays when a frame loss occurs, but the reliability (reachability) of the frame is relatively low.

[0004] In order to reduce communication delays while ensuring reliability, there is a technique in which multiple transmission paths are prepared between a transmitting device and a receiving device, and the same data is transmitted over the multiple paths (Technical Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-102157 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 has a problem in that the same data is transmitted over multiple transmission paths, which increases costs.

[0007] One possible method is to duplicate each frame of data and send it over a single transmission path. However, frame loss can occur in bursts, and even if duplicated frames are sent, reliability may not be ensured. Burst errors occur due to insufficient processing power or bandwidth in the communication device.

[0008] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a transmission technology that can ensure reliability while reducing communication delays. [Means for solving the problem]

[0009] In order to achieve the above object, one aspect of the present disclosure is a transmission system comprising a transmitting device and a receiving device, wherein the transmitting device comprises a copying unit that copies transmission data including a plurality of frames to generate copied data, and a transmission adjustment unit that delays the transmission timing of each frame of the copied data by a predetermined time from the transmission timing of the corresponding frame of the transmission data and transmits the transmission data and the copied data over a single transmission path, and the receiving device comprises a receiving unit that receives the transmission data and the copied data over the transmission path, and a selection unit that selects a frame of the transmission data or a frame of the copied data for each sequence number based on sequence numbers that indicate the same transmission order and are assigned to each frame of the transmission data and the copied data.

[0010] One aspect of the present disclosure is a transmitting device in a transmission system including a transmitting device and a receiving device, the transmitting device including: a copying unit that copies transmission data including a plurality of frames to generate copied data; and an adjustment unit that delays the transmission timing of each frame of the copied data by a predetermined time from the transmission timing of the corresponding frame of the transmission data, and transmits the transmission data and the copied data to the receiving device via a single transmission path.

[0011] One aspect of the present disclosure is a receiving device in a transmission system including a transmitting device and a receiving device, comprising: a receiving unit that receives transmission data including a plurality of frames and duplicate data obtained by duplicating the transmission data from the transmitting device via a single transmission path; and a selecting unit that selects a frame of the transmission data or a frame of the duplicate data for each sequence number based on a sequence number indicating the same transmission order assigned to each frame of the transmission data and the duplicate data.

[0012] One aspect of the present disclosure is a transmission method performed by a transmission system including a transmitting device and a receiving device, in which the transmitting device copies transmission data including a plurality of frames to generate duplicated data, delays the transmission timing of each frame of the duplicated data by a predetermined time from the transmission timing of the corresponding frame of the transmission data, and transmits the transmission data and the duplicated data over a single transmission path, and the receiving device receives the transmission data and the duplicated data via the transmission path and selects a frame of the transmission data or a frame of the duplicated data for each sequence number based on sequence numbers indicating the same transmission order assigned to each frame of the transmission data and the duplicated data.

[0013] One aspect of the present disclosure is a program that causes a computer to function as the transmission device. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a transmission technology that can ensure reliability while reducing communication delays. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a schematic diagram of a transmission system according to the first embodiment. [Figure 2] FIG. 2 is a configuration diagram illustrating an example of a transmission device according to the first embodiment. [Figure 3] FIG. 3 is a schematic diagram showing the transmission timing of each frame transmitted by a transmitting-side transmission device. [Figure 4] FIG. 4 is a sequence diagram showing the operation of the transmission device. [Figure 5] FIG. 5 is a flowchart showing another process of the selection unit. [Figure 6] FIG. 6 is a configuration diagram illustrating an example of a transmission device according to the second embodiment. [Figure 7] FIG. 7 shows an example of the hardware configuration. DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiments of the present disclosure will be described with reference to the accompanying drawings. In this specification and drawings, the same reference numerals indicate the same or corresponding parts.

[0017] First Embodiment 1 shows a schematic diagram of a transmission system according to this embodiment. In the illustrated example, networks 5A and 5B at both ends are connected using an intermediate network 5C. Here, Ethernet (registered trademark) is used for each of the networks 5A, 5B, and 5C, but other networks may also be used. Switches 3A and 3B (Ethernet switches) may be installed at the boundaries of network 5C.

[0018] The transmission devices 1A and 1B of this embodiment are installed outside the switches 3A and 3B and are used to configure a highly reliable network. The transmission devices 1A and 1B on the sending side duplicate (copy) transmission data from the respective networks 5A and 5B to generate duplicate data, and transmit the transmission data and duplicate data to the reception side transmission devices 1A and 1B via one transmission path of the network 5C. The transmission data and duplicate data are composed of multiple frames.

[0019] The receiving side transmission devices 1A, 1B select a frame of transmission data or a frame of duplicated data for each frame, and transfer it to downstream networks 5A, 5B.

[0020] FIG. 2 is a diagram showing an example of the configuration of each of the transmission devices 1A and 1B according to the present embodiment.

[0021] The illustrated transmission devices 1A and 1B include a transmitting unit 10 and a receiving unit 20. In this embodiment, the transmission device 1A shown in FIG. 1 is a transmitting device that transmits transmission data to the transmission device 1B, and the transmission device 1B is a receiving device that receives transmission data from the transmission device 1A. In this case, the transmission device 1A (transmitting device) uses the transmitting unit 10, and the transmission device 1B (receiving device) uses the receiving unit 20.

[0022] The transmitter 10 transmits transmission data to the transmission device 1 B via one transmission path. The transmitter 10 shown in the figure includes a receiver 11, a replicator 12, and a transmission adjuster 13.

[0023] The receiving unit 11 receives transmission data sent from the network 5A (user network). The transmission data includes a plurality of frames. A frame is a unit of data transmission. Examples of frames include Ethernet frames encapsulated in Ethernet (registered trademark) and frames using MPLS. In this embodiment, frames are used as the unit of data transmission, but packets may be used instead of frames.

[0024] The duplicating unit 12 copies transmission data including a plurality of frames to generate duplicated data. Before generating the duplicated data, the duplicating unit 12 may assign a sequence number indicating the transmission order to each frame of the transmission data, for example, to a frame header. By assigning a sequence number before generating the duplicated data, the duplicating unit 12 assigns each frame of the duplicated data the same sequence number as the corresponding frame of the transmission data.

[0025] Alternatively, the receiving transmission device 1B may use an existing sequence number in a header added in the transport layer, network layer, or the like included in each frame, without the duplicating unit 12 assigning a sequence number. Examples of the existing sequence number include a TCP sequence number, an RDMA packet sequence number, and a Fibre Channel sequence ID.

[0026] The transmission adjustment unit 13 delays the transmission timing of each frame of the duplicated data by a predetermined time from the transmission timing of the corresponding frame of the transmission data, and transmits each frame of the transmission data and the duplicated data to the receiving transmission device 1B via one transmission path. In the example shown in FIG. 1, the transmission adjustment unit 13 transmits each frame of the transmission data and the duplicated data to the transmission device 1B via the switch 3A, the network 5C (wide area network), and the switch 3B. The transmission of each frame of the transmission data and the duplicated data will be described later.

[0027] A receiving unit 20 of the receiving-side transmission device 1B receives transmission data from the transmitting-side transmission device 1A via one transmission path. The illustrated receiving unit 20 includes a receiving unit 21, a memory 22, a selecting unit 23, and a transmitting unit 24.

[0028] The receiving unit 21 receives each frame of the transmission data and the duplicated data via one transmission path, and stores them in the memory 22 .

[0029] The selector 23 selects a frame of transmission data or a frame of duplicated data for each sequence number based on the sequence number assigned to each frame of the transmission data and duplicated data stored in the memory 22. The selector 23 then outputs the frame selected for each sequence number to the transmitter 24. The selector 23 may discard frames that were not selected. Note that if the duplicator 12 of the transmitting device 1A assigned a sequence number to each frame, the selector 23 deletes the sequence number assigned to the selected frame.

[0030] The transmitter 24 transmits the frames selected by the selector 23 to the network 5B (user network) as transmission data. The transmitter 24 may transmit the selected frames to the network 5B in the order of their sequence numbers, or may transmit the selected frames to the network 5B in the order in which they are output from the selector 23.

[0031] 3 is a schematic diagram illustrating the transmission timing of each frame transmitted by the transmitting-side transmission device 1A of this embodiment. In the illustrated example, the transmitting-side transmission device 1A copies transmission data consisting of frames 1, 2, 3, and 4, and transmits the transmission data and the copied data to the receiving-side transmission device 1B via a single transmission path.

[0032] In the comparative example, each frame of transmission data is duplicated, and the frame of transmission data and the corresponding frame of the duplicated data are simply output consecutively to the transmission path. For example, frame 1 of the transmission data and frame 1 of the duplicated data are transmitted consecutively. In the comparative example, reliability may not be ensured if a burst communication error occurs in which frames are lost consecutively. That is, even if multiple identical frames are transmitted consecutively, in the event of a burst communication error, all of the same frames may be lost. Burst communication errors occur, for example, due to insufficient processing power / bandwidth in the relay routers and switches 3A and 3B, or insufficient processing power / bandwidth in the storage or memory of the transmission devices 1A and 1B.

[0033] In contrast, in this embodiment, the transmission timing of each frame of duplicated data is delayed by a predetermined time from the transmission timing of the corresponding frame of transmission data, and each frame of transmission data and duplicated data is transmitted over a single transmission path. In the example shown in the figure, frame 1 of the duplicated data is transmitted with a predetermined time (delay time) delay from frame 1 of the transmission data.

[0034] In this embodiment, by delaying each frame of the replicated data by a predetermined time, the delay time increases compared to the comparative example, but the delay is shorter than retransmitting the frame, and the tolerance to frame loss due to burst communication errors can be improved.

[0035] FIG. 4 is a sequence diagram showing the operation of the transmission devices 1A and 1B of this embodiment.

[0036] The transmitting-side transmission device 1A receives transmission data including a plurality of frames from the network 5A, and copies the transmission data to generate duplicated data (S11). Note that before generating the duplicated data, the transmission device 1A may assign a sequence number indicating the transmission order to each frame of the transmission data.

[0037] The transmission device 1A delays the transmission timing of each frame of the duplicated data by a predetermined time from the transmission timing of the corresponding frame of the transmission data, and transmits each frame of the transmission data and the duplicated data to the receiving transmission device 1B via one transmission path (S12, S13).

[0038] The receiving transmission device 1B receives each frame of transmission data and duplicated data via one transmission path and stores them in memory 22 (S14). Based on the sequence numbers assigned to each frame of transmission data and duplicated data stored in memory 22, transmission device 1B selects a frame of transmission data or a frame of duplicated data for each sequence number (S15), and transfers the selected frame as transmission data to network 5B (S16).

[0039] In selecting frames in S15, the transmission device 1B uses the sequence number assigned to each frame. The sequence number indicates the transmission order of the frames. The duplicated data is a duplicate of the transmission data made up of frames to which sequence numbers have been assigned. Therefore, the sequence number assigned to each frame of the duplicated data is the same as the sequence number assigned to each frame of the duplicated data.

[0040] Using the sequence numbers assigned to the received frames, the transmission device 1B identifies two frames (a frame of transmission data and a frame of duplicated data) that have the same information and their transmission order, and selects one of the frames. When the transmission device 1B receives two frames with the same sequence numbers, it selects one of the frames using an arbitrary method. One possible method is to select the frame that was received first or the frame that was received last. In this case, the frame that was not selected is discarded. The selector 23 deletes the selected frame and the frames that were not selected and are to be discarded from the memory 22.

[0041] Furthermore, if transmission device 1B is unable to receive only one frame due to frame loss among frames of transmission data and frames of duplicated data sent with the same sequence number, it selects the frame that it was able to receive.If transmission device 1B receives a frame with a certain sequence number and is unable to receive other frames with that sequence number even after a predetermined time has passed, it determines that the other frames have been lost and selects the frame that it was able to receive.

[0042] In selecting frames in S15, the transmission device 1B may select frames using another method described in the aforementioned Patent Document 1. In this case, the duplicating unit 12 of the transmitting-side transmission device 1A assigns a sequence number to each frame and also assigns a data identifier indicating whether each frame is transmission data or duplicated data. For example, each frame may have an area for setting a data identifier and an area for setting a sequence number in addition to a normal header and payload. The transmission device 1B is also assumed to have a memory A (not shown) for storing frames of transmission data and a memory B (not shown) for storing frames of duplicated data.

[0043] FIG. 5 is a flowchart showing an example of the processing of the selection unit 23 to which another method of Patent Document 1 is applied. The receiving unit 21 accumulates the frames of the received transmission data in the memory A that uses the received frames as a FIFO using the data identifier attached to each frame, and accumulates the frames of the received transmission data in the memory B that uses the received frames as a FIFO. The selection unit 23 extracts the oldest frame in the memory A (S101, S102), and sets the sequence number of the frame as CA. The selection unit 23 compares CA with the reference counter value CF (S103), and branches according to three cases: CF = CA, CF> CA, and CF <CA. When CF = CA, the frame read in S102 is output to the transmission unit 24, 1 is added to CF, and the state transitions to the frame waiting state of the transmission data (S104). At this time, the selection unit 23 deletes the frame from the memory A. When CF> CA, the selection unit 23 deletes and discards the frame from the memory A, and the state transitions to the frame waiting state of the transmission data (S105). When CF <CA, the selection unit 23 transitions to the frame waiting state of the duplicate data (S106).

[0044] In the frame waiting state of the duplicate data, the selection unit 23 reads the oldest frame in the memory B (S107), and sets the sequence number of the frame as CB. The selection unit 23 compares CB with the reference counter value CF (S108), and branches according to three cases: CF> CB, CF = CB, and CF <CB. When CF> CB, the selection unit 23 deletes and discards the frame read in S107 from the memory B, and the state transitions to the frame waiting state of the duplicate data (S109). When CF = CB, the frame is output to the transmission unit 24, 1 is added to CF, and the state transitions to the frame waiting state of the transmission data (S110). At this time, the selection unit 23 deletes the frame from the memory B. When CF <CB, the selection unit 23 adds 1 to CF and transitions to the frame waiting state of the transmission data (S111). Note that when the selection unit 23 outputs the selected frame to the transmission unit 24, it deletes the sequence number and the data identifier added by the transmission device 1A on the transmission side.

[0045] The transmission system of the present embodiment described above comprises a transmission device 1A and a sending device 1B. The transmission device 1A comprises a copying unit 12 that copies transmission data including a plurality of frames to generate copied data, and a transmission adjustment unit 13 that delays the transmission timing of each frame of the copied data by a predetermined time from the transmission timing of the corresponding frame of the transmission data and transmits the transmission data and the copied data over a single transmission path. The transmission device 1B comprises a receiving unit 21 that receives the transmission data and the copied data over the transmission path, and a selecting unit 23 that selects a frame of the transmission data or a frame of the copied data for each sequence number based on sequence numbers that indicate the same transmission order and are assigned to each frame of the transmission data and the copied data.

[0046] In this embodiment, the transmitting device 1 transmits not only the transmission data but also duplicated data obtained by duplicating the transmission data. In other words, by transmitting one frame twice, it is possible to improve the reachability of the frame and improve the reliability of data transmission.

[0047] In this embodiment, the transmission data and the replicated data are transmitted over a single transmission path, so that the system can be constructed at low cost.

[0048] In this embodiment, the transmission timing of each frame of the replicated data is delayed by a predetermined time from the transmission timing of the corresponding frame of the transmission data, thereby improving the tolerance to burst errors. Therefore, this embodiment can provide a transmission technology that can ensure reliability while reducing communication delays.

[0049] Second Embodiment 6 is a configuration diagram showing an example of a transmission device according to the second embodiment. A transmission device 1C according to this embodiment differs from the transmission devices 1A and 1B according to the first embodiment in that a receiving unit 20 includes a calculation unit 25 and a history storage unit 26, but is otherwise similar to the transmission devices 1A and 1B according to the first embodiment.

[0050] The calculation unit 25 of the receiving-side transmission device 1C calculates the frame loss rate using the communication history stored in the history storage unit 26, calculates a predetermined time based on the frame loss rate, and transmits it to the transmitting-side transmission device 1C. The predetermined time is a delay time that the transmission adjustment unit 13 of the transmitting-side transmission device 1C delays the transmission timing of each frame of the duplicated data from the transmission timing of the corresponding frame of the transmission data.

[0051] The history storage unit 26 of the receiving-side transmission device 1C stores frames received by the receiving unit 21. The receiving unit 21 of this embodiment stores frames received from the network 5C in the memory 22 and also in the history storage unit 26.

[0052] The calculation unit 25 calculates the frame loss rate using the communication history stored in the history storage unit 26. Because a sequence number is assigned to each frame received by the receiving unit 21, the calculation unit 25 can obtain the number of frames discarded (lost) on the network 5C by checking the sequence number. That is, if the sequence numbers of received frames are discontinuous, the calculation unit 25 determines that a discarded frame exists. The calculation unit 25 can also measure the number of received frames using the communication history. Therefore, the frame loss rate can be calculated by calculating the ratio between the number of discarded frames and the number of received frames within a certain period of time (for example, one second).

[0053] The calculation unit 25 then calculates the delay time (predetermined time) using the frame loss rate. The calculation unit 25 determines a base time interval (for example, 1 second) in advance. Assuming that frame losses occur continuously over that time interval, the necessary delay time can be calculated by multiplying the frame loss rate by the base time interval. For example, if the base time interval is 1 second and the loss rate is 0.1%, the calculation unit 25 calculates the delay time as 1 second × 0.1% = 1 ms. The calculation unit 25 transmits the calculated delay time to the transmission adjustment unit 13 of the transmitting transmission device 1C via the network 5C.

[0054] The transmission adjustment unit 13 of the transmission device 1C on the transmitting side in this embodiment uses the delay time calculated by the calculation unit 25 to delay the transmission timing of each frame of the replicated data.

[0055] The calculation unit 25 may calculate the delay time at any timing and transmit the calculated delay time to the transmitting-side transmission device 1C. The arbitrary timing may be, for example, periodically at a fixed interval, at a timing specified by the user, or at the timing when transmission of one or a predetermined number of transmission data sets is completed.

[0056] The transmission adjustment unit 13 of the transmitting transmission device 1C may delay the transmission timing of each frame of the duplicated data by a predetermined time during the first transmission, and may delay the transmission timing of each frame of the duplicated data by a delay time calculated by the calculation unit 25 from the next transmission onwards.

[0057] In this embodiment, the receiving-side transmission device 1C is equipped with a calculation unit 25 that calculates a frame loss rate using a communication history, calculates the specified time based on the frame loss rate, and transmits it to the transmitting device, and the transmission adjustment unit 13 of the transmitting-side transmission device 1C uses the calculated specified time to delay the transmission timing of each frame of the duplicated data.

[0058] In this manner, in this embodiment, the predetermined time is calculated based on the frame loss rate, and the transmission timing of the replicated data is delayed by an appropriate predetermined time according to the actual transmission situation, thereby reducing the delay time of the transmission timing of the replicated data.

[0059] In addition, although the calculation unit 25 in this embodiment calculates the predetermined time based on the frame loss rate, the calculation unit 25 may calculate the predetermined time based on the communication quality obtained from the communication history and the resource usage rate of the receiving transmission device 1C, and transmit the calculated time to the transmitting transmission device 1C.

[0060] The communication quality includes the above-mentioned frame loss rate, frame arrival time, frame arrival interval, etc. The frame arrival interval can be obtained using a confirmation command such as tcpdump or tshark. The calculation unit 25 may use packet capture or the like to obtain the time of arrival of packets and calculate the arrival interval.

[0061] The resource usage rate may be, for example, the usage rate (processing status, congestion status) of the memory, storage, etc. of the receiving-side transmission device 1C. Specifically, the disk IO status in Linux (registered trademark) can be acquired using a confirmation command such as iotop or iostat.

[0062] The calculation unit 25 may calculate the delay time by statistically processing the communication quality and the resource usage rate. Alternatively, the calculation unit 25 may acquire the delay time by inputting the communication quality and the resource usage rate into a machine-learned model or a recurrent neural network (RNN).

[0063] <Hardware> The transmission devices 1A, 1B, and 1C of the present embodiment described above can be, for example, a general-purpose computer system as shown in Fig. 7. The computer system shown in the figure includes a CPU (Central Processing Unit, processor) 901, a memory 902, a storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), a communication device 904, an input device 905, and an output device 906. The memory 902 and the storage 903 are storage devices. In this computer system, the CPU 901 executes a predetermined program loaded on the memory 902, thereby realizing the functions of the transmission devices 1A, 1B, and 1C. The transmission devices 1A, 1B, and 1C may also be implemented using an FPGA (field-programmable gate array).

[0064] Furthermore, the transmission devices 1A, 1B, and 1C may be implemented in one computer or in multiple computers. Furthermore, the transmission devices 1A, 1B, and 1C may be virtual machines implemented in a computer. Each program of the transmission devices 1A, 1B, and 1C can be stored in a computer-readable recording medium such as an HDD, SSD, USB (Universal Serial Bus) memory, CD (Compact Disc), or DVD (Digital Versatile Disc), or can be distributed via a network. The computer-readable recording medium is, for example, a non-transitory recording medium.

[0065] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the present disclosure. [Explanation of symbols]

[0066] 1A: Transmission equipment (transmitting equipment) 1B: Transmission device (receiving device) 10: Transmitter 11: Receiving unit 12:Replication Department 13: Transmission adjustment unit 20: Receiving unit 21: Receiving unit 22: Memory 23: Selection section 24: Transmitter 3A, 3B: Switch 5A, 5B, 5C: Network

Claims

1. A transmission system comprising a transmitting device and a receiving device, The transmitting device a duplication unit that duplicates transmission data including a plurality of frames to generate duplicate data; a transmission adjustment unit that delays the transmission timing of each frame of the duplicated data by a predetermined time from the transmission timing of a corresponding frame of the transmission data, and transmits the transmission data and the duplicated data over a single transmission path; The receiving device a receiving unit that receives the transmission data and the duplicated data via the transmission path; a selection unit that selects a frame of the transmission data or a frame of the duplicated data for each sequence number based on a sequence number that indicates the same transmission order and is assigned to each frame of the transmission data and the duplicated data. Transmission system.

2. The replicator assigns the sequence number indicating the transmission order to each frame of the transmission data. The transmission system according to claim 1 .

3. The receiving device a calculation unit that calculates a frame loss rate using a communication history, calculates the predetermined time based on the frame loss rate, and transmits the calculated time to the transmitting device; The transmission adjustment unit of the transmitting device delays the transmission timing of each frame of the duplicated data using the calculated predetermined time. The transmission system according to claim 1 .

4. The receiving device a calculation unit that calculates the predetermined time based on a communication quality acquired from a communication history and a resource usage rate of the receiving device, and transmits the calculated time to the transmitting device; The transmission adjustment unit of the transmitting device delays the transmission timing of each frame of the duplicated data using the calculated predetermined time. The transmission system according to claim 1 .

5. A transmitting device in a transmission system including a transmitting device and a receiving device, a duplication unit that duplicates transmission data including a plurality of frames to generate duplicate data; an adjustment unit that delays the transmission timing of each frame of the duplicated data by a predetermined time from the transmission timing of the corresponding frame of the transmission data, and transmits the transmission data and the duplicated data to the receiving device via a single transmission path. Transmitting device.

6. A receiving device in a transmission system including a transmitting device and a receiving device, a receiving unit that receives transmission data including a plurality of frames and duplicated data obtained by duplicating the transmission data from the transmitting device via a single transmission path; a selection unit that selects a frame of the transmission data or a frame of the duplicated data for each sequence number based on a sequence number that indicates the same transmission order and is assigned to each frame of the transmission data and the duplicated data. Receiving device.

7. A transmission method performed by a transmission system including a transmitting device and a receiving device, The transmitting device Duplicating transmission data including a plurality of frames to generate duplicate data; delaying a transmission timing of each frame of the duplicated data by a predetermined time from a transmission timing of a corresponding frame of the transmission data, and transmitting the transmission data and the duplicated data over a single transmission path; The receiving device receiving the transmission data and the duplicated data via the transmission path; A frame of the transmission data or a frame of the duplicated data is selected for each sequence number based on a sequence number that indicates the same transmission order and is assigned to each frame of the transmission data and the duplicated data. Transmission method.

8. A program that causes a computer to function as the transmitting device according to claim 5.

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