COMMUNICATION SYSTEM, COMPUTER, COMMUNICATION METHOD, AND PROGRAM

Abstract

This communication system comprises a plurality of computers that are connected to an optical network. The optical network comprises a main signal communication path 4 and a control communication path 3. Computers 1, 2 each comprise: a remote direct memory access (RDMA) communication unit 11 that transmits, via the control communication path 3 to a computer to be connected to, setting information for setting the main signal communication path 4; and a main signal transmitting / receiving unit 16 that establishes the main signal communication path 3 on the basis of the setting information. The RDMA communication unit 11 instructs the setting of an RDMA communication path in parallel with the transmission of the setting information. The computers 1, 2 each further comprise a RDMA control unit 14 that allocates a memory area for RDMA communication on the basis of the instruction, and that transmits setting information including the memory area to the computer to be connected to via the control communication path 3, thereby setting the RDMA communication path.

Description

[Technical field]

[0001] The present invention relates to a communication system, a computer, a communication method, and a program. [Background technology]

[0002] In data communications between computer systems over relatively short distances, such as within a data center, RDMA (Remote Direct Memory Access) technology is used to transfer data by accessing memory between computers without going through the CPU in order to increase the communication processing speed (Non-Patent Document 1). By connecting computers directly to the optical network via optical waveguides, the effects of signal loss at relay nodes are eliminated, making it possible to apply RDMA to long-distance data communications.

[0003] In optical communications, with the spread of 5G, distributed control methods and centralized control methods are being researched to dynamically set up or delete optical communication paths in response to various communication requests that arise between geographically distributed computers (Non-Patent Documents 2 and 3). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] IETF, “A Remote Direct Memory Access Protocol Specification”, RFC5040, October 2007 [Non-Patent Document 2] Atsuko Takefusa, "Co-location Experiments of Computing Resources and Optical Path Network Resources in a Grid", IPSJ Technical Report 2006-ARC-167 2006-HPC-105 [Non-Patent Document 3] Masahiko Kamino, "Photonic Transport Network Architecture and Control Management Technology," NTT Technical Journal, October 2007 Summary of the Invention [Problem to be solved by the invention]

[0005] When setting up data transfer using RDMA in computer systems connected via an optical network, a communication path is established for each layer in order from the lower layer to the upper layer in a typical communication method.

[0006] When starting RDMA communication, first the main signaling channel is established at the lowest layer, layer 1, and then the RDMA communication channel is established at the higher layer. It takes several minutes to set up the main signaling channel at layer 1, but the RDMA communication channel is set up after waiting for the layer 1 setting to be completed.

[0007] For this reason, when a main signal communication path and an RDMA communication path are dynamically established in response to a request from a user, there is a problem that it takes a long time before RDMA communication becomes possible.

[0008] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to reduce the time required until the start of RDMA communication. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, one aspect of the present invention is a communication system comprising a plurality of computers connected to an optical network, the optical network including a main signal communication path and a control communication path, each computer comprising a communication unit that transmits configuration information for setting the main signal communication path to a connected computer via the control communication path, and a main signal transceiver unit that establishes the main signal communication path based on the configuration information, and the communication unit comprises a control unit that instructs the setting of an RDMA (Remote Direct Memory Access) communication path in parallel with transmitting the configuration information, reserves a memory area for RDMA communication based on the instruction, and transmits configuration information including the memory area to the connected computer via the control communication path to set up the RDMA communication path.

[0010] One aspect of the present invention is a computer connected to a destination computer via an optical network, the optical network including a main signal communication path and a control communication path, the computer comprising a communication unit that transmits configuration information for setting the main signal communication path to the destination computer via the control communication path, and a main signal transceiver unit that establishes the main signal communication path based on the configuration information, the communication unit comprising a control unit that instructs the setting of an RDMA (Remote Direct Memory Access) communication path in parallel with the transmission of the configuration information, reserves a memory area for RDMA communication based on the instruction, and transmits configuration information including the memory area to the destination computer via the control communication path to set up the RDMA communication path.

[0011] One aspect of the present invention is a communication method performed by a communication system having a plurality of computers connected to an optical network, the optical network including a main signal communication path and a control communication path, and each computer performs the following steps: transmitting configuration information for setting the main signal communication path to a connected computer via the control communication path, establishing the main signal communication path based on the configuration information, and, in parallel with the step of transmitting the configuration information, reserving a memory area for RDMA (Remote Direct Memory Access) communication, and transmitting configuration information including the memory area via the control communication path to the connected computer to set up the RDMA communication path.

[0012] One aspect of the present invention is a program for causing a computer to function as the above-mentioned calculator. Effect of the Invention

[0013] According to the present invention, it is possible to reduce the time required to start RDMA communication. [Brief description of the drawings]

[0014] [Figure 1] 1 is a configuration diagram of a communication system according to an embodiment of the present invention. [Diagram 2]FIG. 11 is an explanatory diagram for explaining a communication path setting process of a comparative example. [Diagram 3] FIG. 2 is an explanatory diagram for explaining a communication path setting process according to the embodiment; [Figure 4] FIG. 4 is a sequence diagram showing a communication path setting process according to the present embodiment. [Diagram 5] FIG. 5 is an explanatory diagram for explaining messages of S14 and S17 in FIG. [Figure 6] FIG. 5 is a sequence diagram showing details of S31 and S32 in FIG. [Figure 7] 3 is a sequence diagram showing a communication path setting process of the comparative example of FIG. 2. [Figure 8] 2 is an example of a hardware configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] <Communication system configuration> 1 is a system configuration diagram of a communication system according to an embodiment of the present invention. The communication system according to the present embodiment includes a plurality of computers 1 and 2 connected to an optical network (optical transmission line).

[0017] The optical network includes a control communication path 3 and a main signal communication path 4. The control communication path 3 is a communication path for transmitting control signals. The main signal communication path 4 is a large-capacity, low-latency communication path of layer 1 (lower layer). The control communication path 3 is set at all times, and the main signal communication path 4 is set dynamically in response to requests from users.

[0018] Computers 1 and 2 transfer data using RDMA (Remote Direct Memory Access) communication. RDMA communication transfers data from the memory of computer 1 to the memory of the other computer using DAM (Direct Memory Access). In RDMA communication, data is transferred without going through the operating systems of computers 1 and 2, so high throughput and low latency data transfer can be achieved.

[0019] In this embodiment, as an upper layer of the main signal communication channel 4 (OTN protocol) of Layer 1, an RDMA communication channel (RDMA protocol) is set on the main signal communication channel 4 end-to-end between the computers 1 and 2. That is, the communication system of this embodiment realizes RDMA over Layer 1 transmission.

[0020] Each of the computers 1 and 2 includes an RDMA communication unit 11 (communication unit), a communication switching unit 12, a data storage unit 13, an RDMA control unit 14 (control unit), a control signal transmitting / receiving unit 15, and a main signal transmitting / receiving unit 16.

[0021] The RDMA communication unit 11 is an application that performs RDMA communication. The RDMA communication unit 11 is implemented using a CPU and a memory. The RDMA communication unit 11 controls the establishment and deletion of the main signal communication path 4. For example, the RDMA communication unit 11 of the computer 1 transmits setting information (control message) for establishing the main signal communication path 4 to the connected computer 2 via the control communication path 3.

[0022] The RDMA communication unit 11 controls the setting and deletion of an RDMA communication path. Specifically, the RDMA communication unit 11 of the computer 1 instructs the RDMA control unit 14 to set up an RDMA communication path in parallel with the transmission of setting information of the control communication path 3.

[0023] The communication switching unit 12 is, for example, a Root Complex or a PCI switch, and switches the device to which the RDMA communication unit 11 communicates.

[0024] The data storage unit 13 is a memory or storage, and stores various data. When the data storage unit 13 is a memory, the RDMA communication unit 11 operates on the data storage unit 13.

[0025] The RDMA control unit 14 controls data transfer by RDMA communication. A DMA (Direct Memory Access) controller can be used for the RDMA control unit 14. The DMA controller is a dedicated application (IC chip) for controlling DMA transfer, and is implemented on, for example, an FPGA NIC (Field Programmable Gate Array Network Interface Card). The RDMA control unit 14 of this embodiment secures a memory area for RDMA communication based on an instruction from the RDMA communication unit 11, and transmits setting information including the memory area to the connected computer 2 via the control communication path 3 to set up the RDMA communication path.

[0026] The control signal transmitting / receiving unit 15 transmits and receives a control signal flowing through the control signal path 3. The control signal transmitting / receiving unit 15 may be a NIC (Network Interface Card).

[0027] The main signal transmitting / receiving unit 16 transmits and receives a main signal flowing through the main signal communication path 4. A NIC equipped with a laser or the like can be used as the main signal transmitting / receiving unit 16. The main signal transmitting / receiving unit 16 establishes the main signal communication path 4 based on setting information of the main signal communication path 4.

[0028] <Communication path setup process> Next, the process of setting up the main signal communication path 4 and the RDMA communication path will be described. It is assumed that the control communication path 3 has been set up in advance. The process of setting up the main signal communication path 4 and the RDMA communication path includes the following processes A, B, and C. Processes A and B can be performed in parallel with process C.

[0029] Process A: The computers 1 and 2 performing RDMA communication transmit and receive control messages (setting request, setting response) for setting up a main signal communication channel 4 via a control communication channel 3 .

[0030] Process B: The computers 1 and 2 set up the main signal communication path 4 based on the control message.

[0031] Process C: The computers 1 and 2 transmit and receive control messages (setting request and setting response) for setting up an RDMA communication path, and set up the RDMA communication path.

[0032] Fig. 2 is an explanatory diagram for explaining a communication path setting process in a comparative example of this embodiment. In Fig. 2, the main signal communication path 4 and the RDMA communication path are set sequentially in the order of process A, process B, and process C. That is, the communication paths are established in order from the lower layer to the higher layer for each layer, and the setting of the RDMA communication path for process C is not started until the main signal communication path 4 is established. In the comparative example, process C is performed via the main signal communication path 4.

[0033] For this reason, the time it takes to establish an RDMA communication path is the sum of the processing times for process A, process B, and process C, and it takes a long time from the start of the setup process to the start of RDMA communication. The processing time for process B is long, about several minutes.

[0034] FIG. 3 is an explanatory diagram for explaining the communication path setting process of the present embodiment.

[0035] In this embodiment, processes A and B and process C are performed in parallel. The control signal communication path 3 is used not only to set up the main signal communication path 4 but also to set up the RDMA communication path. The control communication path 3 is established in advance to set up (or delete) the main signal communication path 4.

[0036] The RDMA communication unit 11 starts setting up the RDMA communication channel as well as starting setting up the main signal communication channel 4. In this manner, in this embodiment, the setting up of the main signal communication channel 4 and the setting up of the RDMA communication channel can be processed in parallel, and the time from the start of the setting process to the start of RDMA communication can be shortened.

[0037] As shown in Figure 3, in process A, the RDMA communication unit 11 of computer 1 transmits and receives control messages (setting information) for setting up a main signal communication path 4 with the RDMA communication unit 11 of the connected computer 2 via the control signal transmission / reception unit 15 and the control communication path 3.

[0038] In process B, which is performed after process A, the RDMA communication unit 11 of the computer 1 controls the main signal transmission / reception unit 16 to establish a main signal communication path 4 with the destination computer 2 based on the control message.

[0039] Process C is performed independently and in parallel with processes A and B. RDMA communication unit 11 of computer 1 sends an instruction to set up an RDMA communication path to RDMA control unit 14. Based on the instruction, RDMA communication unit 11 reserves a memory area for RDMA communication, and transmits setting information including the reserved memory area to destination computer 2 via control communication path 3. RDMA control unit 14 of computer 2 reserves a memory area for RDMA communication based on the setting information. As a result, the RDMA communication path is set up.

[0040] In this embodiment, processing C is performed in parallel with processing A and B, so the time until the RDMA communication path is established is the sum of the processing times of processing A and processing B, and the time until RDMA communication starts can be shortened compared to the comparative example in Figure 2.

[0041] FIG. 4 is a sequence diagram showing a process of setting up a communication path according to the present embodiment shown in FIG.

[0042] Process A is S12 and S13, process B is S14 to S18, and process C is S31 to S33. A control communication path 3 is established in advance between computers 1 and 2 (S11).

[0043] In process A, the RDMA communication unit 11 of the computer 1 accepts a user request and transmits a setting request (control message) including setting information for setting the main signal communication path 4 to the computer 2 via the control signal transmission / reception unit 15 and the control communication path 3 (S12). The user request specifies the node identifier of the computer 2 to be connected.

[0044] The main signal communication path 4 (optical path) can be set up or deleted using distributed control such as GMPLS (Generalized Multi Protocol Label Switching) (Non-Patent Document 2), or centralized control such as SDN (Software Defined Network) or NMS (Network Management SYSTEM) / EMS (Element Management SYSTEM) (Non-Patent Document 3).

[0045] When GMPLS distributed control is used, the configuration information (configuration request) sent by Computer 1 includes a message identifier (Session ID), a node identifier of the local end point of the main signal communication path 4, a node identifier of the remote end point of the main signal communication path 4, an adjacent hop / end point identifier, a wavelength label identifier (candidate group), transmission capacity, etc.

[0046] When SDN centralized control is used, the configuration information (configuration request) that computer 1 sends to computer 2 via a centralized control server (not shown) includes a message identifier (Session ID), a node identifier of the local end point of the main signal communication path 4, an interface / end point identifier as the local end point of the main signal communication path 4, a node identifier of the remote end point of the main signal communication path, a wavelength label identifier, transmission capacity, etc.

[0047] The RDMA communication unit 11 of the computer 2 receives the setting request via the control signal transmission / reception unit 15, and sets up the main signal communication channel 4 based on the setting information included in the setting request. The RDMA communication unit 11 of the computer 2 transmits a setting response (control message) including the setting information of the main signal communication channel 4 to the computer 1 via the control signal transmission / reception unit 15 and the control communication channel 3 (S13). The computer 1 receives the setting response via the control signal transmission / reception unit 15.

[0048] When GMPLS distributed control is used, the configuration information (configuration response) sent by the computer 2 includes a message identifier (Session ID), a node identifier of the local end point of the main signal communication path 4, a node identifier of the remote end point of the main signal communication path 4, an adjacent hop / end point identifier, transmission capacity, an adjacent hop / end point identifier and a wavelength label identifier determined as the main signal communication path 4, etc.

[0049] When SDN centralized control is used, the configuration information (configuration response) sent to computer 1 via the centralized control server includes a message identifier (Session ID), a node identifier of the local end point of the main signal communication path 4, an interface / end point identifier as the local end point of the main signal communication path 4, a node identifier of the remote end point of the main signal communication path, a wavelength label identifier, transmission capacity, etc.

[0050] In process B, upon receiving the setting response, the RDMA communication unit 11 of Computer 1 instructs the main signal transceiver unit 16 to start the main signal communication path 4 (S14). After transmitting the setting response, the RDMA communication unit 11 of Computer 2 instructs the main signal transceiver unit 16 to start the main signal communication path 4 (S15). The main signal transceiver units 16 of Computers 1 and 2 establish the main signal communication path 4 based on the setting information in the setting request and the setting response (S16). It takes a long time, on the order of several minutes, from when each main signal transceiver unit 16 receives the start-up instruction until the main signal communication path 4 is actually established.

[0051] After the main signal communication path 4 is established, the main signal transmission / reception units 16 of the computers 1 and 2 each transmit a response to the start-up instruction to the RDMA communication unit 11 (S17, S18).

[0052] FIG. 5 is an explanatory diagram illustrating messages between RDMA communication unit 11 and main signal transmission / reception unit 16 in S14 and S17 (or S15 and S18) in FIG.

[0053] The RDMA communication unit 11 sends a message including the following items to the main signal transmitting / receiving unit 16 as an instruction to start S14 and S15.

[0054] · Interface Startup Laser on Wavelength control on Modulation method (e.g. 16QAM / 32QAM, QPSK) ·Error correction method (Reed Solumon) In addition, in the case of an instruction to stop the main signal communication path 4, the above messages will be "interface stopped", "laser off", and "wavelength control off".

[0055] In response to S17 and S18, the main signal transmitting / receiving unit 16 sends a message indicating the processing result of whether the establishment of the main signal communication path 4 has succeeded or failed.

[0056] Returning to Fig. 4, the process C will be described. The process C is executed in parallel with the processes A and B. The RDMA communication unit 11 of the computer 1 sends an instruction to set up an RDMA communication path to the RDMA control unit 14. Based on the instruction, the RDMA control unit 14 executes settings such as reserving memory for RDMA, and transmits a setting request including the setting information to the connected computer 2 via the control signal transmission / reception unit 15 and the control communication path 3 (S31).

[0057] When RDMA control unit 14 of Computer 2 receives the setting request via control signal transmission / reception unit 15, it executes setting such as reserving memory for RDMA based on the setting information included in the setting request, and transmits a setting response including the setting information to Computer 1 via control signal transmission / reception unit 15 and control communication path 3 (S32). As a result, the RDMA communication path is set up (S33).

[0058] The RDMA communication unit 11 of the computer 1 may include the communication start timing in the setting information that it transmits to the computer 2 in S31. Specifically, the RDMA communication unit 11 sets the communication start timing in a setting instruction to the RDMA control unit 14, and the RDMA control unit 14 transmits the setting information including the communication start timing to the computer 2. The RDMA communication units 11 of the computers 1 and 2 actually start RDMA communication based on the communication start timing.

[0059] The communication start timing is timer information, and may be, for example, the establishment time of the RDMA communication path plus a predetermined time (fixed value). By setting the predetermined time in consideration of the time required to establish the main signal communication path 4, the RDMA communication is started after the main signal communication path 4 is established.

[0060] If the RDMA communication path is established and the RDMA communication starts before the establishment of the main signal communication path 4, the RDMA communication will fail. Therefore, by setting the communication start timing in the configuration information, it is possible to prevent failure of the RDMA communication.

[0061] FIG. 6 is a sequence diagram showing details of the processes of RDMA communication unit 11 and RDMA control unit 14 in S31 and S32 in FIG.

[0062] The RDMA communication unit 11 of the computer 1 acquires the source address and the destination address (S31-1), and sends a setting instruction to the RDMA control unit 14 to set up an RDMA communication path (S31-2). The setting instruction (e.g., "open") includes the following instructions:

[0063] · Creating SQ (Send Queue), CQ (Completion Queue) and QP (Queue Pair) - Mapping virtual memory addresses to physical memory addresses Memory allocation The RDMA control unit 14 executes settings such as reserving memory for RDMA in accordance with the setting instruction (S31-3). Then, the RDMA control unit 14 transmits a setting request including setting information such as memory information to the computer 2 via the control communication path 3 (S31-4). For example, in the setting request, "Connect" is used when the service type is RC (Reliable Connection), and "mmap" is used when the service type is UD (Unreliable Datagram).

[0064] When the RDMA control unit 14 of the computer 2 receives the setting request, it executes settings such as reserving memory for RDMA in accordance with the setting request (S32-1). Specifically, the RDMA control unit 14 executes the following settings to start RDMA communication.

[0065] · Creating RQ (Receive Queue), CQ (Completion Queue) and QP (Queue Pair) - Mapping virtual memory addresses to physical memory addresses Memory allocation The RDMA control unit 14 transmits a setting response including setting information such as memory information to the computer 1 via the control communication path 3 (S32-2). The RDMA control unit 14 of the computer 1 receives the setting information and notifies the RDMA communication unit 11 of the setting information (S32-3). The setting information also includes a status indicating whether or not the setting of the RDMA communication path on the computer 2 was successful. In this manner, the RDMA communication path is set.

[0066] 4, process C is performed in parallel with processes A and B. Therefore, the processing time of process C is absorbed into the processing time of processes A and B, and the time until RDMA communication starts is the sum of the processing times of processes A and B.

[0067] On the other hand, Fig. 7 is a sequence diagram showing a communication channel setting process of the comparative example shown in Fig. 2. In the illustrated sequence diagram, a setting request for setting the main signal communication channel 4 is transmitted and received in S12 to S13 (processing A), the main signal communication channel 4 is set in S14 to S18 (processing B), and an RDMA communication channel is set in S19 to S21 (processing C). That is, the main signal communication channel 4 and the RDMA communication channel are set sequentially in the order of processes A, B, and C. Therefore, the time until the RDMA communication channel is established is the sum of the processing times of processes A, B, and C, and requires a longer time than the present embodiment shown in Fig. 4.

[0068] <Action and effect> The communication system of the present embodiment described above is a communication system having a plurality of computers connected to an optical network, the optical network including a main signal communication path 4 and a control communication path 3, and each of the computers 1, 2 is provided with an RDMA communication unit 11 that transmits setting information for setting the main signal communication path 4 to a connected computer via the control communication path 3, and a main signal transceiver unit 16 that establishes the main signal communication path 3 based on the setting information, and the RDMA communication unit 11 is provided with an RDMA control unit 14 that instructs setting of the RDMA communication path in parallel with transmitting the setting information, secures a memory area for RDMA communication based on the instruction, and transmits setting information including the memory area to the connected computer via the control communication path 3 to set up the RDMA communication path.

[0069] In this manner, in this embodiment, the setting of the main signal communication channel 4 and the setting of the RDMA communication channel are performed in parallel. As a result, in this embodiment, the setting of the RDMA communication channel can be proceeded without waiting for the establishment of the main signal communication channel of layer 1 as in the communication method of the comparative example, so that RDMA data communication can be started in a short time. In other words, the time required to start RDMA communication can be shortened.

[0070] In this embodiment, the computer 1 may transmit setting information including the timing of starting the RDMA communication to the connected computer 2. This makes it possible to prevent the RDMA communication from starting before the main signal communication path 4 is established.

[0071] <Hardware configuration> The above-described computers 1 and 2 may be, for example, a general-purpose computer system as shown in Fig. 8. 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 each function of the computers 1 and 2.

[0072] The computers 1 and 2 may be implemented in one computer or in multiple computers. The computers 1 and 2 may be virtual machines implemented in a computer. The computer programs may be stored in a computer-readable recording medium such as a HDD, SSD, a Universal Serial Bus (USB) memory, a Compact Disc (CD), or a Digital Versatile Disc (DVD), or may be distributed via a network.

[0073] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0074] 1, 2: Calculator 11: RDMA communication unit (communication unit) 12: Communication switching unit 13: Data storage unit 14: RDMA control unit (control unit) 15: Control signal transmission / reception unit 16: Main signal transmitter / receiver 3: Control channel 4: Main signal communication path

Claims

1. A communication system including a plurality of computers connected to an optical network, the optical network includes a main signal channel and a control channel; Each computer is a communication unit that transmits first setting information for setting the main signal communication path to a connected computer via the control communication path, and in parallel with the transmission of the first setting information, instructs a control unit to set an RDMA (Remote Direct Memory Access) communication path of an upper layer that is established on the main signal communication path of a lower layer; a main signal transmitting / receiving unit that establishes the main signal communication path based on the first setting information; the control unit that receives the instruction, and transmits second setting information for setting the RDMA communication path to the destination computer via the control communication path, thereby setting the RDMA communication path. Communication systems.

2. The control unit transmits the second setting information including a communication start timing of the RDMA communication. The communication system according to claim 1 .

3. A computer connected to a destination computer via an optical network, the optical network includes a main signal channel and a control channel; The computer includes: a communication unit that transmits first setting information for setting the main signal communication path to a connected computer via the control communication path, and in parallel with the transmission of the first setting information, instructs a control unit to set an RDMA (Remote Direct Memory Access) communication path of an upper layer that is established on the main signal communication path of a lower layer; a main signal transmitting / receiving unit that establishes the main signal communication path based on the first setting information; the control unit that receives the instruction, and transmits second setting information for setting the RDMA communication path to the destination computer via the control communication path, thereby setting the RDMA communication path. calculator.

4. A communication method performed by a communication system having a plurality of computers connected to an optical network, comprising: the optical network includes a main signal channel and a control channel; Each computer is transmitting first setting information for setting the main signal communication path to a destination computer via the control communication path, and instructing a control unit to set an RDMA (Remote Direct Memory Access) communication path of an upper layer to be established on the main signal communication path of a lower layer in parallel with the transmission of the first setting information; establishing the main signal communication path based on the first setting information; receiving the instruction, and transmitting second setting information for setting the RDMA communication path to the destination computer via the control communication path, thereby setting the RDMA communication path. Communication methods.

5. A program for causing a computer to function as the calculator according to claim 3.

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