Control device and control method

Abstract

This control device (10) comprises a search unit (11) that searches existing GCL for a respective plurality of communication devices (100) for a time slot that has not been allocated an existing flow and is at a position that is shifted exactly the amount of a propagation delay to the communication devices (100) from the time slot of an existing flow, a determination unit (12) that determines whether a new flow can be allocated to the searched time slot, and a generation unit (13) that, when it has been determined that the new flow can be allocated to the searched time slot, generates a gate control list in which the new flow has been allocated to the searched time slot.

Description

Control device and control method

[0001] The present disclosure relates to a control device and a control method.

[0002] Time Aware Shaper (TAS) is a known technology in which multiple communication devices transmit flows over a network in accordance with a gate control list (GCL) (see Non-Patent Document 1). The GCL is composed of multiple time slots arranged in chronological order and defines the transmission schedule for multiple flows.

[0003] In scheduling by TAS, when a new flow to be transmitted (a new flow) is added, the time slot of the new flow may be allocated to a position selected by an arbitrary selection method that is unrelated to the time slots of existing flows. There are various methods for allocating time slots of new flows, such as random allocation, sparse allocation of time slots to which flows are assigned, and dense allocation of time slots to which flows are assigned.

[0004] Non-Patent Document 2 describes a method for allowing delay variations when adding a time slot for a new flow to an existing GCL.

[0005] “IEEE802.1Qbv - Enhancements for Scheduled Traffic”, [online], [Retrieved December 11, 2023], Internet<URL:https: / / www.ieee802.org / 1 / pages / 802.1bv.html> H.Abe et al., “Improvement of accommodation efficiency by TAS scheduling considering jitter caused by transmission period”, 2023 IEEE 20th Annual Consumer Communications & Networking Conference, NV, 2023, pp.146-151

[0006] 9 is a diagram showing an example of transmission of multiple flows A to N by multiple communication devices 100 (communication devices 100-1 to 100-5). While FIG. 9 shows an example in which communication devices 100-1 to 100-5 are connected in series, in reality, multiple communication devices 100 are connected in a branched manner. Therefore, a flow transmitted from a communication device 100 (not shown in FIG. 9) may merge into a communication section consisting of communication devices 100-1 to 100-5, or a flow may branch from the communication section consisting of communication devices 100-1 to 100-5 and be transmitted to a communication device 100 (not shown).

[0007] Flows A, B, and F are transmitted from the communication device 100-1 to the communication device 100-2, flow C is transmitted from the communication device 100-1 to the communication device 100-3 via the communication device 100-2, flow D is transmitted from the communication device 100-1 to the communication device 100-4 via the communication device 100-2 and the communication device 100-3, flow E is transmitted from the communication device 100-1 to the communication device 100-5 via the communication device 100-2, the communication device 100-3, and the communication device 100-4, and flow G is transmitted from the communication device 100-2 to the communication device 100-1. 00-3, flow H is transmitted from communication device 100-2 to communication device 100-4 via communication device 100-3, flow I is transmitted from communication device 100-2 to communication device 100-5 via communication device 100-3 and communication device 100-4, flow J is transmitted from communication device 100-3 to communication device 100-4, flow K is transmitted from communication device 100-3 to communication device 100-5 via communication device 100-4, and flows L, M, and N are transmitted from communication device 100-4 to communication device 100-5.

[0008] 10 is a diagram showing an example of GCLs for the communication port P1 of the communication device 100-1 on the communication device 100-2 side, the communication port P2 of the communication device 100-2 on the communication device 100-3 side, the communication port P3 of the communication device 100-3 on the communication device 100-4 side, and the communication port P4 of the communication device 100-4 on the communication device 100-5 side, which define the transmission schedules for the above-mentioned flows A to N. Note that there is a propagation delay in the transmission of flows between the communication devices 100. In FIG. 10, the GCLs of each communication device 100 are shown shifted along the time axis by the amount of the propagation delay between the communication devices 100.

[0009] Consider the case of adding a new flow to be transmitted from communication device 100-1 to communication device 100-5 via communication device 100-2, communication device 100-3, and communication device 100-4 in FIG. In this case, if the time slots of flows A to N are allocated without considering the allocation of time slots of existing flows, the scheduling of the new flow will be equivalent to scheduling based on a GCL in which the GCLs of communication devices 100-1 to 100-4 are virtually superimposed, as shown in FIG. 11 . In such scheduling based on a GCL in which the GCLs of each communication device 100 are virtually superimposed, the number of available time slots will decrease, making it difficult to allocate time slots for the new flow. As a result, the bandwidth utilization efficiency of the network will decrease.

[0010] In view of the above circumstances, an object of the present disclosure is to provide a control device and a control method that can increase the probability of scheduling a new flow and improve the bandwidth utilization efficiency of a network.

[0011] In order to solve the above problem, a control device according to the present disclosure is a control device that controls a plurality of communication devices that transmit a plurality of flows based on a gate control list that is composed of a plurality of time slots and that defines the transmission schedules of the plurality of flows, and that includes: a search unit that searches, in an existing gate control list that defines the transmission schedules of existing flows for each of the plurality of communication devices, for a time slot that is located at a position shifted by the propagation delay from the time slot of the existing flow to each communication device and in which the existing flow is not placed; a determination unit that determines whether a new flow can be placed in the searched time slot; and a generation unit that, when it is determined that the new flow can be placed in the searched time slot, generates a gate control list in which the new flow is placed in the searched time slot.

[0012] Furthermore, in order to solve the above-mentioned problems, the control method according to the present disclosure is a control method executed by a control device that controls a plurality of communication devices that transmit a plurality of flows based on a gate control list that is made up of a plurality of time slots and that defines a transmission schedule for the plurality of flows, and includes the steps of: searching, in an existing gate control list that defines the transmission schedule for an existing flow of each of the plurality of communication devices, for a time slot that is located at a position shifted by the propagation delay from the time slot of the existing flow to each communication device and in which the existing flow is not assigned; determining whether or not it is possible to assign a new flow to the searched time slot; and, if it is determined that it is possible to assign the new flow to the searched time slot, generating a gate control list in which the new flow is assigned to the searched time slot.

[0013] The control device and control method according to the present disclosure can increase the probability of scheduling new flows and improve the bandwidth utilization efficiency of the network.

[0014] 10 is a diagram showing an example of the configuration of a communication system including a control device according to the present disclosure. FIG. 11 is a diagram showing an example of the configuration of the control device shown in FIG. 1. FIG. 12 is a flowchart showing an example of the operation of the control device shown in FIG. 2. FIG. 13 is a diagram for explaining an example of generation of a GCL by the control device shown in FIG. 2. FIG. 14 is a diagram for explaining an example of generation of a GCL by the control device shown in FIG. 2. FIG. 15 is a diagram for explaining another example of generation of a GCL by the control device shown in FIG. 2. FIG. 16 is a diagram showing an example of connection of communication devices. FIG. 17 is a diagram showing yet another example of generation of a GCL by the control device shown in FIG. 2. FIG. 18 is a diagram showing an example of the hardware configuration of the control device shown in FIG. 2. FIG. 19 is a diagram showing an example of transmission of multiple flows by multiple communication devices. FIG. 20 is a diagram showing an example of GCL of each communication device shown in FIG. 9. FIG. 21 is a diagram showing a virtual superposition of GCLs of each communication device shown in FIG.

[0015] FIG. 1 is a diagram illustrating an example configuration of a communication system 1 including a control device 10 according to an embodiment of the present disclosure.

[0016] The communication system 1 includes a plurality of communication devices 100-1 to 100-5, a plurality of user devices 200-1 to 200-5, and a control device 10. The communication devices 100-1 to 100-5 are provided corresponding to the plurality of user devices 200-1 to 200-5, respectively. Hereinafter, when there is no need to distinguish between the communication devices 100-1 to 100-5, they will be referred to as communication devices 100, and when there is no need to distinguish between the user devices 200-1 to 200-5, they will be referred to as user devices 200.

[0017] The communication device 100 uses a TAS technique in the TSN (Time-Sensitive Networking) standard to transfer multiple flows to other adjacent communication devices 100. The communication device 100 may be, for example, a switch.

[0018] Specifically, the communication device 100 has a communication port that transmits multiple flows based on a gate control list (GCL) consisting of multiple time slots and defining a transmission schedule for the multiple flows. When the communication device 100 receives a flow from a corresponding user device 200 or another communication device 100, it stores the flow in a queue and transmits it at the timing indicated in the GCL. Furthermore, when the communication device 100 receives a flow addressed to the corresponding user device 200, it outputs the flow to the corresponding user device 200. When a GCL is generated by the control device 10 (described later), the communication device 100 receives and stores the GCL and transmits the flow based on the stored GCL.

[0019] The control device 10 controls the multiple communication devices 100. When adding a new flow to be transmitted (a new flow), the control device 10 updates the GCLs (existing GCLs) of the multiple communication devices 100 that define the transmission schedules of the existing flows to generate new GCLs, and outputs the new GCLs to each communication device 100.

[0020] Next, the configuration of the control device 10 according to this embodiment will be described. Fig. 2 is a diagram showing an example of the configuration of the control device 10 according to this embodiment.

[0021] As shown in FIG. 2 , the control device 10 according to this embodiment includes a search unit 11 , a determination unit 12 , and a generation unit 13 .

[0022] The search unit 11 searches for a time slot in which the existing flow is not allocated, which is located at a position shifted by the propagation delay from the time slot for transmitting the existing flow to each communication device 100, in the existing GCL that defines the transmission schedule of the existing flow for each of the multiple communication devices 100. Hereinafter, the time slot that is shifted by the propagation delay from the time slot for transmitting the existing flow to each communication device 100 may be referred to as a "time slot that is in the same phase as the time slot of the existing flow."

[0023] Specifically, the search unit 11 searches for an existing flow whose communication path does not overlap with the new flow's communication path, based on the existing GCLs of each of the multiple communication devices 100. Note that the search unit 11 searches for an existing flow whose communication path does not overlap with the new flow's communication path, targeting existing flows without delay fluctuation. The search unit 11 searches for a time slot that is in the same phase as the time slot of the existing flow in the existing GCL of the communication device 100 included in the non-overlapping section of the searched existing flow (a time slot shifted by the propagation delay from the time slot of the searched existing flow to each communication device 100 included in the non-overlapping section).

[0024] For example, if the communication section of the new flow does not overlap with the communication section of the existing flow, the search unit 11 determines that a non-overlapping section exists in the existing flow. Also, for example, if a part of the communication section of the new flow overlaps with the communication section of the existing flow, the search unit 11 determines that a non-overlapping section exists in the existing flow.

[0025] The search unit 11 outputs the search results for the time slot to the decision unit 12 .

[0026] The determination unit 12 determines whether or not it is possible to place a new flow in a time slot searched for by the search unit 11. Specifically, if the searched time slot is an empty time slot, the determination unit 12 determines that it is possible to place a new flow, and if another flow is assigned to the searched time slot, the determination unit 12 determines that it is not possible to place a new flow. If the determination unit 12 determines that it is possible to place a new flow, it outputs the determination result to the generation unit 13. On the other hand, if the determination unit 12 determines that it is not possible to place a new flow, it outputs the determination result to the search unit 11. If it is determined that it is not possible to place a new flow in the searched time slot, the search unit 11 searches for a new time slot.

[0027] When it is determined that the new flow can be placed in the searched time slot, the generation unit 13 generates a GCL in which the new flow is placed in the searched time slot. Specifically, the generation unit 13 generates a new GCL in which the new flow is added to the searched time slot in the existing GCL of each of the multiple communication devices 100. The generation unit 13 transmits the GCL generated for each communication device 100 to each communication device 100.

[0028] Next, the operation of the control device 10 according to this embodiment will be described. Fig. 3 is a flowchart showing an example of the operation of the control device 10 according to this embodiment, and is a diagram for explaining a control method executed by the control device 10 according to this embodiment.

[0029] The search unit 11 receives the existing GCLs of each of the communication devices 100 and parameters of the new flow. The parameters of the new flow include a communication path of the new flow. The parameters of the new flow may also include a transmission cycle of the new flow and a time slot length of the new flow.

[0030] Based on the input parameters of the existing GCL and the new flow, the search unit 11 searches, in the existing GCL of each of the plurality of communication devices, for a time slot that is in the same phase as the time slot of the existing flow and in which the existing flow is not assigned (step S11). That is, the search unit 11 searches, in the existing GCL of each of the plurality of communication devices 100, for a time slot that is shifted from the time slot of the existing flow by the propagation delay to each communication device 100 and in which the existing flow is not assigned.

[0031] Specifically, the search unit 11 searches for an existing flow in which a non-overlapping section exists within the communication path of the new flow based on the existing GCL, and then searches for a time slot in the existing GCL of the communication device 100 included in the non-overlapping section that is shifted by the propagation delay from the time slot of the existing flow to each communication device 100.

[0032] The determination unit 12 determines whether or not it is possible to allocate the new flow to the time slot searched for by the search unit 11 (step S12).

[0033] If the determination unit 12 determines that it is not possible to allocate a new flow to the searched time slot (step S12: No), the search unit 11 performs the process of step S11 again to search for a time slot.

[0034] If the determination unit 12 determines that it is possible to place a new flow in the searched time slot (step S12: Yes), the generation unit 13 generates a GCL in which the new flow is placed in the searched time slot (step S13) and transmits it to each communication device 100.

[0035] Next, an example of generating a GCL by the control device 10 according to this embodiment will be described.

[0036] 9 and 10, an example of GCL generation in the case where flow I is added as a new flow when flows A to F exist as existing flows will be described with reference to Figures 4A and 4B. Figures 4A and 4B show examples of GCLs for communication port P1 of communication device 100-1 on the communication device 100-2 side, communication port P2 of communication device 100-2 on the communication device 100-3 side, communication port P3 of communication device 100-3 on the communication device 100-4 side, and communication port P4 of communication device 100-4 on the communication device 100-5 side.

[0037] As described with reference to Figures 9 and 10, flows A, B, and F are transmitted from communication device 100-1 to communication device 100-2, flow C is transmitted from communication device 100-1 to communication device 100-3 via communication device 100-2, flow D is transmitted from communication device 100-1 to communication device 100-4 via communication device 100-2 and communication device 100-3, flow E is transmitted from communication device 100-1 to communication device 100-5 via communication device 100-2, communication device 100-3, and communication device 100-4, and flow I is transmitted from communication device 100-2 to communication device 100-5 via communication device 100-3 and communication device 100-4.

[0038] In this case, the communication paths of flow A and flow I do not overlap. That is, there is a non-overlapping section in the communication path of flow I that does not overlap with the communication path of flow A, which is an existing flow. When it is determined that a non-overlapping section exists in flow A, the search unit 11 searches for a time slot that is in the same phase as the time slot of flow A in the existing GCLs of communication devices 100-2 to 100-4 included in the non-overlapping section (the section from communication device 100-2 to communication device 100-5), as shown in FIG. 4A .

[0039] In the example shown in FIG. 4A, since no other flow is assigned to the searched time slot, the determination unit 12 determines that the new flow (flow I) can be placed in the searched time slot.

[0040] If it is determined that flow I can be placed in the searched time slot, the generation unit 13 generates a GCL in which flow I is placed in the searched time slot, as shown in FIG. 4B.

[0041] 10, time slots for new flows are allocated regardless of time slots for existing flows, so that in the existing GCLs of communication devices 100-2 to 100-4, even though there is an available time slot in the same phase as the time slot for flow A, the time slot for flow I is allocated at a position after the time slot for flow E. Therefore, as explained with reference to FIG. 11, the number of available time slots decreases, making it difficult to allocate time slots for new flows.

[0042] 4B, by adding a new flow to a time slot that is in the same phase as the time slot of an existing flow and in which no existing flow is assigned, it is possible to add a new flow at a position after the time slot of flow E. Therefore, the control device 10 according to this embodiment can increase the probability of scheduling a new flow and improve the bandwidth utilization efficiency of the network.

[0043] FIG. 5 is a diagram illustrating another example of GCL generation by the control device 10 according to the present embodiment. In FIG. 5, a new flow Z is added to a state in which multiple existing flows (existing flows O, P, and Q) with different transmission periods exist. The existing flow O is transmitted from the communication device 100-1 to the communication device 100-3 via the communication device 100-2, the existing flow P is transmitted from the communication device 100-1 to the communication device 100-4 via the communication device 100-2 and the communication device 100-3, the existing flow Q is transmitted from the communication device 100-2 to the communication device 100-3, and the new flow Z is transmitted from the communication device 100-3 to the communication device 100-5 via the communication device 100-4. Furthermore, the transmission periods of the existing flow P and the new flow Z are assumed to be the same.

[0044] The communication paths of the existing flows O and Q and the new flow Z do not overlap. Therefore, the time slot of the new flow Z can be placed in a time slot that is in the same phase as the time slots of either the existing flows O or Q. In this case, the search unit 11 searches for the existing flow O whose transmission period matches that of the new flow Z. That is, the search unit 11 searches for an existing flow that has a non-overlapping section and whose transmission period matches that of the new flow. Then, as shown in FIG. 5 , the generation unit 13 generates a GCL in which the new flow Z is added to a time slot that is in the same phase as the time slot of the searched existing flow O. In this way, it is possible to generate a GCL in which the time slot of the new flow Z is placed in the transmission period required for the new flow Z.

[0045] Furthermore, there may be existing flows with different time slot lengths among multiple existing flows. In this case, the search unit 11 searches for an existing flow whose time slot length matches that of the new flow. That is, the search unit 11 searches for an existing flow that has a non-overlapping section and whose time slot length matches that of the new flow. The generation unit 13 then generates a GCL in which the new flow is added to a time slot that is in the same phase as the time slot of the searched existing flow. In this way, it is possible to generate a GCL in which the time slot of the new flow is arranged with the time slot length required for the new flow.

[0046] 6, the communication system 1 may have a configuration in which a plurality of communication devices 100 are hierarchically connected. In the communication system 1 shown in FIG. 6, consider a case in which an existing flow R transmitted from communication device 100A to communication device 100B via communication device 100C exists, and a new flow S transmitted from communication device 100B to communication device 100G via communication device 100C, communication device 100D, communication device 100E, and communication device 100F is added.

[0047] In a configuration in which multiple communication devices 100 are hierarchically connected, such as that shown in FIG. 6 , there are no flows whose communication paths do not overlap at all between lower-level communication devices 100 connected to the same upper-level communication device 100. Even in the example shown in FIG. 6 , the communication paths of new flow S and existing flow R overlap in the section of the communication path of new flow R between communication device 100B and communication device 100C. As described above, the search unit 11 may determine that a non-overlapping section exists in existing flow R when a portion of the communication section of new flow S overlaps with the communication section of existing flow R. In the example shown in FIG. 6 , the communication path from communication device 100C to communication device 100G via communication device 100D, communication device 100E, and communication device 100F is a non-overlapping section. Therefore, the search unit 11 determines that a non-overlapping section exists in existing flow R. Then, the search unit 11 searches for a time slot in the existing GCL of the communication devices 100 (communication device 100C, communication device 100D, communication device 100E, and communication device 100F) included in the non-overlapping section that is shifted by the propagation delay from the time slot of the existing flow R to each communication device 100.

[0048] 7 is a diagram showing examples of GCLs of the communication port Pa on the communication device 100C side of the communication device 100A, the communication port Pb on the communication device 100C side of the communication device 100B, the communication port Pcl on the lower device (communication devices 100A, B) side of the communication device 100C, the communication port Pch on the upper device (communication device 100D) side of the communication device 100C, the communication port Pd on the communication device 100E side of the communication device 100D, and the communication port Pf on the communication device 100G side of the communication device 100F, all of which are shown in FIG.

[0049] The search unit 11 searches for a time slot that is in the same phase as the time slot of the existing flow R in the communication port Pch of the communication device 100C, the communication port Pd of the communication device 100D, the communication port Pe of the flow E of the communication device 100, and the communication port Pf of the communication device 100F. Since no other flows are assigned to these time slots, the generation unit 13 generates a GCL in which the new flow is placed in the searched time slot.

[0050] As described above, the control device 10 according to this embodiment includes a search unit 11, a determination unit 12, and a generation unit 13. The search unit 11 searches, in the existing GCL of each of the multiple communication devices 100, for a time slot that is located at a position shifted by the propagation delay from the time slot of the existing flow to each communication device 100 and in which no existing flow is allocated. The determination unit 12 determines whether or not it is possible to allocate a new flow to the searched time slot. If it is determined that it is possible to allocate a new flow to the searched time slot, the generation unit 13 generates a GCL in which the new flow is allocated to the searched time slot.

[0051] By adding a new flow to a time slot that is shifted by the propagation delay from the time slot of an existing flow to each communication device 100 (that is, in phase with the time slot of the existing flow) and in which no existing flow is allocated, the number of time slots in which new flows can be allocated increases when additional new flows are added. Therefore, the control device 10 according to this embodiment can increase the probability of scheduling new flows and improve the bandwidth utilization efficiency of the network.

[0052] The above-described control device 10 can be realized, for example, by a computer 401 shown in FIG. 8 . A program for causing the above-described control device 10 to function may be provided. The program may be stored in a storage medium or provided via a network. FIG. 8 is a block diagram showing a schematic configuration of a computer 401 functioning as the control device 10. Here, the computer 401 may be a general-purpose computer, a dedicated computer, a workstation, a PC (Personal Computer), an electronic notepad, or the like. The program instructions may be program code, code segments, or the like for executing necessary tasks.

[0053] 8, the computer 401 includes a processor 410, a read-only memory (ROM) 420, a random access memory (RAM) 430, a storage 440, an input unit 450, an output unit 460, and a communication interface (I / F) 470. Each component is communicably connected to one another via a bus 480. The processor 410 is specifically a central processing unit (CPU), a micro processing unit (MPU), a graphics processing unit (GPU), a digital signal processor (DSP), a system on a chip (SoC), or the like, and may be configured by multiple processors of the same type or different types.

[0054] The processor 410 is a control unit that controls each component and executes various arithmetic processing. That is, the processor 410 reads a program from the ROM 420 or the storage 440 and executes the program using the RAM 430 as a work area. The processor 410 controls each component and executes various arithmetic processing in accordance with the program stored in the ROM 420 or the storage 440. In the above-described embodiment, the program according to the present disclosure is stored in the ROM 420 or the storage 440.

[0055] The program may be stored in a storage medium readable by the computer 401. Using such a storage medium, the program can be installed in the computer 401. Here, the storage medium on which the program is stored may be a non-transitory storage medium. The non-transitory storage medium is not particularly limited, and may be, for example, a CD-ROM, a DVD-ROM, or a USB (Universal Serial Bus) memory. Furthermore, the program may be downloaded from an external device via a network.

[0056] The ROM 420 stores various programs and various frames. The RAM 430 temporarily stores programs or frames as a working area. The storage 440 is configured with a hard disk drive (HDD) or a solid state drive (SSD) and stores various programs including the operating system and various frames.

[0057] The input unit 450 includes one or more input interfaces that receive input operations from a user and acquire information based on the user operations. For example, the input unit 450 may be, but is not limited to, a pointing device, a keyboard, a mouse, or the like.

[0058] The output unit 460 includes one or more output interfaces that output information. For example, the output unit 460 may be, but is not limited to, a display that outputs information as a video or a speaker that outputs information as an audio. If the output unit 460 is a touch panel display, it also functions as the input unit 450.

[0059] The communication interface (I / F) 470 is an interface for communicating with external devices.

[0060] The following additional notes are provided regarding the above-described embodiments.

[0061] [Supplementary Item 1] A control device that controls a plurality of communication devices that transmit a plurality of flows based on a gate control list that is made up of a plurality of time slots and that defines a transmission schedule for the plurality of flows, comprising a control unit, wherein the control unit is configured to: search, in an existing gate control list that defines a transmission schedule for an existing flow for each of the plurality of communication devices, for a time slot that is located at a position shifted by an amount of propagation delay from the time slot of the existing flow to each communication device and in which the existing flow is not assigned; determine whether or not it is possible to assign a new flow to the searched time slot; and, when it is determined that it is possible to assign the new flow to the searched time slot, generate a gate control list in which the new flow is assigned to the searched time slot.

[0062] [Supplementary Item 2] In the control device described in Supplementary Item 1, the control unit searches for an existing flow in which a non-overlapping section exists within the communication path of the new flow, whose communication path does not overlap with that of the new flow, based on the existing gate control list, and searches for a time slot in an existing GCL of a communication device included in the non-overlapping section, which is shifted from the time slot of the searched existing flow by an amount of propagation delay to the communication device.

[0063] [Supplementary Item 3] In the control device according to Supplementary Item 2, the control unit searches for an existing flow that has the non-overlapping section and has a transmission period that matches that of the new flow.

[0064] [Supplementary Item 4] The control device according to Supplementary Item 2, wherein the control unit searches for an existing flow that has the non-overlapping section and has a time slot length that matches that of the new flow.

[0065] [Supplementary Item 5] In the control device according to any one of Supplementary Items 2 to 4, the control unit determines that the non-overlapping section exists in the existing flow when the communication section of the new flow does not overlap with the communication section of the existing flow, or when a portion of the communication section of the new flow overlaps with the communication section of the existing flow.

[0066] [Supplementary Item 6] A control method executed by a control device that controls a plurality of communication devices that transmit a plurality of flows based on a gate control list that is composed of a plurality of time slots and that defines a transmission schedule for the plurality of flows, the control method comprising: searching, in an existing gate control list that defines the transmission schedule for an existing flow of each of the plurality of communication devices, for a time slot that is shifted by an amount corresponding to a propagation delay from the time slot of the existing flow to each communication device and in which the existing flow is not assigned; determining whether a new flow can be assigned to the searched time slot; and if it is determined that the new flow can be assigned to the searched time slot, generating a gate control list in which the new flow is assigned to the searched time slot. All documents, patent applications, and technologies described in this specification are incorporated by reference in this specification to the same extent as if each individual document, patent application, and technology was specifically and individually indicated to be incorporated by reference.

[0067] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present disclosure. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications or alterations are possible without departing from the scope of the claims.

[0068] REFERENCE SIGNS LIST 1 Communication system 10 Control device 11 Search unit 12 Determination unit 13 Generation unit 100 Communication device 200 User device 401 Computer 410 Processor 420 ROM 430 RAM 440 Storage 450 Input unit 460 Output unit 470 Communication interface 480 Bus

Claims

1. A control device for controlling a plurality of communication devices that transmit a plurality of flows based on a gate control list that is composed of a plurality of time slots and defines a transmission schedule for the plurality of flows, the control device comprising: a search unit that searches for time slots that are shifted by a propagation delay from each communication device to the time slot of the existing flow in an existing gate control list that defines a transmission schedule for the existing flow of each of the plurality of communication devices, and that are not occupied by the existing flow; a determination unit that determines whether or not it is possible to arrange a new flow in the searched time slot; and a generation unit that generates a gate control list in which the new flow is arranged in the searched time slot when it is determined that it is possible to arrange the new flow in the searched time slot.

2. The control device according to claim 1, wherein the search unit searches for an existing flow in which there is a non-overlapping section in the communication path of the new flow that does not overlap with the communication path of the new flow based on the existing gate control list, and searches for a time slot at a position shifted by a propagation delay from the time slot of the searched existing flow to the communication device in the existing GCL of the communication device included in the non-overlapping section.

3. The control device according to claim 2, wherein the search unit searches for an existing flow that has the non-overlapping section and has the same transmission period as the new flow.

4. The control device according to claim 2, wherein the search unit searches for an existing flow that has the non-overlapping section and has the same time slot length as the new flow.

5. The control device according to claim 2, wherein the search unit determines that the non-overlapping section exists in the existing flow when the communication section of the new flow does not overlap with the communication section of the existing flow, or when a part of the communication section of the new flow overlaps with the communication section of the existing flow.

6. A control method executed by a control device that controls a plurality of communication devices that transmit a plurality of flows based on a gate control list that is composed of a plurality of time slots and defines a transmission schedule for the plurality of flows, the method comprising: searching, in an existing gate control list that defines a transmission schedule for an existing flow of each of the plurality of communication devices, for a time slot that is shifted by a propagation delay from the time slot of the existing flow to each communication device and in which the existing flow is not arranged; determining whether it is possible to arrange a new flow in the searched time slot; and generating a gate control list in which the new flow is arranged in the searched time slot when it is determined that it is possible to arrange the new flow in the searched time slot.

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