Communication device, communication system, and communication method

Abstract

A communication device (1) according to the present disclosure comprises: a frame reception unit (11) that receives a frame; a determination unit (12) that determines a user identifier and a priority traffic class; a list storage unit (15) that stores a gate control list which indicates a plurality of queues (13) each holding a frame for each user identifier and priority traffic class, respective times of a plurality of time slots, and opened / closed states each being an opened state or a closed state of a plurality of gates (14); a gate opening / closing unit (17) that controls the opened / closed states of the plurality of gates; and a frame transmission unit (18) that transmits a frame which is held in a queue (13-k) corresponding to a gate (14-k) controlled to be in the opened state, wherein at least one time slot in the gate control list is a delay guarantee period.

Description

Technical Field

[0001] The present disclosure relates to a communication device, a communication system, and a communication method.

Background Art

[0002] Conventionally, as a technology for minimizing in-device delay caused by congestion in a relay node and suppressing the occurrence of delay fluctuations, a standard called TSN (Time Sensitive Networking) has been defined. In the TAS (Time Aware Shaper) technology in the TSN standard, the occurrence of congestion is suppressed by cooperatively allocating time slots (TS: Time Slot) corresponding to priority traffic classes (for example, Cos (Class of Service) values) between nodes using a gate control list (GCL).

[0003] For example, in the example shown in FIG. 11, the period during which the TS shown in the GCL is "0" (TS "0") is set as a guard band (GB) period in which frame transmission is not started, which is provided between the best effort (BE) transmission period and the delay guarantee period. The BE transmission period is a period in which frames are transmitted with best effort. The delay guarantee period is a period in which frames received from a transmitting device by delay guarantee communication are transmitted. The GB period is a period in which the communication device does not start frame transmission. Thereby, for example, when a delay occurs in frame transmission at the TS immediately before the GB period, the transmission of the delayed frame can be terminated at TS "0" which is the GB period. Thereby, it is possible to suppress the delay generated at the TS "1" following the TS "0" due to the frames whose transmission was started at the previous TS. In FIG. 11, "o" indicates that the gate corresponding to the queue holding the frame is controlled to be in an open state. Also, "c" indicates that the gate corresponding to the queue holding the frame is controlled to be in a closed state.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2020-136777 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] However, in the above-described conventional technology, the priority traffic classes of frames received by a communication device as delay-guaranteed communication (ST (Scheduled Traffic) communication) from a plurality of transmission devices (for example, Talker) may be the same. Delay-guaranteed communication is communication in which the maximum value of the end-to-end delay of communication is determined and must be satisfied. When providing a delay guarantee as a service provider, the delay guarantee may be defined by a contract between the user and the provider of the service using the communication device. In delay-guaranteed communication, the communication device realizes the delay guarantee by transmitting a frame of a predetermined length having a predetermined priority traffic class received from the transmission device at a predetermined timing within a predetermined TS. The communication device is required to transmit the frames received from the transmission device by delay-guaranteed communication without delay.

[0006] In the GCL of the example shown in FIG. 11, it is shown that the TAS queue corresponding to the priority traffic class "7" is controlled to the open state (o) in TS "1". The open state of TS "1" and the priority traffic class "7" in the GCL is set so that the communication device transmits a frame received as delay-guaranteed communication from one of the plurality of transmission devices within the guaranteed period. Also, it is shown that the TAS queue corresponding to the priority traffic class "7" is controlled to the open state (o) in TS "3". The open state of TS "3" and the priority traffic class "7" in the GCL is set so that the communication device transmits a frame received as delay-guaranteed communication from another of the plurality of transmission devices within the guaranteed period.

[0007] In this example, if a frame of priority traffic class "7" with a certain user identifier is delayed and the communication device receives the frame in TS "3" as shown in FIG. 12, the communication device may transmit the frame in TS "3". In this case, the communication device will hold the frame in the queue until the next cycle of TS "3" without transmitting a frame of priority traffic class "7" with a user identifier different from the above-mentioned certain user identifier. As a result, the transmission of frames of priority traffic class "7" with other user identifiers will be delayed.

[0008] As described above, among a plurality of transmission devices that transmit frames to a communication device, one transmission device may delay the transmission of frames by delay-guaranteed communication by being malfunctioning or performing malicious communication. In this case, the frames received as delay-guaranteed communication from other transmission devices may be delayed.

[0009] An object of the present disclosure made in view of such circumstances is to provide a communication device, a communication system, and a communication method capable of more reliably suppressing the delay of frames transmitted by delay-guaranteed communication.

Means for Solving the Problems

[0010] To solve the above problems, a communication device according to the present disclosure includes a frame receiving unit that receives frames from a plurality of transmission devices, a user identifier for identifying a user of the transmission device that transmitted the frame, and a determination unit that determines a priority traffic class indicating the priority of the frame, a plurality of queues that respectively hold the frames for each of the user identifier and the priority traffic class, a list storage unit that stores a gate control list indicating the time of each of the plurality of time slots and an open / closed state, which is either an open state or a closed state of a plurality of gates respectively corresponding to the plurality of queues in each of the plurality of time slots, a gate opening / closing unit that controls the open / closed state of the plurality of gates based on the current time and the gate control list, and a frame transmission unit that transmits the frames held in the queue corresponding to the gate controlled to the open state in the order in which the frames are received. At least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined so that a frame received from a predetermined transmission device at a predetermined timing is transmitted within the time slot.

[0011] To solve the above problems, a communication system according to the present disclosure is a communication system including a plurality of transmission devices and a communication device that receives frames from each of the plurality of transmission devices. The communication device includes a frame reception unit that receives frames from the plurality of transmission devices, a determination unit that determines a user identifier for identifying a user of the transmission device that transmitted the frame and a priority traffic class indicating the priority of the frame, a plurality of queues that respectively hold the frames for each of the user identifier and the priority traffic class, a list storage unit that stores a gate control list indicating the time of each of the plurality of time slots and an open / closed state, which is either an open state or a closed state, of a plurality of gates respectively corresponding to the plurality of queues in each of the plurality of time slots, a gate open / close unit that controls the open / closed state of the plurality of gates based on the current time and the gate control list, and a frame transmission unit that transmits the frames held in the queue corresponding to the gate controlled to the open state in the order in which the frames were received. At least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined so that a frame received from a predetermined transmission device at a predetermined timing is transmitted within the time slot.

[0012] To solve the above problems, a communication method according to the present disclosure is a communication method executed by a communication device including a storage unit that stores a gate control list indicating the time of each of a plurality of time slots and an open / closed state, which is either an open state or a closed state of a plurality of gates respectively corresponding to the plurality of queues in each of the plurality of time slots. The communication method includes: receiving frames from a plurality of transmitting devices; determining a user identifier for identifying a user of the transmitting device that transmitted the frame and a priority traffic class indicating a priority of the frame; holding the frames in the queues respectively for each of the user identifier and the priority traffic class; controlling the open / closed states of the plurality of gates based on a current time and the gate control list; transmitting the frames held in the queues corresponding to the gates controlled to the open state in the order in which the frames were received; and at least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined so that a frame received from a predetermined transmitting device at a predetermined timing is transmitted within the time slot.

Effect of the Invention

[0013] According to the communication device, communication system, and communication method according to the present disclosure, the delay of frames transmitted by delay-guaranteed communication can be more reliably suppressed.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9A

Figure 9B

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0015] <<First Embodiment>> With reference to FIG. 1, the overall configuration of the first embodiment will be described. FIG. 1 is a schematic diagram of a communication device 1 according to the first embodiment. The communication device 1 receives frames from a plurality of other transmission devices 2 via a communication network. Further, a communication system 100 may be configured that includes a plurality of transmission devices 2 and a communication device 1 that receives frames from each of the plurality of transmission devices 2.

[0016] <Configuration of Communication Device> As shown in FIG. 1, the communication device 1 according to the first embodiment executes communication using the TAS technology in the TSN standard. The communication device 1 includes a frame reception unit 11, a determination unit 12, a plurality of TAS queues (queues) 13 (13-1 to 13-N), a plurality of TAS gates (gates) 14 (14-1 to 14-N), a list storage unit 15, a time information generation unit 16, a gate opening / closing unit 17, and a frame transmission unit 18. Here, N is the number of TAS queues 13 and also the number of TAS gates 14.

[0017] The frame reception unit 11 and the frame transmission unit 18 are constituted by a communication interface. For the communication interface, standards such as Ethernet (registered trademark), FDDI (Fiber Distributed Data Interface), Wi-Fi (registered trademark), etc. may be used. The determination unit 12, the TAS gate 14, and the gate opening / closing unit 17 are constituted by a control unit (controller). The control unit may be constituted by dedicated hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array), or may be constituted by a processor, or may be constituted including both. The TAS queue 13 is constituted by a buffer memory, and the list storage unit 15 is constituted by a memory. The buffer memory and the memory may be an HDD (Hard Disk Drive), an SSD (Solid State Drive), an EEPROM (Electrically Erasable Programmable Read-Only Memory), a ROM (Read Only Memory), a RAM (Random Access Memory), etc.

[0018] The frame reception unit 11 receives frames from a plurality of transmission devices 2.

[0019] The frame includes a user identifier for identifying the user of the transmitting device 2 that transmitted the frame. The user identifier can be, for example, a VLAN (Virtual Local Area Network) identifier for identifying the VLAN to which the transmitting device 2 used by the user belongs.

[0020] In addition, the frame includes a priority traffic class indicating the degree of priority (priority) for being preferentially transmitted by the communication device 1. The priority traffic class can be represented by, for example, a CoS (Class of Service) value.

[0021] The determination unit 12 determines a user identifier for identifying the user of the transmitting device 2 that transmitted the frame and a priority traffic class indicating the priority of the frame. The determination unit 12 inputs the frame into one of the TAS queues 13 based on the user identifier and the priority traffic class. Specifically, the determination unit 12 inputs frames with the same user identifier and priority traffic class into the same TAS queue 13.

[0022] The TAS queue 13 holds frames for each user identifier and priority traffic class. That is, the number N of the TAS queues 13 is the product of the number of user identifiers and the number of priority traffic classes. Also, the TAS queue 13 holds frames so that the order of reception can be identified.

[0023] The TAS gate 14-k (k is an integer from 1 to N) is provided corresponding to the TAS queue 13-k. The TAS gate 14 is controlled by a gate opening / closing unit 17, which will be described in detail later, to be in either an open state or a closed state (open / closed state). When the TAS gate 14 is controlled to be in the open state, it extracts the frame with the earliest reception order among the frames held in the TAS queue 13. Also, when the TAS gate 14 is controlled to be in the closed state, it does not execute processing.

[0024] The list storage unit 15 stores the GCL. As shown in FIG. 2, the GCL indicates the time of each TS (denoted as "Time" in FIG. 2). Further, the GCL indicates the open / closed state, which is either the open state or the closed state of a plurality of TAS gates 14 respectively corresponding to a plurality of TAS queues 13 at each of the plurality of TSs. In the example shown in FIG. 2, the user identifier is represented by a VLAN identifier, and "VLAN-A" and "VLAN-B" are shown as user identifiers. The same applies to the drawings shown hereinafter.

[0025] At least one of the plurality of TSs in the GCL is a delay guarantee period in which the time and the open / closed state are defined so that a frame received from a predetermined transmission device 2 at a predetermined timing is transmitted within the TS. The delay guarantee period is a period for transmitting a frame received from the transmission device 2 by delay guarantee communication. Delay guarantee communication is communication in which the maximum value of the end-to-end delay of the communication is determined and must be satisfied. When providing a delay guarantee as a service provider, the delay guarantee may be defined by a contract between the user and the provider of the service using the communication device 1 of the present embodiment. In delay guarantee communication, the communication device 1 transmits a predetermined-length frame having a predetermined user identifier and a priority traffic class received from the transmission device 2 at a predetermined timing. The communication device 1 is required to transmit the frame received from the transmission device 2 by delay guarantee communication without delay.

[0026] Also, among the TSs shown in the GCL, at least one of the TSs can be a GB period in which frame transmission is not started from any of the plurality of TAS queues 13 provided between the BE transmission period and the delay guarantee period. Further, at least one of the TSs shown in the GCL (for example, the last TS) can be a BE transmission period in which the communication device 1 transmits frames on a best-effort basis. None of the TSs shown in the GCL need to be a BE transmission period.

[0027] In the GCL of the example shown in FIG. 2, the time of TS "0" is 20 μs. Also, in TS "0", it is shown that all TAS gates 14 are controlled to the closed state (c). Further, TS "0" is provided between the GB period and the TS period. Therefore, TS "0" is the GB period.

[0028] In the GCL of the example shown in FIG. 2, the time of TS "1" is 10 μs. Also, in the GCL of the example shown in FIG. 2, within TS "1", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-A" and the priority traffic class "7" are controlled to the open state (o). Also, within TS "1", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-A" and the priority traffic classes "6" to "0" are controlled to the closed state. Also, within TS "1", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-B" and the priority traffic classes "7" to "0" are controlled to the closed state. Here, at the start time of TS "1", a frame indicating the user identifier "VLAN-A" and the priority traffic class "7" is received, and the time of TS "1" is set to a time sufficient to transmit the frame. Therefore, TS "1" is the delay guarantee period.

[0029] In the GCL of the example shown in FIG. 2, the time of TS "2" is 15 μs. Also, in the GCL of the example shown in FIG. 2, within TS "2", it is shown that the TAS gate 14 corresponding to the user identifier "VLAN-A" and the priority traffic class "6" is controlled to be in an open state. Also, within TS "2", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-A" and the priority traffic classes "7", "5" to "0" are controlled to be in a closed state. Also, within TS "2", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-B" and the priority traffic classes "7" to "0" are controlled to be in a closed state. Here, at the start time of TS "2", a frame indicating the user identifier "VLAN-A" and the priority traffic class "6" is received, and the time of TS "2" is set to a time sufficient to transmit the frame. Therefore, TS "2" is a delay guarantee period.

[0030] In the GCL of the example shown in FIG. 2, the time of TS "3" is 15 μs. Also, in the GCL of the example shown in FIG. 2, within TS "3", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-A" and the priority traffic classes "7" to "0" are controlled to be in a closed state. Also, within TS "3", it is shown that the TAS gate 14 corresponding to the user identifier "VLAN-B" and the priority traffic class "7" is controlled to be in an open state. Also, within TS "3", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-B" and the priority traffic classes "6" to "0" are controlled to be in a closed state. Here, at the start time of TS "3", a frame indicating the user identifier "VLAN-B" and the priority traffic class "7" is received, and the time of TS "3" is set to a time sufficient to transmit the frame. Therefore, TS "3" is a delay guarantee period.

[0031] In the GCL of the example shown in FIG. 2, the time of TS "4" is 100 μs. Also, in the GCL of the example shown in FIG. 2, within TS "4", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-A" and the priority traffic classes "5" to "0" are controlled to be in an open state. Also, within TS "4", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-A" and the priority traffic classes "7" and "6" are controlled to be in a closed state. Also, within TS "4", it is shown that the TAS gates 14 corresponding to the user identifier "VLAN-B" and the priority traffic classes "6" to "0" are controlled to be in an open state. Also, within TS "4", it is shown that the TAS gate 14 corresponding to the user identifier "VLAN-B" and the priority traffic class "7" is controlled to be in a closed state. Here, the frames held in the TAS queue 13 corresponding to the open TAS gate 14 are transmitted in best effort in the order in which they are received. Therefore, TS "4" is a best effort transmission period.

[0032] Note that the TS is periodically repeated. In the example shown in FIG. 2, until 20 μs has elapsed since the communication device 1 started communication control, the TS is "0", and then until 10 μs has elapsed, the TS is "1", and then until 15 μs has elapsed, the TS is "2". Further, until 15 μs has elapsed after that, the TS is "3", and then until 100 μs has elapsed, the TS is "4". After that, the TS returns to "0" and is repeated.

[0033] For this reason, if the transmission of the frame started in TS "4" does not end within TS "4", the transmission of the frame may end within TS "0", which is the GB period. Thereby, the transmission of the frame reaching up to TS "1" is suppressed, and the delay of the frame in the delay guarantee periods of TS "1" to TS "3" is suppressed.

[0034] The time information generation unit 16 is a clock indicating the current time and generates time information indicating the current time.

[0035] The gate opening / closing unit 17 acquires time information from the time information generation unit 16. Based on the current time and the GCL, the gate opening / closing unit 17 controls the opening / closing states of the plurality of TAS gates 14. Specifically, the gate opening / closing unit 17 determines a TS whose current time indicated by the time information is within the range. Then, the gate opening / closing unit 17 controls the TAS gate 14 to the opening / closing state indicated corresponding to the TS in the GCL.

[0036] In the example shown in FIG. 2, when the gate opening / closing unit 17 determines that the time is within the range of TS "0", it controls all the TAS gates 14 to the closed state.

[0037] Also, when the gate opening / closing unit 17 determines that the time is within the range of TS "1", it controls the TAS gate 14 with the user identifier "VLAN-A" and the priority traffic class "7" to the open state, controls the TAS gates 14 with the user identifier "VLAN-A" and the priority traffic classes "6" to "0" to the closed state, and controls the TAS gates 14 with the user identifier "VLAN-B" and the priority traffic classes "7" to "0" to the closed state.

[0038] Also, when the gate opening / closing unit 17 determines that the time is within the range of TS "2", it controls the TAS gate 14 with the user identifier "VLAN-A" and the priority traffic class "6" to the open state, controls the TAS gates 14 with the user identifier "VLAN-A" and the priority traffic classes "7", "5" to "0" to the closed state, and controls the TAS gates 14 with the user identifier "VLAN-B" and the priority traffic classes "7" to "0" to the closed state.

[0039] Also, when the gate opening / closing unit 17 determines that the time is within the range of TS "3", it controls the TAS gates 14 with the user identifier "VLAN-A" and the priority traffic classes "7" to "0" to the closed state, controls the TAS gate 14 with the user identifier "VLAN-B" and the priority traffic class "7" to the open state, and controls the TAS gates 14 with the user identifier "VLAN-B" and the priority traffic classes "6" to "0" to the closed state.

[0040] Also, when it is determined that the time is within the range of TS "4", the gate opening / closing unit 17 controls the TAS gates 14 of user identifier "VLAN-A" and priority traffic classes "7" and "6" to the closed state, controls the TAS gates 14 of user identifier "VLAN-A" and priority traffic classes "5" to "0" to the open state, controls the TAS gate 14 of user identifier "VLAN-B" and priority traffic class "7" to the closed state, and controls the TAS gates 14 of user identifier "VLAN-B" and priority traffic classes "6" to "0" to the open state.

[0041] The frame transmission unit 18 transmits the frames held in the TAS queue 13-k corresponding to the TAS gate 14-k controlled to the open state in the order in which the frames are received. Specifically, the frame transmission unit 18 transmits the frames extracted from the TAS queue 13-k by the TAS gate 14-k to other devices via the communication network.

[0042] As a result, as shown in FIG. 3, frames are transmitted from the TAS queue 13-k corresponding to the TAS gate 14-k of user identifier "VLAN-A" and priority traffic class "7" (Cos7 in the example of FIG. 3) within TS "1" (TS1 in the example of FIG. 3). Also, frames are transmitted from the TAS queue 13-k corresponding to the TAS gate 14-k of user identifier "VLAN-A" and priority traffic class "6" (Cos6 in the example of FIG. 3) within TS "2" (TS2 in the example of FIG. 3). In the example shown in FIG. 3, the Cos value is represented by an integer from "7" to "0", and the larger the number, the higher the priority, but it is not limited to this. Also, the cos value "i (i is an integer from 7 to 0)" is shown as "cosi". The same applies to the following drawings.

[0043] Here, for example, assume that a frame corresponding to the user identifier "VLAN-A" and the priority traffic class "7" is received late within TS "3" (in the example of FIG. 3, TS3). In this case, as shown in FIG. 2, within TS "3", the gate opening / closing unit 17 controls the TAS gate 14 for the user identifier "VLAN-A" and the priority traffic class "7" to be in a closed state, and controls the TAS gate 14 for the user identifier "VLAN-B" and the priority traffic class "7" to be in an open state. Therefore, as shown in FIG. 3, within TS "3", a frame is transmitted from the TAS queue 13-k corresponding to the TAS gate 14-k for the user identifier "VLAN-B" and the priority traffic class "7". And within TS "3", a frame is not transmitted from the TAS queue 13-k corresponding to the user identifier "VLAN-A" and the priority traffic class "7", and continues to be held in the TAS queue 13-k until the TAS gate 14-k corresponding to the TAS queue 13-k is opened in a subsequent cycle.

[0044] Note that as shown in FIG. 3, when a frame indicating the user identifier "VLAN-A" and the priority traffic class "7" is received late within TS "1", the TAS gate 14-k extracts the late-received frame from the TAS queue 13-k, and the frame transmission unit 18 transmits the frame to another device via the communication network. For this reason, the transmission of the frame may end within TS "2" immediately following TS "1". In this case, in TS "2", the start of transmission of a frame indicating the user identifier "VLAN-A" and the priority traffic class "6" is delayed. Thus, when the reception of a frame by delay-guaranteed communication is delayed within a TS, the transmission of a frame in subsequent TSs may be delayed by up to one frame.

[0045] <Operation of the communication device> Here, the operation of the communication device 1 according to the first embodiment will be described with reference to FIGS. 4A and 4B. FIGS. 4A and 4B are flowcharts showing an example of the operation of the communication device 1 according to the first embodiment. The operation in the communication device 1 described with reference to FIGS. 4A and 4B corresponds to an example of the scanning method of the communication device 1 according to the first embodiment.

[0046] First, with reference to FIG. 4A, the operation for the communication device 1 to hold a frame will be described. In this operation, the frame reception unit 11 receives frames from a plurality of transmission devices 2.

[0047] In step S11, the determination unit 12 determines whether a frame has been received by the frame reception unit 11.

[0048] If it is determined in step S11 that the frame has not been received, the determination unit 12 repeats the process of step S11 again.

[0049] If it is determined in step S11 that the frame has been received, then in step S12, the determination unit 12 determines a user identifier for identifying the user of the transmission device 2 that transmitted the frame, and a priority traffic class indicating the priority of the frame.

[0050] In step S13, the determination unit 12 causes the TAS queue 13 corresponding to the user identifier and the priority traffic class to hold the frame. As a result, the TAS queue 13 holds frames for each user identifier and priority traffic class.

[0051] In step S14, it is determined whether the communication device 1 has finished communication control. For example, it may be determined whether the communication device 1 has received an instruction indicating the end of communication control.

[0052] In step S14, when it is determined that communication control is to be terminated, the communication device 1 ends the process. In step S14, when it is determined that communication control is not to be terminated, the communication device 1 returns to step S11 to repeat the process.

[0053] Next, with reference to FIG. 4B, the operation for transmitting the frame held by the communication device 1 will be described.

[0054] In step S15, the gate opening / closing unit 17 acquires time information from the time information generation unit 16.

[0055] In step S16, the gate opening / closing unit 17 controls the opening / closing state, which is either the open state or the closed state, of the plurality of TAS gates 14 based on the current time and the GCL. Specifically, the gate opening / closing unit 17 determines the TS within the range indicated by the time information acquired from the time information generation unit 16. Then, in the GCL, the gate opening / closing unit 17 controls the TAS gate 14 to the opening / closing state corresponding to the TS. Here, at least one TS among the plurality of TSs in the GCL is a delay guarantee period in which the time and the opening / closing state of the TS are defined so that the frame received from a predetermined transmission device 2 at a predetermined timing is transmitted within the TS.

[0056] In step S17, the frame transmission unit 18 transmits the frames held in the TAS queue 13-k corresponding to the TAS gate 14-k controlled to the open state in the order in which the frames were received. Specifically, the open TAS gate 14-k extracts the frames held in the TAS queue 13-k corresponding to the TAS gate 14-k. Then, the frame transmission unit 18 transmits the frames extracted by the TAS gate 14-k.

[0057] In step S18, it is determined whether the communication device 1 ends the communication control. For example, it may be determined whether the communication device 1 has received an instruction indicating the end of the communication control.

[0058] In step S18, when it is determined that communication control is to end, the communication device 1 ends the process. In step S18, when it is determined that communication control is not to end, the communication device 1 returns to step S15 and repeats the process.

[0059] As described above, according to the first embodiment, the communication device 1 includes a plurality of TAS queues 13 that respectively hold frames for each user identifier and priority traffic class, the times of the plurality of TSs, and a list storage unit 15 that stores a GCL indicating the open / closed state, which is either the open state or the closed state, of a plurality of TAS gates 14 respectively corresponding to the plurality of TAS queues 13 in each of the plurality of TSs. Further, at least one TS among the plurality of TSs in the GCL is a delay guarantee period in which the time and open / closed state of the TS are defined so that a frame received from a predetermined transmission device 2 at a predetermined timing is transmitted within the TS. Therefore, the communication device 1 can more reliably suppress the delay of frames transmitted by delay guarantee communication. Specifically, when the reception of a frame by delay guarantee communication from one transmission device 2 is delayed, the communication device 1 can suppress the delay of frames received by delay guarantee communication from other transmission devices 2.

[0060] <<Second Embodiment>> The overall configuration of the second embodiment will be described. In the second embodiment, the same reference numerals are added to the functional parts that are the same as those in the first embodiment, and the description thereof is omitted. A communication system 100 may be configured that includes a plurality of transmission devices 2 and a communication device 1 that receives frames from each of the plurality of transmission devices 2.

[0061] <Configuration of Communication Device> The communication device 1 of the second embodiment includes, in the same manner as the first embodiment described with reference to FIG. 1, a frame reception unit 11, a determination unit 12, a plurality of TAS queues 13, a plurality of TAS gates 14, a list storage unit 15, a time information generation unit 16, a gate opening / closing unit 17, and a frame transmission unit 18.

[0062] Similar to the first embodiment, at least one of the TSs shown in the GCL stored in the list storage unit 15 is a delay guarantee period. Also, among the TSs shown in the GCL stored in the list storage unit 15, at least one of the TSs can be a GB period provided between the BE transmission period and the delay guarantee period, during which the communication device 1 does not start transmitting a frame. Further, among the TSs shown in the GCL stored in the list storage unit 15, at least one TS (for example, the last TS) can be a best effort transmission period. None of the TSs shown in the GCL need to be a BE transmission period.

[0063] Unlike the first embodiment, in the GCL stored in the list storage unit 15, the delay guarantee period is classified and defined into a transmission start permission period and a transmission start prohibition period. For the delay guarantee period in which a time sufficient to complete the transmission of a frame was set, the transmission start permission period can set a small time for which the transmission of the frame does not have to be completed, and controls the TAS gate 14 for delay guarantee communication to be in an open state. The TS between the delay guarantee period and the next delay guarantee period is a transmission start prohibition period in which the transmission of a frame is not started from any of the plurality of TAS queues 13. The frame transmission unit 18 completes the transmission of a frame for the case where the transmission of the frame has not been completed during the transmission start permission period within this transmission start prohibition period.

[0064] In the GCL of the example shown in FIG. 5, TS "1" to "2", "3" to "4", and "5" are respective delay guarantee periods. And TS "0" is the GB period provided between TS "6" which is the BE transmission period and TS "1" which is the delay guarantee period. Also, TS "1" and TS "3" are transmission start permission periods. TS "2" is a transmission start prohibition section provided between TS "1" and TS "3" which are delay guarantee periods. TS "4" is a transmission start prohibition section provided between TS "3" and TS "5" which are delay guarantee periods. Further, in TS "0", TS "2", and TS "4", it is shown that the TAS gate 14 corresponding to all user identifiers and priority traffic classes is controlled to be in a closed state.

[0065] The transmission start prohibition period can be any time equal to or less than the time required to transmit the longest frame. The transmission start permission period can be any time within a range not exceeding the requirements of the delay guarantee period. As an example, it may be set based on the maximum delay jitter that can occur in a communication network used for frame transmission and reception between the communication device 1 and the transmission device 2.

[0066] Also, the transmission start prohibition period can be the time required to transmit the longest frame. In such a configuration, although the communication efficiency decreases, it is possible to avoid affecting the TS after the transmission start prohibition period. Note that since the delay of the frame transmitted during the best effort transmission period is not guaranteed, as in the example shown in FIG. 5, the TS immediately before TS "6" which is the best effort transmission period does not have to be a transmission start prohibition period.

[0067] By configuring the GCL as described above, as shown in FIG. 6, in TS "1", the transmission of frames from the TAS queue 13 corresponding to the user identifier "VLAN-A" and the priority traffic class "7" is started. In TS "2", the start of frame transmission from all the TAS queues 13 is prohibited. In TS "3", the transmission of frames from the TAS queue 13 corresponding to the user identifier "VLAN-A" and the priority traffic class "6" is started. In TS "4", the start of frame transmission from all the TAS queues 13 is prohibited. In TS "5", the transmission of frames from the TAS queue 13 corresponding to the user identifier "VLAN-B" and the priority traffic class "7" is started.

[0068] Here, for example, assume that a frame corresponding to the user identifier "VLAN-A" and the priority traffic class "7" is received late in TS "5" (in the example of FIG. 6, TS5). In this case, as shown in FIG. 5, the TAS gate 14 for the user identifier "VLAN-A" and the priority traffic class "7" is controlled to be in a closed state, and the TAS gate 14 for the user identifier "VLAN-B" and the priority traffic class "7" is controlled to be in an open state. Therefore, as shown in FIG. 6, in TS "5", frames are transmitted from the TAS queue 13-k corresponding to the TAS gate 14-k for the user identifier "VLAN-B" and the priority traffic class "7" (Cos7 in the example of FIG. 6). And in TS "5", the frame received late is not transmitted and continues to be held in the TAS queue 13-k until the TAS gate 14-k corresponding to the TAS queue 13-k is opened in the next cycle.

[0069] Furthermore, as shown in FIG. 6, in TS "1", when a frame indicating user identifier "VLAN-A" and priority traffic class "7" (Cos7 in the example of FIG. 6) is delayed and received within TS "2", the frame is not transmitted. Then, hereinafter, the frame continues to be held in the TAS queue 13-k until the TAS gate 14-k corresponding to the TAS queue 13-k is opened. Therefore, within TS "3", a frame indicating user identifier "VLAN-A" and priority traffic class "6" (Cos6 in the example of FIG. 6) is transmitted without delay. Similarly, within TS "5", a frame indicating user identifier "VLAN-B" and priority traffic class "7" (Cos7 in the example of FIG. 6) is transmitted without delay.

[0070] Furthermore, when applying frame preemption defined in IEEE 802.1Qbu and the start of transmission of a frame held in the TAS queue 13-k where the TAS gate 14-k is open is delayed, part of the frame may be transmitted, part of it may be held in the TAS queue 13-k, and transmission may be interrupted until the TAS gate 14-k becomes open in the next cycle. Thereby, it is possible to suppress the transmission of the frame from not ending within the TS and continuing in the immediately following TS.

[0071] <Operation of the communication device> The operation of the communication device 1 according to the second embodiment is the same as the operation of the communication device 1 according to the first embodiment. However, the GCL used by the gate opening / closing unit 17 to open and close the TAS gate 14 is different.

[0072] As described above, according to the second embodiment, in the communication device 1, the TS between the delay guarantee period in the GCL and the next delay guarantee period after the delay guarantee period is a transmission start prohibition period during which frame transmission is not started from any of the plurality of TAS queues 13. Therefore, even when a frame transmitted by delay guarantee communication is received with a delay within the TS (TS1 in the example shown in FIG. 6) transmitted by the communication device 1, the communication device 1 can suppress the delay of a frame received as delay guarantee communication from another transmission device 2.

[0073] <<Third Embodiment>> With reference to FIG. 7, the overall configuration of the third embodiment will be described. FIG. 7 is a schematic diagram of a communication device 1-A according to the third embodiment. The same reference numerals are given to the functional parts identical to those in the first embodiment, and the description thereof is omitted. A communication system 100-A may be configured which includes a plurality of transmission devices 2 and a communication device 1-A that receives frames from each of the plurality of transmission devices 2.

[0074] <Configuration of Communication Device> As shown in FIG. 7, the communication device 1-A according to the third embodiment includes a frame reception unit 11, a determination unit 12, a plurality of TAS queues 13, a plurality of TAS gates 14, a list storage unit 15, a time information generation unit 16, a gate opening / closing unit 17-A, a frame transmission unit 18, a remaining time counter 19, a frame size determination unit 20, and a transmission permission determination unit 21. In the third embodiment, the GCL stored in the list storage unit 15 is the same as the GCL stored in the list storage unit 15 in the first embodiment described with reference to FIG. 2.

[0075] The gate opening / closing unit 17-A and the transmission permission determination unit 21 constitute a control unit. The remaining time counter 19 is constituted by a counter that counts time.

[0076] The remaining time counter 19 counts the remaining time until the end time of each TS based on the time information acquired from the time information generation unit 16 and the GCL.

[0077] The frame size determination unit 20 determines the frame length, which is the length of the frame held in the TAS queue 13.

[0078] The gate opening / closing unit 17-A controls the opening / closing state of the TAS gate 14 based on the current time indicated by the time information, the GCL, and the determination result by the transmission permission determination unit 21.

[0079] Specifically, first, the gate opening / closing unit 17-A determines a TS whose current time indicated by the time information is within the range.

[0080] Then, the gate opening / closing unit 17-A determines whether the TS is within the delay guarantee period. When it is determined that the TS is within the delay guarantee period, the gate opening / closing unit 17-A controls the opening / closing state of the TAS gate 14 based on the determination result of the transmission permission determination unit 21.

[0081] Specifically, the gate opening / closing unit 17-A determines whether it is indicated in the GCL that the TAS gate 14 is in an open state.

[0082] When the gate opening / closing unit 17-A determines that it is indicated in the GCL that the TAS gate 14-k is in a closed state, the gate opening / closing unit 17-A controls the TAS gate 14-k to be in a closed state.

[0083] When the gate opening / closing unit 17-A determines that it is indicated in the GCL that the TAS gate 14-k is in an open state, the transmission permission determination unit 21 determines whether the remaining time of the TS is equal to or longer than the frame transmission time.

[0084] When the transmission permission determination unit 21 determines a TAS gate 14-k that is indicated to be in an open state in the GCL by the gate opening / closing unit 17-A, the transmission permission determination unit 21 determines whether the remaining time counted by the remaining time counter 19 is equal to or longer than the frame transmission time. At this time, the transmission permission determination unit 21 may calculate the frame transmission time based on the frame length and the egress port speed. The transmission permission determination unit 21 may calculate the value obtained by dividing the frame length by the egress port speed as the frame transmission time.

[0085] When it is determined that the remaining time is equal to or greater than the frame transmission time, the gate opening / closing unit 17-A controls the TAS gate 14-k to the open state. Also, when it is determined that the remaining time is less than the frame transmission time, the gate opening / closing unit 17-A controls the TAS gate 14-k to the closed state.

[0086] As a result, as shown in FIG. 8, within TS "1", frames are transmitted from the TAS queue 13 corresponding to the user identifier "VLAN-A" and the priority traffic class "7" (Cos7 in the example of FIG. 8). Also, within TS "2", frames are transmitted from the TAS queue 13 corresponding to the user identifier "VLAN-A" and the priority traffic class "6" (Cos6 in the example of FIG. 8).

[0087] Here, for example, assume that a frame corresponding to the user identifier "VLAN-A" and the priority traffic class "7" is received late within TS "3" (TS3 in the example of FIG. 8). In this case, as shown in FIG. 2, within TS "3", the gate opening / closing unit 17-A controls the TAS gate 14 for the user identifier "VLAN-A" and the priority traffic class "7" to the closed state, and controls the TAS gate 14 for the user identifier "VLAN-B" and the priority traffic class "7" to the open state. For this reason, frames are transmitted from the TAS queue 13-k corresponding to the TAS gate 14-k for the user identifier "VLAN-B" and the priority traffic class "7". And frames are not transmitted from the TAS queue 13-k corresponding to the user identifier "VLAN-A" and the priority traffic class "7", and continue to be held in the TAS queue 13-k until the TAS gate 14-k corresponding to the TAS queue 13-k is opened in the next cycle.

[0088] Furthermore, as shown in FIG. 8, when a frame indicating user identifier "VLAN-A" and priority traffic class "7" (Cos7 in the example of FIG. 8) is received with a delay within TS "1", if it is determined that the remaining time is less than the frame transmission time, the frame is not transmitted. The frame continues to be held in TAS queue 13-k until TAS gate 14-k is controlled to the open state in the next cycle. Also, if it is determined that the remaining time is equal to or greater than the frame transmission time, the frame is transmitted. For this reason, within TS "2" immediately following TS1, a frame indicating user identifier "VLAN-A" and priority traffic class "6" starts transmission without delay, and within TS "1", the frame can be efficiently transmitted without wasting the remaining time.

[0089] Furthermore, when applying frame preemption defined in IEEE 802.1Qbu and the start of transmission of a frame held in TAS queue 13 where TAS gate 14-k is in the open state is delayed, a part of the frame may be transmitted, a part may be held in TAS queue 13, and transmission may be interrupted until TAS gate 14-k is controlled to the open state in subsequent cycles. Thereby, it is possible to suppress the situation where the transmission of the frame does not end within the TS and continues in the immediately following TS.

[0090] <Operation of Communication Device> Here, the operation of communication device 1-A according to the third embodiment will be described with reference to FIGS. 9A and 9B. FIGS. 9A and 9B are sequence diagrams showing an example of the operation of communication device 1-A according to the third embodiment. The operation in communication device 1-A described with reference to FIGS. 9A and 9B corresponds to an example of the scanning method of communication device 1-A according to the third embodiment.

[0091] First, with reference to FIG. 9A, the operation for communication device 1-A to hold a frame will be described.

[0092] The communication device 1-A executes the processes from step S21 to step S24. The processes from step S21 to step S24 are the same as the processes from step S11 to step S14 in the first embodiment.

[0093] Next, with reference to FIG. 9B, the operation for transmitting the frame held by the communication device 1-A will be described.

[0094] In step S25, the gate opening / closing unit 17-A acquires time information from the time information generation unit 16.

[0095] In step S26, the gate opening / closing unit 17-A determines whether the TAS queue 13-k is indicated as being in an open state with a TS whose current time is within the range in the GCL.

[0096] If it is determined in step S26 that the TAS queue 13-k is indicated as being in a closed state in the GCL, then in step S27, the gate opening / closing unit 17-A controls the TAS gate 14-k to be in a closed state.

[0097] If it is determined in step S26 that the TAS queue 13-k is indicated as being in an open state in the GCL, then in step S28, the transmission permission determination unit 21 determines whether the remaining time of the TS counted by the remaining time counter 19 is equal to or greater than the transmission time of the frame.

[0098] If it is determined in step S28 that the remaining time of the TS is less than the transmission time of the frame, then in step S27, the gate opening / closing unit 17-A controls the TAS gate 14-k to be in a closed state.

[0099] If it is determined in step S28 that the remaining time of the TS is equal to or greater than the transmission time of the frame, then in step S29, the gate opening / closing unit 17-A controls the TAS gate 14-k to be in an open state.

[0100] In step S30, it is determined whether or not the communication device 1-A has finished communication control. For example, it may be determined whether or not a command indicating that the communication device 1-A has finished communication control has been received.

[0101] If it is determined in step S30 that communication control has ended, the communication device 1-A ends the process. If it is determined in step S30 that communication control has not ended, the communication device 1-A returns to step S25 and repeats the process.

[0102] As described above, according to the third embodiment, the communication device 1-A further includes a frame size determination unit 20 that determines the frame length, which is the length of the frame held in the TAS queue 13-k, and a transmission availability determination unit 21 that determines whether or not the remaining time of the TS including the current time is equal to or longer than the transmission time of the frame based on the frame length. Further, when it is determined that the remaining time is equal to or longer than the transmission time, the gate opening / closing unit 17-A controls the TAS gate 14-k corresponding to the TAS queue 13-k in which the frame is held to be in an open state, and when it is determined that the remaining time is less than the transmission time, the gate opening / closing unit 17-A controls the TAS gate 14-k to be in a closed state. Thereby, even when a frame transmitted by delay-guaranteed communication is received with a delay within the TS transmitted by the communication device 1-A, the communication device 1-A can suppress the delay of a frame received as delay-guaranteed communication from another transmission device 2. Moreover, the communication device 1-A can transmit frames efficiently.

[0103] <Program> The above-described communication devices 1 and 1-A can be realized by a computer 101. Also, a program for causing the communication devices 1 and 1-A to function may be provided. Further, the program may be stored in a storage medium or provided through a network. FIG. 10 is a block diagram showing a schematic configuration of a computer 101 that functions as the communication devices 1 and 1-A, respectively. Here, the computer 101 may be a general-purpose computer, a dedicated computer, a workstation, a PC (Personal Computer), an electronic notebook, or the like. The program instructions may be program codes, code segments, etc. for executing necessary tasks.

[0104] As shown in FIG. 10, the computer 101 includes a processor 110, a ROM (Read Only Memory) 120, a RAM (Random Access Memory) 130, a storage 140, an input unit 150, a display unit 160, and a communication interface (I / F) 170. Each component is connected to be communicable with each other via a bus 180. Specifically, the processor 110 is a CPU (Central Processing Unit), MPU (Micro Processing Unit), GPU (Graphics Processing Unit), DSP (Digital Signal Processor), SoC (System on a Chip), or the like, and may be composed of a plurality of processors of the same or different types.

[0105] The processor 110 controls each component and executes various arithmetic processes. That is, the processor 110 reads a program from the ROM 120 or the storage 140 and executes the program using the RAM 130 as a work area. The processor 110 performs control of each of the above components and various arithmetic processes according to the program stored in the ROM 120 or the storage 140. In the above-described embodiment, the program according to the present disclosure is stored in the ROM 120 or the storage 140.

[0106] The program may be stored in a storage medium readable by the computer 101. By using such a storage medium, it is possible to install the program on the computer 101. Here, the storage medium storing the program 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, a USB (Universal Serial Bus) memory, or the like. Further, the program may be in a form downloaded from an external device via a network.

[0107] The ROM 120 stores various programs and various data. The RAM 130 temporarily stores a program or data as a working area. The storage 140 is composed of an HDD (Hard Disk Drive) or an SSD (Solid State Drive), and stores various programs and various data including an operating system.

[0108] The input unit 150 includes one or more input interfaces that receive a user's input operation and acquire information based on the user's operation. For example, the input unit 150 is a pointing device, a keyboard, a mouse, etc., but is not limited thereto.

[0109] The display unit 160 includes one or more output interfaces that output information. For example, the display unit 160 is a display that outputs information as video, or a speaker that outputs information as audio, but is not limited thereto. Note that when the display unit 160 is a touch panel type display, it also functions as the input unit 150.

[0110] The communication interface (I / F) 170 is an interface for communicating with an external device.

[0111] Regarding the above embodiments, the following additional remarks are further disclosed.

[0112] (Additional Clause 1) A communication interface that receives frames from a plurality of transmitting devices, A control unit that determines a user identifier for identifying a user of the transmitting device that transmitted the frame and a priority traffic class indicating the priority of the frame, A buffer memory that holds the frames for each of the user identifier and the priority traffic class, A memory that stores a gate control list indicating the time of each of a plurality of time slots and the open / closed state, which is either the open state or the closed state of a plurality of gates respectively corresponding to the plurality of queues, in each of the plurality of time slots, The control unit further controls the open / closed state of the plurality of gates based on the current time and the gate control list, The communication interface transmits the frames held in the queue corresponding to the gate controlled to the open state in the order in which the frames were received, A communication device in which at least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined such that a frame received from a predetermined transmitting device at a predetermined timing is transmitted within the time slot. (Additional clause 2) The communication device according to additional clause 1, wherein, in the gate control list, a time slot between the delay guarantee period and the next delay guarantee period is a transmission start prohibition period in which frame transmission is not started from any of the plurality of queues. (Additional clause 3) The control unit further, Determines the frame length, which is the length of the frame held in the queue, Determines whether the remaining time of the time slot including the current time is equal to or greater than the transmission time of the frame based on the frame length, When it is determined that the remaining time is equal to or longer than the transmission time, the gate corresponding to the queue in which the frame is held is controlled to be in an open state, and when it is determined that the remaining time is shorter than the transmission time, the gate is controlled to be in a closed state. The communication device according to claim 1. (Additional claim 4) A communication system including a plurality of transmission devices and a communication device that receives frames from each of the plurality of transmission devices, The communication device includes: A communication interface that receives frames from a plurality of transmission devices; A control unit that determines a user identifier for identifying a user of the transmission device that transmitted the frame and a priority traffic class indicating the priority of the frame; A buffer memory that holds the frames for each of the user identifier and the priority traffic class; A memory that stores a gate control list indicating the time of each of a plurality of time slots and an open / closed state, which is either an open state or a closed state of a plurality of gates respectively corresponding to the plurality of queues in each of the plurality of time slots; The control unit further controls the open / closed states of the plurality of gates based on the current time and the gate control list; The communication interface transmits the frames held in the queue corresponding to the gate controlled to be in the open state in the order in which the frames are received; At least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined so that a frame received from a predetermined transmission device at a predetermined timing is transmitted within the time slot. The communication system. (Additional claim 5) A communication method executed by a communication device including a storage unit that stores a gate control list indicating the time for each of a plurality of time slots and the open / closed state, which is either the open state or the closed state, of a plurality of gates respectively corresponding to the plurality of queues in each of the plurality of time slots, comprising: receiving frames from a plurality of transmission devices; determining a user identifier for identifying a user of the transmission device that transmitted the frame and a priority traffic class indicating the priority of the frame; holding the frames in the queues respectively for each of the user identifier and the priority traffic class; controlling the open / closed states of the plurality of gates based on the current time and the gate control list; transmitting the frames held in the queues corresponding to the gates controlled to the open state in the order in which the frames were received; and at least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined such that a frame received from a predetermined transmission device at a predetermined timing is transmitted within the time slot.

[0113] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

[0114] The above-described embodiments have been described as representative examples, but it will be apparent to those skilled in the art that many changes 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 changes are possible without departing from the scope of the claims. For example, it is possible to combine a plurality of constituent blocks described in the configuration diagrams of the embodiments into one, or to divide one constituent block.

Explanation of Symbols

[0115] 1, 1-A Communication Device 2 Transmitter 11 Frame Receiver 12 Determination Unit 13, 13-k TAS Queue (Queue) 14, 14-k TAS Gate (Gate) 15 List Storage Unit 16 Time Information Generation Unit 17, 17-A Gate Opening / Closing Unit 18 Frame Transmitter 19 Remaining Time Counter 20 Frame Size Determination Unit 21 Transmission Permissibility Determination Unit 100, 100-A Communication System 101 Computer 110 Processor 120 ROM 130 RAM 140 Storage 150 Input Unit 160 Output Unit 170 Communication Interface 180 Bus

Claims

1. A frame receiving unit that receives frames from a plurality of transmission devices, A determination unit that determines a user identifier for identifying a user of the transmission device that transmitted the frame and a priority traffic class indicating the priority of the frame, A plurality of queues that respectively hold the frames for each of the user identifier and the priority traffic class, A list storage unit that stores a gate control list indicating the time of each of a plurality of time slots and the open / closed state, which is either the open state or the closed state of a plurality of gates respectively corresponding to the plurality of queues in each of the plurality of time slots, A gate opening / closing unit that controls the open / closed state of the plurality of gates based on the current time and the gate control list, A frame transmission unit that transmits the frames held in the queue corresponding to the gate controlled to the open state in the order in which the frames were received, and comprising, At least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined such that a frame received from a predetermined transmission device at a predetermined timing is transmitted within the time slot, The gate control list indicates the open / closed state of the plurality of gates corresponding to the plurality of queues provided for each of the user identifier and the priority traffic class, and the time slot that is the delay guarantee period is set to a different time slot for each user identifier. A communication device.

2. In the gate control list, a time slot between the delay guarantee period and the next delay guarantee period is a transmission start prohibition period in which frame transmission is not started from any of the plurality of queues. The communication device according to claim 1.

3. A frame size determination unit that determines the frame length of the frame held in the queue, A transmission permission determination unit that determines whether the remaining time of the time slot including the current time is equal to or greater than the transmission time of the frame based on the frame length, and further includes: The gate opening / closing unit controls the gate corresponding to the queue in which the frame is held to be in an open state when it is determined that the remaining time is equal to or greater than the transmission time, and controls the gate to be in a closed state when it is determined that the remaining time is less than the transmission time. The communication device according to claim 1.

4. A communication system including a plurality of transmission devices and a communication device that receives frames from each of the plurality of transmission devices, The communication device is, A frame reception unit that receives frames from a plurality of transmission devices, A determination unit that determines a user identifier for identifying the user of the transmission device that transmitted the frame and a priority traffic class indicating the priority of the frame, A plurality of queues that respectively hold the frames for each of the user identifier and the priority traffic class, A list storage unit that stores a gate control list indicating the time of each of the plurality of time slots and the open / closed state, which is either the open state or the closed state, of the plurality of gates respectively corresponding to the plurality of queues in each of the plurality of time slots, A gate opening / closing unit that controls the open / closed state of the plurality of gates based on the current time and the gate control list, A frame transmission unit that transmits the frames held in the queue corresponding to the gate controlled to be in the open state in the order in which the frames are received, and includes: At least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined such that a frame received from a predetermined transmission device at a predetermined timing is transmitted within the time slot. The gate control list indicates the open / closed states of the plurality of gates corresponding to the plurality of queues provided for each of the user identifier and the priority traffic class. The time slot that is the delay guarantee period is set to a different time slot for each user identifier. A communication system.

5. A communication method executed by a communication device including a storage unit that stores a gate control list indicating the time of each of a plurality of time slots and an open / closed state that is either an open state or a closed state of a plurality of gates respectively corresponding to a plurality of queues in each of the plurality of time slots, the method comprising: Receiving frames from a plurality of transmission devices; Determining a user identifier for identifying the user of the transmission device that transmitted the frame and a priority traffic class indicating the priority of the frame; Holding the frames in the queues for each of the user identifier and the priority traffic class; Controlling the open / closed states of the plurality of gates based on the current time and the gate control list; Transmitting the frames held in the queue corresponding to the gate controlled to the open state in the order in which the frames were received, At least one of the plurality of time slots in the gate control list is a delay guarantee period in which the time and the open / closed state are defined such that a frame received from a predetermined transmission device at a predetermined timing is transmitted within the time slot. The gate control list indicates the open / closed states of the plurality of gates corresponding to the plurality of queues provided for each of the user identifier and the priority traffic class, and the time slot serving as the delay guarantee period is a communication method set to different time slots for each user identifier.

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