Communication device and control device

Abstract

A communication device (30) comprises: a port; a storage unit (32) that stores a gate control list for each pattern of communication paths that can be switched and used in a communication network; and a control unit (31) that refers to a gate control list having been stored in the storage unit (32) and corresponding to a pattern of a communication path being used in the communication network, controls queuing of a flow and transmission from the port, and, upon detecting switching of the communication path in the communication network, replaces the gate control list being referred to with a gate control list having been stored in the storage unit (32) prior to the switching and corresponding to the pattern of the communication path after the switching.

Description

Communication and control devices

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

[0002] Patent Document 1 discloses a control device that designs a GCL. "GCL" is an abbreviation for gate control list.

[0003] Non-Patent Document 1 defines TAS. "TAS" is an abbreviation for time aware shaper. Non-Patent Document 2 evaluates the influence of the number of flows and the accommodation rate on the TAS schedule calculation.

[0004] WO 2023 / 238410

[0005] IEEE Computer Society, IEEE Std 802.1Qbv-2015, IEEE Standard for Local and metropolitan area networks -- Bridges and Bridged Networks - Amendment 25: Enhancements for Scheduled Traffic, March 18, 2016. Yuhei Kawakami and five others, "On the Impact of Accommodated Traffic on TAS Scheduling," 2024 IEICE General Conference, March 2024, B-6-66

[0006] By constructing a network with multiple nodes with TAS functionality, it is possible to realize a network function that guarantees maximum delay and maximum jitter, i.e., deterministic delay communication. In this case, it is necessary to assign time slots dedicated to deterministic delay communication to the egress ports of all nodes that pass through end-to-end.

[0007] The mechanism of TAS is shown in Figure 15. TAS performs priority control by determining the traffic to be transmitted according to a time-shared schedule. Specifically, TAS stores frames in FIFO queues for each VLAN-CoS or IP-ToS, and allows transmission from queues whose gates are open according to the GCL. "VLAN" is an abbreviation for virtual local area network. "CoS" is an abbreviation for class of service. "IP" is an abbreviation for Internet Protocol. "ToS" is an abbreviation for type of service. "FIFO" is an abbreviation for first in, first out.

[0008] An example of a GCL is shown in Figure 16. TAS can control best-effort traffic and delay-guaranteed communication by superimposing them together. In the example shown in Figure 16, four ST flows and one NST flow are multiplexed. "ST" is an abbreviation for scheduled traffic. "NST" is an abbreviation for non-scheduled traffic. ST flows correspond to delay-guaranteed communication. NST flows correspond to non-guaranteed communication, i.e., best-effort traffic. The GCL shown in Figure 16 specifies that STs with CoS "7" are permitted in timeslots 1 and 3, STs with CoS "5" in timeslot 2, STs with CoS "4" in timeslot 4, and NSTs with CoS "3" or less are permitted in timeslot 5. This GCL further specifies that the duration for which communication is permitted in each of timeslots 1 through 4 is 15 microseconds, and the duration for which communication is permitted in timeslot 5 is 100 microseconds.

[0009] To avoid collisions end-to-end, all nodes in the network must be time-synchronized and the timing of opening and closing the GCL gates at each node must be coordinated. The GCL is either centrally managed by a controller called a CNC, or managed individually at each node. "CNC" stands for centralized network configuration. Each node opens its gate taking propagation delays into account, preventing collisions with other communications and enabling communication without queuing delays. The transmitting terminal is also time-synchronized and periodically transmits frames in accordance with the GCL timing, enabling communication without queuing delays.

[0010] An example of GCL management by a CNC is shown in Figure 17. In the figure, "NW" is the network, and "TAS-SW" is a node with TAS functionality. TAS-SW controls communications according to the GCL, achieving delay-guaranteed communications. A CNC is installed as a controller that centralizes control of TAS-SWs across the entire network. TAS-SWs have an OperControlList as the GCL they are currently using. To update the GCL they are currently using, the CNC has the function of issuing a new GCL, an AdminControlList, to the TAS-SW and updating the configuration. The TAS-SW updates the OperControlList with the AdminControlList. A TAS-SW has only one OperControlList.

[0011] In the example shown in Figure 17, when updating the GCL, the GCL must be calculated and created in the CNC or a separate calculation tool, and then issued from the CNC to the TAS-SW as an AdminControlList. If a route switch is required due to a network failure, the failure is detected and the route switch is performed. After normal communication is restored, the GCL must be changed to match the new route for TAS communication. The following steps are required to restore TAS communication, and recovery takes time. Step 1: The TAS-SW detects the failure. Step 2: The TAS-SW switches the route. Step 3: The TAS-SW notifies the CNC of the new route. Step 4: The CNC calculates the GCL. Step 5: The CNC issues the AdminControlList. Step 6: The TAS-SW updates the OperControlList. That is, since a GCL calculation is performed for the new route after the route is switched, it takes time to restore the TAS communication.

[0012] The present disclosure has been made in view of the above circumstances, and aims to speed up the restoration of periodic communications such as TAS communications when a communication path switch occurs in a communications network.

[0013] A communication device according to one embodiment is a communication device that builds a communication network with other communication devices, and includes: a memory unit that stores gate control lists that define a port, a plurality of time slots, and a flow with a fixed transmission period that passes through the port in each time slot, for each pattern of communication paths that can be switched and used in the communication network; and a control unit that controls queuing of the flow and sending it out from the port by referring to the gate control list stored in the memory unit that corresponds to the pattern of communication paths currently in use in the communication network, and that, when a switch of a communication path in the communication network is detected, changes the gate control list to be referenced to a gate control list that has been stored in the memory unit since before the switch and that corresponds to the pattern of the communication path after the switch.

[0014] A control device according to one embodiment is a control device that sets multiple time slots for each port of multiple communication devices, and includes: a communication unit that communicates with the multiple communication devices; a memory unit that stores gate control lists that define the multiple time slots and a flow with a fixed transmission period that passes through the corresponding port in each time slot, for each pattern of communication paths that can be switched and used in a communication network constructed by the multiple communication devices; and a control unit that transmits the gate control lists stored in the memory unit that correspond to the patterns of communication paths currently in use in the communication network via the communication unit to a communication device having the corresponding port, and that, upon detecting a switch in a communication path in the communication network, transmits the gate control list that corresponds to the pattern of the communication path after the switch, which has been stored in the memory unit since before the switch, via the communication unit to a communication device having the corresponding port.

[0015] According to the present disclosure, when a communication path switch occurs in a communication network, periodic communication such as TAS communication can be quickly restored.

[0016] 1 is a diagram illustrating a configuration of a communication system according to a first embodiment. FIG. 2 is a block diagram illustrating a configuration of a control device according to the first embodiment. FIG. 3 is a block diagram illustrating a configuration of a communication device according to the first embodiment. FIG. 4 is a diagram illustrating an example of a pattern of a communication path before switching. FIG. 5 is a diagram illustrating an example of a pattern of a communication path after switching. FIG. 6 is a flowchart illustrating the operation of a communication device according to the first embodiment. FIG. 7 is a block diagram illustrating a configuration of another communication device according to a second embodiment. FIG. 8 is a diagram illustrating an example of a pattern of a communication path before switching. FIG. 9 is a diagram illustrating an example of a pattern of a communication path after switching. FIG. 10 is a diagram illustrating an example of a GCL change instruction. FIG. 11 is a block diagram illustrating a configuration of a control device according to a fourth embodiment. FIG. 12 is a block diagram illustrating a configuration of a communication device according to the fourth embodiment. FIG. 13 is a flowchart illustrating the operation of a communication device according to the fourth embodiment. FIG. 14 is a flowchart illustrating the operation of a control device according to the fourth embodiment. FIG. 15 is a diagram illustrating the mechanism of TAS. FIG. 16 is a table illustrating an example of a GCL. FIG. 17 is a diagram illustrating an example of GCL management by a CNC.

[0017] Hereinafter, several embodiments will be described with reference to the drawings.

[0018] In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of each embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0019] The configuration of a communication system 10 according to the first embodiment will be described with reference to FIG.

[0020] The communication system 10 includes a control device 20 and a plurality of communication devices 30. The control device 20 and each communication device 30 are connected by a control communication network and can communicate with each other via the control communication network. The plurality of communication devices 30 form a communication network 11, which is a main signal communication network, and can transfer frames between any user terminals via the communication network 11.

[0021] The control device 20 is a computer that monitors and controls each communication device 30. Each communication device 30 accommodates a user and forwards frames to a port designated for each destination user terminal. The number of communication devices 30 is not limited to four as shown in FIG. 1, but may be two, three, five or more. In this embodiment, the control device 20 functions as a CNC, and each communication device 30 functions as a TAS-SW. Each user terminal is, for example, a terminal such as a mobile device or a PC, or a server such as a cloud server. "PC" is an abbreviation for personal computer. Each user terminal can be either the start point or the end point of a flow.

[0022] An outline of this embodiment will be described with reference to FIG.

[0023] Each communication device 30 performs TAS communication in accordance with the GCL. Each communication device 30 has n OperControlLists, OperControlList_1...n, where n is an integer greater than or equal to 2. That is, each communication device 30 stores multiple GCLs in advance. When each communication device 30 detects a failure in the communication network 11, it changes the current communication path to a new communication path that avoids the failure. Each communication device 30 selects a GCL that is suitable for the new communication path from the multiple GCLs it stores. Each communication device 30 changes the GCL to be applied to the selected GCL. Therefore, according to this embodiment, TAS communication can be restored when the communication network 11 fails without having to perform GCL calculations each time.

[0024] The configuration of the control device 20 according to this embodiment will be described with reference to FIG.

[0025] The control device 20 includes a control unit 21 , a storage unit 22 , and a communication unit 23 .

[0026] The control unit 21 includes at least one processor, at least one programmable circuit, at least one dedicated circuit, or any combination thereof. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for specific processing. "CPU" is an abbreviation for central processing unit. "GPU" is an abbreviation for graphics processing unit. An example of the programmable circuit is an FPGA. "FPGA" is an abbreviation for field-programmable gate array. An example of the dedicated circuit is an ASIC. "ASIC" is an abbreviation for application specific integrated circuit. The control unit 21 controls each part of the control unit 20 and executes processing related to the operation of the control unit 20.

[0027] The storage unit 22 includes at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or any combination thereof. The semiconductor memory is, for example, a RAM, a ROM, or a flash memory. "RAM" is an abbreviation for random access memory. "ROM" is an abbreviation for read only memory. RAM is, for example, an SRAM or a DRAM. "SRAM" is an abbreviation for static random access memory. "DRAM" is an abbreviation for dynamic random access memory. ROM is, for example, an EEPROM. "EEPROM" is an abbreviation for electrically erasable programmable read only memory. Flash memory is, for example, an SSD. "SSD" is an abbreviation for solid-state drive. Magnetic memory is, for example, an HDD. "HDD" is an abbreviation for hard disk drive. The storage unit 22 functions, for example, as a main storage device, an auxiliary storage device, or a cache memory. The storage unit 22 stores information used in the operation of the control device 20 and information obtained by the operation of the control device 20 .

[0028] The communication unit 23 includes at least one communication module. The communication module is, for example, a module that complies with a LAN communication standard such as Ethernet (registered trademark). The communication unit 23 communicates with each communication device 30. The communication unit 23 receives information used in the operation of the control device 20 and transmits information obtained by the operation of the control device 20.

[0029] The functions of the control device 20 are realized by executing a control program according to this embodiment on a processor serving as the control unit 21. That is, the functions of the control device 20 are realized by software. The control program causes a computer to execute the operations of the control device 20, thereby causing the computer to function as the control device 20. That is, the computer functions as the control device 20 by executing the operations of the control device 20 in accordance with the control program.

[0030] The program can be stored on a non-transitory computer-readable medium. Examples of the non-transitory computer-readable medium include flash memory, magnetic recording devices, optical disks, magneto-optical recording media, and ROMs. The program can be distributed by selling, transferring, or lending portable media such as SD cards, DVDs, or CD-ROMs that store the program. "SD" is an abbreviation for Secure Digital. "DVD" is an abbreviation for digital versatile disc. "CD-ROM" is an abbreviation for compact disc read only memory. The program can also be distributed by storing it in the storage of a server and transferring it from the server to another computer. The program can also be provided as a program product.

[0031] A computer temporarily stores a program stored on a portable medium or transferred from a server in its main storage device. The computer then reads the program stored in the main storage device with its processor and executes processing in accordance with the read program. The computer may also read the program directly from the portable medium and execute processing in accordance with the program. The computer may also execute processing in accordance with the received program each time a program is transferred from the server to the computer. Processing may also be executed using a so-called ASP-type service that realizes functions simply by issuing execution instructions and obtaining results, without transferring the program from the server to the computer. "ASP" is an abbreviation for application service provider. A program is information used for processing by a computer and includes something equivalent to a program. For example, data that is not a direct instruction to a computer but has properties that define computer processing falls under the category of "something equivalent to a program."

[0032] Some or all of the functions of the control device 20 may be implemented by a programmable circuit or a dedicated circuit as the control unit 21. In other words, some or all of the functions of the control device 20 may be implemented by hardware.

[0033] The network administrator lists communication path patterns that are assumed to occur in the event of a failure, and calculates GCLs for all patterns in advance. Alternatively, the control unit 21 may automatically calculate GCLs for all patterns in advance. The storage unit 22 stores GCLs corresponding to the n communication path patterns created in this way for each port of each communication device 30 as multi-GCLs 12. The control unit 21 has a GCL selection function 24 that selects multiple GCLs corresponding to each port of each communication device 30 from the multi-GCLs 12 stored in the storage unit 22.

[0034] The control unit 21 has a GCL issuing function 25 that generates GCL information 13 that indicates multiple GCLs selected by the GCL selecting function 24 as AdminControlList_1...n. The communication unit 23 transmits the GCL information 13 generated by the GCL issuing function 25 to a communication device 30 that has a corresponding port.

[0035] The configuration of each communication device 30 according to this embodiment will be described with reference to FIG.

[0036] The communication device 30 includes a control unit 31, a storage unit 32, and a plurality of ports such as a control signal receiving port 33, a main signal receiving port 34, and a main signal transmitting port 35.

[0037] The control unit 31 includes at least one processor, at least one programmable circuit, at least one dedicated circuit, or any combination thereof. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for a specific process. The programmable circuit is, for example, an FPGA. The dedicated circuit is, for example, an ASIC. The control unit 31 controls each part of the communication device 30 and executes processes related to the operation of the communication device 30.

[0038] The storage unit 32 includes at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or any combination thereof. The semiconductor memory is, for example, a RAM, a ROM, or a flash memory. The RAM is, for example, an SRAM or a DRAM. The ROM is, for example, an EEPROM. The flash memory is, for example, an SSD. The magnetic memory is, for example, an HDD. The storage unit 32 functions as, for example, a main storage device, an auxiliary storage device, or a cache memory. The storage unit 32 stores information used in the operation of the communication device 30 and information obtained by the operation of the communication device 30.

[0039] Each port is provided with or connected to at least one communication module. The communication module is, for example, a module compatible with a LAN communication standard such as Ethernet (registered trademark). The control signal receiving port 33 is a port for receiving a control signal transmitted from the control device 20 via the control communication network. The main signal receiving port 34 is a port for receiving a main signal transmitted from another communication device 30 via the communication network 11, which is the main signal communication network. The main signal transmitting port 35 is a port for transmitting the main signal received at the main signal receiving port 34 to another communication device 30 via the communication network 11, which is the main signal communication network.

[0040] The functions of the communication device 30 are realized by executing a communication program according to this embodiment on a processor serving as the control unit 31. That is, the functions of the communication device 30 are realized by software. The communication program causes a computer to execute the operations of the communication device 30, thereby causing the computer to function as the communication device 30. That is, the computer functions as the communication device 30 by executing the operations of the communication device 30 in accordance with the communication program.

[0041] Some or all of the functions of the communication device 30 may be realized by a programmable circuit or a dedicated circuit as the control unit 31. In other words, some or all of the functions of the communication device 30 may be realized by hardware.

[0042] The control unit 31 has a GCL processing function 36 that, when the GCL information 13, which is a control signal transmitted from the control device 20, is received at the control signal receiving port 33, stores in the storage unit 32 a multi-GCL 14 including, as an Operator Control List_1...n, multiple GCLs indicated as AdminControlList_1...n in the GCL information 13. The GCL processing function 36 includes a function to select a GCL corresponding to the pattern of the communication path currently in operation from the multi-GCL 14 stored in the storage unit 32. The GCL processing function 36 includes a function to uniquely determine the communication path pattern based only on the input / output pattern of the flow. For example, as shown in FIG. 4, assume that a pattern P101 using the current path is in operation between two communication devices 30 out of a current path and a backup path. In either communication device 30, the control unit 31 can recognize that the current path is being used, so the GCL processing function 36 determines that pattern P101 is in operation and selects the GCL corresponding to pattern P101.

[0043] The control unit 31 has a TAS function 37 that opens and closes a gate when an ST flow frame, which is a main signal transmitted from another communication device 30, is received at the main signal receiving port 34, so that the ST flow frame is transmitted from the main signal transmitting port 35 to the other communication device 30 in a specified time slot according to the GCL selected by the GCL processing function 36.

[0044] The control unit 31 has a failure detection function 38 that detects a failure in a communication path. The failure detection function 38 includes a function to switch the communication path when a failure is detected.

[0045] The GCL processing function 36 further includes a function of selecting a GCL corresponding to the communication path pattern after switching by the failure detection function 38 from the multi-GCL 14 stored in the storage unit 32, i.e., a function of updating the GCL in operation. The GCL processing function 36 also includes a function of uniquely determining the communication path pattern based solely on the input / output pattern of the flow, even when a failure is detected by the failure detection function 38. For example, as shown in FIG. 5 , assume that a failure in the active path causes switching to the standby path, and pattern P102 using the standby path becomes active. In both communication devices 30, the control unit 31 can recognize that the standby path is being used, so the GCL processing function 36 determines that pattern P102 is active and updates the active GCL to the GCL corresponding to pattern P102.

[0046] As described above, in this embodiment, the communication device 30 can have multiple GCLs calculated in advance. In the event of a network failure, route switching is performed using any network route switching protocol. When route switching is complete, the communication device 30 selects a GCL from the multiple GCLs that matches the pattern of the communication route after route switching and switches the OperControlList, thereby enabling TAS communication to be restored without communicating with the control device 20 or performing GCL calculations. Therefore, according to this embodiment, route switching can be performed immediately in the event of a network failure without performing GCL calculations.

[0047] The operation of each communication device 30 according to this embodiment will be described with reference to Fig. 6. The operation described below corresponds to the communication method according to this embodiment. That is, the communication method according to this embodiment includes at least steps S101 to S105 shown in Fig. 6.

[0048] Before S101, it is assumed that the memory unit 22 of the control device 20 stores, for each pattern of communication paths that can be switched and used in the communication network 11, a GCL that defines a plurality of time slots and a flow of a fixed transmission period that passes through the corresponding main signal transmission port 35 in each time slot. It is also assumed that the control unit 21 of the control device 20 transmits, via the GCL issuing function 25, the GCL corresponding to each communication path pattern stored in the memory unit 22 as GCL information 13 to the communication device 30 having the corresponding main signal transmission port 35 via the communication unit 23.

[0049] In S101, the control unit 31 of the communication device 30 receives the GCL information 13 transmitted from the control device 20 via the control signal receiving port 33. In S102, the control unit 31 of the communication device 30 causes the GCL processing function 36 to store the GCLs corresponding to each communication path pattern received as the GCL information 13 in S101 in the storage unit 32 as the multi-GCL 14. In S103, the control unit 31 of the communication device 30 controls the queuing of flows and transmission from the main signal transmitting port 35 by referring to the GCLs corresponding to the communication path patterns currently in use in the communication network 11 stored in the storage unit 32 using the TAS function 37. In S104, the control unit 31 of the communication device 30 determines, using the fault detection function 38, whether a communication path switch in the communication network 11 has occurred. If it is determined that a switch has not occurred, step S103 is executed again. If it is determined that a switch has occurred, that is, if a switch has been detected, in S105, the control unit 31 of the communication device 30 changes the GCL to be referenced to the GCL that corresponds to the pattern of the communication path after the switch, which has been stored in the storage unit 32 since before the switch, using the GCL processing function 36. After S105, step S103 is executed again.

[0050] As described above, in this embodiment, OperControlList_1...n is a GCL that can be applied at any time and is always maintained during operation. The control device 20 can update the OperControlList_1...n of the communication device 30 by issuing AdminControlList_1...n to the communication device 30. The control device 20 or a calculation tool calculates GCLs for all communication path patterns in advance, and the communication device 30 holds n GCLs as OperControlList_1...n. This allows the communication device 30 to apply a GCL corresponding to the communication path pattern after switching and restore TAS communication without performing GCL calculations or communicating with the control device 20 in the event of a failure. Each communication device 30 can determine the communication path pattern based on its own flow input and output. According to this embodiment, the following steps are all that are required to restore TAS communication, and restoration does not require much time. Step 1: TAS-SW detects a failure. Step 2: TAS-SW switches the route. Step 3: TAS-SW changes the Operator Control List based on the selection from the multi-GCL 14.

[0051] A second embodiment, which is a modification of the first embodiment, will be described below.

[0052] In this embodiment, a representative device that determines the communication path is included among the multiple communication devices 30. The representative device issues a GCL change instruction along with a communication path change instruction, and causes the remaining communication devices 30 to change the GCL, thereby automatically restoring TAS communication throughout the entire communication network 11.

[0053] The configuration of the communication device 40, which is the representative device according to this embodiment, will be described with reference to FIG.

[0054] The communication device 40 includes a control unit 41, a storage unit 42, and a plurality of ports such as a control signal receiving port 43, a main signal receiving port 44, and a main signal transmitting port 45. The configurations of the control unit 41, the storage unit 42, and each port are similar to those of the control unit 31, the storage unit 32, and each port of the communication device 30, except for the functions of the control unit 41, and therefore will not be described here.

[0055] The control unit 41 has a GCL processing function 46, a TAS function 47, and a failure detection function 48 that are similar to the GCL processing function 36, the TAS function 47, and the failure detection function 48 that the control unit 31 of the communication device 30 has, respectively.

[0056] The control unit 41 has a GCL change instruction function 49 that instructs other communication devices 30 to change the GCL when a failure is detected by the failure detection function 48. For example, as shown in FIG. 8, assume that two communication devices 30 are connected to one communication device 40, and two or more communication devices 30 are connected to the other communication devices 40. Assume that a pattern P201 is in operation using a route from the communication device 40 that passes through at least three communication devices 30. Then, as shown in FIG. 9, assume that a failure in part of the route causes switching from the communication device 40 to a detour route that passes through at least three communication devices 30 with a partially different combination, and that a pattern P202 using the detour route is now in operation. The control unit 41 selects the detour route and switches to the detour route using the failure detection function 48. When the switching to the detour route is completed, as shown in FIG. 10, the control unit 41 broadcasts an instruction signal indicating the detour route pattern or an OperControlList corresponding to the detour route pattern to each communication device 30 using the GCL change instruction function 49.

[0057] In this embodiment, the failure detection function 38 of the control unit 31 of each communication device 30 includes a function of detecting a failure in the communication path by receiving an instruction signal transmitted from the communication device 40. The GCL processing function 36 of the control unit 31 of each communication device 30 includes a function of selecting, in accordance with the instruction signal, a GCL corresponding to the pattern of the communication path after switching by the communication device 40 from the multi-GCL 14 stored in the storage unit 32, i.e., a function of updating the GCL in operation. In the example shown in Figures 9 and 10, the control unit 31 changes the GCL in operation from the GCL corresponding to pattern P201 to the GCL corresponding to pattern P202 by the GCL processing function 36 in accordance with the instruction signal.

[0058] As described above, in this embodiment, even if the network scale is large and each communication device 30 cannot uniquely determine the communication path pattern based only on the flow input / output pattern, information on the communication path pattern can be acquired from the communication device 40. In other words, the communication device 40 instructs each communication device 30 on the Operator Control List or communication path pattern to be applied, thereby enabling each communication device 30 to select a GCL according to the current communication path pattern.

[0059] 6 , in this embodiment, the control unit 31 of each communication device 40 detects a change in the communication path in the communication network 11 by receiving a notification from another device of the communication path pattern after the change or a GCL corresponding to the communication path pattern after the change. In this embodiment, the "other device" is the communication device 40, but it may also be the control device 20. In other words, information on the communication path pattern may be shared from the control device 20 through the control communication network instead of from the communication device 40 through the main signal communication network.

[0060] A third embodiment, which is another modification of the first embodiment, will be described below. The same modifications as those made from the first embodiment to the third embodiment may be applied to the second embodiment.

[0061] In this embodiment, when a network failure occurs, each communication device 30 acquires information regarding the timing of GCL switching and simultaneously changes the GCL, thereby restoring TAS communication in cooperation across the entire network.

[0062] In this embodiment, in step S105 shown in FIG. 6 , the control unit 31 of each communication device 40 receives an instruction from another device regarding the timing to change the GCL it references to a GCL corresponding to the pattern of the communication path after switching. The "other device" may be any of the communication devices 30 or the control device 20. For example, the control device 20 may share the timing of the GCL switching through the control communication network, or any of the communication devices 30 may share the timing of the GCL switching by broadcasting a control frame through the main signaling network. According to this embodiment, by synchronizing the timing of the GCL switching, TAS communication can be restored with little frame loss.

[0063] A fourth embodiment, which is yet another modification of the first embodiment, will be described below. The same modifications as those made from the first embodiment to the fourth embodiment may be applied to the second or third embodiment.

[0064] In this embodiment, instead of each communication device 30 having a GCL corresponding to the patterns of all communication routes, in the event of a network failure, the communication device 30 receives a GCL issued as an AdminControlList from the control device 20. The control device 20 holds GCLs corresponding to the patterns of all communication routes that have been calculated in advance. In the event of a network failure, the control device 20 issues a GCL corresponding to the pattern of the communication route after switching as an AdminControlList.

[0065] The configuration of the control device 20 according to this embodiment will be described with reference to Fig. 11. However, the description of the same parts as those shown in Fig. 2 will be omitted.

[0066] When a failure occurs, the communication unit 23 receives communication path information 15 indicating the changed communication path from each communication device 30 that has changed its communication path. The control unit 21 has a communication path determination function 26 that refers to the communication path information 15 and determines the pattern of the communication path currently in operation.

[0067] In this embodiment, the GCL selection function 24 of the control unit 21 includes a function of selecting only a GCL corresponding to the pattern of the communication path currently in operation, rather than multiple GCLs, from the multi-GCL 12 stored in the storage unit 22. The GCL issuance function 25 of the control unit 21 includes a function of generating GCL information 13 that indicates the GCL selected by the GCL selection function 24 as an AdminControlList. The communication unit 23 transmits the GCL information 13 generated by the GCL issuance function 25 to the communication device 30 having the corresponding port.

[0068] The configuration of each communication device 30 according to this embodiment will be described with reference to Fig. 12. However, the description of parts that are the same as those in the configuration shown in Fig. 3 will be omitted.

[0069] The plurality of ports of the communication device 30 includes a control signal transmission port 39. The control signal transmission port 39 is a port for transmitting the communication path information 15 to the control device 20 via the control communication network.

[0070] In this embodiment, the fault detection function 38 possessed by the control unit 31 not only has the function of switching the communication path when a fault is detected, but also has the function of transmitting communication path information 15 indicating the changed communication path from the control signal transmission port 39 to the control device 20.

[0071] In this embodiment, the GCL processing function 36 of the control unit 31 includes a function of storing the GCL 16 indicated as the AdminControlList in the GCL information 13 as the OperControlList in the storage unit 32 when the GCL information 13, which is a control signal transmitted from the control device 20, is received at the control signal receiving port 33. The GCL processing function 36 further includes a function of overwriting and saving the GCL 16 indicated as the AdminControlList in the new GCL information 13 as the OperControlList in the storage unit 32 when new GCL information 13 is received at the control signal receiving port 33 in the event of a failure, i.e., a function of updating the GCL 16 stored in the storage unit 32 to one corresponding to the pattern of the communication path after switching by the failure detection function 38.

[0072] The operation of each communication device 30 according to this embodiment will be described with reference to Fig. 13. The operation described below corresponds to the communication method according to this embodiment. That is, the communication method according to this embodiment includes at least steps S111 to S115 shown in Fig. 13.

[0073] Before S111, it is assumed that the memory unit 22 of the control device 20 stores, for each pattern of communication paths that can be switched and used in the communication network 11, a GCL that defines a plurality of time slots and a flow of a fixed transmission period that passes through the corresponding main signal transmission port 35 in each time slot. It is also assumed that the control unit 21 of the control device 20 transmits, via the GCL issuing function 25, the GCL 16 that corresponds to the pattern of communication paths currently in use in the communication network 11 and that is stored in the memory unit 22, as GCL information 13 to the communication device 30 that has the corresponding main signal transmission port 35, via the communication unit 23.

[0074] In S111, the control unit 31 of the communication device 30 receives the GCL information 13 transmitted from the control device 20 via the control signal receiving port 33. In S112, the control unit 31 of the communication device 30 causes the GCL processing function 36 to store in the memory unit 32 the GCL 16 corresponding to the pattern of the communication path currently being used in the communication network 11, which was received as the GCL information 13 in S111. In S113, the control unit 31 of the communication device 30 controls the queuing of the flow and the transmission from the main signal transmitting port 35 by referring to the GCL 16 corresponding to the pattern of the communication path currently being used in the communication network 11, which is stored in the memory unit 32, via the TAS function 37. In S114, the control unit 31 of the communication device 30 checks whether new GCL information 13 transmitted from the control device 20 has been received via the control signal receiving port 33. If new GCL information 13 has not been received, step S113 is executed again. When new GCL information 13 is received, in S115, the control unit 31 of the communication device 30 causes the GCL processing function 36 to store the GCL corresponding to the pattern of the communication path after switching, received as the new GCL information 13, in the storage unit 32 as the GCL 16 corresponding to the pattern of the communication path currently being used in the communication network 11. After S115, step S113 is executed again.

[0075] The operation of the control device 20 according to this embodiment will be described with reference to Fig. 14. The operation described below corresponds to the control method according to this embodiment. That is, the control method according to this embodiment includes at least steps S201 to S203 shown in Fig. 14.

[0076] In S201, the control unit 21 of the control device 20 determines whether a switch of the communication path has occurred in the communication network 11. If it is determined that a switch has not occurred, step S201 is executed again. If it is determined that a switch has occurred, i.e., if a switch has been detected, in S202, the control unit 21 of the control device 20 causes the GCL issuing function 25 to transmit, via the communication unit 23, a GCL corresponding to the pattern of the communication path after the switch, which has been stored in the memory unit 22 since before the switch, to the communication device 30 having the corresponding main signal transmission port 35, as new GCL information 13. After S203, step S201 is executed again.

[0077] According to this embodiment, compared to the first, second, and third embodiments, each communication device 40 does not need to have multiple GCLs, and the implementation of the communication device 30 is simplified. In this embodiment, the following steps are required until TAS communication is restored, but since there is no need to perform GCL calculations for the new route after route switching, the time required to restore TAS communication can be reduced accordingly. Step 1: TAS-SW detects a failure. Step 2: TAS-SW switches the route. Step 3: TAS-SW notifies the CNC of the new route. Step 4: CNC issues an AdminControlList. Step 5: TAS-SW updates the OperControlList.

[0078] The present disclosure is not limited to the above-described embodiments. For example, two or more blocks shown in the block diagram may be integrated, or one block may be divided. Two or more steps shown in the flowchart may be executed in parallel or in a different order, instead of being executed in chronological order as described, depending on the processing capabilities of the device executing each step, or as needed. Other modifications are possible within the scope of the present disclosure.

[0079] REFERENCE SIGNS LIST 10 Communication system 11 Communication network 12, 14 Multi-GCL 13 GCL information 15 Communication path information 16 GCL 20 Control device 21, 31, 41 Control unit 22, 32, 42 Storage unit 23 Communication unit 24 GCL selection function 25 GCL issuing function 26 Communication path determination function 30, 40 Communication device 33, 43 Control signal receiving port 34, 44 Main signal receiving port 35, 45 Main signal transmitting port 36, 46 GCL processing function 37, 47 TAS function 38, 48 Fault detection function 39 Control signal transmitting port 49 GCL change instruction function

Claims

1. A communication device that builds a communication network with other communication devices, comprising: a memory unit that stores a port, a gate control list that defines a plurality of time slots and a flow with a fixed transmission period that passes through the port in each time slot, for each pattern of communication paths that can be switched and used in the communication network; and a control unit that controls queuing of the flow and sending it out from the port by referring to the gate control list stored in the memory unit that corresponds to the pattern of communication paths currently in use in the communication network, and when it detects a switch of a communication path in the communication network, changes the gate control list it refers to to a gate control list that has been stored in the memory unit since before the switch and that corresponds to the pattern of the communication path after the switch.

2. The communication device according to claim 1, wherein the control unit detects the switching by being notified by another device of the pattern of the communication path after the switching or a gate control list corresponding to the pattern of the communication path after the switching.

3. A communication device according to claim 1 or claim 2, wherein the control unit is instructed by another device as to the timing for changing the gate control list to be referenced to a gate control list corresponding to the pattern of the communication path after the switching.

4. A control device that sets multiple time slots for each port of multiple communication devices, comprising: a communication unit that communicates with the multiple communication devices; a memory unit that stores gate control lists that define the multiple time slots and a flow with a fixed transmission period that passes through the corresponding port in each time slot, for each pattern of communication paths that can be switched and used in a communication network constructed by the multiple communication devices; and a control unit that transmits the gate control lists stored in the memory unit that correspond to the patterns of communication paths currently in use in the communication network to communication devices having the corresponding ports via the communication unit, and that, when a switch of a communication path in the communication network is detected, transmits the gate control list that corresponds to the pattern of the communication path after the switch, which has been stored in the memory unit since before the switch, to the communication devices having the corresponding ports via the communication unit.

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