Control device

Abstract

A control device (20) comprises a communication unit (23) that communicates with a plurality of communication devices, and a control unit (21) that: acquires path information (52) defining, as respective paths, two or more combinations of an active route which passes through a port of at least one communication device among the plurality of communication devices and a reserve route which passes through a port of a communication device different from the active route among the plurality of communication devices, and defining the priority of each of the paths as a class; and, on the basis of the acquired path information (52), sets, via the communication unit (23), a time slot in which only flows of limited classes including a flow of a corresponding class pass to a port through which the active route of each of the paths passes, and sets a time slot in which the flow of the limited class and flows of another one or more classes pass to a port through which the reserve route of each of the paths passes.

Description

control device

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

[0002] Non-Patent Document 1 defines TAS. "TAS" is an abbreviation for time aware shaper.

[0003] 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, 2016-03-18

[0004] 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.

[0005] The mechanism of TAS is shown in Figure 9. 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 with open gates 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. "GCL" is an abbreviation for gate control list.

[0006] An example of a GCL is shown in Figure 10. TAS can control the overlapping of best-effort traffic and delay-guaranteed communication. In the example shown in Figure 10, 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 10 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.

[0007] 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.

[0008] In a redundant configuration such as 1+1 protection, frames are transmitted over both the active and standby paths. When implementing deterministic communication, it is conceivable to allocate dedicated time slots for deterministic communication to the egress ports of all nodes passing through both paths end-to-end. However, under normal conditions, traffic on the standby path occupies bandwidth even though it is not required, resulting in reduced bandwidth utilization.

[0009] The purpose of the present disclosure, which has been made in view of such circumstances, is to improve bandwidth utilization efficiency.

[0010] 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; and a control unit that defines, as a path, two or more combinations of a current route that passes through a port of at least one of the multiple communication devices and a backup route that passes through a port of a communication device of the multiple communication devices that is different from the current route, and acquires path information that defines the priority of each path as a class, and based on the acquired path information, sets, via the communication unit, time slots that allow only flows of a limited class, including flows of a corresponding class, to pass through ports passed through the current route of each path, and sets time slots that allow flows of the limited class and flows of one or more other classes to pass through ports passed through the backup route of each path.

[0011] According to the present disclosure, bandwidth utilization efficiency is improved.

[0012] 1 is a block diagram showing the configuration of a communication system according to an embodiment; FIG. 2 is a block diagram showing the configuration of a control device provided in the communication system; FIG. 3 is a table showing an example of path information; FIG. 4 is a table showing an example of time slot information; FIG. 5 is a table showing an example of setting information; FIG. 6 is a flowchart showing the operation of the control device; FIG. 7 is a flowchart showing the operation of the control device; FIG. 8 is a diagram showing the mechanism of TAS; FIG. 9 is a table showing an example of GCL;

[0013] An embodiment will be described below with reference to the drawings.

[0014] In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0015] The configuration of a communication system 10 according to this embodiment will be described with reference to FIG.

[0016] The communication system 10 includes a control device 20 and a plurality of communication devices such as communication devices 31, 32, 33, and 34. The control device 20 and each communication device are connected by a monitoring and control network 11 and can communicate with each other via the monitoring and control network 11. The plurality of communication devices form a communication network 12, and frames can be transferred between any of user locations such as user locations 41, 42, 43, and 44 via the communication network 12.

[0017] The control device 20 is a computer that monitors and controls each communication device. Each communication device accommodates a user and forwards frames to a port designated for each destination user location. The number of communication devices is four in this embodiment, but it may be two, three, five or more. Each user location 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 location can be either the start point or the end point of a flow.

[0018] In this embodiment, port 31A of communication device 31 is connected to user base 41. Port 32A of communication device 32 is connected to user base 42. Port 33A of communication device 33 is connected to user base 43. Port 34A of communication device 34 is connected to user base 44. Port 31B of communication device 31 is connected to port 34B of communication device 34. Port 32B of communication device 32 is connected to port 33B of communication device 33. Port 31C of communication device 31 is connected to port 32C of communication device 32. Port 33C of communication device 33 is connected to port 34C of communication device 34.

[0019] An outline of this embodiment will be described with reference to FIG.

[0020] The control device 20 sets a normal route and a backup route for each path for deterministic delay communication in the communication network 12. The control device 20 assigns time slots to each transmission port of each communication device for these routes. Of the normal route and backup route, the control device 20 sets the time slot for an operational route so that only specific flows can use it, and for an inoperative route, sets the time slot so that any flow can use it. Therefore, according to this embodiment, the bandwidth of the backup route for deterministic delay communication can be effectively utilized.

[0021] 1 , the control device 20 sets, for example, a path X between the communication devices 32 and 34 and a path Y between the communication devices 31 and 33. If the direction from the communication device 32 toward the communication device 34 is defined as an upstream direction, the path X includes, in the upstream direction, a working path X1 passing through the port 32B of the communication device 32 and the port 33C of the communication device 33, and a backup path X2 passing through the port 32C of the communication device 32 and the port 31B of the communication device 31. If the direction from the communication device 33 toward the communication device 31 is defined as an upstream direction, the path Y includes, in the upstream direction, a working path Y1 passing through the port 33B of the communication device 33 and the port 32C of the communication device 32, and a backup path Y2 passing through the port 33C of the communication device 33 and the port 34B of the communication device 34.

[0022] In this embodiment, the control device 20 monitors the state of the communication network 12 through the monitoring and control network 11. The control device 20 holds information about the time slots of both paths for all paths in the redundant configuration. Under normal conditions, the control device 20 does not reserve time slots exclusively for communication with a fixed delay for the backup path, but instead sets time slots for each communication device through the monitoring and control network 11 so that they can also be used by other users or other classes. Therefore, according to this embodiment, the bandwidth of the backup path can be effectively used depending on the network state.

[0023] In this embodiment, when the control device 20 detects a failure occurring in the communication network 12 through the monitoring and control network 11, it updates the time slots of the communication devices included in the range affected by the failure of the communication network 12 so that they cannot be used by other users or other classes through the monitoring and control network 11. In other words, in the event of an abnormality, the control device 20 reserves a time slot dedicated to communication with a deterministic delay for the backup path. According to this embodiment, the time for which the quality of communication with a deterministic delay is degraded can be reduced.

[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. 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 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 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 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 storage unit 22 stores the connection status of each communication device as network information 51. The control unit 21 has a path design function 24 that selects an arbitrary pair of communication devices according to the connection status of the network information 51, and calculates paths between the selected communication devices, including a working route and a backup route.

[0034] The storage unit 22 stores the paths calculated by the path design function 24 as path information 52. The control unit 21 has a time slot design function 25 that calculates time slots to be assigned to the transmission ports of each communication device according to the paths in the path information 52.

[0035] The storage unit 22 stores the time slots calculated by the time slot design function 25 as time slot information 53. The time slot information 53 includes time slot settings corresponding to the working route and the backup route of the path. The control unit 21 has a path setting function 26 that changes the time slot setting dedicated to communication with confirmed delays for the backup route to a time slot setting that can be used for any flow. The communication unit 23 has an output unit 28 that outputs the time slot setting that reflects the change made by the path setting function 26 to each communication device as setting information 54.

[0036] As described above, the control device 20 can change the priority in accordance with the state of the communication network 12 through the monitoring and control network 11. Therefore, according to this embodiment, the bandwidth utilization rate is improved.

[0037] The communication unit 23 has an input unit 29 that receives an alarm generated in a communication device as alarm information 55 via the monitoring and control network 11. The control unit 21 has a network status monitoring function 27 that determines, from the alarm information 55, a path in the path information 52 where a communication failure has occurred and switches the path where the communication failure has occurred. The path setting function 26 changes the setting of a time slot dedicated to deterministic delay communication for the working route of the path where the communication failure has occurred to a time slot that can be used for any flow. In this embodiment, the path setting function 26 does not change the setting of a time slot that can be used for any flow for the backup route of the path where the communication failure has occurred, but may change it to a time slot dedicated to deterministic delay communication. The output unit 28 outputs the time slot setting that reflects the change made by the path setting function 26 to each communication device as setting information 54.

[0038] When the input unit 29 receives a recovery alarm for the communication network 12 as alarm information 55 via the monitoring and control network 11, the network status monitoring function 27 restores the route switching for the path in which the communication failure occurred. The path setting function 26 restores the time slot settings for the working route of the path in which the communication failure occurred. The path setting function 26 also restores the time slot settings for the backup route of the path in which the communication failure occurred, if the time slot settings had been changed. The output unit 28 outputs the time slot settings reflecting the changes made by the path setting function 26 to each communication device as setting information 54.

[0039] According to this embodiment, since there is no need to calculate time slots when switching routes, the change in time slot settings can be reflected immediately. Bandwidth can be effectively utilized for sections where no communication failure occurs at the source of the switch, improving bandwidth utilization efficiency.

[0040] An example of the path information 52 is shown in FIG. 3. In this example, the path information 52 includes columns such as "Path ID," "VLAN ID," "TC," "Route 1," "Route 2," and "Operational Status." "Path ID" is a path identifier and corresponds to a flow identifier. "VLAN ID" is a VLAN identifier. "TC" is a CoS. "Route 1" is a working route when the "Operational Status" is "1," and a backup route when the "Operational Status" is "2." "Route 2" is a working route when the "Operational Status" is "2," and a backup route when the "Operational Status" is "1." "Route 1" and "Route 2" are set for the upstream and downstream directions, respectively.

[0041] An example of the time slot information 53 is shown in FIG. 4. In this example, the time slot information 53 includes columns such as CoS "7" to "0," "Time," "Path ID," and "Route." Each CoS is set to either "O" or "C" for each time slot. "O" indicates open, i.e., the time slot can be used for the corresponding CoS. "C" indicates closed, i.e., the time slot cannot be used for the corresponding CoS. "Time" indicates the length of time communication is permitted in each time slot. "Path ID" corresponds to the "Path ID" in the path information 52. "Route" indicates whether each time slot belongs to "Route 1" or "Route 2" in the path information 52. The time slot information 53 shown in FIG. 4 is created for port 33C of the communication device 33. The time slot information 53 is created on a port-by-port basis.

[0042] An example of the setting information 54 is shown in FIG. 5. In this example, the setting information 54 includes columns for each CoS from "7" to "0" and for "Time." Each column corresponds to a column with the same name in the time slot information 53. An example of an inactive route in the path information 52 is "Route 2" with a "Path ID" of "Y." Therefore, the corresponding time slot "i+1" is set in the time slot information 53 to be usable only for CoS "6." However, in the setting information 54, this is changed so that it can be used for any other CoS, specifically, any of CoS "7" to "0." The setting information 54 shown in FIG. 5 is created for port 33C of the communication device 33. The setting information 54 is created on a port-by-port basis.

[0043] The operation of the control device 20 according to this embodiment will be described with reference to Fig. 6. 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 S101 to S105 shown in Fig. 6.

[0044] In S101, the control unit 21 uses the path design function 24 to calculate a path connecting any user bases from the network information 51 and path information 52 stored in the storage unit 22. A backup route included in the path is calculated so as to be orthogonal to a working route included in the same path, i.e., so as not to pass through the same port of the same communication device. In S102, the control unit 21 adds the path calculated in S101 to the path information 52 stored in the storage unit 22. In S103, the control unit 21 uses the time slot design function 25 to calculate a time slot for the path added in S102 from the path information 52 and time slot information 53 stored in the storage unit 22. In S104, the control unit 21 adds the time slot calculated in S103 to the time slot information 53 stored in the storage unit 22. In S105, the control unit 21 changes the settings using the path setting function 26 so that the time slots that were added in S104 and are not in operation, i.e., the time slots for the backup path, can also be used by other classes, and outputs the changed settings from the output unit 28 as setting information 54.

[0045] As described above, in this embodiment, the control unit 21 acquires path information 52 and, based on the acquired path information 52, sets multiple time slots for each port of multiple communication devices via the communication unit 23. The path information 52 is information that defines two or more combinations of a working route and a backup route as paths and defines the priority of each path as a class. The working route is a route that passes through a port of at least one communication device among the multiple communication devices. The backup route is a route that passes through a port of a communication device that is different from the working route among the multiple communication devices. Based on the acquired path information 52, the control unit 21 sets, via the communication unit 23, time slots that allow only flows of a limited class, including flows of a corresponding class, to pass through ports passed through the working route of each path. For example, the above-mentioned limited class flows include only flows of the corresponding class. Based on the acquired path information 52, the control unit 21 sets, via the communication unit 23, time slots that allow flows of the above-mentioned limited class and flows of one or more other classes to pass through ports passed through the backup route of each path. For example, the control unit 21 sets a time slot for passing a flow of an arbitrary class to a port passed through on a backup route of each path.

[0046] 3, the path information 52 includes information that a combination of route 1 passing through port 32B of the communication device 32 and port 33C of the communication device 33 and route 2 passing through port 32C of the communication device 32 and port 31B of the communication device 31 is path X, and that the CoS of path X is "7." The path information 52 also includes information that route 1 of path X is the active route and route 2 of path X is the standby route. In the example shown in FIG. 4, the time slot information 53 includes information that the "i"-th time slot of multiple time slots assigned to port 33C of the communication device 33, which is passed through route 1 of path X, allows only flows with a CoS of "7," the same as the CoS of path X, to pass. Since route 1 of path X is the active route, in the example shown in FIG. 5, the setting information 54 includes the same information as the time slot information 53 for the "i"-th time slot of multiple time slots assigned to port 33C of the communication device 33.

[0047] 3, the path information 52 includes information that a combination of route 1 passing through port 33B of the communication device 33 and port 32C of the communication device 32 and route 2 passing through port 33C of the communication device 33 and port 34B of the communication device 34 is path Y, and that the CoS of path Y is "6." The path information 52 also includes information that route 1 of path Y is the active route and route 2 of path Y is the backup route. In the example shown in FIG. 4, the time slot information 53 includes information that the "i+1"-th time slot of the multiple time slots assigned to port 33C of the communication device 33, which is passed through route 2 of path Y, allows only flows with a CoS of "6," the same as the CoS of path Y, to pass. Because route 2 of path Y is the backup route, in the example shown in FIG. 5, the setting information 54 includes information that is different from the time slot information 53 for the "i+1"-th time slot of the multiple time slots assigned to port 33C of the communication device 33. Specifically, the setting information 54 includes information that the "i+1"-th time slot among the multiple time slots assigned to the port 33C of the communication device 33 passes not only a flow with a CoS of "6" that is the same as the CoS of the path Y, but also other flows with a CoS of "7" and "5" or less. In other words, the setting information 54 includes information that the "i+1"-th time slot among the multiple time slots assigned to the port 33C of the communication device 33 passes a flow with an arbitrary CoS.

[0048] The operation of the control device 20 according to this embodiment will be further described with reference to Fig. 7. The operation described below also corresponds to the control method according to this embodiment. That is, the control method according to this embodiment may further include steps S111 to S114 shown in Fig. 7.

[0049] When a failure occurs and the input unit 29 receives alarm information 55, in S111 the control unit 21 detects the occurrence of the failure using the network status monitoring function 27. In S112, the control unit 21 identifies the failed link using the network status monitoring function 27. In S113, the control unit 21 extracts the relevant path from the path information 52 stored in the storage unit 22 and switches the active route. In S114, the control unit 21 changes the settings using the path setting function 26 so that time slots that are not in operation, i.e., time slots for the route from which the switch was made, can also be used for other classes, and outputs the changed settings from the output unit 28 as setting information 54.

[0050] As described above, in this embodiment, when the control unit 21 detects a failure in the working route of any of the paths, it switches that path to the backup route and sets, via the communication unit 23, a time slot through which flows of a limited class and flows of one or more other classes can pass, at a port passed through the working route before the path is switched. For example, the control unit 21 sets a time slot through which flows of any class can pass, at a port passed through the working route before the path is switched.

[0051] The operation of the control device 20 according to this embodiment will be further described with reference to Fig. 8. The operation described below also corresponds to the control method according to this embodiment. That is, the control method according to this embodiment may further include steps S121 to S124 shown in Fig. 8.

[0052] Upon recovery, when the input unit 29 receives alarm information 55, in S121 the control unit 21 detects the recovery using the network status monitoring function 27. In S122, the control unit 21 uses the network status monitoring function 27 to identify the restored link, i.e., the link that has recovered from the failure. In S123, the control unit 21 extracts the relevant path from the path information 52 stored in the memory unit 22 and switches back the active path. In S124, the control unit 21 uses the path setting function 26 to change the setting of the time slots that are not in an active state, i.e., the time slots for the path to be switched back to, to be dedicated to confirmed delay communication, and outputs the changed setting from the output unit 28 as setting information 54.

[0053] The following additional notes are provided regarding the above-described embodiments.

[0054] (Supplementary Item 1) 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; and a control unit that acquires path information that defines, as a path, each of two or more combinations of a current route that passes through a port of at least one of the multiple communication devices and a backup route that passes through a port of one of the multiple communication devices that is different from the current route, and defines the priority of each path as a class, and based on the acquired path information, sets, via the communication unit, time slots that allow only flows of a limited class to pass, including flows of a corresponding class, to ports passed through the current route of each path, and sets time slots that allow flows of the limited class and flows of one or more other classes to ports passed through the backup route of each path. (Supplementary Item 2) The control device according to Supplementary Item 1, wherein the control unit sets time slots that allow flows of any class to pass, to ports passed through the backup route of each path. (Supplementary Item 3) The control device according to Supplementary Item 1 or Supplementary Item 2, wherein the control unit sets time slots that allow flows of any class to pass, to ports passed through the backup route of each path. (Supplementary Item 4) A control device described in any one of Supplementary Items 1 to 3, wherein when the control unit detects a failure in the current route of any of the paths, it switches that path to the backup route, and sets, via the communication unit, a time slot that allows flows of the limited class and flows of one or more other classes to pass through a port that is passed through the current route before the path is switched.

[0055] 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.

[0056] REFERENCE SIGNS LIST 10 Communication system 11 Monitoring and control network 12 Communication network 20 Control device 21 Control unit 22 Memory unit 23 Communication unit 24 Path design function 25 Time slot design function 26 Path setting function 27 Network status monitoring function 28 Output unit 29 Input unit 31, 32, 33, 34 Communication device 31A, 31B, 31C, 32A, 32B, 32C, 33A, 33B, 33C, 34A, 34B, 34C Port 41, 42, 43, 44 User site 51 Network information 52 Path information 53 Time slot information 54 Setting information 55 Alarm information

Claims

1. 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; and a control unit that defines as a path each of two or more combinations of a current route that passes through a port of at least one of the multiple communication devices and a backup route that passes through a port of a communication device of the multiple communication devices that is different from the current route, and acquires path information that defines the priority of each path as a class, and based on the acquired path information, sets, via the communication unit, time slots that allow only flows of a limited class, including flows of a corresponding class, to pass through ports passed through the current route of each path, and sets time slots that allow flows of the limited class and flows of one or more other classes to pass through ports passed through the backup route of each path.

2. The control device according to claim 1, wherein said control unit sets a time slot for passing a flow of any class to a port passed through on said backup route of each path.

3. The control device of claim 1, wherein the limited class of flows includes only flows of the corresponding class.

4. A control device as described in any one of claims 1 to 3, wherein when the control unit detects a failure in the current route of any path, it switches that path to the backup route, and sets, via the communication unit, a time slot that allows flows of the limited class and flows of one or more other classes to pass through to a port that is passed through the current route before the path is switched.

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