Communication equipment and communication methods

Abstract

To provide a communication device having a duplex configuration capable of, when a failure occurs in a line connecting first and second main control devices, appropriately setting both of them respectively to an operation system and a standby system, and a communication method thereof.SOLUTION: A communication device 500 having a duplex configuration includes: first and second communication function units; a first main control device 100 and a second main control device 200 which are set to a standby system or an operation system, and control operation of the first communication function unit or the second communication function unit when being set to the operation system. Each of the first and second main control devices includes: an IP communication unit connected with an IP network; and an operation system / standby system determination processing unit which determines whether or not a main control device on a counterpart side among the first and second main control devices is under operation, and performs system switching where the processing unit sets itself to the standby system when it is determined being under operation, and sets itself to the operation system when it is determined being not under operation.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a communication device, particularly a communication device having a duplex configuration and a communication method thereof.

Background Art

[0002] As a duplex control device for enhancing fault tolerance, an operation / standby system switching is performed to appropriately set each of the first and second components forming a duplex component to an operation system and a standby system by a monitoring unit that monitors the operation status of the first and second components. A device has been proposed (see, for example, Patent Document 1).

[0003] In addition, a device has been proposed in which the first and second components forming a duplex component are connected to each other by dedicated lines, and information regarding the operation status is exchanged with each other using the dedicated lines, and the operation / standby system is switched based on the operation status of the other side (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the device adopting the above-described duplex configuration, when a failure occurs in the wiring connected between the first and second components to perform communication for mutually acquiring information regarding the operation status of each of the first and second components, the operation status of the other component cannot be confirmed. Therefore, when the operation status of the other side cannot be confirmed, it is conceivable to determine that a failure has occurred on the other side and switch the own device from the standby system to the operation system.

[0006] However, even if, for example, the other party's components are functioning correctly as an operational system, the device itself may be set to the operational system, resulting in a malfunction where both the first and second components become operational.

[0007] Therefore, there was a problem in that communication operations using the redundant configuration could not be continued normally until repairs were made to eliminate the fault in the wiring connecting the first and second components.

[0008] Therefore, the present invention aims to provide a communication device and communication method having a redundant configuration that allows the first and second components to be appropriately set as the operational and standby systems even if a failure occurs in the wiring connecting the first and second components. [Means for solving the problem]

[0009] The communication device according to the present invention is a redundant communication device comprising: first and second communication function units; and first and second main control units configured as a standby system or an operational system, which control the operation of the first and second communication function units when configured as the operational system, wherein each of the first and second main control units includes: a communication unit connected to an IP network; and an operational / standby system determination processing unit that performs a determination process via the IP network to determine whether the other main control unit of the first and second main control units is operational, and sets itself as the standby system if it determines that it is operational, and sets itself as the operational system if it determines that it is not operational. The communication unit then sends an ARP request to the IP network requesting the MAC address corresponding to the IP address of the main control unit of the operational system, and continues to wait for the reception of an ARP reply as a response to the ARP request. The operational / standby system determination processing unit determines that the other main control unit is operational if the ARP reply is received and the MAC address indicated in the ARP reply matches the MAC address of the other main control unit, while determining that the other main control unit is not operational if the ARP reply is not received. do. Furthermore, the communication device according to the present invention is a redundant communication device including first and second communication function units, and first and second main control units that are set to a standby system or an operational system and control the operation of the first and second communication function units when set to the operational system, wherein each of the first and second main control units includes a communication unit connected to an IP network, and an operational / standby system determination processing unit that performs a determination process via the IP network to determine whether the other main control unit of the first and second main control units is operational, sets itself to the standby system if it is determined to be operational, and sets itself to the operational system if it is determined not to be operational, and each of the first and second main control units transmits a status inquiry signal via a cable to the other main control unit indicating whether it is currently operational or standby, and determines that the fault has occurred if it cannot receive a status inquiry response signal, which is a response to the status inquiry signal, via the cable. .

[0010] The communication method according to the present invention is a communication method performed by each of the first and second main control devices of a redundant communication device, which includes first and second communication function units and first and second main control devices that are set to a standby system or an operational system and control the operation of the first and second communication function units when set to the operational system, Each of the first and second main control devices, Connecting to an IP Network The system performs a communication step and an operational / standby system determination step, which involves determining whether the other main control unit among the first and second main control units is operational via the IP network, setting itself as the standby system if it is determined to be operational, and setting itself as the operational system if it is determined to be not operational. In the communication step, an ARP request is sent to the IP network requesting the MAC address corresponding to the IP address of the main control unit set as the operational system, and the system then waits for the receipt of an ARP reply as a response to the ARP request. In the operational / standby system determination step, if the ARP reply is received and the MAC address indicated in the ARP reply matches the MAC address of the other main control unit, it is determined that the other main control unit is operational, while if the ARP reply is not received, it is determined that the other main control unit is not operational. . Furthermore, the communication method according to the present invention is A communication method performed by each of the first and second main control units of a redundant communication device, which includes first and second communication function units and first and second main control units configured as a standby system or an operational system, and which control the operation of the first and second communication function units when configured as an operational system, wherein each of the first and second main control units performs a communication step of connecting to an IP network, an operational / standby system determination step of performing a system switching, which involves determining whether the other main control unit of the first and second main control units is operational via the IP network, setting itself to the standby system if it determines that it is operational, and setting itself to the operational system if it determines that it is not operational, and further performing a fault determination step of determining that the fault has occurred if it cannot receive a state inquiry response signal, which is a response to the state inquiry signal, via the cable . [Effects of the Invention]

[0011] In this invention, each of the first and second main control units, which are configured in a redundant communication system, acquires the operational status (operating, standby) of the other main control unit via communication over an IP (Internet Protocol) network.

[0012] This makes it possible to appropriately set one of the first and second main control units as the operational system and the other as the standby system, even if a fault occurs in the wiring connecting the first and second main control units to acquire the operational status of the other main control unit. [Brief explanation of the drawing]

[0013] [Figure 1] This is a block diagram showing the configuration of communication system 1000. [Figure 2] This is a block diagram showing the internal configuration of a redundant communication device 500 as a communication device according to the present invention. [Figure 3] This is a communication flow diagram showing an example of communication operations that take place between the main control units 100 and 200 after startup. [Figure 4] This diagram shows the communication flow when a failure occurs in cables 30, 40, 50, and 60 after the main control devices 100 and 200 have been set to standby and operational systems, respectively. [Figure 5] This is a communication flow diagram showing an example of communication operations performed between the main control units 100 and 200 and the Ethernet switch 51 during fault response processing. [Figure 6] This communication flow diagram shows an example of communication operations between the main control units 100 and 200 and the Ethernet switch 51, initiated by fault response processing initiated by the main control unit 200, when both main control units 100 and 200 are operational. [Figure 7]It is a communication flowchart showing an example of a communication operation performed among the main control devices 100 and 200 and the Ethernet switch 51 when the main control devices 100 and 200 simultaneously execute a failure response process. [Figure 8] It is a communication flowchart showing a communication operation performed among the main control devices 100 and 200 and the Ethernet switch 51 when the main control devices 100 and 200 execute a failure response process considering the priority of system switching.

Embodiment for Carrying Out the Invention

[0014] FIG. 1 is a block diagram showing a communication system 1000 including a communication device according to the present invention.

[0015] As shown in FIG. 1, the communication system 1000 includes a duplex communication device 500, and an Ethernet switch 51, a router 52, an intranet 53, an external device 54, and a public IP (Internet Protocol) network 55 connected to the duplex communication device.

[0016] FIG. 2 is a block diagram showing an example of the internal configuration of the duplex communication device 500 as a communication device according to the present invention.

[0017] As shown in FIG. 2, the duplex communication device 500 is composed of main control devices 100 and 200 as a duplex configuration unit, and terminal line accommodation units A11, A12, B13 to B16 as a function providing unit.

[0018] In each of the terminal line accommodation units A11, A12, B13 to B16, terminals such as a telephone and a FAX (facsimile) connected and accommodated to the main control devices 100 and 200, and various lines such as a public network line or a private network dedicated line are connected, and they are deployed as utilization devices of a communication control device such as a business phone. As shown in FIG. 2, the terminal line accommodation units A11, A12, B13 to B16 are connected via cables 17 to 20, 30, 40, 50, and 60 that transmit control signals and voice signals to the main control devices 100 and 200.

[0019] Each of the terminal line accommodation units A11, A12, and B13-B16 provides the service function of a business phone by connecting the devices used and exchanging voice signals based on instructions (control signals) from the main control unit 100 or 200.

[0020] The main control unit 100 is connected to terminal line accommodation units A11, A12, and B13-B16 via cables 30 and 40, and the main control unit 200 is connected to terminal line accommodation units A11, A12, and B13-B16 via cables 50 and 60.

[0021] Furthermore, one of the features of the redundant communication device 500 is that it monitors the status of the main control devices 100 and 200, which are configured in a redundant state, by using a proprietary signaling method via cables 30, 40, 50, and 60, through which control signals and voice signals for providing the service functions of the business phone are transmitted.

[0022] The main control devices 100 and 200 transmit and receive data regarding the operational status to each other via dedicated channels, separate from the channels used for control signals to the normal terminal line access unit, through cables 30 or 40 and 50 or 60, in order to determine the operational and standby systems.

[0023] The dedicated channel is allocated among the control signals for checking the status of the main control unit. For example, the main control unit 100 transmits data from the dedicated channel to cable 50 via cable 30 and a hardware switch (not shown) included in terminal line accommodation unit A11. Similarly, the main control unit 100 transmits data from the dedicated channel to cable 60 via cable 40 and a hardware switch (not shown) included in terminal line accommodation unit A12.

[0024] Each of the main control units 100 and 200 includes a memory RG that holds operational status information 31, redundant control data 32, and IP information 41, an operational / standby system determination processing unit 33, an IP overlap determination processing unit 42, and an IP communication unit 43.

[0025] Furthermore, the operational status information 31 indicates whether the local device and other devices are in an operational or standby state. For example, the operational status information 31 held in the memory RG included in the main control unit 100 indicates whether the local device (main control unit 100) and the other device (main control unit 200) are in an operational or standby state. On the other hand, the operational status information 31 held in the memory RG included in the main control unit 200 indicates whether the local device (main control unit 200) and the other device (main control unit 100) are in an operational or standby state.

[0026] The redundancy control data 32 indicates which of the two main control devices, 100 or 200, will be prioritized for switching to the standby system when both systems are in the operational state. For example, memory RG pre-stores redundancy control data 32 that is associated with the main control devices 100 and 200 respectively and represents the priority for switching between the operational and standby systems (hereinafter also referred to as system switching). Note that memory RG of each of the main control devices 100 and 200 stores redundancy control data 32 that represents different priorities.

[0027] IP information 41 is, for example, a MAC address. In other words, the IP information 41 stored in the memory RG of the main control unit 100 indicates the MAC address of the main control unit 100, and the IP information 41 stored in the memory RG of the main control unit 200 indicates the MAC address of the main control unit 200.

[0028] The main control units 100 and 200 are each connected to an IP network 55 via an Ethernet switch (hereinafter also referred to as L2SW) 51 through an IP communication unit 43 included in each unit.

[0029] The Ethernet switch 51 is a switch that aggregates the redundant communication devices 500 so that they appear to be a single communication device from an external perspective. This Ethernet switch 51 connects the redundant communication devices 500 to the public IP network 55 via a router 52 or an intranet 53 located at the same site as the redundant communication devices 500.

[0030] The internal operation of the redundant communication device 500 is described in detail below.

[0031] When power is supplied to the main control units 100 and 200, the main control unit control program is executed. First, for example, the operational / standby system determination processing unit 33 of the main control unit 100 creates information representing the current state of its own device (starting up, operating, or standby) based on the state at the time of the previous startup (operating or standby) indicated in the operational status information 31. Then, the main control unit 100 transmits a status inquiry signal 101, which includes the status information representing the state at the time of the previous startup (operating or standby) and the current state (starting up, operating, or standby), as a control signal on a dedicated channel to cables 30 and 40. At this time, the control signal is assigned to a dedicated channel for status monitoring for the main control unit and is transferred to the other main control unit via terminal line accommodation units A11 and A12. The main control unit that receives the control signal analyzes the status information contained in the control signal, that is, the state of the other party (state at the time of the previous startup, current state of itself), and determines its own state (operating or standby) based on the state of the other party. Then, a status inquiry response signal 102 containing information indicating the decision result is sent back to the other party's main control unit as a control signal on a dedicated channel.

[0032] By the way, if the power is turned on normally, both main control units start operating at almost the same time. Therefore, main control units 100 and 200 operate in relation to each other. State at last startup: None Device status: Starting up A status query signal containing status information is received.

[0033] At this time, the status of each of the main control devices 100 and 200 is also checked. State at last startup: None Device status: Starting up Therefore, they are exactly the same.

[0034] Therefore, the operational / standby system determination processing unit 33 of each main control unit 100 and 200 determines whether one of the main control units 100 or 200 is operational and the other is in standby mode, based on the priority indicated by the redundancy control data 32 held in its own memory RG. In other words, of the main control units 100 and 200, the one holding the redundancy control data 32 indicating a higher priority is determined to be operational, and the one holding the redundancy control data 32 indicating a lower priority is determined to be in standby mode.

[0035] As a result, the operational status information 31 regarding the operational status of the main control device 100 is, State at last startup: None Device status: In operation Set to this.

[0036] On the other hand, the operational status information 31 regarding the operational status of the main control device 200 is: State at last startup: None Device status: Standby Set to this.

[0037] After these settings are made, the main control unit 200 will then use status information as follows: Device status: Standby The status inquiry response signal 102, which includes the above, is sent back to the other party's main control unit 100 as a control signal for the dedicated channel. Upon receiving it, the main control unit 100 determines, using its own operational / standby system determination processing unit 33, that its own device is operational and overwrites the memory RG with operational status information 31 indicating this. The main control unit 100 then notifies the terminal line accommodation unit A11 that it is the operational system. Upon receiving this notification, the terminal line accommodation unit A11 switches the path connections for control signals and voice signals, designating the main control unit 100 as the operational system. This makes it possible to provide business phone service functions by connecting the user devices based on instructions (control signals) from the main control unit 100 and exchanging voice signals.

[0038] Figure 3 is a communication flow diagram showing an example of communication operations that take place between the main control units 100 and 200 after the initial startup described above is completed and the business phone begins to operate.

[0039] Although communication between the main control units 100 and 200 is actually carried out via terminal line hubs A11 and A12, and cables 30, 40, 50, and 60, the description of terminal line hubs A11 and A12, and cables 30, 40, 50, and 60 is omitted in Figure 3.

[0040] First, the main control unit 200, which is in standby mode, sends a status inquiry signal 101 at regular intervals to monitor the communication status of the main control unit 100, which is in operational mode. The current status of the redundant main control units is updated based on the response, i.e., the presence or absence of a status inquiry response signal 102.

[0041] In other words, if there is no malfunction in the main control unit 100 of the operational system, the main control unit 200 will send back a status inquiry response signal 102 from the main control unit 100 within a predetermined time period after the main control unit 200 sends the status inquiry signal 101. At this time, the main control unit 200 will maintain its state because its own state is standby and the state of the other party (main control unit 100) indicated by the status inquiry response signal 102 is operational.

[0042] However, if a failure occurs in the main control unit 100 of the operational system, the status inquiry response signal 102 will not be returned even after a predetermined time has elapsed since the status inquiry signal 101 was sent. Therefore, if the status inquiry response signal 102 is not returned after a predetermined time has elapsed since the status inquiry signal 101 was sent, the main control unit 200 of the standby system resends the status inquiry signal 101. If the status inquiry response signal 102 is still not returned, the main control unit 200 repeats the above-described retransmission process of the status inquiry signal 101 a predetermined number of times. If the status inquiry response signal 102 is still not returned from the main control unit 100 of the operational system, the main control unit 200 of the standby system determines that a failure has occurred in the main control unit 100 of the operational system.

[0043] In other words, the main control unit 200 performs fault detection, indicating that a fault has occurred if it does not receive a response signal 102 to the transmission of a status inquiry signal 101.

[0044] Upon detecting such a fault, the main control unit 200 switches the state of its own device from standby to operational. The main control unit 200 then overwrites the memory RG with operational status information 31 indicating that its own device is operational and the other device is in a fault state.

[0045] Subsequently, when the main control unit 100 recovers from the fault state, the main control unit 100 sends a status inquiry signal 101 to the main control unit 200 that includes status information indicating that the status of its own device is undetermined. When the main control unit 200, which has switched to operation, receives this status inquiry signal 101, it sends a status inquiry response signal 102 to the main control unit 100 that includes status information indicating that the status of its own device is in operation, since the operation status information 31 held in its own memory RG indicates that the status of its own device is in operation.

[0046] Upon receiving such a status inquiry response signal 102, the main control unit 100 determines, using its own operational / standby system determination processing unit 33, that its own device is in standby mode, and overwrites the memory RG with operational status information 31 indicating that its own device is in standby mode and the other device is in operation.

[0047] If a failure occurs in the main control unit 100 or 200 that was performing communication operations as the operational system due to the series of communication processes described above, the primary control unit that was set as the standby system will switch to the operational system and continue communication operations.

[0048] Incidentally, according to the series of communication processes described above, when the fault in the main control unit 100 is resolved, mutual communication between the main control units 100 and 200 is resumed via the status inquiry signal 101 and the status inquiry response signal 102. As a result, each of the main control units 100 and 200 can acquire each other's status information (operational system, standby system), and based on the acquired status information, it becomes possible to appropriately set one of the main control units 100 and 200 as the standby system and the other as the operational system.

[0049] However, if a problem such as a break or short circuit occurs in the communication path between the main control units 100 and 200, i.e., cables 30, 40, 50, and 60, communication between the main control units 100 and 200 becomes impossible, and status information (operating system, standby system) cannot be obtained. As a result, each of the main control units 100 and 200 will be unable to ascertain the operating status of the other, making it difficult to properly set one of the main control units 100 and 200 as the operating system and the other as the standby system.

[0050] Figure 4 shows the communication flow when a failure occurs in cables 30, 40, 50, and 60 after the main control devices 100 and 200 have been set to standby and operational systems, respectively, through communication of status inquiry signal 101 and status inquiry response signal 102.

[0051] As shown in Figure 4, after the failure occurs, the standby main control unit 200 continues to repeatedly send the status inquiry signal 101 to the main control unit 100, but because there is a failure in cables 30, 40, 50, and 60, the main control unit 100 cannot receive it. Therefore, although the status inquiry signal 101 is sent a predetermined number of times, the status inquiry response signal 102 is not sent back, so the main control unit 200 determines that there is a failure on the other device side (cables 30, 40, 50, and 60) and switches itself from the standby system to the operational system. Since there is no access to the main control unit 100, it maintains the current operational system state, and both main control units 100 and 200 become operational.

[0052] Therefore, in order to avoid the malfunction in which both the main control units 100 and 200 of the redundant communication device 500 are in the operational state, if it is determined that a failure has occurred in the other party's main control unit, the following fault response process is performed instead of immediately switching over.

[0053] In other words, in the fault response process, first, the IP communication unit 43 of the main control unit (100 or 200) that made the fault determination as described above sends an ARP (Address Resolution Protocol) request message to the Ethernet switch 51. The ARP request message includes IP address #0, which is the IP information of the operational system of the main control unit of this business phone, as the target IP address, and the MAC address of the sending main control unit. Since the ARP request message is a broadcast IP packet, the IP communication unit 43 of each of the main control units 100 and 200 receives the ARP request message via the Ethernet switch 51, router 52, and IP network.

[0054] Upon receiving an ARP request message, the main control unit determines whether the target IP address indicated in the ARP request message is the same as its own IP address. If it determines that the target IP address indicated in the ARP request message is the same as its own IP address, the main control unit that received the ARP request message sends an ARP reply message to the main control unit having the source MAC address via the Ethernet switch 51, router 52, and IP network.

[0055] During this time, the main control unit that sent the ARP request message remains in a waiting state for a predetermined waiting period to receive an ARP reply message. If the ARP reply message 111 is not returned (received) within this waiting period, the IP overlap determination processing unit 42 of this main control unit determines that there is no device with IP address #0 on the IP network (53, 55), i.e., no operational device (main control unit) with an overlapping IP address. As a result, the operational / standby determination processing unit 33 of the main control unit that sent the ARP request message determines that the other main control unit is in a standby state and switches itself from standby to operational.

[0056] On the other hand, if an ARP reply message is received within the waiting period, the IP duplication determination processing unit 42 of the main control unit determines that there is another device on the IP network 55 and intranet 53 that is using IP address #0 in duplicate, i.e., a main control unit in operation. The IP duplication determination processing unit 42 then determines whether the source MAC address indicated in the ARP reply message 111 is the same as the MAC address indicated in the IP information 41 of the other main control unit that has been previously obtained or configured.

[0057] If it determines that they are identical, the IP duplicate detection processing unit 42 determines that the other device using IP address #0 is the operational main control unit of the other party. As a result, the operational / standby system determination processing unit 33 of the main control unit that received the ARP reply message sets its own device as a standby system because the source MAC address indicated in the ARP reply message is that of the operational main control unit of the other party. It then retries fault detection. In other words, at this time, the operational / standby system determination processing unit 33 of the main control unit that received the ARP reply message maintains the standby system state if its own device is currently in standby mode, and switches from the operational system to the standby system if it is in operation.

[0058] Furthermore, if the IP duplication detection processing unit 42 determines that the MAC address of the source of the ARP reply message 111 does not match the MAC address of the main control unit 100, it determines that the source is not the main control unit of the redundant communication device 500, but an external network device (an IP-connected device such as a computer router). In this case, the operational / standby system determination processing unit 33 does not change the state of its own device (standby system), but instead stores warning information in its memory RG prompting the external network device that sent the message to change its address.

[0059] Figure 5 is a communication flow diagram showing an example of the communication operations performed between the main control units 100 and 200 and the Ethernet switch 51 as a result of the fault response processing described above.

[0060] As shown in Figure 5, although the standby system's main control unit 200 sends a status inquiry signal 101 to the main control unit 100 a predetermined number of times, the status inquiry response signal 102 is not returned because a fault has occurred in cable 30, 40, 50, or 60. Since the status inquiry response signal 102 is not returned, the main control unit 200 determines that there is a fault and executes the following fault response process.

[0061] Specifically, first, the main control unit 200 sends an ARP request message 110 to the Ethernet switch 51, representing the IP address #0 of the operational system of the main control unit of this business phone as the target IP address, and the MAC address #2 of the main control unit 200. The ARP request message 110 is then sent to the main control unit 100 via the Ethernet switch 51, router 52, and IP network. Upon receiving the ARP request message 110, the main control unit 100, finding that the target IP address indicated in the ARP request message 110 is the same as its own IP address, sends an ARP reply message 111 to the main control unit 200, which has the MAC address of the sender, via the Ethernet switch 51, router 52, and IP network.

[0062] During this time, the main control unit 200 remains in a waiting state for the reception of the ARP reply message 111 for a predetermined waiting period. If the ARP reply message 111 is received within this waiting period, the main control unit 200 determines that there is another device on the IP network 55 and intranet 53 that is using IP address #0 in duplicate, i.e., a main control unit 100 that is in operation. Since the other main control unit 100 is in operation, the main control unit 200 does not switch from the standby system to the operational system, but instead sets itself to maintain its current state as the standby system.

[0063] As detailed above, in the redundant communication device 500, two main control devices (100, 200) that control the first communication function unit (terminal line accommodation device A11, terminal line accommodation device B13, terminal line accommodation device B14) and the second communication function unit (terminal line accommodation device A12, terminal line accommodation device B15, terminal line accommodation device B16), which perform various communication services including telephone and other call services, set themselves to either the standby system or the operational system according to the following configuration.

[0064] In other words, each of the first and second main control units has a communication unit (43) connected to an IP network (51-53, 55) and the following operational / standby system determination processing unit.

[0065] The operational / standby system determination processing unit (33) performs a determination process via the IP network to determine whether the other main control unit among the first and second main control units (100, 200) is operational or not. If it determines that the other main control unit is operational, it sets itself to the standby system; if it determines that the other main control unit is not operational, it sets itself to the operational system.

[0066] With this configuration, each of the first and second main control units acquires the operational status (operating, standby) of the other main control unit via communication over an IP network. As a result, even if a failure occurs in the cables (30, 40, 50, 60) connecting the first and second main control units to acquire the operational status of the other main control unit, it is possible to appropriately set one of the first and second main control units as the operational system and the other as the standby system.

[0067] Next, we will explain how to recover from a state where both main control units 100 and 200 are in the operational state (one in the operational state, the other in the standby state) because the ARP reply message 111 sent by one of the main control units 100 and 200 could not be received by the other, referring to the communication flow shown in Figure 6.

[0068] Figure 6 is a communication flow diagram showing an example of communication operations that occur between the main control units 100 and 200 and the Ethernet switch 51 as a result of fault response processing initiated by the main control unit 200.

[0069] As shown in Figure 6, first, the IP communication unit 43 of the main control unit 200 of the operational system sends an ARP request message 110 to the Ethernet switch 51, representing IP address #0 as the target IP address and MAC address #2 of the main control unit 200. In other words, the main control unit 200 sends the ARP request message 110 as a broadcast IP packet and waits for a reply in the form of an ARP reply message 111. When the main control unit 200 receives the ARP reply message 111, it means that there is an operational device that is using IP address #0 redundantly. Therefore, the main control unit 200 checks the source MAC address included in the ARP reply message 111 to determine whether the operational device in question is the main control unit 100. At this time, since the source MAC address of the ARP reply message 111 is the MAC address of the operational main control unit 100, the main control unit 200 switches itself from the operational system to the standby system to avoid redundancy in the operational system. The main control unit 200 then overwrites the memory RG with operational status information 31 indicating that its own device is in standby mode and the other device is in operation.

[0070] By the way, in the recovery method described above, one of the main control units 100 and 200, which has become the operational system (main control unit 200), is performing the fault response process.

[0071] However, there are cases where both the main control units 100 and 200 perform fault response processing, and it is possible that both the main control units 100 and 200 may simultaneously switch between the operational and standby systems.

[0072] Figure 7 is a communication flow diagram showing the communication operations that take place between the main control units 100 and 200 and the Ethernet switch 51 when each of the main control units 100 and 200 simultaneously execute fault response processing.

[0073] In other words, when a fault is detected by the status inquiry signal 101 and status inquiry response signal 102 described above, as shown in Figure 7, the main control unit 200 sends an ARP request message 110 to the main control unit 100 via the Ethernet switch 51, and the main control unit 100 sends an ARP request message 112 to the main control unit 200 via the Ethernet switch 51. At this time, when the main control unit 100 receives the ARP request message 110, it sends back an ARP reply message 111 to the main control unit 200 via the Ethernet switch 51. Also, when the main control unit 200 receives the ARP request message 112, it sends back an ARP reply message 113 to the main control unit 100 via the Ethernet switch 51.

[0074] Therefore, each of the main control units 100 and 200, based on the ARP reply message returned from the other main control unit, determines that the other main control unit is also an operational device using IP address #0 for communication, and switches itself from the operational system to the standby system. Such unnecessary system switching of operational main control units may lead to interruptions or termination of ongoing calls and various services.

[0075] Therefore, in the redundant communication device 500, the main control units 100 and 200 are each assigned a priority for performing system switching. That is, for example, the memory RG of the main control unit 100 holds redundant control data 32 representing the first priority, and the memory RG of the main control unit 200 holds redundant control data 32 representing the second priority, which is lower than the first priority. In this case, the system switching to the active system is performed by the main control unit 100 or 200 with the higher priority. Conversely, the system switching to the standby system is performed by the one with the lower priority. For example, if each of the main control units 100 and 200 determines that the other main control unit is also in operation, the main control unit 200, which holds redundant control data 32 representing the second priority, which is lower than the first priority, will switch from the active system to the standby system each time a fault is detected, while the main control unit 100, which holds redundant control data 32 representing the first priority, which is higher than the second priority, will not perform system switching unless two faults are detected consecutively. Furthermore, if either the main control unit 100 or 200 determines that the other main control unit is also not currently in operation, the main control unit 100, which holds redundant control data 32 representing a first priority higher than the second priority, will switch from the standby system to the operational system each time a failure is detected. On the other hand, the main control unit 200, which holds redundant control data 32 representing a second priority lower than the first priority, will not switch unless two failures are detected consecutively.

[0076] Figure 8 is a communication flow diagram showing the communication operations that take place between the main control units 100 and 200 and the Ethernet switch 51 when each of the main control units 100 and 200 performs fault response processing that takes into account the priority for performing the system switching described above.

[0077] When a fault in cable 30, 40, 50, or 60 is detected by the status inquiry signal 101 and status inquiry response signal 102 described above, the main control unit 200 sends an ARP request message 110 to the main control unit 100 via the Ethernet switch 51. Furthermore, the main control unit 100 sends an ARP request message 112 to the main control unit 200 via the Ethernet switch 51. Upon receiving the ARP request message 110, the main control unit 100 sends an ARP reply message 111 back to the main control unit 200 via the Ethernet switch 51. Also, upon receiving the ARP request message 112, the main control unit 200 sends an ARP reply message 113 back to the main control unit 100 via the Ethernet switch 51.

[0078] When main control units 100 and 200 receive an ARP reply message from the other main control unit, they determine, based on the ARP reply message, that the other main control unit is also an operational device using IP address #0 for communication. At this point, each of the main control units 100 and 200 checks the redundancy control data 32 stored in its own memory RG. In this case, the redundancy control data 32 of main control unit 200 represents the second priority (priority 2), and the redundancy control data 32 of main control unit 100 represents the first priority (priority 1). Therefore, main control unit 200 performs the process of switching itself from the operational system to the standby system. On the other hand, the redundancy control data 32 of main control unit 100 represents the first priority, which has a higher priority than the second priority. In this case, according to the first priority, main control unit 100 can switch over if the above-described fault detection operation is performed twice in a row, so at this stage (one fault detection), system switching is not performed. Therefore, the main control device 100 maintains the current operating system state.

[0079] In this way, the redundant communication device 500 avoids unnecessary operation, such as unnecessarily switching the active system to the standby system, by setting different priorities for system switching in the main control devices 100 and 200.

[0080] Furthermore, the main control unit 200 may perform system switching after a predetermined first hour delay following fault detection, based on the second priority, while the main control unit 100 may perform system switching after a second hour delay, which is longer than the first hour, following fault detection, based on the first priority.

[0081] Furthermore, the redundant control data 32 may use priority based on the operating state before fault detection (operating system > standby system > fault > starting up) or an identification number (1 > 2) pre-set in the main control unit.

[0082] In the above embodiment, an application example was described that enhances fault tolerance in the event of a failure of the main control unit. Incidentally, the terminal line accommodation device shown in Figure 2 is a building block configuration that can be added as needed. Therefore, by switching systems according to the failure location as fault tolerance for multiple terminal line accommodation devices, it becomes possible to apply this to a further redundant configuration device by adding the above-mentioned redundant control data and the state detection unit for that determination to determine whether many terminal line accommodation devices are available.

[0083] As described above, with the redundant communication device 500, even if the cables (30, 40, 50, 60) connecting the main control devices 100 and 200 fail, it is possible to correctly set one of the main control devices 100 and 200 as the operational system and the other as the standby system by comparing the IP information obtained through communication with IP network equipment with the IP information of the device itself.

[0084] This also prevents confusing behavior for external devices that notify other IP network devices of multiple MAC addresses for a single IP address.

[0085] Furthermore, depending on the timing of the ARP request message transmission, there is a possibility that when a fault is detected, both the main control units 100 and 200 may transition from the operational system to the standby system, resulting in a state where both are in standby mode and the system is unable to provide functionality. This possibility is avoided by using redundant control data that indicates the priority for executing system switching. In addition, the aforementioned recovery process will not be repeated if the fault condition persists, and this can also be prevented by using the redundant control data described above. [Explanation of symbols]

[0086] 11, 12 Terminal line access unit A 13-16 Terminal line accommodation section B 30, 40, 50, 60 cables 32. Redundancy control data 33. Operation / Standby System Determination Processing Unit 42 IP Overlay Processing Unit 43 IP Communications Department 100, 200 Main control unit 500 Duplex communication equipment

Claims

1. First and second communication function units, A redundant communication device comprising: first and second main control devices, which are set to a standby system or an operational system and control the operation of the first communication function unit and the second communication function unit when set to the operational system, Each of the first and second main control devices is: A communication unit that connects to an IP network, The system includes an operational / standby system determination processing unit that performs a determination process via the IP network to determine whether the other of the first and second primary control units is operational, sets itself to the standby system if it is determined to be operational, and sets itself to the operational system if it is determined not to be operational, thereby performing system switching. The communication unit sends an ARP request to the IP network requesting a MAC address corresponding to the IP address of the main control unit of the operational system, and then waits for the reception of an ARP reply as a response to the ARP request. The communication device is characterized in that the operational / standby system determination processing unit determines that the other party's main control unit is operational when the ARP reply is received and the MAC address indicated in the ARP reply matches the MAC address of the other party's main control unit, while determining that the other party's main control unit is not operational when the ARP reply is not received.

2. The first and second main control devices are connected to each other via a communication path within the communication device. The communication device according to claim 1, characterized in that the operational / standby system determination processing unit performs the determination process and the system switching when a failure occurs in the main control unit of the other party or when a failure occurs in the communication path.

3. A redundant communication device comprising: first and second communication function units; and first and second main control devices, which are set to a standby system or an operational system and control the operation of the first and second communication function units when set to the operational system, Each of the first and second main control devices is: A communication unit that connects to an IP network, The system includes an operational / standby system determination processing unit that performs a determination process via the IP network to determine whether the other of the first and second primary control units is operational, sets itself to the standby system if it is determined to be operational, and sets itself to the operational system if it is determined not to be operational, thereby performing system switching. A communication device characterized in that each of the first and second main control units transmits a status inquiry signal via a cable to the other main control unit indicating whether it is currently in operation or standby mode, and determines that the fault has occurred if it fails to receive a status inquiry response signal, which is a response to the status inquiry signal, via the cable.

4. Each of the first and second main control devices is assigned a priority for performing the system switching. The communication device according to any one of 1 to 3, characterized in that when each of the first and second main control devices determines that the other main control device is in operation, the operational / standby system determination processing unit of the main control device to which the lower priority of the first and second main control devices is assigned performs the system switching.

5. Each of the first and second main control devices is assigned a priority for performing the system switching. The communication device according to any one of 1 to 4, characterized in that, if each of the first and second main control devices determines that the other main control device is not in operation, the operational / standby system determination processing unit of the main control device to which the higher priority of the first and second main control devices is assigned executes the system switching.

6. A communication method performed by each of the first and second main control devices of a redundant communication device, which includes first and second communication function units and first and second main control devices set to a standby system or an operational system and controlling the operation of the first and second communication function units when set to the operational system, Each of the first and second main control devices, Communication steps for connecting to an IP network, The process involves performing a determination process via the IP network to determine whether the other main control unit of the first and second main control units is in operation, setting itself as the standby system if it is determined to be in operation, and performing a system switching process to set itself as the operational system if it is determined to be not in operation. In the communication step, an ARP request is sent to the IP network requesting a MAC address corresponding to the IP address of the main control unit set in the operational system, and then the system waits for the reception of an ARP reply as a response to the ARP request. The communication method is characterized in that, in the operational / standby system determination processing step, if the ARP reply is received and the MAC address indicated in the ARP reply matches the MAC address of the other party's main control unit, it is determined that the other party's main control unit is operational, while if the ARP reply is not received, it is determined that the other party's main control unit is not operational.

7. A communication method performed by each of the first and second main control units of a redundant communication device, which includes first and second communication function units and first and second main control units set to a standby system or an operational system and controlling the operation of the first and second communication function units when set to the operational system, Each of the first and second main control devices, Communication steps for connecting to an IP network, The process involves performing a determination process via the IP network to determine whether the other main control unit of the first and second main control units is in operation, setting itself as the standby system if it is determined to be in operation, and performing a system switching process to set itself as the operational system if it is determined to be not in operation. A communication method characterized in that each of the first and second main control units transmits a status inquiry signal via a cable to the other main control unit indicating whether it is currently in operation or standby mode, and further performs a fault determination step in which it determines that a fault has occurred if it is unable to receive a status inquiry response signal, which is a response to the status inquiry signal, via the cable.

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