Switching system and line control method

Abstract

To provide a technique of easily suppressing a busy ratio of a line.SOLUTION: An exchange comprises: a call control part that provides an exchange service; a connection state management part that manages a connection state with the exchange on a route of the exchange service; a fault detection part that detects a communication fault between adjacent fault detection object exchanges on the route of the exchange service, and notifies the connection state management part of the communication fault; a fault information sharing part that shares fault information of the communication fault with a predetermined notification object exchange different from the fault detection object exchange when the communication fault is detected; and an emission regulation sound guidance part that transmits an emission regulation sound guidance to an origin by limiting a calling to the fault detection object exchange in the case where the fault detection object exchange indicates a disable state of the connection in the connection state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exchange and a line control method. [Background technology]

[0002] Patent document 1 discloses an exchange that has an exchange service control unit made up of multiple software groups that control the execution of exchange services, and an abnormal state monitoring unit made up of software groups that monitor faults in the exchange's hardware and software and monitor the exchange's congestion state, and the abnormal state monitoring unit has an abnormal state judgment unit, the exchange service control unit has a service start judgment unit, and a memory unit has exchange service start judgment data, and when the service start judgment unit receives a request from the exchange service control unit to judge whether or not an exchange service can be started, it refers to the exchange service start judgment data to judge whether or not the exchange service in question can be started and returns the result. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-38259 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 above is an example of a technology for controlling service activation of a switch within the switch itself. However, in a switching system in which multiple switches are connected in multiple stages, such as in a tree or star topology, if there is a switch that does not activate its service, the failure will not be detected until the outgoing call reaches that switch, and unnecessary traffic cannot be suppressed, resulting in a high line busy rate.

[0005] An object of the present invention is to provide a technique for easily suppressing the line busy rate. [Means for solving the problem]

[0006] The present application includes a plurality of means for solving at least part of the above-mentioned problems, examples of which are as follows: To solve the above-mentioned problems, an exchange according to one aspect of the present invention comprises a call control unit that provides an exchange service, a connection status management unit that manages a connection status with exchanges on a path of the exchange service, a fault detection unit that detects a communication fault between an exchange that is a fault detection target adjacent to the path of the exchange service and notifies the connection status management unit, a fault information sharing unit that, when detecting the communication fault, shares fault information of the communication fault with a predetermined notification target exchange that is different from the exchange that is the fault detection target, and a call restriction voice guidance unit that restricts calls to the exchange that is the fault detection target and transmits a call restriction voice guidance to a caller when the exchange that is the fault detection target indicates a connectable state in the connection status.

[0007] In addition, in the above-mentioned exchange, when fault information of the communication fault is shared with the exchange from an intermediate exchange that is an adjacent exchange on the route of the exchange service, the connection status management unit may update the connection status of the fault detection target exchange related to the communication fault.

[0008] Furthermore, in the above-described exchange, when the communication failure is detected, the connection status management unit updates the connection status of the exchange subject to failure detection and an exchange that cannot be connected on the route of the exchange service by indicating that the exchange is in an unconnectable state, and when the communication failure is detected, the failure information sharing unit may include the exchange subject to failure detection and the exchange in an unconnectable state in the failure information of the communication failure and share it.

[0009] Furthermore, in the above-mentioned exchange, when fault information of the communication fault is shared with the exchange from a transit exchange that is an adjacent exchange on the route of the exchange service, the connection status management unit updates the connection status of the exchange that is the target of fault detection related to the fault information in accordance with the transit exchange, and when the fault information is shared with the exchange from any of the transit exchanges, the call restriction voice guidance unit may restrict calls to the exchange that is related to the fault information and transmit call restriction voice guidance to the caller.

[0010] Furthermore, in the above-mentioned exchange, when the exchange subject to fault detection relating to the communication fault is an exchange positioned at a higher position on the path of the exchange service, the fault information sharing unit may not share fault information of the communication fault with a predetermined notification target exchange different from the exchange subject to fault detection, which is positioned at a lower position on the path of the exchange service.

[0011] Furthermore, a line control method according to another aspect of the present invention is a line control method in an exchange system in which a plurality of exchanges are connected in multiple stages to provide exchange services, wherein the exchanges comprise a processor, a call control unit for providing the exchange services, and a connection status management unit for managing connection statuses with exchanges on a path of the exchange services, and the processor carries out the following steps: a fault detection step of detecting a communication fault between an exchange that is a fault detection target adjacent to the path of the exchange services and notifying the connection status management unit; a fault information sharing step of, when the communication fault is detected, sharing fault information about the communication fault with a predetermined exchange that is a notification target and is different from the exchange that is the fault detection target; and a call restriction voice guidance step of restricting calls to the exchange that is the fault detection target and transmitting call restriction voice guidance to a caller when the exchange that is the fault detection target indicates a state in which connection is not possible in the connection status. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a technology for easily suppressing the line busy rate. Problems, configurations, and effects other than those described above will become clear from the following description of the embodiments. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of the configuration of an exchange system using an exchange according to a first embodiment. [Figure 2] FIG. 10 illustrates an example of a data structure of fault notification setting information. [Figure 3] FIG. 10 is a diagram illustrating an example of a data structure of connection state management information. [Figure 4] FIG. 10 illustrates an example of the data structure of a fault notification message. [Figure 5] FIG. 2 illustrates an example of a hardware configuration of a switch. [Figure 6] FIG. 10 is a diagram illustrating an example of a notification sequence when a connection is normal. [Figure 7] FIG. 10 is a diagram illustrating an example of a notification sequence when an abnormal connection occurs. [Figure 8] FIG. 10 is a diagram illustrating an example of a processing sequence when a call is sent. [Figure 9] FIG. 1 is a diagram illustrating an example of the configuration of a tree-type switch network. [Figure 10] FIG. 10 is a diagram illustrating an example of a data structure of fault notification setting information according to the second embodiment. [Figure 11] FIG. 10 is a diagram illustrating an example of a data structure of connection state management information according to the second embodiment. [Figure 12] FIG. 10 is a diagram illustrating an example of a data structure of a fault notification message according to the second embodiment. [Figure 13] FIG. 10 is a diagram illustrating an example of a notification sequence at the time of normal connection according to the second embodiment. [Figure 14] FIG. 10 is a diagram illustrating an example of a notification sequence at the time of an abnormal connection according to the second embodiment. [Figure 15] FIG. 10 is a diagram illustrating an example of a processing sequence when making a call according to the second embodiment. [Figure 16] FIG. 10 is a diagram illustrating an example of the configuration of a tree-type switch network according to a second embodiment. [Figure 17] FIG. 10 is a diagram illustrating an example of data held by the exchange according to the second embodiment. [Figure 18]FIG. 10 is a diagram showing an example of data held by another exchange according to the second embodiment. [Figure 19] FIG. 11 is a diagram showing an example of data held by still another exchange according to the second embodiment. [Figure 20] FIG. 10 is a diagram showing an example of modification of data held by the exchange according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings used to describe the embodiments, identical components are generally designated by the same reference numerals, and repeated description thereof will be omitted. In the following embodiments, the components (including element steps, etc.) are not necessarily essential unless otherwise specified or considered to be fundamentally essential. Furthermore, when a term "consists of A," "composed of A," "having A," or "including A" is used, it does not necessarily exclude other elements, unless otherwise specified to include only that element. Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of a component, etc., it is intended to include those that are substantially similar or similar to that shape, etc., unless otherwise specified or considered to be fundamentally essential.

[0015] In the following description, the input / output unit and display unit of the exchange 100 may be one or more interface devices, although they are not shown. The one or more interface devices may be at least one of the following: One or more I / O (Input / Output) interface devices. The I / O interface devices for the switch 100 may be user interface devices, such as input devices like a keyboard and a pointing device, or output devices like a display device. One or more communication interface devices. The one or more communication interface devices may be one or more homogeneous communication interface devices (e.g., one or more NICs (Network Interface Cards)) or two or more heterogeneous communication interface devices (e.g., an NIC and an HBA (Host Bus Adapter)).

[0016] In the following description, "memory" refers to one or more memory devices, which are an example of one or more storage devices, and may typically be a primary storage device. At least one memory device in the memory may be a volatile memory device or a non-volatile memory device.

[0017] In the following description, the term "storage unit" or "storage" may refer to either a memory or a persistent storage device, or both. Specifically, the persistent storage device may be, for example, a hard disk drive (HDD), a solid state drive (SSD), a non-volatile memory express (NVME) drive, or a storage class memory (SCM).

[0018] Also, in the following description, a "processing unit" or a "processor" may refer to one or more processor devices. The at least one processor device may typically be a microprocessor device such as a CPU (Central Processing Unit), but may also be another type of processor device such as a GPU (Graphics Processing Unit). The at least one processor device may be a single-core or multi-core. The at least one processor device may also be a processor core. The at least one processor device may also be a processor device in a broader sense, such as a circuit that is a collection of gate arrays written in a hardware description language that performs some or all of the processing (e.g., an FPGA (Field-Programmable Gate Array), a CPLD (Complex Programmable Logic Device), or an ASIC (Application Specific Integrated Circuit)).

[0019] Furthermore, in the following description, functions may be described using the expression "yyy unit." However, the functions may be realized by one or more computer programs executed by a processor, by one or more hardware circuits (e.g., FPGAs or ASICs), or by a combination thereof. When a function is realized by a program executed by a processor, the specified processing is performed using a storage device and / or an interface device, etc., as appropriate, and therefore the function may be considered to be at least a part of the processor. Processing described using a function as the subject may be processing performed by a processor or a device having the processor. A program may be installed from a program source. The program source may be, for example, a computer from which the program is distributed or a computer-readable recording medium (e.g., a non-transitory recording medium). The description of each function is merely an example; multiple functions may be combined into one function, or one function may be divided into multiple functions.

[0020] In the following description, processing described with a program or processing unit as the subject may be processing performed by a processor or a device having the processor. Two or more programs may be realized as one program, and one program may be realized as two or more programs.

[0021] In the following description, information that provides an output for an input may be described using expressions such as "xxx table" or "xxx memory unit," but the information may be a table of any structure, or may be a neural network that generates an output for an input, or a learning model such as a genetic algorithm or random forest. In the following description, the structure of each table is an example, and one table may be divided into two or more tables, or two or more tables may all or partly be one table.

[0022] In a multi-stage switching system where connections are made via multiple exchanges connected by trunk lines capable of transmitting information, if a fault occurs in the target exchange or its trunk line and the connection is not possible, the line between the target exchange and an adjacent exchange that is directly connected to the target exchange on the route will be used. Normally, the adjacent exchange will recognize the fault, restrict calls to the target exchange, and send a call restriction voice guidance to the caller. In other words, even for outgoing calls that are subject to call restriction, the line to the adjacent exchange will be temporarily used, resulting in unnecessary traffic and a high line busy rate.

[0023] In order to solve this problem, the inventors have devised a system in which an adjacent exchange that detects a fault in a trunk line or exchange shares the fault information with predetermined adjacent exchanges that are to be notified, and the exchanges that share the fault information restrict calls to the trunk line or exchange where the fault has occurred, while providing voice guidance to the caller to restrict calls. This system prevents calls that should be restricted from using the line to the adjacent exchange, even temporarily, and thus avoids the generation of unnecessary traffic and a high rate of line busy.

[0024] 1 is a diagram showing an example of the configuration of a switching system using a switch according to a first embodiment of the present invention. A switch 100 is connected to a higher-level station 10 (hereinafter, the term "station" is used for convenience and specifically refers to a switch) and a lower-level station 200 on a route of the switching system that provides a switching service. Note that the lowest-level switch on the route is naturally not connected to any lower-level station, and similarly, the highest-level switch is naturally not connected to any higher-level station.

[0025] The upper station 10 and the lower station 200 basically have the same configuration as the exchange 100, so a description thereof will be omitted.

[0026] The exchange 100 includes a storage unit 110, a call control unit 120, a processing unit 130, and a communication unit 140. The storage unit 110 includes fault notification setting information 111 and connection status management information 112. The processing unit 130 includes a fault detection unit 131, a fault information sharing unit 132, a connection status management unit 133, and a call restriction voice guidance unit 134.

[0027] 2 is a diagram showing an example of the data structure of fault notification setting information. The fault notification setting information 111 stores zero or more notification target stations 111b in association with each fault-occurring station 111a. The fault-occurring station 111a is information that identifies the switch in which the occurrence of the fault was detected from the perspective of the switch 100. Even if the fault actually occurs in a trunk line between the switch 100 and the switch in which the occurrence of the fault was detected, the fault is treated as having been detected in the switch that is unable to directly communicate with the switch 100.

[0028] The notification target station 111b is information for specifying a switch to which the switch 100 will notify the occurrence of a failure when a failure is detected in the failure-occurring station 111a. It is possible to set multiple notification target stations 111b for the failure-occurring station 111a, and in that case, all of the notification target stations 111b will be targets to which the switch 100 will notify the occurrence of a failure.

[0029] 3 is a diagram showing an example of the data structure of the connection status management information. The connection status management information 112 stores a connection status 112b associated with each destination station 112a. The destination station 112a is information that identifies the destination exchange to which the exchange 100 sends a call.

[0030] The connection status 112b is information that specifies the connection status of the destination station 112a as seen from the exchange 100. The connection status 112b can include values ​​that indicate multiple states, but in this embodiment, it is treated as being able to take two values: "possible", which indicates that communication is possible, and "not possible", which indicates that communication is impossible.

[0031] The call control unit 120 has a multifunction telephone interface. Here, a multifunction telephone is a telephone connected to a telephone exchange, and in particular, a telephone that allows internal calls within the premises. The call control unit 120 controls the sending and receiving of internal calls by the telephone, and provides an exchange service.

[0032] The processing unit 130 performs various control and calculation processes. The fault detection unit 131 detects a communication fault between an adjacent switch subject to fault detection on the route of the switching service, and notifies the connection status management unit 133 of the fault.

[0033] When the fault information sharing unit 132 detects a communication fault, it shares fault information about the communication fault with a predetermined notification target exchange different from the fault detection target exchange.

[0034] 4 is a diagram showing an example of the data structure of a fault notification message. The fault notification message 113 is a message that the fault information sharing unit 132 transmits when sharing fault information about a communication fault with the switch to be notified. The fault notification message 113 includes a message header 113a, a message identification 113b, a fault-occurring station 113c, and a occurrence / recovery identification 113d.

[0035] The message header 113a is information required to send the fault notification message 113, such as destination information. The message identification 113b is identification information indicating that the message is fault information. The fault occurrence station 113c is information identifying the exchange in which the communication fault was detected. The occurrence / recovery identification 113d is information identifying whether a fault occurrence or recovery was detected.

[0036] The connection status management unit 133 manages the connection status with the exchange on the route of the exchange service.

[0037] When the fault-detected switch indicates a connection-disabled state in the connection state, the outgoing call restriction voice guidance unit 134 restricts calls to the fault-detected switch and transmits outgoing call restriction voice guidance to the caller.

[0038] The communication unit 140 communicates with other exchanges via trunk lines and sends and receives calls.

[0039] 5 is a diagram showing an example of the hardware configuration of an exchange 100. The exchange 100 includes a processor 101 such as a CPU (Central Processing Unit), a memory 102 such as a RAM (Random Access Memory), a storage 103 such as a hard disk or SSD (Solid State Drive), a communication device 104, a call control device 105, and a bus connecting these devices.

[0040] The fault notification setting information 111 and connection state management information 112 in the memory unit 110 are realized by the memory 102 or the storage 103. The call control unit 120 is realized by the call control device 105. The fault detection unit 131, fault information sharing unit 132, connection state management unit 133, and call restriction voice guidance unit 134 in the processing unit 130 are realized by the processor 101. The communication unit 140 is realized by the communication device 104.

[0041] The above is an example of the hardware configuration of the exchange 100 in this embodiment. However, the present invention is not limited to this, and the exchange 100 may be configured using other hardware. Although not shown, the exchange 100 includes well-known elements of a general computer, such as an OS, middleware, and applications.

[0042] [Explanation of Operation] Next, the operation of the exchange 100 in this embodiment will be explained.

[0043] 6 is a diagram showing an example of a notification sequence when a connection is normal. The notification sequence when a connection is normal is started by the exchange 100 periodically (for example, once every 30 seconds).

[0044] First, the fault detection unit 131 of the switch 100 polls the fault detection target station 1000, which is an adjacent switch to be detected for fault detection, on the path of the switching service to detect a communication fault between the switch 100 and the fault detection target station 1000 (step S001). Polling is realized by issuing a command from the switch 100 to the fault detection target station 1000 at regular intervals to request a response. A normal response to the polling indicates that the fault detection target station 1000 is operating normally.

[0045] When an alive notification (normal response) is received from the fault detection target station 1000 (step S002), the switch 100 determines whether the alive notification indicates that the fault detection target station 1000 has recovered from the fault state (step S003). Specifically, the fault detection unit 131 refers to the connection state 112b of the fault detection target station 1000 among the destination stations 112a in the connection state management information 112. If the connection state 112b is "unavailable," the fault detection unit 131 determines that the alive notification indicates recovery from the fault state. If the alive notification does not indicate recovery from the fault state, the fault detection unit 131 ends the notification sequence for normal connection.

[0046] If the alive notification indicates recovery from a failure state, the connection status management unit 133 updates the connection status (step S004). Specifically, first, the failure detection unit 131 notifies the connection status management unit 133. The connection status management unit 133 changes the connection status 112b of the failure detection target station 1000 to "OK".

[0047] Next, the fault information sharing unit 132 transmits a fault notification message 113 indicating recovery from the fault to the notification target station 2000 (step S005). Specifically, the fault information sharing unit 132 refers to the fault notification setting information 111, extracts the notification target station 111b when the fault-occurred station 111a is the fault-detected station 1000, and composes and transmits the fault notification message 113 to each of the notification target stations 2000.

[0048] In constructing the fault notification message 113, the fault information sharing unit 132 sets the notification target station 2000 of each of the notification target stations 111b in the destination information of the message header 113a. The fault information sharing unit 132 sets identification information indicating that the message is fault information in the message identification 113b. The fault information sharing unit 132 sets the fault detection target station 1000 in the fault occurrence station 113c. The fault information sharing unit 132 sets information specifying that recovery from the fault has been detected in the occurrence / recovery identification 113d.

[0049] Upon receiving the fault notification message 113, the connection status management unit 133 of the notification target station 2000 updates the connection status (step S006). Specifically, first, the fault information sharing unit 132 notifies the connection status management unit 133 of the reception of the fault notification message 113. The connection status management unit 133 changes the connection status 112b of the fault detection target station 1000 to "OK."

[0050] Next, the fault information sharing unit 132 transmits a fault notification message 113 indicating the recovery from the fault to the other notification target stations (step S007). Specifically, the fault information sharing unit 132 refers to the fault notification setting information 111, extracts the notification target station 111b when the fault-occurring station 111a is the fault-detection target station 1000, changes the destination information of the message header 113a to the notification target station, and transfers the fault notification message 113 to each of them.

[0051] The above is an example of the notification sequence during normal connection. According to this example of the notification sequence during normal connection, when there is an alive notification from the fault detection target station 1000, if the station has recovered from the fault state, a fault recovery message notifying the notification target station of the recovery can be sent, and fault recovery information and the connection state can be shared.

[0052] 7 is a diagram showing an example of a notification sequence when an abnormal connection occurs. The notification sequence when an abnormal connection occurs is started by the exchange 100 periodically (for example, once every 30 seconds).

[0053] First, the polling in step S001 is the same as the notification sequence when a normal connection is made.

[0054] If a timeout occurs without an alive notification (normal response) from the fault detection target station 1000, or if an abnormality notification is received, the switch 100 detects the occurrence of a fault in the fault detection target station 1000 (step S101).

[0055] If a failure is detected, the connection status management unit 133 updates the connection status (step S102). Specifically, first, the failure detection unit 131 notifies the connection status management unit 133. The connection status management unit 133 changes the connection status 112b of the failure detection target station 1000 to "unavailable."

[0056] Next, the fault information sharing unit 132 composes a fault notification message 113 indicating the detection of a fault occurrence (step S103). Specifically, the fault information sharing unit 132 refers to the fault notification setting information 111, extracts the notification target station 111b when the fault-occurring station 111a is the fault detection target station 1000, and composes a fault notification message 113 for each of the notification target stations 111b as the notification target station 2000.

[0057] In constructing the fault notification message 113, the fault information sharing unit 132 sets the notification target station 2000 of each of the notification target stations 111b in the destination information of the message header 113a. The fault information sharing unit 132 sets identification information indicating that the message is fault information in the message identification 113b. The fault information sharing unit 132 sets the fault detection target station 1000 in the fault occurrence station 113c. The fault information sharing unit 132 sets information specifying that the occurrence of a fault has been detected in the occurrence / recovery identification 113d.

[0058] Then, the fault information sharing unit 132 transmits the constructed fault occurrence message (fault notification message 113) to the notification target stations 2000 (step S104). Specifically, the fault information sharing unit 132 transmits the fault notification message 113 constructed in step S103 to each of the notification target stations 2000.

[0059] Upon receiving the fault notification message 113, the connection status management unit 133 of the notification target station 2000 updates the connection status (step S105). Specifically, first, the fault information sharing unit 132 notifies the connection status management unit 133 of the reception of the fault notification message 113. The connection status management unit 133 changes the connection status 112b of the fault detection target station 1000 to "unavailable."

[0060] Next, the fault information sharing unit 132 transmits a fault notification message 113 indicating the occurrence of a fault to the other notification target stations (step S106). Specifically, the fault information sharing unit 132 refers to the fault notification setting information 111, extracts the notification target station 111b when the fault-occurred station 111a is the fault-detected station 1000, changes the destination information of the message header 113a to the notification target station, and transfers the fault notification message 113 to each of them.

[0061] The above is an example of the notification sequence when an abnormal connection occurs. According to this example of the notification sequence when an abnormal connection occurs, if there is no alive notification or an abnormality notification from the fault detection target station 1000, a fault occurrence message notifying the target station of the occurrence of a fault can be sent to the target station, and fault recovery information and connection status can be shared.

[0062] 8 is a diagram showing an example of a processing sequence when a call is sent. Typically, this is the processing when a call is made from a non-notification target station 3000 adjacent to the exchange 100 on the path to the station 1000 targeted for fault detection, or when a call is made from a telephone connected to the exchange 100 itself to the station 1000 targeted for fault detection. This example sequence is an example when a call is made from a non-notification target station 3000 adjacent to the exchange 100 on the path to the station 1000 targeted for fault detection.

[0063] First, the exchange 100 receives a dial addressed to the fault detection target station 1000 from the call control unit 120 of the non-notification target station 3000 (step S201). Then, the outgoing call restriction voice guidance unit 134 of the exchange 100 checks the connection status of the destination station (step S202). Specifically, the outgoing call restriction voice guidance unit 134 requests the connection status management unit 133 to check whether the connection status 112b of the fault detection target station 1000 is "OK" or "NG."

[0064] If the connection status 112b of the fault detection target station 1000 is "connected", the call control unit 120 transmits a dial command addressed to the fault detection target station 1000 to an adjacent exchange (step S203).

[0065] If the connection status 112b of the fault detection target station 1000 is "unavailable", the outgoing call restriction voice guidance unit 134 restricts calls addressed to the exchange (fault detection target station 1000) that indicates the connection unavailable state, and transmits outgoing call restriction voice guidance to the caller (not-notified station 3000) (step S204).

[0066] The above is an example of the processing sequence when a call is sent. According to this example of the processing sequence when a call is sent, if the connection status of the fault detection target station 1000 at the call destination is "unavailable," the switch in question can transmit a call restriction voice guidance to the call source (not-notified station 3000). In other words, it can be said that call restriction can be performed automatically without waiting for the call to reach an adjacent switch on the route to the fault detection target station 1000 at the call destination, and without the intervention of an administrator or the like. This prevents outgoing calls that should be restricted from using the line to the adjacent switch even temporarily, avoiding the generation of unnecessary traffic and preventing high line busy rates.

[0067] [Explanation of Configuration Example] Next, a configuration example of a switching system using the switching equipment 100 according to this embodiment will be described.

[0068] 9 is a diagram showing an example of the configuration of a tree-type switch network. The tree-type switch network 500 includes switch A 510, switch B 520, switch C 521, switch D 522, switch E 523, and switch F 530. Switch B 520 and switch F 530 are connected by trunk lines as lower-level switches of the top-level switch A 510, and there is no direct trunk line between switch B 520 and switch F 530. Switch C 521 and switch E 523 are connected by trunk lines as lower-level switches of switch B 520, and there is no direct trunk line between switch C 521 and switch E 523. Switch D 522 is connected by a trunk line as a lower-level switch of switch C 521. In the tree-type switch network 500, when a switch originates a call to another office, it uses a route via a higher-level switch. On the other hand, when a fault notification message 113 is sent, this is not the case.

[0069] As shown in the figure, fault notification setting information 520A and connection status management information 520B are stored in the storage unit 110 of the exchange B 520. The fault notification setting information 520A includes information specifying that when the exchange A 510 becomes a faulty station, the exchange C 521 and the exchange E 523 are to be notified stations of a fault notification message, when the exchange C 521 becomes a faulty station, information specifying that when the exchange C 521 becomes a faulty station, the exchange A 510 and the exchange E 523 are to be notified stations of a fault notification message, and information specifying that when the exchange E 523 becomes a faulty station, the exchange A 510 and the exchange C 521 are to be notified stations of a fault notification message.

[0070] The connection status management information 520B also includes the connection status ("OK" when no failure occurs) of the exchange A510, exchange C521, exchange D522, exchange E523, and exchange F530.

[0071] Similarly, as shown in the drawing, the storage unit 110 of the exchange C 521 stores fault notification setting information 521A and connection status management information 521B. The fault notification setting information 521A includes information specifying that when the exchange B 520 becomes a fault-occurring station, the exchange D 522 is to be the station to be notified of a fault notification message, and information specifying that when the exchange D 522 becomes a fault-occurring station, the exchange B 520 is to be the station to be notified of a fault notification message.

[0072] The connection status management information 521B also includes the connection status ("OK" when no failure occurs) of the exchange A510, exchange B520, exchange D522, exchange E523, and exchange F530.

[0073] In this configuration example, the notification sequence at the time of the abnormal connection will be specifically described using an example in which a fault occurs in the trunk line between the exchange B520 and the exchange A510.

[0074] First, the fault detection unit 131 of the exchange B520 detects the occurrence of a fault between the exchange B520 and the exchange A510 when a timeout occurs without a live notification (normal response) being sent from the exchange A510, which is the fault detection target station 1000 (corresponding to step S101).

[0075] Then, the connection status management unit 133 updates the connection status of the exchange A 510 (corresponding to step S102). Specifically, the connection status management unit 133 changes the connection status of the exchange A 510 from "OK" to "NO" in the connection status management information 520B.

[0076] Next, the fault information sharing unit 132 composes a fault notification message 113 indicating that a fault has been detected in the exchange A 510 (corresponding to step S103). Specifically, the fault information sharing unit 132 refers to the fault notification setting information 520A, extracts the exchange C 521 and the exchange E 523 as stations to be notified when the exchange A 510 becomes the station where the fault has occurred, and composes a fault notification message 113 for each of them.

[0077] In configuring the fault notification message 113, the fault information sharing unit 132 generates a fault notification message addressed to the exchange C 521 and a fault notification message addressed to the exchange E 523. The destination information in the message header 113a is set to the exchange C 521 and the exchange E 523, respectively. The fault information sharing unit 132 sets identification information indicating that the message is fault information in the message identification 113b. The fault information sharing unit 132 sets the exchange A 510 in the fault-occurring station 113c. The fault information sharing unit 132 sets information specifying that a fault has been detected in the occurrence / recovery identification 113d.

[0078] Then, the fault information sharing unit 132 transmits the constructed fault occurrence message (fault notification message 113) to each of the exchange C 521 and the exchange E 523 (corresponding to step S104).

[0079] When the connection status management units 133 of the exchanges C521 and E523, which correspond to the notification target station 2000, receive the fault notification message 113, they update their connection status (corresponding to step S105). Here, an example will be described for the exchange C521, but similar processing is also performed for the exchange E523. Specifically, the connection status management unit 133 changes the connection status of the exchange A510 from "OK" to "NOT OK" in the connection status management information 521B.

[0080] Next, the fault information sharing unit 132 transmits a fault notification message 113 indicating the occurrence of a fault to the exchange D 522, which is the station to be notified when the fault notification message 113 is received from the exchange B 520 (corresponding to step S106). Specifically, the fault information sharing unit 132 refers to the fault notification setting information 521A, extracts the exchange D 522 as the station to be notified, changes the destination information of the message header 113a to the exchange D 522, and transfers the fault notification message 113.

[0081] The above is an example of a notification sequence in the event of an abnormal connection. In this example, when exchange B 520 detects that connection with exchange A 510 is not possible, this fault information is automatically shared with exchanges C 521 and D 522. That is, in exchanges B 520, C 521, and D 522, the connection status of exchange A 510 is changed to "unavailable" in their respective connection status management information.

[0082] Therefore, in any of the exchanges B520, C521, and D522, in the processing sequence when a call is sent, the outgoing call restriction voice guidance unit 134 can restrict calls with the destination being an exchange (exchange A510) that is in a state where it cannot be connected, and transmit outgoing call restriction voice guidance to the caller (corresponding to step S204).

[0083] The above is the exchange, the exchange system using the exchange, and the line control method according to the first embodiment. The exchange, the exchange system using the exchange, and the line control method according to the first embodiment can prevent outgoing calls that should be subject to outgoing call restriction from using the line to an adjacent exchange even temporarily, thereby avoiding the generation of unnecessary traffic and preventing the line busy rate from remaining high.

[0084] [Second Embodiment] In the exchange, exchange system using the exchange, and line control method according to the first embodiment, when a fault occurs in one of the exchanges constituting the exchange system, calls addressed to that exchange can be restricted and a call restriction voice guidance can be sent to the caller. However, when the exchanges are connected in a multi-stage structure such as a tree structure or a star structure, there is room for improvement in the possibility that some exchanges may be subject to similar call restriction in response to a fault in one of the exchanges. Conversely, there is room for consideration that in the case of a trunk line fault, if a route other than the route using the trunk line is set, it may not be necessary to uniformly restrict calls in response to the fault.

[0085] The exchange according to the second embodiment, which has been improved in this way, and the exchange system and line control method using the exchange, will be described below. Note that the exchange according to the second embodiment, the exchange system and line control method using the exchange, and the line control method are basically similar to the exchange according to the first embodiment, and therefore differences will be mainly described.

[0086] First, the processing unit 130 of the exchange 100 according to the second embodiment will be described. When a communication failure is detected, the fault information sharing unit 132 includes the exchange that is the target of fault detection and an exchange that is in an unconnectable state in the fault information of the communication failure and shares it. Note that when the exchange that is the target of fault detection related to the communication failure is an exchange that is located at a higher position on the path of the exchange service, the fault information sharing unit 132 does not share the fault information of the communication failure with exchanges that are located at a lower position on the path of the exchange service among predetermined notification target exchanges that are different from the exchange that is the target of fault detection.

[0087] When fault information of a communication fault is shared with the connection status management unit 133 from a transit exchange that is an adjacent exchange on the route of the exchange service, the connection status management unit 133 updates the connection status of the exchange that is the subject of fault detection related to the communication fault. Furthermore, when a communication fault is detected, the connection status management unit 133 updates the connection status of not only the exchange that is the subject of fault detection but also exchanges that are not connectable on the route of the exchange service, by treating them as not connectable exchanges. Furthermore, when fault information of a communication fault is shared with the connection status management unit 133 from a transit exchange that is an adjacent exchange on the route of the exchange service, the connection status management unit 133 updates the connection status of the exchange that is the subject of fault detection and exchanges that are not connectable on the route related to the fault information according to the transit exchange (i.e., the route).

[0088] When fault information is shared by any of the transit exchanges, the call restriction voice guidance unit 134 restricts calls to the exchange related to the fault information and transmits call restriction voice guidance to the call originator.

[0089] 10 is a diagram showing an example of the data structure of fault notification setting information according to the second embodiment. The fault notification setting information 111' according to the second embodiment includes an item (first connection-disabled station 111c to Nth connection-disabled station 111d) for setting a plurality (N: integer) of connection-disabled stations for each faulty station 111a. The purpose of providing the item for setting connection-disabled stations is to enable the setting of all calls to be restricted at once in a configuration in which, when a fault occurs in a faulty station, calls to all of its subordinate exchanges should be restricted. For example, the purpose is to restrict all calls destined for exchanges that can be connected to other exchanges only via the faulty station 111a.

[0090] 11 is a diagram showing an example of the data structure of connection status management information according to the second embodiment. The connection status management information 112' according to the second embodiment includes, for the destination office 112a, a connection status according to the notification path (intermediate exchange) of the fault notification. The purpose of including the connection status according to the notification path (intermediate exchange) of the fault notification is to control this more precisely, even if a fault is detected in the faulty office, or even if the fault actually occurs in a trunk line, as long as the faulty office is connected to another normal exchange via a trunk line, and there is a case where connection is possible via a path that goes through the other normal exchange. For example, if there are multiple paths connecting to the exchange of the faulty office, the purpose is to make the line available if any of the paths is connectable.

[0091] Furthermore, when multiple routes are used to connect to the failed station, there is a possibility that a fault notification message will be received for each route. In particular, in the case of a trunk line fault, if the exchanges connected by the trunk line are target stations for fault detection, each exchange may detect that a fault has occurred in the other exchange and send a fault notification to the other exchange. This is to prevent an exchange that receives both fault notifications from mistaking the connection status as if both exchanges connected by the trunk line are experiencing faults.

[0092] 12 is a diagram showing an example of the data structure of a fault notification message according to the second embodiment. Since the fault notification setting information 111' according to the second embodiment now allows the setting of an item for setting a non-connectable station, the fault notification message 113' according to the second embodiment is configured to include information on multiple non-connectable stations as faulty stations. That is, the fault notification message 113' includes the number of notified stations 113e and a fault occurrence / recovery identification 113d for each first faulty station 113c'. Furthermore, if there are non-connectable stations, the message also includes information on (second to Mth) faulty stations 113f, 113h and fault occurrence / recovery identifications 113g, 113j according to the number of non-connectable stations.

[0093] 13 is a diagram showing an example of a notification sequence at the time of normal connection according to the second embodiment. In the example of the notification sequence at the time of normal connection according to the second embodiment, after step S003 is performed, if the alive notification indicates recovery from a failure state, the connection status management unit 133 updates the connection status of each station (step S004'). Specifically, first, the failure detection unit 131 notifies the connection status management unit 133. The connection status management unit 133 changes the connection status 112b of the failure detection target station 1000 to "possible". At the same time, the connection status management unit 133 also changes the connection status 112b of the connection-disabled station to "possible".

[0094] Furthermore, in the configuration of the fault notification message 113, the fault information sharing unit 132 sets the sum of the fault detection target station 1000 and the connection-incapable stations as the number of notified stations 113e. The fault information sharing unit 132 sets the fault detection target station 1000 as the first fault occurrence station 113c'. The fault information sharing unit 132 sets information specifying that recovery from the fault has been detected as the occurrence / recovery identification 113d. Furthermore, the fault information sharing unit 132 sets the second fault occurrence station 113f through the Mth fault occurrence station 113h for each connection-incapable station, and sets information specifying that recovery from the fault has been detected as the occurrence / recovery identification 113g and 113j.

[0095] Then, upon receiving the fault notification message 113, the connection status management unit 133 of the notification target station 2000 updates the connection status of each station (step S006'). Specifically, first, the fault information sharing unit 132 notifies the connection status management unit 133 of the reception of the fault notification message 113. The connection status management unit 133 changes the connection status 112b of the fault detection target station 1000 to "connectable". At the same time, the connection status management unit 133 also changes the connection status 112b of the connection-incompatible stations to "connectable".

[0096] The above is an example of the notification sequence at the time of normal connection according to the second embodiment. According to the example of the notification sequence at the time of normal connection according to the second embodiment, when there is an alive notification from the fault detection target station 1000, if the station has recovered from the fault state, a fault recovery message notifying the notification target station of the recovery is sent, and fault recovery information and connection status can be shared even with the station that cannot be connected.

[0097] 14 is a diagram showing an example of a notification sequence at the time of an abnormal connection according to the second embodiment. In the example of the notification sequence at the time of an abnormal connection according to the second embodiment, when a failure is detected in step S101, the connection status management unit 133 updates the connection status including the connection-disabled station (step S102'). Specifically, the connection status management unit 133 changes the connection status 112b of the failure detection target station 1000 to "unavailable." At the same time, the connection status management unit 133 also changes the connection status 112b of the connection-disabled station to "unavailable."

[0098] Next, the fault information sharing unit 132 composes a fault notification message 113 including the connection-disabled station (step S103'). Specifically, the fault information sharing unit 132 refers to the fault notification setting information 111, extracts the notification target station 111b when the fault-occurred station 111a is the fault detection target station 1000, and composes a fault notification message 113 for each of them as the notification target station 2000.

[0099] In the configuration of the fault notification message 113, the number of notified stations 113e is set to the sum of the fault detection target station 1000 and the connection-incapable stations. The fault information sharing unit 132 sets the fault detection target station 1000 as the first fault occurrence station 113c'. The fault information sharing unit 132 sets information specifying that a fault has been detected as the occurrence / recovery identification 113d. Furthermore, the fault information sharing unit 132 sets the second fault occurrence station 113f to the Mth fault occurrence station 113h for each connection-incapable station, and sets information specifying that a fault has been detected as the occurrence / recovery identification 113g and 113j.

[0100] When the connection status management unit 133 of the notification target station 2000 receives the fault notification message 113, it updates the connection status for each notification path (step S105'). Specifically, first, the fault information sharing unit 132 notifies the connection status management unit 133 of the reception of the fault notification message 113. The connection status management unit 133 changes either the connection status 112c or 112d in which the switch 100 of the fault detection target station 1000 is used as a transit switch to "unavailable." At the same time, the connection status management unit 133 also changes the connection status 112b of the connection-unavailable station to "unavailable."

[0101] The above is an example of the notification sequence at the time of an abnormal connection according to the second embodiment. According to the example of the notification sequence at the time of an abnormal connection according to the second embodiment, if there is no alive notification or an abnormality notification from the fault detection target station 1000, a fault occurrence message is sent to the notification target station to notify the occurrence of a fault for each path, and the fault occurrence information and connection status can be shared even with the non-connectable station.

[0102] 15 is a diagram showing an example of a processing sequence when a call is sent according to the second embodiment. In an example of a notification sequence when a call is sent according to the second embodiment, after step S201, the outgoing call restriction voice guidance unit 134 of the exchange 100 checks the connection status of each path to the destination office (step S202'). Specifically, the outgoing call restriction voice guidance unit 134 requests the connection status management unit 133 to identify whether the connection status 112b of each path (passing exchange) for the fault detection target office 1000 is "OK" or "NG" and determines whether any path has a connection status of "OK".

[0103] If the connection status 112b of the fault detection target station 1000 is "OK" on any of the routes, the call control unit 120 transmits a dial command addressed to the fault detection target station 1000 to an adjacent exchange (step S203').

[0104] If there is no fault detection target station 1000 whose connection status 112b is "OK" on any of the routes, the call restriction voice guidance unit 134 restricts calls addressed to the exchange (fault detection target station 1000) that indicates an unconnectable state, and transmits call restriction voice guidance to the caller (non-notification target station 3000) (step S204').

[0105] The above is an example of the processing sequence when a call is sent according to the second embodiment. According to the example of the processing sequence when a call is sent according to the second embodiment, if the connection status is "unavailable" for all of the routes to the fault detection target station 1000 of the call destination, the switch in question can transmit a call restriction voice guidance to the call source (not-notified station 3000). Furthermore, call restriction can be automatically implemented for switches that are appropriate to be similarly restricted in response to a fault in the switch of the fault detection target station 1000. Conversely, when multiple routes are set that are expected to use different transit switches, there is no need to uniformly restrict calls in response to the occurrence of a fault if connection is possible via any of the routes, and therefore excessive call restriction can be avoided.

[0106] [Explanation of Configuration Example] Next, a configuration example of a switching system using the switching equipment 100 in the second embodiment will be explained.

[0107] 16 is a diagram showing an example of the configuration of a tree-type switch network according to the second embodiment. The tree-type switch network 600 according to the second embodiment includes a switch A610, a switch B620, a switch C621, a switch D622, a switch E623, a switch F630, a switch G624, and a switch H625. The switches B620 and F630 are lower-level switches of the top-level switch A610 and are connected by trunk lines, with no direct trunk line between the switches B620 and F630. The switch C621 is lower-level switch of the switch B620 and is connected by a trunk fiber. The switch E623 is lower-level switch of the switch B620 and F630 and is connected by trunk lines, with no direct trunk line between the switches C621 and E623. The exchange D622 is connected by a trunk line as a lower exchange of the exchange C621. The exchange G624 and the exchange H625 are connected by a trunk line as lower exchanges of the exchange E623, and there is no direct trunk line between the exchange G624 and the exchange H625.

[0108] In the tree-type switch network 600 according to the second embodiment, when a switch originates a call to another station, a route via a higher-level switch is adopted. However, when a fault notification message 113 is transmitted, this is not the case.

[0109] Here, the storage unit 110 of the exchange B 620 stores fault notification setting information 620A and connection state management information 620B as shown in FIG.

[0110] 17 is a diagram showing an example of data held by an exchange according to the second embodiment. The fault notification setting information 620A includes information specifying that when the exchange A610 becomes a faulty station, the exchange C621 and the exchange E623 are to be notified of a fault notification message, information specifying that when the exchange C621 becomes a faulty station, the exchange A610 and the exchange E623 are to be notified of a fault notification message, and information specifying that when the exchange E623 becomes a faulty station, the exchange A610 and the exchange C621 are to be notified of a fault notification message.

[0111] The fault notification setting information 620A also includes information that if exchange C621 becomes a faulty station, exchange D622 will become a station that cannot be connected, and that if exchange E623 becomes a faulty station, exchange G624 and exchange H625 will become stations that cannot be connected.

[0112] The connection status management information 620B also includes the connection status ("OK" if no failure has occurred) of the exchange A610, exchange C621, exchange D622, exchange E623, exchange F630, exchange G624 and exchange H625.

[0113] The connection state management information 620B also includes two notification paths for the exchange F630: one for when the transit exchange is the exchange A610, and the other for when the transit exchange is the exchange E623.

[0114] 18 is a diagram showing an example of data held by another exchange according to the second embodiment. The storage unit 110 of the exchange C621 stores fault notification setting information 621A and connection state management information 621B.

[0115] The fault notification setting information 621A includes information specifying that if the exchange B620 becomes the fault-occurring station, the exchange D622 will be the station to be notified of the fault notification message, and information specifying that if the exchange D622 becomes the fault-occurring station, the exchange B620 will be the station to be notified of the fault notification message.

[0116] The fault notification setting information 621A also includes information that if the exchange B620 becomes a faulty station, the exchange A610, exchange F630, exchange E623, exchange G624, and exchange H625 will become stations that cannot be connected.

[0117] The connection status management information 620B includes the connection status ("OK" if no failure has occurred) of the exchange A610, exchange B620, exchange D622, exchange E623, exchange F630, exchange G624 and exchange H625.

[0118] 19 is a diagram showing an example of data held in yet another exchange according to the second embodiment. The storage unit 110 of the exchange E623 stores fault notification setting information 623A and connection state management information 623B.

[0119] The fault notification setting information 623A includes information specifying that, when the exchange B620 becomes a faulty station, the exchanges F630, G624, and H625 are to be the notification target stations of a fault notification message. The fault notification setting information 623A also includes information specifying that, when the exchange F630 becomes a faulty station, the exchanges B620, G624, and H625 are to be the notification target stations of a fault notification message. The fault notification setting information 623A also includes information specifying that, when the exchange G624 becomes a faulty station, the exchanges B620, F630, and H625 are to be the notification target stations of a fault notification message. The fault notification setting information 623A also includes information specifying that, when the exchange H625 becomes a faulty station, the exchanges B620, F630, and G624 are to be the notification target stations of a fault notification message.

[0120] The connection status management information 623B also includes the connection status ("OK" if no failure has occurred) of the exchange A610, exchange B620, exchange C621, exchange D622, exchange F630, exchange G624 and exchange H625.

[0121] The connection state management information 623B also includes two notification paths for the exchange A610: one for when the transit exchange is the exchange B620, and the other for when the transit exchange is the exchange F630.

[0122] By setting and storing these retained data values, it becomes possible to change the scope of influence of the fault response and more efficiently suppress the line busy rate.

[0123] For example, FIG. 20 shows an example of settings for exchanges C621 and E623 to suppress the impact of a failure in an exchange further upstream than the upstream exchanges B620 and F630 on calls between the downstream exchanges D622, G624, and H625.

[0124] 20 is a diagram showing an example of modification of data held by an exchange according to the second embodiment. By deleting (setting to null) from fault notification setting information 621A of exchange C621 exchange A610, exchange F630, exchange E623, exchange G624, exchange H625, which are set as stations that cannot be connected in the event that exchange B620 becomes a station where a fault has occurred, and exchange D622, which is set as a station to be notified, exchange C621 will not share with exchange D622 fault information of exchanges higher than exchange B620.

[0125] Therefore, exchange D622 does not share failures in exchanges higher than exchange B620, nor does it share exchanges that cannot be connected. In other words, calls from exchange D622 to exchanges G624 and H625 can be made without restrictions. However, this does not apply when exchange C621 cannot be connected to exchange B620 (when a failure has occurred in the trunk line to exchange B620 or in exchange B620), or when a failure has occurred on the route from exchange D622 to exchange G624 and exchange H625 (exchange C621, exchange B620, exchange E623, exchange G624, or exchange H625). In such cases, calls are restricted by exchange C621, etc.

[0126] Furthermore, the exchange G624 and the exchange H625, which are set as stations to be notified when the exchange B620 and the exchange F630 become fault-occurring stations, are deleted (nulled) from the fault notification setting information 623A of the exchange E623. Furthermore, the exchange H625, which is set as a station to be notified when the exchange G624 becomes a fault-occurring station, and the exchange G624, which is set as a station to be notified when the exchange H625 becomes a fault-occurring station, are deleted (nulled) from the fault notification setting information 623A of the exchange E623. As a result, the exchange G624 and the exchange H625 do not share fault information of exchanges higher than the exchange B620 and the exchange F630 with the exchange E623, and the exchanges G624 and H625 do not share each other's fault information with the exchange E623. In other words, calls can be made from exchange G624 and exchange H625 to exchange D622 without any restrictions.

[0127] The above is the exchange, the exchange system using the exchange, and the line control method according to the second embodiment. The exchange, the exchange system using the exchange, and the line control method according to the second embodiment can minimize the impact of failures as much as possible, avoiding the generation of unnecessary traffic and preventing high line busy rates. Specifically, when exchanges are connected in a multi-stage structure such as a tree structure or a star structure, it is possible to provide an exchange that is suitable for similarly restricting outgoing calls in response to a failure in one exchange. Conversely, in the event of a trunk line failure, if a route other than the route using the trunk line is set, it is possible to avoid uniformly restricting outgoing calls to exchanges that would otherwise be connectable in response to the failure.

[0128] Although the present invention has been specifically described using the embodiments, it goes without saying that the present invention is not limited to these embodiments and can be modified in various ways without departing from the spirit of the present invention. For example, the exchange is not limited to typical topologies such as a tree or star topology, but may be configured in multiple stages. Note that the above-mentioned embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the described configurations.

[0129] Furthermore, the above-mentioned configurations, functions, processing units, etc. may be partially or entirely realized in hardware, for example, by designing them as integrated circuits. Furthermore, the control lines and information lines shown are those considered necessary for the explanation, and do not necessarily represent all control lines and information lines in the product. In reality, it can be assumed that almost all configurations are interconnected.

[0130] Furthermore, the configurations, functions, processing units, etc. of the exchange 100 described above may be partly or entirely implemented in a secure distributed system by, for example, executing them in separate devices for integrated processing.

[0131] Furthermore, the technical elements of the above-described embodiments may be applied independently, or may be divided into multiple parts such as program parts and hardware parts and applied.

[0132] The present invention has been described above mainly with reference to the embodiments. [Explanation of symbols]

[0133] 10: Upper station, 100: Exchange, 110: Memory unit, 111: Fault notification setting information, 112: Connection status management information, 120: Call control unit, 130: Processing unit, 131: Fault detection unit, 132: Fault information sharing unit, 133: Connection status management unit, 134: Call restriction voice guidance unit, 140: Communication unit, 200: Lower station.

Claims

1. a call control unit that provides switching services; a connection status management unit that manages a connection status with an exchange on a path of the exchange service; a fault detection unit that detects a communication fault between an adjacent fault detection target exchange on a path of the exchange service and notifies the connection status management unit; a fault information sharing unit which, when detecting the communication fault, shares fault information of the communication fault with a predetermined notification target exchange different from the fault detection target exchange; a call restriction voice guidance unit that restricts calls to the fault-detected exchange and transmits call restriction voice guidance to a caller when the fault-detected exchange indicates a connection-disabled state in the connection state; An exchange comprising:

2. 2. The switch of claim 1, when fault information of the communication fault is shared with the connection status management unit from a transit exchange that is an adjacent exchange on the route of the exchange service, the connection status management unit updates the connection status of the fault detection target exchange related to the communication fault. An exchange characterized by:

3. 3. The exchange according to claim 1 or 2, when the communication failure is detected, the connection status management unit updates the connection status of the switch subject to failure detection and the switch that is not connectable on the route of the switching service by indicating that the switch is in a connectable state; when the communication failure is detected, the failure information sharing unit includes the switch subjected to failure detection and the switch in an unconnectable state in the failure information of the communication failure and shares the information. An exchange characterized by:

4. 3. The exchange according to claim 2, when fault information of the communication fault is shared from a transit exchange which is an adjacent exchange on the route of the exchange service, the connection status management unit updates the connection status of the fault detection target exchange related to the fault information in accordance with the transit exchange; when the fault information is shared by any of the transit exchanges, the call restriction voice guidance unit restricts calls to the exchange related to the fault information and transmits a call restriction voice guidance to the caller. An exchange characterized by:

5. The exchange according to any one of claims 1 to 4, when the fault detection target exchange relating to the communication fault is an exchange positioned at a higher position on the route of the switching service, the fault information sharing unit does not share fault information of the communication fault with an exchange positioned at a lower position on the route of the switching service among predetermined notification target exchanges different from the fault detection target exchange. An exchange characterized by:

6. A line control method in an exchange system in which a plurality of exchanges are connected in multiple stages to provide exchange services, comprising: the exchange comprises a processor, a call control unit that provides the exchange service, and a connection status management unit that manages a connection status with an exchange on a path of the exchange service; The processor: a fault detection step of detecting a communication fault between an adjacent fault detection target exchange on a path of the exchange service and notifying the connection status management unit; a fault information sharing step of, when detecting the communication fault, sharing fault information of the communication fault with a predetermined notification target exchange different from the fault detection target exchange; a call restriction voice guidance step of restricting calls to the fault-detected exchange and transmitting call restriction voice guidance to a caller when the fault-detected exchange indicates a connection-disabled state in the connection state; A line control method characterized by carrying out the above.

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