JP5545887B2 - Distributed recovery method and network system - Google Patents

Description

  The present invention relates to a technique for distributing and accommodating terminals accommodated in a failed call control server among a plurality of other call control servers.

  In the Next Generation Network (NGN), as a remedy when a failure occurs in the call control server that accommodates the subscriber (terminal), the subscriber controlled by the call control server is called another call. It will be necessary to migrate to the control server. In this case, it is important to shift the service to subscribers without interruption.

  For example, Patent Document 1 discloses a technique for performing a subscriber migration from a call control server to a new call control server so that the service is not interrupted. In Patent Document 1, when a subscriber is transferred from a call processing device used so far to a new call processing device, service contract information and the like necessary for call processing stored in the call processing device so far Is transferred to a new call processing device.

JP 2010-193367 A

  However, the technique of Patent Document 1 is a technique based on the premise of migration of a specific subscriber controlled by a certain call processing device, and all subscribers controlled by the call processing device in which the failure has occurred are migrated. In such a case, since it is necessary to transfer a large amount of subscriber data to the transfer destination call processing device, it takes time to restore the service due to an increase in network load, an increase in the load of the transfer destination call processing device, and the like. In addition, there is an effect (increase in delay) on normal call processing.

  In addition, cited document 1 is intended to transfer a shortage of processing due to an increase in the number of subscribers controlled by a specific call processing device to another call processing device having sufficient processing capacity. The failure of the processing equipment is not considered.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to shorten the recovery time and reduce the processing load on the destination call control server when a failure occurs in the call control server. There is to do.

In order to achieve the above object, the present invention provides a distributed restoration method for distributing and accommodating terminals accommodated in a faulty call control server in a plurality of call control servers, which is performed by a network system. system includes a plurality of call control server, and a subscriber data server storing the subscriber data of all the terminals of the network system, each of the other plurality of call control server is received in the call control server A determination unit for determining whether or not subscriber data corresponding to the terminal exists in the storage unit when receiving a communication request from the terminal, and having a storage unit for storing subscriber data of the terminal being If not present in the storage unit, a terminal device that transmitted the communication request is not controlled by its own call control server, when a communication request dispersion housing due to failure And another, the requesting subscriber data of the terminal to the subscriber data server, performs an acquiring step of storing subscriber data sent to the storage unit from the subscriber data server, the subscriber data server Has a subscriber database that holds subscriber data of terminals accommodated in the edge router in units of edge routers connected to each call control server , and each request of the other plurality of call control servers A transmission step of extracting the subscriber data of all terminals accommodated in the edge router accommodating the terminal of the requested subscriber data from the subscriber database and transmitting it to the call control server of the request source. Do.
Further, the present invention is a distributed recovery method for distributing and accommodating terminals accommodated in a faulty call control server performed by a network system to other call control servers, wherein the network system includes a plurality of A call control server; a subscriber data server for storing subscriber data of all terminals of the network system; and a monitoring server. When the monitoring server detects a failure of the call control server, the monitoring server accommodates the call control server. Notifying each edge router that has been assigned the address of the switching destination call control server, and instructing the routing destination call control server to route the communication originating from the terminal accommodated in the edge router Each of the other plurality of call control servers performs subscriber data of a terminal accommodated in the call control server. A storage unit for storing, and upon receiving a communication request from a terminal, a determination step for determining whether or not subscriber data corresponding to the terminal exists in the storage unit; and The terminal that transmitted the communication request is a terminal that is not controlled by the own call control server, and is determined to be a communication request for distributed accommodation accompanying the occurrence of a failure, and the subscriber data of the terminal is stored in the subscriber data server. Requesting and storing the subscriber data transmitted from the subscriber data server in the storage unit, and the subscriber data server is a unit of edge router connected to each call control server, A subscriber database that holds subscriber data of terminals accommodated in the edge router, and in response to requests from each of the other plurality of call control servers, an end of the requested subscriber data The subscriber data of all the terminal accommodated in the edge router that accommodates the said extracted from the subscriber database, performs transmission step of transmitting to the requesting call control server.

The present invention is a network system for accommodating terminals accommodated in a faulty call control server in a distributed manner among a plurality of other call control servers, the network system including a plurality of call control servers, and a subscriber data server storing the subscriber data of all terminals of the network system, each of the other plurality of call control server, storage for storing subscriber data of the terminal accommodated in the call control server When the communication request from the terminal and the terminal is received, it is determined whether or not the subscriber data corresponding to the terminal exists in the storage means. If the terminal does not exist in the storage means, the terminal that transmitted the communication request a terminal that is not controlled by its own call control server, it is determined that the communication request dispersion housing due to failure, the subscriber data of the terminal to the subscriber data server Requesting, has an acquisition means for storing in said memory means subscriber data transmitted from the subscriber data server, the subscriber data server, the unit of the edge router connected to the call control server And a subscriber database that holds subscriber data of the terminal accommodated in the edge router, and an edge that accommodates the terminal of the requested subscriber data in response to each request of the plurality of other call control servers. And transmitting means for extracting subscriber data of all terminals accommodated in the router from the subscriber database and transmitting the extracted data to the call control server of the request source.
A network system that accommodates terminals accommodated in a failed call control server in a distributed manner among a plurality of other call control servers, the network system including a plurality of call control servers and all of the network systems. A subscriber data server for storing subscriber data of the terminal; and a monitoring server. When the monitoring server detects a failure of the call control server, it switches to each edge router accommodated in the call control server. A notification means for notifying the address of the call control server and instructing the switching destination call control server to route the communication transmitted from the terminal accommodated in the edge router; Each of the call control servers includes storage means for storing subscriber data of terminals accommodated in the call control server, and communication from the terminals. When the request is accepted, it is determined whether or not the subscriber data corresponding to the terminal exists in the storage means. If the subscriber data does not exist in the storage means, the terminal that transmitted the communication request is controlled by the own call control server. It is determined that the terminal is a communication request for distributed accommodation accompanying the occurrence of a failure, the subscriber data server requests subscriber data of the terminal, and the subscriber data transmitted from the subscriber data server The subscriber data server holds the subscriber data of the terminal accommodated in the edge router in units of edge routers connected to each call control server. The subscriber database and the subscribers of all terminals accommodated in the edge router that accommodates the terminal of the requested subscriber data in response to each request of the plurality of other call control servers. The chromatography data, the extracted from the subscriber database comprises a transmitting means for transmitting to the requesting call control server, the.

  According to the present invention, when a failure occurs in the call control server, the recovery time can be shortened, and the processing load on the transfer destination call control server can be reduced.

1 is an overall configuration diagram of a network system according to an embodiment of the present invention. It is a block diagram of the network system after distributed switching.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a network system such as a next generation network according to an embodiment of the present invention. The network system according to the present embodiment includes a plurality of terminals 1a to 6a, a plurality of edge routers (SSE: Subscriber Service Edge) 1b to 6b, a plurality of call control servers (SIP Signaling Control Servers) 1d to 3d, and subscribers. A data server 1h and a routing DB 1g are provided.

  Each terminal 1a to 6a is accommodated in any one of the edge routers 1b to 6b, and each edge router 1b to 6b is accommodated in any one of the call control servers 1d to 3d.

  Each call control server 1d to 3d stores subscriber data acquisition unit 13 and subscriber data 1c to 6c of terminals 1a to 6a accommodated in edge routers 1b to 6b accommodated in the call control server. A storage unit 14 is provided. The subscriber data acquisition unit 13 acquires subscriber data of a terminal that does not exist in the storage unit 14 from the subscriber data server 1h and stores it in the storage unit 14.

  The subscriber data 1c to 6c are subscriber information including service contract information necessary for call processing. In the present embodiment, subscriber data of all terminals accommodated in the edge router is held together for each edge router.

  In the illustrated example, the storage unit 14 of the call control server # 1: 1d stores the subscriber data # 1-1: 1c of the terminal 1a and the terminal 1a ′ accommodated in the edge router # 1-1: 1b, The terminal 2a and the subscriber data # 1-2: 2c of the terminal 2a ′ accommodated in the edge router # 1-2: 2b are stored. Further, the storage unit 14 of the call control server # 2: 2d stores the subscriber data # 2-1: 3c of the terminal 3a accommodated in the edge router # 2-1: 3b and the edge router # 2-2: The subscriber data # 2-2: 4c of the terminal 4a accommodated in 4b is stored. Further, the storage unit 14 of the call control server # 3: 3d stores the subscriber data # 3-1: 5c of the terminal 5a accommodated in the edge router # 3-1: 5b and the edge router # 3-2: The subscriber data # 3-2: 6c of the terminal 6a accommodated in 6b is stored.

  The subscriber data server 1h includes a subscriber data transmission unit 11, a routing DB update unit 12, and a subscriber DB 1f. The subscriber data transmission unit 11 transmits the subscriber data stored in the subscriber DB 1f in response to a request from the call control server. The routing DB update unit 12 updates the routing table stored in the routing DB 1g.

  The subscriber DB 1f stores subscriber data of all terminals accommodated in the call control servers 1d to 3d and the edge routers 1b to 6b. Further, the subscriber DB 1f of this embodiment holds subscriber data of terminals accommodated in the edge router in units of edge routers 1b to 6b. The subscriber data 1c to 6c stored in the subscriber DB 1f and the subscriber data 1e to 6e stored in the storage unit 14 of the call control servers 1d to 3d are the same (1c = 1e, 2c = 2e, 3c = 3e, 4c = 4e, 5c = 5e, 6c = 6e).

  The routing DB 1g stores routing tables for the edge routers 1b to 6b under the network system.

  Note that the monitoring server 1i that is an external system of the network system monitors the states of the call control servers 1d to 3d.

  The call control servers 1d to 3d and the subscriber data server 1h described above use, for example, a general-purpose computer system including a CPU, a memory, an external storage device such as an HDD, an input device, and an output device. be able to. In this computer system, each function of each device is realized by the CPU executing a predetermined program loaded on the memory. For example, each function of the call control servers 1d to 3d and the subscriber data server 1h is the same as that of the call control servers 1d to 3d in the case of a program for each call control server 1d to 3d, and for the subscriber data server 1h. In the case of the above program, it is realized by the CPU of the subscriber data server 1h executing it.

  The programs for the call control servers 1d to 3d and the program for the subscriber data server 1h may be stored in a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, an MO, and a DVD-ROM. Distribution via a network is also possible.

  Next, the processing of this embodiment will be described.

  In the present embodiment, when a certain call control server fails, terminals (subscribers) accommodated in the failed call control server are distributed and accommodated in a plurality of other call control servers.

  When a failure occurs in a certain call control server, the monitoring server 1i has data related to the magnitude of the load such as the CPU processing amount, buffer usage rate, number of accommodated subscribers, etc. at the time of the busy call control server. The number of servers to be distributed and the distribution destination server are determined based on the CPU capacity of the call control server during the busy hour, the buffer usage rate, and the surplus amounts such as the number of accommodated subscribers. Communication equipment such as a call control server is generally designed based on an estimated load amount several months ahead, so there is a margin.

  There are two methods of specifying the distribution destination server: a method of specifying when a failure occurs (switching), and a method of preliminarily estimating the margin based on traffic time characteristics, day of week characteristics, etc. . Since the latter method can reduce the time required for specifying the distribution destination server, the service stop time due to the failure of the call control server can be reduced.

  When the number of call control servers to be distributed (number of switching destination call control servers) and the distribution destination call control server (switching destination call control server) are determined, the monitoring server 1i sends to each edge router accommodated in the failed call control server. On the other hand, the IP address of the switching destination call control server is notified, and the switching destination call control server is instructed to communicate with the communication transmitted from the terminal accommodated in the edge router.

  When the switching destination call control server receives the communication request from the edge router, the switching destination call control server determines whether or not the terminal (subscriber) that has transmitted the communication request is a terminal controlled by the own call control server. That is, if the subscriber data of the terminal exists in the storage unit 14, the switching destination call control server determines that the terminal is controlled by the own call control server, and stores the subscriber data of the terminal in the storage unit 14. Is not a terminal controlled by the own call control server. If it is determined that the terminal is not controlled by the own call control server, it is determined that the communication is due to distributed accommodation (communication by failure switching) accompanying the occurrence of a failure, and the subscriber data server 1h is requested for subscriber data. The subscriber data request includes a subscriber ID (for example, a telephone number) included in the communication request.

  When the subscriber data transmission unit 11 of the subscriber data server 1h receives the subscriber data request from the switching destination call control server, the subscriber data is sent from the subscriber ID together with the subscriber data of the requested subscriber ID. The accommodated edge router is identified, and subscriber data of all terminals accommodated in the identified edge router is extracted from the subscriber DB and transmitted to the switching destination call control server. As a result, the number of inquiries of subscriber data to the subscriber data server 1h of the switching destination call control server can be reduced.

  In addition, the subscriber DB of the present embodiment can reduce the processing time for extracting subscriber data from the subscriber DB by holding subscriber data in units of edge routers. As for holding subscriber data in units of edge routers, for example, a subscriber table (data set) holding subscriber data of terminals accommodated in the edge router is provided for each edge router, or for each edge router. For example, the subscriber data of terminals accommodated in the edge router may be clustered (aggregated).

  Further, the routing DB update unit 12 of the subscriber data server 1h notifies the routing DB 1g to change the accommodation destination call control server of the identified edge router from the failed call control server to the switching destination call control server. . As a result, incoming calls to all the migration target terminals accommodated in the edge router can be received not via the failed call control server but via the switching destination call control server.

  The switching destination call control server makes an inquiry about the subscriber data to the subscriber DB in addition to the above-described method performed at the time of a communication request from the edge router, the edge router accommodated in the failed call control server. On the other hand, there is also a method in which the switching destination call control server is instructed to perform routing and triggered by the time when the edge router performs the switching procedure.

  Next, the processing (distributed recovery processing) of the present embodiment described above will be specifically described with reference to FIG.

  Normally, as shown in FIG. 1, outgoing calls and incoming calls from the terminals 1a to 6a are processed by the accommodated edge routers 1b to 6b and the call control servers 1d to 3d in which the edge routers are accommodated. Is done. Here, the process of the present embodiment will be described by taking as an example the case where the call control server # 1: 1d fails.

  When the call control server # 1: 1d fails, the monitoring server 1i determines the number of call control servers to be distributed and the call control server. In the example shown in FIG. 2, outgoing calls from edge router # 1-1: 1b are sent to call control server # 2: 2d, outgoing calls from edge router # 1-2: 2b are sent to call control server # 3: 3d Decide to be distributed (routing). As a result, the outgoing call from the terminals 1a and 1a ′ is routed to the call control server # 2: 2d via the edge router # 1-1: 1b, and the outgoing call from the terminals 2a and 2a ′ is the edge router # 1-2: Routed to call control server # 3: 3d via 2b.

  The number of call control servers and how to determine the call control server are, for example, the number of terminals accommodated by the call control server # 1: 1d, the traffic volume that the call control server # 1: 1d normally processes, and the CPU usage rate. Data, call control server # 2: 2d and call control server # 3: 3d margin processing capacity (number of terminals accommodated, traffic normally processed by call control server # 1: 1d, CPU usage It is conceivable to calculate from (calculated from data such as rate).

  As a subsequent process, the call control server # 2: 2d and the call control server # 3: 3d to be switched are respectively connected to the edge router # 1-1: 1b and the edge router with respect to the subscriber data server 1h (subscriber DB1f). # 1-2: Inquire the subscriber data of the terminal accommodated in 2b. As described above, the inquiry about the subscriber data includes a method that is performed when a communication request is made from each edge router, and a method that is performed when the edge router performs a switching procedure when a failure occurs in the call control server. In the following, a case will be described as an example where the switching destination call control server # 2: 2d inquires of the subscriber data server 1h about the subscriber data of the terminal accommodated in the edge router # 1-1: 1b.

<Inquiry of subscriber data when communication request from edge router>
An outgoing call from the terminal 1a is routed to the call control server # 2: 2d via the edge router # 1-1: 1b. The call control server # 2: 2d that has received the outgoing call from the terminal 1a refers to the storage unit 14 and determines whether or not the subscriber data of the terminal 1a exists. In this case, since the subscriber data of the terminal 1a does not exist in the storage unit 14, the call control server # 2: 2d determines that the communication request (call) is due to failure switching, and the terminal 1a Inquires about the subscriber data.

  The subscriber data server 1h performs the following processing.

  (1) When the subscriber data transmission unit 11 of the subscriber data server 1h receives an inquiry about the subscriber data of the terminal 1a from the call control server # 2: 2d, not only the subscriber data of the terminal 1a but also the terminal 1a Are read from the subscriber DB 1f and transmitted to the call control server # 2: 2d.

  (2) In addition, the routing DB update unit 12 of the subscriber data server 1h changes the destination call control server of the edge router 1b from the call control server # 1: 1d to the call control server # 2: 2d for the routing DB 1g. Notify the change and update the routing table of routing DB1g.

  Through the process (1), the call control server # 2: 2d receives the subscriber data of all the terminals 1a and 1a ′ accommodated in the edge router # 1-1: 1b and stores them in the storage unit 14. To do. The call control server # 2: 2d performs call connection processing based on the received subscriber data of the terminal 1a. Further, since the storage unit 14 of the call control server # 2: 2d holds the subscriber data 1e of all terminals accommodated by the edge router # 1-1: 1b, there is a communication request from the terminal 1a ′. When this happens, there is no need to inquire subscriber data to the subscriber data server 1h.

  Also, by the processing of (2), the routing DB 1g changes the routing to the edge router # 1-1: 1b to the routing to the call control server # 2: 2d. An incoming call can be received via call control server # 2: 2d rather than via call control server # 1: 1d.

<How to query subscriber data during edge router switching>
When edge router # 1-1: 1b switches the call control server of the connection destination from call control server # 1: 1d to call control server # 2: 2d, the subscriber of call control server # 2: 2d The data acquisition unit 13 detects that the edge router # 1-1: 1b is subordinate to the subscriber data server 1h, and all the terminals 1a, 1a ′ accommodated in the edge router # 1-1: 1b Request subscriber data 1e.

  The subscriber data server 1h performs the following processing.

   (1) The subscriber data transmission unit 11 of the subscriber data server 1h reads out the subscriber data 1e of all terminals of the edge router 1b from the subscriber DB 1f and transmits it to the call control server # 2: 2d.

  (2) Also, the routing DB update unit 12 of the subscriber data server 1h changes the accommodating call control server of the edge router 1b from the call control server # 1: 1d to the call control server # 2: 2d for the routing DB1g. Notify the change and update the routing table of routing DB1g.

  Through the process (1), the call control server # 2: 2d receives the subscriber data of all the terminals 1a and 1a ′ accommodated in the edge router # 1-1: 1b and stores them in the storage unit 14. To do. Thus, since the storage unit 14 of the call control server # 2: 2d holds the subscriber data 1e of all terminals accommodated by the edge router # 1-1: 1b, the edge router # 1-1: 1b For outgoing calls from terminals 1a and 1a 'accommodated in the call, the call control server # 2: 2d connects the call based on the subscriber data 1e without inquiring the subscriber data from the subscriber data server 1h. Process.

  Also, by the processing of (2), the routing DB 1g changes the routing to the edge router # 1-1: 1b to the routing to the call control server # 2: 2d. An incoming call can be received via call control server # 2: 2d rather than via call control server # 1: 1d.

  In the present embodiment described above, when a certain call control server fails, the switching destination call control servers are distributed in a plurality. As a result, the subscriber data received by the switching destination call control server from the subscriber DB and held by the failed call control server is divided by the plurality of switching destination call control servers. The time is shortened, and the number of data that needs to be processed by the switching destination call control server is reduced. That is, when a failure occurs in the call control server, the recovery time can be shortened and the processing load on the destination call control server can be reduced.

  For example, if there are n switching destination call control servers, the amount of subscriber data transferred to each switching destination call control server becomes 1 / n, so that the transfer time is shortened and the processing amount at the transfer destination is 1. The failure recovery time can be shortened by shortening the processing time at the switching destination due to / n.

  Further, in this embodiment, since the remaining capacity of the existing call control server is used by distributing and accommodating in a plurality of call control servers, it is not necessary to separately prepare a spare call control server for failure recovery.

  Also, in the subscriber DB of this embodiment, by holding data in units of edge routers, the time until data transmission can be shortened and the recovery time of the switching destination can be shortened.

  In addition, this invention is not limited to the said embodiment, Many deformation | transformation are possible within the range of the summary.

1a-6a: Terminal
1b-6b: Edge router
1c-6c: Subscriber data (subscriber information)
1d to 3d: Call control server
1d to 3d: Call control server
1e-6e: Subscriber data (subscriber information)
1f: Subscriber DB
1g: Routing table
1i: Subscriber data server

Claims (4)

A distributed restoration method for distributing and accommodating terminals accommodated in a faulty call control server performed by a network system in a plurality of other call control servers,
The network system includes a plurality of call control servers and a subscriber data server that stores subscriber data of all terminals of the network system,
Each of the other plurality of call control servers includes:
A storage unit for storing subscriber data of terminals accommodated in the call control server;
When receiving a communication request from a terminal, a determination step of determining whether subscriber data corresponding to the terminal exists in the storage unit;
When the terminal does not exist in the storage unit, it is determined that the terminal that transmitted the communication request is a terminal that is not controlled by the own call control server, and is a distributed accommodation communication request due to the occurrence of a failure, and the subscriber data server Requesting the subscriber data of the terminal and storing the subscriber data transmitted from the subscriber data server in the storage unit, and
The subscriber data server is
In the unit of edge router connected to each call control server, it has a subscriber database that holds subscriber data of terminals accommodated in the edge router ,
In response to each request of the other plurality of call control servers , the subscriber data of all the terminals accommodated in the edge router accommodating the terminal of the requested subscriber data is extracted from the subscriber database, A distributed recovery method characterized by performing a transmission step of transmitting to a requesting call control server. A distributed restoration method for distributing and accommodating terminals accommodated in a faulty call control server performed by a network system in a plurality of other call control servers,
The network system includes a plurality of call control servers, a subscriber data server that stores subscriber data of all terminals of the network system, and a monitoring server.
The monitoring server is
When a failure of the call control server is detected, the address of the switching destination call control server is notified to each edge router accommodated in the call control server, and communication transmitted from the terminal accommodated in the edge router is transmitted. Performs a notification step that instructs the switching destination call control server to route,
Each of the other plurality of call control servers includes:
A storage unit for storing subscriber data of terminals accommodated in the call control server;
When receiving a communication request from a terminal, a determination step of determining whether subscriber data corresponding to the terminal exists in the storage unit;
When the terminal does not exist in the storage unit, it is determined that the terminal that transmitted the communication request is a terminal that is not controlled by the own call control server, and is a distributed accommodation communication request due to the occurrence of a failure, and the subscriber data server Requesting the subscriber data of the terminal and storing the subscriber data transmitted from the subscriber data server in the storage unit, and
The subscriber data server is
In the unit of edge router connected to each call control server, it has a subscriber database that holds subscriber data of terminals accommodated in the edge router,
In response to each request of the other plurality of call control servers, the subscriber data of all the terminals accommodated in the edge router accommodating the terminal of the requested subscriber data is extracted from the subscriber database, Perform a send step to send to the requesting call control server
A distributed recovery method characterized by the above. A network system for accommodating terminals accommodated in a failed call control server in a distributed manner among other call control servers,
The network system includes a plurality of call control servers and a subscriber data server that stores subscriber data of all terminals of the network system,
Each of the other plurality of call control servers includes:
Storage means for storing subscriber data of terminals accommodated in the call control server;
When a communication request from a terminal is received, it is determined whether or not subscriber data corresponding to the terminal exists in the storage unit. If the subscriber data does not exist in the storage unit, the terminal that transmitted the communication request performs self-call control. A terminal that is not controlled by the server is determined to be a communication request for distributed accommodation accompanying the occurrence of a failure, the subscriber data server is requested for subscriber data of the terminal, and is transmitted from the subscriber data server. Obtaining means for storing the stored subscriber data in the storage means,
The subscriber data server is
A subscriber database that holds subscriber data of terminals accommodated in the edge router in units of edge routers connected to each call control server ;
In response to each request of the other plurality of call control servers , the subscriber data of all the terminals accommodated in the edge router accommodating the terminal of the requested subscriber data is extracted from the subscriber database, And a transmission means for transmitting to the requesting call control server. A network system for accommodating terminals accommodated in a failed call control server in a distributed manner among other call control servers,
The network system includes a plurality of call control servers, a subscriber data server that stores subscriber data of all terminals of the network system, and a monitoring server.
The monitoring server is
When a failure of the call control server is detected, the address of the switching destination call control server is notified to each edge router accommodated in the call control server, and communication transmitted from the terminal accommodated in the edge router is transmitted. Has a notification means for instructing the switching destination call control server to perform routing,
Each of the other plurality of call control servers includes:
Storage means for storing subscriber data of terminals accommodated in the call control server;
When a communication request from a terminal is received, it is determined whether or not subscriber data corresponding to the terminal exists in the storage unit. If the subscriber data does not exist in the storage unit, the terminal that transmitted the communication request performs self-call control. A terminal that is not controlled by the server is determined to be a communication request for distributed accommodation accompanying the occurrence of a failure, the subscriber data server is requested for subscriber data of the terminal, and is transmitted from the subscriber data server. Obtaining means for storing the stored subscriber data in the storage means,
The subscriber data server is
A subscriber database that holds subscriber data of terminals accommodated in the edge router in units of edge routers connected to each call control server;
In response to each request of the other plurality of call control servers, the subscriber data of all the terminals accommodated in the edge router accommodating the terminal of the requested subscriber data is extracted from the subscriber database, Transmission means for transmitting to the call control server of the request source
A network system characterized by

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