JP2014220675A - Communication control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication control system that does not reduce communication service processing performance even at the time of failure of a processing server constituting part of a cluster and increase or decrease in processing servers.SOLUTION: A data management server 30 holds session information that processing servers (application servers 20) need to process a communication service request from a user terminal 2 in one lump. A load balancer 10 distributes new and continuous communication service requests about the same session to the same processing server using session identification information included in an individual communication service request. If a processing server is failed or reduced, the load balancer 10 redistributes a subsequent continuous communication service request to another working processing server. The processing server to which the continuous communication service request is distributed in the middle of a session obtains necessary session information from the data management server 30 to continue the communication service of the session.

Description

  The present invention relates to a communication control system that provides a communication service such as an IP (Internet Protocol) telephone in a cluster configuration with a plurality of processing servers. In particular, the present invention relates to a technique for continuing a provided communication service without interruption even when a failure occurs in a processing server or when the number of processing servers is increased or decreased according to demand.

  In a communication control system with a cluster configuration consisting of multiple processing servers, session information necessary to continue the communication service so that the service can continue even if a failure occurs in the processing server providing the communication service. Are also copied and stored in other processing servers (see, for example, Patent Document 1).

  Each communication service is processed by a specific processing server distributed by a load balancer (signal distribution device). Each time the communication service transitions to a predetermined stable state, each processing server transmits the session information at that time to another Copy and store it on the processing server.

JP 2012-248091 A

  In the conventional communication control system, when a failure occurs in an operating processing server that provides a communication service, or when an operating processing server is removed, the load balancer provides the processing server again. Reassign the communication service to another processing server that holds a copy of the session information of the communication service. At this time, in order to prevent the load from being concentrated on a specific server that holds a copy of the session information, the session information of all communication services provided at that time is rearranged, and then a new distribution is performed. The communication service was to be continued. For this reason, there has been a case where the communication service processing performance is temporarily lowered before the relocation of the session information is completed.

  In addition, when processing servers that make up a cluster are expanded in response to changes in demand for communication services, session information can be re-allocated in order to redistribute the load so that the processing capacity of the added processing servers can be utilized immediately. There was a need to make arrangements. Therefore, even in this case, the communication service processing performance may be temporarily lowered until the rearrangement of the session information is completed.

  The present invention has been made in order to solve the above-described problems. Even when a failure occurs in a processing server constituting the cluster or when the number of processing servers is increased or decreased, the communication service processing performance is reduced. It is an object of the present invention to provide a communication control system that does not generate.

  In order to solve the above problems, the present invention provides a plurality of processing servers for providing a predetermined communication service to the user terminal based on a communication service request signal transmitted from the user terminal in a predetermined procedure, and the user terminal A communication control system comprising: a signal distribution device that distributes the communication service request signal transmitted from the plurality of processing servers; and a data management server that stores and manages information necessary for providing the communication service, When the signal distribution device receives a new communication service request signal from the user terminal, the signal distribution device determines a processing server as a distribution destination of the new communication service request signal by a predetermined distribution algorithm, and Session identification information included in the communication service request signal and the processing server of the determined distribution destination Is stored in its own storage unit, and the communication service request signal received from the user terminal is the same session identification as that stored as the distribution history information in the communication service request signal. In the case of a continuous communication service request signal including information, a service request distribution unit that distributes the continuous communication service request signal to the distribution destination processing server associated with the session identification information, Each of the plurality of processing servers generates session information corresponding to the session identification information included in the new communication service request signal when the communication service request signal assigned to the processing server is a new communication service request signal. While using the session information stored in its own storage unit, If the received communication service request signal is the continuous communication service request signal, the session information stored in its own storage unit corresponding to the session identification information included in the continuous communication service request signal is used. A session control processing unit that provides the communication service by executing a predetermined process; and whenever the predetermined process is executed and the communication service transitions to a predetermined stable state, the stable state after the transition A session information registration unit that transmits the session information stored in the storage unit including the information that represents to the data management server, and the communication service request signal distributed to itself is not a new communication service request signal, and Session information corresponding to the session identification information included in the communication service request signal is stored in the own storage unit. A session information acquisition unit that acquires the session information from the data management server and stores it in the storage unit, the data management server transmits the session transmitted from the plurality of processing servers. A session information management unit is provided that stores information in its own storage unit and returns the session information to the requesting processing server in response to a request from the processing server.

  By doing so, it is not necessary to relocate the session information even when a failure occurs in the processing servers that make up the cluster, or when the number of processing servers is increased or decreased, so communication service processing performance is not degraded. A communication control system can be provided.

  Further, in the communication control system according to the present invention, the signal distribution device includes a server state management table that holds operation states of the plurality of processing servers in its storage unit, and the service request distribution unit includes When transmission of the communication service request signal to the distribution destination processing server fails, the communication service request signal is distributed to one of the other processing servers whose operation state is in operation.

  In this way, when a failure occurs in the operating processing server, the other processing server that is operating can take over the communication service provided by the processing server in which the failure has occurred.

  In the communication control system according to the present invention, the service request distribution unit may be configured such that the operation state of the processing server of the distribution destination held in the server state management table is not in operation, or the distribution destination When the information of the processing server is deleted from the server status management table, the communication service request signal to the processing server of the distribution destination is distributed to any of the other processing servers whose operating status is operating It was.

  In this way, if a processing server that was operating is disconnected from the system or has stopped operating, the other processing server that is operating can take over the communication service provided by the processing server. be able to.

  According to the present invention, it is possible to provide a communication control system that does not cause a decrease in communication service processing performance even when a failure occurs in a server that constitutes a cluster or when servers are increased or decreased.

It is a figure which shows the structural example of the communication control system which concerns on this invention. It is a functional block diagram which shows the structural example of a load balancer (signal distribution apparatus). It is a functional block diagram which shows the structural example of an application server. It is a functional block diagram which shows the structural example of a data management server. It is a figure which shows the structure and data example of a server state management table. It is a figure which shows the structure and data example of a distribution management table (distribution log | history). It is a figure which shows the structure and data example of a session information management table (session information). It is explanatory drawing about the stable state of IP telephone service using SIP. It is a flowchart which shows the example of the distribution process which a load balancer (signal distribution apparatus) performs. It is a flowchart which shows the example of the communication service request process which an application server performs. It is a sequence diagram which shows the example of the signal in the case of providing IP telephone service using SIP, and the flow of a process. It is a figure which shows the structural example of the conventional communication control system.

  DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate. In this embodiment, a communication control system that provides IP telephone service using SIP (Session Initiation Protocol) has a cluster configuration including a plurality of processing servers (hereinafter also referred to as “application servers”) that perform call control processing. An example will be described. The present invention is not limited to the IP telephone service but can be applied to any communication service provided by setting a session with a user terminal, and the protocol to be used is not limited to SIP.

<Conventional communication control system>
First, a configuration example and an operation outline of a conventional communication control system will be described as a comparative example with reference to FIG. FIG. 12 is a diagram illustrating a configuration example of a conventional communication control system.

  As shown in FIG. 12, a conventional communication control system 1A that provides a communication service such as an IP telephone service to a plurality of user terminals 2 connected to a network 3 includes a load balancer 10A and a plurality of members constituting a cluster. Application servers 20A-1, 20A-2, 20A-3,... And a data management server 30A.

  The load balancer 10A transmits a communication service request signal (hereinafter sometimes abbreviated as “request signal”) transmitted from each user terminal 2 according to a predetermined procedure to any one application server by a predetermined distribution algorithm. The response signal transmitted from the distribution destination application server is relayed to the requesting user terminal 2 and returned.

  The distribution algorithm includes a round robin method, a round robin method with server load determination (a server with a server load exceeding a certain value is skipped and the next server is assigned), a hash method, a hash method with a server load determination (a server load is a constant value) The above server is skipped and the next server is assigned).

  The application server 20A to which the communication service request signal from the user terminal 2 is distributed by the load balancer 10A sets a session with the user terminal 2 according to a predetermined procedure, and a predetermined session required for providing the communication service Various communication services are provided to the user terminal 2 by generating information and executing predetermined processing.

  In addition, the application server 20 </ b> A changes the stability after the transition every time the provided communication service (for example, IP telephone service) transitions to a predetermined stable state (for example, “calling”, “busy”, etc.). Session information including information indicating the state is copied to another application server 20A and stored as a backup. In the example of FIG. 12, as indicated by the dashed arrow and rectangle, the session information s1 of the application server 20A-1 is copied to the application server 20A-2, and the session information s2 of the application server 20A-2 is copied to the application server 20A-. For example, a set of a copy source and a copy destination is predetermined by a predetermined rule.

  Here, it is assumed that a failure occurs in one application server 20A (for example, application server 20A-1) that is operating, and the server can no longer continue the communication service provided by the server itself. Assume. At this time, when detecting the failure of the application server 20A-1, the load balancer 10A holds a copy of the session information s1 of the communication service for the communication service request signal distributed to the application server 20A-1. Sort to application server 20A-2. Thereby, the distribution destination application server 20A-2 promotes the backup session information s1 held by itself to the current session information s1, and continues the communication service of the session. Further, the session information s1 is duplicated and held in the application server 20A-3 as a new backup destination.

  Note that if the subsequent communication service request signal is simply distributed to the server that has been the replication destination of the failed server, the duplication destination server is subjected to about twice as much load as before. Therefore, in such a case, it is necessary to rearrange the current and backup session information of all sessions distributed to each application server 20A at that time so that the load on each server is almost equal. . In some cases, the communication service processing performance temporarily decreases before the rearrangement is completed.

  Further, even when the number of application servers 20A is increased or decreased according to a change in demand for communication services, it is necessary to rearrange the same session information, which also causes a temporary decrease in communication service processing performance. was there.

  In the conventional communication control system 1A, the data management server 30A holds and manages data such as the subscriber information 331 of the communication service subscriber, but does not hold session information necessary for providing the communication service.

<Communication control system of the present invention>
Next, the configuration and operation of the communication control system according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a diagram showing a configuration example of a communication control system according to the present invention. As shown in FIG. 1, a communication control system 1 according to the present invention for providing a communication service such as an IP telephone service to a plurality of user terminals 2 connected to a network 3 includes a load balancer (signal distribution device) 10 and , And a plurality of application servers 20-1, 20-2, 20-3,... Constituting the cluster and a data management server 30.

  The load balancer 10 distributes a new communication service request signal transmitted from each user terminal 2 to any one of the application servers 20 by a predetermined distribution algorithm, and transmits a response signal transmitted from the distribution destination application server 20. , Relay it back to the requesting user terminal 2.

  The distribution algorithm includes: round robin method, round robin method with server load determination (skip servers with server load over a certain level and assign the next server), hash method, hash method with server load determination (server load over a certain level) The server is skipped and the next server is assigned).

  In addition, the load balancer 10 associates the session identification information included in the new communication service request signal with the identification information of the application server 20 that is the distribution destination, and holds it as the distribution history 132, and thereafter the same session. The continuous communication service request signal having the identification information is distributed to the application server 20 of the same distribution destination.

  In the example of FIG. 1, the load balancer 10 is used as a single unit. However, the distribution history 132 can be configured by synchronizing a plurality of load balancers.

  Each application server 20 to which the communication service request signal is distributed by the load balancer 10 sets up a session with the user terminal 2 according to a predetermined procedure, and a predetermined communication service (for example, IP phone service) )I will provide a. At this time, each application server 20 holds predetermined session information including session identification information and user identification information necessary for providing a communication service on each session in the storage unit, and refers to the session information. A predetermined communication service is provided while updating.

  In addition, the application server 20 changes the stable state after the transition every time the provided communication service (for example, IP telephone service) transitions to a predetermined stable state (for example, “calling”, “busy”, etc.). Is sent to the data management server 30 and held as session information 332. Therefore, session information about communication services of all sessions provided by the communication control system 1 is collectively stored as session information 332 in the data management server 30.

  Here, a failure occurs in one application server 20 (for example, application server 20-1) that is operating, and the server can no longer continue the communication service that it has shared and provided. Assume. At this time, when the load balancer 10 detects a failure of the application server 20-1, the load of the other application server 20 is almost equalized after that for the communication service request signal distributed to the application server 20-1. As described above, the communication service request signal is individually allocated. At this time, each application server 20 as a distribution destination does not hold session information (for example, session information s1) necessary for processing of the service, so after acquiring the session information from the data management server 30, Continue communication services.

  Thus, in the communication control system 1 according to the present invention, even when a failure occurs in the operating application server 20, the load balancer 10 redistributes subsequent communication service request signals to the other application servers 20. Therefore, it is possible to eliminate the rearrangement of session information, which was necessary in the conventional system.

  In addition, even when the number of application servers 20 is increased or decreased in accordance with a change in demand for communication services, the load balancer 10 receives the subsequent communication service request signals, and the loads on all the application servers 20 after the increase and decrease are substantially equal. All you need to do is re-sort. Therefore, also in this case, it is possible to eliminate the rearrangement of session information that is necessary in the conventional system.

  In the example of FIG. 1, the data management server 30 is a single unit, but a plurality of units can be configured by applying a distributed technique (such as replication) in a known database management system.

<Configuration of each device>
Next, the configuration of each device included in the communication control system 1 according to the present invention will be described with reference to FIGS.

<Load balancer (signal distribution device)>
FIG. 2 is a functional block diagram illustrating a configuration example of the load balancer (signal distribution device) 10. As shown in FIG. 2, the load balancer 10 includes a control unit 11, a transmission / reception unit 12, and a storage unit 13.

  The transmission / reception unit 12 transmits / receives information to / from other devices. For example, the transmission / reception unit 12 receives a communication service request signal (for example, a SIP message) input from the user terminal 2 (see FIG. 1), a response signal addressed to the user terminal 2 transmitted from the application server 20, and the like. Those communication service request signals are transmitted to each application server 20, and those response signals are transmitted to the user terminal 2.

  The control unit 11 controls the operation of the load balancer 10, and includes a service request reception unit 111, a service request distribution unit 112, a service response transmission unit 113, and a server state management unit 114. The function of the control unit 11 including these is that a CPU (Central Processing Unit) (not shown) included in the load balancer 10 loads a predetermined program stored in the storage unit 13 to a main memory (not shown) and executes it. Is embodied by.

  The service request reception unit 111 acquires a service request signal transmitted from the user terminal 2 (see FIG. 1) via the transmission / reception unit 12.

  When the service request distribution unit 112 receives a new communication service request signal from the service request reception unit 111, the service request distribution unit 112 determines a distribution destination application server 20 using a predetermined distribution algorithm, and determines the distribution destination The request signal is transmitted to the application server 20. At this time, the service request distribution unit 112 generates information associating the session identification information included in the request signal with the determined application server 20 and registers the information in the distribution management table 132.

  When the service request distribution unit 112 receives a continuous communication service request signal including the same session identification information as that registered in the distribution management table 132 from the service request reception unit 111, the distribution management table By referring to 132, the continuation request signal is distributed and transmitted to the application server 20 associated with the session identification information, that is, the same application server 20 as the distribution destination of the new communication service request signal.

  The service response transmission unit 113 acquires a response signal to the request signal transmitted from the application server 20 that is the distribution destination via the transmission / reception unit 12, and transmits the response signal to the requesting user terminal 2 via the transmission / reception unit 12. To send.

  When the server state management unit 114 detects the occurrence of a failure in the application server 20 that is the distribution destination, or receives a notification from the data management server 30 about the addition, removal, or failure of the application server 20, the server state management table Information on the application server 20 held in 131 is added, deleted, or updated.

  The storage unit 13 includes a storage device such as a hard disk or a semiconductor memory, and includes a server state management table 131 and a distribution management table 132.

  FIG. 5 is a diagram illustrating a configuration and data example of the server state management table 131. As illustrated in FIG. 5, a record including a server identifier, a server state, and a server load is registered in the server state management table 131 for each application server 20 to be managed.

  Here, the server identifier is identification information given to uniquely identify each application server 20. Here, for the sake of convenience, the server identifier values are represented as “server A”, “server B”, “server C”,... The server state indicates the operating state of each application server 20. The server status includes, for example, “in operation” indicating a normal operation state, “failing” indicating a failure and inoperable state, and “standby” indicating a state where preparation for operation is completed. One of “under status confirmation” indicating that the status is unconfirmed and unknown is stored. The server load represents the load of each operating application server 20 as a percentage of the allowable maximum load, for example. Note that “−” is stored in the server load of the application server 20 whose server status is other than “in operation”.

  FIG. 6 is a diagram illustrating a configuration and data example of the distribution management table (distribution history) 132. FIG. 6 is a configuration and data example when a communication service is provided using SIP. In the distribution management table 132, a record including a Call-ID, a server identifier, and a final distribution time is provided by the communication service. Registered for each session (call) that has been made.

  Here, the Call-ID is identification information specified by the user terminal 2 that is the source in order to uniquely identify each session (call). Here, for convenience, Call-ID values are represented as “call identifier c1”, “call identifier c2”, “call identifier c3”,. The server identifier is identification information (same as FIG. 5) attached to the application server 20 determined as the distribution destination of the communication service request signal of the session. The final distribution time is the time when the communication service request signal is distributed last in the session. Here, for convenience, the value of the final distribution time is expressed as “time t1”, “time t2”, “time t3”,.

<Application server>
FIG. 3 is a functional block diagram illustrating a configuration example of the application server 20. As illustrated in FIG. 3, the application server 20 includes a control unit 21, a transmission / reception unit 22, and a storage unit 23.

  The transmission / reception unit 22 transmits / receives information to / from other devices. For example, the transmission / reception unit 22 receives a communication service request signal (for example, a SIP message) input from the user terminal 2 (see FIG. 1) and distributed by the load balancer 10, and returns it to the user terminal 2 to the load balancer 10. A response signal is transmitted. In addition, transmission / reception of session information and information regarding the state change of the application server 20 is performed with the data management server 30.

  The control unit 21 controls the operation of the application server 20 and includes a session control processing unit 211, a session information registration unit 212, and a session information acquisition unit 213. The functions of the control unit 21 including these are realized by a CPU (not shown) included in the application server 20 loading a predetermined program stored in the storage unit 23 into a main memory (not shown) and executing it. .

  The session control processing unit 211 acquires a communication service request signal (for example, a SIP message) transmitted from the user terminal 2 (see FIG. 1) and distributed by the load balancer 10 via the transmission / reception unit 12, and a communication service (for example, After generating session information necessary for providing (IP phone service), session control processing (for example, IP phone call control processing) is executed while referring to and updating the session information.

  Each time the communication service transitions to a predetermined stable state (eg, “calling”, “busy”, etc.) as the session control process (eg, call control process) is executed, the session information registration unit 212 Session information (for example, call information) including information indicating a stable state after transition is registered or updated in the data management server 30 via the transmission / reception unit 12.

  In addition, the session information acquisition unit 213 performs session information (for example, call control processing) necessary for executing session control processing (for example, call control processing) corresponding to a continuous communication service request signal (for example, SIP message) distributed by the load balancer 10. , Call information) is not held by itself, the session information is acquired from the data management server 30 via the transmission / reception unit 12.

  The storage unit 23 is configured by a storage device such as a hard disk or a semiconductor memory, and includes a session information management cache table 231. In the session information management cache table 231, the same content as the record corresponding to the session distributed to the application server 20 among the records of the session information management table 332 described later with reference to FIG. 7 is registered.

<Data management server>
FIG. 4 is a functional block diagram illustrating a configuration example of the data management server 30. As shown in FIG. 4, the data management server 30 includes a control unit 31, a transmission / reception unit 32, and a storage unit 33.

  The transmission / reception unit 32 transmits / receives information to / from other devices. For example, the transmission / reception unit 32 receives a signal requesting reference to subscriber information or session information transmitted from the application server 20 and transmits the requested subscriber information, session information, or the like to the application server 20. To do. Further, a signal for requesting registration and update of session information transmitted from the application server 20 is received, and information on a failure or increase / decrease in the application server 20 is received from an administrator terminal (not shown), Information is transmitted to each application server 20.

  The control unit 31 controls the operation of the data management server 30 and includes a subscriber information management unit 311, a session information management unit 312, and a server information management unit 313. The functions of the control unit 31 including these are realized by a CPU (not shown) included in the data management server 30 loading a predetermined program stored in the storage unit 33 into a main memory (not shown) and executing it. The

  The subscriber information management unit 311 performs registration, deletion, update, reference, and the like of information on each subscriber held in the subscriber information management table 331. The session information management unit 312 performs registration, deletion, update, reference, and the like of session information held in the session information management table 332. Also, the server information management unit 313 performs registration, deletion, update, reference, and the like of server information held in the server information management table 333.

  The storage unit 33 includes a storage device such as a hard disk or a semiconductor memory, and includes a subscriber information management table 331, a session information management table 332, and a server information management table 333.

  Among these, subscriber information transmitted from the user terminal 2 via the application server 20 is registered in the subscriber information management table 331. This subscriber information includes the identification information of the subscriber and the IP address of the user terminal 2 used by the subscriber (the detailed configuration is omitted). The server information management table 333 includes the server identifier, IP address, allowable maximum load, and the like of each application server 20.

  FIG. 7 is a diagram showing a configuration and data example of the session information management table (session information) 332. FIG. 7 shows a configuration and data example when a communication service is provided using SIP. The session information management table (session information) 332 includes Call-ID, Via, From, To, CSeq, and SIP stable. A record consisting of the status is registered for each session (call) in which the communication service is provided.

  Here, the Call-ID is identification information specified by the user terminal 2 that is the source in order to uniquely identify each session, as described above with reference to FIG. Via is information that specifies a response destination of a response signal to the communication service request signal of the session. Here, for convenience, the value of Via is expressed as “response destination r1”, “response destination r2”, “response destination r3”,. From is information indicating the source of the service request, and To is information indicating the destination of the service request. In the case of an IP telephone service, From corresponds to a caller user, and To corresponds to a callee user. Here, for convenience, the values of From and To are represented as “user u1”, “user u2”, “user u3”,.

  Information on the latest communication service request signal (for example, SIP message) in the session is held in CSeq. In the data example of FIG. 7, the value of CSeq is composed of a serial number attached to the SIP message and a predetermined request name (for example, “INVITE”, “ACK”, etc.) indicating the type of request. The SIP stable state is information indicating to what level the communication service provided in the session has progressed.

  FIG. 8 is an explanatory diagram of the SIP stable state in the IP telephone service using SIP. As shown in FIG. 8, in the IP telephone service using SIP, a series of procedures until a call session is set and released between the caller user terminal 2A and the callee user terminal 2B is defined. In other words, in the life cycle of one call as a service execution unit, a plurality of different processes such as “calling”, “answering”, and “disconnecting” are executed according to these procedures. Although a detailed description is omitted, the SIP stable state indicates how far the processing of the application server (SIP server) 20 has progressed, and has any value from “ST1” to “ST12” in FIG. . The session information management table 332 held by the data management server 30 stores, for example, values after “ST5”, and “ST1” to “ST4” are stored as local information of the application server 20 as session information. It may be held only on the information management cache table 231 side.

<Load balancer distribution processing>
Next, details of the distribution process executed by the load balancer 10 will be described with reference to FIG. FIG. 9 is a flowchart illustrating an example of distribution processing executed by the load balancer 10.

  A communication service request signal transmitted from the user terminal 2 to the load balancer 10 is acquired by the service request receiving unit 111 via the transmission / reception unit 12 and delivered to the service request distribution unit 112. In step S11, the service request distribution unit 112 determines whether or not the request signal corresponds to a new session. If the request signal is a new session (“Yes” in step S11), the service request distribution unit 112 adds a new request to step S13. If it is not a session (“No” in step S11), the process proceeds to step S12. At this time, when determining whether or not the session is a new session, the distribution management table 132 (see FIG. 6) is referred to. Specifically, if a record matching session identification information (for example, SIP Call-ID value) included in the request signal is registered in the distribution management table 132, it is determined that the session is not a new session. Otherwise, it is determined as a new session.

  In step S <b> 12, the service request distribution unit 112 identifies the distributed application server 20 by acquiring the value of the server identifier from the corresponding record of the distribution management table 132, and refers to the server state management table 131 to identify the server. Determine whether it is in operation. If the server is not operating (“No” in step S12), the process proceeds to step S13. If the server is operating (“Yes” in step S12), the process proceeds to step S15.

  In step S13, the service request distribution unit 112 determines a distribution destination server from among the active application servers 20 by a predetermined distribution algorithm. Next, in step S <b> 14, the service request distribution unit 112 generates a new record that associates the Call-ID value with the server identifier of the distribution destination server, and additionally registers it in the distribution management table 132. On the other hand, in step S15, the service request distribution unit 112 determines the server identified in step S12 as a distribution destination server.

  Next, the service request distribution unit 112 transfers the request signal via the transmission / reception unit 12 to the distribution destination server determined in step S13 or step S15 in step S16. Next, in step S17, the service request distribution unit 112 determines whether or not the request signal has been successfully transferred. If the transfer is successful (“Yes” in step S17), the service request distribution unit 112 transfers the request signal to step S18. If unsuccessful (“No” in step S17), the process proceeds to step S19.

  In step S18, the service request distribution unit 112 stores the current time as the final distribution time in the corresponding record of the distribution management table 132, and then ends the process. On the other hand, in step S19, the service request distribution unit 112 changes the server state of the distribution destination server held in the server state management table 131 to “failing”, and then returns the processing to step S13 by the connector A. Determine the distribution destination server again. At this time, if an application server whose server status is “standby” is registered in the server status management table 131, the server status is changed to “active”, and then the distribution server is changed. It may be determined again.

<Service request processing of application server>
Next, details of service request processing executed by the application server 20 will be described with reference to FIG. FIG. 10 is a flowchart illustrating an example of distribution processing executed by the application server 20.

  The communication service request signal transmitted from the user terminal 2 is distributed and transmitted to any one application server 20 by the load balancer 10. In the distribution destination application server 20, the session control processing unit 211 acquires the communication service request signal transmitted from the load balancer 10 via the transmission / reception unit 22.

  In step S21, the session control processing unit 211 determines whether or not the request signal corresponds to a new service request (for example, an SIP INVITE request), and if it is a new service request (in step S21). If “Yes”) is not a new service request in step S22 (“No” in step S21), the process proceeds to step S23.

  In step S22, the session control processing unit 211 extracts a value of Call-ID, Via, From, To, and CSeq included in the request signal to generate a new session information record, and a session information management cache table Additional registration in H.231.

  On the other hand, in step S23, the session control processing unit 211 determines whether or not the session information of the session is held in the session information management cache table 231 (the data configuration is the same as the session information management table 332 in FIG. 7). judge. If the session information is held (“Yes” in step S23), the process proceeds to step S25. If the session information is not held (“No” in step S23), the process proceeds to step S24. At this time, if a record that matches the session identification information (for example, the value of SIP Call-ID) included in the request signal is registered in the session information management cache table 231, it is determined that the session information is retained. Otherwise, it is determined that the session information is not held.

  In step S <b> 24, the session control processing unit 211 acquires session information corresponding to the session identification information from the data management server 30. Specifically, a session information acquisition request signal including the session identification information (for example, Call-ID value) is transmitted to the data management server 30 via the transmission / reception unit 22, and the response signal is transmitted to the transmission / reception unit 22. The necessary session information is acquired by receiving the data from the data management server 30. Then, a new record including the acquired session information is generated and additionally registered in the session information management cache table 231.

  Next, in step S25, the session control processing unit 211 executes a predetermined process corresponding to the request signal while referring to the session information held in the session information management cache table 231. If the stable state of the session has changed as a result of the processing, the session information in the session information management cache table 231 is updated. When the stable state of the session information is updated to a predetermined stable state, the data management server 30 requests registration update or update of the session information held in the session information management table 332 in step S26. After that, the process ends.

<Operation when application server fails>
Finally, an operation in the case where a failure occurs in the operating application server 20 will be described with reference to FIG. FIG. 11 is a sequence diagram illustrating an example of a signal and a flow of processing when a failure occurs in the application server 20-1 that provides an IP telephone service using SIP.

  First, in step S31, an INVITE request for requesting a call connection is transmitted from the source user terminal 2A to the load balancer. The load balancer 10 distributes the new communication service request signal to, for example, the application server 20-1, and the application server 20-1 sequentially executes call processing for calling the destination user terminal 2B (see FIG. 8). (Steps S32 to S40). The details of the processing of steps S32 to S40 have been described with reference to FIGS.

  Here, it is assumed that a failure occurs immediately after the application server 20-1 transmits the response signal in step S39 to the load balancer 10, and the application server 20-1 is in an inoperable state. At this time, the load balancer 10 tries to distribute the service request signal S41 transmitted next from the transmission source user terminal 2A to the application server 20-1, but the transmission fails. Therefore, the load balancer 10 determines that the application server 20-1 is in failure, and sends the request signal to another application server (for example, the application server 20-2) that is operating according to a predetermined distribution algorithm. Redistribute and transmit (step S42).

  At this time, the application server 20-2 does not hold call information (session information) necessary for executing call processing for the request signal. Therefore, the session information acquisition unit 213 of the application server 20-2 requests the data management server 30 to acquire the call information (step S43). The session information management unit 312 of the data management server 30 requested to acquire the call information reads the requested call information from the session information management table 332 and returns it to the application server 20-2 (step S44). Thus, the session control processing unit 211 of the application server 20-2 additionally registers the call information returned from the data management server 30 in its own session information management cache table 231, and then performs call processing using the call information. Execute (Steps S45 to S47). As a result, when the stable state of the session is changed and the session information in the session information management cache table 231 is updated, the session information registration unit 212 of the application server 20-2 is updated in step S45. By transmitting the session information to the data management server 30, the updated session information is registered and held in the session information management table 332 of the data management server 30.

  When the application server 20 is increased or decreased, the load balancer 10 refers to the server state management table 131 in which the result of the increase or decrease is reflected by the server state management unit 114, and the application server that is currently operating at that time The subsequent communication service request signals are reassigned to 20. As a result, even if a continuous communication service request signal is distributed to the application server 20 that does not hold the necessary session information, the application server 20 acquires the necessary session information from the data management server 30 each time. Therefore, it is not necessary to rearrange the session information as in the conventional system.

  As described above, in the present embodiment, the session information and the backup information that are conventionally held in a distributed manner by the application servers 20A (see FIG. 12) are collectively held in the data management server 30. Therefore, when the application server 20A fails or is increased or decreased, it is possible to eliminate the rearrangement of session information and its backup information, which was necessary in the past. Therefore, according to the present embodiment, it is possible to reliably suppress the occurrence of a temporary decrease in communication service processing performance that could not be avoided with the conventional system.

  In the prior art, since the session information including the backup portion is distributed and held on each application server 20A, when the processing program on the application server 20A is updated, the generation management of the session information (the relevant data It is necessary to identify the old and new with the updated program and convert the old data into new data). On the other hand, according to the present embodiment, the processing on the application server 20 can be configured to depend only on the communication service request signal from the user terminal 2 and the session information on the data management server 30. Therefore, it is possible to easily update the processing program on the application server 20.

  Although the description of the embodiment of the present invention has been completed above, the embodiment of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention.

1, 1A communication control system 2 user terminal 2A source user terminal 2B destination user terminal 3 network 10, 10A load balancer 11, 21, 31 control unit 12, 22, 32 transmission / reception unit 13, 23, 33 storage unit 20, 20A Application server (SIP server) (processing server)
30, 30A Data management server 111 Service request reception unit 112 Service request distribution unit 113 Service response transmission unit 114 Server state management unit 131 Server state management table 132 Distribution management table (distribution history)
DESCRIPTION OF SYMBOLS 211 Session control processing part 212 Session information registration part 213 Session information acquisition part 231 Session information management cache table 311 Subscriber information management part 312 Session information management part 313 Server information management part 331 Subscriber information management table (subscriber information)
332 Session information management table (session information)
333 Server information management table

Claims (3)

A plurality of processing servers that provide a predetermined communication service to the user terminal based on a communication service request signal transmitted from the user terminal in a predetermined procedure, and the communication service request signal transmitted from the user terminal A communication control system comprising: a signal distribution device that distributes to a processing server; and a data management server that stores and manages information necessary for providing the communication service,
When the signal distribution device receives a new communication service request signal from the user terminal, the signal distribution device determines a processing server as a distribution destination of the new communication service request signal by a predetermined distribution algorithm, and The distribution history information that associates the session identification information included in the communication service request signal with the determined processing server of the distribution destination is stored in its own storage unit, and the communication service request signal received from the user terminal thereafter is If the communication service request signal is a continuous communication service request signal that includes the same session identification information as that stored as the distribution history information in the communication service request signal, the distribution destination associated with the session identification information Service required to distribute the continuous communication service request signal to the processing server Equipped with a sorting unit,
Each of the plurality of processing servers is
If the communication service request signal distributed to itself is a new communication service request signal, session information corresponding to the session identification information included in the new communication service request signal is generated and stored in its own storage unit If the communication service request signal distributed to itself is the continuous communication service request signal, the own storage corresponding to the session identification information included in the continuous communication service request signal is used. Session control processing unit that provides the communication service by executing predetermined processing using session information stored in the unit;
Each time the predetermined process is executed and the communication service transitions to a predetermined stable state, the session information stored in the storage unit including the information indicating the stable state after the transition is stored in the data management server. A session information registration unit to be transmitted;
When the communication service request signal assigned to itself is not a new communication service request signal, and the session information corresponding to the session identification information included in the communication service request signal is not stored in the own storage unit Includes a session information acquisition unit that acquires the session information from the data management server and stores the session information in the storage unit.
The data management server stores the session information transmitted from the plurality of processing servers in its own storage unit, and returns the session information to the requesting processing server in response to a request from the processing server A communication control system comprising an information management unit. The communication control system according to claim 1,
The signal distribution device includes:
A server state management table that holds operating states of the plurality of processing servers is provided in its own storage unit,
If the service request distribution unit fails to transmit the communication service request signal to the distribution destination processing server, the service request distribution unit sends the communication service request signal to any of the other processing servers that are operating. A communication control system characterized by sorting. The communication control system according to claim 2,
The service request distribution unit deletes the information of the distribution destination processing server from the server state management table when the operation state of the distribution destination processing server held in the server state management table is not in operation. If it is, the communication control system is characterized in that the communication service request signal to the distribution destination processing server is distributed to any of the other processing servers whose operation state is in operation.

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