KR20070092466A - Soft-switch and its call session audit methods in broadband convergence network - Google Patents

Abstract

A soft switch in a BcN(Broadband convergence Network) and a call session auditing method thereof are provided to match call session state information between a soft switch and each gateway by providing an audit function for POTS(Plain Old Telephone Service) call sessions. If a soft switch activates a call session state information audit function(S2), a calling-side call control block requests audit information from a calling-side gateway and acquires it(S4). The call control block obtains a context ID from the calling-side gateway, requests audit information from a called-side call control block, and acquires it(S6). The calling-side call control block requests audit information from a subscriber DB of the soft switch and acquires it(S8). Based on the acquired audit information, the calling-side call control block judges whether the calling-side gateway, the called-side call control block, and the subscriber DB have the same state information with respect to an identical call session(S10). If not, the calling-side call control block initializes state information of the call session for the calling-side gateway, the called-side call control block, and the subscriber DB(S12).

Description

SOFT-SWITCH AND ITS CALL SESSION AUDIT METHODS IN BROADBAND CONVERGENCE NETWORK}

1 is a configuration diagram showing the configuration of a broadband communication network.

2 is a conceptual diagram illustrating call connection in a broadband communication network.

3 is a diagram illustrating a function for each function according to call setting in a broadband communication network.

4 is a flow chart illustrating a call audit operation in accordance with the present invention.

5A-5B illustrate Audit and Auditvalue message formats in accordance with the present invention.

The present invention relates to a soft switch in a broadband communication network and a call session auditing method thereof, and more particularly, to match call session state information of a soft switch providing a telephone service in a broadband communication network with call session state information of a gateway. will be.

Broadband networks are networks constructed with high-speed networks over large geographical areas. Broadband communication network is a kind of computer communication network that connects a large area through various equipment and provides multimedia services stably.

Broadband networks use softswitches and gateway devices to provide telephone services. The soft switch stores information on originating and called number for providing communication service in broadband communication network, and stores information including status information of terminal required for setting up actual call session. The softswitch also controls various gateways to control call session establishment.

The gateway can be largely divided into an access gateway and a trunk gateway, and the trunk gateway is a gateway that connects a public switched telephone network and a broadband communication network. The access gateway serves to accommodate a general telephone terminal in a broadband communication network. A call path is established through these various gateways.

In broadband networks, call sessions are established by softswitches and gateways. In the call setup process, when a call connection is requested from the calling terminal to the called terminal, the soft switch checks the state of the call session of the corresponding terminal, induces connection, and establishes a call path through the gateway.

In a conventional public switched telephone network, a facility for accommodating subscribers and a device for managing the state of a call session exist in the same exchange so that the state information of the call session is always maintained. However, the broadband communication network has a problem in that the call session state information is inconsistent because the call session establishment is distributed remotely by the soft switch and the gateway due to the increase in the acceptability of the communication network and the change in the transmission method.

If the status information of call session is inconsistent, there is a mismatch between the call session set by softswitch and the actual session state and the state of resources occupied for establishing the call session, or when the status of softswitch and gateway resource is inconsistent. to be.

If the occupancy status information of broadband network resources is inconsistent, there is a disadvantage in that efficient resource usage is impossible. In addition, this inconsistency acts as an instability factor in the operation of the system, there is a problem that if the inconsistency of the state information of the resource occupancy accumulates, the call session setup can not be performed throughout the system. In other words, there is a problem that the load of the system and the network is increased as the call session which is not actually used is maintained, and a state in which the resource for establishing the call session is not available may occur.

In addition, in the conventional public switched telephone network, since the call session setup function, which is limited to the inside of the system, operates in a distributed form between the soft switch and the gateway, a loss of the protocol message used when setting up the call session between the soft switch and the gateway is caused. There is a disadvantage that the possibility of inconsistency of the state information of the call session is increased.

An object of the present invention for solving such a problem is an audit function for a call session of a plain old telephone service (POTS), which is accommodated in a gateway in a broadband communication network and provided with a telephone telephone service under the control of a soft switch. This provides a way to match the state information of the call session between the softswitch and the gateway.

A call session auditing method in a broadband communication network for achieving the above object includes a first step of driving a call session auditing function for a specific call session of a soft switch device; A second step of the soft switch device querying the gateway device for information on the resources allocated by the gateway device for the call session; A third step of receiving a response to the query of the second step from the gateway device, and comparing the information of the resource allocated for the call session with the state information of the call session stored in the soft switch device; And a fourth step of initializing the state information of the call session when the state information and the response of the call session do not match in the third step.

In order to achieve the above object, a soft switch in a broadband communication network includes: a protocol block for performing communication using a protocol message with a gateway provided in the broadband communication network; And a call processing block for acquiring information on resources allocated by the gateway for a predetermined call session by using the protocol block, and initializing state information of the call session when it is inconsistent with the state information of the call session. It is characterized by including.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the preferred embodiment of the present invention, an environment in which a public telephone switching network is connected to a broadband communication network will be described as an example.

1 is a configuration diagram showing the configuration of a broadband communication network.

The broadband network is connected to the public switched telephone network.

The public telephone switching network includes a single station exchange 20 and an intercity exchange 30.

The terminal exchange 20 provides a telephone service by performing a call connection within a predetermined region and a role of accommodating existing telephone service subscribers.

The intercity exchange 30 may provide a telephone service for a large area by performing a connection between the terminal exchanges 20 that perform a call connection in a predetermined region.

The public switched telephone network is being transformed into a broadband communication network that can provide various services according to the development of communication technology. Therefore, it is necessary to change the network environment in the environment that accommodates the existing subscribers of the public switched telephone network in the process of converting the public switched telephone network into the broadband communication network. Due to these demands, various equipments are used in broadband networks.

The broadband communication network includes a soft switch 100, access gateways 210 and 220, and a trunk gateway 250.

The soft switch 100 controls a variety of equipment such as a gateway in a broadband communication network to establish a call session. In addition, the soft switch 100 performs an audit function for the established call session. When the audit function of the call session is operated, the soft switch 100 inquires the gateway of the call session state and performs an audit of the call session by using the response. The audit of the call session is to determine whether the state information of the call sessions that are distributed and stored in the various equipments of the broadband communication is consistent. It is to confirm the existence of abnormally occupied resources and restore it to an appropriate state.

The soft switch 100 controls the operation of other equipment and audits the call session by using a protocol message, and protocols of the protocol message include H.323, Session Initiation Protool (SIP), and Media Gateway Control (MEGACO) protocols. Used.

The access gateways 210 and 220 serve to accommodate the telephone terminals 11 and 12 in the broadband communication network. The access gateways 210 and 220 allow the call to be connected to the telephone terminals 11 and 12 through the broadband communication network. When the access gateway 210 or 220 receives a request for connection of a call session from the telephone terminals 11 and 12, the access gateway 210 or 220 converts the connection request into a protocol message and transmits the connection request to the soft switch 100. When the connection request is received, it serves to transmit the connection request of the call session to the receiving telephone terminal (11, 12).

The trunk gateway 250 is a gateway used to accommodate a public switched telephone network in a broadband communication network. It acts as a kind of toll exchange, and induces the establishment of a call session in a broadband communication network for a call requested from a public switched telephone network, or carries a call connection request from a broadband communication network to a public switched telephone network.

Broadband networks send and receive data in the form of packets. The access gateways 210 and 220 convert the signals according to the operations of the telephone terminals 11 and 12 into packets of a type used in the broadband communication network.

A typical gateway including an access gateway 210. 220 and a trunk gateway 250 responds to the soft switch 100 by checking the occupancy status of each subscriber when the soft switch 100 requests information on a call session. . In addition, the gateway includes a codec & decoder function for converting a user's voice signal into a signal used in a broadband communication network to provide a telephone service in a broadband communication network.

The telephone terminals 11 and 12 are the same terminals as the telephone terminals provided with the telephone service in the public switched telephone network, and may be provided with the service in the public telephone switched network or the broadband communication network. By requesting a call connection by picking up the handset of the terminal and manipulating the dial, it is notified that the call is requested using a bell, and the telephone service is provided in this manner.

2 is a conceptual diagram illustrating call connection in a broadband communication network.

When the telephone terminal 11 accommodated in the broadband communication network requests a call connection, the access gateway 210 of the calling party that accommodates the telephone terminal 11 transmits the call request to the soft switch 100. The soft switch 100 checks the address of the called terminal 12 requested to connect the call and transmits the call connection request to the access gateway 220 in which the called terminal 12 is accommodated. The call gateway 220 of the called party receiving the call connection request informs the call terminal 12 of the called party that the call connection is requested and calls between the two phone terminals 11 and 12 through the access gateway 210 of the calling party. Provide service.

At this time, a protocol message is used for communication between the soft switch 100 and each of the access gateways 210 and 220.

A broadband communication network is a kind of packet switching network. Information and data for a telephone service are transmitted using a broadband communication network in the form of a packet. In addition, call connection in a broadband communication network is divided into a setting for call connection and transmission and reception of an actual voice call, and thus there are different paths. That is, a signal path for setting up a telephone service and a transmission path of information according to an actual call exist differently.

When the first call connection is requested, the soft switch 100 establishes a call. The call setup is performed by providing the address information of the telephone terminals 11 and 12 in the soft switch 100 to the two access gateways 210 and 220 of the calling party and the called party. The call terminals 11 and 12 of the calling party and the called party communicate by using a packet transmission method through two access gateways 210 and 220 of the calling party and the called party. In this case, information according to a call may be transmitted through a different path for each packet since the information is transmitted through a packet transmission method.

3 is a diagram illustrating a function of each function according to call setting in a broadband communication network.

Softswitch 100 has protocol blocks 111 and 112 and call processing blocks 151 and 152, and access gateways 210 and 220 have contexts 211 and 221. In addition, the soft switch 100 may be provided with a subscriber DB (170) inside or outside.

The protocol blocks 111 and 112 serve to communicate between the soft switch 100 and the access gateways 210 and 220. Access gateways 210 and 220 are controlled only by protocol messages. Accordingly, the protocol blocks 111 and 112 convert the signals in the soft switch 100 into protocol message forms so that the access gateways 210 and 220 can recognize them.

The call processing blocks 151 and 152 serve to set up an actual call inside the soft switch 100. In addition, the call processing blocks 151 and 152 obtain state information on the call set according to the audit function for the call session, and perform the audit on the call session based on the obtained state information. The call processing blocks 151 and 152 check the state of the telephone terminals 11 and 12 accommodated in the soft switch 100 to determine whether a call connection is possible, and allocate the actual resources of the access gateways 210 and 220. Etc.

The subscriber DB 170 stores state information of the telephone terminal accommodated in the soft switch 100. In addition, a relay line DB (not shown) having a function similar to that of the subscriber DB 170 may be further included due to the soft switch 100 being connected to the public switched telephone network. The relay line DB stores the state information of the telephone terminal accommodated through the public switched telephone network similarly to the subscriber DB 170.

Access gateways 210 and 220 have contexts 211 and 221. The contexts 211 and 221 are resources used for actual telephone service in the access gateways 210 and 220 according to call setup, and are resources allocated by the command of the soft switch 100. The context ID represents the contexts 211 and 221, and the contexts 211 and 221 have different context IDs according to the corresponding terminal and the call.

The protocol blocks 111 and 112 and the call processing blocks 151 and 152 in the soft switch 100 are specifically divided into a calling party and a called party. In addition, the telephone terminals 11 and 12 of the calling party and the called party may exist in different soft switches 100.

In a call setup process in a broadband communication network, a protocol message transmitted from the access gateways 210 and 220 to the soft switch 100 may be lost due to transmission failure of the network. When the protocol message is lost, a situation may arise in which state information about a call session between the access gateways 210 and 220 and the soft switch 100 does not match. For example, if a call is established and the call is normally terminated while the access gateways 210 and 220 are in a call, the access gateways 210 and 220 reclaim the resources allocated to the call and move to an available state. The soft switch 100 notifies that the call has ended. However, if a protocol message indicating that the call is terminated is lost due to transmission failure of the network, the state information of the call session is inconsistent between the soft switch 100 and the access gateways 210 and 220.

As such, the audit operation of the call session is performed to match the state information of the call session between the soft switch 100 and the access gateways 210 and 220.

4 is a flowchart illustrating a call audit operation according to the present invention.

The soft switch 100 drives the audit function of the state information of the call session (S2). The audit operation is driven when the soft switch 100 determines that the call session state information is inconsistent. For example, by performing a ping operation to all gateways accommodated by the soft switch 100 at predetermined time intervals, the audit operation may be performed when a communication failure occurs between the soft switch 100 and the gateway. .

In addition, it is possible to implement a form of driving the audit operation at predetermined time intervals. The audit operation may be driven at a predetermined time interval, that is, 12 hours, 24 hours, or one week, according to the network manager or resource management logic.

When the audit operation is driven in the soft switch 100 (S2), the call processing block 151 of the calling party of the soft switch 100 requests and obtains audit information from the calling gateway 210 (S4).

The request and acquisition of the audit information is performed by the call processing block 151 requesting the context ID for the call performing the audit to the access gateway 210 of the calling party through the protocol block 111. At this time, the protocol block 111 communicates with the access gateway 210 using an Audit message of the MEGACO protocol.

The audit message is a message for inquiring the information of the actually allocated resource for the call in the call session is connected in the soft switch 100. For the Audit message, the access gateway 211 responds with context ID information using the Auditvalue message.

The Auditvalue message is sent to the originating protocol block 111 in response to the Audit message. At this time, if there is no context ID for the audit message, an error message is transmitted. In addition, when an error is responded to an audit message according to an implementation intention of a person skilled in the art, the step of acquiring the audit information from other functional units and devices other than the gateway may be omitted.

In step S4, the call processing block 151 obtains context ID information from the access gateway 210 of the calling party, and then requests and obtains audit information from the call processing block 152 of the called party (S6).

As such audit information, the call processing block 151 of the calling party requests and obtains state information about the call performing auditing by the call processing block 152 of the called party. At this time, when the calling party and the calling party terminals 11 and 12 in step S6 are accommodated in different softswitch 100, the calling party's soft block 100 has the calling party's protocol block 111 and the call processing block. 151 exists, and there exists a protocol block 112 and a call processing block 152 on the called side in a soft switch (not shown) on the called side.

Even in this case, the communication between the two call processing blocks 151 and 152 is similar to the case where the two call processing blocks 151 and 152 exist in the single soft switch 100. The only difference is that the communication between the two call processing blocks 151, 152 is transferred to the other softswitch 100.

According to various implementations by those skilled in the art, steps below step S6 may be omitted depending on the result of step S4. For example, if the call processing block 151 of the calling party has not yet connected a call session, that is, while the calling terminal is dialing, the call processing block 151 of the called party is not generated. The audit information request step is omitted to the call processing block 152 of the called party because it is not.

In the case of an ongoing call, the call processing block 152 of the called party must have the same state information of the call session as the call processing block 151 of the calling party for the call. In other words, when a specific call that performs an audit in the call processing block 151 of the calling party is busy, the call must be in a busy state in the call processing block 152 of the called party. Therefore, the call processing block 151 of the calling party acquires the state information of the call that the call processing block 152 of the called party has with respect to the call. In this case, the call processing block 152 of the called party may not exist. When the call processing block 152 of the called party does not exist in this manner, it is determined that the state information of the call session is inconsistent.

Next, the call processing block 151 of the calling party requests and obtains audit information from the subscriber DB 170 of the soft switch 100 (S8). The subscriber DB 170 stores state information of the telephone terminal accommodated in the soft switch 100. For example, when one terminal accommodated in the soft switch 100 is currently in a call, the subscriber DB 170 stores that the terminal is in a call state (busy). Since the subscriber DB 170 stores the state information on the terminal, when a call connection is requested to a specific terminal, the subscriber DB 170 determines whether to perform the call connection request by checking the state information on the corresponding terminal stored in the subscriber DB 170. Can be.

Therefore, the state information of the terminal stored in the subscriber DB 170 should store the same information as the state information of the call session of the call processing block 151. In the call processing block 151, the specific call is in progress, and the specific terminal accommodated in the soft switch 100 is in a state of making a call, and thus the corresponding terminal in the subscriber DB 170 should be busy.

Thereafter, the call processing block 151 of the calling party of the soft switch 100 receives audit information obtained from the access gateway 210, the call processing block 152 of the called party, and the subscriber DB 170 for the same call session. In operation S10, it is determined whether all state information of the corresponding call session is identical. Audit information obtained in steps S4, S6, and S8 should represent the same status information for the call session.

In other words, a call in progress in the call processing block 151 of the calling party is assigned a call resource at the gateway, a call session is in progress in the call processing block 152 of the called party, and the stored terminal of the subscriber DB 170 is stored. The status information of must be in a busy state. It is determined whether the state information of the gateway, the call processing block 152 of the called party, and the subscriber DB 170 for the specific call is consistent.

If the state information does not match in step S10, the state information for the call session is initialized (S12). Initialization of the status information idles all the status information related to the call session, that is, the status information of the call processing block 151, the access gateway 210, the subscriber DB 170, and the call processing block 152 of the called party. It is set to (idle) state. If the status information is inconsistent, the use of resources is abnormal and the resource management of the call session is in an abnormal state, so that the status information of all the functional units and equipment related to the call session is set to an available state.

The format of the Audit and Auditvalue messages according to the present invention is as follows.

5A to 5B illustrate the Audit and Auditvalue message formats according to the present invention.

Figure 5a shows the format of the audit message according to the MEGACO protocol. The audit message identifies the call to be audited with the information of the terminal in use. In other words, the Audit message queries the context ID information M1 using the information M2 of the terminal using the specific call session. Termination ID M2 is used as information indicating a terminal using a particular call session. Therefore, the Audit message is to query the context ID (M1) corresponding to the termination ID (M2) using the call session to be audited. In addition, the audit message includes index number information and port information of the audit message for distinguishing the audit message from the address of the soft switch 100.

5B illustrates the format of an Auditvalue response message for an Audit message.

The Auditvalue message is in a format similar to the Audit message and further includes a context ID (M3) corresponding to the requested termination ID (M4).

In the preferred embodiment of the present invention, the auditing operation at the calling party is described as an example, but the auditing operation at the called party is also possible, which is the same as the auditing operation at the calling party. The audit operation on the called party is performed by the call processing block 152 of the called party, and collects audit information for the called party rather than the calling party to perform the auditing operation.

As described above, the soft switch and the call session auditing method in the broadband communication network according to the present invention, in the establishment of a call session between the soft switch and the gateway for providing a telephone service in the broadband communication network, abnormal processing, network failure, etc. Auditing whether there is a discrepancy between call session state information between the soft switch and the gateway, it reflects the exact resource and call state, thereby providing service continuity and operational stability of the system in the broadband communication network.

In addition, a preferred embodiment of the present invention is for the purpose of illustration, those skilled in the art will be able to various modifications, changes, substitutions and additions through the spirit and scope of the appended claims, such modifications and changes are the following claims It should be seen as belonging to a range.

Claims (10)

In the call session auditing method of a Broadband Convergence Network (BcN) including at least one soft switch device and a gateway device, A first step of operating a call session auditing function for a specific call session of the soft switch device; A second step of the soft switch device querying the gateway device for information on resources allocated by the gateway device for the call session; A third step of receiving a response to the query of the second step from the gateway device, and comparing information of resources allocated for the call session with state information of the call session previously stored in the soft switch device; And And a fourth step of initializing the state information of the call session when the state information of the call session and the response do not match in the third step. The method of claim 1, Call session auditing method in a broadband communication network, characterized in that the information of the resource allocated by the gateway device for the call session includes context ID information. The method of claim 1, wherein the second step, Call session auditing method in a broadband communication network, characterized in that for collecting the information of the resources allocated by the gateway device for the call session using the audit message of the MEGACO (Media Gateway Control) protocol. The method of claim 1, wherein the third step, And obtaining the state information of the call session from the plurality of soft switch devices when the call session uses resources of the plurality of soft switch devices. The method of claim 1, wherein the initialization of the state information of the third step, Call session auditing method in a broadband communication network, characterized in that the soft switch device and the gateway device in the state assigned resources and stored state information for the call session is switched to the idle (idle) state. A protocol block for performing communication using a protocol message with a gateway provided in a broadband communication network; And By using the protocol block, a call processing block for acquiring information of resources allocated by the gateway for a predetermined call session, and comparing the information with the state information of the call session to initialize the state information of the call session. And a soft switch in a broadband communication network. The method of claim 6, wherein the resource information, And a context ID information of the gateway. The method of claim 6, wherein the protocol block, Soft switch in the broadband communication network, characterized in that for collecting the information of the resources allocated by the gateway for the call session using the MEGACO (Media Gateway Control) protocol. The method of claim 6, wherein the call processing block, And when the call session uses resources of a plurality of soft switch equipments, obtains state information of the call sessions from the plurality of soft switch equipments. The method of claim 6, wherein the call processing block, Soft switch in the broadband communication network, characterized in that for initializing the state information of the call session by switching the resources allocated for the call session to the idle (idle) state.

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