JP2011049687A - Communication network system, sip signal relay method therefor and sip application server - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an SIP application server to reliably specify the other SIP application servers located on the same SIP signal path and their service classes at all times. <P>SOLUTION: Whether a specified SIP header has been already added to a received SIP signal is determined first. When determined that the specified SIP header has not been added yet, the specified SIP header which includes the identification information of the server and an identifier indicating the class of a service provided by the server as information elements and whose deletion and change are prohibited is added to the received SIP signal. On the other hand, when determined that the specified SIP header has already been added, whether the identification information of the server and the identifier indicating the class of the service provided by the server are included in the specified SIP header is determined. When determined that they are not included, the identification information of the server and the identifier indicating the class of the service provided by the server are added to the end of the specified SIP header. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention uses a SIP (Session Description Protocol) as a communication protocol, forms a SIP signal path between endpoints via a SIP application server, and transfers the SIP signal. The present invention relates to a SIP signal relay method and a SIP application server.

  A next generation network (NGN) discussed in ITU-T and the like assumes a network architecture in which services are provided via an IP (Internet Protocol) network. NGN has decided to adopt IMS formulated by 3GPP (3rd Generation Partnership Project), which is a standard organization for third-generation mobile communication networks, and provides network services using this IMS. IMS (IP Multimedia Subsystem) is a subsystem that performs service execution control, session control between terminals, registration processing, charging processing, and the like by using SIP (Session Initiation Protocol) as a protocol.

  Further, in IMS, by using an application server (SIP AS) using SIP, it is possible not only to establish a multimedia session between two parties but also to execute an extended service. When this extended service is used, a request for establishing a new dialog transmitted from the user terminal at the time of outgoing or incoming call is transferred from the SIP server to the SIP application server in accordance with the subscriber's service subscription conditions. Then, a SIP signal path that passes through the SIP application server is formed between each user terminal of the source and destination, and thereafter, various services by the SIP application server are provided to the user terminal by using the SIP signal path. To do.

  By the way, in general, some SIP application servers may be able to leave the SIP signal path in the SIP dialog after the SIP dialog is established. For example, when the user terminal that provided the service by the SIP application server stops using the service, the SIP application server becomes substantially unnecessary. However, in the conventional system, the SIP application server once inserted in the SIP signal path continues to intervene in the SIP signal path and performs unnecessary relay processing until the session ends. For this reason, various problems such as an increase in processing load on the SIP application server, an increase in delay of SIP signals, and a waste of network resources accompanying an increase in the number of SIP signals occur.

  Therefore, in order to identify a SIP application server that has become substantially unnecessary on the SIP signal path, it has been studied to apply a technique for identifying a SIP entity interposed on the SIP signal path. The technology for identifying this SIP entity uses, for example, the Via header and Record-Route header added to the SIP signal exchanged when forming the SIP signal route, and other headers that exist on the SIP signal route from these headers. A URI (Uniform Resource Identifier) of a SIP entity is detected (for example, see Non-Patent Document 1).

IETF RFC 3261 “SIP: Session Initiation Protocol” June 2002, Internet <URL http://www.ietf.org/rfc/rfc3261.txt>

  However, the technology described in Non-Patent Document 1 that identifies other SIP entities existing on the SIP signal path from the Via header or Record-Route header is used only to identify the route through which the SIP signal passes. Therefore, it is impossible to specify the type of the specified SIP entity.

  Non-Patent Document 1 describes that a new extension parameter can be defined and set as a parameter of an information element in a Via header or a Record-Route header. However, Via header and Record-Route header are generally called B2BUA (Back-to-Back User Agent), which is deleted or modified when SIP signal is relayed by SIP entity editing / deleting, etc. There is. For this reason, the information element set in the header on the SIP signal path does not always circulate between the endpoints of the SIP signal path. Therefore, even if it is defined that an identifier for identifying the SIP entity type is set in the extension parameter of the Via header or Record-Route header, the SIP entity type cannot always be identified.

  The present invention has been made paying attention to the above circumstances, and the purpose of this invention is to identify the types of services provided by the SIP application server and other SIP application servers that exist on the same SIP signal path. It is an object of the present invention to provide a communication network system, its SIP signal relay method, and SIP application server that can always reliably identify a network.

  In order to achieve the above object, one aspect of the present invention is communication that uses SIP (Session Description Protocol) as a communication protocol, and forms a SIP signal path through a plurality of SIP application servers to transfer the SIP signal. In the network system, when a SIP signal transferred on the SIP signal path is received by each of the plurality of SIP application servers, at least the identification information of the local server and the service provided by the local server are added to the received SIP signal. Add a specific SIP header that includes an identifier indicating the type of information as an information element, and prohibits deletion and modification, and relays the SIP signal with this specific SIP header added onto the SIP signal path. It is what.

  Therefore, when a SIP application server relays and forwards a SIP signal, a specific SIP header including the identification information of the server itself and an identifier indicating the type of service provided by the server as an information element is added to the SIP signal. Is done. For this reason, SIP application servers intervening on the same SIP signal path intervene on the same SIP signal path by reading a specific SIP header added to the SIP signal when relaying the SIP signal. It is possible to recognize the location of other SIP application servers and their service types. Therefore, for example, in an SIP application server, if an identifier indicating the service type is described in a specific SIP header, the corresponding SIP application server is removed from the SIP signal path based on this identifier. It becomes possible to do.

  Specifically, when adding the specific SIP header, it is first determined whether or not the specific SIP header has been added to the received SIP signal, and it is determined that the specific SIP header has not been added In addition, a specific SIP header including identification information of the local server and an identifier indicating the type of service provided by the local server as information elements is added to the SIP signal. On the other hand, if it is determined that the specific SIP header has been added, whether or not the specific SIP header includes identification information of the local server and an identifier indicating the type of service provided by the local server. judge. When it is determined that the identification information and the identifier are not included, the identification information of the local server and the identifier indicating the type of service provided by the local server are added to the end of the specific SIP header. When it is determined that the identification information and the identifier are included, the SIP signal is transmitted without performing the additional processing.

  In this way, a plurality of specific SIP headers are added to the SIP signal, or the same SIP application server identification information and an identifier representing the service type are inserted into the specific SIP header. Problems can be prevented, thereby reducing the SIP signal overhead.

  That is, according to the present invention, a communication network system in which a SIP application server can always reliably identify another SIP application server existing on the same SIP signal path and the type of service provided by the server, and A SIP signal relay method and a SIP application server can be provided.

1 is a schematic configuration diagram of a communication network system including a SIP application server according to an embodiment of the present invention. It is a block diagram which shows the function structure of the SIP application server concerning one Embodiment of this invention. The flowchart which shows the procedure and content of the SIP signal relay process by the SIP application server shown in FIG. The figure which shows an example of the information added to a specific SIP header in each SIP application server in the establishment process of a SIP signal path | route.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a communication network system including a SIP application server according to an embodiment of the present invention.
This communication network system includes a network based on IMS (IP Multimedia Subsystem) managed by a communication carrier, and uses SIP (Session Initiation Protocol) as a communication protocol.

The network NW includes a plurality of SIP servers SSV1 to SSVn, a plurality of SIP application servers (AS) ASV1 to ASVm, and a subscriber information database (HSS: Home Subscriber Server) DB.
Among these, the SIP servers SSV1 to SSVn are respectively S-CSCF (Serving-Call Session Control Function) 11, P-CSCF (Proxy-Call Session Control Function) 12, and I-CSCF (Interrogating-Call Session Control Function) 13. have. The P-CSCF 12 functions as a proxy server, and user terminals UE1 to UEn such as a mobile phone, a PDA (Personal Digital Assistant), and a personal computer are connected to the P-CSCF 12.

  The S-CSCF 11 functions as a session control server. Based on the subscriber information stored in the subscriber information database (HSS) DB, the S-CSCF 11 is based on SIP for the subscriber terminals UE1 to UEn and the SIP application servers ASV1 to ASVm. Perform session control processing such as session establishment and release.

The SIP application servers ASV1 to ASVm provide various services to subscribers (users), and are connected to the S-CSCF 11 in the network NW and also to the maintenance terminal MT. As an additional service, for example, a CAT (Customized Alerting Tone) service that provides a special ringing tone such as music data instead of RBT (Ring Back Tone) to a calling subscriber terminal, or a subscriber terminal that performs a hold operation For example, there is a hold service that provides a hold sound, an answering service that records call voice data transmitted from a subscriber terminal, and the like.
The maintenance terminal MT is used by a communication carrier operating this network NW for network maintenance and management.

By the way, the SIP application servers ASV1 to ASVm are configured as follows. FIG. 2 is a block diagram showing the configuration.
That is, the SIP application servers ASV1 to ASVm each include a socket unit 31, a SIP communication control unit 32, a SIP call control unit 33, a session management data storage unit 34, and a SIP session timer control unit 35. A header control unit 36, a SIP message body control unit 37, an application service logic storage unit 38, an application service logic management unit 39, a SIP application / server type storage unit 40, and a SIP application / server type management unit 41 are provided. ing.

  The socket unit 31 is used to connect the own server to the SIP communication network NW and the maintenance network. The SIP communication control unit 32 transmits and receives SIP signals to and from the SIP communication network NW via the socket 31. The SIP call control unit 33 performs call control by SIP based on the management data stored in the session management data storage unit 34. The SIP session timer control unit 35 measures the response time of the SIP control signal, and the SIP call control unit 33 executes retransmission control based on the time measured by the SIP session timer control unit 35.

  The application service logic storage unit 38 stores the service logic of the application provided by the server itself and information indicating the criteria for determining whether or not to leave the SIP signal path. For example, “cancellation of service use by user terminal” or “existence of other SIP application servers having the same service type on the same signal path.” The application service logic management unit 39 In accordance with the input operation of the maintenance terminal MT, the storage, change and deletion of the information indicating the service logic and the detachability determination criterion with respect to the application service logic storage unit 38 are controlled.

  The SIP application / server type storage unit 40 is used to store identification information of the own server and an identifier representing the type of service provided by the own server. The SIP application / server type management unit 41 controls the storage, change, and deletion of the identification information and the service type identifier with respect to the SIP application / server type storage unit 40 in accordance with the input operation of the maintenance terminal MT. As server identification information, for example, either SIP-URI or SIPS-URI is used.

  The SIP header control unit 36 performs processing for adding a specific SIP header according to the present invention in addition to processing for a general SIP header added to the SIP signal input from the SIP call control unit 33. This specific SIP header is used to describe the URI of the local server and an identifier representing the type of service provided by the local server. Further, the header name of the specific SIP header is a header whose header or its contents are prohibited from being deleted or changed. The SIP message body control unit 37 performs processing on the message body of the SIP signal input from the SIP call control unit 33. The specific SIP header is related to the leaving process such as the identifier indicating the leaving schedule from the SIP signal transfer path in addition to the URI of the own server and the identifier indicating the type of service provided by the own server. Other identifiers may be described.

Next, a specific SIP header addition control operation by the SIP application servers ASV1 to ASVm configured as described above will be described. FIG. 3 is a flowchart showing the processing procedure and processing contents.
In the SIP application servers ASV1 to ASVm, the SIP call control unit 33 monitors the reception of the SIP signal in step S51. When a SIP signal is received in this state, the SIP header control unit 36 first determines in step S52 whether a specific SIP header has already been added to the received SIP signal. If the specific SIP header is not added as a result of this determination, in step S54, the URI of the local server and the identifier representing the type of service provided by the local server are obtained via the SIP call control unit 33. Read from the type storage unit 40. Then, a specific SIP header including the read URI and service type identifier as an information element and prohibited from being deleted or changed is generated, and the generated specific SIP header is added to the received SIP signal. . The specific SIP header is related to the leaving process such as the identifier indicating the leaving schedule from the SIP signal transfer path in addition to the URI of the own server and the identifier indicating the type of service provided by the own server. Other identifiers may be described.

  On the other hand, it is assumed that the specific SIP header has already been added to the received SIP signal as a result of the determination in step S52. In this case, in step S53, the SIP header control unit 36 determines whether the URI of the own server and the identifier of the service type are described in the already added specific SIP header. As a result of this determination, if the URI of the own server and the identifier of the service type have not yet been described, the URI of the own server and the identifier of the service type are added to the end of the specific SIP header in step S55. At this time, processing other than the addition of the information element, that is, replacement or deletion is prohibited for the specific SIP header. Also, at the end of the specific SIP header, in addition to the URI of the local server and the identifier indicating the type of service provided by the local server, an identifier that indicates the departure schedule from the SIP signal transfer path, etc. Other identifiers may be added.

  On the other hand, if the URI of the own server and the identifier of the service type have already been described in the specific SIP header, the SIP call control unit 33, together with the SIP message body control unit 37 and the SIP header control unit 36, in step S56, Perform the necessary SIP signal processing. And the SIP communication control part 32 transmits the SIP signal after this process to the SIP communication network NW by step S57.

FIG. 4 shows an example of a change in a specific SIP header when the above-described specific SIP header addition control is performed in each SIP application server ASV1 to ASV4 in the process of establishing a SIP signal path (SIP session). It is shown.
As shown in the figure, first, in the SIP application server ASV1 located on the upstream side of the SIP control signal, since the specific SIP header XH has not yet been added to the received session establishment request INVITE, the URI (ASV1 ) And an identifier (ID001) indicating the type of service provided by the local server is generated as an information element and added to the received INVITE.

  Subsequently, in the SIP application server ASV2 arranged downstream thereof, since the specific SIP header XH is already added to the received session establishment request INVITE, the URI provided by the own server (ASV2) and the service provided by the own server Is added to the end of the specific SIP header XH. Similarly, in the SIP application servers ASV3, ASV4,..., The URI (ASV3, ASV4,...) Of the server and the identifier (ID003, ID001, ID009,. Added to the end of the specific SIP header XH.

  If a response 200 OK to the session establishment request INVITE is received, the specific SIP header XH is already added to the 200 OK, and the URI of the local server and the local server are included in the specific SIP header XH. Since the identifier representing the type of service to be provided has already been described, each SIP application server ASV4, ASV3,... Transfers the response 200 OK as it is without changing the specific SIP header XH. Note that the same specific SIP header addition processing is also performed when a 1xx response or an ACK request is received.

  After the session is established, each SIP application server ASV1 to ASVm existing on the SIP signal path uses the specific SIP header XH added to the received SIP signal, so that the same SIP signal can be obtained. It is possible to recognize the presence / absence of a SIP application server other than itself on the route and the type of service provided by the server. Then, based on the recognition result, it is determined whether or not it is possible to leave the own server from the SIP signal path, and when it is determined that the server can be left, a process for removing the own server from the SIP signal path is performed. Can do.

  For example, in the example shown in FIG. 4, when the SIP application server ASV3 receives the SIP signal, ASV1; ID001 and ASV3; ID001 described in the specific SIP header added to the SIP signal, It can be recognized that another SIP application server ASV1 that provides the same type of service as that provided by its own server ASV3 exists on the same SIP signal path.

  Then, the SIP application server ASV3 executes processing for causing the own server to leave the SIP signal path based on the recognition result. In this leaving process, for example, a SIP request UPDATE is sent to the SIP application server located at the end point on the SIP signal path, and the SIP application server located at both end points on the SIP signal path is sent. It is executed when it is confirmed that the response 200 OK is returned from.

  As described above in detail, in this embodiment, the SIP signal received in the session establishment process includes at least identification information of the local server and an identifier indicating the type of service provided by the local server as information elements, and is deleted and changed. Is added, and a SIP signal to which the specific SIP header XH is added is transmitted on the SIP signal path.

  Further, when adding the specific SIP header XH, first, it is determined whether or not the specific SIP header XH has been added to the received SIP signal, and it is determined that the specific SIP header XH has not been added. In this case, a specific SIP header XH including at least identification information of the local server and an identifier indicating the type of service provided by the local server as an information element and prohibited from being deleted or changed is generated, and the specific SIP header Add XH to the received SIP signal. In contrast, if it is determined that the specific SIP header XH has been added, does the specific SIP header include the identification information of the XH local server and the identifier indicating the type of service provided by the local server? If it is determined that it is not included, at least the identification information of the local server and an identifier indicating the type of service provided by the local server are added to the end of the specific SIP header XH. .

  Therefore, in the SIP application server, when the SIP signal is relayed and transferred, the SIP signal includes a specific SIP header XH including identification information of the own server and an identifier indicating the type of service provided by the own server as information elements. Added. For this reason, in a SIP application server that intervenes on the same SIP signal path, when a SIP signal is relayed and transferred, the specific SIP header XH added to the SIP signal is read, so that the same SIP signal path can be read. It is possible to recognize the location of other intervening SIP application servers and their service types.

  In addition, in addition control of a specific SIP header, it is determined whether or not a specific SIP header XH has been added, and whether or not the URI and service type identifier of the local server have been described in the specific SIP header XH. As a result, multiple specific SIP headers are added to the SIP signal, or the same SIP application server identification information and the identifier indicating the service type are inserted into the specific SIP header. Problems can be prevented, thereby reducing the SIP signal overhead.

  The present invention is not limited to the above-described embodiment, and identification information other than URI and ID may be used for SIP application server identification information and service type identifier. Further, in the above-described embodiment, in addition to the identification information of the local server and the identifier indicating the type of service provided by the local server in the specific SIP header, the identifier is related to the disconnection process such as an identifier expressing the planned disconnection from the SIP signal transfer path. He stated that other identifiers could be described. However, the present invention is not limited to this. Separately from the specific SIP header including the identification information of the own server and the identifier indicating the type of service provided by the own server, an identifier or the like indicating the departure schedule from the SIP signal transfer path. A second specific SIP header including other identifiers related to the leaving process may be generated and added to the SIP signal. In addition, the configuration and number of SIP application servers, the configuration of a specific SIP header, the additional control procedure of the specific SIP header, and the contents thereof can be variously modified and implemented without departing from the gist of the present invention.

  In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  NW ... IMS network, SSV1 to SSVn ... SIP server, ASV1 to ASVm ... SIP application server, DB ... subscriber information database, UE1, UE2 ... user terminal, MT ... maintenance terminal, 11 ... S-CSCF, 12 ... P- CSCF, 13 ... I-CSCF, 31 ... Socket unit, 32 ... SIP communication control unit, 33 ... SIP call control unit, 34 ... Session management data storage unit, 35 ... SIP session timer control unit, 36 ... SIP header control unit 37... SIP message body control unit 38... Application service logic storage unit 39... Application service logic management unit 40... SIP application server type storage unit 41.

Claims (6)

In a communication network system that uses SIP (Session Description Protocol) as a communication protocol and transfers SIP signals by forming SIP signal paths that pass through multiple SIP application servers.
Each of the plurality of SIP application servers is
Receiving means for receiving a SIP signal transferred on the SIP signal path;
Header addition control for adding, to the received SIP signal, a specific SIP header that includes at least identification information of the local server and an identifier representing the type of service provided by the local server as information elements and is prohibited from being deleted or changed Means,
A communication network system comprising: a transmission unit configured to transmit a SIP signal to which the specific SIP header is added onto the SIP signal path. The header addition control means includes
Means for determining whether or not the specific SIP header has been added to the received SIP signal;
When it is determined that the specific SIP header has not been added, at least the identification information of the local server and the identifier indicating the type of service provided by the local server are included as information elements, and the specific SIP that is prohibited from being deleted or changed Means for generating a header and adding the generated specific SIP header to the received SIP signal;
Means for determining whether or not the specific SIP header includes identification information of the local server and an identifier representing a type of service provided by the local server when it is determined that the specific SIP header has been added; ,
When it is determined that the specific SIP header does not include the identification information of the local server and the identifier indicating the type of service provided by the local server, the identification information of the local server and the local server are included at the end of the specific SIP header. 2. The communication network system according to claim 1, further comprising means for adding an identifier representing a type of service provided by the server. In a communication network system that uses SIP (Session Description Protocol) as a communication protocol and forms SIP signal paths through multiple SIP application servers to transfer SIP signals, the SIP application server relays and forwards SIP signals. SIP signal relay method to
Receiving a SIP signal for transfer on the SIP signal path;
Adding at least identification information of the own server and an identifier representing the type of service provided by the own server as an information element, and adding a specific SIP header prohibited from being deleted and changed to the received SIP signal;
A SIP signal relay method comprising: transmitting a SIP signal to which the specific SIP header is added onto the SIP signal path. The process of adding the specific SIP header is as follows:
Determining whether the specific SIP header has been added to the received SIP signal;
When it is determined that the specific SIP header has not been added, at least the identification information of the local server and the identifier indicating the type of service provided by the local server are included as information elements, and the specific SIP that is prohibited from being deleted or changed Generating a header and adding the generated specific SIP header to the received SIP signal;
A step of determining whether or not the specific SIP header includes identification information of the local server and an identifier representing a type of service provided by the local server when it is determined that the specific SIP header has been added; ,
When it is determined that the specific SIP header does not include the identification information of the local server and the identifier representing the type of service provided by the local server, the identification information of the local server and the identification information of the local server are included at the end of the specific SIP header. 5. The SIP signal relay method according to claim 4, further comprising a step of adding an identifier representing a type of service provided by the server. The SIP application server used in a communication network system that uses SIP (Session Description Protocol) as a communication protocol and transfers a SIP signal by forming a SIP signal path via a plurality of SIP application servers,
Receiving means for receiving a SIP signal transferred on the SIP signal path;
Header addition control for adding, to the received SIP signal, a specific SIP header that includes at least identification information of the local server and an identifier representing the type of service provided by the local server as information elements and is prohibited from being deleted or changed Means,
A SIP application server, comprising: a transmission unit configured to transmit a SIP signal to which the specific SIP header is added onto the SIP signal path. The header addition control means includes
Means for determining whether or not the specific SIP header has been added to the received SIP signal;
When it is determined that the specific SIP header has not been added, at least the identification information of the local server and the identifier indicating the type of service provided by the local server are included as information elements, and the specific SIP that is prohibited from being deleted or changed Means for generating a header and adding the generated specific SIP header to the received SIP signal;
Means for determining whether or not the specific SIP header includes identification information of the local server and an identifier representing a type of service provided by the local server when it is determined that the specific SIP header has been added; ,
When it is determined that the specific SIP header does not include the identification information of the local server and the identifier indicating the type of service provided by the local server, the identification information of the local server and the local server are included at the end of the specific SIP header. 8. The SIP application server according to claim 7, further comprising means for adding an identifier representing a type of service provided by the server.

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