JP2011151474A - Address converter, communication system, message communication method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique achieving an address conversion processing of a message without holding address correspondence information in preparation for an incoming call in an address converter, in a communication service network using an SIP (Session Initiation Protocol). <P>SOLUTION: An address converter is installed in a boundary part between an access network and a core network and is used. The address converter is configured to receive from a user terminal a registration message including the address of the user terminal as information of a contact header, to determine an external address being a core network side address in the address converter for the user terminal, to add the external address to the registration message as information of a prescribed header, and to transmit to a SIP server the registration message with the external address added thereto by including the registration message in a packet in which the external address is designated as a transmission source address. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention performs an address conversion process of signals transmitted and received between a plurality of communication networks, which are arranged at a boundary portion of a plurality of communication networks configured to provide a communication service using SIP (Session Initiation Protocol). The present invention relates to an address translation device to be performed.

  When a service is operated by multiple carriers in a communication service network using SIP such as an IP telephone service network, a session border controller (SBC: Session Border Controller) The SBC device is installed to absorb system differences between communication networks.

  Also, the SBC device may be installed and used at the boundary between the core network and the access network in the same ISP or carrier for the purpose of concealing address information and ensuring security.

  In addition, there exists patent document 1 as a prior art document relevant to this application.

JP 2007-318707 A

  FIG. 1 shows a configuration example of a communication system when an SBC device is used to connect a core network and an access network. As shown in FIG. 1, the communication system is configured by connecting a core network 2 and an access network 3 by an SBC device 1. Each of the core network 2 and the access network 3 is a network capable of data communication by IP (Internet Protocol). Further, a PSTN 4 (Public Switched Telephone Network) is connected to the core network 2 in the example of FIG. 1 via the PSTN-GW 5.

  A user terminal 6 is connected to the access network 3, and a SIP server 7 is connected to the core network 2, and each user terminal communicates with other user terminals connected to the core network by control communication based on SIP. It is possible to implement VoIP telephone communication. Although only three user terminals (such as telephone terminals capable of SIP communication) are shown in FIG. 1, a large number of user terminals are actually connected to each network. A plurality of access networks are connected to the core network 2. The SIP server 7 is a server having all the SIP functions.

  In a communication service network using SIP, a REGISTER message for requesting the SIP server 7 to bind the name of the user terminal 6 such as the telephone number and the address of the user terminal 6 to the SIP server 7 from the user terminal 6. (Also called a registration message) is sent periodically.

  Here, when the SBC device 1 is installed at the boundary between the access network 3 and the core network 2 as shown in FIG. 1, signals transmitted and received between the access network 3 and the core network 2 are always SBC devices. Go through 1. Therefore, in a system including the SBC device 1 as shown in FIG. 1, the SBC device 1 periodically receives a REGISTER message from each user terminal 6, performs address conversion processing, and performs a SIP server in the core network 2. Forward the REGISTER message to 7. Further, when a call is made to the user terminal 6 in the access network 3, the SBC device 1 receives an INVITE message (also referred to as a connection request message) related to the incoming call from the SIP server 7, performs address conversion, Processing to transmit to the user terminal 6 is performed.

  For example, as shown in FIG. 2, the SBC device 1 that performs the address conversion process as described above includes an address of a user terminal and an address (on the core network 2 side) outside the SBC device 1 corresponding to the user terminal ( Address correspondence information in which the external address is associated is stored in storage means such as a memory. Note that in a communication network based on SIP, a message transmission destination is identified by a pair of an IP address and a port number, and the above “address” indicates a pair of an IP address and a port number. In this specification, unless otherwise specified, “address” is used to mean a set of an IP address and a port number.

  An outline of a processing sequence when the SBC device 1 storing the address correspondence information shown in FIG. 2 is used will be described with reference to FIG. In the example of FIG. 3, the address of the user terminal 6 is address A, and the external address corresponding to the user terminal 6 in the SBC device 1 is address G.

  The user terminal 6 sends a REGISTER message describing its own address A in the Contact header (step 1). The address described in the Contact header is stored in association with the name (described in the To header in the REGISTER message) in the SIP server 7 or the like, and used as the address of the request message addressed to the user terminal 6 (request URI). It is what is done.

  The SBC device 1 receives the REGISTER message, converts the address A in the Contact header into an address G, which is an external address of the SBC device 1, and associates the address A with the address G in the storage means as address correspondence information. Store (step 2). The SBC device 1 transfers a REGISTER message in which the address G is described in the Contact header to the SIP server 7 (step 3), and the SIP server 7 performs processing based on normal SIP such as storing the correspondence between the name and the address G. Is executed (step 4).

  Thereafter, a response message is returned from the SIP server 7 to the SBC device 1 (step 5). The SBC device 1 searches the address correspondence information and extracts the address A corresponding to the address G described in the Contact header. The address of the Contact header is converted (step 6), and a response message is transmitted to the user terminal 6 (step 7).

  Subsequently, when a call connection request (INVITE message) specifying the name of the user terminal 6 arrives at the SIP server 7 from an external user terminal, the SIP server 7 acquires an address G corresponding to the name, An INVITE message in which the address G is set in the URI (R-URI) is transmitted to the SBC device 1 (step 8). The SBC device 1 that has received the INVITE message searches the address correspondence information, extracts the address A corresponding to the address G, converts the R-URI, and transmits the INVITE message to the user terminal 6 (steps 9 and 10). ).

  In preparation for an incoming call to each user terminal 6 existing under the access network 3, the SBC device 1 must always retain address correspondence information, but depending on the number of user terminals 6 existing under the access network 3. There is a problem that the amount of data to be stored becomes enormous, and the hardware resources (memory amount and the like) of the SBC device 1 may be compressed. In addition, when the address correspondence information disappears due to a failure of the SBC device 1 or the like, the user terminal 6 cannot receive incoming calls from outside unless the REGISTER message is sent again from the user terminal 6. is there.

  Further, when there is an incoming call for each user terminal 6, the SBC device 1 must always search for address correspondence information, and depending on the amount of data to be searched, the load for the search process is large. Therefore, there is a problem that the processing capacity of the SBC device 1 may be compressed.

  The present invention has been made in view of the above points. In an address translation device such as an SBC device in a communication service network using SIP, an address in SIP message communication is maintained without holding address correspondence information in preparation for an incoming call. A technique that enables conversion processing is provided.

  In order to solve the above problems, the present invention provides a communication service network having an access network connected to a user terminal and a core network connected to a SIP server, at a boundary portion between the access network and the core network. An address translation device used for receiving a registration message including the address of the user terminal as Contact header information from the user terminal, and an address on the core network side in the address translation device An external address is determined for the user terminal, external address adding means for adding the external address to the registration message as information on a predetermined header, and the external address added as information on the predetermined header The SIP message is included in a packet in which the external address is specified as a source address. And an address translation device comprising a transmission means for transmitting data to the server.

  The address translation device receives a response message to the registration message from the SIP server, acquires the address of the user terminal described in a Contact header included in the response message, and uses the response message as a destination address. The user terminal address may be included in a designated packet for transmission.

  In addition, the address translation device receives a connection request message having the address of the user terminal as a transmission destination from the SIP server, and sends the connection request message to a packet in which the address of the user terminal is designated as a destination address. It may be configured to include and transmit to the user terminal. Further, a Path header may be used as the predetermined header.

  According to the present invention, in an address translation device that is installed and used at the boundary between an access network and a core network, when a registration message is received, the address of the contact header is not translated, The external address, which is the assigned core network address, is added to the registration message as predetermined header information, and the registration message with the external address added is sent to the SIP server. Addresses and user terminal addresses can be managed in association with each other. Therefore, when the SIP server receives the connection request message, the address of the user terminal can be set as the request destination (R-URI), and the connection request message can be transmitted to the address translation device. Therefore, the address translation device can transmit a connection request message to the user terminal according to the R-URI without searching for address correspondence information.

1 is a diagram illustrating a configuration example of a system using an SBC device 1. FIG. It is a figure which shows the address corresponding | compatible information which the conventional SBC apparatus 1 stores. It is a sequence diagram for demonstrating the process in the conventional system. 1 is a configuration diagram of a system according to an embodiment of the present invention. It is a functional lineblock diagram of SBC device 10 concerning an embodiment of the invention. It is a sequence diagram for demonstrating operation | movement of the system which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention can be applied to any service as long as it is a communication service using SIP. However, in the following embodiments, the case where the present invention is applied to an IP telephone service is assumed as an example. .

  Since the basic function of the SBC device 10 described below is an address conversion function in various layers, the SBC device 10 can also be called an address conversion device. The SBC device 10 is an example of an address translation device according to the present invention, and the address translation device according to the present invention is not limited to the SBC device. For example, the present invention can be applied to a NAT device.

(System configuration)
FIG. 4 shows a configuration diagram of a system according to the embodiment of the present invention. Although the overall configuration of the system shown in FIG. 4 is the same as that shown in FIG. 1, the system shown in FIG. 4 is installed at the boundary between the core network 2 and the access network 3 according to one embodiment of the present invention. The two are different in that the SBC device 10 is a form. Further, the SIP server 7 in the present embodiment includes a function for processing a Path header compliant with RFC3327.

  The access network 3 in the present embodiment may be any one of a carrier that manages the SIP server 7 or an IP network of an ISP, another carrier or an IP network of another ISP, the Internet, and an in-company network. A network configured by connecting a plurality of these networks may be used. An IP network other than these networks may be used.

  FIG. 5 shows a functional configuration diagram of the SBC device 10. As shown in FIG. 5, the SBC device 10 according to the present embodiment includes an access network communication unit 11, an anti-core network communication unit 12, an external address determination unit 13, a SIP message processing unit 14, and a media communication unit 15. . The contents of the processing of each functional unit will be described in detail in the description of the system operation described later, and the outline of the function of each functional unit will be described below.

  The access network communication unit 11 is a functional unit for performing data communication such as SIP message communication and media communication with a device (such as a user terminal) in the access network 3. The core network communication unit 12 is a functional unit for performing data communication such as SIP message communication and media communication with devices (SIP server, external user terminal, etc.) in the core network 2.

  The external address determination unit 13 is a functional unit that determines and assigns an address on the core network 2 side of the SBC device 10 as an external address corresponding to the user terminal 6 that has transmitted the REGISTER message. The SIP message processing unit 14 is a functional unit for performing processing on the SIP message such as adding / deleting header information to / from the SIP message. The SIP message processing unit 14 includes a SIP message conversion function as a general function of the SBC, a description conversion function related to media communication, and the like, but the function is not necessarily a necessary function in the present embodiment. Detailed description will be omitted.

  The media communication unit 15 communicates between a user terminal on the access network 3 side and a user terminal on the core network 2 side (a user terminal connected to a network such as an access network connected to the core network 2). This is a functional unit for relaying media (sound in this embodiment).

  Note that the configuration of the SBC device 10 described above shows the configuration related to the processing of the present embodiment, and it is needless to say that other functional units as the SBC device may be further included.

  The SBC device 10 can be realized by mounting a program for performing processing corresponding to each functional unit on a general computer including a storage unit such as a memory and a hard disk and a CPU. The program may be installed in the computer from a recording medium such as a portable memory or a disk, or may be downloaded from a server on a network to the computer and installed.

(System operation)
Next, the operation of the system according to the present embodiment will be described with reference to the sequence chart of FIG.

  In the example described below, the address of the user terminal 6 is the address A, the address on the access network 3 side in the SBC device 10 is the address P, the external address corresponding to the user terminal 6 assigned to the SBC device 10 is the address G, and the SIP server Address 7 is address S.

  On each sequence in the figure, an outline of the configuration of an IP packet (hereinafter simply referred to as a packet) including a SIP message to be transmitted is described. In the configuration of each packet shown in the figure, the “destination” and “transmission source” portions indicate address information that is a pair of an IP address and a port number, respectively, and the type of SIP message such as REGISTER is described. Indicates SIP layer information. FIG. 6 shows only information necessary for the description of the present embodiment.

  In FIG. 6, the user terminal 6 transmits a packet including a REGISTER message in which the address A, which is its own address, is described in the Contact header (step 100). The packet is received by the access network communication unit 11 of the SBC device 10.

  In the SBC device 10 that has received the packet, the external address determination unit 13 determines an address G that is an external address corresponding to the user terminal 6 and passes it to the SIP message processing unit 14 together with the REGISTER message (step 101). The external address can be determined, for example, by selecting one from a plurality of pooled addresses based on a predetermined rule. This is an example, and in the present embodiment, the external address determination method is not limited to a specific method.

  Subsequently, the SIP message processing unit 14 adds a Path header describing the address G to the REGISTER message and passes it to the core-to-core network communication unit 12 (step 102). The Path header is a header defined in RFC3327. The address described in the Contact header is not changed and remains as address A.

  Then, the core-to-core network communication unit 12 generates a packet (destination: address S, transmission source: address G) including the REGISTER message with the Path header added, and sends the packet to the core network 2 (step 103). .

  The packet is received by the SIP server 7. In the SIP server 7, the address A described in the Contact header in the REGISTER message and the address G described in the Path header are associated with each other and stored in a storage means such as a memory, and the binding target included in the REGISTER message The SIP processing is performed in which the name and the address A described in the Contact header are associated with each other and stored in the storage means as binding information (step 104). However, the binding information may be stored in a server such as a location server outside the SIP server 7.

  Then, the SIP server 7 transmits a packet including a 200 OK message as a response message to the SBC device 10 (step 105). As shown in FIG. 6, the 200 OK message includes the same Contact header and Path header as the received REGISTER message.

  The SBC device 10 that has received the packet including the 200 OK message transfers the 200 OK message to the address A (user terminal 6) described in the Contact header in the received 200 OK message.

  More specifically, the SIP message processing unit 14 extracts the address A described in the Contact header in the 200 OK message included in the received packet, and passes it to the access network communication unit 11 together with the 200 OK message. The access network communication unit 11 uses the address A passed from the SIP message processing unit 11 as a destination address and a packet including a 200 OK message using the address P of the SBC device 10 on the access network 3 side as a transmission source address. Generate and send (step 106, step 107). The SIP message processing unit 14 may delete the Path header from the 200 OK message, and the access network communication unit 11 may transmit the 200 OK message from which the Path header is deleted.

  Thereafter, it is assumed that a call connection request (INVITE message) specifying the name of the user terminal 6 is transmitted from another user terminal existing on the core network 2 side (step 110). At this time, the SIP server 7 receives the INVITE message, acquires the address A corresponding to the name described as the request URI (R-URI) of the INVITE message from the binding information, and also stores the Contact header stored in step 104. The address G corresponding to the address A is extracted from the correspondence information between the address and the address in the Path header. Then, an Invite message in which the address A is described as an R-URI and the address G is described in the Route header is created, and a packet including the Invite message is transmitted to the address G described in the Route header (step 111).

  The SBC device 10 that has received the packet including the Invite message by the core-to-core network communication unit 12 transmits the Invite message to the R-URI (address A). More specifically, the SIP message processing unit 14 deletes the Route header from the Invite message, acquires an R-URI (address A) from the Invite message, and sends the Invite message and the address A to the access network communication unit 11. Pass (step 112). Then, the access network communication unit 11 generates a packet including an Invite message with the address A as the destination and the address P as the transmission source, and sends the packet to the access network 3 (step 113).

  Through the above processing, media communication between user terminals is realized. Note that the SBC device 10 can perform packet address conversion on the response message to the Invite message transmitted from the user terminal 6 by various methods. For example, when the SBC 10 apparatus receives the INVITE message, the address A and the address G are stored in association with each other, and by referring to the stored information, the address A and the address G for the response message packet are stored. Conversion processing can be performed. Since such retained information is retained only when a communication session between user terminals is established, problems such as memory pressure do not occur. Also, in the case of media communication, correspondence information between the core network 2 side address and the access network 3 side address is necessary, but this information is also necessary only when performing media communication. There is no problem.

(Effect of embodiment)
As described above, by using the technique described in this embodiment, it is necessary to always hold address correspondence information in which the address of the user terminal and the external address of the SBC device 10 are associated with each other in preparation for incoming calls. Disappears. Therefore, unlike the prior art, there is no risk of squeezing hardware resources by storing address correspondence information, and there is no enormous processing load associated with information retrieval when an incoming call is received.

  Furthermore, since address correspondence information is not held for incoming calls, there is no problem caused by volatilization of address correspondence information as in the prior art. Further, since the address correspondence information is not held in the SBC device 10, maintainability, efficiency, and availability are improved.

  The present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the claims. For example, in the present embodiment, in the REGISTER message, the external address corresponding to the user terminal 6 is described in the Path header, but it is not essential to use the Path header. In the REGISTER message, a header other than the Path header may be used as long as the header information can indicate the external address corresponding to the user terminal 6. When a header other than the Path header is used, the SIP server 7 is configured to operate in the same manner as when the Path header is used.

1, 10 SBC equipment 2 Core network 3 Access network 4 PSTN
5 PSTN-GW
6 User terminal 7 SIP server 11 Access network communication unit 12 Core network communication unit 13 External address determination unit 14 SIP message processing unit 15 Media communication unit

Claims (7)

In a communication service network having an access network to which a user terminal is connected and a core network to which a SIP server is connected, an address conversion device installed and used at a boundary portion between the access network and the core network,
Receiving means for receiving a registration message including the address of the user terminal as information of the Contact header from the user terminal;
An external address adding means for determining an external address which is an address on the core network side in the address translation device for the user terminal, and adding the external address to the registration message as information of a predetermined header;
Transmission means for including the registration message with the external address added as information of the predetermined header in a packet in which the external address is designated as a transmission source address and transmitting the packet to the SIP server. Address translation device.   A response message to the registration message is received from the SIP server, the address of the user terminal described in the Contact header included in the response message is acquired, and the address of the user terminal is set as the destination address of the response message. The address translation apparatus according to claim 1, wherein the address translation apparatus transmits the packet in a designated packet.   A connection request message whose destination is the address of the user terminal is received from the SIP server, and the connection request message is included in a packet in which the address of the user terminal is designated as a destination address and transmitted to the user terminal The address translation apparatus according to claim 1 or 2, wherein   4. The address translation apparatus according to claim 1, wherein the predetermined header is a Path header. In a communication service network having an access network to which a user terminal is connected and a core network to which a SIP server is connected, an address translation device installed at a boundary portion between the access network and the core network, and the SIP server A communication system comprising:
The address translation device receives a registration message including the address of the user terminal as Contact header information from the user terminal, and sends an external address that is an address on the core network side in the address translation device to the user terminal. Determine, add the external address as information of a predetermined header to the registration message,
The address translation device transmits the registration message, in which the external address is added as information of the predetermined header, to the SIP server by including the packet in which the external address is specified as a source address,
The SIP server receives the registration message, associates the address of the user terminal as information of the Contact header of the registration message and the external address as information of the predetermined header, and stores them in a storage unit. ,
When the SIP server receives a connection request message for requesting connection of the user terminal, the SIP server acquires the external address corresponding to the address of the user terminal from the storage unit, and the user A communication system comprising: a connection request message including a terminal address as a transmission destination included in a packet in which the external address is specified as a destination address, and transmitting the packet to the address translation device. In a communication service network having an access network to which a user terminal is connected and a core network to which a SIP server is connected, an address translation device installed at a boundary portion between the access network and the core network, and the SIP server A message communication method executed by a communication system comprising:
The address translation device receives a registration message including the address of the user terminal as Contact header information from the user terminal, and sends an external address that is an address on the core network side in the address translation device to the user terminal. Determine, add the external address as information of a predetermined header to the registration message,
The address translation device transmits the registration message, in which the external address is added as information of the predetermined header, to the SIP server by including the packet in which the external address is specified as a source address,
The SIP server receives the registration message, associates the address of the user terminal as information of the Contact header of the registration message and the external address as information of the predetermined header, and stores them in a storage unit. ,
When the SIP server receives a connection request message for requesting connection of the user terminal, the SIP server acquires the external address corresponding to the address of the user terminal from the storage unit, and the user A message communication method comprising: transmitting a connection request message including a terminal address as a transmission destination to the address translation device by including the connection request message in a packet in which the external address is specified as a destination address. Functions as an address translation device installed in a boundary part between the access network and the core network in a communication service network having a computer and an access network to which a user terminal is connected and a core network to which a SIP server is connected A program for making a computer
Receiving means for receiving a registration message including the address of the user terminal as information of the Contact header from the user terminal;
An external address adding means for determining an external address which is an address on the core network side in the address translation device for the user terminal, and adding the external address to the registration message as information of a predetermined header;
Transmission means for transmitting the registration message, in which the external address is added as information of the predetermined header, to the SIP server by including the packet in which the external address is specified as a transmission source address;
Program to function as.

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