JP2006005754A - Sip signal conversion method, sip-alg device, sip signal conversion program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a SIP signal conversion method in which each SIP-ALG independently determine whether the SIP transmission between terminals is the one in an identical private network or not when a SIP signal is relayed by a plurality of SIP-ALGs in the SIP transmission between terminals. <P>SOLUTION: As for a SIP signal transmitted from a private network to a global network, a network identification information of a NAT device and an IP address and a port number before and after conversion of an SDP are set up as an original SIP header, when the IP address and the port number of the SIP signal are converted at a SIP-ALG. In addition, as for a SIP signal transmitted from the global network to the private network, the original SIP header is compared with the network identification information of the NAT device and the SDP to determine whether they are terminals of an identical private network. Moreover, the IP address and the port number of the SDP are converted into the IP address and the port number before conversion included at the original SIP header, in the case of the SIP communication between terminals in the identical private network. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a SIP signal conversion method, a SIP-ALG device, a SIP signal conversion program, and a recording medium, and in particular, a NAT device that connects a private network and a global network is connected to one of a plurality of SIP-ALGs. In addition, when performing SIP communication between terminals of the same private network, the present invention relates to a technique that is effective when applied to the case of converting the IP address and port number of a SIP signal when passing through two different SIP-ALGs. It is.

  Conventionally, when a terminal of a certain private network performs transmission / reception of media signals such as voice and video with a terminal of the same private network, or a terminal of the global network or another private network, first, for example, SIP communication between the terminals To establish a session. At this time, the SIP signal transmitted / received between the terminals passes through a SIP server accommodated in the global network, for example. Since networks having different address systems such as the private network and the global network, or the IPv4 network and the IPv6 network are connected using a NAT device, the SIP signal transmitted from the terminal of the private network to the SIP server and A SIP signal transmitted from the SIP server to the terminal of the private network always passes through the NAT device. At this time, the NAT device causes SIP-ALG to convert the IP address and port number of the SIP signal.

  The SIP-ALG, in cooperation with the NAT device, for example, converts the IP address of the SIP header such as Via or Contact header and the SIP signal reception port number in the SIP layer, and in the session description by SDP of the SIP body. Converts IP address and media reception port number. Thus, by converting the IP address and port number for media reception in the SIP-ALG, it is possible to transmit and receive the media signal between terminals that have transmitted and received the SIP signal (for example, , See Non-Patent Document 1.)

  In addition, when a terminal in a private network (first terminal) performs SIP communication with another terminal via a SIP server installed in the global network, the other terminal that performs the SIP communication is a terminal in the same private network. Even in the case of (second terminal), a SIP signal is transmitted from the first terminal to the SIP server of the global network, and thereafter, the SIP signal is transmitted from the SIP server of the global network to the second terminal. Therefore, the SIP signal transmitted from one terminal to the other terminal is transmitted from the private network to the global network (SIP server) and from the global network (SIP server) to the private network. It will go through SIP-ALG twice. In this way, using the feature that goes through the SIP-ALG twice, the network identification information of the source private network and the SDP information on the private network side are acquired and stored on the SIP-ALG during the first time through the SIP-ALG. In addition, the network identification information of the destination private network is acquired during the second SIP-ALG, and the source private network and the destination private network are the same compared with the network identification information collected and held the first time. In recent years, a technique for determining whether or not the SIP communication is communication between terminals of the same private network has been proposed. In this method, in SIP-ALG through which a SIP signal transmitted from the global network (SIP server) to a private network terminal passes, the terminal that first transmitted the SIP signal is the same private network terminal or the global network. Alternatively, if it is a terminal of the other private network, and if it is a terminal of the same private network, for example, the IP address and media reception port number of the session description by the SDP are converted, that is, each terminal is accommodated. It is re-converted to an IP address and media reception port number that conforms to the private network address system. As a result, each terminal obtains an IP address and a media reception port number for transmitting and receiving a media signal as an IP address and a media reception port number according to the address system of the private network. Communication paths can be set in the network, and media signals can be transmitted and received without going through the NAT device (global network).

However, if the private network is a large-scale private network such as a VPN (Virtual Private Network) having a plurality of bases, a plurality of SIP-ALG devices may be provided for the purpose of load distribution. Can be considered. In that case, even in SIP communication between terminals of the same private network, SIP-ALG through which a SIP signal transmitted from one terminal to the SIP server passes, and SIP transmitted from the SIP server to the other terminal The SIP-ALG through which the signal passes may be different. At this time, in SIP-ALG through which the SIP signal transmitted from the global network (SIP server) to the terminal of the private network passes, the SIP signal is transmitted first by comparing the identification information of the private network as described above. When trying to determine whether a terminal is a terminal of the same private network or a terminal of a global network or another private network, the SIP-ALG through which the SIP signal transmitted from the SIP server to the other terminal passes is It is necessary to take measures such as referring to network identification information and SDP information collected and held by other SIP-ALGs. For this reason, the network identification information and SDP information are communicated between a plurality of SIP-ALGs, resulting in a problem that processing delay increases.
Kazuhito Hayashi, Takaho Shibata, Yuichi Suwa, Hiroaki Kosuge, Junichiro Kuroki, “A Study on the Management Method of Address Translation Entries in SIP Application Level Gateway (SIP-ALG)”, IEICE Technical Report NS2002-188, PS2002-62 ( 2002-12), p25-28

  As described in the background art, the problem to be solved by the present invention is that the SIP communication is performed in the SIP-ALG when the SIP signal passes through a plurality of SIP-ALGs in the SIP communication between terminals. Processing delay increases when determining whether the communication is between terminals on the same private network, communication between a private network terminal and a global network terminal, or communication between terminals on different private networks. Is a point.

  An object of the present invention is that a NAT device that connects a private network and a global network is connected to one of a plurality of SIP-ALGs, and two different SIP-s in SIP communication between terminals of the same private network. It is an object of the present invention to provide a technology capable of determining whether or not the SIP-ALG is SIP communication between terminals in the same private network when going through the ALG.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  The outline of the invention disclosed in the present application will be described as follows.

  (1) A network in which one or more private networks accommodating two or more terminals and two or more NAT (Network Address Translation) devices are connected to the global network by the NAT devices and accommodated in the private network. SIP (Session Initiation Protocol) compatible terminals are connected to SIP private terminals in the same private network or SIP compatible terminals accommodated in the global network or other private networks via a SIP server accommodated in the global network. SIP-ALG (SIP-Application Level Gateway) SIP signal conversion method for converting an IP address and a port number of a SIP signal in cooperation with the NAT device when performing SIP communication with the NAT device, Step 1 for managing the correspondence of the private network in which the NAT device is accommodated, and a SIP signal transferred from the NAT device is transmitted from the private network to the global network. 2 and converting the IP address and media receiving port number of the session description by SDP of the SIP signal in cooperation with the NAT device, and the SIP signal Step 3 of setting the identification information of the private network in which the transferred NAT device is accommodated, the IP address of the session description by the SDP before conversion in Step 2 and the port number for receiving media as the unique SIP header in the SIP signal Step 4 for converting the IP address and port number of the SIP header of the SIP signal in cooperation with the NAT device, and the SIP signal transferred from the NAT device is a signal transmitted from the global network to the private network. And if there is a session description by the SDP, a step 5 for determining whether or not the unique SIP header is set If it is determined in step 5 that a unique SIP header is set, the private network in which the NAT device that transferred the SIP signal is accommodated is specified, and the private network described in the unique SIP header is specified. Step 6 for determining whether or not the ID information matches, and if it is determined to match in Step 6, describe the IP address and media reception port number of the session description by SDP of the SIP signal in the unique SIP header. And a step 7 for converting into a received IP address and a media receiving port number.

  (2) In the SIP signal conversion method of (1), the step 3 includes the identification information of the private network in which the NAT device is accommodated, the IP address of the session description by the SDP before the conversion in the step 3, and In addition to the media reception port number, the IP address and the media reception port number of the session description by the SDP converted in the step 3 are set as unique SIP headers, and the step 7 is determined to match in the step 6 Only when the converted IP address and media reception port number described in the unique SIP header of the SIP signal match the IP address and media reception port number of the session description by SDP of the SIP signal. The IP address and media reception port number of the session description by the SDP are converted.

  The SIP signal conversion method according to the present invention is the SIP-ALG in the SIP-ALG that is used when the SIP signal is transmitted from the terminal of the private network to the SIP server of the global network, as in the means (1). The NAT device with which the terminal is linked, in other words, the identification information of the private network in which the terminal is accommodated, the IP address of the session description by SDP before being converted in the SIP-ALG, and the port number for media reception as the unique SIP header Set to SIP signal. For this reason, the SIP-ALG that is used when sending a SIP signal from the SIP server of the global network to the terminal of the private network refers to the original SIP header, and does not inquire other SIP-ALGs. It is possible to determine whether or not the SIP communication is between terminals of the network. Then, when it is determined that the SIP communication is between the terminals of the same private network, referring to the unique SIP header, the IP address and media reception port number of the session description by the SDP are the original values, that is, the It can be converted into an IP address and a media reception port number in accordance with the private network address system. As a result, after establishing a session by SIP communication between terminals in the same private network, when transmitting and receiving media signals such as voice and video, a route is set in the private network, and the NAT device (global network) is The media signal can be transmitted and received without intervention.

  However, in the case of the means (1), for example, when the unique SIP header is taken over by the SIP signal reply SIP signal transmitted from the private network terminal to the global network terminal, the reply SIP signal is received. The SIP-ALG determines that the terminal that transmitted the reply SIP signal is a terminal of the same private network. Therefore, as in the means of (2) above, in addition to the identification information of the private network, the IP address of the session description by SDP before conversion and the port number for media reception in the unique SIP header, the session by SDP after conversion It is also preferable to set the IP address and media reception port number of the description. The IP address and media reception port number of the session description by the converted SDP set in the unique SIP header are the IP address and media reception port number assigned to the terminal that transmitted the SIP signal. Therefore, the value is different from the IP address and media reception port number of the session description by SDP of the reply SIP signal from the terminal of the global network. Therefore, as shown in the means of (2) above, the identification information of the private network matches, and the IP address and media reception port number of the session description by SDP after the conversion of the unique SIP header, and reception By determining that the SIP communication between the terminals of the same private network is SIP communication only when the IP address of the session description by the SDP of the SIP signal and the port number for media reception match, the terminal from the terminal of the global network Even in the SIP-ALG that has received the reply SIP signal, it is possible to determine whether or not it is SIP communication between terminals in the same private network.

  The SIP-ALG device that implements the SIP signal conversion method as described in (1) above, for example, shows the correspondence between the IP address on the private network side managed by each NAT device and the IP address on the global network side. Network address management means for collectively managing each NAT device, NAT-compatible network identification information management means for managing the correspondence between each NAT device and the private network in which the NAT device is accommodated, and transferred from the NAT device When the SIP signal is a signal transmitted from the private network to the global network and there is a session description by the SDP, the NAT device is accommodated based on the correspondence managed by the NAT-compatible network identification information management means. A means for identifying a private network and an SDP field that converts the IP address and media reception port number of the session description by SDP of the SIP signal in cooperation with the NAT device. The IP address and the media reception port number of the session description by the SDP before conversion by the field conversion means, the identified private network identification information, and the SDP field conversion means are set as the unique SIP header in the SIP signal. Unique SIP header setting means, SIP header conversion means for converting the IP address and port number of the SIP header of the SIP signal in cooperation with the NAT apparatus, and the SIP signal transferred from the NAT apparatus is transferred from the global network to the private network And a description of the session in the SDP, the unique SIP header is set, and the identification information of the private network in which the NAT device is accommodated is the unique SIP header. The SDP of the SIP signal is sent to the SDP field conversion means when it matches the identification information of the private network described in Conversion determination means for converting the IP address and media reception port number in the session description into the IP address and media reception port number described in the unique SIP header.

  At this time, the unique SIP header setting means converts the private network identification information in step 3 in addition to the private network identification information and the IP address and media reception port number of the session description in SDP before the conversion in step 3. The IP address and media reception port number of the session description in the later SDP are set as a unique SIP header, and the conversion determination means satisfies each determination condition, and the conversion described in the unique SIP header of the SIP signal. Only when the later IP address and the media receiving port number match the IP address and the media receiving port number of the session description by the SDP of the SIP signal, the SDP field conversion means is provided with the IP address of the session description by the SDP and If the media reception port number is converted, the means (2) The SIP signal conversion method as described above can be realized.

  In addition, the SIP signal conversion method such as the means (1) or (2) described above, for example, instead of the SIP-ALG device including each means as described above, the computer and the computer (1) or It can also be realized by using a program that performs the processing of each step of the means (2). At this time, the program can be provided by being recorded on a magnetic, electrical, or optical recording medium, or can be provided through a network such as the Internet.

Hereinafter, the present invention will be described in detail together with embodiments (examples) with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same function are given the same reference numerals and their repeated explanation is omitted.

  The SIP signal conversion method of the present invention is a SIP that converts the SIP layer IP address and port number of a SIP signal in cooperation with a NAT device that connects two networks having different address systems such as a private network and a global network. -This is a SIP signal conversion method in ALG. At this time, for the SIP signal transmitted from the private network to the global network, the SIP-ALG uses the identification information of the private network in which the terminal (NAT device) that transmitted the SIP signal is accommodated, the session by SDP. Set the original SIP header that correlates the IP address and port number before conversion of the description (hereinafter simply referred to as SDP) and the IP address and port number after conversion. For SIP signals transmitted from the global network to the private network, refer to the unique SIP header to identify the private network in which the terminal (NAT device) that transmitted the SIP signal first is accommodated. When it is determined that the terminal that first transmitted the SIP signal and the terminal that finally receives the SIP signal are accommodated in the same private network, the IP address and port number of the SDP and the value before conversion are restored. By doing so, when transmitting a SIP signal from the source terminal to the SIP server to the SIP server and the SIP-ALG connected to the NAT device via which the SIP signal is transmitted from the SIP server to the destination terminal Even when the SIP-ALG connected to the NAT device passing through is different, the processing delay in SIP communication can be reduced.

1 to 6 are schematic diagrams for explaining a SIP signal conversion method according to an embodiment of the present invention. FIG. 1 is a diagram showing a configuration example of a network to which the SIP signal conversion method according to the embodiment is applied. 2 is a diagram showing a configuration example of the SIP-ALG of FIG. 1, FIG. 3 is a diagram showing an example of a network address management table, FIG. 4 is a diagram showing an example of a NAT-compatible network identification information management table, and FIG. FIG. 6 is a flowchart for explaining an example of a specific processing procedure of step 508 in FIG. 5.
In FIG. 1, 1 is a first private network, 101 is a first NAT device, 102 is a second NAT device, 103 is a first terminal, 104 is a second terminal, 2 is a second private network, 201 is a third NAT device, and 202 is The fourth terminal, 3 is a global network, 301 is a third terminal, 302 is a SIP server, 401 is a first SIP-ALG device, 402 is a second SIP-ALG device, and 403 is a third SIP-ALG device. In FIG. 2, 40101 is a SIP signal transmission / reception unit, 40102 is a transmission direction determination unit, 40103 is an SDP conversion unit, 40103a is an SDP field conversion unit, 40103b is a unique SIP header setting unit, 40103c is an SDP conversion determination unit, and 40104 is SIP header conversion means, 40105 is network address management means, and 40106 is NAT-compatible network identification information management means.

  The SIP signal conversion method of this embodiment is applied to a network composed of three networks, such as a first private network 1 and a second private network 2 such as a VPN, and a global network 3, as shown in FIG. The At this time, it is assumed that the first private network 1 and the global network 3 are connected by the first NAT device 101 and the second NAT device 102 as shown in FIG. Further, it is assumed that the second private network 2 and the global network 3 are connected by a third NAT device 201 as shown in FIG. At this time, the first NAT device 101, the second NAT device 102, and the third NAT device 201 are connected to the first SIP-ALG device 401, the second SIP-ALG device 402, and the third SIP-ALG device 403, respectively.

  The first terminal 103 and the second terminal 104 accommodated in the first private network 1, the third terminal 301 accommodated in the global network 3, and the fourth terminal 202 accommodated in the second private network 2 are In addition, each of the terminals is compatible with SIP, and by performing SIP communication between the terminals via the SIP server 302 accommodated in the global network 3, it is possible to transmit and receive media such as audio and video. Suppose you can. At this time, the first terminal 103 is assigned an IP address according to the address system of the first private network 1. In this embodiment, the address system of the first private network 1 is 192.168.0.0/24, and the IP address assigned to the first terminal 103 is 192.168.0.1. Further, it is assumed that the port number for SIP signal reception of the first terminal 103 is 5060 and the port number for media reception is 10001. Similarly, the second terminal 104 is assigned an IP address 192.168.0.2 in accordance with the address system of the first private network 1, the SIP signal reception port number is 5060, and the media reception port. It is assumed that the number is 10002.

  The third terminal 301 is assigned an IP address according to the address system of the global network 3. In this embodiment, the IP address assigned to the third terminal 301 is 128.0.0.3. The port number for SIP signal reception of the third terminal 301 is 5060 and the port number for media reception is 10003.

  The fourth terminal 202 is assigned an IP address in accordance with the address system of the second private network 2. In this embodiment, the address system of the second private network 2 is 192.168.1.0/24, and the IP address assigned to the fourth terminal 202 is 192.168.1.4. Further, it is assumed that the port number for SIP signal reception of the fourth terminal 202 is 5060 and the port number for media reception is 10004.

  The first SIP-ALG device 401 is a device that cooperates with the first NAT device 101 to convert the SIP layer address information of the SIP signal (message) received by the first NAT device 101. In this embodiment, the first SIP-ALG device 401 receives the SIP signal transferred from the first NAT device 101 and converts the address information into the first NAT device as shown in FIG. SIP signal transmission / reception means 40101 for returning to 101, transmission direction determination means 40102 for determining the transmission direction of the SIP signal transferred from the first NAT device 101, SDP conversion means 40103 for converting the SDP of the SIP signal, The SIP header conversion means 40104 for rewriting a SIP layer (SIP header) other than the SDP of the SIP signal, and the correspondence between the address system on the private network side in which each NAT device is accommodated and the side address system on the global network Network address management means 40105 for collectively managing each NAT device, and network identification for identifying the network in which each NAT device is accommodated And NAT-compatible network identification information management means 40106 for managing information.

  Also, the SDP conversion means 40103 includes, for example, an SDP field conversion means 40103a for converting the IP address of the c field and the media reception port number of the m field in the SDP of the SIP signal, as shown in FIG. A unique SIP header setting means 40103b for setting a unique SIP header in a SIP signal transmitted from the private network to the global network, and a determination as to whether or not to perform SDP conversion of the SIP signal transmitted from the global network to the private network SDP conversion determination means 40103c to perform.

  Further, as shown in FIG. 3, for example, the network address management means 40105 has a global network side address system which is a private network side address system accommodated for each NAT device and an address system after conversion of private addresses. Holds a network address management table. In the present embodiment, as shown in FIG. 3, it is assumed that the first NAT device 101 manages 192.168.0.0/24 as the private network side address system and 130.0.0.0/24 as the global network side address system. Similarly, the second NAT device 101 manages 192.168.0.0/24 as the private network side address system and 131.0.0.0/24 as the global network side address system, and the third NAT apparatus 201 uses 192.168. As the private network side address system. Assume that 1.0 / 24 is managed as the global network side address system, 132.0.0.0/24.

  On the other hand, as shown in FIG. 4, for example, the NAT-compatible network identification information management means 40106 determines in which private network each NAT device through which SIP communication is performed is accommodated (belongs). It holds a NAT-compatible network identification information management table that summarizes network identification information to be expressed. In the present embodiment, as shown in FIG. 1, the first NAT device 101 and the second NAT device 102 are accommodated in the first private network 1, and the third NAT device 201 is accommodated in the second private network 2. . Therefore, if the network identification information representing the first private network 1 is PN1, and the network identification information representing the second private network 2 is PN2, the NAT-compatible network identification information management table is a table as shown in FIG. .

  Although illustration and detailed description are omitted, the second SIP-ALG device 402 and the third SIP-ALG device 403 have the same configuration as the first SIP-ALG device 401.

  In the network as shown in FIG. 1, the SIP signal transmitted from the first terminal 103 or the second terminal 104 or the fourth terminal 202 to the SIP server 302, or the first terminal 103 or the second terminal from the SIP server 302. The SIP signal transmitted to the second terminal 104 or the fourth terminal 202 passes through one of the first NAT device 101, the second NAT device 102, and the third NAT device 201. At this time, when each of the NAT devices receives the SIP signal, the NAT device transfers the received SIP signal to the SIP-ALG device, and the SIP-ALG device transmits the IP address of the SDP, a port number for receiving media, The IP address of the SIP header, the port number for receiving the SIP signal, and the like are converted. Hereinafter, an example of a conversion procedure such as an IP address and a port number in the first SIP-ALG device 401 shown in FIG. 2 will be briefly described with reference to FIGS.

  When the first SIP-ALG device 401 receives the SIP signal transferred from the first NAT device 101 by the SIP signal transmission / reception means 40101, first, as shown in FIG. It is confirmed that SDP is set for the signal (step 501). Step 501 is performed by the transmission direction determination means 40102. When the processing in step 501 is completed, the transmission direction determination unit 40102 passes the SIP signal and the confirmed transmission direction to the SDP conversion unit 40103.

  When the SDP conversion unit 40103 receives the SIP signal and transmission direction information from the transmission direction determination unit 40102, the SDP conversion unit 40103 determines whether or not the transmission direction is a private network to a global network (step 502). At this time, if it is determined that the transmission direction of the SIP signal is from the private network to the global network, the SDP conversion unit 40103 converts the c field and m field of the SDP of the SIP signal to the SDP field conversion unit 40103a. Let

  At this time, the SDP field conversion unit 40103a first recognizes that the NAT device that has transferred the received SIP signal is the first NAT device 101. Then, the network identification information of the first NAT device 101 is obtained by referring to the NAT-compatible network identification management table (step 503). After the step 503, the SDP field conversion means 40103a obtains the IP address of the c field of the SDP and the media reception port number of the m field of the received SIP signal. Then, referring to the network address management table, it is confirmed that the acquired IP address in the c field is an address managed by the first NAT device 101 that acquired the network identification information in the step 503. When the IP address is confirmed, the SDP field conversion unit 40103a requests the first NAT device 101 to issue an IP address and a media reception port number in accordance with the address system of the global network 3. Then, the IP address in the c field and the media reception port number in the m field are converted into the IP address and media reception port number issued from the first NAT device (step 504).

  After the conversion of the IP address of the c field and the media transmission / reception port number of the m field in the step 504, the SDP conversion unit 40103 then sets the unique SIP header in the unique SIP header setting unit 40103b. (Step 505). At this time, the unique SIP header setting means 40103b adds, for example, the network identification information of the first NAT device 101 acquired in step 503, the IP address of the c field before the conversion of the SDP, and the SIP header of the SIP signal. A unique SIP header having five pieces of information including the media transmission / reception port number in the m field, the IP address of the c field after conversion, and the media transmission / reception port number in the m field is set. At this time, the unique SIP header is conventionally added to the SIP header of the SIP signal with a header name different from the header name included in the SIP signal.

  After completing the setting of the unique SIP header in the step 505, the SDP converting means 40103 converts the IP address of the c field and the m field media reception port number, and converts the SIP signal in which the unique SIP header is set to the SIP signal. It is passed to the SIP header conversion means 40104. The SIP header conversion means 40104 converts the IP address of the SIP layer (SIP header) other than the SDP of the SIP signal and the unique SIP header and the port number for receiving the SIP signal (step 506). At this time, the SIP header conversion means 40104 refers to, for example, the network address management table, and the first NAT device 101 having acquired the network identification information in the step 503 has received the SIP signal reception IP address of the SIP header. After confirming that the address is managed, the first NAT apparatus 101 is requested to issue a SIP signal reception port number in accordance with the address system of the global network 3. Then, the IP address of the SIP header is converted to the IP address of the c field converted in the step 504, and the SIP signal reception port number is converted to the media reception port number issued from the first NAT device 101. To do.

  The SIP header conversion means 40104 passes the SIP signal to the SIP signal transmission / reception means 40101 after the conversion of the IP address of the SIP header and the SIP signal reception port number in the step 506. When the SIP signal transmission / reception means 40101 receives the SIP signal from the SIP header conversion means 40104, it returns the SIP signal to the first NAT device 101 (step 507). Then, the first NAT device 101 transmits the SIP signal returned from the first SIP-ALG device 401 to the SIP server 302 of the global network 3 that is the original transmission destination.

  If the SDP conversion means 40103 determines in step 502 that the transmission direction of the SIP signal is not from the private network to the global network, that is, the transmission direction is from the global network to the private network, it is shown in FIG. As described above, the process of step 508 is performed.

  When performing the processing of step 508, the SDP conversion means 40103 first causes the SDP conversion determination means 40103c to determine whether or not the SDP conversion of the received SIP signal is necessary. At this time, as shown in FIG. 6, the SDP conversion determination means 40103c first determines whether or not the unique SIP header is set in the received SIP signal (step 508a). At this time, if it is determined that the unique SIP header is set, the SDP conversion determination unit 40103c recognizes that the NAT device that has transferred the SIP signal is the first NAT device 101. Then, the network identification information of the first NAT device 101 is acquired with reference to the NAT-compatible network identification information management table (step 508b). After the step 508b, the SDP conversion determination unit 40103c converts the IP address of the c field and the media reception port number of the m field included in the original SIP header of the SIP signal, and the SDP of the received SIP signal. The IP address in the c field and the media reception port number in the m field are compared to determine whether or not they match (step 508c and step 508d). At this time, if it is determined that they match, the SDP conversion determination means 40103c continues to check the network identification information included in the unique SIP header of the received SIP signal, and the network identification information included in the unique SIP header and the network identification information It is determined whether or not the network identification information acquired in step 508b matches (steps 508e and 508f). At this time, if it is determined that they match, the terminal that first transmitted the SIP signal and the terminal that finally receives the SIP signal are accommodated in the same private network. Therefore, the SDP conversion determination unit 40103c causes the SDP field conversion unit 40103a to convert the SDP of the SIP signal.

  At this time, the SDP field conversion means 40103a refers to the unique SIP header of the received SIP signal, converts the IP address of the c field of the SDP of the SIP signal and the media reception port number of the m field to the unique SIP header. The IP address and port number before conversion in the header are rewritten (step 508g). Thereafter, for example, the original SIP header is deleted, and the SIP signal in which the c field and m field of the SDP are rewritten is passed to the SIP header converting means 40104 to perform the processing of step 506, and the first NAT is performed in step 507. A SIP signal is returned to the apparatus 101. In this way, when the SIP signal in which the IP address in the c field and the media reception port number in the m field are returned to the values before conversion is returned to the first NAT device 101, the first NAT device 101 transmits the SIP signal. It is forwarded to the terminal that finally receives it. As a result, the terminal that has received the SIP signal knows that the SIP signal is a signal transmitted from a terminal accommodated in the same private network. At this time, the IP address in the c field of the SDP is an address in the address system of the private network, and the media reception port number in the m field is a port number set by the terminal that transmitted the SIP signal. Therefore, when media such as voice and video are transmitted / received after establishing a SIP session between the terminals, a route can be set in the private network without going through the global network.

  If it is determined in step 508f that the network identification information included in the unique SIP header and the network identification information acquired in step 508b do not match, the terminal that first transmitted the SIP signal and the SIP signal are finalized. Thus, the terminal that receives the message is accommodated in a different private network. Therefore, the SDP conversion determination unit 40103c does not cause the SDP field conversion unit 40103a to convert the IP address of the c field and the media reception port number of the m field, and the received SIP signal is directly used as the SIP header conversion unit 40104. And the processing of step 506 and step 507 is performed. Also, in the SIP signal conversion method of this embodiment, the unique SIP header is always set when a SIP signal is transmitted from the private network to the global network via the NAT device and SIP-ALG device. Therefore, if it is determined in step 508a that the unique SIP header is not set, the terminal that first transmitted the SIP signal is accommodated in the same network as the network in which the SIP server is accommodated, that is, in the global network. Will be. Also in this case, the SDP conversion determination unit 40103 does not cause the SDP field conversion unit 40103a to convert the IP address of the c field and the media reception port number of the m field, and the received SIP signal is directly used as the SIP header conversion unit. 40104 to cause the processing of step 506 and step 507 to be performed.

  Further, when the SIP signal transmitted from the terminal of the global network 3 is a reply SIP signal of the SIP signal transmitted from the terminal of the private network, the SIP signal transmitted from the terminal of the private network to the reply SIP signal. The set unique SIP header may be carried over. However, in that case, the IP address and media reception port number of the SDP of the reply SIP signal are values for the terminals of the global network, and the converted IP address and media reception port number in the unique SIP header are This value is for a private network terminal. For this reason, it is determined in step 508c and step 508d that they do not match. Therefore, the IP address of the c field and the media reception port number of the m field are not converted by the SDP field conversion unit 40103a, and the received SIP signal is directly passed to the SIP header conversion unit 40104, and the steps 506 and The process of step 507 is performed.

  As described above, in the SIP signal conversion method of the present embodiment, when a SIP signal is transmitted from a private network terminal (transmission terminal) to a global network SIP server via a NAT device and a SIP-ALG device, Five pieces of information: network identification information of NAT device (transmission terminal), IP address of c field before conversion of SDP of the SIP signal and port number of m field, IP address of c field after conversion and port number of m field A unique SIP header with is set. Therefore, when a SIP signal is transmitted from the SIP server to a private network terminal (receiving terminal) via a NAT device and a SIP-ALG device, the SIP-ALG device independently transmits the SIP signal first. It is possible to identify whether the transmitting terminal (transmitting terminal) is accommodated in the same private network as the receiving terminal, or is accommodated in a private network or a global network different from the receiving terminal. Therefore, in a network provided with a plurality of SIP-ALG devices as shown in FIG. 1, there is no need to inquire communication routes to other SIP-ALG devices as in the prior art, and processing delay in SIP communication is reduced. Can do.

  Hereinafter, in the network shown in FIG. 1, when performing SIP communication between terminals of the same private network, when performing SIP communication between terminals of different private networks, SIP communication between the terminals of the private network and the terminals of the global network. A specific communication procedure including a SIP signal conversion example and the like will be described.

  7 to 17 are schematic diagrams for specifically explaining the SIP signal conversion method according to the present embodiment. FIG. 7 is a diagram showing a route of SIP communication between terminals in the same private network. FIG. FIG. 9 is a sequence diagram when a SIP signal (INVITE request) is transmitted from the first terminal to the second terminal, FIG. 9 is a diagram illustrating an example of the SIP signal transmitted from the first terminal, and FIG. 10 is converted by the first SIP-ALG device. FIG. 11 is a diagram showing an example of a SIP signal edited by a SIP server, and FIG. 12 is a diagram showing an example of a SIP signal converted by the second SIP-ALG device. FIG. 13 is a sequence diagram when a SIP signal (200 OK response) is transmitted from the second terminal to the first terminal, FIG. 14 is a diagram illustrating an example of the SIP signal transmitted from the second terminal, and FIG. 15 is a diagram illustrating the second SIP. FIG. 16 shows an example of a SIP signal edited by the SIP server, and FIG. 17 shows an example of the SIP signal converted by the first SIP-ALG device. FIG.

  As a specific example of the SIP signal conversion method of the present embodiment, first, as shown in FIG. 7, SIP communication is performed between the first terminal 103 and the second terminal 104 accommodated in the same first private network 1, A conversion method for establishing a session will be described. At this time, the SIP signals transmitted and received between the first terminal 103 and the second terminal 104 are, as shown in FIG. 7, the first NAT device 101, the first SIP-ALG device 401, the SIP server 302, the Via the second NAT device 102 and the second SIP-ALG device 402.

  At this time, if a SIP signal (INVITE request) requesting establishment of a session is transmitted from the first terminal 103 to the second terminal 104, the SIP signal is first transmitted as shown in FIG. Received by the 1 NAT device 101 (S601). At this time, the SIP signal (INVITE) transmitted from the first terminal 103 is, for example, as shown in FIG. 9, and the IP address of the SIP header and the IP address of the c field of the SDP are respectively The IP address assigned by the address system of 1 private network 1 is 192.168.0.1. Further, the port number for receiving the SIP signal and the port number for receiving the media are also the numbers 5060 and 10001 set in the first terminal.

  When receiving the SIP signal from the first terminal 103, the first NAT device 101 transfers the SIP signal to the first SIP-ALG device 401 and converts the SDP and SIP header of the SIP signal (S602).

  When the first SIP-ALG device 401 receives the SIP signal transferred from the first NAT device 101, in step 502 shown in FIG. 5, the transmission direction of the SIP signal is from the private network to the global network. judge. Therefore, the first SIP-ALG device 401 performs the conversion process in the order of step 503, step 504, step 505, step 506, and step 507 (S603). At this time, the first SIP-ALG device 401 acquires PN1 as network identification information of the private network (first private network) in which the first NAT device 101 is accommodated. Further, the IP address 192.168.0.1 and the media reception port number 10001 on the first private network side are acquired from the c field and m field of the SDP of the received SIP signal. In addition, the global network IP address 130.0.0.1, media reception port number 20001, and SIP signal reception port number 15060 are obtained in cooperation with the first NAT device. As a result, the first SIP-ALG device 401 returns the converted SIP signal to the first NAT device 101 as shown in FIG. 10 (S604). In the example shown in FIG. 10, the header name is P-ALG-INF, the network identification information (PN1), the IP address of the c field before conversion (192.168.0.1), and the port number of the m field (10001). , The original SIP header (P-ALG-) with the header value as a character string in which the five information of the converted c field IP address (130.0.0.1) and m field port number (20001) are connected with a hyphen (-) INF: PN1-192.168.0.1-10001-130.0.0.1-20001) is set.

  When the first NAT device 101 receives the SIP signal returned from the first SIP-ALG device 401 as shown in FIG. 10, the first NAT device 101 transmits the SIP signal to the SIP server 302 that is the transmission destination of the original SIP signal (INVITE). A signal is transmitted (S605).

  When the SIP server 302 receives the SIP signal as shown in FIG. 10 transmitted from the first NAT device 101, for example, it returns a SIP signal (100 Trying) indicating that signal processing is in progress. The destination of the received SIP signal (INVITE) is specified, the Via header is set, etc., and the edited SIP signal (INVITE) as shown in FIG. 11 is transmitted to the second terminal 104. . At this time, the SIP signal (INVITE) transmitted from the SIP server 302 is received by the second NAT device 102 and transferred to the second SIP-ALG device 402 (S606, S607).

  When the second SIP-ALG device 402 receives the SIP signal transmitted from the SIP server 302, it determines that the transmission direction of the SIP signal is from the global network to the private network in the step 502 shown in FIG. To do. Therefore, the second SIP-ALG device 402 performs conversion processing in the order of step 508, step 506, and step 507 (S608). At this time, since the unique SIP header is set in the SIP signal in the second SIP-ALG device 402, PN1 is used as network identification information of the private network (first private network) in which the second NAT device 102 is accommodated. To get. Further, the IP address of the c field and the media reception port number of the m field after conversion of the unique SIP header of the received SIP signal match the c field and the m field of the SDP. Further, the network identification information (PN1) of the unique SIP header matches the acquired network identification information (PN1) of the second NAT device 102. Therefore, the SDP conversion determination means 40103c of the second SIP-ALG device 402 determines that the SIP communication is between terminals in the same private network, and causes the SDP field conversion means 40103a to convert the c field and m field. At this time, the SDP field conversion means 40103a uses the IP address of the SDP c field and the media reception port number of the m field as the IP address (192.168.0.1) before conversion and the port number ( 10001). Thereafter, the SIP header converting means 40104 performs the processing of step 507. As a result, the second SIP-ALG device 402 returns the SIP signal (INVITE) converted as shown in FIG. 12 to the second NAT device (S609).

  When the second NAT device 102 receives the SIP signal returned from the second SIP-ALG device 402 as shown in FIG. A SIP signal is transmitted (S610).

  As a result, in the second terminal 104, the SIP signal in which the IP address in the c field of the SDP and the media reception port number in the m field are set to the IP address and port number on the private network side of the first terminal 103 is obtained. Can be received. At this time, when the second terminal 104 receives the SIP signal as shown in FIG. 12, for example, a SIP signal (100 Trying) indicating that signal processing is being performed or a SIP signal indicating that calling is in progress. Returns a signal (180 Ringing).

  Thereafter, when the second terminal 104 responds to the SIP signal (INVITE) as shown in FIG. 12, the SIP signal (200 OK response) indicating the response from the second terminal 104 to the SIP server 302. Is sent. At this time, the SIP signal (200 OK) is first received by the second NAT device 102 as shown in FIG. 13 (S612). At this time, the SIP signal (200 OK) transmitted from the second terminal 104 is, for example, as shown in FIG. 14, and the IP address of the SIP header and the IP address of the c field of the SDP are respectively The IP address assigned by the address system of the first private network 1 is 192.168.0.2. Also, the port number for receiving the SIP signal and the port number for receiving the media are the numbers 5060 and 10002 set in the second terminal 104, respectively.

  When receiving the SIP signal (200 OK) from the second terminal 104, the second NAT device 102 transfers the SIP signal to the second SIP-ALG device 402, and converts the SDP and SIP header of the SIP signal. (S613).

  When the second SIP-ALG device 402 receives the SIP signal transferred from the second NAT device 102, in step 502 shown in FIG. 5, the transmission direction of the SIP signal is from the private network to the global network. judge. Therefore, in the second SIP-ALG device 402, the conversion process is performed in the order of step 503, step 504, step 505, step 506, and step 507 (S614). At this time, the second SIP-ALG device 402 acquires PN1 as network identification information of the private network (first private network) in which the second NAT device 102 is accommodated. Further, the IP address 192.168.0.2 and the media reception port number 10002 on the first private network side are acquired from the c field and m field of the session description by SDP of the received SIP signal. In addition, the global network IP address 131.0.0.2, media reception port number 20002, and SIP signal reception port number 15060 are acquired in cooperation with the second NAT device. As a result, the second SIP-ALG device 402 returns the SIP signal converted as shown in FIG. 15 to the second NAT device 102 (S615). In the example shown in FIG. 15, the header name is P-ALG-INF, the network identification information (PN1), the IP address of the c field before conversion (192.168.0.2), and the port number of the m field (10002). A unique SIP header (P-ALG-) with a header value consisting of a string consisting of five pieces of information: the IP address (131.0.0.2) in the c field after conversion and the port number (20002) in the m field connected with a hyphen (-) INF: PN1-192.168.0.2-10002-131.0.0.2-20002) is set.

  When the second NAT device 102 receives the SIP signal returned from the second SIP-ALG device 402 as shown in FIG. 15, the second NAT device 102 sends the original SIP signal (200 OK) to the SIP server 302 as the transmission destination. A SIP signal is transmitted (S616).

  When the SIP server 302 receives the SIP signal (200 OK) transmitted from the second NAT device 102 as shown in FIG. 15, the SIP server 302 identifies the transmission destination of the SIP signal from the Via header, and FIG. The SIP signal (200 OK) edited as shown is transmitted to the first terminal 103. At this time, the SIP signal transmitted from the SIP server 302 is received by the first NAT device 101 and transferred to the first SIP-ALG device 401 (S617, S618).

  When receiving the SIP signal transmitted from the SIP server 302, the first SIP-ALG device 401 determines in step 502 shown in FIG. 5 that the transmission direction of the SIP signal is from the global network to the private network. To do. Therefore, the first SIP-ALG device 401 performs the conversion process in the order of step 508, step 506, and step 507 (S619). At this time, since the original SIP header is set in the SIP signal in the first SIP-ALG device 401, PN1 is used as the network identification information of the private network (first private network) in which the first NAT device 101 is accommodated. To get. Further, the IP address of the c field and the media reception port number of the m field after conversion of the unique SIP header of the received SIP signal match the c field and the m field of the SDP. Further, the network identification information (PN1) of the unique SIP header and the acquired network identification information (PN1) of the first NAT device 101 also coincide. Therefore, the SDP conversion determination unit 40103c of the first SIP-ALG device 401 determines that the SIP communication is performed between terminals in the same private network, and causes the SDP field conversion unit 40103a to convert the c field and the m field. At this time, the SDP field conversion means 40103a uses the IP address in the c field of the SDP and the media reception port number in the m field as the IP address (192.168.0.2) before conversion and the port number (in the unique SIP header). 10002). Thereafter, the SIP header converting means 40104 performs the processing of step 507. As a result, the first SIP-ALG device 401 returns the SIP signal (200 OK) converted as shown in FIG. 17 to the first NAT device 101 (S620).

  When the first NAT device 101 receives the SIP signal returned from the first SIP-ALG device 401 as shown in FIG. 17, the first NAT device 101 sends it to the first terminal 103 which is the transmission destination of the original SIP signal (200 OK). The SIP signal is transmitted (S621).

  As a result, in the first terminal 103, the SIP signal in which the IP address in the c field of the SDP and the port number for media reception in the m field are set to the IP address and port number on the private network side of the second terminal 104. Can be received. At this time, when the first terminal 103 receives the SIP signal as shown in FIG. 17, for example, it returns a SIP signal (ACK) notifying that the final response has been received. Although illustration is omitted, when the second terminal 104 receives the SIP signal (ACK), a session between the first terminal 103 and the second terminal 104 is established, and a media signal such as audio or video is transmitted. You can send and receive.

  As described above, the first terminal is configured to convert and control the IP address and port number of the SDP in the first SIP-ALG device 401 and the second SIP-ALG device 402 for the INVITE request and the 200 OK response. 103 and the second terminal 104 can exchange the IP address on the first private network 1 side with each other by the SDP. Therefore, when transmitting and receiving media signals such as audio and video between the first terminal 103 and the second terminal 104, a path that does not pass through the NAT devices 401 and 402 is set in the first private network 1, It is possible to send and receive.

  In this embodiment, the case where the INVITE request is transmitted from the first terminal 103 to the second terminal 104 has been described. However, the INVITE request is transmitted from the second terminal 104 to the first terminal 103. Needless to say, the session can be established in the same procedure.

  FIGS. 18 to 28 are schematic diagrams for specifically explaining the SIP signal conversion method of the present embodiment. FIG. 18 is a diagram showing a route of SIP communication between terminals of different private networks. FIG. 20 is a sequence diagram when a SIP signal (INVITE request) is transmitted from the fourth terminal to the second terminal, FIG. 20 is a diagram illustrating an example of a SIP signal transmitted by the fourth terminal, and FIG. 21 is converted by the third SIP-ALG device. FIG. 22 is a diagram illustrating an example of a SIP signal edited by a SIP server, and FIG. 23 is a diagram illustrating an example of a SIP signal converted by a second SIP-ALG device. FIG. 24 is a sequence diagram when a SIP signal (200 OK response) is transmitted from the second terminal to the fourth terminal, FIG. 25 is a diagram illustrating an example of a SIP signal transmitted from the second terminal, and FIG. FIG. 27 shows an example of a SIP signal edited by a SIP server, and FIG. 28 shows an example of a SIP signal converted by a third SIP-ALG device. FIG.

  As a specific example of the SIP signal conversion method of the present embodiment, next, as shown in FIG. 18, the second terminal 104 accommodated in the first private network 1 and the fourth terminal accommodated in the second private network 2. A procedure for establishing a session by performing SIP communication between the terminals 202 will be described. At this time, as shown in FIG. 18, the SIP signals transmitted and received between the second terminal 104 and the fourth terminal 202 are the second NAT device 102, the second SIP-ALG device 402, the SIP server 302, the It goes through the third NAT device 201 and the third SIP-ALG device 403.

  At this time, if a SIP signal (INVITE request) requesting establishment of a session is transmitted from the fourth terminal 202 to the second terminal 104, the SIP signal is first transmitted as shown in FIG. The data is received by the 3NAT device 201 (S701). At this time, the SIP signal (INVITE) transmitted from the fourth terminal 202 is, for example, as shown in FIG. 20, and the IP address of the SIP header and the IP address of the c field of the SDP are 2 The IP address assigned by the private network 2 address system is 192.168.1.4. Further, the port number for receiving the SIP signal and the port number for receiving the media are the numbers 5060 and 10004 set in the fourth terminal 202, respectively.

  When receiving the SIP signal from the fourth terminal 202, the third NAT device 201 transfers the SIP signal to the third SIP-ALG device 403 and converts the SDP and SIP header of the SIP signal (S702).

  When the third SIP-ALG device 403 receives the SIP signal (INVITE) transferred from the third NAT device 201, in step 502 shown in FIG. 5, the transmission direction of the SIP signal is changed from a private network to a global network. It is determined that Therefore, the third SIP-ALG device 403 performs conversion processing in the order of step 503, step 504, step 505, step 506, and step 507 (S703). At this time, the third SIP-ALG device 403 acquires PN2 as network identification information of the private network (second private network) in which the third NAT device 201 is accommodated. Further, the IP address 192.168.1.4 and the media reception port number 10004 on the second private network side are acquired from the c field and m field of the SDP of the received SIP signal. Further, in cooperation with the third NAT device 201, the global network IP address 132.0.1.4, the media reception port number 20004, and the SIP signal reception port number 15060 are obtained. As a result, the third SIP-ALG device 403 returns the SIP signal (INVITE) converted as shown in FIG. 21 to the third NAT device 201 (S704). In the example shown in FIG. 21, the header name is P-ALG-INF, the network identification information (PN2), the IP address of the c field before conversion (192.168.1.4), and the port number of the m field (10004). , The original SIP header (P-ALG-) with the header value as a character string in which the five information of the converted c field IP address (132.0.1.4) and m field port number (20004) are connected with a hyphen (-) INF: PN2-192.168.1.4-10004-132.0.1.4-20004) is set.

  When the third NAT device 201 receives the SIP signal as shown in FIG. 21 returned from the third SIP-ALG device 403, the third NAT device 201 sends the SIP server 302, which is the transmission destination of the original SIP signal (INVITE), to the SIP server 302. A signal is transmitted (S705).

  When the SIP server 302 receives the SIP signal (INVITE) transmitted from the third NAT device 201 as shown in FIG. 21, for example, it returns a SIP signal (100 Trying) indicating that signal processing is in progress. On the other hand, the destination of the received SIP signal (INVITE) is specified, the Via header is set, and the edited SIP signal (INVITE) as shown in FIG. 22 is directed to the second terminal 104. To send. At this time, the SIP signal (INVITE) transmitted from the SIP server 302 is received by the second NAT device 102 and transferred to the second SIP-ALG device 402 (S706, S707).

  When the second SIP-ALG device 402 receives the SIP signal (INVITE) transmitted from the SIP server 302, the transmission direction of the SIP signal is changed from the global network to the private network in the step 502 shown in FIG. Judge that there is. Therefore, the second SIP-ALG device 402 performs the conversion process in the order of step 508, step 506, and step 507 (S708). At this time, since the unique SIP header is set in the SIP signal in the second SIP-ALG device 402, PN1 is used as network identification information of the private network (first private network) in which the second NAT device 102 is accommodated. To get. Further, the IP address of the c field and the media reception port number of the m field after conversion of the unique SIP header of the received SIP signal match the c field and the m field of the SDP. However, the network identification information (PN2) of the unique SIP header and the acquired network identification information (PN1) of the second NAT device 102 do not match. Therefore, the SDP conversion determination unit 40103c of the second SIP-ALG device 402 determines that the SIP communication is between terminals of different private networks, and does not cause the c field and m field to be converted by the SDP field conversion unit 40103a. Thereafter, the SIP header converting means 40104 performs the processing of step 507. As a result, the second SIP-ALG device 402 returns the SIP signal (INVITE) converted as shown in FIG. 23 to the second NAT device 102 (S709).

  When the second NAT device 102 receives the SIP signal returned from the second SIP-ALG device 402 as shown in FIG. 23, the second NAT device 102 sends the original SIP signal (INVITE) to the second terminal 104 as the transmission destination. A SIP signal is transmitted (S710).

  As a result, in the second terminal 104, the SIP signal (INVITE) in which the IP address in the c field of the SDP and the media reception port number in the m field are set to the IP address and port number in accordance with the global network address system. ). At this time, when the second terminal 104 receives the SIP signal as shown in FIG. 23, for example, a SIP signal (100 Trying) indicating that signal processing is being performed or a SIP signal indicating that calling is in progress. Returns a signal (180 Ringing).

  Thereafter, when the second terminal 104 responds to the SIP signal (INVITE) as shown in FIG. 23, the SIP signal (200 OK response) indicating the response from the second terminal 104 to the SIP server 302. Is sent. At this time, the SIP signal (200 OK) is first received by the second NAT device 102 as shown in FIG. 24 (S712). At this time, the SIP signal (200 OK) transmitted from the second terminal 104 is, for example, as shown in FIG. 25, and the IP address of the SIP header and the IP address of the c field of the SDP are respectively The IP address assigned by the address system of the first private network 1 is 192.168.0.2. Also, the port number for receiving the SIP signal and the port number for receiving the media are the numbers 5060 and 10002 set in the second terminal 104, respectively.

  Upon receiving the SIP signal (200 OK) from the second terminal 104, the second NAT device 102 transfers the SIP signal to the second SIP-ALG device 402, and receives the SDP and SIP header of the received SIP signal. Conversion is performed (S713).

  When the second SIP-ALG device 402 receives the SIP signal (200 OK) transferred from the second NAT device 102, the transmission direction of the SIP signal is changed from the private network to the global in step 502 shown in FIG. It is determined to be a net. Therefore, in the second SIP-ALG device 402, conversion processing is performed in the order of step 503, step 504, step 505, step 506, and step 507 (S714). At this time, the second SIP-ALG device 402 acquires PN1 as network identification information of the private network (first private network) in which the second NAT device 102 is accommodated. Also, the IP address 192.168.0.2 and the media reception port number 10002 on the first private network side are obtained from the c field and m field of the received SIP signal. Further, in cooperation with the second NAT device 102, an IP address 131.0.0.2 for global network, a port number for media reception 20002, and a port number for SIP signal reception 15060 are acquired. As a result, the second SIP-ALG device 402 returns the converted SIP signal (200 OK) as shown in FIG. 26 to the second NAT device 102 (S615). In the example shown in FIG. 26, the header name is P-ALG-INF, the network identification information (PN1), the IP address of the c field before conversion (192.168.0.2), and the port number of the m field (10002). A unique SIP header (P-ALG-) with a header value consisting of a string consisting of five pieces of information: the IP address (131.0.0.2) in the c field after conversion and the port number (20002) in the m field connected with a hyphen (-) INF: PN1-192.168.0.2-10002-131.0.0.2-20002) is set.

  When the second NAT device 102 receives the SIP signal returned from the second SIP-ALG device 402 as shown in FIG. 26, the second NAT device 102 sends the original SIP signal (200 OK) to the SIP server 302 as the transmission destination. A SIP signal is transmitted (S716).

  When the SIP server 302 receives the SIP signal as shown in FIG. 26 transmitted from the second NAT device 102, the SIP server 302 identifies the destination of the SIP signal from the Via header, and as shown in FIG. The edited SIP signal (200 OK) is transmitted to the fourth terminal 202. At this time, the SIP signal transmitted from the SIP server 302 is received by the third NAT device 201 and transferred to the third SIP-ALG device 403 (S717, S718).

  When the third SIP-ALG device 403 receives the SIP signal (200 OK) transmitted from the SIP server 302, the SIP signal transmission direction is changed from the global network to the private network in the step 502 shown in FIG. It is determined that Therefore, the third SIP-ALG device 403 performs conversion processing in the order of step 508, step 506, and step 507 (S719). At this time, since the unique SIP header is set in the SIP signal in the third SIP-ALG device 403, PN2 is used as network identification information of the private network (second private network) in which the third NAT device 201 is accommodated. To get. Further, the IP address of the c field and the media reception port number of the m field after conversion of the unique SIP header of the received SIP signal match the c field and the m field of the SDP. However, the network identification information (PN1) of the unique SIP header and the acquired network identification information (PN2) of the third NAT device 201 do not match. Therefore, the SDP conversion determination means 40103c of the third SIP-ALG device 403 determines that the SIP communication is between terminals of different private networks, and does not cause the SDP field conversion means 40103a to convert the c field and m field. Thereafter, the SIP header converting means 40104 performs the processing of step 507. As a result, the third SIP-ALG device 403 returns the SIP signal (200 OK) converted as shown in FIG. 28 to the third NAT device 201 (S720).

  When the third NAT device 201 receives the SIP signal returned from the third SIP-ALG device 403 as shown in FIG. 28, the third NAT device 201 sends the original SIP signal (200 OK) to the fourth terminal 202 as the transmission destination. The SIP signal is transmitted (S721).

  As a result, the fourth terminal 202 receives the SIP signal in which the IP address in the c field of the SDP and the port number for media reception in the m field are set to the IP address and the port number according to the global address system. To do. At this time, when receiving the SIP signal as shown in FIG. 28, the fourth terminal 202 returns, for example, a SIP signal (ACK) notifying that the final response has been received. Although illustration is omitted, when the second terminal 104 receives the SIP signal (ACK), a session between the fourth terminal 202 and the second terminal 104 is established, and a media signal such as audio or video is transmitted. You can send and receive.

  As described above, the fourth terminal is obtained by converting and controlling the IP address and port number of the SDP in the third SIP-ALG device 403 and the second SIP-ALG device 402 for the INVITE request and the 200 OK response. 202 and the second terminal 104 can exchange SDPs set with IP addresses and port numbers on the global network side after conversion. Therefore, when a media signal such as audio or video is transmitted / received between the fourth terminal 202 and the second terminal 104, it can be transmitted / received via the third NAT device 201 and the second NAT device 102.

  In the present embodiment, the case where the fourth terminal 202 transmits the INVITE request to the second terminal 104 has been described. However, the second terminal 104 transmits the INVITE request to the fourth terminal 202. Needless to say, a session can be established in the same procedure. Also, when the INVITE request is transmitted from the fourth terminal 202 to the first terminal 103, and the INVITE request is transmitted from the first terminal 103 to the fourth terminal 202, the session is performed in the same procedure. Needless to say, it can be established.

  FIG. 29 to FIG. 39 are schematic diagrams for specifically explaining the SIP signal conversion method of the present embodiment, and FIG. 29 is a diagram showing a route of SIP communication between the terminal of the global network and the terminal of the private network. FIG. 30 is a sequence diagram when a SIP signal (INVITE request) is transmitted from the third terminal to the second terminal, FIG. 31 is a diagram showing an example of the SIP signal edited by the SIP server, and FIG. 32 is the second SIP-ALG. FIG. 33 shows an example of a SIP signal (200 OK response) transmitted by the second terminal, and FIG. 34 shows an example of a SIP signal converted by the second SIP-ALG. FIG. FIG. 35 is a sequence diagram when a SIP signal (INVITE request) is transmitted from the second terminal to the third terminal, FIG. 36 is a diagram illustrating an example of a SIP signal transmitted from the second terminal, and FIG. FIG. 38 is a diagram showing an example of a SIP signal converted by ALG, FIG. 38 is a diagram showing an example of a SIP signal (200 OK) transmitted by the third terminal, and FIG. 39 is an example of a SIP signal converted by the second SIP-ALG. FIG.

  As a specific example of the SIP signal conversion method of the present embodiment, finally, as shown in FIG. 29, the second terminal 104 accommodated in the first private network 1 and the third terminal 301 accommodated in the global network 3 are used. Of establishing a session by performing SIP communication between the two. At this time, the SIP signal transmitted and received between the second terminal 104 and the third terminal 301 passes through the second NAT device 102, the second SIP-ALG device 402, and the SIP server 302 as shown in FIG. To do. At this time, since the conversion method differs between the second terminal 104 and the third terminal 301 that transmit an INVITE request for requesting establishment of a session by SIP communication, first, from the third terminal 301 A case where the SIP signal (INVITE request) is transmitted will be described.

  When the SIP signal (INVITE request) requesting establishment of a session is transmitted from the third terminal 301 to the second terminal 104, the SIP signal is first received by the SIP server 302 as shown in FIG. (S801). At this time, in the SIP signal (INVITE) transmitted from the third terminal 301, the IP address of the SIP header and the IP address of the c field of the SDP are the IP addresses assigned by the global network address system. ing. Further, the port number for receiving the SIP signal and the port number for receiving the media are the numbers set in the third terminal 301.

  When the SIP server 302 receives the SIP signal (INVITE) transmitted from the third terminal 301, the SIP server 302 returns, for example, a SIP signal (100 Trying) indicating that signal processing is being performed, while the received SIP signal The transmission destination of the signal (INVITE) is specified, the Via header is set, and the SIP signal (INVITE) edited as shown in FIG. 31 is transmitted to the second terminal 104. At this time, the SIP signal transmitted from the SIP server 302 is received by the second NAT device 102 and transferred to the second SIP-ALG device 402 (S802, S803).

  When the second SIP-ALG device 402 receives the SIP signal (INVITE) transmitted from the SIP server 302, the transmission direction of the SIP signal is changed from the global network to the private network in the step 502 shown in FIG. Judge that there is. Therefore, the second SIP-ALG device 402 performs conversion processing in the order of step 508, step 506, and step 507 (S804). At this time, since the unique SIP header is not set in the SIP signal, the second SIP-ALG device 402 determines that the SIP communication is performed between the terminal of the global network and the terminal of the private network, and the SDP field conversion unit 40103a. Does not convert the c field and m field. Thereafter, the SIP header converting means 40104 performs the processing of step 507. As a result, the second SIP-ALG device 402 returns the SIP signal (INVITE) converted as shown in FIG. 32 to the second NAT device 102 (S805).

  When the second NAT device 102 receives the SIP signal returned from the second SIP-ALG device 402 as shown in FIG. 32, the second NAT device 102 sends it to the second terminal 104 which is the transmission destination of the original SIP signal (INVITE request). The SIP signal is transmitted (S806).

  As a result, the second terminal 104 receives the SIP signal in which the IP address in the c field of the SDP and the media reception port number in the m field are set to the IP address and port number in accordance with the global network address system. To do. At this time, when the second terminal 104 receives the SIP signal as shown in FIG. 32, for example, the SIP signal (100 Trying) indicating that the signal processing is being performed or the SIP signal indicating that the calling is being performed. Returns a signal (180 Ringing).

  Thereafter, when the second terminal 104 responds to the SIP signal (INVITE) as shown in FIG. 32, a SIP signal (200 OK response) indicating a response from the second terminal 104 to the SIP server is received. Sent. At this time, the SIP signal (200 OK) is first received by the second NAT device 102 as shown in FIG. 30 (S807). At this time, the SIP signal (200 OK) transmitted from the second terminal 104 is, for example, as shown in FIG. 33. The IP address of the SIP header and the IP address of the c field of the SDP are respectively The IP address is assigned by the address system of the first private network 1. Further, the port number for receiving the SIP signal and the port number for receiving the media are also numbers set by the second terminal 104.

  Upon receiving the SIP signal (200 OK) from the second terminal 104, the second NAT device 102 transfers the SIP signal to the second SIP-ALG device 402, and receives the SDP and SIP header of the received SIP signal. Conversion is performed (S808).

  When the second SIP-ALG device 402 receives the SIP signal (200 OK) transferred from the second NAT device 102, the transmission direction of the SIP signal is changed from the private network to the global in step 502 shown in FIG. It is determined to be a net. Therefore, in the second SIP-ALG device 402, conversion processing is performed in the order of step 503, step 504, step 505, step 506, and step 507 (S809). At this time, the second SIP-ALG device 402 acquires PN1 as network identification information of the private network (first private network) in which the second NAT device 102 is accommodated. Also, the IP address 192.168.0.2 and the media reception port number 10002 on the first private network side are obtained from the c field and m field of the SDP of the received SIP signal. In addition, the global network IP address 131.0.0.2, media reception port number 20002, and SIP signal reception port number 15060 are acquired in cooperation with the second NAT device. As a result, the second SIP-ALG device 402 returns the converted SIP signal (200 OK) as shown in FIG. 34 to the second NAT device 102 (S810). In the example shown in FIG. 34, the header name is P-ALG-INF, the network identification information (PN1), the IP address of the c field before conversion (192.168.0.2), and the port number of the m field (10002). , The original SIP header (P-ALG-) with the header value as a character string in which the five information of the converted c field IP address (131.0.0.2) and m field port number (20002) are connected with a hyphen (-) INF: PN1-192.168.0.2-10002-131.0.0.2-20002) is set.

  When the second NAT device 102 receives the SIP signal returned from the second SIP-ALG device 402 as shown in FIG. 34, the second NAT device 102 sends the original SIP signal (200 OK) to the SIP server 302 as the transmission destination. A SIP signal is transmitted (S811).

  When the SIP server 302 receives the SIP signal transmitted from the second NAT device 102 as shown in FIG. 34, the SIP server 302 specifies the destination of the SIP signal from the Via header, and edits the SIP signal (200 OK) is transmitted to the third terminal 301 (S812).

  As a result, the third terminal 301 receives the SIP signal in which the IP address in the c field of the SDP and the port number for media reception in the m field are set to the IP address and port number in accordance with the global network address system. To do. At this time, when the third terminal 301 receives the SIP signal (200 OK), for example, it returns a SIP signal (ACK) notifying that the final response has been received. Although illustration is omitted, when the second terminal 104 receives the SIP signal (ACK), a session between the third terminal 301 and the second terminal 104 is established, and a media signal such as audio or video is transmitted. You can send and receive.

  As described above, the second terminal 104 converts the IP address and port number of the SDP in the second SIP-ALG device 402 and controls the second terminal 104 for the INVITE request and the 200 OK response. The SDP in which the IP address and port number on the global network side after the conversion is set is acquired, and the second terminal 104 sets the SDP in which the actual global network IP address and port number of the third terminal 301 are set. Can be obtained. Therefore, when a media signal such as audio or video is transmitted / received between the third terminal 301 and the second terminal 104, it can be transmitted / received via the second NAT device 102.

  Next, a case where a SIP signal (INVITE request) requesting establishment of a session is transmitted from the second terminal 104 to the third terminal 301 will be described. At this time, as shown in FIG. 35, the SIP signal is first received by the second NAT device 102 (S813). At this time, the SIP signal (INVITE) transmitted from the second terminal 104 is, for example, as shown in FIG. 36. The IP address of the SIP header and the IP address of the c field of the SDP are respectively It is an IP address assigned by the address system of 1 private network 1. Further, the port number for receiving the SIP signal and the port number for receiving the media are also numbers set by the second terminal 104.

  Upon receiving the SIP signal (INVITE) from the second terminal 104, the second NAT device 102 transfers the SIP signal to the second SIP-ALG device 402, and converts the SDP and SIP header of the received SIP signal. (S814).

  When the second SIP-ALG device 402 receives the SIP signal transferred from the second NAT device 102, in step 502 shown in FIG. 5, the transmission direction of the SIP signal is from the private network to the global network. judge. Therefore, in the second SIP-ALG device 402, conversion processing is performed in the order of step 503, step 504, step 505, step 506, and step 507 (S815). At this time, the second SIP-ALG device 402 acquires PN1 as network identification information of the private network (first private network) in which the second NAT device 102 is accommodated. Also, the IP address 192.168.0.2 and the media reception port number 10002 on the first private network side are obtained from the c field and m field of the SDP of the received SIP signal. Further, in cooperation with the second NAT device 102, an IP address 131.0.0.2 for global network, a port number for media reception 20002, and a port number for SIP signal reception 15060 are acquired. As a result, the second SIP-ALG device 402 returns the SIP signal (INVITE) converted as shown in FIG. 37 to the second NAT device 102 (S816). In the example shown in FIG. 37, the header name is P-ALG-INF, the network identification information (PN1), the IP address of the c field before conversion (192.168.0.2), and the port number of the m field (10002). A unique SIP header (P-ALG-) with a header value consisting of a string consisting of five pieces of information: the IP address (131.0.0.2) in the c field after conversion and the port number (20002) in the m field connected with a hyphen (-) INF: PN1-192.168.0.2-10002-131.0.0.2-20002) is set.

  When the second NAT device 102 receives the SIP signal returned from the second SIP-ALG device 402 as shown in FIG. 37, the second NAT device 102 transmits the SIP signal to the SIP server 302 that is the transmission destination of the original SIP signal (INVITE). A signal is transmitted (S817).

  When the SIP server 302 receives the SIP signal transmitted from the second NAT device 102 as shown in FIG. 37, for example, it returns a SIP signal (100 Trying) indicating that signal processing is in progress. The destination of the SIP signal is specified from the Via header, and the edited SIP signal (INVITE) is transmitted to the third terminal 301 (S818). As a result, the third terminal 301 receives the SIP signal in which the IP address and the media reception port number are set in accordance with the global network address system after the conversion of the second terminal 104. At this time, when the third terminal 301 receives the SIP signal (INVITE), for example, a SIP signal (100 Trying) indicating that signal processing is being performed or a SIP signal (180 Trying) indicating that calling is in progress. Reply “Ringing”.

  Thereafter, when the third terminal 301 responds to the SIP signal (INVITE), the third terminal 301 transmits a SIP signal (200 OK response) indicating the response to the SIP server 302 (S819). ). At this time, the SIP signal (200 OK) transmitted from the third terminal 301 is, for example, as shown in FIG. 38, and the IP address of the SIP header and the IP address of the c field of the SDP are respectively The IP address is assigned by the address system of the global network 3. Further, the port number for receiving the SIP signal and the port number for receiving the media are also the numbers set by the third terminal 301. In the present embodiment, the SIP signal (200 OK), as shown in FIG. 38, takes over the unique SIP header set in the SIP signal (INVITE) received by the third terminal 301. To do.

  When the SIP server 302 receives the SIP signal as shown in FIG. 38 transmitted from the third terminal 301, the SIP server 302 specifies the destination of the SIP signal from the Via header and edits the SIP signal (200 OK) is transmitted to the second terminal 104. At this time, the SIP signal (200 OK) transmitted from the SIP server is received by the second NAT device 102 and transferred to the second SIP-ALG device 402 (S820, S821).

  When the second SIP-ALG device 402 receives the SIP signal (200 OK) transmitted from the SIP server 302, the transmission direction of the SIP signal is changed from the global network to the private network in the step 502 shown in FIG. It is determined that Therefore, the second SIP-ALG device 402 performs the conversion process in the order of step 508, step 506, and step 507 (S822). At this time, in the second SIP-ALG device 402, a unique SIP header is set in the SIP signal. However, if the processing in step 508c and step 508d shown in FIG. 6 is performed, the conversion in the unique SIP header is performed. The later IP address and media reception port number do not match the IP address in the c field of the SDP and the port number in the m field. Therefore, the second SIP-ALG device 402 determines that the SIP communication is between a global network terminal and a private network terminal, and does not cause the SDP field conversion means 40103a to convert the c field and m field. Thereafter, the SIP header converting means 40104 performs the processing of step 507. As a result, the second SIP-ALG device 402 returns the converted SIP signal (200 OK) as shown in FIG. 39 to the second NAT device 102 (S823).

  When the second NAT device 102 receives the SIP signal returned from the second SIP-ALG device 402 as shown in FIG. 39, the second NAT device 102 sends it to the second terminal 104 which is the transmission destination of the original SIP signal (200 OK). The SIP signal is transmitted (S824).

  As a result, the second terminal 104 receives the SIP signal in which the IP address in the c field of the SDP and the media reception port number in the m field are set to the IP address and port number in accordance with the global network address system. To do. At this time, when the second terminal 104 receives the SIP signal as shown in FIG. 39, for example, it returns a SIP signal (ACK) notifying that the final response has been received. Although illustration is omitted, when the third terminal 301 receives the SIP signal (ACK), a session between the third terminal 301 and the second terminal 104 is established, and a media signal such as audio or video is transmitted. You can send and receive.

  As described above, the second terminal 104 converts the IP address and port number of the SDP in the second SIP-ALG device 402 and controls the second terminal 104 for the INVITE request and the 200 OK response. The SDP in which the IP address and port number on the global network side after the conversion is set is acquired, and the second terminal 104 sets the SDP in which the actual global network IP address and port number of the third terminal 301 are set. Can be obtained. Therefore, when a media signal such as audio or video is transmitted / received between the third terminal 301 and the second terminal 104, it can be transmitted / received via the second NAT device 102.

  In the present embodiment, the case where SIP communication is performed between the third terminal 301 and the second terminal 104 has been described. However, the third terminal 301 and the second terminal 104 are connected between the third terminal 301 and the first terminal 103. Needless to say, when SIP communication is performed between the four terminals 202, a session can be established in the same procedure.

  As described above, according to the SIP signal conversion method of the present embodiment, when a SIP signal is transmitted and received between terminals, a SIP-ALG device through which a SIP signal transmitted from the private network to the global network passes, Even if SIP-ALG devices through which SIP signals transmitted from the global network to the private network pass are different, the SIP-ALG devices through which SIP signals transmitted from the global network to the private network are independent, It is possible to determine whether the terminal that transmitted the SIP signal and the terminal that receives the SIP signal are accommodated in the same private network. Therefore, there is no need to make an inquiry to another SIP-ALG as in the prior art, and the processing delay in SIP communication can be reduced.

  Further, in the SIP signal conversion method of the present embodiment, by setting the unique SIP header, the SIP-ALG device through which the SIP signal transmitted from the global network to the private network passes has transmitted the SIP signal. When the terminal is accommodated in the same private network as the terminal that receives the SIP signal, the IP address in the c field of the SDP and the media reception port number in the m field are converted before referring to the unique SIP header, that is, It can be converted into IP address and port number according to the private network address system. Therefore, when SIP communication is performed between terminals accommodated in the same private network and a session is established, transmission / reception of media signals such as voice and video after the session is established does not pass through a NAT device in the private network. Can be set and transmitted / received.

  The present invention has been specifically described above based on the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. is there.

  For example, in the above-described embodiment, the example has been described in which the SIP-ALG device performs the process as shown in FIGS. 5 and 6 to convert the SIP layer IP address and port number of the SIP signal. If the conversion result is the conversion method finally described in the above embodiment, for example, the order of the steps shown in FIGS. 5 and 6 may be changed.

  In the above embodiment, the SIP-ALG apparatus having the configuration as shown in FIG. 2 is taken as an example. However, the present invention is not limited to this, and some functions of each means shown in FIG. It may be configured by the above means.

  In the embodiment, as shown in FIGS. 10, 15, 21, 26, 34, and 37, the header name is P-ALG-INF, the network identification information, and the c before conversion. A unique SIP header was set with a header value consisting of a string consisting of five pieces of information: the IP address of the field, the port number of the m field, the IP address of the converted c field, and the port number of the m field. However, if the settings are such that the five pieces of information can be identified, for example, a header for setting the network identification information, a header for setting an IP address before conversion and a port number for media reception, an IP address after conversion and for media reception A plurality of headers such as a header for setting a port number may be set.

  In the above-described embodiment, the network configuration in which the private network and the global network are connected has been described as an example. However, the present invention is not limited to this. The SIP signal conversion method of the present invention can also be applied to a network configuration in which the SIP-ALG device rewrites the SIP layer IP address and port number of the SIP signal during SIP communication.

  Further, in the above-described embodiment, the case where the respective units perform the conversion processing in cooperation with each other in the SIP-ALG apparatus having the configuration as illustrated in FIG. 2 is described as an example. You may make a computer perform the process as shown to FIG. 5 and FIG. In this case, a program for causing the computer to execute the process of each step as shown in FIGS. 5 and 6 may be prepared and executed by the computer. At this time, the program may be provided by being recorded on a magnetic, electrical, or optical recording medium, or may be provided through a network such as the Internet.

It is a schematic diagram for demonstrating the SIP signal conversion method of one Example by this invention, and is a figure which shows the structural example of the network to which the SIP signal conversion method of this Example is applied. It is a schematic diagram for demonstrating the SIP signal conversion method of one Example by this invention, and is a figure which shows the structural example of SIP-ALG of FIG. It is a schematic diagram for demonstrating the SIP signal conversion method of one Example by this invention, and is a figure which shows an example of a network address management table. It is a schematic diagram for demonstrating the SIP signal conversion method of one Example by this invention, and is a figure which shows an example of a NAT corresponding network identification information management table. It is a schematic diagram for demonstrating the SIP signal conversion method of one Example by this invention, and is a flowchart for demonstrating an example of the process sequence in SIP-ALG. It is a schematic diagram for demonstrating the SIP signal conversion method of one Example by this invention, and is a flowchart for demonstrating an example of the specific process sequence of step 508 of FIG. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows the path | route of SIP communication between the terminals of the same private network. It is a schematic diagram for demonstrating the SIP signal conversion method of a present Example concretely, and is a sequence diagram at the time of transmitting a SIP signal (INVITE request) from the 1st terminal to the 2nd terminal. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal which a 1st terminal transmits. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted with the 1st SIP-ALG apparatus. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal edited with the SIP server. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted with the 2nd SIP-ALG apparatus. It is a schematic diagram for demonstrating the SIP signal conversion method of a present Example concretely, and is a sequence diagram at the time of transmitting a SIP signal (200 OK response) from a 2nd terminal to a 1st terminal. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal which a 2nd terminal transmits. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted with the 2nd SIP-ALG apparatus. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal edited with the SIP server. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted by 1st SIP-ALG. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows the path | route of SIP communication between the terminals of a different private network. It is a schematic diagram for demonstrating the SIP signal conversion method of a present Example concretely, and is a sequence diagram at the time of transmitting a SIP signal (INVITE request) from the 4th terminal to the 2nd terminal. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal which a 4th terminal transmits. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted with the 3rd SIP-ALG apparatus. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal edited with the SIP server. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted with the 2nd SIP-ALG apparatus. FIG. 24 is a schematic diagram for specifically explaining the SIP signal conversion method of the present embodiment, and FIG. 24 is a sequence diagram when a SIP signal (200 OK response) is transmitted from the second terminal to the fourth terminal. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal which a 2nd terminal transmits. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted with the 2nd SIP-ALG apparatus. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal edited with the SIP server. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted with the 3rd SIP-ALG apparatus. It is a schematic diagram for demonstrating concretely the SIP signal conversion method of a present Example, and is a figure which shows the path | route of SIP communication between the terminal of a global network and the terminal of a private network. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a sequence diagram at the time of transmitting a SIP signal (INVITE request) from the 3rd terminal to the 2nd terminal. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal edited with the SIP server. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted by 2nd SIP-ALG. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal (200 OK response) which a 2nd terminal transmits. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted by 2nd SIP-ALG. It is a schematic diagram for demonstrating concretely the SIP signal conversion method of a present Example, and is a sequence diagram at the time of transmitting a SIP signal (INVITE request) from the 2nd terminal to the 3rd terminal. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal which a 2nd terminal transmits. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted by 2nd SIP-ALG. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal (200 OK) which a 3rd terminal transmits. It is a schematic diagram for demonstrating specifically the SIP signal conversion method of a present Example, and is a figure which shows an example of the SIP signal converted by 2nd SIP-ALG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st private network 101 ... 1st NAT apparatus 102 ... 2nd NAT apparatus 103 ... 1st terminal 104 ... 2nd terminal 2 ... 2nd private network 201 ... 3rd NAT apparatus 202 ... 4th terminal 3 ... Global network 301 ... 3rd Terminal 302 ... SIP server 401 ... First SIP-ALG device 402 ... Second SIP-ALG device 403 ... Third SIP-ALG device 40101 ... SIP signal transmission / reception means 40102 ... Transmission direction determination means 40103 ... SDP conversion means 40103a ... SDP field conversion means 40103b ... Original SIP header setting means 40103c ... SDP conversion determination means 40104 ... SIP header conversion means 40105 ... Network address management means 40106 ... NAT-compatible network identification information management means

Claims (6)

A SIP network accommodated in the private network, in which one or more private networks accommodating two or more terminals and two or more NAT (Network Address Translation) devices are connected to the global network by the NAT devices. (Session Initiation Protocol) SIP communication between a SIP compatible terminal in the same private network or a SIP compatible terminal accommodated in the global network or another private network via a SIP server accommodated in the global network SIP-ALG (SIP-Application Level Gateway) SIP signal conversion method for converting the IP address and port number of a SIP signal in cooperation with the NAT device,
Managing a correspondence relationship between each NAT device and a private network in which the NAT device is accommodated; and
When the SIP signal transferred from the NAT device is a signal transmitted from the private network to the global network and there is a session description by SDP, the IP of the session description by SDP of the SIP signal in cooperation with the NAT device Step 2 for converting the address and the media reception port number;
The identification information of the private network in which the NAT device that transferred the SIP signal is accommodated, and the IP address and media reception port number of the session description by the SDP before conversion in the step 2 are used as the unique SIP header in the SIP signal. Step 3 to set,
Step 4 of converting the IP address and port number of the SIP header of the SIP signal in cooperation with the NAT device;
Step 5 for determining whether or not the unique SIP header is set when the SIP signal transferred from the NAT device is a signal transmitted from the global network to the private network and there is a session description by the SDP. When,
If it is determined in step 5 that a unique SIP header has been set, the private network in which the NAT device that transferred the SIP signal is accommodated is identified, and the private network described in the unique SIP header is identified. Step 6 for determining whether it matches the identification information;
If it is determined in step 6 that they match, the IP address and media reception port number in the session description by SDP of the SIP signal are converted into the IP address and media reception port number described in the unique SIP header. And a SIP signal conversion method comprising: The step 3 is converted in the step 3 in addition to the identification information of the private network in which the NAT device is accommodated, the IP address and the media reception port number of the session description by the SDP before the conversion in the step 3. Set the IP address and media reception port number of the session description by SDP later as a unique SIP header,
Step 7 is determined to match in Step 6, and the IP address after conversion described in the unique SIP header of the SIP signal and the port number for media reception are the IP address of the session description by SDP of the SIP signal. 2. The SIP signal conversion method according to claim 1, wherein the IP address and the media reception port number of the session description by the SDP are converted only when they coincide with the media reception port number. A SIP network accommodated in the private network, in which one or more private networks accommodating two or more terminals and two or more NAT (Network Address Translation) devices are connected to the global network by the NAT devices. SIP communication between a (Session Initiation Protocol) compatible terminal and a SIP compatible terminal in the same private network or a SIP compatible terminal accommodated in the global network or another private network via a SIP server accommodated in the global network A SIP-ALG (SIP-Application Level Gateway) device that converts the IP address and port number of a SIP signal in cooperation with the NAT device,
Network address management means for managing the correspondence between the IP address on the private network side and the IP address on the global network side managed by each NAT device collectively for each NAT device;
NAT-compatible network identification information management means for managing the correspondence between each NAT device and the private network in which the NAT device is accommodated;
When the SIP signal transferred from the NAT device is a signal transmitted from the private network to the global network, and there is a session description by SDP, based on the correspondence managed by the NAT-compatible network identification information management means, Means for identifying the private network in which the NAT device is accommodated;
SDP field conversion means for converting the IP address and media reception port number of the session description by SDP of the SIP signal in cooperation with the NAT device;
Unique SIP header setting means for setting the identification information of the specified private network and the IP address and media reception port number of the session description by the SDP before conversion by the SDP field conversion means as the unique SIP header in the SIP signal When,
SIP header conversion means for converting the IP address and port number of the SIP header of the SIP signal in cooperation with the NAT device;
The SIP signal transferred from the NAT device is a signal transmitted from a global network to a private network, and there is a session description by the SDP, the unique SIP header is set, and the NAT device When the identification information of the private network in which the private network is stored matches the identification information of the private network described in the unique SIP header, the SDP field conversion means sends the IP address of the session description by SDP of the SIP signal and A SIP-ALG apparatus comprising: a conversion determination means for converting a media reception port number into an IP address and a media reception port number described in the unique SIP header. The unique SIP header setting means adds the private network identification information, the IP address and the media reception port number of the session description by the SDP before the conversion at the step 3, and the SDP after the conversion at the step 3. Set the session description IP address and media reception port number as a unique SIP header,
The conversion determination means satisfies the determination conditions, and the IP address and media reception port number after conversion described in the unique SIP header of the SIP signal are the IP address and medium of the session description by SDP of the SIP signal. 4. The SIP-ALG device according to claim 3, wherein the SIP-ALG device converts the IP address and media reception port number of the session description by the SDP only when the reception port number matches.   A SIP signal conversion program for causing a computer to execute the processing of each step according to claim 1 or 2. 6. A recording medium on which the SIP signal conversion program according to claim 5 is recorded in a state that can be read by the computer.

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