KR100726185B1 - System, gateway server and stun server for internetwork communication between networks using various internet protocol address, and method thereof - Google Patents

Abstract

An interworking service system between IP(Internet Protocol) networks using different IP addresses, a gateway device, a server, and an interworking service method are provided to solve an NAT(Network Address Translation)-traversal problem for a protocol where call setup and substantial data transceiving are separated, by using an existing NAT without requiring a large change of an existing STUN(Simple Traversal UDP through NAT) protocol itself. The first server(400) is located outside an NAT(300), and provides public IP binding information for a private IP passing through the NAT. The second server(200) is located in a local network(10), extracts host information for receiving media from a packet payload of a call connection request received from a terminal(100) allocated with the private IP address, and obtains host information bound to the public IP by the first server for the extracted host information, then applies the obtained information to the packet payload of the call connection request to send the information to a receiving terminal(500).

Description

System, gateway server and STUN server for internetwork communication between networks using various internet protocol address, and method

1 is a block diagram of a system for providing interworking between IP networks using different IP addresses according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating detailed functional blocks of the second server in the interlock providing system of FIG. 1.

3 is a diagram illustrating an IP header set by a second server of FIG. 2.

4 is a diagram illustrating a UDP header set by a second server of FIG. 2.

FIG. 5 is a block diagram illustrating detailed functional blocks of the first server in the interlock providing system of FIG. 1.

6 is a diagram illustrating a method for providing interworking between IP networks using different IP addresses according to the first embodiment of the present invention.

7 is a diagram showing an implementation of an interworking providing system according to a second embodiment of the present invention in a mobile communication network.

8 is a diagram illustrating a linkage providing method according to a second embodiment of the present invention.

The present invention relates to an interworking providing system, a gateway device, a server, and an interworking providing method between IP networks using different IP addresses.

IMS (IP Multimedia Subsystem), called the third generation network platform, is a technology that provides all services based on IP, unlike a circuit-oriented network system. IMS, the third-generation switching system, followed by circuit switches and softswitches, integrates voice and data services into a single structure and delivers them to fixed or mobile devices on an IP network.

It also has the meaning of turning the network open using the Internet protocol. Technology that accelerates network convergence by increasing the service flexibility of wired and wireless networks is a concern of the telecom industry in that it not only reduces application development and management costs, but also increases the diversity of new services.

Such an IP network assigns a globally common IP, that is, a global IP (hereinafter, referred to as a public IP) address to each terminal to identify a sender address in communication between the terminals.

However, with the expansion of IP network applications, including IMS, public IP addresses are in short supply due to the increase in utilization.

Accordingly, most carriers use NAT (Network Address Translation) technology for securing insufficient public IP address and securing network stability.

NAT is a network address translation technology that translates private IP addresses into public IP addresses. That is, the terminal assigns a private IP address that can be used only in the local network. When such a terminal uses another network or the public network, the private IP address assigned to the terminal is converted into a public IP address, and the public IP address is converted into a private IP address. In addition, as one NAT, Port Address Translation (PAT) translates not only IP addresses but also port numbers of TCP / UDP. This solves the problem of lack of public IP address by allowing a large number of public IP addresses to be used together.

However, since NAT can analyze only the 3rd and 4th layer headers of the OSI model and not the upper layers, the NAT recognizes the packet generating host's identification information (source address, originating port) in the payload in the 4th layer header of the packet. Including Internet applications are not supported. This is called a problem with NAT-Traversal.

In other words, the problem of NAT-Traversal is that the identification information of the originator address of the terminal in the local network, that is, the packet generating host set to the private IP address, cannot be converted to the public IP address by NAT, so that the incoming routing from the outside cannot occur. it means.

As a conventional technique for solving this problem, there is a Simple Traversal under UDP through NAT (hereinafter, referred to as STUN) method.

STUN is a technology based on Server-Client. It is a technology that provides public IP address and port information allocated by NAT, located outside of NAT. According to this STUN, individual terminals running the STUN-Client can obtain a NAT-translated public IP address from the STUN server, respectively.

However, the STUN-Client must be driven for each individual terminal, so it is difficult to apply it directly to the network and acts as a kind of burden on the terminal.

In addition, the calling terminal may not know whether the called terminal exists on the same network before the call connection. In this case, although the destination terminal exists in the own network that does not need NAT traversal, an unnecessary process of accessing the STUN server through the NAT is performed. This causes irrationality of call processing and waste of radio channel.

Accordingly, the technical problem to be achieved by the present invention is to provide an interworking providing system, a gateway device, a server, and an interworking providing method between IP networks using different IP addresses to solve the NAT-Traversal problem.

Another technical problem to be achieved by the present invention is to provide an interworking providing system, a gateway device, a server, and an interworking providing method for solving a NAT-Traversal problem in an IP network using different IP addresses using a Session Initiation Protocol (SIP). .

According to a feature of the present invention in order to achieve the above problems,

Interlocking provision system,

In a system providing interworking using NAT (Network Address Translation) between a local network using a private IP and a global network using a public IP, public IP binding information for the private IP located outside the NAT and passing through the NAT is provided. Providing a first server; And extracting host information for media reception from a packet payload of a call connection request received from a terminal allocated with the private IP address, and located in the local network, and authorized by the first server for the extracted host information. And a second server that acquires IP information bound to IP, applies the packet payload of the call connection request, and transmits the received host information to the called terminal.

According to another feature of the invention,

Gateway device,

A gateway device including a server providing binding information of a public IP and providing interworking using a NAT between a global network using a public IP and a local network using a private IP, comprising: configuring a node of the local network; IP masquerading, which extracts host information for media reception from a payload of a call connection request packet and replaces header information for requesting binding information of the public IP with host information of the extracted private IP type. module; A public IP binding client module for requesting the public IP binding including the header information changed by the IP masquerading module and a response address set to the IP address of the second server to receive a public IP binding response; And an application layer gateway module for acquiring host information converted from the public IP binding response to the public IP and changing the host information of the packet payload.

According to another feature of the invention,

The server,

A server including a gateway device that performs client functions for IP binding and connected to an outside of a NAT located at a boundary between a local network using a private IP and a global network using a public IP. A first module for storing configuration information for performing a public IP binding operation; And extracting header information converted from the public IP binding request received from the gateway device to the public IP address according to the configuration information, checking the response address, and using the response address to extract the header information. And a second module for transmitting the cited public IP binding response to the gateway device.

According to another feature of the invention,

The interlocking offer method,

A method for providing interworking using NAT (Network Address Translation) between a local network using private IP and a global network using public IP, the method comprising: (a) a packet of a call connection request received by the local network from a terminal in the local network; Extract host information for receiving media set to private IP from payload

step; (b) replacing the header information with the extracted host information and transmitting a binding request for a public IP; (c) receiving a binding response of a public IP including header information converted into a public IP by the NAT; And (d) obtaining host information bound to the public IP from the header information included in the binding response of the public IP, applying the same to the call connection request packet, and transmitting the host information to the called terminal.

According to another feature of the invention,

The interlocking offer method,

In a method of providing interworking using a network address translation (NAT) between a local network using a private IP and a global network using a public IP, the local network may include an SDP message of an INVITE message when SIP (Seesion Initiation Protocol) is performed. Extracting media reception information set to the private IP included; Replacing a header of a STUN (Simple Traversal under UDP through NAT) binding request message for obtaining public IP binding information for the private IP of the media reception information with the extracted media reception information; Transmitting the stun binding request message and receiving a stun binding response message including header information that is converted to a public IP through NAT; And acquiring the public IP information of the substituted media reception information from the header information converted into the public IP and changing the media reception information of the INVITE message to the obtained information.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In addition, when a part is said to "include" a certain component, this means that it may further include other components, except to exclude other components unless otherwise stated.

In addition, the term module described herein refers to a unit for processing a specific function or operation, which may be implemented in hardware or software, or a combination of hardware and software.

Now, the interworking providing system, the gateway device, the server and the interworking providing method between IP networks using different IP addresses will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a system for providing interworking between IP networks using different IP addresses according to a first embodiment of the present invention.

That is, according to Figure 1, each host (node) of the interworking providing system is the source terminal 100, the second server 200, network address translation means 300, the first server 400 and the destination terminal 500 ).

Here, the interworking providing system is implemented in an IP network 1 including a local network 10 using a private IP address and a global network 20 using a public IP address.

In addition, the interworking providing system uses a protocol in which a signaling process for call setup and a media session process for data transmission and reception are separated, and negotiation information of the media session process is recorded in a packet payload. In this protocol, host information is included in a payload of an application itself, and thus media session negotiation is performed between an end host, that is, a calling terminal 100 and a called terminal 500. In this case, the host information means more specifically, media reception information for actually exchanging multimedia such as voice and video between end hosts, that is, address information of the destination terminal 100 and 200 for media reception.

The calling terminal 100 and the called terminal 500 are terminating hosts on the communication line of the IP network 1. At this time, the terminal (calling side) 100 is located in the local IP network 10 and is assigned a private IP address. The terminal 500 may be a terminal that is located in the global IP network 20 and is assigned a public IP address or a terminal that is allocated to a corresponding private IP address in another local IP network.

The second server 200 changes the media reception information in the form of a private IP address into the media reception information in the form of a public IP address in the payload of the packet transmitted from the originating terminal 100 to the corresponding terminal (called party) 500. To send. In other words, it performs the application level gateway (ALG) function.

At this time, the public IP address is obtained by requesting binding information of the public IP to the first server 400 and receiving a binding response. Therefore, the second server 200 serves as a client for binding the public IP address.

Here, the binding request of the public IP address uses the IP Masquerading technique. IP Masquerading is a networking feature of Linux that allows computers connected to a Linux box to be assigned a virtual IP address so that they can connect to the Internet with a single IP address.

Therefore, when using IP masquerading, the binding request is transmitted to the second server 300 in which the header information is replaced with media reception information in the form of a private IP address extracted from the payload of the packet received from the originating terminal 100. . Then, the binding information of the public IP address with respect to the header information is received from the second server 300.

In this case, since the binding information of the received public IP address is for the header information substituted with the media reception information, thereby obtaining media reception information in the form of public IP address for the media reception information in the form of private IP address included in the packet payload. . Accordingly, the second server 200 performs an IP masquerading function.

The network address translation means 300 refers to a network address translation (NAT), which is located at the boundary between the local network 10 and the global network 20 to obtain source address information in the form of a private IP address included in the header of the packet. Convert to source address information in the form of a public IP address. In addition, source address information in the form of public IP address is converted into source address information in the form of private IP. This source IP address information includes an IP address and a port. In this case, address translation is possible for the network layer and the transport layer corresponding to layers 3 and 4 based on the Open System Interconnection (OSI) model.

The first server 400 is connected to the global network 20 and provides binding information of the public IP address by the network address translation means 300. That is, the server performs a server function corresponding to the client for binding the public IP address of the first server. Therefore, when the binding request is received from the second server 200, the header information of the packet converted to the public IP address is extracted while passing through the network address conversion means 300. In addition, this is transmitted to the second server 200 in a binding response. At this time, the first server 400 transmits the binding response to the address confirmed by confirming the response destination address of the binding request. The binding response address is set by the second server 200 as its own IP address at the time of the binding request. .

FIG. 2 is a block diagram illustrating detailed functional blocks of the second server in the interlock providing system of FIG. 1.

That is, according to FIG. 2, the second server 200 includes a first module 210, a second module 220, a third module 230, a fourth module 240, and a fifth module 250. .

The first module 210 performs IP masquerading. In more detail, the header information setting unit 220 and the header checksum calculator 230 may be included.

The header information setting unit 220 sets the media reception information extracted from the payload of the packet received from the originating terminal 100 as header information of the packet for the binding request to be transmitted to the first server 400. This header information setting will be described with reference to FIGS. 3 and 4 as follows.

First, referring to FIG. 3, this is an illustration of an IP header, in which a parameter "Source IP Address" (P100) is replaced with media reception information of the calling terminal 100.

Referring next to Figure 4, this is a UDP header parameter "Source port" (P200) is replaced with the media reception information of the source terminal 100.

Here, the media reception information, as already mentioned in FIG. 1, is assigned to the destination IP terminal 100, 200 as a private IP address as an IP address for media reception.

The header checksum calculator 230 recalculates the parameter "Header Checksum" P120 of the IP header by reflecting the IP address value substituted by the header information setting unit 220. In addition, the parameter "Checksum" P220 of the UDP header can be recalculated. However, this is not necessary because the UDP layer does not recalculate a separate parameter "Checksum" (P220).

The second module 220 performs a client function corresponding to the first server 400 providing binding information of the public IP address. That is, the packet for the binding request in which the header information is substituted by the first module 210 is transmitted to the first server 400. At this time, the response address of the binding request is set as the IP address of the second server 200 and transmitted.

When receiving the binding response from the first server 400, the public IP binding information of the header information is extracted therefrom.

The third module 230 performs an application layer gateway function of changing media reception information in the form of a private IP address included in the payload of the packet into media reception information in the form of a public IP address. That is, the media reception information in the form of a private IP address is changed to public IP binding information of the header information extracted by the second module 220. Here, since the header information is information obtained by replacing the media reception information in the form of a private IP address by the first module 210, its public IP binding information is the same as the media reception information in the form of a public IP address.

In addition, as shown in FIG. 2, the second server 200 may include a fourth module 240. Here, the fourth module 240 performs a call relay function. In other words, the proxy function receives the call connection request from the calling terminal 100 and delivers it to the called terminal 500 and receives the call connection response from the called terminal 500 and delivers it to the calling terminal 100. Do this. In this case, the call connection request transmitted to the called terminal 500 is a packet in which the media reception address information of the payload provided from the third module 230 is converted into a public IP address.

In addition, the second server 200 may include a fifth module 250, as shown in FIG. 2. The fifth module 250 interworks with the first module 210 and the fourth module 240. By determining the destination of the received packet header, it is determined whether the network of the calling terminal 100 and the called terminal 500 is the same to determine whether to perform IP masquerading. At this time, if it determines to perform the IP masquerading to inform the first module 240.

Therefore, according to the configuration of the second server 200, the second module 220 performs the client function of the public IP binding, including the fifth module 250 to determine whether to perform public IP binding through this Can be. For this reason, do not perform public IP binding on the same network that does not require network address translation before the negotiation of the communication session is completed.

FIG. 5 is a block diagram illustrating detailed functional blocks of the first server in the interlock providing system of FIG. 1.

That is, according to Figure 5, the first server 400 performs the server function of the public IP binding. More specifically, the first module 410 and the second module 420 may be included.

The first module 410 stores the setting information for performing the process of the public IP binding in conjunction with the second server 200, in particular, the second module 220.

The second module 420 is the public IP address information converted by the network address conversion means 300 in the header information of the public IP binding request received from the second module 220 according to the setting information of the first module 410. Extract In addition, the response address set from the response address information of the public IP binding is extracted. The extracted public IP address information is loaded into the public IP binding response and transmitted to the extracted response address.

6 is a diagram illustrating a method for providing interworking between IP networks using different IP addresses according to the first embodiment of the present invention.

That is, according to FIG. 6, the calling terminal 100 assigned the private IP address transmits a call connection request to the second server 200 (S101).

By the way, it may further comprise the step (S103, S105, S107) before the step (S109).

That is, the second server 200 determines whether the network where the calling terminal 100 and the called terminal 500 are located in the call connection request received in step S101 is the same network (S103). The determination is made by comparing the IP address specified in the destination of the call connection request (corresponding to the parameter "Destination IP Address" in the IP header) with the IP address specified in the source (corresponding to the parameter "Source IP Address" in the IP header). Can be.

First, as a result of the determination in step S103, when the calling terminal 100 and the called terminal 500 exist in the same network that does not require IP address translation, there is no need to pass through the network address translation means 300. In operation S107, the call connection request from the calling party terminal 100 is transmitted to the called party terminal 500.

Next, if the originating terminal 100 and the called terminal 500 are present in different networks as a result of the determination in step S103, IP address translation is required, so that IP masquerading is determined.

Then, the second server 200 performs IP masquerading (S109). That is, the media reception information is extracted from the payload of the packet for the call connection request received in step S101. And it is replaced with the header information of the packet for the public IP binding request to be transmitted to the first server (400).

Then, the second server 200 transmits the IP masqueraded public IP binding request to the first server 400 (S111). In this case, the public IP binding request includes response address information set as the IP address of the second server 200.

Then, the first server 400 performs a public IP binding operation (S113). That is, the header information converted to the public IP address is extracted from the public IP binding request received through the network address conversion unit 300. The extracted header information is included in the public IP binding response.

Then, the first server 400 transmits the public IP binding response to the second server 200 by using the IP address of the second server 200 included in the response address information of the public IP binding request (S115).

Then, the second server 200 receives the public IP binding response to perform the application layer gateway function (S117). That is, the media reception information of the payload of the call connection request received in step S101 is changed to the public IP-bound header information extracted from the public IP binding response.

Then, the second server 200 transmits the call connection request in which the packet payload is changed to the media reception information in the form of a public IP address through the network address translation means 300 to the called terminal 500 (S119).

Then, the call connection response is received from the called terminal 500 (S121).

Then, a call connection is made between the calling terminal 100 and the called terminal 500.

Thus, even if the network address conversion means 300 converts only the header information of the call connection request into the public IP address, the media reception information is already converted into the public IP address through the steps S109, S111, S113, S115, and S117. Therefore, media session negotiation can be performed smoothly.

Based on the above description, the interworking providing system and interworking providing method between IP networks using different IP addresses according to the second embodiment of the present invention will be described with reference to FIGS. 7 to 8.

That is, FIG. 7 is a diagram illustrating an implementation of an interworking providing system according to a second embodiment of the present invention in a mobile communication network, and FIG. 8 is a diagram illustrating a interworking providing method according to a second embodiment of the present invention. At this time, the protocol uses a Session Initiation Protocol (SIP) protocol.

First, referring to FIG. 7, a SIP User Agent A 600 is located in a mobile communication network 30 and is connected to a Radio Access Network (RAN). Here, the radio access network refers to a network connected to the SIP user agent A 600 through a wireless network, including the base station 700 and the PDSN / GGSN 800.

The base station 700 converts an analog signal received from the SIP user agent A 600 in the serving cell into a digital signal and delivers the digital signal to the PDSN / GGSN 800 connected by wire. The digital signal received from the PDSN / GGSN 800 is converted into an analog signal and transmitted to the SIP user agent A 600.

PDSN / GGSN 800 performs IP address allocation / management / routing. That is, the digital signal received from the base station 700 is converted into an IP packet and sent to the Internet network 40. In addition, the IP packet received from the Internet network 40 is converted into a digital signal and sent to the base station 700. Accordingly, the SIP user agent A 600 may exchange the SIP packet in the form of an IP packet with the SIP user agent B 1200 through the radio access network.

The gateway device 900 performs an SIP-ALG (Application Level Gateway) function, an IP masquerading function, a STUN client function, and a SIP-Proxy function.

The SIP-ALG (Application Level Gateway) function performs an ALG function that allocates and converts a source IP address and a source port of a SIP message into an IP form that can be received from the Internet. More specifically, address / port information in “m (media) / c (connection) line” in the Content (SDP section) of the INVITE message is converted into an IP type that can be interworked with the Internet network.

At this time, the conversion is performed by setting the IP address and port of the SIP user agent A 600 in the packet through the IP masquerading function.

The STUN Client function allows the STUN Server 1000 to obtain a public IP address (IP address and port) for the SIP User Agent A 600 to receive media from the Internet 40. Receive by request. This is called stun binding.

SIP-Proxy functions as a proxy server between SIP user agents A and B (600, 1200).

The gateway device 900 configured as described above solves the NAT-Traversal problem when interworking with the Internet network 40 using the SIP message. In addition, since the stun client exists as a separate device on the node other than the SIP user agent A 600, the burden on the terminal is minimized. In addition, it is possible to perform the stun binding operation after receiving the INVITE message, so that if the SIP user agent B 1200 is in the mobile communication network 30, the session can be directly connected without the stun binding operation. This can prevent the irrationality of call processing and the waste of the radio channel due to the stun binding operation regardless of the network where the called SIP user agent is provided because the stun client is provided in the terminal.

The network address translation (NAT) 1000 allocates and converts a source IP address and a source port of a packet in the form of a public IP so that an incoming call is possible when the mobile communication network 30 and the Internet network 40 interwork.

The STUN (Simple Traversal UDP through NAT) server 1100 is located outside the NAT 1000. The SIP-user agent 600 located in the mobile communication network 30 notifies the stern client, that is, the gateway device 900, of the public IP address and port assigned by the NAT 1000 when interworking with the internet network 40.

The gateway device 900, the NAT 1000, and the stun server 1100 described above correspond to the second server 200, the network address translation means 300, and the first server 400 in FIGS. 1 to 4, respectively. The configuration of the embodiment described.

Next, referring to FIG. 8, a call flow for session negotiation between SIP user agents A and B 600 and 1200 is illustrated in the network of FIG. 7.

That is, as shown in FIG. 8, session negotiation is performed using SIP messages such as "INVITE", "100 Trying", "183 Session Progress", "PRRACK", "200 OK", and "ACK".

However, at this time, the gateway device 900 receiving the "INVITE" message from the SIP user agent A 600 (S201) performs IP masquerading (S203). That is, the header information for the "STUN Binding-Request" message is assigned to the IP address specified in the m (media) / c (connection) line of the "Session Description Protocol" message contained in the body of the "INVITE" message. Replace with a Port value. At this time, the "Response-Address" set as the IP address of the gateway device 900 is inserted into the "STUN Binding-Request" message.

Then, the gateway device 900 transmits the " STUN Binding-Request " message, which has passed through the step S203, to the stun server 1100 (S205).

Then, the stun server 1100 extracts "Source-IP-Address" in the converted IP header and "Source-Port" in the UDP header from the header information of the "STUN Binding-Request" message. . This is specified in the "Mapped-Address" attribute of the "STUN Binding-Response" message (S207). Then, the gateway device 900 transmits the "STUN Binding-Response" to the address specified in the "Response-Address" attribute of the "STUN Binding-Request" message (S209).

Then, the gateway device 900 extracts the "Mapped-Address" attribute value of the "STUN Binding-Response" message from the stun server 1100, and the IP address in the media reception address (m / c line) in "INVITE" and An ALG operation of changing a port to the extracted attribute value is performed (S211).

Then, the gateway device 900 transmits the message " INVITE " which has passed through the step S209 to the user agent B 1200 (S213).

According to the above description, before transmitting the "INVITE" message to the destination SIP user agent B 1200 when signaling for call connection, the media reception information included in the "SDP" message of the "INVITE" message is not associated with IP masquerading. According to the stun binding operation, the Internet network 40 sets an incoming IP address.

Therefore, in case of a protocol divided into a signaling step for call setup and a media stream step, which is an actual data transmission / reception process, media reception information contained in a session layer that cannot be converted by NAT is authorized before the media stream step, that is, at the beginning of the signaling step. By setting the IP address, NAT-Traversal can be solved.

The embodiments of the present invention described above are not implemented only through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Implementation may be easily implemented by those skilled in the art from the description of the above-described embodiments.

The scope of the present invention is not limited to the above-described embodiments, but various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims are also within the scope of the present invention.

By the above-described configuration, the problem of NAT-Traversal for a protocol in which call setup and actual data transmission and reception are separated using an existing NAT without greatly requiring a change to the conventional STUN protocol itself is solved.

In addition, since the STUN protocol is based on the server-client, but implements the STUN-Client role performed by the terminal on the network node, it minimizes the burden on the terminal and does not require any changes or additions to the existing terminal. Do.

Claims (15)

In a system for providing interworking using a network address translation (NAT) between a local network using private IP and a global network using public IP, A first server located outside the NAT and providing public IP binding information for the private IP passing through the NAT; And Host information for media reception is extracted from a packet payload of a call connection request received from a terminal assigned to the private IP address and located in the local network. A second server that acquires host information bound with a packet and applies it to the packet payload of the call connection request and transmits it to the called terminal Interworking providing system comprising a. The method of claim 1, The second server, A first module for extracting the host information from the payload of the call connection request packet and replacing the header information for the public IP binding request with the extracted private IP type host information; The public IP binding request including the header information changed by the first module and the response address set to the IP address of the second server is transmitted to the first server, and the public IP binding response is received to the first server. A second module for performing a client operation of a public IP binding for the public; And A third module for acquiring host information converted from the public IP binding response to public IP and changing host information of the packet payload Interworking providing system comprising a. The method of claim 2, The first module, A header information setting unit which sets an IP address of the host information as a source IP address of the header information and sets a port of the host information as a source port of the header information; And A header checksum calculator for recalculating a checksum of the header information by reflecting a value set by the header information setting unit Interworking providing system comprising a. The method of claim 2, The second server, A fourth module for performing a proxy function of the call connection request packet Linkage providing system further comprising. The method according to any one of claims 2 to 4, The second server, A fourth module for determining whether IP masquerading operation of the first module is performed according to whether a destination network specified in a header of the call connection request packet is identical to a source network; Linkage providing system further comprising. The method according to any one of claims 2 to 4, The first server, A first module configured to store setting information for a public IP binding operation in association with the second server; And A second module for checking a response address in the received public IP binding request received according to the configuration information and using the same, putting public IP binding information of the header information in a public IP binding response to the second server; Interworking providing system comprising a. The method of claim 1, The local network and the global network, Interworking providing system, characterized in that the interworking by the SIP (Session Initiation Protocol) based communication protocol. A gateway device including a server providing binding information of a public IP and providing interworking using a NAT between a global network using a public IP and a local network using a private IP, Configure a node of the local network, IP masquerading, which extracts host information for media reception from a payload of a call connection request packet, and replaces header information for requesting binding information of the public IP with host information of the extracted private IP type. module; A public IP binding client module for requesting the public IP binding including the header information changed by the IP masquerading module and a response address set to the IP address of the second server to receive a public IP binding response; And An application layer gateway module for acquiring host information converted from the public IP binding response to the public IP and changing the host information of the packet payload Gateway device comprising a. A server that includes a gateway device that performs client functions for public IP binding and is connected to the outside of NAT located at the boundary between a local network using private IP and a global network using public IP, A first module that stores setting information for performing a public IP binding operation in association with the gateway device; And In the public IP binding request received from the gateway device according to the configuration information, the header information extracted through the NAT and converted into the public IP address is extracted, and the response address is checked to display the extracted information using the response address. A second module for transmitting a public IP binding response to the gateway device Server containing. In a method of providing interworking using a network address translation (NAT) between a local network using a private IP and a global network using a public IP, (a) extracting, by the local network, host information for receiving a media set to a private IP from a packet payload of a call connection request received from a terminal in the local network; (b) Substituting the header information with the extracted host information to bind the public IP Transmitting a call; (c) receiving a binding response of a public IP including header information converted into a public IP by the NAT; And (d) the public IP in the header information included in the binding response of the public IP Acquiring the host information bound by the MAP, applying the same to the call connection request packet, and transmitting the same to the called terminal; Linkage providing method comprising a. The method of claim 10, In step (a), Checking a destination of a packet header of the call connection request to determine whether a network of the called terminal is the same as a network of the calling terminal; As a result of the check, the network of the called terminal is connected to the network of the calling terminal. Forwarding a packet of the call connection request to the called terminal when the same value; And Extracting the host information from the packet payload of the call connection request when the network of the called terminal is an external network of the calling terminal; Linkage providing method comprising a. The method of claim 10, In step (b), Extracting a source IP address from the media reception information and setting it as a source IP address of IP header information of the public IP binding request; Extracting a source port from the media reception address information and setting the source port as a source port of UDP (User Datagram Protocol) header information of the public IP binding request; And Recalculating a checksum of the IP header information by reflecting the set IP address value Linkage providing method comprising a. The method of claim 12, In step (b), Recalculating the checksum of the UDP header information by reflecting the set source port value Linkage providing method further comprising. The method according to any one of claims 10 to 13, And a protocol in which a signaling process for call setup and a media session process for data transmission and reception are separated and a negotiation information of the media session process is included in a packet payload. In a method of providing interworking using a network address translation (NAT) between a local network using a private IP and a global network using a public IP, Extracting, by the local network, media reception information set to the private IP included in the SDP message of the INVITE message when performing SIP (Seesion Initiation Protocol) signaling; Replacing a header of a STUN (Simple Traversal under UDP through NAT) binding request message for obtaining public IP binding information for the private IP of the media reception information with the extracted media reception information; Transmitting the stun binding request message and receiving a stun binding response message including header information that is converted to a public IP through NAT; And Acquiring public IP information of the substituted media reception information from the header information converted into the public IP and changing the media reception information of the INVITE message to the obtained information; Linkage providing method comprising a.

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