KR20010088233A - Application-based interworking system and method for interworking between networks using different protocol versions - Google Patents

Abstract

PURPOSE: An application-based interlocking system using protocols of an inter-different version and a method thereof are provided to maintain the compatibility with a conventional system and offer an interlocking service by interlocking a communication network using an inter-different version in an application layer. CONSTITUTION: A parser(330) extracts a destination URL(Universal Resource Locator) from the first request packet. An address converting unit(340) performs a lookup of an IPv4(Internet Protocol version 4) or IPv6 Internet address corresponding to the destination URL transmitted from the parser(330) through a name server. Service requesting units(350a,350b) compose the second request packet having the Internet address transmitted from the address converting unit(340) as the destination address, and transmit the second request packet to the second communication network through the second processing unit. Service providing units(360a,360b) recompose the second response packet corresponding to the second request packet as the first response packet suitable for the first lower communication protocol and transmit the first response packet to the first communication network through the first processing unit.

Description

Application-based interworking system and method for interworking between networks using different protocol versions}

The present invention relates to a method of interworking communication networks using different versions of a protocol, and more particularly, to a method of interworking an IPv4 network and an IPv6 network at an application layer.

With the development of the World Wide Web (WWW) technology, the number of Internet users is increasing rapidly, and various business models through the Internet, for example, electronic commerce systems, are being developed. In addition, extensive research is being conducted on the technology related to communication networks to provide the optimal Internet services to Internet users. In particular, active researches are being conducted on technologies related to the high speed of the Internet, for example, Asynchronous Transfer Mode (ATM). have.

On the other hand, as the number of Internet users is rapidly increasing, active researches on next-generation Internet protocols having a 128-bit addressing system are in progress to solve the problem of exhaustion of 32-bit Internet address (IP address). The Internet Protocol (IP) currently in use is version 4 (ie, IPv4) and the next generation Internet Protocol (IPng) is collectively referred to as version 6 (ie, IPv6). IPv6 is designed not only to extend the Internet address, but also to simplify the common header format to reduce bandwidth costs and processing costs of common headers. In addition, IPv6 is designed to be efficiently applied to the real-time processing of multimedia data by introducing the concept of a flow label (block label), it is expected to provide a higher level of service than IPv4. In addition, IPv6 provides enhanced security through authentication, data integrity, and data confidentiality.

However, it is not easy to immediately replace the currently used IPv4 based internet communication network (hereinafter referred to as IPv4 network) with the IPv6 based internet communication network (hereinafter referred to as IPv6 network). Because the Internet is so widespread, not only is it not easy to replace the communication protocol used in the Internet at once, but various conventional Internet services must be continuously provided to Internet users regardless of the type of network. Because. Therefore, assuming the gradual evolution of the network from IPv4 network to IPv6 network, it is necessary to interwork between IPv4 network and IPv6 network, and in the process of interworking between IPv4 network and IPv6 network, a conventional IPv4 host (ie computer system) ) And maintaining compatibility with routers / gateways are important.

The conventional interworking scheme between the IPv4 network and the IPv6 network can be roughly classified into three types. The first method is that a host of IPv6 has two protocol stacks, namely, both protocol stacks of IPv4 and IPv6. In other words, an IPv6 host uses an IPv4 packet to interact with an IPv4 host, and another IPv6 host interacts with an IPv6 packet by using an IPv6 packet. It is possible to gradually exchange the network. The second method is to transmit an IPv6 packet through an IPv4 network by encapsulating an IPv6 header into an IPv4 header through a tunneling technique. The third method is to perform header translation between an IPv4 header and an IPv6 header at an IPv6 host or router. Here, header translation includes Internet address translation and protocol translation.

Such a conventional interworking technique between the IPv4 network and the IPv6 network can be implemented in various combinations, but the interworking between the IPv4 network and the IPv6 network generated in the routing process is performed at the IP layer. Since the IP layer of the communication protocol stack is generally implemented in an operating system kernel, a conventional interworking method between an IPv4 network and an IPv6 network has a problem of directly modifying an operating system. Such direct modification of the operating system may not only cause compatibility problems between systems, but also incur a large amount of time and cost during implementation and testing.

The technical problem to be solved by the present invention is to solve the above problems, by transparently interworking a communication network using different versions of the protocol to the Internet user at the application layer, without modifying the operating system kernel and the conventional system An application-based interworking system and method capable of maintaining compatibility are provided.

1 schematically shows an example of a network configuration to which an embodiment of the present invention is applied.

FIG. 2 schematically illustrates an example of a communication protocol stack included in the translation proxy (application-based interworking system) in FIG. 1.

FIG. 3 schematically illustrates the internal structure of the PTM in FIG. 2.

4 is a flowchart illustrating a method for interworking a communication network using different versions of a protocol based on an application according to an embodiment of the present invention.

In order to solve the above technical problem, an application-based interworking system according to an aspect of the present invention is a system for interworking a first communication network and a second communication network using different versions of the protocol, through the first communication network A first processing unit of a first lower communication protocol for operating a link, a network, and a transport layer used for packet transmission and reception; A second processing unit of a second lower communication protocol having a different version from the first lower communication protocol used for transmitting and receiving a packet through the second communication network; And an interworking unit for interworking the first lower communication protocol and the second lower communication protocol in an application layer, wherein the interworking unit receives a first request packet received through the first communication network and transmitted through the first processing unit. Converting the second request packet suitable for the second lower communication protocol into the second communication network through the second processing unit, received through the second communication network, and transmitted through the second processing unit; The second response packet, which is a response to the request packet, is reconfigured into a first response packet suitable for the first lower communication protocol, and is transmitted to the first communication network through the first processing unit.

Further, if the version of the Internet layer protocol of the first lower communication protocol is IPv4, the version of the Internet layer protocol of the second lower communication protocol is IPv6, and if the Internet layer protocol of the first lower communication protocol is version IPv6, The version of the Internet layer protocol of the second lower communication protocol is preferably IPv4.

The interworking unit may further include a proxy function that temporarily stores the contents of the second response packet in a storage medium and searches the storage medium first for a response to the first request packet. .

The linkage unit may include a parser configured to extract a destination URL from the first request packet; An address translator for looking up an IPv4 or IPv6 Internet address corresponding to the destination URL delivered from the parser through a domain name server; A service request unit for constructing the second request packet having an Internet address delivered from the address conversion unit as a destination address, and transmitting the second request packet to the second communication network through the second processing unit; And a service providing unit configured to reconfigure the second response packet, which is a response to the second request packet, into the first response packet suitable for the first lower communication protocol, and to transmit the second response packet to the first communication network through the first processing unit. This is preferred.

In order to solve the other technical problem, the application-based interworking method according to an aspect of the present invention is a first communication network using a first lower communication protocol and the first using a different version of the protocol and the first lower communication protocol 2) A method of interworking a communication network, comprising: (a) receiving a first request packet according to the first lower communication protocol through the first communication network; (b) converting the first request packet received in step (a) into a second request packet suitable for the second lower communication protocol at the application layer; And (c) transmitting the second request packet through the second communication network.

In addition, in the step (c), the second request packet transmitted through the second communication network may pass through the first communication network using the first lower communication protocol using a tunneling technique.

An application-based interworking method according to another aspect of the present invention is a method for interworking a first communication network using a first lower communication protocol and a second communication network using different versions of protocols with the first lower communication protocol. (a) receiving a first request packet through the first communication network; (b) converting the first request packet received in step (a) into a second request packet suitable for the second lower communication protocol at the application layer; (c) transmitting the second request packet through the second communication network; (d) receiving a second response packet which is a response to the second request packet through the second communication network; (e) reconstructing the second response packet received in step (d) into a first response packet suitable for the first lower communication protocol at the application layer; And (f) transmitting the first response packet through the first communication network.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the preferred embodiment of the present invention. 1 schematically shows an example of a network configuration to which an embodiment of the present invention is applied.

The present invention provides a PTM (Proxy-based Translation Mechanism / Machine / Module) as a method of interworking an IPv4 host and a router with an IPv6 host and a router while maintaining compatibility with the IPv4 host and the router. PTM utilizes the existing proxy mechanism to provide an application-based interworking mechanism that allows IPv4 host users to access the IPv6 host and receive Internet services through IPv4 applications, and interworking IPv4 and IPv6 networks at the application layer. It is one solution.

Here, the proxy is a temporary storage of information that the user has ever accessed over the Internet in a storage medium such as a hard disk, so that the hard disk acts as a cache storage device of the computer, when the user requests an Internet service. It is a technique to search the information stored in the hard disk primarily. If the information requested by the user is on the hard disk, the information can be provided to the user without receiving the data from the remote place through the communication network, thereby providing a faster response. However, if the information requested by the user has been changed on the remote host, the information on one disk will be incorrect. Therefore, when a user request occurs, the information is not retrieved from the hard disk and passed on to the other host. After checking whether the information has not changed, the contents of the hard disk will be responded to the user.

However, although the present invention describes an example of a method for interworking an IPv4 network and an IPv6 network in an application layer, the present invention will be described based on a proxy server, but the present invention is not limited to a proxy server. Those of ordinary skill in the art will understand. For example, the present invention may be implemented in a firewall system or the like to provide an interworking mechanism between an IPv4 network and an IPv6 network in an application layer.

For convenience of description, FIG. 1 shows a host C4 110 existing in an IPv4 network, two IPv6 networks 100a and 100b formed in the middle of an entire IPv4 network, and a host A6 existing in a first IPv6 network 100a. 120 and host B6 130 present in second IPv6 network 100b are shown, which are mediated by translation proxies 150a and 150b, which are application-based interworking systems in accordance with an embodiment of the present invention. In addition, it is assumed that communication between two IPv6 networks 100a and 100b is performed by a tunneling technique between R1 and R2 routers having an IPv4 / IPv6 dual protocol stack.

Here, tunneling is a technique for transmitting data between communication networks using different communication protocols, and refers to a technique for allowing one network to transmit data using a connection of another network. In other words, data packets delivered to a communication network are expressed using different communication protocols and then transmitted as if they pass through different areas through a tunnel. In FIG. 1, an IPv6 packet is encapsulated into an IPv4 packet and transmitted.

For the interworking service according to the embodiment of the present invention, the user should set the proxy server as the conversion proxy 150a or 150b shown in FIG. FIG. 1 shows that P1 150a is set as the proxy server of A6 120 and P2 150b is set as the proxy server of C4 110 and B6 130. The internal structure and operation of the conversion proxy 150a and 150b according to an embodiment of the present invention will be described first, and then a specific method of communicating between C4 110 and A6 120 or B6 130 will be described. do.

FIG. 2 schematically illustrates an example of a communication protocol stack included in the translation proxies 150a and 150b in FIG. 1. As shown in FIG. 2, the translation proxy is equipped with IPv4 protocol stacks 210a, 220a, 230a and IPv6 protocol stacks 210b, 220b, 230b at the same time, and provides an application layer 240 for communication between IPv4 and IPv6 networks. Relay or mediate).

Here, the IPv4 protocol stack, which is a lower communication protocol used for accessing an IPv4 network, and the IPv6 protocol stack, which is a lower communication protocol used for accessing an IPv6 network, are different in the versions of the Internet protocols 220a and 220b for the network layer. have. That is, the IPv4 protocol stack uses IPv4, and the IPv6 protocol stack uses IPv6. Of course, different link layer protocols may be used for the subnets 210a and 210b in the link layer according to the type of the subnet used for the link connection. TCP (Transmission Control Protocol) 230a, 230b is a representative transport layer protocol used in the Internet. In addition, the PTM 240 according to the embodiment of the present invention, which is an interworking unit for interworking an IPv4 network and an IPv6 network, may be implemented using the same API (Application Program Interface) as the proxy service.

Suppose an IPv4 network user connects to an IPv6 network through his or her Internet application. First, the service request of the user is sent in the form of IPv4 packet to the translation proxy specified by the proxy server in the application, and the translation proxy analyzes the service request of the user and the DNS (Domain Name Service / System) to the IPv6 network to which the user wants to connect. ) Lookup obtains the Internet address of the IPv6 host, converts the IPv4 packet into the IPv6 packet, and sends the user's service request to the IPv6 host. At this time, an IPv4 connection (eg, socket / v4) is established between the user and the translation proxy, and an IPv6 connection (eg, socket / v6) is established between the translation proxy and the IPv6 host.

Here, DNS refers to a distributed naming system that translates or maps a domain name of a host to an IP address. The Internet layer used in the Internet and the applications above it recognize only IP addresses, for example, 210.105.79.103, which is easy to interpret from the machine's point of view but difficult to remember. With this in mind, the technique of translating human-friendly domain names into IP addresses was introduced.

In addition, the service request of the user applied to the embodiment of the present invention is an HTTP service request, but the present invention is not limited to the HTTP service. For example, it will be understood by those skilled in the art that the present invention can be applied to the ftp service in the same manner.

Subsequently, an internal structure of the PTM 240 operating the application layer will be described in detail with reference to FIG. 3. FIG. 3 schematically illustrates the internal structure of the PTM 240 in FIG. 2. As shown in FIG. 3, the PTM 240 includes a data receiver 320, a parser 330, an address translator 340, a service requester 350a and 350b, and a service provider 360a and 360b. It includes.

The data receiver 320 is a module that receives a service request from a client and a response from a server through a lower communication protocol. In FIG. 3, it is assumed that a socket interface is used for communication with a user or a server, and data is transmitted through socket / v4 310a in the case of IPv4 network and socket / v6 310b in the case of IPv6 network. It shows that it is received. The data receiver 320 receives a user's service request or a server's response received through the IPv4 / IPv6 sockets 310a and 310b, stores the result in a buffer, and transmits the same to the parser 330. In this case, a separate thread is preferably allocated to each service request to improve performance.

The parser 330 analyzes the service request of the user transmitted from the data receiver 320, extracts a URL (Universal Resource Locator) of a destination that the user wants to access, and delivers it to the address translator 340. In addition, the parser 330 manages information on the current connection (ie, connection information about the origin and destination) in a mapping table, so that a response from a server later can be returned to the corresponding client. It is desirable to. However, the mapping table management function may be performed by the address change unit 340. When the parser 330 receives the response from the server, the parser 330 analyzes the response and supports the service provider 360a or 360b to obtain the client information that performs the request by referring to the mapping table.

The address conversion unit 340 performs a function of obtaining an Internet address corresponding to the destination URL delivered from the parser 330. To this end, the address translator 340 requests a name service from a DNS server and receives an IPv4 or IPv6 Internet address corresponding to a destination URL (DNS lookup function). If the DNS server does not support the IPv4 / IPv6 name service at the same time, request the name service from the DNS server for IPv4 and the DNS server for IPv6. As described above, the mapping table management function may be performed by the address translation unit 340.

The service request unit 350a or 350b converts or reconfigures the service request of the IPv4 network received from the user into a service request for the IPv6 network and sends the IPv6 service request to the Internet address obtained through the DNS lookup by the address conversion unit 340. Transmit via socket / v6 310b. If the service request is received from the user through the IPv6 network, the service request is converted into a service request for the IPv4 network, and the IPv4 service request is transmitted to the destination through the socket / v4 310a. Therefore, although the service request unit 350a for IPv4 and the service request unit 350b for IPv6 are separately illustrated in FIG. 3, they may be configured as integrated modules.

The service providers 360a and 360b receive the client information that performs the request with reference to the mapping table with respect to the service response received from the data receiver 320 and transmitted through the parser 330, and then obtains new information. This module generates and reconfigures the response and sends it to the client. Here, when receiving an IPv6 service response, it reconfigures to an IPv4 response, and when receiving an IPv4 service response, it reconfigures to an IPv6 response.

For example, when the service request is made from the IPv4 network to the IPv6 network, the IPv4 service request received through the socket / v4 310a using the IPv4 sub-communication protocol may be received by the data receiver 320. Via the parser 330 is transmitted to the address translation unit 340. The IPv6 DNS lookup is performed by the address translation unit 340, reconfigured into an IPv6 service request through the service request unit 350b, and transmitted to the IPv6 network through the socket / v6 310b. When the IPv6 service response from the IPv6 network is received through the socket / v6 310b, the service provider 360a is reconfigured into the IPv4 service response through the parser 330 and returned to the client through the socket / v4 310a. do.

In the case of a service request from the IPv6 network to the IPv4 network, the IPv6 service request is received through the socket / v6 310b and transmitted to the address translator 340 via the data receiver 320 and the parser 330. Here, after the IPv4 DNS lookup is performed, the service request unit 350a is reconfigured into an IPv4 service request and transmitted to the IPv4 network through the socket / v4 310a. The IPv4 service response from the IPv4 network is received via the socket / v4 310a, reconstructed by the service provider 360b into an IPv6 service response via the parser 330, and returned to the client via the socket / v6 310b. do.

Subsequently, an application-based interworking method according to an embodiment of the present invention will be described in detail using a socket interface as an example. 4 is a flowchart illustrating a method for interworking a communication network using different versions of a protocol based on an application according to an embodiment of the present invention.

First, the PTM initializes the socket (step 410) and waits for a service request from the client (step 415). The PTM preferably establishes both IPv4 and IPv6 sockets in order to receive service requests from both IPv4 and IPv6 networks.

When a service request is received from the user (step 420), a destination URL is extracted from the corresponding service request packet (step 425), and a DNS lookup is performed (step 430).

As a result of the DNS lookup, it is determined whether the Internet address corresponding to the destination URL is an IPv4 address or an IPv6 address (step 440).

If it is an IPv6 Internet address, a new IPv6 socket is initialized (step 450b), and the service request (assuming IPv4 service request) received in step 420 is reconfigured into a new IPv6 service request (step 455b). Request the IPv6 service through (step 460b).

Next, upon receiving an IPv6 service response to the service request from the IPv6 server (step 465b), it reconfigures it to an IPv4 service response (step 470b) and returns to the client in response to the service request received in step 420 ( Step 475b).

If it is an IPv4 Internet address, a new IPv4 socket is initialized (step 450a), and the service request (assuming IPv6 service request) received in step 420 is reconfigured into a new IPv4 service request (step 455a). Request the IPv4 service through (step 460a). Next, upon receiving an IPv4 service response for the service request from the IPv4 server (step 465a), it reconfigures it to an IPv6 service response (step 470a) and returns to the client in response to the service request received in step 420 ( Step 475a).

Based on the configuration and operation of the PTM according to an embodiment of the present invention so far, a specific method of communicating between C4 110 and A6 120 or B6 130 in the network configuration of FIG. The focus will be on the transmission side. The response to the HTTP service request is the reverse of the service request transmission (but the difference is that the DNS lookup process is not performed). Here, as shown in FIG. 1, it is assumed that P1 150a is set as the proxy server of A6 120, and P2 150b is set as the proxy server of C4 110 and B6 130.

First, a process of transmitting an HTTP service request from C4 110 to B6 130 will be described.

C4 110 transmits the IPv4 packet including the domain name information of B6 130 in the HTTP header field to its proxy server P2 150b. Here, the origin address of the IPv4 packet is set to C4 110, and the destination address is set to P2 150b.

P2 150b performs a DNS lookup of B6 130 to obtain the IPv6 Internet address of B6 130, converts the IPv4 packet into an IPv6 packet, and transmits the IPv6 packet to B6 130 as the final destination. Here, the origin address of the IPv6 packet is set to P2 150b and the destination address is set to B6 130.

The IPv6 packet transmitted from P2 150b is received by B6 130, which is the final destination, through routing of the IPv6 network.

Next, a process of transmitting a service request from C4 110 to A6 120 will be described.

The C4 110 transmits an IPv4 packet including the domain name information of the A6 120 in the HTTP header field to its proxy server P2 150b.

P2 150b performs a DNS lookup of A6 120 to obtain the IPv6 Internet address of A6 120, converts the IPv4 packet into an IPv6 packet, and sends the IPv6 packet to A6 130, the final destination.

The IPv6 packet transmitted from P2 150b is delivered to R2 via routing of the IPv6 network, and R2 encapsulates it into an IPv4 packet and transmits it to R1 (IPv6-over-IPv4 tunneling).

R1 decapsulates the received IPv4 packet, extracts the IPv6 packet, and then transmits the IPv6 packet to the A6 120 as the final destination through IPv6 routing.

Finally, a process in which a service request is transmitted from an IPv6 host A6 120 to an IPv4 server C4 110 is described.

A6 120 transmits the IPv6 packet including the domain name information of C4 110 in the HTTP header field to P1 150a, which is its proxy server.

P1 150a performs a DNS lookup of C4110 to obtain an IPv4 Internet address of C4110, converts an IPv6 packet into an IPv4 packet, and transmits the IPv4 packet to C4110, the final destination.

The IPv4 packet transmitted from P1 150a is received by C4 110, which is the final destination through routing of the IPv4 network.

Method embodiments of the present invention may be written as a program executable in a computer system. In addition, the program can be read from a computer readable recording medium having recorded such a program and executed in a general-purpose digital computer system. Such recording media include magnetic storage media (e.g., ROM, floppy disk, hard disk, etc.), optical reading media (e.g., CD-ROM, DVD, etc.) and carrier waves (e.g., transmission over the Internet). Media is included.

So far, the present invention has been described with reference to the preferred embodiment (s). Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

According to the present invention, by interworking a communication network using different versions of the protocol at the application layer, it is possible to provide an interworking service while maintaining compatibility with a conventional system without modifying an operating system kernel. In addition, by providing the interworking service transparently to the user by interworking in the application layer, the user can receive the desired Internet service regardless of the version of the communication protocol.

Claims (11)

In a system for interworking a first communication network and a second communication network using different versions of the protocol, A first processing unit of a first lower communication protocol operating a link, a network, and a transport layer used to transmit and receive a packet through the first communication network; A second processing unit of a second lower communication protocol having a different version from the first lower communication protocol used for transmitting and receiving a packet through the second communication network; And An interworking unit for interworking the first lower communication protocol and the second lower communication protocol at an application layer; The interworking unit is received through the first communication network, converts a first request packet transmitted through the first processing unit into a second request packet suitable for the second lower communication protocol, and then through the second processing unit, the second communication network. And a second response packet, which is a response to the second request packet, received through the second communication network and transmitted through the second processing unit, to a first response packet suitable for the first lower communication protocol. Application based interworking system, characterized in that for transmitting to the first communication network through the first processing unit. The method of claim 1, If the version of the internet layer protocol of the first lower communication protocol is IPv4, the version of the internet layer protocol of the second lower communication protocol is IPv6, If the internet layer protocol of the first lower communication protocol is IPv6, the version of the internet layer protocol of the second lower communication protocol is IPv4. The method of claim 1, wherein the linkage unit, And a proxy function for temporarily storing the contents of the second response packet in a storage medium, and first searching the storage medium for a response to the first request packet thereafter. . The method of claim 1, wherein the linkage unit, And extracting a destination URL from the first request packet to look up an IPv4 or IPv6 Internet address corresponding to the destination URL through a domain name server. The method of claim 4, wherein the linkage unit, A parser configured to extract a destination URL from the first request packet; An address translator for looking up an IPv4 or IPv6 Internet address corresponding to the destination URL delivered from the parser through a domain name server; A service request unit for constructing the second request packet having an Internet address delivered from the address conversion unit as a destination address, and transmitting the second request packet to the second communication network through the second processing unit; And And a service providing unit configured to reconfigure the second response packet, which is a response to the second request packet, into the first response packet suitable for the first lower communication protocol, and to transmit the second response packet to the first communication network through the first processing unit. Application based interworking system characterized by. In the method of interworking a first communication network using a first lower communication protocol and a second communication network using a different version of the protocol and the first lower communication protocol, (a) receiving a first request packet according to the first lower communication protocol through the first communication network; (b) converting the first request packet received in step (a) into a second request packet suitable for the second lower communication protocol at the application layer; And and (c) transmitting the second request packet through the second communication network. The method of claim 6, If the version of the internet layer protocol of the first lower communication protocol is IPv4, the version of the internet layer protocol of the second lower communication protocol is IPv6, If the version of the internet layer protocol of the first lower communication protocol is IPv6, the version of the internet layer protocol of the second lower communication protocol is IPv4. The method of claim 6, The second request packet transmitted through the second communication network in the step (c) is via the first communication network using the first lower communication protocol using a tunneling scheme. According to claim 6, wherein step (b), And looking up an IPv4 or IPv6 Internet address corresponding to a destination URL of the first request packet through a domain name server. In the method of interworking a first communication network using a first lower communication protocol and a second communication network using a different version of the protocol and the first lower communication protocol, (a) receiving a first request packet through the first communication network; (b) converting the first request packet received in step (a) into a second request packet suitable for the second lower communication protocol at the application layer; (c) transmitting the second request packet through the second communication network; (d) receiving a second response packet which is a response to the second request packet through the second communication network; (e) reconstructing the second response packet received in step (d) into a first response packet suitable for the first lower communication protocol at the application layer; And and (f) transmitting the first response packet through the first communication network. The method of claim 10, If the version of the internet layer protocol of the first lower communication protocol is IPv4, the version of the internet layer protocol of the second lower communication protocol is IPv6, If the version of the Internet layer protocol of the first lower communication protocol is IPv6, the version of the Internet layer protocol of the second lower communication protocol is IPv4.