JP2009118173A - Gateway device, network system, communication method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transfer data transmitted from an information appliance communicable only in a closed network also to other closed networks. <P>SOLUTION: A gateway device performs encapsulation to local data, by which communication to an open network becomes possible, receives encapsulated data transmitted from a first other gateway device connected to the open network, releases encapsulation of the encapsulated data to extract the local data, transmits the local data extracted from the encapsulated data into a closed network in which a proxy device itself exists, stores transfer destination information which is the information specifying a second other gateway device connected to the open network, and transmits the encapsulated data received from the first other gateway device to the second other gateway device specified by the transfer destination information. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gateway device, a network system, a communication method, and a program.

Various digital data including photographs, sounds, and videos are shared among a plurality of devices connected to a network. For example, Patent Document 1 discloses a mechanism for downloading a moving image file from a device in a P2P system and reading the file by a so-called file sharing P2P (Peer to Peer) application. In addition, content sharing in a network that is not premised on connection with another network (referred to as a closed network or a private network, for example, a home network in which the communication range is limited to the same home is an example). As an intended standard, there is a DLNA (Digital Living Network Alliance: registered trademark) guideline (see Non-Patent Document 1). For example, content reproduction by streaming can be performed between devices compliant with the DLNA guidelines in the home network.
JP 2007-87185 A Digital Living Network Alliance Home Networked Device Interoperability Guidelines Version: 1.0, [online], June 2004, Digital Network Alliance, Internet <URL: http: //www.dlna.prg>

  When a plurality of devices holding content are connected to the same home network, the devices can share the content by complying with the DLNA guidelines. However, content cannot be shared between a DNLA guideline compliant device connected to a home network and a DLNA guideline compliant device connected to a home network different from the home network.

  On the other hand, if each DLNA guideline compliant device implements a P2P application, content can be shared between different home networks. However, in order to do so, it is necessary to mount a P2P application on all of the DLNA guideline compliant devices.

  The present invention has been made in view of such a background, and makes it possible to transfer data transmitted from an information home appliance that can communicate only within a closed network to another closed network. For the purpose.

  A main invention of the present invention for solving the above-mentioned problems is a gateway device capable of communicating with an open network and capable of transmitting / receiving information to / from an information home appliance existing in the closed network. And an encapsulation processing unit that performs encapsulation that enables communication to the open network into local data that is data that can be communicated with the open network and that cannot be communicated to the open network. A remote receiver for receiving the encapsulated data transmitted from the first other gateway device connected to the network; and decapsulating the encapsulated data to extract the local data A decapsulation processing unit and the local data extracted from the encapsulated data; Transfer destination information storing transfer destination information that is information specifying the local communication unit that transmits to the closed network where the proxy device itself exists and the second other gateway device connected to the opened network A storage unit; and a transfer processing unit that transmits the encapsulated data received from the first other gateway device to the second other gateway device specified by the transfer destination information. And

  ADVANTAGE OF THE INVENTION According to this invention, the data sent from the information household appliance which can communicate only in the closed network can be transferred also to another closed network.

  Hereinafter, a network system 1 according to an embodiment of the present invention will be described.

(System configuration)
FIG. 1 is a diagram illustrating a configuration example of a network system 1 according to the present embodiment.
The network configuration in the network system 1 of the present embodiment includes a plurality of home networks 2.

  The home network 2 is a closed network. A closed network is a network that is not logically (or physically) directly connected to an external network and cannot directly communicate with the external network, and is also called a private network. . A closed network is realized by, for example, assigning a private address defined in TCP / IP to each device. In the network system 1 of this embodiment, as will be described later, the gateway device 5 converts data to enable communication between the home networks 2 that are closed networks.

  The home network 2 includes a home router 4, a gateway device 5, and two information home appliances (hereinafter referred to as DLNA-compliant devices 6) compliant with DLNA guidelines. Each of these is connected to a LAN (Local Area Network) 3 and can communicate with each other.

  The home router 4 has an address translation function such as NAT (Network Address Translator), and is configured to transfer data to a gateway device 5 when data is received for a specific port number.

  The gateway device 5 is an example of the Internet (an open network via the home router 4. The open network is physically and logically connected to an external network and directly connected to the external network. And can communicate with a gateway device (other gateway device) 5 of another home network 2. The gateway device 5 is, for example, a portable terminal such as a television having a communication function, a hard disk recorder, a personal computer, a mobile player capable of reproducing video / music, or a mobile phone. In addition, the gateway device 5 may be implemented with software compliant with the DLNA guidelines.

  The DLNA-compliant device 6 can perform communication using the DLNA protocol. The DLNA-compliant device 6 is, for example, a hard disk recorder having a communication function, a television, a printer, a digital camera, a digital video recorder, a portable player such as a mobile player or a mobile phone capable of reproducing video / music, a personal computer, etc. It is.

  The LAN 3 is constructed using, for example, a communication circuit such as Ethernet (registered trademark), a power line, wireless, or infrared.

  In the following description, data that can be communicated only in the home network 2 and cannot be communicated on the Internet is referred to as local data. In the present embodiment, the local data is various messages in a data format defined by DLNA. On the other hand, data that can be communicated on the Internet is called remote data. In this embodiment, remote data is generated by adding a header to local data.

FIG. 2 is a diagram illustrating a hardware configuration example of the gateway device according to the present embodiment.
The gateway device 5 includes a CPU 20 that controls the entire gateway device, a RAM (Random Access Memory) 21 and a ROM (Read Only Memory) 22 that store data and programs, and a network interface 23 that transmits and receives data to and from the LAN 3. The display control unit 24 performs control for displaying information on the connected monitor 26, and the hard disk 25 can record and delete data. Depending on the form of the gateway device 5, the display control unit 24 and the hard disk 25 can be omitted. The hard disk 25 may be another external storage device.

FIG. 3 is a diagram illustrating functional blocks of the gateway device 5 according to the present embodiment.
The gateway device 5 includes a communication unit 300, a transfer list unit 301, an encapsulation processing unit 302, a LAN protocol proxy unit 303, a decapsulation processing unit 304, a TTL management unit 305, and a group ID management unit 306. And a local transfer determination unit 307.

  The communication unit 300 transmits / receives data to / from the LAN 3 and communicates with each device connected to the LAN 3 in the home network 2. The communication unit 300 communicates with another home network 2 on the Internet via the home router 4.

  The transfer list unit 301 communicates with the other gateway device 5, and the location identifier information of the home router 4 of the home network 2 to which the other gateway 5 belongs (in this embodiment, the IP address and the port number). .) Is memorized. When a packet is transmitted with the location identifier information stored in the transfer list unit 301 as a destination, the packet is transferred to another gateway device 5 of the home network 2 to which the home router 4 belongs. In the present embodiment, the transfer list unit 301 stores one piece of location identifier information, but a plurality of pieces of location identifier information may be stored depending on the configuration of the network system 1.

  The encapsulation processing unit 302 performs processing (hereinafter referred to as encapsulation) for converting the given data into a certain format used for a protocol defined in communication between the gateway devices 5. Specifically, the encapsulation processing unit 302 generates and adds a header including information (hereinafter referred to as type information) for determining whether the request is a request or a response to the given data. In addition, when the type information is a request, the encapsulation processing unit 302 is a transfer number limit (TTL: Time To Live) value in the gateway device 5, a group ID indicating a group to which the gateway device 5 belongs, and a transmission source. The location identifier information of the home router 4 for communicating with the gateway device 5 is also added to the header. Also, the encapsulation processing unit 302 refers to a TTL management unit 305 described later, and discards the given data when the TTL value is 0.

  When receiving the remote data from another gateway device 5 included in another home network 2, the decapsulation processing unit 304 decapsulates the remote data by decomposing the remote data into a header and a trailer.

  The intra-LAN protocol proxy unit 303 sends the remote data trailer released by the decapsulation processing unit 304 as local data to the LAN 3 according to the DLNA protocol.

  The TTL management unit 305 holds a value obtained by subtracting 1 from the TTL value included in the header extracted by the decapsulation unit 304. The TTL management unit 305 also holds an initial value of the TTL value. The TTL value held by the TTL management unit 305 and its initial value are referenced from the encapsulation processing unit 302.

  The group ID management unit 306 holds identification information (hereinafter referred to as a group ID) of a group to which the gateway device 5 belongs. The group ID to which the gateway device 5 belongs may not be set, and a plurality of group IDs may be set. The group ID is referred to by the encapsulation processing unit 302 and the local transfer determination unit 307 described later.

  The local transfer determination unit 307 compares the group ID included in the header extracted by the decapsulation processing unit 304 with the group ID managed by the group ID management unit 306, and determines whether or not the remote transfer determination unit 307 Decide whether to transfer data into the home network 2.

  Each of the functional units 300 to 307 is realized by a program stored in the hard disk 25 or the ROM 22 being expanded in the RAM 21 and executed by the CPU 20.

(System processing)
Next, communication according to the present embodiment will be described in detail. In the subsequent processing, communication between the gateway device 5 and the DLNA-compliant device 6 is communication via the LAN 3, and communication between the gateway devices 5 is via the home router 4 and the Internet. Communication.

  In the present embodiment, for the sake of simplicity of explanation, communication between the gateway device 5a, the gateway device 5c, the gateway device 5d, and the gateway device 5g will be described as an example. Of course, it is not limited.

  FIG. 4 is a sequence diagram illustrating an example of a flow of communication performed in the network system 1 of the present embodiment. In FIG. 4, the description about the home router 4 is omitted.

  In the example of FIG. 4, it is assumed that the gateway devices 5a, 5c, and 5g belong to the same group, and the gateway device 5d belongs to a different group. As an example, “87234” is stored in the group ID management unit 306 included in the gateway devices 5a, 5c, and 5g, and “87235” is stored in the group ID management unit 306 of the gateway device 5d. And

  First, the DLNA-compliant device 6a in the home network 2a performs local multicast transmission of a device search message (SSDP M-SEARCH; hereinafter referred to as a local request) to the LAN 3a. The gateway device 5a in the home network 2a receives the local request, performs local request processing in which the received local request is encapsulated and transferred to another home network 2 (S1: described later with reference to FIG. 5). ).

  The gateway device 5a transmits the remote data in which the local request is encapsulated to the gateway device 5c via the Internet. Specifically, the gateway device 5a transmits remote data to the home router 4c of the home network 2c by sending remote data with the location identifier information stored in the transfer list unit 301 as a destination, and transmits the remote data. The received home router 4c transfers the received remote data to the gateway device 5c belonging to the home network 2c, whereby the remote data is transmitted to the other gateway device 5c.

  The gateway device 5c that has received the remote data performs remote request processing (S2: described later with reference to FIG. 7). In step S2, the gateway device 5c decapsulates the received remote data, extracts a local request, and extracts the extracted local data from the appropriate DLNA-compliant device 6 connected to the LAN 3c in the home network 2c. Send a request. The gateway device 5c encapsulates the local request and transmits it to the gateway device 5d via the Internet.

  When the gateway device 5c receives a response to the local request transmitted to the DLNA-compliant device 6 connected to the LAN 3c of the home network 2c in step S2, the gateway device 5c performs local response processing (S3: see FIG. 8). And will be described later.) In step S3, the gateway device 5c generates remote data that encapsulates the local response received from the DLNA device 6c connected to the LAN 3c in the home network 2c, and transmits the generated remote data to the gateway device 5a.

  The gateway device 5d receives the remote data generated in step S2 transmitted from the gateway device 5c, and performs remote request processing (S2). In step S2, the gateway device 5d decapsulates the received remote data. However, since the group ID included in the header is different from the group ID stored in the group ID management unit 306, the gateway device 5d Instead of transmitting local data to the LAN 3d, the local request is encapsulated again and transmitted to the gateway device 5g via the Internet.

  When the gateway device 5g receives remote data, the gateway device 5g performs remote request processing (S2). In step S2, the gateway device 5g decapsulates the received encapsulated local request, extracts a trailer, and connects the extracted trailer as a local request to the LAN 3g in the home network 2g. To a DLNA-compliant device 6.

  When the gateway device 5g receives a response from the DLNA-compliant device 6 in response to the local request transmitted in step S2, the gateway device 5g performs local response processing (S3). In step S3, the gateway device 5g generates remote data encapsulating the response received from the DLNA device 6 connected to the LAN 3g in the home network 2g, and transmits the generated remote data to the gateway device 5a.

  When the gateway device 5a receives remote data encapsulating the response transmitted from the gateway device 5c and the gateway device 5g in step S3, the gateway device 5a performs remote response processing (S4: described later with reference to FIG. 9). In step S4, the gateway device 5 releases the received remote data from the DLNA-compliant device 6a connected to the LAN 3a in the home network 2a, extracts the trailer, and extracts the extracted trailer locally. Data is transmitted to the LAN 3a.

  Further, the gateway device 5a receives the remote data in which the response is encapsulated, whereby the gateway device 5 (gateway device 5c and gateway device 5g) in the home network 2 (home network 2c and home network 5g) to be communicated. ) To acquire the location identifier information of the home router 4 (home router 4c and home router 4g) for communication with the gateway device 5 in the home network 2 to be directly communicated, Remote data encapsulating requests and responses from the DLNA-compliant device 6 can be directly transmitted and received.

  Through the above communication processing, finally, the DLNA-compliant device 6a in the home network 2a can acquire desired content from the entire network system 1.

  Hereinafter, step S1 to step S4 in FIG. 4 will be described in detail. In addition, although the process which concerns mainly on communication between the gateway apparatus 5a and the gateway apparatus 5c is demonstrated here, the content of the process to perform is the same also with the other gateway apparatuses 5.

(Local request processing: S1)
FIG. 5 is a flowchart showing the flow of local request processing in step S1 of FIG.
The intra-LAN protocol proxy unit 303 of the gateway device 5a receives the local data transmitted from the DLNA-compliant device 6a via the communication unit 300 of the gateway device 5a (S101).

  The encapsulation processing unit 302 is a type information indicating that the local data received by the intra-LAN protocol proxy unit 303 is a request, an initial value of a TTL value managed by the TTL management unit 305, and a group ID management. Encapsulation is performed by generating remote data to which a header including the group ID managed by the unit 306 is added (S102).

  FIG. 6 is a diagram illustrating a configuration example of remote data generated by the encapsulation processing unit 302 in step S102. As shown in FIG. 6, remote data in which a local request is encapsulated includes a header 1001 and a trailer 1002. The header 1001 includes type information indicating a request, a group ID, and a TTL value. include. The trailer 1002 is a local request transmitted from the DLNA-compliant device 6a.

  The communication unit 300 acquires the location identifier information of the home router 4c for communicating with the gateway device 5c of the home network 2c from the transfer list unit 301, and uses the remote data generated by the encapsulation processing unit 302 as the location identifier information. Is sent to the Internet as a destination to transmit remote data to the gateway device 5c (S103).

(Remote request processing: S2)
FIG. 7 is a flowchart showing the flow of remote request processing in step S2 of FIG.
The decapsulation processing unit 304 of the gateway device 5c in the home network 2c receives the encapsulated remote data transmitted by the gateway device 5a via the communication unit 300 of the gateway device 5c, and receives the received remote data. The decapsulation processing is performed to analyze and extract the header and trailer from the remote data (S201).

  The local transfer determination unit 307 compares the group ID managed by the group ID management unit 306 with the group ID included in the header extracted by the decapsulation processing unit 304 (S202). If the group IDs match, the process proceeds to step S203. If the group IDs do not match, the process proceeds to step S204.

  When the group ID of the group ID management unit 306 matches the group ID of the header, the protocol proxy unit 303 in the gateway 5c uses the trailer extracted by the decapsulation processing unit 304 as the LAN 3c of the home network 2c. The local data is generated by appropriately rewriting it for transmission to the DLNA-compliant device 6 (proxy processing). The intra-LAN protocol proxy unit 303 transmits the rewritten local data to the LAN 3c via the communication unit 300 (S203). In the present embodiment, the communication unit 300 transmits local data to a predetermined multicast address, and transmits local data to the LAN 3c by multicast transmission.

  The TTL management unit 305 of the gateway device 5c calculates a TTL value by subtracting 1 from the TTL value included in the header extracted by the decapsulation processing unit 304, and passes it to the encapsulation processing unit 302 (S204).

  The encapsulation processing unit 302 of the gateway device 5c acquires the TTL value passed from the TTL management unit 305, and determines whether the TTL value is 0 or 1 (S205). When the TTL value is 0, the encapsulation processing unit 302 discards the stored data and ends the process. In addition, when the TTL value is 1 or more, the encapsulation processing unit 302 shifts the process to step S206.

  The encapsulation processing unit 302 of the gateway device 5c includes the group ID included in the header extracted by the decapsulation processing unit 304, the TTL value passed from the TTL management unit 305, and the home network 2a that is the remote data transmission source. The header including the location identifier information of the home router 4a for communicating with the gateway device 5a is added to the trailer extracted by the decapsulation processing unit 304 to generate remote data, thereby performing encapsulation (S206). ).

  The communication unit 300 of the gateway device 5c acquires the location identifier information of the home router 4d managed by the transfer list unit 301 for communicating with the gateway device 5d of the home network 2d, and is generated by the encapsulation processing unit 302 The obtained remote data is transmitted with the acquired position identifier information as the destination (S207).

(Local response processing: S3)
FIG. 8 is a flowchart showing the flow of local response processing in step S3 of FIG. In the local response process of FIG. 8, when the gateway device 5c of the home network 2c transmits local data to the LAN 3c of the home network 2c in step S203 of FIG. 7, the DLNA-compliant device 6c in the home network 2c This is executed when a predetermined message (hereinafter referred to as a local response) defined by the DLNA guidelines is transmitted to the gateway device 5c as a response to data.

  The intra-LAN protocol proxy unit 303 of the gateway device 5c receives the local response transmitted by the DLNA-compliant device 6c via the communication unit 300 (S301).

  The encapsulation processing unit 302 of the gateway device 5c generates remote data by adding a header including type information indicating that it is a response to the local response, and performs encapsulation (S302).

  The communication unit 300 of the gateway device 5c uses the home router 4a for communicating with the gateway device 5a in the home network 2a that is the transmission source in the header of the remote data received by the decapsulation processing unit 304 in step S201 in FIG. If the location identifier information is included, the location identifier information is the destination, and if the location identifier information is not included, the location identifier information indicating the source of the remote data received in step S201 Is transmitted to the remote data generated by the encapsulation processing unit 302 in step S302 (S303).

(Remote response processing: S4)
FIG. 9 is a flowchart showing the flow of the remote response process in step S4 of FIG. 9 is executed when the gateway device 5a of the home network 2a receives the remote data transmitted by the gateway device 5c of the home network 2c in step S303 of FIG.

  The decapsulation processing unit 304 of the gateway device 5a of the home network 2a receives remote data transmitted from the gateway device 5c of the home network 2c via the communication unit 300, and extracts a header and a trailer from the received remote data. The decapsulation process to extract is performed (S401).

  The in-LAN protocol proxy unit 303 of the gateway device 5a appropriately rewrites the trailer extracted by the decapsulation processing unit 304 to transmit to the DLNA-compliant device 6a in the LAN 3a of the home network 2a (proxy processing). The data is transmitted to the LAN 3a to which the gateway device 5a is connected via the communication unit 300 (S402).

  The other processes for directly communicating between the gateway device 5a connected to the home network 2a and the gateway device 5c in the other home network 2c to be communicated by the above processing from S1 to S4. Since the location identifier information of the home router 4c in the home network 2c can be known, the subsequent communication can be performed directly between the gateway device 5a and the gateway device 5c.

  As described above, communication according to the DLNA protocol can be performed and content can be shared between the DLNA-compliant device 6 in the home network 2a and the DLNA-compliant device 6 in another unknown home network 2.

  According to the network system 1 of the present embodiment, the gateway device 5 encapsulates the local data transmitted by the DLNA-compliant device 6 in the home network 2 according to the DLNA protocol to generate remote data, and the remote data is transmitted via the Internet. Can be transmitted to the gateway device 5 of the other home network 2, and in the other home network 2, the gateway device 5 can extract the local data from the received remote data and transmit it to the other home network 2. Therefore, local data sent from an information appliance that communicates in accordance with a protocol that is used in a closed network such as the home network 2 and cannot communicate with the open network is transferred to another closed network. can do. Therefore, it becomes possible to share content between information appliances belonging to different closed networks.

  In the network system 1 of the present embodiment, the gateway device 5 extracts local data from the remote data received from the first gateway device 5 and transmits it to the home network 2, and transmits the remote data to the second gateway. It can be transferred to the device 5. Therefore, content can be shared between the home networks 2 which are many closed networks.

  Therefore, for example, when the home network 2 is constructed in each of the three generation homes (for example, a parent home, a child home, and a grandson home), the photo data taken by the grandchild with the digital camera The gateway device 5 installed in the home network 2 of the home transfers to the gateway device 5 installed in the home network 2 of the child home, so that the television set installed in the home network 2 of the child home A personal computer, a printer, etc. can receive and output photo data sent from the grandchild's digital camera, and the remote data received by the child's home gateway apparatus 5 from the grandchild's home gateway apparatus 5 Is also transferred to the gateway device 5 of the parent home, and the TV and personal computer are also used in the home network 2 of the parent home. From a printer, it is possible to receive and output picture data sent from the grandchildren of the digital camera. That is, it becomes possible to share content among a plurality of homes.

  For example, when a P2P system is configured by a plurality of gateway devices 5 of the present invention, the DLNA-compliant device 6 in the home network 2 can participate in the P2P system without implementing a P2P application. . In general, in a P2P system, each device on which a P2P application is mounted is a minimum configuration unit. However, according to the network system 1 of the present embodiment, the home network 2 can be handled as the minimum configuration unit of the P2P system.

  Further, in the network system 1 of the present embodiment, when transferring the remote data, the gateway device 5 decreases the TTL value by 1 and transfers the remote data when the TTL value becomes 0. The remote data is not transferred forever, and the network load can be suppressed.

  In the network system 1 of the present embodiment, the gateway device 5 can filter unnecessary data by setting the group ID. Therefore, the traffic of the home network 2 can be prevented from being increased unnecessarily.

  Note that in the network system 1 of the present embodiment, various protocols defined in the DLNA guidelines (hereinafter collectively referred to as DLNA protocols) are examples of protocols that can be communicated in the home network 2 only in a closed network. However, the present invention is not limited to this, and a closed network protocol such as Bonjour (also called Randezvous) may be employed.

  In the present embodiment, the network system 1 is composed of ten home networks 2 for the sake of simplicity of explanation, but the present invention is not limited to this, and the network system 1 is composed of more than ten home networks 2. Of course, it may be configured from less than 10 home networks 2.

  Further, the home network 2 is configured such that two DLNA-compliant devices 6 are connected to each other. However, the present invention is not limited to this, and only one device may be connected. You may make it connect.

  In the present embodiment, the location identifier information is an IP address and a port number. However, the location identifier information is not limited to this and may be information necessary for communication with another gateway device 5. For example, when a global address is assigned to the gateway device 5, the location identifier information can be the IP address of the gateway device 5.

  Further, the group ID management unit 306 stores the group ID of the group to which the gateway device 5 belongs, but instead of or in addition to this, the identification information of the gateway device 5 is stored. May be.

  Although the present embodiment has been described above, the above embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

It is a figure which shows the structural example of the network system 1 which concerns on this embodiment. It is a figure which shows the structural example of the hardware of the gateway apparatus 5 which concerns on this embodiment. It is a functional block diagram of the gateway apparatus 5 which concerns on this embodiment. It is a sequence diagram which shows an example of communication in the network system 1 of this embodiment. It is a flowchart which shows the flow of the local request process in step S1 of FIG. It is a figure which shows the specific example of remote data. It is a flowchart which shows the flow of the remote request process in step S2 of FIG. It is a flowchart which shows the flow of the local response process in step S3 of FIG. It is a flowchart which shows the flow of the remote response process in step S4 of FIG.

Explanation of symbols

1 Network system 2 Home network 3 LAN
4 Home router 5 Gateway device 6 DLNA compliant device 20 CPU
21 RAM
22 ROM
23 Network Interface 24 Display Control Unit 25 Hard Disk 26 Monitor 300 Communication Unit 301 Transfer List Unit 302 Encapsulation Processing Unit 303 Intra-LAN Protocol Proxy Unit 304 Decapsulation Processing Unit 305 TTL Management Unit 306 Group ID Management Unit 307 Local Transfer Determination Unit

Claims (10)

A gateway device capable of communicating with an open network and capable of transmitting / receiving information to / from an information appliance in a closed network,
An encapsulation processing unit that performs encapsulation that enables communication to the open network to local data that is data that can be communicated in the closed network and cannot be communicated to the open network. When,
A remote receiving unit for receiving the encapsulated data transmitted from a first other gateway device connected to the open network;
A decapsulation processing unit for decapsulating the encapsulated data and extracting the local data;
A local communication unit that transmits the local data extracted from the encapsulated data into the closed network in which the proxy device itself exists;
A transfer destination information storage unit for storing transfer destination information that is information for specifying the second other gateway device connected to the open network;
A transfer processing unit that transmits the encapsulated data received from the first other gateway device to the second other gateway device specified by the transfer destination information;
A gateway device comprising: The gateway device according to claim 1,
A location identifier that is invalid in the closed network in which the proxy device itself exists and that is included in the encapsulated data received via the open network is a valid location identifier in the closed network. A gateway device comprising a position identifier conversion processing unit for converting to The gateway device according to claim 2,
The local data is one of a data group having a hierarchical structure, and a process for processing the local data higher than the local data is dynamically performed in association with the converted position identifier. A gateway device comprising a processing unit generating unit for generating. The gateway device according to claim 2,
The invalid location identifier is a location identifier of the information appliance that exists in the closed network different from the closed network where the gateway device itself exists,
The gateway device, wherein the valid location identifier is a location identifier of the gateway device itself. The gateway device according to claim 1,
The encapsulation includes a location identifier of the information home appliance that exists in the closed network that is different from the closed network in which the gateway device itself that is the transmission destination and the gateway device that is the transmission source exists. A gateway device characterized in that a location identifier of the information home appliance in the closed network is added to the local data as a header. The gateway device according to claim 1,
The encapsulated data is accompanied by an upper limit on the number of transfers,
The transfer processing unit, when the upper limit value attached to the encapsulated data received from the first other gateway device exceeds a predetermined value, the encapsulated data, Appending a value obtained by subtracting a predetermined value from the upper limit value and transmitting it to the second other gateway device;
The gateway apparatus characterized by this. The gateway device according to claim 1,
A group information storage unit that stores group information that is information indicating a group to which the gateway device belongs;
The encapsulated data is accompanied by the group information indicating the group as a destination,
The local communication unit is configured to connect the local data to the closed network only when the group information attached to the encapsulated data matches the group information stored in the group information storage unit. Sending in,
The gateway apparatus characterized by this. A first network that is a closed network having a first gateway device accessible to a first information appliance;
A second network that is a closed network having a second gateway device that can access a second information home appliance that cannot communicate with the first information home appliance;
And a third network that is a closed network having a third gateway device that can access a third information home appliance that cannot communicate with the first and second information home appliances. A network system,
The first to third gateway devices are communicably connected to each other via an open network,
The first gateway device is:
Communication to the open network is transmitted to the local data that is transmitted from the first information home appliance and is communicable within the closed network and is impossible to communicate with the open network. An encapsulation processing unit for performing encapsulation, and
A transfer destination information storage unit for storing transfer destination information which is information for specifying the second gateway device;
A remote transmission unit for transmitting the encapsulated data to the second gateway device specified by the transfer destination information via the open network;
With
The second gateway device is
A remote receiver for receiving the encapsulated data transmitted from the first gateway device;
A decapsulation processing unit for decapsulating the encapsulated data and extracting the local data;
A local communication unit for transmitting the local data to the second information home appliance;
A transfer destination information storage unit for storing the transfer destination information for specifying the third gateway device;
A remote transmission unit for transmitting the encapsulated data to the third gateway device specified by the transfer destination information via the open network;
With
The third gateway device is
A remote receiver for receiving the encapsulated data transmitted from the second gateway device;
A decapsulation processing unit for decapsulating the encapsulated data and extracting the local data;
A local communication unit for transmitting the local data to the third information home appliance;
A network system comprising: A gateway device that can communicate with an open network and can send / receive information to / from an information appliance in the closed network.
Encapsulation that enables communication to the open network is performed on local data that is data that can be communicated in the closed network and communication to the open network is impossible.
Receiving the encapsulated data transmitted from a first other gateway device connected to the open network;
Unencapsulate the encapsulated data and extract the local data;
Sending the local data extracted from the encapsulated data into the closed network where the proxy device itself resides;
Storing transfer destination information which is information for specifying the second other gateway device connected to the open network;
Transmitting the encapsulated data received from the first other gateway device to the second other gateway device specified by the transfer destination information;
A communication method characterized by the above. To a gateway device that can communicate with an open network and can send and receive information to and from information appliances in the closed network.
Encapsulating local data that is communicable within the closed network and that is incapable of communication with the open network, to enable communication with the open network; and
Receiving the encapsulated data transmitted from a first other gateway device connected to the open network;
Unencapsulating the encapsulated data and extracting the local data;
Transmitting the local data extracted from the encapsulated data into the closed network where the proxy device itself exists;
Storing transfer destination information which is information for specifying a second other gateway device connected to the open network;
Transmitting the encapsulated data received from the first other gateway device to the second other gateway device specified by the transfer destination information;
A program for running

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