JP2007129461A - Communication system and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a network terminal connected to a local IP network to be connected from a global IP network side adaptive to changes in IP address. <P>SOLUTION: A management device 2 notifies a global IP address of a repeating device 3a as a connection destination for a requirement from a network terminal 1. The network terminal 1 connects to the repeating device 3a using the global IP address. By communicating with the repeating device 3a using a high order layer of an OSI reference model, a virtual communication circuit is established for communication beyond a router device 4. The management device 2 responds to a DNS5 about inquiry of subdomain name by answering the global IP address of the repeating device 3a which has established a virtual communication circuit with a corresponding network terminal 1. The repeating device 3a relays communication by way of the virtual communication circuit established with the network terminal 1 corresponding to the subdomain name, for a client terminal 6 connected based on the subdomain name. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a communication system and a communication method for enabling a network terminal connected to a local IP network to be connected from the global IP network side.

  In recent years, there have been many regular connection services to the Internet (global IP (Internet Protocol) network) using CATV (cable television), ADSL (asymmetric digital subscriber line), FTTH (optical cable), FWA (wireless data communication), etc. Has been. In order to connect to the Internet, a global IP address is indispensable, but the cost is too high for a general user to occupy the global IP address. Therefore, generally, a global IP address owned by an ISP (Internet Service Provider) is borrowed and connected to the Internet.

  By the way, when connecting from the Internet side to the Internet terminal of the user who has borrowed the global IP address from the ISP, it is necessary to specify the global IP address. However, when borrowing a global IP address owned by an ISP in this way, this global IP address is assigned with a time limit and is reassigned when the time limit expires, so the assigned global IP address changes. Therefore, every time the global IP address changes, the user cannot connect to the Internet terminal unless the global IP address is designated.

  Therefore, a dynamic DNS (Domain Name Server) is known as a system for dealing with such a change in global IP address (see, for example, Patent Document 1). In dynamic DNS, a domain name and a global IP address are registered in association with each other, and this association is updated each time the global IP address changes. As a result, when connecting to the user's Internet terminal from the Internet side, the current global IP address can be acquired by first specifying a domain name and inquiring to the dynamic DNS. It becomes possible to connect.

JP 2002-305531 A

  By the way, in the conventional dynamic DNS, when the global IP address changes, the user's Internet terminal must notify the dynamic DNS that the global IP address has changed. The time difference until the registration of the dynamic DNS is updated becomes a problem. Further, when the dynamic DNS information is cached in another DNS, it becomes impossible to connect to the user's Internet terminal until the cached DNS information is updated.

  Further, depending on the ISP, a global IP address may not be assigned to a user's Internet terminal, but a private IP address may be assigned via a router device between the Internet and, for example, CATV. In this case, it is impossible to connect to the user's Internet terminal from the Internet side. Similarly, when the user himself / herself interposes a router device with the Internet, it is impossible to connect from the Internet side.

  Therefore, in the present invention, it is possible to connect a network terminal connected to the local IP network through a router device between the global IP network and the change of the IP address. It is an object of the present invention to provide a possible communication system and communication method.

  The communication system of the present invention is a management apparatus that is assigned a global IP address and connected to a global IP network, and is registered as a domain name server that manages subdomain names in a domain name server connected to the global IP network. A local IP address through a management device that has been assigned and a router device that is assigned a global IP address and is connected to the global IP network, and relays communication on the global IP network side and communication on the local IP network side. Network terminal program for enabling network terminals connected to the network to be connected from the global IP network side, and a plurality of programs connected to the global IP network, each assigned with an individual global IP address In response to a request from a network terminal managed by the management device using the subdomain name, the global IP address of the relay device selected from a plurality of relay devices is connected to the connection destination of the network terminal corresponding to the subdomain name. The network terminal program connects the network terminal to the connection destination relay device using the global IP address notified from the management device, and communicates with the connection destination relay device. For communicating with the upper layer of the OSI reference model between them to function as means for establishing a virtual communication line that communicates beyond the router device, and the management device further includes a subdomain name from the domain name server. The subdomain name that was inquired among multiple relay devices A means for replying a global IP address of a relay device that has established a virtual communication line with a corresponding network terminal, wherein the relay device responds to a domain name server with a global IP address corresponding to a subdomain name; A means for relaying communication over a virtual communication line established with a network terminal corresponding to this sub-domain name to a client terminal connected based on the global IP address obtained from the domain name server, inquiring about the address It is characterized by having.

  The communication method of the present invention is a management apparatus that is connected to a global IP network with a global IP address and is registered as a domain name server that manages subdomain names in a domain name server connected to the global IP network. A management device, a router device to which a global IP address is assigned and connected to the global IP network, relaying communication on the global IP network side and communication on the local IP network side, and a local IP network The network terminal connected to the local IP network is connected to the global IP network by a network terminal to be connected and a plurality of relay devices each assigned with a separate global IP address and connected to the global IP network. A communication method for enabling connection from the network side, wherein a global IP address of a relay device selected from a plurality of relay devices in response to a request from a network terminal managed by the management device using a subdomain name is Notification as the connection destination of the network terminal corresponding to the name, the network terminal connects to the connection destination relay device using the global IP address notified from the management device, and the OSI with this connection destination relay device Establishing a virtual communication line that communicates beyond the router device by communicating with the upper layer of the reference model, and when the management device inquires about the subdomain name from the domain name server, A virtual communication line has been established with the network terminal corresponding to the specified subdomain name. Replying the global IP address of the relay device, the relay device inquires of the domain name server about the global IP address corresponding to the subdomain name, and connects based on the global IP address acquired from the domain name server On the other hand, the present invention includes relaying communication by a virtual communication line established with a network terminal corresponding to the subdomain name.

  The OSI reference model refers to a model in which communication functions that a computer should have are divided into a hierarchical structure based on a network structure design policy “OSI (Open Systems Interconnection)” established by ISO (International Organization for Standardization). . The OSI reference model includes the first layer (physical layer), the second layer (data link layer), the third layer (network layer), the fourth layer (transport layer), the fifth layer (session layer), and the sixth layer. (Presentation layer) and 7th layer (application layer). In the OSI reference model, the first layer to the fourth layer are referred to as a lower layer, and the fifth layer to the seventh layer are referred to as an upper layer. The lower layer is responsible for telecommunications signal processing, and the upper layer is responsible for information processing itself. Control related to the IP address by the router device is performed in the third layer, and processing for relaying communication between different IP networks by the router device is performed in the fourth layer. In the present invention, communication beyond the router device is realized by performing communication using a layer above the fourth layer, that is, an upper layer of the OSI reference model.

  According to the present invention, a network terminal that operates a network terminal program requests a global IP address of a relay device connected from a plurality of relay devices to the management device, and the global information notified from the management device An IP address is used to connect to a connection destination relay device, and a virtual communication line is established for communication with the connection destination relay device by an upper layer of the OSI reference model. The virtual communication line transmits and receives data through a socket interface, which is an upper layer API (application program interface) that uses the lower layer of the OSI reference model, for example, and the processing by this socket interface is aware of the IP address of the other party. It is possible to communicate without any problem. That is, according to the present invention, communication by the higher layer of the OSI reference model can be performed without being aware of the other party's IP address. That is, even if the IP address of the network terminal is a local IP address of the local IP network, communication can be performed between the network terminal and the relay apparatus connected to the global IP network through the virtual communication line across the router apparatus. it can.

  In the present invention, when connecting from the client terminal on the global IP network side to this network terminal, the sub-domain name of the network terminal managed by the management apparatus is inquired to the domain name server connected to the global IP network. The domain name server makes an inquiry to the management apparatus of the present invention. In response to the inquiry about the subdomain name, the management apparatus returns the global IP address of the relay apparatus that has established a virtual communication line with the network terminal corresponding to the subdomain name. As a result, the client terminal can connect to the relay apparatus using this global IP address. Here, the relay device relays communication with the network terminal corresponding to the above-mentioned subdomain name that has established the virtual communication line, to the client terminal connected based on the global IP address. As a result, the client terminal can connect to the network terminal corresponding to the subdomain name via the relay device.

  According to the present invention, it is possible to connect from a global IP network side to a network terminal connected to a local IP network with a router device interposed between the global IP network. Further, when connecting from the global IP network side, it is only necessary to connect to the relay device, and communication between the relay device and the network terminal with the established virtual communication line is relayed. It is possible to respond to changes in

  FIG. 1 is an overall configuration diagram of a communication system according to an embodiment of the present invention, and FIG. 2 is a block diagram of the communication system of FIG.

  1, the communication system according to the embodiment of the present invention includes a network terminal 1 that executes the network terminal program of the present invention, a management device 2 that manages a subdomain name of the network terminal 1, and a network terminal 1. It includes relay devices 3a, 3b, 3c that establish virtual communication lines between them. A DNS (domain name server) 5 is an existing DNS connected to the global IP network 7. Although not shown, there are usually a plurality of DNSs 5 on the global IP network 7. Further, although only one network terminal 1 is illustrated, a plurality of network terminals 1 may exist. It is assumed that the management apparatus 2 is registered in the DNS 5 as a DNS that manages the subdomain name.

  The network terminal 1 is connected to the global IP network 7 via the router device 4. The router device 4 is installed in an ISP, home, or the like, and relays communication on the global IP network 7 side and communication on the local IP network 8 side to which the network terminal 1 is connected. The relay device 1, the management device 2, the DNS 5, and the like are also connected to the global IP network 7 by a similar router device, but are not shown. The management device 2, the relay devices 3a to 3c, and the DNS 5 including the port on the global IP network 7 side of the router device 4 are individually assigned global IP addresses for communication in the global IP network 7. And The global IP addresses of the management device 2, the relay devices 3a to 3c, and the DNS 5 are fixed IP addresses. However, the global IP address of the router device 4 may be fixed or variable.

  The network terminal program executed on the network terminal 1 is a program for enabling the network terminal 1 connected to the local IP network 8 to be connected from the global IP network 7 side, as shown in FIG. The terminal 1 is a socket between the allocation request means 10 for requesting the management device 2 to assign the relay devices 3a to 3c to be associated with the subdomain name and any one of the relay devices 3a to 3c assigned by the management device 2. This is a program for functioning as socket means 11 for establishing a virtual communication line using an interface. The network terminal program is supplied to the network terminal 1 via a storage medium such as a USB (Universal Serial Bus) memory or other non-volatile memory or a CD-ROM, or via an IP network. It may be recorded on the storage medium. The network terminal 1 can be connected to an IP network and can execute the network terminal program of the present invention, and can be a computer, a mobile phone or a personal digital assistant (PDA (personal digital assistant)). Any of these may be used.

  The network terminal 1 can connect to the management device 2 connected to the global IP network 7 via the router device 4 by using the global IP address of the management device 2. The global IP address can also be obtained by inquiring DNS 5 from the domain name of management device 2. The allocation request unit 10 notifies the management apparatus 2 connected to the global IP network 7 of the subdomain name allocated to itself, and requests allocation of the relay apparatuses 3a to 3c to be associated with the subdomain name. Is. The socket unit 11 uses one of the global IP addresses of the relay devices 3a to 3c notified from the management device 2 in response to the allocation request, and connects to the relay device (for example, the relay device 3a) via the router device 4. (The same applies to the following.) (This connection is possible by using a global IP address, as described above), and the upper layer of the OSI reference model is connected to the relay device 3a of the connection destination. A virtual communication line for transmitting and receiving data is established by a socket interface that is an API.

  In response to the allocation request of the relay devices 3a to 3c from the network terminal 1, the management device 2 receives the global IP address of the relay device 3a selected from the plurality of relay devices 3a to 3c, and is notified from the network terminal 1 It has a relay device assignment means 20 for notifying as a connection destination of the network terminal 1 corresponding to the name. The relay device assigning means 20 manages the correspondence between the subdomain name notified from the network terminal 1 and the assigned relay device 3a by registering it in the database at the time of assignment.

  Note that a domain name (for example, “server.co.jp”) is assigned to the management apparatus 2. The management device 2 manages the subdomain name (for example, “user”) of the network terminal 1 and, in response to an inquiry from the DNS 5, an FQDN (fully qualified domain name) including the subdomain name (in the above example, DNS means 20 for replying a global IP address corresponding to “user.server.co.jp”). More specifically, the global IP address that is replied by the DNS means 20 is not the IP address of the network terminal 1 itself corresponding to the subdomain name, but the relay device 3a that has established a virtual communication line by the network terminal 1 and the socket interface. Global IP address.

  The relay apparatuses 3a to 3d are connected to the socket means 30 for establishing a virtual communication line using a socket interface in response to a request for establishment of a virtual communication line from the network terminal 1, and the client terminal 6 connected from the global IP network 7 side. On the other hand, it has relay means 31 for relaying communication through the virtual communication line established by the socket means 30. Here, since the client terminal 6 does not know the global IP address of the relay device 31, the client terminal 6 inquires about the global IP address corresponding to the FQDN including the subdomain name of the network terminal 1 to be connected to the DNS 5. As described above, the DNS 5 inquires of the management device 2 about the subdomain name and returns the acquired global IP of the relay devices 3a to 3d, so that the client terminal 6 is based on the global IP address acquired from the DNS 5. Connect to the relay devices 3a to 3d. The relay unit 31 relays communication using the virtual communication line established with the network terminal 1 corresponding to the subdomain name to the client terminal 6 connected based on the global IP address acquired from the DNS 5. Is.

  Here, a specific procedure for establishing a virtual communication line between the socket unit 11 of the network terminal 1 and the socket unit 30 of the relay device 3a will be described. FIG. 3 is a flowchart showing a procedure for establishing a virtual communication line by the socket interface.

  First, the socket means 30 of the relay device 3a generates a socket (step S100) and assigns a name (step S101). At this time, the socket means 30 determines the port number and protocol to be used. Thereafter, the socket unit 30 waits for a connection request from the network terminal 1 (step S102).

  On the other hand, when the socket means 11 of the network terminal 1 acquires the global IP address of the relay device 3a assigned from the management device 2 (step S200), it generates a socket (step S201) and relays using this global IP address. A connection request is made to the apparatus 3a (step S202).

  At this point, since the mutual identification information (IP address and port number) between the relay device 3a and the network terminal 1 is confirmed, a single communication path (virtual communication line) is connected between the relay device 3a and the network terminal 1. ) Is established (steps S103 and S203). Thereafter, the socket unit 30 of the relay device 3a and the socket unit 11 of the network terminal 1 can transmit / receive data to / from the socket (steps S104 and S204). When the transmission / reception ends, the socket means 30 and 11 close the socket (steps S105 and S205).

  In data transmission / reception using such a socket interface, communication is performed with the other party only by transmitting / receiving data to / from the socket without being aware of the mutual IP address and port number of the relay device 3a and the network terminal 1. It is possible. Therefore, even if the IP address of the network terminal 1 is a local IP address of the local IP network, it is possible to communicate with the relay device 3a beyond the router device 4.

  The port number and protocol used by the socket are arbitrary, but when a firewall is interposed between the global IP network 7 and the local IP network 8, the port number: 80, protocol: HTTP (hypertext It is desirable to use a transfer protocol. Normally, the firewall is set to allow the port number and protocol to pass through. Therefore, it is not necessary to change the setting even if the firewall is interposed by using these port numbers and protocols.

  Next, a flow from the client terminal 6 to the network terminal 1 connected to the network terminal 1 via the relay device 3a by the communication system having the above configuration will be described. FIG. 4 is a flowchart showing a communication procedure by the communication system of FIG.

  First, the network terminal program of the present invention is executed on the network terminal 1 (step S300). The network terminal 1 on which this network terminal program has been executed notifies the management device 2 of the subdomain name assigned to it by the assignment request means 10 and requests assignment of the relay devices 3a to 3c (step S301). ). In response to the allocation request of the relay devices 3a to 3c from the network terminal 1, the management device 2 uses the relay device allocation means 20 to assign the global IP address of the relay device 3a selected from the plurality of relay devices 3a to 3c to this network. The network terminal 1 is notified as the connection destination of the network terminal 1 corresponding to the subdomain name notified from the terminal 1 (step 302). The network terminal 1 uses the global IP address of the relay device 3a notified from the management device 2 in response to this allocation request, and establishes a virtual communication line with the relay device 3a by the socket means 11 (steps S303 and S304). ).

  On the other hand, the client terminal 6 inquires of the DNS 5 about the global IP address corresponding to the FQDN including the subdomain name assigned to the network terminal 1 to be connected (step S305). The DNS 5 inquires of the management apparatus 2 about the subdomain name (step S306). The management apparatus 2 returns to the DNS 5 the global IP address of the relay apparatus 3a that has established a virtual communication line with the client terminal 6 managed by the subdomain name (step S307). The DNS 5 returns the global IP of the relay device 3a acquired from the management device 2 to the client terminal 6 (step S308). The client terminal 6 connects to the relay device 3a based on the global IP address acquired from the DNS 5 (step S309). The relay unit 31 relays communication using the virtual communication line established with the network terminal 1 corresponding to the subdomain name to the client terminal 6 connected based on the global IP address acquired from the DNS 5. (Step S310).

  Through the above processing, the client terminal 6 relays the global IP by relaying the relay device 3a to the network terminal 1 connected to the local IP network 8 with the router device 4 interposed between the client terminal 6 and the global IP network 7. It becomes possible to connect from the network 7 side. Further, when connecting from the global IP network 7 side, it is only necessary to connect to the relay device 3a, and communication between the relay device 3a and the network terminal 1 with the established virtual communication line is relayed. A change in the IP address of the terminal 1 can also be handled. If such a communication system is used, the user of the network terminal 1 uses the network terminal 1 connected to the local IP network 8 to perform a web server function, a file sharing function, a bulletin board function, a chat function, and a screen sharing function. It is possible to provide the client terminal 6 with a web mail function, a screen sharing function, a remote operation function, and the like.

  The present invention is useful as a communication system and communication method for enabling connection of a network terminal connected to a local IP network from the global IP network side. In particular, the present invention makes it possible to connect a network terminal connected to a local IP network through a router device between the global IP network from the global IP network side and cope with a change in IP address. This is suitable as a communication system and a communication method, and if this is used, a network terminal connected to a local IP network allows a web server function, a file sharing function, a bulletin board function, a chat function, a screen sharing function, a web mail function, a screen. A sharing function and a remote operation function can be provided.

1 is an overall configuration diagram of a communication system in an embodiment of the present invention. It is a block diagram of the communication system of FIG. It is a flowchart which shows the establishment procedure of the virtual communication line by a socket interface. It is a flowchart which shows the communication procedure by the communication system of FIG.

Explanation of symbols

1 Network terminal 2 Management device 3a, 3b, 3c Relay device 4 Router device 5 DNS
6 Client terminal 7 Global IP network 8 Local IP network 10 Allocation request unit 11 Socket unit 20 Relay device allocation unit 21 DNS unit 30 Socket unit 31 Relay unit

Claims (3)

A management apparatus that is assigned a global IP address and is connected to a global IP network, the management apparatus registered as a domain name server that manages subdomain names in a domain name server connected to the global IP network;
A router that is assigned a global IP address and is connected to the global IP network, and is connected to the local IP network via a router that relays communication on the global IP network side and communication on the local IP network side. A network terminal program for enabling a network terminal to be connected from the global IP network side;
A plurality of relay devices each assigned with an individual global IP address and connected to the global IP network,
In response to a request from a network terminal managed by the subdomain name, the management apparatus notifies a global IP address of a relay apparatus selected from the plurality of relay apparatuses as a connection destination of the network terminal corresponding to the subdomain name And means for
The network terminal program connects the network terminal to a connection destination relay device using the global IP address notified from the management device, and the upper layer of the OSI reference model with the connection destination relay device. For functioning as means for establishing a virtual communication line for communicating across the router device by communicating with
The management device further establishes the virtual communication line with the network terminal corresponding to the inquired subdomain name among the plurality of relay devices in response to the inquiry of the subdomain name from the domain name server. A means for answering the global IP address of the relay device
The relay device queries the domain name server for a global IP address corresponding to the subdomain name, and corresponds to the subdomain name for a client terminal connected based on the global IP address acquired from the domain name server. A communication system having means for relaying communication through a virtual communication line established with a network terminal.   The communication system according to claim 1, wherein the virtual communication line transmits and receives data through a socket interface. A management apparatus that is assigned a global IP address and is connected to a global IP network, the management apparatus registered as a domain name server that manages subdomain names in a domain name server connected to the global IP network;
A router device to which a global IP address is assigned and connected to a global IP network, which relays communication on the global IP network side and communication on the local IP network side;
A network terminal connected to the local IP network;
With a plurality of relay devices each assigned an individual global IP address and connected to the global IP network,
A communication method for enabling a network terminal connected to the local IP network to be connected from the global IP network side,
In response to a request from a network terminal managed by the subdomain name, the management apparatus notifies a global IP address of a relay apparatus selected from the plurality of relay apparatuses as a connection destination of the network terminal corresponding to the subdomain name To do,
The network terminal uses the global IP address notified from the management device to connect to a connection destination relay device, and communicates with the connection destination relay device by an upper layer of the OSI reference model. Establishing a virtual communication line that communicates across devices,
In response to an inquiry about a subdomain name from the domain name server, the management device establishes the virtual communication line with a network terminal corresponding to the inquired subdomain name among the plurality of relay devices. Answering the global IP address of the relay device
The relay device queries the domain name server for a global IP address corresponding to the subdomain name, and corresponds to the subdomain name for a client terminal connected based on the global IP address acquired from the domain name server. A communication method including relaying communication through a virtual communication line established with a network terminal.

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