JP2008271203A - Communication network system and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a router device having a mechanism for continuing a communication without breaking the connection of established communication right in the middle of the occurrence of a network failure sch thats it is impossible to be connected to an ISP and a communication throughput is reduced. <P>SOLUTION: When transmitting transmission data from a terminal device 10, a terminal side router device 30 changes a transmission source IP address included in an IP packet being the transmission data from a local address to a global address, and a server side router device 50 changes the transmission source IP address included in the received transmission data from the global address to the local address. The server side router device 50 changes a transmission destination IP address of reply data received from a server device 20 from a local address to a global address, and the terminal side router device 30 receiving the replay data changes the transmission destination IP address included in the replay data from the global address to the local address. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention continues communication without disconnection of communication established during the occurrence of a network failure such as inability to connect to an Internet service provider (hereinafter referred to as an ISP) or a decrease in communication throughput. The present invention relates to a communication network system and program.

  For communication between network devices used in a network such as the Internet, a protocol (communication protocol) called IP (Internet Protocol) is used, and an IP address is used as an identifier for identifying these network devices. If this IP address is uniquely assigned to network devices all over the world connected to the Internet, the IP address will be exhausted.

  Therefore, a “private address” (unique IP address for network devices in the company or home) is assigned to network devices that are not connected to the Internet, and when this network device connects to the Internet, a “global address” (global address) is assigned. The IP address is effectively utilized by allocating the only IP address in the network device. This address translation function from a private address to a global address is called “NAT (Network Address Translation)” or “IP masquerading”, and this address translation is mainly performed by a router device. In general, this global address is automatically assigned by a server apparatus called “DHCP (Dynamic Host Configuration Protocol)”.

  By the way, in the network, for example, a network failure occurs due to various reasons such as a physical disconnection of a network cable or a power failure. Here, when a network failure occurs, a great trouble is caused in daily work, and therefore, a countermeasure against the failure is prepared by preparing a backup line and duplicating the communication path. For example, a method of changing the communication path by changing the communication means or changing the connection destination ISP is used.

  However, when the communication path is changed, the network device, for example, from the address of the ISP server device (main line network) of the connection destination that has already been set, the ISP server device (sub-line network) for the backup line is used. There arises a problem that a setting change such as changing the setting to an address or changing the setting from an already set DHCP server address to a new DHCP server address is required. Therefore, in order to solve such a problem, a technique has been proposed in which the router device on the transmission side is provided with a NAT function and address conversion is performed at the time of line switching so that the setting of the terminal-side network device does not have to be performed again ( For example, see Patent Document 1).

JP 2003-249950 A

  However, with this prior art proposed method, communication established while a network failure such as an inability to connect to the ISP or a decrease in communication throughput has occurred will continue because the IP address of the transmission source changes. There is a problem that it cannot be done.

  In other words, in communication that maintains a session such as TCP, when an IP address change occurs due to line switching, a communication mismatch occurs and the session is disconnected, so it is necessary to reestablish the TCP session.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a communication network system and program having a mechanism for continuing communication without disconnection of communication established during the occurrence of a network failure such as inability to connect to an ISP or a decrease in communication throughput. Is to provide.

The communication network system according to the first aspect of the present invention is a communication network system in which a terminal device and a server device are connected by the Internet via a terminal router device and a server router device, respectively.
The terminal-side router device includes first correspondence address storage means for storing a local address and a global address in association with each other, and transmission data reception means for receiving transmission data from the terminal device to the server device. A global address changing means for changing a local address of the terminal device set as a transmission source address included in the transmission data to a global address stored in the first corresponding address storage means, and the global address Transmission means for transmitting the transmission data changed by the changing means to the server side router device,
The server-side router device includes a second corresponding address storage unit that stores a global address and a local address of the terminal device in association with each other, a transmission data reception unit that receives transmission data transmitted from the transmission unit, Local address changing means for changing the global address of the terminal device set as the source address included in the transmission data to a local address stored in the second corresponding address storage means, and the local address changing means And transmission means for transmitting the transmission data changed by the above to the server device.

  Furthermore, a program for causing a computer to function as the main means shown in the invention described in claim 1 is provided (the invention described in claim 5).

The communication network system according to claim 2 is the communication network system according to claim 1,
The server-side router device includes a reply data receiving unit that receives reply data returned from the server device, and a local address of the terminal device that is set as a transmission destination address included in the reply data. A global address changing means for changing to the global address stored by the corresponding address storage means, and a reply means for returning the reply data changed by the global address changing means to the terminal side router device. The router device on the side changes the reply data receiving means for receiving the reply data, and changes the destination address included in the reply data to the local address of the terminal device stored in the first corresponding address storage means Change by local address change means and this local address change means Characterized in that it has a return means for the return data back to the terminal device, the.

  Furthermore, a program for causing a computer to function as the main means shown in the invention described in claim 2 is provided (the invention described in claim 6).

The communication network system according to claim 3 is the communication network system according to claim 1 or 2,
The terminal-side router device further includes address correspondence information transmitting means for transmitting address correspondence information associating a global address and a local address of the terminal device to the server-side router device,
The second correspondence address storage means of the server side router device stores the address correspondence information transmitted by the address correspondence information transmission means.

The communication network system according to claim 4 is the communication network system according to any one of claims 1 to 3,
The terminal side router device has a first connection means for connecting to the first network, and a second connection means for connecting to the second network when the first connection means fails to connect to the first network. Connecting means,
The global address transmitted by the address correspondence information transmitting means is a global address for connecting to the first or second network.

  According to the present invention, a communication network system and a program capable of continuing communication without disconnection of a communication established during a network failure such as an inability to connect to an ISP or a decrease in communication throughput. Can provide.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration of a communication network system according to an embodiment of the present invention.
This communication network system includes a plurality of terminal devices 10 (installed on a network N3 such as an in-house LAN, etc. (IP addresses are 210.150.1.1/24, 210.150.1.254/24 in order to explain this embodiment) Only the IP address is described below), the terminal side router device 30 (210.150.10.200/24), the server device 20 (210.150.32.1/24) installed in the destination network N4, and the server side router device 50 (210.150.32.200). / 24), main line network N1, DHCP server apparatus 40 (210.150.10.0/24), secondary line (backup line) network N2, DHCP server apparatus 60 (210.150. 20.0 / 24) is connected. In the embodiment of the present invention, a two-line network of the main line network N1 and the sub-line network N2 is configured, but it may be configured by a network of more lines.

  In this communication network system, transmission data created by the terminal devices 10... Passes through the terminal side router device 30, passes through the main line network N 1 or the sub line network N 2, and passes through the server side router device 50. 20 is transmitted.

  Further, in this communication network system, the reply data from the server device 20 passes through the server side router device 50, passes through the terminal side router device 30 via the main line network N1 or the sub line network N2, and passes through the terminal device 10 ... Will be replied to.

  FIG. 2 is a hardware configuration diagram of the terminal side router device 30. The terminal-side router device 30 includes a CPU 31 that is a computer. The CPU 31 controls the operation of each unit in the terminal-side router device 30 according to a program stored in the storage unit 32 such as a flash memory.

  The CPU 31 is connected by a bus line 35 to the storage unit 32, a transmission / reception unit 34, a transmission / reception control device 33 that controls the transmission / reception unit 34, and the like. The transmission / reception unit 34 is connected to the networks N1, N2, and N3. The storage unit 32 includes an initial setting data storage unit 32A and an address conversion table 32B. In addition, transmission data transmitted from the terminal side router device 30 to the server side router device 50 or received reply data is transmitted / received by the transmission / reception unit 34 by the CPU 31 controlling the transmission / reception control device 33.

  As shown in FIG. 3, the initial setting data storage unit 32A includes a connection destination table 32A (1) and a terminal device management table 32A (2). The connection destination table 32A (1) includes a connection destination network name 1a, a connection account 1b, and a connection password 1c. The terminal device management table 32A (2) includes an identifier ID (1d) of the terminal side router device 30 and a terminal device. 10 local addresses and range 1e, and server side router address: port 1f.

  In the connection destination table 32A (1), the name 1a, the account 1b, and the password 1c of the main line network N1 are stored, and the name 1a, the account 1b, and the password 1c of the sub-line network N1 are stored in the ISP. When a network failure or the like such as inability to connect or a decrease in communication throughput occurs, the network can be switched.

  Note that only one piece of data is stored in the server side router address: port 1f of the terminal device management table 32A (2), but a plurality of pieces of data can be stored according to the number of server devices 20 to be connected.

  Further, by storing the identifier ID (1d), the local address and range 1d, and the server side router address: port 1f in the terminal device management table 32A (2), an identifier packet p1 described later can be generated.

  The address conversion table 32B is shown in FIG. The address conversion table 32B includes a terminal side router identifier 1d, a previous line state 3b, a current line state 3c, a local address 1ea, a main line global address 3ea, and a sub line global address 3eb. From this address conversion table 32B, the terminal side router device 30 can determine the correspondence between the local address of the terminal device 10 and the global address, and whether the currently connected line is a main line or a sub line. In the embodiment, the terminal-side router identifier 1d is CNET1.

  FIG. 5 is a hardware configuration diagram of the server side router device 50. The server-side router device 30 includes a CPU 51 that is a computer. The CPU 51 is connected to a storage unit 52, a transmission / reception unit 54, a transmission / reception control device 53 that controls the transmission / reception unit 54, and the like via a bus line 55. . The transmission / reception unit 54 is connected to the networks N1, N2, and N4. The storage unit 52 stores an initial setting data storage unit 52A and an identifier information management table 52B.

As shown in FIG. 6, the initial setting data storage unit 52A includes a connection destination management table 52A (1) and a terminal device management table 52A (2). The connection destination management table 52A (1) includes a connection destination network name 1a, an account 1b for connecting to the network, a password 1c, an IP address 1fa of the server side router device 50, and a reception port 1fb. 52A (2) includes a terminal-side router identifier 1d, a local address of the terminal device 10, and a range 1e. Thereby, the server side router apparatus 50 comes to be connected from the network N1 or N2. The initial setting 52A may be set manually or may be automatically set from the terminal side router device 30 or the like.
However, when setting automatically, it is necessary to embed the local address of the terminal side router device 30 in the identifier.

  The identifier management table 52B is shown in FIG. The identifier management table 52B stores a terminal-side identifier ID (1d), a local address 1ea, and a global address 3e. The identifier management table 52B enables correspondence between the local address of the terminal device 10 and the global address.

  FIG. 8 is a sequence diagram showing a flow of communication processing among the terminal device 10, the terminal side router device 30, the server side router device 50, and the server device 20 in the communication network system. Hereinafter, FIG. 8 will be described.

First, the terminal side router device 30 stores the initial setting data storage unit 32A in the storage unit 32 (301).
On the other hand, the server side router device 50 stores the initial setting data storage unit 52A shown in FIG. 6 in the storage unit 52 (501).

  Next, the terminal side router device 30 connects to the ISP, and a global address is assigned by this ISP. The global address allocated by the ISP is stored in the address conversion table 32B of the storage unit 32 shown in FIG. 4 (302). This is the first corresponding address storage means in the claims according to the present invention.

  Next, the terminal side router device 30 refers to the identifier ID (1d), the local address and range 1e, the server side router address and the port 1f of the initial setting data storage unit 32A stored in the storage unit 32. An identifier packet (IP packet p1) including the identifier 1d of the device 30 is generated and transmitted to the server side router device 50 (303). This identifier packet p1 is shown in FIG. In addition to the identifier 1d, the identifier packet p1 is set with the address of the server side router device 50 as the destination address 1fa and the address of the terminal side router device 30 as the source address 4b. Includes information that communication is performed using the UDP protocol, and information on a connection destination port (for example, port number 65432) of the server side router device.

  By transmitting this identifier packet p1 from the terminal side router device 30 to the server side router device 50, the server side router device 50 stores the terminal side router identifier 1d, local address and range 1e stored in the initial setting data storage unit 52A. The local address and the global address of the terminal device 10 can be associated with each other by the identifier 1d and the source address 4b included in the identifier packet.

  The server side router device 50 stores the table in which the local address and the global address are associated with each other in the storage unit 52 as the identifier information management table 52B illustrated in FIG. 7 (the second corresponding address storage unit according to the present invention) ), It responds to the terminal side router device 30 to that effect. This identifier information management table may be set manually or automatically. However, care must be taken not to overlap the address of the terminal side router device 30.

Next, the terminal device 10 transmits the transmission data (304).
The terminal device 10 transmits the IP packet p2 shown in FIG. The local address of the terminal device 10 is set in the source address 4b of the IP packet p2.

  The terminal-side router device 30 that has received this IP packet p2 refers to the address conversion table 32B stored in the storage unit 32 and refers to the main line global address corresponding to the source address (local address) included in this IP packet p2. 3ea (or sub-line global address 3eb).

  Then, the terminal side router device 30 transmits the changed IP packet p3 shown in FIG. 11 to the server side router device 50. A global address (main line global address 3ea or subline global address 3eb) of the terminal device 10 is set in the source address 4b included in the IP packet p3. As a result, communication in the Internet environment becomes possible.

  On the other hand, the server side router device 50 receives the IP packet p3 transmitted from the terminal side router device 30 (504), and receives the received IP packet based on the identifier information management table 52B shown in FIG. The global address of the source address 4b included in the packet p3 is changed to a local address, and the server side router device 50 transmits the changed IP packet p4 shown in FIG. 12 to the server device 20.

  The server device 20 that has received this IP packet p4 returns reply data (IP packet p5 shown in FIG. 13) based on the request to the server side router device 50. Note that a local address is set in the transmission destination address 4a included in the IP packet p5.

  The server side router device 50 that has received this IP packet p5 refers to the identifier information management table 52B stored in the storage unit 52, and changes the local address set in the transmission destination address 4a to the global address 3e. The changed IP packet p6 shown in FIG. 14 is transmitted to the terminal side router device 30. This enables communication under the Internet environment.

  On the other hand, the terminal-side router device 30 that has received the IP packet p6 refers to the address conversion table 32B stored in the storage unit 32 (305), and uses the global address of the destination address 4a included in the IP packet p6 as a local address. change. The changed IP packet p7 shown in FIG. 15 is transmitted to the terminal device 10.

  The flow of processing between the devices has been described above with reference to FIG. Next, the processing of the terminal side router device 30 and the server side router device 50 when the main line network N1 and the sub line network N2 are switched will be described with reference to the flowcharts of FIGS.

  FIG. 16 is a flowchart showing a processing flow of the terminal side router device 30. FIG. 17 is a flowchart showing a process flow of the connection process AB which is a part of the process of the terminal side router device 30.

FIG. 16 will be described. First, in the initial setting, the initial setting data storage unit 32A is stored in the storage unit 32 (step A1, 301 in FIG. 8).
Next, connection processing AB is performed on the ISP in order to obtain a global address (step AB, 302 in FIG. 8). This connection processing AB will be described later.

  After this connection process AB, the terminal apparatus 10 transmits data of the IP packet p2, and determines whether or not the IP packet p2 has been received (step A2, 303 in FIG. 8). If it is determined that it has been received (step A2 (Yes)), it is determined whether the current line state 3c of the address conversion table 32B stored in the storage unit 32 is “1” or “2” (not “1”). It discriminate | determines (step A3).

  Here, if the current line state 3c is “1” (step A3 (Yes)), it means that the connection is made to the main line network N1, and therefore the source address 4b included in the received IP packet p2 is changed. The corresponding main line global address 3ea is changed (step A4). If the line state 3c is “2” this time (step A3 (No)), it means that the line is connected to the sub-line network N2, and therefore the source address 4b included in the received IP packet p2 is associated with the corresponding sub-line 4b. The line global address is changed to 3eb (step A5).

  Then, this IP packet p3 is transmitted to the server side router device 50 (step A6, 304 in FIG. 8). When the reply data (IP packet p6) is received from the server side router device 50 (step A7 (Yes)), the address conversion table 32B included in the storage unit 32 is referred to, and the transmission destination included in the IP packet p6 The global address of the address 4a is changed to the corresponding local address (step A8, 305 in FIG. 8).

Then, the changed IP packet p7 is transmitted to the terminal device 10 (step A9). Next, the connection process (step AB) in FIG. 17 will be described.
First, when connecting to the ISP, as initialization processing, “0” is set in the current line state 3c of the address conversion table 32B of the storage unit 32 (step B1), and “0” is set in the previous line state 3b. (Step B2).

  Next, it is determined whether or not connection to the main line network N1 can be established (or communication throughput has decreased) (step B3). If the connection to the main line network N1 is established (step B3 (Yes)), “1” indicating the main line network N1 is set in the current line state 3c of the address conversion table 32B (step B4). Then, the previous line state 3b and the current line state 3c are compared. If they are the same (step B5 (Yes)), “1” is set in the previous line state 3b of the address conversion table 32B (step B11). When connecting for the first time, step B5 (No) is always performed, and step B6 and subsequent steps described later are performed.

  On the other hand, the previous line state 3b and the current line state 3c are compared. If they are not the same (step B5 (No)), the global addresses of the terminal device 10 and the terminal side router device 30 are acquired from the ISP (step B6). The acquired global address of the terminal device 10 is set to the main line global address 3ea of the address conversion table 32B (step B7). The global address of the terminal side router device 30 is transmitted to the server side router device 50 as the identifier packet p1.

  Then, the server side router address and the port number 1f are acquired from the initial setting data storage unit 32A stored in the storage unit 32 (step B8), and the terminal side router identifier information 1d and the like are then used as an identifier packet (IP packet p1). The server side router device 50 is transmitted (step B9), the response from the server side router device 50 is received (step B10), and “1” is set in the previous line state 1b of the address translation table 32B (step B11). The connection process AB is terminated.

  In the case of step B3 (No), that is, whether or not connection to the main line network N1 is possible and connection to the main line network N1 is not possible, connection to the sub line network N2 is possible (or communication throughput decreases). It is determined whether or not (step B12). If connection to the sub-line network N2 is established (step B12 (Yes)), “2” meaning the sub-line network N2 is set in the current line state 3c of the address conversion table 32B stored in the storage unit 32 ( Step B13).

  In the case of Step B14 (Yes), that is, the previous line state 3b and the current line state 3c are compared. If they are the same, “2” is set in the previous line state 3b of the address conversion table 32B (Step B20). On the other hand, the previous line state 3b and the current line state 3c are compared. If they are not the same (step B14 (No)), the global addresses of the terminal device 10 and the terminal side router device 30 are acquired from the ISP (step B15). The acquired global address of the terminal device 10 is set to the sub-line global address 3eb of the address conversion table 32B (step B16). The global address of the terminal side router device 30 is transmitted to the server side router device 50 as the identifier packet p1.

  In step B17, the server side router address and port number 1f are obtained from the initial setting data storage unit 32A stored in the storage unit 32, and then the terminal side router identifier information 1d and the like are used as an identifier packet (IP packet p1). The server side router device 50 is transmitted (step B18), the response from the server side router device 50 is received (step B19), and “2” is set in the previous line state 1b of the address translation table 32B (step B20). The connection process AB is terminated.

  This completes the description of the operation of the terminal side router device 30 according to the flowchart. As a result, even if the main line network N1 and the sub-line network N2 are switched to each other due to a failure, it is possible to grasp which network the terminal side router device is currently connected to and which network it was connected to last time. Established during the occurrence of a network failure, such as a local address to global address translation or a global address to local address translation that can not be connected to an ISP, or a reduced communication throughput. Communication can be continued without disconnecting communication.

Next, the operation of the server side router device 50 will be described with reference to the flowcharts of FIGS.
The server side router device 50 first stores the initial setting data storage unit 52A in the storage unit 52 (step C1, 501 in FIG. 8). Based on the initial setting data storage unit 52A, connection is made to the ISP (step C2, 502 in FIG. 8), and a response is received (step C3).

  Here, in step C4 (503 in FIG. 8), it is determined whether or not the identifier packet (IP packet p1) transmitted by the terminal-side router device 30 has been received. Step C4 (Yes)), the local address and range 1e corresponding to the identifier 1d are retrieved from the initial setting data storage unit 52A2 (Step C5), and based on the source address 4b included in the received identifier packet (IP packet p1). The identifier information management table 52B is created (step C6).

  In step C7, the terminal side router device 30 is responded to the fact that the identifier packet (IP packet p1) has been received, and the transmission / reception process CD is continued (step CD). This transmission / reception processing CD is shown in FIG.

  In step D1, it is determined whether or not transmission data (IP packet p3) has been received from the terminal side router device 30, and if it is determined that it has been received (step D1 (Yes), 504 in FIG. 8), identifier management is performed. The local address 1ea in the table 52B is changed to the source address of the IP packet (step D2), and the IP packet p5 is transmitted to the server device 20 (step D3).

  Then, in step D4, it is determined whether or not reply data (IP packet p5) has been received from the server device 20. If it is determined that it has been received (step D4 (Yes)), the identifier stored in the storage unit 52 is determined. The global address 3e stored in the management table 52B is set as the destination address of the IP packet (step D5), the IP packet p6 is transmitted to the terminal side router device 30 (step D6), and this transmission / reception process CD is terminated.

  As a result, it is possible to provide a communication network system and a program capable of continuing communication without disconnection of communication established during the occurrence of a network failure such as inability to connect to an ISP or a decrease in communication throughput. .

  In the present embodiment, the global address and local address of the terminal device 10 are converted by the identifier information management table 52B stored in the storage unit 52 of the server side router device, and the identifier management table 52B is converted into the initial setting data storage unit. The local address and the range 1e are created based on the local address 52A and the range 1e. When the local address and the range 1e are the same local address as that of the terminal device 10, it is necessary to set the local address so as not to overlap. However, the local address 1e that is initially set only needs to be uniquely set in the server side router device 50, and is not necessarily the same as the local address of the terminal device 10. Furthermore, the initial setting data storage units 32A and 52A do not need to be set in advance, and may be generated at a necessary time.

  Note that the processing of the terminal-side router device 30 and the server-side router device 50 described in the above-described embodiment, that is, each processing shown in the flowcharts of FIGS. It is stored in the unit 52, but in addition to recording media such as memory cards (ROM cards, RAM cards, etc.), magnetic disks (floppy disks, hard disks, etc.), optical disks (CD-ROMs, DVDs, etc.), semiconductor memories, etc. Further, a part or all of the program may be stored in a recording medium provided in the server device or the client device, and may be received and read via a network.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment or some constituent features are combined, the problem described in the column of the problem to be solved by the invention can be solved. When the effect described in the column of effect is obtained, a configuration in which these constituent requirements are deleted or combined can be extracted as an invention.

The figure which shows the structure of the communication network system which concerns on embodiment of this invention. The hardware block diagram of the terminal side router apparatus 30. FIG. The figure which shows 32A of initial setting data memorize | stored in the memory | storage part 32 of the terminal side router apparatus 30. FIG. The figure which shows the initial setting data 32B memorize | stored in the memory | storage part 32 of the terminal side router apparatus 30. FIG. The hardware block diagram of the server side router apparatus 50. FIG. The figure which shows 52 A of initialization data memorize | stored in the memory | storage part 52 of the server side router apparatus 50. FIG. The figure which shows the identifier information management table 52B memorize | stored in the memory | storage part 52 of the server side router apparatus 50. FIG. Data flow between devices in a communication network system. The figure which shows the IP packet which concerns on the identifier packet transmitted to the server side router apparatus 50 from the terminal side router apparatus 30. FIG. The figure which shows the IP packet transmitted to the terminal side router apparatus 30 from the terminal device 10. FIG. The figure which shows the IP packet transmitted to the server side router apparatus 50 from the terminal side router apparatus 30. FIG. The figure which shows the IP packet transmitted to the server apparatus 20 from the server side router apparatus 50. The figure which shows the IP packet transmitted to the server side router apparatus 50 from the server apparatus 20. FIG. The figure which shows the IP packet transmitted to the terminal side router apparatus 30 from the server side router apparatus 50. FIG. The figure which shows the IP packet transmitted to the terminal device 10 from the terminal side router apparatus 30. FIG. 5 is a flowchart showing processing of the terminal side router device 30. The flowchart which shows the connection process AB of the terminal side router apparatus 30. FIG. The flowchart which shows the process of the server side router apparatus 50. FIG. The flowchart which shows the transmission / reception process CD of the server side router apparatus 50. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Terminal device 20 ... Server device 30 ... Terminal side router device 50 ... Server side router device 31, 51 ... CPU
32, 52 ... storage unit 32A, 32A (1), 32A (2), 52A (1), 52A (2), ... initial setting data storage unit 32B ... address conversion table 52B ... identifier information management table 33, 53 ... transmission / reception Control device 34, 54 ... Transmission / reception unit 35, 55 ... Bus line 40 ... DHCP server device 1
60: DHCP server device 2
N1, N2, N3, N4 ... Network p1, p2, p3, p4, p5, p6, p7 ... IP packet

Claims (6)

A communication network system in which a terminal device and a server device are connected by the Internet via a terminal side router device and a server side router device, respectively.
The terminal-side router device is
First corresponding address storage means for storing a local address and a global address of the terminal device in association with each other;
Transmission data receiving means for receiving transmission data from the terminal device to the server device;
Global address changing means for changing a local address of the terminal device set as a source address included in the transmission data to a global address stored in the first corresponding address storage means;
Transmission means for transmitting the transmission data changed by the global address changing means to the server side router device,
The server side router device is:
Second corresponding address storage means for storing the global address and local address of the terminal device in association with each other;
Transmission data receiving means for receiving transmission data transmitted from the transmission means;
Local address changing means for changing the global address of the terminal device set in the transmission source address included in the transmission data to a local address stored in the second corresponding address storage means;
Transmitting means for transmitting the transmission data changed by the local address changing means to the server device;
A communication network system. The server side router device is:
Reply data receiving means for receiving reply data returned from the server device;
A global address changing means for changing a local address of the terminal device set as a transmission destination address included in the reply data to a global address stored by the second corresponding address storage means;
A reply means for replying the reply data changed by the global address changing means to the router device on the terminal side,
The terminal-side router device is
Reply data receiving means for receiving the reply data;
Local address changing means for changing the destination address included in the reply data to the local address of the terminal device stored in the first corresponding address storage means;
A reply means for replying the reply data changed by the local address changing means to the terminal device;
The communication network system according to claim 1, further comprising: The terminal-side router device further includes address correspondence information transmitting means for transmitting address correspondence information associating a global address and a local address of the terminal device to the server-side router device,
The second corresponding address storage means of the server side router device,
3. The communication network system according to claim 1, wherein the address correspondence information transmitted by the address correspondence information transmission means is stored. The terminal-side router device is
A first connection means for connecting to a first network;
A second connection means for connecting to the second network when the first connection means fails to connect to the first network;
The communication network according to any one of claims 1 to 3, wherein the global address transmitted by the address correspondence information transmitting means is a global address for connecting to the first or second network. system. A computer of the terminal-side router device in a communication network system in which the terminal device and the server device are connected via the Internet via the terminal-side router device and the server-side router device, respectively.
Means for associating a local address and a global address of the terminal device and storing them in a first corresponding address storage means;
Global address changing means for changing a local address of the terminal device set as a transmission source address included in the transmission data to a global address stored by the first corresponding address storage means;
A function of the transmission data changed by the global address changing means as transmitting means for transmitting to the server side router apparatus, and causing the computer of the server side router apparatus to
Means for associating a global address and a local address of the terminal device and storing them in a second corresponding address storage means;
Transmission data receiving means for receiving transmission data transmitted from the transmission means;
Local address changing means for changing the global address of the terminal device set in the transmission source address included in the transmission data to a local address stored in the second corresponding address storage means;
Transmitting means for transmitting the transmission data changed by the local address changing means to the server device;
A computer-readable program designed to function as a computer. The server side router device computer,
Reply data receiving means for receiving reply data returned from the server device;
Global address changing means for changing a local address of the terminal device set as a transmission destination address included in the reply data to a global address stored in the second corresponding address storage means;
The reply data changed by the global address changing means is made to function as a reply means for returning to the terminal side router device,
A computer of the terminal side router device,
Reply data receiving means for receiving the reply data;
Local address changing means for changing a destination address included in the reply data to a local address of the terminal device stored in the first corresponding address storage means;
Reply means for replying the reply data changed by the local address changing means to the terminal device,
The computer-readable program according to claim 5, wherein the computer-readable program is made to function as:

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