JP2008148243A - Communication apparatus, communication system, communication method and communication program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform communication at layer-2 and layer-3 levels without requiring a terminal internal setting change between networks using the same IP address system to which a plurality of terminals are connected. <P>SOLUTION: When receiving an Ethernet(R) frame from an Ethernet(R) port 301, a frame identification unit 312 confirms a protocol type and classifies the frame. When the protocol type is IP, an IPDA translation unit 313 and an IPSA translation unit 314 translate a transmission destination IP address and a transmission source IP address by retrieving a virtual terminal table 318. When the protocol type is ARP, an ARPDA translation unit 315 and an ARPSA translation unit 316 translate transmission the destination IP address and the transmission source IP address included in ARP data by retrieving the virtual terminal table 318. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication device, a communication system, a communication method, and a communication program, and in particular, can communicate at a layer 2 and layer 3 level between networks using the same IP address system without requiring the internal setting change of each terminal. The present invention relates to a communication device, a communication system, a communication method, and a communication program.

  Networks using the same IP address system may be connected using a hub (HUB) or a switch. At this time, since it is necessary to assign a different IP address to each terminal, it is necessary to take care not to assign a common IP address, and strict management of the IP address is necessary.

  Conventionally, there is a method for enabling IP communication between networks using the same IP address system without requiring a change in the network address of the terminal. For example, there is a method in which NAT (Network Address Translation) routers connected to each network using the same IP address are arranged symmetrically. In the method using the NAT router of prior art 1, communication at the layer 3 level is possible between networks of the same IP address system by arranging the NAT routers symmetrically.

  Further, for example, Patent Document 1 discloses an IP conversion apparatus that allows communication between layers 2 and 3 between terminals using a common IP address. “Communicating between layer 2 and layer 3” means enabling communication at the layer 2 and layer 3 levels of the OSI basic reference model. The IP conversion apparatus assigns different address information to each Ethernet (registered trademark) port, and converts the source IP address and the destination IP address. By doing so, communication is possible even between terminals having a common default IP address held in advance. Therefore, the IP conversion device 5 described in Patent Document 1 enables communication at the layer 2 and layer 3 levels between terminals having a common IP address.

JP 2005-79672 A

  FIG. 10 is an explanatory diagram showing an example of a method of installing NAT routers connected symmetrically to each network using the same IP address. The operation of the NAT routers 41 and 42 shown in FIG. 10 will be described below.

  The NAT routers 41 and 42 are originally devices for enabling communication between a private network and a global network. For example, the NAT router 41 has an Ethernet port 401 connected to the private network and an Ethernet port 402 connected to the global network. The NAT router 42 has an Ethernet port 404 connected to the private network and an Ethernet port 403 connected to the global network. The NAT routers 41 and 42 have IP conversion tables 405 and 406 for performing IP conversion of received packets, respectively.

  The IP conversion tables 405 and 406 included in the NAT routers 41 and 42 include input port information of received packets and IP information of received packets in association with information after IP conversion.

  The NAT routers 41 and 42 receive packets including the global IP address as the transmission destination IP address (IPDA) and the private IP address as the transmission source IP address (IPSA) from the Ethernet ports 401 and 404. In this case, the NAT routers 41 and 42 refer to the IP conversion tables 405 and 406 to convert and transfer only the IPSA included in the packet.

  In contrast, the NAT routers 41 and 42 may receive packets including the private IP address as IPDA and the global IP address as IPSA from the Ethernet ports 402 and 473 connected to the global network. In this case, the NAT routers 41 and 42 refer to the IP conversion tables 405 and 406 to convert and transfer only the IPSA included in the packet.

  Hereinafter, an operation when an IP packet is transmitted from the terminal 911 to the terminal 921 will be described with reference to FIG. For example, when the terminal 911 transmits a packet to the destination terminal 921, the terminal 911 generates a packet including a global IP address (for example, 10.0.0.3) indicating the Ethernet port 403 of the NAT router 42 as the destination IP address. Transmit to the Ethernet port 401 of the router 41.

  When the NAT router 41 receives a packet from the Ethernet port 401, the NAT router 41 searches the IP conversion table 405 based on the input port number and IP address information included in the received packet. However, the NAT router 41 searches the IP conversion table 405 only once. Then, the NAT router 41 changes only the IPSA included in the received packet to a global IP address (for example, 10.0.0.1) and transmits it to the NAT router 42 via the Ethernet port 402.

  When receiving the packet from the Ethernet port 403, the NAT router 42 searches the IP conversion table 406 based on the input port included in the received packet and the IPDA information included in the received packet. However, the NAT router 42 searches the IP conversion table 406 only once. Then, the NAT router 42 changes only the IPDA included in the received packet to a private IP address (for example, 192.168.0.1), and transmits it to the destination terminal 921 via the Ethernet port 404.

  As described above, the NAT routers 41 and 42 convert only the source IP address (or only the destination IP address) included in the received packet. Then, when a network having the same IP address system is directly connected by one NAT router, the destination IP address (or source IP address) after the IP conversion becomes an address equivalent to the IP address of the destination terminal. there is a possibility. Therefore, the same IP network cannot be connected using one NAT router.

  In the method using the NAT router, in order to use a protocol other than the IP protocol, it is necessary to transfer an Ethernet frame having the MAC address of the destination terminal as MACDA using the NAT router. However, the NAT router can transfer only a frame having the MAC address addressed to its own node as MACDA. For this reason, an Ethernet frame having the MAC address of the destination terminal as MACDA is discarded by the NAT router. Accordingly, since layer 2 communication (communication at the layer 2 level) is not possible between networks using the same IP address, protocols other than the IP protocol (for example, AppleTalk, IPX, SNA) cannot be used.

  In the method using the NAT router, when the transmission source terminal transmits a packet to the transmission destination terminal, the packet including the IP address of the device (or port) to which the transmission destination terminal is connected as the transmission destination IP address. Must be generated and sent. However, the prior art 1 does not consider any method for obtaining the IP address. Therefore, even if the transmission source terminal wants to transmit an IP packet to the transmission destination terminal, the transmission destination IP address of the IP packet cannot be acquired by itself and cannot be directly connected to the transmission destination terminal.

  FIG. 11 is a block diagram showing an example of the configuration of a system using the IP conversion device described in Patent Document 1 and the like. Hereinafter, an outline of the IP conversion device disclosed in Patent Document 1 will be described with reference to FIG. As shown in FIG. 11, the system using the IP conversion device described in Patent Document 1 includes terminals 511 and 521 and an IP conversion device 5 that connects the terminals 511 and 521.

  The terminals 511 and 512 use the same IP address (for example, 192.168.0.1), and the MAC addresses of the terminals 511 and 512 are “A” and “B”, respectively.

  The IP conversion apparatus 5 connects a terminal 511 and a terminal 512 via Ethernet ports 501 and 502. In the IP converter 5, different IP addresses (for example, 192.168.0.11 and 192.168.0.12) are set for each Ethernet port. Further, the IP conversion device 5 includes an IP conversion table 503 that is referred to when performing IP conversion processing of a received packet.

  The IP conversion table 503 includes the IP address set for the port and the common IP address of the terminal in association with the Ethernet port number. For example, the entry corresponding to the Ethernet port 501 includes the IP address “192.168.0.11” set for the Ethernet port 501 and the common IP address “192.168.0.1” of the terminals 511 and 512. Similarly, the entry corresponding to the Ethernet port 502 includes the IP address “192.168.0.12” set for the Ethernet port 502 and the common IP address “192.168.0.1” of the terminals 511 and 512.

  Hereinafter, an operation of transmitting an IP packet from the terminal 511 to the transmission destination terminal 521 will be described.

  When the terminal 511 transmits an IP packet to the destination terminal 521, the terminal 511 transmits an IP packet including the IP address of the Ethernet port 502 of the IP conversion apparatus 5 to which the terminal 521 is connected as IPDA. For example, the terminal 511 transmits a packet including the IP address “192.168.0.12” of the Ethernet port 502 of the IP conversion device 5 as IPDA to the terminal 521.

  When receiving the packet, the IP conversion device 5 searches the IP conversion table 503 using the input port information included in the received packet. However, the IP conversion device 5 searches the IP conversion table 503 only once. Next, the IP converter 5 converts the IPSA included in the received packet based on the retrieved port IP address. Also, the IP conversion device 5 changes the IPDA included in the received packet based on the common IP address of the searched terminal.

  For example, when receiving a packet from the Ethernet port 51, the IP conversion device 5 searches for an entry corresponding to the reception port 501 included in the IP conversion table 503. The IP converter 5 acquires the port IP address “192.168.0.11” associated with the Ethernet port 501 and the common IP address “192.168.0.1” of the terminal, converts the IPSA and IPDA, and converts the terminal Transfer to 521.

  However, in a system using an IP conversion device, an IP address is set for each Ethernet port, and the IP address included in the received frame is converted based on the IP address set for the Ethernet port. When a plurality of terminals are connected to one Ethernet port, the destination IP address included in the IP packet transmitted from each terminal is converted to the same IP address. Therefore, communication between two or more terminals using the same IP address cannot be performed. Therefore, when a plurality of terminals are connected to one Ethernet port, communication between the terminals cannot be performed. Further, even if the transmission source terminal wants to transmit an IP packet to the transmission destination terminal, the transmission destination IP address included in the IP packet cannot be acquired by itself and cannot be directly connected to the transmission destination terminal.

  Therefore, the present invention provides a communication device provided between networks using the same IP address system, a communication device that enables communication at the layer 2 and layer 3 levels without requiring any change in internal settings of the terminal, and communication It is an object to provide a system, a communication method, and a communication program.

  In addition, the present invention provides a communication apparatus provided between networks using the same IP address system, even if a plurality of terminals are connected to one Ethernet port without requiring any change in the internal settings of the terminals. It is an object of the present invention to provide a communication device, a communication system, a communication method, and a communication program that enable communication.

  The present invention also provides an interface for a transmission source terminal to acquire a transmission destination IP address without requiring a change in the internal setting of the terminal in a communication apparatus provided between networks using the same IP address system. Another object of the present invention is to provide a communication device, a communication system, a communication method, and a communication program that allow a transmission source terminal to specify a transmission destination IP address by itself.

  A communication device according to the present invention is a communication device (for example, virtual terminal device 3) that relays communication between terminals connected to a network having the same IP address system, and is a first device connected to a first network. When the second terminal obtains an IP address on the first network side when the terminal (for example, the terminal 11) communicates with the second terminal (for example, the terminal 21) connected to the second network. A virtual address specifying unit (for example, realized by the setting unit 311) that specifies a virtual IP address that can be acquired in this case, and a virtual address that transmits the virtual IP address specified by the virtual address specifying unit to the first terminal When receiving data from the transmission means (for example, realized by the setting unit 311) and the first terminal, as a transmission source included in the received data Sending side address converting means (for example, IPSA converting unit 314) that converts the IP address of the first terminal into a virtual IP address that can be acquired when the first terminal acquires the IP address on the second network side. When the data is received from the first terminal, the virtual IP address of the second terminal as the transmission destination included in the received data is received by the second terminal in the second network. Receiving-side address conversion means (for example, realized by the IPDA conversion unit 313 and the ARPDA conversion unit 315).

  The communication device also includes an actual IP address used by the first terminal in the first network, a virtual IP address that can be acquired when the first terminal acquires an IP address on the second network side, and And the virtual IP address that can be acquired when the second terminal acquires the IP address on the first network side temporarily, and the actual IP address used by the second terminal in the second network And a virtual address table (for example, a virtual terminal table 318), and the transmission-side address conversion means is based on the virtual address correspondence table and includes the first terminal as the transmission source included in the received data. The IP address is converted into a virtual IP address, and the receiving side address converting means receives the data based on the virtual address correspondence table. The virtual IP address of the second terminal as a transmission destination included in the chromatography data, or may be converted to the real IP address of the second terminal.

  According to another aspect of the communication apparatus of the present invention, when connecting between networks having the same IP address system to which a plurality of terminals are connected, the terminals are not changed in layer 2 without changing the default IP address of the terminals. And means (for example, an IPDA conversion unit 313, an IPSA conversion unit 314, an ARPDA conversion unit 315, and an ARPSA conversion unit 316) that enable communication at the layer 3 level.

  Still another aspect of the communication device according to the present invention is connected to the first network when connecting the first network and the second network having the same IP address system to which a plurality of terminals are connected. A frame identification unit for identifying a protocol type of an Ethernet frame received from the first Ethernet port, and a transmission destination IP address of the IP packet of the Ethernet frame when the frame identification unit determines that the protocol type is an IP type. If the destination terminal acquires an IP address on the second network side, an IPDA conversion unit that converts the IP address to an IP address that can be acquired, and transmission of an IP packet when the frame identification unit determines that the protocol type is an IP type The source IP address is assumed to be the IP address of the source terminal on the second network side. The IPSA conversion unit that converts the IP address to an IP address that can be acquired when the address is acquired, and the frame identification unit that is included in the data field of the ARP packet of the received Ethernet frame when the protocol type is determined to be the ARP type The ARPDA converter that converts the destination IP address to an IP address that can be acquired when the destination terminal acquires the IP address on the second network side, and the frame identification unit has determined that the protocol type is the ARP type A source IP address included in the data field of the ARP packet is converted to an IP address that can be acquired when the source terminal temporarily acquires the IP address on the second network side; Ethernet frame received, Ethernet Characterized by comprising a frame control unit for transferring a port other than input port receiving the frame.

  Further, the communication device uses the first Ethernet port connected to the first network and the default IP address of the first terminal connected to the first network, so that the first terminal is the second one. If the IP address is acquired on the network side, the IP address that can be acquired is included in association with the second terminal connected to the first Ethernet port and the second network on the first network side. The virtual terminal table includes the IP address that can be acquired when the IP address is acquired in association with the default IP address of the second terminal, and the IPDA conversion unit includes the input port of the received frame, Based on the search result of the virtual terminal table using the destination IP address information included in the received frame. Then, the destination IP address information is converted, and the ARPDA conversion unit uses the input port of the received frame and the destination IP address information included in the received frame, based on the result of searching the virtual terminal table, The destination IP address information is converted, and the IPSA conversion unit uses the input port of the received frame and the source IP address information included in the received frame, based on the result of searching the virtual terminal table, The IP address information is converted, and the ARPSA conversion unit uses the input port of the received frame and the source IP address information included in the received frame to search for the source IP address based on the search result of the virtual terminal table. The information may be converted.

  The communication apparatus also includes a setting unit having an interface for searching a virtual terminal table by CGI or GUI using a fixed IP address. The setting unit sets a virtual terminal table and sets a destination IP address from a source terminal. In response to the inquiry, the virtual terminal table may be searched and responded to the transmission source terminal.

  Further, when the communication apparatus determines that the first Ethernet port connected to the first network and the second terminal connected to the second network acquire an IP address on the first network side. An IPDA conversion table including the second Ethernet port connecting the second network and the default IP address of the second terminal in association with each other using the obtainable IP address, the first Ethernet port, and the first It can be acquired when the first terminal temporarily acquires an IP address on the second network side using the default IP address of the first terminal connected to the network and the second Ethernet port. An IPSA conversion table including IP addresses in association with each other, and an IPDA conversion unit is provided for input ports and received frames. Based on the result of searching the IPDA conversion table using the existing destination IP address, the destination IP address information is converted and the output port is acquired. The ARPDA conversion unit converts the input port and the received frame into Based on the result of searching the IPDA conversion table using the included destination IP address, the destination IP address information is converted and the output port is acquired, and the IPSA conversion unit receives the input port in the received frame. And the source IP address information included in the output port and the received frame, the source IP address information is converted based on the result of searching the IPSA conversion table, and the ARPSA conversion unit Source IP address information included in input port, output port and received frame With, based on the result of searching the IPSA conversion table, converts the source IP address information, the frame control unit may be configured to forward the received frame to the output port.

  A communication system according to the present invention is a communication system that performs communication between terminals connected to a network having the same IP address system, and includes a communication device that relays communication between the terminals. Acquired when the first terminal connected to the network communicates with the second terminal connected to the second network and the second terminal temporarily acquires an IP address on the first network side. A virtual address specifying means for specifying a virtual IP address, a virtual address transmitting means for transmitting the virtual IP address specified by the virtual address specifying means to the first terminal, and receiving data when receiving data from the first terminal. When the first terminal obtains the IP address of the first terminal on the second network side as the transmission source included in When receiving the data from the first terminal and the transmission side address conversion means for converting into an obtainable virtual IP address, the second terminal determines the virtual IP address of the second terminal as the transmission destination included in the received data. Receiving side address converting means for converting into an actual IP address used in the second network, and the first terminal transmits data including the virtual IP address received from the communication device as a transmission destination to the communication device. It is characterized by.

  The communication method according to the present invention is a communication method for performing communication between terminals connected to a network having the same IP address system, and a communication device that relays communication between the terminals is connected to the first network. When the first terminal communicates with the second terminal connected to the second network, the virtual IP address that can be acquired when the second terminal temporarily acquires the IP address on the first network side A step of specifying, a step in which the communication device transmits the specified virtual IP address to the first terminal, and data including, as a transmission destination, the virtual IP address received by the first terminal from the communication device. And when the communication device receives data from the first terminal, the IP address of the first terminal as the transmission source included in the received data is set to the first terminal. If the communication device receives data from the first terminal, the communication device receives data from the first terminal as a transmission destination included in the received data. Converting the virtual IP address of the second terminal into an actual IP address used by the second terminal in the second network.

  In another aspect of the communication method according to the present invention, the first network having the same IP address system to which a plurality of terminals are connected and the second network are connected to the first network. Is a communication method for relaying communication between a terminal connected to a second network and a terminal connected to the second network, and when receiving an Ethernet frame from the first Ethernet port connected to the first network, the protocol of the received frame When the type is identified and the protocol type is determined to be the IP type, the transmission destination IP address of the IP packet of the Ethernet frame can be acquired if the transmission destination terminal temporarily acquires the IP address on the second network side Send IP packet when converted to IP address and protocol type is determined to be IP type The IP address is converted to an IP address that can be acquired if the source terminal acquires the IP address on the second network side, and the ARP packet of the received Ethernet frame is determined when the protocol type is determined to be the ARP type. The destination IP address included in the data field is converted into an IP address that can be acquired when the destination terminal temporarily acquires an IP address on the second network side, and the protocol type is determined to be the ARP type. In this case, the source IP address included in the data field of the ARP packet is converted into an IP address that can be acquired when the source terminal temporarily acquires an IP address on the second network side, and the received Ethernet Frame from the input port that received the Ethernet frame. Characterized by transfer ports.

  According to still another aspect of the communication method of the present invention, when a first network having the same IP address system to which a plurality of terminals are connected and a second network are connected, the communication method is connected to the first network. A communication method for relaying communication between a terminal connected to a second network and a terminal connected to the second network, the first Ethernet port connected to the first network, and the first network connected to the first network The first Ethernet port includes an IP address that can be acquired when the first terminal acquires an IP address on the second network side using the default IP address of the first terminal in association with the first Ethernet port. Can be acquired when the second terminal connected to the second network acquires an IP address on the first network side. A virtual terminal table including the default IP address of the second terminal in association with the P address is stored in advance, and a CGI or GUI user having a fixed IP address is used to search the virtual terminal table. In response to an inquiry about the destination IP address from the source terminal, the virtual terminal table is searched and responded to the source terminal, and an Ethernet frame is received from the first Ethernet port connected to the first network. When the protocol type of the received Ethernet frame is identified and the protocol type is determined to be the IP type, the virtual terminal is used by using the input port of the received Ethernet frame, the destination IP address and the source IP address information. Results of searching the table When the transmission destination IP address and the transmission source IP address are converted based on the protocol, and the protocol type is determined to be the ARP type, the input port of the received Ethernet frame and the transmission destination included in the data field of the ARP packet Based on the search result of the virtual terminal table using the IP address and the source IP address, the destination IP address and the source IP address are converted, and the received Ethernet frame is other than the input port that received the Ethernet frame. It transfers to the port of this.

  According to still another aspect of the communication method of the present invention, when a first network having the same IP address system to which a plurality of terminals are connected and a second network are connected, the communication method is connected to the first network. A communication method for relaying communication between a terminal connected to a second network and a terminal connected to a second network, wherein the first Ethernet port connected to the first network and the second network are connected When the second terminal acquires an IP address on the first network side, the IP address that can be acquired is used to correspond to the Ethernet port connecting the second network and the default IP address of the second terminal. A pre-stored IPDA conversion table including the first Ethernet port and the first network connected to the first network Using the default IP address at the end and the Ethernet port that connects the second network, the IP address that can be acquired when the first terminal acquires an IP address on the second network side is associated with The virtual terminal table is searched for the destination IP address inquiry from the source terminal using the interface for virtual terminal table search by CGI or GUI using the fixed IP address. When the Ethernet frame is received from the first Ethernet port connected to the first network in response to the transmission source terminal, the protocol type of the received Ethernet frame is identified, and the protocol type is determined to be the IP type The received Ethernet frame. Based on the result of searching the IPDA conversion table and the IPSA conversion table, the destination IP address and the source IP address of the IP packet of the Ethernet frame are obtained using the input port of the system, the destination IP address, and the source IP address information. When the IP address is converted and the protocol type is determined to be the ARP type, the IPDA conversion table is obtained using the input port of the received Ethernet frame and the destination IP address and the source IP address included in the data field of the ARP packet. Based on the result of searching the IPSA conversion table, the destination IP address and the source IP address included in the data field of the ARP packet are converted, and the received Ethernet frame other than the input port that received the Ethernet frame is converted. Forward to other ports It is characterized by doing.

  A communication program according to the present invention is a communication program for relaying communication between terminals connected to a network having the same IP address system, and a first terminal connected to a first network is connected to a computer. A process for specifying a virtual IP address that can be acquired when the second terminal acquires an IP address on the first network side when communicating with a second terminal connected to the second network; When the specified virtual IP address is transmitted to the first terminal and data is received from the first terminal, the first terminal determines the IP address of the first terminal as the transmission source included in the received data. If the IP address is acquired on the second network side, the virtual IP address can be acquired and the data is received from the first terminal. , The virtual IP address of the second terminal as a transmission destination included in the received data, the second terminal is for executing a process of converting the real IP address used in the second network.

  In another aspect of the communication program according to the present invention, when the first network having the same IP address system to which a plurality of terminals are connected and the second network are connected, the communication program is connected to the first network. A communication program for relaying communication between a terminal connected to a second network and a terminal connected to the second network, wherein the computer receives an Ethernet frame from the first Ethernet port connected to the first network The process of identifying the protocol type of the received frame, and if the protocol type is determined to be the IP type, the destination IP address of the IP packet of the Ethernet frame is temporarily acquired by the destination terminal on the second network side If so, the process of converting to an IP address that can be acquired, and the protocol type Is converted to an IP address that can be acquired when the source terminal temporarily acquires an IP address on the second network side, and a protocol type Is determined as the ARP type, the transmission destination IP address included in the data field of the ARP packet of the received Ethernet frame is acquired when the transmission destination terminal temporarily acquires the IP address on the second network side. When the process is converted to a possible IP address, and the protocol type is determined to be the ARP type, the source IP address included in the data field of the ARP packet is temporarily set by the source terminal on the second network side. If it is acquired, it will be converted into an IP address that can be acquired, and The Ethernet frame is intended for executing the process of transferring a port other than input port receiving an Ethernet frame.

  In another aspect of the communication program according to the present invention, when the first network having the same IP address system to which a plurality of terminals are connected and the second network are connected, the communication program is connected to the first network. A communication program for relaying communication between a terminal connected to a second network and a terminal connected to the second network, the computer having a first Ethernet port connected to the first network, and a first network The IP address that can be acquired when the first terminal acquires an IP address on the second network side using the default IP address of the connected first terminal is associated and included. The second terminal connected to the first Ethernet port and the second network is assumed to have an IP address on the first network side. A process of storing in advance a virtual terminal table including the default IP address of the second terminal in association with the IP address that can be acquired when it is acquired, and a user using a CGI or GUI having a fixed IP address is virtual In response to an inquiry about the destination IP address from the source terminal using the interface for searching the terminal table, processing for searching the virtual terminal table and responding to the source terminal, and connection to the first network When receiving an Ethernet frame from the first Ethernet port, processing for identifying the protocol type of the received Ethernet frame, and when the protocol type is determined to be an IP type, the input port of the received Ethernet frame and the destination IP Address and source IP address And processing of converting the destination IP address and the source IP address based on the result of searching the virtual terminal table using the less information, and when the protocol type is determined to be the ARP type, the received Ethernet frame Based on the search result of the virtual terminal table using the input port and the destination IP address and source IP address included in the data field of the ARP packet, the destination IP address and the source IP address are converted. And a process of transferring the received Ethernet frame to a port other than the input port that received the Ethernet frame.

  Still another aspect of the communication program according to the present invention is connected to the first network when connecting the first network having the same IP address system to which a plurality of terminals are connected and the second network. A communication program for relaying communication between a terminal connected to a second network and a terminal connected to the second network, wherein the computer has a first Ethernet port connected to the first network, and a second network If the second terminal connected to the network acquires the IP address on the first network side, the IP address that can be acquired and the Ethernet port for connecting the second network and the second terminal A process for storing an IPDA conversion table including a default IP address in association with each other; a first Ethernet port; When the first terminal obtains an IP address on the second network side using the default IP address of the first terminal connected to the first network and the Ethernet port connecting the second network In this case, the destination from the transmission source terminal using the processing for storing the IPSA conversion table including the IP address that can be acquired in advance and the interface for searching the virtual terminal table by CGI or GUI using the fixed IP address In response to an IP address inquiry, a process of searching the virtual terminal table and responding to the source terminal, and an Ethernet frame received when receiving an Ethernet frame from the first Ethernet port connected to the first network Process to identify the protocol type of the When it is determined that the col type is an IP type, the IP address of the Ethernet frame is determined based on the result of searching the IPDA conversion table and the IPSA conversion table using the input port of the received Ethernet frame, the destination IP address, and the source IP address information. Processing for converting the transmission destination IP address and the transmission source IP address of the packet, and when the protocol type is determined to be the ARP type, the input port of the received Ethernet frame and the transmission destination IP included in the data field of the ARP packet Based on the result of searching the IPDA conversion table and the IPSA conversion table using the address and the source IP address, the destination IP address and the source IP address included in the data field of the ARP packet are converted. Processing and received And a process of transferring the Ethernet frame to a port other than the input port that received the Ethernet frame.

  The first communication device according to the present invention receives an Ethernet received from a first Ethernet port connected to the first network when connecting the first network and the second network having the same IP address system. Frame identification unit that identifies the protocol type of the frame, and if the protocol type is determined to be IP type, the destination IP address of the IP packet of the Ethernet frame is temporarily acquired by the destination terminal on the second network side In this case, the IPDA conversion unit that converts the IP address to an IP address that can be acquired, and the IP address that can be acquired when the source terminal temporarily acquires the IP address on the second network side. IPSA converter that converts to ARP type and protocol type as ARP type In this case, the transmission destination IP address included in the data field of the ARP packet of the received Ethernet frame is changed to an IP address that can be acquired when the transmission destination terminal temporarily acquires an IP address on the second network side. The ARPDA conversion unit to be converted and the source IP address included in the data field of the ARP packet are converted to an IP address that can be acquired when the source terminal temporarily acquires an IP address on the second network side. An ARPSA converter and a frame controller that transfers the received Ethernet frame to a port other than the input port that received the Ethernet frame.

  By adopting the configuration as described above, communication at the layer 2 and layer 3 levels can be performed using a communication device provided between networks using the same IP address system, without needing to change the internal settings of the terminal. And the first object of the present invention can be achieved.

  The second communication device of the present invention is connected to the first network when connecting the first network having the same IP address system to which a plurality of terminals are connected and the second network. Available when the first terminal obtains an IP address on the second network side using the Ethernet port of 1 and the default IP address of the first terminal connected to the first network. IP addresses that can be acquired when the second terminal connected to the first Ethernet port and the second network acquires an IP address on the first network side, in association with the corresponding IP address. The virtual terminal table including the default IP address of the second terminal in association with each other, the input port of the received frame, and the reception An IPDA conversion unit and an ARPDA conversion unit for converting the destination IP address information based on the search result of the virtual terminal table using the destination IP address information included in the frame; an input port of the received frame; Based on the search result of the virtual terminal table using the source IP address information included in the received frame, an IPSA converter and an ARPSA converter for converting the source IP address information, and the received Ethernet frame A frame control unit that transfers the Ethernet frame to a port other than the input port that received the Ethernet frame.

  By adopting the above configuration, communication between terminals is possible even when multiple terminals are connected to one Ethernet port using a communication device provided between networks using the same IP address system. And the second object of the present invention can be achieved.

  The third communication device of the present invention provides an interface for searching a virtual terminal table by CGI or GUI using a fixed IP address when connecting a first network and a second network having the same IP address system. A virtual terminal table, and a setting unit that searches the virtual terminal table and responds to the source terminal in response to an inquiry about the destination IP address from the source terminal, and is connected to the first network A frame identification unit for identifying a protocol type of an Ethernet frame received from the first Ethernet port, and a destination IP address of the IP packet when the protocol type is determined to be an IP type, the destination terminal is on the second network side IP address that can be acquired if IP address is acquired in An IPDA converter that converts the IP packet source IP address to an IP address that can be acquired when the source terminal temporarily acquires an IP address on the second network side, When it is determined that the protocol type is the ARP type, and the destination IP address included in the data field of the ARP packet of the received Ethernet frame is temporarily acquired by the destination terminal on the second network side The ARPDA conversion unit that converts the IP address to an IP address that can be acquired by the client and the source IP address included in the data field of the ARP packet when the source terminal temporarily acquires the IP address on the second network side An ARPSA conversion unit that converts the IP address to a possible IP address and the received Ethernet The Ttofuremu, and a frame controller for transferring a port other than input port receiving an Ethernet frame.

  By adopting the configuration as described above, a communication device provided between networks using the same IP address system is used to provide an interface for a transmission source terminal to acquire a transmission destination IP address. The terminal can specify the transmission destination IP address by itself, and the third object of the present invention can be achieved.

  According to the present invention, in communication between terminals connected to a network having the same IP address system, a virtual IP address that can be acquired when the second terminal temporarily acquires an IP address on the first network side. Is transmitted to the first terminal. In addition, when data is received from the first terminal, when the first terminal acquires the IP address of the first terminal as the transmission source included in the received data on the second network side. The virtual IP address is converted into an obtainable virtual IP address, and the virtual IP address of the second terminal as the transmission destination included in the received data is converted into an actual IP address used by the second terminal in the second network. Therefore, in communication apparatuses provided between networks using the same IP address system, communication at the layer 2 and layer 3 levels can be performed without the need to change the internal settings of the terminals.

  According to the present invention, a communication device is provided between networks using the same IP address system. The communication device receives not only the Ethernet frame addressed to the own node from the first network but all the Ethernet frames transmitted to the second network. The frame identification unit identifies the type of the received Ethernet frame.

  When the protocol type is IP, the IPDA conversion unit converts the transmission destination IP address into an IP address that can be acquired when the transmission destination terminal temporarily acquires the IP address on the second network side. The IPSA conversion unit converts the source IP address into an IP address that can be acquired when the source terminal temporarily acquires an IP address on the second network side.

  When the protocol type is ARP, the ARPDA conversion unit obtains the transmission destination IP address included in the ARP data when the transmission destination terminal temporarily obtains the IP address on the second network side. Convert to Further, the ARPSA conversion unit converts the transmission source IP address into an IP address that can be acquired when the transmission source terminal temporarily acquires the IP address on the second network side.

  Then, the frame control unit transfers each converted Ethernet frame to a port other than the input port.

  Therefore, communication at the layer 2 and layer 3 levels can be performed using a communication device provided between networks using the same IP address system, without the need to change the internal settings of the terminal.

  According to the present invention, a communication device is provided between networks using the same IP address system to which a plurality of terminals are connected. The communication device does not convert the IP address of the received frame itself based on the IP address set in the Ethernet port, but manages a virtual IP address when each terminal performs communication. Therefore, a virtual terminal table is used. The virtual terminal table includes an Ethernet port and a default IP address of a terminal connected to the first network in association with an IP address that the terminal can acquire in the second network, and further includes an Ethernet port And a second terminal connected to the second network, using an IP address that can be acquired in the first network, and a table including the default IP address of the second terminal in association with each other.

  The IPDA conversion unit and the ARPDA conversion unit convert the destination IP address information based on the search result of the virtual terminal table using the input port of the received frame and the destination IP address information included in the received frame. To do. Further, the IPSA conversion unit and the ARPSA conversion unit use the input port of the received frame and the source IP address information included in the received frame, based on the result of searching the virtual terminal table, for the source IP address information Convert.

  Therefore, communication between terminals can be performed even when a plurality of terminals are connected to one Ethernet port by using a communication device provided between networks using the same IP address system.

  Further, according to the present invention, a communication device is provided between networks using the same IP address system. The setting unit of the communication apparatus has an interface such as CGI or GUI using a fixed IP address. Further, the setting unit has means for searching the virtual terminal table and responding to the source terminal in response to the inquiry about the destination IP address from the source terminal.

  Therefore, using a communication device provided between networks using the same IP address system, the transmission source terminal provides an interface for acquiring the transmission destination IP address, and the transmission source terminal assigns the transmission destination IP address to itself. Can be specified.

Embodiment 1 FIG.
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of a network system using a communication apparatus according to the present invention. As shown in FIG. 1, the network system includes a network 1, a network 2, and a virtual terminal device 3. In the present embodiment, the communication device is specifically realized by the virtual terminal device 3.

  In the present embodiment, the networks 1 and 2 are networks having the same IP address system. For example, it is assumed that the IP address system of the network 1 and the IP address system of the network 2 are both “192.168.0.1/24”.

  The network 1 includes terminals 11 and 12. The IP addresses of the terminal 11 and the terminal 12 are “192.168.0.1” and “192.168.0.2”, respectively. Although FIG. 1 shows a case where the network 1 includes two terminals 11 and 12, the number of terminals is not limited to two. For example, the network 1 may include three or more terminals. The terminals 11 and 12 are specifically realized by an information processing terminal such as a personal computer.

  The network 2 includes terminals 21 and 22. Further, it is assumed that the IP addresses of the terminal 21 and the terminal 22 are “192.168.0.1” and “192.168.0.2”, respectively. Although FIG. 1 shows a case where the network 2 includes two terminals 21 and 22, the number of terminals is not limited to two. For example, the network 2 may include three or more terminals. The terminals 21 and 22 are specifically realized by an information processing terminal such as a personal computer.

  The virtual terminal device 3 performs virtual address conversion for each terminal connected to a plurality of networks having the same IP address system, as if the virtual terminal device 3 has different addresses. It is a device that enables communication between terminals at the layer 2 and layer 3 levels. The virtual terminal device 3 is realized by a network device such as a router, for example. The virtual terminal device 3 may be realized by an information processing device such as a personal computer that operates according to a program.

  In this embodiment, since the network 1 and the network 2 have the same IP address system, for example, the terminal 11 connected to the network 1 and the terminal 21 connected to the network 2 are both the same IP address. It has “192.168.0.1”. Similarly, for example, the terminal 12 connected to the network 1 and the terminal 22 connected to the network 2 both have the same IP address “192.168.0.2”. Therefore, since the IP addresses are duplicated as it is, communication between the terminals 11 and 12 connected to the network 1 and the terminals 21 and 22 connected to the network 2 cannot be performed.

  In the present embodiment, the virtual terminal device 3 is used in the network 1 when the terminals 21 and 22 connected to the network 2 are viewed from the terminals 11 and 12 connected to the network 1, for example. Virtual address conversion is performed as if the terminals 21 and 22 have IP addresses that have not been assigned (for example, “192.168.0.3” or “192.168.0.4”). By doing so, in the present embodiment, communication between networks 1 and 2 having the same IP address system is possible.

  FIG. 2 is a block diagram illustrating an example of the configuration of the virtual terminal device 3. As shown in FIG. 2, the virtual terminal device 3 includes Ethernet ports 301 and 302, a setting unit 311, a frame identification unit 312, an IPDA conversion unit 313, an IPSA conversion unit 314, an ARPDA conversion unit 315, an ARPSA conversion unit 316, and a frame control. Part 317 and virtual terminal table 318.

  The Ethernet port 301 is an interface unit connected to the network 1. In the virtual terminal device 3, the frame received from the Ethernet port 301 is transferred to the frame identification unit 312. A frame transmitted (output) from the frame control unit 317 to the Ethernet port 301 is transferred to the network 1 via the Ethernet port 301. That is, the virtual terminal device 3 transmits a frame (data) to the terminals 11 and 12 connected to the network 1 using the Ethernet port 301.

  The Ethernet port 302 is an interface unit that connects to the network 2. In the virtual terminal device 3, the frame received from the Ethernet port 302 is transferred to the frame identification unit 312. A frame transmitted (output) from the frame control unit 317 to the Ethernet port 302 is transferred to the network 2 via the Ethernet port 302. That is, the virtual terminal device 3 transmits frames (data) to the terminals 21 and 22 connected to the network 2 using the Ethernet port 302.

  The setting unit 311 has an interface such as CGI or GUI. For example, the setting unit 311 displays a setting screen using CGI or GUI on a display unit such as a monitor. In addition, the user performs a setting operation of the virtual terminal device 3 while viewing the setting screen using the CGI or GUI. Then, the setting unit 311 may set the virtual terminal table 318 in accordance with a user setting operation.

  The setting unit 311 has an IP address (for example, 192.168.0.254). In this case, the user terminal (terminal 11, 12, 21, 22) designates the IP address of the setting unit 311 and displays an interface such as CGI or GUI (for example, information on the virtual terminal table 318). ) To obtain the IP address of the destination terminal.

  That is, the setting unit 311 connects the terminals 11 and 12 connected to the network 1 (or the terminals 21 and 22 connected to the network 2) to the terminals 21 and 22 connected to the second network 2 (or the network 1). When communicating with the terminals 11 and 12, the virtual IP addresses that can be acquired when the terminals 21 and 22 (or the terminals 11 and 12) acquire an IP address on the network 1 (or network 2) side are specified. It has a function. The setting unit 311 has a function of transmitting the specified virtual IP address to the terminals 11 and 12 (or the terminals 21 and 22). For example, the setting unit 311 extracts the IP address of the destination terminal from the virtual terminal table 318 in response to a request from the terminals 11, 12, 21, and 22, and sends it to the requesting terminals 11, 12, 21, and 22. A function to transmit is provided.

  When transmitting an IP packet to the user terminal, the setting unit 311 converts the input port of the frame received from the user terminal to another port (a port other than the input port), and transmits the frame to the frame control unit 317 together with the transmission frame. (Output) function is provided.

  The frame identification unit 312 has a function of analyzing frames received from the Ethernet ports 301 and 302. In this case, first, the frame identification unit 312 determines whether or not an IP header is included in the received frame. When the IP header is included, the frame identifying unit 312 transfers the received frame to the setting unit 311 if the IPDA included in the received frame is the same as the IP address of the setting unit 311. If the IP address is other than the IP address of the setting unit 311, the frame identification unit 312 transmits (outputs) the received frame to the IPDA conversion unit 313 together with the input port information of the received frame.

  When the IP header is not included, the frame identification unit 312 detects the type information of the received frame. When the type information indicates ARP (Address Resolution Protocol), the frame identification unit 312 controls the received frame together with the input port information of the received frame. To the unit 315. In the case of a frame other than a frame having type information indicating ARP, the frame identifying unit 312 transmits (outputs) the received frame to the frame control unit 317 together with the input port information of the received frame.

  The IPDA conversion unit 313 has a function of acquiring (extracting) IPDA information based on the IP header of a frame received (input) from the frame identification unit 312. The IPDA conversion unit 313 has a function of searching the virtual terminal table 318 based on the acquired IPDA information and the input port information of the received frame. The IPDA conversion unit 313 has a function of converting the IPDA information of the received frame using the search result of the virtual terminal table 318. The IPDA conversion unit 313 has a function of transferring the received frame to the IPSA conversion unit 314 together with the input port information of the received frame after the conversion. That is, when data is received from the IPDA conversion unit 313 and the terminals 11 and 12 (or terminals 21 and 22), the virtual IP addresses of the terminals 21 and 22 (or terminals 11 and 12) as transmission destinations included in the received data are The terminal 21 or 22 (or the terminal 11 or 12) has a function of converting into an actual IP address used in the network 2 (or network 1).

  The IPSA conversion unit 314 has a function of acquiring (extracting) IPSA information based on the IP header of a frame received (input) from the IPDA conversion unit 313. The IPSA conversion unit 314 has a function of searching the virtual terminal table 318 based on the acquired IPSA information and the input port information of the received frame. The IPSA conversion unit 314 has a function of converting the IPSA information of the received frame using the search result of the virtual terminal table 318. The IPSA conversion unit 314 has a function of transferring the received frame to the frame control unit 317 together with the input port information of the received frame after the conversion. That is, when the IPSA conversion unit 314 receives data from the terminals 11 and 12 (or the terminals 21 and 22), the IP address of the terminals 11 and 12 (or the terminals 21 and 22) as the transmission source included in the received data is When the terminals 11 and 12 (or the terminals 21 and 22) acquire an IP address on the network 2 (or network 1) side, the terminal 11 and 12 (or the terminals 21 and 22) have a function of converting to a virtual IP address that can be acquired.

  The ARPDA conversion unit 315 has a function of acquiring (extracting) IPDA information from the ARP data based on the ARP data portion of the frame received (input) from the frame identification unit 312. Further, the ARPDA conversion unit 315 has a function of searching the virtual terminal table 318 based on the acquired IPDA information and the input port information of the received frame. Further, the ARPDA conversion unit 315 has a function of converting IPDA information in the ARP data of the received frame using the search result of the virtual terminal table 318. The ARPDA converter 315 has a function of transferring the received frame to the ARPSA converter 316 together with the input port information of the received frame after the conversion. That is, when data is received from the IPDA conversion unit 313 and the terminals 11 and 12 (or terminals 21 and 22), the virtual IP addresses of the terminals 21 and 22 (or terminals 11 and 12) as transmission destinations included in the received data are The terminal 21 or 22 (or the terminal 11 or 12) has a function of converting into an actual IP address used in the network 2 (or network 1).

  The ARPSA conversion unit 316 has a function of acquiring (extracting) IPSA information from the ARP data based on the ARP data portion of the frame received (input) from the ARPDA conversion unit 315. In addition, the ARPSA conversion unit 316 has a function of searching the virtual terminal table 318 based on the acquired IPSA information and the input port information of the received frame. Further, the ARPSA conversion unit 316 has a function of converting IPSA information in the ARP data of the received frame using the search result of the virtual terminal table 318. The ARPSA converter 316 has a function of transferring the received frame to the frame controller 317 together with the input port information of the received frame after the conversion. That is, when the IPSA conversion unit 314 receives data from the terminals 11 and 12 (or the terminals 21 and 22), the IP address of the terminals 11 and 12 (or the terminals 21 and 22) as the transmission source included in the received data is When the terminals 11 and 12 (or the terminals 21 and 22) acquire an IP address on the network 2 (or network 1) side, the terminal 11 and 12 (or the terminals 21 and 22) have a function of converting to a virtual IP address that can be acquired.

  The frame control unit 317 has a function of transferring a frame received (input) from the setting unit 311, the frame identification unit 312, the IPSA conversion unit 314 conversion unit, the ARPSA conversion unit 316, or the like to a port other than the input port that received the received frame. Is provided. For example, when the received frame is data received at the Ethernet port 301, the frame control unit 317 transfers the received frame to the Ethernet port 302. For example, when the received frame is data received at the Ethernet port 302, the frame control unit 317 transfers the received frame to the Ethernet port 301.

  Specifically, the virtual terminal table 318 is stored in a storage device (not shown) such as a memory or a hard disk device provided in the virtual terminal device 3. FIG. 3 is an explanatory diagram showing an example of the virtual terminal table 318. As shown in FIG. 3, the virtual terminal table 318 includes the input port of the received frame, the original IP address information (IP address before conversion) of the received frame, and new IP address information (IP address after conversion). Include in correspondence.

  That is, the virtual terminal table 318 corresponds to the actual IP address used by the terminals 11 and 12 in the network 1 and the virtual IP address that can be acquired when the terminals 11 and 12 acquire the IP address temporarily on the network 2 side. In addition, the actual IP address used by the terminals 21 and 22 in the network 2 and the virtual IP address that can be acquired if the terminals 21 and 22 acquire the IP address on the network 1 side are associated with each other. . Based on the virtual terminal table 318, the IPSA conversion unit 314 and the ARPSA conversion unit 316 convert the IP addresses of the terminals 11 and 12 (or the terminals 21 and 22) included in the received data into virtual IP addresses. To do. Further, the IPDA conversion unit 313 and the ARPDA conversion unit 315 convert the virtual IP addresses of the terminals 21 and 22 (or the terminals 11 and 12) as the transmission destination included in the received data based on the virtual terminal table 318 to the terminals 21 and 21. 22 (or terminals 11 and 12) are converted into actual IP addresses.

  In the present embodiment, in the virtual terminal table 318, the IPDA conversion unit 313, the IPSA conversion unit 314, the ARPDA conversion unit 315, and the ARPSA conversion unit 316 perform processing for converting the IP header of the received frame or the IP information of the ARP data. Used when. The virtual terminal table 318 is created based on information of the networks 1 and 2 and the terminals 11, 12, 13, 14 registered in advance by an administrator who manages the network system using the virtual terminal device 3, for example. And stored in the storage device of the virtual terminal device 3. Further, for example, the virtual terminal table 318 is generated by the virtual terminal device 3 based on the information of the networks 1 and 2 and the terminals 11, 12, 13, and 14 registered in advance and stored in the storage device of the virtual terminal device 3. It may be stored.

  Hereinafter, the table configuration of the IP translation table (virtual terminal table) 318 will be described with reference to FIGS.

  As shown in FIG. 3, the IP conversion table (virtual terminal table) 318 includes a keyword field and a field after IP conversion. The keyword field of the IP conversion table 318 includes input port information (the port that received the received frame) and original IP information (an IP address originally included in the received frame).

  In FIG. 3, in the field of the original IP address for the input port (Ethernet port) 301, the IP addresses of the terminals 11 and 12 connected to the network 1 on the Ethernet port 301 side are set (1 in FIG. 3). (See first and second record). In the field of the original IP address for the input port 301, the IP that can be acquired when the terminals 21 and 22 connected to the network 2 on the Ethernet port 302 side acquire the IP address on the network 1 side temporarily. Addresses are set (see the third and fourth records in FIG. 3).

  For example, in the original IP address field, the IP addresses “192.168.0.1” and “192.168.0.2” of the terminals 11 and 12 connected to the network 1 are set as the original IP information regarding the input port 301. Yes. In the field of the original IP address, as the original IP information regarding the input port 301, the IP addresses “192.168.0.3” and “192.168. 0.4 "is set.

  Further, as shown in FIG. 3, in the post-IP conversion field corresponding to the input port information and the original IP address “192.168.0.1 to 192.168.0.4”, the terminals 11 and 12 connected to the network 1 are displayed. IP addresses “192.168.0.3” and “192.168.0.4” that can be acquired when the IP address is temporarily acquired on the network 2 side are set. Also, the IP addresses “192.168.0.1” and “192.168.0.2” of the terminals 21 and 22 connected to the network 2 are set.

  Similarly, in FIG. 3, the IP address of the terminals 21 and 22 connected to the network 2 on the Ethernet port 302 side is set in the entry related to the input port (Ethernet port) 302 (the fifth item in FIG. 3). And the sixth record). In the entry related to the input port 302, an IP address that can be acquired when the terminals 11 and 12 connected to the network 1 on the Ethernet port 301 side acquire an IP address on the network 2 side is set. (Refer to the seventh and eighth records in FIG. 3).

  For example, the IP addresses “192.168.0.1” and “192.168.0.2” of the terminals 21 and 22 connected to the network 2 are set in the original IP information field regarding the input port 302. In the field of the original IP information related to the input port 302, IP addresses “192.168.0.3” and “192.168.0.4” that can be obtained by the network 11 by the terminals 11 and 12 connected to the network 1 are set. Yes.

  Further, as shown in FIG. 3, in the post-IP conversion field corresponding to the IP addresses “192.168.0.1 to 192.168.0.4”, the terminals 21 and 22 connected to the terminal network 2 are connected to the network 1 side. If IP addresses are acquired, IP addresses “192.168.0.3” and “192.168.0.4” that can be acquired are set. In addition, the IP addresses “192.168.0.1” and “192.168.0.2” of the terminals 11 and 12 connected to the network 1 are set.

  In this embodiment, when the virtual terminal device 3 is realized by an information processing device such as a personal computer, the storage device of the virtual terminal device 3 communicates between terminals connected to a network having the same IP address system. The various programs for relaying are stored. For example, when the first terminal connected to the first network communicates with the second terminal connected to the second network, the storage device of the virtual terminal device 3 has the second terminal connected to the computer. A process of specifying a virtual IP address that can be acquired when an IP address is acquired on the first network side, a process of transmitting the specified virtual IP address to the first terminal, and data from the first terminal Is received, the IP address of the first terminal as a transmission source included in the received data is converted into a virtual IP address that can be acquired when the first terminal temporarily acquires an IP address on the second network side. And when receiving data from the first terminal, the second terminal sets the virtual IP address of the second terminal as the transmission destination included in the received data to the second network. Storing a communication program for executing a process of converting the real IP address for use in chromatography click.

  Next, the operation will be described. FIG. 4 is a sequence diagram illustrating an example of a process in which the virtual terminal device 3 performs address conversion between the terminals 11 and 21 and relays communication. FIG. 5 is an explanatory diagram showing an example of a frame format transmitted / received between the terminals 11 and 21. Hereinafter, the system operation of the network system using the virtual terminal device 3 will be described using the sequence diagram shown in FIG. 4 and the frame format shown in FIG. In this embodiment, as an example, a case where communication is performed between the terminal 11 connected to the network 1 and the terminal 21 connected to the network 2 is described. However, communication with the terminal 12 and the terminal 22 is described. The same applies when performing the above.

  When the terminal 11 accesses the terminal 21 to perform WEB access or the like, the terminal 11 accesses the virtual terminal device 3 according to a user operation. Then, the terminal 11 inquires about the IP address in the network 1 of the terminal 21 connected to the network 2 (an IP address that can be acquired when the terminal 21 acquires temporarily in the network 1) (step S101). For example, the terminal 11 transmits an address request packet for requesting an IP address in the network 1 of the terminal 21 to the virtual terminal device 3.

  Then, the setting unit 311 of the virtual terminal device 3 refers to the virtual terminal table 318. In this case, the setting unit 311 first sets the IP address (address after IP conversion “address” after the IP address of the terminal 21 connected to the network 2 (address “192.168.0.1” on the port 2 side)). Search and extract 192.168.0.3 "). Then, the setting unit 311 responds (transmits) the extracted IP address (the address “192.168.0.3” after IP conversion) to the terminal 11 as a search result of the virtual terminal table 318 (step S102).

  Next, the terminal 11 uses the IP address “192.168.0.3” in the network 1 of the terminal 21 to use the ARP request packet for inquiring the physical address (MAC address) of the terminal 21 corresponding to the IP address “192.168.0.3”. Is generated. Then, the terminal 11 transmits the generated ARP request packet 603 to the virtual terminal device 3 (step S103).

  When receiving the ARP request packet, the virtual terminal device 3 searches the virtual terminal table 318 (see FIG. 3). Then, the virtual terminal device 3 performs a predetermined conversion process on the received ARP request packet, changes it to the converted ARP request packet 604, and transfers it to the terminal 21 (step S104). Specifically, the virtual terminal device 3 converts the IPDA in the ARP data of the ARP request packet from “192.168.0.3” to “192.168.0.1” and also changes the IPSA from “192.168.0.1” to “192.168.0.3”. Is converted into a post-conversion ARP request packet 604 and transferred.

  Next, when the terminal 21 receives the post-conversion ARP request packet addressed to itself, the terminal 21 generates an ARP response packet 605 for responding to the post-conversion ARP request packet. Then, the terminal 21 transmits to the destination terminal (that is, the terminal 11) whose IP address is “192.168.0.3” based on the IP address included in the received converted ARP request packet (step S105).

  When receiving the ARP response packet 605, the virtual terminal device 3 refers to the virtual terminal table 318. Then, the virtual terminal device 3 performs a predetermined conversion process on the received ARP response packet 606, converts it into a converted ARP response packet, and forwards it to the terminal 11 (step S106). Specifically, the virtual terminal device 3 converts the IPDA in the ARP data of the ARP response packet from “192.168.0.3” to “192.168.0.1” and also changes the IPSA from “192.168.0.1” to “192.168.0.3”. Is converted into an ARP response packet after conversion and transferred.

  Next, when receiving the converted ARP response packet addressed to itself, the terminal 11 stores the MAC address “B” corresponding to the IP address “192.168.0.3” included in the converted ARP response packet. For example, the terminal 11 stores an ARP table in a storage device (not shown) such as a memory or a hard disk device in advance, and stores the MAC address “B” in the ARP table based on the received converted ARP response packet. To do.

  By executing the above processing, the MAC address of the receiving terminal 21 is stored in the transmitting terminal 11, and an IP packet can be transmitted from the terminal 11 to the terminal 21.

  Next, an operation when an IP packet is actually transmitted from the terminal 11 to the terminal 21 will be described. When the terminal 11 transmits a packet to the terminal 21, the destination MAC address (hereinafter referred to as MACDA) is set to “B”, the source MAC address (hereinafter referred to as MACSA) is set to “A”, and the IPDA is set to “192.168”. .0.3 "and an IP packet 607 with IPSA" 192.168.0.1 "is generated. Then, the terminal 11 transmits the generated IP packet to the virtual terminal device 3 (step S107).

  When receiving the IP packet, the virtual terminal device 3 refers to the virtual terminal table 318. Then, the virtual terminal device 3 performs a predetermined conversion process on the received IP packet, changes the IP packet to the converted IP packet 608, and transfers the IP packet to the terminal 21 (step S108). Specifically, the virtual terminal device 3 converts the IPDA of the IP packet from “192.168.0.3” to “192.168.0.1” and converts the IPSA from “192.168.0.1” to “192.168.0.3”. The converted IP packet is transferred after being converted.

  Conversely, when transmitting an IP packet from the terminal 21 to the terminal 11, the terminal 21 sets MACDA to “B”, MACSA to “A”, IPDA to “192.168.0.3”, and IPSA to “192.168.”. An IP packet 609 with “0.1” is generated. Then, the terminal 21 transmits the generated IP packet to the virtual terminal device 3 (step S109).

  When receiving the IP packet, the virtual terminal device 3 refers to the virtual terminal table 318. Then, the virtual terminal device 3 performs a predetermined conversion process on the received IP packet, changes it to the converted IP packet 610, and transfers it to the terminal 11 (step S110). Specifically, the virtual terminal device 3 converts the IPDA of the IP packet from “192.168.0.3” to “192.168.0.1” and also converts the IPSA from “192.168.0.1” to “192.168.0.3”. The converted IP packet is transferred after being converted.

  As described above, according to the present embodiment, the communication device (virtual terminal device 3) is provided between two networks using the same IP address system. The virtual terminal device 3 does not receive only the Ethernet frame addressed to itself from the first network (for example, the network 1), but all the Ethernet frames transmitted to the second network (for example, the network 2). Receive.

  Further, when the protocol type is IP, the IPDA conversion unit 313 of the virtual terminal device 3 obtains the transmission destination IP address when the transmission destination terminal temporarily obtains the IP address on the second network side. Convert to address. The IPSA conversion unit 314 converts the source IP address into an IP address that can be acquired when the source terminal temporarily acquires an IP address on the second network side.

  Further, when the protocol type is ARP, the ARPDA conversion unit 315 can acquire the transmission destination IP address included in the ARP data when the transmission destination terminal temporarily acquires the IP address on the second network side. To a valid IP address. The ARPSA conversion unit 316 converts the transmission source IP address into an IP address that can be acquired when the transmission source terminal temporarily acquires an IP address on the second network network side.

  Then, the virtual terminal device 3 transfers each Ethernet frame after conversion shown above to a port other than the input port.

  Conventionally, when a NAT router is used, the NAT router transfers only a frame having a MAC address addressed to itself as MACDA. Therefore, communication at the layer 2 level cannot be performed between networks using the same IP address system.

  On the other hand, according to this embodiment, by providing the above configuration, it is not necessary to change the internal setting of the terminal using a communication device provided between two networks using the same IP address system. In addition, communication at the layer 2 and layer 3 levels can be performed.

  Further, according to the present embodiment, the communication device (virtual terminal device 3) is provided between two networks that use the same IP address system to which a plurality of terminals are connected. The virtual terminal device 3 does not convert the IP address of the received frame itself based on the IP address set for the Ethernet port, but manages the virtual IP address when each terminal performs communication. Therefore, the virtual terminal device 3 uses a virtual terminal table. The virtual terminal table includes an Ethernet port and a default IP address of a terminal connected to the first network in association with an IP address that the terminal can acquire in the second network, and further includes an Ethernet port And a second terminal connected to the second network using an IP address that can be acquired in the first network, and a table including the default IP address of the second terminal in association with each other.

  The IPDA conversion unit 313 and the ARPDA conversion unit 315 use the input port of the reception frame and the transmission destination IP address information included in the reception frame, and based on the result of searching the virtual terminal table, transmission destination IP address information Convert. Also, the IPSA conversion unit 314 and the ARPSA conversion unit 316 use the input port of the received frame and the source IP address information included in the received frame, based on the result of searching the virtual terminal table, Convert address information.

  In a conventional IP converter (see Patent Document 1), when a plurality of terminals are connected to one Ethernet port, communication between terminals cannot be performed.

  On the other hand, according to this embodiment, by providing the above-described configuration, one Ethernet is used by using a communication device provided between networks using the same IP address system to which a plurality of terminals are connected. Communication between terminals can be performed even when a plurality of terminals are connected to the port.

  According to the present embodiment, the communication device (virtual terminal device 3) is provided between two networks that use the same IP address system. The setting unit 311 of the virtual terminal device 3 has an interface such as CGI or GUI using a fixed IP address. In addition, the setting unit 311 has means for searching the virtual terminal table and responding to the source terminal in response to an inquiry about the destination IP address from the source terminal.

  Conventionally, when a NAT router or an IP conversion device is used, when a transmission source terminal transmits an IP packet to a transmission destination terminal, the transmission destination IP address of the IP packet cannot be acquired by itself.

  On the other hand, according to this embodiment, using a communication device provided between networks using the same IP address system, an interface for a transmission source terminal to acquire a transmission destination IP address is provided. It is possible to allow the transmission source terminal to specify the transmission destination IP address by itself.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to the drawings. The communication apparatus shown in the second embodiment of the present invention is characterized by enabling layer 2 and layer 3 communication between networks of three or more identical IP address systems. FIG. 6 is a block diagram illustrating a configuration example of a network system using the communication device according to the second embodiment of the present invention. As shown in FIG. 6, in the present embodiment, the network system includes a network 1, a network 2, a network 8, and a virtual terminal device 3.

  In the present embodiment, the networks 1, 2, and 8 are networks having the same IP address system. For example, it is assumed that the IP address systems of the networks 1, 2, and 8 are both “192.168.0.1/24”.

  The network 1 includes terminals 11 and 12. The IP address of the terminal 11 is “192.168.0.1”, and the IP address of the terminal 12 is “192.168.0.2”. 6 shows a case where the network 1 includes two terminals 11 and 12. However, the number of terminals is not limited to two. For example, the network 1 may include three or more terminals. The terminals 11 and 12 are specifically realized by an information processing terminal such as a personal computer.

  The network 2 includes terminals 21 and 22. Further, it is assumed that the IP address of the terminal 21 is “192.168.0.1” and the IP address of the terminal 22 is “192.168.0.2”. 6 shows a case where the network 2 includes two terminals 21 and 22. However, the number of terminals is not limited to two. For example, the network 2 may include three or more terminals. The terminals 21 and 22 are specifically realized by an information processing terminal such as a personal computer.

  The network 8 includes terminals 81 and 82. Further, it is assumed that the IP address of the terminal 81 is “192.168.0.1” and the IP address of the terminal 82 is “192.168.0.2”. 6 shows a case where the network 8 includes two terminals 81 and 82, the number of terminals is not limited to two. For example, the network 8 may include three or more terminals. The terminals 81 and 82 are specifically realized by an information processing terminal such as a personal computer.

  FIG. 7 is a block diagram illustrating a configuration example of the virtual terminal device 3 according to the second embodiment. In FIG. 7, the same components as those of the virtual terminal device 3 shown in FIG.

  As shown in FIG. 7, the virtual terminal device 3 includes Ethernet ports 301, 302, and 303, a setting unit 311, a frame identification unit 312, an IPDA conversion unit 323, an IPSA conversion unit 324, an ARPDA conversion unit 325, an ARPSA conversion unit 326, A frame control unit 327, an IPDA conversion table 3281, and an IPSA conversion table 3282 are included.

  The Ethernet port 303 is an interface unit similar to the Ethernet ports 301 and 302 shown in the first embodiment. Specifically, the Ethernet port 303 is an interface unit connected to the network 8. In the virtual terminal device 3, the frame received from the Ethernet port 303 is transferred to the frame identification unit 312. A frame transmitted (output) from the frame control unit 327 to the Ethernet port 303 is transferred to the network 8 via the Ethernet port 303. That is, the virtual terminal device 3 transmits a frame (data) to the terminals 81 and 82 connected to the network 8 using the Ethernet port 303.

  The setting unit 321 has an interface such as CGI or GUI. For example, the setting unit 321 displays a setting screen using CGI or GUI on a display unit such as a monitor. Further, the user performs a setting operation of the virtual terminal device 3 while viewing the setting screen using the CGI or GUI. Then, the setting unit 321 may set the IPDA conversion table 3281 and the IPSA conversion table 3282 in accordance with a user setting operation.

  In addition, the user terminal (terminal 11, 12, 21, 22, 81, 82) designates the IP address of the setting unit 321 and stores information on CGI and GUI (for example, information on the IPDA conversion table 3281 and the IPSA conversion table 3282). The IP address of the destination terminal can be obtained by accessing an interface such as a display screen that can be displayed. For example, the setting unit 321 extracts the IP address of the transmission destination terminal from the IPDA conversion table 3281 and the IPSA conversion table 3282 in response to a request from the terminals 11, 12, 21, 22, 81, and 82. A function of transmitting to the terminals 11, 12, 21, 22, 81, 82 is provided.

  The setting unit 321 has a function of transmitting (outputting) an IP packet to the frame control unit 327 together with the transmission frame, using an input port of a frame received from the user terminal as an output port when transmitting an IP packet to the user terminal.

  The IPDA conversion unit 323 has a function of acquiring (extracting) IPDA information based on an IP header of a frame received (input) from the frame identification unit 312 first. Further, the IPDA conversion unit 323 has a function of searching the IPDA conversion table 3281 based on the acquired IPDA information and the input port information of the received frame. Further, after the search, the IPDA conversion unit 323 has a function of converting the IPDA information of the received frame using the search result of the IPDA conversion table 3281. The IPDA conversion unit 323 has a function of transferring the received frame to the IPSA conversion unit 314 together with the input port information of the received frame and the searched output port information.

  If the IPDA of the received frame is an IP multicast type or a broadcast type, the IPDA conversion unit 323 does not change (convert) the IPDA information. The IPDA conversion unit 323 then transfers the received frame to the IPSA conversion unit 314 together with the received frame and the input port information, using all ports other than the input port of the received frame as output ports.

  The IPSA conversion unit 324 has a function of acquiring (extracting) IPSA information based on the IP header of a frame received (input) from the IPDA conversion unit 323. The IPSA conversion unit 324 has a function of searching the IPSA conversion table 3282 based on the acquired IPSA information and the input port and output port information of the received frame received (input) from the IPDA conversion unit 323. The IPSA conversion unit 324 has a function of converting the IPSA information of the received frame using the search result of the IPSA conversion table 3282 after the search. The IPSA conversion unit 324 has a function of transferring the received frame to the frame control unit 327 together with the output port information of the received frame.

  The ARPDA conversion unit 325 has a function of acquiring (extracting) IPDA information from the ARP data based on the ARP data portion of the frame received (input) from the frame identification unit 312. Further, the ARPDA conversion unit 325 has a function of searching the IP conversion table 3281 based on the acquired IPDA information and the input port information of the received frame. In addition, the ARPDA conversion unit 325 has a function of converting IPDA information in the ARP data of the received frame using the search result of the IPDA conversion table 3281 after the search. The ARPDA converter 325 has a function of transferring the received frame to the ARPSA converter 326 together with the input port information of the received frame and the searched output port information.

  The ARPSA conversion unit 326 has a function of acquiring (extracting) IPSA information from ARP data based on the ARP data portion of the frame received (input) from the ARPDA conversion unit 325. The ARPSA conversion unit 326 also has a function of searching the IPSA conversion table 3282 based on the acquired IPSA information and the input port and output port information received from the ARPDA conversion unit 325. The ARPSA conversion unit 326 has a function of converting IPSA information in the ARP data of the received frame using the search result of the IPSA conversion table 3282. The ARPSA conversion unit 326 has a function of transferring the received frame to the frame control unit 327 together with the output port information of the received frame.

  The frame control unit 327 has a function of transferring a frame received (input) from the setting unit 321, the frame identification unit 312, the IPSA conversion unit 324 conversion unit, the ARPSA conversion unit 326, and the like to the output port of the received frame.

  Specifically, the IPDA conversion table 3281 is stored in a storage device (not shown) such as a memory or a hard disk device provided in the virtual terminal device 3. FIG. 8 is an explanatory diagram showing an example of the IPDA conversion table 3281. The IPDA conversion table 3281 is stored in the networks 1, 2, 8 and the terminals 11, 12, 13, 14, 81, 82 registered in advance by an administrator who manages the network system using the virtual terminal device 3, for example. And is stored in the storage device of the virtual terminal device 3. Further, for example, the IPDA conversion table 3281 is generated by the virtual terminal device 3 based on the information of the networks 1, 2, 8 and the terminals 11, 12, 13, 14, 81, 82 registered in advance. It may be stored in the storage device of the device 3.

  Hereinafter, the table configuration of the IPDA conversion table 3281 will be described with reference to FIGS. 6 and 8.

  As shown in FIG. 8, the IPDA conversion table 3281 includes a keyword field and a result field. The keyword field of the IPDA conversion table 3281 includes input port information of a received frame (port that received the received frame) and original IPDA information (IPDA originally included in the received frame).

  In FIG. 8, in the original IPDA information field, for example, the network terminals (terminals 21, 22, 81, 82) connected to the Ethernet ports 302 and 303 other than the Ethernet port 301 are connected to the network 1 side. If an IP address is acquired, an IP address that can be acquired is set.

  For example, in the original IPDA information field, an IP address “192.168.0.3” that can be obtained by the network 21 by the terminal 21 connected to the network 2 is set. In the original IPDA information field, an IP address “192.168.0.4” that can be acquired by the terminal 81 connected to the network 8 in the network 1 is set.

  As shown in FIG. 8, the result field corresponding to the keyword field (input port information and original IPDA information) includes frame output port information and post-IPDA converted information. The frame output field (output port information field) includes Ethernet port information (for example, ports 302 and 303) to which terminals (for example, terminals 21 and 81) corresponding to the IPDA information described above are connected. The IPDA converted field contains the original IP address of the terminal (for example, “192.168.0.1”).

  Specifically, the IPSA conversion table 3282 is stored in a storage device (not shown) such as a memory or a hard disk device provided in the virtual terminal device 3. FIG. 9 is an explanatory diagram showing an example of the IPSA conversion table 3282. Note that the IPSA conversion table 3282 is stored in the networks 1, 2, 8 and the terminals 11, 12, 13, 14, 81, 82 registered in advance by an administrator who manages the network system using the virtual terminal device 3, for example. And is stored in the storage device of the virtual terminal device 3. Further, for example, the IPSA conversion table 3282 is generated by the virtual terminal device 3 based on the information of the networks 1, 2, 8 and the terminals 11, 12, 13, 14, 81, 82 registered in advance. It may be stored in the storage device of the device 3.

  Hereinafter, the table configuration of the IPSA conversion table 3282 will be described with reference to FIGS. 6 and 9.

  As shown in FIG. 9, the IPSA conversion table 3282 includes a keyword field. The keyword field of the IPSA conversion table 3282 includes input port information (port that received the received frame), original IPSA information (IPSA originally included in the received frame), and output port (port that outputs the received frame).

  In FIG. 9, the IP address of the terminal connected to the network connected to the input port is set in the IPSA information field. In the output port field, port information other than the input port is set. For example, in the entry of the input port 301, the IP addresses of the terminals 11 and 12 of the network 1 are set in the IPSA information field, and the ports 302 and 303 other than the input port are set in the output port information field.

  Also, as shown in FIG. 9, the result field corresponding to the keyword field (input port information, original IPSA information, output port information) includes information after IPSA conversion. The IPSA converted field includes an IP address (for example, “192.168.0.10”) that can be used by the transmission source terminal in the transmission destination network.

  Note that the functions of the frame identification unit 312 and the Ethernet ports 301 and 302 are the same as those described in the first embodiment. In the present embodiment, the basic operation in which the virtual terminal apparatus 3 relays communication by performing address conversion between the terminals 11, 12, 21, 22, 81, 82 is the same as that of the first embodiment. It is the same as the operation shown.

  As described above, according to the present embodiment, the virtual terminal device 3 does not receive only the Ethernet frame addressed to itself, but the second network (or the third network (for example, the network 8)). All Ethernet frames sent to the are received and the protocol type of the received frame is identified.

  When the protocol type is IP, the IPDA conversion unit 323 of the virtual terminal device 3 obtains the transmission destination IP address and the transmission destination terminal temporarily acquires the IP address on the second network (or third network) side. If the IP address is converted to an IP address that can be acquired. The IPSA conversion unit 324 converts the transmission source IP address into an IP address that can be acquired when the transmission source terminal temporarily acquires the IP address on the second network (or third network) side.

  In addition, when the protocol type is ARP, the ARPDA conversion unit 325 temporarily sets the destination IP address included in the ARP data, and the destination terminal temporarily sets the IP address on the second network (or third network) side. If it is acquired, it is converted to an IP address that can be acquired. The ARPSA conversion unit 326 converts the transmission source IP address into an IP address that can be acquired when the transmission source terminal temporarily acquires an IP address on the second network (or third network) side.

  Then, the virtual terminal device 3 transfers each Ethernet frame after the above conversion to the output port.

  Conventionally, when a NAT router is used, the NAT router transfers only a frame having a MAC address addressed to itself as MACDA. Therefore, communication at the layer 2 level cannot be performed between networks using the same IP address system.

  On the other hand, according to the present embodiment, three or more networks using the same IP address system (for example, the first network, the second network, and the third network) are provided with the above configuration. Communication at the layer 2 and layer 3 levels can be performed without the need to change the internal settings of the terminal using a communication device provided in between.

  Further, according to the present embodiment, the virtual terminal device 3 does not convert the IP address of the received frame itself based on the IP address set in the Ethernet port, but in the case where each terminal performs communication. A common IP address. Therefore, the virtual terminal device 3 uses an IPDA conversion table and an IPSA conversion table.

  This IPDA conversion table uses an IP address that can be acquired in the first network by the first Ethernet port connected to the first network and the second terminal connected to the second network. The table includes an Ethernet port connected to the second network, a default IP address of the transmission destination terminal, and the like in association with each other.

  The IPSA conversion table includes a first Ethernet port connected to the first network, a default IP address of the first terminal connected to the first network, and an Ethernet connecting the second network. It is a table including an IP address and the like that can be acquired by the first terminal in the second network using the port.

  The IPDA conversion unit 323 and the ARPDA conversion unit 324 convert the destination IP address information based on the result of searching the IPDA conversion table using the input port and the destination IP address included in the received frame. Get the output port. Further, the IPSA conversion unit 325 and the ARPSA conversion unit 326 use the input port and output port in the received frame and the source IP address information included in the received frame, based on the result of searching the IPSA conversion table, The source IP address information is converted.

  Then, the frame control unit 327 of the virtual terminal device 3 transfers the received frame to the output port.

  In a conventional IP converter (see Patent Document 1), when a plurality of terminals are connected to one Ethernet port, communication between terminals cannot be performed.

  On the other hand, according to this embodiment, by using the communication apparatus provided between three or more networks using the same IP address system to which a plurality of terminals are connected by providing the above configuration. Even when a plurality of terminals are connected to one Ethernet port, communication between terminals can be performed.

  Further, according to the present embodiment, the setting unit 321 has an interface such as CGI or GUI using a fixed IP address. In addition, the setting unit 321 includes means for searching the virtual terminal table and responding to the source terminal in response to an inquiry about the destination IP address from the source terminal.

  Conventionally, when a NAT router or an IP conversion device is used, when a transmission source terminal transmits an IP packet to a transmission destination terminal, the transmission destination IP address of the IP packet cannot be acquired by itself.

  In contrast, according to the present embodiment, an interface for a transmission source terminal to acquire a transmission destination IP address using a communication device provided between three or more networks using the same IP address system is provided. In addition, the transmission source terminal can specify the transmission destination IP address by itself.

  The present invention can be applied to the use of a communication apparatus that relays communication between networks using the same IP address system.

It is a block diagram which shows an example of a structure of the network system using the communication apparatus by this invention. It is a block diagram which shows an example of a structure of a virtual terminal device. It is explanatory drawing which shows an example of a virtual terminal table. It is a sequence diagram which shows an example of the process in which a virtual terminal device performs address conversion between terminals, and relays communication. It is explanatory drawing which shows the example of the frame format transmitted / received between terminals. It is a block diagram which shows the structural example of the network system using the communication apparatus in 2nd Embodiment. It is a block diagram which shows the structural example of the virtual terminal device in 2nd Embodiment. It is explanatory drawing which shows an example of an IPDA conversion table. It is explanatory drawing which shows an example of an IPSA conversion table. It is explanatory drawing which shows the example of the method of arrange | positioning symmetrically arrange | positioning the NAT router connected to each network using the same IP address. It is a block diagram which shows an example of a structure of the system using an IP converter.

Explanation of symbols

1, 2, 8 Network 3 Virtual terminal device 11, 12, 21, 22, 81, 82 Terminals 301, 302, 303 Ethernet port 311, 321 Setting unit 312 Frame identification unit 313, 323 IPDA conversion unit 314, 324 IPSA conversion unit 315, 325 ARPDA conversion unit 316, 326 ARPSA conversion unit 317, 327 Frame control unit 318 Virtual terminal table 3281 IPDA conversion table 3282 IPSA conversion table

Claims (16)

A communication device that relays communication between terminals connected to a network having the same IP address system,
When the first terminal connected to the first network communicates with the second terminal connected to the second network, the second terminal temporarily acquires an IP address on the first network side. Virtual address specifying means for specifying a virtual IP address that can be acquired in the case of
Virtual address transmitting means for transmitting the virtual IP address specified by the virtual address specifying means to the first terminal;
When data is received from the first terminal, the IP address of the first terminal as a transmission source included in the received data is acquired by the first terminal on the second network side. A transmission side address conversion means for converting into a virtual IP address that can be acquired in the case
When data is received from the first terminal, the virtual IP address of the second terminal as a transmission destination included in the received data is changed to an actual IP address used by the second terminal in the second network. A communication apparatus comprising: a receiving side address converting means for converting. An actual IP address used in the first network by the first terminal and a virtual IP address that can be acquired when the first terminal acquires the IP address on the second network side in association with each other And an actual IP address used by the second terminal in the second network, and a virtual IP address that can be acquired when the second terminal acquires an IP address on the first network side, A virtual address correspondence table including
The transmission side address conversion means converts the IP address of the first terminal as the transmission source included in the received data into a virtual IP address based on the virtual address correspondence table,
The receiving-side address conversion unit converts the virtual IP address of the second terminal as a transmission destination included in the received data into an actual IP address of the second terminal based on the virtual address correspondence table. Item 2. The communication device according to Item 1.   Means for enabling communication between terminals at the layer 2 and layer 3 levels without changing the default IP address of the terminals when connecting between networks having the same IP address system to which a plurality of terminals are connected A communication apparatus comprising: An Ethernet frame received from a first Ethernet port connected to the first network when connecting a first network having the same IP address system to which a plurality of terminals are connected and a second network. A frame identifier for identifying the protocol type of
When the frame identification unit determines that the protocol type is IP type, the transmission destination IP address of the IP packet of the Ethernet frame is acquired when the transmission destination terminal temporarily acquires the IP address on the second network side. An IPDA conversion unit that converts the IP address to a possible IP address;
When the frame identification unit determines that the protocol type is an IP type, the IP address that can be acquired when the transmission source terminal temporarily acquires the IP address on the second network side is the IP packet. An IPSA conversion unit for converting to
When the frame identification unit determines that the protocol type is the ARP type, the destination terminal includes the destination IP address included in the data field of the received ARP packet of the Ethernet frame on the second network side. If an IP address is acquired, an ARPDA conversion unit that converts the IP address into an acquirable IP address;
When the frame identification unit determines that the protocol type is the ARP type, the source IP address included in the data field of the ARP packet is temporarily acquired by the source terminal on the second network side. Then, an ARPSA conversion unit that converts the IP address to an acquirable IP address,
A communication apparatus comprising: a frame control unit that transfers the received Ethernet frame to a port other than the input port that received the Ethernet frame. Using the first Ethernet port connected to the first network and the default IP address of the first terminal connected to the first network, the first terminal is connected to the second network side. If an IP address is acquired, an IP address that can be acquired is included in association with the second terminal connected to the first Ethernet port and the second network on the first network side. A virtual terminal table including an IP address that can be acquired when an IP address is acquired, in association with the default IP address of the second terminal,
The IPDA conversion unit converts the destination IP address information based on the result of searching the virtual terminal table using the input port of the received frame and the destination IP address information included in the received frame,
The ARPDA conversion unit converts the destination IP address information based on the result of searching the virtual terminal table using the input port of the received frame and the destination IP address information included in the received frame,
The IPSA conversion unit converts the source IP address information based on a result of searching the virtual terminal table using the input port of the received frame and the source IP address information included in the received frame,
The ARPSA conversion unit converts the transmission source IP address information based on a result of searching the virtual terminal table using the input port of the reception frame and the transmission source IP address information included in the reception frame. Item 5. The communication device according to Item 4. A setting unit having an interface for searching a virtual terminal table by CGI or GUI using a fixed IP address;
The communication device according to claim 4, wherein the setting unit sets the virtual terminal table and searches the virtual terminal table and responds to the source terminal in response to an inquiry about a destination IP address from the source terminal. IP address that can be acquired when the first Ethernet port connected to the first network and the second terminal connected to the second network acquire an IP address temporarily on the first network side And an IPDA conversion table including the second Ethernet port connecting the second network and the default IP address of the second terminal in association with each other,
Using the first Ethernet port, the default IP address of the first terminal connected to the first network, and the second Ethernet port, the first terminal is connected to the second network. An IPSA conversion table that includes IP addresses that can be acquired if the IP address is temporarily acquired on the side,
The IPDA conversion unit converts the destination IP address information based on the result of searching the IPDA conversion table using the input port and the destination IP address included in the received frame, and sets the output port. Acquired,
The ARPDA converter converts the destination IP address information based on the result of searching the IPDA conversion table using the input port and the destination IP address included in the received frame, and sets the output port. Acquired,
The IPSA conversion unit uses the input port in the received frame and the source IP address information included in the output port and the received frame to search for the source IP address information based on a result of searching the IPSA conversion table. Convert
The ARPSA conversion unit uses the input port in the received frame and the source IP address information included in the output port and the received frame to search for the source IP address information based on the result of searching the IPSA conversion table. Convert
The communication apparatus according to claim 4, wherein the frame control unit transfers the received frame to the output port. A communication system for performing communication between terminals connected to a network having the same IP address system,
A communication device that relays communication between terminals is provided.
The communication device
When the first terminal connected to the first network communicates with the second terminal connected to the second network, the second terminal temporarily acquires an IP address on the first network side. Virtual address specifying means for specifying a virtual IP address that can be acquired in the case of
Virtual address transmitting means for transmitting the virtual IP address specified by the virtual address specifying means to the first terminal;
When data is received from the first terminal, the IP address of the first terminal as a transmission source included in the received data is acquired by the first terminal on the second network side. A transmission side address conversion means for converting into a virtual IP address that can be acquired in a case;
When data is received from the first terminal, the virtual IP address of the second terminal as a transmission destination included in the received data is changed to an actual IP address used by the second terminal in the second network. Receiving address conversion means for converting,
The first terminal transmits data including a virtual IP address received from the communication device as a transmission destination to the communication device. A communication method for performing communication between terminals connected to a network having the same IP address system,
When a communication device that relays communication between terminals communicates with a second terminal connected to a second network when the first terminal connected to the first network communicates with the second terminal Identifying a virtual IP address that can be acquired when it is assumed that an IP address is acquired on the network side of 1;
The communication device transmitting the identified virtual IP address to the first terminal;
The first terminal transmitting data including a virtual IP address received from the communication device as a transmission destination to the communication device;
When the communication device receives data from the first terminal, the IP address of the first terminal as a transmission source included in the received data is assumed to be the IP address of the first terminal on the second network side. Converting to an IP address that can be acquired if the address is acquired;
When the communication device receives data from the first terminal, the second terminal uses the virtual IP address of the second terminal as a transmission destination included in the received data in the second network. And a step of converting to an actual IP address. When connecting the first network and the second network having the same IP address system to which a plurality of terminals are connected, the terminal connected to the first network and the second network are connected A communication method for relaying communication with a connected terminal,
When receiving an Ethernet frame from a first Ethernet port connected to the first network, identifying the protocol type of the received frame;
When the protocol type is determined to be the IP type, the destination IP address of the IP packet of the Ethernet frame is set to an IP address that can be acquired when the destination terminal temporarily acquires the IP address on the second network side. Converted,
When the protocol type is determined to be an IP type, the source IP address of the IP packet is converted into an IP address that can be acquired when the source terminal temporarily acquires an IP address on the second network side,
When the protocol type is determined to be the ARP type, the transmission destination terminal temporarily acquires the IP address on the second network side as the transmission destination IP address included in the data field of the received ARP packet of the Ethernet frame. If so, convert it to an IP address that can be acquired,
When the protocol type is determined as the ARP type, the transmission source IP address included in the data field of the ARP packet is acquired when the transmission source terminal temporarily acquires the IP address on the second network side. To a possible IP address,
The received Ethernet frame is transferred to a port other than the input port that received the Ethernet frame. When connecting the first network and the second network having the same IP address system to which a plurality of terminals are connected, the terminal connected to the first network and the second network are connected A communication method for relaying communication with a connected terminal,
Using the first Ethernet port connected to the first network and the default IP address of the first terminal connected to the first network, the first terminal is connected to the second network side. If an IP address is acquired, an IP address that can be acquired is included in association with the second terminal connected to the first Ethernet port and the second network on the first network side. Temporarily storing a virtual terminal table including the default IP address of the second terminal in association with an IP address that can be acquired when an IP address is acquired,
In response to an inquiry about the destination IP address from the source terminal, the CGI or GUI user having a fixed IP address uses the interface for searching the virtual terminal table, and responds to the source terminal by searching the virtual terminal table. And
When receiving an Ethernet frame from a first Ethernet port connected to the first network, identifying the protocol type of the received Ethernet frame;
When the protocol type is determined to be the IP type, the destination IP address is determined based on the result of searching the virtual terminal table using the input port of the received Ethernet frame, the destination IP address and the source IP address information. Convert the address and source IP address,
When the protocol type is determined to be the ARP type, the virtual terminal table is searched using the input port of the received Ethernet frame and the destination IP address and source IP address included in the data field of the ARP packet. Based on the result, the destination IP address and the source IP address are converted,
The received Ethernet frame is transferred to a port other than the input port that received the Ethernet frame. When connecting the first network and the second network having the same IP address system to which a plurality of terminals are connected, the terminal connected to the first network and the second network are connected A communication method for relaying communication with a connected terminal,
IP address that can be acquired when the first Ethernet port connected to the first network and the second terminal connected to the second network acquire an IP address temporarily on the first network side And previously storing an IPDA conversion table including the Ethernet port connecting the second network and the default IP address of the second terminal in association with each other,
Using the first Ethernet port, the default IP address of the first terminal connected to the first network, and the Ethernet port connecting the second network, the first terminal If an IP address is acquired on the network side of 2 in advance, an IPSA conversion table including an IP address that can be acquired is stored in advance,
Using a virtual terminal table search interface by CGI or GUI using a fixed IP address, in response to an inquiry about the destination IP address from the source terminal, search the virtual terminal table and respond to the source terminal,
When receiving an Ethernet frame from a first Ethernet port connected to the first network, identifying the protocol type of the received Ethernet frame;
When the protocol type is determined to be the IP type, using the input port of the received Ethernet frame, the transmission destination IP address and the transmission source IP address information, based on the result of searching the IPDA conversion table and the IPSA conversion table, Converting the destination IP address and the source IP address of the IP packet of the Ethernet frame;
When the protocol type is determined to be the ARP type, the IPDA conversion table and the IP address conversion table and the source IP address included in the input port of the received Ethernet frame and the destination IP address and source IP address included in the data field of the ARP packet are used. Based on the search result of the IPSA conversion table, the destination IP address and the source IP address included in the data field of the ARP packet are converted,
The received Ethernet frame is transferred to a port other than the input port that received the Ethernet frame. A communication program for relaying communication between terminals connected to a network having the same IP address system,
On the computer,
When the first terminal connected to the first network communicates with the second terminal connected to the second network, the second terminal temporarily acquires an IP address on the first network side. A process of specifying a virtual IP address that can be acquired in the case of
Processing for transmitting the identified virtual IP address to the first terminal;
When data is received from the first terminal, the IP address of the first terminal as a transmission source included in the received data is acquired by the first terminal on the second network side. Processing to convert to a virtual IP address that can be acquired
When data is received from the first terminal, the virtual IP address of the second terminal as a transmission destination included in the received data is changed to an actual IP address used by the second terminal in the second network. A communication program for executing conversion processing. When connecting the first network and the second network having the same IP address system to which a plurality of terminals are connected, the terminal connected to the first network and the second network are connected A communication program for relaying communication with a connected terminal,
On the computer,
When receiving an Ethernet frame from a first Ethernet port connected to the first network, processing for identifying the protocol type of the received frame;
When the protocol type is determined to be the IP type, the destination IP address of the IP packet of the Ethernet frame is set to an IP address that can be acquired when the destination terminal temporarily acquires the IP address on the second network side. Process to convert,
A process of converting a source IP address of the IP packet into an IP address that can be acquired when the source terminal temporarily acquires an IP address on the second network side when the protocol type is determined to be an IP type; ,
When the protocol type is determined to be the ARP type, the transmission destination terminal temporarily acquires the IP address on the second network side as the transmission destination IP address included in the data field of the received ARP packet of the Ethernet frame. If so, processing to convert to an IP address that can be acquired,
When the protocol type is determined as the ARP type, the source IP address included in the data field of the ARP packet can be acquired when the source terminal temporarily acquires the IP address on the second network side. A process of converting to an IP address,
A communication program for executing the process of transferring the received Ethernet frame to a port other than the input port that received the Ethernet frame. When the first network having the same IP address system to which a plurality of terminals are connected and the second network are connected, the terminal connected to the first network and the second network are connected. A communication program for relaying communication with a terminal,
On the computer,
Using the first Ethernet port connected to the first network and the default IP address of the first terminal connected to the first network, the first terminal is connected to the second network side. If an IP address is acquired, an IP address that can be acquired is included in association with the second terminal connected to the first Ethernet port and the second network on the first network side. A process of storing in advance a virtual terminal table including a default IP address of the second terminal in association with an IP address that can be acquired if an IP address is acquired;
In response to an inquiry about the destination IP address from the source terminal, the CGI or GUI user having a fixed IP address uses the interface for searching the virtual terminal table, and responds to the source terminal by searching the virtual terminal table. Processing to
A process of identifying the protocol type of the received Ethernet frame when receiving an Ethernet frame from a first Ethernet port connected to the first network;
When the protocol type is determined to be the IP type, the destination IP address is determined based on the result of searching the virtual terminal table using the input port of the received Ethernet frame, the destination IP address and the source IP address information. A process of converting an address and a source IP address;
When the protocol type is determined to be the ARP type, the virtual terminal table is searched using the input port of the received Ethernet frame and the destination IP address and source IP address included in the data field of the ARP packet. A process for converting the destination IP address and the source IP address based on the result;
A communication program for executing the process of transferring the received Ethernet frame to a port other than the input port that received the Ethernet frame. When connecting the first network and the second network having the same IP address system to which a plurality of terminals are connected, the terminal connected to the first network and the second network are connected A communication program for relaying communication with a connected terminal,
On the computer,
IP address that can be acquired when the first Ethernet port connected to the first network and the second terminal connected to the second network acquire an IP address temporarily on the first network side And storing in advance an IPDA conversion table including the Ethernet port connecting the second network and the default IP address of the second terminal in association with each other;
Using the first Ethernet port, the default IP address of the first terminal connected to the first network, and the Ethernet port connecting the second network, the first terminal A process of storing in advance an IPSA conversion table that includes an IP address that can be acquired in a case where the IP address is temporarily acquired on the second network side;
Processing for searching the virtual terminal table and responding to the source terminal in response to an inquiry about the destination IP address from the source terminal using the interface for virtual terminal table search by CGI or GUI using a fixed IP address; ,
A process of identifying the protocol type of the received Ethernet frame when receiving an Ethernet frame from a first Ethernet port connected to the first network;
When the protocol type is determined to be an IP type, based on the result of searching the IPDA conversion table and the IPSA conversion table using the input port of the received Ethernet frame, the destination IP address, and the source IP address information, A process of converting the destination IP address and the source IP address of the IP packet of the Ethernet frame;
When the protocol type is determined to be the ARP type, the IPDA conversion table and the source IP address and the source IP address included in the data field of the ARP packet are input using the input port of the received Ethernet frame. A process of converting the destination IP address and the source IP address included in the data field of the ARP packet based on the result of searching the IPSA conversion table;
A communication program for executing the process of transferring the received Ethernet frame to a port other than the input port that received the Ethernet frame.

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