Relay device, relay method, and program

Abstract

To provide a relay device, a relay method, and a program, in which an expansion of a radio network is facilitated.SOLUTION: A relay device 1 comprises: an address extraction part 112 that extracts transmission source MAC address information on an ARP request frame received by a radio module 105A and stores the information in an extraction address storage part 131; an address conversion part 113 that converts the transmission source MAC address into a module MAC address in the ARP request frame, and converts transmission destination MAC address into the transmission source MAC address indicated by the transmission source MAC address stored by the extraction address storage part 131 in the ARP response frame; and a transmission control part 114 that performs control so that the ARP request frame after the conversion of the transmission source MAC address is transmitted from a radio module 105B to the other relay device 1, and the ARP response frame after the conversion of the transmission destination MAC address is transmitted from the radio module 105A to the other relay device 1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a relay device, a relay method, and a program. [Background technology]

[0002] A communication system has been proposed that supports a base station mode in which a packet signal containing data whose initial source and final destination are not the wireless device itself is communicated, that is, a wireless distribution system (WDS) that includes a relay device that can operate as an access point and communicates between the relay devices that operate as access points (see, for example, Patent Document 1). In addition, a wireless mesh network based on the IEEE802.11s standard is known as a network in which multiple wireless devices communicate with each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-016690 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the intercommunication function between access points that make up a WDS-compatible communication system is not versatile and often only works between access points manufactured by the same manufacturer. Specifically, it is difficult to add an access point manufactured by a different manufacturer to a network that already has a WDS-compatible communication system realized by multiple access points installed, and the network cannot be easily expanded.

[0005] The present invention has been made in view of the above, and has an object to provide a relay device, a relay method, and a program that make it easy to expand a wireless network. [Means for solving the problem]

[0006] In order to achieve the above object, a relay device according to the present invention comprises: a first wireless module that functions as an access point; a second wireless module that functions as a station; a module address storage unit that stores module MAC address information for identifying at least the second wireless module; a frame acquisition unit that acquires a first frame received by the first wireless module and a second frame received by the second wireless module; a transmission control unit that, when the frame acquisition unit acquires the first frame, transmits the first frame to a destination by transmitting the first frame to another relay device via the second wireless module or to a terminal device subordinate to the own device, and, when the frame acquisition unit acquires the second frame, controls the second frame to be transmitted to a destination by transmitting the second frame to another relay device via the first wireless module or to a terminal device subordinate to the own device; an address extraction unit that extracts source MAC address information indicating a source MAC address that identifies a source of the first frame; an extracted address storage unit that stores the source MAC address information; an address conversion unit that converts the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address to generate a converted first frame, and converts a destination MAC address that identifies a destination of the second frame, excluding a broadcast frame, obtained thereafter into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit to generate a converted second frame. picture, the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; When the destination IP address of the second frame matches the source IP address stored in the extracted address storage unit, the address conversion unit converts the destination MAC address of the second frame to the source MAC address associated with the source IP address stored in the extracted address storage unit, and when the destination IP address of the second frame is different from the source IP address stored in the extracted address storage unit or the extracted address storage unit does not store the source MAC address information, converts the destination MAC address of the second frame to a MAC address for broadcast. .

[0007] A relay method according to another aspect of the present invention comprises: A relay method using a relay device including a first wireless module functioning as an access point and a second wireless module functioning as a station, acquiring a first frame received by the first wireless module and a second frame received by the second wireless module; When the first frame is acquired, transmitting the first frame to another relay device via the second wireless module, or to a terminal device under the own device, thereby causing the first frame to be transmitted to a destination; When the second frame is acquired, controlling the second frame to be transmitted to a destination by transmitting the second frame to another relay device or to a terminal device under the own device via the first wireless module; extracting source MAC address information indicating a source MAC address that identifies a source of the first frame; storing the source MAC address information in an extracted address storage unit; and converting the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address stored in a module address storage unit that stores module MAC address information for identifying at least the second wireless module to generate a converted first frame, and converting a destination MAC address identifying a destination of the second frame, excluding a broadcast frame, obtained thereafter into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit to generate a converted second frame. fruit, the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; When a destination IP address of the second frame matches a source IP address stored in the extracted address storage unit, converting a destination MAC address of the second frame into the source MAC address associated with the source IP address stored in the extracted address storage unit; and converting the destination MAC address of the second frame into a broadcast MAC address when the destination IP address of the second frame is different from the source IP address stored in the extracted address storage unit, or when the extracted address storage unit does not store the source MAC address information. nothing.

[0008] From another aspect, the program according to the present invention is Computer, a frame acquisition unit that acquires a first frame received by a first wireless module functioning as an access point and a second frame received by a second wireless module functioning as a station; a transmission control unit that controls, when the frame acquisition unit acquires the first frame, to transmit the first frame to a destination by transmitting the first frame to another relay device via the second wireless module or to a terminal device subordinate to the own device, and, when the frame acquisition unit acquires the second frame, to transmit the second frame to a destination by transmitting the second frame to another relay device via the first wireless module or to a terminal device subordinate to the own device; an address extraction unit that extracts source MAC address information indicating a source MAC address that identifies a source of the first frame; an address conversion unit that converts the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address stored in a module address storage unit that stores module MAC address information for identifying at least the second wireless module, to generate a converted first frame, and that converts a destination MAC address that identifies a destination of the second frame, excluding a broadcast frame, acquired thereafter, into the source MAC address indicated by the source MAC address information stored in an extracted address storage unit that stores the source MAC address information, to generate a converted second frame; to function as A program for: the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; When the destination IP address of the second frame matches the source IP address stored in the extracted address storage unit, the address conversion unit converts the destination MAC address of the second frame to the source MAC address associated with the source IP address stored in the extracted address storage unit, and when the destination IP address of the second frame is different from the source IP address stored in the extracted address storage unit or the extracted address storage unit does not store the source MAC address information, converts the destination MAC address of the second frame to a MAC address for broadcast. . Effect of the Invention

[0009] According to the relay device of the present invention, even if each of the relay devices functioning as a so-called parent device does not have an inter-parent device communication function for transmitting and receiving frames between the multiple relay devices functioning as other parent devices, it is possible to transmit and receive frames between the multiple relay devices. Therefore, it becomes easy to add a new relay device to the relay devices constituting the network, and accordingly, it becomes easy to expand the network. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing a configuration of a communication system according to an embodiment of the present invention; [Diagram 2] FIG. 2A is a diagram showing a hardware configuration of a relay device according to an embodiment, and FIG. 2B is a diagram showing a connection relationship between devices in a communication system according to an embodiment. [Diagram 3] FIG. 2 is a diagram illustrating a functional configuration of a relay device according to an embodiment. [Figure 4] 11 is a diagram showing contents of information stored in an extracted address storage unit in the embodiment; FIG. [Diagram 5] FIG. 4 is a sequence diagram showing an operation of the communication system according to the embodiment. [Figure 6] (A) is a diagram showing the transition of the source address of an ARP request frame in an embodiment, (B) is a diagram showing the transition of the destination address of an ARP response frame in an embodiment, and (C) is a diagram showing the transition of the source address of a connection request frame in an embodiment. [Figure 7] FIG. 4 is a sequence diagram showing an operation of the communication system according to the embodiment. [Figure 8] (A) is a diagram showing the transition of the destination address of a connection response frame in an embodiment, (B) is a diagram showing the transition of the source address of an ARP request frame in an embodiment, and (C) is a diagram showing the transition of the source address of an ARP response frame in an embodiment. [Figure 9] FIG. 4 is a sequence diagram showing an operation of the communication system according to the embodiment. [Figure 10](A) is a diagram showing the transition of the destination address of an ARP response frame in an embodiment, (B) is a diagram showing the transition of the source address of a connection request frame in an embodiment, (C) is a diagram showing the transition of the source address of a connection request frame in an embodiment, and (D) is a diagram showing the transition of the source address of a connection response frame in an embodiment. [Figure 11] FIG. 4 is a sequence diagram showing an operation of the communication system according to the embodiment. [Figure 12] 11 is a diagram showing the transition of a destination address of a connection response frame in the embodiment. FIG. [Figure 13] FIG. 4 is a sequence diagram showing an operation of the communication system according to the embodiment. [Figure 14] FIG. 4 is a sequence diagram showing an operation of the communication system according to the embodiment. [Figure 15] FIG. 4 is a sequence diagram showing an operation of the communication system according to the embodiment. [Figure 16] FIG. 4 is a sequence diagram showing an operation of the communication system according to the embodiment. [Figure 17] 10 is a flowchart showing an example of the flow of a relay process executed by a relay device according to an embodiment. [Figure 18] 10 is a flowchart showing an example of the flow of a relay process executed by a relay device according to an embodiment. [Figure 19] 11A and 11B are diagrams illustrating how frames are handled by a relay device according to an embodiment of the present invention. [Figure 20] FIG. 13 is a diagram illustrating a hardware configuration of a relay device according to a modified example. [Figure 21] FIG. 13 is a diagram illustrating a functional configuration of a relay device according to a modified example. [Figure 22] FIG. 13 is a diagram illustrating a functional configuration of a relay device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A relay device according to an embodiment of the present invention will be described in detail below with reference to FIG. 1. The relay device according to this embodiment includes a first wireless module functioning as an access point, a second wireless module functioning as a station, a module address storage unit, a frame acquisition unit, a transmission control unit, an address extraction unit, an extracted address storage unit, and an address conversion unit. Here, the module address storage unit stores module MAC address information for identifying at least the second wireless module. The frame acquisition unit acquires a first frame received by the first wireless module and a second frame received by the second wireless module. When the frame acquisition unit acquires the first frame, the transmission control unit controls the first frame to be transmitted to a destination by transmitting the first frame to another relay device via the second wireless module, or to a terminal device subordinate to the own device. When the frame acquisition unit acquires the second frame, the transmission control unit controls the second frame to be transmitted to a destination by transmitting the second frame to another relay device via the first wireless module, or to a terminal device subordinate to the own device. The address extraction unit extracts source MAC address information indicating a source MAC address that identifies a source of the first frame. The extracted address storage unit stores the source MAC address information. The address conversion unit converts the source MAC address of a first frame to be transferred to a first wireless module of another relay device via the second wireless module into a module MAC address to generate a converted first frame. Furthermore, the address conversion unit converts the destination MAC address that identifies a destination of the second frame into a source MAC address indicated by the source MAC address information stored in the extracted address storage unit to generate a converted second frame for a second frame obtained thereafter, excluding a broadcast frame.

[0012] As shown in FIG. 1, the communication system according to the present embodiment includes three relay devices 1 (1A, 1B, 1C) that construct a network by mutual communication, and terminal devices 3 (3A, 3B, 3C) that exist in the cells of the relay devices 1. This communication system is adopted, for example, as a home network or an office wireless LAN. The terminal device 3 is, for example, a general-purpose personal computer equipped with a wireless module. The terminal device 3 includes an ARP table storage unit that stores an ARP (Address Resolution Protocol) table. When each of the terminal devices 3 starts transmitting a data frame to another terminal device 3, if the MAC address information of the destination terminal device 3 is not registered in the ARP table, the terminal device 3 generates an ARP request frame for inquiring about the MAC address of the destination terminal device 3 and transmits it to the destination terminal device 3. Then, when the terminal device 3 receives an ARP response frame including the MAC address information of the terminal device 3 from the destination terminal device 3, the terminal device 3 extracts the MAC address information of the other terminal device 3 from the received ARP response frame and registers it in the ARP table stored in the ARP table storage unit. In addition, when a terminal device 3 transmits a data frame to another terminal device 3, it first establishes a connection (communication link) with the destination terminal device 3 using a three-way handshake based on TCP (Transmission Control Protocol), and then begins transmitting the data frame to the other terminal device 3.

[0013] A relay device according to an embodiment of the present invention will be described in detail below with reference to Figs. 2(A) and (B), 3, and 4. Fig. 2(A) is a hardware configuration diagram of the relay device 1A according to the present embodiment. As shown in Fig. 2(A), the relay device 1A includes a CPU (Central Processing Unit) 101, a main memory 102, an auxiliary memory 103, two wireless modules 105A and 105B, and a bus 109 connecting the respective units. The main memory 102 is composed of a volatile memory such as a RAM (Random Access Memory) and is used as a working area for the CPU 101. The auxiliary memory 103 is composed of a non-volatile memory such as a ROM (Read Only Memory), or an SSD (Solid State Drive), an HDD (Hard Disk Drive), or the like, and stores a program for controlling the relay device 1. The CPU 101 reads the program stored in the auxiliary memory 103 into the main memory 102 and executes it.

[0014] The wireless modules 105A and 105B each have a different MAC address (hereinafter referred to as a module MAC (Media Access Control) address) and communicate with each other in a communication method conforming to the wireless communication standard of IEEE802.11. The wireless modules 105A and 105B each have an antenna (not shown), a receiving circuit (not shown), a signal processing unit (not shown), and a transmitting circuit (not shown). The receiving circuit receives a wireless signal via the antenna, demodulates a signal corresponding to the received wireless signal, generates a baseband signal, and outputs the baseband signal to the signal processing unit. The transmitting circuit generates a wireless signal corresponding to a frame to be transmitted by modulating a carrier signal using the baseband signal input from the signal processing unit, and transmits the generated wireless signal via the antenna. Here, the frame includes an ARP request frame, an ARP response frame, or a connection request frame or a connection response frame in the Internet layer conforming to the IPv4 or IPv6 standard. The signal processing unit is realized by, for example, a DSP (Digital Signal Processor), and generates a frame corresponding to a wireless signal received by the receiving circuit based on a baseband signal input from the receiving circuit, and sends it to the bus 109. Here, the signal processing unit of the wireless module 105A generates a frame including module MAC address information indicating a module MAC address for identifying the wireless module 105A, and sends it to the bus 109. The signal processing unit of the wireless module 105B generates a frame including module MAC address information indicating a module MAC address for identifying the wireless module 105B, and sends it to the bus 109. The signal processing unit also generates a baseband signal based on various frames transferred from the main storage unit 102 via the bus 109, and outputs it to the transmitting circuit. In this embodiment, the wireless module 105A functions as an access point (hereinafter referred to as "AP"), and the wireless module 105B functions as a station (hereinafter referred to as "STA"). Hereinafter, the wireless module 105A will be referred to as the "wireless module 105A on the AP side" and the wireless module 105B will be referred to as the "wireless module 105B on the STA side" as appropriate.The relay device 1B and the relay device 1C have the same hardware configuration as the relay device 1A, and the description thereof will be omitted.

[0015] Fig. 2(B) is a connection diagram of relay devices in the communication system shown in Fig. 1. Terminal devices 3A, 3B, and 3C are wirelessly connected to the AP-side wireless modules of relay devices 1A, 1B, and 1C, respectively. As shown in Fig. 2(B), the connections between relay devices 1A, 1B, and 1C are wirelessly connected between STA-side wireless module 105B of relay device 1A and AP-side wireless module 105C of relay device 1B, and between STA-side wireless module 105D of relay device 1B and AP-side wireless module 105E of relay device 1C. The connection relationships between relay devices 1A, 1B, and 1C are fixed by an administrator when the system is set up.

[0016] Fig. 3 is a diagram showing a functional configuration of relay device 1A according to an embodiment. In relay device 1A, CPU 101 loads a program stored in auxiliary storage unit 103 into main storage unit 102 and executes it, thereby functioning as frame acquisition unit 111, address extraction unit 112, address conversion unit 113, and transmission control unit 114 as shown in Fig. 3. In addition, auxiliary storage unit 103 shown in Fig. 2(A) has extracted address storage unit 131 and module address storage unit 132. Furthermore, main storage unit 102 shown in Fig. 2(A) functions as frame buffer 121 that temporarily stores frames received by wireless modules 105A and 105B as shown in Fig. 3. As shown in FIG. 4, for example, the extracted address memory unit 131 stores the source MAC address information, source IP address information, and wireless module identification information (specifically, IDM(AP) or the like) identifying the wireless modules 105A, 105B that received the frame acquired by the frame acquisition unit 111 in association with frame identification information (specifically, IDF(0) or the like) identifying the frame stored in the frame buffer 121.

[0017] The module address storage unit 132 stores module MAC address information for identifying the wireless modules 105A and 105B in association with module identification information for identifying the wireless modules 105A and 105B.

[0018] The frame acquisition unit 111 acquires a frame received by the wireless module 105A and a frame received by the wireless module 105B. When the frame acquisition unit 111 acquires a frame including the module MAC address information of the wireless modules 105A and 105B from the wireless modules 105A and 105B, the frame acquisition unit 111 stores the acquired frame in the frame buffer 121. In addition, the frame acquisition unit 111 notifies the address extraction unit 112 of the frames received from the wireless modules 105A and 105B.

[0019] When the address extraction unit 112 is notified of a frame from the frame acquisition unit 111, it extracts source MAC address information indicating a source MAC address that identifies the source of the frame. The address extraction unit 112 also extracts source IP address information indicating a source IP address that identifies the source of the frame in the Internet layer, and module MAC address information for identifying the wireless modules 105A and 105B that received the frame. Furthermore, the address extraction unit 112 refers to the module MAC address information stored in the module address storage unit 132, and when the extracted module MAC address matches the module MAC address of the wireless module 105A on the AP side, it determines that the frame has been received by the wireless module 105A on the AP side. On the other hand, when the extracted module MAC address matches the module MAC address of the wireless module 105B on the STA side, the address extraction unit 112 determines that the frame has been received by the wireless module 105B on the STA side. Then, based on the determination result, address extraction unit 112 notifies address conversion unit 113 and transmission control unit 114 of wireless module identification information that identifies wireless modules 105A, 105B that received the frame and frame identification information that identifies the frame. Furthermore, address extraction unit 112 stores the above-mentioned wireless module identification information together with the source MAC address information and source IP address information of the extracted frame in extracted address storage unit 131 in association with the frame identification information.

[0020] Also, assume that address extraction unit 112 acquires a frame that has the same source IP address as a frame previously acquired from frame acquisition unit 111 but has a different source MAC address. In this case, address extraction unit 112 extracts source MAC address information of the frame last acquired by frame acquisition unit 111, and updates the MAC address stored in extracted address storage unit 131 in association with source IP address information already stored therein, with the extracted MAC address. As a result, for example, when there are multiple terminal devices 3 to which duplicate IP addresses are assigned, the MAC address information assigned to the terminal device 3 that is the source of the frame last received among the frames received from these terminal devices 3 is stored in extracted address storage unit 131.

[0021] The address conversion unit 113 converts the source MAC address of a frame received by the wireless module 105A into the module MAC address of the wireless module 105B stored in the module address storage unit 132 to generate a converted frame. The address conversion unit 113 also converts the destination MAC address of a frame received by the wireless module 105B into the source MAC address stored in the extracted address storage unit 131 to generate a converted frame. The address conversion unit 113 then notifies the transmission control unit 114 of the generated converted frame. Here, when the destination IP address of the frame received by the wireless module 105B matches the source IP address stored in the extracted address storage unit 131, the address conversion unit 113 converts the destination MAC address of the frame into the source MAC address associated with the source IP address stored in the extracted address storage unit 131. Furthermore, if the destination IP address of a frame received by wireless module 105B is different from the source IP address stored in extracted address storage unit 131, or if extracted address storage unit 131 does not store source MAC address information, address conversion unit 113 converts the destination MAC address of the frame to a MAC address for broadcast. Furthermore, if the destination MAC address of the frame has already been set to a MAC address for broadcast, address conversion unit 113 maintains the destination MAC address as the MAC address for broadcast.

[0022] When the frame acquisition unit 111 acquires a frame received by the wireless module 105A, the transmission control unit 114 transfers the frame after a predetermined conversion corresponding to the acquired frame to the wireless module 105B. The wireless module 105B transmits the frame to another predetermined relay device 1 existing in the cell corresponding to the relay device 1.

[0023] Furthermore, when the frame acquisition unit 111 acquires a frame received by the wireless module 105B, the transmission control unit 114 transfers the above-mentioned converted frame corresponding to the acquired frame to the wireless module 105A. Then, the wireless module 105A transmits the converted frame to another relay device 1. The above-mentioned frame acquisition unit 111, the transmission control unit 114, and the frame buffer 121 constitute a bridge BR that functions as a Layer 2 switch in terms of software. The above-mentioned address extraction unit 112, the address conversion unit 113, the frame buffer 121, the extracted address storage unit 131, and the module address storage unit 132 constitute an address management unit AC that manages addresses.

[0024] Next, the operation of the communication system according to the present embodiment will be described in detail with reference to Fig. 5 to Fig. 16. Here, it is assumed that the MAC addresses of the terminal devices 3A, 3B, and 3C shown in Fig. 1 are "00:00:00:FF:00:01", "00:00:00:FF:00:02", and "00:00:00:FF:00:03", and that the IP addresses of the terminal devices 3A, 3B, and 3C are "192.168.0.1", "192.168.0.2", and "192.168.0.3", respectively. It is also assumed that the MAC addresses of the wireless modules 105B, 105D, and 105F of the relay devices 1A, 1B, and 1C are "00:00:00:00:00:01", "00:00:00:00:00:02", and "00:00:00:00:00:03", respectively. In the following description of address conversion in frame forwarding, the address of the wireless module 105B on the STA side (105B side) of the two wireless modules in the relay device plays a more important role.

[0025] First, a case where the terminal device 3A transmits a data frame to the terminal device 3B will be described. FIG. 5 is a sequence diagram showing the operation of the communication system according to the embodiment. Here, if the MAC address of the terminal device 3B is not registered in the ARP table of the terminal device 3A, as shown in FIG. 5, when the terminal device 3A starts a communication process for transmitting a data frame to the terminal device 3B, an ARP request frame for acquiring the MAC address of the terminal device 3B is first broadcast from the terminal device 3A and transmitted to the relay device 1A (step S1). The contents of the frame at this time are as shown in the left diagram of FIG. 6(A), and since it is a broadcast, the destination MAC address in the header is "BC_Add". On the other hand, when the relay device 1A receives the ARP request frame at the wireless module 105A, it extracts the source MAC address information "00:00:00:FF:00:01" and the source IP address information "192.168.01" of the received ARP request frame, and stores the extracted source MAC address information and source IP address information in the extracted address storage unit 131 (step S2). As shown in Fig. 6(A), the Ethernet header of the ARP request frame contains information indicating the destination MAC address "DSTMAC" and the source MAC address "SRCMAC". In addition, the Ethernet payload, which includes an IP header based on IPv4 and IPv6, contains information indicating the source MAC address "SenderMAC", the source IP address "SenderIP", the MAC address of the request destination for MAC address information "TargetMAC", and the destination IP address "TargetIPAddress".

[0026] Next, the relay device 1A converts the source MAC address of the received ARP request frame into a module MAC address that identifies the wireless module 105B of the relay device 1A (step S3). Then, the relay device 1A converts both the source MAC address "SRCMAC" included in the Ethernet header of the ARP request frame and the source MAC address "SenderMAC" included in the Ethernet payload from the MAC address "00:00:00:FF:00:01" of the terminal device 3A to the MAC address "00:00:00:00:00:01" of the wireless module 105B, as shown in the right diagram of Fig. 6(A). Returning to Fig. 5, the converted ARP request frame is then transmitted from the relay device 1A (wireless module 105B on the STA side) to the relay device 1B (wireless module 105C on the AP side) (step S4).

[0027] On the other hand, when the relay device 1B receives the converted ARP request frame, the received ARP request frame is broadcast from the relay device 1B to the terminal device 3B present in the cell corresponding to the relay device 1B (step S5). On the other hand, when the terminal device 3B receives the ARP request frame addressed to itself, it generates an ARP response frame including its own MAC address information "00:00:00:FF:00:02" (step S6). Here, the terminal device 3B generates an ARP response frame in which the same MAC address as the source MAC address of the received ARP request frame is set as the destination MAC address. Specifically, as shown in the left diagram of FIG. 6(B), the terminal device 3B generates an ARP response frame in which the destination MAC address "DSTMAC" is set to the MAC address "00:00:00:00:00:01" of the wireless module 105B of the relay device 1A. Returning to FIG. 5, the generated ARP response frame is then transmitted from the terminal device 3B to the relay device 1B (step S7).

[0028] On the other hand, when the relay device 1B receives the ARP response frame, the received ARP response frame is transmitted from the relay device 1B (AP-side wireless module 105C) to the relay device 1A (STA-side module 105B) based on the destination MAC address "DSTMAC" (step S8). At this time, the relay device 1B transmits the received ARP response frame to the relay device 1A via the wireless module 105C. On the other hand, when the relay device 1A receives the ARP response frame, it converts the destination MAC address of the received ARP response frame into the source MAC address information (i.e., the MAC address of the terminal device 3A) stored by the extracted address storage unit 131 in step S2 (step S9). Specifically, as shown in the right diagram of FIG. 6(B), the relay device 1A converts the destination MAC address "DSTMAC" included in the Ethernet header of the ARP response frame from the MAC address "00:00:00:00:00:01" of the wireless module 105B to the MAC address "00:00:00:FF:00:01" of the terminal device 3A. The relay device 1A converts the destination MAC address of the ARP response frame in this manner when the destination MAC address is its own device and the destination IP address matches the source IP address of the ARP request frame stored in the extracted address storage unit 131. Returning to FIG. 5, next, the converted ARP response frame shown in the right diagram of FIG. 6(B) is transmitted from the relay device 1A (wireless module 105A on the AP side) to the terminal device 3A based on the converted MAC address (step S10). On the other hand, when the terminal device 3A receives the ARP response frame, it extracts the MAC address information of the terminal device 3B from the received ARP response frame and stores the extracted MAC address information in an ARP table storage unit (not shown) in correspondence with the IP address information of the terminal device 3B (step S11).

[0029] Next, the terminal device 3A generates a connection request frame for requesting establishment of a connection to the terminal device 3B in the Internet layer (step S12). Here, the terminal device 3A generates a connection request frame in which the destination MAC address of the connection request frame is set to the MAC address extracted from the ARP response frame (the MAC address stored in the ARP table storage unit). Specifically, as shown in the left diagram of FIG. 6(C), the terminal device 3A generates a connection request frame in which the destination MAC address "DSTMAC" is set to the MAC address "00:00:00:FF:00:02" of the terminal device 3B. Returning to FIG. 5, the generated connection request frame is then transmitted from the terminal device 3A to the relay device 1A (step S13).

[0030] On the other hand, when the relay device 1A (wireless module 105A on the AP side) receives the connection request frame, it converts the source MAC address of the received connection request frame into a module MAC address that identifies the wireless module 105B (step S14). Here, as shown in the right diagram of FIG. 6(C), the relay device 1A converts the source MAC address "SRCMAC" of the connection request frame from the MAC address "00:00:00:FF:00:01" of the terminal device 3A into the MAC address "00:00:00:00:00:01" of the wireless module 105B of the relay device 1A. Next, as shown in FIG. 7, the converted connection request frame shown in the right diagram of FIG. 6(C) is transmitted from the relay device 1A (wireless module 105B on the STA side) to the relay device 1B (wireless module 105C on the AP side) (step S15). On the other hand, when the relay device 1B receives the converted connection request frame, the received connection request frame is transmitted from the relay device 1B (wireless module 105C on the AP side) to the terminal device 3B based on the destination MAC address (step S16).

[0031] On the other hand, when the terminal device 3B receives a connection request frame addressed to itself, it generates a connection response frame (ACK (ACKnowledge) frame) in which the source MAC address is set to the MAC address of its own device (step S17). Here, the terminal device 3B generates a connection response frame in which the same MAC address as the source MAC address of the received connection request frame is set to the destination MAC address. Specifically, as shown in the left diagram of FIG. 8(A), the terminal device 3B generates a connection response frame in which the destination MAC address "DSTMAC" is set to the MAC address "00:00:00:00:00:01" of the wireless module 105B of the relay device 1A. Returning to FIG. 7, the generated connection response frame is then transmitted from the terminal device 3B to the relay device 1B (step S18).

[0032] On the other hand, when the relay device 1B (wireless module 105C on the AP side) receives the connection response frame, the received connection response frame is transmitted from the relay device 1B to the relay device 1A based on the destination MAC address (step S19). At this time, the relay device 1B transmits the received connection response frame to the relay device 1A (wireless module 105B on the STA side) via the wireless module 105C. At this time, when the relay device 1A receives the connection response frame via its own wireless module 105B, it converts the destination MAC address of the received connection response frame into the source MAC address indicated by the source MAC address information in the ARP request frame from the terminal device 3A, which is stored in the extracted address storage unit 131 (step S20). Specifically, as shown in the right diagram of FIG. 8(A), the relay device 1A converts the destination MAC address "DSTMAC" included in the Ethernet header of the connection response frame from the MAC address "00:00:00:00:00:01" of the wireless module 105B to the MAC address "00:00:00:FF:00:01" of the terminal device 3A. The relay device 1A converts the destination MAC address of the connection response frame in this manner when the destination MAC address is its own device and the destination IP address matches the source IP address of the connection request frame stored in the extracted address storage unit 131. Returning to FIG. 7, the converted connection response frame shown in the right diagram of FIG. 8(A) is then transmitted from the relay device 1A (wireless module 105A on the AP side) to the terminal device 3A based on the converted MAC address (step S21).

[0033] After that, although not shown in Fig. 7, when the terminal device 3A receives the connection response frame, it generates a transmission start notification frame for notifying the terminal device 3B that it will start transmitting data frames. Then, the generated transmission start notification frame is transmitted from the terminal device 3A to the terminal device 3B in the same sequence as the above-mentioned connection request frame. In this way, a connection is established between the terminal devices 3A and 3B by a three-way handshake. Next, a data frame is transmitted from the terminal device 3A to the terminal device 3B in the same sequence as the above-mentioned connection request frame.

[0034] Next, a case where the terminal device 3A transmits a data frame to the terminal device 3C will be described. In the following description, the wireless modules 105A, 105B, 105C, 105D, 105E, and 105F in the transmission and reception of the relay devices 1A, 1B, and 1C will be omitted as appropriate. When the MAC address of the terminal device 3C is not registered in the ARP table of the terminal device 3A, as shown in FIG. 5, when the terminal device 3A starts a communication process for transmitting a data frame to the terminal device 3C, first, the same process (not shown) as the above-mentioned steps S1 to S4 is executed, and the ARP request frame reaches the relay device 1B. After that, as shown below the dashed line in FIG. 7, the relay device 1B extracts the source MAC address information and the source IP address information of the received ARP request frame, and stores the extracted source MAC address information and the source IP address information in the extracted address storage unit 131 (step S22). Next, the relay device 1B converts the source MAC address of the received ARP request frame into a module MAC address that identifies the wireless module 105D of the relay device 1B (step S23). Specifically, the relay device 1B converts both of the source MAC addresses "SRCMAC" and "SenderMAC" of the ARP request frame from the MAC address "00:00:00:00:00:01" of the wireless module 105B of the relay device 1A to the MAC address "00:00:00:00:00:02" of the wireless module 105D of the relay device 1B, as in the converted frame shown in the right diagram of FIG. 8(B). Returning to FIG. 7, the converted ARP request frame is then transmitted from the relay device 1B to the relay device 1C (step S24).

[0035] On the other hand, when the relay device 1C receives the converted ARP request frame shown in the right diagram of FIG. 8(B), the received ARP request frame is broadcast from the relay device 1C to the terminal device 3C present in the cell corresponding to the relay device 1C (step S25). On the other hand, when the terminal device 3C receives the ARP request frame addressed to itself, it generates an ARP response frame including its own MAC address information (step S26). Here, the terminal device 3C generates an ARP response frame with the source MAC address of the received ARP request frame set as the destination MAC address. Specifically, the terminal device 3C generates an ARP response frame with the destination MAC address "DSTMAC" set to the MAC address "00:00:00:00:00:02" of the relay device 1B as shown in the left diagram of FIG. 8(C). Returning to FIG. 7, the generated ARP response frame is then transmitted from the terminal device 3C to the relay device 1C (step S27).

[0036] On the other hand, when the relay device 1C receives the ARP response frame, the received ARP response frame is transmitted from the relay device 1C to the relay device 1B based on the destination MAC address as shown in Fig. 9 (step S28). At this time, the relay device 1C transmits the received ARP response frame to the relay device 1B via the wireless module 105E. On the other hand, when the relay device 1B receives the ARP response frame via its own wireless module 105D, it converts the destination MAC address of the received ARP response frame into the source MAC address (i.e., the module MAC address of the relay device 1A) indicated by the source MAC address information stored in the extracted address storage unit 131 in step S22 (step S29). Specifically, as shown in the right diagram of FIG. 8(C), the relay device 1B converts the destination MAC address "DSTMAC" and "SenderMAC" included in the Ethernet header of the ARP response frame from the MAC address "00:00:00:00:00:02" of the wireless module 105D of the relay device 1B to the MAC address "00:00:00:00:00:01" of the wireless module 105B of the relay device 1A. The relay device 1B converts the destination MAC address of the ARP response frame in this manner when the destination MAC address is its own device and the destination IP address matches the source IP address of the ARP request frame stored in the extracted address storage unit 131. Returning to FIG. 9, the converted ARP response frame shown in the right diagram of FIG. 8(C) is then transmitted from the relay device 1B to the relay device 1A based on the destination MAC address (step S30).

[0037] On the other hand, when the relay device 1A receives the ARP response frame, it converts the destination MAC address of the received ARP response frame into the source MAC address (i.e., the MAC address of the terminal device 3A) indicated by the source MAC address information in the ARP response frame stored in the extracted address storage unit 131 (step S31). Specifically, as shown in the left diagram of FIG. 10(A), the relay device 1A converts the destination MAC address included in the Ethernet header of the ARP response frame from the MAC address "00:00:00:00:00:01" of the wireless module 105B to the MAC address "00:00:00:FF:00:01" of the terminal device 3A. The relay device 1A converts the destination MAC address of the ARP response frame in this way when the destination MAC address is its own device and the destination IP address matches the source IP address stored in the extracted address storage unit 131. Next, the converted ARP response frame is transmitted from the relay device 1A to the terminal device 3A based on the converted MAC address (step S32). On the other hand, when the terminal device 3A receives the ARP response frame, it extracts the MAC address information of the terminal device 3C from the received ARP response frame and stores the extracted MAC address information in an ARP table storage unit (not shown) in correspondence with the IP address information of the terminal device 3C (step S33).

[0038] Next, the terminal device 3A generates a connection request frame for requesting establishment of a connection to the terminal device 3C in the Internet layer (step S34). Here, the terminal device 3A generates a connection request frame in which the destination MAC address of the connection frame is set to the MAC address of the terminal device 3C extracted from the ARP response frame. Specifically, as shown in the left diagram of FIG. 10(B), the terminal device 3A generates a connection request frame in which the destination MAC address "DSTMAC" is set to the MAC address "00:00:00:FF:00:03" of the terminal device 3C. Returning to FIG. 9, the generated connection request frame is then transmitted from the terminal device 3A to the relay device 1A (step S35).

[0039] On the other hand, when the relay device 1A receives the connection request frame, it converts the source MAC address of the received connection request frame into a module MAC address that identifies the wireless module 105B (step S36). Here, as shown in the right diagram of FIG. 10(B), the relay device 1A converts the source MAC address "SRCMAC" of the connection request frame from the MAC address "00:00:00:FF:00:01" of the terminal device 3A into the MAC address "00:00:00:00:00:01" of the wireless module 105B. Returning to FIG. 9, the converted connection request frame is then transmitted from the relay device 1A to the relay device 1B (step S37). On the other hand, when the relay device 1B receives the converted connection request frame shown in the left diagram of FIG. 10(C), it converts the source MAC address of the received connection request frame into a module MAC address that identifies the wireless module 105B of the relay device 1B (step S38). Specifically, as shown in the right diagram of Fig. 10(C), the relay device 1B converts the source MAC address "SRCMAC" of the connection request frame from the MAC address "00:00:00:00:00:01" of the relay device 1A to the MAC address "00:00:00:00:00:02" of the wireless module 105D of the relay device 1B. Returning to Fig. 9, the converted connection request frame is then transmitted from the relay device 1B to the relay device 1C (step S39). On the other hand, when the relay device 1C receives the connection request frame, the received connection request frame is transmitted from the relay device 1C to the terminal device 3C based on the destination MAC address of the frame (step S40).

[0040] On the other hand, when the terminal device 3C receives a connection request frame addressed to itself, it generates a connection response frame (ACK frame) in which the source MAC address is set to the MAC address of its own device (step S41). Here, the terminal device 3C generates a connection response frame in which the same MAC address as the source MAC address "SRCMAC" of the received connection request frame is set to the destination MAC address "DSTMAC". Specifically, as shown in the left diagram of FIG. 10(D), the terminal device 3C generates a connection response frame in which the destination MAC address "DSTMAC" is set to the MAC address "00:00:00:00:00:02" of the relay device 1B. Then, as shown in FIG. 11, the generated connection response frame is transmitted from the terminal device 3C to the relay device 1C (step S42).

[0041] On the other hand, when the relay device 1C receives the connection response frame, the received connection response frame is transmitted from the relay device 1C to the relay device 1B based on the destination MAC address (step S43). At this time, the relay device 1C transmits the received connection response frame to the relay device 1B via the wireless module 105E.

[0042] On the other hand, when the relay device 1B receives the connection response frame via the wireless module 105D of the relay device 1B, the relay device 1B converts the destination MAC address of the received connection response frame to the source MAC address indicated by the source MAC address information in the ARP request frame stored in the extracted address storage unit 131 (step S44). Specifically, as shown in the right diagram of FIG. 10(D), the relay device 1B converts the destination MAC address "DSTMAC" of the connection response frame from the MAC address "00:00:00:00:00:02" of the wireless module 105D to the MAC address "00:00:00:00:00:01" of the wireless module 105B of the relay device 1A. The relay device 1B converts the destination MAC address of the connection response frame in this manner when the destination MAC address is the relay device itself and the destination IP address matches the source IP address stored in the extracted address storage unit 131. Thereafter, the converted connection request frame is transmitted from relay device 1B to relay device 1A based on the destination MAC address (step S45).

[0043] On the other hand, when the relay device 1A receives the connection response frame, it converts the destination MAC address of the received connection response frame into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit 131 (step S46). Specifically, as shown in FIG. 12, the relay device 1A converts the destination MAC address "DSTMAC" of the connection response frame from the MAC address "00:00:00:00:00:01" of the wireless module 105B into the MAC address "00:00:00:FF:00:01" of the terminal device 3A. The relay device 1A converts the destination MAC address of the connection response frame in this manner when the destination MAC address is its own device and the destination IP address matches the source IP address stored in the extracted address storage unit 131. Returning to FIG. 11, the converted connection response frame is then transmitted from the relay device 1A to the terminal device 3A based on the converted MAC address (step S47).

[0044] 11, when the terminal device 3A receives the connection response frame, it generates a transmission start notification frame for notifying the terminal device 3C that it will start transmitting data frames. Then, the generated transmission start notification frame is transmitted from the terminal device 3A to the terminal device 3C in the same sequence as the above-mentioned connection request frame. In this way, a connection is established between the terminal devices 3A and 3C by a three-way handshake. Next, a data frame is transmitted to the terminal device 3C in the same sequence as the above-mentioned connection request frame.

[0045] Next, a case where the terminal device 3B transmits a data frame to the terminal device 3A will be described. Note that, in the processes in Fig. 13 to Fig. 16, which are sequence diagrams showing the operation of the communication system according to the embodiment described below, the generation of the APR request frame, the APR response frame, the connection request frame, and the connection response frame and the address conversion within the frames have been described above, and detailed description thereof will be omitted.

[0046] When the MAC address of the terminal device 3A is not registered in the ARP table of the terminal device 3B, as shown in FIG. 13, when the terminal device 3B starts a communication process for transmitting a data frame to the terminal device 3A, an ARP request frame for acquiring the MAC address of the terminal device 3A is broadcast from the terminal device 3B to the relay device 1B (step S51). On the other hand, when the relay device 1B receives an ARP request frame, the received ARP request frame is broadcast from the relay device 1B to the relay device 1A (step S52). At this time, the relay device 1B transmits the received ARP response frame to the relay device 1A via the wireless module 105C. Here, since the destination MAC address of the ARP response frame received by the relay device 1A is set to a MAC address for broadcasting, the ARP request frame is broadcast from the relay device 1A to the terminal device 3A (step S53). At this time, the relay device 1A transmits the received ARP response frame to the terminal device 3A via the wireless module 105A. In the flow from steps S51 to S53, the ARP request frame sent from the terminal device 3B is broadcast from the AP side module to the STA side module, and the MAC address is not stored or converted.

[0047] On the other hand, when the terminal device 3A receives the ARP request frame addressed to itself, it generates an ARP response frame including its own MAC address information (step S54). Here, the terminal device 3A generates an ARP response frame with the source MAC address of the received ARP request frame set as the destination MAC address. Then, the generated ARP response frame is transmitted from the terminal device 3A to the relay device 1A (step S55).

[0048] On the other hand, when the relay device 1A receives the ARP response frame at the wireless module 105A, it extracts the source MAC address information and the source IP address information of the received ARP response frame, and stores the extracted source MAC address information and the source IP address information in the extracted address storage unit 131 (step S56). After that, the relay device 1A converts the source MAC address of the received ARP response frame into a module MAC address that identifies the wireless module 105B of the relay device 1A (step S57). Next, the converted ARP response frame is transmitted from the relay device 1A to the relay device 1B (step S58). At this time, the relay device 1A transmits the converted ARP response frame to the relay device 1B via the wireless module 105B. Then, the converted ARP response frame is transmitted from the relay device 1B to the terminal device 3B (step S59). On the other hand, when the terminal device 3B receives the ARP response frame, it extracts the MAC address information of the terminal device 3A from the received ARP response frame and stores the extracted MAC address information in an ARP table storage unit (not shown) in correspondence with the IP address information of the terminal device 3A (step S60).

[0049] Next, the terminal device 3B generates a connection request frame for requesting the establishment of a connection to the terminal device 3A in the Internet layer (step S61). Here, the terminal device 3B generates a connection request frame in which the destination MAC address of the connection frame is set to the MAC address of the wireless module 105B of the relay device 1A extracted from the ARP response frame. After that, the generated connection request frame is transmitted from the terminal device 3B to the relay device 1B (step S62). On the other hand, when the relay device 1B receives the connection request frame, the received connection request frame is transmitted to the relay device 1A based on the destination MAC address (step S63). On the other hand, when the relay device 1A receives the connection request frame, the relay device 1A converts the destination MAC address of the received connection request frame to the source MAC address indicated by the source MAC address information stored in the extracted address storage unit 131 (step S64). Specifically, the relay device 1A converts the destination MAC address of the connection request frame from the MAC address of the wireless module 105B to the MAC address of the terminal device 3A. Relay device 1A converts the destination MAC address of the connection request frame in this manner when the destination MAC address is its own device and the destination IP address matches the source IP address stored in extracted address storage unit 131. Next, as shown in Fig. 14, the converted connection request frame is transmitted from relay device 1A to terminal device 3A based on the converted MAC address (step S65).

[0050] On the other hand, when the terminal device 3A receives a connection request frame addressed to itself, it generates a connection response frame (ACK frame) in which the source MAC address is set to the MAC address of its own device (step S66). Then, the generated connection response frame is transmitted from the terminal device 3A to the relay device 1A (step S67). On the other hand, the relay device 1A converts the source MAC address of the received connection response frame into a module MAC address that identifies the wireless module 105B of the relay device 1A (step S68). After that, the converted connection response frame is transmitted from the relay device 1A to the relay device 1B (step S69). At this time, the relay device 1A transmits the converted connection response frame to the relay device 1B via the wireless module 105B. On the other hand, when the relay device 1B receives the connection response frame, the received connection response frame is transmitted from the relay device 1B to the terminal device 3B (step S70).

[0051] After that, although not shown in Fig. 14, when the terminal device 3B receives the connection response frame, it generates a transmission start notification frame for notifying the terminal device 3A that it will start transmitting data frames. Then, the generated transmission start notification frame is transmitted from the terminal device 3B to the terminal device 3A in the same sequence as the above-mentioned connection request frame. In this way, a connection is established between the terminal devices 3A and 3B by a three-way handshake. Next, a data frame is transmitted from the terminal device 3B to the terminal device 3A in the same sequence as the above-mentioned connection request frame.

[0052] Next, a case where the terminal device 3C transmits a data frame to the terminal device 3A will be described. When the MAC address of the terminal device 3A is not registered in the ARP table of the terminal device 3C, as shown in FIG. 15, when the terminal device 3C starts a communication process for transmitting a data frame to the terminal device 3A, an ARP request frame for acquiring the MAC address of the terminal device 3A is broadcast from the terminal device 3C and transmitted to the relay device 1C (step S71). On the other hand, when the relay device 1C receives an ARP request frame, the received ARP request frame is broadcast from the relay device 1C to the relay device 1B (step S72). At this time, the relay device 1C transmits the received ARP request frame to the relay device 1B via the wireless module 105E. The ARP request frame received by the relay device 1B is broadcast from the relay device 1B to the relay device 1A (step S73). The ARP request frame received by the relay device 1A is broadcast from the relay device 1A to the terminal device 3A (step S74). At this time, relay device 1A transmits the received ARP request frame to terminal device 3A via wireless module 105A. In the flow from steps S71 to S74, the ARP request frame sent from terminal device 3C is received by the STA side module of each relay device (relay devices 1B and 1A) via AP side wireless module 105E of relay device 1C, and is broadcast in succession to the AP side wireless modules of each relay device, and the MAC address is not stored or converted.

[0053] On the other hand, when the terminal device 3A receives the ARP request frame addressed to itself, it generates an ARP response frame including its own MAC address information (step S75). Here, the terminal device 3C generates an ARP response frame in which the same MAC address as the source MAC address of the received ARP request frame is set as the destination MAC address. Next, the generated ARP response frame is transmitted from the terminal device 3A to the relay device 1A (step S76).

[0054] On the other hand, when the relay device 1A receives an ARP response frame at the wireless module 105A, it extracts the source MAC address information and the source IP address information of the received ARP response frame, and stores the extracted source MAC address information and the source IP address information in the extracted address storage unit 131 (step S77). Next, the relay device 1A converts the source MAC address of the received ARP response frame into a module MAC address that identifies the wireless module 105B of the relay device 1A (step S78). After that, the converted ARP response frame is transmitted from the relay device 1A to the relay device 1B (step S79). On the other hand, when the relay device 1B receives an ARP response frame at the wireless module 105C, it extracts the source MAC address information and the source IP address information of the received ARP response frame, and stores the extracted source MAC address information and the source IP address information in the extracted address storage unit 131 (step S80). Next, the relay device 1B converts the source MAC address of the received ARP response frame into a module MAC address that identifies the wireless module 105D of the relay device 1B (step S81). Then, the converted ARP response frame is transmitted from the relay device 1B to the relay device 1C (step S82). At this time, the relay device 1B transmits the converted ARP response frame to the relay device 1C via the wireless module 105D. Then, the converted ARP response frame is transmitted from the relay device 1C to the terminal device 3C (step S83). On the other hand, when the terminal device 3C receives the ARP response frame, it extracts the MAC address information of the terminal device 3A from the received ARP response frame, and stores the extracted MAC address information in the ARP table storage unit in association with the IP address information of the terminal device 3A (step S84).

[0055] Thereafter, as shown in FIG. 16, the terminal device 3C generates a connection request frame for requesting establishment of a connection to the terminal device 3A in the Internet layer (step S85). Here, the terminal device 3C generates a connection request frame in which the destination MAC address of the connection frame is set to the MAC address of the wireless module 105D of the relay device 1B extracted from the ARP response frame. Next, the generated connection request frame is transmitted from the terminal device 3C to the relay device 1C (step S86). On the other hand, when the relay device 1C receives the connection request frame, the received connection request frame is transmitted to the relay device 1B based on the destination MAC address (step S87). On the other hand, when the relay device 1B receives the connection request frame, the relay device 1B converts the destination MAC address of the received connection request frame into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit 131 (step S88). Specifically, relay device 1B converts the destination MAC address of the connection request frame from the MAC address of wireless module 105D to the MAC address of wireless module 105B of relay device 1A. Relay device 1B converts the destination MAC address of the connection request frame in this manner when the destination MAC address is its own device and the destination IP address matches the source IP address stored in extracted address storage unit 131. Next, the converted connection request frame is transmitted from relay device 1B to relay device 1A based on the converted MAC address (step S89).

[0056] On the other hand, when the relay device 1A receives a connection request frame, it converts the destination MAC address of the received connection request frame into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit 131 (step S90). Specifically, the relay device 1A converts the destination MAC address of the connection request frame from the MAC address of the wireless module 105B into the MAC address of the terminal device 3A. The relay device 1A converts the destination MAC address of the connection request frame in this manner when the destination MAC address is its own device and the destination IP address matches the source IP address stored in the extracted address storage unit 131. Then, the converted connection request frame is transmitted from the relay device 1A to the terminal device 3A based on the converted MAC address (step S91).

[0057] On the other hand, when the terminal device 3A receives a connection request frame addressed to itself, it generates a connection response frame (ACK frame) in which the source MAC address is set to the MAC address of its own device (step S92). After that, the generated connection response frame is transmitted from the terminal device 3A to the relay device 1A (step S93). On the other hand, the relay device 1A converts the source MAC address of the received connection response frame into a module MAC address that identifies the wireless module 105B of the relay device 1A (step S94). Next, the converted connection response frame is transmitted from the relay device 1A to the relay device 1B (step S95). At this time, the relay device 1A transmits the converted ARP response frame to the relay device 1B via the wireless module 105B. On the other hand, the relay device 1B converts the source MAC address of the received connection response frame into a module MAC address that identifies the wireless module 105D of the relay device 1B (step S96). Next, the converted connection response frame is transmitted from the relay device 1B to the relay device 1C (step S97). At this time, the relay device 1B transmits the converted connection response frame to the relay device 1C via the wireless module 105D. On the other hand, when the relay device 1C receives the connection response frame, the received connection response frame is transmitted from the relay device 1C to the terminal device 3C (step S98).

[0058] Thereafter, when the terminal device 3C receives the connection response frame, it generates a transmission start notification frame for notifying the terminal device 3A that it will start transmitting data frames. Then, the generated transmission start notification frame is transmitted from the terminal device 3C to the terminal device 3A in the same sequence as the above-mentioned connection request frame. In this way, a connection is established between the terminal devices 3A and 3C by a three-way handshake. Next, a data frame is transmitted from the terminal device 3C to the terminal device 3A in the same sequence as the above-mentioned connection request frame.

[0059] Next, the relay process executed by the relay device 1A according to the present embodiment will be described in detail with reference to Fig. 17 and Fig. 18. This relay process is started, for example, when the relay device 1 is powered on. Hereinafter, the wireless module 105A will be referred to as the "wireless module on the AP side," and the wireless module 105B will be referred to as the "wireless module on the STA side." In addition, the above-mentioned ARP request frame, ARP response frame, connection request frame, connection response frame, and transmission start notification frame will be collectively referred to as frames.

[0060] 17, frame acquisition unit 111 determines whether or not a frame has been acquired from wireless modules 105A and 105B (step S101). Here, as long as frame acquisition unit 111 determines that a frame has not been acquired from wireless modules 105A and 105B (step S101: No), it repeatedly executes the process of step S101.

[0061] On the other hand, when the frame acquisition unit 111 determines that the frame has been acquired (step S101: Yes), it stores the acquired frame in the frame buffer 121 (step S102). At this time, the frame acquisition unit 111 notifies the address extraction unit 112 of the acquired frame. Next, the address extraction unit 112 determines whether the frame has been received by the wireless module 105A on the AP side (step S103). Here, the address extraction unit 112 extracts a module MAC address included in the frame. Then, the address extraction unit 112 refers to the module MAC address information stored in the module address storage unit 132, and if the extracted module MAC address matches the module MAC address of the wireless module 105A on the AP side, it determines that the frame has been received by the wireless module 105A on the AP side. On the other hand, if the extracted module MAC address matches the module MAC address of the wireless module 105B on the STA side, the address extraction unit 112 determines that the frame has been received by the wireless module 105B on the STA side.

[0062] Here, when the address extraction unit 112 determines that the frame has been received by the wireless module 105A on the AP side (step S103: Yes), it notifies the address conversion unit 113 and the transmission control unit 114 of the wireless module identification information of the wireless module 105A that received the frame and the frame identification information that identifies the frame.

[0063] Next, the transmission control unit 114 judges whether or not the frame has been acquired from the terminal device 3A under the control of the own device (step S104). If the transmission control unit 114 judges that the frame has been acquired from the terminal device 3A under the control of the own device (step S104: Yes), the process of step S106 described later is executed. On the other hand, if the transmission control unit 114 judges that the frame has not been acquired from the terminal device 3A under the control of the own device (the frame has been received from a wireless module on the STA side of another relay device) (step S104: No), the transmission control unit 114 judges whether or not the frame is to be transmitted to the terminal device 3A under the control of the own device (step S105: Yes). If the transmission control unit 114 judges that the frame is to be transmitted to the terminal device 3A under the control of the own device (step S105: Yes), the process of step S114 described later is executed. On the other hand, if the transmission control unit 114 determines not to transmit the frame to the subordinate terminal device 3A of its own device (to transmit the frame to another relay device via the wireless module 105B on the STA side) (step S105: No), the process of step S107 is performed.

[0064] In step S106, it is determined whether or not the frame is to be transmitted using the wireless module 105A on the AP side. If the transmission control unit 114 determines that the frame is to be transmitted using the wireless module 105A on the AP side (step S106: Yes), the process of step S114 described below is executed. On the other hand, if the transmission control unit 114 determines that the frame is not to be transmitted using the wireless module 105A on the AP side (transmitted using the wireless module 105B on the STA side) (step S106: No), the process proceeds to step S107.

[0065] In step S107, the address extraction unit 112 extracts the source MAC address information and the source IP address information included in the frame notified by the frame acquisition unit 111, and stores the extracted source MAC address information and the source IP address information in the extracted address storage unit 131 (step S107). Next, the address conversion unit 113 converts the source MAC address of the frame identified by the frame identification information notified by the address extraction unit 112, stored in the frame buffer 121, into a module MAC address that identifies the wireless module 105B (step S108). Next, the transmission control unit 114 transfers the converted frame, in which the source MAC address has been converted, to the wireless module 105B on the STA side (step S109). At this time, the wireless module 105B on the STA side transmits the transferred frame to another predetermined relay device 1B. After that, the process of step S101 is executed again.

[0066] On the other hand, when it is determined in step S103 that the frame has been received by the wireless module 105B on the STA side (step S103: No), the address extraction unit 112 notifies the address conversion unit 113 and the transmission control unit 114 of the wireless module identification information of the wireless module 105B that received the frame and the frame identification information that identifies the frame. After that, the address conversion unit 113 determines whether or not the destination IP address of the frame stored in the frame buffer 121 and identified by the frame identification information notified by the address extraction unit 112 matches the source IP address stored in the extracted address storage unit 131 (step S110). Here, it is assumed that the address conversion unit 113 determines that the destination IP address of the frame identified by the frame identification information notified by the address extraction unit 112 matches the source IP address stored in the extracted address storage unit 131 (step S110: Yes). In this case, address conversion unit 113 converts the destination MAC address of the frame into a source MAC address associated with the source IP address stored in extracted address storage unit 131 (step S111). Here, address conversion unit 113 notifies transmission control unit 114 of the converted frame with the converted destination MAC address. Next, transmission control unit 114 transfers the frame to wireless module 105A on the AP side (step S112). At this time, wireless module 105A on the AP side transmits the transferred frame to subordinate terminal device 3A or another relay device based on the destination. Then, the process of step S101 is executed again.

[0067] Also, in step S110, it is assumed that the address conversion unit 113 determines that the destination IP address of the frame identified by the frame identification information notified from the address extraction unit 112 is different from the source IP address stored in the extracted address storage unit 131, or that the extracted address storage unit 131 does not store source MAC address information (step S110: No). In this case, as shown in FIG. 18, the address conversion unit 113 converts the destination MAC address of the frame into a MAC address for broadcast (step S113). Here, if the destination MAC address of the frame has already been set to a MAC address for broadcast, the address conversion unit 113 maintains the destination MAC address as the MAC address for broadcast. Then, the transmission control unit 114 transfers the frame to the wireless module 105A on the AP side. Thereafter, the wireless module 105A on the AP side transmits the transferred frame to a predetermined destination or broadcasts it without changing the MAC address (step S114). Then, the process of step S101 is executed again.

[0068] In order to generalize the processing described above using Figures 5 to 18, Figure 19 shows a table in which the handling of frames processed by a relay device in an embodiment of the present invention is organized according to the type of wireless module receiving the frame, the type of wireless module transmitting the frame, and the destination terminal device or relay device.

[0069] 19, first, the case where the AP-side wireless module of the relay device receives a frame is divided into four cases according to the following cases: the source of the frame is another relay device (wireless module on the STA side), the source of the frame is a terminal device under the own device, the destination of the frame is another relay device (wireless module on the AP side or wireless module on the STA side), and the destination of the frame is a terminal device under the own device. Among these, in the two cases of transmitting a frame received from a terminal device under the own device to another relay device and transmitting a frame received from another relay device to another relay device, the process of storing the MAC address of the source in extracted address storage unit 131 and changing it to the MAC address of the wireless module of the own device (STA side) occurs regardless of the type of frame.

[0070] On the other hand, the wireless module on the STA side receives frames only from frames transmitted from other relay devices (wireless module on the AP side). In either of the two cases, that is, when the destination of the received frame is another relay device (wireless module on the STA side) or when the received frame is transmitted to a terminal device subordinate to the own device using the wireless module on the AP side, a process occurs in which the destination MAC address is changed to the MAC address stored in the extracted address storage unit 131 of the own device (in the case of transmitting to a subordinate terminal device, that is, the MAC address of the terminal device). However, this process is not performed in the case of a broadcast frame such as an APR request frame, and in this case, the frame is forwarded as is.

[0071] As described above, according to the relay device 1 of the present embodiment, the address extraction unit 112 extracts source MAC address information of the ARP request frame and the connection request frame and stores it in the extracted address storage unit 131. Furthermore, the address conversion unit 113 converts the source MAC address of the ARP request frame and the connection request frame into a module MAC address to generate a converted ARP request frame and a connection request frame. Furthermore, the address conversion unit 113 converts the destination MAC address of the ARP request frame and the connection response frame into a source MAC address indicated by the source MAC address information stored in the extracted address storage unit 131 when processing the ARP request frame or the connection request frame to generate a converted ARP response frame and a connection response frame. Then, when the frame acquisition unit 111 acquires the ARP request frame and the connection request frame, the transmission control unit 114 controls the ARP request frame and the connection request frame to be transmitted from the wireless module 105A to the terminal device 3. Moreover, the transmission control unit 114 controls the wireless module 105B to transmit the converted ARP request frame and connection request frame to the other relay device 1. Furthermore, when the frame acquisition unit 111 acquires the ARP response frame and connection response frame, the transmission control unit 114 controls the wireless module 105A to transmit the converted ARP response frame and connection response frame to the other relay device 1. This allows, for example, when transmitting an ARP request frame, a connection request frame, an ARP response frame, or a connection response frame from each of the three relay devices 1 (1A, 1B, 1C) to the other relay device 1, to set the destination MAC address of the ARP request frame, the connection request frame, the ARP response frame, or the connection response frame to the MAC address of the other relay device 1 and transmit the frame. That is, the relay device 1 that is the source of the ARP request frame, the connection request frame, the ARP response frame, or the connection response frame can transmit the ARP request frame, the connection request frame, the ARP response frame, or the connection response frame to the other relay device 1, regarding itself as a so-called parent device and the other relay device 1 as a so-called child device.Therefore, even if each of the three relay devices 1 functioning as so-called parent devices does not have an inter-parent device communication function (e.g., WDS function) for transmitting and receiving frames with the other relay devices 1 functioning as parent devices, the three relay devices 1 can transmit and receive frames among each other. This makes it easy to add a new relay device 1 to the relay devices 1 that make up the network, which makes it easier to expand the network. Also, the inter-parent device communication function can be realized with an inexpensive configuration.

[0072] Although the embodiment of the present invention has been described above, the present invention is not limited to the configuration of the above-mentioned embodiment. For example, as shown in FIG. 20, the relay device 2001 may include only one wireless module 2105. In FIG. 20, the same components as those in the embodiment are given the same reference numerals as those in FIG. 2(A). Here, the wireless module 2105 has the same configuration as the wireless modules 105A and 105B described in the embodiment. In the relay device 2001 according to this modification, the CPU 101 loads a program stored in the auxiliary storage unit 103 into the main storage unit 102 and executes it, thereby functioning as a frame acquisition unit 111, an address extraction unit 112, an address conversion unit 113, a transmission control unit 114, a virtual AP 2151A, and a virtual STA 2151B as shown in FIG. 21. In FIG. 21, the same components as those in the embodiment are given the same reference numerals as those in FIG. 3. In addition, the module address storage unit 132 stores module MAC address information indicating the module MAC addresses assigned to the virtual AP 2151A and the virtual STA 2151B, respectively.

[0073] The virtual AP 2151A selects frames whose destination MAC address is set to a MAC address other than the MAC address of the virtual STA 2151B from among the frames received by the wireless module 2105. Then, the virtual AP 2151A adds module MAC address information indicating the module MAC address assigned to the virtual AP 2151A to the selected frame and transfers it to the frame acquisition unit 111. Note that the virtual AP 2151A realizes the functions of the wireless module 105A in FIG. 2(A) by software (dedicated program) for operating a wireless circuit.

[0074] The virtual STA 2151B selects frames whose destination MAC address is set to the MAC address of the virtual STA 2151B from among the frames received by the wireless module 2105. Then, the virtual STA 2151B adds module MAC address information indicating the module MAC address assigned to the virtual STA 2151B to the selected frame and transfers it to the frame acquisition unit 111. Note that the virtual STA 2151B realizes the functions carried out by the wireless module 105B in Fig. 2(A) by software (dedicated program) for operating a wireless circuit.

[0075] According to this configuration, since it is possible to provide a configuration having only one wireless module 2105, the hardware scale of the relay device 2001 can be reduced accordingly.

[0076] In the embodiment, an example of the relay device 1 including two wireless modules 105A and 105B has been described, but the number of wireless modules included in the relay device is not limited to two. For example, as shown in FIG. 22, the relay device 3001 may include a plurality of wireless modules 105B functioning as stations. In FIG. 22, the same components as those in the embodiment are denoted by the same reference numerals as those in FIG. 3. Here, the module address storage unit 132 stores the module MAC addresses assigned to the plurality of wireless modules 105B functioning as stations. In addition, in this relay device 3001, the CPU 101 loads a program stored in the auxiliary storage unit 103 into the main storage unit 102 and executes it, thereby functioning as the frame acquisition unit 111, the address extraction unit 112, the address conversion unit 3113, the transmission control unit 3114, and the module selection unit 3115. For a frame received by the wireless module 105A, the module selection unit 3115 selects a wireless module 105B to be used when transmitting the frame to another relay device from among the plurality of wireless modules 105B.

[0077] The address conversion unit 3113 identifies the MAC address information of the wireless module 105B selected by the module selection unit 3115 from the module MAC address information of each of the multiple wireless modules 105B stored in the module address storage unit 132. Then, the address conversion unit 3113 converts the source MAC address of the frame to the module MAC address of the identified wireless module 105B to generate a converted frame. Then, the transmission control unit 3114 transfers the converted frame to the wireless module 105B selected by the module selection unit 3115 based on the source MAC address information of the converted frame.

[0078] According to this configuration, wireless modules 105B functioning as multiple stations can communicate with multiple relay devices simultaneously.

[0079] The various functions of the relay devices 1, 2001, and 3001 according to the present invention can be realized by using a computer system equipped with a wireless communication module, without using a dedicated system. For example, a program for executing the above operations may be stored in a non-transitory recording medium (such as a CD-ROM) that can be read by the computer system and distributed to a computer connected to a network, and the program may be installed in the computer system to configure the relay devices 1, 2001, and 3001 that execute the above processes.

[0080] The method of providing the program to the computer is arbitrary. For example, the program may be uploaded to a server on a communication line and distributed to the computer via the communication line. The computer then starts up the program and executes it under the control of the OS in the same way as other applications. In this way, the computer functions as the relay device 1, 2001, 3001 that executes the above-mentioned processes.

[0081] Although the embodiment and the modified examples of the present invention have been described above, the present invention is not limited to these. The present invention includes appropriate combinations of the embodiment and the modified examples, and appropriate modifications thereto. [Industrial Applicability]

[0082] The present invention is suitable for a relay device used to construct a wireless network. [Explanation of symbols]

[0083] 1, 1A, 1B, 1C, 2001, 3001: relay device, 3, 3A, 3B, 3C: terminal device, 101: CPU, 102: main memory unit, 103: auxiliary memory unit, 105A, 105B, 105C, 105D, 105E, 105F, 2105: wireless module, 109: bus, 111: frame acquisition unit, 112: address extraction unit, 113, 3113: address conversion unit, 114, 3114: transmission control unit, 121: frame buffer, 131: extracted address storage unit, 132: module address storage unit, 2151A: virtual AP, 2151B: virtual STA, 3115: module selection unit, BR: bridge, AC: address management unit

Claims

1. a first wireless module that functions as an access point; a second wireless module that functions as a station; a module address storage unit that stores module MAC address information for identifying at least the second wireless module; a frame acquisition unit that acquires a first frame received by the first wireless module and a second frame received by the second wireless module; a transmission control unit that, when the frame acquisition unit acquires the first frame, transmits the first frame to a destination by transmitting the first frame to another relay device via the second wireless module or to a terminal device subordinate to the own device, and, when the frame acquisition unit acquires the second frame, controls the second frame to be transmitted to a destination by transmitting the second frame to another relay device via the first wireless module or to a terminal device subordinate to the own device; an address extraction unit that extracts source MAC address information indicating a source MAC address that identifies a source of the first frame; an extracted address storage unit that stores the source MAC address information; an address conversion unit that converts the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address to generate a converted first frame, and converts a destination MAC address that identifies a destination of the second frame, excluding a broadcast frame, obtained thereafter into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit to generate a converted second frame, the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; when the destination IP address of the second frame matches the source IP address stored in the extracted address storage unit, the address conversion unit converts the destination MAC address of the second frame to the source MAC address associated with the source IP address stored in the extracted address storage unit, and when the destination IP address of the second frame is different from the source IP address stored in the extracted address storage unit or the extracted address storage unit does not store the source MAC address information, the address conversion unit converts the destination MAC address of the second frame to a MAC address for broadcast. Relay device.

2. A first wireless module functioning as an access point; a second wireless module that functions as a station; a module address storage unit that stores module MAC address information for identifying at least the second wireless module; a frame acquisition unit that acquires a first frame received by the first wireless module and a second frame received by the second wireless module; a transmission control unit that, when the frame acquisition unit acquires the first frame, transmits the first frame to a destination by transmitting the first frame to another relay device via the second wireless module or to a terminal device subordinate to the own device, and, when the frame acquisition unit acquires the second frame, controls the second frame to be transmitted to a destination by transmitting the second frame to another relay device via the first wireless module or to a terminal device subordinate to the own device; an address extraction unit that extracts source MAC address information indicating a source MAC address that identifies a source of the first frame; an extracted address storage unit that stores the source MAC address information; an address conversion unit that converts the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address to generate a converted first frame, and converts a destination MAC address that identifies a destination of the second frame, excluding a broadcast frame, obtained thereafter into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit to generate a converted second frame, the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; when a destination IP address of the second frame matches a source IP address stored in the extracted address storage unit, the address conversion unit converts a destination MAC address of the second frame into the source MAC address associated with the source IP address stored in the extracted address storage unit; When the frame acquisition unit acquires the first frame having a source MAC address that is the same as the source IP address already stored in the extracted address storage unit and that differs from the source IP address already stored in the extracted address storage unit, the address extraction unit extracts the source MAC address information of the acquired first frame and updates the source MAC address information associated with the source IP address already stored in the extracted address storage unit with the extracted source MAC address information. Relay device.

3. A plurality of the second wireless modules are provided. The relay device according to claim 1 or 2.

4. A relay method using a relay device including a first wireless module functioning as an access point and a second wireless module functioning as a station, acquiring a first frame received by the first wireless module and a second frame received by the second wireless module; When the first frame is acquired, transmitting the first frame to another relay device via the second wireless module, or to a terminal device under the own device, thereby causing the first frame to be transmitted to a destination; When the second frame is acquired, controlling the second frame to be transmitted to a destination by transmitting the second frame to another relay device or to a terminal device under the own device via the first wireless module; extracting source MAC address information indicating a source MAC address that identifies a source of the first frame; storing the source MAC address information in an extracted address storage unit; a step of converting the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address stored in a module address storage unit that stores module MAC address information for identifying at least the second wireless module, to generate a converted first frame, and converting a destination MAC address identifying a destination of the second frame, excluding a broadcast frame, acquired thereafter into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit, to generate a converted second frame, the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; When a destination IP address of the second frame matches a source IP address stored in the extracted address storage unit, converting a destination MAC address of the second frame into the source MAC address associated with the source IP address stored in the extracted address storage unit; and if the destination IP address of the second frame is different from the source IP address stored in the extracted address storage unit, or if the extracted address storage unit does not store the source MAC address information, converting the destination MAC address of the second frame into a broadcast MAC address. Relay method.

5. A relay method using a relay device including a first wireless module functioning as an access point and a second wireless module functioning as a station, acquiring a first frame received by the first wireless module and a second frame received by the second wireless module; When the first frame is acquired, transmitting the first frame to another relay device via the second wireless module, or to a terminal device under the own device, thereby causing the first frame to be transmitted to a destination; When the second frame is acquired, controlling the second frame to be transmitted to a destination by transmitting the second frame to another relay device or to a terminal device under the own device via the first wireless module; extracting source MAC address information indicating a source MAC address that identifies a source of the first frame; storing the source MAC address information in an extracted address storage unit; a step of converting the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address stored in a module address storage unit that stores module MAC address information for identifying at least the second wireless module, to generate a converted first frame, and converting a destination MAC address identifying a destination of the second frame, excluding a broadcast frame, acquired thereafter into the source MAC address indicated by the source MAC address information stored in the extracted address storage unit, to generate a converted second frame, the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; When a destination IP address of the second frame matches a source IP address stored in the extracted address storage unit, converting a destination MAC address of the second frame into the source MAC address associated with the source IP address stored in the extracted address storage unit; when the first frame is acquired whose source MAC address is the same as the source IP address already stored in the extracted address storage unit and differs from the source IP address already stored in the extracted address storage unit, extracting source MAC address information of the acquired first frame, and updating the source MAC address information associated with the source IP address already stored in the extracted address storage unit with the extracted source MAC address information, Relay method.

6. A computer comprising: a frame acquisition unit that acquires a first frame received by a first wireless module functioning as an access point and a second frame received by a second wireless module functioning as a station; a transmission control unit that controls, when the frame acquisition unit acquires the first frame, to transmit the first frame to a destination by transmitting the first frame to another relay device via the second wireless module or to a terminal device subordinate to the own device, and, when the frame acquisition unit acquires the second frame, to transmit the second frame to a destination by transmitting the second frame to another relay device via the first wireless module or to a terminal device subordinate to the own device; an address extraction unit that extracts source MAC address information indicating a source MAC address that identifies a source of the first frame; an address conversion unit that converts the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address stored in a module address storage unit that stores module MAC address information for identifying at least the second wireless module, to generate a converted first frame, and that converts a destination MAC address identifying a destination of the second frame, excluding a broadcast frame, acquired thereafter into the source MAC address indicated by the source MAC address information stored in an extracted address storage unit that stores the source MAC address information, to generate a converted second frame; A program for causing the device to function as a the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; when the destination IP address of the second frame matches the source IP address stored in the extracted address storage unit, the address conversion unit converts the destination MAC address of the second frame to the source MAC address associated with the source IP address stored in the extracted address storage unit, and when the destination IP address of the second frame is different from the source IP address stored in the extracted address storage unit or the extracted address storage unit does not store the source MAC address information, the address conversion unit converts the destination MAC address of the second frame to a MAC address for broadcast. program.

7. Computer, a frame acquisition unit that acquires a first frame received by a first wireless module functioning as an access point and a second frame received by a second wireless module functioning as a station; a transmission control unit that controls, when the frame acquisition unit acquires the first frame, to transmit the first frame to a destination by transmitting the first frame to another relay device via the second wireless module or to a terminal device subordinate to the own device, and, when the frame acquisition unit acquires the second frame, to transmit the second frame to a destination by transmitting the second frame to another relay device via the first wireless module or to a terminal device subordinate to the own device; an address extraction unit that extracts source MAC address information indicating a source MAC address that identifies a source of the first frame; an address conversion unit that converts the source MAC address of a first frame to be transferred to the first wireless module of another relay device via the second wireless module into the module MAC address stored in a module address storage unit that stores module MAC address information for identifying at least the second wireless module, to generate a converted first frame, and that converts a destination MAC address identifying a destination of the second frame, excluding a broadcast frame, acquired thereafter into the source MAC address indicated by the source MAC address information stored in an extracted address storage unit that stores the source MAC address information, to generate a converted second frame; A program for causing the device to function as a the extracted address storage unit stores the source MAC address in association with the source IP address of the first frame; when a destination IP address of the second frame matches a source IP address stored in the extracted address storage unit, the address conversion unit converts a destination MAC address of the second frame into the source MAC address associated with the source IP address stored in the extracted address storage unit; When the frame acquisition unit acquires the first frame having a source MAC address that is the same as the source IP address already stored in the extracted address storage unit and that differs from the source IP address already stored in the extracted address storage unit, the address extraction unit extracts the source MAC address information of the acquired first frame and updates the source MAC address information associated with the source IP address already stored in the extracted address storage unit with the extracted source MAC address information. program.

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