Relay device, communication terminal information management method, and program
Patent Information
- Application Number
- JP2023074848
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-04-28
- Publication Date
- 2025-12-22
- Estimated Expiration
- Not applicable · inactive patent
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a relay device, a communication terminal information management method, and a program therefor. [Background technology]
[0002] Conventionally, a relay device that relays communication between a wired interface and a wireless interface while converting communication protocols and the like has been known. The relay device relays communication data that, for example, a communication terminal used by a user transmits to a server device or the like connected via a network device such as a wired base station device. In such a relay device, the relay device acquires a field related to the destination of communication data received from a device (e.g., a communication terminal or the like) connected to the wired interface side, rewrites the source MAC (Media Access Control) address contained in the acquired field to the MAC address of the relay device itself, and transmits the communication data from the wireless interface to a base station device (e.g., an access point or the like) via a wireless communication link. The relay device stores information (hereinafter also referred to as communication terminal information) that pairs the MAC address of the communication terminal with the IP (Internet Protocol) address set in the communication terminal in a correspondence information table (hereinafter also referred to as address conversion table). Even when communication data addressed to the IP address of the communication terminal is received from the base station device, the relay device can identify the MAC address that pairs with the received IP address, and as a result, can transmit the communication data to the communication terminal connected to the relay device. Patent Document 1 describes a relay device that performs such address conversion. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2013-051531 A Summary of the Invention [Problem to be solved by the invention]
[0004] However, when the capacity of the storage device (for example, memory) of the relay device itself is not abundant, the number of pieces of communication terminal information that can be stored in the address conversion table described above is limited (there is an upper limit). Therefore, in order to efficiently operate the address conversion table, it may be desirable to appropriately secure an area for storing communication terminal information by deleting (volatilizing) device information related to communication terminals that are not communicating after a predetermined time (hereinafter referred to as a first predetermined time) has elapsed, thereby appropriately managing the communication terminal information. Therefore, when communication is performed from a communication terminal to the relay device after the period for storing communication terminal information (corresponding to the first predetermined time in this embodiment) has elapsed in the address conversion table of the relay device, the relay device needs to store the communication terminal information again, which may cause a problem of communication delay. In addition, when communication is started from a device (for example, a server device, etc.) connected to the base station device to a communication terminal after the first predetermined time has elapsed, the relay device cannot transmit communication data to the communication terminal because there is no communication terminal information to be converted in the address conversion table, which may cause the same problem of communication delay as described above, and efficient communication cannot be performed.
[0005] The present invention has been made in view of the above circumstances, and its main object is to efficiently operate an address translation table while maintaining efficient communication. [Means for solving the problem]
[0006] In order to solve the above problem, a relay device according to one embodiment of the present invention is a relay device that is connected to one or more communication terminals via wired communication and relays between the communication terminals and a wireless network, and includes a first communication unit that exchanges communication data with the communication terminals, a second communication unit that exchanges communication data with any communication device via the wireless network, a timing unit that provides time information, a memory unit having an address conversion table that stores communication terminal information linked to each communication terminal, the source MAC address and source IP address of the communication terminal received by the first communication unit, and the storage start time, which is time information provided at the time when the connection with the communication terminal is started, a conversion unit that converts the source MAC address included in the communication data received by the first communication unit or the second communication unit based on the address conversion table, and a judgment unit that judges whether a first predetermined time for storing the communication terminal information has elapsed for the communication terminal information stored in the address conversion table, and judges the aliveness or deadness of the communication terminal corresponding to the communication terminal information for which it is determined that the first predetermined time has elapsed, and the memory unit deletes the communication terminal information of the communication terminal determined to be unable to communicate by the aliveness judgment from the address conversion table.
[0007] According to this, the relay device determines whether a first specified time for storing communication terminal information has elapsed for the communication terminal information stored in the address conversion table, and determines whether the communication terminal corresponding to the communication terminal information for which it has been determined that the first specified time has elapsed is alive or dead.By doing so, it is possible to delete from the address conversion table the communication terminal information of only those communication terminals that have been determined to be unable to communicate based on the alive or dead determination, thereby making effective use of the capacity of the storage device provided in the relay device, and suppressing communication delays that may occur due to the communication terminal information of communication terminals with which it is necessary to maintain communication being uniformly deleted from the address conversion table.
[0008] In addition, the judgment unit further identifies the communication terminal corresponding to the communication terminal information for which it has been determined that the first specified time has elapsed, notifies the first communication unit to send a device confirmation frame to the identified communication terminal, and determines whether the communication terminal is alive or dead by receiving a notification from the first communication unit as to whether a response frame that is a response to the device confirmation frame was received within a second specified time.
[0009] According to this, the relay device identifies the communication terminal corresponding to the communication terminal information for which it has determined that a first specified time has elapsed, transmits a device confirmation frame to the identified communication terminal, and receives notification as to whether a response frame that is a response to the device confirmation frame was received within a second specified time, thereby making it possible to determine whether the communication terminal is alive or dead, and to specifically know the communication terminal for which address conversion table communication needs to be maintained.
[0010] In addition, when the judgment unit receives communication data via the first communication unit from a communication terminal not stored in the address conversion table, it judges whether the storage capacity of the address conversion table will be equal to or greater than the maximum storage capacity of the storage unit if new communication terminal information is to be stored, and if it is determined that it will be equal to or greater than the maximum storage capacity, it notifies the first communication unit to send a device confirmation frame to the communication terminal corresponding to at least a portion of the communication terminal information stored in the address conversion table, and judges the alive or dead status of the communication terminal by receiving a notification from the first communication unit as to whether or not a response frame that is a response to the device confirmation frame has been received.
[0011] According to this, when the relay device receives communication data from a communication terminal not stored in the address conversion table, it becomes necessary to store new communication terminal information, but at that time, it judges whether the address conversion table will be equal to or larger than the maximum storage capacity for storing communication terminal information, and if it judges that it will be equal to or larger than the maximum storage capacity, it transmits a device confirmation frame to the communication terminals corresponding to all of the communication terminal information stored in the address conversion table. This allows the relay device to determine which communication terminal information should be deleted from the address conversion table based on the presence or absence of a response from the communication terminal to the confirmation frame, and it is possible to delete only unnecessary communication terminal information from the address conversion table and add new communication terminal information.
[0012] Furthermore, a communication terminal information management method according to one embodiment of the present invention is a communication terminal information management method in a relay device that is connected to one or more communication terminals via wired communication and relays between a wireless network, and includes the steps of: linking the MAC address and IP address information of communication data address information contained in communication data received from the communication terminal with a storage start time indicating the timing when the connection with the communication terminal was started for each communication terminal, and storing the MAC address and IP address information as communication terminal information in an address conversion table; determining whether a first predetermined time for storing the communication terminal information stored in the address conversion table has elapsed; determining the alive or dead status of the communication terminal corresponding to the communication terminal information for which it has been determined that the first predetermined time has elapsed; and deleting from the address conversion table the communication terminal information of a communication terminal that has been determined to be unable to communicate by the alive or dead status determination of the determination unit.
[0013] This provides the same effects as the relay device described above.
[0014] In addition, the above-mentioned communication terminal information management method further includes a step of determining whether the storage capacity of the address conversion table will be equal to or greater than the maximum storage capacity of the storage unit if new communication terminal information is to be stored when communication data is received from a communication terminal not stored in the address conversion table, and if it is determined that the storage capacity will be equal to or greater than the maximum storage capacity, a step of transmitting a device confirmation frame to the communication terminal corresponding to at least a portion of the communication terminal information stored in the address conversion table, and a step of determining whether the communication terminal is alive or dead by receiving a notification of whether a response frame, which is a response to the device confirmation frame, has been received.
[0015] This provides the same effects as the relay device described above.
[0016] Furthermore, a program according to one embodiment of the present invention is a communication terminal information management method in a relay device that is connected to one or more communication terminals via wired communication and relays between a wireless network, the program including the steps of: linking the MAC address and IP address information of the communication data address information contained in the communication data received from the communication terminal with a storage start time indicating the timing when the connection with the communication terminal started for each communication terminal, and storing the information in an address conversion table as communication terminal information; determining whether a first predetermined time for storing the communication terminal information stored in the address conversion table has elapsed; determining the alive or dead status of the communication terminal corresponding to the communication terminal information for which it has been determined that the first predetermined time has elapsed; and deleting the communication terminal information of the communication terminal determined to be unable to communicate by the alive or dead status determination of the determination unit from the address conversion table.
[0017] This provides the same effects as the relay device described above. Effect of the Invention
[0018] According to the present invention, the relay device appropriately deletes only unnecessary communication terminal information from the address conversion table, thereby making effective use of the capacity of the storage device equipped in the device itself, while also suppressing delays that may occur due to the random deletion of communication terminal information of communication terminals with which communication needs to be maintained from the address conversion table. [Brief description of the drawings]
[0019] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a communication system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing the relationship between the functions of the relay device according to the embodiment of the present invention. [Diagram 3] FIG. 3 shows an example of an address conversion table provided in the relay device according to the embodiment of the present invention. [Figure 4a] FIG. 4a shows an example of address information included in communication data address information of a communication data frame before a relay device according to an embodiment of the present invention converts an address. [Figure 4b] FIG. 4b shows an example of address information included in the communication data address information of the communication data frame after the relay device according to the embodiment of the present invention has performed address conversion. [Diagram 5] FIG. 5 is a sequence diagram showing a process performed when a first predetermined time has elapsed in the communication terminal information stored in the address conversion table in the relay device according to the embodiment of the present invention. [Figure 6] FIG. 6 is a sequence diagram showing a process performed when new communication terminal information is to be added to the address conversion table in the relay device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] Hereinafter, the embodiment will be specifically described with reference to the drawings. The embodiments described below each show a preferred specific example of the present invention. The numerical values, shapes, components, the layout and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, Elements not described in the independent claims showing the most general concept of the invention are described as optional elements constituting a more preferred embodiment. Note that the same elements are given the same reference numerals and descriptions thereof may be omitted.
[0021] (Embodiment) In this embodiment, we will describe a relay device or the like that can effectively utilize the capacity of the storage device of its own device while suppressing communication delays by checking the status of a communication terminal with which it wishes to maintain communication and deleting information about communication terminals that are no longer necessary from the storage device.
[0022] First, a communication system 100 according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing a configuration of the communication system 100 according to the present embodiment. As shown in Fig. 1, the communication system 100 includes a communication terminal 101, a relay device 102, a wireless communication link 103, a base station device 104, a server device 105, a communication link 106, and a communication link 107. The communication system 100 is a communication system in which data is exchanged between the communication terminal 101 and the server device 105 via the relay device 102 and the base station device 104.
[0023] The communication terminal 101 is a terminal equipped with a wired communication interface conforming to a wired communication standard such as IEEE (Institute of Electrical and Electronics Engineers) 802.3, and is, for example, a personal computer (PC), a multi-function printer (MFP), a point of sale (POS) terminal, or an industrial machine (e.g., computer numerical control (CNC) device, etc.), which is connected to the relay device 102 via a communication link 106. The communication terminal 101 transmits and receives communication data (e.g., data frames, etc.) between the relay device 102 and the server device 105 via the relay device 102 and the base station device 104. Note that, in this embodiment, as shown in FIG. 1, one communication terminal 101 is connected to the relay device 102, but the present invention is not limited to this, and a plurality of other communication terminals may be connected to the relay device 102 via, for example, a layer 2 switch, etc.
[0024] The relay device 102 is a communication device that relays communication between the communication link 106 and the wireless communication link 103. The relay device 102 includes a wired communication interface that complies with a wired communication standard such as IEEE802.3 and a wireless communication interface that complies with a wireless communication standard such as IEEE802.11ac, and transmits and receives communication data by converting the communication protocol and the type of communication data between the two interfaces, thereby relaying communication between the communication link 106 and the wireless communication link 103.
[0025] The wireless communication link 103 is a wireless communication path such as a wireless network realized by wireless communication conforming to a wireless communication standard such as IEEE802.11ac.
[0026] The base station device 104 is a communication device equipped with a wireless interface conforming to a wireless communication standard such as IEEE802.11ac. The base station device 104 is, for example, an access point that manages the connection of a wireless communication path related to the wireless communication link 103. The base station device 104 is equipped with a wireless communication interface and a wired communication interface, and relays communication between the wireless communication link 103 and the communication link 107. Note that the base station device 104 does not necessarily have to be equipped with a wired communication interface.
[0027] The server device 105 is, for example, a WEB server or a NAS (Network Attached Storage) server. The server device has a wired communication interface and is connected to the base station device 104 via a communication link 107. The server device 105 exchanges communication data with the communication terminal 101 and provides services such as services based on HTTP (Hyper Text Transport Protocol) and services such as provision of storage space to the communication terminal 101. The server device may have a wireless communication interface instead of a wired communication interface and be connected to the base station device 104 via the communication link 107. In this embodiment, as shown in FIG. 1, one server device 105 is connected to the base station device 104, but the present invention is not limited to this. A plurality of server devices different from the server device 105 may be connected to the base station device 104 via, for example, a layer 2 switch.
[0028] The communication link 106 is a wired communication path using a wired cable or the like that complies with a wired communication standard such as IEEE802.3, etc. The communication link 106 connects the communication terminal 101 and the relay device 102.
[0029] The communication link 107 is a wired communication path using a wired cable or the like that complies with a wired communication standard such as IEEE802.3. The communication link 107 connects the server device 105 and the base station device 104. Note that in this embodiment, the communication link 107 is described as a wired communication path, but is not limited to this, and may be realized by a wireless communication path that complies with a wireless communication standard such as IEEE802.11ac.
[0030] Next, each function of the relay device according to the present embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the configuration of relay device 102 according to the present embodiment.
[0031] 2, the relay device 102 includes a first communication unit 201, a conversion unit 202, a second communication unit 203, a determination unit 204, a timer unit 205, and a storage unit 206. The above-mentioned functions of the relay device 102 are realized by hardware such as a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a storage device (e.g., a non-volatile storage device such as an embedded multi media card (eMMC), a hard disk drive (HDD), or a solid state drive (SSD)), and a communication module. Specifically, the functions are realized by the CPU reading out a program stored in the storage device and executing it in cooperation with the hardware. In addition, the communication data exchanged between the first communication unit 201, the conversion unit 202, and the second communication unit 203 is appropriately converted according to the type of communication data according to a communication protocol that each functional unit can process.
[0032] The first communication unit 201 is a wired communication interface conforming to the IEEE802.3 standard or the like, and transmits and receives communication data between the communication terminal 101 and the relay device 102. When the first communication unit 201 receives communication data transmitted from the communication terminal 101, it transfers the received communication data to the conversion unit 202. Furthermore, the first communication unit 201 transmits the communication data transferred from the conversion unit 202 to the communication terminal 101. Furthermore, the first communication unit 201 transmits a device confirmation frame to a specific or all communication terminals 101 corresponding to the communication terminal information stored in the address conversion table 300 based on a notification from a determination unit 204 (described later), and notifies the determination unit 204 of whether or not a response frame has been received as a response to the device confirmation frame.
[0033] The conversion unit 202 performs a process (address conversion) of appropriately rewriting a destination or source address included in the communication data based on an address conversion table 300 (described later). Specifically, the conversion unit 202 appropriately rewrites the destination address so that the address indicates a destination suitable for communication related to the first communication unit and the second communication unit based on communication terminal information of a pair of a MAC address and an IP address in the address conversion table 300 stored in the storage unit 206. Furthermore, when the communication data received from the communication terminal 101 includes a pair of a new MAC address and an IP address that are not stored in the address conversion table 300, the conversion unit 202 adds the pair of the MAC address and the IP address to the address conversion table as new communication terminal information. In this way, the conversion unit 202 relays the communication data between different communication links by rewriting the destination address of the communication data. After completing the conversion of the address of the communication data, the conversion unit 202 transfers the communication data to the second communication unit. An example of the address conversion will be described in detail later.
[0034] The second communication unit 203 is a wireless communication interface conforming to the IEEE802.11ac standard or the like, and transmits and receives communication data between the relay device 102 and the base station device 104. When the second communication unit 203 receives communication data for which address conversion has been completed by the conversion unit 202, the second communication unit 203 transmits the communication data to the base station device 104. Furthermore, when the second communication unit 203 receives communication data from the base station device 104, the second communication unit 203 transfers the communication data to the conversion unit 202.
[0035] The determination unit 204 acquires time information measured by the timer unit 205, and refers to the storage start time of each of the plurality of identifiers stored in the address conversion table 300 to determine whether or not a period (first predetermined time) for storing the communication terminal information has elapsed. When the determination unit 204 determines that the first predetermined time has elapsed, the determination unit 204 notifies the first communication unit 201 to transmit a device confirmation frame (described later), which is a communication frame for determining whether or not the communication terminal 101 corresponding to the communication terminal information is alive, and determines whether or not the communication terminal 101 is alive (details will be described later). The determination of whether or not the first predetermined time has elapsed may be based on whether or not the first predetermined time has elapsed from the storage start time of the plurality of communication terminals 101 stored in the address conversion table 300, or the determination that the first predetermined time has elapsed may be triggered by the arrival of a specific time measured by the timer unit.
[0036] Furthermore, by referring to a destination or source address included in communication data received from the first communication unit 201 or the second communication unit 203, when it becomes necessary to add communication terminal information related to a new communication terminal 101 to the address translation table 300, the determination unit 204 determines whether the address translation table 300 will reach or exceed the maximum storage capacity for storing communication terminal information. In other words, the determination unit 204 determines whether the area in the address translation table 300 for storing communication terminal information reaches a saturated state. When the determination unit 204 determines that the address translation table 300 will reach or exceed the maximum storage capacity, the determination unit 204 transmits a device confirmation frame to all communication terminals 101 corresponding to the communication terminal information stored in the address translation table 300 via the first communication unit 201, determines whether the communication terminal is alive or dead based on the notification from the first communication unit 201 (described later), and notifies the storage unit 206 of the result of the determination.
[0037] Specifically, in checking and judging whether communication terminal 101 is alive, judgment unit 204 identifies communication terminal 101 based on communication terminal information stored in address conversion table 300, and transmits a device confirmation frame to the identified communication terminal 101 via first communication unit 201. When communication terminal 101 receives the device confirmation frame, it transmits a response frame (e.g., ACK (Acknowledgement) notification, etc.) to relay device 102 as a response to the transmitted device confirmation frame. After transmitting the device confirmation frame to communication terminal 101, first communication unit 201 notifies judgment unit 204 of the reception of the response frame. This allows judgment unit 204 to judge that communication terminal 101 is connected to relay device 102. On the other hand, if the first communication unit 201 cannot receive the response frame even after a predetermined time (second predetermined time) has elapsed due to the power being turned off or the connection being cut somewhere on the communication path after transmitting the device check frame to the communication terminal 101, the first communication unit 201 notifies the determination unit 204 of that fact (that the response frame has not been received). From this, the determination unit 204 can determine that the relay device 102 cannot communicate with the communication terminal 101 (is not connected).
[0038] The clock unit 205 measures time information. The clock unit 205 is realized by, for example, an RTC (Real Time Clock) and provides the measured time information in response to a request from another processing unit of the relay device 102. The time information may be measured based on a 12-hour or 24-hour clock, or may measure the elapsed time since the relay device 102 was powered on.
[0039] The storage unit 206 includes an address conversion table 300. The storage unit 206 stores (stores) in the address conversion table 300 "communication terminal information" that links the MAC address, IP address, and storage start time of the communication terminal 101 included in the communication data received by the first communication unit 201. Also, based on the determination result (notification) of the determination unit 204, the storage unit 206 deletes specific communication terminal information from the stored contents of the address conversion table 300.
[0040] Next, the address conversion table provided in the relay device according to the present embodiment will be described with reference to FIG.
[0041] 3 shows an example of the address translation table 300 provided in the relay device 102. In this example, there is a plurality of target communication terminals, and communication terminal information for three of them is shown. As shown in FIG. 3, the address translation table 300 has an identifier field 301, a MAC address field 302, an IP address field 303, and a storage start time field 304.
[0042] Identifiers for identifying individual pieces of communication terminal information, which are a set (pair or linked) of information including a MAC address, an IP address, and a storage start time, are stored in the identifier field 301. The identifiers are expressed, for example, by numbers such as decimal or hexadecimal numbers, letters such as the alphabet, or a combination of these numbers and letters, and an arbitrary identifier is assigned each time new communication terminal information is stored.
[0043] In the MAC address field 302, the MAC address of the communication terminal 101 connected to the relay device 102 is stored.
[0044] In the IP address field 303, an IP address given to the communication terminal 101 connected to the relay device 102 is stored.
[0045] The storage start time field 304 stores time information (also referred to as storage start time) indicating the timing (point in time) when the communication terminal information was added to the address conversion table 300. The storage start time is the time measured by the clock unit 205 included in the relay device 102 at the timing when the communication terminal information was added to the address conversion table 300. The time information stored in the storage start time field 304 may be, for example, the current time or the time that has elapsed since the relay device 102 was powered on.
[0046] In this way, the address conversion table 300 shown in FIG. 3 stores communication terminal information that links, for each communication terminal, the source MAC address and source IP address of the communication terminal, as well as the storage start time, which is time information provided at the time when the connection with the communication terminal is started.
[0047] (Explanation of flow according to embodiment) Next, a series of processes that relay device 102 according to this embodiment performs on address translation table 300 when a first predetermined time has elapsed for any communication terminal information will be described with reference to Fig. 5. The process flow in Fig. 5 is executed when a first predetermined time has elapsed for any one or more pieces of communication terminal information stored in address translation table 300. Note that Fig. 5 will be described on the premise of a series of processes performed in the exchange of communication data between communication terminal 101 and relay device 102.
[0048] Step S501 is a step in which the determination unit 204 determines whether or not a first predetermined time has elapsed for each of one or more specific pieces of communication terminal information stored in the address conversion table 300. If it is determined that the first predetermined time has elapsed, step S502 is executed (Yes in step S501), and if it is determined that the first predetermined time has not elapsed, step S501 is executed repeatedly until the first predetermined time has elapsed (No in step S501).
[0049] Step S502 is a step in which the first communication unit 201 transmits a device check frame to the specific communication terminal 101 for which it has been determined in step S501 that the first predetermined time has elapsed in order to check whether the specific communication terminal 101 is alive or dead.
[0050] Step S503 is a step in which the determination unit 204 determines whether or not a response frame is received within a second predetermined time from the specific communication terminal 101, which is the destination of the device check frame, via the first communication unit 201. If the first communication unit 201 receives a response frame from the specific communication terminal 101 (Yes in step S503), the determination unit 204 executes step S505, and if the response frame is not received from the specific communication terminal 101 even after the second predetermined time has elapsed, the determination unit 204 executes step S504 (No in step S503).
[0051] In step S504, the storage unit 206 deletes from the address translation table 300 the communication terminal information relating to the specific communication terminal 101 from which the response frame was not received in step S503.
[0052] Step S505 is a step in which storage unit 206 extends the storage period of communication terminal information related to a specific communication terminal 101 stored in address conversion table 300. Specifically, for example, when determination unit 204 determines that a response frame has been received from a specific communication terminal 101, storage start time 304 of the specific communication terminal information is updated to the time at which the response frame was received in step S503, thereby substantially extending the storage period of the specific communication terminal information.
[0053] Step S506 is a step in which the determination unit 204 determines whether the alive / dead determination has been completed for all communication terminals for which the first predetermined time has elapsed. When the determination unit 204 determines that the alive / dead determination has been completed for all communication terminals that are targets stored in the address conversion table 300 (i.e., the communication terminal 101 for which the first predetermined time has elapsed), the determination unit 204 executes step S501 again and waits for the first predetermined time related to the communication terminal information to elapse (Yes in step S506). On the other hand, when the alive / dead determination has not been completed for all target communication terminals (i.e., when it is determined that there are still communication terminals to be confirmed), the determination unit 204 specifies communication terminals, excluding the communication terminals for which the determination has already been completed, from among the target communication terminals stored in the address conversion table 300, and executes step S502 again (No in step S506).
[0054] In the present embodiment, as shown in Fig. 5, an example has been described in which step S502 to step S506 are executed to check and determine whether all communication terminals for which the first predetermined time has elapsed are alive or dead, but for example, the alive or dead check may be performed all at once in step S502 for all specific communication terminals 101 for which the first predetermined time has elapsed in step S501. For example, the first communication unit 201 may transmit a device check frame by broadcast communication to all specific communication terminals 101 in step S502 to check whether they are alive or dead.
[0055] Next, a series of processes related to deleting communication terminal information stored in address translation table 300 will be described with reference to Fig. 6, which are performed when relay device 102 according to this embodiment receives communication data including a new MAC address or IP address not stored in address translation table 300 from communication terminal 101. Note that Fig. 6 is described on the premise of a series of processes performed in the exchange of communication data between communication terminal 101 and relay device 102.
[0056] Step S601 is a step in which the first communication unit 201 receives communication data from the communication terminal 101. Specifically, the first communication unit 201 receives communication data from the communication terminal 101 having a new MAC address or IP address that is not stored in the address translation table 300. Upon receiving the communication data, the process in FIG. 6 is started.
[0057] Step S602 is a step in which, when it becomes necessary to add communication terminal information relating to a new communication terminal 101 to the address translation table 300 based on the MAC address or IP address included in the communication data received in step S601, the determination unit 204 determines whether or not the storage capacity of the address translation table 300 will be equal to or greater than the maximum storage capacity capable of storing communication terminal information if the information is additionally stored. If the determination unit 204 determines that the storage capacity will be equal to or greater than the maximum storage capacity (Yes in step S602), it executes step S603, and if the determination unit 204 determines that the storage capacity will not be equal to or greater than the maximum storage capacity (No in step S602), it executes step S607.
[0058] Step S603 is a step in which the first communication unit 201 transmits a device confirmation frame to all communication terminals 101 stored in the address translation table 300 in order to confirm whether the communication terminals 101 stored in the address translation table 300 are alive or dead. The device confirmation frame may be broadcast, multicast, or unicast.
[0059] Step S604 is a step in which the determination unit 204 determines whether or not a response frame has been received from the communication terminal 101. If a response frame has not been received from the communication terminal 101, step S605 is executed (No in step S604), and if a response frame has been received from the communication terminal 101, step S606 is executed (Yes in step S604). Note that, before executing step S606, the storage time in the communication terminal information may be extended for the communication terminal that has received the response frame by the same process as described in step S505.
[0060] Step S605 is a step in which the memory unit 206 deletes, from the communication terminal information stored in the address conversion table 300, communication terminal information relating to a specific communication terminal 101 that is determined to have not received a response frame within a specified time (second specified time) in the alive / dead determination performed by the determination unit 204.
[0061] Step S606 is a step in which the determination unit 204 determines whether or not the alive check of the communication terminals corresponding to all the communication terminal information stored in the address conversion table 300 has been completed. If the determination unit 204 determines that the alive check of all the communication terminals has been completed, it executes step S602 again (Yes in step S606), and if it determines that there are still communication terminals to be checked, it specifies the communication terminals excluding the communication terminals whose check has already been completed from the communication terminal information stored in the address conversion table 300, and executes step S603 again (No in step S606).
[0062] Step S607 is a step in which the memory unit 206 stores in the address conversion table 300 a new communication terminal that is a set (pair or linked) of information consisting of the MAC address, IP address, and storage start time measured by the timing unit 205 of the communication terminal 101 from which the response frame was received by the first communication unit 201.
[0063] 6, in the present embodiment, an example has been described in which steps S602 to S606 are executed to determine whether or not the address translation table 300 has reached the maximum storage capacity for storing communication terminal information, and alive / dead confirmation is performed for the communication terminals in order to secure the storage capacity of the address translation table 300, but, for example, in step S603, alive / dead confirmation may be performed once for all communication terminals 101 stored in the address translation table 300. For example, alive / dead confirmation may be performed by having the first communication unit 201 transmit a device confirmation frame by broadcast communication to all the communication terminals 101 in step S603.
[0064] The process (step S603) for checking whether the communication terminal 101 is alive or dead may be performed not for all communication terminals stored in the address translation table 300, but only for at least some of them, for example, for a specific communication terminal determined in advance. For example, when the administrator of the communication system 100 wants a guest user to temporarily use the relay device 102, the administrator intentionally checks whether the communication terminal is alive or dead using a device confirmation frame, and deletes the communication terminal information from the address translation table 300 on a priority basis, thereby enabling the communication system 100 to be operated efficiently. Here, the specific communication terminal determined in advance is, for example, a communication terminal that is expected to use the communication system 100 for a limited period of time, such as a communication terminal used by a guest user.
[0065] Furthermore, steps S603 to S605 may be performed for each communication terminal, rather than for all of them, and then the storage capacity may be checked in step S602 each time. When capacity becomes available, the address of the new communication terminal may be stored.
[0066] From here, an example of address conversion performed by relay device 102 when communication data is transmitted from a communication terminal to a server device will be described with reference to Fig. 4. Fig. 4a and Fig. 4b are examples of address conversion performed by relay device 102. Note that hereinafter Fig. 4a and Fig. 4b will be collectively referred to as Fig. 4, 401a and 401b will be collectively referred to as 401, 402a and 402b will be collectively referred to as 402, and 403a and 403b will be collectively referred to as 403.
[0067] FIG. 4 shows an example of address information included in the communication data frame communication data destination table before and after the relay device according to the embodiment of the present invention converts the address. More specifically, FIG. 4 shows an example of address information included in the header portion of the communication data. The communication data address information 400 is referred to when the relay device 102 or the base station device 104 transfers the communication data, and is appropriately rewritten when the relay device 102 or the base station device 104 relays the communication data. Specifically, FIG. 4a shows an example of the case where communication data is transmitted from the communication terminal 101 to the server device 105 (before converting the address). FIG. 4b shows an example after the relay device 102, which has received the communication data of FIG. 4a, rewrites various information of the communication data address information included in the received communication data to information suitable for relaying to the server device 105 (after converting the address).
[0068] In this embodiment, it is assumed that communication terminal 101 has a MAC address of "84:25:3f:00:00:01", relay device 102 has a MAC address of "84:25:3f:00:00:32", base station device 104 has a MAC address of "84:25:3f:00:00:80", and server device 105 has a MAC address of "84:25:3f:00:00:64". It is also assumed that communication terminal 101 is assigned an IP address of "192.168.56.4", and server device 105 is assigned an IP address of "192.168.56.8".
[0069] As shown in FIG. 4, communication data address information 400 includes type information 401 , MAC address information 402 , and IP address information 403 .
[0070] The communication data address information 400 includes information on pairs of MAC addresses for identifying the communication terminals of the destination and source of communication data and IP addresses assigned to the communication terminals. The relay device 102 and the base station device 104 exchange communication data based on the MAC address and IP address information contained in the communication data address information 400.
[0071] MAC address information 402 indicates a MAC address of a device that transmits communication data, such as communication terminal 101 or server device 105. Specifically, as shown in Fig. 4a, when communication data is transmitted from communication terminal 101 to server device 105, MAC address information 402a indicates the MAC address of communication terminal 101, which is the source, and indicates the MAC address of base station device 104 to which server device 105, which is the destination, is connected. Also, as shown in Fig. 4b, after relay device 102 updates the information of the communication data address information, MAC address information 402b indicates the MAC address of relay device 102, which is the source, and indicates the MAC address of base station device 104 to which server device 105, which is the destination, is connected.
[0072] IP address information 403 indicates an IP address assigned to a device that transmits communication data, such as communication terminal 101 or server device 105. Specifically, as shown in Figures 4a and 4b, both IP address information 403a and 403b indicate the IP address of communication terminal 101 and the IP address of server device 105, which is the transmission destination.
[0073] From here, the address conversion performed in relay device 102 until communication data transmitted from communication terminal 101 is relayed through relay device 102 and transmitted to server device 105 will be described. First, when the relay device 102 receives communication data from the communication terminal 101, it reads the communication data address information 400a included in the communication data and acquires information related to the destination of the communication data. Specifically, when the relay device 102 reads the communication data address information 400a, it refers to the type information 401 and refers to the MAC address information and IP address information set as the destination. The second communication unit 203 included in the relay device 102 sets the MAC address information and IP address information in the communication data address information 400 included in the communication data as the destination when transmitting the communication data, and the second communication unit 203 transmits the communication data to the base station device 104 based on this.
[0074] Next, the relay device 102 stores the MAC address "84:25:3f:00:00:01" of the communication terminal 101 included in the MAC address information 402a in the MAC address field 302 of the address conversion table 300, and associates the IP address "192.168.56.4" of the communication terminal 101 included in the IP address information 403a with the IP address field 303 of the address conversion table 300 and stores them as communication terminal information. Based on the communication terminal information related to the communication terminal 101 that is the source of the communication data in the address conversion table 300, the relay device 102 rewrites the source MAC address of the MAC address information 402a of the communication data address information 400a to "84:25:3f:00:00:32", and updates the communication data to the communication data address information 400b (FIG. 4b). Next, the relay device 102 transmits the communication data including the updated communication data address information 400b to the base station device 104.
[0075] When the base station device 104 receives communication data including the communication data address information 400b, the base station device 104 compares the information in its own address conversion table with the destination IP address information "192.168.56.8" included in the IP address information 403b of the received communication data address information 400b, and identifies the server device 105. Similarly, based on the information of the server device 105 identified from the address conversion table, the base station device 104 rewrites the MAC address information 402b from its own device's "84:25:3f:00:00:80" to the MAC address of the server device 105, "84:25:3f:00:00:64," and transmits the communication data to the server device 105. In this way, the communication data transmitted from the communication terminal 101 is transmitted to the server device 105 via the relay device 102.
[0076] In addition, with regard to the communication until the communication data transmitted from server device 105 is relayed by relay device 102 and transmitted to communication terminal 101, the address conversion process described in the explanation of Figure 4 can be applied appropriately by making server device 105 the source and communication terminal 101 the destination, so a detailed explanation will be omitted.
[0077] As described above, the relay device 102 according to the embodiment of the present invention stores communication terminal information, which is a set (pair or linked) of information including the MAC address, IP address, and storage start time clocked by the clock unit 205 included in the communication data transmitted by the communication terminal 101, in the address conversion table 300. The relay device 102 compares the time clocked by the clock unit 205 with the storage start time of the target identifier (communication terminal information of the communication terminal), and when a first predetermined time has elapsed, determines that the first predetermined time has elapsed for the communication terminal information. However, instead of mechanically (randomly) deleting the communication terminal information as in the conventional technology, the relay device 102 transmits a device confirmation frame to the communication terminal 101 corresponding to the communication terminal information, and deletes only the communication terminal information related to the communication terminal 101 that cannot receive a response frame to the device confirmation frame within a second predetermined time from the address conversion table 300.
[0078] Furthermore, when it becomes necessary to add communication terminal information relating to a new communication terminal 101 to address translation table 300, if relay device 102 according to the embodiment of the present invention determines that the address translation table is saturated, it transmits a device confirmation frame to all communication terminals 101 corresponding to the communication terminal information stored in address translation table 300. Relay device 102 deletes communication terminal information relating to communication terminals 101 that have not received a response frame to the device confirmation frame within a second predetermined time from address translation table 300. This allows relay device 102 according to the embodiment of the present invention to delete only unnecessary communication terminal information from address translation table 300.
[0079] In this way, the relay device of the embodiment of the present invention can appropriately delete unnecessary communication terminal information stored in the address conversion table, thereby effectively utilizing the capacity of the storage device (memory) equipped in the device itself, while also suppressing delays that occur when starting communication toward a communication terminal with which it is desired to maintain communication, due to the absence of communication terminal information in the address conversion table.
[0080] The present invention can be realized not only as an apparatus, but also as a method in which the processing means constituting the apparatus are steps, as a program for causing a computer to execute those steps, as a computer-readable storage medium such as a CD-ROM on which the program is recorded, or as information, data or signals indicating the program.These programs, information, data and signals may be distributed via a communication network such as the Internet. [Industrial Applicability]
[0081] The present invention can be applied to a relay device or the like to which a plurality of communication terminals are connected. [Explanation of symbols]
[0082] 100 Communication Systems 101 Communication terminal 102 Relay device 103 Wireless communication links 104 Base station equipment 105 Server device 106, 107 Communication links 201 1st Communications Department 202 Conversion unit 203 2nd Communications Department 204 Judgment section 205 Timing section 206 Memory section 300 Address Translation Table 301 Identifier Field 302 MAC Address Field 303 IP Address Field 304 Memory start time field 400a, 400b Communication data address information 401a, 401b type information 402a, 402b MAC address information 403a, 403b IP address information
Claims
1. A relay device connected to one or more communication terminals via wired communication and relaying between the communication terminals and the communication device via a wireless network, a first communication unit that transmits and receives communication data to and from the communication terminal; a second communication unit that transmits and receives communication data to and from the communication device via the wireless network; a timing unit that provides time information; a storage unit including an address conversion table that stores communication terminal information in which a source MAC address and a source IP address of the communication terminal received by the first communication unit, and a storage start time that is time information provided at the timing when a connection with the communication terminal is started, are linked to each communication terminal; a conversion unit that converts the source MAC address included in the communication data received by the first communication unit or the second communication unit based on the address conversion table; a determination unit that determines whether a first predetermined time for storing the communication terminal information has elapsed for the communication terminal information stored in the address conversion table via the first communication unit, and determines whether the communication terminal corresponding to the communication terminal information for which it has been determined that the first predetermined time has elapsed is alive or dead; Equipped with the storage unit deletes the communication terminal information of the communication terminal determined to be unable to communicate with the communication terminal based on the alive / dead determination from the address conversion table. Relay device.
2. The determination unit further Identifying the communication terminal corresponding to the communication terminal information for which it is determined that the first predetermined time has elapsed; notifying the first communication unit to transmit a device confirmation frame, which is a communication frame for determining whether the specified communication terminal is alive or dead, to the specified communication terminal; determining whether the communication terminal is alive or dead by receiving a notification from the first communication unit as to whether a response frame, which is a response to the device confirmation frame, has been received within a second predetermined time; The relay device according to claim 1 .
3. A relay device connected to one or more communication terminals via wired communication and relaying between the communication terminals and the communication device via a wireless network, a first communication unit that transmits and receives communication data to and from the communication terminal; a second communication unit that transmits and receives communication data to and from the communication device; a storage unit including an address conversion table that stores communication terminal information associated with at least a source MAC address of the communication terminal received by the first communication unit; a conversion unit that converts the source MAC address included in the communication data received by the first communication unit or the second communication unit based on the address conversion table; A determination unit, receiving communication data from a new communication terminal not stored in the address conversion table via the first communication unit, and when it becomes necessary to add the communication terminal information related to the new communication terminal to the address conversion table, determining whether or not the storage capacity of the address conversion table will become equal to or greater than the maximum storage capacity of the storage unit due to the addition of the new communication terminal information; If it is determined that the capacity will be equal to or greater than the maximum storage capacity, a first communication unit is notified to transmit a device confirmation frame, which is a communication frame for determining whether the communication terminals correspond to at least a portion of the communication terminal information stored in the address conversion table, to the communication terminals; a determination unit that determines whether the communication terminal is alive or dead by receiving a notification from the first communication unit as to whether a response frame that is a response to the device confirmation frame has been received; Equipped with Furthermore, the storage unit deletes the communication terminal information of the communication terminal that is determined to be unable to communicate with the communication terminal based on the alive / dead determination from the address translation table. Relay device.
4. 1. A communication terminal information management method in a relay device that is connected to one or more communication terminals via wired communication and relays between the communication terminals and the communication devices via a wireless network, comprising: a communication step of exchanging communication data with the communication terminal; a storage step of linking the MAC address and IP address information of the communication data address information included in the communication data received from the communication terminal via the communication step with a storage start time indicating the timing at which connection with the communication terminal was started for each communication terminal, and storing the linked information in an address conversion table as communication terminal information; a first determination step of determining whether or not a first predetermined time for storing the communication terminal information has elapsed for the communication terminal information stored in the address conversion table; a second determination step of determining whether the communication terminal corresponding to the communication terminal information for which it has been determined that the first predetermined time has elapsed is alive or dead; a deletion step of deleting, from the address translation table, the communication terminal information of the communication terminal determined in the second determination step to be unable to communicate with the communication terminal; A communication terminal information management method, comprising:
5. A communication terminal information management method in a relay device that is connected to one or more communication terminals via wired communication and relays between the communication terminals and the communication devices via a wireless network, comprising: a communication step of exchanging communication data with the communication terminal; a storage step of associating at least the MAC addresses of the communication terminals received through the communication step with each other and storing the MAC addresses as communication terminal information in an address conversion table; a third determination step of receiving communication data from a new communication terminal not stored in the address conversion table via the communication step, and determining whether or not the address conversion table will exceed a maximum storage capacity when it becomes necessary to add the communication terminal information related to the new communication terminal to the address conversion table by adding the new communication terminal information; a transmitting step of transmitting a device confirmation frame, which is a communication frame for determining whether the communication terminal is alive or dead, to the communication terminals corresponding to at least a part of the communication terminal information stored in the address conversion table when it is determined that the capacity will be equal to or greater than the maximum storage capacity; a fourth determination step of determining whether the communication terminal is alive or dead by receiving a notification of whether a response frame that is a response to the device confirmation frame has been received; Furthermore, in the storing step, the communication terminal information of the communication terminal determined to be unable to communicate with the communication terminal by the alive / dead determination is deleted from the address translation table. A method for managing communication terminal information.
6. A program for causing a computer to execute the communication terminal information management method according to claim 4.