JP2008061146A - Communication equipment and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide communication equipment and a communication method for properly selecting a server function and a client function even when a plurality of communication equipment are continuously started. <P>SOLUTION: When any DHCP server which assigns an IP address in response to a request from another node operating as a DHCP client does not exist within a communication available range, a generalization assignment part 260 makes a DHCP serve initialization part 220 create an address pool, and makes an autonomous assignment part 230 perform the address assignment of its own device based on an APIPA. A generalization assignment part 260 makes a DHCP server part 210 perform a DHCP server operation in parallel with the address assignment of its own device. In the case of performing address assignment to another node before deciding the IP address of its own device, the generalization assignment part 260 makes the DHCP server part 210 notify the assignment destination of the address that the address is temporary. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication apparatus and a communication method used in an IP (internet protocol) network that performs only one-hop communication without relaying communication, such as a wireless ad hoc network, and in particular, an IP address without a user operation. The present invention relates to a communication device and a communication method that are set autonomously.

  In many communication networks using IP such as the Internet, DHCP (dynamic host configuration protocol, see Non-Patent Document 1), which is a communication protocol in which a specific communication device dynamically assigns an IP address to another communication device, is often used. It has been. In such a communication network, an apparatus (hereinafter simply referred to as “initial setting”) that performs various initial settings (hereinafter simply referred to as “initial settings”) necessary to start IP communication including IP address settings with respect to a communication apparatus that uses a communication service (Hereinafter referred to as “DHCP server”) is arranged on the communication service provider side.

  On the other hand, in recent years, due to the expansion of network technology, it has been noted that IP communication functions that have been widely used in communication services in the past have been installed in electronic devices in homes and offices such as televisions, video decks, and game machines. Yes. Such electronic devices not only function as communication devices with each other to form a PAN (personal area network) and facilitate cooperation with other electronic devices, but also expandability of electronic devices and the degree of freedom of arrangement. Can be increased.

  However, since such a PAN does not use a communication service in which a DHCP server is arranged, each communication apparatus must be initialized in the PAN.

  In particular, when building a PAN at home, the user often does not have specialized knowledge about the network. For such a user, it is difficult to perform the initial setting, and the burden on the user is large. In addition, an electronic device does not always have an excellent user interface such as a keyboard or a mouse, as in a personal computer. Therefore, even if the user has specialized knowledge, there is a possibility that a great deal of labor is involved in performing the initial setting.

  Recently, with the advancement of wireless IP network technology represented by wireless local area network (LAN), Bluetooth (registered trademark), and ultra wideband (UWB), the IP communication function has become more diverse, including digital cameras and printers. It has come to be installed in electronic devices. Therefore, the number of communication devices constituting the PAN can be further increased in the future. It is troublesome for the user to perform initial settings one by one for such a large number of communication devices and check the operation.

  In order to reduce such a burden on the user, a DHCP server may be arranged in the PAN. However, when an abnormality occurs in the DHCP server, there is a problem that recovery is difficult particularly for a user who does not have specialized knowledge about the network.

  Therefore, each communication device itself is a technology for assigning its own IP address, and it has been conventionally performed to combine APIPA (automatic private IP addressing, see Non-Patent Document 2), also called Auto IP, with DHCP. (For example, see Patent Document 1 and Patent Document 2).

  Here, a conventional communication apparatus that performs initial setting by a combination of DHCP and APIPA will be described using an example of PAN.

  FIG. 14 is a system configuration diagram showing an example of the configuration of a PAN in which a conventional communication device is arranged. The wireless PAN 10 includes a first node 20-1 and a second node 20-2 as conventional communication devices capable of mutual IP communication. That is, the wireless communication path 30 exists between the first node 20-1 and the second node 20-2. Further, the first node 20-1 and the second node 20-2 have the same configuration.

  FIG. 15 is a block diagram showing the configuration of the node 20 as the conventional communication apparatus shown in FIG. Hereinafter, nodes other than the node to be described are referred to as “other nodes”.

  In FIG. 15, the node 20 includes a DHCP server unit 21, an autonomous allocation unit 22, a DHCP address acquisition unit 23, a general allocation unit 24, and a communication unit 25.

  The DHCP server unit 21 performs IP address allocation (hereinafter simply referred to as “address allocation”) in response to a request from another node. The autonomous allocation unit 22 performs the operation of APIPA in the address allocation of its own device. The DHCP address acquisition unit 23 performs an IP address acquisition process as a DHCP client that acquires initial setting information including an IP address from a DHCP server in the address assignment of the own device. The overall allocation unit 24 selects which one of APIPA and DHCP is used for address allocation of its own device, that is, which of the autonomous allocation unit 22 and the DHCP address acquisition unit 23 is used. The DHCP server unit 21, the autonomous allocation unit 22, the DHCP address acquisition unit 23, and the overall allocation unit 24 are software functions of the protocol stack. The communication unit 25 is a network interface for performing IP communication, and parameters necessary for IP communication such as an IP address of the own apparatus are set. When the power is turned on, the node 20 performs an initial setting for starting IP communication.

  FIG. 16 is a flowchart showing a flow of initial setting operation in the PAN 10 shown in FIG.

  When a node that functions as a DHCP server receives a DHCPDISCOVER message from another node, it sends out a DHCPOFFER message that presents an IP address to be assigned to that node. Accordingly, in step S41, the overall allocation unit 24 broadcasts the DHCP DHCPDISCOVER message generated by the DHCP address acquisition unit 23 and searches for surrounding nodes.

  In step S42, the overall allocation unit 24 determines whether there is a DHCP server in the vicinity (within the communicable range) based on whether a DHCPOFFER message has been received. If a DHCP server exists in the surrounding area (S42: YES), the overall allocation unit 24 determines that the own apparatus operates as a DHCP client to which an IP address is allocated from another node, and proceeds to step S43. If there is no DHCP server in the vicinity (S42: NO), the overall allocation unit 24 determines that its own device operates as a DHCP server that allocates an IP address to another node, and proceeds to step S44. .

  In step S43, the DHCP address acquisition unit 23 acquires an IP address as a DHCP client. Specifically, the DHCP address acquisition unit 23 transmits a DHCPREQUEST message requesting that the IP address presented from the DHCP server be used by the own device. In response to receiving the DHCPREQUEST message, the DHCP server returns a DHCPACK message indicating approval for the request. Then, the node 20 finishes the initial setting and continues to operate as a DHCP client.

  On the other hand, in step 44, the autonomous allocation unit 22 determines its own IP address by APIPA. Specifically, the autonomous allocation unit 22 generates an IP address using, for example, a random number, and broadcast-outputs an ARP Probe message for confirming a situation as to whether the generated IP address is used by another node. And the autonomous allocation part 22 acquires the produced | generated IP address, when there is no response from another node.

  Next, in step S45, the DHCP server unit 21 starts as a DHCP server, and creates an address pool indicating the definition range of IP addresses assigned to surrounding DHCP clients. Then, the node 20 operates as a DHCP server such as completing the initial setting and responding to the DHCPDISCOVER message sent from the DHCP client.

In this way, the conventional communication apparatus can switch between the operation as the DHCP client and the operation as the DHCP server according to the surrounding situation. Therefore, even if an abnormality occurs in any of the communication devices, a DHCP server is always arranged, and the PAN can function.
JP 2005-277937 A JP 2005-348337 A R. Droms, “Dynamic Host Configuration Protocol”, IETF RFC2131, 1997 S. Cheshire, B.M. Aboba and E.M. Guttman, “Dynamic Configuration of IPv4 Link-Local Addresses”, IETF RFC 3927, 2005.

  However, in the PAN in which the above-described conventional communication device is arranged, for example, a problem may occur when a plurality of communication devices are activated in succession.

  FIG. 17 is a sequence diagram illustrating an example of the operation of each node 20 and the state of signals when each node 20 of the PAN 10 illustrated in FIG. 14 performs initial setting. Here, the first node 20-1 is powered on first, but the second node 20-2 is powered on when the initial setting of the first node 20-1 has not been completed. An example of this is illustrated.

In step S51, the time _{t 0,} the first node 20-1 is turned power-on (ON) state, the second node 20-2 remained power-off (OFF) state.

In step S52, the first node 20-1, immediately after time _{t 0,} broadcasts outputs a DHCPDISCOVER message. However, since the second node 20-2 is in an OFF state at this time, no response is returned to the first node 20-1.

  In step S53, the first node 20-1 enters the autonomous setting state because no response is returned to the DHCPDISCOVER message in step S52.

  In step S54, it is assumed that the second node 20-2 is turned on immediately after the first node 20-1 enters the autonomous setting state in step S53.

  In step S55, the second node 20-2 broadcasts a DHCPDISCOVER message. However, at this time, since the first node 20-1 has not yet been activated as a server, no response is returned to the second node 20-2.

  In step S56, the first node 20-1 selects an IP address to be allocated to the own device, and sends an ARP Probe message for confirming the status specifying the selected IP address three times at intervals of 1 to 2 seconds. Broadcast output. The first node 20-1 selects, for example, “192.168.1.1” as the IP address assigned to the own device.

  When each node 20 receives an ARP Probe message designating an already used IP address, it notifies that fact. However, since the IP address has not yet been assigned to the second node 20-2 at the time of step S56, the response to the ARP Probe message of the status confirmation at step S56 is returned to the first node 20-1. Not come.

  In step S57, the second node 20-2 enters the autonomous setting state because the response to the DHCPDISCOVER message in step S55 is not returned.

  In step S58, the second node 20-2 selects an IP address to be allocated to the own device, and broadcasts an ARP Probe message for confirming the status specifying the selected IP address. Here, the second node 20-2 selects, for example, “192.168.2.1” as the IP address assigned to the own device. However, at this time, since the first node 20-1 has not yet started the operation as a server, no response is returned to the second node 20-2.

  In step S59, it is assumed that the first node 20-1 has timed out without receiving any response to the status confirmation ARP Probe message sent in step S56. Due to this timeout, the first node 20-1 determines that there is no problem in using the requested IP address in the own device, determines the IP address of the own device, and shifts to the DHCP server operating state.

  In step S60, the first node 20-1 broadcasts and outputs an ARP Probe message of a usage request notifying the start of use of the selected IP address, and generates an address pool. However, at this time, since the second node 20-2 has not yet started the operation as a server and the IP address of its own device has not been determined, the response to the first node 20-1 is not received. I will not return.

  In step S61, the second node 20-2 determines that the ARP Probe message sent in step S58 has timed out without any response, and thus the DHCP server as in the first node 20-1. Transition to the operating state.

  In step S62, the second node 20-2 broadcasts an ARP Probe message requesting use, and generates an address pool.

  As a result, as is clear from FIG. 17, both the first node 20-1 and the second node 20-2 operate as servers, and set their own IP address and address pool independently of each other. To do. In such a state, these IP addresses and address pools overlap, and for example, the same IP address may be assigned to different nodes, and problems such as IP communication being disabled between those nodes may occur. There is.

  In order to avoid such a situation, it is also conceivable that the communication apparatus that is first turned on starts the server function completely and then the other communication apparatus is turned on. However, since confirmation of the status of the ARP Probe message normally requires a time of 4 seconds or more, it takes a relatively long time to turn on the power of the second communication apparatus. On the other hand, particularly when a PAN is formed in a very narrow range such as in a home, as a normal operation, power is continuously turned on to a plurality of communication devices. Therefore, the user is forced to perform an unnatural operation, and a problem arises in terms of usability.

  The present invention has been made in view of such a point, and provides a communication device and a communication method capable of appropriately selecting a server function and a client function even when a plurality of communication devices are activated in succession. For the purpose.

  The communication device according to the present invention includes a client operation unit that requests the node to assign an IP address to the own device when the node to which the IP address is assigned to the other node is within the communication range, Server operation unit that autonomously assigns an IP address to its own device and assigns an IP address to another node based on the IP address when a node that assigns an IP address to the node does not exist within the communicable range And an assignment determination unit for determining whether the same address as the IP address assigned to the own device by the server operation unit is already assigned to another node, the assignment determination unit, and the server operation unit Before determining that the same address as the IP address assigned to the server is not already assigned to another node. There when allocating the IP address to another node, a configuration in which allocation of the IP address includes a temporary setting notifying unit that notifies that this is the temporary for the assignee.

  In the communication method of the present invention, a server presence / absence determining step for determining whether or not a node to which an IP address is assigned to another node exists within a communicable range, and a node to which an IP address is assigned to another node can communicate When it is determined that the node does not exist within the range, the IP address is autonomously assigned to the own device, and when it is determined that the node to which the IP address is assigned to another node is within the communicable range, An address acquisition step for requesting assignment of an IP address to the own device and a process of assigning an IP address to another node based on the IP address when the IP address is autonomously assigned to the own device The same address as the IP address assigned to the local device has already been assigned to another node A process start step for starting a process for determining whether or not an IP address is assigned to another node before determining that the same address as the IP address assigned to the own device has not already been assigned to another node. When performing, the provisional setting notification step of notifying that the assignment of the IP address is provisional to the assignment destination is provided.

  According to the present invention, even before the IP address of the own device is determined, provisional address assignment is performed after notifying other nodes of duplication of IP address assignment or the possibility of change. Even when a plurality of communication devices are turned on in succession, the DHCP server function and the DHCP client function can be appropriately selected, so that the usability can be improved. Furthermore, since the IP address is assigned to another node at an early stage before the IP address of the own device is determined, the rising speed of the PAN can be increased.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram showing a configuration of a wireless PAN in which a communication device according to an embodiment of the present invention is arranged.

  In FIG. 1, the wireless PAN 100 includes a first node 200-1 and a second node 200-2. The first node 200-1 and the second node 200-2 are capable of wireless IP communication with each other, and a wireless communication path 300 is formed between them. Further, the parts related to the communication between the first node 200-1 and the second node 200-2 have the same configuration.

  The first node 200-1 and the second node 200-2 are, for example, a television and a hard disk recorder, and record video data by transferring video data received by the television to the hard disk recorder. is there. Since the video data is transmitted through the wireless communication path 300, the installation location of the hard disk recorder can be selected more freely.

  Hereinafter, the configuration and operation of each node 200 will be described. Nodes other than the node to be described are referred to as “other nodes”.

  FIG. 2 is a block diagram showing a configuration of node 200 as a communication apparatus according to the present embodiment.

  In FIG. 2, the node 200 includes a communication unit 210, a DHCP server unit 220, a DHCP server initial setting unit 230, an autonomous allocation unit 240, a DHCP address acquisition unit 250, a PAN designation determination unit 260, a general allocation unit 270, an application unit 280, And an application communication unit 290.

  The communication unit 210 is a network interface for performing wireless IP communication, and parameters necessary for IP communication such as an IP address of the own apparatus are set.

  The DHCP server unit 220 performs address assignment in response to a request from another node operating as a DHCP client. Specifically, when the DHCP REQUEST message is received by the communication unit 210, the DHCP server unit 220 assigns an IP address to the transmission source of the message via the communication unit 210.

  The DHCP server initial setting unit 230 performs an initial setting for the DHCP server unit 220 in order to cause the own device to function as a DHCP server when there is no DHCP server around the own device.

  The autonomous allocation unit 240 performs the operation of APIPA in address allocation for the own device. Specifically, the autonomous assignment unit 240 assigns an address to the own device, and checks whether the assigned IP address is already used by another node via the general assignment unit 270 and the communication unit 210. Do.

  The DHCP address acquisition unit 250 requests the other node 200 operating as a DHCP server to assign an IP address as a DHCP client in address assignment to the own device. Specifically, the DHCP address acquisition unit 250 acquires and acquires an IP address from the other node 200 that operates as a DHCP server, for example, by sending a DHCPREQUEST message via the overall allocation unit 270 and the communication unit 210. An IP address is assigned to the own device.

  The PAN designation determination unit 260 compares the IP address acquired by the DHCP address acquisition unit 250 with the IP addresses of the surrounding nodes, and determines whether or not there is a possibility that both are duplicated. Specifically, the PAN designation determination unit 260 acquires the transmission source IP address of the IP packet received by the communication unit 210, compares the IP address acquired by the DHCP address acquisition unit 250, and if they match. Performs processing for the IP address.

  The overall allocation unit 270 controls each unit of the own device and selects a method used for address allocation to the own device.

  The application unit 280 is application software that uses IP communication, and has a function of transmitting and receiving video data via the communication unit 210, for example. Further, the application unit 280 controls the communication unit 210 using the application communication unit 290 when performing IP communication.

  The application communication unit 290 notifies the application unit 280 of the status of the DHCP address acquisition unit 250 and controls the communication unit 210 according to an instruction from the application communication unit 290.

  Further, although not shown, the node 200 may be a CPU (central processing unit), a storage medium such as a ROM (read only memory) storing a control program, a working memory such as a RAM (random access memory), and a communication circuit. realizable. The function of each unit described above is realized by the CPU executing the control program.

  The node 200 operates as a DHCP client in an initial state, and switches to a mode in which it operates as a DHCP server according to surrounding conditions. The overall allocation unit 270 controls and switches the operation state of the node 200 in cooperation with other units. Hereinafter, the operation of each part of the node 200 will be described in detail.

  FIG. 3 is a flowchart showing the transition of the operation state of the node 200.

  In an initial state, the node 200 is in a power-off state 1000 where power is not turned on. When the power is turned on in this state, the node 200 transits to a DHCP client operation state 2000 that operates as a DHCP client.

  In the DHCP client operating state 2000, the node 200 first attempts to acquire an IP address from another node operating as a DHCP server using DHCP. If the acquisition of the IP address is successful, the DHCP client operation state 2000 is continued as it is, and the client initial setting process and the temporary setting cancellation determination process are executed.

  The client initial setting process is a process of setting the IP address acquired from the server in the own apparatus. The temporary setting cancellation determination process is a process of determining cancellation of the temporary setting based on a packet received from the DHCP server when the IP address setting of the own apparatus is the temporary setting. The client initial setting process and the temporary setting cancellation determination process will be described in detail later with reference to FIGS. 11 and 12, respectively.

  On the other hand, when the acquisition of the IP address from the node fails, the node 200 transitions to a DHCP server operating state 3000 that operates as a DHCP server.

  In the DHCP server operating state 3000, the node 200 executes a server initial setting process and an IP address assignment process.

  The server initial setting process is a process for setting the IP address and address pool of the own apparatus. The IP address assignment process is a process for assigning an IP address in response to a request from another node operating as a DHCP client. The server initial setting process and the IP address assignment process will be described later in detail with reference to FIGS. 4 and 10, respectively.

  The node 200 that operates as a DHCP server executes an IP address assignment process in parallel with the server initial setting process, thereby assigning an address to another node 200 that operates as a DHCP client before the server initial setting process is completed. Makes it possible to do. However, it notifies the address assignment target node 200 that the address assignment is temporary.

  When the node 200 is turned off or the communication function of the node 200 is reset while in the DHCP client operation state 2000 or the DHCP server operation state 3000, the process returns to the power-off state 1000. become. Therefore, when the DHCP server function is once transferred to the other node 200 in the same wireless PAN 100 after the operation as the DHCP server is started, both powers are turned off, and the node 200 on the side that wants to function as the DHCP server is connected first. The power may be turned on. Further, the timing of turning off the power and turning on the power may be controlled automatically.

  FIG. 4 is a flowchart showing the flow of the server initial setting process executed in the DHCP server operation state 3000 of FIG.

  In step S3110, the DHCP server initial setting unit 230 generates an address pool in response to a request from the overall allocation unit 270, and determines the first IP address of the generated address pool as the IP address of the own device.

  FIG. 5 is an explanatory diagram showing an example of an IP address system and an example of an IP address in the wireless PAN 100 shown in FIG.

  In the wireless PAN 100, each node 200 employs IPv4 (IP version 4) as a communication protocol. Each node 200 handles the IP address 310 by dividing it into three bit strings of a network address 301, a PAN specifying unit 302, and a node specifying unit 303. The reason why the PAN specifying unit 302 and the node specifying unit 303 are set is to make it easier to detect this when an IP address is assigned redundantly between nodes. This will be described in detail later. Here, an example of the IP address 310 is described in decimal notation 311, binary notation 312 every 8 bits, and decimal notation 313 in which the lower 16 bits are separated by the PAN specifying part 302 and the node specifying part 303. .

  The network address 301 is a bit string that is common to all the nodes 200 belonging to the same wireless PAN 100 and to which a given value is assigned. Nodes having the same network address 301 can communicate with each other. Here, the network address 301 is 16 bits, and for example, “192.168.” Is specified in decimal notation 313. The netmask corresponds to the number of bits of the network address 301, which is “255.255.0.0” here.

  The reach of the wireless interface in the wireless PAN 100 is relatively short. For this reason, a plurality of wireless PANs 100 are formed at relatively close distances, and wireless communication areas of the plurality of wireless PANs 100 may overlap due to the movement of the node 200. Then, nodes 200 that should belong to different wireless PANs 100 may connect and perform wireless communication. In this case, when the nodes 200 of the wireless PANs 100 configured in different places start communication, if the network address 301 is different, it may be necessary to change the routing setting or the like. Therefore, in this embodiment, a common network address is used for the nodes 200 of all the wireless PANs 100.

  The PAN specifying unit 302 is a bit string for specifying the wireless PAN 100 in the IP address 310. Here, the PAN specifying unit 302 is 12 bits, and for example, “32” is specified in decimal notation 313. Therefore, 2 12 (= 4,096) wireless PANs 100 can be designated.

  The node specifying unit 303 is a bit string for specifying the node 200 in the IP address 310. Here, the node designating unit 303 is 4 bits, and for example, “1” is designated by decimal notation 313. Thus, since the number of bits of the node designating unit 303 is small, it is possible to easily detect duplication of the IP address 310 in the same wireless PAN 100.

  Note that the arrangement and bit length of each of the network address 301, the PAN specifying unit 302, and the node specifying unit 303 are not limited to the above contents. Also, an address of another communication protocol such as IPv6 (IP version 6) may be applied. Furthermore, it is also possible to use a class A private address such as “10.x.x.x”. In this case, the PAN designation unit 302 and the node designation unit 303 can take 24 bits.

  FIG. 6 is an explanatory diagram showing an example of the configuration of the address pool generated by the DHCP server initial setting unit 230. The address pool 350 includes a plurality of fields describing an IP address 310, an allocation state 351, and a MAC (media access control) address 352, respectively. Here, a case where the network address of the IP address 310 and the value of the PAN specifying unit are the same as those in FIG. 5 is illustrated.

  An IP address in which the network address 301 and the PAN specifying unit 302 are the same is “192.168.1.0 to 192.168.1.15”. Therefore, among these IP addresses 310, except for the broadcast address “192.168.1.0” that cannot be assigned to the node 200, “192.168.1.1 to 192.168.1.15” Are described in the field of the IP address 310.

  In the assignment state 351, information indicating the assignment state of the corresponding IP address 310 is described. “Free” indicates that the corresponding IP address 310 is not assigned to any node 200. “Reserving” indicates that the corresponding IP address 310 is reserved in one of the nodes 200 but has not been assigned yet. “In use” indicates that it is assigned to any node 200 and is being used.

  The MAC address 352 describes the MAC address of the node 200 to which the corresponding IP address 310 is reserved or assigned.

  If the value of the PAN designation 302 is different for each node 200 functioning as a DHCP server, the IP address 310 does not overlap between the address pools 350. The value of the PAN specifying unit 302 is also used for the IP address 310 of the node 200 that functions as a DHCP server. Therefore, it is possible to determine whether or not the IP addresses 310 described in the respective address pools 350 are duplicated only by comparing the PAN specifying unit 302 of the IP address 310 of the node 200 functioning as a DHCP server.

  In step S3110 of FIG. 4, the DHCP server initial setting unit 230 selects and determines the value of the PAN specifying unit 302 shown in FIG. 5 with a random number, and combines the given network address 301 with the address pool 350 shown in FIG. It is generated and held in the DHCP server unit 220. Then, the DHCP server initial setting unit 230 determines the first IP address of the generated address pool 350 as the IP address of the own device. Then, the DHCP server initial setting unit 230 sets the determined IP address (hereinafter referred to as “temporary server address”) in the communication unit 210 via the overall allocation unit 270. That is, a temporary server address is assigned to the own device.

  Next, in step S3120, the autonomous allocation unit 240 sends a status confirmation ARP Probe message, which is a request for confirming that the temporary server address is not used in the surrounding nodes, to the overall allocation unit 270 and the communication unit 210. Broadcast output via

  FIG. 7 is an explanatory diagram showing the configuration of an ARP Probe message for status confirmation.

  A packet used in ARP has an “Opcode” field 401 for describing the type of message. The packet used in the ARP includes a “sender hardware address” field 402 for describing the hardware address of the transmission source, a “sender IP address” field 403 for describing the IP address of the transmission source, and a processing target. A “target hardware address” field 404 for describing a hardware address to be processed, and a “target IP address” field 405 for describing an IP address to be processed.

  In the case of the ARP Probe message 410 for status confirmation, as shown in FIG. 7, a value “1” indicating an ARP request is described in the “Opcode” field 401. Further, the MAC address of the device itself is described in the “sender hardware address” field 402, and the value “0” is described in the “sender IP address” field 403 and the “target hardware address” field 404. In the “target IP address” field 405, the temporary server address determined in step S3110 is described.

  In step S3130 of FIG. 4, the autonomous allocation unit 240 monitors the input of a response to the status confirmation ARP Probe message output in step S3120.

  When each node 200 has already assigned an IP address to its own device and receives the status confirmation ARP Probe message 410 in which the same IP address is described in the “target IP address” field 405, the IP address An ARP response indicating address duplication is broadcasted. Specifically, an IP address that matches the description of the “sender IP address” field 403 of the ARP Probe message 410 is assigned, and a MAC address different from the description of the “sender hardware address” field 402 of the ARP Probe message 410 of the status confirmation is assigned. The ARP response is output from the node 200 having the same.

  FIG. 8 is an explanatory diagram showing the structure of the ARP response, and corresponds to FIG.

  In the case of the ARP response 420, the “Opcode” field 401 describes a value “2” indicating a response to the ARP request. Unlike the ARP Probe message 410 for status confirmation, the “sender IP address” field 403 describes the IP address of the transmission source of the ARP response 420. In the “sender hardware address” field 402, the MAC address of the transmission source of the ARP response 420 is described.

  When the node 200 that has output the status confirmation ARP Probe message 410 in Step 3120 of FIG. 4 receives the ARP response 420 illustrated in FIG. 8 from the other nodes 200, the node 200 describes the “sender IP address” field 403 in the ARP response 420. The value of the PAN designation unit 302 of the IP address 310 of the other node included is compared with the value of the PAN designation unit 302 of the IP address 310 assigned to the own device. If they match, the node 200 that uses the same IP address as the temporary server address determined in step S3110 is present in the surroundings although it cannot communicate directly.

  Therefore, if there is an input of the status confirmation ARP response 420 before the timeout occurs, the autonomous allocation unit 240 returns to step S3110 and reselects the IP address of the own device. If the timeout has occurred, the process proceeds to step S3140. For example, 1 second is set as the timeout time.

  In step S3140, the autonomous allocation unit 240 determines whether a timeout has occurred for three or more consecutive times in the status confirmation of the IP address. If it is less than three times (S3140: NO), the process returns to step S3120, and the status confirmation ARP Probe message 410 is output again. If the timeout is 3 times or more (S3140: YES), the temporary server address is used by the own device, assuming that there is no node using the same IP address as the temporary server address determined in step S3110. The IP address is selected and the process proceeds to step S3150.

  In step S3150, the autonomous allocation unit 240 generates an ARP Probe message (ARP Announcement) of a usage request for notifying that the temporary server address is used by the own device, and outputs the generated ARP Probe message via the overall allocation unit 270 and the communication unit 210. .

  FIG. 9 is an explanatory diagram showing the configuration of the ARP Probe message for use request, and corresponds to FIG.

  In the case of the use request ARP Probe message 430, a value “1” indicating an ARP request is described in the “Opcode” field 401. Further, unlike the ARP Probe message 410 for status confirmation, the “sender IP address” field 403 describes the IP address of the transmission source of the ARP Probe message 430 for use request. In the “target IP address” field 405, an IP address determined to be used by the transmission source of the ARP Probe message 430 of the use request is described.

  In step S3160 of FIG. 4, the autonomous allocation unit 240 determines whether or not the use request ARP Probe message 430 shown in FIG. If it is less than three times (S3160: NO), the autonomous allocation unit 240 returns to step S3150 and outputs the use request ARP Probe message 430 again. When the output count of the use request ARP Probe message 430 is three times or more (S3160: YES), the node 200 determines the IP address of the own device and ends the series of processes.

  In this way, the node 200 that has started the DHCP server operation ends the server initial setting process, and the setting of the address pool and the IP address of the own device is completed.

  The node 200 starts the above-described IP address assignment process when the process of step S3110 is completed in the server initial setting process and the address pool is generated.

  FIG. 10 is a flowchart showing a flow of IP address assignment processing executed in the DHCP server operation state 3000 of FIG. The node 200 that searches for the node 200 that functions as a DHCP server broadcasts a DHCPDISCOVER message as described in the related art.

  In step S3210, when the DHCPDISCOVER message is input from the other node 200 operating as a DHCP client, the communication unit 210 notifies the DHCP server unit 220 of the DHCPDISCOVER message.

  Next, in step S3220, the DHCP server unit 220 selects an IP address 310 to be allocated from the address pool 350 generated in step S3110 of FIG. 4 for the notified DHCPDISCOVER message. However, at this time, the DHCP server unit 220 selects the IP address 310 whose allocation state 351 is “free”. Then, the DHCP server unit 220 rewrites the allocation state 351 of the selected IP address 310 as “reserved” and changes the MAC address included in the DHCPDISCOVER message notified from the communication unit 210 to the corresponding MAC address 352. Describe in the field.

  Next, in step S3230, the overall allocation unit 270 determines whether the own device has already output the use request ARP Probe message 430, that is, whether the address pool of the own device has been determined. Specifically, the overall allocation unit 270 monitors the state of the autonomous allocation unit 240 and determines whether or not the IP address allocation process executed by the own apparatus has already reached the process of S3150 in FIG. . If the autonomous allocation unit 240 has not yet output the use request ARP Probe message 430 (S3230: NO), the process proceeds to step S3240.

  In step S3240, the overall allocation unit 270 causes the DHCP server unit 220 to set a temporary setting flag indicating that the setting of the IP address 310 performed in step S3220 is temporary in the DHCPOFFER message. The DHCPOFFER message is a signal for storing the IP address 310 selected in step S3220 and presenting the IP address 310 as a response to the DHCPDISCOVER message.

  The temporary setting flag is set in the DHCPOFFER message because the IP address assignment processing may return to step S3110 in FIG. 4 to change the address pool and present another IP address. That is, the temporary setting flag is for notifying the receiving side of the DHCPOFFER message that the IP address to be assigned is temporary. As the temporary setting flag, for example, a DHCP flag field or an IP option field may be used.

  Next, in step S3250, the DHCP server unit 220 broadcasts a DHCPOFFER message via the communication unit 210.

  On the other hand, if the ARP Probe message 430 requesting use has already been output from the own apparatus (S3230: YES), the IP address assignment processing does not return to step S3110 in FIG. Accordingly, since the address pool 350 has been determined, the DHCP server unit 220 proceeds to step S3250 without setting the temporary setting flag, and outputs a DHCPOFFER message.

  In step S3260, the DHCP server unit 220 monitors the reception of the DHCPREQUEST message by the communication unit 210 as a response to the DHCPOFFER message output in step S3250. The DHCPREQUEST message is a signal for requesting that the node 200 that has received the DHCPOFFER message uses the IP address provided by the DHCPOFFER message. The DHCPREQUEST message includes a selected server IP address that is the IP address of the node 200 selected as the request destination. In this case, the IP address of the own device is designated as the selected server IP address, and the IP address assignment state 351 that is requested to be used is “reserved”.

  If the corresponding DHCPREQUEST message arrives at the own device before the timeout occurs (S3260: YES), the DHCP server unit 220 proceeds to step S3270. On the other hand, when the corresponding DHCPREQUEST message times out without arriving at the own apparatus (S3260: NO), the process proceeds to step S3280.

  In step S3270, the DHCP server unit 220 rewrites the allocation state 351 corresponding to the IP address 310 requested to be used by the DHCPREQUEST message in the address pool 350 from “reserved” to “in use”.

  Next, in step S3290, the overall allocation unit 270 determines again whether or not the own device has already output the use request ARP Probe message 430. If the autonomous allocation unit 240 has not yet output the use request ARP Probe message 430 (S3290: NO), the process proceeds to step S3300.

  In step S3300, the overall allocation unit 270 causes the DHCP server unit 220 to set the temporary setting flag this time in the DHCPACK message. The DHCPACK message is a signal for notifying the surrounding nodes 200 that the assignment of the IP address 310 is successful, and stores the IP address 310 to be assigned.

  In step S <b> 3310, the DHCP server unit 220 broadcasts a DHCPACK message via the communication unit 210.

  In step S3320, the DHCP server unit 220 determines whether to end the DHCP server operation of the own device. If the DHCP server operation is to be continued (S3320: NO), the process returns to step S3210 again to monitor the input of a new DHCPDISCOVER message from the other node 200 operating as a client. When the DHCP server operation is terminated due to an instruction to stop wireless communication by a user operation (S3320: YES), a series of processes is terminated.

  On the other hand, in step S3280, although the DHCPOFFER message is output, the corresponding DHCPREQUEST message does not arrive, so the DHCP server unit 220 sets the release of the IP address 310 presented to the node 200. That is, the DHCP server unit 220 rewrites the allocation state 351 of the IP address 310 selected in step S3220 in the address pool 350 from “reserved” to “free”. Then, the process proceeds to step S3320.

  If the ARP Probe message 430 requesting use has already been output from the own device at the stage where step S3270 is completed (S3290: YES), the address pool 350 has been determined, so the provisional setting flag is set. Without proceeding to step S3310, and a DHCPACK message is output.

  In this way, when the node 200 is in the DHCP server operation state, the node 200 performs address assignment in response to a request from another node 200 operating as a client. If the address pool has not yet been determined at the stage of the address assignment, it is notified that the address assignment is temporary. Therefore, the address receiving side starts the initial setting for operating as a DHCP client and starts IP communication at an early stage where the node 200 that has started the DHCP server operation has not completed the initial setting. Can do. The overall allocation unit 270 may omit the processes in steps S3230, S3240, S3290, and S3300 when the address pool of the own device is determined.

  FIG. 11 is a flowchart showing the flow of client initial setting processing executed in the DHCP client operation state 2000 of FIG.

  In step S2110, the overall allocation unit 270 causes the DHCP address acquisition unit 250 to generate a DHCPDISCOVER message, broadcasts it via the communication unit 210, and searches for a DHCP server.

  In step S2120, the overall allocation unit 270 monitors for a predetermined time that the DHCPOFFER message is received by the communication unit 210 as a response to the DHCPDISCOVER message in step S2110. This DHCPOFFER message is output in step S3250 of FIG. 10 when the other node 200 operating as the DHCP server performs the IP address assignment process shown in FIG. That is, when the DHCPOFFER message arrives at its own device, another node 200 functioning as a DHCP server exists within the communicable range.

  If the DHCPOFFER message has arrived at its own device (FIG. 11, S2120: YES), the overall allocation unit 270 passes the DHCPOFFER message to the DHCP address acquisition unit 250, and proceeds to step S2130. Then, the overall allocation unit 270 continues the DHCP client operation state of its own device. At this time, if there are a plurality of other nodes 200 functioning as a DHCP server within the communicable range, a plurality of DHCPOFFER messages arrive.

  On the other hand, if the corresponding DHCPOFFER message has timed out without arriving (S2120: NO), the process proceeds to step S3100. Then, the overall allocation unit 270 transitions its own apparatus to the DHCP server operation state 3000 in FIG. 3 on the assumption that there is no other node 200 functioning as a DHCP server within the communicable range. Then, the node 200 executes the server initial setting process and the IP address assignment process described with reference to FIGS.

  In step S2130, the DHCP address acquisition unit 250 acquires the presented IP address 310 from each input DHCPOFFER message, and determines whether or not a temporary setting flag is set in each DHCPOFFER message. This temporary setting flag is set by the other node 200 operating as the DHCP server in step S3240 in FIG. That is, whether or not the IP address presented in the DHCPOFFER message is likely to be changed later can be determined based on whether or not the temporary setting flag is set.

  For the DHCPOFFER message in which the temporary setting flag is set (S2130: YES), the process proceeds to step S2140. For a DHCPOFFER message in which the temporary setting flag is not set (S2130: NO), the process proceeds to step S2150 after step S2140 without passing through step S2140.

  In step S2140, the DHCP address acquisition unit 250 internally sets a temporary setting flag for the corresponding IP address.

  In step S2150, the DHCP address acquisition unit 250 selects an IP address that is requested to be used by the own device from among the IP addresses presented by the DHCPOFFER message. At this time, when there is an IP address for which the temporary setting flag is not set, the DHCP address acquisition unit 250 selects the IP address for which the temporary setting flag is not set. Further, when there are a plurality of presented IP addresses, the DHCP address acquiring unit 250 preferentially selects the IP address presented from the other party of the DHCPOFFER message presented first, for example.

  Next, in step S <b> 2160, the DHCP address acquisition unit 250 generates a DHCPREQUEST message and broadcasts it via the overall allocation unit 270 and the communication unit 210. At this time, the DHCP address acquisition unit 250 specifies the IP address selected in step S2150 as the request IP address in the DHCPREQUEST message, and also specifies the IP address of the node 200 that presented the IP address as the selected server IP address. To do.

  Next, in step S2170, the DHCP address acquisition unit 250 receives a DHCPACK message as a response to the DHCPREQUEST message sent in step S2160. This DHCPACK message is output in step S3310 of FIG. 10 by another node 200 operating as a DHCP server.

  Next, in step S2180, the DHCP address acquisition unit 250 determines whether or not a temporary setting flag is set in the input DHCPACK message. This temporary setting flag is set by the other node 200 operating as the DHCP server in step S3300 in FIG. That is, when the temporary setting flag is set, it can be seen that the IP address assigned by the DHCPACK message may be changed later. If the temporary setting flag is set (S2180: YES), the process proceeds to step S2190. If the temporary setting flag is not set (S2180: NO), the process proceeds to step S2200 after step S2190 without passing through step S2190.

  In step S2190, the DHCP address acquisition unit 250 internally sets a temporary setting flag for the corresponding IP address, similarly to step S2140. However, if the temporary setting flag is already set at the corresponding IP address, it is left as it is.

  In step S2200, the DHCP address acquisition unit 250 sets the IP address selected in step S2150 and assigned to the own device in step S2170 to the communication unit 210 via the overall allocation unit 270. Corresponding to the setting of the IP address, the communication unit 210 acquires various information that can be acquired by DHCP, such as a netmask, a default gateway address, and a DNS (domain name system) server address, and sets them in its own apparatus. Then, a series of processing ends.

  In this way, the node 200 becomes a state capable of IP communication as a DHCP client. In addition, since the presence / absence of temporary setting is checked in two steps of step S2130 and step S2180, when there is an IP address that is not temporarily set among a plurality of IP addresses presented from a plurality of servers, This can be selected.

  However, when the IP address assigned to the own device is provisionally set, the IP address may not only be changed, but may be set redundantly with other nodes 200.

  Therefore, the application communication unit 290 monitors whether or not the temporary setting flag is set in the DHCP address acquisition unit 250, and notifies the application unit 280 when the temporary setting flag is set. Upon receiving this notification, the application unit 280 refrains from transmitting important information to limit communication performed by the application unit 280, or cause the application communication unit 290 to restrict reception by the communication unit 210. Let control take place.

  On the other hand, when the DHCP server determines the address pool, the IP address assigned to the own device is also determined. At this time, the communication restriction described above should be released promptly. Therefore, the node 200 operating as a DHCP client cancels the temporary setting designation to start normal IP communication by appropriately canceling the temporary setting designation at the time when the IP address is presented by the DHCPOFFER message in step S2120 of FIG. Judgment processing is started.

  FIG. 12 is a flowchart showing the flow of temporary setting release determination processing executed in the DHCP client operation state 2000 of FIG.

  In step S2310, the communication unit 210 inputs an IP packet transmitted from the other node 200 to the own device.

  In step S2320, the overall allocation unit 270 determines whether or not the transmission source of the received IP packet is a DHCP server. Specifically, the overall allocation unit 270 extracts a value described in the node designation unit 303 from the destination IP address 310 of the IP packet, and determines whether or not the extracted value is “1”. If the source of the IP packet is a DHCP server (S2320: YES), the process proceeds to step S2330.

  In step S2330, the overall assignment unit 270 determines whether or not a temporary setting flag is set for the IP address 310 assigned to the own device. If the temporary setting flag is set (S2330: YES), the process proceeds to step S2340. If the temporary setting flag is not set (S2330: NO), it is not necessary to determine whether to cancel the temporary setting, and thus the process ends.

  In step S2340, the overall allocation unit 270 determines whether or not a temporary setting flag is set in the received IP packet. In the present embodiment, as described above, it can be set in the DHCPOFFER message and the DHCPACK message. If the temporary setting flag is not set (S2340: NO), the process proceeds to step S2350.

  In step S2350, the PAN designation determination unit 260 extracts the value described in the PAN designation unit 302 of the source IP address 310 of the received IP packet. Then, the PAN designation determination unit 260 obtains the value extracted from the received IP packet and the value described in the PAN designation unit 302 of the IP address 310 acquired by the DHCP address acquisition unit 250 through DHCP in step S2200 of FIG. Compare. If these values match (S2350: YES), the process proceeds to step S2360.

  In step S2360, the PAN designation determination unit 260 operates as a DHCP server, and determines that the other node 200 that has presented the IP address to its own device has confirmed the address pool and started IP communication. 250, the corresponding temporary setting flag is deleted. Then, a series of processing ends.

  Further, when the source of the received IP packet is not a DHCP server (S2320: NO), when the temporary setting flag is set in the received IP packet (S2340: YES), and the source of the received IP packet If the value of the PAN specifying unit 302 differs between the address and the IP address 310 acquired by the own device (S2350: NO), the process returns to step S2310.

  In this way, when the node 200 operates as a DHCP client, even if the IP address assigned from the other node 200 operating as the DHCP server is provisionally set, the node 200 sends an IP packet addressed to itself from the other node 200. This temporary setting can be canceled promptly when received.

  For example, after receiving a DHCPOFFER message with a provisional setting flag set from a certain node 200 and receiving a DHCPACK message without a provisional setting flag, the provisional setting designation is canceled when the DHCPACK message is received. It will be.

  For example, after the DHCPACK message, there is a case where no packet is sent from the node 200 functioning as the DHCP server. Therefore, in such a case, it is desirable to perform an abnormal process of actively inquiring whether or not the temporary setting of the IP address can be canceled and retrying acquisition of the IP address as appropriate. As this abnormal processing, for example, when a predetermined time elapses without canceling the temporary setting and a timeout occurs, an ARP request for inquiring about the IP address of the own device is output, and an ARP response is not received. When the time-out occurs, the initial setting of the IP address is assumed to be continued, and the client initial setting process may be executed again.

  Further, in order to avoid such a situation, the overall allocation unit 270, when the own device operates as a DHCP server, with respect to the other node 200 that has performed address assignment when the address pool of the own device is determined. Thus, a packet in which the temporary setting flag is not set may be sent.

  Furthermore, in this embodiment, the PAN designation determination unit 260 is used when determining temporary setting deletion, but there is a possibility that the IP address of the own device overlaps with another device that has moved into the wireless PAN 100 area. It can also be used for determination.

  Hereinafter, the operation of each node 200 and the state of signals will be described using a specific example of the activation timing of each node 200 in the wireless PAN 100 shown in FIG.

  FIG. 13 is a sequence diagram illustrating an example of operations and signal states of each node 200 when each node 200 of the wireless PAN 100 illustrated in FIG. 1 performs initial setting. Here, the first node 200-1 is powered on first, and the second node 200-2 is powered on at the stage where the initial setting of the first node 200-1 is not completed immediately thereafter. An example of the case is illustrated.

In step S5100, the time _{t 0,} the first node 200-1 is turned power-on (ON) state, the second node 200-2 remained power-off (OFF) state.

In step S5200, the first node 200-1, immediately after time _{t 0,} broadcasts outputs a DHCPDISCOVER message (step S2110 in FIG. 11). However, at this time, since the second node 200-2 is in the OFF state, no response is returned to the first node 200-1 (step S2120 in FIG. 11: NO).

  In step S5300, the first node 200-1 enters the DHCP server operating state (step S3100 in FIG. 11).

  In step S5400, it is assumed that the second node 200-2 is turned on immediately after the first node 200-1 enters the DHCP server operation state in step S5300.

  In step S5500, the second node 200-2 broadcasts a DHCPDISCOVER message (step S2110 in FIG. 11).

  In step S5600, since the first node 200-1 has already started the server initial setting process and the IP address assignment process, the assignment is performed in response to the input of the DHCPDISCOVER message from the second node 200-2. Is selected (step S3220 in FIG. 10). Then, the first node 200-1 transmits a DHCPOFFER message (step S3250 in FIG. 10).

  Here, the first node 200-1 generates the address pool 350 shown in FIG. 6, sets “192.168.1.1” as the temporary server address of the own device, and the IP of the second node 200-2. It is assumed that “192.168.1.2” is selected as the address.

  Further, at this time, it is assumed that the server initial setting process of the first node 200-1 has not reached Step S3120 in FIG. 4 (Step S3230 in FIG. 10: NO). In this case, as described above, the first node 200-1 sets a temporary setting flag in the DHCPOFFER message to be transmitted (step S3240 in FIG. 10). Therefore, the IP address “192.168.1.2” in which the temporary setting flag is set is provided to the second node 200-2 (step S2140 in FIG. 11).

  In step S5700, the first node 200-1 continues the server initial setting process, and outputs a status confirmation ARP Probe message 410 (step S3120 in FIG. 4). However, since the second node 200-2 has not decided to use the provided IP address at this time, no response is returned to the first node 200-1. Even if the second node 200-2 has already decided to use the provided IP address, since it is an IP address different from that of the first node 200-1, no response is returned. .

  In step S5800, the second node 200-2 continues the client initial setting process and outputs a DHCPREQUEST message (step S2160 in FIG. 11).

  In step S5900, the first node 200-1 outputs a DHCPACK message as a response to the DHCPREQUEST message in step S5800 (step S3310 in FIG. 10). As a result, the second node 200-2 is assigned the IP address “192.168.1.2” and is ready for IP communication.

  At this time, it is assumed that the first node 200-1 has output the status confirmation ARP Probe message 410 only once in the server initial setting process shown in FIG. 4 (step S3230 in FIG. 10: NO). . In this case, as described above, the first node 200-1 sets a temporary setting flag in the DHCPACK message to be transmitted (step S3300 in FIG. 10). Therefore, the temporary setting flag remains set for the IP address of the second node 200-2 (step S2190 in FIG. 11).

  In step S6000, the first node 200-1 continues the server initial setting process and outputs the status confirmation ARP Probe message 410 two more times (step S3120 in FIG. 4). However, since an IP address different from that of the first node 200-1 is assigned to the second node 200-2, no response is returned to the first node 200-1 (step S3140 in FIG. 4: YES).

  In step S6100, the first node 200-1 outputs an ARP Probe message 430 requesting use (step S3140 in FIG. 4), and finally ends the server initial setting process. Also, the second node 200-2 ends the client initial setting process before the temporary setting flag is set in the IP address.

As a result, at time t ₁ after the server initial setting process of the first node 200-1 and the client initial setting process of the second node 200-2 are completed, the first node 200-1 is the DHCP server. The second node 200-2 operates as a DHCP client.

  In the prior art, in order to perform normal communication, one of the nodes must be in the DHCP server operating state and then the other node must be turned on. In the node 200 of the present embodiment, the first node Before the node 200-1 enters the DHCP server operating state, the second node 200-2 is turned on. In other words, in this embodiment, even if the power is continuously turned on to a plurality of nodes 200, each node 200 can appropriately select the server function and the client function, and can communicate normally. I understand. In addition, before the node 200 operating as a DHCP server determines an address pool, the node 200 operating as a DHCP client can acquire an IP address and start IP communication. That is, the node 200 that is powered on for the second time and thereafter can start IP communication immediately after the power is turned on.

  As described above, according to the present embodiment, the node transitions to the DHCP server operating state when there is no other node operating as a DHCP server that assigns an IP address within the communication range. Then, in parallel with the initial setting process for operating as a DHCP server, the node executes a process of assigning addresses in response to a request from another node operating as a DHCP client. As a result, the node 200 to which power is first turned on can assign an IP address to another node operating as a DHCP client even if the function as a server is not completely started. That is, even if the power is turned on in succession for a plurality of nodes, the server function and the client function can be appropriately selected in each node, and the start-up of the entire wireless PAN can be speeded up.

  However, the node that has transitioned to the DHCP server operating state has an address before determining that the same address as the IP address assigned to the own device has not already been assigned to another node, that is, before determining the address pool of the own device. When the allocation is performed, the allocation destination is notified that the address allocation is temporary. That is, the node that has transitioned to the DHCP server operating state notifies the allocation destination that the IP address allocated by the node may be changed. As a result, the address receiving side can know that the assigned IP address is duplicated with another node 200 or may be changed, and prohibits transmission of highly important information. As such, appropriate restrictions can be added to the communication.

  Further, the IP address is divided into a network address, a PAN designation unit, and a node designation unit, and an address pool is generated for each node 200 by using the network address and the PAN designation unit in common. Thus, by setting a different PAN specifying unit for each DHCP server, it is possible to easily prevent duplication of the IP address of the address pool between the DHCP servers.

  Furthermore, in principle, the DHCP server and the surrounding devices check the IP address by comparing the PAN designation part using the common network address and PAN designation part. Accordingly, it is possible to more easily determine whether or not there is duplication of IP addresses or address pools between DHCP servers, and the IP address check process can be speeded up.

  In some cases, the same IP address is assigned to a plurality of nodes that have started up in an environment where they cannot perform wireless communication with each other, and wireless communication can be performed later by moving the nodes. Conceivable. In this case, as in step S2350 in FIG. 12, the DHCP server compares the PAN specifying unit of the IP address of the own device with the PAN specifying unit of the IP address of the transmission source of the received data. The existence of a DHCP server having the same address pool can be investigated. Specifically, when data is received from a node having a MAC address that is not registered in its own address pool, the PAN specification part of the IP address of the transmission source matches the PAN specification part of the IP address of its own device In this case, it can be determined that there is a DHCP server having the same address pool as the own device. In this case, the server initial setting process shown in FIG. 4 may be executed again.

  In the embodiment described above, the example in which the present invention is applied to a television and a hard disk recorder has been described. However, the present invention is applied to various other electronic devices such as a fixed phone, a mobile phone, a video deck, a speaker, and a game device. Of course, it can be applied. In particular, for example, in electronic devices that may perform important communication including personal information such as cash settlement, transmission of important information can be suppressed during temporary setting. In addition, during temporary settings, transmission of important information is suppressed, while communications that allow some interruption or information leakage due to IP address changes, such as web access and streaming, are performed as usual. It is possible to properly use whether or not communication is possible. That is, it is possible to achieve both high speed of PAN rise and ensuring safety.

  The communication device and the communication method according to the present invention can switch the server function and the client function according to the surrounding situation, and can further improve usability, such as a fixed telephone, a mobile phone, a television, a video deck, It is useful for various other electronic devices such as a hard disk recorder, a speaker, and a game device.

The system block diagram which shows the structure of the wireless PAN which has arrange | positioned the communication apparatus which concerns on one embodiment of this invention The block diagram which shows the structure of the communication apparatus which concerns on this Embodiment The flowchart which shows the transition of the operation state of the communication apparatus which concerns on this Embodiment The flowchart which shows the flow of the server initial setting process in the communication apparatus which concerns on this Embodiment. Explanatory drawing showing an example of an IP address system and an example of an IP address in a wireless PAN in which a communication apparatus according to the present embodiment is arranged Explanatory drawing which shows an example of a structure of the address pool which the communication apparatus which concerns on this Embodiment produces | generates Explanatory drawing which shows the structure of the ARP Probe message for status confirmation according to the present embodiment Explanatory drawing which shows the structure of the ARP response of the situation confirmation which concerns on this Embodiment Explanatory drawing which shows the structure of the ARP Probe message of the use request which concerns on this Embodiment The flowchart which shows the flow of the IP address allocation process in the communication apparatus which concerns on this Embodiment The flowchart which shows the flow of the client initial setting process in the communication apparatus which concerns on this Embodiment The flowchart which shows the flow of the temporary setting cancellation | release determination processing in the communication apparatus which concerns on this Embodiment Sequence diagram showing an example of the operation of each communication device and the state of signals when the communication device according to the present embodiment performs initial setting System configuration diagram showing an example of the configuration of a PAN using a conventional communication device Block diagram showing the configuration of a conventional communication device The flowchart which shows the flow of the operation | movement of the initial setting in PAN using the conventional communication apparatus. Sequence diagram showing an example of operation and signal behavior of each communication device when a conventional communication device performs initial setting

Explanation of symbols

100 wireless PAN
200 nodes 210 communication unit 220 DHCP server unit 230 DHCP server initial setting unit 240 autonomous allocation unit 250 DHCP address acquisition unit 260 PAN designation determination unit 270 overall allocation unit 280 application unit 290 application communication unit 300 wireless communication path

Claims (5)

When a node that assigns an IP address to another node exists in the communicable range, a client operation unit that requests the node to assign an IP address to the own device;
Server operation that assigns an IP address autonomously to its own device and assigns an IP address to another node based on the IP address when a node that assigns an IP address to another node does not exist within the communicable range And
An assignment determination unit for determining whether the same address as the IP address assigned to the own device by the server operation unit is already assigned to another node;
Before the allocation determining unit determines that the same address as the IP address allocated to the device by the server operating unit is not already allocated to the other node, the server operating unit sets the IP address to the other node. A temporary setting notification unit that notifies the allocation destination that the allocation of the IP address is provisional when performing the allocation;
A communication device. The server operating unit is
Assigning an IP address to the other node by sending a predetermined message storing the IP address to be assigned to the other node;
The temporary setting notification unit
By setting a temporary setting flag in the predetermined message, it is notified that the IP address assignment by the predetermined message is temporary.
The communication apparatus according to claim 1. A communication unit that performs IP communication using an IP address assigned to the own device;
A communication restriction unit that restricts IP communication by the communication unit when notified that the assignment of the IP address to the own device is temporary;
The communication device according to claim 1, further comprising: When the allocation determining unit determines that the same address as the IP address allocated to the own device by the server operating unit has not already been allocated to another node, the allocation to the IP address allocation destination by the server operating unit A setting confirmation notifying unit for notifying the confirmation of the assignment of the IP address;
When the communication unit is notified of the assignment of the IP address to the own device in a state in which the IP communication is restricted, a restriction release unit for releasing the restriction of the IP communication by the communication restriction unit;
The communication device according to claim 3, further comprising: A server presence / absence determining step for determining whether or not a node to which an IP address is assigned to another node exists within a communicable range;
When it is determined that a node that assigns an IP address to another node does not exist within the communicable range, the node that autonomously assigns an IP address to its own device and assigns an IP address to the other node is in a communicable range An address acquisition step for requesting the node to assign an IP address to the own device when it is determined that
When an IP address is autonomously assigned to the own device, a process of assigning an IP address to another node based on the IP address is started, and the same address as the IP address assigned to the own device is assigned to the other node. A process start step for starting a process for determining whether or not the process has already been assigned,
When assigning an IP address to another node before determining that the same address as the IP address assigned to the own device has not already been assigned to the other node, A temporary setting notification step for notifying that the assignment is temporary;
A communication method.

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