JP2014110603A - Communication device, control method for communication device, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device capable of more surely communicating with a partner device by appropriately managing correspondence of addresses.SOLUTION: A communication device allocates an IP address to another communication device and performs first storage by associating the IP address with identification information on the other communication device; and acquires a physical address to be a destination for communicating with the other communication device and performs second storage by associating the acquired physical address with the IP address. When receiving a release request for requiring allocation release of the IP address from the other communication device, the communication device updates the first storage before updating the second storage so as to correspond to the update of the first storage.

Description

  The present invention relates to a communication device, a communication device control method, and a program.

  In recent years, a case where a wireless LAN station function is installed in a device such as a digital camera and a wireless LAN access point is connected and used is increasing. For example, Patent Document 1 discloses a method for easily sharing an image by mounting a wireless LAN station function on a digital camera, uploading an image captured by the digital camera to a network via an access point.

  In addition, in order to enable devices such as digital cameras and printers to directly communicate with each other via a wireless LAN without using an access point, the functions of the access point are often built in these devices. When these devices are equipped with a wireless LAN access point function, a DHCP server function is often installed together in order to assign an IP address to each device.

  A digital camera as a DHCP server performs search processing to search for a communication partner device after assigning an IP address to a DHCP client. For example, a communication partner device is searched using a search protocol such as mDNS (Multicast DNS) or SSDP (Simple Service Discovery Protocol). When the IP address of the communication partner is acquired by the search process, ARP specifying the IP address is executed to acquire the MAC address. Thereafter, communication with the communication partner is started using the IP address and the MAC address acquired by ARP. Here, the digital camera as the DHCP server stores the correspondence between the IP address assigned to the device and the MAC address of the device in the DHCP table. The correspondence between the IP address obtained by ARP and the MAC address is also stored in the ARP table.

JP 2011-35768 A

  The IP address assigned by the DHCP server is released after a predetermined period. The correspondence between each IP address and MAC address stored in the ARP table is deleted from the table when the update time determined for each IP address is reached.

  However, in the prior art, the DHCP table and the ARP table are not synchronized with each update. Therefore, there is a possibility that the correspondence between the IP address and the MAC address is inconsistent between the DHCP table and the ARP table. For example, the IP address of a device may remain associated in the ARP table even though the IP address assignment to the device having a certain MAC address is canceled by the DHCP server. Therefore, in the prior art, when a device with a certain IP address is retrieved as a result of searching for a communication partner device, an attempt is made to communicate using the MAC address associated with the IP address based on the stored ARP table. There was also a case that could not communicate.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a communication device that can appropriately manage the correspondence of addresses and can more reliably communicate with a counterpart device.

  In order to achieve the above object, a communication apparatus according to the present invention includes an assigning unit that assigns an IP address to another communication apparatus, and stores the assigned IP address and the identification information of the other communication apparatus in association with each other. A second storage for storing the allocated IP address and the acquired physical address in association with each other; and a storage unit for acquiring a physical address serving as a destination for communicating with the other communication device; Means, receiving means for receiving a release request for requesting release of the IP address assignment from the other communication device, and storing the first storage means in response to the release request received by the receiving means And updating means for updating the contents and updating the storage contents of the second storage means so as to correspond to the update.

  ADVANTAGE OF THE INVENTION According to this invention, the communication apparatus which can manage the correspondence of an address appropriately and can communicate more reliably with the other party apparatus can be provided.

Hardware block diagram of the communication apparatus of the present embodiment Software block diagram of the communication apparatus of this embodiment Network configuration diagram of this embodiment The flowchart which shows operation | movement of the communication apparatus of a present Example. Explanatory drawing of DHCP table and ARP table Sequence diagram showing communication between conventional communication devices The flowchart which shows operation | movement of the communication apparatus of a present Example. Sequence diagram showing communication between communication devices of the present embodiment Flowchart showing the operation of the communication device in the second embodiment.

[Example 1]
Hereinafter, the communication apparatus according to the present embodiment will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating an example of a hardware configuration of a communication apparatus 101 according to an embodiment to which the present invention can be applied. The control unit 102 controls the entire communication apparatus by executing a control program stored in the storage unit 103. The control unit 102 is configured by a processor such as a CPU or MPU. The control unit 102 also controls the setting of communication parameters with other devices. The storage unit 103 stores various control programs executed by the control unit 102 and information such as communication parameters. Further, the storage unit 103 may store image data, a file, or the like generated by a communication device or received from an external device. The storage unit 103 includes various memories such as a ROM, a RAM, an HDD, and a flash memory. Note that various operations of the communication apparatus 101 shown in the flowcharts and sequence diagrams described below are performed by the control unit 102 executing a control program stored in the storage unit 103.

  The wireless unit 104 performs wireless LAN communication conforming to the IEEE802.11 series. The display unit 105 has a function capable of outputting visually recognizable information such as an LCD or LED, or outputting sound such as a speaker. The display unit 105 only needs to have a function of outputting at least one of visual information and sound information. The antenna control unit 107 controls the antenna 108 and transmits a signal by wireless communication. The input unit 109 includes buttons, a touch panel, and the like for the user to perform various inputs. Note that the communication apparatus 101 may have a hardware configuration other than the hardware configuration shown in FIG. For example, when the communication device 101 is a digital camera, an imaging unit is provided, and when the communication device 101 is a printer, a printing unit is provided.

  FIG. 2 is a block diagram illustrating an example of the software configuration 201 of the communication apparatus according to the present embodiment. Each software shown in FIG. 2 is stored in the storage unit 103 in FIG. 1 and is executed by the control unit 102 as appropriate. The mDNS control unit 202 is software for executing Multicast DNS for searching for a host name of a communication partner apparatus. The UPnP control unit 203 is software for executing SSDP (Simple Service Discovery Protocol) for searching for a desired service. These are all software for searching for a device that is a communication partner of the communication device, but may include other software for searching for a device. The DHCP client control unit 204 is software for causing the communication device to operate as a DHCP (Dynamic Host Configuration Protocol) client. On the other hand, the DHCP server control unit 205 is software for operating the communication apparatus as a DHCP server. The communication apparatus according to the present embodiment operates as a DHCP client or a DHCP server according to its own role set by a user in advance or automatically determined by negotiation with another communication apparatus. Determine what works as. When the communication apparatus operates as a DHCP server, the DHCP server control unit 205 assigns an IP address to another apparatus according to the DHCP protocol. Then, the assigned IP address and the MAC address as identification information of the other device are associated with each other and registered in the DHCP table. The DHCP table will be described later. The AutoIP control unit 206 performs a process of automatically determining the IP address of the communication device itself from an IP address within a predetermined range when there is no DHCP server. The ARP table control unit 207 executes ARP (Address Resolution Protocol) specifying an IP address. ARP is an address resolution protocol, and is used to acquire the MAC address of a device that should receive a packet next, using a destination IP address as a key. When there is a relay device between the device with the destination IP address, the MAC address of the relay device is acquired by ARP. The ARP table control unit 207 manages the MAC address acquired by ARP and the IP address specified by ARP as an ARP table in association with each other. The DHCP table and the ARP table are stored in the storage unit 103 in FIG. The MAC address is an example of a physical address set in the communication device. The DHCP server control unit 205 and the ARP table control unit 207 are examples of a first storage unit and a second storage unit, respectively.

  The wireless LAN packet receiving unit 208 receives a wireless LAN packet via the antenna 108, the antenna control unit 107, and the wireless unit 104 of FIG. The wireless LAN packet transmission unit 209 transmits a wireless LAN packet via the wireless unit 104, the antenna control unit 107, and the antenna 108 of FIG.

  The wireless LAN station function control unit 210 performs various operations such as authentication / encryption processing when the communication apparatus operates as a wireless LAN station. The wireless LAN access point function control unit 211 executes various operations such as authentication / encryption processing when the communication apparatus operates as a wireless LAN access point. The communication apparatus according to the present embodiment operates as a wireless LAN access point according to its own role set in advance by a user or according to its own role automatically determined by negotiation with another communication apparatus. Or act as a station. The packet routing control unit 212 routes communication packets when the wireless LAN access point function control unit 211 is operating.

  These software are examples, and other software blocks may be provided. Also, a plurality of software blocks may constitute one software block, or any one of the software blocks may be further divided into software blocks that perform a plurality of functions.

  FIG. 3 is a diagram showing a system configuration in the present embodiment. The example of FIG. 3 shows a wireless LAN network 31 compliant with IEEE 802.11. In the example of FIG. 3, the wireless LAN network 31 is configured by three communication devices 32, 33, and 34, and each of these communication devices has the configuration of FIGS. 1 and 2. The communication device 32 in FIG. 3 operates as an access point in the wireless LAN network 31 by the wireless LAN access point function control unit 211. On the other hand, the communication device 33 and the communication device 34 operate as stations in the wireless LAN network 31 by the wireless LAN station function control unit 210. In the present embodiment, it is assumed that the communication device 32 operating as an access point is a digital camera, and the communication devices 33 and 34 operating as stations are printers. Hereinafter, the communication device 32 is referred to as a digital camera, and the communication devices 33 and 34 are referred to as a printer A and a printer B, respectively.

  FIG. 4 is a flowchart illustrating processing executed in the digital camera when the digital camera and the printer perform communication by wireless LAN. In the following description, the case where the digital camera communicates with the printer A in FIG. 3 will be described, but the same applies to the case where the digital camera communicates with the printer B. Each step in FIG. 4 is processed by the control unit 102 executing each program (for example, each software module shown in FIG. 2) stored in the storage unit 103 in FIG. 1 in the digital camera.

  In step S <b> 401, the wireless LAN access point function control unit 211 of the digital camera forms the wireless LAN network 31. Specifically, the digital camera periodically transmits a beacon including an SSID indicating the formed wireless LAN network 31 and responds to a wireless LAN network inquiry signal (Probe Request) transmitted from the station. In step S <b> 402, the wireless LAN access point function control unit 211 of the digital camera performs predetermined authentication processing conforming to IEEE 802.11 and establishes a connection with the printer A through the wireless LAN. In step S <b> 403, the DHCP server control unit 205 of the digital camera assigns an IP address to the printer A. In step S404, the DHCP server control unit 205 of the digital camera associates the MAC address of the printer A with the IP address assigned in step S403, and registers them in the DHCP table.

  Thereafter, when the digital camera actually receives a service such as print processing using the printer, the digital camera searches for a printer existing in the wireless LAN network 31. For the printer search, for example, SSDP is used.

  In step S405, the UPnP control unit 203 of the digital camera executes SSDP and searches for a printer. Specifically, a search packet called M-SEARCH is transmitted by multicast and waits for a response from the printer. Since the response to M-SEARCH includes the IP address of printer A, the digital camera obtains the IP address of printer A as a result of the search in S405. In S406, the digital camera refers to the ARP table stored in itself, and determines whether or not the IP address acquired in S405 is registered in the ARP table. If it is determined that it is registered in the ARP table, the process advances to step S407, and the wireless LAN packet transmission unit 209 of the digital camera transmits data to be transmitted, such as image data, to the printer A. On the other hand, if it is determined that the acquired IP address is not registered in the ARP table, the process proceeds to S408. In step S <b> 408, the digital camera transmits an ARP request packet with the IP address of the printer A as a transmission destination. In step S <b> 409, the digital camera receives the ARP response packet and acquires a MAC address that is a destination when data is transmitted to the printer A. In step S410, the ARP table control unit 207 of the digital camera associates the IP address of the printer A with the MAC address acquired in step S409 and registers them in the ARP table stored in itself. Thereafter, the process proceeds to S407, and the digital camera transmits data to the printer A.

  Next, the aforementioned DHCP table and ARP table will be described with reference to FIG.

  The DHCP table is a table for managing an IP address, a MAC address of a communication apparatus to which the IP address is assigned, and a lease time thereof. The lease time indicates a period during which the assignment of the IP address and the MAC address is valid. In the example of FIG. 5A, an IP address of 192.168.0.1 is assigned to a communication device with a MAC address of 00: bb: cc: dd: ee: ff, and its valid period is 36000 seconds. It is shown that. Further, 192.168.0.2, which is an IP address that can be assigned by this DHCP server, indicates that it is not currently assigned to any communication device.

  Next, the ARP table will be described. In a TCP / IP network, in order for a communication device to communicate with a partner device, not only an IP address but also a MAC address must be designated as a destination address. Therefore, the communication device holds a table indicating the correspondence relationship between the IP address and the MAC address, and clears a record related to the partner device in the table when communication with the partner device is interrupted for a predetermined time or longer. This table is an ARP table. In the example of FIG. 5B, two records are registered in the ARP table. The “type” that is one of the items in the ARP table indicates whether the record is dynamic or static. A dynamic record is a record obtained by ARP, and a static record is a record created by user input. Also, “life” as one of the items indicates a period during which the record is registered in the ARP table, and does not indicate an effective period of the correspondence between the IP address and the MAC address indicated by the record. Absent.

  As described above, although the DHCP table and the ARP table are both tables indicating the correspondence between the IP address and the MAC address, they are managed as separate tables. Conventionally, these tables are not synchronized with each other. Therefore, in the DHCP table, there is a situation in which the correspondence between the IP address and the MAC address continues to remain in the ARP table even though the assignment of the IP address and the MAC address has already been released. It was.

  A case where such a situation occurs will be described with reference to the sequence diagram of FIG.

  In the sequence diagram of FIG. 6, the printer A that has established a connection with the digital camera via the wireless LAN network 31 leaves the wireless LAN network 31, and then a new printer B connects with the digital camera via the wireless LAN network 31. Shows the case.

  First, the digital camera and the printer A establish a connection via the wireless LAN network 31 (F601). Thereafter, the digital camera as the DHCP server assigns an IP address to the printer A (F602). It is assumed that, for example, 192.168.0.101 is assigned to the printer A as an IP address by the processing of F602. The DHCP table stored in the digital camera is also updated at this time. However, the ARP table stored in the digital camera is not updated at this time.

  Thereafter, in order to use the printer, the digital camera executes a service search by SSDP (F603). Here, a search packet called M-SEARCH is transmitted by multicast. Although all the devices connected to the wireless LAN network 31 receive the packet transmitted by multicast, only the printer A exists at this time, so only the printer A responds to the search packet (F604).

  From the response by the printer A, the digital camera acquires the IP address of the printer A. Thereafter, in order to communicate with the printer A, information on the MAC address as the transmission destination is necessary. At this time, since the record of the printer A does not exist in the ARP table, the digital camera executes ARP. As a result, the MAC address is acquired. At this time, the IP address 192.168.0.101 and the acquired MAC address are registered in association with each other in the ARP table stored in the digital camera. The digital camera communicates with the printer A using the IP address 192.168.0.101 and the acquired MAC address (F605).

  In the printer A, when predetermined processing such as printing is completed or the power is turned off, the printer A notifies the digital camera of the withdrawal of the service (F606). Specifically, the printer A transmits a Bye packet defined by UPnP. The Bye packet is a signal indicating that the device leaves the UPnP system. Thereafter, the printer A transmits a DHCP RELEASE packet and requests the digital camera, which is a DHCP server, to release the IP address assignment (F607). As a result, the entry of 192.168.0.101 in the DHCP table stored in the digital camera is cleared, and the IP address can be assigned by the next address assignment. Subsequently, the printer A leaves the wireless LAN network 31 (F608). Specifically, a deauth packet or a disassoc packet is transmitted to the digital camera.

  Thereafter, the printer B participates in the wireless LAN network 31. That is, the digital camera and the printer A establish a connection via the wireless LAN network 31 (F609). Then, the digital camera as the DHCP server assigns an IP address to the printer B (F610). By the process of F610, for example, 192.168.0.101 is assigned to the printer B as an IP address. The DHCP table stored in the digital camera is also updated at this time. However, the ARP table stored in the digital camera is not updated at this time. Therefore, in the ARP table, the IP address of 192.168.0.101 remains associated with the MAC address acquired by ARP with the previous printer A.

  Thereafter, the digital camera executes a service search by SSDP in order to use the printer (F611). Here, a search packet called M-SEARCH is transmitted by multicast. Although all devices connected to the wireless LAN network 31 receive a packet transmitted by multicast, only the printer B exists at this time, so only the printer B responds to the search packet (F612).

  From the response by the printer B, the digital camera acquires the IP address of the printer B. The IP address of the printer B is 192.168.0.101 assigned in F610. In order to communicate with the printer B, MAC address information as a transmission destination is necessary. At this point, there is a record with an IP address of 192.168.0.101 in the ARP table. Therefore, the digital camera tries to communicate with the 192.168.0.101 device according to the ARP table without executing the ARP. However, the MAC address associated with 192.168.0.101 in the ARP table is a MAC address for communicating with the printer A, and is not for communicating with the printer B. Accordingly, the digital camera fails to communicate with the printer B (F613).

  As described above, if the correspondence between the IP address and the MAC address continues to remain in the ARP table even though the assignment of the IP address and the MAC address has already been canceled in the DHCP table, normal communication is not performed. It becomes impossible.

  Therefore, when the digital camera of this embodiment receives a DHCP RELEASE packet from a station, or when the station leaves the wireless LAN network, the digital camera executes processing for clearing the record in the ARP table corresponding to the station.

  FIG. 7 is a flowchart illustrating processing executed in the digital camera when communication with a printer is performed via a wireless LAN. In the following description, the case where the digital camera communicates with the printer A in FIG. 3 will be described, but the same applies to the case where the digital camera communicates with the printer B. Each step in FIG. 7 is processed by the control unit 102 executing each program (for example, each software module shown in FIG. 2) stored in the storage unit 103 in FIG. 1 in the digital camera.

  In step S <b> 701, the digital camera determines whether an IP address assignment release request has been received from the printer A. Specifically, it is determined whether a DHCP RELEASE packet is received from printer A. If a DHCP RELEASE packet is received, the process proceeds to S702. If not received, the process proceeds to S706. In step S <b> 702, the DHCP server control unit 205 of the digital camera cancels the association between the IP address assigned to the printer A and the MAC address of the printer A in the DHCP table stored by itself. In step S <b> 703, the ARP table control unit 207 of the digital camera deletes the IP address of the printer A and the MAC address record associated with the IP address from the ARP table stored by itself. In this embodiment, this processing synchronizes the contents stored in the DHCP table and the contents stored in the ARP table, and the IP address that has been unassigned by DHCP does not remain in the ARP table.

  Thereafter, in S704, the digital camera determines whether or not a disconnection notification for disconnecting the wireless LAN connection has been received from the printer A. The disconnection notification is, for example, a deauth packet or dessoc packet conforming to IEEE 802.11. If the digital camera receives the disconnection notification, the process advances to step S705, and the digital camera disconnects the connection between the digital camera and the printer A via the wireless LAN network 31. If the disconnection notification has not been received, the process of this flowchart ends. The trigger for the disconnection process performed in S705 is not limited to the reception of the disconnection notification. In other words, even if the disconnection notification is not received, even when it is determined by wireless communication monitoring (also referred to as aging timer processing) that the printer A has left the wireless LAN network 31, the process of S705 is performed. Also good.

  If it is determined in S701 that a DHCP RELEASE packet has not been received, the process proceeds to S706. In step S <b> 706, the digital camera determines whether a disconnection notification for disconnecting the wireless LAN connection has been received from the printer A. The disconnection notification is as described above. If the digital camera receives a disconnection notification, the process advances to step S707. On the other hand, if the digital camera does not receive a disconnection notification, the process of this flowchart ends.

  In step S <b> 707, the DHCP server control unit 205 of the digital camera cancels the association between the IP address assigned to the printer A and the MAC address of the printer A in the DHCP table stored by itself. In step S708, the ARP table control unit 207 of the digital camera deletes the IP address of the printer A and the MAC address record associated with the IP address from the ARP table stored in the digital camera. In this embodiment, this processing synchronizes the contents stored in the DHCP table and the contents stored in the ARP table, so that the IP address of the printer A that has left the wireless LAN network 31 does not remain in the ARP table. Thereafter, in S709, the digital camera disconnects the connection between the digital camera and the printer A via the wireless LAN network 31. Note that the trigger of the disconnection process performed in S709 is not limited to the reception of the disconnection notification, as described in the process of S705.

  As described above, when the digital camera according to the present embodiment receives a DHCP RELEASE packet from the printer A or receives a wireless LAN disconnection notification, the digital camera not only updates the contents stored in the DHCP table but also stores the ARP table. The contents are also updated. Thereby, the conventional problem described in FIG. 6 can be prevented.

  In particular, in the present embodiment, even when a DHCP RELEASE packet is not received, the DHCP table and the ARP table are updated when a wireless LAN disconnection notification is received. Thus, for example, even if the printer A to which a certain IP address is assigned by DHCP leaves the wireless LAN and there is a printer B in which the same IP address is manually set, the digital camera is normal with this printer B. Will be able to communicate.

  The sequence diagram of FIG. 8 is a diagram illustrating a communication flow of the digital camera, the printer A, and the printer B in the present embodiment. Compared with FIG. 6, how the conventional problems are solved will be described.

  The processing from F801 to F807 is the same as F601 to F607 in FIG. In F807, when the digital camera receives the DHCP RELEASE packet from the printer A, the digital camera updates the ARP table stored in itself (F808). By this process, the record in which the IP address 192.168.0.101 is associated with the acquired MAC address in the ARP table stored in the digital camera is deleted. Thereafter, processing from F809 to F813 is the same as F608 to F612 in FIG. In F813, the digital camera acquires the IP address 192.168.0.101 of the printer B. In order to communicate with the printer B, information on the MAC address as the transmission destination is necessary, but the information on the IP address 192.168.0.101 in the ARP table has been deleted by the processing of F808. Therefore, the digital camera executes ARP and acquires the MAC address. Then, the digital camera registers the IP address 192.168.0.101 and the acquired MAC address in association with each other in the ARP table. The digital camera communicates with the printer B using the IP address 192.168.0.101 and the acquired MAC address (F814).

  As described above, according to the present embodiment, a communication error due to a mismatch between information in the DHCP table and the ARP table is eliminated, and communication with the partner apparatus can be performed more reliably.

[Example 2]
In the first embodiment, when a digital camera operating as a DHCP server receives an IP address allocation release request sent from a printer operating as a DHCP client, the ARP table is updated in conjunction with the request. I made it. Alternatively, when a wireless LAN disconnection notification is received from the printer, the ARP table is updated in conjunction with it. That is, the ARP table is updated in conjunction with at least one of reception of an IP address assignment release request and reception of a wireless LAN disconnection notification. In contrast, in the second embodiment, the ARP table is updated in conjunction with the IP address assignment by DHCP without waiting for the IP address assignment release request or the wireless LAN disconnection notification. Hereinafter, the second embodiment will be described focusing on differences from the first embodiment.

  Since the configuration of each communication apparatus and the configuration of the wireless LAN network system in this embodiment are the same as those in the first embodiment, description thereof will be omitted. Also in this embodiment, the communication device 32 operating as an access point is a digital camera, and the communication devices 33 and 34 operating as stations are printers. A digital camera that operates as an access point becomes a DHCP server, and a printer that operates as a station becomes a DHCP client.

  FIG. 9 is a flowchart showing processing executed in the digital camera when the digital camera and the printer perform communication by wireless LAN. Since the flowchart of FIG. 9 corresponds to the flowchart of FIG. 4 of the first embodiment, differences from FIG. 4 will be described in the description of FIG. Each step in FIG. 9 is processed by the control unit 102 executing each program (for example, each software module shown in FIG. 2) stored in the storage unit 103 in FIG. 1 in the digital camera.

  The processes from S401 to S404 are the same as those in FIG. That is, the digital camera forms a wireless LAN network and establishes a connection with the printer A via the wireless LAN. Then, an IP address is assigned to the printer A of the digital camera, and the assigned IP address and the MAC address of the printer A are associated and registered in the DHCP table.

  Thereafter, in S901, the digital camera updates the ARP table. Specifically, the update processing of the ARP table performed in S901 may be any of the following. As a first method, the ARP table control unit 207 of the digital camera also registers the IP address and MAC address registered in the DHCP table in S404 in the ARP table. At this time, if the same IP address is already registered in the ARP table, the existing IP address record is invalidated by overwriting the table. In this way, the contents of these tables are synchronized by updating the ARP table in the same manner when the DHCP table is updated.

  As a second method, the ARP table control unit 207 of the digital camera determines whether the IP address registered in the DHCP table in S404 exists in the ARP table. If it exists, the record is deleted. If it does not exist, no processing is executed. In this way, it is prevented that records that may not be used remain in the ARP table.

  As a third method, the ARP table control unit 207 of the digital camera clears the entire ARP table in response to the update of the DHCP table in S404. In this way, it is prevented that records that may not be used remain in the ARP table.

  The ARP table update process executed in S901 may be any of these three methods. Further, which of these three types of methods is used may be selectively switched according to a user operation, or may be automatically switched using information on the network system configuration. For example, in the case of a system configuration in which a digital camera and a printer can communicate directly without using a relay device, it is desirable to use the first method. On the other hand, in the case of a system configuration that requires a relay device to communicate between the digital camera and the printer, the second method or the third method is desirable.

  After the processing of S901 is performed, the processing from S405 to S410 is the same as that in FIG. However, the determination result in S406 varies depending on which of the above three methods is used in S901. If the first method is used, S406 is always Yes, and the process proceeds to S407. On the other hand, if the second method or the third method is used, the answer is always No in S406, and the process proceeds to S408.

  As described above, in this embodiment, the ARP table is updated in conjunction with the IP address assignment by DHCP without waiting for an IP address assignment release request or a wireless LAN disconnection notification. According to this embodiment, the conventional problem described in FIG. 6 can be prevented.

[Other Embodiments]
The above embodiment shows an example for carrying out the present invention, and the above embodiment can be variously modified without departing from the gist of the present invention.

  The communication device of the above embodiment is not limited to a digital camera or a printer. It may be a PC or a tablet terminal, and may be a mobile terminal such as a mobile phone or a smartphone. Further, it may be an image processing apparatus such as a copying machine, a scanner, a FAX, or a multifunction machine, or a digital home appliance such as a television or a recorder.

  The network in which the communication device exists is not limited to the infrastructure mode wireless network in which the access point exists, and may be an ad hoc mode wireless network that does not require an access point. In the case of an ad hoc network, it is preferable to negotiate between communication devices to determine which communication device performs the function of the DHCP server.

  The above embodiment has been described by taking an example of a wireless LAN compliant with IEEE 802.11. However, the present invention may be implemented in other wireless media such as wireless USB, MBOA, Bluetooth (registered trademark), UWB, and ZigBee (registered trademark). Moreover, you may implement in wired communication media, such as wired LAN. Here, MBOA is an abbreviation for Multi Band OFDM Alliance. UWB includes wireless USB, wireless 1394, WINET, and the like.

  In the above embodiment, DHCP is used as a method for assigning an IP address to a communication apparatus as a communication partner. However, another method such as address assignment by AUTOIP or automatic link local address assignment by IPv6 is used. It doesn't matter. In that case, the DHCP table of the above embodiment is replaced with a table indicating the correspondence between the IP address and the MAC address in each protocol.

  In the above embodiment, UPnP SSDP is used as a method of searching for a communication device as a communication partner, but another method such as mDNS or SLP may be used.

  Furthermore, the present invention is also realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program code. It is a process to be executed. In this case, the program and the storage medium storing the program constitute the present invention.

102 Control unit 103 Storage unit 104 Wireless unit 105 Display unit

Claims (22)

A communication device,
Assigning means for assigning IP addresses to other communication devices;
First storage means for storing the assigned IP address and identification information of the other communication device in association with each other;
Obtaining means for obtaining a physical address as a destination for communicating with the other communication device;
Second storage means for storing the assigned IP address and the acquired physical address in association with each other;
Receiving means for receiving a release request for requesting release of the IP address assignment from the other communication device;
Updating means for updating the storage content of the first storage means in response to the release request received by the receiving means, and updating the storage content of the second storage means so as to correspond to the update;
A communication apparatus comprising: The first storage means stores a table in which the assigned IP address is associated with identification information of the other communication device,
The communication apparatus according to claim 1, wherein the second storage unit stores a table in which the assigned IP address is associated with the acquired physical address.   The updating unit deletes the identification information of the other communication device from the table stored by the first storage unit in response to the release request received by the receiving unit, and the second storage unit The communication apparatus according to claim 2, wherein the assigned IP address and the acquired physical address are deleted from the stored table. A communication device,
Assigning means for assigning IP addresses to other communication devices;
First storage means for storing the assigned IP address and identification information of the other communication device in association with each other;
Obtaining means for obtaining a physical address as a destination for communicating with the other communication device;
Second storage means for storing the assigned IP address and the acquired physical address in association with each other;
Receiving means for receiving notification from the other communication device to disconnect the network connection with the communication device;
Updating means for updating the storage content of the first storage means in response to the reception of the notification by the receiving means, and updating the storage content of the second storage means so as to correspond to the update;
A communication apparatus comprising: The first storage means stores a table in which the assigned IP address is associated with identification information of the other communication device,
5. The communication apparatus according to claim 4, wherein the second storage unit stores a table in which the assigned IP address is associated with the acquired physical address.   The update unit deletes the identification information of the other communication device from the table stored by the first storage unit in response to the reception of the notification by the reception unit, and stores it by the second storage unit. The communication apparatus according to claim 2, wherein the assigned IP address and the acquired physical address are deleted from the assigned table. Communication means for communicating with the other communication device by a wireless LAN compliant with IEEE802.11.
The communication apparatus according to claim 1, wherein the IP address assigned by the assigning unit is an address used when the communication unit communicates with the other communication apparatus. Communication means for communicating with the other communication device by a wireless LAN compliant with IEEE802.11.
The communication apparatus according to claim 4, wherein the reception unit receives a notification of disconnecting the wireless LAN connection from the other communication apparatus.   The communication apparatus according to claim 1, wherein the assigning unit assigns an IP address using DHCP, and the obtaining unit obtains a physical address using ARP.   The communication apparatus according to claim 1, wherein the identification information stored by the first storage unit is a MAC address. A communication device,
Assigning means for assigning an IP address to another communication device using DHCP;
Registration means for registering the MAC address acquired by the ARP specifying the IP address and the IP address in the ARP table;
Updating means for updating the ARP table in response to the assignment of the IP address being canceled by DHCP;
A communication apparatus comprising: A communication device,
Assigning means for assigning an IP address to another communication device using DHCP;
Registration means for registering the MAC address acquired by the ARP specifying the IP address and the IP address in the ARP table;
Updating means for updating the ARP table in response to receiving a notification for disconnecting the network connection with the communication device from the other communication device;
A communication apparatus comprising: The communication apparatus according to claim 11 or 12, wherein the updating unit invalidates registration of the IP address and the MAC address in the ARP table.   The communication apparatus according to claim 13, wherein the updating unit deletes registration of the IP address and the MAC address in the ARP table. A communication device,
Assigning means for assigning an IP address to another communication device using DHCP;
An updating means for updating the ARP table in accordance with the assignment of the IP address by the assigning means without executing the ARP specifying the IP address;
A communication apparatus comprising: Communication means for communicating with the other communication device by a wireless LAN compliant with IEEE802.11.
The communication apparatus according to claim 11, wherein the IP address assigned by the assigning unit is an address used when the communication unit communicates with the other communication apparatus. A communication device control method comprising:
An assigning step of assigning IP addresses to other communication devices;
A first storage step of storing the assigned IP address and the identification information of the other communication device in association with each other in a storage unit;
An acquisition step of acquiring a physical address as a destination for communicating with the other communication device;
A second storage step of storing the allocated IP address and the acquired physical address in a storage unit in association with each other;
Receiving a release request for requesting release of the IP address assignment from the other communication device;
In response to the release request received by the receiving step, the storage content in the first storage step is updated, and the storage content in the second storage step is updated to correspond to the update;
A method for controlling a communication apparatus, comprising: A communication device control method comprising:
An assigning step of assigning IP addresses to other communication devices;
A first storage step of storing the assigned IP address and the identification information of the other communication device in association with each other in a storage unit;
An acquisition step of acquiring a physical address as a destination for communicating with the other communication device;
A second storage step of storing the allocated IP address and the acquired physical address in a storage unit in association with each other;
Receiving from the other communication device a notification for disconnecting the network connection with the communication device;
An update step of updating the storage content in the first storage step in response to the reception of the notification by the reception step, and updating the storage content in the second storage step to correspond to the update;
A method for controlling a communication apparatus, comprising: A communication device control method comprising:
An assigning step of assigning an IP address to another communication device using DHCP;
A registration step of registering the MAC address acquired by the ARP specifying the IP address and the IP address in an ARP table;
An update step of updating the ARP table in response to the IP address being deallocated by DHCP;
A method for controlling a communication apparatus, comprising: A communication device control method comprising:
An assigning step of assigning an IP address to another communication device using DHCP;
A registration step of registering the MAC address acquired by the ARP specifying the IP address and the IP address in an ARP table;
An update step of updating the ARP table in response to receiving a notification of disconnecting a network connection with the communication device from the other communication device;
A method for controlling a communication apparatus, comprising: A communication device control method comprising:
An assigning step of assigning an IP address to another communication device using DHCP;
An updating step for updating the ARP table without executing the ARP designating the IP address in accordance with the assignment of the IP address in the assignment step;
A method for controlling a communication apparatus, comprising:   The program for making a computer perform each step of the control method as described in any one of Claims 17 thru | or 21.

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