JP2005348337A - Communication apparatus, communication system, method for controlling the communication system, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain interconnectivity between communication apparatuses even if communication between a DHCP server and another communication apparatus is disabled. <P>SOLUTION: There are provided a first address setting section for acquiring a network address from an address allocation device which allocates a network address to an apparatus connected to a communication network, and setting the acquired network address as its own network address; a communication disability detection section for detecting that communication with the address allocation device is disabled; a communication disability message transmission section for transmitting, to another communication apparatus connected to the communication network, a communication disability message indicating that the communication with the address allocation device is disabled, when the communication with the address allocation device is disabled; and a second address setting section for determining a network address to be given to itself and setting it as its own network address when the communication with the address allocation device is disabled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  There are a stateful method in which a communication device sets its own network address, a stateful method in which a network address is acquired from a server, and a stateless method in which the communication device itself determines a network address. As a stateful network address setting method, DHCP (Dynamic Host Configuration Protocol) is known. AutoIP is known as a stateless network address setting method. AutoIP is also called APIPA (Automatic Private IP Addressing).

If a communication device connected to the communication network can access the DHCP server, the communication device acquires a network address from the DHCP server, and if not, the communication device itself determines the network address.
"Dynamic Configuration of Link-Local IPv4 Addresses" by Stuart Cheshire INTERNET-DRAFT 2004 "Dynamic Host Configuration Protocol" by R. Droms, RFC 2131 1997

  However, when the address system of the network address assigned by a server such as a DHCP server (for example, the subnet address and subnet mask in the IP address) is different from the address system of the network address determined by the communication device itself by AutoIP or the like If all the communication devices do not set the IP address using the same setting method, communication between the communication devices cannot be performed. Therefore, when communication between the DHCP server and another communication device becomes impossible after a certain communication device sets a network address by DHCP, the other communication device sets a network address by AutoIP. Thus, communication may not be possible between these communication devices due to a difference in the set address system.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a communication device, a communication system, a communication system control method, and a program capable of improving the interoperability between the communication devices. And

  A main invention of the present invention for solving the above problems is a communication device, which is connected to a communication network and obtains a network address from an address assignment device that assigns a network address to the device connected to the communication network. A first address setting unit that sets the acquired network address as its network address, a communication inability detecting unit that detects that communication with the address allocation device is disabled, and the address allocation. When communication with the device is disabled, a communication disable message indicating that communication with the address assignment device has been disabled is sent to another communication device connected to the communication network. When communication between the incommunicable message transmitting unit to be transmitted and the address allocation device is disabled Determining the network address for imparting to itself, and a second address setting unit for setting the determined the network address as its network address, and further comprising a.

  ADVANTAGE OF THE INVENTION According to this invention, the interconnection property between communication apparatuses can be improved.

=== System configuration ===
FIG. 1 shows a configuration example of a communication system 1 according to the present embodiment. The communication system 1 includes a plurality of network devices 10 and a DHCP (Dynamic Host Configuration Protocol) server 11.

  The network device 10 is, for example, a home appliance having a communication function, a router, or a personal computer. The communication system 1 according to the present embodiment assumes that network devices 10 are connected to each other via a LAN 12 in a home so that they can communicate with each other.

  Each network device 10 and the DHCP server 11 are connected to each other via a local area network (LAN) 12 so that they can communicate with each other. The LAN 12 is a communication network in which communication is performed in accordance with, for example, TCP / IP (Transmission Control Protocol / Internet Protocol). The LAN 12 is constructed using, for example, a communication line such as Ethernet (registered trademark), a telephone line, a power line, wireless, or infrared.

  The DHCP server 11 assigns a network address to the network device 10 connected to the LAN 12. In the present embodiment, the network address in the LAN 12 is an IP address. The DHCP server 11 assigns a private address (192.168.0.0 to 192.168.255.255) to the network device 10. When the network device 10 cannot communicate with the DHCP server 11, the network device 10 determines its own IP address, and sets the determined IP address as its own IP address. The network device 10 sets a link local address (169.254.4.0 to 169.254.255.255) as its own IP address.

  FIG. 2 shows a configuration example of hardware of the network device 10 according to the present embodiment. The network device 10 receives a packet that flows to the LAN 12 or receives a packet that flows to the LAN 12, a CPU 20 that controls the entire network device 10, a RAM (Random Access Memory) 21 and a ROM (Read Only Memory) 22 that store data and programs. The network interface unit 23 that transmits / receives data to / from other network devices 10 connected to the LAN 12 and the monitor 25 that is connected to the outside. And a display control unit 24. The CPU 20 reads out the program stored in the ROM 22 to the RAM 21 and executes it, thereby realizing various functions to be described later.

  FIG. 3 is a functional block diagram of the network device 10. The network device 10 includes a communication enable / disable message transmitter 31 (communication disabled message transmitter and communicable message transmitter), a communication enable / disable message receiver 32 (communication disabled message receiver and a communicable message receiver), and a communication enable / disable checker 33. (Communication impossible detection unit, communication possible detection unit), DHCP address setting unit 34 (first address setting unit, third address setting unit), AutoIP address setting unit 35 (second address setting unit, fourth address) A setting unit) and an address setting information storage unit 40. The communication enable / disable message transmitting unit 31, the communication enable / disable message receiving unit 32, the communication enable / disable checking unit 33, the DHCP address setting unit 34, and the AutoIP address setting unit 35 are read by the CPU 20 to the RAM 21 and executed. The address setting information storage unit 40 is realized in the storage area of the RAM 21.

  The communication availability checking unit 33 checks whether communication with the DHCP server 11 is possible. The communication availability checking unit 33 broadcasts a DHCPDISCOVER packet defined by DHCP on the LAN 12, and determines whether or not the DHCPOFFER packet returned from the DHCP server 11 in response to the DHCPDISCOVER packet can be received within a predetermined period. 11 determines whether or not communication with the terminal 11 is possible.

  The communication enable / disable message transmission unit 31 transmits a communication enable / disable message that is a message including communication enable / disable information indicating whether or not the network device 10 can communicate with the DHCP server 11 to another network device 10. To do. In the present embodiment, the communication enable / disable message transmission unit 31 transmits a communication enable / disable message to other network devices 10 connected to the LAN 12 by broadcasting the communication enable / disable message on the LAN 12. The communication enable / disable message receiving unit 32 receives a communication enable / disable message transmitted from another network device 10.

  The DHCP address setting unit 34 sets a stateful IP address by DHCP. The DHCP address setting unit 34 sets the IP address assigned by the DHCP server 11 as the IP address of the network device 10. The IP address setting process by DHCP is detailed in RFC (Request For Comments) 2131, for example.

  The AutoIP setting unit 35 sets a stateless IP address using AutoIP. The AutoIP setting unit 35 determines the IP address of the network device 10 without connecting to the server.

  FIG. 4 shows the flow of IP address setting processing by AutoIP. Among the link local addresses (169.254.0.0 to 169.254.255.255), the network device 10 randomly selects candidates from “169.254.1.0 to 169.254.254.255”. One IP address is selected (S401). The network device 10 broadcasts a message in which the selected IP address is set on the LAN 12 by ARP (ARPPROBE), and the selected IP address depends on whether there is a response to the ARP at a predetermined time. It is determined whether or not it is used by the network device 10 (S402). When the network device 10 determines that the selected IP address is not used (S402: YES), the network device 10 sets the IP address as the IP address of the network device 10 (S403). The network device 10 broadcasts a message including the set IP address on the LAN 12 by ARP (ARPANNONCE), and notifies the other network device 10 of the used IP address (S404). Note that the network device 10 receives a message transmitted from another network device 10 by ARP, and when the received message includes the same IP address as its own, the processing from (S401) is performed again. Set its own IP address.

  FIG. 5 is a diagram illustrating a configuration example of the address setting information storage unit 40. As shown in FIG. 5, the address setting information storage unit 40 includes an address setting method column 41 and a message reception flag column 42.

  In the address setting method column 41, information indicating the setting method of the IP address of the network device 10 is set. When the DHCP address setting unit 34 sets the IP address of the network device 10 by DHCP, “DHCP” is set in the address setting method column 41. When the AutoIP address setting unit 35 sets the IP address of the network device 10 using AutoIP, “AutoIP” is set in the address setting method column 41. The network device 10 can determine whether or not the network device 10 can communicate with the DHCP server 11 based on whether or not “DHCP” is set in the address setting method column 41.

  In the message reception flag column 42, a value indicating whether or not the network device 10 has received a communication enable / disable message from another network device 10 is set. When the network device 10 receives a communication enable / disable message from another network device 10, “◯” is set in the message reception flag field 42.

  FIG. 6 is a diagram illustrating a configuration example of a communication availability message. As shown in FIG. 6, the communication enable / disable message includes a transmission source IP address column 51, a destination IP address column 52, and a data content column 53.

  In the transmission source IP address column 51, the IP address of the network device 10 that transmits the communication availability message is set. If no IP address is set for the network device 10, “0.0.0.0” is set. Further, while the network device 10 is performing the IP address setting processing by DHCP or AutoIP, the communication availability message transmitted from the network device 10 performing the IP address setting processing also indicates “0.0. .0 "is set.

  In the destination IP address column 52, an IP address as a transmission destination of the communication availability message is set. In this embodiment, since the communication enable / disable message is broadcast on the LAN 12, a limited broadcast address “255.255.255.255” is set in the destination IP address field 52.

  Communication availability information is set in the data content column 53. When communication between the network device 10 and the DHCP server 11 is possible, “◯” is set in the data content column 53, and when communication is impossible, “X” is set.

=== Address setting processing ===
Hereinafter, details of the process of setting the IP address (hereinafter referred to as address setting process) in the network device 10 according to the present embodiment will be described.

  The network device 10 of this embodiment sets an IP address by DHCP if communication with the DHCP server 11 is possible, and sets an IP address by AutoIP if communication is impossible. In addition, the network device 10 notifies the other network devices 10 of whether communication with the DHCP server 11 is possible.

  FIG. 7 is a diagram for explaining the flow of address setting processing in the network device 10.

  When the DHCP lease period or the predetermined interval period elapses (timeout), or the network device 10 receives a communication enable / disable message from another network device 10 (S701), the network device 10 receives the message reception flag field 42 of the address setting information storage unit 40. Is updated (S702). The network device 10 sets “x” in the message reception flag column 42 when the DHCP lease period or the predetermined interval period elapses, and stores the message reception flag column 42 when the communication availability message is received. Set “O”.

  When the DHCP lease period or the predetermined interval period has elapsed (S703: NO), the network device 10 broadcasts a DHCPDISCOVER packet on the LAN 12, and sends a DHCPOFFER packet returned from the DHCP server 11 to the broadcast DHCPDISCOVER packet. It is checked whether or not it can be received within a predetermined period (S704). The network device 10 determines whether or not communication with the DHCP server 11 is possible depending on whether or not the DHCPOFFER packet can be received from the DHCP server 11 (S705).

  When the communication availability message is received (S703: YES), the network device 10 refers to the communication availability information included in the communication availability message to determine whether or not communication with the DHCP server 11 is possible. Judgment is made (S705).

  When communication with the DHCP server 11 is not possible (S705: NO), and “AutoIP” is set in the address setting method column 41 of the address setting information storage unit 40 (S706: NO), the network device 10 The address setting process ends. The network device 10 uses the IP address based on the already set AutoIP method as it is.

  When communication with the DHCP server 11 is not possible (S705: NO) and “DHCP” is set in the address setting method column 41 (S706: YES), the message reception flag of the address setting information storage unit 40 If “×” is set in the field 42 (S707: NO), the network device 10 sets a communication enable / disable message (hereinafter, referred to as “communication enable / disable information” indicating that communication with the DHCP server 11 is impossible). A communication impossible message) is broadcast on the LAN 12 to notify other network devices 10 that communication with the DHCP server 11 has become impossible (S708). The network device 10 sets an IP address by AutoIP (S709), and sets “AutoIP” in the address setting method column 41 of the address setting information storage unit 40.

  On the other hand, when communication with the DHCP server 11 is possible (S705: YES), the network device 10 determines whether “DHCP” is set in the address setting method column 41 of the address setting information storage unit 40. (S710).

  When “DHCP” is set in the address setting method column 41 (S710: YES), the network device 10 sets the DHCP lease period depending on whether “x” is set in the message reception flag column 42 or not. It is determined whether or not it has elapsed (S711). When the DHCP lease period has passed (S711: YES), the network device 10 sets an IP address by DHCP (S712), and sets “DHCP” in the address setting method column 41 of the address setting information storage unit 40. Set.

  When “AutoIP” is set in the address setting method column 41 (S710: NO), and “x” is set in the message reception flag column 42 (S713: NO), the network device 10 is a DHCP server. A communication enable / disable message (hereinafter, referred to as a communication enable message) in which communication enable / disable information indicating that communication with the server 11 is possible is broadcast on the LAN 12 and is communicated to the other network devices 10 with the DHCP server 11. The fact that communication is possible is notified (S714). The network device 10 sets the IP address by DHCP (S715), and sets “DHCP” in the address setting method column 41 of the address setting information storage unit 40.

  As described above, when communication with the DHCP server 11 becomes impossible, the network device 10 sets an IP address by AutoIP, and broadcasts a communication failure message on the LAN 12, so that other network devices 10 Is notified that communication with the DHCP server 11 has become impossible. Further, when communication with the DHCP server 11 becomes possible, the network device 10 sets an IP address by DHCP and broadcasts a communicable message on the LAN 12 to the other network devices 10. Notify that communication with the DHCP server 11 is possible. The network device 10 that has received the broadcast communication enable / disable message sets an IP address by DHCP or AutoIP according to the communication enable / disable information set in the received communication enable / disable message. As a result, when any one of the network devices 10 connected to the LAN 12 detects that communication with the DHCP server 11 is enabled or disabled, the IP address performed in the network device 10 is determined. The IP address is also set in the other network device 10 by the same method as the setting method. Therefore, mutual communication between the network devices 10 can be maintained.

=== Specific Example of Address Setting Processing ===
FIG. 8 is a diagram showing a specific example of the address setting process described above.
The network device A (10) broadcasts a DHCPDISCOVER packet on the LAN 12 (S801). The DHCP server 11 receives the DHCPDISCOVER packet and broadcasts the DHCPOFFER packet on the LAN 12 (S802). Upon receiving the DHCPOFFER packet, the network device A (10) determines that communication with the DHCP server 11 is possible, and sets an IP address by DHCP (S803). Similarly to the network device A (10), the network device B (10) broadcasts the DHCPDISCOVER packet on the LAN 12 (S804), receives the DHCPOFFER packet (S805), and sets the IP address by DHCP (S806). .

  After receiving the DHCPOFFER packet, the network device A (10) broadcasts the DHCPDISCOVER packet again on the LAN 12 after the lease period T81 has elapsed (S807). Here, if the DHCP server 11 is unable to communicate with the network device 10 on the LAN 12 due to, for example, the power being turned off or a failure in the communication path, the communication is disabled (S808). The network device A (10) cannot receive the DHCPOFFER packet from the DHCP server 11 within the timeout period T82 after broadcasting the DHCPDISCOVER packet. Since the network device A (10) cannot receive the DHCPOFFER packet within the timeout period T82, the network device A (10) determines that communication with the DHCP server 11 cannot be performed, and broadcasts a communication disable message on the LAN 12 (S809). ), An IP address is set by AutoIP (S810).

When the network device B (10) receives the communication disable message broadcast on the LAN 12, the network device B (10) sets an IP address by AutoIP (S811).
When the network device B (10) cannot receive the notification impossible message, the DHCP device lease time T83 has elapsed in the network device B (10), and communication with the DHCP server 11 is impossible. Until the IP address is set by AutoIP, the network device B (10) is set with the IP address by the DHCP method. Accordingly, a period T84 from when the network device A (10) sets the IP address by AutoIP to when the network device B (10) sets the IP address by AutoIP is the same as that of the network device A (10). Communication using the IP address cannot be performed with the network device B (10).

  However, the network device A (10) of the present embodiment sets an IP address by AutoIP and broadcasts a communication impossible message on the LAN 12, and the network device B (10) receives the broadcast communication disabled message. In response to this, the IP address is set by AutoIP. Accordingly, the network device A (10) sets an IP address by AutoIP during a period in which communication using the IP address cannot be performed between the network device A (10) and the network device B (10). It can be shortened to a period T85 until the network device B (10) sets an address by AutoIP in response to the reception of the communication impossible message. Therefore, the interconnectivity of the network device 10 in the communication system 1 can be improved.

  FIG. 9 shows a specific example of the address setting process when the DHCP server 11 is connected to the LAN 12 again after the process shown in FIG.

  After the network device A (10) broadcasts a communication failure message on the LAN 12 (S809), the network device C (10) connects to the LAN 12 (S901), and the network device C (10) sends a DHCPDISCOVER packet on the LAN 12 (S902). The network device C (10) cannot receive the DHCPOFFER packet from the DHCP server 11 during the predetermined timeout period T91, and sets the IP address by AutoIP (S903).

  On the other hand, the network device A (10) broadcasts a DHCPDISCOVER packet on the LAN 12 when a predetermined interval T92 elapses after the IP address is set by AutoIP (S809) (S904).

  When the DHCP server 11 connects to the LAN 12 (S905) and receives the DHCPDISCOVER packet broadcast from the network device A (10), the DHCPOFFER packet is broadcast on the LAN 12 (S906).

  The network device A (10) receives the DHCPOFFER packet broadcast from the DHCP server 11, and determines that communication with the DHCP server 11 is possible. A communicable message is broadcast on the LAN 12 (S907), and the network device A (10) sets an IP address by DHCP (S908).

  Upon receiving the broadcast communicable message, the network device C (10) broadcasts a DHCPDISCOVER packet on the LAN 12 (S909), receives a DHCPOFFER packet (S910), and sets an IP address by DHCP (S911). .

  When the network device C (10) cannot receive the communicable message, the network device C (10) has passed the predetermined interval period T93 and can communicate with the DHCP server 11. Until the IP address by DHCP is set and the IP address by DHCP is set, the IP address by the AutoIP method is set in the network device C (10). Accordingly, the period T94 from when the network device A (10) sets the IP address by DHCP until the IP address is set by DHCP in the network device C (10) is the same as that of the network device A (10). Communication using the IP address cannot be performed with the network device C (10).

  However, the network device A (10) of the present embodiment sets the IP address by DHCP and broadcasts a communicable message on the LAN 12, and the network device C (10) transmits the broadcast communicable message. An IP address is set by DHCP in response to reception. Accordingly, the network device A (10) sets the IP address by DHCP during the period in which communication using the IP address cannot be performed between the network device A (10) and the network device B (10), and the network It can be shortened to the engine T95 until the device C (10) sets the IP address by DHCP according to the communicable message. Therefore, in the example shown in FIG. 9, as in the example shown in FIG. 8, the period during which communication using the IP address cannot be performed between the network device A (10) and the network device C (10) is shortened. In addition, the interconnectivity of the network device 10 in the communication system 1 can be improved.

  FIG. 10 is a specific example of a change in the state of the network device 10 in the communication system 1 according to the present embodiment.

  Network devices A to C (10) are connected to the LAN 12 (FIG. 10A). In this state, each of the network devices A to C (10) cannot communicate with the DHCP server 11, and an IP address by AutoIP is set.

  The DHCP server 11 is connected to the LAN 12 (FIG. 10B), and a new network device D (10) is connected to the LAN 12 (FIG. 10C). The network device D (10) broadcasts a DHCPDISCOVER packet on the LAN 12 (S1001). The DHCP server 11 receives the DHCPDISCOVER packet and broadcasts the DHCPOFFER packet on the LAN 12 (S1002). The network device D (10) receives the DHCPOFFER packet, determines that communication with the DHCP server is possible, and sets an IP address by DHCP.

  The network device D (10) broadcasts a communicable message on the LAN 12 (S1003) (FIG. 10 (d)). When each of the network devices A to C (10) receives the communicable message transmitted from the network device D (10), it broadcasts a DHCPDISCOVER packet on the LAN 12 (S1004). The DHCP server 11 broadcasts a DHCPOFFER packet in response to receiving a DHCPDISCOVER packet transmitted from each of the network devices A to C (10) (S1005). The network devices A to C (10) perform IP address setting by DHCP (FIG. 10 (e)). Thus, each of the network devices A to D (10) is set with the IP address set by DHCP, and can communicate with each other.

  For example, when the communication of the DHCP server 11 is cut off due to power cut or communication line failure, the DHCP lease period elapses in the network device B (10), and the network device B (10) sends the DHCPDISCOVER packet to the LAN 12 Even when broadcasted upward (S1006), the network device B (10) cannot receive a DHCPOFFER packet from the DHCP server 11 during a predetermined period (FIG. 10 (f)). If the network device B (10) fails to receive a DHCPOFFER packet from the DHCP server 11 within a predetermined period, it sets an IP address by AutoIP and broadcasts a communication disable message on the LAN 12 (S1007). ) Notifying other network devices 10 that communication with the DHCP server 11 is not possible (FIG. 10 (g)). When the network devices A, C, and D (10) receive the communication disable message broadcast from the network device B (10), the IP addresses are set by AutoIP. As a result, each of the network devices A to D (10) is set to a link local address by AutoIP, so that communication using the IP address is possible.

  Here, when the network device E (10) is connected to the LAN 12, the network device E (10) broadcasts a DHCPDISCOVER packet on the LAN 12 (S1008) and confirms that the DHCPOFFER packet cannot be received within a predetermined period. Then, the IP address is set by AutoIP (FIG. 10 (h)).

  As described above, the network device 10 according to the present embodiment sets an IP address by AutoIP when communication with the DHCP server 11 is disabled, and transmits a communication disabled message to another network device. The IP address is set by AutoIP in the other network device 10 as well. Similarly, when the network device 10 can communicate with the DHCP server 11, the IP address is set by DHCP, and a communication enable message is transmitted to the other network device 10, and the other network is set. Also in the device 10, the IP address is set by DHCP. Accordingly, it is possible to shorten the period during which communication cannot be performed between the network devices 10 connected to the LAN 12 due to the difference in the IP address setting method, and to improve the interoperability between the network devices 10.

=== Modification ===
In the present embodiment, the network device 10 that first detects the availability of communication with the DHCP server 11 broadcasts the communication enable / disable message in which the communication enable / disable information is set, but instead of the communication enable / disable message. An address setting message that is a message instructing to set an IP address may be transmitted. In this case, each of the network devices 10 that has received the address setting message checks whether communication with the DHCP server is possible. Thereby, each network device 10 can confirm whether or not communication with the DHCP server 11 is impossible.

  Further, although the network device 10 of the present embodiment uses the limited broadcast address (255.255.255.255) as the broadcast address in the LAN 12, the present invention is not limited to this, for example, a directed broadcast address. (All IP address host units assigned to each network device 10 are set to 1) can also be used. Thereby, it is possible to transmit a communication availability notification message beyond the router.

  In the present embodiment, the IPv4 format IP address is used as the network address in the LAN 12. However, the present invention is not limited to this. For example, an IPv6 format IP address may be used. In this case, for example, the IP address set by the AutoIP method is a link local address indicated by “FE80 :: / 64”.

  Further, the communication enable / disable message may be multicast in addition to being broadcast on the LAN 12. In this case, the address set in the destination IP address column 52 of the communication enable / disable message is not a broadcast address but a multicast address. Thereby, it is possible to cope with the case where the IP address assigned to the network device 10 follows the IPv6 system.

  In the present embodiment, the network device 10 broadcasts the DHCPDISCOVER packet on the LAN 12 and communicates with the DHCP server 11 depending on whether or not the DHCPOFFER packet from the DHCP server 11 for the transmitted DHCPDISCOVER packet can be received. The packet (data) flowing on the LAN 12 is monitored, and whether or not the communication with the DHCP server 11 is possible depending on whether or not the DHCPOFFER packet is flowing. May be determined. As a result, the amount of data broadcast can be suppressed.

  Further, the DHCP server 11 periodically broadcasts a message to the LAN 12, and the network device 10 communicates with the DHCP server 11 depending on whether the message broadcast from the DHCP server 11 can be received within a predetermined period. It may be determined whether communication is possible.

  Further, the DHCP server 11 is an end notification that is a message indicating that the communication is to be ended, for example, when the power is turned off or when a communication line failure is detected such that the communication quality deteriorates due to noise or the like. You may make it broadcast a message on LAN12. In this case, the network device 10 receives the end notification message (end notification message receiving unit), determines that communication with the DHCP server 11 is disabled in response to the reception of the end notification message, and performs IP communication using AutoIP. Set the address. Thereby, it is possible to reduce the communication load caused by each of the network devices 10 broadcasting the DHCPDISCOVER packet.

  Further, the DHCP server 11 may broadcast a start notification message, which is a message indicating the start of communication, on the LAN 12 when the power is turned on or the communication line is recovered from a failure. In this case, the network device 10 receives the start notification message (start notification message receiving unit), and sets an IP address by DHCP in response to reception of the start notification message. Thereby, the network device 10 can quickly determine that communication with the DHCP server 11 is possible.

  The network device 10 may display information on the set IP address on the monitor 25. FIG. 11 shows an example of a screen that displays information related to the IP address of the network device 10. The screen 60 displays an IP address column 61 that displays an IP address set in the network device 10, a subnet mask column 62 that displays a subnet mask of the IP address, and an IP address setting method ("DHCP" or "AutoIP"). An address setting method column 63 to be displayed is provided.

  The network device 10 may display the change history of the IP address setting method in the IP address on the monitor 25. FIG. 12 shows an example of a screen that displays the change history of the IP address setting method in the network device 10. The screen 70 displays a date and time column 71 for displaying the date and time when the IP address setting method is changed, an address setting method column 72 for displaying the IP address setting method, and an IP address and subnet mask set for the network device. An address field 73 and a content field 74 for displaying an explanation of the reason why the IP address setting method has been changed are provided.

  Although the present embodiment has been described above, the above examples are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

1 is a diagram showing an overall configuration of a communication system 1 according to an embodiment of the present invention. It is a figure which shows the hardware constitutions of the network apparatus 10 by one embodiment of this invention. 1 is a functional block diagram of a network device 10 according to an embodiment of the present invention. It is a figure which shows the flow of the setting process of IP address by AutoIP by one embodiment of this invention. It is a figure which shows one structural example of the address setting information storage part 40 by one embodiment of this invention. It is a figure which shows the example of 1 structure of the communication availability message by one embodiment of this invention. It is a figure explaining the flow of the address setting process in the network device 10 by one embodiment of this invention. It is a figure which shows the specific example of an address setting process by one embodiment of this invention. It is a figure which shows the specific example of an address setting process by one embodiment of this invention. It is a specific example of the change of the state of the network apparatus 10 by one embodiment of this invention. It is an example of the screen which displays the information regarding the IP address set to the network device 10 by one embodiment of this invention. It is an example of the screen which displays the change log | history of the IP address setting system in the network device 10 by one embodiment of this invention.

Explanation of symbols

10 Network equipment 11 DHCP server 12 LAN
20 CPU
21 RAM
22 ROM
DESCRIPTION OF SYMBOLS 23 Network interface part 24 Display control part 25 Monitor 31 Communication availability message transmission part 32 Communication availability message reception part 33 Communication availability inspection part 34 AutoIP address setting part 35 DHCP address setting part 40 Address setting information storage part 51 Source IP address 52 Destination IP address 53 Data contents

Claims (19)

Connect to the communication network,
A first address setting unit that acquires a network address from an address allocation device that allocates a network address to a device connected to the communication network, and sets the acquired network address as its own network address;
A communication inability detecting unit for detecting that communication with the address allocation device is disabled;
Communication indicating that communication with the address assignment device is disabled with respect to other communication devices connected to the communication network when communication with the address assignment device is disabled An incommunicable message sending unit for sending an infeasible message;
A second address setting unit that determines a network address to be assigned to itself when communication with the address assignment device is disabled, and sets the determined network address as its own network address;
A communication device comprising: The communication device according to claim 1,
The first address setting unit acquires the network address by DHCP;
Communication equipment characterized by. The communication device according to claim 1,
The second address setting unit determines the network address by AutoIP;
Communication equipment characterized by. A communication device that receives the communication failure message transmitted from the communication device according to claim 1,
A communication disabled message receiving unit for receiving the communication disabled message;
A third address setting unit that acquires the network address from the address allocation device and sets the acquired network address as its own network address;
A fourth address setting unit that determines a network address to be given to itself in response to reception of the incommunicable message, and sets the determined network address as its own network address;
A communication device comprising: The communication device according to claim 4,
A communication availability checking unit that checks whether communication with the address allocation device is possible in response to reception of the incommunicable message;
The fourth address setting unit determines a network address to be given to itself when communication with the address assignment device is impossible, and sets the determined network address as its own network address. about,
Communication equipment characterized by. The communication device according to claim 1,
A communicable detector that detects that communication with the address allocation device is possible;
A communicable message transmission for transmitting a communicable message indicating that communication with the address assigning device is possible when communication with the address assigning device is possible to the other communication device. And
With
The first address setting unit acquires a network address from the address assignment device when communication with the address assignment device becomes possible, and sets the acquired network address as its own network address. about,
Communication equipment characterized by. A communication device that receives the communicable message transmitted from the communication device according to claim 6,
A communication disabled message receiving unit for receiving the communication disabled message;
A third address setting unit that acquires the network address from the address allocation device and sets the acquired network address as its own network address;
A fourth address setting unit that determines a network address in the communication network in response to the reception of the communication disabled message, and sets the determined network address as its own network address;
A communicable message receiver that receives the communicable message;
With
The third address setting unit acquires a network address from the address allocation device in response to reception of the communicable message, and sets the acquired network address as its own network address;
Communication equipment characterized by. The communication device according to claim 1,
The communication failure detection unit monitors data flowing on the communication network, and data including information for the address allocation device to determine the network address of the communication device does not flow within a predetermined period. Detecting that communication with the address allocation device is disabled;
Communication equipment characterized by. The information processing apparatus according to claim 8,
The data is a DHCPOFFER packet defined in DHCP;
An information processing apparatus characterized by the above. The communication device according to claim 1,
An end notification message receiving unit for receiving an end notification message transmitted from the address allocation device and indicating that the address allocation device ends communication;
The second address setting unit determines a network address to be given to itself in response to reception of the end notification message, and sets the determined network address as its own network address;
Communication equipment characterized by. The communication device according to claim 1,
A start notification message receiving unit for receiving a start notification message transmitted from the address allocation device and indicating that the address allocation device starts communication;
The first address setting unit acquires the network address from the address allocation device in response to receiving the start notification message, and sets the acquired network address as its own network address;
Communication characterized. A communication system including an address assignment device for assigning a network address to a device connected to a communication network, and first and second communication devices connected to the communication network,
The first communication device is:
A first address setting unit that acquires the network address from the address allocation device and sets the acquired network address as a network address of the first communication device;
A communication inability detecting unit for detecting that communication with the address allocation device is disabled;
When communication with the address allocation device is disabled, a communication disabled message indicating that communication with the address allocation device is disabled is transmitted to the second communication device. A communication impossible message transmission unit;
When communication with the address assignment device becomes impossible, a network address to be given to the first communication device is determined, and the determined network address is used as a network address of the first communication device. A second address setting unit for setting,
The second communication device is:
A third address setting unit that acquires the network address from the address allocation device and sets the acquired network address as a network address of the second communication device;
A communication disabled message receiving unit that receives the communication disabled message transmitted from the first communication device;
A fourth address setting for determining a network address to be given to the second communication device in response to the reception of the communication impossible message and setting the determined network address as a network address of the second communication device. A section,
A communication system characterized by the above. A communication system according to claim 12,
The second communication device is:
In response to the reception of the incommunicable message, a communication availability checking unit that checks whether communication with the address allocation device is possible,
The third address setting unit determines a network address to be given to the second communication device when the communication availability checking unit determines that communication with the address assignment device is impossible. Setting the determined network address as the network address of the second communication device;
A communication system characterized by the above. A communication system according to claim 12,
The first communication device is:
A communicable detector that detects that communication with the address allocation device is possible;
A communicable message that transmits to the second communication device a communicable message indicating that communication with the address allocating device is possible when communication with the address allocating device is possible. A transmission unit;
With
The first address setting unit acquires a network address from the address assignment device when communication with the address assignment device becomes possible, and uses the acquired network address of the first communication device. Set as network address,
The second communication device is:
A communicable message receiving unit for receiving the communicable message transmitted from the first communication device;
The third address setting unit acquires a network address from the address allocation device in response to reception of the communicable message, and sets the acquired network address as a network address of the second communication device;
A communication system characterized by the above. A control method for a communication system comprising an address assignment device for assigning a network address to a device connected to a communication network, and first and second communication devices connected to the communication network,
The first communication device is:
Obtaining the network address from the address assignment device, setting the obtained network address as a network address of the first communication device;
Detecting that communication with the address allocation device is disabled,
When communication with the address allocation device is disabled, a communication disabled message indicating that communication with the address allocation device is disabled is transmitted to the second communication device,
When communication with the address assignment device becomes impossible, a network address to be given to the first communication device is determined, and the determined network address is used as a network address of the first communication device. Set,
The second communication device is:
Obtaining the network address from the address assignment device, setting the obtained network address as a network address of the second communication device;
Receiving the non-communication message transmitted from the first communication device;
Determining a network address to be given to the second communication device in response to reception of the incommunicable message, and setting the determined network address as a network address of the second communication device;
A control method for a communication system characterized by the above. A control method for a communication system according to claim 15,
The second communication device is:
In response to receiving the communication disable message, check whether communication with the address assignment device is possible,
When communication with the address assignment device is impossible, a network address to be given to the second communication device is determined, and the determined network address is set as a network address of the second communication device To do,
A control method for a communication system characterized by the above. A control method for a communication system according to claim 15,
The first communication device is:
Detecting that communication with the address assignment device is possible,
When communication with the address assignment device is enabled, a communication enable message indicating that communication with the address assignment device is enabled is sent to the second communication device,
When communication with the address allocation device is enabled, a network address is acquired from the address allocation device, and the acquired network address is set as a network address of the first communication device,
The second communication device is:
Receiving the communicable message transmitted from the first communication device;
In response to receiving the communicable message, obtaining a network address from the address assignment device, and setting the obtained network address as a network address of the second communication device;
A control method for a communication system characterized by the above. To the computer connected to the communication network,
Obtaining the network address from an address assignment device that assigns a network address to a device connected to the communication network, and setting the obtained network address as its own network address;
Detecting that communication with the address allocation device is disabled;
When communication with the address assignment device is disabled, it indicates that communication with the address assignment device is disabled for other communication devices connected to the communication network. Sending an incommunicable message;
Determining a network address to be assigned to itself, and setting the determined network address as its own network address;
A program for running Connect to a communication network, obtain a network address from an address assignment device that assigns a network address to a device connected to the communication network, set the obtained network address as its own network address, and When the communication between the address allocation device is detected and the communication with the address allocation device is disabled, the address allocation device is connected to another communication device connected to the communication network. A communication inability message indicating that communication with the address is disabled, and when communication with the address assignment device is disabled, a network address to be assigned to itself is determined and determined. Communication device that sets the network address as its own network address The computer receiving the incommunicable messages et transmitted,
Obtaining the network address from the address assignment device, and setting the obtained network address as its own network address;
Determining a network address in the communication network in response to the reception of the communication disable message, and setting the determined network address as its own network address;
A program for running

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