JP2008140209A - Communication device with switchable server function, and switching method therefor and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide service without depending on a network configuration, in a local network divided into one or more subnetworks by one or more routers. <P>SOLUTION: This communication device having a function (a server function) of providing the service to another communication device inside the local network has: a server function finding means finding the other communication device having the server function in the local network; a server function validity decision means deciding the communication device whose server function is enabled; and a server function switching means switching validation of the server function. When finding the other communication device having the server function, the communication device whose server function is enabled is switched when receiving a server function switching instruction from the communication device or when it is decided that the server function switching is necessary by the server function validity decision means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for switching communication devices, and more particularly, to communication between communication devices connected to a network in a local network, and particularly in a network in which a home network is composed of one or more routers. The present invention relates to a method for switching a communication device that provides a service to another communication device due to a change in configuration.

  In recent years, networking in the home has become widespread with the rapid development of the information society.

  In addition, communication devices and communication devices (hereinafter collectively referred to as “communication devices”) connected to the home network operate in cooperation with each other, that is, communicate with each other. By doing so, it is expected to improve the convenience of the service provided by the communication device. However, depending on the configuration of the home network, the service may not be received (communication between communication devices may not be possible).

  For example, when a router is connected instead of a hub, or when a wireless router is connected instead of a wireless access point, the home network is composed of a plurality of routers.

  Here, the home router (including the home wireless router) is equipped with a NAT or NAPT function. FIG. 1 shows a network configuration in which a wireless router 3b is connected under the modem built-in router 3a and a wireless router 3c is connected under the router 3a, and a plurality of routers are connected in series at home. Communication from the communication device 5b to the communication device 4b with a server function is possible because the router 3b is in the same network. Further, since the communication started from the communication device 5b to the communication device 5a is communication from the LAN side to the WAN side for the router 3b, address conversion (NAPT) is automatically set in the router 3b and communication is performed. It is possible to do. However, since the communication started from the communication device 5a to the communication device 4b with the server function is communication from the WAN side to the LAN side for the router 3b, the NAPT function and the firewall function operate and cannot communicate. In this case, since communication is possible from the LAN side to the communication device on the WAN side, the communication can be performed by providing the communication device with server function 4b with a function for starting communication from the communication device with server function 4b to the communication device 5a. Is possible. The same applies to the communication devices under the router 3c. However, in the case of a network configuration in which the router 3d is connected under the router 3a as shown in FIG. 2 and the three routers are connected in a triangle shape in the home, the communication equipment under the router 3d even if the above method is used. It is impossible for 5d and the communication device 4b with a server function under the router 3b to communicate. In this case, if the communication device 4a with the server function is supplying the service instead of the communication device 4b with the server function, the communication is performed from the LAN side to the WAN side for all the communication devices and can communicate with the communication device with the server function. It is.

  In order to avoid such a situation that the service cannot be received due to the network configuration, it is necessary to replace the communication device that supplies the service with a more optimal communication device when the network configuration changes.

  As a conventional method of replacing communication devices, check the remaining battery capacity of each slave unit in the network and the positional relationship of each terminal, and select a terminal suitable for network maintenance (slave unit with many slave units that can communicate). There was a new parent device (for example, see Patent Document 1). FIG. 42 shows a sequence of the conventional communication terminal changing method described in Patent Document 1.

In FIG. 42, the terminal 1 which is the master unit measures its own battery remaining amount (step S100), and if the remaining amount is less than the specified value, it decides to switch the master unit (step S101). Information on the remaining amount of each battery is requested (step S102). Each of the terminal 2 and the terminal 3 measures its own battery remaining amount (step S103) and notifies the terminal 1 which is the parent device (step S104), and the terminal 1 compares the respective remaining battery amounts received from the respective terminals. Thus, the terminal for changing the parent device has been determined (step S105).
Japanese Patent Laying-Open No. 2003-273388 (page 12, FIG. 3)

  However, in the conventional configuration, it is possible to select one of a plurality of communication devices connected to the same network and change the server function, but there is no concept that there is a network configuration that cannot be connected in the first place. Therefore, it cannot be applied to a home network composed of a plurality of routers as a problem.

  In other words, considering the connectivity in a home network composed of a plurality of routers, for the reasons described above, it is desirable to switch the server function to the communication device of the upper subnetwork. However, the conventional configuration is only on the same network. However, since the connectivity can only be taken into consideration, the server function cannot be changed to the communication device of the upper subnetwork. This causes a problem that the communication device of the upper subnetwork cannot receive service from the communication device having the server function of the lower subnetwork.

  An object of the present invention is to solve the above-described conventional problems, and to provide a method for replacing a communication device that supplies a service with a more optimal communication device when a network configuration changes.

  In order to solve the conventional problem, a communication device having a server function according to claim 1 of the present invention is provided in a local network connected to an external network, between the communication device in the local network and the external network. There is one or more routers, the local network is divided into one or more different sub-networks by one or more routers, connected to any router of the local network, and other communication devices in the local network A communication function having a function (server function) for providing a service to a server, a server function discovery means for discovering another communication apparatus having a server function existing in the local network, and at least a result of the server function discovery means A server that uses the server function to determine which communication device should be enabled Comprising a capacity proper determination means, the result of the server functions properly determining means, or by receiving the server function switching message from another communication apparatus, and a server function switching means for switching the valid and invalid server functions, the.

  With this configuration, when there are a plurality of communication devices having a server function on the network, it is possible to replace the communication device that supplies the service with a more optimal communication device.

  According to a second aspect of the present invention, there is provided a communication apparatus having the server function according to the first aspect, wherein the server function discovery means searches for another communication apparatus having a server function existing in the local network. Server function search means for receiving the server function search packet from another communication device having a server function, and transmitting a response packet to the server function search packet, the server function search means, A server function search packet is transmitted to another communication apparatus having a server function existing in the local network, and a response packet is received from another communication apparatus having the server function, or the search response means has a server function The communication device having the server function is found by receiving the server function search packet from the other communication device having.

  With this configuration, it is possible to detect whether there are a plurality of apparatuses having a server function on the network.

  A communication device according to claim 3 of the present invention is a communication device having a server function according to claim 2, wherein a router located between the router to which the communication device having the server function is connected and an external network is connected. The LAN side address information of one or more routers or the LAN side address information and the WAN side address information is acquired, and the acquired address information is used to connect to the first network to which the acquired address information belongs. The apparatus further comprises upper subnetwork existence determination means for estimating and storing a range of addresses that can be taken by the apparatus, and the server function search means is one or more of the first networks stored by the upper subnetwork existence determination means By using the address range information, an address that can be taken by the communication device having the server function is obtained, and the server is addressed to the address. To send an ability to search for a packet.

  With this configuration, a communication device having a server function that exists in a network to which the router to which the router is connected or another router (upper router) that exists between the router to which the router is connected and an external network, It becomes possible to find a communication device having a server function that exists under the connected router.

  A communication device according to claim 4 of the present invention is the communication device having the server function according to claim 2, wherein the search response means receives a server function search packet from another communication device having the server function. When the server function appropriateness determining means determines that it is a communication device that should enable the server function, it transmits a response packet of the server function search packet.

  With this configuration, it is possible to reduce the traffic load due to a search response when there are a large number of communication devices having a server function.

  According to a fifth aspect of the present invention, there is provided a communication apparatus having the server function according to the first aspect, wherein the server function appropriateness determining means is a server function appropriateness determining means, and the server function finding means is a server function. Other communication having a server function in a router to which a communication device having a network or a router to which a communication device having a server function is connected and another router (upper router) existing between an external network If a device is not found, it is determined that it is a communication device for which the server function is to be enabled, and if another communication device having the server function is found, it is a communication for which the server function is to be disabled. Judged to be a device.

  With this configuration, the server function of the device positioned at the highest level among the communication devices having the server function can be validated at all times, so that the connectivity between the device having the server function and other communication devices can be improved. In addition, if there is a communication device having a server function that enables the server function in the network to which it belongs and the peer network, it is possible to maintain the service provision without interruption by not replacing it. .

  A communication device according to a sixth aspect of the present invention is the communication device having the server function according to the first aspect, wherein the server function switching means is configured such that when the server function is switched from being enabled to being disabled, Information of another communication device whose server function is changed is transmitted to the communication device providing the service.

  With this configuration, each communication device provided with a service can reconnect the session instantaneously without searching for the device on the network to the communication device that newly activates the server function. It is possible to reduce the possibility of interruption of service reception by changing the communication device to be activated.

  A communication device according to a seventh aspect of the present invention is the communication device having the server function according to the first aspect, wherein the server function switching means replaces the server function when invalidating its own server function. The information of the communication device that is providing the service is transmitted to the other communication device.

  With this configuration, if the communication device that provided the service cannot detect that the server function has changed and the service cannot be received, the service is provided from the communication device that has enabled the replaced server function. It is possible to try to provide services to the communication apparatus.

  A communication apparatus according to an eighth aspect of the present invention is the communication apparatus having the server function according to the first aspect, wherein the server function switching means should enable the server function by itself. When it is determined that the server is a communication device, a server function switching message for instructing the server function to be invalidated is transmitted to another communication device having the server function discovered by the server function discovery means, and the server function is activated. If the server function is not enabled, the server function is enabled. If the server function appropriateness determining means determines that the server function is a communication device that should disable the server function, the server function is enabled. A server function switching message instructing the activation of the server function is transmitted to another communication device having the server function discovered by the function discovery means, and its own server To disable the function.

  With this configuration, it is possible not only to switch the validity / invalidity of the server function by itself, but also to instruct other communication apparatuses with a server function to switch the validity / invalidity of the server function.

  A communication device according to claim 9 of the present invention is the communication device having the server function according to claim 1, wherein a plurality of different routers are connected in parallel below the router to which the communication device having the server function belongs. Lower subnetwork presence determination means for determining whether or not the lower subnetwork presence determination means uses a network configuration change notification message received from another communication device or from another communication device in the local network. The information contained in the received packet is used to determine that a plurality of different routers are connected in parallel below the router to which the communication device having the server function belongs. The communication device that validates the server function is determined based on the result of the determination means.

  With this configuration, it is possible to avoid the communication disabled state by replacing the communication device with the server function enabled only when the communication disabled state occurs, and each communication device provided with the service functions as a server function. It is possible to reduce the number of times of re-establishing a session with a communication apparatus that has enabled the server, and it is also possible to cope with a case where it is not desired to change the communication apparatus in which the server function is enabled as much as possible.

  A communication device according to a tenth aspect of the present invention is the communication device having the server function according to the ninth aspect, wherein a packet received from another communication device in the local network includes other communication in the local network. Information that can identify the router to which the device is connected is included, and the sub-network existence determination means compares at least information that can identify the router included in a packet received from another communication device in the local network. Then, it is determined that a plurality of different routers are connected in parallel below the router to which the communication device having the server function belongs.

  With this configuration, the communication device itself having the server function can determine that a plurality of different routers are connected in parallel below the router to which the communication device belongs.

  A communication apparatus according to an eleventh aspect of the present invention is the communication apparatus having the server function according to the tenth aspect, wherein the lower-layer sub-network existence determining means is identification information of a router to which the communication apparatus having the server function is connected. The router to which the communication device having the server function belongs is received when a plurality of packets including identification information of different routers are received and the source address included in the IP header of the received packet including identification information of the different routers is not the same Is determined that a plurality of different routers are connected in parallel.

  With this configuration, the communication device itself having the server function can reliably determine that a plurality of different routers are connected in parallel below the router to which the communication device belongs.

  A communication apparatus according to a twelfth aspect of the present invention is a communication apparatus having the server function according to the ninth aspect, wherein the server function appropriateness determining means is configured so that the server function finding means is in a local network connected to an external network. If no other communication device having the server function is found, the device determines that it is a communication device to enable the server function, and if it finds another communication device having the server function, It is determined that the communication device is to disable the function.

  With this configuration, as long as each communication device has a network configuration that can receive a service, it is possible not to change the communication device that validates the server function.

  According to a thirteenth aspect of the present invention, there is provided a communication apparatus having the server function according to the ninth aspect, wherein the server function appropriateness determining means is a router to which the server function finding means belongs and the communication apparatus having the server function belongs. The lower sub-network existence determination means has found a plurality of different routers below the router to which the communication device having the server function belongs. Are determined to be connected in parallel, it is determined that the communication device that activates the server function should be changed.

  With this configuration, only when each communication device is changed to a network configuration that cannot receive a service, it is possible to change the server function to a communication device having a server function that allows each communication device to receive a service. .

  In a communication device according to a fourteenth aspect of the present invention, in a local network connected to an external network, one or more routers exist between the communication device in the local network and the external network. It is divided into one or more different sub-networks by one or more routers, is connected to any router in the local network, and has a server function in the local network and performs message communication with other communication devices. One or more of the routers located between the router to which the communication device having the server function is connected and the external network are set as communication devices connected to the LAN side network. Obtain and store information about the range of possible addresses Subnetwork presence determination means and lower subnetwork presence determination means for determining that a plurality of different routers are connected in parallel below the router to which the communication device belongs are received from other communication devices in the local network The packet includes information capable of identifying a router to which another communication device in the local network is connected, and the lower subnetwork existence determination means includes at least a packet received from another communication device in the local network. By comparing information that can identify the routers included, it is determined that a plurality of different routers are connected in parallel below the router to which the communication device belongs.

  With this configuration, it is possible to determine that a plurality of different routers are connected in parallel below the router to which the communication device having no server function belongs.

  A communication device according to claim 15 of the present invention is the communication device according to claim 14, wherein the lower subnetwork existence determination means is a router different from the identification information of the router to which the communication device having a server function is connected. When a plurality of packets including identification information are received and the source address included in the IP header of the received packet including the identification information of the different router is not the same, a plurality of different routers are located below the router to which the communication device belongs. Determine that they are connected in parallel.

  With this configuration, it is possible for a communication device itself having no server function to determine that a plurality of different routers are connected in parallel below the router to which the communication device belongs.

  The communication device according to claim 16 of the present invention is the communication device according to claim 14, wherein the lower subnetwork existence determination means includes a plurality of different routers connected in parallel below the router to which the communication device belongs. When it is determined that there is a router connected to the communication device or the communication device is connected using information on one or more address ranges of the first network stored by the upper subnetwork presence determination means A network configuration change notification message is transmitted to a network belonging to another router (upper router) existing between the router and the external network.

  With this configuration, it is possible to notify other communication apparatuses existing in the upper subnetwork that a plurality of different routers are connected in parallel in a network lower than the network.

  In the server function switching method according to claim 17 of the present invention, in a local network connected to an external network, one or more routers exist between the communication device in the local network and the external network. A function (server function) that is divided into one or more different sub-networks by the one or more routers, is connected to any router of the local network, and provides services to other communication devices in the local network A method of replacing a communication device having a step of discovering another communication device having a server function existing in a local network, a step of determining a communication device in which the server function is to be enabled, And a step of switching invalidity.

  With this configuration, when there are a plurality of communication devices having a server function on the network, it is possible to replace the communication device that supplies the service with a more optimal communication device.

  In the communication system according to claim 18 of the present invention, in a local network connected to an external network, one or more routers exist between the communication device in the local network and the external network, and the local network is the 1 Communication divided into one or more different sub-networks by one or more routers, connected to any router in the local network, and having a function (server function) for providing services to other communication devices in the local network A communication device connected to one of the routers of the local network and having a server function in the local network, and a communication device that performs message communication with another communication device, the communication device having a server function, Server machine in the local network To discover other communication devices having comprising a server discovery unit, a server proper determination unit that determines a communication device to enable a server function, a server function switching unit for switching the valid and invalid server functions.

  With this configuration, when there are a plurality of communication devices having a server function on the network, it is possible to replace the communication device that supplies the service with a more optimal communication device.

  According to the communication device of the present invention, it is possible to improve connectivity between devices without depending on the network configuration by replacing the communication device that supplies the service when the network configuration changes with a more optimal communication device. it can.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
[Applicable environment for server replacement method]
FIG. 1 is a configuration example of a home network according to Embodiment 1 of the present invention.

  The home network 2 is configured by connecting three routers 3 a to 3 c, and the router 3 a is the highest router connected to the Internet 1. Each router is connected to communication devices 4a to 4c with server function having a server function and communication devices 5a to 5c not having a server function. The configuration of the home network 2 may be wired or wireless. Each of the communication devices 4a to 4c and 5a to 5c can communicate through a network. Further, the communication device with a server function has a function of providing a service possessed by itself to a user or another communication device. As an example of a communication device with a server function, a network-compatible AV recorder that transmits content list information in response to a request from another communication device, or transmits the content of a content requested from another communication device. Also, a relay device that relays a request or response from a communication device to another communication device can be considered. Note that the AV recorder and the relay device described here are examples of communication devices and are not limited thereto. The configuration of a home network composed of three routers is an example, and the present invention can be similarly applied to a network composed of fewer than three routers or a network composed of three or more routers.

  Here, in the present embodiment, the server functions of the server-equipped communication devices 4a to 4c are communication that establishes a communication path with other communication devices and relays messages to connect to different routers. A relay function that enables message communication between devices will be described. Therefore, in this embodiment, after a message is once transmitted / received to / from a communication device with a server function in which the server function is enabled, the communication device and the communication device with a server function maintain a communication path. It is possible to communicate with other communication devices beyond the router via the communication device with a server function.

  FIG. 3 shows an example of a basic hardware configuration of the communication device according to Embodiment 1 of the present invention. The communication device includes a main CPU, ROM, RAM, user I / O, and network I / F. The main CPU performs processing related to a communication service for transmitting / receiving data to / from another communication device and an application service in which the communication device provides a service unique to the communication device to a user or another communication device. When the main CPU performs processing, data and programs are read from the ROM and RAM and written to the RAM. At this time, input from the user, display of information on the service, and the like are executed through the user I / O. In addition, data is exchanged with communication devices and routers in the home network through the network I / F.

  The application service described here corresponds to a service such as provision of content list information and transmission of content data in the example of the AV recorder described above. The communication service corresponds to communication control for exchanging information with the communication device of the communication partner.

[Functional configuration of communication equipment with server function]
FIG. 4 is a functional block diagram showing the configuration of the communication device 4a with a server function in the first embodiment of the present invention. In addition, the other communication apparatus with a server function in this Embodiment shall also have the same structure.

  In FIG. 4, the communication device with server function 4a includes a communication I / F unit 400, a higher-level subnetwork determination unit 401, a storage unit 402, a server function search / response unit 403, a server suitability determination unit 404, and a server function. A switching unit 405 and a server function unit / client function unit 406 are provided.

[Communication I / F part]
The communication I / F unit 400 controls the network I / F, and receives information from the network and transmits information to the network.

  In addition, the communication I / F unit 400 manages its own address information used for communication, and can be actually set on the network to make it easier to find communication devices with the server function enabled from communication devices under the lower router. Of these addresses, an address resetting process for setting an address within a predetermined address range may be executed. As an example of information managed as address information at this time, an own IP address, a netmask, a default gateway address, or the like can be considered.

[High-level subnetwork judgment unit]
The upper subnetwork determination unit 401 performs upper subnetwork analysis (described later), and acquires network information under the router connected to the higher level (Internet side) of the router to which the higher level subnetwork is determined. For example, the upper sub-network determining unit of the server-equipped communication device 4b connected to the router 3b in FIG. 1 acquires network information under the router 3a. When the upper subnetwork analysis is simply described, the LAN address of the upper router is obtained using trace route, or the WAN address of the router to which the router is connected is obtained using UPnP IGD, and the obtained address is This is a process of inferring an address that can be set for a communication device connected to the upper router by specifying the network address of the upper subnetwork.

  The upper subnetwork determining unit 401 stores the upper subnetwork information acquired by the upper subnetwork analysis in the storage unit 402. An example of the upper subnetwork information is network address information of the upper subnetwork. That is, when the network address under the router 3a is 192.168.1.0/24, the upper subnetwork information of the communication device 4b with a server function connected to the router 3b is 192.168.1.0. / 24 is stored. Here, 192.168.1.0 indicates a network address, and / 24 indicates the number of bits of the netmask. Similarly, when the network address under the router 3b is 192.168.2.0/24, the upper subnetwork information of the communication device 4c with a server function connected to the router 3c is 192.168.1.0. / 24 and 192.168.2.0/24 are stored as two network addresses. If the network address is known, the possible values of the host address can be easily inferred, so that it is possible to easily identify an address that may be set in a communication device connected to the network.

[Storage unit]
The storage unit 402 stores higher-level subnetwork information, router identification information, communication partner communication device information, information about a communication device with a server function that currently enables the server function, and the like.

[Server function search / response section]
The server function search / response unit 403 uses the upper subnetwork information stored in the storage unit 402 to check whether a “communication device having a valid server function” is connected to the network belonging to the upper router. Processing to search, processing to search for “communication equipment with server function enabled” connected to the network belonging to the peer router, and other communication when its own server function is enabled This is a function that provides a function of returning a response to a server function search request received from a device. At this time, when another communication device in which the server function is valid is found by the search processing, the server appropriateness determination unit 404 is notified to that effect, and information of the found communication device is notified to the server function switching unit 405. To do. If no other communication device in which the server function is valid can be found by the search, the server appropriateness determination unit 404 is notified accordingly. The server function search / response unit 403 always waits for reception of a server function search request from another communication device. When a server function search request is received from another communication device, a response to the server function search request is transmitted if the server function is valid.

[Server suitability determination section]
The server suitability determination unit 404 is a function unit that determines a communication device whose server function should be validated. When the server suitability determination unit 404 receives a notification from the server function search / response unit 403 that a communication device in which the server function is enabled by discovery is found, the server function is enabled in the upper subnetwork or peer network. It is determined that there is a communication device. Further, upon receiving a notification that a communication device with the server function enabled cannot be found by the search, it is determined that there is no communication device with the server function enabled in the upper subnetwork or peer network. This is because the NAPT function and firewall function of the home router are obstructed, and communication cannot be started from a communication device located on the WAN side to a communication device located on the LAN side. This is because the communicable communication device can be determined to be a communication device existing in the same network as itself or a communication device located on the WAN side with respect to itself. Therefore, when a communication device having an effective server function is found by searching, it can be determined that the found device exists in the upper subnetwork or the peer network. In addition, the problem that communication cannot be established from a communication device located on the WAN side and communication with a communication device located on the LAN side cannot be communicated from the communication device located on the LAN side to the communication device located on the WAN side. It can be avoided by starting. In other words, by installing a communication device with the server function enabled in the highest-level subnetwork, each communication device is positioned on the LAN side with respect to the communication device with the server function enabled. It becomes possible to communicate as. Therefore, when the server function search / response unit 403 receives a notification indicating that a communication device for which the server function is enabled by discovery is found, the discovered communication device exists in the upper subnetwork or peer network, so It is determined that the communication device is to disable the function, and the determination result is notified to the server function switching unit 405. On the other hand, when receiving a notification that the communication function with the server function enabled cannot be found by the search, the communication function with the server function does not exist on the network or exists in the lower subnetwork, so Is determined to be a communication device to be enabled, and the determination result is notified to the server function switching unit 405.

[Server function switching section]
The server function switching unit 405 is a function unit that switches the function of the server function unit / client function unit 406 in response to an instruction to switch the server function. The server function switching instruction includes a server function switching message from another communication device with a server function and a determination result from the server suitability determination unit 404. When the server function is to be validated, the server function switching unit 405 validates the server function unit of the server function unit / client function unit 406 and invalidates the client function unit. On the other hand, when disabling the server function, the server function unit of the server function unit / client function unit 406 is disabled and the client function unit is enabled. In the initial state of the present embodiment, it is assumed that the server function unit / server function unit 406 of the server function unit / client function unit 406 is disabled and the client function unit is enabled.

  In addition, when switching the server function from the valid state to the invalid state, before switching, the communication device with the server function is notified to the communication device providing the service, and the server function is valid. Is stored in the storage unit 402 as information on the communication device. When the server function is switched from the invalid state to the valid state, the information on the server function after the activation is stored in the storage unit 402 as information on the communication device in which the server function is valid. The information on the communication device with the server function to be replaced is notified from the server function search / response unit 403 or is acquired from the server function switching message from another communication device with the server function.

  In addition, when switching the server function based on the determination result from the server suitability determination unit 404, the server function switching message indicates the determination result instruction from the server suitability determination unit 404 to the communication device with server function discovered before switching the server function. Notify as.

[Server Function / Client Function]
The server function unit / client function unit 406 includes a server function that provides a service to another communication device, and a client function unit that communicates (receives a service) with a communication device in which the server function is enabled. Control is performed by the server function switching unit 405 so that when one function is valid, the other function is invalidated.

  When functioning as a server function unit, communication is performed using information of other communication devices stored in the storage unit 402. When functioning as a client function unit, the server function stored in the storage unit 402 is Communication with the communication device is performed using information of the communication device that is enabled.

[Overview of operation of communication equipment with server function]
An outline of the operation of the server-equipped communication devices 4 a to 4 c configured as described above will be described with reference to FIGS. 6, 7, 8, 9, and 10.

  FIG. 6 is an overall processing flow of the communication device with a server function in the embodiment of the present invention.

  When the communication device with a server function receives a message (Yes in step S600), the communication device search processing with a server function (step S603) is executed (step S601).

[Communication device search processing with server function]
FIG. 7 is a processing flow of the communication device searching process with a server function (step S603) of the communication apparatus with a server function according to the first embodiment of the present invention.

  First, the upper subnetwork determining unit 401 performs upper subnetwork analysis (step S700, details will be described later), and the network address under the router connected to the higher level (Internet side) of the router to which it is connected is determined. Information (upper subnetwork information) is acquired and stored in the storage unit 402. Then, the server function search / response unit 403 uses the upper subnetwork information to estimate the address of the “communication device in which the server function is valid” connected to each upper router, and unicasts the server function search request. (Step S701). At the same time, a server function search request is multicast or broadcasted within the network under the router to which it belongs (step S701). If the presence of the upper router is not detected in the upper subnetwork analysis, a server function search request is transmitted by multicast or broadcast only within the router to which it belongs (step S701).

  For example, the communication device 4c with a server function connected to the router 3c in FIG. 1 is based on the network address information of the router 3a and the router 3b, and the “server function connected to the router 3a and the router 3b is effective. The device address is estimated and a server function search request is unicasted. In addition, in the process of estimating the address of the “communication device in which the server function is effective”, the “communication device in which the server function is effective” is controlled to take a specific address range (address reset processing is performed). In the case of execution), a server function search request is transmitted only to candidate addresses. With this processing, it is necessary to send a server function search request to all valid host addresses of the router 3a and the router 3c (for example, 192.168.x.1 to 192.168.x.254 in the case of a class C private address). Therefore, it is only necessary to send a server function search request to a predetermined address range. As a result, the processing speed can be increased and communication traffic can be reduced.

  FIG. 12 shows an example of a server function search request. In the server function search request, an ID indicating that this message is a server function search request is set in the message ID field in the body. Also, an ID unique to the transmission source communication device is set as the transmission source ID. Information indicating whether the communication device that is the server function search request transmission source has the server function may be included in the ID unique to the communication device, or another field may be prepared.

  When the server function communication device connected to the upper router receives the server function search request, the server function search / response unit 403 sends the server function search response to the server function search request only when its server function is valid. To the source address (IP address, port number). An example of the format of the server function search response is the same as the server function search request. However, an ID value indicating a server function search response is set as the message ID.

  Here, in general, when a router starts communication from a device connected to the LAN side network to a device connected to the WAN side network, address conversion setting (NAPT setting) is automatically executed and connected to the WAN side network. Sent to the connected device. Therefore, a device connected to the WAN side network can communicate with a device connected to the LAN side network by transmitting the packet to the source address (IP address, port number) of the received packet. For this reason, by transmitting the server function search request packet as described above to the communication device connected to the upper router, the “communication device having an effective server function” connected to the upper router is transmitted. A response can be received, and as a result, a “communication device in which the server function is effective” can be found.

  Next, it is determined whether the server function search / response unit 403 has received the server function search response (step S702).

  If the server function search response has not been received (No in step S702), the server suitability determination unit 404 does not have a communication device in which the server function is valid in the higher-level subnetwork or peer network. It is determined that the communication device is to be validated (step S703). Thereafter, it is determined whether or not the server function is already valid (step S704). If it is already valid (Yes in step S704), the process is terminated, and if the server function is not valid (No in step S704), the server The function switching unit 405 performs server function switching processing based on appropriateness determination (step S705).

  On the other hand, if the server function search response is received (Yes in step S702), the server suitability determination unit 404 finds that the communication device for which the found server function is valid exists in the upper subnetwork or the peer network, so that the server function itself Is determined to be a communication device to be invalidated (step S706). Thereafter, it is determined whether or not the server function is already valid (step S707). If the server function is not valid (No in step S707), the process is terminated, and if it is valid (Yes in step S707), the server function is switched. The server function switching process based on appropriateness determination is performed in the unit 405 (step S705).

[Message reception processing]
FIG. 8 is a processing flow of message reception processing (step S601) of the communication device with server function according to the first embodiment of the present invention.

  The server function search / response unit 403 of the communication device with server function 4a always receives the server function search request from the communication device connected to the lower router (step S800), and the server function from the communication device with server function. Waiting for reception of a switching message (step S803). When a server function search request is received from a communication device connected to a lower router (Yes in step S800), it is determined whether or not its own server function is valid (step S801), and if it is valid (step S801). Yes) A server function search request response is transmitted (step S802). If the server function is not valid (No in step S801), the process is terminated.

  On the other hand, when the received message is not a server function search request from another communication device with a server function (No in step S800) but a server function switching message (Yes in step S808), the server function switching unit 405 sends a message A server switching process by reception is performed (step S804), and the process ends.

  If neither a server function search request nor a server function switching message is received (No in step S800 and No in step S803), other message reception processing is performed (step S805), and the processing is terminated.

[Server function switching processing by message reception]
FIG. 9 is a diagram showing server function switching processing by message reception in step S804 of FIG.

  If a server function switching message for instructing activation of the server function is received from another communication device with a server function as a trigger for the server function switching process (Yes in step S900), whether or not the server function is enabled Is determined (step S902). If enabled (Yes in step S902), the process is terminated without doing anything, and if the server function is not enabled (No in step S902), the client function unit of the server function unit / client function unit 406 The server function unit is invalidated (step S903), and the process is terminated. On the other hand, if a server function switching message for instructing the server function to be disabled is received from another communication device with a server function (No in step S900 and Yes in step S901), is the server function enabled? It is determined whether or not (step S904). If it has not been activated (No in step S904), the process is terminated without doing anything, and if its own server function has been activated (Yes in step S904), the server is provided to the communication device that provides the service itself. Information on other communication devices whose functions are changed is transmitted (step S905), the server function unit of the server function unit / client function unit 406 is invalidated and the client function unit is validated (step S906), and the process is terminated.

[Server function switching processing based on suitability judgment]
FIG. 10 is a diagram showing server function switching processing based on suitability determination in step S705 of FIG.

  As a trigger for the server function switching process, when receiving a determination notification indicating that the server function is to be enabled by the server suitability determination unit 404 (Yes in step S1000), the server function communication device with the server function discovered by the search is sent to the server. A server function switching message for instructing the function invalidation is transmitted (step S1005), the client function unit of the server function unit / client function unit 406 is invalidated and the server function unit is validated (step S1006), and the process is terminated. . When the server appropriateness determination unit 404 receives a determination notification indicating that it is a communication device whose server function should be disabled (No in step S1000, Yes in step S1001), the server function is enabled for the communication device with the server function found by the search. The server function switching message for instructing to be transmitted is transmitted (step S1002), the information of the communication device with other server function that replaces the server function is transmitted to the communication device that provides the service (step S1003), and the server The server function unit of the function unit / client function unit 406 is invalidated and the client function unit is validated (step S1004), and the process ends.

[Upper subnetwork analysis processing]
Next, upper subnetwork analysis processing executed by the communication device will be described.

  The upper sub-network analysis process is a process executed by each communication device including “communication device in which the server function is valid”. The network under the router to which it is connected and its upper side (that is, the Internet) This is a process of acquiring the network address of the network under the router on the side). First, network address information of a network under a router to which it is connected is acquired from the communication I / F unit 400.

  As an example of processing for acquiring the network address of the upper router, the same method as in Japanese Patent Application No. 2005-103059 can be used. Here, the outline will be described.

  The upper subnetwork analysis process consists of two steps. The first step is a step of acquiring the address of the upper router in the home network in order to acquire the network address information of the upper router. The next step is a step of acquiring the network address of the router (or a range of addresses effective in the network) using the acquired address of the router.

  Here, a network address of a router (or a range of addresses effective in the network) is referred to as an address space of the network. In addition, a process for estimating the address space of the network using the address information of the router is referred to as an address space estimation process.

  As a method of acquiring the address of the upper router in the home network, a method of acquiring an address using a packet in which TTL (Time To Live) is changed (a method similar to trace route), UPnP (Universal Plug and Play) A method of acquiring an address using an IGD (Internet Gateway Device) specification can be used.

(Method of using packet with changed TTL)
First, a method of acquiring a router address using a packet whose TTL has been changed will be described. FIG. 27 is a configuration example of a home network. In FIG. 27, two different networks, the home network 2 and the Internet 1, are connected. The home network 2 may not be a home network as long as it is a local network. As shown in FIG. 27, the home network 2 includes a communication device 10, a router A20, a router B30, and a router C40. The router A20 includes a WAN side communication I / F 2721 and a LAN side communication I / F 2722. The router B30 includes a WAN side communication I / F 2731 and a LAN side communication I / F 2732. The router C40 includes a WAN side communication I / F 2741 and a LAN side communication I / F 2742. Note that in the router A20, the router B30, and the router C40, descriptions of configurations other than the WAN side communication I / F and the LAN side communication I / F are omitted.

  The router C40 is a gateway that connects the home network 2 and the Internet 1 by connecting to the router D50 of the Internet 1. In the router C40, a global address is allocated to the WAN side communication I / F 2741, and a private address is allocated to the LAN side I / F 2742. Private addresses are assigned to the WAN side communication I / F 2721 and the LAN side communication I / F 2722 of the router A20, and the WAN side communication I / F 2731 and the LAN side communication I / F 2732 of the router B30, respectively.

  FIG. 28 is a flowchart showing a process performed by the communication device 10 to acquire a network address of a router (or a range of valid addresses that can be taken by a terminal under the router) using a packet whose TTL has been changed. It is. When starting the upper subnetwork analysis process, the communication device 10 activates the TTL packet transmission process (step S101). Here, the activated TTL packet transmission processing is executed in parallel with the TTL response packet reception processing (step S102). After starting the TTL packet transmission process, the communication device 10 determines whether or not a TTL response packet has been received (step S102). When receiving the TTL response packet (Yes in step S102), the communication device 10 determines that a router has been detected, and executes a TTL response packet reception process (step S103). More specifically, the TTL response packet is ICMP (Internet Control Message Protocol) TIME EXCEEDED MESSAGE. The ICMP TIME EXCEEDED MESSAGE is a message that reports to the transmission source that the packet is discarded due to the surviving time (TTL: Time To Live) of the packet to be relayed.

  The communication device 10 determines whether or not the transmission source address of the TTL response packet is a global address (step S104). When the transmission source address of the TTL response packet is not a global address (No in step S104), the first communication device 10 executes an address space estimation process (step S105). When the transmission source address of the TTL response packet is a global address (Yes in step S104), the first communication device 10 stops the TTL packet transmission process (step S107).

  The communication device 10 determines whether or not all TTL response packets for the transmitted TTL packet have been received (step S108). If all have been received (Yes in step S108), the first communication device 10 ends the address space estimation processing shown in FIG. If not all have been received (No in step S108), the first communication device 10 returns to step S102 and enters a TTL response packet reception standby state. The reason for continuing the reception process until all the TTL response packets for the transmitted TTL packet are received is that the TTL response packets are not necessarily received in the order in which the TTL packets are transmitted. In the TTL packet corresponding to the TTL response packet whose source address is the global address, if the set TTL value is TTLg, the TTL response is received when all the TTL response packets for the TTL packet having a TTL value equal to or less than TTLg are received. It may be determined that all packets have been received.

  Details of the TTL packet transmission processing will be described with reference to FIGS. FIG. 29 is a flowchart of TTL packet transmission processing. FIG. 30 is a diagram illustrating a configuration of a TTL packet when UDP (User Datagram Protocol) is used for transmission of the TTL packet. FIG. 31 is a diagram illustrating an example of a correspondence relationship between a TTL and a destination port number in a TTL packet.

  The TTL packet transmission process will be described with reference to FIG. The communication device 10 confirms whether or not to continue the creation of the TTL packet (step S111). The determination as to whether or not the TTL packet creation is continued is made based on whether or not the transmission source has received a response packet of the global address in the reception of a TTL packet response described later. If the response of the global address is received, it is determined that the packet continuation is to be stopped (No in step S111), and if the response of the global address is not received, it is determined to continue (Yes in step S111).

  When it is determined that the TTL packet creation is to be stopped, the TTL packet transmission process is terminated. If it is determined that the TTL packet creation is to be continued, a TTL packet is created by incrementing the TTL and the destination port number by one (step S112). The upper subnetwork determining unit 401 transmits the created TTL packet via the communication I / F unit 400 (step S113). Note that the upper subnetwork determining unit 401 may transmit the next TTL packet incremented by TTL without waiting for the reception of the TTL response packet corresponding to the transmitted TTL packet. In this case, since the communication device 10 can transmit a plurality of TTL packets at the same time, the router can be detected at high speed. The TTL packet may be transmitted to a specific global address on the Internet (for example, the LAN side I / F 501 of the router D50 or a specific server address on the Internet (for example, panasonic.com)). .

  As shown in FIG. 31, the upper subnetwork determining unit 401 creates a TTL packet while incrementing the value of the TTL field of the IP header from 1 and incrementing the destination port number field of the UDP header from 10001. The destination port number is not limited to the example shown in FIG. 31, and may be another port number. The destination port number only needs to be able to uniquely determine the TTL from the destination port number.

  Further, the TTL packet is not limited to the example using UDP as shown in FIG. 30, and for example, ICMP shown in FIG. 32 may be used. In this case, as shown in FIG. 33, a method of associating the TTL of the IP header with the sequence number can be used.

  TTL response packet reception processing will be described with reference to FIGS. FIG. 27 shows the correspondence between TTL packets and TTL response packets. FIG. 34 is a diagram illustrating an example of a TTL response packet.

  In FIG. 27, a router A20, a router B30, a router C40, and a router D50 transmit the TTL packet received by each LAN side communication I / F to the WAN side router by subtracting the TTL value by one. Each router decrements the TTL value by 1 and discards the TTL packet without transmitting it to the router on the WAN side when TTL = 0. Then, each router transmits a TTL response packet to the transmission source of the TTL packet to indicate that the packet discard due to the TTL value has occurred. In the data portion of the TTL response packet shown in FIG. 34, 64-bit data including the discarded router discovery packet IP header and the subsequent UDP header is added.

  Consider a case in which the communication device 10 transmits a TTL packet set to TTL = 1 toward a specific IP address on the Internet 1. The TTL packet with TTL = 1 is received by the LAN side I / F 2722 of the router A20. The TTL packet set to TTL = 1 is set to TTL = 0 before being transmitted from the WAN I / F 2721. Therefore, the router A20 discards the TTL packet with TTL = 1. The router A 20 transmits a TTL response packet to the first communication device 10 in order to notify that the TTL packet with TTL = 1 has been discarded. At this time, the transmission source IP address of the TTL response packet (hereinafter referred to as the transmission source address) is the IP address of the LAN side communication I / F 2722 of the router A20 (hereinafter, the IP address of the LAN side communication I / F of each router). Is referred to as the LAN address of each router). The first communication device 10 can know the LAN address of the router A20 by confirming the transmission source address of the TTL response packet.

  Similarly, when the first communication device 10 transmits a TTL packet set to TTL = 2 toward a specific IP address on the Internet, the router B30 uses the LAN address of the router B30 itself as the source address. The transmitted TTL response packet is transmitted to the communication device 10. Also, when the communication device 10 transmits a TTL packet set to TTL = 3 toward a specific IP address on the Internet, the router C40 uses a TTL response packet with the LAN side address of the router C40 itself as the transmission source address. Is transmitted to the communication device 10. In this way, the communication device 10 can detect each router and obtain the LAN side address of each router by receiving the TTL response packet corresponding to the TTL packet. The first communication device 10 can acquire connection order information related to the connection order of routers connected between itself and the Internet 1.

  Next, address space estimation processing performed by the communication device 10 will be described. The address space estimation process described here is a process for estimating a range of addresses that can be set in a terminal connected to a network under a router. Since the address range that can be set in the terminal corresponds to the host address range, the network address can be obtained from this range.

  When the transmission source address of the TTL response packet is a local address, the communication device 10 transmits the transmission using the TTL value specified by the TTL packet corresponding to the TTL response packet, targeting the transmission source router of the TTL response packet. An address range estimation packet in which the destination address is changed is transmitted. For example, the router A20 uses a TTL value of 1, and the router B30 uses a TTL value of 2.

  Also, the communication device 10 primarily estimates and stores the address space of the router based on the LAN address of the router obtained from the TTL response packet. As a specific method of the primary estimation of the address space, a method of estimating the address space as a class C address can be considered. For example, if the LAN address of the router A20 is 192.168.0.1, the address space of the router A20 can be estimated as 192.168.0.1 to 192.168.0.254. When the obtained router's LAN address is a class A or class B private address, it may be presumed that the obtained router's address space is an address space corresponding to each class. . For example, when the private address of the router A 20 is 10.1.0.130, the router presumes that the address space of the router is 10.0.0.1-10.255.255.254. Also, 10.1.0.1-10.0.2554 (only the least significant 8 bits are changed) or 10.1.0.129 to 10.1.0.254 (only the least significant 7 bits are changed) ) Or the like.

  When the communication device 10 primarily estimates the address space, the communication device 10 primarily stores and stores the obtained router address space so that the LAN address of the obtained router is included. Then, the upper subnetwork determining unit 401 sequentially designates the addresses in the stored address space as a transmission destination, and transmits an address range estimation packet. At this time, it can be considered that the obtained LAN address of the router is always included in the primary estimated address space, so the communication device 10 transmits an address range estimation packet to the obtained router LAN address. You don't have to.

  The address range estimation packet is a packet for confirming whether or not the address space estimated by the communication device 10 as the address space of the target router is the address space of the target router. As the address range estimation packet, the UDP packet shown in FIG. 30 or the ICMP packet shown in FIG. 32 is used. The difference between the TTL packet and the address range estimation packet is that the destination address of the TTL packet is a specific address on the Internet, whereas the destination address of the address range estimation packet is different from the address space of the target router. This is a possible local address.

  Further, in the communication I / F unit 400, the communication device 10 uses the UDP packet shown in FIG. 30 so that the TTL response packet and the ICMP TIME EXCEEDED MESSAGE that is the response of the address range estimation packet can be identified. The UDP packet specifying the port number not used in the TTL packet is transmitted as an address range estimation packet. As a result, the port number specified by the address range estimation packet is included in the data portion of ICMP TIME EXCEEDED MESSAGE which is a response to the address range estimation packet. In this way, the communication device 10 can identify the TTL response packet and the ICMP TIME EXCEEDED MESSAGE that is a response to the address range estimation packet by referring to the port number. Similarly, when ICMP is used as the address range estimation packet, a value not used in the TTL packet is set for the sequence number and the like. A router address space estimation method using the address range estimation packet response will be described later.

  When there is a response to the address range estimation packet, the communication device 10 determines whether the response is ICMP TIME EXCEEDED MESSAGE. If the response is not ICMP TIME EXCEEDED MESSAGE, it is determined that the destination address of the address range estimation packet is within the address space of the router. Then, the communication device 10 updates and stores the estimated address space information of the router based on the determination result.

  The reason why the destination of the address range estimation packet can be determined as an address outside the range of the router address space by receiving ICMP TIME EXCEEDED MESSAGE as a response to the address range estimation packet will be described. The address range estimation packet is transmitted by designating the same TTL value as the TTL packet transmitted to acquire the router's LAN address (for example, when estimating the address space of the router A20, the TTL value is 1). It is specified). When a packet is transmitted by specifying an address outside the range of the router address space, the router attempts to transmit the packet to the upper router. At this time, since the TTL value is subtracted and TTL = 0, the router discards the address range estimation packet and transmits ICMP TIME EXCEEDED MESSAGE. Therefore, when ICMP TIME EXCEEDED MESSAGE is received as a response to the address range estimation packet, it is understood that the transmission destination address of the address range estimation packet is outside the range of the router address space.

  Even if there is no response to the address range estimation packet, the communication device 10 may determine that the destination address of the address range estimation packet is within the address space of the target router. When the response is ICMP TIME EXCEEDED MESSAGE, the communication device 10 determines that the transmission destination address of the address range estimation packet is outside the address space of the router. And the communication apparatus 10 updates and memorize | stores the estimated information of the LAN side address space of a router based on the determination result. Thereafter, the communication device 10 determines whether or not the estimation of the address space has been completed. Specifically, the address space confirms whether or not all of the transmission of the address range estimation packet and the response to the address range estimation packet have been received. If not completed, the upper subnetwork determining unit continues the process. When it is determined that the communication has ended, the communication device ends the address space estimation process, that is, ends the upper subnetwork analysis.

  Note that the communication device 10 may end the address space estimation process when detecting an address at a boundary between an address determined to be within the address space and an address determined to be outside the address space. This is because the address space of the router is generally composed of continuous addresses. For example, when the communication device 10 transmits an address range estimation packet as a transmission destination in order from 192.268.2.2 (192.168.2.3, 192.168.2.4, ...) (192) .168.2.1 is the address of the router and is not transmitted because it is always known to be in the address space.) The case where it is first determined that the address space is out of range in 192.168.2.128 will be explained. . In this case, if the address space is continuous, it can be predicted that all addresses after 192.168.2.128 are determined to be outside the range of the address space. For this reason, when the communication device 10 determines that 192.168.2.128 is out of the range of the address space, the communication device 10 does not transmit the address range estimation packet to the address of the entire address space that is actually primarily estimated, The determination process may be terminated. At this time, the router address space information stored in the communication device 10 is updated based on the determination result.

(Method using UPnP IGD specification)
Next, a method for acquiring a router address using the UPnP IGD specification will be described.

  Note that, after obtaining the router address, the process of estimating the range of the address space is the same as the method of using the packet with the TTL changed.

  In the method of using the packet with the TTL changed, the router existing in the home network 2 is detected using the TTL packet with the TTL changed and the TTL response packet using the ICMP TIME EXCEEDED MESSAGE. However, routers that do not perform TTL processing, routers that filter ICMP packets, and the like are commercially available. For this reason, there is a router to which the upper subnetwork analysis process described in the method of using a packet with TTL changed cannot be applied. In the method using the UPnP IGD specification, an upper subnetwork analysis process for solving this problem will be described.

  FIG. 35 is a diagram illustrating an example of a network in which the upper subnetwork analysis process using the UPnP IGD specification is used. In FIG. 35, the home network 2 is different from the communication device 10 in that a second communication device 11 is provided. The second communication device 11 is a communication terminal that executes an upper subnetwork analysis process that uses the IGD specifications. The second communication device 11 (hereinafter simply referred to as “communication device 11”) obtains each WAN side address in addition to the LAN side addresses of the router A20, the router B30, and the router C40. Different.

  The operation of the upper subnetwork analysis process of the communication device 11 will be described. Using the UPnP IGD (Internet Gateway Device) specification or the like, the communication device 11 acquires the LAN address of the router to which it is connected, and further acquires the WAN address. Then, the communication device 11 estimates the range of the address space of the upper router while acquiring the LAN address of the upper router. In the example shown in FIG. 35, the order of addresses acquired by the communication device 11 is A → B → C → D → E → F.

  The address space estimation process performed by the communication device 11 will be described with reference to FIG. FIG. 36 is a flowchart showing the upper subnetwork analysis process performed by the communication device 11. In the process shown in FIG. 36, the communication device 11 uses a router discovery packet (hereinafter referred to as “M-SEARCH”) that is a UPnP discovery message to the router to which it is connected (router A20 in the case of FIG. 35). , Which is referred to as an estimated router packet) (step S201). The communication device 11 determines whether or not a response packet to the transmitted estimated router packet (hereinafter referred to as an estimated router response packet) has been received (step S202). FIG. 37 shows an example of the data portion of the estimated router packet. FIG. 38 shows an example of the data portion of the estimated router response packet.

  When the communication device 11 receives the estimated router response packet (Yes in step S202), the communication device 11 analyzes the estimated router response packet and acquires the LAN side address of the transmission source router (step S203). Note that since the communication device 11 uses UPnP, the device description and the service description are acquired from information included in the estimated router response packet. These pieces of information are used as information for action transmission. Then, the communication device 11 stops the estimated router packet transmission process (step S204). The communication device 11 acquires the WAN address of the router that is the source of the estimated router response packet (step S205).

  A procedure for acquiring the WAN address of the router using the UPnP IGD specification will be described. The communication device 11 transmits a GetExternalIPAddress action to the LAN address of the transmission source router of the estimated router response packet. FIG. 39 is a diagram illustrating an example of the GetExternalIPAddress action. The router that has received the GetExternalIPAddress action returns a response to the second communication device 11 so that the second communication device 11 obtains the WAN address of the router. FIG. 40 is a diagram illustrating an example of a response to the GetExternalIPAddress action. In this response, the LAN side address of the router is set in the part enclosed by the <NewExternalIPAddress> tag. Therefore, the communication device 11 can obtain the WAN address of the router by extracting the value of the <NewExternalIPAddress> tag. Note that a router usually has a web-based user interface. For this reason, the communication device 11 may acquire the WAN side address of the transmission source router of the estimated router response packet using a Web-based user interface. Specifically, the WAN address of the source router of the estimated router response packet can be obtained by transmitting an http message to the source router of the estimated router response packet and receiving the response.

  The communication device 11 checks whether or not the WAN address of the source router of the estimated router response packet is a local address (step S206). When the acquired WAN side address is a global address (No in step S206), the communication device 11 specifies that the upper router of the source router of the estimated router response packet is a router on the Internet 1. That is, the communication device 11 estimates that all the routers in the home network 2 have been detected and ends the process. On the other hand, when the acquired WAN address is a local address (Yes in step S206), the communication device 11 determines that there is a router belonging to the home network 2 above the source router of the estimated router response packet. Then, again using the WAN address information of the router, the estimated router packet is transmitted (step S207). The estimated router packet transmission process will be described later.

  Then, address space estimation processing is executed using information on the source router of the estimated router response packet (LAN side address, WAN side address, etc.) (step S208).

  The address space estimation process here is slightly different from the case of using a packet whose TTL is changed, and the address space of the upper router is estimated based on the notified WAN address. For example, in FIG. 35, when the second communication device 11 acquires the WAN address of the router B30, the address space estimation process (step S208) is activated. Specifically, the upper subnetwork determining unit primarily estimates the address space of the router C40 using the WAN side address of the router B30, and stores the estimated address space information. Then, the upper subnetwork determination unit performs address space estimation using the same address range estimation packet as in Embodiment 1, and updates the address space information. The difference from the method using the packet with the TTL changed is that the address always included in the address space is not the LAN address of the router to be estimated (the LAN address of the router C40), but the WAN address ( This is only the point that is the WAN side address of the router B30.

  When the WAN address of the router (router A20) to which the communication device 11 is directly connected is acquired, the address space of the router B30 is estimated and stored using the WAN address of the router A20 as described above. In addition, the LAN address information of the router A20 is estimated and stored using the IP address and netmask information of the communication device 11 itself.

  Then, the estimated router packet transmission process is started again, and the process returns to step S202 to receive the estimated router response packet.

  By using the flowchart shown in FIG. 36, the communication device 11 can confirm the presence of a higher-order router from the router connected to itself, and therefore can store connection order information of routers in the home network 2. it can.

  In the above description, the address space estimation process using the address range estimation packet is executed in the address space estimation process. Similar to the method of using a packet whose TTL is changed, the address space estimation process using the address range estimation packet is not executed, and the upper subnetwork analysis process is completed using the address space information estimated first. Good.

(Estimated router packet transmission processing)
In addition, it is possible to transmit the estimated router packet using UPnP and transmit M-SEARCH by unicast to the estimated LAN address of the upper router (in the UPnP Forum standard, M-SEARCH is only multicast, but most routers can also receive unicast M-SEARCH).

  FIG. 41 shows an example of the LAN address of the upper router that the communication device 11 estimates as the destination of the estimated router packet. Normally, the local address of class C is used as the LAN address of the router when it is used in the factory default state. In this case, the value of the lower 8 bits of the local address is 1 or 254. Therefore, when the upper subnetwork determining unit 401 estimates the LAN address of the upper router, the upper router's LAN address is detected by replacing the lower 8 bits of the router WAN address detected by the control unit 101 with 1 or 254. Preferentially inferred as a LAN side address. By guessing in this way, the upper subnetwork determining unit 401 can detect the upper router at high speed. Also, when changing the router's LAN address, the user often sets the lower 8 bits of the LAN address to a specific value such as 64 or 128. For this reason, the upper subnetwork determining unit 401 preferentially estimates an address in which the lower 8 bits of the LAN side address are set to a specific value that is frequently set by the user as the address of the upper router.

  In principle, the communication device 11 can create a large number of estimated router packets whose destinations are all the addresses that can be estimated as shown in FIG. 41 and transmit them at a time. However, if a large number of estimated router packets are transmitted at once, the network may be congested and other communications may be adversely affected. In addition, it is conceivable that the estimated router packet transmitted is discarded, and the router side LAN address acquisition is adversely affected. In order to avoid such an influence, the upper subnetwork determining unit 401 controls to transmit an estimated router packet equal to or less than a predetermined number in a certain period. Further, as shown in FIG. 37, the estimated router packet is transmitted by designating that only the router returns a response.

  In the example of FIG. 37, by setting “urn: schemas-upnp-org: device: InternetGatewayDevice: 1” as ST (SearchTarget), only the router returns a response. For this reason, even if the second communication device 11 transmits the estimated router packet to a plurality of addresses, it does not receive a response from an address other than the router. On the other hand, the second communication device 11 receives the estimated router response packet as shown in the example of FIG. 37 with respect to the estimated router packet in which the router address is specified. The second communication device 11 can obtain the router's LAN address by referring to the source address of the IP header of the estimated router response packet.

  In this way, the second communication device 11 acquires the WAN address after acquiring the LAN address of the router to which it is connected. Based on the obtained WAN address, the address space of the upper router is estimated. Furthermore, the LAN address of the higher router is acquired from the WAN address of the router to which it is connected. By repeating this operation, the second communication device 11 acquires the addresses of all routers in the home network 2 and the connection information of the routers, and estimates the LAN-side address space of each router in the home network 2. Process. Accordingly, the second communication device 11 does not need to perform the operation of the TTL included in the TTL packet or the reception process of the ICMP TIME EXCEEDED MESSAGE. Further, the present invention can be applied to a commercially available router that does not perform TTL processing and a commercially available router that filters ICMP packets.

[Functional configuration of communication equipment without server function]
FIG. 5 is a functional block diagram showing a configuration of the communication device 5a having no server function in the first embodiment of the present invention. The functional configuration of a communication device that does not have a server function is a configuration in which a functional unit related to processing of the server function is removed from a communication device that has a server function. In addition, the other communication apparatus which does not have a server function in this Embodiment shall also have the same structure. The functional configuration will be described below.

  In FIG. 5, the communication device 5 a having no server function includes a communication I / F unit 500, a higher-level subnetwork determination unit 501, a storage unit 502, a server function search unit 503, and a client function unit 506. ing.

[Communication I / F part]
The communication I / F unit 500 controls the network I / F, and receives information from the network and transmits information to the network.

[High-level subnetwork judgment unit]
The upper subnetwork determining unit 501 performs the same upper subnetwork analysis as the above-described upper subnetwork determining unit 401, and the network information under the router connected to the higher level (Internet side) of the router to which it is connected. Is stored in the storage unit 502.

[Server Function Search Unit]
The server function search unit 503 performs only a search process of “communication equipment in which the server function is valid” by the server function search / response unit 403 described above.

[Client Function]
The client function unit 506 performs only a process of communicating (receiving a service) with a communication device in which the server function of the server function unit / client function unit 406 described above is valid.

[Overview of operation of communication equipment without server function]
An outline of operations of the communication devices 5a to 5c having no server function configured as described above will be described with reference to FIG.

  FIG. 11 is a processing flow of a communication device having no server function in Embodiment 1 of the present invention.

  A communication device having no server function performs upper subnetwork analysis (step S1105) by the upper subnetwork determining unit 501 at regular intervals in the same manner as the communication device with server function, and based on the result of the upper subnetwork analysis. A server function search request is transmitted to search for a “communication device in which the server function is valid” (step S1106). Since this operation is the same as the operation of the communication device with the server function described above, detailed description thereof is omitted.

  After transmitting the server function search request, the server function search unit 503 waits for reception of the server function search response (step S1100). When the server function search response is received (Yes in step S1100), the server function that is the transmission source of the server function search response A communication path is connected to the attached communication device (step S1101) to receive a service.

  On the other hand, when a message other than the server function search response is received (No in step S1100 and Yes in step S1102), other message reception processing is performed (step S1103).

  Although it has been described that the upper subnetwork analysis and the transmission of the server function search request are periodically performed, the upper subnetwork analysis and the server function search request may be performed only when the communication path with the communication device with the server function is disconnected. An input means for inputting a signal may be provided, and the input may be performed in accordance with a signal from the input means.

  Hereinafter, an example in which server function switching processing is performed in such an environment will be described.

[When a communication device with a server function is newly connected to the upper subnetwork]
In FIG. 1, using the example in which the server-equipped communication device 4b is newly connected to the network while the server-function-equipped communication device 4b is valid, the server-function-equipped communication device is newly added to the upper subnetwork. The processing when connected to will be described.

  When the server-equipped communication device 4a is newly connected to the network, the server device-equipped communication device search process (step S603) is performed immediately without waiting for a predetermined time only for the first time. In the communication function search processing with a server function (step S603), an upper subnetwork analysis is performed (step S700). As a result, in the first embodiment, since it is determined that the router 3a to which the communication device 4a with a server function is connected is the highest router and there is no network above itself, the server function search is performed only in the peer network. The request is transmitted by multicast (step S701). Since there is no “communication device in which the server function is valid” in the peer network, there is no response to the search request (No in step S702), and it is determined that it is a communication device in which the server function should be validated (step S703). . Further, since the server-equipped communication device 4a is newly connected to the network and the server function of the server function unit / client function unit 406 is not activated (No in step S704), the server function switching process based on appropriateness determination is performed. This is performed (step S705). In the server function switching process based on appropriateness determination, since it is determined that it is a communication device that should enable the server function (Yes in step S1000), the server function is enabled (step S1006).

  Here, a description will be given of processing in a case where the server function is discovered from another communication device with a server function that has been validated after the server function is validated.

  The server-equipped communication device 4b periodically transmits a server function search request to the upper subnetwork. When the server function communication device 4a receives the server function search request from the server function communication device 4b (Yes in step S800), the server function is enabled (Yes in step S801). A server function search response is transmitted to 4b (step S802). At this time, if the server function search request is received from the server function communication device 4b before the server function communication device 4a validates the server function (No in step S801), nothing is done.

  When the server-equipped communication device 4b receives the server function search response from the server-equipped communication device 4a, the server-equipped communication device 4b has found a communication device with the server function that exists in a higher subnetwork than the network to which it belongs. A server function switching message for instructing activation of the server function is transmitted to the communication apparatus 4a with a server function by determining that the communication apparatus should be disabled. When the communication device with server function 4a receives the server function switching message from the communication device 4b with server function (Yes in step S803), the server function switching processing by receiving the message is performed (step S804). In the server function switching process by message reception, a server function switching message for instructing activation of the server function is received (Yes in step S900), and the server function itself has already been activated (Yes in step S902). The process ends without switching.

[When a communication device with server function is newly connected to a lower subnetwork]
In FIG. 1, a communication device with a server function is newly added to a lower subnetwork by using an example in which the communication device 4c with a server function is newly connected to the network while the communication device with a server function 4b is valid. The processing when connected to will be described. In FIG. 1, the communication device 4a with a server function is illustrated, but in the present embodiment, the description will be made assuming that the communication device 4a with a server function does not exist.

  When the server-equipped communication device 4c is newly connected to the network, the server-equipped communication device search process (step S603) is performed immediately without waiting for a certain time only for the first time. In the communication function search processing with a server function (step S603), an upper subnetwork analysis is performed (step S700). Based on the network address information of the router 3a and the router 3b obtained as a result, the address of the “communication device in which the server function is valid” connected to the router 3a and the router 3b is estimated, and a server function search request is transmitted. (Step S701). Also, a server function search request is transmitted by multicast to the network of the router 3c to which it is connected (step S701). Here, the server-equipped communication device 4b connected to the router 3b of the higher-level subnetwork has enabled the server function, and when receiving a server function search request from the server-equipped communication device 4c (Yes in step S800), itself Since the server function is enabled (Yes in step S801), a server function search response is transmitted to the communication device with server function 4c (step S802). The server-equipped communication device 4c receives the server function search response from the server-equipped communication device 4b (Yes in step S702), and since there is a server-equipped communication device in which the server function is enabled in the higher-level subnetwork, Since it is determined that the function is a communication device whose function should be invalidated (step S706), and since it is newly connected to the network and its own server function is not activated (No in step S707), the server Ends processing without switching functions.

[When a higher-level subnetwork that includes a server-equipped communication device with the server function enabled is connected]
In FIG. 1, a network (router 3a and a communication device connected to the router 3a) including the communication device 4a with the server function in which the server function is enabled while the communication device 4b with the server function is enabled is newly provided. A process when a higher-level subnetwork is newly connected will be described using a connected example.

  The server-equipped communication device 4b periodically performs upper subnetwork analysis (step S700). When the upper subnetwork analysis discovers that the upper subnetwork (network connected to the router 3a) is connected, the server-equipped communication device 4b transmits a server function search request to the upper subnetwork (step S701). ). Here, since the server function-equipped communication device 4a connected to the router 3a of the upper subnetwork has validated the server function, a server function search response is received (Yes in step S702). Since there is a communication device with a server function in which the server function is enabled in the upper subnetwork, it is determined that it is a communication device that should disable the server function (step S706), and the server function is enabled (step S706). In step S707, the server function switching process based on the appropriateness determination is performed (step S705). In the server function switching process based on the appropriate determination, since the server function itself is determined to be a communication device whose server function should be disabled (Yes in step S1001), the server function is validated for the discovered communication device with server function 4a. A server function switching message is sent (step S1002). At the same time, information on the communication device 4a with the server function, which is the communication device with the server function to be replaced, such as an IP address, is notified to the other communication devices currently providing the service (step S1003). Then, its own server function is invalidated (the server function unit of the server function unit / client function unit 406 is invalidated and the client function unit is validated) (step S1004), and the switching process is terminated.

  On the other hand, the communication device 4a with a server function performs the same operation as the communication device 4a with a server function described above [when the communication device with a server function is newly connected to a higher-level subnetwork], and validates its own server function. Do not switch.

[When a sub-network including a server-equipped communication device with the server function enabled is connected]
In FIG. 1, a network (router 3c and a communication device connected to the router 3c) including the communication device 4c with the server function in which the server function is enabled while the communication device 4b with the server function is enabled is newly provided. Processing when a lower subnetwork is newly connected will be described using a connected example.

  The server-equipped communication device 4c periodically performs upper subnetwork analysis (step S700). After the network connection, if it is found by the upper subnetwork analysis that the upper subnetwork (the network connected to the router 3b) is connected, the above-mentioned [upper subs including the communication device with the server function with the server function enabled) The same operation as that of the communication device 4b with a server function in the case where the network is connected] is performed, and its own server function is invalidated.

  On the other hand, the communication device 4b with a server function performs the same operation as the communication device 4a with a server function described above [when the communication device with a server function is newly connected to a higher-level subnetwork], and validates its own server function. Do not switch.

  In the present embodiment, the upper subnetwork analysis is periodically performed. However, the user has input means for inputting a signal to the communication device, and the upper subnetwork analysis is performed according to the signal of the input means. May be.

(Embodiment 2)
[Applicable environment for server replacement method]
FIG. 26 is a configuration example of a home network according to Embodiment 2 of the present invention.

  The home network 2 is configured by connecting four routers 3a to 3d. The router 3a is a top-level router connected to the Internet 1, and the router 3c and the router 3d are connected in parallel below the router 3b. Has been. Each router is connected to communication devices 4a to 4d with a server function having a server function and communication devices 5a to 5d having no server function. The configuration of the home network 2 may be wired or wireless. The functions provided by the communication devices 4a to 4d and 5a to 5d are the same as those of the communication device according to the first embodiment of the present invention except for the lower subnetwork determination function. The hardware configuration is the same as that of the communication device in the first embodiment. The configuration of the home network configured with four routers is an example, and the present invention can be similarly applied to a network configured with fewer than four routers or a network configured with four or more routers.

[Functional configuration of communication equipment with server function]
FIG. 13 is a functional block diagram showing a configuration of the communication device 4a with a server function according to the second embodiment of the present invention. The functional block diagram shown in FIG. 13 is different from the functional block diagram shown in FIG. 4 in that a lower subnetwork determining unit 1307 is provided. Since the other components are the same as those in FIG. 4, the same components as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted. In addition, the other communication apparatus with a server function in this Embodiment shall also have the same structure. The functional configuration will be described below.

  4, the communication device with server function 4a includes a communication I / F unit 400, a higher-level subnetwork determination unit 401, a storage unit 402, a server function search / response unit 403, a server suitability determination unit 404, and a server function. A switching unit 405, a server function unit / client function unit 406, and a lower subnetwork determination unit 1307 are provided.

  The communication I / F unit 400, the upper subnetwork determination unit 401, the storage unit 402, the server function search / response unit 403, and the server function unit / client function unit 406 have the same processing functions as those of the first embodiment. Since there is, explanation is omitted.

[Low-level subnetwork judgment unit]
The lower subnetwork determining unit 1307 is a functional unit that determines that a plurality of different routers are connected in parallel below the router to which the lower subnetwork belongs. The lower subnetwork determining unit 1307 compares the router identification information included in the body of the packet received by starting communication from a communication device other than itself, and the source IP address included in the IP header, so that a plurality of different information is obtained. When the presence of the router is detected, the server appropriateness determination unit 404 is notified that a plurality of different routers are connected in parallel below the router to which the router belongs. This is because the NAPT function and firewall function of the home router are hindered, and communication cannot be started from a communication device located on the WAN side to a communication device located on the LAN side. It can be determined that the communication device belongs to the network, and includes the identification information of the router different from the identification information of the router to which it belongs, and the source IP address (router WAN address) included in the IP header is This is because by receiving two or more different packets, it can be determined that a plurality of different routers are connected in parallel below the router to which the packet belongs.

[Server suitability determination section]
The server suitability determination unit 404 is a function unit that determines a communication device whose server function should be validated. In a state where the server function is disabled, a server function search request is received from another communication device with a server function within a certain period of time, or the server function is enabled by a search process in the server function search / response unit 403 If you receive a notification that another server-equipped communication device is found, it is determined that it is a communication device that should disable the server function because another communication device with a server function already exists in the network. To do. At this time, since it is not necessary to switch the server function, the determination result is not notified to the server function switching unit 405. In addition, when the server function is disabled, a server function search request is not received from another communication device with a server function within a predetermined time, and the server function search / response unit 403 performs a server function search process. If you receive a notification that another server-equipped communication device that is enabled cannot be found, there is no other server-equipped communication device in the network. It is determined that the device is a device, and the determination result is notified to the server function switching unit 405.

  On the other hand, when the server function is activated and the server function search / response unit 403 receives a notification that another server-equipped communication device with the server function is found by a search process, the server function arbitration A communication device whose server function should be validated is determined by processing (described later).

  Also, if the lower subnetwork determining unit 1307 notifies that a plurality of different routers are connected in parallel below the router to which the subordinate network belongs, whether or not it is necessary to change the communication device that activates the server function. to decide. If your server function is enabled, or if there is a server-equipped communication device that enables the server function in the host or peer network, there is no need to change the communication device that enables the server function to decide. At this time, since it is not necessary to switch the server function, the determination result is not notified to the server function switching unit 405. On the other hand, if the server function is not enabled and there is no communication device with the server function that enables the server function in the host or peer network, change the communication device that enables the server function. The server function switching unit 405 is notified of the determination result.

  This is because, as described in Embodiment 1, every time the network configuration changes, a communication device with the server function enabled is not installed at the highest level to improve connectivity, but a state where communication is impossible occurs. In such a case, the communication device with the server function enabled is changed to avoid the communication disabled state, so that the communication device with the server function enabled is not changed as much as possible. In general, a home router cannot start communication from a communication device located on the WAN side and communicate with a communication device located on the LAN side due to the influence of the NAPT function or firewall function, but the communication device located on the LAN side. It is possible to start communication from a communication device to a communication device located on the WAN side. Therefore, when routers are connected in series, communication is possible as long as communication is started from a communication device located on the LAN side to a communication device located on the WAN side, and the server function is enabled at the lower level. It is not impossible to perform communication by arranging communication devices. However, when routers are connected in parallel, communication devices under the router connected in parallel will always start from the WAN side with respect to the communication partner regardless of which communication is started. I can't. Therefore, only when the routers are connected in parallel and the communication devices under the respective routers cannot always communicate with each other, it is necessary to switch the communication device with the server function enabled to the upper subnetwork. Communication devices can communicate with each other by the number of switching times.

[Server function switching section]
The server function switching unit 405 is a function unit that switches the function of the server function unit / client function unit 406 in response to an instruction to switch the server function. The server function switching instruction includes a server function switching message from another communication device with a server function and a determination result from the server suitability determination unit 404. The server function switching instruction includes a server function switching message from another communication device with a server function and a determination result from the server suitability determination unit 404. When the server function is to be validated, the server function switching unit 405 validates the server function unit of the server function unit / client function unit 406 and invalidates the client function unit. On the other hand, when disabling the server function, the server function unit of the server function unit / client function unit 406 is disabled and the client function unit is enabled.

  In addition, when receiving an instruction to change the communication device that activates the server function, it sends a server function switching message to instruct the server device to disable the server function to the communication device that is currently enabling the server function. The server function is activated or a server function switching message for instructing the activation of the server function is transmitted to the upper and peer networks, and the communication device for activating the server function is replaced.

  In addition, when switching the server function from the valid state to the invalid state, before switching, the communication device with the server function is notified to the communication device providing the service, and the server function is valid. Is stored in the storage unit 402 as information on the communication device. When the server function is switched from the invalid state to the valid state, the information is stored in the storage unit 402 as information of the communication device in which the server function is valid after the server function is validated. The information on the communication device with a server function to be replaced is notified from the server function search / response unit 403 or is acquired from a server function switching message from another communication device with a server function.

  In addition, when switching the server function according to the determination result from the server suitability determination unit 404, the server function switch is used to instruct the determination result from the server suitability determination unit 404 to the communication device with the server function discovered before switching the server function. Notify as a message.

[Overview of operation of communication equipment with server function]
An outline of operations of the communication devices 4a to 4d with a server function configured as described above will be described with reference to FIGS. 15 to 21 and FIG.

  FIG. 25 is an overall processing flow of the communication device with a server function in the embodiment of the present invention.

  When the communication device with the server function receives the message (Yes in step S2500), the communication device with the server function is executed (step S2501), and the communication device search process with the server function (step S2503) is executed at regular intervals. In addition, if a communication device with a server function cannot be found in the host or peer network in the communication device search process with a server function (step S2503), the lower subnetwork that cannot be searched with the communication device search process with a server function (step S2508) In order to detect whether or not a communication device with a server function exists, it is determined whether a server function search request has been received from the communication device with a server function for a certain period of time.

  When the server-equipped communication device receives the message (Yes in step S2500), the communication device with the server function executes a message reception process (step S2501). If a message has not been received (No in step S2500), and if a certain time has elapsed after the message reception process (step S2501) (Yes in step S2502), a communication device search process with a server function is performed (step S2502). S2503). In the server device-equipped communication device search process (step S2503), when a response to the server function search request is received (Yes in step S2504), the process again returns to a message reception wait state. On the other hand, in the server device-equipped communication device search process (step S2503), when a response to the server function search request is not received (No in step S2504), or a certain time has not elapsed (No in step S2502), If the server-equipped communication device search process has not been executed, it is determined whether or not its own server function is already valid (step S2505). If its own server function is already valid (Yes in step S2505), it returns to the message reception waiting state again. On the other hand, if the server function is not enabled (No in step S2505), it is determined whether a server function search request is received from the communication device with the server function within a certain time. Thereby, it is possible to detect whether or not a communication device with a server function exists in the lower subnetwork. If no server function search request is received from the communication device with server function within a certain time (No in step S2506 and Yes in step S2507), there is no other communication device with server function in the network. The server itself determines that it is a communication device whose server function should be validated (step S2508), the server function switching unit 405 performs server function switching processing based on appropriateness determination (step S2509), and returns to the message reception waiting state again. On the other hand, if a server function search request has been received from a communication device with a server function (Yes in step S2506), the communication device with the server function already exists in the lower subnetwork, and the state again returns to a message reception waiting state. .

[Communication device search processing with server function]
FIG. 15 is a processing flow of the communication device search processing with server function (step S2503) of the communication device with server function according to the second embodiment of the present invention.

  Since processing (step S1500 to step S1501) when a communication device with a server function is found by searching is the same as that in the first embodiment, description thereof is omitted.

  FIG. 24 shows an example of a server function search request. In the server function search request, an ID indicating that this message is a server function search request is set in the message ID field in the body. Also, an ID unique to the transmission source communication device is set as the transmission source ID. In addition, for example, a router MAC address or a product number is set as router identification information so that it can be determined which router a communication device belongs to. Information on whether or not the communication device of the server function search request transmission source has the server function may be included in the ID unique to the transmission source communication device, or other fields may be prepared.

  When the server function communication device connected to the upper router receives the server function search request, the server function search / response unit 403 sends the server function search response to the server function search request only when its server function is valid. To the source address (IP address, port number). An example of the format of the server function search response is the same as the server function search request. However, an ID value indicating a server function search response is set as the message ID.

  The server-equipped communication device determines whether a server function search response has been received after transmitting the server function search request (step S1502).

  If the server function search response cannot be received (No in step S1502), the process ends without doing anything.

  If a server function search response has been received (Yes in step S1502), it is determined whether or not its own server function is already valid (step S1503). If the server function is not valid (No in step S1503), it is determined that the server device is a communication device whose server function should be invalidated because a communication device in which the server function is valid already exists in the network (step S1505). Since it is not necessary to switch the server function, the process is terminated. When the server function is valid (Yes in step S1503), server function arbitration processing is performed to determine which server function should be validated with the communication device for which the discovered server function is valid (step S1504, which will be described later). .

[Message reception processing]
FIG. 16 is a process flow of the message reception process (step S2501) of the communication device with a server function according to the second embodiment of the present invention.

  The server function search / response unit 403 of the communication device with server function 4a always receives a server function search request from a communication device connected to a lower router (step S1600), and receives server functions from other communication devices with server function. Receiving the switching message (step S1602) and receiving a network configuration change notification message indicating that a plurality of different routers are connected in parallel below the router to which the communication device does not have a server function (step S1604). Waiting for. When a server function search request is received from a communication device connected to a lower router (Yes in step S1600), a server function search request reception process (step S1601) described later is performed.

  On the other hand, when a server function switching message is received from another communication device with a server function (No in step S1600 and Yes in step S1602), the server function switching unit 405 performs server switching processing by receiving the message (step S1603). .

  When a network configuration change notification message is received from a communication device that does not have a server function (No in step S1600, No in step S1602, and Yes in step S1604), the lower subnetwork determination unit 1307 determines that it is It is determined that a plurality of different routers are connected in parallel below the router to which the router belongs, and the determination result is notified to the server suitability determination unit 404. The server appropriateness determination unit 404 receives the notification of the lower subnetwork determination unit 1307 and determines whether or not its server function is valid (step S1605). If its own server function is valid (Yes in step S1605), even if a plurality of different routers are connected in parallel below the router to which it belongs, the communication devices under each router can communicate with each other. Since it is possible, it is determined that there is no need to change the communication device that validates the server function, and the process ends. If its own server function is not valid (No in step S1605), it is determined whether or not there is a communication device with a server function that enables the server function in the host or peer network (step S1606).

  If there is a communication device with a server function that enables the server function in the higher level or peer network (Yes in step S1606), even if a plurality of different routers are connected in parallel below the router to which it belongs, Since communication devices under the router can communicate with each other via a communication device with a server function that currently enables the server function, it is determined that there is no need to change the communication device that enables the server function, and the processing is terminated. . When there is no communication device with a server function that enables the server function in the higher level or peer network (No in step S1606), communication between the communication devices under the router connected in parallel to the lower level of the router to which the device belongs is communicating. Therefore, it is determined that the communication device that activates the server function should be changed (step S1607), the determination result is notified to the server function switching unit 405, and the server function switching unit 405 performs server function switching processing based on appropriateness determination. (Step S1608).

  If no server function search request, server function switching message, or network configuration change message has been received (No in step S1600, No in step S1602, and No in S1604), other message reception processing is performed (step S1609). .

[Server function search request reception processing]
The server function search request reception process (step S1601) of the communication device with a server function will be described with reference to FIG.

  In the server function search request reception process, first, it is determined whether or not its own server function is valid (step S1700). If the server function is valid (Yes in step S1700), a response to the server function search request is transmitted (step S1701), and a lower subnetwork existence determination process (step S1702) described later is performed. If the server function of the server is not valid (No in step S1700), it is determined whether the device that has transmitted the received server function search request is a communication device with a server function (step S1704). If the transmission source device of the received server function search request is a communication device with a server function (Yes in step S1704), it is determined whether a connection is already established with a communication device in which another server function is enabled. Judgment is made (step S1710). If the connection is already established with the communication device in which the server function is enabled (Yes in step S1710), the lower subnetwork existence determination process (step S1702) is performed. If the connection is not yet connected to a communication device with the server function enabled, the server function communication device that sent the server function search request may have already enabled the server function. Is determined to be a communication device whose server function should be invalidated (step S1707), and lower subnetwork existence determination processing (step S1702) is performed. If the transmission source device of the received server function search request is not a communication device with a server function (No in step S1704), lower subnetwork existence determination processing (step S1702) is performed.

  As a result of the lower subnetwork existence determination process (step S1702), when the lower subnetwork determination unit 1307 determines that a plurality of different routers are not connected in parallel below the router to which it belongs (No in step S1703). The process is terminated. If it is determined that a plurality of different routers are connected in parallel below the router to which it belongs (Yes in step S1703), it is determined whether or not its server function is valid (step S1705). If its own server function is valid (Yes in step S1705), even if a plurality of different routers are connected in parallel below the router to which it belongs, the communication devices under each router can communicate with each other. Since it is possible, it is determined that there is no need to change the communication device that validates the server function, and the process ends. If its own server function is not valid (No in step S1705), it is determined whether or not there is a communication device with the server function in which the server function is valid in the host or peer network (step S1706).

  If there is a communication device with a server function that enables the server function in the higher level or peer network (Yes in step S1706), even if a plurality of different routers are connected in parallel below the router to which the server belongs, Since communication devices under the router can communicate with each other via a communication device with a server function that currently enables the server function, it is determined that there is no need to change the communication device that enables the server function, and the processing is terminated. . If there is no server-equipped communication device that enables the server function in the upper level or peer network (No in step S1706), the communication devices under the router connected in parallel below the router to which the device belongs belong to each other. Therefore, it is determined that the communication device that activates the server function should be changed (step S1708), the determination result is notified to the server function switching unit 405, and the server function switching unit 405 performs server function switching processing based on appropriateness determination. (Step S1709).

[Low-level subnetwork existence determination processing]
With reference to FIG. 18, the lower subnetwork presence determination process (step S1702) of the communication device with a server function will be described.

  In the lower subnetwork existence determination process (step S1702), first, the lower subnetwork determination unit 1307 compares the router identification information included in the received server function search request with the identification information of the router to which it belongs (step S1800). ). This is because a server function search request is received only from a peer device or a communication device existing in a sub-network lower than itself due to the influence of the NAPT function and firewall function of a general home router. This is because it is determined that a router exists below the router to which it belongs. If the identification information of the router included in the received server function search request is the same as the identification information of the router to which it belongs (No in step S1800), it is a packet received from a communication device existing in the peer network, and therefore belongs to itself. It is determined that a plurality of different routers are not connected in parallel below the router (step S1801), the determination result is notified to the server suitability determination unit 404, and the process ends. On the other hand, if the identification information of the router included in the received server function search request is different from the identification information of the router to which the router belongs (Yes in step S1800), the router exists below the router to which the router belongs, The router identification information in the body and the transmission source address of the IP header are stored in the storage unit 402, the transmission source address of the IP header of the received packet, and the server function previously received from another communication device and stored in the storage unit 402 The source address of the IP header of the search request is compared (step S1802). This is to determine whether a plurality of different routers are connected in series below the router to which the router belongs or whether a plurality of different routers are connected in parallel. By using the fact that the source address of a packet transmitted from a communication device belonging to a sub-network lower than itself is converted to the WAN address of the router by using the NAPT function or firewall function of the home router, the IP header of the packet By comparing the source address, that is, the WAN address of the router, if a plurality of packets having different source identification addresses and the same source address are received, it belongs to a plurality of routers connected in series It can be determined that the packets have been received from a plurality of communication devices, and when a plurality of packets having different source addresses are received, it can be determined that the packets have been received from a plurality of communication devices belonging to a plurality of routers connected in parallel. Therefore, if the source address of the IP header of the received packet is the same as the source address of the IP header of the server function search request that was previously received and stored in the storage unit 402 (No in step S1802), it belongs to itself. It is determined that a plurality of different routers are connected in series below the router and are not connected in parallel (step S1801), the determination result is notified to the server suitability determination unit 404, and the process ends. On the other hand, if the source address of the IP header of the received packet is different from the source address of the IP header of the server function search request that has been received and stored in the storage unit 402 (Yes in step S1802), it belongs to itself. It is determined that a plurality of different routers are connected in parallel below the router (step S1803), the determination result is notified to the server suitability determination unit 404, and the process ends.

  In the second embodiment, it is determined by receiving a server function search request from a communication device belonging to a plurality of different routers that a plurality of different routers are connected in parallel below the router to which the router belongs. However, it may be a message other than the server function search request. Further, the router identification information and the transmission source communication device identification information of different messages may be compared instead of the same type of message.

  In addition, when the router identification information of the received server function search request is different from the identification information of the router to which the server belongs, the router identification information in the packet and the source address of the IP header are described as being stored in the storage unit 402. When the server function search request is received, it is stored in the storage unit 402. When the router identification information of the received server function search request is different from the identification information of the router to which the server belongs, the server function search request is received and stored in the storage unit 402. The router identification information of the server function search request may be compared with the source address of the IP header.

  Further, it may be stored only when a packet having router identification information different from the router to which it belongs and having router identification information not registered in the storage unit 402 is received.

  The router identification information may be a MAC address, serial number, router LAN address, etc., but is not limited to this, and any information that can uniquely identify the router may be used.

  In addition, although it has been described that by comparing the source address of the IP header, it is determined whether there are a plurality of different routers in series below the router to which the IP header belongs, or a plurality of different routers in parallel. Any method can be used as long as it can determine whether it is serial or parallel.

  In addition, when the identification information of the router included in the received server function search request is different from the router to which the server belongs, it is compared with the source address of the IP header of the server function search request received and stored in the storage unit 402. However, the source address of the IP header of the server function search request previously stored in the storage unit 402 may be compared, and if they are different, the router identification information may be compared. It is not defined.

[Server function switching processing by message reception]
FIG. 19 is a diagram showing server function switching processing by message reception in step S1603 of FIG.

  When a server function switching message instructing activation of the server function is received from another communication device with a server function as a trigger for the server function switching process (Yes in step S1900), the server function switching unit 405 The server function unit of the client function unit 406 is activated (step S1901), and a server function search request is transmitted to the communication device to the network of the upper router and the peer network determined from the result of the upper subnetwork analysis (step S1500) ( Step S1902). After transmitting the server search request, the server waits for a server function search response from a communication device belonging to the upper subnetwork (step S1903). If a server function search response is received from a communication device belonging to the upper subnetwork (Yes in step S1903). Since the communication device with the server function exists in the higher-level sub-network that can improve the connectivity, the server function unit of the server function unit / client function unit 406 is disabled and the client function unit is enabled (step S1904). finish. On the other hand, if the server function search response cannot be received from the communication device existing in the higher-level subnetwork (No in step S1903), the reception of the server function search response from the communication device existing in the peer network is awaited (step S1905). . When a server function search response is received from a communication device existing in the peer network (Yes in step S1905), a server function arbitration process described later is performed (step S1906). As a result of the server function arbitration process, its own server function is valid. If the server function has been activated (Yes in step S1907), a server function activation response is transmitted to the communication apparatus with the server function that is the transmission source of the server function switching message instructing activation of the server function (step S1909). ), The process is terminated. If the server function is disabled as a result of the server function arbitration process (No in step S1907), the process ends. If a server function search response has not been received from a communication device that exists in the peer network (No in step S1905), the server function switch that instructs the communication device that has already enabled the server function to disable the server function A message is transmitted (step S1908), a server function activation response is transmitted to the communication device with the server function that is the transmission source of the server function switching message instructing activation of the server function (step S1909), and the process is terminated. To do.

  On the other hand, when a server function switching message for instructing invalidation of the server function is received from another communication device with a server function (No in step S1900 and Yes in step S1910), the communication that provides the service itself Information on other communication devices that replace the server function is transmitted to the device (step S 1911), the server function unit of the server function unit / client function unit 406 is disabled, and the client function unit is enabled (step S 1912). finish.

[Server function switching process based on appropriate judgment]
FIG. 20 is a diagram showing server function switching processing based on suitability determination in step S1608 in FIG. 16, step S1709 in FIG. 17, and step S2509 in FIG.

  When the server function switching process trigger is received from the server suitability determination unit 404 as a communication notification that the server function is to be enabled (Yes in step S2000), the server function unit / client function unit 406 server function The part is validated and the client function part is invalidated (step S2003), and the process is terminated. When the server appropriateness determination unit 404 receives a determination notification that it is a communication device that should invalidate the server function (No in step S2000 and Yes in step S2001), the server function unit of the server function unit / client function unit 406 The client function unit is disabled (step S2004), and the process is terminated.

  On the other hand, when a notification of determination that the communication device that activates the server function should be changed is received from the server suitability determination unit 404 (No in S2000, No in S2001, and Yes in step S2002), the higher rank and the peer A server function switching message for instructing activation of the server function is transmitted to the network (step S2005), and reception of a server function activation response is awaited (step S2006). If a server function activation response is received within a certain time (No in step S2007 and Yes in step S2006), either one of the communication devices with the server function in the upper level or peer network has activated the server function. The process ends without doing anything. On the other hand, if the server function activation response is not received within a certain time (No in step S2006 and Yes in step S2007), the server function unit / Server function switching message for instructing to disable the server function for the server function communication device that currently enables the server function by enabling the server function part of the client function unit 406 and disabling the client function unit (step S2008). Is transmitted (step S2009), and the process is terminated.

  In this embodiment, the server function is enabled when the server function is not enabled and there is no communication device with the server function that enables the server function in the host or peer network. It is explained that it is determined that the communication device to be changed should be changed. However, when it is detected that multiple different routers are connected in parallel under the router to which it belongs, communication that always enables the server function at the highest level. If you want to switch to install the device, even if your server function is enabled, if there is no communication device with server function that enables the server function in the upper subnetwork, A server function switching message that determines that the communication device that activates the server function should be changed and instructs the higher-level subnetwork to activate the server function. It may be transmitted di.

  In this embodiment, the server function switching message for instructing the server function to be activated is transmitted to the host and peer networks. However, if the server function is not valid, the server function switching message is transmitted. Instead, the server function may be validated. Also, instead of sending a server function switching message for instructing the server function to be activated to a plurality of communication devices with a server function, it is determined in advance among communication devices with a server function existing in a higher level or peer network. You may transmit the server function switching message which instruct | indicates validation of a server function with respect to 1 unit | set.

[Server function arbitration]
The server function arbitration process in step S1504 in FIG. 15 and step S1908 in FIG. 19 will be described with reference to FIG.

  The server function arbitration process is a process for mediating one communication device that provides a service by enabling the server function.

  In the server function arbitration process, the server function communication device that activates the found server function is compared with the time during which the server function is activated (step S2100), and if the server function is shorter (in step S2101) No), it is determined whether there is a communication device that currently provides a service (step S2102). If a service is currently being provided to any communication device on the network (Yes in step S2102), information on the other communication device that replaces the server function is transmitted to the communication device that is providing the service. (Step S2104) The server function unit / client function unit 406 of the server function unit / client function unit 406 is invalidated and the client function unit is validated (Step S2103), and the process is terminated. If the service is not currently provided to the communication device on the network (No in step S2102), the server function unit of the server function unit / client function unit 406 is disabled and the client function unit is enabled (step S2103). Exit. If the time during which the server function is enabled is longer (Yes in step S2101), a server function switching message for instructing to disable the server function is transmitted to the communication device that has enabled the found server function ( Step S2105), the process is terminated.

  Although it has been described that the server function search time is compared when a server function search response is received from a communication device with a server function that exists in the peer network, the server function search time is the server function search time. Information may be exchanged by preparing fields in the request and server function search response, or other messages may be used.

  In this embodiment, the time for which the server function is activated is used as a judgment material for arbitration. However, the arbitration method for the server function is not limited to this description, and other than the time for which the server function is activated. May be compared using, for example, the number of communication devices providing services, the functions and processing capabilities provided, the date of manufacture (newness as a communication device), etc. It may not be a thing but may mediate to one by other methods.

[Functional configuration of communication equipment without server function]
FIG. 14 is a functional block diagram showing the configuration of the communication device 5a having no server function in Embodiment 2 of the present invention. The functional configuration of a communication device that does not have a server function is a configuration in which a functional unit related to processing of the server function is removed from a communication device that has a server function. The functional block diagram shown in FIG. 14 is different from the functional block diagram shown in FIG. 5 in that a lower subnetwork determining unit 1407 is provided. Since the other components are the same as those in FIG. 5, the same components as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted. In addition, the other communication apparatus which does not have a server function in this Embodiment shall also have the same structure. The functional configuration will be described below.

  In FIG. 14, the communication device 5a having no server function includes a communication I / F unit 500, an upper subnetwork determination unit 501, a storage unit 502, a server function search unit 503, a client function unit 506, A sub-network determination unit 1407 is provided.

  The communication I / F unit 500, the higher-level subnetwork determination unit 501, the storage unit 502, the server function search unit 503, and the client function unit 506 have the same function units and processing functions as those described in the first embodiment, and thus description thereof is omitted. To do.

[Low-level subnetwork judgment unit]
The lower subnetwork determining unit 1407 is a functional unit that determines that a plurality of different routers are connected in parallel below the router to which the lower subnetwork belongs. The lower subnetwork determining unit 1407 compares the router identification information included in the body of the packet received by starting communication from a communication device other than itself, and the source IP address included in the IP header, so that a plurality of different information is obtained. When the presence of a router is detected, a network configuration change notification message is transmitted to the effect that a plurality of different routers are connected in parallel below the router to which the router belongs to the network to which the router belongs and the upper subnetwork.

[Overview of operation of communication equipment without server function]
An outline of operations of the attached communication devices 5a to 5d having no server function configured as described above will be described with reference to FIGS.

  FIG. 22 is a processing flow of a communication device having no server function in Embodiment 2 of the present invention.

  The communication device having no server function performs upper subnetwork analysis (step S2208) by the upper subnetwork determining unit 501 at regular intervals in the same manner as the communication device with server function, and based on the result of the upper subnetwork analysis. A server function search request is transmitted to search for a “communication device in which the server function is valid” (step S2209). Since this operation is the same as the operation of the communication device having no server function in the first embodiment, detailed description thereof is omitted. However, it is assumed that the server function search request and the server function search response follow the format shown in FIG.

  After transmitting the server function search request, the server function search unit 503 waits for reception of the server function search response (step S2200). When the server function search response is received (Yes in step S2200), the server function that is the source of the server function search response A communication path is connected to the attached communication device (step S2201) to receive a service.

  Further, when a server function search request is received (Yes in step S2203), a lower subnetwork existence determination process (step S2204) described later is performed.

  On the other hand, when a message other than the server function search response is received (No in step S2200, No in step S2203, and Yes in step S2205), other message reception processing is performed (step S2206).

[Low-level subnetwork existence determination processing]
With reference to FIG. 23, the lower subnetwork existence determination process (step S2204) of the communication device having no server function will be described.

  In the lower subnetwork existence determination process (step S2204), first, the lower subnetwork determination unit 1407 compares the router identification information included in the received server function search request with the identification information of the router to which it belongs (step S2300). ). If the identification information of the router included in the received server function search request is the same as the identification information of the router to which it belongs (No in step S2300), it is a packet received from a communication device existing in the peer network, and therefore belongs to itself. It is determined that a plurality of different routers are not connected in parallel below the router, and the process ends. On the other hand, if the identification information of the router included in the received server function search request is different from the identification information of the router to which the router belongs (Yes in step S2300), the router exists below the router to which the router belongs, The router identification information in the body and the source address of the IP header are stored in the storage unit 502, the source address of the IP header of the received packet, and the server function previously received from other communication devices and stored in the storage unit 502 The source address of the IP header of the search request is compared (step S2301). If the source address of the IP header of the received packet is the same as the source address of the IP header of the server function search request that was previously received and stored in the storage unit 502 (No in step S2301), the router of the router to which it belongs. A plurality of different routers are connected in series at the lower level, and it is determined that they are not connected in parallel, and the process ends. On the other hand, if the source address of the IP header of the received packet is different from the source address of the IP header of the server function search request received and stored in the storage unit 502 (Yes in step S2301), it belongs to itself. There is a communication device with a server function that determines that a plurality of different routers are connected in parallel below the router, and the server function is enabled in the upper or peer network determined from the result of the upper subnetwork analysis (step S2308). If so (Yes in step S2302), the process is terminated without doing anything, and if it does not exist (No in step S2302), a plurality of different routers are connected in parallel to the lower and peer networks. A network configuration change notification indicating this is transmitted (step S2303), and the process is terminated. .

  Hereinafter, an example in which server function switching processing is performed in such an environment will be described.

[When a communication device with a server function is newly connected to the upper subnetwork]
In FIG. 1, using the example in which the server-equipped communication device 4b is newly connected to the network while the server-function-equipped communication device 4b is valid, the server-function-equipped communication device is newly added to the upper subnetwork. The processing when connected to will be described. Note that the MAC address of the router 3a is 00-0E-7F-F9-87-28, the transmission source address is 192.168.1.1, the MAC address of the router 3b is 00-08-02-0A-DA-86, The source address is 192.168.2.220, the MAC address of the router 3c is 00-11-43-BD-BE-43, and the source address is 192.168.3.10.

  When the server-equipped communication device 4a is newly connected to the network, the server device-equipped communication device search process (step S2503) is performed immediately without waiting for a predetermined time only for the first time. In the communication function search processing with a server function (step S2503), the upper subnetwork analysis is performed (step S1500). As a result, in the second embodiment, since it is determined that the router 3a to which the communication device with server function 4a is connected is the highest router and there is no network above itself, the server function search is performed only in the peer network. The request is transmitted by multicast (step S1501). Since there is no “communication device in which the server function is valid” in the peer network, there is no response to the search request (No in step S1502), and the server-equipped communication device search process (step S2503) is terminated. The communication device with server function 4a has not received a response to the server function search request in the communication device search process with server function (step S2503) (No in step S2504), and is newly connected to the network. Since the server function of the server function unit / client function unit 406 is not activated (Yes in step S2505), it waits for reception of a server function search request from a subnetwork lower than a certain time. Since the router 3b and the router 3c exist below the router 3a, and the communication devices 4b and 4c with server functions are connected to the router 3a, the communication device 4a with server function is changed from any of the communication devices with server function to the server. A function search request is received (Yes in step S2500, step S2501 is executed, and step S1600 is Yes), and a server function search request reception process (step S1601) is executed. Here, it is assumed that a server function search request is received from the communication device 4b with a server function. In the server function search request reception process (step S1601), the server function search response is not transmitted because the server function is not valid (No in step S1700). In addition, the communication device with the server function search request is the communication device 4b with the server function (Yes in step S1704), and the communication device 4a with the server function is the communication device 4b with the server function that enables the server function. Since the connection is not connected (No in step S1710), it is determined that it is a communication device whose server function should be disabled (step S1707), and the lower subnetwork existence determination process (step S1702) is performed. In the lower subnetwork existence determination process (step S1702), the router identification information included in the received server function search request is compared with the identification information of the router to which it belongs (step S1800). What is the MAC address 00-0E-7F-F9-87-28 of the router 3a to which the router itself belongs and the MAC address 00-08-02-0A-DA-86 of the router 3b, which is router identification information included in the received packet? Because they are different (Yes in step S1800), the source address of the IP header of the received server function search request is compared with the source address of the IP header of the server function search request that has been received and stored in the storage unit 402 ( Step S1802). Here, the server function-equipped communication device 4a has just been newly connected and has not received another server function search request, and therefore cannot be compared (No in step S1802). The router identification information and the IP header source address included in the server function search request received from the server function communication device 4b are stored in the storage unit 402, and a plurality of different routers are arranged in parallel below the router to which the server belongs. It is determined that they are not connected (step S1801), and the lower subnetwork existence determination process (step S1702) is terminated. As a result of the lower subnetwork existence determination processing (step S1702), since it is determined that a plurality of different routers are not connected in parallel below the router to which the subnetwork belongs (Yes in step S1703), the message reception processing ends, and the server The subsequent operations are performed in a state where the server function of the function unit / client function unit 406 is not activated.

[When a communication device with server function is newly connected to a lower subnetwork]
In FIG. 1, a communication device with a server function is newly added to a higher-level subnetwork using an example in which the communication device with a server function 4b is newly connected to the network while the communication device with a server function 4b is enabled. The processing when connected to will be described. Note that the MAC address of the router 3a is 00-0E-7F-F9-87-28, the transmission source address is 192.168.1.1, the MAC address of the router 3b is 00-08-02-0A-DA-86, The source address is 192.168.2.220, the MAC address of the router 3c is 00-11-43-BD-BE-43, and the source address is 192.168.3.10.

  When the server-equipped communication device 4c is newly connected to the network, the server-equipped communication device search process (step S2503) is performed immediately without waiting for a certain time only for the first time. In the communication function search processing with a server function (step S2503), the upper subnetwork analysis is performed (step S1500). Based on the network address information of the router 3a and the router 3b obtained as a result, the address of the “communication device in which the server function is valid” connected to the router 3a and the router 3b is estimated, and a server function search request is transmitted. (Step S1501). Also, a server function search request is transmitted by multicast to the network of the router 3c to which it is connected (step S1501). Here, the server-equipped communication device 4b connected to the router 3b of the higher-level subnetwork has enabled the server function, and when a server function search request is received from the server-equipped communication device 4c (Yes in step S2500, step S2501). And the server function search request reception process (step S1601) is executed. In the server function search request receiving process (step S1601), since the server function-equipped communication device 4b has its server function enabled (Yes in step S1700), a server function search response is transmitted to the server function-equipped communication device 4c. (Step S1701). The server function communication device 4c receives the server function search response from the server function communication device 4b (Yes in step S1502), and is newly connected to the network. The server function of the server function unit / client function unit 406 Is not activated (No in step S1503), it is determined that it is a communication device whose server function should be invalidated (step S706), and the server-equipped communication device search process is terminated. The subsequent operations are performed in a state where the server function of the function unit / client function unit 406 is not activated.

  On the other hand, the server-equipped communication device 4 that has received the server function search request from the server-equipped communication device 4c transmits a server function search response to the server-function-equipped communication device 4c (step S1701), and then performs a lower subnetwork existence determination process. (Step S1702) is performed. In the lower subnetwork existence determination process (step S1702), the router identification information included in the received server function search request is compared with the identification information of the router to which it belongs (step S1800). What is the MAC address 00-08-02-0A-DA-86 of the router 3b to which it belongs and the MAC address 00-11-43-BD-BE-43 of the router 3c, which is router identification information included in the received packet? Because they are different (Yes in step S1800), the source address of the IP header of the received server function search request is compared with the source address of the IP header of the server function search request that has been received and stored in the storage unit 402 ( Step S1802). Here, since the communication device 4b with the server function has validated the server function, assuming that the connection is made with the communication device 5c that does not have the server function and exists in the lower subnetwork connected to the router 3c. The storage unit 402 stores the MAC address of the router 3c and the source address 192.168.3.10 of the IP header when a server function search request is received from the communication device 5c having no server function. The communication device 4b with a server function includes a transmission source address 192.168.3.10 of the server function search request received from the communication device 4c with a server function, and a communication device having no server function stored in the storage unit 402. Since the source address 192.168.3.10 of the server function search request received from 5c is the same (No in step S1802), a plurality of different routers are not connected in parallel below the router to which the server belongs. (Step S1801), the lower subnetwork existence determination process (Step S1702) is terminated. As a result of the lower subnetwork existence determination process (step S1702), since it is determined that a plurality of different routers are not connected in parallel below the router to which the subnetwork belongs (Yes in step S1703), the message reception process is terminated.

  On the other hand, the server function search request transmitted by the server function communication device 3c is also received by the server function communication device 4a. The communication device 4a with the server function also performs the lower subnetwork existence determination process similarly to the server function 4b. However, since the router 3b and the router 3c are connected in series, the server receives from any communication device existing in the lower subnetwork. Since all the function search requests are also composed of the MAC address and the source address of the router 3b, it is determined that a plurality of different routers are not connected in parallel below the router to which the function search request belongs, and the message reception process ends.

[When a higher-level subnetwork that includes a server-equipped communication device with the server function enabled is connected]
In FIG. 1, a network (router 3a and a communication device connected to the router 3a) including the communication device 4a with the server function in which the server function is enabled while the communication device 4b with the server function is enabled is newly provided. A process when a higher-level subnetwork is newly connected will be described using a connected example. Note that the MAC address of the router 3a is 00-0E-7F-F9-87-28, the transmission source address is 192.168.1.1, the MAC address of the router 3b is 00-08-02-0A-DA-86, The source address is 192.168.2.220, the MAC address of the router 3c is 00-11-43-BD-BE-43, and the source address is 192.168.3.10.

  The communication device with server function 4b periodically performs communication device search processing with server function search (step S2503). In the communication device search processing with a server function (step S2503), the upper subnetwork analysis (step S1500) is performed, and the upper subnetwork analysis (network connected to the router 3a) is newly connected. If found, the server function-equipped communication device 4b transmits a server function search request to the upper subnetwork (step S1501). Similarly, a server function search request is transmitted to the peer network (step S1501). Here, since the server function-equipped communication device 4a connected to the router 3a of the higher-level subnetwork has validated the server function, the server function search response is received (Yes in step S1502). Since there is a server-equipped communication device in which the server function is enabled in the upper subnetwork and the server function is valid (Yes in step S1503), either of the communication devices with the server function that enables the server function is selected. On the other hand, server function arbitration processing is performed to reduce the number (step S1504). In the server function arbitration process (step S1504), the time for which the server function with the discovered server function-equipped communication device 4a is validated is compared (step S2100). Here, it is assumed that the communication function 4a with the server function activates the server function for 5 minutes, and the communication apparatus 4b with the server function activates the server function for 1 hour. As a result of comparing the time during which the server function with the server function with server function 4a and the server function enabled is found, the server function is enabled for a longer time (Yes in step S2101). The communication device 4b transmits a server function switching message for instructing invalidation of the server function to the communication device 4a with a server function (step S2105), and ends the server function arbitration process (step S2503).

  On the other hand, since the communication device 4a with a server function is connected to the router 3b and the router 3c below the router 3a to which the server function belongs, and the communication devices 4b and 4c with a server function are respectively connected to the communication device 4a. A server function search request is received from the communication device (Yes in step S2500, step S2501 is executed, and step S1600 is Yes), and a server function search request reception process (step S1601) is executed. Here, it is assumed that a server function search request is received from the communication device 4b with a server function. In the server function search request reception process (step S1601), since the server function is valid (Yes in step S1700), a server function search response is transmitted to the communication device 4b with a server function (step S1701), and a lower subnetwork exists. A determination process (step S1702) is performed. In the lower subnetwork existence determination process (step S1702), the router identification information included in the received server function search request is compared with the identification information of the router to which it belongs (step S1800). What is the MAC address 00-0E-7F-F9-87-28 of the router 3a to which the router itself belongs and the MAC address 00-08-02-0A-DA-86 of the router 3b, which is router identification information included in the received packet? Because they are different (Yes in step S1800), the source address of the IP header of the received server function search request is compared with the source address of the IP header of the server function search request that has been received and stored in the storage unit 402 ( Step S1802). Here, if the network including the server-equipped communication device 4a has just been newly connected, and no connection is connected to the communication device connected to the router 3b and the router 3c, the communication device existing in the lower subnetwork Since no other server function search request has been received, comparison cannot be made (No in step S1802). The router identification information and the IP header source address included in the server function search request received from the server function communication device 4b are stored in the storage unit 402, and a plurality of different routers are arranged in parallel below the router to which the server belongs. It is determined that they are not connected (step S1801), and the lower subnetwork existence determination process (step S1702) is terminated. As a result of the lower subnetwork existence determination process (step S1702), since it is determined that a plurality of different routers are not connected in parallel below the router to which the subnetwork belongs (Yes in step S1703), the message reception process is terminated. Thereafter, a server function switching message for instructing the server function to be invalidated is received from the server function communication device 4b (Yes in Step S2500, Step S2501 is executed, No in Step S1600, and Yes in S1602), and the server by message reception A function switching process is performed (step S1603). In server function switching processing by message reception (step S1603), server function switching processing by message reception is performed (step S1603). In the server function switching process (step S1603) by receiving a message, since the server function switching message instructing invalidation of the server function is received (No in step S1900 and Yes in step S1910), the service is provided. Information on the communication device with server function 4b to be replaced is notified to the communication device being replaced (step S1911), and its own server function is invalidated (step S1912).

[When a sub-network including a server-equipped communication device with the server function enabled is connected]
In FIG. 1, a network (router 3c and a communication device connected to the router 3c) including the communication device 4c with the server function in which the server function is enabled while the communication device 4b with the server function is enabled is newly provided. Processing when a lower subnetwork is newly connected will be described using a connected example. Note that the MAC address of the router 3a is 00-0E-7F-F9-87-28, the transmission source address is 192.168.1.1, the MAC address of the router 3b is 00-08-02-0A-DA-86, The source address is 192.168.2.220, the MAC address of the router 3c is 00-11-43-BD-BE-43, and the source address is 192.168.3.10.

  The server-equipped communication device 4c periodically performs communication device search processing with server function search (step S2503). In the communication device search processing with a server function (step S2503), the upper subnetwork analysis (step S1500) is performed, and the upper subnetwork (the network connected to the router 3a and the network connected to the router 3b) is newly connected. Is detected by the upper subnetwork analysis, the server-equipped communication device 4c transmits a server function search request to the upper subnetwork (step S1501). Similarly, a server function search request is transmitted to the peer network (step S1501). Here, since the server function-equipped communication device 4b connected to the router 3b of the higher-level subnetwork has validated the server function, the server function search response is received (Yes in step S1502). Since there is a server-equipped communication device in which the server function is enabled in the upper subnetwork and the server function is valid (Yes in step S1503), either of the communication devices with the server function that enables the server function is selected. On the other hand, server function arbitration processing is performed to reduce the number (step S1504). In the server function arbitration process (step S1504), the time during which the server function with the server function-equipped communication device 4b that has been discovered is validated is compared (step S2100). Here, it is assumed that the time when the communication device with server function 4c validates the server function is 5 minutes, and the time when the communication device with server function 4b validates the server function is 1 hour. As a result of comparing the time during which the server function with the server function with the server function 4b and the server function enabled is found, the time during which the server function is enabled is shorter (No in step S2101), and the server function Since the service is provided to the communication device 4c that does not have the service (Yes in step S2102), the information on the communication device 4b with the server function that replaces the communication device 3c that does not have the server function that provides the service is displayed. Notification is made (step S2104), the server function is invalidated (step S2103), and the subsequent operations are performed.

  On the other hand, since the communication device 4b with a server function is connected to the router 3c below the router 3b to which the server function belongs, and the communication device 4c with a server function is connected to each of the communication devices 4b with a server function, (Yes in Step S2500, Step S2501 is executed and Yes in Step S1600), and server function search request reception processing (Step S1601) is executed. In the server function search request reception process (step S1601), since the server function is valid (Yes in step S1700), a server function search response is transmitted to the communication device 4c with a server function (step S1701), and a lower subnetwork exists. A determination process (step S1702) is performed. In the lower subnetwork existence determination process (step S1702), the router identification information included in the received server function search request is compared with the identification information of the router to which it belongs (step S1800). What is the MAC address 00-08-02-0A-DA-86 of the router 3b to which it belongs and the MAC address 00-11-43-BD-BE-43 of the router 3c, which is router identification information included in the received packet? Because they are different (Yes in step S1800), the source address of the IP header of the received server function search request is compared with the source address of the IP header of the server function search request that has been received and stored in the storage unit 402 ( Step S1802). Here, since no subnetwork has existed in the lower level of the network including the communication device with server function 4b so far, a server function search request has not been received from any other communication device in the lower subnetwork. Cannot be performed (No in step S1802). The router identification information and the source address of the IP header included in the server function search request received from the server function communication device 4c are stored in the storage unit 402, and a plurality of different routers are arranged in parallel below the router to which the server belongs. It is determined that they are not connected (step S1801), and the lower subnetwork existence determination process (step S1702) is terminated. As a result of the lower subnetwork existence determination process (step S1702), since it is determined that a plurality of different routers are not connected in parallel below the router to which the subnetwork belongs (Yes in step S1703), the message reception process ends, and again Return to message reception waiting state.

[When a communication device with a server function detects that multiple different routers are connected in parallel underneath]
In FIG. 26, when the communication device with server function 4c has enabled the server function, the communication device with server function 4b detects that a plurality of different routers are connected in parallel below the router 3b to which it belongs. An example in which server function switching processing is performed will be described. The MAC address of the router 3b is 00-08-02-0A-DA-86, the transmission source address is 192.168.2.220, the MAC address of the router 3c is 00-11-43-BD-BE-43, The transmission source address is 192.168.3.10, the router 3d MAC address is 00-D0-59-67-7A-FE, and the transmission source address is 192.168.3.20.

  When the router 3d and the server-equipped communication device 4d are newly connected to the network, the server-equipped communication device 4d immediately performs the server-equipped communication device search process (step S2503) without waiting for a certain period of time. In the communication device search processing with a server function (step S2503), a higher-level subnetwork analysis is performed (step S1500), and the result of the higher-level subnetwork analysis is received. The server function search request is transmitted by unicast (step S1501), and at the same time, the server function search request is transmitted by multicast within the peer network (step S1501). The server function communication device that currently enables the server function is 4c, and there is no server function communication device that enables the server function in the upper subnetwork and peer network of the server function communication device 4d. There is no response to the search request (No in step S1502), and the server-equipped communication device search process (step S2503) is terminated. The communication device with server function 4d has not received a response to the server function search request in the communication device search processing with server function (step S2503) (No in step S2504), and is newly connected to the network. Since the server function of the server function unit / client function unit 406 is not activated (Yes in step S2505), it waits for reception of a server function search request from a subnetwork lower than a certain time. However, since there is no lower subnetwork, the message is not received within a predetermined time (No in step S2506 and Yes in step S2507). Therefore, it is determined that its own server function should be validated (step S2508), and server function switching processing (step S2509) based on appropriateness determination is performed. In the server function switching process (step S2509) based on appropriateness determination, since it is determined that it is a communication device that should enable the server function (Yes in step S2000), the server function is enabled (step S2000). S2003).

  On the other hand, the communication device with server function 4b always waits for reception of a message (step S2500). When the router 3d and the server-equipped communication device 4d are connected to the network, a server function search request is received from the server-equipped communication device 4d (Yes in Step S2500, Step S2501 is executed, and Yes in Step S1600). Server function search request reception processing (step S1601) is executed. In the server function search request reception process (step S1601), the server function search response is not transmitted because the server function is not valid (No in step S1700). The communication device that is the transmission source of the server function search request is the communication device 4d with the server function (Yes in step S1704), and the connection is made with the communication device 4c with the server function that has already enabled the server function. (Yes in step S1710), lower subnetwork existence determination processing (step S1702) is performed. In the lower subnetwork existence determination process (step S1702), the router identification information included in the received server function search request is compared with the identification information of the router to which it belongs (step S1800). What is the MAC address 00-08-02-0A-DA-86 of the router 3b to which the router itself belongs and the MAC address 00-D0-59-67-7A-FE of the router 3d which is router identification information included in the received packet? Because they are different (Yes in step S1800), the source address of the IP header of the received server function search request is compared with the source address of the IP header of the server function search request that has been received and stored in the storage unit 402 ( Step S1802). The server-equipped communication device 4c that currently has the server function enabled has a function of periodically performing higher-level subnetwork analysis and transmitting a server function search request to the higher-level subnetwork-equipped communication device with server function. The storage unit 402 of the communication device with server function 4b stores the MAC address and the transmission source address of the router 3c to which the communication device with server function 4c belongs. Server function search request source address 192.168.3.10 received from the server function communication device 4c and server function search request source address 192.168.3.20 received from the server function communication device 4d. (Yes in step S1802), it is determined that a plurality of different routers are connected in parallel below the router to which it belongs (step S1803). As a result of the lower subnetwork existence determination process (step S1702), it is detected that a plurality of different routers are connected in parallel below the router to which it belongs (Yes in step S1703), and its own server function is valid. Therefore, it is determined whether or not the communication device with the server function enabled exists in the host or peer network (step S1706). Since the server-equipped communication device that currently activates the server function is 3c and belongs to a router that exists below the router to which it belongs (No in step S1706), the communication device that should activate the server function is selected. It is determined that it should be changed (step S1708), and server function switching processing based on appropriateness determination is performed (step S1709). In the server function switching process (step S1709) based on appropriateness determination, it is determined that the communication device that activates the server function should be changed (No in step S200, No in step S2001, and in step S2002). Yes), a server function switching message for instructing activation of the server function is transmitted to the network and peer network of the upper router 3a (step S2005), and reception of a server function activation response is awaited (step S2006).

  At this time, the communication device 4a with a server function connected to the upper router 3a receives a server function switching message instructing the activation of the server function from the communication device 4b with a server function (Yes in step S2500, and executes step S2501). No in step S1600 and Yes in step S1602), server function switching processing by message reception is performed (step S1603). In the server function switching process (step S1603) by receiving a message, since the server function switching message for instructing the server function is received (Yes in step S1900), the server function is enabled (step S1901). ). Next, as a result of the upper subnetwork analysis (step S1500), it has been found that the router 3a to which the communication device with server function 4a is connected is the highest router, so that a server function search request is multicast only to the peer network. Transmit (step S1902). The communication device with server function 4c exists only in the peer network, and the server function search response is not received (No in step S1903 and No in step S1905). A server function switching message for instructing the server function to be invalidated is transmitted to 4d and 4d (step S1908), and a server function validation response is transmitted to the communication device with server function 4b (step S1909).

  Since the server-equipped communication device 4b has received the server function validation response from the server-equipped communication device 4a within a predetermined time (No in step S2007 and Yes in step S2006), the communication device that activates the server function is selected. The processing is terminated as it is switched.

  On the other hand, a server function switching message for instructing invalidation of the server function is received from the communication device with server function 4a (Yes in Step S2500, Step S2501 is executed, No in Step S1600, and Yes in Step S1602). The communication devices 4c and 4d perform server function switching processing by message reception (step S1603). In the server function switching process (step S1603) by receiving a message, since the server function switching message instructing invalidation of the server function is received (No in step S1900 and Yes in step S1910), the service is provided. Information on the communication device 4a with server function to be replaced is notified to the communication device being replaced (step S1911), and its own server function is invalidated (step S1912).

  Similarly, when the router 3d and the communication device 5d that does not have a server function are newly connected, the communication device 4b with a server function receives a server function search request from the communication device 5d that does not have a server function. As a result, it detects that a plurality of different routers are connected in parallel below the router to which it belongs, and changes the communication device to enable the server function.

[When a communication device that does not have a server function detects that multiple different routers are connected in parallel underneath]
In FIG. 26, when the communication device 4c with a server function is valid, the communication device 5b having no server function detects that a plurality of different routers are connected in parallel at the lower level. An example in which function switching processing is performed will be described. In FIG. 26, the communication device 4b with a server function is illustrated, but in the present embodiment, it is assumed that the communication device 4b with a server function does not exist. The MAC address of the router 3b is 00-08-02-0A-DA-86, the transmission source address is 192.168.2.220, the MAC address of the router 3c is 00-11-43-BD-BE-43, The transmission source address is 192.168.3.10, the router 3d MAC address is 00-D0-59-67-7A-FE, and the transmission source address is 192.168.3.20.

  When the router 3d and the server-equipped communication device 4d are newly connected to the network, the server-equipped communication device 4d immediately performs the server-equipped communication device search process (step S2503) without waiting for a certain period of time. In the communication device search processing with a server function (step S2503), a higher-level subnetwork analysis is performed (step S1500), and the result of the higher-level subnetwork analysis is received. The server function search request is transmitted by unicast (step S1501), and at the same time, the server function search request is transmitted by multicast within the peer network (step S1501). The server function communication device that currently enables the server function is 4c, and there is no server function communication device that enables the server function in the upper subnetwork and peer network of the server function communication device 4d. There is no response to the search request (No in step S1502), and the server-equipped communication device search process (step S2503) is terminated. The communication device with server function 4d has not received a response to the server function search request in the communication device search processing with server function (step S2503) (No in step S2504), and is newly connected to the network. Since the server function of the server function unit / client function unit 406 is not activated (Yes in step S2505), it waits for reception of a server function search request from a subnetwork lower than a certain time. However, since there is no lower subnetwork, the message is not received within a predetermined time (No in step S2506 and Yes in step S2507). Therefore, it is determined that its own server function should be validated (step S2508), and server function switching processing based on appropriateness determination is performed (step S2509). In the server function switching process (step S2509) based on appropriateness determination, since it is determined that it is a communication device that should enable the server function (Yes in step S2000), the server function is enabled (step S2000). S2003).

  On the other hand, the communication device 5b having no server function always waits for reception of a message including reception of a server function search request from a communication device connected to a lower router. In the process of estimating the address of a “communication device for which the server function is valid”, if the “communication device for which the server function is valid” is controlled to take a specific address range, and the peer network has a server function When there is no communication device, the communication device that does not have the server function may change the IP address to a predetermined address range, so that the communication device that does not have the server function also exists in the lower subnetwork. A server function search request transmitted by unicast from a communication device can be received in the same manner as a communication device with a server function. When the router 3d and the communication device with server function 4d are connected to the network, a server function search request is received from the communication device with server function 4d (No in step S2200 and Yes in step S2203). A determination process (step S2204) is performed. In the lower subnetwork existence determination process (step S2204), the router identification information included in the received server function search request is compared with the identification information of the router to which it belongs (step S2300). What is the MAC address 00-08-02-0A-DA-86 of the router 3b to which the router itself belongs and the MAC address 00-D0-59-67-7A-FE of the router 3d which is router identification information included in the received packet? Since they are different (Yes in step S2300), the source address of the IP header of the received server function search request is compared with the source address of the IP header of the server function search request that has been received and stored in the storage unit 502 ( Step S2301). The server-equipped communication device 4c that currently has the server function enabled has a function of periodically performing higher-level subnetwork analysis and transmitting a server function search request to the higher-level subnetwork-equipped communication device with server function. The storage unit 502 of the communication device 5b having no server function stores the MAC address and the transmission source address of the router 3c to which the communication device with server function 4c belongs. The source address of the server function search request received from the server-equipped communication device 4c is 192.168.3.10, and the source address of server function search request received from the server-equipped communication device 4d is 192.168.8.3. .20 (Yes in step S2301), it is detected that a plurality of different routers are connected in parallel below the router to which the router belongs, and the communication device with the server function enabled is connected to the upper or peer network. It is determined whether it exists (step S2302). The server-equipped communication device that currently enables the server function is 3c, and belongs to a router that exists below the router to which the server function belongs (No in step S2302), so the network and peer network of the upper router 3a A network configuration change notification message indicating that a plurality of different routers are connected in parallel below the router to which it belongs is transmitted (step S2303).

  On the other hand, the network configuration change notification is received (Yes in Step S2500, Step S2501 is executed, No in Step S1600, No in Step S1602, and Yes in Step S1604). Since it is detected that a network configuration in which a plurality of different routers are connected in parallel in the sub-network is found, and the server function is not activated (No in step S1605), the server function is activated. It is determined whether or not the communication device exists in the higher level or peer network (step S1606). Since the server-equipped communication device that currently activates the server function is 3c and belongs to a router that exists below the router to which it belongs (No in step S1606), the communication device that should activate the server function is selected. It is determined that it should be changed (step S1607), and server function switching processing based on appropriateness determination is performed (step S1608). In the server function switching process (step S1608) based on appropriateness determination, it is determined that the communication device with server function 4a connected to the upper router 3a should change the communication device that activates the server function (No in step S200). In addition, the router 3a to which the communication device 4a with the server function is connected based on the result of the upper subnetwork analysis (step S1500) is the highest-level router from the result of the upper subnetwork analysis (step S1500). Therefore, it is determined that there is no communication device that has activated the server function, and therefore, a server function switching message instructing activation of the server function is transmitted only to the peer network (step S2005). Waiting for reception (step S2006). Since the router 3a is the highest-level router and there is no other communication device with a server function in the peer network and does not receive a server function search response within a certain time (No in step S2006 and Yes in step S2007), itself The server function is activated (step S2008), and a server function switching message for instructing invalidation of the server function is transmitted to the server functions-equipped communication devices 4c and 4d that are currently validating the server function (step S2009).

  On the other hand, a server function switching message for instructing invalidation of the server function is received from the communication device with server function 4a (Yes in Step S2500, Step S2501 is executed, No in Step S1600, and Yes in Step S1602). The communication devices 4c and 4d perform server function switching processing by message reception (step S1603). In the server function switching process (step S1603) by receiving a message, since a server function switching message instructing invalidation of the server function is received (No in step S1900 and Yes in step S1910), the service is provided. Information of the communication device 4a with a server function to be replaced is notified to the communication device being replaced (step S1911), and its own server function is invalidated (step S1912).

  Similarly, when the router 3d and the communication device 5d having no server function are newly connected, the communication device 5b having no server function is similarly requested by the communication device 5d having no server function. , It detects that a plurality of different routers are connected in parallel below the router to which it belongs, and changes the communication device to enable the server function.

  In the present embodiment, the upper subnetwork analysis is periodically performed. However, the user has input means for inputting a signal to the communication device, and the upper subnetwork analysis is performed according to the signal of the input means. May be.

  A communication device replacement method and a communication device according to the present invention replace a communication device that supplies a service when a network configuration changes in a local network including one or more routers with a more optimal communication device. It is useful as a method. According to the present invention, a communication device can receive a service without depending on a network configuration. Further, the lower subnetwork presence determination means can be applied to the purpose of grasping the network configuration.

The figure which shows an example of a structure of the home network in Embodiment 1 of this invention The figure which shows an example of a structure of the home network in Embodiment 2 of this invention The figure which shows an example of the hardware constitutions of the communication apparatus in embodiment of this invention The figure which shows the functional block of the communication apparatus with a server function in Embodiment 1 of this invention. The figure which shows the functional block of the communication apparatus which does not have a server function in Embodiment 1 of this invention. The figure which shows the whole processing flow of the communication apparatus with a server function in Embodiment 1 of this invention. The figure which shows the processing flow of the communication apparatus search process with a server function of the communication apparatus with a server function in Embodiment 1 of this invention. The figure which shows the processing flow of the message reception process of the communication apparatus with a server function in Embodiment 1 of this invention. The figure which shows the processing flow of the server function switching process by the message reception of the communication apparatus with a server function in Embodiment 1 of this invention. The figure which shows the processing flow of the server function switching process by the appropriate judgment of the communication apparatus with a server function in Embodiment 1 of this invention. The figure which shows the processing flow of the communication apparatus which does not have a server function in Embodiment 1 of this invention. The figure which shows an example of the server function search request / response in Embodiment 1 of this invention The figure which shows the functional block of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows the functional block of the communication apparatus which does not have a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the communication apparatus search process with a server function of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the message reception process of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the server function search request reception process of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the low-order subnetwork presence determination process of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the server function switching process by the message reception of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the server function switching process by the appropriate judgment of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the server function arbitration process of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the communication apparatus which does not have a server function in Embodiment 2 of this invention. The figure which shows the processing flow of the low subnetwork presence determination process of the communication apparatus which does not have a server function in Embodiment 2 of this invention. The figure which shows an example of the server function search request / response in Embodiment 2 of this invention The figure which shows the whole processing flow of the communication apparatus with a server function in Embodiment 2 of this invention. The figure which shows an example of a structure of the home network in Embodiment 2 of this invention The figure which shows an example of the structure of the network in which the high-order subnetwork analysis process using the packet which changed TTL is used, and a TTL packet The figure which shows the processing flow of the process which acquires the network address of a router using the packet which changed TTL. The figure which shows the processing flow of a TTL packet transmission process The figure which shows an example of the TTL packet using UDP The figure which shows an example of the correspondence of TTL of a TTL packet, and a destination port number The figure which shows an example of the TTL packet using ICMP The figure which shows an example of the correspondence of TTL of a TTL packet, and a sequence number The figure which shows an example of a TTL response packet The figure which shows an example of the network where the high-order subnetwork analysis process using a UPnP IGD specification is used The figure which shows the processing flow of upper subnetwork analysis processing The figure which shows an example of the data part of an estimation router packet The figure which shows an example of the data part of an estimation router response packet The figure which shows an example of a GetExternalIPAddress action The figure which shows an example of the response with respect to GetExternalIPAddress action The figure which shows an example of the LAN side address of the high-order router guessed as a transmission destination of an estimated router packet The figure which shows the sequence of the replacement method of the conventional communication apparatus

Explanation of symbols

1 Internet 2 Home network 3a, 3b, 3c, 3d Router 4a, 4b, 4c, 4d Communication device with server function 5a, 5b, 5c, 5d Communication device 400, 500 Communication I / F unit 401 without server function 501 Upper sub-network determination unit 402, 502 Storage unit 403 Server function search / response unit 404 Server appropriateness determination unit 405 Server function switching unit 406 Server function unit / client function unit 503 Server function search unit 506 Client function unit 1307, 1407 Lower sub Network judgment part

Claims (18)

In a local network connected to an external network,
One or more routers exist between the communication device in the local network and the external network;
The local network is divided into one or more different subnetworks by the one or more routers;
Connected to any router of the local network,
A communication device having a function (server function) for providing a service to another communication device in the local network,
Server function discovery means for discovering another communication device having a server function existing in the local network;
At least server function appropriateness determining means for determining a communication device that should validate the server function using the result of the server function finding means,
A communication device having a server function, comprising: a server function switching unit that switches between valid and invalid of a server function based on a result of the server function appropriateness determining unit or a server function switching message from another communication device. The server function discovery means includes:
Server function search means for searching for another communication device having a server function existing in the local network;
A search response means for receiving a server function search packet from another communication device having a server function and transmitting a response packet to the server function search packet is provided. The server function search means exists in the local network. Send a server function search packet to another communication device having a server function to
Receiving a response packet from another communication device having a server function;
Or the search response means receives a server function search packet from another communication device having a server function.
To find a communication device having a server function,
A communication apparatus having the server function according to claim 1. Obtaining LAN side address information or LAN side address information and WAN side address information of one or more routers among routers located between a router to which the communication device having the server function is connected and an external network, Using the acquired address information, further comprising a higher-level subnetwork presence determination means for estimating and storing a range of addresses that can be taken by a communication device connected to the first network to which the acquired address information belongs,
The server function search means includes
Using the information of the address range of one or more of the first networks stored by the upper subnetwork presence determination means, an address that can be taken by a communication device having a server function is obtained, and a server function search addressed to the address Send packets,
A communication apparatus having the server function according to claim 2. The search response means includes
Receive a server function search packet from another communication device having a server function,
When the server function appropriateness determining means determines that the server function is a communication device that should enable the server function,
A communication apparatus having the server function according to claim 2. The server function suitability determining means includes
The server function discovery means is
In a network that belongs to a router to which a communication device having the server function is connected or another router (upper router) that exists between a router to which the communication device having the server function is connected and an external network,
If no other communication device having the server function is found, the device itself determines that the communication device should enable the server function,
When another communication device having a server function is found, it determines that it is a communication device whose server function should be disabled.
A communication apparatus having the server function according to claim 1. The server function switching means includes
If you switch your server function from enabled to disabled,
Send information of other communication devices that replace the server function to the communication device that is providing the service,
A communication apparatus having the server function according to claim 1. The server function switching means includes
When disabling its own server function,
Send information about the communication device that is providing the service to other communication devices that replace the server function.
A communication apparatus having the server function according to claim 1. The server function switching means includes
When the server function appropriateness determining means determines that it is a communication device that should enable the server function,
A server function switching message for instructing invalidation of the server function is transmitted to another communication device having the server function discovered by the server function discovery unit;
If your server function is not enabled, enable your server function,
When the server function appropriateness determining means determines that it is a communication device that should invalidate the server function,
If your server function is enabled,
A server function switching message for instructing the activation of the server function is transmitted to another communication device having the server function discovered by the server function discovery means;
Disable its own server functionality,
A communication apparatus having the server function according to claim 1. A lower subnetwork existence determination means for determining that a plurality of different routers are connected in parallel below a router to which the communication device having the server function belongs;
The lower subnetwork existence determination means includes:
Use a network configuration change notification message received from another communication device, or
Or
Using information contained in packets received from other communication devices in the local network,
It is determined that a plurality of different routers are connected in parallel below the router to which the communication device having the server function belongs,
The server function suitability determining means includes
Determining a communication device that enables a server function according to a result of the lower subnetwork presence determination means;
A communication apparatus having the server function according to claim 1. A packet received from another communication device in the local network includes information that can identify a router to which the other communication device in the local network is connected.
The lower subnetwork existence determination means includes:
By comparing at least information identifying the router included in a packet received from another communication device in the local network,
The communication device having a server function according to claim 9, wherein it is determined that a plurality of different routers are connected in parallel below a router to which the communication device having the server function belongs. The lower subnetwork existence determination means includes:
Receiving a plurality of packets containing router identification information different from the router identification information to which the communication device having the server function is connected;
And,
When the source address included in the IP header of the packet containing the received identification information of the different router is not the same,
The communication apparatus having a server function according to claim 10, wherein it is determined that a plurality of different routers are connected in parallel below a router to which the communication apparatus having the server function belongs. The server function suitability determining means includes
The server function discovery means is
In a local network connected to the external network,
If no other communication device having the server function is found, the device itself determines that the communication device should enable the server function,
When another communication device having a server function is found, it determines that it is a communication device whose server function should be disabled.
A communication apparatus having the server function according to claim 9. The server function suitability determining means includes
The server function discovery means is
Under the router to which the communication device having the server function belongs, another communication device having a server function that enables the server function has been found,
And,
The lower subnetwork existence determination means includes
When it is determined that a plurality of different routers are connected in parallel below the router to which the communication device having the server function belongs,
Judge that the communication device that activates the server function should be changed,
A communication apparatus having the server function according to claim 9. In a local network connected to an external network,
One or more routers exist between the communication device in the local network and the external network;
The local network is divided into one or more different subnetworks by the one or more routers;
Connected to any router of the local network,
A communication device having a server function in the local network, and a communication device that performs message communication with other communication devices,
Address range that can be set in the communication device connected to the LAN side network for one or more routers located between the router connected to the communication device having the server function and the external network An upper subnetwork existence determination means for obtaining and storing information on
Lower subnetwork existence determination means for determining that a plurality of different routers are connected in parallel below the router to which the communication device belongs,
A packet received from another communication device in the local network includes information that can identify a router to which the other communication device in the local network is connected.
The lower subnetwork existence determination means includes:
By comparing at least information identifying the router included in a packet received from another communication device in the local network,
Determining that a plurality of different routers are connected in parallel below the router to which the communication device belongs;
Communication device. The lower subnetwork existence determination means includes:
Receiving a plurality of packets containing router identification information different from the router identification information to which the communication device having the server function is connected;
And,
When the source address included in the IP header of the packet containing the received identification information of the different router is not the same,
The communication apparatus according to claim 14, wherein it is determined that a plurality of different routers are connected in parallel below a router to which the communication apparatus belongs. The lower subnetwork existence determination means includes:
When it is determined that a plurality of different routers are connected in parallel below the router to which the communication device belongs,
Using the information of the address range of one or more of the first networks stored by the upper subnetwork presence determination means,
For a network that belongs to a router to which the communication device is connected or another router (upper router) that exists between the router to which the communication device is connected and an external network,
Send network configuration change notification messages,
The communication apparatus according to claim 14. In a local network connected to an external network,
One or more routers exist between the communication device in the local network and the external network;
The local network is divided into one or more different subnetworks by the one or more routers;
Connected to any router of the local network,
A method of replacing a communication device having a function (server function) for providing a service to another communication device in the local network,
Discovering another communication device having a server function existing in the local network;
Determining a communication device for which the server function should be enabled;
And a step of switching between enabling and disabling the server function. A communication system,
In a local network connected to an external network,
One or more routers exist between the communication device in the local network and the external network;
The local network is divided into one or more different subnetworks by the one or more routers;
Connected to any router of the local network,
A communication device having a function (server function) for providing a service to another communication device in the local network;
A communication device connected to any router of the local network and having a server function in the local network, and a communication device that performs message communication with other communication devices;
The communication device having the server function is:
A server discovery unit for discovering other communication devices having a server function existing in the local network;
A server suitability determination unit that determines a communication device that enables the server function;
Including a server function switching unit that switches between enabling and disabling the server function,
Communications system.

Images