JP2016184882A - Control device and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To search for a node an IP address of which is erroneously set from a node in a sub-network.SOLUTION: A control device comprises: a communication unit (140) for transmitting and receiving packets on a sub-network; a search unit (170) for searching for a target node by transmitting a search request packet via the communication unit and receiving a search response packet; and a node information management unit (150) for passively detecting the presence of a start-up node on the sub-network every time a packet is received to manage the start-up node as node information. When transmitting the search request packet, the search unit transmits it to an IP address in the node information held by the node information management unit as a destination by unicast. At that time, for a node of which an IP address is erroneously set, the search unit transmits the search request packet having a MAC address in the corresponding node information as a destination MAC, and a dummy address close to the IP address set erroneously as a transmission source IP address.SELECTED DRAWING: Figure 8

Description

  The present disclosure relates to a control apparatus and system, and relates to a control apparatus and system for searching for a target device on a network.

Conventionally, as a protocol for a searcher device to search for a target device (hereinafter also referred to as a searchee device) on a network, an IP (Internet Protocol) level packet is generally used. Specifically, the searching device transmits a “search request packet” in a specific format in which a predetermined multicast address is a destination address and a predetermined port is a destination port, and a corresponding “search” The target device is found by receiving the “response packet”. As the destination address of the “search request packet”, a broadcast address may be used instead of the multicast address. On the other hand, when a search target device returns a “search response packet”, it is common to return the search device with a unicast address with the search device as a destination address. In order for the searching device to find the search target device, it is necessary that the outgoing “search request packet” reaches the search target device and the return “search response packet” reaches the search device.
However, depending on the network environment, multicast packets and broadcast packets may not be transferred. It is the router's role to transfer IP level packets, but multicast packets are not transferred if the multicast transfer function is not provided. Even if the router has a multicast forwarding function, multicast packets are often not forwarded because the multicast snooping function does not operate correctly. In addition, broadcast packets may not be transferred in rare cases. In particular, in a wireless LAN (Local Area Network) environment, the data may not be transferred. In such a network environment, since the “search request packet” does not reach the searched device, the searching device cannot find the searched device.

  Therefore, in addition to transmission by multicast or broadcast, a method of transmitting a “search request packet” with a destination address as a specific IP address by unicast is conceivable.

  However, even if the transmission is performed by unicast, if the IP address of the target device is set in error, the router cannot transfer the packet to the target device. Here, the IP address being set erroneously means that it is not within the network segment range defined by the router. You can check the network segment defined by the router on the router setting screen. For example, if the IP address on the LAN side is 192.168.11.1 and the subnet mask is 255.255.255.0, the IP address within the network segment range is 192.168.11. 2 to 192.168.11.254. A router will attempt to forward IP addresses that are outside the network segment it is responsible for to a higher router. Accordingly, since the packet is not transferred to the LAN side, the packet does not reach the target device.

  As a case where the IP address is set erroneously, for example, a case where DHCP (Dynamic Host Configuration Protocol) is set to invalid and a case where the router is replaced are assumed. Devices connected to the network are normally enabled with DHCP in the initial state, and when connected to the network, an IP address is dynamically allocated from the router. However, in the case where DHCP is set to be invalid, the IP address of the device becomes a static IP address, and there is a possibility that the IP address setting is incorrect. In the case where the router is replaced, if the IP address is not reset for each device by the router after replacement, the IP address setting of each device may be incorrect.

  Even if the search device is a target device with an incorrect IP address setting, it is desirable that the search device can find the device if it is connected to the same router.

  For example, Patent Document 1 (Japanese Patent Laid-Open No. 2009-49894) discloses a technique in which a search device searches for a target device as follows: “A system in which a plurality of devices communicate via a network, and other devices belonging to the system. In order to be discovered from a device, in order to discover a discovered device that has a function of performing small-scale communication with a neighboring router every predetermined time and other devices belonging to the above system, A network communication system including a discovery device having a function of confirming a desired device by acquiring connection device information from a router and communicating with the device described in the connection device information is disclosed.

JP 2009-49894 A

  However, Patent Document 1 does not show a configuration for finding a terminal device (or node) that is a terminal device (or node) connected to the same router but has an incorrect IP address setting. Therefore, in patent document 1, it cannot respond to said request.

  The present disclosure has been devised in view of such circumstances, and an object in one aspect thereof is to provide a control device and a system for searching for a node having an incorrect address setting among nodes connected to the same subnet. That is.

  According to one embodiment, a control device that searches for a target node on the same subnet of a network transmits a search request packet via a communication unit that transmits and receives packets on the subnet, and transmits a search response packet. A search unit that searches for a target node by receiving, and a node information management unit that passively detects the presence of an activation node on a subnet and manages it as node information each time a packet is received via a communication unit And comprising.

  When the search unit transmits a search request packet, the IP address of the node information in the node information management unit is transmitted as a destination IP address by unicast, but at this time, the IP address of the node information is set incorrectly. If it is determined that the destination MAC address is the MAC address of the node information in the node information management unit, a dummy address close to the erroneously set IP address is generated, and the dummy address is set as the source IP address. To transmit a search request packet.

  Preferably, the search unit further transmits an ARP reply for the ARP request having the dummy address as the sender IP address when receiving the ARP request having the dummy address as the search IP address after transmitting the search request packet. .

  Preferably, when the search unit receives a search response packet having the dummy address as the destination IP address, the control device outputs information indicating that the target node in which the IP address is set incorrectly is searched. .

  Preferably, the search unit transmits the search request packet by multicast and transmits the node information IP address in the node information management unit by unicast using the destination IP address as the destination IP address.

  Preferably, when the search unit transmits a search request packet, the search unit transmits the packet by broadcast, and transmits the IP address of the node information in the node information management unit as a destination IP address by unicast.

  According to another embodiment, a system including a plurality of nodes on the same subnet of a network and a control device that searches for a target node from the plurality of nodes is provided.

  The control device includes: a communication unit that transmits and receives packets on the subnet; a search unit that transmits a search request packet through the communication unit and receives a search response packet; and a packet through the communication unit. A node information management unit that passively detects the presence of an activation node on the subnet and manages it as node information.

  When the search unit transmits a search request packet, the IP address of the node information in the node information management unit is transmitted as a destination IP address by unicast, but at this time, the IP address of the node information is set incorrectly. If it is determined that the destination MAC address is the MAC address of the node information in the node information management unit, a dummy address close to the erroneously set IP address is generated, and the dummy address is set as the source IP address. To transmit a search request packet.

  According to an aspect of the present disclosure, the control device searches for a node in which an address different from the subnet address is set by receiving a search response packet for a search request packet having a dummy address as a transmission source ( Discovery).

2 is a diagram for explaining a schematic configuration of a communication network 1 according to Embodiment 1. FIG. FIG. 2 is a block diagram of a HEMS (Home Energy Management System) controller 100 in FIG. 1. It is a figure for demonstrating the software structure of the HEMS controller 100 of FIG. 6 is a diagram illustrating an example of a configuration of a node list 123 according to Embodiment 1. FIG. 6 is a diagram showing an example of a configuration of node information according to Embodiment 1. FIG. It is a figure which shows the structure of an ARP packet. It is a figure which shows the structure of arbitrary IP packets. 3 is a functional block diagram for explaining a functional configuration of a HEMS controller 100 according to Embodiment 1. FIG. 6 is a flowchart showing node information deletion processing according to the first embodiment. 6 is a flowchart showing a node list information update process when receiving an ARP request or an ARP reply according to the first embodiment. 7 is a flowchart showing information update processing of the node list 123 when an IP packet according to the first embodiment is received. It is a flowchart which shows the process which searches the target node which concerns on this Embodiment 1. It is a flowchart which shows the process which searches the target node which concerns on this Embodiment 2. FIG. It is a figure which shows an example of the subnet mask table | surface which concerns on Embodiment 1. FIG. FIG. 5 is a diagram schematically showing a search sequence using a dummy IP address according to the first embodiment. FIG. 16 is a diagram illustrating an example of a configuration of a search request packet in the search sequence of FIG. 15. It is a figure which shows an example of a structure of the ARP request of the search sequence of FIG. FIG. 16 is a diagram illustrating an example of a configuration of an ARP reply of the search sequence in FIG. 15. It is a figure which shows an example of a structure of the search response packet of the search sequence of FIG. 10 is a diagram illustrating an output example of information according to Embodiment 3. FIG.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Embodiment 1]
In the present embodiment, a search process for a target node (see FIGS. 1 to 19) is performed by a search device in a subnet. Further, in this search process, a search process using a dummy IP address (see FIGS. 14 to 19) is performed in order to search (discover) a search target device having an incorrect IP address setting as a target node. The

<Schematic configuration of communication network 1>
FIG. 1 is a diagram for explaining a schematic configuration of a communication network 1 according to the first embodiment. With reference to FIG. 1, the communication network 1 includes a wireless LAN router 302 and a subnet 10. The wireless LAN router 302 is connected to an external network 900 such as the Internet. A server device 901 such as a cloud server is connected to the network 900. The server device 901 communicates with a terminal 902 having a browser. The terminal 902 may be any terminal having a browser such as a smartphone, a tablet terminal, or a personal computer.

  The subnet 10 includes a HEMS controller 100, a plurality of nodes 201, 202, 203..., And a switching hub 300. A “node” is a communication device (IP compatible device) having an IP address. In general, the node includes a personal computer, a printer, a NAS (Network Attached Storage, also referred to as network storage), a tablet terminal, an AV (Audio Visual) device, and white goods. In FIG. 1, the wireless LAN router 302 is connected to the HEMS controller 100, the node 202, and the switching hub 300 via the wired LAN 803, and is connected to the node 203 via the wireless LAN 802. The node 201 is connected to the switching hub 300 and further connected to the wireless LAN router 302 via the switching hub 300.

  Some of the plurality of nodes 201, 202, 203,... Connected to the wireless LAN router 302 are “ECHONET Lite nodes” corresponding to ECHONET Lite devices. In the present embodiment, for example, the nodes 202 and 203 are ECHONET Lite nodes. Node 201 is a power monitor.

  The HEMS controller 100 functions as a control device in the communication network 1. Specifically, the HEMS controller 100 controls the plurality of nodes 201, 202, 203,... By communicating with the plurality of nodes 201, 202, 203,.

  In the present embodiment, the new node 209 may join the subnet 10, and a node participating in the subnet 10 (hereinafter also referred to as “existing node”) may leave the subnet 10. When the new node 209 joins the network, the new node 209 is treated as an existing node.

  Referring to FIG. 1, the numbers in parentheses (for example, 192.168.11.1) shown in relation to the wireless LAN router 302, the HEMS controller 100, and each node represent the IP address of the device or node. The wireless LAN router 302 has a DHCP function. The wireless LAN router 302 automatically assigns IP addresses as shown to the HEMS controller 100 and the plurality of nodes 202, 203,... By the DHCP function. The assigned IP address is stored in a storage unit included in each node, and in the HEMS controller 100, is stored in a storage unit 160 described later. The HEMS controller 100 and each node have a network adapter (not shown) such as a LAN card in which a MAC (Media Access Control) address indicating a unique number is preset (stored). Here, the MAC address is an example of “unique identification information” for the node or the HEMS controller 100, and the IP address is an example of “variable identification information” assigned to the node or the HEMS controller 100. is there.

  Referring to FIG. 1, it is assumed that the subnet mask of wireless LAN router 302 is set to 255.255.255.0. As can be seen from the IP address assigned by the wireless LAN router 302, the node used as a network address in the IP address (for example, “192.168.11” if “192.168.11.5”) is common. A group of the above constitutes one subnet 10 (divided network).

  The node 201 should normally be assigned “192.168.11.X” as the IP address. However, in FIG. 1, it is assumed that DHCP is disabled in the node 201 and a static IP address, for example, “192.168.100.100” is set. This IP address is not within the range of the subnet 10 managed by the wireless LAN router 302. Therefore, the HEMS controller 100 (searching device) cannot send and receive IP level packets to and from the node 201 (searched device) by a normal method.

  However, the HEMS controller 100 (searching device) can receive an ARP (Address Resolution Protocol) request transmitted from the node 201 (searched device). This is because the ARP request is transmitted and received at the MAC level. Therefore, the HEMS controller 100 can detect the node 201 as an activation node.

  In the present embodiment, even when an IP address is erroneously set in the node 201, the HEMS controller 100 can search for the node 201 at the IP level using a dummy IP address.

  In the present embodiment, the HEMS controller 100 is an example of a search device that is a subject that searches for a target node existing in the subnet 10, and each of the nodes 201, 202, 203,... It is an example of a search device. In the present embodiment, the “startup node” refers to a node that is turned on and activated. Further, in the present embodiment, “IP address incorrect setting” indicates that an IP address different from the IP address based on the subnet system of the subnet 10 is set in the search target device. Details of the search process by the search device and the search process using the dummy IP address described above will be described later.

<Configuration of HEMS controller>
FIG. 2 is a block diagram of the HEMS controller 100 of FIG. Referring to FIG. 2, HEMS controller 100 includes a CPU (Central Processing Unit) 1101. The HEMS controller 100 further includes a ROM (Read Only Memory) 1107 connected to the CPU 1101, a light emitting element 1103, a high-speed communication interface 1104, a power source 1105, a timer 1106 for measuring time (time), a RAM (Random Access Memory) 1102, A push button 1108, a slide switch 1109, and a reset switch (not shown) are provided.

  The CPU 1101 controls the overall operation of the HEMS controller 100. The CPU 1101 receives input from the push button 1108 and the slide switch 1109. In addition, the CPU 1101 outputs a light emission instruction to the light emitting element 1103.

  The ROM 1107 is a non-volatile memory device that stores programs, data that cannot be changed, and the like. The RAM 1102 is a volatile memory device in which a program is loaded and a work area and file system of the program, changeable data, and the like are stored. The high-speed communication interface 1104 is an interface that performs communication with the wireless LAN router 302 using Ethernet (registered trademark). The power source 1105 supplies power to each unit of the HEMS controller 100.

<Software configuration of HEMS controller 100>
FIG. 3 is a diagram for explaining a software configuration of the HEMS controller 100 of FIG. With reference to FIG. 3, the HEMS controller 100 includes at least a device-side application 110, a host-side application 120, and an upper layer 130. The device side application 110 includes a UDP (User Datagram Protocol) socket 111. The UDP socket 111 is used for transmission and reception. The host-side application 120 includes a UDP socket 121 for transmission and a RAW socket 122 for transmission / reception. The host-side application 120 stores a node list 123 (described later) in the RAM 1102.

  The device-side application 110 is an application for the HEMS controller 100 itself to behave as a controller class in ECHONET Lite. If there are requests from the nodes 201, 202, 203,..., The device-side application 110 receives them and transmits a response or notification to the request. The device side application 110 is not necessary for the present embodiment.

  The host-side application 120 receives a packet from the activation node connected to the subnet 10 through the RAW socket 122. The host-side application 120 maintains the information in the node list 123 in the latest state.

  The host-side application 120 further provides an API (Application Programming Interface) to the upper layer 130 (home appliance control application or the like). The host-side application 120 receives an instruction from the upper layer 130 and returns a list of the latest ECHONET Lite devices and the like to the upper layer 130. In addition, the host-side application 120 receives an instruction from the upper layer 130 and transmits a request to the node. Further, the host-side application 120 receives a notification or a response to the request from the node and returns it to the upper layer 130.

  The upper layer 130 includes a home appliance control application, a home appliance control CGI (Common Gateway Interface), and the like. These are independent of each other. Each communicates with the host-side application 120 independently. The home appliance control application can indirectly receive a user instruction from the terminal 902 by communicating with the server device 901.

  Each of the device-side application 110 and the host-side application 120 sets the destination UDP port number to 3610 when transmitting a packet. The source UDP port number may be arbitrary. When each of the device-side application 110 and the host-side application 120 receives a packet, it processes the packet whose destination UDP port number is 3610.

  The host-side application 120 opens the UDP socket 121 for transmission. As described above, the host-side application 120 arbitrarily sets the transmission source port number of the UDP socket 121.

  The host-side application 120 opens the RAW socket 122 for transmission / reception. The reason why the RAW socket 122 is opened is that the source MAC address is obtained at the same time when the packet is received. The RAW socket 122 receives all data that can be received by the network interface “eth0” among the data transmitted on the subnet 10. The host-side application 120 uses data having UDP / IP and destination UDP port number 3610 out of all received data. Alternatively, an ARP packet described later or an arbitrary IP packet is used.

  The HEMS controller 100 having the above configuration searches for a target node in order to control the target node on the subnet 10. More specifically, the HEMS controller 100 transmits a search request packet to the subnet 10 by multicast or broadcast. In addition, the HEMS controller 100 also transmits a search request packet by unicast. Here, the target node is a searched device. In the example of FIG. 1, the power monitor 201 and the ECHONET Lite nodes 202 and 203 are equivalent.

  In the present embodiment, the HEMS controller 100 manages the latest information (node information to be described later) of the startup node in the subnet 10 using the node list 123 (details will be described later). When transmitting the search request packet, the HEMS controller 100 transmits the search request packet by multicast or broadcast, and based on the node information of the node activated on the subnet 10, the search request having the IP address of the node information as the destination address Send the packet by unicast. Thereby, even in a network environment where multicast or broadcast is not transferred, the HEMS controller 100 can find the target node.

(Node list configuration)
In the node list 123 included in the HEMS controller 100, node information for managing the information of the “starting node” in the subnet 10 is registered. FIG. 4 is a diagram for explaining the configuration of the node list 123. The node list 123 is a container including a plurality of node information. There is one node information for each node found in the subnet 10. Various methods of configuring the node list 123 are conceivable, but it is preferable to configure a hash table so that target node information can be searched at high speed. A variable-length array (in the example of FIG. 4, there are 23 array elements from [0] to [22]) and each array element is configured by a link list. The length of the array is dynamically expanded as the number of node information increases. The configuration of FIG. 4 is a general hash table configuration. The node information includes at least the MAC address and IP address of the node.

  When reading node information from the node list 123, a search is performed based on the source MAC address that received the packet. Specifically, the hash value calculated from the MAC address by a predetermined hash operation is divided by the length of the array of the node list 123 (value 23 in the example of FIG. 4). Then, in the node list 123, the link list of the element corresponding to the value indicating the remainder is traced, and node information having a MAC address that matches the MAC address is read out.

  At the time of writing the node information, the hash value calculated from the MAC address of the transmission source that received the packet is divided by the length of the array of the node list 123 (value 23 in the example of FIG. 4) as before. . In the node list 123, the node information is registered at the beginning or end of the link list of the element corresponding to the value indicating the remainder.

  FIG. 5 is a diagram showing an example of the configuration of the node information according to the first embodiment. Referring to FIG. 5, the node information includes the MAC address and IP address of the node, the time at which the node information should be deleted from the node list 123, the pre-deletion ARP (Address Resolution Protocol) request transmitted flag, and the search request packet. At least a transmission counter is included.

  In the subnet 10, the state of the subnet 10 changes, such as the possibility that a node may join or leave as described above. In order to follow this change, node information whose activation is not confirmed must be deleted from the node list 123. The node information includes the time to be deleted, and is deleted when the time to be deleted is reached. For example, the time to be deleted is a time after a predetermined time (for example, after 15 minutes) from when the HEMS controller 100 last (recently) received the packet of the node information. The HEMS controller 100 updates the time to be deleted every time a packet is received from the node. Details of the method for setting the time to be deleted will be described later.

  The pre-deletion ARP request transmitted flag is used to determine whether or not the EMS request has been transmitted immediately before the HEMS controller 100 deletes the node information. If the pre-deletion ARP request transmission flag is 0, the ARP request is transmitted with the IP address of the node as the search IP address. If there is a response, the node information is not deleted. The initial value of the pre-deletion ARP request transmission flag is set to zero.

  The search request packet transmission counter counts the number of times that the HEMS controller 100 transmits a search request packet in order to check whether or not the node is the target node. Since the search request packet may not arrive, the search request packet is transmitted to the same node many times. The initial value of the search request packet transmission counter is zero.

<Packet configuration>
Data transmitted on the subnet 10 will be described. In the present embodiment, the transmission data has a packet configuration.

  FIG. 6 is a diagram illustrating a configuration of an ARP packet. The ARP request or ARP reply has the configuration of the ARP packet shown in FIG.

  Referring to FIG. 6, the ARP packet includes an Ethernet header part and an ARP protocol part. The Ethernet header part includes the MAC address of the destination node, the MAC address of the source node, and the type of the upper layer protocol. When the upper layer is an ARP packet, the type of this protocol indicates “ARP”.

  The ARP protocol section includes the type of physical network medium (Ethernet in this embodiment), the type of higher-level protocol handled by the ARP protocol (IP in this embodiment), and the length of the address used in the physical layer. And a protocol size indicating the length of an address used in the upper protocol. Furthermore, an OP code for indicating the type of ARP operation, a sender MAC address, a sender IP address, a search MAC address, and a search IP address are included. In the OP code, either “request” indicating an ARP request or “reply” indicating a response to the ARP request is set.

  The sender MAC address and the sender IP address indicate the MAC address and IP address of the node itself that transmitted the ARP request or ARP reply, respectively.

  When the ARP packet indicates an ARP request, the search MAC address is set to 0, and the search IP address is set to the IP address to be searched. When the ARP packet indicates an ARP reply, the MAC address and IP address of the transmission node of the corresponding ARP request are set in the search MAC address and the search IP address, respectively.

  FIG. 7 is a diagram illustrating a configuration of an arbitrary IP packet. Referring to FIG. 7, an arbitrary IP packet includes an Ethernet header part, an IP header part, and a payload part. The Ethernet header part includes the MAC address of the destination node, the MAC address of the source node, and the type of the upper layer protocol. When the upper layer is an IP packet, this protocol type indicates “IP”.

  The IP header part includes a header length indicating the version of the IP protocol and the size of the IP header part, a service type, a packet length, an identifier for the IP packet, a flag and a fragment offset, a TTL (time to live), an upper layer protocol number, And a header checksum for consistency checking. For example, if the upper layer is a UDP packet or a DHCP packet, “17” is entered in the upper layer protocol number. If the packet is an IGMP packet, “2” is entered.

  Furthermore, the IP header part includes a source IP address indicating the IP address of the source node of the IP packet and an IP address of the destination node of the IP packet. Further, the payload portion includes specific data of the upper layer. For example, if the upper layer is a UDP packet, a UDP header portion follows.

  In the present embodiment, when receiving a packet, the HEMS controller 100 and each node can determine whether the packet is an ARP packet or an IP packet based on the type of the packet.

<When the pair of MAC address and IP address is not correct>
When the HEMS controller 100 receives an arbitrary IP packet, there is a possibility that the combination of the source MAC address and the source IP address is not correct.

  For example, when an arbitrary IP packet is transmitted from a network beyond the wireless LAN router 302 (that is, a network different from the subnet 10), true transmission is performed for the source IP address of the IP packet. The IP address of the wireless LAN router 302 is set as the source MAC address.

  If the IP packet is a DHCP packet, the source IP address is uniformly set to 0.0.0.0. In such a case, it can be said that the combination of the source MAC address and the source IP address is not correct.

<Management of node list 123>
Next, management of the node list 123 by the HEMS controller 100 will be described. Although the node list 123 is empty in the initial state, information on the “starting node” in the subnet 10 is added or deleted by the management process of the node list 123.

  FIG. 9 is a flowchart showing processing for deleting node information from the node list 123 according to the first embodiment.

  FIG. 10 is a flowchart showing information update processing of the node list 123 when receiving an ARP request or ARP reply according to the first embodiment.

  FIG. 11 is a flowchart showing information update processing of the node list 123 when an arbitrary IP packet according to the first embodiment is received.

(Deleting node information)
A process of deleting node information from the node list 123 will be described with reference to FIG. The processing of FIG. 9 is executed periodically (for example, every 250 ms).

  First, the HEMS controller 100 takes out the next node information from the node list 123 (step S3). If there is no next node information (NO in step S5), the process is terminated. If there is next node information (YES in step S5), the HEMS controller 100 determines whether or not the node has timed out (time to be deleted) (step S7).

  If the node has not timed out (NO in step S7), the process returns to step S3. The next node information is extracted from the node list 123, and the processing from step S5 is similarly executed.

  If the node has timed out (YES in step S7), the HEMS controller 100 determines whether or not the pre-deletion ARP request transmission flag of the node is “0” (step S9).

  If the pre-deletion ARP request transmission flag is “0” (YES in step S9), the HEMS controller 100 transmits an ARP request with the IP address of the node as the search IP address. However, when the IP address of the node is 0.0.0.0 (since it is a temporary IP address), the node information of the node is immediately deleted without transmitting the ARP request (step S11).

  When the HEMS controller 100 transmits the above ARP request, the HEMS controller 100 sets the request transmission completion flag of the node information to “1” (step S13), and extends the time to delete the node by 10 seconds (step S15). ). Then, it returns to step S3.

  If the pre-deletion ARP request transmitted flag is not “0” in step S9 (NO in step S9), the HEMS controller 100 deletes the node information of the node from the node list 123 (step S17). Then, it returns to step S3.

  As described above, the HEMS controller 100 basically deletes the node information from the node list 123 when it is time to delete each node information, but whether or not the node is still activated immediately before the deletion. Send an ARP request (via RAW socket 122) to confirm If the ARP response (or any IP packet) cannot be received from the node within 10 seconds, the node information is deleted. If the ARP response (or any IP packet) can be received from the node, the node information is not deleted.

(Node information registration process)
When the HEMS controller 100 receives a packet through the RAW socket 122, the HEMS controller 100 registers the node information in the node list 123 based on the source MAC address. This target packet is an ARP reply or ARP request packet and an arbitrary IP packet.

-Registration process when receiving ARP reply / ARP request-
First, registration processing when an ARP reply or ARP request packet is received will be described with reference to FIG. The process of FIG. 10 is executed every time an ARP request or an ARP reply is received. The dummy IP address generated by the HEMS controller 100 is stored in the RAM 1102.

  However, in some cases, the source MAC address and the sender MAC address do not match. In this case, the HEMS controller 100 does not perform the processing of FIG. 10 (when a duplicate IP address is detected, the router also receives an ARP reply). May come). Therefore, the sender MAC address described in FIG. 10 is the same value as the source MAC address.

  First, the HEMS controller 100 determines whether an ARP request (see FIG. 17) in which a dummy IP address is set as a search IP address has been received based on the content of the received packet (step S18).

  When the HEMS controller 100 determines that the received packet is an ARP request in which a dummy IP address is set as the search IP address (YES in step 18), the HEMS controller 100 passes through the RAW socket 122. An ARP reply (see FIG. 18) is transmitted (step S19). Thereafter, the process proceeds to step S20. The processes in steps S18 to S19 correspond to a path P3 (ARP reply) in FIG.

  On the other hand, if the HEMS controller 100 determines that the received packet is not an ARP request in which a dummy IP address is set as the search IP address (NO in step 18), the process proceeds to step S20.

  In step S20, the HEMS controller 100 extracts node information from the node list 123 using the sender MAC address of the received packet (ARP request or ARP reply) as a key (step S20). It is determined whether there is node information that matches the sender MAC address (step S21).

  If there is no node information that matches the sender MAC address (NO in step S21), the HEMS controller 100 newly creates node information (step S22). The sender MAC address and sender IP address of the received packet are set as the MAC address and IP address of the node information, respectively. Further, the packet transmission counter of the node information is set to 0 (initial value).

  The HEMS controller 100 adds the newly created node information to the node list 123 and registers it (step S23). In addition, the HEMS controller 100 sets a time after 15 minutes from the current time to the time 53 when the received node information is to be deleted. Further, the pre-deletion ARP request transmission completion flag is set to 0 (initial value) (step S26).

  If there is node information that matches the sender MAC address in step S21 (YES in step S21), the HEMS controller 100 determines whether the IP address of the node information matches the sender IP address of the received packet. It is determined whether or not (step S24). If it is determined that they match (YES in step S24), in step S26, the same processing as described above (step S26) is executed for the node information.

  If the IP address of the node information does not match the sender IP address of the received packet (NO in step S24), the HEMS controller 100 updates the IP address of the node information to the sender IP address (step S24). S25). Thereafter, the process of step S26 is executed in the same manner as described above.

  10, the HEMS controller 100 updates the time at which the node information of the node should be deleted every time an ARP request or ARP reply is received, so as to indicate 15 minutes after the time when the packet is received ( Extend the time).

-Registration process when receiving any IP packet-
Next, registration processing when an arbitrary IP packet is received will be described with reference to FIG. The HEMS controller 100 executes the process of FIG. 11 every time an arbitrary IP packet is received. The arbitrary IP packet includes an IGMP packet, an ICMP (abbreviation of Internet Control Message Protocol) packet, a DHCP packet, a UDP packet, a TCP (abbreviation of Transmission Control Protocol) packet, and the like.

  Referring to FIG. 11, HEMS controller 100 extracts node information from node list 123 using the source MAC address of the received IP packet as a key (step S30). The HEMS controller 100 determines whether there is node information that matches the source MAC address (step S31). If there is node information that matches the transmission source MAC address (YES in step S31), the HEMS controller 100, as in the process of step S26 of FIG. The time after the lapse of minutes is set, and the request transmission completion flag is set to 0 (step S35).

  If there is no node information that matches the source MAC address (NO in step S31), the HEMS controller 100 newly creates node information (step S32). The HEMS controller 100 sets the source MAC address of the received packet as the MAC address in this node information, and also sets 0.0.0.0 as the IP address. Also, 0 is set in the packet transmission counter.

In the present embodiment, as described above in “(When the pair of MAC address and IP address is not correct)”, the pair of the source MAC address and source IP address of the received IP packet is always It is not always correct. Accordingly, the HEMS controller 100 temporarily sets 0.0.0.0 to the IP address of the newly created node information as described above.

  The HEMS controller 100 adds the newly created node information to the node list 123 (step S33).

  Further, the HEMS controller 100 transmits an ARP request in which the source IP address of the received IP packet is set to the search IP address (step S34). At this time, if the source IP address of the received IP packet indicates 0.0.0.0, the ARP request is not transmitted. Then, the process of step S35 is performed about the newly created node information.

  When the HEMS controller 100 receives the ARP reply for the ARP request after transmitting the ARP request in step S34, the HEMS controller 100 executes the process of step S25 according to the flow of FIG. As a result, the IP address of the node information initially set to 0.0.0.0 is updated to the correct IP address.

  Thus, in the case of FIG. 11 as well, as in FIG. 10, every time an HEMS controller 100 receives an arbitrary IP packet from a node, the time at which the node information of the node should be deleted is the time at which the packet is received. Update (extend time) to indicate 15 minutes later.

  Since the above-described deletion process (see FIG. 9) is executed based on the time to be deleted updated in FIG. 10 and FIG. 11, the node information is deleted while the activation is confirmed for the activation node. There is nothing. Therefore, the information regarding the “startup node” on the subnet 10 can be maintained in the latest state by the processing of FIGS. 9 to 11. The processes in FIGS. 9 to 11 are basically processes executed when a packet is received. This is why “passive detection of the presence of an activation node on the subnet 10” is performed.

<Target node search processing>
Next, processing in which the HEMS controller 100 searches for the target node on the subnet 10 will be described.

  In the present embodiment, the HEMS controller 100 transmits a search request packet to the subnet 10 and receives a search response packet corresponding thereto to find the target node. Here, finding the target node is also referred to as “successful search”.

  FIG. 12 is a flowchart of processing for searching for a target node according to the first embodiment. The HEMS controller 100 executes the processing of FIG. 12 at regular intervals (for example, every 3 minutes).

  Referring to FIG. 12, HEMS controller 100 transmits a search request packet in which the destination IP address is set to the multicast address (step S40). The multicast address and port number are determined in advance between the searching device and the searched device.

  For example, when the searched device is an ECHONET Lite (registered trademark) device, the multicast address is 224.0.23.0 and the port number is 3610.

  As another example, when the search target device is a UPnP (Universal Plug and Play-Simple Service Discovery Protocol) device, the multicast address is set to 239.255.255.250, and the port number is set to 1900.

  In the present embodiment, in order to reliably search for a target node on the subnet 10, the HEMS controller 100 generates a search request packet based on each node information in the node list 123 and transmits it by unicast (step). S41 and S42).

  Specifically, the HEMS controller 100 selects one destination IP address of the search request packet from the node information in the node list 123. In this selection, it is preferable to select the node information having the smallest search request packet transmission counter value from each node information of the node list 123. The search request packet is generated by setting the MAC address and IP address of the node information thus selected to the destination MAC address and the destination IP address, and transmitted by unicast.

  In the present embodiment, the node information having the IP address of 0.0.0.0 is excluded from the selection targets when the node information is selected in step S41 described above. This is because the IP address may not be updated after node information is newly created in step S32 (FIG. 11).

  The HEMS controller 100 also excludes nodes that have already received the search response packet from selection targets. This is because the node has already been successfully searched and does not need to be searched again. Further, the HEMS controller 100 also excludes node information whose packet transmission counter has reached an upper limit (for example, 30 times) from selection targets. This is because the fact that the search response packet is not received even though the search request packet is repeatedly transmitted to the node can be determined that the node is not the target node. It is. In step S41, when all the node information managed in the node list 123 is not the target, it is not necessary to transmit by unicast in step S41.

  When a search request packet is generated based on each node information of the node list 123 and transmitted by unicast (steps S41 and S42), the HEMS controller 100 determines “dummy IP address” for the device of the node information. "Search using" is executed (step S42a). Details of the “search using a dummy IP address” will be described later.

  When the HEMS controller 100 transmits the search request packet based on the IP address of the selected node information by unicast, the HEMS controller 100 increments the value of the search request packet transmission counter of the node information (step S43).

  The MAC address and IP address of the HEMS controller 100 are set in the source MAC address and source IP address of the search request packet.

  The HEMS controller 100 waits until a predetermined period (for example, 5 seconds) elapses in order to receive a search response packet for the search request packet (step S44).

  The search response packet has a configuration of an IP packet (see FIG. 7). Specifically, the MAC address and IP address of the source node are set in the source MAC address and source IP address of the search response packet, respectively.

  In step S44, the HEMS controller 100 may receive a plurality of search response packets (because the search request packet is transmitted by multicast). Therefore, it is necessary to always wait for a predetermined period (for example, 5 seconds) after transmitting the search request packet. If the search response packet is received within the predetermined period and it is confirmed that the content is a response to the previously transmitted search request packet, it is determined that the target node has been found. In this case, the HEMS controller separately manages the node information of the target node. Since this management method is not within the scope of the present invention, a description thereof will be omitted.

<Search using dummy IP address>
In the present embodiment, when the search device (HEMS controller 100) determines that the IP address is set in the search target device incorrectly, the search device (HEMS controller 100) performs a search using a search request packet having a dummy IP address. (Step S42a).

  The search using the dummy IP address will be described on the assumption that an activation node having “192.168.100.100” (hereinafter referred to as address (A)) is found as an IP address.

  For the search using the dummy IP address, the HEMS controller 100 determines whether the address (A) is an address of the subnet system of the subnet 10 to which the search device (HEMS controller 100) belongs. When the HEMS controller 100 determines that the address (A) is not an address of the subnet system, the HEMS controller 100 generates a dummy IP address. The HEMS controller 100 performs a search sequence for determining whether the activation node is the target node, using the generated dummy IP address. When the HEMS controller 100 determines that the address (A) is an address of the subnet system, the HEMS controller 100 performs a search sequence by a normal method.

a. Address Determination Process First, a process for determining whether the address (A) is an address of the subnet system of the subnet 10 will be described.

  The HEMS controller 100 determines whether the address (A) is an address of the subnet system from the IP address and subnet mask of the search device (HEMS controller 100). The HEMS controller 100 can acquire the IP address and subnet mask of the search device by a program.

  Specifically, when the IP address of the search device = 192.168.11.5 (hereinafter referred to as address (B)) and the subnet mask = 255.255.255.0 (hereinafter referred to as subnet mask (C)) are acquired, the HEMS The controller 100 acquires a network address according to the following calculation.

  In the calculation, the HEMS controller 100 first performs a first AND operation (bit AND) of the address (A) and the subnet mask (C). By this calculation, the address “192.168.100.0” is calculated. In addition, the HEMS controller 100 performs a second AND operation (bit AND) between the address (B) and the subnet mask (C). By this calculation, the address “192.168.11.0” is calculated. The HEMS controller 100 compares the calculated values of the first and second AND operations, and based on the comparison result, the calculated value of the first AND operation is different from the calculated value of the second AND operation. If it is determined, the HEMS controller 100 determines that the address (A) is not the address of the subnet system to which the search device (the activation node) belongs.

b. Dummy IP Address Generation Processing As described above, when it is determined that the address (A) (“192.168.100.100”) of the activation node is not a subnet address, the HEMS controller 100 determines the dummy IP address. Generate an address.

  The HEMS controller 100 generates the same IP address as that of the address (A) and is different from the address (A). However, the IP address to be generated must not overlap with the IP address of another activation node.

  In the dummy IP address generation process, in order to obtain a subnet mask corresponding to the same subnet system as the address (A), the HEMS controller 100 first selects a subnet mask having the narrowest address range that can be indicated by the subnet mask. Assume. Specifically, the HEMS controller 100 sets the subnet mask (class C, prefix / 30) having the narrowest address range from the subnet mask table of the IP address in FIG. 14, that is, the subnet mask “255.255.255.252”. Acquire (subnet mask is acquired by the program).

The HEMS controller 100 obtains dummy IP address candidates using the subnet mask “255.255.255.252”. The dummy IP address candidate is calculated by performing the following third AND operation (bit AND) using the address (A) “192.168.100.100” and the subnet mask “255.255.255.252”. The third AND operation is expressed by the following equation using a binary number.
11000000.10101000.01100100.01100100 (192.168.100.100)
11111111.11111111.11111111.11111100 (255.255.255.252)
-----------------------------------
11000000.10101000.01100100.01100100 (192.168.100.100)
The lower 2 bits of each value in the above formula indicate the bits of the host part. Therefore, the HEMS controller 100 can generate the following four IP addresses (= 2 ^ 2).
11000000.10101000.01100100.01100100 (192.168.100.100)
11000000.10101000.01100100.01100101 (192.168.100.101)
11000000.10101000.01100100.01100110 (192.168.100.102)
11000000.10101000.01100100.01100111 (192.168.100.103)
The HEMS controller 100 selects a dummy IP address according to a predetermined selection criterion from among a plurality of IP addresses (the above-mentioned four IP addresses) calculated by the third AND operation.

  According to this selection criterion, among the plurality of IP addresses, an IP address whose host part bits are all “1” and an IP address whose host part bits are all “0” are dummy IP addresses. Not selected. Also, among the plurality of IP addresses described above, an IP address that matches an IP address registered in a node list 123 (described later) that manages information on the activation node is not selected as a dummy IP address. For example, if “192.168.100.101” is already registered in the node list 123 among the above four IP addresses, “192.168.100.101” is not selected as a dummy IP address.

  Therefore, the HEMS controller 100 selects “192.168.100.102” as a dummy IP address according to the selection criterion among the four IP addresses calculated by the third logical product operation.

  When an IP address according to the selection criteria is selected from the IP address range (the above four IP addresses) calculated by the subnet mask “255.255.255.252”, the IP address is set as a dummy IP address. It is determined.

  On the other hand, if the IP address according to the selection criterion using the subnet mask “255.255.255.252”, that is, the dummy IP address is not determined, the HEMS controller 100 uses the new subnet mask to set the dummy IP address. Is generated. In other words, the HEMS controller 100 uses the subnet mask whose address range indicated by the subnet mask is the second narrowest (“255.255.255.248” of (class C, prefix / 29) in the table of FIG. 14) as described above. A dummy IP address is generated by the IP address generation process.

  As described above, the HEMS controller 100 is described above until the IP address (dummy IP address) according to the above selection criteria is acquired while switching the subnet mask in order from the smallest address range indicated by the subnet mask. The dummy IP address generation process is repeated. As a result, for a searched device in which an IP address is set incorrectly, a dummy IP address close to the incorrectly set IP address of the searched device (that is, the value of the incorrectly set IP address) IP address having a small difference from the IP address) is generated.

c. Search Sequence FIG. 15 is a diagram schematically showing a search sequence using a dummy IP address in the present embodiment. 16 to 19 are diagrams illustrating the configuration of a packet transferred in the search sequence of FIG. The premise of the search sequence shown in FIG. 15 is as follows.

  In the search device (HEMS controller 100), “MA1” is set as the MAC address, and “IA1” (192.168.11.5) is set as the IP address. In the search target device (node 201), “MA2” is set as the MAC address, and “IA2” (192.168.100.100) is set as the IP address. The searcher device determines that the IP address (192.168.100.100) of the searchee device determined to be the activation node is not the address of the subnet system to which the searcher device belongs (that is, the IP address set in error). The searching device generates “IA3” (192.168.100.102) as a dummy IP address based on the determination result.

  Assume that the searching device recognizes the presence of the node 201 in advance by monitoring an ARP packet or an arbitrary IP packet. That is, the searcher device can detect the node 201 as an activation node, and grasps the MAC address “MA2” and the IP address “IA2”. However, it is not yet known whether the node 201 is really the target device.

  The searching device transmits a search request packet (see FIG. 16) to determine whether the start node (searched device) is the target node (see path P1 in FIG. 15), and the search response packet (see FIG. 15). 19) (see path P4 in FIG. 15).

  With the search sequence of FIG. 15, in order for the searching device to successfully detect the searched device as the target device, the searching device can receive the search request packet and the searching device can receive the search response packet. Both are necessary.

-Transmission of search request packet-
Transmission of the search request packet in FIG. 15 will be described. The search device generates a search request packet that is an IP packet, and transmits the generated search request packet. The search request packet is generated based on the node information in the node list 123.

  The searcher device transmits a search request packet as a normal IP level packet. At this time, if the searching device determines that the destination IP address is an address different from the address of the subnet system to which the searching device belongs, the searching device normally tries to transfer the search request packet to the default gateway. Since the default gateway is normally set in the router, in this case, the searcher device tries to forward the search request packet to the router. When the search request packet is transferred to the router, the search request packet is not transferred to the LAN side because the destination IP address of the search request packet is outside the jurisdiction for the router. Therefore, the search request packet does not reach the searched device.

  However, in the first embodiment, the searcher device does not transmit the search request packet at the normal IP level, but causes the RAW socket 122 to generate the search request packet of FIG. 16 and transmits the generated search request packet. Let After all, the packet reaches the other party as long as the destination MAC address is set correctly at the Ethernet (registered trademark) level. If the RAW socket is used, the packet can be delivered to the search target device (node 201) without being transferred to the default gateway by directly setting the destination MAC address to “MA2”.

  Referring to FIG. 16, the MAC address “MA2” read from the node information in node list 123 is set as the destination MAC address of the search request packet. A dummy IP address “IA3” is set as the source IP address of the search request packet. The dummy IP address “IA3” indicates an address of the same subnet system as that of the searched device. In the present embodiment, setting a dummy IP address as a source IP address in a search request packet is referred to as “spoofing”.

  The reason for impersonating the above source IP address will be described. Originally, “IA1” should be set in the source IP address of the search request packet. However, when “IA1” is set as the source IP address, the searched device can receive the search request packet, but the searching device cannot receive the search response packet from the searched device. This is because the searchee device determines that the source IP address of the search request packet is an address of a different subnet system from the subnet to which the searchee device belongs, and based on the determination result, the search response packet is sent to the default gateway. Try to transfer. However, since the default gateway does not exist in the subnet 10, the searchee device cannot transmit a search response packet.

  Therefore, in the first embodiment, the searcher device disguises the source IP address of the search request packet as an address (dummy IP address) in the same subnet system as that of the searchee device. As a result, the searchee device can transmit a search response packet.

-Send ARP request-
When the search target device receives the search request packet of FIG. 16, in order to transmit a response (search response packet of FIG. 19) to the search device, it is necessary to first obtain the MAC address of the search device. That is, since the searchee device has not acquired the MAC address corresponding to the transmission source IP address “IA3” of the received search request packet, the searchee device can obtain an ARP request (see FIG. 17) is used to make an inquiry about the IP address “IA3”. The ARP request is usually an ARP packet transmitted at the OS (operating system) level.

-Send ARP reply-
When the searching device receives the ARP request from the searching device via the RAW socket 122, the searching device transmits an ARP reply (see FIG. 18). This corresponds to steps S18 to S19 in FIG.

  Specifically, when the searcher device determines that the received packet is an ARP request in which the IP address “IA3” is set as the search IP address based on the contents of the packet, the ARP reply (FIG. 18). Reply).

  The ARP reply is normally transmitted at the OS level, but in the first embodiment, the ARP reply is for searching for a device for a dummy IP address. There is no level, and an ARP reply is generated and transmitted by a dedicated program. The searching device responds with an ARP reply in response to the ARP request of the search IP address “IA3”.

-Transmission of search response packet-
When the searched device receives an ARP reply from the searching device, it transmits a search response packet (see FIG. 19) that is an IP packet. The search response packet reaches the search device.

  The searcher device determines whether the search response packet from the searchee device corresponds to the search request packet described above.

  If the searcher device determines that the received search response packet corresponds to the search request packet described above, the searcher device determines that the searchee device is the target node.

d. Specific Example of Search Sequence The search sequence in FIG. 15 will be described with a specific example. In this example, the IP address of the wireless LAN router 302 in the subnet 10 is “192.168.11.1”, the IP address of the search device (HEMS controller 100) is “192.168.11.93”, and the search target device (node 201). The IP address of the power monitor is the IP address “192.168.100.100” set in error.

  (Step 1) First, the searcher device transmits a search request packet (see FIG. 16) to the searchee device. Referring to FIG. 16, the search request packet includes the MAC address of the destination node, the MAC address of the source node, and the type of the upper layer protocol. The search request packet further includes a source IP address indicating the IP address of the source node and an IP address of the destination node. The search request packet further includes a payload that is specific data.

  The original IP address “192.168.11.93” of the search device should be set as the transmission source IP address of the search request packet. However, when the original IP address is set, the search request packet reaches the searched device, but the searching device cannot receive the corresponding search response packet from the searched device.

  The searcher device generates a dummy IP address (for example, “192.168.100.101”) having an address system of the same subnet as the partner (searched device) in order to be able to receive the search response packet. The search device transmits a search request packet in which the generated dummy IP address is set as the transmission source IP address via the RAW socket 122. The searched device receives the search request packet having the dummy IP address.

  (Step 2) When the searchee device receives the search request packet, the searchee device tries to return a search response packet to the transmission source IP address (“192.168.100.101”). The search response packet requires a destination IP address and a hardware address (MAC address).

  Since the searchee device does not know the hardware address of the transmission source IP address (“192.168.100.101”), an ARP request (see FIG. 17) is acquired to acquire the hardware address before transmitting the search response packet. Send. The ARP request is a packet that inquires the source of the search request packet.

  Referring to FIG. 17, the ARP request includes the MAC address of the destination node, the MAC address of the source node, and the type of the upper layer protocol. Further, the ARP request includes an OP code for indicating the type of ARP operation, a sender MAC address, a sender IP address, a search MAC address, and a search IP address.

  (Step 3) The searching device receives an ARP request from the searching device. When the search device determines that the search IP address of the received ARP request matches the dummy IP address (“192.168.100.101”), the search device transmits an ARP reply (see FIG. 18). The ARP reply indicates a response to the inquiry with the dummy IP address as the transmission source when the searching device receives the ARP request. Since the structure of the ARP reply packet is the same as that of the ARP request, description thereof will not be repeated.

  The searched device receives the ARP reply from the searching device. The searched device acquires the hardware address of the searching device from the received ARP reply. The searcher device transmits a search response packet (see FIG. 19) in which the dummy IP address and the acquired hardware address are set. Since the structure of the search response packet is the same as that of the search request packet, description thereof will not be repeated.

  (Step 4) The searcher device receives the search response packet transmitted from the searchee device. As a result, the searcher device discovers that the searchee device (the power sensor of the node 201) whose IP address is set incorrectly is connected in the subnet 10 to which the searcher device is connected.

  In step S42a of FIG. 12, the above-described “search using a dummy IP address” is performed. Specifically, the HEMS controller 100 first performs the above-described “address determination process” for the IP address of the node information of the activation node. In the “address determination process”, when it is determined that the IP address is not an address of the subnet system of the subnet 10 to which the search device (HEMS controller 100) belongs, the HEMS controller 100 determines that the “dummy IP address” "Generation process" is executed.

  A “search sequence” (see FIG. 15) using the generated dummy IP address is performed. The HEMS controller 100 uses the “search sequence” to find the activation node as a target node with an incorrect IP address setting.

  The search request packet (see FIG. 16) transferred in the “search sequence” in step S42a is counted in step S43. Also, the search response packet (see FIG. 19) transferred in the “search sequence” is also processed as a timeout measurement target in step S44.

[Embodiment 2]
The second embodiment is a modification of the first embodiment. In the first embodiment, the HEMS controller 100 transmits a search request packet by multicast when searching for a target node (see step S40 in FIG. 12). On the other hand, in Embodiment 2, the HEMS controller 100 transmits a search request packet by broadcast. Also in step S42 of FIG. 13, “search using a dummy IP address” (step S42a) is performed. Since the process of step S42a is the same as that shown in FIG. 12, the description thereof will not be repeated.

  Note that the HEMS controller 100 uses a search request packet depending on whether a search request packet is transmitted by multicast or broadcast. A discovery protocol is predetermined between the searching device and the searched device.

  In the second embodiment as well, the configuration and functions other than the point that the search request packet is transmitted by broadcasting are the same as those in the first embodiment, so that detailed description thereof will not be repeated. .

  FIG. 13 is a flowchart showing processing for searching for a target node according to the second embodiment. The HEMS controller 100 executes the process of FIG. 13 at regular intervals (for example, every 3 minutes).

  Referring to FIG. 13, the HEMS controller 100 transmits a search request packet in which the destination IP address is set to the broadcast address (step S40a).

  Unlike the multicast address, the broadcast address does not need to be determined in particular, but the port number is determined in advance between the searching device and the searched device.

  For example, when the search target device is a power monitor node manufactured by Sharp Corporation, the HEMS controller 100 transmits a search request packet in which the destination IP address is set to the broadcast address and the destination port number is set to 12132 by broadcast.

  As for the broadcast address, a limited broadcast address (255.255.255.255) with all bits of the IP address set to 1, and a directed broadcast with all the host part of the IP address set to 1 only. There is an address. For example, the IP address of each node in the subnet 10 is 192.168.11. When X and the subnet mask is 255.255.255.0, 192.168.11.255 is obtained. In any case, since it can be expected to reach each node of the subnet 10, either one may be used.

  Also in the second embodiment, the HEMS controller 100 generates a search request packet based on the IP address of each node information in the node list 123 and transmits it by unicast in order to reliably search for the target node on the subnet 10. (Steps S41 and S42). Also in this unicast transmission, the above-described “search using a dummy IP address” (step S42a) is performed.

  Since the processing after step S41 in FIG. 13 is the same as the processing described in FIG. 12, detailed description will not be repeated.

[Embodiment 3]
In the third embodiment, a modification of the first and second embodiments is shown. In the modification, the HEMS controller 100 has a function of outputting information (see FIG. 20) indicating that a target node in which an address different from the subnet system address of the subnet 10 is set is searched. FIG. 20 shows an output example of information based on a search sequence (see FIG. 15) using a dummy IP address.

  The HEMS controller 100 transmits the above information to the server device 901 via the wireless LAN router 302. The server device 901 stores information from the HEMS controller 100. When the user terminal 902 communicates with the server apparatus 901, the browsing function of the terminal 902 displays information stored in the server apparatus 901 on a display unit of the terminal 902 (see FIG. 20).

  In the information of FIG. 20, “XY” indicates the name of a target node having an IP address of a subnet system different from that of the HEMS controller 100 (for example, the class name of a power monitor or an ECHONET Lite node). In addition, the information in FIG. 20 indicates the MAC address “XX” of the device “XY”, and a message that prompts the user to change the IP address “ZZ” of the device “XY” to the IP address of the subnet system of the subnet 10 including. The user can change the IP address of the device according to the message. After the IP address of the device is changed to the IP address of the subnet system of the subnet 10, the HEMS controller 100 can communicate with the device (target node) at a normal IP level. It should be noted that the HEMS controller 100 can acquire the information of the above “XY”, “XX”, and “ZZ” from the content of the packet received from the target node (searched device).

<Functional configuration of HEMS controller>
FIG. 8 is a functional block diagram showing a functional configuration of the HEMS controller 100 according to each embodiment. Referring to FIG. 8, HEMS controller 100 includes a communication unit 140 that transmits and receives packets on subnet 10, node information management unit 150, storage unit 160, and search unit 170. The communication unit 140 includes functions of a RAW socket 122 and a UDP socket 121 that communicate via the high-speed communication interface 1104.

  The node information management unit 150 passively detects the presence of an activation node on the subnet 10. Specifically, every time a packet is received via the communication unit 140, as shown in FIG. 10 and FIG. 11, information related to the packet transmission source node is managed by the node list 123 as node information.

  The search unit 170 searches for a target node by transmitting a search request packet via the communication unit 140 and receiving a search response packet. As shown in FIG. 12, when searching for a search request packet, the search unit 170 transmits the search request packet by multicast and sends the search request packet to the address of the node information managed by the node information management unit 150 as a destination. Send by unicast.

  The search unit 170 may transmit the search request packet by broadcast as shown in FIG. 13 instead of the multicast transmission described above.

  In addition, the search unit 170 includes a dummy usage search unit 171. The dummy usage search unit 171 performs the “search using a dummy IP address” shown in step S42a.

  As shown in FIG. 9, if the node information is not updated for a predetermined time, the node information management unit 150 transmits a packet for confirming whether or not the node has been activated via the communication unit 140 and confirms it. If no response corresponding to the packet is received, the node information is deleted.

<Effect of Embodiment>
As described above, in each embodiment, the searching device can find a target device (searched device) in which an IP address is incorrectly set while being connected to the same subnet as the searching device. In addition, the searching device can present information (see FIG. 20) for assisting in changing the IP address of the discovered target device to a correct address to the user.

  Further, every time the communication unit 140 receives a packet, the node list 123 manages information related to the packet transmission source node as node information. As a result, it is possible to passively detect a node activated on the subnet 10 without generating unnecessary traffic.

  Further, when the HEMS controller 100 searches for a target node on the subnet 10, in addition to transmission of multicast or broadcast, a search request packet based on the node information of the node list 123 is transmitted by unicast. As a result, even in a network environment where multicast packets or broadcast packets do not reach the target node, the HEMS controller 100 can reliably find the target node.

  Further, since the search request packet is generated based on the node information in the node list 123 and transmitted to the subnet 10, the HEMS controller 100 can transmit only the search request packet to the active node. . Therefore, the HEMS controller 100 does not generate useless traffic for the target node search.

  It should be thought that embodiment disclosed this time and its modification are illustrations in all the points, and are not restrictive. The scope of the present disclosure is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Communication network, 302 Wireless LAN router, 10 subnets, 100 HEMS controller, 110 Device side application, 120 Host side application, 140 Communication part, 150 Node information management part, 160 Storage part, 170 search part, 171 Dummy use search part

Claims (7)

A control device that searches for a target node on the same subnet of a network,
The control device includes:
A communication unit that transmits and receives packets on the subnet;
A search unit for searching for a target node by transmitting a search request packet via the communication unit and receiving a search response packet;
A node information management unit that passively detects the presence of an activation node on a subnet and manages it as node information each time a packet is received via the communication unit;
With
When the search unit transmits the search request packet, the IP address of the node information in the node information management unit is transmitted as a destination IP address by unicast,
At this time, if it is determined that the IP address of the node information is set in error, the MAC address of the node information in the node information management unit is set as the destination MAC address, and is close to the IP address set in error A control device that generates a dummy address and transmits the search request packet using the dummy address as a source IP address. The search unit further includes:
The ARP reply for the ARP request having the dummy address as a sender IP address is transmitted when an ARP request having the dummy address as a search IP address is received after the search request packet is transmitted. Control device. When the search response packet having the dummy address as a destination IP address is received by the search unit,
The control device includes:
The control device according to claim 1, wherein the control device outputs information indicating that a target node having an IP address set incorrectly is searched.   4. The search unit according to claim 1, wherein when the search request packet is transmitted, the search unit transmits the packet by multicast and transmits the IP address of the node information in the node information management unit as a destination IP address by unicast. 5. The control apparatus in any one.   4. The search unit according to claim 1, wherein when the search request packet is transmitted, the search unit transmits the packet by broadcast, and transmits the IP address of the node information in the node information management unit as a destination IP address by unicast. 5. The control apparatus in any one. A system comprising a plurality of nodes on the same subnet of a network, and a control device for searching for a target node from the plurality of nodes,
The control device includes:
A communication unit that transmits and receives packets on the subnet;
A search unit for searching for a target node by transmitting a search request packet via the communication unit and receiving a search response packet;
A node information management unit that passively detects the presence of an activation node on a subnet and manages it as node information each time a packet is received via the communication unit;
With
When the search unit transmits a search request packet, the node information IP address of the node information in the node information management unit is transmitted as a destination IP address by unicast, but the IP address of the node information is incorrect. If the destination address is the MAC address of the node information in the node information management unit, a dummy address close to the erroneously set IP address is generated, and the dummy address is A system for transmitting the search request packet using a source IP address. The system further comprises a user terminal,
The system according to claim 6, wherein the user terminal displays on the screen information indicating that a target node having an IP address set incorrectly is searched.

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