JP6111607B2 - Network topology estimation device, network topology estimation method and program - Google Patents

Description

  The present invention relates to a technique for estimating a network topology.

  In the field of smart grids and M2M (Machine to Mchine) networks, specific information that changes over time, such as sensor devices and environmental information measurement equipment, is usually provided for each local area such as an office, factory, home, and automobile (for example, A detection device that acquires environmental information, power information, temperature information, vibration information, sound information, and the like, and an actuator device that operates the machine are installed.

  The detection device and the actuator device are not only an internal server which is an information processing apparatus installed in each local area, but also via a communication network (Internet network, 3G network, LTE network, Wimax network, PHS network, PLC communication network, etc.) In some cases, communication is also performed with an external server that is an information processing apparatus connected in this manner. In this case, the information acquired by the detection device is not only processed by the internal server but also by the external server, and the actuator device is controlled not only by the internal server but also by the external server.

  For example, power consumption information acquired by a power meter that is a sensor device in each home is not only processed by an internal server installed in each home, but also a company that supplies power (a power generation company, a power transmission company, or a power distribution company). It may also be processed by an external server installed in the company.

  In recent years, processing and control by external servers have been conducted in recent years, particularly in the smart grid field, automatic meter reading using smart meters such as power smart meters, gas smart meters and water smart meters, remote control or automatic control of related equipment, and other value-added services. It is attracting attention from the viewpoint of application. In this case, each smart meter is a sensor device or an actuator device.

  Also, in the fields of smart grids and M2M networks as described above, and other fields such as home networks, office networks, and outdoor communication networks, a plurality of nodes that transmit and receive information are autonomously called wireless multi-hop networks. Wireless multi-hop communication that builds the network is attracting attention. Wireless multi-hop communication eliminates the need for communication infrastructure provided by carriers and the like, so it is possible to expand communication areas, improve communication efficiency, improve communication availability, durability, reliability, and speed. .

  For example, in the field of smart grids, using a smart meter as a node, it is considered to construct a sensor network that collects various types of information and controls related devices with a wireless multi-hop network. In addition, by using Wifi devices such as smartphones as nodes, it is considered to construct an ad hoc network that transmits all information from a transmission source node to a transmission destination node by wireless multihop communication as a wireless multihop network. Yes.

  Hereinafter, devices (such as sensor devices, actuator devices, and WiFi devices) that can be used as nodes for constructing a wireless multi-hop network are collectively referred to as wireless devices. Note that ZigBee, Z-Wave, IEEE802.11, and the like are typical examples of communication methods for communication performed by the wireless device, but this communication method is not limited to these examples.

  In order to provide services continuously, there may be failures in the provision of services using wireless multi-hop networks when failures or malfunctions occur in wireless devices that are nodes of wireless multi-hop networks. It is necessary to manage the state of each wireless device.

  Management of wireless devices may be performed by an end user who installs or uses each wireless device, but since end users are usually general consumers, they have specialized knowledge to manage wireless devices. Often not. For this reason, it is desirable for a specialist who has specialized knowledge to manage the wireless device to remotely manage the state of the wireless device.

  When a special technology is used for remote management of wireless devices, problems such as an increase in cost and a decrease in versatility arise. For this reason, it is desirable to use standard remote management technology, which is a standard technology for realizing remote management, for remote management of wireless devices. Known standard remote management techniques include TR-069 (see Non-Patent Document 1) and OMA-DM, which have been developed for the purpose of managing broadband routers, STB (Set Top Box), 3G communication devices, and the like. Yes.

  In the above-mentioned standard remote management technology, a management device that performs remote management communicates individually with a terminal to be managed, obtains management information indicating the status of each terminal, transmits instructions to each terminal, etc. The terminal status is managed. As a wireless device management method using this technology, a gateway as a management apparatus transmits a request message for requesting notification of management information to each wireless device, and the wireless device responds with management information according to the request message. The method of returning to the gateway is general. The management information includes, for example, the MAC address, network address, and routing information (such as the network address of the parent device) of the wireless device, and the gateway uses the management information to determine the network topology that is the connection relationship of each wireless device. It is possible to manage network topology information indicating

  In addition, since many wireless devices are driven by a battery, power saving of wireless devices is required to extend the life of wireless multi-hop networks and wireless devices. However, when remote management of wireless devices is performed, each wireless device performs communication for remote management, which causes a problem that power consumption increases.

  This can be solved by suppressing the transmission frequency of the management information by the wireless device.

The Broadband Forum, "CPE WAN Management Protocol BBF TR-069", [online], November 2010, [retrieved on October 23, 2012], Internet <URL: http://www.broadband-forum.org/technical /download/TR-069_Amendment-3.pdf>

  However, when the transmission frequency of management information is suppressed as described above, or when packet loss frequently occurs due to wireless conditions, the network topology that is the connection relationship of each wireless device is frequently changed, particularly in a situation where the actual network is changed. It may be difficult to manage network topology information indicating the topology.

  Specifically, when transmission of management information is suppressed or packet loss occurs for management information, the gateway can acquire only a part of the management information of each wireless device, and as a result, Inconsistencies may occur in the network topology information.

  For example, when the correct network topology is a tree topology (tree topology), if some management information is lost, the network topology indicated by the network topology information managed by the gateway is no longer a tree topology, and the correct network topology It may become impossible to manage.

  11 and 12 are diagrams for specifically explaining the above problem.

  In FIG. 11, for each of a plurality of nodes that are wireless devices constituting a wireless multi-hop network, MAC addresses (A, B, C,...) Used as node identifiers for identifying the nodes and multi-hop communication are used. Necessary network addresses (0001, 0002, 0003,...) Are assigned. Further, it is assumed that the wireless multi-hop network is set to have a network tree topology. Hereinafter, nodes having MAC addresses A, B, C,... Are referred to as node A, node B, node C,.

  Network topology information is managed by a gateway (GW). Further, in the tree topology, the network topology information includes the connection relationship of each node, the network address of each node (local NWK and local NWK address in the figure), and the network address of the parent node of each node (parent NWK in the figure). And the parent NWK address).

  In the above situation, it is assumed that the nodes C, F, and G reconnect to the wireless multi-hop network, and as a result, the network addresses of the nodes C, F, and G have changed. Specifically, it is assumed that the network address of node C has changed from 0003 to 1003, the network address of node F has changed from 0006 to 1006, and the network address of node G has changed from 0007 to 1007. Further, it is assumed that the parent node of the nodes F and G is the node C regardless of before and after the reconnection.

  After the reconnection of the nodes C, F and G, the gateway receives the management information from the nodes F and G, but transmission of the management information from the nodes other than the nodes F and G is suppressed (or Suppose that management information could not be received (due to packet loss of management information). In this case, when the gateway updates the network topology information, the connection relationship regarding the nodes F and G is updated based on the received management information, but the connection relationship regarding the node C receives the latest management information. Since there is not, it will update based on the past management information.

  For this reason, the network address of the node C, which is the parent node of the nodes F and G, is 0003 in the network topology information even though it is actually 1003. In this case, the parent nodes of the nodes F and G are unknown on the network topology information, and the gateway cannot grasp an appropriate network topology.

  Also, at 12, as a result of nodes C, D, E, and F reconnecting to the wireless multi-hop network, the network addresses of nodes C, D, F, and G change, after which the gateway Only management information is received.

  Note that the network address of node C changes from 0003 to 0007, the network address of node D changes from 0004 to 0003, the network address of node E changes from 0005 to 0008, and the network address of node F changes from 0006 to 1009. Suppose that The parent nodes of the nodes C and D are the node B, the parent node of the node E is the node C, and the parent node of the node F is the node D.

  In this case, the network topology indicated by the updated network topology information is the administrative network topology shown at the bottom of FIG. In this example, in addition to the occurrence of a node F whose parent node is unknown, a node E having a plurality of nodes (specifically, nodes C and D) as parent nodes is generated. In a tree topology, a node does not have multiple nodes as parent nodes. Therefore, the nodes E and F deviate from the appropriate network topology, and the gateway cannot grasp the appropriate network topology.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a network topology estimation apparatus, a network topology estimation method, and a program capable of estimating more accurate network topology information.

The network topology estimation apparatus according to the present invention is:
A node other than the root node having no parent node is a network topology estimation device for estimating a network topology in a tree topology having only one parent node,
Current network topology information indicating a current connection relationship between nodes constructing a network, and past network topology information indicating a past connection relationship between the nodes,
From the current network topology information, an estimation target node that is a node having a connection relationship that does not conform to a predetermined rule having a network topology as a tree topology is selected, and an actual connection relationship of the estimation target node is determined as the past based on the network topology information have a, an estimation unit that estimates of,
Each of the current network topology information and the past network topology information indicates a parent-child relationship between the nodes;
The estimation unit selects a node having a parent node that does not conform to the rule as the estimation target node, and an actual parent node of the estimation target node is a parent node of the estimation target node in the past network topology information. Estimated as a certain original parent node .

A network topology estimation method according to the present invention is a network topology estimation method for estimating a network topology in a tree topology in which nodes other than a root node having no parent node have only one parent node,
Current network topology information indicating a current connection relationship between nodes constructing a network, and past network topology information indicating a past connection relationship between the nodes,
From the current network topology information, an estimation target node that is a node having a connection relationship that does not conform to a predetermined rule having a network topology as a tree topology is selected, and an actual connection relationship of the estimation target node is determined as the past estimated based on network topology information,
Each of the current network topology information and the past network topology information indicates a parent-child relationship between the nodes;
A node having a parent node that does not conform to the rule is selected as the estimation target node, and an actual parent node of the estimation target node is an original parent node that is a parent node of the estimation target node in the past network topology information Estimate .

The program according to the present invention is a program for causing a computer to execute network topology estimation for estimating a network topology in a tree topology in which nodes other than the root node having no node have only one parent node,
A computer having current network topology information indicating a current connection relationship between nodes constructing a network and past network topology information indicating a past connection relationship between the nodes;
From the current network topology information, an estimation target node that is a node having a connection relationship that does not conform to a predetermined rule having a network topology as a tree topology is selected, and an actual connection relationship of the estimation target node is determined as the past estimated based on network topology information,
Each of the current network topology information and the past network topology information indicates a parent-child relationship between the nodes;
A node having a parent node that does not conform to the rule is selected as the estimation target node, and an actual parent node of the estimation target node is an original parent node that is a parent node of the estimation target node in the past network topology information The estimation procedure is executed.

  According to the present invention, more accurate network topology information can be estimated.

It is a figure which shows an example of the communication system of 1st embodiment of this invention. It is a figure which shows the other example of the communication system of 1st embodiment of this invention. It is a figure for demonstrating an example of the network topology estimation change process in 1st embodiment of this invention. It is a block diagram which shows the structural example of the gateway in 1st embodiment of this invention. It is a flowchart in order to demonstrate the operation example of the gateway in 1st embodiment of this invention. It is a figure for demonstrating an example of the network topology estimation change process in 2nd embodiment of this invention. It is a block diagram which shows the structural example of the gateway in 2nd embodiment of this invention. It is a flowchart in order to demonstrate the operation example of the gateway in 2nd embodiment of this invention. It is a figure for demonstrating an example of the network topology estimation change process in 3rd embodiment of this invention. It is a block diagram which shows the structural example of the gateway in 3rd embodiment of this invention. It is a flowchart for demonstrating the operation example of the gateway in 3rd embodiment of this invention. It is a figure for demonstrating an example of the problem of related technology. It is a figure for demonstrating the other example of the problem of related technology.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, components having the same function may be denoted by the same reference numerals and description thereof may be omitted.

  In each of the following embodiments, management information is notified only from some nodes after the connection relationship of each node that constructs a wireless multi-hop network such as a sensor network or an ad hoc network has changed. A configuration and operation for estimating an actual network topology that conforms to the network topology management rule when network topology information that does not conform to the network topology management rule is created will be mainly described. Note that a general wireless device such as a sensor device, an actuator device, and a WiFi device can be used as the node.

(First embodiment)
The feature of the first embodiment is that an actual network topology that conforms to the network topology management rule is estimated by estimating the network address of the parent node in a node whose parent node is unknown based on past network topology information. Is to estimate.

  FIG. 1A is a diagram illustrating a communication system according to the present embodiment. As shown in FIG. 1A, the communication system includes a plurality of nodes 1 that construct a wireless multi-hop network, and a gateway (GW) 2 that performs remote management of each node 1.

  Each node 1 is a wireless device capable of constructing a wireless multi-hop network.

  The network topology that is the connection relationship of each node 1 is determined according to a network topology management rule predetermined for the gateway 2. The network topology management rule is a rule that defines the type of network topology, and in this embodiment, the network topology is a tree topology (tree topology). In the tree topology, nodes other than the root node that do not have a parent node have only one parent node.

  Each node 1 is assigned a MAC address (A, B, C,...) Used as a node identifier for identifying the node and a network address (0001, 0002, 0003,...) Necessary for multihop communication. ing. Hereinafter, the node 1 having the MAC addresses A to G may be referred to as nodes A to G, respectively.

  The gateway 2 creates and stores network topology information indicating the network topology, and uses the network topology information as a network topology estimation device that estimates an actual connection relationship of the node 1 having a connection relationship that does not conform to the network topology management rule. It has a function.

  Specifically, the gateway 2 stores, as network topology information, current network topology information indicating a current connection relationship between nodes and past network topology information indicating a past connection relationship between nodes.

  Then, the gateway 2 transmits a request message for requesting notification of management information to each of the nodes A to G at a predetermined timing, and then sends management information as a response message to the request message from each of the nodes A to G. Receive. Each node A to G may suppress notification of management information depending on the situation. Even if each node A to G transmits management information, the management information may be lost due to packet loss, and the gateway 2 may not receive the management information.

  Thereafter, the gateway 2 updates the current network topology information and the past network topology information based on the received management information. At this time, in the updated current network topology information, when there is an estimation target node that is a node having a connection relationship that does not conform to the network topology management rule, the gateway 2 sets the actual connection relationship of the estimation target node in the past. Based on the network topology information, estimation is performed, and based on the estimation result, the current network topology information is corrected to create post-estimation network topology information.

  The management information is information for remotely managing each of the nodes A to G. At least the MAC address of each of the nodes A to G and the own network address that is the network address of each of the nodes A to G; And a parent network address that is a network address of the parent node of each of the nodes A to G. These pieces of information are used for specifying the connection relationship between the node and other nodes. In addition to these information, the management information includes manufacturing vendor information (vendor name and vendor code), device model name, serial number, type information of the power source used, surplus power information (remaining battery information), It may include link quality information, software modules to be held, and the like.

  Note that the network topology shown in FIG. 1A is merely an example, and the present invention is not limited to this. For example, the communication system may be as shown in FIG. 1B. 1A and 1B, nodes A to G are assigned "0001" to "0007" as their own network addresses.

  FIG. 2 is a diagram for explaining an example of an estimation change process for estimating the network topology by the gateway 2 of the present embodiment and creating the estimated network topology information.

  In FIG. 2, actual network topology 3A, current network topology information 11 and past network topology information 12 are shown.

  In an actual network topology 3A, nodes C, F, and G reconnect to the wireless multi-hop network in the situation shown in FIG. 1A, and as a result, the network addresses of nodes C, F, and G have changed. is there.

  The current network topology information 11 is created when only the nodes F and G notify the gateway 2 of management information after the network addresses of the nodes C, F, and G change. The past network topology information 12 indicates the network topology shown in FIG. 1A (that is, the network topology before the network addresses of the nodes C, F, and G change).

  The gateway 2 creates the estimated network topology information 13 by performing the following processing.

  1: First, the gateway 2 is a node having a network address that does not exist as its own network address as a parent network address in the current network topology information 11 as an estimation target node that is a node having a connection relationship incompatible with the network topology management rule. Select F and G. That is, there is no node having the parent network address “1003” of the estimation target nodes F and G as its own network address.

  2: Subsequently, the gateway 2 selects the node C to be the parent node of the estimation target nodes F and G in the past network topology information 12 as the original parent mode.

  3: Further, the gateway 2 estimates that the actual parent nodes of the estimation target nodes F and G are still in the original parent mode, and calculates the actual parent network addresses of the estimation target nodes F and G as the current network topology information. 11 is estimated to be the original network address of the former parent node C. The gateway 2 then replaces the information obtained by changing the parent network addresses of the estimation target nodes F and G in the current network topology information 11 with the own network address of the former parent node C in the current network topology information 11. Created as topology information 13.

  The network topology indicated by the estimated network topology information 13 is the estimated network topology 3B shown in FIG. In the estimated network topology 3B, all nodes participate in the wireless multi-hop network, resulting in a tree topology that conforms to the network topology management rules.

  However, since this is only an estimation, there may be a difference between the current actual network topology 3A and the estimated network topology 3B. In the example of FIG. 2, the network address of the node C is 0003 in the estimated network topology 3B, but is 1003 in the actual network topology 3A.

  Next, the configuration of the gateway 2 will be described.

  Hereinafter, in this embodiment, the gateway 2 is referred to as a gateway 2A in order to distinguish it from the gateway 2 in the second and third embodiments described later.

  FIG. 3 is a block diagram showing the configuration of the gateway 2A. In FIG. 3, the gateway 2 </ b> A includes a management information response message receiving unit 21, a management information DB (database) 22, a topology information DB 23, a network topology information creating unit 24, and an estimated network topology creating unit 25. 3 indicate the flow of control, reference, or information between the components.

  The management information response message receiving unit 21 is a receiving unit that receives management information from each node 1. Specifically, the management information response message receiving unit 21 receives the management information notified by each node 1 as a response message to the request message to notify the management information from the gateway 2A to each node 1.

  The management information DB 22 stores the management information received by the management information response message receiving unit 21. The management information DB 22 continuously stores management information received from each node after remote management of each node 1 by the gateway 2A is started.

  The topology information DB 23 is a storage unit that stores network topology information. Specifically, the topology information DB 23 stores current network topology information 231, past network topology information 232, and estimated network topology information 233 as network topology information.

  As will be described later, each of the network topology information 213 to 233 is created at each predetermined creation timing during remote management of each node 1, and the topology information DB 23 stores the latest current network topology information 231 and the latest estimated network topology information 231. The network topology information 233 is stored, and the past network topology information 232 for a predetermined number of times is stored.

  The network topology information creation unit 24 creates the current network based on the management information (specifically, the MAC address, the own network address, and the parent network address included in the management information) stored in the management information DB 22 at the creation timing. Topology information and past network topology information indicating the network topology at the previous creation timing are created.

  For example, the network topology information creation unit 24 creates current network topology information based on the latest management information at the current time of each node, and based on the latest management information at the previous creation timing of each node. Create past network topology information. The network topology information creation unit 24 may create a copy of the current network topology information created at the previous creation timing as past network topology information. Even in this case, since the current network topology information created at the previous creation timing is created based on the management information, the past network topology information is also created based on the management information.

  Then, the network topology information creation unit 24 updates the current network topology information 231 in the topology information DB to the created current network topology information, and uses the created past network topology information as past network topology information 232. to add. At this time, when the past network topology information 232 for a predetermined number of times has already been stored, the network topology information creation unit 24 deletes the oldest network topology information 232.

  The creation timing is arbitrary, but for example, when the transmission of the request message by the gateway 2A to the reception of the response message is repeated periodically, immediately before the end of each cycle, that is, the response message from each node It is desirable to be a time point at which it can be considered that a sufficient amount of management information for collecting current network topology information can be collected.

  Based on the past network topology information 232, the estimated network topology creation unit 25 estimates the actual connection relationship of the estimation target node, which is a node having a connection relationship that is incompatible with the network topology management rule, in the current network topology information 231. It is an estimation part.

  Specifically, when the network topology information creation unit 24 stores the current network topology information 231 and the past network topology information 232, the estimated network topology creation unit 25 selects the current network topology information 231 and the past network topology information. Based on H.232, the current actual network topology is estimated, network topology information indicating the estimated network topology is created as estimated network topology information 233, and stored in the topology information DB.

  The estimated network topology creating unit 25 includes an estimation target node selecting unit 251, a parent node searching unit 252, and a network topology information estimating / changing unit 253.

  The estimation target node selection unit 251 selects, from the current network topology information 231, a node having a connection relationship that is incompatible with the network topology management rule as an estimation target node. Specifically, the estimation target node selection unit 251 selects all nodes (nodes F and G in FIG. 2) whose parent network address does not exist in the own network address as estimation target nodes. That is, the parent node of the estimation target node does not exist in the current network topology information 231 as its own node.

  The estimation target node selection unit 251 extracts the MAC address of the selected estimation target node from the current network topology information 231 as the estimation target MAC address, and collects the extracted estimation target MAC addresses as a parent group as an estimation target MAC address group. The node search unit 252 is notified. The estimation target MAC address group includes one or a plurality of estimation target MAC addresses.

  When there is no estimation target node, the estimation target node selection unit 251 notifies the network topology information estimation / change unit 253 of absence information that the estimation target node does not exist.

  The parent node search unit 252 uses a node having the parent netword address of the estimation target node having the estimation target MAC address notified from the estimation target node selection unit 251 from the past network topology information 232 as its own network address. A search process for searching as the original parent node of the node is executed. Here, the parent node search unit 252 searches for the original parent node from the latest past network topology information 232.

  When the original parent node is found by the search process, the parent node searching unit 252 extracts the MAC address of the original parent node as the original parent MAC address from the past network topology information 232, and the estimation target MAC address and the original parent MAC address. Are notified to the network topology information estimation / change unit 253. At this time, the parent node search unit 252 may notify the set of the estimation target MAC address and the original parent MAC address for each estimation target MAC address, or may collectively notify it.

  On the other hand, when the original parent node is not found by the search process, the parent node searching unit 252 searches the original parent node from the previous network topology information 232 one more time ago. In this way, the parent node search unit 252 repeats the search process until the original parent node is found, using the past network topology information 232 in the new order. At this time, if the original parent node cannot be searched using all the past network topology information 232, the parent node search unit 252 causes the network topology information creation unit 24 to store the past network topology information 232 at a desired time. And the search processing is performed using the created past network topology information 232.

  The network topology information estimation / change unit 253 determines the actual parent node of the estimation target node having the estimation target MAC address based on the set of the estimation target MAC address and the original parent MAC address notified from the parent node search unit 252. presume. Then, the network topology information estimation / change unit 253 creates network topology information obtained by changing the current network topology information 231 as the estimated network topology information 233 based on the estimation result.

  Specifically, the network topology information estimation / change unit 253 estimates that the actual parent node of the estimation target node is still the original parent node having the original parent MAC address, and the current network topology information 231 The estimated network topology information 233 is created by changing the parent network address of the estimation target node to the own network address of the original parent node having the original parent MAC address in the current network topology information 231. At this time, the network topology information estimation / change unit 253, for example, estimates the actual parent node for each of the estimation target nodes, creates the estimated network topology information 233 after estimating all the actual parent nodes. To do.

  When the estimated network topology information 233 is created, the network topology information estimation / change unit 253 stores the created estimated network topology information 233 in the topology information DB 23.

  Also, when the absence information is notified from the estimation target node selection unit 251, the network topology information estimation / change unit 253 creates a copy of the current network topology information 231 as it is as the estimated network topology information 233. And stored in the topology information DB 23.

  Next, the operation of the gateway 2A will be described.

  FIG. 4 is a flowchart for explaining an operation example of the gateway 2A.

  First, every time management information is received, the management information response message receiving unit 21 of the gateway 2A stores the management information in the management information DB 22 (step S100).

  Thereafter, at a predetermined creation timing, the network topology information creation unit 24 acquires management information from the management information DB 22, creates current network topology information and past network topology information based on the management information, and The network topology information 231 and the past network topology information 232 are stored in the topology information DB 23 (step S101). The network topology information creation unit 24 creates a copy of the current network topology information 232 stored in the topology information DB 23 as the past network topology information, which is the current network topology information created at the previous creation timing. May be.

  Subsequently, the network topology information creation unit 24 outputs to the estimation target node selection unit 251 that the current network topology information 231 and the past network topology information 232 have been updated. When receiving the notification, the estimation target node selection unit 251 acquires the current network topology information 231 from the topology information DB 23, and the estimation target node having a parent node that is incompatible with the network topology management rule from the current network topology information 231. Is searched (step S102).

  Then, the estimation target node selection unit 251 determines whether an estimation target node has been found (step S103).

  When the estimation target MAC address is not found, the estimation target node selection unit 251 notifies the network topology information estimation / change unit 253 of the absence information. Upon receiving the absence information, the network topology information estimation / change unit 253 creates a copy of the current network topology information 231 in the topology information DB 23 as the estimated network topology information 233 and stores it in the topology information DB 23 ( Step S104) and the process ends.

  On the other hand, when the estimation target MAC address is found, the estimation target node selection unit 251 extracts the MAC address of the found estimation target node from the current network topology information 231 as the estimation target MAC address, and the estimation target MAC address Are collectively notified to the parent node search unit 252 as the estimation target MAC address group. The parent node search unit 252 receives the estimation target MAC address group (step S105).

  The parent node search unit 252 selects one of the estimation target MAC addresses included in the estimation target MAC address group, and selects the original parent node of the estimation target node having the selected estimation target MAC address as the highest in the topology information DB 23. A search process for searching from the new past network topology information 232 is executed (step S106).

  Then, the parent node search unit 252 determines whether or not the original parent node has been found by the search process (step S107).

  If the original parent node is not found, the parent node search unit 252 executes search processing for searching the original parent node until the original parent node is found, using the past network topology information 232 in order from the newest one (step S108). If the original parent node cannot be found using all the past network topology information 232 stored in the topology information DB 23, the parent node search unit 252 sends the network topology information creation unit 24. The creation of the past network topology information 232 at a desired time is requested, and the former parent node is searched using the created past network topology information 232.

  When the original parent node is found in the process of step S107 or S108, the parent node search unit 252 extracts the MAC address of the original parent node as the original parent MAC address from the past network topology information 232 in which the original parent node is found, A set of the original parent MAC address and the estimation target MAC address selected in step S106 is generated. Then, the parent node search unit 252 determines whether all original parent nodes corresponding to all estimation target MAC addresses included in the estimation target MAC address group have been found (step S109).

  If all the original parent nodes have not been found, the parent node searching unit 252 returns to the process of step S105. In step S105, the parent node search unit 252 selects an estimation target MAC address that has not yet been selected.

  On the other hand, when all the original parent nodes are found, the parent node searching unit 252 estimates / changes the network topology information for all the pairs of the original parent MAC address and the estimation target MAC address created in any of steps S107 to S109. Notification to the unit 253. Upon receiving these sets, the network topology information estimation / change unit 253 acquires the current network topology information 231 from the topology information DB 23. For each set, the network topology information estimation / change unit 253 estimates that the actual parent node of the estimation target node having the estimation target MAC address included in the set is the original parent node having the original parent MAC address, The estimated network topology information 233 is created by changing the parent network address of the estimation target node in the current network topology information 231 to the own network address of the original parent node in the current network topology information 231. Then, the network topology information estimation / change unit 253 stores the estimated network topology information 233 in the topology information DB 23 (step S110), and ends the process.

  As described above, according to the present embodiment, in the current network topology information 231, the actual connection relationship of the estimation target nodes having a connection relationship that does not conform to the network topology management rule is estimated based on the past network topology information 232. Is done. For this reason, even if a part of the management information of each node cannot be received, more accurate network topology information can be estimated.

  In the present embodiment, since the actual parent node of the estimation target node is estimated based on the former parent node that is a past parent node, more accurate network topology information can be estimated.

(Second embodiment)
The feature of the second embodiment is that the own network address of the parent node of the estimation target node in the current network topology information is estimated based on the past network topology information and the latest information on the current network topology information.

  FIG. 5 is a diagram for explaining an example of the estimation change process by the gateway 2 of the present embodiment. In FIG. 5, the actual network topology 3A, the current network topology information 11 and the past network topology information 12 are the same as in the example of FIG.

  1: First, as in the first embodiment, the gateway 2 selects nodes F and G having a network address that does not exist as its own network address as a parent network address in the current network topology information 11 as an estimation target node. To do.

  2: Subsequently, the gateway 2 again selects the node C, which is the parent node of the estimation target nodes F and G, as the original parent mode in the past network topology information 12 as in the first embodiment.

  3: Further, the gateway 2 estimates that the actual parent nodes of the estimation target nodes F and G are still the former parent node C, and the estimation result and the latest management information received from the estimation target nodes F and G. Based on the (current network topology information 11), the own network address of the former parent node C in the current network topology information 11 is changed to the parent network addresses of the estimation target nodes F and G in the current network topology information 11 Later network topology information 14 is created.

  The network topology indicated by the estimated network topology information 14 is the estimated network topology 3C. In the estimated network topology 3C, as in the estimated network topology 3B in the first embodiment, all nodes participate in the wireless multi-hop network, and the estimated network topology 3C is the network topology of the gateway 2. The tree topology conforms to the management rules. Furthermore, the estimated network topology 3C is different from the estimated network topology 3B and is the same as the actual network topology 3A.

  Next, the structure of the gateway 2 of this embodiment is demonstrated. Below, in order to distinguish with the gateway 2A of 1st embodiment, it calls the gateway 2B.

  FIG. 6 is a block diagram showing a configuration of the gateway 2B. In FIG. 6, the gateway 2B includes a management information response message receiving unit 21, a management information DB 22, a topology information DB 23, a network topology information creating unit 24, and an estimated network topology creating unit 25B. 6 indicate the flow of control, reference, or information between the components.

  The functions of the management information response message receiving unit 21, the management information DB 22, and the topology information DB 23 shown in FIG. 6 are the same as those in the first embodiment. The function of the network topology information creation unit 24 is the same as that of the first embodiment except that the function cooperation destination (communication destination) is changed from the estimated network topology creation unit 25 to the estimated network topology creation unit 25B. The same.

  The estimated network topology creating unit 25B uses the current network topology information 231 and the past network to determine the actual connection relationship of the estimation target node, which is a node having a connection relationship incompatible with the network topology management rule, in the current network topology information 231. It is an estimation unit that estimates based on the topology information 232.

  The estimated network topology creating unit 25B includes an estimation target node selecting unit 251, a parent node searching unit 252, and a latest information application type network topology information estimating / changing unit 254.

  The functions of the estimation target node selection unit 251 and the parent node search unit 252 are as follows except that the function cooperation destination is changed from the network topology information estimation / change unit 253 to the latest information application type network topology information estimation / change unit 254. The same as in the first embodiment.

  The latest information application type network topology information estimation / change unit 254 determines the actual state of the estimation target node having the estimation target MAC address based on the set of the estimation target MAC address and the original parent MAC address notified from the parent node search unit 252. The parent node of is estimated. Then, the latest information application type network topology information estimation / change unit 254 creates network topology information obtained by changing the current network topology information 231 as the estimated network topology information 233 based on the estimation result.

  Specifically, the latest information application type network topology information estimation / change unit 254 estimates that the actual parent node of the estimation target node is the original parent node having the original parent MAC address even now, and the current network The network topology information 233 after the estimation is created by changing the own network address of the original parent node in the topology information 231 to the parent network address of the estimation target node in the current network topology information 231.

  At this time, for example, the latest information application type network topology information estimation / change unit 254 estimates an actual parent node for each estimation target node, estimates all actual parent nodes, and then estimates the network topology after estimation. Information 233 is created.

  When the estimated network topology information 233 is created, the latest information application type network topology information estimation / change unit 254 stores the created estimated network topology information 233 in the topology information DB 23.

  Further, when the absence information is notified from the estimation target node selection unit 251, the latest information application type network topology information estimation / change unit 254 estimates the network topology information 233 after copying the current network topology information 231 as it is. And stored in the topology information DB 23.

  As described above, the latest information application type network topology information estimation / change unit 254, as with the network topology information estimation / change unit 253 of the first embodiment, estimates the current parent node of the estimation target node as the current estimation. It is estimated that the target node is the parent node, and the current network topology information 231 is changed so that the parent-child relationship is as estimated.

  However, the latest information application type network topology information estimation / change unit 254 and the network topology information estimation / change unit 253 change the own network address of the original parent node based on the latest information of the current network topology information 231. The point is different.

  Next, the operation of the gateway 2B will be described.

  FIG. 7 is a flowchart for explaining an operation example of the gateway 2B.

  The processing in steps S200 to S209 in FIG. 7 is the same as the processing in steps S100 to S109 in FIG. 4 in which the network topology information estimation / change unit 253 is replaced with the latest information application type network topology information estimation / change unit 254. Therefore, the description thereof is omitted here.

  When all the original parent nodes are found in step S209, the parent node search unit 252 uses the latest information application type network to create all the pairs of the original parent MAC address and the estimation target MAC address created in any of steps S207 to S209. The topology information estimation / change unit 254 is notified. When the latest information application type network topology information estimation / change unit 254 receives these sets, it acquires the current network topology information 231 from the topology information DB 23. The latest information application type network topology information estimation / change unit 254 is, for each set, the actual parent node of the estimation target node having the estimation target MAC address included in the set is the original parent node having the original parent MAC address. And the post-estimation network topology information 233 is created by changing the own network address of the original parent node in the current network topology information 231 to the parent network address of the estimation target node in the current network topology information 231. . Then, the latest information application type network topology information estimation / change unit 254 stores the estimated network topology information 233 in the topology information DB 23 (step S210), and ends the process.

  As described above, according to the present embodiment, the network topology after estimation in which the own network address of the original parent node in the current network topology information 231 is changed to the parent network address of the estimation target node in the current network topology information 231. Information 233 is created.

  For this reason, since the estimated network topology information 233 is created based on the latest management information at the present time, the more accurate estimated network topology information 233 is compared with the first embodiment. It becomes possible to create. In some cases, it is possible to create post-estimation network topology information 233 indicating the same network topology as the actual one.

(Third embodiment)
The feature of the third embodiment is that the current network topology information is corrected by correcting the own network addresses of a plurality of competing nodes, which are a plurality of nodes whose own network addresses conflict (duplicate). To create network topology information after estimation.

  FIG. 8 is a diagram for explaining an example of a conflict correction process for correcting the own network address of the competing node by the gateway 2 and an estimation change process for creating the estimated network topology information.

  In FIG. 8, actual network topology 3D, current network topology information 15 and past network topology information 17 are shown.

  In an actual network topology 3D, in the situation shown in FIG. 1B, nodes C, D, E and F reconnect to the wireless multi-hop network, so that the network addresses of nodes C, D, E and F are It has changed.

  The current network topology information 15 is created when only the management information of the node D is notified to the gateway 2 after the network addresses of the nodes C, D, E, and F change. The past network topology information 17 indicates the network topology shown in FIG. 1B (that is, the network topology before the network addresses of the nodes C, D, E, and F change).

  The gateway 2 creates the estimated network topology information 13 by performing the following processing.

  1: First, in the current network topology information 15, the gateway 2 selects competing nodes C and D whose own network address conflicts with the other network's own network address, which is a kind of connection relationship incompatible with the network topology management rule. select.

  2: Subsequently, the gateway 2 determines that the own network address of the competing node D that has responded with the latest management information is correct among the competing nodes C and D, and the gateway 2 By correcting the own network address to an invalid value (“−” in the example of FIG. 8), the current network topology information 15 is changed to the network topology information 16 after the conflict correction. Note that the competing node D that has received the response of the latest management information specifically corresponds to the latest management information in the management information received from the competing nodes C and D by the management information response message receiving unit 21. It is a competing node. When the transmission from the request message to the reception of the response message is repeated periodically, the management information response message receiving unit 21 in the management information received from the competing nodes C and D during the current period Management information received at the same time.

  3: Then, the gateway 2 selects the node F having the network address that does not exist as its own network address as the parent network address in the network topology information 16 after the conflict correction as the estimation target node. That is, there is no node having the parent network address “0004” of the estimation target node F as its own network address.

  4: Thereafter, the gateway 2 selects the former parent node D that is the parent node of the estimation target node F in the past network topology information 17 as in the first embodiment.

  5: Further, similarly to the first embodiment, the gateway 2 estimates that the actual parent node of the estimation target node F is still the former parent node D, and sets the actual parent network address of the estimation target node F. The network address of the node D in the network topology information 16 after the conflict correction is estimated. Then, the gateway 2 changes the information obtained by changing the parent network address of the estimation target node F in the network topology information 16 after the conflict correction to the own network address of the node D in the network topology information 16 after the conflict correction. Created as topology information 18.

  The network topology indicated by the estimated network topology information 18 is the estimated network topology 3E. In the estimated network topology 3E, as in the first and second embodiments, all the nodes participate in the wireless multi-hop network, and the estimated network topology 3E is the network topology management of the gateway 2. The tree topology conforms to the rules. Furthermore, since each overlapping node's own network address is corrected based on the latest management information, each node has only one parent node. Therefore, the estimated network topology information has a plurality of parent nodes. It becomes possible to prevent a node from occurring.

  Note that when the parent network address of the estimation target node is the latest information, the gateway 2 uses the own network address of the original parent node of the estimation target node in the network topology information 16 after the conflict correction, as in the second embodiment. The parent network address of the estimation target node that is the latest information may be estimated. In this case, the gateway 2 changes its own network address of the original parent node of the estimation target node in the network topology information 16 after the conflict correction to the parent network address of the estimation target node. However, in the example of FIG. 8, since the parent network address information of the estimation target node F is not the latest information, the same processing as in the second embodiment is not performed.

  Next, the structure of the gateway 2 of this embodiment is demonstrated. Below, in order to distinguish with the gateways 2 and 2B in 1st embodiment and 2nd embodiment, it calls the gate 2C.

  FIG. 9 is a block diagram showing a configuration of the gateway 2C. In FIG. 6, the gateway 2C is different from the gateways 2A and 2B shown in FIG. 3 in that the network topology information creation unit 24 includes a competing network address correction unit 241. In FIG. 9, the gateway 2C includes the estimated network topology creating unit 25, but may include the estimated network topology creating unit 25B. Further, solid arrows in FIG. 9 indicate the flow of control, reference, or information between the components.

  When the network topology information creating unit 24 creates the current network topology information, the conflicting network address correcting unit 241 checks whether or not there is a conflict (duplication) of its own network address in the current network topology information.

  When there is a conflict with the own network address, the conflict network address correcting unit 241 selects a plurality of competing nodes with which the own network address competes from the created current network topology information. Then, the competing network address correcting unit 241 corrects the own network address of the competing node other than the competing node that has responded to the latest management information in the created current network topology information to an invalid value (unknown value). Thus, the network topology information after the conflict correction is created.

  The contention network address correction unit 241 stores the created network topology information after the contention correction in the topology information DB 23 as current network topology information.

  If there are a plurality of competing node groups having competing local network addresses, the competing network address correcting unit 241 performs a contention correcting process for each competing node group. For example, when there are three first nodes having the own network address “0001” and two other second nodes having the own network address “0002”, the conflicting network address correcting unit 241 For each of the node and the second node, the own network address of the competing node other than the competing node that has responded with the latest management information is corrected to an invalid value.

  On the other hand, if there is no conflict of the own network address, the conflicting network address correcting unit 241 uses the generated current network address information as it is as the corrected network address information, and uses the corrected network address information as the current network topology information 231. Is stored in the topology information DB 23.

  Next, the operation of the gateway 2C will be described.

  FIG. 10 is a flowchart for explaining an operation example of the gateway 2C.

  First, every time management information is received, the management information response message receiving unit 21 of the gateway 2A stores the management information in the management information DB 22 (step S300).

  Thereafter, at a predetermined creation timing, the network topology information creation unit 24 acquires management information from the management information DB 22, creates past network topology information 232 based on the management information, and stores it in the topology information DB. (Step S301) Further, the network topology information creating unit 24 creates current network topology information 232 based on the management information (Step S302).

  Note that the processing from step S300 to S302 corresponds to the processing from step S100 to S101 in FIG. 4 and the processing from step S200 to S201 in FIG.

  Thereafter, the conflicting network address correcting unit 241 checks whether or not there is a conflict of its own network address in the network address information of the created temporary current network topology information (step S303).

  When there is a conflict with the own network address, the conflict network address correcting unit 241 selects a plurality of competing nodes with which the own network address conflicts from the created temporary current network topology information. Then, the competing network address correcting unit 241 corrects the own network address of the competing node other than the competing node that has responded to the latest management information in the created temporary current network topology information to an invalid value. Create network topology information after conflict correction. The contention network address correction unit 241 stores the created network topology information after the contention correction in the topology information DB 23 as the current network topology information (step S304).

  On the other hand, when there is no conflict of the own network address, the conflicting network address correcting unit 241 uses the temporary current network topology as the corrected network topology information, and the corrected network topology information as the current network topology information 231. It is stored in the topology information DB 23 (step S305).

  When the process of step S304 or S305 is completed, the processes of steps S101 to S110 in FIG. 4 or steps S202 to S210 in FIG. 7 are executed.

  As described above, according to this embodiment, since the own network address of a node having a plurality of parent nodes is corrected, network topology information conforming to a network topology management rule without a node having a plurality of parent nodes is created. It becomes possible to do.

  In each embodiment described above, the illustrated configuration is merely an example, and the present invention is not limited to the configuration.

  For example, the function of the gateway 2 is realized by recording a program for realizing the function on a computer-readable recording medium, and causing the computer to read and execute the program recorded on the recording medium. May be.

  Further, although the gateway 2 has the function of the network topology estimation device, the network topology estimation device may be outside the gateway 2. For example, the function of the network topology estimation device may be provided in a remote management server that performs remote management and is connected to each node 1 via the gateway 2.

1 node 2, 2A to 2C gateway 21 management information response message receiving unit 22 management information DB (database)
23 Topology information 24 Network topology information creation unit 25 Estimated network topology creation unit 231 Current network topology information 232 Past network topology information 233 Estimated network topology information 241 Competing network address correction unit 251 Estimation target node selection unit 252 Parent node search Section 253 Network topology information estimation / change section 254 Latest information application type network topology information estimation / change section

Claims (8)

A node other than the root node having no parent node is a network topology estimation device for estimating a network topology in a tree topology having only one parent node,
Current network topology information indicating a current connection relationship between nodes constructing a network, and past network topology information indicating a past connection relationship between the nodes,
From the current network topology information, an estimation target node that is a node having a connection relationship that does not conform to a predetermined rule having a network topology as a tree topology is selected, and an actual connection relationship of the estimation target node is determined as the past based on the network topology information have a, an estimation unit that estimates of,
Each of the current network topology information and the past network topology information indicates a parent-child relationship between the nodes;
The estimation unit selects a node having a parent node that does not conform to the rule as the estimation target node, and an actual parent node of the estimation target node is a parent node of the estimation target node in the past network topology information. A network topology estimation apparatus that estimates a certain original parent node . Each of the current network topology information and the past network topology information indicates a parent-child relationship between the nodes by a local network address that is the network address of the node and a network address of the parent node of the node. Shown in relation to a parent network address
The estimating unit, the own network address of the Motochika node in the current network topology information, creating an estimated network topology information is changed to the parent network address of the estimation target node in the current network topology information, claims 2. The network topology estimation apparatus according to 1. Each of the current network topology information and the past network topology information indicates a parent-child relationship between the nodes by a local network address that is the network address of the node and a network address of the parent node of the node. Shown in relation to a parent network address
The estimation unit creates estimated network topology information in which a parent network address of the estimation target node in the current network topology information is changed to a local network address of an original parent node of the estimation target node in the current network topology information The network topology estimation apparatus according to claim 1 . 4. The network topology estimation apparatus according to claim 2 , wherein the estimation unit selects, as the estimation target node, a node having a network address that does not exist as its own network address as a parent network address in the current network topology information. . A receiving unit for receiving management information for specifying the connection relation from the node;
5. The network topology estimation apparatus according to claim 1 , further comprising: a creation unit that creates the current network topology information and the past network topology information based on the management information. Each of the current network topology information and the past network topology information indicates a connection relationship between the nodes by a local network address that is a network address of the node and a network address of a parent node of the node. Shown in relation to a parent network address
The creation unit, in the current network topology information, among a plurality of competing nodes with which the own network address competes, a conflict corresponding to the latest management information among the management information received by the receiving unit from each competing node The network topology estimation apparatus according to claim 5 , wherein the network address of a competing node other than the node is corrected to an invalid value. A network topology estimation method for estimating a network topology in a tree topology in which a node other than a root node having no parent node has only one parent node,
Current network topology information indicating a current connection relationship between nodes constructing a network, and past network topology information indicating a past connection relationship between the nodes,
From the current network topology information, an estimation target node that is a node having a connection relationship that does not conform to a predetermined rule having a network topology as a tree topology is selected, and an actual connection relationship of the estimation target node is determined as the past estimated based on network topology information,
Each of the current network topology information and the past network topology information indicates a parent-child relationship between the nodes;
A node having a parent node that does not conform to the rule is selected as the estimation target node, and an actual parent node of the estimation target node is an original parent node that is a parent node of the estimation target node in the past network topology information estimated to, network topology estimation method. A program that causes a computer to execute network topology estimation for estimating a network topology in a tree topology in which a node other than a root node having no node has only one parent node,
A computer having current network topology information indicating a current connection relationship between nodes constructing a network and past network topology information indicating a past connection relationship between the nodes;
From the current network topology information, an estimation target node that is a node having a connection relationship that does not conform to a predetermined rule having a network topology as a tree topology is selected, and an actual connection relationship of the estimation target node is determined as the past estimated based on network topology information,
Each of the current network topology information and the past network topology information indicates a parent-child relationship between the nodes;
A node having a parent node that does not conform to the rule is selected as the estimation target node, and an actual parent node of the estimation target node is an original parent node that is a parent node of the estimation target node in the past network topology information A program for executing the estimation procedure.

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