JP5244838B2 - Degraded path detection system, degraded path detection method, and computer program - Google Patents

Description

  The present invention relates to a degraded path detection system, a degraded path detection method, and a computer program.

  Patent Literature 1 discloses a cluster in which each node device belongs to one of a plurality of clusters by autonomously determining a cluster to which the node device belongs based on information acquired from the network system. As for actual quality measurement, a quality measurement method is described in which full mesh measurement is performed only between representative nodes in each cluster. In this quality measurement method, when other nodes belonging to the cluster require network quality measurement results, the total number of measurements can be reduced by using the measurement results of the representative node, and the load on the network Can be suppressed. As a result, in a multi-node large-scale distributed network environment that is expected to increase rapidly in the ubiquitous era, it is possible to automatically perform efficient quality measurement while maintaining scalability. Useful for grasping and detecting faults.

Japanese Patent Laid-Open No. 2007-074202

  In the above-described conventional technology, the total number of measurements is suppressed, but due to the measurement method, measurement devices are required for all the representative nodes of the network, and installation costs are increased. In addition, when there is a deterioration factor other than the representative node, a deterioration path cannot be extracted. In addition, when a plurality of degraded paths are extracted, there is a possibility that a degraded path effective for handling is not properly notified to a maintenance person or the like.

  The present invention has been made in view of such circumstances, and its purpose is to efficiently and appropriately detect a degraded path that is effective for coping to improve network quality while suppressing costs. An object of the present invention is to provide a degradation path detection system, a degradation path detection method, and a computer program.

The present invention has been made to solve the above-described problem, and includes a degraded path detection device including a degraded path detection device and a measurement terminal connected to the node in a network in which a plurality of nodes are connected by links. a system, the degradation path detection apparatus selects the node of the hierarchy where the measurement terminal from the network is connected, the selected topology decompose subtree network with tree structure as the node to the root node In the topology of the tree structure decomposed by the construction unit, the subtree network construction unit, a measurement instruction execution unit for instructing measurement of communication quality between the measurement terminals, and obtained according to an instruction from the measurement instruction execution unit And detecting a degradation path based on a degradation value of communication quality between the measured terminals, and a degradation value between the root node and Includes selecting analysis unit that performs selection analysis process for identifying the measurement terminal as the large and (measuring terminal selection / degradation value analysis unit), the partial tree network construction unit, after the selection analysis process by the selection analysis unit, Select a node that is one level higher than the current root node as a new root node, perform a subtree network construction process for decomposing the network into a tree topology with the new node selected as the root node, and The execution unit instructs the measurement of communication quality between the measurement terminals specified by the selection analysis process in the topology of the tree structure decomposed by the subtree network configuration process by the subtree network construction unit It performs instruction execution processing of the selection until the process ends for all the nodes in the network Repeat the processing from the analysis unit to perform a deterioration path detection system, characterized in that.

  Further, the present invention is a degraded path detection system comprising a degraded path detection device and a measurement terminal connected to the node in a network in which a plurality of nodes are connected by a link, wherein the degraded path detection device Is a sub-tree network that selects a sub-tree network having a tree structure in which the selected node is selected as a root node and the measurement terminal is a leaf node. Obtained in response to an instruction from the construction instruction section, a measurement instruction execution section instructing measurement of communication quality between the measurement terminals in the subtree network extracted by the subtree network construction section, and the measurement instruction execution section Further, based on a measurement deterioration value of communication quality between the measurement terminals, the measurement terminal to be measured is further selected, and the measurement instruction Instructing measurement of communication quality between the selected measurement terminals to the row unit, detecting a degraded path in the subtree network based on a measured degradation value between the measurement terminals obtained by measurement, and the root node And a selection analysis unit (measurement terminal selection / degradation value analysis unit) that identifies the measurement terminal with the maximum degradation value between the subtree and the subtree network construction unit, wherein the root node is at the lowest hierarchy In some cases, all the measurement terminals connected to the root node are leaf nodes, and when the root node is not the lowest hierarchy, a subtree having the measurement terminal selected by the selection analysis unit as a leaf node. A degradation path detection system characterized by extracting a network.

  Further, the present invention is a degradation path detection system comprising a degradation path detection device and a measurement terminal connected to the node in a network formed by connecting a plurality of nodes by links, the measurement terminal comprising: In response to an instruction from the deteriorated path detection device, the communication device includes means for measuring communication quality with the other measurement terminals, and the deteriorated path detection device selects in order from the nodes in the hierarchy to which the measurement terminals are connected. A partial tree network construction unit for extracting a tree-structured partial tree network having the selected node as a root node and the measurement terminal as a leaf node from the network; and the portion extracted by the partial tree network construction unit A measurement finger that selects a pair of measurement terminals in the tree network and instructs measurement of communication quality between the selected pair of measurement terminals. An execution unit and a deterioration value acquisition unit (measurement result reception / deterioration value calculation unit) that acquires a measurement result of communication quality between the selected pair in response to an instruction from the measurement instruction execution unit and calculates a deterioration value And a pair of measurement terminals that require measurement for detection of a degradation path based on the measurement degradation value between the measurement terminals acquired by the degradation value acquisition unit, and communication between the selected pair of measurement terminals The measurement instruction execution unit is instructed to perform quality measurement, and the deterioration value of the link in the subtree network is acquired by the measurement deterioration value between the pair of measurement terminals acquired by the deterioration value acquisition unit. And a selection analysis unit (measurement terminal selection / degradation value analysis unit) that identifies the measurement terminal that has the maximum degradation value with the root node, and the subtree network construction unit includes Roux When the node is the lowest hierarchy, all the measurement terminals connected to the root node are leaf nodes, and when the root node is not the lowest hierarchy, the measurement terminal selected by the selection analysis unit This is a degraded path detection system characterized by extracting a subtree network with a leaf node as a node.

  Further, the present invention is the above-described degradation path detection system, wherein the selection analysis unit performs measurement for detection of degradation paths based on the measurement degradation value between the measurement terminals acquired by the degradation value acquisition unit. The necessary measurement terminals are selected, the measurement instruction execution unit is instructed to measure the communication quality between the selected measurement terminals, and the portion is determined by the measurement deterioration value between the measurement terminals acquired by the deterioration value acquisition unit. When the degradation path is detected by obtaining the degradation value of the link in the tree network, and the degradation path is detected, the degradation value of each link in the degradation path is corrected, and then the degradation of the link in the subtree network is performed. A measurement terminal having a maximum deterioration value with the root node is specified based on the value.

The present invention is a degradation path detection method used in a degradation path detection system comprising a degradation path detection device and a measurement terminal connected to the node in a network formed by connecting a plurality of nodes by links, In the degraded path detection device, the subtree network construction unit selects the node of the layer to which the measurement terminal is connected from a network in which a plurality of nodes are connected by links, and the selected node is set as a root node. Measurement of communication quality between the measurement terminals in the tree structure topology decomposed in the lowest layer subtree network construction process in which the lower layer subtree network construction process is decomposed into a tree structure topology and the measurement instruction execution unit is decomposed in the lowest layer subtree network construction process The lowermost layer instruction execution process and the selection analysis unit (measurement terminal selection / degradation value analysis unit) respond to the instructions. A selection analysis process for detecting a degradation path based on a degradation value of communication quality between the measurement terminals obtained in this way, and identifying a measurement terminal having a maximum degradation value with the root node; A sub-tree network construction process in which a network construction unit selects a node that is one layer higher than the current root node as a new root node, and decomposes it into a tree-structure topology with the new node selected as the root node as a root node; The measurement instruction execution unit includes an instruction execution process for instructing measurement between the measurement terminals identified by the selection analysis process in the topology of the tree structure decomposed in the subtree network construction process, The process from the selection analysis process is repeatedly executed until the process is completed for all the nodes in the network. It is the degradation path detection method comprising.

In addition, the present invention selects a node in a hierarchy to which a measurement terminal is connected from a network in which a plurality of nodes are connected to a computer used as a degraded path detection device, and routes the selected node to the route. Instructing measurement of communication quality between the measurement terminals in a bottom layer subtree network construction step that is decomposed into a tree structure topology as a node and the tree structure topology decomposed in the bottom layer subtree network construction step a lowermost instruction execution step, and detects the degradation path based on the degradation value of the communication quality between the measurement terminal obtained in response to the instruction, the measurement terminal degradation value between the root node becomes the maximum and selection analysis identifying a, as a new root node a node in one level higher than the current root node Selected, the topology decomposing subtree network construction step of the tree structure a new selected node of the network and the root node, in the selection analysis steps in the topology of the decomposed tree structure in the subtree network construction step An instruction execution step for instructing measurement of communication quality between the specified measurement terminals; and a repetitive processing step for repeatedly executing the processing from the selection analysis step until the processing is completed for all nodes in the network. a computer program characterized and Turkey is executed.

According to the present invention, it is possible to achieve efficient quality measurement for all nodes without measuring communication quality using a full mesh by already using the measurement result of the measurement path and obtaining it by calculation. As a result, it is possible to detect a degraded path while minimizing the load on the network, so that the application to a large-scale network is easy. In addition, the measurement equipment necessary for detecting the degraded path may be arranged only outside the network, and it is not necessary to install the measurement equipment inside the network for calculating the quality of each section. Therefore, the installation cost can be suppressed.
According to the present invention, since the measurement process is performed while calculating and correcting the deterioration value in the already detected deterioration path, the deterioration state is canceled when the deterioration in the other deterioration paths is canceled. It is possible to detect degraded paths in the network while suppressing path detection, and since most of the detected degraded paths are independent, it is possible to suppress wasteful separation work when detecting degraded paths. And early failure recovery is possible.

1 is an overall configuration diagram of a degraded path detection system according to an embodiment of the present invention. It is a functional block diagram which shows the structure of the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the data structure of the data which the degradation path | pass detection apparatus by the embodiment uses for a process. It is a figure which shows the processing flow of the whole degradation path | pass detection process in the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the processing flow of the subtree data construction process in the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the processing flow of the measurement process in a subtree in the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the processing flow of the measurement degradation path | pass process in the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the processing flow of the link degradation value calculation process in the degradation path | route detection apparatus by the embodiment. It is a figure which shows the processing flow of the degradation area candidate extraction process in the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the processing flow of the aliasing degradation analysis process in the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the processing flow of the aliasing degradation analysis process in the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the processing flow of the largest degradation area extraction process in the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the processing flow of the subtree data reconstruction process in the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the partial tree data construction process by the embodiment. It is a figure for demonstrating the measurement degradation path | pass process by the same embodiment. It is a figure for demonstrating the measurement degradation path | pass process by the same embodiment. It is a figure for demonstrating the link degradation value calculation process by the embodiment. It is a figure for demonstrating the link degradation value calculation process by the embodiment. It is a figure for demonstrating the degradation area candidate extraction process by the same embodiment. It is a figure for demonstrating the degradation area candidate extraction process by the same embodiment. It is a figure for demonstrating the aliasing degradation analysis process by the embodiment. It is a figure for demonstrating the aliasing degradation analysis process by the embodiment. It is a figure for demonstrating the maximum degradation area extraction process by the same embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the subtree data reconstruction process by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. 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It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure for demonstrating the example of analysis of the degradation path | pass detection apparatus by the embodiment. It is a figure which shows the example of the measuring object network which can be analyzed by the degradation path | pass detection apparatus by the embodiment. FIG. 72 is a diagram illustrating an example in which the measurement target network in FIG. 71 is divided into subtrees. FIG. 73 is a diagram showing a degraded path in the partial tree network shown in FIG. 72.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[1. Constitution]
FIG. 1 is a diagram showing an overall configuration of a degraded path detection system according to an embodiment of the present invention.
As shown in the figure, a degraded path detection system for detecting a degraded path in a measurement target network composed of a plurality of routers R includes a degradation path detection apparatus 1 having a network topology information storage device 2, a measurement target network, and the like. The measurement terminal T is connected to the router R that constitutes the network, and all the measurement terminals T and the degraded path detection device 1 are connected by a communication network.
In the figure, the measurement target network has a tree structure, but the measurement network may have any structure as long as it can be divided into subtrees.

In the present embodiment, a relay device such as the measurement terminal T and the router R in the measurement target network is a “node”, and a section between the measurement terminal T and the router R and between the router R and the router R is a “link”. .
In the topology of the tree structure, the layer in which the measurement terminal T is installed is the measurement terminal layer, and in the measurement target network, the first layer, the second layer,... From the router R (node) close to the measurement terminal T. And grouping with the Nth layer. In the following description, when “nodes included in the i-th layer” (i is 1, 2,..., N) or the like, it indicates all nodes included in the i-th layer. When “nodes included in two layers” are described, the topology shown in FIG. 1 indicates two nodes (routers R) in the second layer.
The lower hierarchy number, that is, the hierarchy closer to the terminal layer is the lower hierarchy, the higher hierarchy number is the higher hierarchy, and the one lower hierarchy node connected to a node is connected to a child node or a node. The node that is one level higher is used as the parent node.

  The network topology information storage device 2 stores network topology information. The network topology information is information that identifies the connection relationship between the elements (nodes and links) constituting the measurement target network and each measurement terminal T. Each element and each measurement terminal T has unique identification information. The network topology information includes identification information of each element, the type of whether each node is a measurement terminal T or a router R, and information on the communication address of each node. In the present embodiment, node identification information is referred to as a node ID, and a node having a node ID x is described as a node N [x]. In particular, the measurement terminal T whose node ID is x is also referred to as measurement terminal T [x]. In the drawings, the node IDs of the measurement terminal T and the router R are described in [].

  The degradation path detection device 1 can specify the path between the measurement terminals T based on the network topology information stored in the network topology information storage device 2 and the identification information of the measurement terminals. The degraded path detection apparatus 1 instructs the measurement terminal T to measure communication quality (hereinafter, communication quality measurement is also simply referred to as “measurement”), and the measurement terminal T transmits and receives the measurement instruction in response to the measurement instruction. Receives transmission information of a communication packet. The degraded path detection device 1 calculates the IP (Internet Protocol) quality between two points from the time stamp of transmission information transmission / reception of communication packets between the measurement terminals T. Here, the IP quality indicates delay and packet loss.

  The measurement terminal T is a device capable of active communication between measurement terminals, like a general communication terminal. The measurement terminal T performs communication between other measurement terminals T in response to a communication quality measurement instruction from the degraded path detection device 1, and transmits transmission information of the communication packet to the degraded path detection device 1. The measurement terminal T acquires the time when the communication packet is transmitted / received. It is assumed that time synchronization is performed at the time of measurement of communication quality by each measurement terminal T.

The degradation path detection apparatus 1 according to the present embodiment performs the following processing in order to detect a path that is determined to be degraded between devices that constitute a measurement target network.
(1) The entire measurement network is decomposed into a small tree-structure topology from the side closer to the measurement terminal T.
(2) Within the decomposed tree-structure topology, measurement is performed between the measurement terminals T to detect a degradation path, and the degradation value between the root node and the measurement terminal T in the tree-structure topology is maximized. The measurement terminal T is extracted.
(3) A new subtree having a root node as a node on one layer connected to the root node of each subtree having a decomposed tree structure is set as a target range, and between the measurement terminals T extracted in (2) Measurement is performed to detect a degradation path, and a measurement terminal T having a maximum degradation value is extracted.
(4) The processing of (3) is repeated to detect a degraded path of the entire topology.

The above processing has the following characteristics.
(A) It is possible to detect a path that deteriorates at the end-end by the sum of the deterioration of each element.
(B) When the degradation in the other degraded paths is eliminated, it is possible to efficiently recognize the degraded path to be dealt with by suppressing the detection of the paths in which the degraded state is eliminated.
(C) Even if a plurality of independent degraded paths exist at the same time, there is no False Negative path (a state in which a degraded path is not detected) in one measurement for the entire measurement target network.

FIG. 2 is a functional block diagram showing the configuration of the degraded path detection apparatus 1.
In the figure, the degradation path detection device 1 includes a subtree network construction unit 11, a measurement instruction execution unit 12, a measurement result reception / degradation value calculation unit 13, a measurement terminal selection / degradation value analysis unit 14, a storage unit 15, and An output unit 16 is provided. The network topology information storage device 2 may be provided in the degraded path detection device 1 or may be realized by an external device connected to the degraded path detection device 1.

  The subtree network construction unit 11 extracts a subtree network that is a measurement target for detecting a degraded path. The measurement instruction execution unit 12 transmits a measurement instruction to the measurement terminal T in the subtree network extracted by the subtree network construction unit 11. In addition, a measurement instruction is transmitted to the measurement terminal T based on the information received from the measurement terminal selection / degradation value analysis unit 14. The measurement result reception / deterioration value calculation unit 13 receives transmission information of a communication packet from the measurement terminal T, and calculates a measurement deterioration value (delay / loss) between the two measurement terminals T from the reception information. The measurement terminal selection / degradation value analysis unit 14 selects the measurement terminal T necessary for the analysis according to the measurement result received by the measurement result reception / degradation value calculation unit 13, and detects the degradation path from the measurement result, The measurement terminal T that maximizes the degradation value between the node and the leaf node is specified. The root node is a node at the highest level in the subtree network, and the leaf node is a node (measurement terminal T) in the measurement terminal layer in the subtree network. The storage unit 15 stores data used for the degradation path detection process. The output unit 16 displays the detected degraded path on the screen. Alternatively, the output unit 16 may print the detected degradation path, write it on a computer-readable recording medium, or send it to another computer connected via a network.

  An outline of processing by each unit in the degraded path detection device 1 will be described.

(Step S1): The subtree network construction unit 11 extracts, as a measurement range, a subtree network in which a node included in the first hierarchy is a root node and a measurement terminal T directly connected to this node is a leaf node.

(Step S2): The measurement terminal selection / degradation value analysis unit 14 selects a pair of measurement terminals T so that the coverage rate is 100% for the measurement terminals T of the subtree network that is each measurement range, and performs a measurement instruction. The execution unit 12 transmits an instruction to the measurement terminal T so as to perform measurement between each pair. The coverage rate of 100% is a state in which all measurement terminals T included in the subtree network are used only once in the selected pair. However, when the number of measuring terminals T is an odd number, only one is used twice.

(Step S3): The measurement terminal T performs measurement communication with the measurement terminal T designated as a pair, and transmits and receives packets. Each measuring terminal T records the information (transmission destination, transmission source, sequence number, etc.) of the transmitted / received packet and the time when the packet was transmitted / received. After the measurement is completed, the measurement terminal T transmits the transmission / reception packet information, the packet transmission / reception time, and the measurement result information including the node identification information for specifying the own measurement terminal T to the degradation path detection device 1.

(Step S4): The measurement result reception / deterioration value calculation unit 13 receives the measurement result information received from the measurement terminal T, and the measurement deterioration value between the measurement terminals T in a certain unit time from the received measurement result information. (Delay time / Packet loss rate) is calculated.

(Step S5): The measurement terminal selection / degradation value analysis unit 14 selects a measurement terminal T necessary for the analysis according to the measurement degradation value of each path, and the measurement instruction execution unit 12 performs measurement to the selected measurement terminal T. Instruct. The measurement result reception / degradation value detection unit 13 receives the measurement result, and the measurement terminal selection / degradation value analysis unit 14 calculates the degradation value and detects the degradation path in each measurement range (subtree network). Then, the measurement terminal T having the maximum deterioration value between the root node and the leaf node is extracted.

(Step S6): The subtree network construction unit 11 extracts a new measurement range (subtree network) in which the node included in the second hierarchy is a root node and the measurement terminal T extracted in step S5 is a leaf node. .

(Step S7): The same processing as Steps S2 to S4 is performed on the subtree network extracted in Step S6, and a degraded path in the measurement range (subtree network) having the second-layer node as a root node is detected. The measurement terminal T having the maximum deterioration value between the root node and the leaf node is extracted.

(Step S8): Thereafter, similarly, a measurement range (partial tree network) in which a node included in each layer is a root node and the extracted measurement terminal T is a leaf node is extracted, and each measurement range (subtree network) The process of detecting the degraded path and extracting the measurement terminal T having the maximum degraded value is repeated until the node in the highest hierarchy becomes the root node. The output unit 16 of the degraded path detection device 1 outputs the detected degraded path as an analysis result.

  When the degradation in the other degraded paths is eliminated, the process in step S5 is detailed to obtain the effect of suppressing the detection of the path in which the degraded state is eliminated, as in step S5 'below.

(Step S5 ′): The measurement terminal selection / degradation value analysis unit 14 selects a measurement terminal T necessary for analysis according to the measurement degradation value of each path, and the measurement instruction execution unit 12 selects the measurement terminal T selected. Instruct the measurement. The measurement result reception / deterioration value calculation unit 13 receives the measurement result and calculates the deterioration value, and the measurement terminal selection / degradation value analysis unit 14 deteriorates within each measurement range (subtree network) from the calculation result. Analyzes whether a path exists.
When a degraded path is detected, the measurement terminal selection / degradation value analysis unit 14 corrects the degradation value of each link in the degraded path to “0”, and then determines the route based on the degradation value of each link in the subtree. The measurement terminal T having the maximum degradation value between the node and the leaf node is extracted.

When the degradation value of each link in the degraded path is used as it is, all the paths including the degraded part are detected as degraded paths, and it becomes difficult to narrow down the range to be dealt with. Therefore, when a degraded path is detected, a process of correcting the degradation value of each link in the degraded path by “0” is performed, and for the path including the degraded portion, the degraded path is eliminated in the calculation. By setting the deterioration value at, it is possible to obtain an effect of suppressing detection of a path in which the deterioration state is canceled when the deterioration in the other deterioration paths is canceled.
If no degradation path is detected, correction processing is not performed, and the measurement terminal T that maximizes the degradation value between the root node and the leaf node is extracted based on the degradation value of each link obtained from the measurement result itself. Will be.

[2. Processing of degraded path detection device]
Subsequently, the processing flow of the degraded path detection apparatus 1 will be described using a flowchart, and the processing of this processing flow will be described with a specific example.

[2.1 Data structure]
First, data used by the degradation path detection apparatus 1 for processing will be described.
FIG. 3 is a diagram illustrating a data structure of data stored in the storage unit 15 of the degraded path detection device 1. The data structure shown in the figure is for handling only one type of quality information (for example, delay) as each deterioration value or deterioration correction value of communication quality (IP quality).

  The node information corresponds to each node, and each node information stores information related to the corresponding node (own node), and node information corresponding to the child node is also stored as information related to the own node. Since the measurement target network has a tree structure (or can be divided into tree structures), node information of one or more child nodes is stored in one node information. Further, one or more child node pair information is also stored as information related to the own node.

In the figure, the node information includes data of a node ID, a link deterioration value, a child node pair list, a child node list, a subtree constituting node, a link total deterioration value, and a link deterioration correction value.
The node ID is an identifier that can uniquely identify a node (local node) to which each node information corresponds.
The link deterioration value indicates a link deterioration value between the own node and the parent node of the own node.
The child node pair list is list information in which child node pair information indicating a child node paired at the time of measurement is stored in a subtree having its own node as a root. The child node pair information includes data of a node ID of two child nodes that are paired and a path deterioration value indicating a deterioration value between the measurement terminals T associated with each of the two child nodes.
The child node list is list information in which node information of child nodes connected to the own node is stored.
The sub-tree constituting node indicates a child node that belongs to a route in which the sum of link deterioration values between the own node and the measurement terminal T is maximum. Here, the node ID of the child node is set.
The link total deterioration value indicates the total value of link deterioration values set in the nodes on the path from the own node to the measurement terminal T, which can be traced through the subtree constituting nodes.
The link deterioration correction value indicates a link deterioration value between the own node and the parent node belonging to the path determined to be deteriorated.

  In the present embodiment, the description is given taking as an example a data structure for only one type of quality information, but multiple types (delay and loss) of quality information may be handled. When handling multiple types (delay and loss) of quality information, an area for storing each information may be prepared, or the data shown in FIG. 3 may be used for each type. Note that this data structure is an example, and processing may be performed using another data structure.

  In the example of setting node information in the drawing, the first line is a node ID, the second line is a link degradation value, the third line is a child node pair list, the fourth line is a child node list, and the fifth line is a subtree configuration node. The 6th line shows the link total deterioration value, and the 7th line shows the set value of the link deterioration correction value. In the drawing, when setting examples of child node pair information are shown, the first and second lines indicate node IDs, and the third line indicates path degradation values. Also, in the node information, the child node list pair list indicates the identification information of the child node of the pair for which the child node pair information is set, and the child node list indicates the child node for which the node information is set. Shows identification information.

In addition, a measurement terminal T obtained by tracing a node sub-tree configuration node is referred to as “measurement terminal T associated with a node”. When specifying the measurement terminal T associated with a certain node, first, node information of the node is read, and a sub-tree configuration node is read from the read node information. If the node ID is set for the subtree constituting node, the process of reading the node information specified by the set node ID is repeated until reaching the node information for which no subtree constituting node is set. The measurement terminal T is accompanied by a node identified by the node ID set in the node information in which no subtree constituting node is set, that is, a node corresponding to node information having no subtree constituting node. Further, the node information read at this time is node information of a node existing in a path from a certain node to the accompanying measurement terminal T.
In the following description of the processing, the procedure for identifying the measurement terminal T associated with the node and the procedure for obtaining the node information of the node existing in the path from the node to the measurement terminal T associated with the node are performed as described above. The description is omitted.

[2.2 Processing procedure]
[2.2.1 Degraded path detection overall processing]
FIG. 4 is a diagram illustrating a processing flow of the entire degradation path detection in the degradation path detection apparatus 1.
The degradation path detection device 1 starts the degradation path detection process when a designated time is reached periodically at predetermined time intervals or when an analysis instruction is input from the outside. First, when the degradation path detection device 1 refers to the network topology information stored in the network topology information storage device 2 and sequentially selects the first layer to the Nth layer as the processing target layer, the processing from step S20 is performed. It carries out in order (step S10). Further, the processes from step S30 to S80 are performed until all the nodes of the processing target layer selected in step S10 are selected (step S20).
Note that the subtree network construction unit 11 of the degraded path detection device 1 refers to the network topology information, selects the router R connected to the measurement terminal T as a node in the first layer, and makes it the router R in the first layer. By selecting the connected unselected router R as the second layer node until all the routers R are selected, the router R up to the Nth layer can be selected as the node. It should be noted that information on the hierarchy to which each router R belongs may be set in advance in the network topology information.

The degraded path detection device 1 selects one node that has not yet been selected in the processing target layer (step S30), and the measurement target network, which is a tree-structured network, is obtained by the partial tree data construction processing shown in FIG. The node selected in step S30 is divided into subtrees having a root node (step S40), and measurement is performed in the subtree divided in step S40 by the intra-subtree measurement process shown in FIG. 6 (step S50). Based on the measurement result of step S50, the degraded path detection device 1 extracts a section where the degradation value between the root node and the leaf node is most likely to be maximized by the degraded section candidate extraction process shown in FIG. 9 (step S60). ). In order to determine whether a path connecting the extracted section and another section is a degraded path, the presence / absence of a degraded path in the subtree is analyzed by the aliasing degradation analysis process shown in FIGS. 10 and 11 (step S70). Then, by the maximum degradation section extraction process shown in FIG. 12, it is analyzed whether the extracted section is the section of the maximum degradation value between the root node and the leaf node in the subtree. The section with the maximum value is extracted (step S80).
The output unit 16 of the degraded path detection device 1 outputs the detected degraded path after the above process ends (step S90).
Details of each process from step S40 to step S80 will be described below. The input parameter of each process of step S40 to step S80 is the node selected in step S30. Note that the node (router R) selected in step S30 is referred to as a “selected node”.

[2.2.2 Subtree data construction process]
[2.2.2.1 Processing flow]
FIG. 5 is a diagram showing a processing flow of the subtree data construction processing by the subtree network construction unit 11 of the degraded path detection device 1, and shows the detailed processing of step S40 in FIG. Note that the construction method of the subtree and the structure of the subtree data are examples, and the present invention is not limited thereto.

  First, the subtree network construction unit 11 of the degraded path detection device 1 newly generates and writes the node information of the selected node in the storage unit 15, and writes the node ID of the selected node in the node ID of the generated node information. (Step S101). Subsequently, the subtree network construction unit 11 refers to the network topology information stored in the network topology information storage device 2, and extracts the node IDs of all child nodes of the selected node (step S102).

  If the subtree network construction unit 11 determines that the node information in which the node ID of the extracted child node is set is not yet registered in the storage unit 15 (step S103: NO), the subtree network construction unit 11 stores the node information in step S102. The node information of the extracted child node is newly generated and written, and the node ID of the corresponding child node is written in the generated node information (step S104). Furthermore, the subtree network construction unit 11 writes the node information of the child node generated in step S104 into the child node list in the node information of the selected node generated in step S101 (step S105).

  On the other hand, if it is determined that the node information in which the node ID of the child node extracted in step S102 is set is already registered in the storage unit 15 (step S103: YES), the subtree network construction unit 11 The node information in which the node ID of the child node is set is extracted from 15, and the node information of the extracted child node is written in the child node list in the node information of the selected node generated in step S101 (step S105).

[2.2.2.2 Description of processing by specific example]
For example, there is one node in the second hierarchy, and its child nodes are node N [1] and node N [2] in the first hierarchy, and node N [1] has node N [3] in the measurement terminal layer. To the node N [5], and the node N [2] is connected to the node N [6] and the node N [6] to the node N [8]. Is assumed.
Since the entire algorithm shown in FIG. 4 performs processing in order from the node included in the first hierarchy, in this case, the node selected first in step S30 is either node N [1] or node N [2]. It becomes. Since the subtree data construction process is the same in both cases, the case where the node N [1] is selected will be described.

(1) Since the node N [1] is selected, node information in which the node ID “1” is set corresponding to the node N [1] is generated and registered in the storage unit 15 (step S101).

(2) The child nodes connected to the node N [1] are the measurement terminals T as the nodes N [3] to N [5], and the node information for these child nodes has not been generated. Node information of N [3] to N [5] is generated and registered in the storage unit 15 (steps S102 to S104).
Thereby, node information in which the node ID “3” is set, node information in which the node ID “4” is set, and node information in which the node ID “5” is set are generated.

(3) In order to associate the node N [1], which is the selected node, with the nodes N [3] to N [5], which are the child nodes, all the children generated in (2) are included in the node information of the selected node. The node information of the node is written as a child node list (step S105).

  When a node included in another first hierarchy becomes a selected node, the same processing as described above is performed. However, when a node in the second hierarchy or higher becomes a selected node, the same applies until the node information of the selected node is generated (step S101), but the node information of the child node has already been generated (step S102, S103: NO). Therefore, a process of adding the node information list of the generated child nodes as a child node list to the node information of the selected node (step S105).

[2.2.3 Measurement process in subtree]
[2.2.3.1 Process flow]
FIG. 6 is a diagram showing a processing flow of the sub-tree measurement processing in the degraded path detection device 1, and shows detailed processing in step S50 of FIG. This processing flow includes a method for selecting the measurement terminal T in the subtree and a process based on the measurement deterioration value obtained by the measurement between the selected measurement terminals T.

The selection method of the first measurement terminal T in the subtree is selected so that the coverage rate is 100% for the following reason.
(A) Failure to measure all elements in the network so that they pass through at least once may lead to detection failure of a degraded path.
(B) In the first measurement, if a path with a coverage rate exceeding 100% is measured, the path may become an unnecessary path for detecting a degraded path, and an unnecessary load is applied to the network.
That is, first, measurement is performed at a coverage rate of 100%, and measurement based on the measurement result is performed, so that the minimum necessary measurement is achieved.

  The measurement terminal selection / degradation analysis unit 14 of the degradation path detection apparatus 1 selects an unselected child node from among the child nodes indicated by the child node list set in the node information of the selected node, and all the children are selected. The following steps S202 to S216 are performed until selection for the node is completed (step S201).

  First, the measurement terminal selection / deterioration analysis unit 14 determines whether the selected node is included in the first hierarchy (step S202). When included in the first hierarchy (step S202: YES), the measurement instruction execution unit 12 determines that from among the unselected child nodes if there are two or more unselected child nodes (step S206: two or more). If two child nodes are selected at random (step S208) and the number of unselected child nodes is one (step S206: one), 1 is randomly selected from the unselected child nodes and the selected child nodes. Is selected (step S207).

  On the other hand, when the selected node is not included in the first hierarchy (step S202: NO), the measurement terminal selection / degradation analysis unit 14 has two or more unselected child nodes (step S203: two or more). From the unselected child nodes, two child nodes having the largest link total degradation value are selected (step S205). If the number of unselected child nodes is 1 (step S203: 1), the unselected And the selected child node having the smallest total link degradation value are selected (step S204). The link total deterioration value is read from the node information of the child node set as the child node list in the node information of the selected node.

  Subsequent to step S208 or step S205, when the measurement terminal selection / degradation analysis unit 14 generates child node pair information and writes the child node pair information in the storage unit 15, nodes of the selected two child nodes are included in the generated child node pair information. The ID is written (step S209). The measurement terminal selection / degradation analyzer 14 adds the child node pair information generated in step S209 as a child node pair list to the node information of the selected node (step S210). When the measurement terminal selection / degradation analysis unit 14 identifies the measurement terminal T associated with each of the two child nodes of the selected child node pair and reads the address information (step S211), the measurement instruction execution unit 12 reads the address information. A measurement instruction is output to the measurement terminal T specified using the address (step S212). The measurement instruction includes address information of the counterpart measuring terminal T.

  The measurement terminal T that has received the measurement instruction from the degraded path detection device 1 transmits a quality measurement packet to the paired measurement terminal T, and degrades the transmission information of the communication packet obtained as a result. Return to the path detection device 1. When the measurement result reception / degradation value calculation unit 13 of the degradation path detection apparatus 1 receives the transmission information of the communication packet from the measurement terminal T that has output the measurement instruction as the measurement result (step S213), the measurement result reception / degradation value calculation unit 13 A measurement degradation value is obtained based on the time stamp and the sequence number. Here, it is assumed that a delay is obtained. The measurement terminal selection / deterioration value analysis unit 14 corrects the calculated measurement deterioration value, and then writes the corrected deterioration value to the path deterioration value of the child node pair information added in step S210 (step S214). The measurement degradation value correction is a process of subtracting the sum of link degradation correction values set in the node information of the nodes included in the measurement path.

  When the path degradation value is “0” (step S215: YES), the measurement terminal selection / degradation value analysis unit 14 sets the link degradation value in the node information in which the node ID of the selected child node pair is set to “ "0" is written (step S216).

  When the processing up to step S216 is completed for all the child nodes of the selected node, the measurement terminal selection / degradation value analysis unit 14 refers to the child node pair information in which the path degradation value is written in step S214, and measures the above. Of the child node pairs that have been subjected to the above, a child node pair whose path degradation value exceeds a predetermined threshold value for detecting a degradation path is extracted (step S217). If there is no child node pair extracted in step S217 (step S218: NO), measurement terminal selection / deterioration value analysis unit 14 ends the process and returns to the caller. When there is a child node pair extracted in step S217 (step S218: YES), a path between the measurement terminals T associated with the extracted child node pair is detected as a degraded path (step S219), and the extracted child node pair is input. The measurement degradation path process shown in FIG. 7 is executed (step S220).

[2.2.3.2 Description of processing by specific example]
The contents of the measurement process in the sub-tree for the sub-tree data based on the measurement with the coverage rate of 100% will be described according to the processing flow described above.

(1) The measurement terminal selection / deterioration analysis unit 14 creates two pairs from the child nodes of the selected node, and generates child node pair information for each pair (steps S201 to S209).
Here, since it is desired to perform measurement with a coverage rate of 100%, a pair of child nodes is paired so as to minimize duplication. Then, child node pair information is generated for each paired child node. For example, in the child node pair information when the selected node is the node N [1] and the node N [2] and the node N [3] among the child nodes are child node pairs, the node IDs “2” and “3” Is set.

(2) Subsequently, the measurement terminal selection / degradation analysis unit 14 associates the child node pair information generated in (1) with the selected node (step S210).
For example, it is assumed that the selected node is the node N [1], and the child nodes of the node N [1] are the node N [2], the node N [3], the node N [10], and the node N [11]. In this case, node ID “1” and child node list “2, 3, 10, 11” are set in the node information of the selected node. When a pair of the node N [2] and the node N [3] and a pair of the node N [10] and the node N [11] are generated, the node information of the selected node includes a node list as a child node pair list. Child node pair information set with IDs “2” and “3” and child node pair information set with node IDs “10” and “11” are set.

(3) The measurement instruction execution unit 12 performs measurement between the measurement terminals T associated with each of the generated child node pairs, and the measurement result reception / deterioration value calculation unit 13 adds the measurement result received from the measurement terminal T to the measurement result. Based on this, a measured deterioration value is calculated. The measurement terminal selection / degradation value analysis unit 14 subtracts the link degradation correction value set in the node information of the node included in the measurement path from the measurement degradation value, and sets the subtraction result as the path degradation value of the child node pair information. (Steps S211 to S215).
For example, as shown in FIG. 14, the selected node is the node N [1], the child node pair of the node N [1] is the node N [2], the node N [3], and the measurement terminal T associated with the node N [2]. The node N [6] connected to the node N [4] that is the child node and the measurement terminal T attached to the node N [3] are connected to the node N [7] that is the child node N [5]. ]. Assume that quality measurement is performed between the measurement terminals T having the relationship shown in FIG. 5, that is, between the node N [6] and the node N [7], and the measurement deterioration value is “40”.
At this time, if link deterioration correction values are not set for all the node information for each node in the measurement path, the path deterioration values of the child node pair information in which the node IDs “2” and “3” are set include: The measurement deterioration value “40” is set as it is.

On the other hand, when the link degradation correction value is set in the node information for the nodes in the measurement path, the total value of the link degradation correction values is subtracted from the measurement degradation value, and the subtraction result is used as the path degradation value of the child node pair information. Set.
For example, if the link deterioration correction value “10” is set in the node information corresponding to the node N [4] and the link deterioration correction value “20” is set in the node information corresponding to the node N [7], A certain “30” is subtracted from the measured degradation value “40”, and the subtraction result “10” is written in the path degradation value of the child node pair information in which the node IDs “2” and “3” are set.

(4) If the value set in the path degradation value of the child node pair information is “0”, the measurement terminal selection / degradation value analysis unit 14 includes the node information in the node information for the two node IDs set in the child node pair information. “0” is written in the link deterioration value (steps S215 to S216).
For example, it is assumed that “0” is set as the path degradation value of the child node pair information of the node IDs “2” and “3”. “0” is also set to the link deterioration value of the node information of the node N [2] in which the node ID “2” is set and the node information of the node N [3] in which the node ID “3” is set. To do.

(5) When measurement is performed for all child node pairs and the setting of the path degradation value is completed, the measurement terminal selection / degradation value analysis unit 14 extracts child node pair information in which the path degradation value exceeding the degradation threshold is set. To do. If extraction is possible, the path between the measurement terminals T associated with each node specified by the extracted child node pair information is detected as a degraded path, and the extracted child node pair information is passed to the measurement degraded path processing (step S217 to S220).

[2.2.4 Measurement degradation pass processing]
[2.2.4.1 Processing flow]
FIG. 7 is a diagram illustrating a processing flow of measurement degradation path processing in the degradation path detection apparatus 1.
The measurement degradation path process includes a method for selecting the measurement terminal T in the subtree and a process based on the measurement degradation value obtained by the measurement between the selected measurement terminals T.

In the measurement degradation path processing shown in the figure, the path degradation value obtained from the measurement degradation value obtained by the measurement with the coverage rate of 100% and the link degradation correction value in the node information corresponding to the node in the measurement path is degraded. This is processing when a degraded path exceeding a threshold is detected.
As can be said in other processes as well, by setting the path degradation value and the degradation value of each link in the degradation path to “0”, a part of the degradation paths that have been detected by other paths. , The state of being detected as a degraded path (when the degradation in another degraded path is eliminated, the degraded state is eliminated) is suppressed.
In addition, since the section with the second highest degradation value between the root node and the leaf node is connected to the maximum degradation section in other subtrees, it may become a degraded path, so the subtree is reconstructed. By doing so, it is possible to detect such a path.

  In the figure, the measurement terminal selection / degradation value analysis unit 14 of the degraded path detection device 1 performs the following step S302 until all the child node pair information of the child node pair detected as a degraded path in step S219 in FIG. 6 is selected. To S311 are performed (step S301).

  First, the measurement terminal selection / degradation value analysis unit 14 includes unselected child node pair information other than the child node pair information selected in step S301 among the child node pair information of the child node pair detected as a degraded path in step S219 in FIG. It is determined whether the number of is one or more (step S302). If it is determined that there are two or more (step S302: two or more), the measurement terminal selection / degradation value analysis unit 14 randomly selects two child node pair information from unselected child node pair information (step S303). When it is determined that there is one (step S302: one), one is randomly selected from the child node pair information set in the child node pair list set in the node information of the selected node, Unselected child node pair information is selected (step S304).

  The measurement terminal selection / degradation value analysis unit 14 links the child node indicated by the child node pair information selected in step S303 or S304 (described as “selector node pair information” in the description of this processing flow) as shown in FIG. A deterioration value calculation process is executed to calculate a link deterioration value between each child node and the selected node (step S305). Subsequently, the measurement terminal selection / deterioration value analysis unit 14 determines whether or not the selected node is a node in the first hierarchy (step S306).

  If the selected node is a node in the first hierarchy (step S306: YES), “0” is written in the path degradation value of the selector node pair information (step S307). Further, the measurement terminal selection / degradation value analysis unit 14 sets the currently set link degradation value as the link degradation correction value for the node information of the child node indicated by the selector node pair information, and then the link degradation value. Is set to “0” (step S308).

  On the other hand, when the selected node is not a node in the first hierarchy (step S306: NO), the measurement terminal selection / deterioration value analysis unit 14 determines the child from the selector node pair information selected from unselected in step S303 or S304. The node ID of the node is extracted (step S309), and the subtree reconstruction process shown in FIG. 13 is performed on the child node of the extracted node ID (step S310). In the subtree reconstruction process, the subtree is reconstructed so that the second highest section after the degradation value between the root node and the leaf node in the degradation path becomes a component of the subtree. Upon completion of the subtree reconstruction process, the measurement terminal selection / degradation value analysis unit 14 determines link degradation from the node information of the nodes included in the path between the measurement terminals T attached to each child node after the reconstruction process. The value is read and the sum is calculated, and the link deterioration value of the calculation result is set as the path deterioration value of the child node pair information (step S311).

[2.2.4.2 Description of processing by specific example]
A process for subtree data when a degraded path is detected by measuring 100% coverage according to the processing flow described above will be described.
For example, in the subtree shown in FIG. 14, the measurement terminal T associated with each of the node N [2] and the node N [3] that are the child node pairs of the node N [1] that is the selection node, that is, the node N [6] Consider the case where the path degradation value is “70” as a result of the quality measurement between the nodes N [7] and exceeds the degradation threshold. In this case, “70” is set as the path degradation value of the child node pair information in which the node IDs “2” and “3” are set.

(1) The degradation value of the link between a selection node and each child node is calculated by making the child node pair information that became a degradation path into two pairs (steps S301 to S305).
The pairing method of the child node pair information differs depending on whether the extracted child node pair information is an even number or an odd number. When the extracted child node pair information is an even number, pairing is performed only from the extracted child node pair information. In the case of an odd number, pairing is performed only from the extracted child node pair information, and the last one child node pair information is paired by selecting one from the other child node pair information. Further, the link deterioration value between the child node indicated by the extracted child node pair information and the selected node is calculated by a link deterioration value calculation process described later.

(2) When the selected node is included in the first hierarchy, the path degradation value of the child node pair information used for the measurement is changed to “0”, and the calculated link degradation value between the selected node and each child node is The link degradation correction value of the node information of each child node is set, and “0” is set as the link degradation value (steps S306 to S308).
For example, the selected node is the first layer node N [10], and two measurement terminals T as the node N [11] and the node N [12] are connected to the node N [10]. 11] −N N [12] is assumed to have a degradation value of “70”. The partial tree network construction unit 11 rewrites the path degradation value “70” currently set in the child node pair information of the node IDs “11” and “12” to “0”.
Further, in the link degradation value calculation process in step S305, the degradation value between the node N [10] and the node N [11] is “40”, and the degradation value between the node N [10] and the node N [12] is “30”. ”. The measurement terminal selection / degradation analysis unit 14 writes the link degradation value “0” and the link degradation correction value “40” in the node information of the node ID “11”, and in the node information of the node ID “12”. The link deterioration value “0” and the link deterioration correction value “30” are written.

(3) When the selected node is other than the first layer, the measurement terminal T attached to each child node is different from the measurement terminal T when the degraded path is detected by the subtree data reconstruction process (details will be described later) in step S310. (Steps S309 to S311).
In order to perform the degraded section candidate extraction process to be performed next, it is necessary to assign a path degradation value consistent with the subtree configuration to all the child node pair information of the selected node. Therefore, the sum of the link deterioration values set in the node information of each node belonging to the path between the measurement terminals T attached to the two nodes set in the child node pair information after the subtree data reconstruction processing is calculated Then, the calculation result is set to the path deterioration value.

FIG. 15A shows the link degradation value of each link in the subtree of FIG. 14, and FIG. 15B shows the node information of the nodes in the subtree. Result of measurement between the measurement terminals T associated with the node N [2] and the node N [3], which are child node pairs of the selected node N [1], that is, between the node N [6] and the node N [7]. This shows a state in which the link degradation value is detected as a degraded path and the link degradation value between the selected node and each child node is calculated by the link degradation value calculation processing in step S306. The link degradation value between the selected node and each child node is “10” between the node N [1] and the node N [2], and “0” between the node N [1] and the node N [3].
At this time, as a result of executing the partial tree data reconstruction (step S310), as shown in FIG. 16A, the measurement terminal T attached to the node N [2] is moved to the node N [10], and the node N [3 ] Is changed to node N [11], and the node information of each node in the degraded path is changed.

As shown in FIG. 16B, in the node information of the node N [2], the link degradation value is changed from “10” to “0”, the link total degradation value is changed from “30” to “10”, and the link degradation is performed. The correction value is updated from “NULL” to “10”, and in the node information of the node N [3], the link degradation value is changed from “0” to “0”, and the subtree configuration nodes are “5” to “9”. In addition, the link total deterioration value is updated from “30” to “20”, and the link deterioration correction value is updated from “NULL” to “0”.
Further, in the node information of the node N [4], the link degradation value is changed from “0” to “0”, the subtree configuration node is changed from “6” to “10”, and the link total degradation value is changed from “30” to “30”. 10, the link degradation correction value is updated from “NULL” to “0”, and in the node information of the node N [5], the link degradation value is changed from “20” to “0”, and the subtree configuration node is “0”. The link total deterioration value is updated from “10” to “10”, and the link deterioration correction value is updated from “NULL” to “20” from “7” to “8”.
Further, in the node information of the node N [6], the link deterioration value is updated from “30” to “0”, the link deterioration correction value is updated from “NULL” to “30”, and the node information of the node N [7] is updated. , The link deterioration value is updated from “10” to “0”, and the link deterioration correction value is updated from “NULL” to “10”.

This means that the path between the measurement terminals T associated with the node N [2] and the node N [3] has been changed by the subtree data reconstruction process.
Therefore, the subtree network construction unit 11 uses each node (node N [2], node N [3], node N as the path degradation value of the child node pair information indicating the node N [2] -node N [3] pair. N [4], node N [9], node N [10], node N [11]) is set to “30”, which is the sum of the link degradation values (0, 0, 0, 10, 10, 10). . That is, the path degradation value “30” is set in the child node pair information of the node IDs “2” and “3”.
Through the processing so far, the path degradation value of the child node pair information indicating the node N [2] -node N [3] pair is set to “70” in step S214 and changed to “30” in step S311. .

[2.2.5 Link degradation value calculation processing]
[2.2.5.1 Processing Flow]
FIG. 8 is a diagram illustrating a processing flow of link degradation value calculation processing in the degradation path detection device 1.
In the link degradation value calculation process, the degradation value of each link between the selection node that is the root node of the subtree and the four child nodes of the selection node is calculated.

  In the figure, the measurement terminal selection / degradation value analysis unit 14 reads out the node ID set in each of the two selected child node pair information, and link degradation is performed on all of the node information specified by the read node ID. It is determined whether or not a value is set (step S401). If it is determined that link degradation values are set for all the node information (step S401: YES), the process is terminated as it is. If it is determined that there is a link deterioration value that is not set in the identified node information (step S401: NO), the measurement terminal selection / deterioration value analysis unit 14 is the same for both of the two child node pair information. It is determined whether or not the node ID is set (step S402).

  When it is determined that the same node ID is set in both of the two child node pair information (step S402: YES), the measurement terminal selection / deterioration value analysis unit 14 is set only in one child node pair information. A node ID is extracted (step S403). At this time, two node IDs are extracted. The measurement terminal selection / degradation value analysis unit 14 specifies the measurement terminal T associated with the node specified by the extracted two node IDs, and the measurement instruction execution unit 12 specifies the address of the measurement terminal T specified from the network topology information. When the information is read, a measurement instruction in which the address information of the partner measurement terminal T is set is output to the specified measurement terminal T. The measurement terminal T that has received the measurement instruction from the degraded path detection device 1 transmits a quality measurement packet to the paired measurement terminal T, and degrades the transmission information of the communication packet obtained as a result. Return to the path detection device 1. The measurement result reception / degradation value calculation unit 13 of the degradation path detection apparatus 1 receives the transmission information of the communication packet from the measurement terminal T that has output the measurement instruction as a measurement result, and obtains a measurement degradation value (step S404).

On the other hand, when it is determined that the same node ID is not set in both of the two child node pair information (step S402: NO), the measurement terminal selection / degradation value analysis unit 14 sets one of the two child node pair information. When a node ID is extracted at random from the node IDs that have been set (step S405), the measurement terminal T associated with the node specified by the extracted node ID is specified (step S406). The specified measurement terminal T is referred to as terminal A. Further, when the measurement terminal selection / degradation value analysis unit 14 extracts the two node IDs set in the other child node pair information, the measurement terminal T associated with each of the nodes specified by the extracted two node IDs. Is specified (step S407). The specified measurement terminals T are referred to as a terminal B and a terminal C, respectively.
When the measurement instruction execution unit 12 reads the address information of the terminals A, B, and C specified from the network topology information, the measurement instruction execution unit 12 outputs a measurement instruction between the terminal A and the terminal B to the terminal A and the terminal B, and A measurement instruction between terminal A and terminal C is output to A and terminal C. The terminals A, B, and C that have received the measurement instruction from the degraded path detection device 1 transmit a quality measurement packet to the paired measurement terminal T and transmit the communication packet obtained as a result. Information is returned to the degraded path detection apparatus 1. The measurement result reception / degradation value calculation unit 13 of the degraded path detection device 1 calculates the measurement degradation value between the terminal A and the terminal B and between the terminal A and the terminal C from the transmission information of the received communication packet. A terminal-to-terminal deterioration value after correcting the measurement deterioration value is obtained (step S408).

  The measurement terminal selection / deterioration value analysis unit 14 calculates the deterioration value of the selected node and each measurement terminal T from the measurement deterioration value obtained in step S404 or the inter-terminal deterioration value after correction processing obtained in step S408. Calculate (step S409). Further, the measurement terminal selection / deterioration value analysis unit 14 calculates a deterioration value between each child node specified by the node ID in the child node pair information and the selected node that is the parent node, and the node ID of the child node The calculated link degradation value is written in the node information specified by (step S410).

[2.2.5.2 Explanation of Processing by Specific Example]
The measurement and calculation method for calculating the deterioration value between the selected node and the child node of the selected node by the link deterioration value calculation process shown in FIG. 8 will be described.

(1) The input to the link degradation value calculation process is two child node pair information. If link degradation values are set for all the node information of nodes belonging to these, this process is skipped because there is no need to newly calculate (step S401).

(2) When calculating the link degradation value, the following two may be considered depending on the state of the node belonging to the selected child node pair information.
(State 1) As shown in FIG. 17A, one child node pair of the selected node N [1] is node N [2] -node N [3], and the other child node pair is node N [3. ] Suppose node N [4]. Nodes N [2], [3], and [4] are connected to measurement terminals T of nodes N [10], [11], and [12], respectively.
(State 2) As shown in FIG. 18A, one child node pair of the selected node N [1] is node N [2] -node N [3], and the other child node pair is node N [4]. ] Suppose node N [5]. In this case, there is no overlapping node in the two child node pair information.

(2-1): In the case of the state 1 shown in FIG. 17A, since the node overlapping with the two child node pair information is the node N [3], as shown in FIG. Node N [2] and node N [4] belonging to only the node pair are extracted, and measurement is performed between measurement terminals T associated with the extracted node, that is, node N [10] -node N [12]. The measurement deterioration value is calculated (steps S402 to S404).

(2-2): In the case of state 2 shown in FIG. 18A, nodes are randomly extracted from one child node pair (node N [2] -node N [3]) (for example, node N [2]). Then, the measurement terminal T associated with the node is extracted as the terminal A (node N [10]) (steps S405 to S406).
Next, the measurement terminal T associated with each of the other child node pairs (node N [4], node N [5]) is extracted as terminal B (node N [12]) and terminal C (node N [13]). . And as shown in FIG.18 (b), it measures between terminal A-terminal B and terminal A-terminal C, and calculates a measurement degradation value (step S407, S408).

(3) The measurement terminal selection / degradation value analysis unit 14 measures the measurement degradation value obtained by the measurement here, the link degradation value / link degradation correction value of each node in the measurement path here, and information on two child node pairs The degradation value between the selected node and each node in the child node pair information is calculated from the path degradation value set in, and the calculation result is set to the link degradation value in the node information of each child node (step S409). , S410).
Details of the degradation value calculation procedure between the selected node and each node in the child node pair information are shown below. Note that the calculation method is not greatly different depending on the presence or absence of overlapping nodes in the two child node pair information, and only the number of equations is different.

(Procedure 1) The link deterioration correction value belonging to the measurement path is subtracted from the measurement deterioration value.
The measured deterioration value between the node N [10] (terminal A) and the node N [12] (terminal B) is “60”. The node information of the node N [10] includes the link deterioration value “0”, the link It is assumed that the deterioration correction value “30” is set, and the node deterioration information “20” and the link deterioration correction value “0” are set in the node information of the node N [12].

At this time, the degradation value between the node N [10] and the node N [12] is “10” (= 60 (measured degradation value) −30 (link degradation correction value of the node N [10]) − 20 (node N [ 12], which means a degradation value between node N [2] and node N [4].
The same process is performed for the path between the node N [10] (terminal A) and the node N [13] (terminal C), and the deterioration value between the node N [2] and the node N [5] is calculated. . Here, it is assumed that the calculation result is “20”.

  As shown in FIG. 18C, the degradation value between the node N [1] and the node N [2] is “L1”, and the degradation value between the node N [1] and the node N [3] is “L2”. Assuming that the degradation value between the node N [1] and the node N [4] is “L3” and the degradation value between the node N [1] and the node N [5] is “L4”, the following holds according to the above calculation. Means that.

L1 + L3 = 10 Deterioration value between node N [2] and node N [4] (formula 1)
L1 + L4 = 20 Deterioration value between node N [2] and node N [5] (formula 2)

(Procedure 2) The link degradation value of the node belonging to the path between the measurement terminals T associated with each node pair is subtracted from the path degradation value in the two child node pair information.
The link deterioration value “30” is set in the child node pair information of the node N [2] and the node N [3], the link deterioration value “0” and the link deterioration correction value “30” are set in the node information of the node N [10]. ”And the link deterioration value“ 10 ”and the link deterioration correction value“ NULL ”are set in the node information of the node N [11].
At this time, 30 (path degradation value set in child node pair information of node N [2] and node N [3])-0 (path degradation value of node N [10])-10 (node N [11] Path degradation value) = “20” means a degradation value between the node N [2] and the node N [3].
Similarly, it is assumed that the deterioration value between the node N [4] and the node N [5] is calculated and the calculation result is “10”. At this time, the following holds.

L1 + L2 = 20 Deterioration value between node N [2] and node N [3] (formula 3)
L3 + L4 = 10 Deterioration value between node N [4] and node N [5] (formula 4)

  The following is obtained by solving the equations consisting of the four obtained (Expression 1) to (Expression 4).

  L1 = 10, L2 = 10, L3 = 0, L4 = 10

  The obtained result is set to the link degradation value of each node. That is, the link degradation value “10 (L1)” is stored in the node information of the node N [2], the link degradation value “10 (L2)” is stored in the node information of the node N [3], and the node information of the node N [4]. In this case, “0 (L3)” is written in the link degradation value and “10 (L4)” is written in the link degradation value of the node N [5].

[2.2.6 Deterioration section candidate extraction process]
[2.2.6.1 Processing flow]
FIG. 9 is a diagram illustrating a processing flow of the degradation section candidate extraction process in the degradation path detection apparatus 1.
In the degradation section candidate extraction process, two paths with the maximum path degradation value are extracted from the measurement paths with the coverage rate of 100%, and the section with the maximum degradation value between the selected node and the measurement terminal T is extracted from the two paths. This is a process for extracting. However, since the path degradation value of a path that has been detected as a degraded path by measurement with a coverage rate of 100% is corrected to “0” at the time of detection, the path degradation value is the largest in a range that is not determined to be degraded. Two paths are targeted.
The reason for extracting the two paths with the maximum path degradation value is that the possibility that the path has the maximum degradation value between the selected node and the measurement terminal T is the highest. This is because the analysis has begun. When a deteriorated path is detected in the process of extracting the deteriorated section candidate, the correction process of the path deteriorated value and the link deteriorated value to “0”, and the subtree, as in the description of the flowchart of the measured deteriorated path treatment described above, Perform the rebuild process.

  In the figure, first, the measurement terminal selection / degradation value analysis unit 14 reads the path degradation values of all the child node pair information set in the node information of the selected node, and the maximum value of the read path degradation values is “0”. Is determined (step S501). When the maximum value is “0” (step S501: YES), the measurement terminal selection / deterioration value analysis unit 14 selects child node information for which the link deterioration value is set from all the child nodes of the selected node. When the node ID is specified and one of the node IDs set in the specified child node information is selected at random (step S502), the node ID of the selected child node is set as the subtree constituting node of the node information of the selected node. Then, the process ends (step S513).

  If it is determined in step S501 that the maximum value is not “0” (step S501: NO), the measurement terminal selection / degradation value analysis unit 14 includes all child node pair information set in the node information of the selected node. The two child node pair information having the largest path degradation value is selected (step S503). The measurement terminal selection / degradation value analysis unit 14 performs the link deterioration value calculation process shown in FIG. 8 for the selected child node pair information, and the child node specified by the node ID set in the selected child node pair information; A link degradation value with the selected node is calculated (step S504).

  When the measurement terminal selection / degradation value analysis unit 14 reads the node ID set in the child node pair information selected in step S503 and specifies the measurement terminal T associated with the child node specified by the read node ID, Deterioration values are calculated for the paths of all combinations of the specified measurement terminals T (step S505). The degradation value of the path from the selected node to the measurement terminal T associated with a certain child node is the sum of the link degradation value set in the node information of the child node and the link total degradation value. Therefore, the degradation value of the path between the selected node and the measurement terminal T associated with each node can be calculated from the node information of each child node set in the node information of the selected node. Depending on the combination of the measurement terminals T, the calculated deterioration value of the path between the selected node and the measurement terminal T can be added to calculate the deterioration values for the paths of all combinations of the measurement terminals T. The measurement terminal selection / deterioration value analysis unit 14 determines whether any of the deterioration values calculated in step S505 exceeds the deterioration threshold (step S506).

  If it is determined that there is nothing exceeding the degradation threshold (step S506: NO), the child node having the maximum sum of the link degradation value and the link total degradation value is selected from the child nodes of the selected node (step S512). Specifically, the node information of the child node is read from the child node list set in the node information of the selected node, and the sum of the link deterioration value and the link total deterioration value is maximum from the node information of this child node. Select the node information. The subtree network construction unit 11 sets the node ID in the node information of the child node selected in step S512 to the subtree constituting node of the node information of the selected node, and returns to the caller when the process is completed (step S513).

  When it is determined in step S506 that there is an object that exceeds the deterioration threshold (step S506: YES), the measurement terminal selection / deterioration value analysis unit 14 detects a path between the measurement terminals T that exceeds the deterioration threshold as a deterioration path. (Step S507) The child node of the selected node belonging to the detected degraded path, that is, the child node identified as the measurement terminal T associated with the measurement terminal T in Step S505 is extracted (Step S508).

  When the measurement terminal selection / degradation value analysis unit 14 determines that the selected node is a node in the first hierarchy (step S508-1: YES), the link degradation value currently set in the node information of the extracted child node Is set to the link deterioration correction value, and then “0” is set to the link deterioration value (step S514). The measurement terminal selection / deterioration value analysis unit 14 extracts and extracts the child node pair information in which the node ID of the child node extracted in step S508 is set from the child node pair information associated with the node information of the selected node. The current path deterioration value of the child node pair information thus updated is updated to a value obtained by subtracting the link correction value set in the node information of the selected node in step S514 (step S515). Thereafter, the degradation section candidate extraction process is recursively executed for the selected node (step S516).

  On the other hand, if the measurement terminal selection / deterioration value analysis unit 14 determines that the selected node is not a node in the first hierarchy (step S508-1: NO), the child node extracted in step S508 is input, and will be described later. The partial tree data reconstruction process shown in FIG. 13 is performed (step S509). In the subtree reconstruction process, the subtree is reconstructed so that a section in which the degradation value between the root node and the leaf node is the second highest after the degradation path becomes a constituent element of the subtree. The measurement terminal selection / deterioration value analysis unit 14 selects child node pair information including the node ID of the child node extracted in step S508 from the child node pair information associated with the node information of the selected node (step S508). S510). The measurement terminal selection / degradation value analysis unit 14 calculates the sum of the link deterioration values of the nodes included in the path between the measurement terminals T attached to each node after the reconstruction processing in step S509, and uses the calculated result as child node pair information. Is set to the path degradation value (step S511). Thereafter, the degradation section candidate extraction process is recursively executed for the selected node (step S516).

[2.2.6.2 Description of processing by specific example]
(1) Two child node pair information having the largest value is extracted from the path degradation values in the child node pair information set in the selected node (step S503).
If a part of the path between the measuring terminals T that can be configured using the extracted child node pair information overlaps with a part of the path that has already been determined to be deteriorated by another path, the deterioration value of the overlapping part has been corrected. is there. Therefore, since there is a high possibility that the section between the selected node and the measurement terminal T included in the path having the maximum path degradation value becomes a part of the degradation path, such child node pair information is extracted.

(2) Four child nodes of the selected node included in the two child node pair information extracted in (1) are specified, and deterioration values between the four specified nodes and the selected node are respectively calculated. . Then, it is determined from this calculated deterioration value whether or not the measurement terminals T associated with the four child nodes become a deterioration path (steps S504 to S506).
As shown in FIG. 19, in the case of the subtree similar to FIG. 18, between the measurement terminal T [10] and the measurement terminal T [11] and between the measurement terminal T [12] and the measurement terminal T [13] The measurement has been performed by measuring the coverage rate 100%, and the link deterioration value calculation process is performed between the measurement terminal T [10] and the measurement terminal T [12] and between the measurement terminal T [10] and the measurement terminal T [13]. The measurement has already been performed. As a result, the degradation values between the nodes in the subtree are known, and therefore degradation between the measurement terminal [11] and the measurement terminal [12] that are not measured and between the measurement terminal [11] and the measurement terminal [13] is performed. The value can be calculated. That is, the degradation value between the measurement terminal T [11] and the measurement terminal T [12] is the link degradation value set in the node information of the nodes N [10], [2], [4], and [12]. The degradation value between the measurement terminal T [11] and the measurement terminal T [13] is a total, and the link degradation set in the node information of the nodes N [10], [2], [5], and [13] The sum of the values,
In step S505, by calculating the degradation value between the unmeasured measurement terminals, whether or not all of the four nodes N [10], [11], [12], and [13] are degraded paths. Make a decision.

(3) When the degradation value between any measurement terminals T does not exceed the degradation threshold (not a degradation path), a section in which the degradation value between the selected node and the measurement terminal T is maximum is extracted, and selections belonging to the section A child node of the node is registered as a subtree constituting node of the node information of the selected node (steps S512 and S513).
In FIG. 19, the deterioration value between the node N [1] and the measurement terminal [11] (the sum of the deterioration value of the node N [3] and the link total deterioration value of the node N [3]) is greater than the other three sections. If larger, the node N [3], which is a child node of the selected node N [1], is registered as a subtree constituting node of the node information of the selected node N [1].

(4) It is determined whether all of the four measurement terminals T are degraded paths, and when a degraded path is detected, a subtree data reconstruction process is performed in the same manner as in the measured degraded path process, The path degradation value in the extracted child node pair information is updated (steps S507 to S511, S514, and S515).

(5) After the path deterioration value is updated, the deterioration section candidate extraction process is performed again (step S516).
When a degraded path is detected, the path degradation value of each child node pair information may be changed. FIG. 20 is a diagram illustrating an example in which the path degradation value is changed. In the subtree shown in FIG. 20A, the path degradation value between the measurement terminal T [A] and the measurement terminal T [A ′] is 60, and the path between the measurement terminal T [B] and the measurement terminal T [B ′]. The degradation value is 50, the path degradation value between the measurement terminal T [C] and the measurement terminal T [C ′] is 40, and the path degradation value between the measurement terminal T [N] and the measurement terminal T [N ′] is 30. Suppose. In this case, as shown in FIG. 20B, the degradation section candidate processing target path includes a path between node N [A] and node N [A ′], and node N [B] −node N [B ′]. It becomes a path between. The path degradation values between the selected node-node N [A], node N [A ′], node N [B], and node N [B ′] are “40”, “20”, “40”, respectively. ”,“ 10 ”, and the node N [A] -node N [B] is detected as a degraded path.

At this time, between the selected node and the measuring terminal T [A] and between the selected node and the measuring terminal T [B] have been detected as degraded paths, and the link degradation value is corrected to “0”. Therefore, as illustrated in FIG. 20C, the path degradation value between the measurement terminal T [A] and the measurement terminal T [A ′] is the path degradation value “40” between the selected node and the node N [A]. The subtracted “20” and the path degradation value between the measurement terminal T [B] and the measurement terminal T [B ′] are “10” obtained by subtracting the path degradation value “40” between the selected node and the node N [B]. Become.
What is desired to be found in each subtree is a section in which the degradation value between the selected node and the measurement terminal T is maximum. In the case shown in FIG. 20, between the measurement terminal T [C] and the measurement terminal T [C ′], There is a higher possibility that the interval between the measurement terminal T [N] and the measurement terminal T [N ′] includes a section where the degradation value is maximum. Therefore, the degradation section candidate extraction process is performed again.

[2.2.7 Return degradation analysis processing]
[2.2.7.1 Processing flow]
10 and 11 are diagrams showing a processing flow of the aliasing deterioration analysis process in the deterioration path detecting apparatus 1, and show the detailed process of step S70 in FIG.
In the aliasing degradation analysis process, analysis is performed to determine whether or not the measurement terminal T in the degradation segment candidate and the aliasing path between the measurement terminals T in paths other than the two paths used for extraction of the degradation segment candidate are detected as degradation paths. To do.
Therefore, by comparing the degradation value of the degradation section candidate with the path degradation value of another path, measurement is performed only on a possible location and the presence / absence of the degradation path is analyzed. When a degraded path is detected, as described above, a path degradation value or link degradation value correction process and a subtree reconstruction process are performed.

  In FIG. 10, the measurement terminal selection / degradation value analysis unit 14 reads out the node ID from the subtree configuration node set in the node information of the selected node, and sets it in the node information of the child node specified by the read node ID. The sum of the link degradation value and the link total degradation value is calculated (step S601). The measurement terminal selection / degradation value analysis unit 14 sets the node ID of the child node for which the link degradation value is set from the child node pair information set in the child node pair list of the node information of the selected node. In addition, child node pair information in which the sum of the path degradation value set in each child node pair information and the sum calculated in step S601 exceeds the degradation threshold is extracted (step S602). If there is no child node pair information extracted in step S602 (step S602: NO), the process ends.

  If there is child node pair information extracted in step S602, the measurement terminal selection / degradation value analysis unit 14 selects the path deterioration values set in the extracted child node pair information in descending order, and performs the following processing (step S604). Hereinafter, in the description of this processing flow, the child node pair information selected in step S604 is referred to as selector node pair information.

  The measurement terminal selection / degradation value analysis unit 14 randomly selects one of the node IDs of the two child nodes set in the selector node pair information, and the measurement terminal T associated with the child node of the selected node ID. Is identified (step S605). In the description of this processing flow, the specified measurement terminal T is described as “measurement terminal T1”, and the measurement terminal T that is not specified is described as “measurement terminal T1 ′”. Subsequently, the measurement terminal selection / degradation value analysis unit 14 reads out the node ID set in the subtree configuration node of the node information of the selected node, and the measurement terminal T (associated with the child node specified by this node ID ( In the description of this processing flow, “measurement terminal T2”) is specified (step S606).

  The measurement instruction execution unit 12 performs measurement between the measurement terminal T1 specified in step S605 and the measurement terminal T2 specified in step S606. When the measurement instruction execution unit 12 reads the address information of the measurement terminals T1 and T2 from the network topology information, the measurement instruction execution unit 12 outputs a measurement instruction to the measurement terminals T1 and T2. The measurement result reception / degradation value calculation unit 13 of the degraded path detection device 1 receives the transmission information of the communication packet from the measurement terminals T1 and T2 as the measurement result, and obtains the measurement degradation value (step S607).

The measurement terminal selection / deterioration value analysis unit 14 calculates deterioration values between the selected node and the measurement terminal T1 and between the selected node and the measurement terminal T1 ′ based on the measurement deterioration value obtained in Step S607 (Step S607). S608).
The degradation value between the selected node and the measurement terminal T2 can be calculated by summing the degradation values set in the node information of the nodes on the path from the selection node to the measurement terminal T2. Therefore, the degradation value between the selected node and the measurement terminal T1 can be calculated by subtracting the degradation value between the selection node and the measurement terminal T2 from the measurement degradation value in step S607.
Further, the deterioration value between the measurement terminal T1 and the measurement terminal T1 ′ can be acquired from the path deterioration value of the selected child node pair information. That is, the degradation value between the selected node and the measurement terminal T1 ′ can be calculated by subtracting the calculated degradation value between the selection node and the measurement terminal T1 from the path degradation value between the measurement terminal T1 and the measurement terminal T1 ′.

The measurement terminal selection / degradation value analysis unit 14 calculates and selects a degradation value between the selected node and each child node set in the selector node pair information based on the degradation value calculated in step S608. The link deterioration value calculated in step S608 is set in the node information of the child node indicated by the child node pair information (step S609).
The degradation value between the selected node and the child node associated with the measurement terminal T1 is the node of the child node associated with the measurement terminal T1 from the degradation value between the selection node and the measurement terminal T1 calculated in step S608. It is obtained by subtracting the total link degradation value set in the information.
Similarly, the deterioration value between the selected node and the child node to which the measurement terminal T1 ′ is attached is associated with the measurement terminal T1 ′ from the deterioration value between the selection node and the measurement terminal T1 ′ calculated in step S608. It is obtained by subtracting the link total deterioration value set in the node information of the child node.

Subsequently, the measurement terminal selection / degradation value analysis unit 14 determines, from the measurement terminal T attached to the subtree constituting node of the selected node, all combinations of measurement terminals T attached to the child nodes indicated by the selector node pair information. A degradation value between the measurement terminals T is calculated (step S610).
In FIG. 11, the measurement terminal selection / degradation value analysis unit 14 determines whether there is a degradation value calculated in step S610 that exceeds the degradation threshold (step S611). If there is no calculation result exceeding the degradation threshold (step S611: NO), the process returns to step S604, and the child node pair information with the next largest path degradation value is selected and processed.

  On the other hand, when there is a calculation result exceeding the deterioration threshold (step S611: YES), the measurement terminal selection / deterioration value analysis unit 14 detects the corresponding path as a deterioration path (step S612), and detects the path detected as the deterioration path. A child node of the selected node belonging to is extracted (step S613).

  When it is determined that the selected node is a node in the first hierarchy (step S614: YES), the measurement terminal selection / degradation value analysis unit 14 links the link degradation value currently set in the node information of the extracted child node. After setting the deterioration correction value, “0” is set to the link deterioration value (step S618). The measurement terminal selection / deterioration value analysis unit 14 extracts the child node pair information in which the node ID of the child node extracted in step S613 is set from the child node pair information set as the node pair list in the node information of the selected node. The current path degradation value of the extracted child node pair information is updated to a value obtained by subtracting the link correction value set in step S618 (step S619). Then, after executing the degradation section candidate extraction process for the selected node (step S620), the aliasing degradation analysis process is performed (step S621).

  If it is determined that the selected node is not a node in the first hierarchy (step S614: NO), the subtree network construction unit 11 performs a subtree data reconstruction process on the extracted child node (step S615). Then, when the measurement terminal selection / degradation value analysis unit 14 extracts the child node pair information including the child node extracted in step S613 from the child node pair information of the selected node (step S616), each child node after the reconstruction process The sum of the link deterioration values of the nodes included in the path between the measurement terminals T attached to is calculated, and the calculation result is set to the path deterioration value of the child node pair information (step S617). Then, after executing the degradation section candidate extraction process for the selected node (step S620), the aliasing degradation analysis process is performed (step S621).

[2.2.7.2 Explanation of processing by specific example]
In the aliasing degradation analysis process, the aliasing degradation path in the subtree, which could not be detected in the subtree measurement or the degradation section candidate extraction process, is detected.

(1) Analyzing whether a degraded path can be detected by connecting a path between the selected node and the measurement terminal T extracted by the degradation section candidate extraction process and a path between another selected node and the measurement terminal T. (Steps S601 and S602).
In order to do this, the sum of the degradation value between the extracted selected node and the measurement terminal T and the path degradation value of the child node pair information to which the node for which the link degradation value is not set belongs is calculated. Analyze whether there is a node pair exceeding the degradation threshold.
Since the path between the measurement terminals T that connects the sections between the selected node for which the link degradation value has already been set and the measurement terminal T has already been determined whether or not it becomes a degradation path, the link degradation is performed. The node pair to which the node for which the value is set belongs is excluded.
Further, when the sum of the path between the extracted selected node and the measurement terminal T and the path degradation value of the child node pair information does not exceed the degradation threshold, the measurement terminal T associated with the node pair and the measurement terminal of the extracted degradation section candidate Since the degradation value between T does not exceed the degradation threshold, it is excluded.

  In the case of the subtree shown in FIG. 21, the degradation section candidate is a section between the selected node having the path degradation value “40” and the measurement terminal T [A], and the measurement terminal T [A] −measurement terminal T [A ′. ], The path degradation value between measurement terminal T [B] and measurement terminal T [B ′] is “40”, and between measurement terminal T [C] and measurement terminal T [C ′]. And the path degradation value between the measurement terminal T [N] and the measurement terminal T [N ′] is “10”.

When the degradation threshold is “70”, the sum of the degradation value “40” of the degradation section candidate and the path degradation value exceeds the degradation threshold between the measurement terminal T [B] and the measurement terminal T [B ′].
Considering between the measurement terminal T [B] and the measurement terminal T [B ′], the distribution of the deterioration values includes a state B1 in which the deterioration value between one selected node and the measurement terminal T is “30” or more. A state B2 in which the degradation value between both the selected node and the measurement terminal T is less than “30” is conceivable.
When the distribution of degradation values between the measurement terminal T [B] and the measurement terminal T [B ′] is in the state B1, the path between the measurement terminal T [A] and the measurement terminal T [B ′] is equal to or greater than the degradation threshold, and degradation occurs. May be a pass. Therefore, the area between the measurement terminal T [B] and the measurement terminal T [B ′] is an analysis target.

  On the other hand, the path between the measurement terminal T [C] and the measurement terminal T [C ′] is a path connected to the degradation section candidate even if the state C in which the degradation value between the selected node and the measurement terminal T is maximized is considered. Since the deterioration threshold is not exceeded, it is excluded from the analysis target. Measurement terminal T [N] −measurement terminal T [N ′] is similarly excluded from the analysis target.

(2) When a path in which the sum of the degradation value of the degradation section candidate and the path degradation value exceeds the degradation threshold can be extracted, measurement is performed between the measurement terminal T of the degradation section candidate and one measurement terminal T belonging to the extracted path. The degradation value between the selected node of the extraction path and the measurement terminal T is calculated. Also, a degradation value (link degradation value of the child node) between the selected node in the extraction path and its child node is calculated from the calculation result, and set in the node information of the child node (steps S605 to S609).

FIG. 22 is a diagram schematically showing the analysis target in FIG. As shown in the figure, the path used for the degradation section candidate extraction process, that is, between the measurement terminal T [A] and the measurement terminal T [A ′], the degradation value (link degradation value) of each link in the path. Is known. Moreover, the link degradation value between node N [4] -measurement terminal T [B] and between node N [5] -measurement terminal T [B '] is also known by the process in the first hierarchy.
Therefore, by performing measurement between the measurement terminal T [A] and the measurement terminal T [B] ′, a degradation value between the node N [1] and the node N [5] is calculated, and the link of the node N [5] The calculation result is set to the deterioration value.
Further, the measurement is performed in the sub-tree measurement between the measurement terminal T [B] and the measurement terminal T [B ′], and since the path degradation value is known, the node N [1] −node N [5] If the degradation value between the nodes N [1] and N [4] can be calculated, the calculation result is set as the link degradation value of the node N [4].

(3) From the above calculation, between node N [1] (selected node) −node N [B] (measurement terminal T [B]) and between node N [1] −node N [B ′] (measurement terminal) Since each deterioration value during T [B]) can be calculated, it can be determined whether it corresponds to state B1 or state B2 shown in FIG. In the case of the state B1, a path between the measurement terminal T [A] and the measurement terminal T [B ′] exceeding the deterioration threshold is detected as a deterioration path. Similarly to the degraded section candidate extraction process, the subtree data reconstruction process is performed, and the path degradation value in the extracted child node pair information is updated (steps S610 to S619).

(4) Similar to the description in the deteriorated section candidate extraction process, the deteriorated value between the selected node and the measuring terminal T in another path may be maximized, so the deteriorated section candidate extraction process is performed again (step) S620).

[2.2.8 Maximum degradation section extraction processing]
[2.2.8.1 Processing flow]
FIG. 12 is a diagram illustrating a processing flow of the maximum degradation section extraction process in the degradation path detection apparatus 1.
In the maximum degradation section extraction process, a section in which the degradation value between the selected node and the measurement terminal T is maximum is determined in the subtree. In the processing so far, all the degraded paths existing in the subtree have been detected, and the degradation value of the link included in the detected degraded path has been corrected to “0”, so the selected node in the subtree The section where the deterioration value between the measurement terminals T is the maximum is the true maximum deterioration section. The determination of the maximum degradation section is performed by comparing the degradation value of the degradation section candidate with the path degradation value of another path, and performing analysis by measurement only when there is a path that can be a degradation value larger than the degradation section candidate. Extract the degradation interval.

  First, the measurement terminal selection / degradation value analysis unit 14 reads out the node ID of the child node from the subtree configuration node set in the node information of the selected node, and from the node information of the child node specified by the read node ID. When the link deterioration value is read, the sum of the read link deterioration value and the link total deterioration value read from the node information of the selected node is calculated and used as a reference deterioration value (step S701). The measurement terminal selection / degradation value analysis unit 14 does not set the node ID of the child node for which the link deterioration value is set from the child node pair information associated with the node information of the selected node, and Then, the child node pair information that exceeds the deterioration value set in each child node pair information and the reference deterioration value calculated in step S701 is extracted (step S702). If there is no child node pair information extracted in step S702 (step S702: NO), the reference deterioration value is set as the total deterioration value in the node information of the selected node (step S714).

  If there is child node pair information extracted in step S702, selection is made in descending order of path degradation values set in the extracted child node pair information, and the following processing is performed (step S704). Hereinafter, in the description of this processing flow, the child node pair information selected in step S704 will be referred to as selector node pair information.

  The measurement terminal selection / degradation value analysis unit 14 randomly selects one of the node IDs of the two child nodes set in the selector node pair information, and the measurement terminal T associated with the child node of the selected node ID. Is specified (step S705). In the description of this processing flow, the specified measurement terminal T is described as “measurement terminal T1”, and the measurement terminal T that is not specified is described as “measurement terminal T1 ′”. Subsequently, the measurement terminal selection / degradation value analysis unit 14 reads out the node ID set in the subtree configuration node of the node information of the selected node, and the measurement terminal T (associated with the child node specified by this node ID ( In the description of the processing flow, “measurement terminal T2”) is specified (step S706).

  The measurement instruction execution unit 12 performs measurement between the measurement terminal T1 specified in step S705 and the measurement terminal T2 specified in step S706. The measurement instruction execution unit 12 outputs measurement instructions to these measurement terminals T1 and T2, and the measurement result reception / deterioration value calculation unit 13 determines the measurement results received from the measurement terminals T1 and T2 that output the measurement instructions. A measurement deterioration value is obtained (step S707).

The measurement terminal selection / degradation value analysis unit 14 determines degradation values between the selected node and the measurement terminal T1, and between the selected node and the measurement terminal T1 ′ (hereinafter, comparative degradation) based on the measurement degradation value obtained in step S707. Each value is calculated (step S708). This can be calculated by the same process as step S608 in FIG.
Further, the measurement terminal selection / degradation value analysis unit 14 calculates a degradation value between the selected node and each child node set in the selector node pair information based on the degradation value calculated in step S708. The link degradation value calculated in step S708 is set in the node information of the child node indicated by the selector node pair information (step S709). This can be calculated by the same processing as step S609 in FIG.

  Subsequently, the measurement terminal selection / deterioration value analysis unit 14 determines whether there is a comparative deterioration value that exceeds the reference deterioration value (step S710). When it is determined that there is a comparative deterioration value that exceeds the reference deterioration value (step S710: YES), the measurement terminal selection / deterioration value analysis unit 14 selects a child node of the selected node that belongs to the path that exceeds the reference deterioration value as the selected node. After the node information is set as a subtree constituting node, the maximum degradation section extraction process is performed (step S711), the process is terminated, and the process returns to the caller.

  On the other hand, if it is determined that there is no comparative deterioration value exceeding the reference deterioration value (step S710: NO), the process returns to step S704, and child node pair information having the next largest path deterioration value is selected from the child node pair information extracted in step S702. If all the child node pair information extracted in step S702 is processed, the reference deterioration value is set as the total deterioration value in the node information of the selected node (step S714). The measurement terminal selection / deterioration value analysis unit 14 ends the process and returns to the caller.

[2.2.8.2 Description of processing by specific example]
In the maximum degradation section extraction process, a section in which the degradation value between the selected node and the measurement terminal T in the subtree is maximized is determined.

(1) First, an analysis is performed to determine whether or not there is a connection between the selected node and the measurement terminal T that has a deterioration value that exceeds the deterioration value between the selected node and the measurement terminal T extracted by the deterioration section candidate extraction process (step S701, S702).
In order to do this, the analysis is performed on the node pair of the child node pair information in which the path deterioration value exceeding the deterioration value between the extracted selected node and the measurement terminal T and the node for which no link deterioration value is set are set. .
The section between the selected node for which the link degradation value has already been set and the measuring terminal T has been compared during the degradation section candidate extraction process, and is therefore excluded from the analysis target.
Further, when the path degradation value of the child node pair information does not exceed the degradation value between the extracted selected node and the measuring terminal T, the degradation value between the measuring terminal T and the selected node associated with the node pair is the degradation that has already been extracted. Since it does not exceed the degradation value of the section candidate, it is excluded.

In the case of the subtree shown in FIG. 23, the degradation section candidate is a section between the selected node having the path degradation value “20” and the measurement terminal T [A], and the measurement terminal T [A] −measurement terminal T [A ′. ], The path degradation value between measurement terminal T [B] and measurement terminal T [B ′] is “30”, and between measurement terminal T [C] and measurement terminal T [C ′]. And the path degradation value between the measurement terminal T [N] and the measurement terminal T [N ′] is “10”.
At this time, a path having a path deterioration value exceeding the deterioration value “20” of the deterioration section candidate is between the measurement terminal T [B] and the measurement terminal T [B ′].

Assuming that the distance between the measurement terminal T [B] and the measurement terminal T [B ′] is considered, the distribution between the degradation values is the degradation between the selected node and one measurement terminal T (measurement terminal T [B ′]). A state B1 in which the value exceeds “20” or a state B2 in which the degradation value between the selected node and both measurement terminals T is less than “20” is conceivable.
When the distribution of deterioration values between the measurement terminal T [B] and the measurement terminal T [B ′] is in the state B1, the path between the selected node and the measurement terminal T [B ′] exceeds the deterioration value of the deterioration section candidate. Since there is a possibility that the degradation value between the selected node and the measurement terminal T in the subtree may be maximized, the area between the measurement terminal T [B] and the measurement terminal T [B ′] is an analysis target.
On the other hand, the path between the measurement terminal T [C] and the measurement terminal T [C ′] is between the selected node and the measurement terminal T even if the state C in which the degradation value between the selection node and the measurement terminal T is maximized is considered. Since the deterioration value of the image does not exceed the deterioration value of the deterioration section candidate, it is excluded from the analysis target.

(2) When a path exceeding the deterioration value of the deterioration section candidate can be extracted, measurement is performed between the measurement terminal T of the deterioration section candidate and one of the measurement terminals T belonging to the extracted path, and an extraction path selection node—measurement terminal A deterioration value between T is calculated. Further, a deterioration value (link deterioration value of the child node) between the selected node in the extraction path and its child node is calculated from the calculation result, and set in the node information of the child node (steps S705 to S709).
In the case of the example in FIG. 23, the measurement is performed either between the measurement terminal T [A] and the measurement terminal T [B] or between the measurement terminal T [A] and the measurement terminal T [B ′]. Note that the method of calculating the link deterioration value of the child node of the selected node is the same as the return deterioration path analysis.

(3) From the above calculation, the deterioration value between the selected node and the measurement terminal T in the extracted path is calculated, and it is determined whether the state is the state B1 or the state B2 shown in FIG. 23 (step S710).
When the determination result corresponds to the state B1, the selected node having the degradation value exceeding the degradation zone candidate and the measurement terminal T [B ′] is set as a new degradation zone candidate, and the child node of the selection node in the new degradation zone candidate Is registered in the subtree constituting node of the selected node (step S711).
Further, the maximum degradation section extraction process in the subtree is performed using the new degradation section candidate and the reference (step S712). As a result, the node between the selected node and the measurement terminal T that truly has the maximum degradation value is found in the subtree.

(4) If it is determined in step S710 that there is no connection between the selected node and the measuring terminal T that truly has the maximum deterioration value other than the deterioration section candidate, the subtree configuration set in the node information of the selected node The sum of the link deterioration value of the node and the link total deterioration value is set as the link total deterioration value of each node information (step S714).
As a result, a node for which a link total degradation value is set means that the extraction of the section where the degradation value between the measurement terminals T from the node is maximum has been completed, and the degradation value (that The total link degradation value of the nodes belonging to the section) can be found.

[2.2.9 Subtree data reconstruction process]
[2.2.9.1 Processing Flow]
FIG. 13 is a diagram illustrating a processing flow of subtree data reconstruction processing by the degraded path detection device 1. In the subtree data reconstruction process, when a degraded path is detected, the subtree is reconstructed so that the section with the second highest degradation value between the root node and the leaf node becomes a constituent element of the subtree.
The section with the second highest degradation value between the root node and the leaf node is connected to the maximum degradation section in other subtrees, and may become a degraded path. This process is performed so that there is no negative path).

  In FIG. 13, the subtree network construction unit 11 reads out node information of nodes belonging to paths from each extraction node to the measurement terminal T associated with each extraction node (step S801). The measurement terminal selection / degradation value analysis unit 14 sets the currently set link degradation value to the link degradation correction value for the node information of the measurement terminal T identified in step S801, and then sets “0” as the link degradation value. Is set (step S802).

  The subtree network construction unit 11 reads the child node pair information set in the node information of the identified parent node of the measurement terminal T, and the current path degradation value of the read child node pair information is obtained in step S802. The link correction value set in the node information is updated to a value obtained by subtraction (step S803).

The subtree network construction unit 11 selects the nodes corresponding to the node information read out in step S801 as processing target layers in order from the first layer, and performs the processing from step S805 onward.
The subtree network construction unit 11 performs the following processing from step S806 on the unselected nodes in this processing flow among the nodes included in the processing target layer.

  The subtree network construction unit 11 selects an unselected node included in the layer to be processed (step S806), and uses the currently set link degradation value for the node information of the selected node as a link degradation correction value. Then, “0” is set as the link degradation value (step S807).

When the selected node is the first hierarchy (step S808: NO), the subtree network construction unit 11 performs the degradation section candidate extraction process for the selected node selected in step S806 (step S810), and performs the maximum degradation section extraction process. This is performed (step S811).
On the other hand, when the selected node selected in step S806 is higher than or equal to the second hierarchy (step S808: YES), the subtree network construction unit 11 determines the node ID from the subtree configuration node set in the node information of this selected node. And the child node pair information in which the read node ID is set is specified. The subtree network construction unit 11 identifies the measurement terminal T associated with each node from the node IDs of the two nodes set in the identified child node pair information, and belongs to the path between the identified measurement terminals T. Read the link degradation value from the node information of the node. The subtree network construction unit 11 sets the total value of the read link deterioration values as the path deterioration value of the specified child node pair information (step S809). Thereafter, the degradation section candidate extraction process is performed for the selected node selected in step S806 (step S810), and the maximum degradation section extraction process is performed (step S811).

[2.2.9.2 Explanation of processing by specific example]
In the subtree data reconstruction process, when a deteriorated path is detected in a subtree in which the selected node belongs to the second hierarchy or higher, the child node of the selected node in the deteriorated path is connected between the measurement terminals T associated with each child node. Reconstruct subtree data for.

FIG. 24 shows a part of the measurement target network that is the target of the subtree data reconstruction process.
In the figure, it is assumed that the node N [1] is a selected node, and the path P1) between the measurement terminal T [A] and the measurement terminal T [I] is detected as a degraded path. A section indicated by a dotted line (for example, node N [4] −measurement terminal T [A]) indicates a section extracted as the maximum degradation section in the processing in each layer. That is, when the selected node is the node N [2], the node N [2] and the measurement terminal T [A] are in the maximum degradation section.

  As shown in FIG. 25A, there are a node N [2], a node N [3], and the like as child nodes of the node N [1] shown in FIG. 2] (the link degradation value of the node N [2]) is “10”, and the degradation value between the node N [1] and the node N [3] (the link degradation value of the node N [3]) is “ 0 ”. FIG. 25B shows node information of the nodes N [1], N [2], and N [3] at this time.

  Further, as shown in FIG. 26A, as child node pairs in the node N [4] shown in FIG. 24, the measurement terminal T [A] -measurement terminal T [B] and the measurement terminal T [C]- The measurement terminal T [D] and the like exist, the path degradation value between the measurement terminal T [A] and the measurement terminal T [B] is “30”, and the degradation value between the node N [4] and the measurement terminal T [A]. (Link degradation value of node N [A]) is “20”, degradation value between node N [4] and measurement terminal T [B] (link degradation value of node N [B]) is “10”, node N [4] The degradation value between the measurement terminals T [C] (link degradation value of the node N [C]) is “15”, and the degradation value between the node N [4] and the measurement terminals T [D] (node N [C] Assume that the link degradation value of D] is “10” and the other path degradation values are “0”. At this time, the node N [4], the node N [A], the node N [B], the node N [C], the node information of the node N [D], and the node N [A] and the node N [B], FIG. 26B shows child node pair information of the node N [C] and the node N [D].

  As shown in FIG. 27 (a), there are measurement terminal T [E], measurement terminal T [F], etc. as child node pairs in node N [5] shown in FIG. Is “30”, the degradation value between node N [5] and measurement terminal T [E] (link degradation value of node N [E]) is “10”, and between node N [5] and measurement terminal T [F] The degradation value (link degradation value of the node N [F]) is “20”, and other path degradation values are “0”. FIG. 27B shows node information of the node N [5], node N [E], and node N [F] and child node pair information of the node N [E] and node N [F] at this time.

  As shown in FIG. 28 (a), there are measurement terminal T [G], measurement terminal T [H], etc. as child node pairs in node N [6] shown in FIG. Is “10”, the degradation value between the node N [6] and the measurement terminal T [G] (link degradation value of the node N [G]) is “0”, and between the node N [6] and the measurement terminal T [H]. Assume that the degradation value (link degradation value of the node N [H]) is “10” and other path degradation values are “0”. FIG. 28B shows node information of the node N [6], node N [G], and node N [H] and child node pair information of the node N [G] and node N [H] at this time.

  Further, as shown in FIG. 29A, the node N [2] shown in FIG. 24 is connected to three nodes N, N [4], N [5], and N [6]. The degradation value between the node N [2] and the node N [4] (link degradation value of the node N [4]) is “20”, and the degradation value between the node N [2] and the node N [5] (node N [ 5] is “0”, and the degradation value between node N [2] and node N [6] (link degradation value of node N [6]) is “5”. At this time, the node information of the node N [2], the node N [4], the node N [5], the node N [6], the node N [4], the node N [5], and the node N [5] The child node pair information of the node N [6] is shown in FIG.

  Further, as shown in FIG. 30, it is assumed that the deterioration value of the maximum deterioration section between the node N [3] and the measurement terminal T [I] is “20”.

That is, the degradation value of the path between the measurement terminal T [A] and the measurement terminal T [I] is the degradation value “20” between the node N [A] and the node N [4], and the node N [4] −node N. Degradation value “20” between [2], degradation value “10” between node N [2] and node N [1], degradation value “0” between node N [1] and node N [3], node This is represented as the sum “70” of the degradation value “20” between N [3] and the measurement terminal T [I], and is a degradation path because it is equal to or greater than the degradation threshold “70”.
The following description will be described with reference to FIGS.

(1) The input information for the subtree data reconstruction process is a child node of the selected node included in the degraded path. In the upper diagram, node N [2] and node N [3] correspond, and these two nodes indicate “two extraction nodes” in the flowchart.
The subsequent processing is performed for two extraction nodes, but since the same processing is performed, only the processing for the extraction node N [2] is described.

(2) A node belonging to the path from the extraction node to the measurement terminal T attached to the extraction node is extracted (step S801).
As shown in FIG. 31, the nodes from the extraction node N [2] to the measurement terminal T associated with the extraction node N [2] are obtained by following the subtree constituting nodes in the node information from the node N [2]. It is node N [4] and node N [A]. That is, for the extraction node N [2], three of “node N [2] / node N [4] / node N [A]” are extracted by this process. Similar processing is performed on the extraction node N [3].

(3) In the node information of the measuring terminal T among the nodes extracted in (2), the link deterioration value is set to the link deterioration correction value, and “0” is set to the link deterioration value. Further, the path degradation value is updated to the value obtained by subtracting the link degradation correction value in the child node pair information to which each measurement terminal T belongs, which is set in the node information of the parent node of the measurement terminal T (steps S802 and S803). .
As shown in FIG. 32, in the node information of the node (node N [A]) of the measurement terminal T, the link deterioration value is set to the link deterioration correction value, and “0” is set to the link deterioration value. Further, the child node pair information to which the node T [A] belongs is specified from the child node pair information set in the node information of the node N [4] that is the parent node of the node N [A]. The link deterioration correction value is subtracted from the currently set path deterioration value, and the subtraction result is set to the path deterioration value.
By performing such a correction process, when this section becomes a part of another path, a deterioration value is added and it is suppressed from being detected as a deterioration path.
Note that this processing is similarly performed for the node N [I].

(4) The subsequent processing is performed from the first layer toward the upper layer. That is, the node N [4], which is a node in the first hierarchy between the node N [2] and the node N [A], and the first hierarchy between the node N [3] and the node N [I] are included. The node becomes a processing target (steps S804 to S806).

(5) As shown in FIG. 33, in the node information of the node (node N [4]) selected in (4), a link deterioration value is set in the link deterioration correction value, and “0” is set in the link deterioration value. Setting is performed (step S807).
For the same reason as the processing at the measurement terminal T, the link deterioration value and the link deterioration correction value are changed.

(6) Since the selected node (node N [4]) is a node in the first layer, the degradation section candidate extraction process and the maximum degradation section extraction process are performed at node N [4]. The maximum degradation section in the subtree having [4] as a root node is changed (steps S808, S810, S811).
In the degradation section candidate extraction, two paths having the largest path degradation value are extracted, and a section in which the degradation value between the root node and the leaf node is maximized is extracted as a candidate.
As a result of the processing so far, as shown in FIG. 34, the link deterioration value of the node N [A] and the path deterioration value between the node N [A] and the node N [B] have been changed. Section candidate extraction will be performed.
In this example, the path degradation value of the path other than the path between the node N [A] and the measurement terminal T [B] and the path between the node N [C] and the measurement terminal T [D] is set to “0”. In the degradation section candidate extraction process to be performed, paths between the node N [A] and the measurement terminal T [B] and between the node N [C] and the measurement terminal T [D] are extracted, and the node N having the largest degradation value is extracted. The section between [4] -measurement terminal T [C] is extracted as a degradation section candidate.
If a path having a path degradation value of “20” exists, a path between the path and the node N [C] -measurement terminal T [D] is extracted, and a degradation section candidate is extracted from the path. It works as follows.
In the subtree having the node N [4] as the root node, the analysis process for determining whether or not the path to be turned back at the node N [4] has deteriorated has already been performed. Deterioration section extraction processing will be performed.
As a result of the above processing, as shown in FIG. 35, the sub-tree constituting node in the node N [4] is changed to the node N [C] and is also changed to the link total deterioration value “15”.
This completes the subtree data reconstruction process in the node N [4] belonging to the first hierarchy.

(7) Next, the subtree data reconstruction process is performed on the node (node N [2]) belonging to the second hierarchy. First, as shown in FIG. 36, the link deterioration value is set to the link deterioration correction value and “0” is set to the link deterioration value as in the first layer node (steps S806 and S807).
Note that the processing after this processing is common to the nodes in the second and higher layers.

(8) Since the node (node N [2]) selected in (7) is a node of the second or higher hierarchy, the child node pair information including the node ID set in the node information subtree constituting node is specified. Then, the total value of the link degradation values of the nodes belonging to the path between the measurement terminals T associated with the two nodes set in the identified child node pair information is set as the path degradation value (steps S808 and S809).
First, since the sub-tree constituting node of the node N [2] is the node N [4], the child node pair information including the node N [4] is extracted as shown in FIG. Each of the tree nodes is traced, and the associated measurement terminal T is specified.
In this example, since the node N [5] is set in the child node pair information to which the node N [4] belongs, the node N [4] and the measurement terminal T associated with the node N [5] are extracted. .
Here, since the information of the node N [5] has not been changed, the measurement terminal T associated with the node N [5] is the node N [F], but the measurement associated with the node N [4]. The terminal T is changed from the node N [A] to the node N [C] by the process (6) as shown in FIG. That is, it means that the path degradation values between the measurement terminals T associated with the node N [4] and the node N [5] are different.
Therefore, the sum of the link degradation values of the nodes belonging to the path between the measurement terminals T is calculated and set as the path degradation value.
In this example, the node information of the nodes in the path between the node N [C] and the node N [F] is as shown in FIG. The link degradation value set in the node information of each node in the path, that is, the node N [C], the node N [4], the node N [2], the node N [5], and the node N [F] The total “15 + 0 + 0 + 0 + 20” is calculated, and the calculation result “35” is set as the path degradation value in the child node pair information of the node N [4] and the node N [5].

(9) After correcting the path degradation value of each child node pair information at the node N [2] by the above processing, the degradation section candidate extraction processing with the node N [2] as the root node, Perform the maximum degradation section extraction process. As a result, when the degradation value of each link of the path detected as degradation is set to “0”, a section in which the degradation value between the node N [2] and the measurement terminal T is maximum is re-extracted (step S810, S811).
In this example, since the input node (two extraction nodes) is a node in the second hierarchy, the subtree data reconstruction process is completed. However, when a higher hierarchy node is input as the extraction node, each node The above processes (7) to (9) are repeated.

[3. Processing example]
Here, a series of operations of the degraded path detection device 1 will be described using a specific example of a measurement target network.

FIG. 39 is a diagram illustrating a measurement target network, where a circled portion indicates the router R and a squared portion indicates the measuring terminal T. The numbers (1-26) assigned to the router R and the measurement terminal T indicate the ID of each node. Also, the lines connecting the routers R and between the routers R and the measuring terminals T represent links.
A link (for example, a link between the node N [1] and the node N [2]) and a node (for example, the node N [4]) indicated by a broken line indicate degradation points, and are swung to each degradation point. The numerical value indicates the deterioration value (for example, delay time) of the corresponding part.

  Nodes included in the first hierarchy are nodes N [2], [3], [4], and [5], and nodes included in the second hierarchy are node N [1]. Measurement terminals T [6] to [10] are connected to the node N [2], measurement terminals T [11] to [16] are connected to the node N [3], and measurement is performed to the node N [4]. Terminals T [17] to [20] are connected, and measurement terminals T [21] to [26] are connected to the node N [5].

  Hereinafter, the degradation path detection method by the degradation path detection device 1 will be described according to the above-described flowchart, taking the measurement target network of FIG. 39 as an example. Here, the deterioration threshold is “70”.

(1) Processing is performed in order from the first layer to the upper layer. First, the first hierarchy is selected (step S10).

(2) First, “node N [2]”, which is a node included in the first hierarchy, is selected (steps S20 and S30). 40 to 44 are diagrams for explaining the processing for the subtree of the selected node N [2].
The process for the subtree whose node is the node N [2] is the most basic process of this algorithm, and shows an example in which no degraded path is detected in the subtree.

(2.1) The subtree data construction process is performed on “node N [2]” that is the selected node (step S40). That is, the processing target here is the range shown in FIG.

(2.1.1) First, node information for the selected node is generated (step S101). Thereby, as shown in FIG. 41A, node information in which the node ID “2” is set is generated.

(2.1.2) Subsequently, the child node of the node N [2], which is the selected node, is extracted from the topology information. In this example, as illustrated in FIG. 40A, the child nodes of the node N [2] are the node N [6] to the node N [10] (step S102). Since the node information of the extracted child node is not generated, node information of each child node is generated (steps S103 and S104). FIG. 41B shows the node information of the generated child node.

(2.1.2) The node information of the generated child node is added to the child node list of the selected node (step S105). FIG. 41C shows the node information of the selected node after adding the child node list.

(2.2) The in-subtree measurement process is performed on “node N [2]” that is the selected node (step S50).

(2.2.1) A process is performed on an unselected node among the nodes N [6] to N [10] which are child nodes of the selected node (step S201).

(2.2.2) Since the selected node belongs to the first hierarchy and there are two or more unselected child nodes, two child nodes are selected at random. Here, it is assumed that the node N [6] and the node N [7] are selected (steps S202, S206, and S208).
As shown in FIG. 42A, child node pair information is generated, and the node ID of the selected child node is set (step S209).

(2.2.3) As shown in FIG. 42B, the generated child node pair information is added to the node information of the selected node (step S210).

(2.2.4) Two measurement terminals T attached to each of the two selected child nodes (node N [6] and node N [7]) are specified (step S211). As shown in FIG. 41 (b), the node information of the node N [6] and the node N [7] has no subtree configuration node information, that is, it means that the node is the measurement terminal T. The measurement terminals T attached to the two child nodes are the node N [6] and the node N [7].
The degradation path detection device 1 issues a measurement instruction to the specified measurement terminal T and receives the measurement result. Further, the measurement degradation value between the measurement terminals T specified from the received information is calculated, and after the correction process, the calculation result is set to the path degradation value of the child node pair information (steps S212 to S214).
The correction process is a process of subtracting the link deterioration correction value in the node information of each node in the measurement path from the measurement deterioration value, but the path connecting node N [6] -node N [7]. Since the link deterioration correction value is not set in the node information in (node N [6] −node N [2] −node N [7]), the correction processing is not performed and the measured deterioration value remains as it is as the path deterioration value. Is stored in the child node pair information.
In this example, since the measured deterioration value is “10”, the path deterioration value is set as it is as shown in FIG.

(2.2.5) Similarly, generation of child node pair information of node N [8] and node N [9], addition of child node pair information to the node information of the selected node, node N [8] and node N [9] The measurement deterioration value is set to the path deterioration value of the child node pair information during the measurement (steps S202, S206, S208 to S211). FIG. 42C shows the generated child node pair information and the node information to which the child node pair information is added.
Since the path degradation value between the node N [8] and the node N [9] is “0”, as shown in FIG. 42 (d), the node information of the node N [8] and the node N [9] “0” is set to the link degradation value (step S216).

(2.2.6) Since only the node N [10] that has not yet been selected is paired with the selected node. Here, node N [9] is selected and paired. Then, like other pairs, generation of child node pair information of the node N [9] and the node N [10], addition of child node pair information to the node information of the selected node, the node N [9] and the node N [10 ], And the measurement degradation value is set to the path degradation value of the child node pair information (steps S202, S206, S207, S209 to S211). FIG. 42E is a diagram illustrating the generated child node pair information and the node information to which the child node pair information is added.

(2.3) Subsequently, the degradation section candidate extraction process is performed on “node N [2]” which is the selected node (step S60).
Since the maximum value of the path degradation value set in the child node pair information of the selected node N [2] is not “0”, two child node pair information having the largest path degradation value is extracted (steps S501 and S503).
Since the child node pair information of the selected node N [2] is as shown in FIGS. 42 (b), (c), and (e), the node N [9] and the node N [10] for which the path degradation value “20” is set. ] And the node pair information of the node N [6] and the node N [7] for which the path degradation value “10” is set are extracted.

(2.3.1) Link deterioration value calculation processing is performed based on the extracted two child node pair information.
All of the node information of the child nodes (node N [6], node N [7], node N [9], node N [10]) set in the extracted child node pair information have link degradation value values. It is not set, and there is no node ID belonging to both child node pair information (steps S401 and S402).

(2.3.2) A node ID is randomly extracted from one child node pair information, a measurement terminal T associated with the node is specified, and this is called a measurement terminal T (A) (steps S405 and S406).
Here, it is assumed that the node N [6] is selected. Further, since the node N [6] is the measurement terminal T, the node N [6] is the measurement terminal T (A). The measurement terminal T attached to each of the nodes (node N [9] and node N [10]) belonging to the other child node pair information is specified, and these are called measurement terminal T (B) and measurement terminal T (C) ( Step S407). Since the nodes N [9] and N [10] are the measurement terminals T, the node N [9] is the measurement terminal T (B) and the node N [10] is the measurement terminal T (C).

(2.3.3) Between measurement terminal T (A) (node N [6]) and measurement terminal T (B) (node N [9]), and measurement terminal T (A) (node N [6]) And measurement terminal T (C) (node N [10]) to obtain a degradation value between measurement terminals.
The inter-measurement terminal degradation value between the measurement terminal T (A) (node N [6]) and the measurement terminal T (B) (node N [9]) is “0”, and the measurement terminal T (A) (node N [6] ] Between the measurement terminals T (C) (node N [10]) is “20”.
Through the processing so far, the degradation values of the four paths shown in FIG.

(2.3.4) Subsequently, the degradation value between the selected node and each measurement terminal T is calculated by solving the equation described in the link degradation value calculation process. Also, using the link degradation value / link degradation correction value of the node between each selected node and the measurement terminal T, the degradation value between the selected node and the child node of the selected node is calculated, and the node information in the node information of each child node is calculated. A calculation result is set to the link degradation value (steps S409 and S410). Here, since the child node of the selected node is the measurement terminal T, the solution of the equation is a degradation value between the selected node and its child node.

  The degradation values of the nodes N [2] and N [6] are “L26”, the degradation values of the node N [2] and the node N [7] are “L27”, and the degradation values of the node N [2] and the node N [9]. If the deterioration value is “L29” and the deterioration values of the nodes N [2] and N [10] are “L210”, the following equations and solutions are obtained.

L26 + L27 = 10, L26 + L29 = 0, L26 + L210 = 20, L29 + L210 = 20
２６ L26 = 0, L27 = 10, L29 = 0, L210 = 20

The result obtained as described above is set to the link deterioration value in the node information of each child node. FIG.43 (b) is a figure which shows the node information of the child node after setting a link degradation value.
Up to this point, the link deterioration value calculation process is completed, and the process returns to the deterioration section candidate extraction process.

(2.3.5) Subsequently, a degradation value between the measurement terminals T associated with each of the nodes belonging to the extracted child node pair is calculated (step S505).

Deterioration value between node N [6] and node N [7]: 10
Degradation value between node N [6] and node N [9]: 0
Deterioration value between node N [6] and node N [10]: 20
Deterioration value between node N [7] and node N [9]: 10 (L27 + L29 = 10)
Deterioration value between node N [7] and node N [10]: 30 (L27 + L210 = 30)
Deterioration value between node N [9] and node N [10]: 20

(2.3.6) Since there is no path exceeding the degradation threshold “70” in the calculated degradation value between measurement terminals, the sum of the link degradation value and the link total degradation value among the child nodes of the selected node. Is extracted and registered in the subtree constituting node of the selected node (steps S506, S512, S513).
Since the link total degradation value means the total degradation value from any node to the measurement terminal T, this value does not exist in the node of the measurement terminal T. That is, the child node (measurement terminal T) having the maximum link degradation value is the extraction target, which is the node N [10]. As illustrated in FIG. 44A, the node N [10] is registered in the subtree configuration node in the node information of the selected node N [2].

(2.4) The aliasing deterioration analysis process is performed on the selected node “node N [2]” (step S70).

(2.4.1) The sum of the link deterioration value and the link total deterioration value of the subtree constituting node registered in the selected node is calculated (step S601).
This means that the deterioration value of the deterioration section candidate that is highly likely to have the maximum deterioration value between the selected node (node N [2]) and the measurement terminal T in the subtree is calculated. Here, as shown in FIG. 44A, the node registered in the sub-tree constituting node of the node N [2] is the node N [10], and as shown in FIG. The sum of the link deterioration value and the link total deterioration value of N [10] is “20”.

(2.4.2) From the child node pair information of the selected node, a child node pair that does not belong to the child node for which the link degradation value is set and whose sum of the path degradation value and the calculation result exceeds the degradation threshold is selected. Extract (step S602).
At this time, the node information of the nodes N [6] to N [10] that are child nodes of the selected node (node N [2]) is the nodes N [6], [7], [9], [10]. ] Is set as shown in FIG. 43 (b) and node N [8] is set as shown in FIG. 42 (d), and link degradation values are already set in all child node information. Further, the child node pair information of the selected node is as shown in FIGS.
That is, in the node information of the nodes (nodes N [6] to N [10]) set in the child node pair information, there is no node for which no link deterioration value is set, and the path deterioration value and the calculation result There is no child node pair whose sum exceeds the deterioration threshold (step S603: NO).
Thus, the aliasing deterioration analysis is completed.

(2.5) Subsequently, the maximum degradation section extraction process is performed on the selected node “node N [2]” (step S80).
Similar to the loopback deterioration analysis, the sum of the link deterioration value and the link total deterioration value of the subtree constituting node registered in the selected node is calculated (step S701). In the previous loopback deterioration analysis, there is no change in the node information and the like, so the sum of the link deterioration value and the link total deterioration value is “20”, which is set as the reference deterioration value. In addition, there is no child node of the selected node for which no link degradation value is set. Therefore, as shown in FIG. 44B, the reference deterioration value “20” is set as the link total deterioration value of the selected node (steps S702, S703, and S714).

  Thus, the analysis in the subtree having the selected node (node N [2]) as the root node is completed. FIG. 40B shows the subtree after the analysis is completed. In the figure, child nodes and links belonging to the path having the maximum degradation value, and the degradation value are shown. In this way, the child node (node N [10]) of the selected node belonging to the path having the maximum deterioration value between the selected node and the measurement terminal T is determined.

(3) Next, “node N [3]”, which is a node included in the first hierarchy, is selected (step S30). FIGS. 45 to 49 are diagrams for explaining processing relating to the selected node N [3].
An example in which the processing of the subtree with the selected node of node N [3] includes a section in which the degradation value between the selected node and the measurement terminal T is maximum, in addition to the two paths that are candidates for the degradation section candidate extraction process. Is shown.

(3.1) The subtree data construction process is performed on “node N [3]” that is the selected node (step S40). That is, the processing target here is the range shown in FIG.
In the same manner as the subtree data construction process performed at node N [2], node information for the selected node and node information for the child nodes (node N [11] to node N [16]) of the selected node are generated and selected. Add the node information of the generated child node to the child node list of the node. FIG. 46A shows the node information of the selected node generated and the node information of the child node added to each node information.

(3.2) The in-subtree measurement process is performed on “node N [3]” that is the selected node (step S50).
Similar to the sub-tree measurement process in the node N [2], a child node pair is generated, and child node pair information is added to the selected node. In addition, measurement is performed between the measurement terminals T attached to each node in each pair, and a path degradation value is calculated. Here, node N [11] −node N [12], node N [13] −node N [14], and node N [15] −node N [16] are each paired. The path degradation value in each pair is “30 (= 15 + 15)” between the node N [11] and the node N [12], and “25 (= 10 + 15) ”and“ 20 (= 0 + 20) ”between the node N [15] and the node N [16].
From the above, child node pair information is generated as shown in FIG. 46B, and the child node pair list of the node information of the selected node is added.
Since there is no path degradation value that exceeds the degradation threshold, this process ends here.

(3.3) Subsequently, the deterioration section candidate extraction process is performed on “node N [3]” which is the selected node (step S60).
Since the maximum value of the path degradation value set in the child node pair information of the selected node N [3] is not “0”, the two child node pair information having the largest path degradation value is extracted. Here, since the child node pair information of the selected node N [3] is as shown in FIG. 46B, the child node pair of the node N [11] and the node N [12] for which the path degradation value “30” is set. The information and the child node pair information of the node N [13] and the node N [14] for which the path degradation value “25” is set are extracted.

(3.3.1) A link deterioration value calculation process is performed based on the extracted two child node pair information.
Similarly to the link degradation value calculation process performed when the selected node is the node N [2], between the node N [3] and the node N [11], between the node N [3] and the node N [12], Each deterioration value between the node N [3] and the node N [13] and between the node N [3] and the node N [14] is calculated, and set to the link deterioration value of each child node information. The calculation results are as follows.

Deterioration value between node N [3] and node N [11]: 15
Deterioration value between node N [3] and node N [12]: 15
Deterioration value between node N [3] and node N [13]: 10
Deterioration value between node N [3] and node N [14]: 15

  Therefore, the node information from the node N [11] to the node N [14] is as shown in FIG.

  Next, a deterioration value between the measurement terminals T associated with each node belonging to the extracted child node pair is calculated. The calculation results are as follows.

Deterioration value between node N [11] and node N [12]: 30
Deterioration value between node N [11] and node N [13]: 25
Deterioration value between node N [11] and node N [14]: 30
Deterioration value between node N [12] and node N [13]: 25
Deterioration value between node N [12] and node N [14]: 30
Deterioration value between node N [13] and node N [14]: 25

Since there is no path exceeding the degradation threshold “70” among the degradation values between the measurement terminals obtained as described above, the sum of the link degradation value and the link total degradation value is the largest among the child nodes of the selected node. A node that is a child node is registered in the subtree constituting node of the selected node.
Here, since the deterioration value of the three sections is the maximum, it is assumed that the node N [11] is selected at random.
As described above, as illustrated in FIG. 48A, the node N [11] is registered in the subtree configuration node in the node information of the selected node N [3].

(3.4) The aliasing deterioration analysis process is performed on the selected node “node N [3]” (step S70).
As shown in FIG. 48A, the node registered in the sub-tree constituting node of the selected node is the node N [11], and as shown in FIG. 47A, the node information of the node N [11] The sum of the link deterioration value and the link total deterioration value registered in “15” is “15”. In addition, among the node information of the child nodes registered in the selected node, the node information of the nodes N [15] and N [16] remains the setting contents shown in FIG. The value is not set.
In the selected node, the node N [15] and the node N [16] are a pair, and the child node pair information is as shown in FIG.
Since the path degradation value set in the child node pair information is “20”, and the sum of the link degradation value and the link total degradation value of the subtree configuration node (node N [11]) is “15”, The sum of the two deterioration values is “35 (= 20 + 15)” and does not exceed the deterioration threshold “70”.
That is, it means that the communication path that is turned back at the selected node cannot be a degraded path in the subtree having the selected node (node N [3]) as the root node.
Thus, the aliasing deterioration analysis is completed.

(3.5) Subsequently, the maximum degradation section extraction process is performed on the selected node “node N [3]” (step S80).

(3.5.1) A comparison process based on the subtree configuration node (node N [11]) is performed.
The sum of the link deterioration value “15” and the link total deterioration value “NULL” of the subtree configuration node (node N [11]) shown in FIG. 47A is the reference deterioration value, and the value is “15”. . In addition, in the child node pair information of the selected node shown in FIG. 46 (b), nodes (node N [15], node N [16]) for which no link degradation value is set as shown in FIG. 46 (a). There exists child node pair information to which the node belongs, and the path deterioration value is “20” from the child node pair information shown in FIG. 46B, which exceeds the reference deterioration value (step S703: YES).
This is because the path degradation value is small, but the degradation value between the measurement node T associated with the selected node and each child node may exceed the degradation value between the selection node and the measurement terminal T extracted by the degradation section candidate extraction process. It means that there is.

Since the path degradation value between the node N [15] and the node N [16] is “20”, a case like the state (a) or the state (b) shown in FIG. 49 can be considered.
In the state (a), since the deterioration value between the selected node and the child node does not exceed the deterioration value “15” of the deterioration section candidate, the child node having the maximum deterioration value between the selected node and the child node is the node N [11]. On the other hand, in the state (b), the child node that exceeds the deterioration value “15” of the deterioration section candidate and has the maximum deterioration value between the selected node and the child node is the node N [15].
Therefore, in step S704 and subsequent steps, it is analyzed which of these states a path for which a path deterioration value exceeding the reference deterioration value is set.

  Therefore, a node belonging to the extracted child node pair information (child node pair information to which the node N [15] and the node N [16] belong) is selected at random. Here, node N [15] is selected. Further, the measurement terminal T associated with the selected node is specified. Here, since the node N [15] is the measurement terminal T, the node N [15] is the measurement terminal T to be identified (step S705).

The measurement terminal T associated with the subtree constituting node registered in the selected node is specified (step S706).
Since the sub-tree constituting node is the node N [11] and the node N [11] is the measurement terminal T, the measurement terminal T to be specified is the node N [11].

Measurement is performed between the specified measurement terminals T to calculate a measurement deterioration value, and a deterioration value (comparison deterioration value) between the selected node and each measurement terminal T is calculated (steps S707 and S708).
The degradation value when measured between the node N [11] and the node N [15] is “15”. Here, the degradation value between the node N [3] and the node N [11] is “L311”, the degradation value between the node N [3] and the node N [15] is “L315”, and the node N [3] and the node If the deterioration value between N [16] is “L316”, the following holds.

L311 + L315 = 15, L315 + L316 = 20, L311 = 15
Ｌ L315 = 0, L316 = 20

  In the processing target subtree here, the selected node is a node in the first hierarchy, and the child node of the selected node is the node of the measuring terminal T. Therefore, the above calculation result is the deterioration value between the selected node and the child node. Become. Therefore, as shown in FIG. 47B, the calculation result is set to the link deterioration value of each child node (node N [15] and node N [16]) (step S709).

The reference deterioration value is “15”, and the comparison deterioration values are the deterioration value “0” between the node N [3] and the node N [15] and the deterioration value between the node N [3] and the node N [16]. Since it is “20”, there is a comparative deterioration value exceeding the reference deterioration value (step S710: YES).
As shown in FIG. 48B, a node N [16] that is a child node of a selected node belonging to a path exceeding the reference deterioration value (path between the node N [3] and the node N [16]) is selected as the selected node. Are registered in the subtree constituting node (step S711).
Since the change of the subtree constituent node in the selected node has occurred, the maximum degradation section extraction process is performed again using the new subtree constituent node (step S712).

(3.5.2) In the maximum degradation section extraction process, a comparison process based on the subtree configuration node (node N [16]) is performed.
The sum of the link deterioration value “20” and the link total deterioration value “NULL” of the sub-tree constituting node of the node N [16] illustrated in FIG. 47B is the reference deterioration value, and the value is “20”. Further, as a result of the previous processing, there is no node for which no link degradation value is set as a child node of the selected node (node N [3]). Therefore, as shown in FIG. 48C, the reference deterioration value “20” is set as the link total deterioration value of the selected node.

  Thus, the analysis in the subtree having the selected node (node N [3]) as the root node is completed. FIG. 45B shows the subtree after the analysis is completed. In the figure, child nodes and links belonging to the path having the maximum degradation value, and the degradation value are shown. In this way, the child node (node N [16]) of the selected node belonging to the path having the maximum deterioration value between the selected node and the measurement terminal T is determined.

(4) Next, “node N [4]”, which is a node included in the first hierarchy, is selected (step S30). 50 to 53 are diagrams for explaining the processing related to the selected node N [4].
The processing of the subtree whose node is the node N [4] shows an example in which a degraded path is detected by measurement within the subtree.

(4.1) The subtree data construction process is performed on “node N [4]” that is the selected node (step S40). That is, the processing target here is the range shown in FIG.
In the same manner as the subtree data construction processing performed at node N [2], node information for the selected node and node information for child nodes (node N [17] to node N [20]) of the selected node are generated and selected. Add the node information of the generated child node to the child node list of the node. FIG. 51A shows the node information of the selected node generated and the node information of the child node added to each node information.

(4.2) The in-subtree measurement process is performed on “node N [4]” that is the selected node (step S50).
Similar to the sub-tree measurement process in the node N [2], a child node pair is generated, and child node pair information is added to the selected node. In addition, measurement is performed between the measurement terminals T attached to each node in each pair, and a path degradation value is calculated. Here, node N [17] -node N [18] and node N [19] -node N [20] are paired, respectively. The path degradation value in each pair is “70 (= 30 + 20 + 20)” between the node N [17] and the node N [18], and “25” between the node N [19] and the node N [20]. (= 20 + 5) ".
From the above, child node pair information is generated as shown in FIG. 51B, and the child node pair list of the node information of the selected node is added.
Since the degradation threshold is “70” and the path degradation value between the node N [17] and the node N [18] is “70”, this path is detected as a degraded path (steps S217 to S219).

(4.2.1) The measurement degradation path process is performed using the child node pair information extracted as the degradation path (step S220).
Since there is only one child node pair information extracted as a degraded path in the sub-tree measurement, child node pair information other than the extracted child node pair information is randomly selected from the child node pair information of the selected node. Here, the child node pair information of the node N [19] and the node N [20] is selected (steps S302 and S304).
That is, there are two pieces of child node pair information for the next link degradation value calculation processing target as shown in FIG.

(4.2.1.1) A link deterioration value calculation process is performed based on the extracted two child node pair information.
Similarly to the link deterioration value calculation process performed when the selected node is the node N [2], between the node N [4] and the node N [17], between the node N [4] and the node N [18], The respective degradation values between the node N [4] and the node N [19] and between the node N [4] and the node N [20] are calculated and set to the link degradation value of each child node information. The calculation results are as follows.

Deterioration value between node N [4] and node N [17]: 40
Deterioration value between node N [4] and node N [18]: 30
Deterioration value between node N [4] and node N [19]: 10
Deterioration value between node N [4] and node N [20]: 15

  Therefore, the node information from the node N [17] to the node N [20] is as shown in FIG.

  Since the selected node (node N [4]) is a node in the first layer, as shown in FIG. 52 (b), “0” is set to the path degradation value of the child node pair information extracted as the degradation path, For the node information of each node (node N [17] and node N [18]) belonging to this child node pair information, the link deterioration value is set as the link deterioration correction value, and “0” is set as the link deterioration value ( Steps S307 and S308).

(4.3) The degradation section candidate extraction process is performed on “node N [4]” that is the selected node (step S60).
Since the maximum value of the path degradation value set in the child node pair information of the selected node N [4] is not “0”, the two child node pair information having the largest path degradation value is extracted. Here, since there is only two child node pair information of the selected node N [4], the child node pair information of the node N [17] and the node N [18] for which the path degradation value “0” is set (FIG. 52 ( b)) and child node pair information (FIG. 51B) of the node N [19] and the node N [20] for which the path degradation value “25” is set are extracted.

(4.3.1) Based on the extracted two child node pair information, a link deterioration value calculation process is performed.
As shown in FIG. 52B, the node information of the nodes belonging to the extracted two child node pair information is the node N [17] and the node N [20] for the node N [17] and the node N [18]. ] Is as shown in FIG. 52 (a). Since the link deterioration values of all the nodes have already been calculated, the link deterioration value calculation process ends without performing a new process (step S401: YES).

  Next, a deterioration value between the measurement terminals T associated with each node belonging to the extracted child node pair is calculated. The calculation results are as follows.

Degradation value between node N [17] and node N [18]: 0
Deterioration value between node N [17] and node N [19]: 10
Deterioration value between node N [17] and node N [20]: 15
Deterioration value between node N [18] and node N [19]: 10
Deterioration value between node N [18] and node N [20]: 15
Deterioration value between node N [19] and node N [20]: 25

  Since there is no path exceeding the degradation threshold “70” among the degradation values between the measurement terminals obtained as described above, link degradation among the child nodes of the selected node as shown in FIG. Node N [20], which is the child node having the maximum sum of the value and the link total degradation value, is registered in the subtree constituting node of the selected node.

(4.4) The aliasing deterioration analysis process is performed on the selected node “node N [4]” (step S70).
As shown in FIG. 53 (a), the node registered in the sub-tree constituting node of the selected node is the node N [20], and as shown in FIG. 52 (a), the link degradation of the node N [20] The sum of the value and the link total deterioration value is “15”. As shown in FIGS. 52A and 52B, the node information of the child nodes N [17] to [20] registered in the selected node (node N [4]) includes link degradation. There are no nodes for which no value is set.
Therefore, the aliasing deterioration analysis ends here.

(4.5) The maximum degradation section extraction process is performed on the selected node “node N [4]” (step S80).
The sum of the link deterioration value “15” and the link total deterioration value “NULL” of the sub-tree constituting node (node N [20]) of the node N [20] shown in FIG. Is “15”. Further, since there is no node for which no link deterioration value is set among the child nodes registered in the selected node (node N [4]), as shown in FIG. “15” is set as the total link degradation value of the selected node.

  Thus, the analysis in the subtree having the selected node (node N [4]) as the root node is completed. FIG. 50B shows the subtree after the analysis is completed. In the figure, child nodes and links belonging to the path having the maximum degradation value, and the degradation value are shown. In this way, the child node (node N [20]) of the selected node belonging to the path having the maximum deterioration value between the selected node and the measurement terminal T is determined.

(5) Next, “node N [5]”, which is a node included in the first hierarchy, is selected (step S30). 54 to 59 are diagrams for explaining the processing related to the selected node N [5].
In the processing of the subtree with the selected node of node N [5], no deteriorated path is detected within the range in which the deteriorated section candidate extraction process is performed, but the deteriorated section candidate is connected between the selected node of another path and the measurement terminal T. An example in which a path connecting sections is a degraded path is shown.

(5.1) The subtree data construction process is performed on “node N [5]” which is the selected node (step S40). That is, the processing target here is the range shown in FIG.
In the same manner as the subtree data construction processing performed at node N [2], node information for the selected node and node information for child nodes (node N [21] to node N [26]) of the selected node are generated and selected. Add the node information of the generated child node to the child node list of the node. FIG. 55A shows the node information of the selected node generated and the node information of the child node added to each node information.

(5.2) The in-subtree measurement process is performed on “node N [5]” that is the selected node (step S50).
Similar to the sub-tree measurement process in the node N [2], a child node pair is generated, and the child node pair information is added to the node pair list of the node information of the selected node. In addition, measurement is performed between the measurement terminals T attached to each node in each pair, and a path degradation value is calculated. Here, node N [21] −node N [22], node N [23] −node N [24], and node N [25] −node N [26] are paired. The path degradation value in each pair is “50 (= 30 + 20)” between the node N [21] and the node N [22], and “60 (= 30 +) between the node N [23] and the node N [24]. 30) ”and“ 40 (= 0 + 40) ”between the node N [25] and the node N [26].
From the above, child node pair information is generated as shown in FIG. 55 (b), and the child node pair list of the node information of the selected node is added.
Since there is no path degradation value that exceeds the degradation threshold, this process ends here.

(5.3) The degradation section candidate extraction process is performed on the selected node “node N [5]” (step S60).
Since the maximum value of the path degradation value set in the child node pair information of the selected node N [5] is not “0”, the two child node pair information having the largest path degradation value is extracted. Here, since the child node pair information of the selected node N [5] is as shown in FIG. 55B, the child of the node N [21] and the node N [22] for which the path degradation value “50” is set. The node pair information and the node pair information of the node N [23] and the node N [24] for which the path degradation value “60” is set are extracted.

(5.3.1) Link deterioration value calculation processing is performed based on the extracted two child node pair information.
Similarly to the link deterioration value calculation process performed when the selected node is the node N [2], between the node N [5] and the node N [21], between the node N [5] and the node N [22], Each deterioration value between the node N [5] and the node N [23] and between the node N [5] and the node N [24] is calculated, and set to the link deterioration value of each child node information. The calculation results are as follows.

Deterioration value between node N [5] and node N [21]: 30
Deterioration value between node N [5] and node N [22]: 20
Deterioration value between node N [5] and node N [23]: 30
Deterioration value between node N [5] and node N [24]: 30

  Therefore, the node information from the node N [21] to the node N [24] is as shown in FIG.

  Next, a deterioration value between the measurement terminals T associated with each node belonging to the extracted child node pair is calculated. The calculation results are as follows.

Deterioration value between node N [21] and node N [22]: 50
Deterioration value between node N [21] and node N [23]: 60
Deterioration value between node N [21] and node N [24]: 60
Deterioration value between node N [22] and node N [23]: 50
Deterioration value between node N [22] and node N [24]: 50
Deterioration value between node N [23] and node N [24]: 60

Since there is no path exceeding the degradation threshold “70” among the degradation values between the measurement terminals obtained as described above, the sum of the link degradation value and the link total degradation value is the largest among the child nodes of the selected node. A node that is a child node is registered in the subtree constituting node of the selected node.
Here, since the deterioration value of the three sections is the maximum, it is assumed that the node N [21] is selected at random.
As described above, the node N [21] is registered in the subtree configuration node in the node information of the selected node N [5].

(5.4) The aliasing deterioration analysis process is performed on “node N [5]” which is the selected node (step S70).
The node registered in the sub-tree constituting node of the selected node is the node N [21]. As shown in FIG. 56A, the link deterioration value and the link registered in the node information of the node N [21]. The sum of the total deterioration values is “30”. Also, as shown in FIG. 56 (a), among the node information of the child nodes registered in the selected node, the link degradation value has a value for the node information of the node N [25] and the node N [26]. Not set.
In the selected node, the node N [25] and the node N [26] are a pair, and the child node pair information is as shown in FIG.
Since the path degradation value set in this child node pair information is “40”, and the sum of the link degradation value and the link total degradation value of the subtree configuration node (node N [21]) is “30”, The sum of the two degradation values is “70 (= 30 + 40)”, which is equal to or greater than the degradation threshold “70” (step S603: YES).
That is, there is a possibility that a degradation path exists between the measurement terminal T associated with the subtree constituting node (node N [21]) and the measurement terminal T associated with any of the extracted child node pairs. Yes.

Since the path degradation value between the node N [25] and the node N [26] is “40”, a case like the state (a) or the state (b) shown in FIG. 57 is conceivable.
In the state (a), the sum of the deterioration value between the selected node and the node N [25] or the selected node and the node N [26], and the link deterioration value and the link total deterioration value of the node N [21] is “70. Is less than. In the state (b), the sum of the link degradation value and the link total degradation value of either the selected node and the node N [25] or the selected node and the node N [26] and the node N [21] is “ 70 "or more.
Therefore, in step S604 and subsequent steps, it is analyzed whether or not a degraded path is obtained by connecting a degraded section candidate and a selected node-measurement terminal T section in another path.

  A node belonging to the extracted child node pair information (child node pair information to which the node N [25] and the node N [26] belong) is selected at random. Here, the node N [25] is selected. Further, the measurement terminal T associated with the selected node is specified. Here, since the node N [25] is the measurement terminal T, the node N [25] is the measurement terminal T to be identified (step S605).

The measurement terminal T associated with the subtree constituting node registered in the selected node is specified (step S606).
Since the sub-tree constituting node is the node N [21] and the node N [21] is the measurement terminal T, the measurement terminal T to be specified is the node N [21].

Measurement is performed between the specified measurement terminals T, and a measurement deterioration value is calculated, and a deterioration value between the selected node and each measurement terminal T is calculated (steps S607 and S608).
The degradation value when measured between the node N [21] and the node N [25] is “30”. Here, the degradation value between the node N [5] and the node N [21] is “L521”, the degradation value between the node N [5] and the node N [25] is “L525”, and the node N [5] and the node When the deterioration value between N [26] is set to “L526”, the following holds.

L521 + L525 = 30, L525 + L526 = 40, L521 = 30
５ L525 = 0, L526 = 40

  Since the node N [25] and the node N [26] are measurement terminal T nodes, the above calculation result is a degradation value between the selected node and the child node. Therefore, as shown in FIG. 56 (b), the calculation result is set to the link degradation value of the node information of each child node (node N [25] and node N [26]) (step S609).

  Deterioration values between the measurement terminals T (node N [21], node N [25], node N [26]) are as follows (step S610).

Deterioration value between node N [21] and node N [25]: 30
Deterioration value between node N [21] and node N [26]: 70
Deterioration value between node N [25] and node N [26]: 40

  At this time, since there is a path with a degradation threshold value “70” or more, it is detected as a degradation path (steps S611 and S612). Child nodes of the selected node belonging to the degraded path are the node N [21] and the node N [26] (step S613). Further, since the selected node belongs to the first hierarchy, as shown in FIG. 56C, the link deterioration is added to the link deterioration correction value of the extracted child nodes (node N [21] and node N [26]). A value is set, and “0” is set as the link degradation value (steps S614 and S618).

Further, the link degradation correction value of the child node is subtracted from the path degradation value of each child node pair information to which the extracted child node (node N [21] and node N [26]) belongs, and the subtraction result is obtained for each path degradation. A value is set (step S619).
The child node pair information to which the node N [21] and the node N [26] belong is as shown in FIG. Therefore, as shown in FIG. 56 (d), the link degradation correction value of the node to which it belongs is subtracted from the path degradation value of each child node pair information.

With the above processing, the deterioration value between the measurement terminal T and the selected node associated with the subtree constituent node extracted by the deterioration section candidate extraction processing is corrected to “0”. That is, the sub-tree constituting node registered in the selected node at this time has the maximum deterioration value between the selected node and the measurement terminal T in the sub-tree having the selected node (node N [5]) as the root node. It may not be a child node in the section.
Therefore, the degraded section candidate extraction process is performed again and an analysis is performed as to whether or not the extracted sections constitute a degraded path (steps S620 and S621).

  By the processing so far, each node information and child node pair information is as shown in FIG.

(5.4.1) The degradation section candidate extraction process is performed on the selected node “node N [5]” (step S620).
As shown in FIG. 58, since the maximum value of the path degradation value set in the child node pair information of the selected node N [5] is not “0”, similarly, the two child node pairs having the largest path degradation value. Extract information. Here, the child node pair information of the nodes N [21] and N [22] for which the path degradation value “20” is set, and the nodes N [23] and N for which the path degradation value “60” is set. [24] Child node pair information is extracted.

(5.4.1.1) Based on the extracted two child node pair information, link deterioration value calculation processing is performed.
Since link degradation values have already been set in all the nodes (node N [21] to node N [24]) belonging to the extracted child node pair information, this processing ends.

  From the link deterioration value of the child node belonging to the extracted child node pair and the link total deterioration value, the deterioration value between the measurement terminals T associated with each child node is as follows.

Deterioration value between node N [21] and node N [22]: 20
Deterioration value between node N [21] and node N [23]: 30
Deterioration value between node N [21] and node N [24]: 30
Deterioration value between node N [22] and node N [23]: 50
Deterioration value between node N [22] and node N [24]: 50
Deterioration value between node N [23] and node N [24]: 60

Since there is no path exceeding the degradation threshold “70” among the degradation values between the measurement terminals obtained as described above, the sum of the link degradation value and the link total degradation value is the largest among the child nodes of the selected node. A node that is a child node is registered in the subtree constituting node of the selected node.
Here, since the deterioration value of the two sections is the maximum, it is assumed that the node N [23] is selected at random.
As described above, as shown in FIG. 59A, the node N [23] is registered in the subtree configuration node in the node information of the selected node N [5].

(5.4.2) The aliasing analysis process is performed for “node N [5]” that is the selected node (step S621).
The node registered in the sub-tree constituting node of the selected node is the node N [23]. As shown in FIG. 58, the link deterioration value and the link total deterioration value set in the node information of the node N [23] Is the sum of 30. Further, the node information of the child node set as the child node list in the node information of the selected node is as shown in FIG. 58, and there is no node information for which no link deterioration value is set.
Therefore, there are no more degraded paths in the subtree having the node N [5] as the root node.

(5.5) The maximum degradation section extraction process is performed on the selected node “node N [5]” (step S80).
As shown in FIG. 58, the sum of the link deterioration value “30” and the link total deterioration value “NULL” of the subtree constituting node (node N [23]) is the reference deterioration value, and the value is “30”. .
Among the child nodes registered in the selected node (node N [5]), there is no node for which the link deterioration value is not set. Therefore, as shown in FIG. Is set to the link total deterioration value of the node information of the selected node.

  Thus, the analysis in the subtree having the selected node (node N [5]) as the root node is completed. FIG. 54B shows the subtree after the analysis is completed. In the figure, child nodes and links belonging to the path having the maximum degradation value, and the degradation value are shown. In this way, the child node (node N [23]) of the selected node belonging to the path having the maximum deterioration value between the selected node and the measurement terminal T is determined.

  As described above, the process from the node N [2] to the node N [5] belonging to the first hierarchy is completed, and the process proceeds to the process for the second hierarchy node.

(6) “Node N [1]”, which is a node included in the second hierarchy, is selected (step S30). FIGS. 60 to 69 are diagrams for explaining the processing related to the selected node N [1].
A subtree to be processed when a node in the second hierarchy or higher is a selection node is a subtree connecting the selection node and a child node of the selection node, and each child node (node N [2] belonging to the first hierarchy). Node N [5]) and the measurement terminal T have a maximum degradation value (interval up to the measurement terminal T obtained by tracing the subtree constituting node of each child node).
In this example, the partial tree shown in FIG. 60 is a range to be processed.

In FIG. 60, the numerical value described in the link between the node of the first layer and the measurement terminal T is a known deterioration value that has been calculated in the process in each subtree of the first layer.
The numerical value between the node N [1] and the node N [2] is an unknown degradation value included in the link between the node N [1] and the node N [2].
Since the numerical value in parentheses between the node N [1] and the node N [4] has a deterioration value “20” in the node N [4], the calculation is performed between the node N [1] and the node N [4]. It is an unknown deterioration value that appears as a deterioration value at present.

  In the processing of the subtree with the selected node N [1], the degradation path is not detected in the measurement within the subtree, but the degradation path is detected in the degradation section candidate extraction process, and the subtree data reconstruction process is performed accordingly. Is shown.

(6.1) The subtree data construction process is performed on “node N [1]” which is the selected node (step S40).
(6.1.1) First, node information for the selected node is generated (step S101). Thereby, as illustrated in FIG. 61A, node information in which the node ID “1” is set is generated.
(6.1.2) Subsequently, child nodes of the selected node are extracted from the topology information. In this example, the child nodes of the node N [2] are the node N [2] to the node N [5] (step S102).
Since the node information of the extracted child node has already been generated, the child node information of the node N [2] to the node N [5] is converted into the node of the generated node N [1] as shown in FIG. It adds to the child node list of information (step S103, S105). The node information of the node N [2] is shown in FIG. 44B, the node information of the node N [3] is shown in FIG. 48C, the node information of the node N [4] is shown in FIG. The node information [5] is the decoy shown in FIG.

(6.2) The sub-tree measurement process is performed on “node N [1]” which is the selected node (step S50).

(6.2.1) Processing is performed on an unselected node among the nodes N [2] to N [5], which are child nodes of the selected node (step S201).

(6.2.2) Since the selected node belongs to the second hierarchy and there are two or more unselected child nodes, two child nodes having the largest link total degradation value are selected from among them ( Steps S202, S203, S205).
At this time, the unselected child nodes are all child nodes, and the node information of each child node is as shown in FIG. 44B for the node N [2] and FIG. 48C for the node N [3]. FIG. 53 (b) shows the node N [4] and FIG. 59 (b) shows the node N [5]. Secondly, a node N [3] having the largest link total degradation value is paired. The second node with the largest link total degradation value is the node N [2] and the node N [3]. Here, it is assumed that the node N [3] is selected at random.

(6.2.3) As shown in FIG. 62A, child node pair information is generated, and the node ID of the selected child node pair is set. Further, child node pair information is added to the selected node (steps S209 and S210).

Two measurement terminals T associated with the two selected child nodes (node N [3] and node N [5]) are specified (step S211). Since the sub-tree constituting node registered in the node information of the node N [3] is the node N [16], and the node N [16] is the measurement terminal T node, the measurement terminal associated with the node N [3] T becomes node N [16]. Similarly, the measurement terminal T attached to the node N [5] is the node N [23].
Measurement is performed between the two specified measurement terminals T (node N [16] and node N [23]), and path degradation values are calculated (steps S212 to S214).
In this example, since the path degradation value is “50”, the calculation result is set to the path degradation value of the child node pair information as shown in FIG.

Similarly, node N [2] and node N [4] are used as child node pairs, child node pair information is generated, and child node pair information is added to the selected node. Further, measurement is performed between the measurement terminals T (node N [10] and node N [20]) associated with each child node (node N [2] and node N [4]), and the calculated path degradation value is calculated. “65” is set in the child node pair information (steps S202, S203, S205, and S209 to S214).
With the above processing, each piece of information becomes as shown in FIG.
Since the path degradation values are both less than the degradation threshold “70”, the sub-tree measurement process is terminated.

(6.3) The degradation section candidate extraction process is performed on “node N [1]” which is the selected node (step S60).
Since the maximum value of the path degradation value set in the child node pair information of the selected node N [1] is not “0”, two child node pair information having the largest path degradation value is extracted (steps S501 and S503). In this example, as shown in FIGS. 62B and 62C, since the node N [1] has only two child node pair information, the two are extracted.

(6.3.1) Based on the extracted two child node pair information, link deterioration value calculation processing is performed.
In the same manner as the link deterioration value calculation process in the node N [2], the measurement terminals T associated with the node N [1] and the child nodes of the node N [1] (from the node N [2] to the node N [5]), respectively. The degradation value is calculated (steps S401, S402, S405 to S409).
The deterioration values between the node N [1] and each measurement terminal T are as follows.

Deterioration value between node N [1] and node N [10] (measurement terminal T associated with node N [2]): 40
Deterioration value between node N [1] and node N [16] (measurement terminal T associated with node N [3]): 20
Degradation value between node N [1] and node N [20] (measurement terminal T associated with node N [3]): 25
Degradation value between node N [1] and node N [23] (measurement terminal T associated with node N [4]): 30

A degradation value between each child node in the extracted two child node pair information and its parent node (selected node) is calculated and set to the link degradation value of each child node (step S410).
Here, the link total degradation value (total degradation value from each child node to the associated measurement terminal T) in the child node (node N [2] to node N [5]) of the node N [1] is known, Each is as follows.

Deterioration value between measurement terminals T (node N [10]) associated with node N [2] from node N [2]: 20
Deterioration value between measurement terminals T (node N [16]) associated with node N [3] from node N [3]: 20
Deterioration value between measurement terminals T (node N [20]) associated with node N [4] from node N [4]: 15
Deterioration value between measurement terminals T (node N [23]) associated with node N [5] from node N [5]: 30

From the above, the deterioration value between the node N [1] and each child node (from the node N [2] to the node N [5]) is as follows.
Deterioration value between node N [1] and node N [2]: 20 (= (deterioration value between node N [1] and node N [10]) − (between node N [2] and node N [10] Degradation value) = 40-20)
Degradation value between node N [1] and node N [3]: 0 (= (degradation value between node N [1] and node N [16]) − (between node N [3] and node N [16] Degradation value) = 20-20)
Deterioration value between node N [1] and node N [4]: 10 (= (deterioration value between node N [1] and node N [20]) − (between node N [4] and node N [20] Degradation value) = 25-15)
Degradation value between node N [1] and node N [5]: 0 (= (degradation value between node N [1] and node N [23]) − (between node N [5] and node N [23] Degradation value) = 30-30)

Therefore, the link deterioration values of the node information of the nodes N [2] to N [5] are as shown in FIG.
Up to this point, the link deterioration value calculation process is completed, and the process returns to the deterioration section candidate extraction process.

  Subsequently, a deterioration value between the measurement terminals T associated with each node belonging to the extracted child node pair is calculated (step S505).

Deterioration value between node N [10] and node N [16]: 60
Deterioration value between node N [10] and node N [20]: 65
Deterioration value between node N [10] and node N [23]: 70
Deterioration value between node N [16] and node N [20]: 45
Deterioration value between node N [16] and node N [23]: 50
Deterioration value between node N [20] and node N [23]: 55

Since the degradation value between the node N [10] and the node N [23] is “70”, which is equal to or greater than the degradation threshold, this path is detected as a degraded path and a child node of the selected node in the degraded path is extracted. (Steps S506 to S508).
The extracted nodes are node N [2] and node N [5].
Since the selected node (node N [1]) is the second layer, the subtree data reconstruction process is performed using the extracted two nodes (node N [2] and node N [5]). Implement (Steps S508-1, S509).

(6.3.2) The partial tree data reconstruction process is performed on the extracted nodes (node N [2] and node N [5]).
First, a node belonging to the path from each extraction node to the measurement terminal T associated with each extraction node is extracted (step S801).
The node between the node N [2] and the measurement terminal T associated therewith is only the node N [10] that is the node of the measurement terminal T. For node N [5], there is only node N [23]. That is, in S801, the nodes N [2] and N [5] of the first hierarchy and the nodes N [10] and N [23] of the measurement terminal T are extracted.
In this example, since the extraction nodes (node N [2], node N [5]) are nodes in the first layer, the node newly extracted in step S801 is only the node of the measurement terminal T. In the case of the second and higher layers, the node between the extraction node and the node of the measurement terminal T is also extracted.

Next, in the node of the measurement terminal T, the link deterioration value is set as it is as the link deterioration correction value, and the link deterioration value is changed to “0” (step S802).
Since the nodes of the measurement terminal T are the node N [10] and the node N [23], the link deterioration value and the link deterioration correction value in the node information of these two nodes are changed as shown in FIG. To do.

  The child node pair information to which the node of the measuring terminal T belongs is extracted from the child node pair information set in the node information of the parent node of the node of the measuring terminal T, and the link deterioration correction value of the node of the measuring terminal T is extracted from the path deterioration value. A value obtained by subtracting is set as a path deterioration value (step S803).

The child node pair information to which the node (node N [10] and node N [23]) of the measuring terminal T belongs is as shown in FIG. 64 (b).
Since the link degradation correction value of the node N [10] is “20” and the path degradation value of the child node pair information to which the node N [10] belongs is “20”, the path degradation value is “0 (= 20− 20) ".
Similarly, since the link degradation correction value of the node N [23] is “60” and the path degradation value of the child node pair information to which the node N [23] belongs is “30”, the path degradation value is “30 ( = 60-30) ".
By setting the newly calculated path degradation value in the child node pair information of FIG. 64 (b), it is updated as shown in FIG. 64 (c).

Next, processing is performed in order from the lower layer on the nodes of the first and higher layers (steps S804 and S805).
Since the nodes belonging to the first hierarchy are the node N [2] and the node N [5], the node N [2] is first selected at random (step S806).

The link deterioration value is set as the link deterioration correction value in the node information of the selected node, and the link deterioration value is changed to “0” (step S807).
With this processing, the node information in the selected node (node N [2]) becomes as shown in FIG.
Since the selected node (node N [2]) is a node belonging to the first layer, the deterioration section candidate extraction process and the maximum deterioration section extraction process are performed in the state after the correction process (steps S810 and S811).

(6.3.2.1) The degradation section candidate extraction process is performed on the selected node “node N [2]” (step S810).
By the partial tree data reconstruction processing so far, each piece of information of the partial tree having the node N [2] as the root node is as shown in FIG. Since the maximum value of the path degradation value set in the child node pair information of the selected node N [2] is not “0”, the two child node pair information having the largest path degradation value is extracted. Here, since the child node pair information of the selected node N [2] is as shown in FIG. 65A, the child node pair information of the path degradation value “10” and the child node pair information of the path degradation value “0” are extracted. become. The child node pair information of the path degradation value “10” is a pair of the node N [6] and the node N [7]. Since there are two child node pair information whose path degradation values are “0”, a pair of the node N [8] and the node N [9] is selected at random.

(6.3.3.2.1.1) Link deterioration value calculation processing is performed based on the extracted two child node pair information.
Since link degradation values have already been set for all the node information (node N [6] to node N [9]) corresponding to the nodes in the extracted two child node pair information, the link calculation value is not newly calculated, and the link The deterioration value calculation process ends.

  In the subtree having the node N [2] as the root node, the deterioration value between the measurement terminals T does not exceed the deterioration threshold value. Therefore, as shown in FIG. 65 (b), the selected node (node N [2]) and Node N [7], which is the node having the maximum deterioration value between measurement terminals T, is set as the subtree configuration node in the node information of node N [2].

(6.3.2.2) The maximum degradation section extraction process is performed on the selected node “node N [2]” (step S811).
The sum of the link deterioration value and the link total deterioration value of the subtree constituting node (node N [7]) is the reference deterioration value, and the value is “10”. Among the child nodes registered in the selected node (node N [2]), there is no node for which no link deterioration value is set, so that the reference deterioration value “10” as shown in FIG. Is set to the link total deterioration value of the node N [2] which is the selected node.
Thus, the process for the selected node (node N [2]) is completed.

Next, the node N [5] belonging to the same first hierarchy is selected as a selected node, and the process is performed (step S806).
Similar to the subtree data reconstruction process in the node N [2], the current link degradation value “0” is set as the link degradation correction value in the selected node (node N [5]), and the link degradation value is “0”. Set.
Since the selected node (node N [5]) is a node belonging to the first layer, the deterioration section candidate extraction process and the maximum deterioration section extraction process are performed in the state after the correction process.

(6.3.2.3) The deteriorated section candidate extraction process is performed on the selected node “node N [5]” (step S810).
By the partial tree data reconstruction process so far, each piece of information of the partial tree having the node N [5] as the root node is as shown in FIG. Since the maximum value of the path degradation value set in the child node pair information of the selected node N [5] is not “0”, the two child node pair information having the largest path degradation value is extracted. Therefore, the child node pair information of the nodes N [21] and N [22] in which the path degradation value “20” is set, and the nodes N [23] and N [in which the path degradation value “30” is set. 24] is extracted.

(6.3.3.2.3.1) Based on the extracted two child node pair information, link degradation value calculation processing is performed.
Since link degradation values have already been set for all the node information (node N [21] to node N [26]) in the two extracted node pairs, the link degradation value calculation processing ends without performing a new calculation process. It becomes.

  In the subtree having the node N [5] as the root node, the deterioration value between the measurement terminals T does not exceed the deterioration threshold value. Therefore, as shown in FIG. 66 (b), the selected node (node N [5]) Node N [24], which is the node having the maximum deterioration value between measurement terminals T, is set as node information of the node N [5] as a subtree configuration node.

(6.3.2.4) The maximum degradation section extraction process is performed on the selected node “node N [5]” (step S811).
The sum of the link deterioration value “30” and the link total deterioration value “NULL” of the subtree constituting node (node N [24]) is the reference deterioration value, and the value is “30”. Among the child nodes registered in the selected node (node N [5]), there is no node to which no link deterioration value is assigned, and therefore, as shown in FIG. 66 (b), the reference deterioration value “30”. Is set to the link total deterioration value of the node information corresponding to the node N [5] which is the selected node.
Thus, the process for the selected node (node N [5]) is completed.
In addition, the subtree data reconstruction process (step S509) called after the degraded section candidate extraction process is ended.

When the subtree data reconstruction process ends, the child node pair information including the extracted node is extracted from the child node pair information of the selected node (step S510).
Since the nodes extracted by the process of step S508 are the node N [2] and the node N [5], the child node pair information to which these nodes belong in the selected node (node N [1]) is shown in FIG. As shown in (a).

The sum of the link deterioration values of the nodes included in the path between the measurement terminals T associated with each child node after the reconstruction process is calculated, and the calculation result is set to the path deterioration value of the child node pair information (step S511).
From the node N [2] to the accompanying measurement terminal T, the node N [2] and the node N [7] belong. The two pieces of node information are as shown in FIG. 67 (b).
Also, the node N [4] and the node N [20] belong to the measuring terminal T associated with the node N [4]. The two pieces of node information are as shown in FIG. 67 (c).
Therefore, as illustrated in FIG. 67D, the path degradation value of the child node pair information to which the node N [2] belongs is the link degradation value “0” of the node N [2] and the link degradation value of the node N [7]. “35” that is the sum of “10”, the link degradation value “10” of the node N [4], and the link degradation value “15” of the node N [20].

Similarly, node N [5] and node N [23] belong from node N [5] to the associated measurement terminal T, and from node N [3] to the associated measurement terminal T, Node N [3] and node N [16] belong to it. Each node information is as shown in FIG. 67 (e).
Therefore, the path degradation value of the child node pair information to which the node N [5] belongs is, as shown in FIG. 67 (f), the link degradation value “0” of the node N [3] and the link degradation value of the node N [16]. It is “50” which is the sum of “20”, the link degradation value “0” of the node N [5] and the link degradation value “30” of the node N [24].

  Through the above processing, each piece of information in the subtree of the selected node (node N [1]) is as shown in FIG.

  Since the path degradation value of the child node pair information of the selected node (node N [1]) has changed, the degradation section candidate extraction process is performed again at the selected node (step S516).

(6.3.3) The degradation section candidate extraction process is performed on “node N [1]” that is the selected node (step S516).
Since the maximum value of the path degradation value set in the child node pair information of the selected node N [1] is not “0”, the two child node pair information having the largest path degradation value is extracted.
In this example, as shown in FIG. 68, since the node N [1] has only two child node pair information, the two are extracted.

(6.3.4) Link deterioration value calculation processing is performed based on the extracted two child node pair information.
Since the link deterioration values of the nodes belonging to the two child node pair information have already been calculated, this processing is terminated without doing anything.

  A degradation value between the measurement terminals T associated with each of the nodes belonging to the extracted child node pair is calculated (step S505).

Deterioration value between node N [7] and node N [16]: 30
Deterioration value between node N [7] and node N [20]: 35
Deterioration value between node N [7] and node N [24]: 40
Deterioration value between node N [16] and node N [20]: 45
Deterioration value between node N [16] and node N [24]: 50
Deterioration value between node N [20] and node N [24]: 55

Since the degradation value between any measurement terminals is less than the degradation threshold value “70”, a child node having the maximum sum of the link degradation value and the link total degradation value is extracted and set as a sub-tree constituting node of the selected node To do.
Here, since node N [5] has the maximum sum of the link deterioration value and the link total deterioration value, as shown in FIG. 69 (a), node N [5] is selected as the subtree constituting node of the selected node. Set.

(6.4) The aliasing deterioration analysis process is performed on the selected node “node N [1]” (step S70).
As shown in FIG. 69 (a), the node registered in the subtree constituting node of the selected node is the node N [5], and the sum of the link deterioration value and the link total deterioration value of the node N [5] is shown in FIG. As shown in the node information of 68 nodes N [5], it is “30”.
Also, the node information of the nodes N [2], N [3], N [4], and N [5] that are child nodes registered in the selected node (node N [1]) is shown in FIG. As shown, there is no node for which no link degradation value is set.
Therefore, the aliasing deterioration analysis ends here.

(6.5) The maximum degradation section extraction process is performed on the selected node “node N [1]” (step S80).
As described above, the node registered in the subtree constituting node of the selected node is the node N [5], and the sum of the link deterioration value and the link total deterioration value of the node N [5] is “30”. This is the reference deterioration value. Among the child nodes registered in the selected node (node N [1]), there is no node for which the link degradation value is not set, and therefore, as shown in FIG. 69 (b), the node N [1] The reference degradation value “30” is set as the total link degradation value of the node information.

  Thus, the analysis in the subtree having the selected node (node N [1]) as the root node is completed.

  Further, since the processing for the nodes in all layers is completed, the output unit 16 of the degraded path detection device 1 outputs the path detected as a degraded path in this process (step S90). As a result, all the degraded path detection processes are completed.

FIG. 70 is a diagram illustrating an output example of the output unit 16 of the degraded path detection device 1.
As shown in the figure, the location of the detected degraded path is shown for the link representing the network topology read from the network topology information. In the figure, as a degraded path to be detected, a node N [10] −node N [2] −node N [1] −node N [5] −node N [23] path, node N [17] − A path of node N [4] -node N [18] and a path of node N [21] -node N [5] -node N [26] are shown.

[4. Application to networks capable of subtree partitioning]
This embodiment can be applied to any network that can divide a subtree, not the subtree network itself.

FIG. 71 is a diagram illustrating a measurement target network that can be analyzed by the degraded path detection device according to the present embodiment. The measurement target network shown in the figure can be divided into subtrees. In addition, although the division | segmentation method to a subtree is not ask | required, as shown to the process of step S10 of FIG. 4, the 1st hierarchy-the Nth hierarchy can be selected in order.
FIG. 72 is a diagram showing an example in which the measurement target network NW shown in FIG. 71 is divided into subtrees. The network shown in FIG. 71 can be divided into two subtree networks NW1 and NW2 shown in FIG. 72 by some method. In FIGS. 71 and 72, routers R1 and R2 with the same reference numerals indicate the same nodes. Therefore, a path with the maximum deterioration value is found by the algorithm of this embodiment in each of the divided partial tree networks NW1 and NW2 shown in FIG.

  FIG. 73 shows a degraded path in partial tree network NW1 shown in FIG. In FIG. 73, a path indicated by a double line is a degraded path of the subtree network NW1, that is, a path between measurement terminals having the maximum degradation value. Similarly, the degraded path detection device 1 detects a degraded path of the subtree network NW2. As described above, if the network can be divided into partial trees, the degraded path detection apparatus according to the present embodiment can detect a degraded path even in a network other than the tree structure.

[5. effect]
According to the present embodiment, the measurement path (measurement terminal) is already minimized by using the measurement result of the measurement path, and all nodes are targeted without measuring the communication quality using the full mesh. Efficient quality measurement can be realized. As a result, it is possible to detect a degraded path while minimizing the load on the network, so that the application to a large-scale network is easy. In addition, the measurement equipment necessary for detecting the degraded path may be arranged only outside the network, and it is not necessary to install the measurement equipment inside the network for calculating the quality of each section. Therefore, the installation cost can be suppressed.
According to the present embodiment, the measurement process is performed while calculating and correcting the degradation value in the degradation path that has already been detected. Therefore, when the degradation in the other degradation path is eliminated, the degradation state is eliminated. It is possible to detect a degraded path in the network while suppressing the detection of a path to be lost, and since most of the detected degraded paths are independent, the wasteful separation work at the time of detecting a degraded path is suppressed. And early failure recovery is possible.

[6. Others]
In addition, the above-mentioned degradation path detection apparatus 1 has a computer system inside. The operation process of the subtree network construction unit 11, the measurement instruction execution unit 12, the measurement result reception / degradation value calculation unit 13, the measurement terminal selection / degradation value analysis unit 14, and the output unit 16 of the degradation path detection device 1. Is stored in a computer-readable recording medium in the form of a program, and the above processing is performed by the computer system reading and executing this program. The computer system here includes a CPU, various memories, an OS, and hardware such as peripheral devices.

Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

DESCRIPTION OF SYMBOLS 1 ... Degraded path detection apparatus 11 ... Subtree network construction part 12 ... Measurement instruction | indication execution part 13 ... Measurement result reception / deterioration value calculation part (deterioration value acquisition part)
14 ... Measurement terminal selection / degradation value analysis unit (selection analysis unit)
DESCRIPTION OF SYMBOLS 15 ... Memory | storage part 16 ... Output part 2 ... Network topology information storage apparatus R ... Router T ... Measuring terminal N ... Node

Claims (6)

A degradation path detection system comprising a degradation path detection device and a measurement terminal connected to the node in a network formed by connecting a plurality of nodes by links,
The degradation path detection device is:
A sub-tree network construction unit that selects the node of the hierarchy to which the measurement terminal is connected from the network, and decomposes the selected node into a tree-structure topology with the selected node as a root node;
In the topology of the tree structure disassembled by the partial tree network construction unit, a measurement instruction execution unit that instructs measurement of communication quality between the measurement terminals;
A degradation path is detected based on a degradation value of communication quality between the measurement terminals obtained according to an instruction from the measurement instruction execution unit, and a measurement terminal having a maximum degradation value with the root node is specified. And a selection analysis unit that performs selection analysis processing .
After the selection analysis processing by the selection analysis unit, the subtree network construction unit selects a node that is one layer higher than the current root node as a new root node, and selects the new node that has selected the network as a root node Subtree network construction processing that decomposes into a tree topology
The measurement instruction execution unit, in the topology of the tree structure obtained by decomposing the partial tree network construction unit is by the subtree network construction processing, the selection analyzing unit of the communication quality due between the measuring terminals identified by said selected analysis process Perform instruction execution processing to instruct measurement,
Repeatedly executing the processing from the selection analysis unit until the processing is completed for all the nodes in the network,
The degradation path detection system characterized by this. A degradation path detection system comprising a degradation path detection device and a measurement terminal connected to the node in a network formed by connecting a plurality of nodes by links,
The degradation path detection device is:
A subtree network constructing unit that selects a subtree network having a tree structure in which the selected node is selected as a root node and the measurement terminal is a leaf node in order from the nodes of the hierarchy to which the measurement terminal is connected. When,
A measurement instruction execution unit for instructing measurement of communication quality between the measurement terminals in the subtree network extracted by the subtree network construction unit;
Based on the measurement degradation value of the communication quality between the measurement terminals obtained according to the instruction from the measurement instruction execution unit, further select the measurement terminal to be measured, and between the measurement terminals selected by the measurement instruction execution unit Instructing measurement of the communication quality of the network, detecting a degraded path in the subtree network based on a measured degradation value between the measurement terminals obtained by the measurement, and maximizing the degradation value with the root node A selection analysis unit that identifies the measurement terminal,
When the root node is the lowest hierarchy, the subtree network construction unit sets all the measurement terminals connected to the root node as leaf nodes, and when the root node is not the lowest hierarchy, Extracting a subtree network with the measurement terminal selected by the selection analysis unit as a leaf node;
The degradation path detection system characterized by this. A degradation path detection system comprising a degradation path detection device and a measurement terminal connected to the node in a network formed by connecting a plurality of nodes by links,
The measurement terminal includes a unit that receives an instruction from the degraded path detection device and measures communication quality with the other measurement terminals,
The degradation path detection device is:
A subtree network constructing unit that selects a subtree network having a tree structure in which the selected node is selected as a root node and the measurement terminal is a leaf node in order from the nodes of the hierarchy to which the measurement terminal is connected. When,
A measurement instruction execution unit that selects a pair of measurement terminals in the subtree network extracted by the subtree network construction unit and instructs measurement of communication quality between the selected pair of measurement terminals;
A deterioration value acquisition unit that acquires a measurement result of communication quality between the selected pair in response to an instruction from the measurement instruction execution unit and calculates a deterioration value;
Based on the measurement degradation value between the measurement terminals acquired by the degradation value acquisition unit, select a pair of measurement terminals that need to be measured for detection of a degradation path, and the communication quality between the selected pair of measurement terminals The measurement instruction execution unit is instructed to perform measurement, and a degradation path is detected by obtaining a degradation value of a link in the subtree network based on a measurement degradation value between the pair of measurement terminals obtained by the degradation value acquisition unit. And a selection analysis unit that identifies the measurement terminal that maximizes the degradation value with the root node,
When the root node is the lowest hierarchy, the subtree network construction unit sets all the measurement terminals connected to the root node as leaf nodes, and when the root node is not the lowest hierarchy, Extracting a subtree network with the measurement terminal selected by the selection analysis unit as a leaf node;
The degradation path detection system characterized by this. The selection analysis unit selects a measurement terminal that requires measurement for detection of a degradation path based on the measurement degradation value between the measurement terminals acquired by the degradation value acquisition unit, and performs communication between the selected measurement terminals. The measurement instruction execution unit is instructed to perform quality measurement, and a degradation path is detected by obtaining a degradation value of a link in the subtree network based on the measurement degradation value between the measurement terminals obtained by the degradation value acquisition unit. If a degraded path is detected, the degradation value of each link in the degraded path is corrected, and then the degradation value with the root node is maximized based on the degradation value of the link in the subtree network. Identify the measuring device,
The degradation path detection system according to claim 3 characterized by things. A degradation path detection method used in a degradation path detection system comprising a degradation path detection device and a measurement terminal connected to the node in a network formed by connecting a plurality of nodes by links,
In the degraded path detection device,
The partial tree network construction unit selects the node of the layer to which the measurement terminal is connected from the network formed by connecting a plurality of nodes by links, and decomposes the topology into a tree structure with the selected node as a root node. The lowest layer subtree network construction process,
A measurement instruction execution unit, in the topology of the tree structure decomposed in the lowest layer subtree network construction process, a lowest layer instruction execution process for instructing measurement of communication quality between the measurement terminals;
The selection analysis unit detects a degradation path based on a degradation value of communication quality between the measurement terminals obtained according to the instruction, and identifies a measurement terminal having a maximum degradation value with the root node. Selection analysis process to
The subtree network construction unit selects a node that is one layer higher than the current root node as a new root node, and decomposes the subtree network into a tree-structure topology with the new node selected as the root node as a root node Construction process and
The measurement instruction execution unit includes an instruction execution process for instructing measurement between the measurement terminals specified by the selection analysis process in the topology of the tree structure decomposed in the subtree network construction process;
Repeatedly executing the process from the selection analysis process until the process is completed for all the nodes in the network,
A degradation path detection method characterized by the above. In a computer used as a degradation path detection device,
A step of constructing a lowermost sub- tree network that selects the node in the hierarchy to which the measurement terminal is connected from a network formed by connecting a plurality of nodes by links, and decomposes the selected node into a tree-structure topology with the selected node as a root node When,
In the topology of the tree structure disassembled in the lowest layer subtree network construction step, a lowest layer instruction execution step for instructing measurement of communication quality between the measurement terminals;
Detects the degradation path based on the degradation value of the communication quality between the measurement terminal obtained in response to the instruction, the selected analysis steps of degradation value between said root node to identify the measurement terminal as the maximum ,
A subtree network construction step of selecting a node one layer higher than the current root node as a new root node, and decomposing the network into a tree-structured topology with the new node selected as the root node;
An instruction execution step for instructing measurement of communication quality between the measurement terminals identified in the selection analysis step in the topology of the tree structure decomposed in the subtree network construction step ;
A repetitive processing step for repeatedly executing the processing from the selection analysis step until the processing is completed for all the nodes in the network;
Computer program characterized and Turkey allowed to run.

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