Network management device, network management system, and network management method

Abstract

To provide a network management device capable of identifying whether a fault originates from a network or a terminal unit when a connection failure occurs between the terminal unit and the same.SOLUTION: The network management device is configured to transmit transmission data to multiple terminal units, receive response data corresponding to the transmission data, and group-determine whether or not the terminal unit corresponding to the response data belongs to a group that includes multiple terminal units from the response data. The network management device also configured to determine the terminal unit as an individual error when determined that the terminal unit belongs to the group as the group determination result, and when the difference between the response time, which is the time from a point when the transmission data is transmitted to the terminal unit belonging to the group that includes multiple terminal units, to a point when the response data is received, and a first value of is greater than a first predetermined value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a network management device, a network management system, and a network management method, and more particularly to a network management device, a network management system, and a network management method for monitoring the states of each terminal device and the network with respect to a plurality of terminal devices connected to a predetermined network.

Background Art

[0002] Patent Document 1 provides a network failure detection system and a network failure detection device that can set an appropriate round-trip time (hereinafter referred to as RTT) threshold considering propagation delay. The network failure detection device according to Patent Document 1 groups monitoring target devices with similar RTT values based on the RTT values of each monitoring target device acquired during normal times (normal times). Then, the network failure detection device generates a distribution of RTT values for each group and determines the RTT threshold for that group from the generated distribution of RTT values.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A network management system according to the related art transmits messages to each of a plurality of terminal devices connected to the same network, and compares the RTT value, which is the response time of the response message, with a predetermined threshold value. When the response time is greater than the predetermined threshold value, it is detected that a failure has occurred in the network and the terminal device. However, when a failure is detected based only on the response time of each terminal device, there is a problem that it is difficult to determine whether the delay in the response time is due to a failure occurring in the network or a failure occurring in one of the plurality of terminal devices. In addition, the predetermined threshold value needs to be determined manually or automatically for each terminal device based on statistical information, which incurs costs for prior preparation.

[0005] The present disclosure provides a network management device, a network management system, and a network management method capable of specifying whether a failure is caused by the network or the terminal device when a connection failure occurs between the network management device and the terminal device.

Means for Solving the Problems

[0006] The network management device according to the present disclosure divides a plurality of terminal devices connected to a network into a plurality of groups, transmits transmission data to the plurality of terminal devices, and receives response data from the plurality of terminal devices to obtain the connection states of the plurality of terminal devices. The network management device includes an individual error determination unit that determines the connection state of a terminal device as an individual error when the difference between the response time, which is the time from the transmission of the transmission data to the reception of the response data for the terminal devices belonging to a group among the plurality of groups, and the average response time, which is the average value of the response times for each of the plurality of terminal devices belonging to that group, is greater than a first predetermined value, and for each of the plurality of terminal devices belonging to a group among the plurality of groups, when the difference between the current average response time, which is the average value of the current response times, and the previous average response time, which is the average value of the previous response times, is greater than a second predetermined value, at least one of a group error determination unit that determines the connection state of the group as a group error.

[0007] The network management method according to the present disclosure is a method for obtaining the connection states of a plurality of terminal devices by dividing the plurality of terminal devices connected to a network into a plurality of groups, transmitting transmission data to the plurality of terminal devices, and receiving response data corresponding to the transmission data. The network management method includes a step of measuring, for each of the plurality of terminal devices, a response time from the time of transmitting the transmission data to the time of receiving the response data. Further, when the difference between the response time for the terminal devices belonging to a group among the plurality of groups and the average response time, which is the average value of the response times for the plurality of terminal devices belonging to the group, is greater than a first predetermined value, determining an individual error for the terminal device; and, for the plurality of terminal devices belonging to a group among the plurality of groups, when the difference between the current average response time, which is the average value of the current response times, and the previous average response time, which is the average value of the previous response times, is greater than a second predetermined value, determining a group error for the group. The network management method includes at least one of these steps.

Effect of the Invention

[0008] According to the network management apparatus and the like of the present disclosure, when a connection failure with a terminal device occurs, it is possible to specify whether the failure is due to the network or the terminal device.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 2B

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, a more detailed description than necessary may be omitted. For example, a detailed description of well-known matters and a redundant description of substantially the same configuration may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art.

[0011] Note that the inventors provide the accompanying drawings and the following description for those skilled in the art to fully understand the present disclosure, and do not intend to limit the subject matter recited in the claims thereby.

[0012] (Embodiment 1) Hereinafter, Embodiment 1 will be described with reference to FIGS. 1 to 12.

[0013] [1-1. Configuration] FIG. 1 is a block diagram showing a configuration example of a network management system 1 according to Embodiment 1. In FIG. 1, the network management system 1 includes a plurality of terminal devices 801, two router devices 802A and 802B, networks 803A and 803B, and a network management device 804.

[0014] In FIG. 1, the plurality of terminal devices 801 are, for example, terminal devices such as projectors, displays, printers, scanners, etc. When receiving a request message, they return a response message in response. In FIG. 1, the plurality of n terminal devices 801 connected to the network 803A are denoted as A1 to An, and the plurality of m terminal devices 801 connected to the network 803B are denoted as B1 to Bm.

[0015] The router devices 802A and 802B are communication devices that manage communication paths on the networks 803A and 803B, respectively. The terminal devices A1 to An are communicably connected to the network management device 804 via the network 803A, and the terminal devices B1 to Bm are communicably connected to the network management device 804 via the network 803B.

[0016] The network management device 804 is a terminal device such as a computer, and by executing a program stored in an internal or external storage medium, it manages the communication state between a plurality of terminal devices 801 connected to the networks 803A and 803B and the network management device 804, and presents it to a user (not shown). Also, there is an abnormal location 805 in the network 803B where an abnormality has occurred in the communication state, and a larger delay has occurred in a part of the communication path between the terminal devices B1 to Bm and the network management device 804 than in the case of normal operation without the abnormal location 805.

[0017] FIG. 2A is a block diagram showing a detailed configuration example of the network management device 804 in FIG. 1. In FIG. 2A, the terminal device management unit 104 stores terminal device information for dividing and managing a plurality of terminal devices 801 connected to the network into a plurality of groups. The terminal device information includes address information such as the local IP address of the terminal device 801.

[0018] In FIG. 2A, the transmission data setting unit 103 sets transmission data for acquiring the communication state of the terminal device 801 based on the terminal device information of the terminal device management unit 104. The transmission / reception unit 101 transmits the transmission data set by the transmission data setting unit 103 to the terminal device 801 and receives response data from each terminal device 801. The packet analysis unit 102 associates the response data received by the transmission / reception unit 101 with the transmission data set by the transmission data setting unit 103, measures the response time from transmission to reception, and then outputs a set of terminal device information and response data to the group determination unit 105.

[0019] The group determination unit 105 determines whether the terminal device 801 corresponding to the response data belongs to a group based on the information stored in the terminal device management unit 104. When the terminal device 801 belongs to a group, the group determination unit 105 adds group information to the terminal device information and the response data and outputs the result to the group response analysis unit 106. When the terminal device 801 does not belong to a group, the group determination unit 105 directly outputs the input terminal device information and response data to the communication state analysis unit 107. The group response analysis unit 106 calculates the average value of the response times of the terminal devices 801 belonging to the same group as the terminal device 801, and further calculates the time difference between the response time of the terminal device 801 and the average response time of the group.

[0020] The reference time setting unit 108 sets the reference response time of each terminal device 801 and the reference average response time of each group as the reference values of the response time of the terminal device 801 in the normal state and the average response time of the group. The communication state analysis unit 107 compares the reference response time set by the reference time setting unit 108 with the response data of the terminal device 801 and analyzes the communication state based on the delay amount. Similarly, the reference time setting unit 108 compares the reference average response time set by the reference time setting unit 108 with the average response time of the group and analyzes the communication state. The error determination unit 109 sets determination information for notifying the user as a warning or an error based on the analysis result of the communication state analysis unit 107. The display unit 110 displays the failure cause to the user based on the determination result of the error determination unit 109.

[0021] FIG. 2B is a flowchart showing the control process of the network management device 804. The operation of the network management device 804 will be described later.

[0022] Hereinafter, the detailed configuration of each part of the network management system 1 will be described with reference to FIGS. 3 to 8.

[0023] FIG. 3 is a block diagram showing a detailed configuration example of the packet analysis unit 102 in FIG. 2A. In FIG. 3, the packet analysis unit 102 includes a received data storage unit 201, a transmitted data storage unit 202, a time information output unit 203, and a received data shaping unit 204.

[0024] In FIG. 3, the time information output unit 203 outputs time information indicating the current time to the received data storage unit 201 and the transmitted data storage unit 202. The transmitted data storage unit 202 adds the time information of the time when the transmitted data was input (the time when the transmitted data was transmitted to the terminal device 801) to the transmitted data input from the transmitted data setting unit 103 and stores it. Similarly, the received data storage unit 201 adds the information of the time when the response data was input (the time when the response message was received from the terminal device 801) to the response data received from the terminal device 801 via the transceiver unit 101 and stores it. The received data shaping unit 204 reads out the data stored in the received data storage unit 201 and the transmitted data storage unit 202 and outputs it to the group determination unit 105 collectively.

[0025] FIG. 4 is a block diagram showing a detailed configuration example of the transmitted data setting unit 103 in FIG. 2A. In FIG. 4, the transmitted data setting unit 103 includes a communication command management unit 301, a transmitted data creation unit 302, and a transmission address setting unit 303.

[0026] In FIG. 4, the communication command management unit 301 stores various command (command) groups for transmitting and receiving information with the terminal device 801. The transmission address setting unit 303 sets the address (IP address) of the destination terminal device 801 based on the information of each terminal device 801 input from the terminal device management unit 104, and outputs it to the transmission data creation unit. The transmission data creation unit 302 creates a request message to be transmitted to the terminal device 801 using the address set by the transmission address setting unit 303 and the command group stored in the communication command management unit 301, transmits it to the terminal device 801 via the transmission and reception unit 101, and outputs it to the packet analysis unit 102. The packet analysis unit 102 associates the transmitted packet and the received response message with the terminal device 801 from which the received response message was transmitted.

[0027] FIG. 5 is a block diagram showing a detailed configuration example of the group determination unit 105 in FIG. 2A. In FIG. 5, the packet information extraction unit 401 extracts, from each of the input response data, the response data, the correspondence information of the terminal device 801 that transmitted it, and the information on the response time taken from transmission to reception, and outputs them to the determination unit 402. The determination unit 402 determines whether each terminal device 801 belongs to any group based on the correspondence information from the group management unit 403. If the terminal device 801 belongs to any group, the extracted correspondence information and response time information are output to the group setting unit 404. The group setting unit 404 adds information related to the group to the correspondence information and response time information, and outputs it to the group response analysis unit 106. If the terminal device 801 does not belong to any group, the correspondence information and response time information are output to the communication state analysis unit 107.

[0028] FIG. 6 is a block diagram showing a detailed configuration example of the group response analysis unit 106 in FIG. 2A. In FIG. 6, the group response analysis unit 106 includes a time information extraction unit 501, a response time detection unit 502, a previous value storage unit 503, and a packet response analysis unit 504.

[0029] In FIG. 6, the time information extraction unit 501 extracts time information from the information input from the group determination unit 105. The response time detection unit 502 calculates the response time of the terminal device 801 based on the time information, and outputs it to the previous value storage unit 503 and the packet response analysis unit 504. The previous value storage unit 503 temporarily stores the response time input from the response time detection unit 502 at the immediately previous time, and outputs the stored response time to the packet response analysis unit 504 as necessary. The packet response analysis unit 504 obtains the difference between the response time at the current time and the response time at the immediately previous time, further calculates the average response time of the group, and outputs the response time information to the communication state analysis unit 107.

[0030] FIG. 7 is a block diagram showing a detailed configuration example of the communication state analysis unit 107 in FIG. 2A. In FIG. 7, the communication state analysis unit 107 includes a received data analysis unit 601, a delay amount analysis unit 602, a previous value comparison unit 603, and a communication state setting unit 604.

[0031] In FIG. 7, information about the response time of the terminal device 801 is input to the received data analysis unit 601 from the group response analysis unit 106 if the terminal device 801 belongs to a group, or from the group determination unit 105 if the terminal device 801 does not belong to a group. The received data analysis unit 601 acquires the current state of the terminal device 801 from the input information and outputs it to the communication state setting unit 604. Regarding the terminal device 801 that does not belong to a group, the received data analysis unit 601 specifies the connection state of the terminal device 801 to the network based on the input terminal device information.

[0032] FIG. 8 is a block diagram showing a detailed configuration example of the error determination unit 109 in FIG. 2A. In FIG. 8, the error determination unit 109 includes an individual error determination unit 701, a threshold setting unit 702, and a group error determination unit 703. In FIG. 8, the threshold setting unit 702 sets a threshold for the delay amount of the response time of the terminal device 801. The individual error determination unit 701 determines whether the delay amount of the response time of the terminal device 801 is longer than the threshold response time from the threshold setting unit 702. The group error determination unit 703 determines the communication state in units of groups. The threshold may be a value empirically input by the user, or may be automatically determined based on the variation range of the delay time up to now.

[0033] [1-2. Operation] Regarding the network management system configured as described above, its operation will be described below with reference to FIGS. 2B and 9A to 12.

[0034] FIG. 2B is a flowchart showing an operation example of the control process of the network management device 804 in FIG. 1. In FIG. 2B, the network management device 804 includes steps S100, S200, S300, S400, S500, and S1200. In step S100, the transmission data setting unit 103 of the network management device 804 sets the transmission data to be transmitted to each terminal device 801.

[0035] In FIG. 2B, in step S200, the network management device 804 transmits the transmission data set in step S100 to each terminal device 801 and waits until response data is received from the terminal device 801. In the subsequent step S300, the packet analysis unit 102, the group determination unit 105, the group response analysis unit 106, and the communication state analysis unit 107 analyze the received response data to obtain various information such as the response time and the average response time of the group.

[0036] In the subsequent step S400, the terminal device 801 determines whether it belongs to any group. If the terminal device 801 belongs to any group, it proceeds to step S500. If it does not belong to any group, it proceeds to the error determination process in step S1200. In step S500, for the terminal device 801 belonging to a certain group, the group response analysis unit 106 obtains the difference between the response time of the terminal device 801 and the average response time of the group to which the terminal device 801 belongs. Finally, in step S1200, an error determination process described in detail with reference to FIG. 12 is performed.

[0037] FIG. 9A is a timing chart showing an operation example of data transmission and reception processing in the network management system 1 of FIG. 1. FIG. 9A shows the data transmission and reception between the network management device 804 and the terminal devices A1 and B1 in step S200 of FIG. 2B. Here, the network management device 804 simultaneously transmits transmission data A1s and B1s for prompting responses to the terminal devices A1 and B1 to the terminal device 801. Thereafter, response data A1r is received from the terminal device A1 after a time tA1 from the completion of the transmission of the transmission data A1s, and response data B1r is received after a time tB1 from the completion of the transmission of the transmission data B1s. The times tA1 and tB1 from the completion of the transmission of the transmission data A1s and B1s to the completion of the reception of the response data A1r and B1r are referred to as the response times of the terminal devices A1 and B1.

[0038] FIG. 9B is a diagram showing an example table of information analyzed by the packet analysis unit 102. In FIG. 9B, it can be seen that the response time until the reception of the response data A1r is represented as "tA1" and the response time until the reception of the response data B1r is represented as "tB1" by the packet analysis unit 102.

[0039] FIG. 10A and FIG. 10B are diagrams showing response time data output from the group response analysis unit 106 to the communication state analysis unit 107. FIG. 10A and FIG. 10B correspond to Group A and Group B, respectively. Referring to FIG. 10A, it can be seen that Group A includes terminal devices A1 to An, and the response times of the respective response data A1r to Anr have changed from the previous response times tA1p to tAnp to the current response times tA1 to tAn. Similarly, FIG. 10B shows that the response times of the respective response data B1r to Bmr of the terminal devices B1 to Bm belonging to Group B have changed from the previous response times tB1p to tBmp to the current response times tB1 to tBm.

[0040] FIG. 11A is a diagram showing a table of the response states of the terminal device 801 calculated in step S500 of FIG. 2B. In FIG. 11A, Group A includes terminal devices A1 to An, each of which is transmitting response data A1r to Anr to the network management device 804. Also, the average value of the response times tA1 to tAn of the terminal devices A1 to An is the average response time tAavg, and the difference between the response times tA1 to tAn and the average response time tAavg is represented by the differential response times ΔtA1 to ΔtAn. That is, the following equation holds. ΔtAi = tAi - tAavg (i = 1, 2,... n) Furthermore, assuming that the threshold α is set by the threshold setting unit 702 of the error determination unit 109, the result of determining whether the differential response time is less than the threshold α by the individual error determination unit 701 of the error determination unit 109 is shown as the individual delay determination result (in FIG. 11A, "○" if YES and "×" if NO).

[0041] For example, in the case of FIG. 11A, since the differential response time ΔtA1 is less than α, the delay determination is "○", but the differential response time ΔtA2 is greater than or equal to α, and the delay determination is "×". The same individual delay determination results are determined for all groups.

[0042] FIG. 11B is a diagram showing another table of the response states of the terminal device 801 calculated in step S500 of FIG. 2B. In FIG. 11B, the average response time of group B at the current time t (corresponding to the current average response time) is represented by “gB(t)”. Also, “gB(t−1)”, which is the average response time at the immediately previous time t−1, is stored in the previous value storage unit 503 of the group response analysis unit 106, and the difference ΔgB(t) between the current average response time and the previous average response time (corresponding to the immediately previous average response time) is obtained. That is, the following equation holds. ΔgB(t)=gB(t)-gB(t-1) Furthermore, assuming that the threshold β is set by the threshold setting unit 702 of the error determination unit 109, the result of determining by the group error determination unit 703 of the error determination unit 109 whether the difference ΔgB(t) is smaller than the threshold β is used as the group delay determination result. In FIG. 11B, if YES, it is indicated by “◯”, and if NO, it is indicated by “×”.

[0043] For example, in the case of FIG. 11B, the differences ΔgB(t−1) to ΔgB(t−n) are smaller than the threshold β, so the delay determination is “◯”, but the difference ΔgB(t) is equal to or greater than the threshold β, and the delay determination is “×”. The same group delay determination results are obtained for all groups. Based on these individual delay determination results and group delay determination results, an error determination process is performed in the next step S1200.

[0044] FIG. 12 is a flowchart showing an operation example of the error determination process in the network management device 804. In FIG. 12, the error determination process (step S1200) includes steps S1201 to S1207.

[0045] In FIG. 12, first, in step S1201, the network management device 804 acquires the group delay determination result and the individual delay determination result for all groups and all terminal devices 801. Next, in step S1202, it is determined whether the acquired group delay determination result is an error determination (×). If YES, the process proceeds to step S1204A, and if NO, the process proceeds to step S1203.

[0046] In step S1204A, since the group delay determination result is an error determination, it can be seen that a delay has occurred in the entire group (group B in the example of FIG. 11B). Therefore, a more detailed cause is analyzed. For example, phenomena such as missing response data or occurrence of transmission / reception retries despite reception of response data are detected, and more detailed causes such as a poor connection status with the network or authentication failure are determined. After step S1204A, the error determination process proceeds to step S1207, and the occurrence of group delay and the more detailed cause analyzed in step S1204A are presented to the user via the display unit 110.

[0047] In step S1203, it is determined whether the obtained individual delay determination result is an error determination (×). If YES, the process proceeds to step S1204B; if NO, the process proceeds to S1205.

[0048] In step S1204B, since the individual delay determination result is an error determination, it can be seen that a delay has occurred only in that terminal device 801 (terminal device A2 in the example of FIG. 11A). Therefore, a more detailed cause is analyzed (the details are the same as in step S1204A). After step S1204B, the error determination process proceeds to step S1206, and the occurrence of individual delay and the more detailed cause analyzed in step S1204B are presented to the user via the display unit 110.

[0049] If there is no error determination in either step S1202 or S1203, in step S1205, a screen on which various pieces of information extracted from the received response data are arranged is created and presented to the user via the display unit 110.

[0050] [1-3. Effects, etc.] As described above, the network management system 1 according to Embodiment 1 simultaneously performs group delay determination and individual delay determination on the terminal devices 801 that are group-managed. As a result, when a connection failure occurs between the network management device 804 and the terminal device 801, the user can identify whether it is caused by the terminal device 801 or the networks 803A and 803B, and can take appropriate measures.

[0051] (Other Embodiments) In Embodiment 1, each of the networks 803A and 803B was treated as groups A and B. However, the method of dividing into a plurality of groups is not limited to this. For example, a plurality of networks may be included in one group, or a plurality of terminal devices connected to one network may be classified into a plurality of groups.

[0052] Also, in Embodiment 1, only the terminal device 801 was the management target. However, the management target is not limited to the terminal device, and may be any device that can return response data to the transmission data by connecting to a network such as a router device.

[0053] As described above, embodiments have been described as examples of the technology in the present disclosure. For this purpose, the accompanying drawings and detailed description have been provided.

[0054] Therefore, among the components described in the accompanying drawings and detailed description, not only the components essential for solving the problems but also the components not essential for solving the problems for exemplifying the above technology may be included. Therefore, just because those non-essential components are described in the accompanying drawings and detailed description, it should not be immediately determined that those non-essential components are essential.

[0055] Also, since the above-described embodiments are for exemplifying the technology in the present disclosure, various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or their equivalents.

Industrial Applicability

[0056] The present disclosure is applicable to a network management system for a network including a plurality of terminal devices.

Explanation of Signs

[0057] 1 Network management system 101 Transmission / reception unit 102 Packet analysis unit 103 Transmission data setting unit 104 Terminal device management unit 105 Group determination unit 106 Group response analysis unit 107 Communication state analysis unit 108 Reference time setting unit 109 Error determination unit 110 Display unit 201 Received data storage unit 202 Transmission data storage unit 203 Time information output unit 204 Received data shaping unit 301 Communication command management unit 302 Transmission data creation unit 303 Transmission address setting unit 401 Packet information extraction unit 402 Determination unit 403 Group management unit 404 Group setting unit 501 Time information extraction unit 502 Response time detection unit 503 Previous value storage unit 504 Packet response analysis unit 601 Received data analysis unit 602 Delay amount analysis unit 603 Previous value comparison unit 604 Communication state setting unit 701 Individual error determination unit 702 Threshold setting unit 703 Group error determination unit 801 Terminal device 802A, 802B Router device 803A, 803B Network 804 Network Management Device 805 Abnormal Location Terminal Devices A1, A2, …, An, B1, B2, …, Bn

Claims

1. Transmit transmission data to a plurality of terminal devices, receive response data corresponding to the transmission data, Perform a group determination from the response data as to whether the terminal device corresponding to the response data belongs to a group including a plurality of terminal devices, As a result of the group determination, when it is determined that the terminal device belongs to the group, perform at least one of the following determinations (1) and (2): (1) When the difference between the response time, which is the time from the transmission of the transmission data to the reception of the response data for the terminal device belonging to the group including a plurality of terminal devices, and the first value is greater than the first predetermined value, determine that there is an individual error for the terminal device. (2) When the difference between the second value and the third value calculated from the respective response times of the plurality of terminal devices belonging to the group is greater than the second predetermined value, determine that there is a group error for the group. Output either the determined individual error or the group error. A network management device.

2. The first value is a value calculated based on the respective response times of the plurality of terminal devices belonging to the group. The network management device according to Claim 1.

3. The third value is a value calculated based on the respective previous response times of the plurality of terminal devices belonging to the group. The network management device according to Claim 1.

4. Regarding the individual error, when the difference between the response time and the average response time, which is the average value of the response times for the plurality of terminal devices belonging to the group, is greater than the first predetermined value, determine that there is an individual error for the terminal device. Regarding the group error, for the plurality of terminal devices belonging to the group, when the difference between the current average response time, which is the average value of the current response times, and the previous average response time, which is the average value of the previous response times, is greater than the second predetermined value, determine that there is a group error for the group. The network management device according to Claim 1.

5. Obtain the time when the transmission data was transmitted and the time when the response data was received, and measure the difference between the time when the transmission data was transmitted and the time when the response data was received as the response time. The network management device according to Claim 1.

6. If, as a result of the determination of the individual error and the group error, no error is identified, output the information included in the response data. The network management device according to claim 1.

7. Display the result of either the determined individual error or the group error. The network management device according to claim 1.

8. The plurality of terminal devices, A network management system comprising the network management device according to any one of claims 1 to 7. Network management system.

9. Transmitting transmission data to a plurality of terminal devices and receiving response data corresponding to the transmission data; A group determination step of determining whether a terminal device corresponding to the response data belongs to a group including a plurality of terminal devices from the response data; Transmitting transmission data to a plurality of terminal devices and receiving response data corresponding to the transmission data; Measuring a response time from the time of transmission of the transmission data to the time of reception of the response data for each of the plurality of terminal devices, Furthermore, as a result of the group determination step, when it is determined that the terminal device belongs to the group, at least one of the following steps (1) and (2) is provided, (1) When the difference between the response time for the terminal device belonging to the group among the plurality of groups and the first value is greater than a first predetermined value, determining an individual error for the terminal device; (2) When the difference between a second value and a third value, which are values calculated from the respective response times of the plurality of terminal devices belonging to the group among the plurality of groups, is greater than a second predetermined value, determining a group error for the group; Outputting either the determined individual error or the group error. Network management method.

10. The first value is a value calculated based on the respective response times of the plurality of terminal devices belonging to the group. The network management method according to claim 9.

11. The third value is a value calculated based on the respective previous response times of the plurality of terminal devices belonging to the group. The network management method according to claim 9.

12. When the difference between the response time of the individual error and the average response time, which is the average value of the response times for a plurality of terminal devices belonging to the group, is greater than a first predetermined value, it is determined as an individual error for the terminal device. When the difference between the current average response time, which is the average value of the current response times for a plurality of terminal devices belonging to the group, and the previous average response time, which is the average value of the previous response times, is greater than a second predetermined value, it is determined as a group error for the group. The network management method according to claim 9.

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