Network management device, network management system and network management method

1. A network management device that 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 corresponding to the transmission data to acquire connection states of the plurality of terminal devices, the network management device comprising at least one of:

an individual error determiner configured to determine that an individual error occurs in a target terminal device belonging to a group among the plurality of groups when a difference between (i) a response time from a transmission time of the transmission data to a reception time of the response data for the target terminal device and (ii) a first reference time is larger than a first predetermined value; and

a group error determiner configured to determine that a group error occurs in a target group to which two or more terminal devices belongs among the plurality of groups when a difference between (i) a current average response time that is an average value of the response time for each of the two or more terminal devices and (ii) a second reference time is larger than a second predetermined value.

2. The network management device according to claim 1 ,

wherein a data of the first reference time is generated based on the response time for each of two or more terminal devices belonging to the group.

3. The network management device according to claim 1 ,

wherein a data of the second reference time is generated based on the response time for each of the two or more terminal devices.

4. The network management device according to claim 3 ,

wherein a data of the first reference time is generated based on a value that is generated in each of the plurality of groups.

5. The network management device according to claim 3 ,

wherein a data of the first reference time is generated based on a previous response time for each of the two or more terminal devices.

6. The network management device according to claim 1 , further comprising a time information output unit configured to output a current time,

wherein the individual error determiner or the group error determiner acquires a time when the transmission data is transmitted and a time when the response data is received from the time information output unit, and measures a difference between the time when the transmission data is transmitted and the time when the response data is received as the response time.

7. The network management device according to claim 1 , wherein

the network management device presets a reference response time for the plurality of terminal devices, and

the individual error determiner determines that the individual error occurs when a difference between the reference response time and the response time of the target terminal device is larger than a third predetermined value.

8. The network management device according to claim 1 , wherein

the network management device presets a reference average response time for the plurality of groups, and

the group error determiner determines that the group error occurs when a difference between the reference average response time and the current average response time is larger than a fourth predetermined value.

9. The network management device according to claim 1 , further comprising a display unit configured to display the acquired connection states including the individual error or the group error.

10. A network management system comprising:

the network management device according to claim 8 ; and

the plurality of terminal devices.

11. A network management method for dividing a 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 to acquire connection states of the plurality of terminal devices, the network management method comprising:

measuring, for each of the plurality of terminal devices, a response time from a transmission time of the transmission data to a reception time of the response data; and at least one of

determining that an individual error occurs in a target terminal device belonging to a group among the plurality of groups when a difference between (i) the response time for the target terminal device and (ii) a first reference time is larger than a first predetermined value; and

determining that a group error occurs in a target group to which two or more terminal devices belongs among the plurality of groups when a difference between (i) a current average response time that is an average value of the response time for each of the two or more terminal devices and (ii) a second reference time is larger than a second predetermined value.

12. A network management method for dividing a plurality of terminal devices connected to a network into a plurality of groups according to claim 11 ,

wherein a data of the first reference time is generated based on the response time for each of two or more terminal devices belonging to the group.

13. A network management method for dividing a plurality of terminal devices connected to a network into a plurality of groups according to claim 11 ,

wherein a data of the second reference time is generated based on the response time for each of the two or more terminal devices.

14. A network management method for dividing a plurality of terminal devices connected to a network into a plurality of groups according to claim 11 ,

wherein a data of the first reference time is generated based on a value that is generated in each of the plurality of groups.

15. A network management method for dividing a plurality of terminal devices connected to a network into a plurality of groups according to claim 11 ,

wherein a data of the first reference time is generated based on a previous response time for each of the two or more terminal devices.