Packet analysis device and packet analysis method

1. A non-transitory computer-readable recording medium having stored therein a packet analysis program that causes a computer to execute a process, the process comprising:

acquiring, from a relay device that relays packets between a first communication device and a second communication device, a plurality of first delay times generated by a round trip of the packets between the first communication device and the relay device, and a plurality of second delay times generated by a round trip of the packets between the second communication device and the relay device;

sorting the plurality of first delay times separately from the plurality of second delay times, based on delay time length;

calculating device delay times based on a first delay calculation that calculates for each device delay time a corresponding difference between one of the plurality of first delay times and one of the plurality of second delay times in a same rank after the sorting; and

operating the relay device based on the device delay times.

2. The non-transitory computer-readable recording medium according to claim 1 , the process further comprising:

detecting a device delay maximum value among the device delay times calculated in a predetermined time period; and

detecting an overload state of the relay device when an appearance frequency or ratio of the device delay maximum value is equal to or more than a predetermined threshold value.

3. The non-transitory computer-readable recording medium according to claim 1 , wherein the process:

calculates the device delay times based on the first delay calculation, when first variation states of the plurality of first delay times acquired in a predetermined time period and second variation states of the plurality of second delay times acquired in the predetermined time period are not in a specific variation state, and

calculates the device delay times based a second delay calculation that calculates an average difference between a first average value of the plurality of first delay times and a second average value of the plurality of second delay times, when the first variation states and the second variation states are in the specific variation state.

4. The non-transitory computer-readable recording medium according to claim 3 , wherein the process:

detects a plurality of first minimum values from the plurality of first delay times acquired in a first predetermined time period, to acquire a second minimum value which is a minimum value among the plurality of first minimum values,

detects a plurality of first maximum values from the plurality of second delay times acquired in the first predetermined time period, to acquire a second maximum value which is a maximum value among the plurality of first maximum values, and

detects that the first variation states and the second variation states are in the specific variation state, when a third minimum value among the plurality of first delay times acquired in a second predetermined time period and a third maximum value among the plurality of second delay times acquired in the second predetermined time period are both present within a range from the second minimum value to the second maximum value.

5. The non-transitory computer-readable recording medium according to claim 3 , wherein the process:

calculates a plurality of first difference values which are each a difference value between a minimum value among the plurality of first delay times acquired in the first predetermined time period and a maximum value among the plurality of second delay times acquired in the first predetermined time period,

detects a maximum difference value among the plurality of first difference values,

calculates a second difference value which is a difference value between a minimum value among the plurality of first delay times acquired in the second predetermined time period and a maximum value among the plurality of second delay times acquired in the second predetermined time period, and

determines that the first variation states and the second variation states are in the specific variation state in the predetermined time period from the first predetermined time period to the second predetermined time period, when the second difference value is less than the maximum difference value.

6. The non-transitory computer-readable recording medium according to claim 3 , wherein the process:

calculates first statistical information from the plurality of first delay times acquired in the first predetermined time period and the plurality of second delay times acquired in the first predetermined time period,

detects a maximum value in the first statistical information;

calculates second statistical information from the plurality of first delay times acquired in the second time and the plurality of second delay times acquired in the second predetermined time period; and

determines that the first variation states and the second variation states are in the specific variation state in the predetermined time period from the first predetermined time period to the second predetermined time period, when the second statistical information is less than the maximum value.

7. The non-transitory computer-readable recording medium according to claim 6 , wherein the process

calculates variances of the plurality of first delay times and the plurality of second delay times, or standard deviations of the plurality of first delay times and the plurality of second delay times, as the first statistical information and the second statistical information.

8. The non-transitory computer-readable recording medium according to claim 1 , wherein the operating includes detecting an overload state of the relay device when a maximum delay time, among the device delay times, exceeds a threshold.

9. The non-transitory computer-readable recording medium according to claim 8 , wherein the operating includes issuing instructions to a network connected to the relay device when the overload state of the relay device is detected.

10. A packet analysis method comprising:

acquiring, from a relay device that relays packets between a first communication device and a second communication device, a plurality of first delay times generated by a round trip of the packets between the first communication device and the relay device, and a plurality of second delay times generated by a round trip of the packets between the second communication device and the relay device;

sorting the plurality of first delay times separately from the plurality of second delay times based on a length of a delay time;

calculating device delay times, each based on a difference between one of the plurality of first delay times and one of the plurality of second delay times in a same rank after the sorting, by a processor; and

operating the relay device based on the device delay times.

11. The packet analysis method according to claim 10 , further comprising detecting an overload state of the relay device when a maximum delay time, among the device delay times, exceeds a threshold.

12. The packet analysis method according to claim 11 , further comprising issuing instructions to a network connected to the relay device when the overload state of the relay device is detected.

13. A packet analysis device comprising:

a memory;

a processor coupled to the memory and configured to;

acquire, from a relay device that relays packets between a first communication device and a second communication device, a plurality of first delay times generated by a round trip of the packets between the first communication device and the relay device, and a plurality of second delay times generated by a round trip of the packets between the second communication device and the relay device,

sort the plurality of first delay times separately from the plurality of second delay times based on a length of a delay time,

calculate device delay times, each based on a difference between one of the plurality of first delay times and one of the plurality of second delay times in a same rank after the sorting; and

operate the relay device based on the device delay times.

14. The packet analysis device according to claim 13 , wherein the processor is further configured to detect an overload state of the relay device when a maximum delay time, among the device delay times, exceeds a threshold.

15. The packet analysis device according to claim 14 , wherein the packet analysis device is connected to a network, and

wherein the packet analysis device further comprises a network interface configured to issue instructions to the network when the overload state of the relay device is detected.