Method and system to calculate network latency, and to display the same field of the invention

• US 20010050903A1
• Filed: 01/25/2001
• Published: 12/13/2001
• Est. Priority Date: 01/28/2000
• Status: Active Grant

• Current Assignee: Dynatrace LLC (Dynatrace, Inc.)
• Original Assignee: Compuware Corporation (KKR & Co., Inc.)
• Inventors: Vanlint, Paul
• Granted Patent: US 6,922,417 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 1/24 Testing correct operation
• CPC Class Codes: H04L 41/22 comprising specially adapted graphical user interfaces [GUI]
• CPC Class Codes: H04L 43/0858 One way delays
• CPC Class Codes: H04L 43/106 using time related information in packets, e.g. by adding timestamps

Abstract

A method to calculate network latency includes correlating a first packet identifier recorded at a first network location with a second packet identifier recorded at a second network location, wherein the first and second packet identifiers indicate a common first packet and have respective first and second timestamps associated therewith. A first network traversal time for the first packet is calculated as the difference between the first and second timestamps associated with the first and second packet identifiers respectively. The network traversal time for the first packet is then the graphically display.

Claims

1. A method of calculating network latency, the method including:

correlating a first packet identifier recorded at a first network location with a second packet identifier recorded at a second network location, wherein the first and second packet identifiers indicate a common first packet and have respective first and second timestamps associated therewith; and

calculating a first network traversal time for the first packet as the difference between the first and second timestamps associated with the first and second packet identifiers respectively.

2. The method of

claim 1

wherein the first packet identifier and the first timestamp are contained in a first trace file captured at the first network location, and wherein the second packet identifier and the second timestamp are contained in a second trace file captured at the second network location.

3. The method of

claim 1

including at least partially merging the first and second trace files into a merged file, the merged file containing an entry for each correlation of a first packet identifier with a second packet identifier.

4. The method of

claim 1

wherein the correlating includes correlating the first packet identifier with multiple packet identifiers recorded at the second network location as a result of fragmentation of the first packet during transmission from the first network location to the second network location.

5. The method of

claim 4

wherein the calculating includes calculating multiple traversal times as the respective differences between the first timestamp and each of multiple timestamps associated with the respective multiple packet identifiers.

6. The method of

claim 5

including identifying a minimum traversal time from among the multiple traversal times as a selected offset.

7. The method of

claim 1

including determining whether clock drift influenced a plurality of traversal times for a plurality of packets transmitted between the first and second network locations and, if so, then adjusting the plurality of traversal times to compensate for the clock drift.

8. The method of

claim 7

wherein the adjusting of the plurality of traversal times includes calibrating each of a plurality of timestamps associated with a plurality of packet identifiers recorded at the second network location.

9. The method of

claim 1

wherein bi-directional packet transmissions occur between the first and second network locations, and the correlating includes determining a direction of transmission of the first packet between the first and second network locations.

10. The method of

claim 1

wherein the first packet is transmitted from the first network location to the second network location, the method including correlating a third packet identifier recorded at the second network location with a fourth packet identifier recorded at the first network location, wherein the third and fourth packet identifiers identify a second packet transmitted from the second network location to the first network location responsive to the first packet, and wherein the third and fourth packet identifiers have respective third and fourth timestamps associated therewith.

11. The method of

claim 10

including calculating a second network traversal time for the second packet as the difference between the third and fourth timestamps.

12. The method of

claim 11

including calculating an average traversal time between the first and second network locations as the average of the first and second network traversal times.

13. The method of

claim 11

wherein the first and second network traversal times are minimum traversal times for fragmented transmissions of the first and second packets respectively.

14. The method of

claim 12

including adjusting at least the first traversal time based on the average traversal time.

15. The method of

claim 12

including adjusting the first and second traversal times based on the average traversal time.

16. The method of

claim 14

wherein the adjusting includes calibrating timestamps associated with the second network location utilizing the average traversal time.

17. The method of

claim 1

including outputting at least the first traversal time.

18. The method of

claim 17

wherein the outputting comprises generating a graphical display of the first traversal time.

19. A system to calculate network latency, the system including:

a correlation engine to correlate a first packet identifier recorded at a first network location with a second packet identifier recorded at a second network location, wherein the first and second packet identifiers indicate a common first packet and have respective first and second timestamps associated therewith; and

a synchronization engine to calculate a first network traversal time for the first packet as the difference between the first and second timestamps associated with the first and second packet identifiers respectively.

20. The system of

claim 19

wherein the first packet identifier and the first timestamp are contained in a first trace file captured at the first network location, and wherein the second packet identifier and the second timestamp are contained in a second trace file captured at the second network location.

21. The system of

claim 19

wherein the synchronization engine is to at least partially merge the first and second trace files into a merged file, the merged file containing an entry for each correlation of a first packet identifier with a second packet identifier.

22. The system of

claim 19

wherein the correlation engine is to correlate the first packet identifier with multiple packet identifiers recorded at the second network location as a result of fragmentation of the first packet during transmission from the first network location to the second network location.

23. The system of

claim 22

wherein the synchronization engine is to calculate multiple traversal times as the respective differences between the first timestamp and each of multiple timestamps associated with the respective multiple packet identifiers.

24. The system of

claim 23

wherein the synchronization engine is to identify a minimum traversal time from among the multiple traversal times as a selected offset.

25. The system of

claim 19

wherein the synchronization engine is to determine whether clock drift influenced a plurality of traversal times for a plurality of packets transmitted between the first and second network locations and, if so, then to adjust the plurality of traversal times to compensate for the clock drift .

26. The system of

claim 25

wherein the synchronization engine is to calibrate each of a plurality of timestamps associated with a plurality of packet identifiers recorded at the second network location.

27. The system of

claim 19

wherein bi-directional packet transmissions occur between the first and second network locations, and the correlation engine is to determine a direction of transmission of the first packet between the first and second network locations.

28. The system of

claim 19

wherein the first packet is transmitted from the first network location to the second network location, the correlation engine is to correlate a third packet identifier recorded at the second network location with a fourth packet identifier recorded at the first network location, wherein the third and fourth packet identifiers identify a second packet transmitted from the second network location to the first network location responsive to the first packet, and wherein the third and fourth packet identifiers have respective third and fourth timestamps associated therewith.

29. The system of

claim 28

wherein the synchronization engine is to calculate a second network traversal time for the second packet as the difference between the third and fourth timestamps.

30. The system of

claim 29

wherein the synchronization engine is to calculate an average traversal time between the first and second network locations as the average of the first and second network traversal times.

31. The system of

claim 28

wherein the first and second network traversal times are minimum traversal times for fragmented transmissions of the first and second packets respectively.

32. The system of

claim 30

wherein the synchronization engine is to adjust at least the first traversal time based on the average traversal time.

33. The system of

claim 30

wherein the synchronization engine is to adjust the first and second traversal times based on the average traversal time.

34. The system of

claim 32

wherein the synchronization engine is to calibrate timestamps associated with the second network location utilizing the average traversal time.

35. The system of

claim 19

including a visualization module to output at least the first traversal time.

36. The method of

claim 35

wherein the visualization module is to generate a graphical display of the first traversal time.

37. A computer-readable medium storing a sequence of instructions that, when executed by machine, causing machine to perform method of calculating network latency, the method including:

correlating a first packet identifier recorded at a first network location with a second packet identifier recorded at a second network location, wherein the first and second packet identifiers indicate a common first packet and have respective first and second timestamps associated therewith; and

calculating a first network traversal time for the first packet as the difference between the first and second timestamps associated with the first and second packet identifiers respectively.