IP Library › Granted Patent US 8,243,599
Granted Patent B2
US 8,243,599 · App. 11/555,484 · Granted Aug 14, 2012

Method and apparatus for high resolution passive network latency measurement

Assignee: Cisco Technology, Inc.
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Quick Facts
Patent No.
US 8,243,599
App. No.
11/555,484
Granted
Aug 14, 2012
Kind
B2
Abstract

A method includes receiving a first capture time corresponding to a first time that a data packet is received at a first probe and a second capture time corresponding to a second time that the data packet is received at a second probe. The data packet is from existing network traffic transmitted over a data network. The first and second probes can be configured to capture the data packet in response to a capture instruction. The first capture time and second capture time are different and are used to calculate the latency of at least a portion of a data network.

Claims (37)

1. A method for execution by one or more processors, the method comprising:

periodically synchronizing a time clock of a first probe connected to a first access point on a data network with a time clock of a second probe connected to a second access point on the data network, the frequency with which the synchronization occurs is increased or decreased based upon sensitivity to variations in timing of communications over the data network;

receiving a first capture time corresponding to a first time that a data packet is received at the first probe, the data packet being from the existing network traffic transmitted over the data network, the first probe being configured to capture the data packet in response to a first capture instruction;

receiving a second capture time corresponding to a second time that the data packet is received at the second probe, the second probe being configured to capture the data packet in response to a second capture instruction, the first time and second time being different; and

calculating, using one or more processors, the latency of at least a portion of the data network based on the first capture time and the second capture time.

2. The method of claim 1 , further comprising:

receiving a first data packet identifier associated with the data packet and associated with the first capture time;

receiving a second data packet identifier associated with the data packet and associated with the second capture time; and

associating, using the first data packet identifier and the second data packet identifier, the first capture time and the second capture time to calculate the latency.

3. The method claim 1 , wherein the first and second probes are programmed without disrupting the flow of the existing network traffic being measured for latency.

4. The method of claim 1 , wherein at least one of the first probe or the second probe is integrated into a network device.

5. The method of claim 1 , wherein the data packet is an inbound data packet, the method further comprising:

receiving a third capture time corresponding to a third time that an outbound data packet is received at the first probe;

receiving a fourth capture time corresponding to a fourth time that the outbound data packet is received at the second probe, the third time and fourth time being different; and

calculating the latency of at least a portion of the data network using the third capture time and the fourth capture time.

6. The method of claim 1 , wherein the calculating includes calculating at a network management component, the network management component receives the first data packet identifier, the second data packet identifier, the first capture time, and the second capture time without disrupting the flow of the existing network traffic being measured for latency.

7. The method of claim 1 , further comprising:

sending the first capture time from the first probe to the second probe, the calculating includes calculating at the second probe.

8. The method of claim 1 , wherein the data packet is from a set of data packets captured from the existing network traffic, the calculating includes calculating based on a set of capture times associated with the set of data packets.

9. The method of claim 1 , wherein calculating the latency includes distributing the calculation between at least two of the first probe, the second probe, or a network management component.

10. The method of claim 9 , wherein the first probe calculates the latency for first type of existing network traffic and wherein the second probe calculates the latency for a second type of existing network traffic.

11. The method of claim 10 , wherein the first type of network traffic comprises outbound traffic for a first network device and wherein the second type of network traffic comprises outbound traffic for a second network device.

12. The method of claim 1 , wherein the first capture instruction is sent from a network management component.

13. The method of claim 1 , wherein the second capture instruction is sent from a network management component.

14. The method of claim 13 , wherein the first capture instruction is sent from a network management component.

15. The method of claim 1 , wherein the first or second capture instructions include one of a start capture time, a capture time window, an instruction for assigning a capture time, and a reporting instruction.

16. An apparatus for measuring a latency of at least a portion of a data network, comprising:

a first probe connected to the data network and configured to capture a data packet from existing network traffic according to a first capture instruction, the first probe being configured to assign a first capture time corresponding to a time of capture by the first probe;

a second probe connected to the data network and configured to capture the data packet from the existing network traffic according to a second capture instruction, the second probe being configured to assign a second capture time corresponding to a time of capture by the second probe; and

a time synchronization server configured to periodically synchronize a time clock of the first probe with a time clock of the second probe, the frequency with which the synchronization occurs is increased or decreased based upon sensitivity to variations in timing of communications over the data network.

17. The apparatus of claim 16 , wherein the first probe is configured to send and receive a data packet identifier associated with the captured data packet without disrupting the flow of existing network traffic being measured for latency, the data packet identifier corresponds with the first capture time.

18. The apparatus of claim 16 , wherein the first probe is configured to receive the second capture time from the second probe, the first probe is configured to calculate the latency of the portion of the data network using the first capture time and the second capture time.

19. The apparatus of claim 18 , wherein the second probe is configured to receive the first capture time from the first probe, the second probe is configured to calculate the latency of the portion of the data network using the first capture time and the second capture time.

20. The apparatus of claim 16 , wherein a network management component is configured to receive the first capture time from the first probe and the second capture time from the second probe, the network management component is configured to calculate the latency of the portion of the data network using the first capture time and the second capture time, the network management component is configured to communicate with the first and second probes without disrupting the flow of existing network traffic being measured for latency.

21. The apparatus of claim 16 , wherein a network management component is configured to receive the first capture time based on the first probe and the second capture time from the second probe, the network management component is configured to calculate the latency of the portion of the data network based on the first capture time and the second capture time, the network management component, first probe, second probe, and time synchronization server are integrated into a single device.

22. The apparatus of claim 16 , further comprising a network management component configured to issue the first capture instruction specifying a device to receive the first capture time and the second capture instruction specifying the device to receive the second capture time.

23. The apparatus of claim 16 , wherein the first or second capture instructions include one of a start capture time, a capture time window, an instruction for assigning a capture time, and a reporting instruction.

Assignments (5)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Apr 29, 2008
From: QOVIA, INC.
To: CISCO SYSTEMS, INC.
Reel/Frame 020880/0163 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Apr 25, 2008
From: CISCO SYSTEMS, INC.
To: CISCO TECHNOLOGY, INC.
Reel/Frame 020860/0257 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Dec 10, 2007
From: QOVIA, INC.
To: CISCO SYSTEMS, INC.
Reel/Frame 020222/0403 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Dec 6, 2007
From: BECKER, DANIEL L.; LIZAMBRI, TODD J.; SHIM, CHOON B.; YU, XIANG
To: QOVIA, INC.
Reel/Frame 020207/0988 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Dec 6, 2007
From: BECKER, DANIEL L.; LIZAMBRI, TODD J.; SHIM, CHOON B.; YU, XIANG
To: QOVIA, INC.
Reel/Frame 020208/0177 →
Continuity (1)
Related Publication 20080247331A1 · Oct 9, 2008