Methods and apparatus to determine network delay with location independence from retransmission delay and application response time

1. A method for monitoring retransmission delay in a communication network comprising:

monitoring, via a network monitoring device, an exchange of data segments between at least a first network device and a second network device;

determining, via the network monitoring device, the first network device failed to receive at least one lost data segment from the second network device causing the second network device to retransmit the at least one lost data segment;

marking, via the network monitoring device, a retransmission delay start time when the second network device transmits a latest acknowledged data segment relative to retransmission of the at least one lost data segment;

marking, via the network monitoring device, a retransmission delay end time when the second network device retransmits the at least one lost data segment to the first network device; and

determining a difference between the retransmission delay start time and the retransmission delay end time to yield a total retransmission delay.

2. The method of claim 1 , further comprising:

displaying, via a display of the network monitoring device, the total retransmission delay.

3. The method of claim 1 , wherein determining, via the network monitoring device, the first network device failed to receive at least one lost data segment from the second network device comprises:

determining the second network device retransmits the at least one lost data segment.

4. The method of claim 1 , wherein determining, via the network monitoring device, the first network device failed to receive at least one lost data segment from the second network device comprises:

determining the second network device receives an acknowledgement from the first network device having the same value as a prior acknowledgement.

5. The method of claim 1 , wherein the first network device and the second network device include at least one of a client and a server.

6. The method of claim 1 , wherein the first network device and the second network device exchange data segments via a Transmission Control Protocol (TCP).

7. A network monitoring device, comprising:

one or more network interfaces adapted to communicate in a communication network;

a processor adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to:

monitor an exchange of data segments between at least a first network device and a second network device;

determine the first network device failed to receive at least one lost data segment from the second network device causing the second network device to retransmit the at least one lost data segment;

mark a retransmission delay start time when the second network device transmits a latest acknowledged data segment relative to retransmission of the at least one lost data segment;

mark, via the network monitoring device, a retransmission delay end time when the second network device retransmits the at least one lost data segment to the first network device; and

determine a difference between the retransmission delay start time and the retransmission delay end time to yield a total retransmission delay.

8. The network monitoring device of claim 7 , further comprising:

a display that displays the total retransmission delay.

9. The network monitoring device of claim 7 , wherein the first network device and the second network device include at least one of a server device and a client device.

10. The network monitoring device of claim 7 , wherein, the process, when executed to determine the first network device failed to receive at least one lost data segment from the second network device, is further operable to:

determine the second network device retransmits the at least one lost data segment.

11. The network monitoring device of claim 7 , wherein, the process, when executed to determine the first network device failed to receive at least one lost data segment from the second network device, is further operable to:

determine the second network device receives an acknowledgement from the first network device having the same value as a prior acknowledgement.

12. A method for monitoring application response time in a communication network comprising:

monitoring, via a network monitoring device, an exchange of data between at least a first network device and a second network device;

determining, via the network monitoring device, a network round trip time from a time difference between transmission of an initial data signal from the first network device to the second network device and receipt, by the first network device, of a corresponding acknowledgement data signal from the second network device;

marking, via the network monitoring device, an application response start time when a first data segment is transmitted from the first network device to the second network device;

marking, via the network monitoring device, an application response end time when a second data segment from the second network device is received by the first network device;

determining, via the network monitoring device, a difference between the application response start time and the application response end time to yield an application response time; and

determining, via the network monitoring device, a difference between the application response time and the network round trip time to yield a total application response time.

13. The method of claim 12 , further comprising:

displaying, via a display of the network monitoring device, the total application response time.

14. The method of claim 12 , wherein the first network device and the second network device include at least one of a client and a server.

15. The method of claim 12 , wherein the first data segment is a requesting data segment and the second data segment is a responding data segment.

16. A network monitoring device, comprising:

one or more network interfaces adapted to communicate in a communication network;

a processor adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to:

monitor an exchange of data between at least a first network device and a second network device;

determine a network round trip time from a time difference between transmission of an initial data signal from the first network device to the second network device and receipt, by the first network device, of a corresponding acknowledgement data signal from the second network device;

mark an application response start time when a requesting data segment is transmitted from the first network device to the second network device;

mark an application response end time when a responding data segment from the second network device is received by the first network device;

determine a difference between the application response start time and the application response end time to yield an application response time; and

determine a difference between the application response time and the network round trip time to yield a total application response time.

17. The network monitoring device of claim 16 further comprising:

a display that displays the total application response time.

18. The network monitoring device of claim 16 , wherein the first network device and the second network device include at least one of a server device and a client device.

19. A tangible, non-transitory, computer-readable media having software encoded thereon, the software, when executed by a processor, operable to:

monitor an exchange of data segments between at least a first network device and a second network device;

determine a network round trip time from a time difference between transmission of an initial data signal from the first network device to the second network device and receipt, by the first network device, of a corresponding acknowledgement data signal from the second network device;

determine the first network device failed to receive at least one lost data segment from the second network device causing the second network device to retransmit the at least one lost data segment;

mark a retransmission delay start time when the second network device transmits a latest acknowledged data segment relative to retransmission of the at least one lost data segment;

mark, via the network monitoring device, a retransmission delay end time when the second network device retransmits the at least one lost data segment to the first network device;

determine a difference between the retransmission delay start time and the retransmission delay end time to yield a total retransmission delay;

mark an application response start time when a first data segment request is transmitted from the first network device to the second network device;

mark an application response end time when a second data segment response from the second network device is received by the first network device;

determine a difference between the application response start time and the application response end time to yield an application response time;

determine a difference between the application response time and the network round trip time to yield a total application response time; and

display the total retransmission delay and the total application response time.