Method and apparatus for round trip delay KPI monitoring in live network using user plane probe session

1. A method for apportioning delays of a plurality of network elements on a round trip path in a network, said method comprising the steps of:

Transmitting, at a user element, a loopback packet having a probe session indicator along said round trip path,

wherein said roundtrip path reaches a core network element, and

wherein the loopback packet is received at said user element after completing said roundtrip path;

determining at each of said plurality of network elements on said round trip path the presence of said probe session indicator, and

responsive to the presence of said probe session indicator, logging a first timestamp corresponding to the time of receipt of said loopback message, and a second timestamp corresponding to the time of retransmission of said loopback message; and

transmitting at each of said plurality of network elements said first and second timestamps to a network management system.

2. A method for apportioning delays as claimed in claim 1 wherein said determining the presence of said probe session indicator is determined in an application layer of said network element.

3. A method for apportioning delays as claimed in claim 2 wherein said indicator comprises an International Mobile Subscriber Identity (IMSI) identifying a probe session.

4. A method for apportioning delays as claimed in claim 2 wherein said probe session indicator comprises a probe bit identifying a probe session.

5. A method for apportioning delays as claimed in claim 4 wherein

said probe bit comprises a bit in a message header of said loopback message.

6. A method for apportioning delays as claimed in claim 1 wherein

said loopback message comprises a modified Internet Control Message Protocol (ICMP) PING message, and wherein said loopback message has identical uplink and downlink paths.

7. A method performed by an intermediate network device, the method comprising:

receiving, at the intermediate network device, a message having a probe session indicator,

wherein the message is a loopback message having an uplink path originating from a user element that reaches a network core element and a downlink path returning the loopback message to the user element;

determining that the message includes the probe session indicator;

based on the message including the probe session indicator:

generating a first timestamp corresponding to a time of receipt of the message;

generating a second timestamp corresponding to a time of transmission of the message, and

transmitting the first timestamp and the second timestamp to a first device; and

transmitting the message to a second device.

8. The method of claim 7 , wherein said loopback message traverses the same intermediate nodes on the uplink path and downlink path.

9. The method of claim 7 , wherein the first device is a network management system.

10. The method of claim 7 , wherein determining that the message includes the probe session indicator is performed at an application layer of the intermediate network device.

11. The method of claim 7 , wherein the probe session indicator comprises an International Mobile Subscriber Identity (IMSI) identifying a probe session.

12. The method of claim 7 , wherein the probe session indicator comprises a probe bit identifying a probe session.

13. The method of claim 7 , wherein the message comprises a modified Internet Control Message Protocol (ICMP) PING message.

14. An intermediate network device comprising:

a memory device; and

a processor in communication with the memory device, the processor being configured to:

receive a message having a probe session indicator,

wherein the message is a loopback message having an uplink path originating from a user element that reaches a network core element and a downlink path returning the loopback message to the user element;

determine that the message includes the probe session indicator;

based on the message including the probe session indicator:

generate a first timestamp corresponding to a time of receipt of the message;

generate a second timestamp corresponding to a time of transmission of the message, and

transmit the first timestamp and the second timestamp to a first device; and

transmit the message to a second device.

15. The intermediate network device of claim 14 , wherein said loopback message traverses the same intermediate nodes on the uplink path and downlink path.

16. The intermediate network device of claim 14 , wherein the first device is a network management system.

17. The intermediate network device of claim 14 , wherein determining that the message includes the probe session indicator is performed by the processor at an application layer of the intermediate network device.

18. The intermediate network device of claim 14 , wherein the probe session indicator comprises an International Mobile Subscriber Identity (IMSI) identifying a probe session.

19. The intermediate network device of claim 14 , wherein the probe session indicator comprises a probe bit identifying a probe session.

20. The intermediate network device of claim 14 , wherein the message comprises a modified Internet Control Message Protocol (ICMP) PING message.