Method and system for determining one-way packet travel time using RTCP

• US 20080049635A1
• Filed: 08/25/2006
• Published: 02/28/2008
• Est. Priority Date: 08/25/2006
• Status: Abandoned Application

• Current Assignee: SBC Knowledge Ventures LP (AT&T, Inc.)
• Original Assignee: SBC Knowledge Ventures LP (AT&T, Inc.)
• Inventors: James, James, Smith, Wallace, Huang, Alexander
• Application Number:
  US11/510,852
• Publication Number:
  US 20080049635A1
• Time in Patent Office: Days
• US Class Current: 370/252
• 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
• CPC Class Codes: H04L 67/125 involving control of end-device applications over a network
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

A method of measuring a one-way packet travel time from a first communication system to a second communication system comprises receiving a Real-time Transport Control Protocol (RTCP) packet outputted by the second communication system. A Network Time Protocol (NTP) timestamp value is extracted from the RTCP packet, and a time value, T, is determined based on the NTP timestamp value. A Last Sender Report (LSR) value and a Delay since LSR (DLSR) value are extracted from the RTCP packet. A value L=T−LSR−DLSR is determined to measure the one-way packet travel time from the first communication system to the second communication system.

Claims

1. A method of measuring a one-way packet travel time from a first communication system to a second communication system, the method comprising:

receiving a Real-time Transport Control Protocol (RTCP) packet outputted by the second communication system;

extracting a Network Time Protocol (NTP) timestamp value from the RTCP packet;

determining a time value, T, based on the NTP timestamp value;

extracting a Last Sender Report (LSR) value from the RTCP packet;

extracting a Delay since LSR (DLSR) value from the RTCP packet; and

determining a value L=T−

LSR−

DLSR to measure the one-way packet travel time from the first communication system to the second communication system.

2. The method of claim 1 further comprising outputting the value L.

3. The method of claim 1 further comprising tuning a network based on the value L.

4. The method of claim 1 wherein the RTCP packet is outputted by the second communication system based on a previous RTCP packet that was sent from the first communication system to the second communication system

5. The method of claim 1 wherein the RTCP packet is to be sent to the first communication system.

6. The method of claim 1 wherein the first communication system is associated with a first party, wherein the second communication system is associated with a second party, and wherein said determining the value L=T−

LSR−

DLSR is performed by a third party other than the first party and the second party.

7. The method of claim 1 wherein said determining the value L=T−

LSR−

DLSR is performed by the first communication system.

8. The method of claim 1 wherein said receiving the RTCP packet is at a node that is not in a communication path between the second communication system and the first communication system.

9. The method of claim 1 wherein the time value, T, is determined based on a middle 32 bits of the NTP timestamp value.

10. A system for measuring a one-way packet travel time from a first communication system to a second communication system, the system comprising:

a receiver to receive a Real-time Transport Control Protocol (RTCP) packet outputted by the second communication system; and

a processor to extract a Network Time Protocol (NTP) timestamp value from the RTCP packet, the processor to determine a time value, T, based on the NTP timestamp value, the processor to extract a Last Sender Report (LSR) value from the RTCP packet, the processor to extract a Delay since LSR (DLSR) value from the RTCP packet, and the processor to determine a value L=T−

LSR−

DLSR to measure the one-way packet travel time from the first communication system to the second communication system.

11. The system of claim 10 wherein the RTCP packet is outputted by the second communication system based on a previous RTCP packet that was sent from the first communication system to the second communication system

12. The system of claim 10 wherein the RTCP packet is to be sent to the first communication system.

13. The system of claim 10 wherein the time value, T, is determined based on a middle 32 bits of the NTP timestamp value.

14. A computer-readable medium having computer-readable program code to cause a computer system to measure a one-way packet travel time from a first communication system to a second communication system by performing acts of:

receiving a Real-time Transport Control Protocol (RTCP) packet outputted by the second communication system;

extracting a Network Time Protocol (NTP) timestamp value from the RTCP packet;

determining a time value, T, based on the NTP timestamp value;

extracting a Last Sender Report (LSR) value from the RTCP packet;

extracting a Delay since LSR (DLSR) value from the RTCP packet; and

determining a value L=T−

LSR−

DLSR to measure the one-way packet travel time from the first communication system to the second communication system.

15. The computer-readable medium of claim 14 wherein the RTCP packet is outputted by the second communication system based on a previous RTCP packet that was sent from the first communication system to the second communication system

16. The computer-readable medium of claim 14 wherein the RTCP packet is to be sent to the first communication system.

17. The computer-readable medium of claim 14 wherein the first communication system is associated with a first party, wherein the second communication system is associated with a second party, and wherein said determining the value L=T−

LSR−

DLSR is performed by a third party other than the first party and the second party.

18. The computer-readable medium of claim 14 wherein said determining the value L=T−

LSR−

DLSR is performed by the first communication system.

19. The computer-readable medium of claim 14 wherein said receiving the RTCP packet is at a node that is not in a communication path between the second communication system and the first communication system.

20. The computer-readable medium of claim 14 wherein the time value, T, is determined based on a middle 32 bits of the NTP timestamp value.