System and method for robust communication via a non-reliable protocol

• US 20060056403A1
• Filed: 09/13/2004
• Published: 03/16/2006
• Est. Priority Date: 09/13/2004
• Status: Abandoned Application

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Pleasant, Daniel L., Kailasam, Gopalakrishnan
• Application Number:
  US10/939,921
• Publication Number:
  US 20060056403A1
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock
• CPC Class Codes: H04J 3/0664 unidirectional timestamps
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 41/06 Management of faults, events, alarms or notifications
• CPC Class Codes: H04L 43/0829 Packet loss
• CPC Class Codes: H04L 43/0852 Delays
• CPC Class Codes: H04L 43/106 using time related information in packets, e.g. by adding timestamps

Abstract

A system and method are provided which enhance the robustness of non-reliable protocols, such as UDP. As described further below, according to at least one embodiment, a method is provided for improving the robustness of using non-reliable protocols, such as UDP, in applications in which small numbers of time-critical packets are transmitted. For instance, in a system of cooperating devices on a network, a device on a network may broadcast information about itself to the other devices. According to various embodiments described below, a combination of redundant re-transmissions of non-reliable protocol data packets and inclusion of timestamps in the non-reliable protocol data packets is used to improve the robustness of applications that rely on the non-reliable protocol data packets.

Claims

1. A method comprising:

synchronizing local clocks of a plurality of devices that are communicatively coupled to a communication network;

communicating from one of the plurality of devices at least one data packet via a non-reliable protocol over the communication network, wherein the at least one data packet includes a timestamp therein based on the local clock of the device from which the at least one packet is communicated; and

after a defined delay, re-communicating the at least one data packet via the non-reliable over the communication network, wherein the at least one data packet again includes the timestamp.

2. The method of claim 1 wherein the non-reliable protocol is user datagram protocol (UDP).

3. The method of claim 1 wherein said communicating comprises broadcasting said at least one data packet over the communication network.

4. The method of claim 1 further comprising:

after another defined delay, re-communicating the at least one data packet via the non-reliable protocol over the communication network, wherein the at least one data packet again includes the timestamp.

5. The method of claim 1 wherein said synchronizing uses one selected from the group consisting of:

IEEE 1588, Network Time Protocol (NTP), and global positioning system (GPS).

6. The method of claim 1 wherein said synchronizing comprises:

said plurality of devices interacting to actively synchronize their local clocks.

7. The method of claim 1 further comprising:

at least one of said plurality of devices receiving said at least one data packet at least once from said communicating and said re-communicating.

8. The method of claim 7 further comprising:

said at least one of said plurality of devices receiving said at least one data packet and determining if it can perform a time-sensitive operation relative to the timestamp included in the at least one data packet.

9. A method comprising:

synchronizing local clocks of a plurality of devices that are communicatively coupled to a communication network;

forming a first data packet of a non-reliable protocol, said first data packet including a first timestamp therein based on the local clock of a first one of the plurality of devices;

communicating from the first one of the plurality of devices the first data packet over the communication network via the non-reliable protocol; and

re-communicating, via the non-reliable protocol, the first data packet over the communication network at least once after at least one defined time delay.

10. The method of claim 9 wherein the first data packet is a user datagram protocol (UDP) data packet.

11. The method of claim 9 wherein said communicating comprises broadcasting said first data packet over the communication network.

12. The method of claim 9 wherein said re-communicating comprises:

re-communicating the first data packet a plurality of times, each of said plurality of times separated by a time delay.

13. The method of claim 9 wherein the first data packet includes the first timestamp when re-communicated in said re-communicating step.

14. The method of claim 9 wherein said synchronizing uses one selected from the group consisting of:

IEEE 1588, Network Time Protocol (NTP), and global positioning system (GPS).

15. The method of claim 9 further comprising:

at least one of said plurality of devices receiving said first data packet at least once as a result of said communicating and said re-communicating.

16. The method of claim 15 further comprising:

said at least one of said plurality of devices receiving said first data packet and determining if it can perform a time-sensitive operation relative to the timestamp included in the at least one data packet.

17. The method of claim 16 wherein said first data packet further includes information identifying an event, and wherein said determining if it can perform a time-sensitive operation comprises determining a time-sensitive operation to perform responsive to said identified event.

18. A method comprising:

synchronizing local clocks of a plurality of devices that are communicatively coupled to a communication network;

transmitting from a first of the plurality of devices a user datagram protocol (UDP) data packet over the communication network a plurality of times separated by at least one defined time delay, wherein a first timestamp is included in the UDP data packet each of the plurality of times the UDP data packet is transmitted; and

receiving at least once by at least a second of the plurality of devices the UDP data packet, wherein the at least a second of the plurality of devices evaluates the timestamp to determine if it can perform a time-sensitive action responsive to the received UDP data packet.

19. The method of claim 18 wherein said transmitting comprises broadcasting said UDP data packet over the communication network.

20. The method of claim 18 wherein said synchronizing uses one selected from the group consisting of:

IEEE 1588, Network Time Protocol (NTP), and global positioning system (GPS).

21. A system comprising:

a plurality of devices that are communicatively coupled to a communication network;

each of the plurality of devices include a local clock, wherein the local clocks are actively synchronized;

at least a first one of the plurality of devices generates a message to be communicated over the communication network to at least a second one of the plurality of devices, wherein the at least a second one of the plurality of devices includes an application that is operable to receive the message and responsive to the message perform a time-sensitive action;

wherein the at least a first one of the plurality of devices forms the generated message into at least one non-reliable protocol data packet that includes a timestamp based on the local clock of the at least a first one of the plurality of devices, and wherein the at least a first one of the plurality of devices communicates the at least one non-reliable protocol data packet a plurality of times separated by at least one defined time delay.

22. The system of claim 21 wherein the at least one non-reliable protocol data packet is a user datagram protocol (UDP) data packet.

23. The system of claim 21 wherein the time-sensitive action comprises taking a measurement.

24. The system of claim 23 wherein said taking a measurement comprises taking a measurement of a signal output by said at least a first one of the plurality of devices.

25. The system of claim 21 wherein said message identifies an event, and wherein said at least a second one of the plurality of devices is configured to determine said time-sensitive action that it is to perform responsive to the identified event.