Method for transporting data and computer network for carrying out said method

• US 6,405,236 B1
• Filed: 09/09/1999
• Issued: 06/11/2002
• Est. Priority Date: 01/09/1998
• Status: Expired due to Term

• Current Assignee: Callstat Solutions LLC (Jeffrey M. Gross)
• Original Assignee: Hilf! GmbH Microcomputer- Consulting
• Inventors: Nieratschker, Karl
• Primary Examiner(s): Coulter, Kenneth R.
• Application Number:
  US09/380,793
• Time in Patent Office: 1,006 Days
• Field of Search: 709/200, 709/230, 714/55, 713/600, 713/500
• US Class Current: 709/200
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/164 Adaptation or special uses of UDP protocol
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols
• CPC Class Codes: H04L 69/326 in the transport layer [OSI layer 4] H04L69/16 takes precedence
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

The invention relates to a method for transporting data between application programs assigned to different interconnected computers of a computer network, the method being based on a connectionless and packet-oriented transport method capable of transporting the data packets between application programs. When a data packet is transmitted from the application program of a source computer to that of the destination computer, a retransmission timer (RT) and an acknowledgement timer (QT) are initiated. After the data packet has been initially received, it is transferred to the application program of the destination computer. Each time the destination computer receives a data packet, an acknowledgement packet is transmitted back to the source computer, confirming receipt of the data packet. In the event that receipt has still not been registered after a predetermined acknowledgement waiting period, the application program of the source computer is informed that receipt of the data packet has not been acknowledged within the acknowledgement waiting period. A message is also sent when the acknowledgement packet is received on time. The method is particularly suitable for distributed real-time systems. The invention also relates to a computer network for implementing the method.

Claims

1. A method for transporting data between application programs assigned to different interconnected computers of a computer network, the method being based on the connectionless and packet-oriented transport protocol UDP/IP, which is capable of transporting data packets between application programs assigned to any computers of said network, and comprising the steps:

initiating in a source computer a retransmission timer timing out after a predetermined retransmission waiting period and an acknowledgement timer timing out after a predetermined acknowledgement waiting period when a data packet is transmitted from the application program of the source computer to the application program of a destination computer,

transferring the data packet, after it has been initially received by the destination computer, to the application program of the destination computer,

transmitting an acknowledgement packet to the source computer, each time the destination computer receives a data packet, to confirm receipt of the data packet,

retransmitting the data packet to the destination computer and reinitiating the retransmission timer in the event that receipt of the acknowledgement packet has still not been registered by the source computer on timeout of the predetermined retransmission waiting period,

informing the application program of the source computer that receipt of the data packet sent has not been acknowledged within the acknowledgement waiting period if receipt of the acknowledgement packet has still not been registered on timeout of the predetermined acknowledgement waiting period in the source computer; and

informing the application program of the source computer that the data packet has been acknowledged within the acknowledgement waiting period if receipt of an acknowledgment packet within the predetermined acknowledgement waiting period in the source computer is registered for the first time.

2. The method as set forth in claim 1 wherein said acknowledgement waiting period is set individual for each data packet to be transmitted, depending on the system timing requirements.

3. The method as set forth in claim 1 or 2 wherein said retransmission waiting period is set individual for each data packet to be transmitted.

4. The method as set forth in claim 1 wherein said retransmission and acknowledgement timers in said source computer comprise the same basic time unit.

5. The method as set forth in claim 4 wherein the system clock forms said basic time unit.

6. The method as set forth in claim 4 wherein said basic time unit is independent of said system clock and is defined by a separate timer.

7. The method as set forth in any of the claims 4 to 6 wherein on timeout of each basic time unit it is established whether said retransmission timer or said acknowledgement timer has timed out.

8. The method as set forth in claim 1 wherein if several acknowledgement packets arrive at said source computer for said same data packet sent by said source computer, the acknowledgement packets arriving after arrival of the first acknowledgement packet are rejected.

9. The method as set forth in claim 1 wherein if said transmitted data packet arrives at said destination computer multiply, the duplicates are rejected.

10. The method as set forth in claim 1 wherein a transmission data buffer area of said application program of said source computer is provided in said source computer for said data packet to be transmitted, said transmission data buffer area being that from which said data packet is transmitted.

11. The method as set forth in claim 10 wherein after transmission to said application program of said destination computer said data packet remains in said transmission data buffer area in said source computer until said acknowledgement packet sent by said destination computer arrives at said source computer, said data buffer area then being released instantly and asynchronously to said application program of said source computer for said application program of said source computer.

12. The method as set forth in claim 10 or 11 wherein said transmission data buffer area is instantly released on timeout of said acknowledgement timer.

13. The method as set forth in claim 1 wherein transmission of said data packet occurs asynchronously to timeout of said application program of said source computer.

14. The method as set forth in claim 1 wherein the received data packet is transferred to said application program of said destination computer asynchronous to timeout of said application program of said destination computer.

15. The method as set forth in claim 1 wherein the internet protocol IP is based on a link layer ensuring access to a transport medium connecting the computers of the network.

16. The method as set forth in claim 15 wherein said link layer is an Ethernet layer.

17. The method as set forth in claim 1 wherein between source computer and destination computer several data transport channels are provided.

18. The method as set forth in claim 17 wherein prior to transmission a vacant channel is selected and said data packet is then transmitted via said selected channel to said destination computer.

19. The method as set forth in claim 1 wherein between said computers of said network only a single data transport channel is provided.

20. The method as set forth in any of the claims 17 to 19 wherein it is assured that said data packets transmitted within a channel are received in the same sequence as they were transmitted.

21. The method as set forth in claim 1 wherein said individual computers of said network work real-time oriented.

22. The method as set forth in claim 21 wherein said individual computers each work with a real-time operating system.

23. The method as set forth in claim 1 wherein said acknowledgement waiting period is longer than said retransmission waiting period.

24. A computer network comprising different interconnected computers of a computer network which are capable of swapping data packets between application programs assigned to any computers of the network via the connectionless and packet-oriented transport protocol UDP/IP, each computer comprising:

means for monitoring the retransmission waiting period capable of being initiated when the computer, functioning as a source computer, sends a data packet from the application program of the computer to the application program of another computer functioning as the destination computer of the network, the means then sensing the time having passed since transmission of said data packet and timing out after a predetermined retransmission waiting period;

means for monitoring the acknowledgement waiting period capable of being initiated when the computer, functioning as a source computer, sends a data packet from the application program of the computer to the application program of another computer functioning as the destination computer of the network, the means then sensing the time having passed since initial transmission of the data packet and timing out after a predetermined acknowledgement waiting period;

means capable of transferring the packet to the application program of the computer after initial receipt of a data packet when said computer functions as a destination computer;

means capable of transmitting an acknowledgement packet confirming receipt to the source computer, having transmitted the data packet, every time a data packet is received, when said computer functions as a destination computer;

means capable of reinitiating the transmission of the data packet to the destination computer and the means for monitoring the retransmission waiting period when the computer functions as a source computer and receipt of the acknowledgement packet has not been registered by the computer on timeout of the predetermined retransmission waiting period; and

means capable of informing the application program of the computer—

when the computer functions as a source computer and receipt of the acknowledgement packet has not been registered in the computer on timeout of the predetermined acknowledgement waiting period—

that receipt of the transmitted data packet was not acknowledged within the acknowledgement waiting period, and which are capable of informing the application program of said computer that the data packet was acknowledged within the acknowledgement waiting period when receipt of an acknowledgement packet is initially registered within the predetermined acknowledgement waiting period in said computer.