Wavefront detection and disambiguation of acknowledgments

• US 7,616,638 B2
• Filed: 07/28/2004
• Issued: 11/10/2009
• Est. Priority Date: 07/29/2003
• Status: Active Grant

• Current Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Original Assignee: Orbital Data Corporation (Cloud Software Group)
• Inventors: Samuels, Allen R., Sutter, Paul G.
• Primary Examiner(s): Sheikh; Ayaz R.
• Assistant Examiner(s): Weidner; Timothy J
• Application Number:
  US10/902,493
• Publication Number:
  US 20050058131A1
• Time in Patent Office: 1,931 Days
• Field of Search: None
• US Class Current: 370/394
• CPC Class Codes: H04L 41/00 Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/34 ensuring sequence integrity, e.g. using sequence numbers
• CPC Class Codes: H04L 67/2876 Pairs of inter-processing entities at each side of the network, e.g. split proxies
• CPC Class Codes: H04L 67/56 Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54
• 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 69/166 IP fragmentation; TCP segmentation

Abstract

One or more flow control modules, implemented on various types of network topologies, provide a number of functionalities for controlling the flow of IP packets (such as TCP/IP packets) over a network connection. The flow control modules may be implemented within a sender and/or receiver or may be deployed into a network as a separate device without requiring significant additional resources.

Claims

1. A method for communicating with a remote system using Internet Protocol (IP) via a computer network, the method comprising:

transmitting, by a flow control module configured on a device, a data packet to the remote system;

retransmitting, by the flow control module, the data packet to the remote system;

maintaining, by the flow control module, a transmit number identifying each transmission of the data packet;

receiving, by the flow control module, an acknowledgement packet indicating that the data packet was received by the remote system, the acknowledgement packet identifying the transmit number in an IP identification (ID) field with a predetermined bit reversed for one of the transmission or the retransmission of the data packet; and

associating, by the flow control module, the transmit number in the acknowledgement packet with either the transmission or the retransmission of the data packet, based on the transmit number identified via the IP identification field in the acknowledgement packet, thereby determining whether the transmission or the retransmission of the data packet was received and acknowledged by the remote system.

2. The method of claim 1, further comprising:

presuming, by the flow control module, lost any data packets that (1) have not been acknowledged and (2) were transmitted before the acknowledged transmission or retransmission of the data packet; and

retransmitting, by the flow control module, the presumed lost data packets.

3. The method of claim 1, wherein the transmission or the retransmission is identified in the acknowledgement packet as a function of the transmit number.

4. The method of claim 3, wherein the transmit number is a time stamp.

5. The method of claim 3, wherein the data packet conforms to the TCP/IP protocol.

6. The method of claim 5, wherein the transmit number of the transmitted or retransmitted data packet is included in the IP ID field of the acknowledgement packet with a most significant bit reversed.

7. The method of claim 1, wherein the associating is performed in a flow control module coupled to a sender sending data packets to the remote system.

8. The method of claim 1, wherein transmitting the data packet to the remote system further comprises transmitting the data packet with a sequence ID;

and wherein retransmitting the data packet to the remote system further comprises retransmitting the data packet with the sequence ID with a predetermined bit reversed.

9. The method of claim 1, wherein transmitting the data packet to the remote system further comprises transmitting the data packet with a first sequence ID;

and wherein retransmitting the data packet to the remote system further comprises retransmitting the data packet with a second sequence ID that is a predetermined function of the first sequence ID.

10. A method for transmitting data packets to a receiver over a network, the method comprising:

transmitting, by a flow control module configured on a device, a plurality of data packets to the receiver;

retransmitting, by the flow control module, a number of transmitted data packets responsive to an indication that the number of transmitted data packets were not received by the receiver;

maintaining, by the flow control module, a unique transmit number for each instance of a transmitted or retransmitted data packet;

receiving, by the flow control module, acknowledgements indicating that at least some of the data packets have been received, acknowledgements comprising the unique transmit number in the IP identifier (ID) field with a predetermined bit reversed for one of the transmission or the retransmission of the data packet; and

disambiguating, by the flow control module, the received acknowledgements to determine for each ambiguous acknowledgement the instance of transmitted or retransmitted data packet to which the ambiguous acknowledgement relates.

11. The method of claim 10, further comprising:

for each received acknowledgment, presuming, by the flow control module, lost any data packets that were transmitted before the acknowledged data packet but not yet acknowledged as received; and

retransmitting the presumed lost data packets.

12. The method of claim 10, further comprising:

determining, by the flow control module, whether transmitted data packets should be retransmitted; and

retransmitting, by the flow control module, data packets responsive to the determining.

13. The method of claim 10, wherein the transmitted and retransmitted data packets include the transmit number, and wherein the received acknowledgements include identifying information that comprises a function of the transmit number.

14. The method of claim 13, wherein the transmit number is a time stamp.

15. The method of claim 13, wherein the data packets conform to the TCP/IP protocol.

16. The method of claim 15, wherein the transmit number of the transmitted or retransmitted data packet is included in an IP ID field of a packet of the acknowledgements with a most significant bit reversed.

17. A computer readable medium for communicating with a remote system using Internet Protocol (IP) via a computer network, the computer-readable medium containing computer program code for instructing a flow control module on a device to perform the operations:

transmitting a data packet to the remote system;

retransmitting the data packet to the remote system;

maintaining a transmit number identifying each transmission of the data packet;

receiving an acknowledgement packet indicating that the data packet was received by the remote system, the acknowledgement packet identifying the transmit number in an IP identification (ID) field with a predetermined bit reversed for one of the transmission or the retransmission of the data packet; and

associating the transmit number in the acknowledgement packet with either the transmission or the retransmission of the data packet, based on the transmit number identified via the IP identification field in the acknowledgement packet, thereby determining whether the transmission or the retransmission of the data packet was received and acknowledged by the remote system.

18. The computer readable medium of claim 17, the computer program code further for performing the operations:

presuming lost any data packets that (1) have not been acknowledged and (2) were transmitted before the acknowledged transmission or retransmission of the data packet; and

retransmitting the presumed lost data packets.

19. The computer readable medium of claim 17, wherein the transmission or the retransmission is identified in the acknowledgement packet as a function of the transmit number.

20. The computer readable medium of claim 19, wherein the transmit number is a time stamp.

21. The computer readable medium of claim 19, wherein the data packets conform to the TCP/IP protocol.

22. The computer readable medium of claim 21, wherein the transmit number of the transmitted or retransmitted data packet is included in an IP ID field of the acknowledgement packet with a most significant bit reversed.

23. The computer readable medium of claim 17, wherein the associating is performed in a flow control module coupled to a sender sending data packets to the remote system.

24. A computer readable medium for transmitting data packets to a receiver over a network, the computer-readable medium containing computer program code for instructing a flow control module on a device to perform the operations:

transmitting a plurality of data packets to the receiver;

retransmitting a number of transmitted data packets responsive to an indication that the number of transmitted data packets were not received by the receiver;

maintaining a unique transmit number for each instance of a transmitted or retransmitted data packet;

receiving acknowledgements indicating that at least some of the data packets have been received, acknowledgements comprising the unique transmit number in the IP identifier (ID) field with a predetermined bit reversed for one of the transmission or the retransmission of the data packet; and

disambiguating the received acknowledgements to determine for each ambiguous acknowledgement the instance of transmitted or retransmitted data packet to which the ambiguous acknowledgement relates.

25. The computer readable medium of claim 24, the computer program code further performing the operations:

for each received acknowledgment, presuming lost any data packets that were transmitted before the acknowledged data packet but not yet acknowledged as received; and

retransmitting the presumed lost data packets.

26. The computer readable medium of claim 24, the computer program code further performing the operations:

determining whether transmitted data packets should be retransmitted; and

retransmitting data packets responsive to the step for determining.

27. The computer readable medium of claim 24, the received acknowledgements include identifying information that comprises a function of the unique transmit number.

28. The computer readable medium of claim 27, wherein the unique transmit number is a time stamp.

29. The computer readable medium of claim 27, wherein the data packets conform to the TCP/IP protocol.

30. The computer readable medium of claim 29, wherein the identifying information in an acknowledgement packet associated with each of the acknowledgements comprises the unique transmit number of the transmitted or retransmitted data packet in an IP ID field of the acknowledgement packet with a most significant bit reversed.