Early generation of acknowledgements for flow control

• US 20050060426A1
• Filed: 07/28/2004
• Published: 03/17/2005
• 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.
• Granted Patent: US 7,698,453 B2
• Time in Patent Office: Days
• US Class Current: 709/238
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04L 43/08 Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
• 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 handling retransmission and acknowledgements of data packets transmitted from a sender to a recipient over a network, the method comprising:

receiving data packets from the sender;

transmitting the received data packets downstream to the recipient;

pre-acknowledging the received data packets by sending acknowledgments to the sender before receiving acknowledgements from a downstream entity for the data packets; and

controlling the flow of data packets received from the sender.

2. The method of claim 1, further comprising:

retaining a copy of the transmitted data packets until acknowledged as received from a downstream entity.

3. The method of claim 1, wherein each data packet is pre-acknowledged only after the data packet is transmitted downstream to the recipient.

4. The method of claim 1, wherein controlling the flow of data packets received from the sender comprises sending a packet to the sender, wherein the packet includes a TCP window having a size that is set to allow the sender to transmit a desired number of packets.

5. The method of claim 4, wherein the size of the TCP window is set to zero to disallow additional data packets from the sender.

6. The method of claim 1, wherein controlling the flow of data packets received from the sender comprises skipping a predetermined fraction of the acknowledgements sent to the sender.

7. The method of claim 1, wherein the data packets are sent over the network using the TCP/IP protocol.

8. A method for pre-acknowledging data packets sent over a network connection, the method comprising:

intercepting a data packet from a sender to a recipient;

transmitting the data packet to the recipient;

retaining a copy of the transmitted data packet;

sending an acknowledgement to the sender for the data packet;

determining whether the data packet has been delivered to the recipient or has been lost;

retransmitting the data packet if the data packet has been determined lost;

discarding the data packet if the data packet has been determined delivered; and

controlling the flow of additional packets sent by the sender.

9. The method of claim 8, wherein the acknowledgement for the data packet is sent to the sender only after the data packet is transmitted to the recipient.

10. The method of claim 8, wherein controlling the flow of additional packets comprises sending a packet to the sender, wherein the packet includes a TCP window having a size that is set to allow the sender to transmit a desired number of packets.

11. The method of claim 10, wherein the size of the TCP window is set to zero to disallow additional data packets from the sender.

12. The method of claim 8, wherein controlling the flow of additional packets comprises using a TCP delayed ACK mechanism.

13. The method of claim 8, wherein the data packet is sent over the network connection using the TCP/IP protocol.

14. The method of claim 8, wherein the data packet is intercepted before a high-loss link in the network connection.

15. The method of claim 8, wherein the data packet is intercepted at a point in the network connection having a bandwidth mismatch, with a lower bandwidth downstream of the point of interception.

16. The method of claim 8, wherein the data packet is intercepted at a point in the network having a latency transition.

17. In a flow control module communicatively coupled via a network between a sender and a recipient, a method of terminating the sender'"'"'s connection with the recipient, the method comprising:

a step for pre-acknowledging packets received by the flow control module from the sender so that the sender operates as if the pre-acknowledged packets have been received by the recipient;

a step for handling retransmission to the recipient of any lost packets as needed; and

a step for controlling the flow of packets transmitted by the sender.

18. A computer program product for handling retransmission and acknowledgements of data packets transmitted from a sender to a recipient over a network, the computer program product comprising a computer-readable medium containing computer program code for performing the operations:

receiving data packets from the sender;

transmitting the received data packets downstream to the recipient;

pre-acknowledging the received data packets by sending acknowledgments to the sender before receiving acknowledgements from a downstream entity for the data packets; and

controlling the flow of data packets received from the sender.

19. The computer program product of claim 18, the computer program code further for performing the operation:

retaining a copy of the transmitted data packets until acknowledged as received from a downstream entity.

20. The computer program product of claim 18, wherein each data packet is pre-acknowledged only after the data packet is transmitted downstream to the recipient.

21. The computer program product of claim 18, wherein controlling the flow of data packets received from the sender comprises sending a packet to the sender, wherein the packet includes a TCP window having a size that is set to allow the sender to transmit a desired number of packets.

22. The computer program product of claim 21, wherein the size of the TCP window is set to zero to disallow additional data packets from the sender.

23. The computer program product of claim 18, wherein controlling the flow of data packets received from the sender comprises skipping a predetermined fraction of the acknowledgements sent to the sender.

24. The computer program product of claim 18, wherein the data packets are sent over the network using the TCP/IP protocol.

25. A computer program product for pre-acknowledging data packets sent over a network connection, the computer program product comprising a computer-readable medium containing computer program code for performing the operations:

intercepting a data packet from a sender to a recipient;

transmitting the data packet to the recipient;

retaining a copy of the transmitted data packet;

sending an acknowledgement to the sender for the data packet;

determining whether the data packet has been delivered to the recipient or has been lost;

retransmitting the data packet if the data packet has been determined lost;

discarding the data packet if the data packet has been determined delivered; and

controlling the flow of additional packets sent by the sender.

26. The computer program product of claim 25, wherein the acknowledgement for the data packet is sent to the sender only after the data packet is transmitted to the recipient.

27. The computer program product of claim 25, wherein controlling the flow of additional packets comprises sending a packet to the sender, wherein the packet includes a TCP window having a size that is set to allow the sender to transmit a desired number of packets.

28. The computer program product of claim 27, wherein the size of the TCP window is set to zero to disallow additional data packets from the sender.

29. The computer program product of claim 25, wherein controlling the flow of additional packets comprises using a TCP delayed ACK mechanism.

30. The computer program product of claim 25, wherein the data packet is sent over the network connection using the TCP/IP protocol.

31. The computer program product of claim 25, wherein the data packet is intercepted before a high-loss link in the network connection.

32. The computer program product of claim 25, wherein the data packet is intercepted at a point in the network connection having a bandwidth mismatch, with a lower bandwidth downstream of the point of interception.

33. The computer program product of claim 25, wherein the data packet is intercepted at a point in the network having a latency transition.

34. A flow control module for handling retransmission and acknowledgements of data packets transmitted from a sender to a recipient over a network, the flow control module comprising:

a network interface for receiving data packets from the sender and transmitting data packets to the recipient;

a preack module configured to send an early acknowledgement to the sender for data packets received therefrom before receiving an acknowledgement from a downstream entity for the data packets; and

a memory coupled to the network interface, the memory configured to store data packets until acknowledged as received by a downstream entity;

an overflow control module for controlling the flow of packets received from the sender.

35. The flow control module of claim 34, wherein the network interface retransmits lost data packets.

36. The flow control module of claim 35, wherein the preack module sends an early acknowledgement for each data packet only after the network interface transmits the data packet to the recipient.

37. The flow control module of claim 34, wherein the overflow control module controls the flow by sending a packet to the sender, wherein the packet includes a TCP window having a size that is set to allow the sender to transmit a desired number of packets.

38. The flow control module of claim 37, wherein the size of the TCP window is set to zero to disallow additional data packets from the sender.

39. The flow control module of claim 34, wherein the overflow control module controls the flow by skipping a predetermined fraction of the acknowledgements sent to the sender.

40. The flow control module of claim 34, wherein the data packets are sent over the network using the TCP/IP protocol.