TCP throughput control by imposing temporal delay

• US 8,379,515 B1
• Filed: 02/01/2007
• Issued: 02/19/2013
• Est. Priority Date: 02/01/2007
• Status: Active Grant

• Current Assignee: F5 Networks, Inc. (F5 Incorporated)
• Original Assignee: F5 Networks, Inc. (F5 Incorporated)
• Inventors: Mukerji, Arindum
• Primary Examiner(s): Rinehart, Mark
• Assistant Examiner(s): ONAMUTI, GBEMILEKE J
• Application Number:
  US11/670,410
• Time in Patent Office: 2,210 Days
• Field of Search: 370/229, 370/310, 370/395.4, 370/235, 370/217, 370/236, 370/230, 709/218, 709/217, 709/232
• US Class Current: 370/229
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04L 47/265 sent by intermediate network nodes
• CPC Class Codes: H04L 47/267 sent by the destination endpoint network streaming of media packets with control of the source by the destination H04L65/613
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 47/323 Discarding or blocking control packets, e.g. ACK packets
• CPC Class Codes: H04L 69/163 In-band adaptation of TCP data exchange; In-band control procedures

Abstract

A system, apparatus, and method are directed towards managing traffic over a network by imposing temporal delays in acknowledgments (ACKs). A Traffic Management Device (TMD), interposed between two network session end-points monitors a buffer of relayed packets. If the contents of the buffer exceed a threshold value, delays are imposed on sending of acknowledgements. If the buffer contents exceed the threshold, and the buffer'"'"'s contents are increasing, the delays may be increased. If the buffer'"'"'s contents are about at steady state, the acknowledgement delays may be decreased, or maintained at a current delay status. In one embodiment, if the sender is sending packets at a rate above a receiver'"'"'s ability to receive the packets, and the sender appears not to be decreasing its rate of transmission, an explicit congestion notification echo (ECE) may be sent to the sender.

Claims

1. A network device for managing a communications over a network, comprising:

a buffer for use in receiving and storing network packets; and

a management component that is programmed to perform actions, including;

receiving a network packet;

monitoring changes in an amount of content stored in the buffer;

selectively adjusting a delay for sending an acknowledgement (ACK) to the received network packet based on the monitored changes in the buffer, wherein selectively adjusting includes;

the management component determining that the contents of the buffer are above a threshold value, and determining that the contents of the buffer are increasing, and when both determinations are valid, then increasing the delay of sending the ACK to a sending network device of the received network packet;

the management component determining that the contents of the buffer are above a threshold value, and determining that the contents of the buffer are decreasing, and when both determinations are valid, then decreasing the delay of sending the ACK to the sending network device of the received network packet; and

selectively forwarding the network packet to a destination.

2. The network device of claim 1:

wherein the actions further including;

if the contents of the buffer are substantially increasing above a threshold value, and a round trip time for the sending network device is less than a round trip time for the destination, sending an explicit congestion notification (ECN) to the sending network device.

3. The network device of claim 1:

wherein selectively adjusting the delay further comprises adjusting the temporal delay using at least one of a ramp, or a step.

4. The network device of claim 1:

wherein selectively adjusting the delay further comprises adjusting the temporal delay based on a relationship between a round trip time for network packets for the sending network device, and a round trip time for network packets for the destination.

5. A method of managing a communications over a network, comprising:

receiving a network packet at an intermediate device interposed between a sending device and a receiving device;

determining a status of a buffer within the intermediate device and is configured for receiving the network packet;

when it is determined that the status of the buffer indicates that the buffer'"'"'s contents are increasing and it is determined that the buffer'"'"'s contents is above a threshold value, such that both determinations are valid, increasing a temporal delay for sending of an acknowledgement (ACK) to network packets received from the sending device;

when it is determined that the status of the buffer indicates that the buffer'"'"'s contents are decreasing and it is determined that the buffer'"'"'s contents is above the threshold value, such that both determinations are valid, decreasing a temporal delay for sending of an ACK to network packets received from the sending device; and

selectively sending the ACK based on the determined temporal delay and the buffer'"'"'s contents, in response to the received network packet.

6. The method of claim 5, further comprising, if the buffer is substantially full, dropping the received network packet, and inhibiting sending of the ACK to the dropped network packet.

7. The method of claim 5, further comprising:

if the status of the buffer indicates that the contents of the buffer are substantially increasing and is above a threshold value, and the sending device is transmitting network packets at a rate that is higher than the receiving device is consuming the network packets, then sending a congestion signal to the sending device.

8. The method of claim 5, further comprising:

if the status of the buffer indicates that the contents of the buffer is below the threshold value, then employing a current temporal delay for sending of the ACK to the sending device.

9. The method of claim 5, further comprising:

if the contents of the buffer are less than the threshold, moving the received network packet into the buffer; and

forwarding another network packet to the receiving device, wherein the other network packet is selected from the buffer based on a First-in/First-out mechanism.

10. The method of claim 5, further comprising:

if the status of the buffer indicates that the contents of the buffer are substantially increasing and is above a threshold value, and if the current temporal delays in ACKs is above another threshold associated with a retransmission timeout, then sending a congestion signal to the sending device.

11. The method of claim 5, wherein selectively sending the ACK affects a sending of another network packet by the sending device.

12. A non-transitory, computer-readable storage medium having machine-executable instructions for managing communications over a network, the machine-executable instructions when installed onto a network device interposed between a sending network device and a receiving network device enables the interposed network device to perform actions, comprising:

receiving a network packet from the sending network device;

when it is determined that a buffer'"'"'s contents are increasing and when it is also determined that the buffer'"'"'s contents is above a threshold value, selectively increasing a temporal delay for sending of an acknowledgement (ACK) to network packets received from the sending device;

when it is determined that the buffer'"'"'s contents are decreasing and when it is also determined that the buffer'"'"'s contents is above the threshold value, selectively decreasing a temporal delay for sending of an acknowledgement (ACK) to network packets received from the sending device; and

based on the temporal delay, selectively sending the ACK to the sending device.

13. The non-transitory, computer-readable storage medium of claim 12, wherein selectively decreasing or selectively increasing the temporal delay further comprises adjusting the temporal delay to approximately match a round trip time (RTT) for the sending device to an RTT of the receiving device.

14. The non-transitory, computer-readable storage medium of claim 12, wherein selectively decreasing or increasing the temporal delay further comprises employing at least one of a step or a ramp function.

15. The non-transitory, computer-readable storage medium of claim 12, wherein the interposed network device is configured to perform as at least one of a router, a proxy, a firewall, a load balancer, a gateway, a network address translation device, a port translator, or a traffic management device.

16. The non-transitory, computer-readable storage medium of claim 12, wherein selectively sending the ACK to the sending device further comprises, if the buffer is substantially full, dropping the received network packet, and inhibiting sending of the ACK to the received network packet.

17. A traffic management device (TMD) for enabling communications between at least one sending network device and a receiving network device, comprising:

a transceiver that receives packets from the sending network device destined for the receiving network device; and

a processor for executing instructions for selectively delaying sending of an acknowledgement (ACK) to the sending device in response to receiving a network packet, based, at least in part, on whether a buffer'"'"'s contents are above a threshold value, and further whether the buffer'"'"'s contents are also increasing, at substantially steady-state, or decreasing.

18. The traffic management device of claim 17, further the processing component further being configured for sending an explicit congestion notification based on the buffer'"'"'s contents and a current temporal delay of the ACK.

19. A traffic management device (TMD) for enabling communications between at least one sending network device and a receiving network device, comprising:

a transceiver that receives packets from the sending network device destined for the receiving network device; and

a processor for executing instructions that;

selectively delays sending of an acknowledgement (ACK) to the sending device in response to receiving a network packet, based, at least in part, on whether a buffer'"'"'s contents are above a threshold value, and further whether the buffer'"'"'s contents are also increasing, at substantially steady-state, or decreasing; and

when it is determined that the contents of the buffer are substantially increasing above the threshold value, and a round trip time for the sending network device is less than a round trip time for a destination, sending an explicit congestion notification (ECN) to the sending network device.