Buffer bloat control

• US 10,063,489 B2
• Filed: 02/20/2014
• Issued: 08/28/2018
• Est. Priority Date: 02/20/2014
• Status: Active Grant

• Current Assignee: PNI Canada Acquireco Corp. (Francisco Partners Management LLC)
• Original Assignee: Sandvine Incorporated ULC (Sandvine Corp.)
• Inventors: Snellman, Juho, Gorrie, Luke
• Primary Examiner(s): Blanton, John
• Application Number:
  US15/120,503
• Publication Number:
  US 20170070442A1
• Time in Patent Office: 1,650 Days
• CPC Class Codes: H04L 47/41 by acting on aggregated flows or links
• CPC Class Codes: H04L 49/103 using a shared central buffer; using a shared memory
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]

Abstract

TCP data packets are transferred from a plurality of server nodes to a client node, wherein the proxy node captures all packets of the TCP flows, buffers the captured packets in a TCP stack and updates an active TCP flow list in a subscriber record representing the client node. A current proxy scheduling capacity from a current maximum amount of data allowed concurrently in transmission in one more TCP flows to the client node is estimated. When a triggering event is received, a packet retrieved from the TCP stack is scheduled in accordance with the estimated current proxy scheduling capacity and order given by the active flow list. The scheduled packet is transmitted and the active flow list is updated, whereupon scheduling a TCP flow for transmission is repeated until the current proxy scheduling capacity has been reached or there are no TCP flows in the active flow list.

Claims

1. Method performed in a proxy node for transferring transmission control protocol, TCP, data packets in TCP flows from a plurality of server nodes to a client node, wherein the proxy node captures the TCP data packets of the TCP flows, buffers the captured TCP data packets and updates a TCP active flow list in a subscriber record representing the client node;

the method comprising;

estimating a current proxy scheduling capacity from a current maximum total data amount allowed concurrently in transmission in one or more TCP flows to the client node;

until the current proxy scheduling capacity has been reached or there are no TCP flows in the TCP active flow list, scheduling a TCP flow for transmission when a TCP data packet transmission triggering event is received, the scheduling based on an order given by the TCP active flow list;

transmitting one or more TCP data packets from the scheduled TCP flow to the client node;

updating the TCP active flow list; and

repeating the step of scheduling a TCP flow for transmission.

2. The method of claim 1, wherein the estimating of a current proxy scheduling capacity further includes:

determining a roundtrip time for one or more transmitted TCP data packets; and

adjusting the estimated current proxy scheduling capacity based on the roundtrip time, the data amount in transmission when transmitting the one or more TCP data packets, and/or one or more predetermined adjustment factors.

3. The method of claim 2, wherein the step of adjusting the estimated current proxy scheduling capacity comprises applying a speed-up or slow-down factor.

4. The method of claim 2, wherein the adjusting the estimated current proxy scheduling capacity includes adjusting the current proxy scheduling capacity up or down upon delivery of a TCP packet.

5. The method of claim 1, wherein the client node is a wireless device capable of receiving TCP data packets over a plurality of radio access technologies, e.g. HSPA, UMTS, GPRS, or Wi-Fi.

6. The method of claim 1, wherein the current maximum data amount allowed concurrently in transmission in TCP flows to the client node is an amount of bytes.

7. The method of claim 1, further comprising storing the determined roundtrip time as a previous roundtrip time when exceeding a predetermined roundtrip time threshold, comparing a current roundtrip time to the previous roundtrip time and maintaining a proxy scheduling capacity when the previous roundtrip time is greater than the current round-trip time and current roundtrip time exceeds the predetermined roundtrip time threshold.

8. The method of claim 1, wherein the subscriber record contains a list of active TCP flows and a list of passive TCP flows, wherein a flow is in the list of active TCP flows if there is unsent TCP data packets buffered for the flow and in the passive list if there are no unsent TCP data packets buffered for the flow and wherein a flow is moved from the list of passive TCP flows to the list of active TCP flows when one or more TCP packets are received from the server nodes and when a flow is moved to the list of passive TCP flows when all buffered TCP data packets for a flow has been transmitted to the client node.

9. The method of claim 1, wherein the transmitting TCP data packets further includes allowing transmission of a scheduled TCP flow, when the data amount in transmission is below to a pre-configured per-subscriber limit set for the client node.

10. The method of claim 1, wherein the transmitting TCP data packets further includes allowing transmission of a scheduled TCP flow, when the data amount in transmission is below a pre-configured per-flow limit.

11. The method of claim 1, wherein the proxy node is configured to capture user datagram protocol, UDP, data packets and forward the captured UDP data packets, the method further comprising interleaving the UDP data packets with the TCP data packets during the scheduling, inspecting a data stream comprising the interleaved TCP and UDP data packets, determining an amount of remaining UDP data packets from the delivery information and using the determined amount to improve the scheduling.

12. The method of claim 11, further including presuming acknowledgement of UDP data packets when receiving acknowledgement for a subsequent TCP packet.

19. A non-transitory computer program comprising computer program code which, when executed in a proxy node causes the proxy node to execute the method claimed claim 1.

13. A proxy node for transferring transmission control protocol, TCP, data packets in TCP flows from a plurality of server nodes to a client node;

the proxy node comprising;

a receiver configured to receive TCP data packets destined for the client node;

a memory configured to store the received TCP data packets and to update a TCP active flow list in a subscriber record representing the client node;

a processor configured to;

estimate a current proxy scheduling capacity from a current maximum total data amount allowed concurrently in transmission in one or more TCP flows to the client node;

until the current proxy scheduling capacity has been reached or no there are no TCP flows are in the TCP active flow list, schedule a TCP flow for transmission when a TCP data packet transmission triggering event is received, the scheduling based on an order given by the TCP active flow list for the subscriber;

initiate transmission one or more TCP data packets from the scheduled TCP flow to the client node;

update the TCP active flow list; and

repeat the step of scheduling a TCP flow for transmission.

14. The proxy node of claim 13, wherein the processor further is configured to:

determine a roundtrip time for one or more transmitted TCP data packets; and

adjust the estimated current proxy scheduling capacity based on the roundtrip time, the data amount in transmission when transmitting the one or more TCP data packets, and/or one or more predetermined adjustment factors.

15. The proxy node of claim 13, wherein the processor is further configured to:

allow transmission of a scheduled TCP flow, when the data amount in transmission is below to a pre-configured per-subscriber limit set for the client node.

16. The proxy node of claim 13, wherein the processor is further configured to:

allow transmission of a scheduled TCP flow, when the data amount in transmission is below a pre-configured per-flow limit.

17. The proxy node of claim 13, wherein the processor is further configured to compare a roundtrip time to a predetermined roundtrip time threshold, to store the roundtrip time as a previous roundtrip time when exceeding the predetermined roundtrip time threshold, to compare a current roundtrip time to the previous roundtrip time and to instruct the packet scheduling entity to maintain the proxy scheduling capacity when the previous roundtrip time is greater than the current round-trip time and current roundtrip time exceeds the predetermined roundtrip time threshold.

18. The proxy node of claim 13, wherein the receiver, is further configured to store receive user datagram protocol, UDP, data packets, the memory is further configured to store UDP data packets, and the processor is further configured to interleave the UDP data packets with the TCP data packets during the step of scheduling, inspect a data stream comprising the interleaved TCP and UDP data packets, determine an amount of remaining UDP data packets from the delivery information and use the determined amount to improve the scheduling.