# US 8,787,169 B2 · System and method for adjusting transport layer processing during flow control and suspension states > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,169 B2 - Document ID: US8787169B2 - Status: Granted - Kind: B2 - Application number: 13/621,079 - Filed: 2012-09-15 - Published: 2013-08-08 - Granted: 2014-07-22 - Earliest claimed: 2012-02-03 - Assignees: Apple Inc. - Applicants: Cahya Masputra; Padmavathy Bhooma - Inventors: Cahya Masputra; Padmavathy Bhooma - Web page: https://patentgrep.com/patent/US8787169B2 ## CPC - H04L 47/60: implementing hierarchical scheduling - H04L 47/2441: relying on flow classification, e.g. using integrated services [IntServ] - H04L 47/6215: {Individual queue per QOS, rate or priority} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method for efficiently transmitting packets from a client device comprising: receiving a packet at a network transport layer of a client device; calculating a flow hash value for the packet, the flow hash value associating the packet with a particular network flow, the flow hash value usable to track the packet and other packets associated with the particular network flow; receiving feedback for the flow from a layer below the network transport layer of the client device, the flow being identified using the flow hash value, the feedback indicating queuing conditions associated with the flow; and adjusting built in backoff mechanisms normally provided by the network socket layer based on the current queuing conditions. ## Claims ### Claim 1 A method for efficiently transmitting packets from a client device comprising: receiving a packet at a network transport layer of a client device; calculating a flow hash value for the packet, the flow hash value associating the packet with a particular network flow, the flow hash value usable to track the packet and other packets associated with the particular network flow; receiving feedback for the flow from a layer below the network transport layer of the client device, the flow being identified using the flow hash value, the feedback indicating queuing conditions associated with the flow; and adjusting built in backoff mechanisms normally provided by the network transport layer based on the current queuing conditions; wherein the current queuing conditions include an indication as to whether a socket associated with the flow is flow controlled as the result of a number of packets accumulating in a transmit queue reaching a specified threshold and wherein the built in backoff mechanisms provided by the transport layer are responsively disabled. ### Claim 2 (depends on 1) The method as in claim 1 wherein adjusting the built in backoff mechanisms comprises disabling a retransmit function provided by the transport layer. ### Claim 3 (depends on 2) The method as in claim 2 wherein the transport layer is a TCP transport layer and the flow contains TCP packets. ### Claim 4 (depends on 2) The method as in claim 2 wherein the transport layer is a UDP transport layer and the flow contains UDP packets. ### Claim 5 (depends on 1) The method as in claim 1 wherein adjusting the built in backoff mechanisms comprises adjusting a retransmit timer provided by the transport layer, the retransmit timer indicating a duration at which the transport layer waits before attempting to retransmit after failing to receive an acknowledgement (ACK). ### Claim 6 (depends on 5) The method as in claim 5 wherein a socket associated with the flow is marked as flow controlled at a network layer, the flow control mark indicating that new packets for the socket should be delayed. ### Claim 7 (depends on 6) The method as in claim 6 wherein if an application associated with the flow continues to send data, packets for the flow are dropped if the socket is a user datagram protocol (UDP) socket. ### Claim 8 (depends on 1) The method as in claim 1 wherein adjusting built in backoff mechanisms provided by the transport layer comprises disabling explicit congestion notification (ECN) provided by the transport layer. ### Claim 9 (depends on 8) The method as in claim 8 further comprising enabling ECN when current queuing conditions improve. ### Claim 10 A non-transitory machine-readable medium having a program code stored thereon which, when executed by a processor, causes the processor to perform a plurality of operations comprising: receiving a packet at a network transport layer of a client device; calculating a flow hash value for the packet, the flow hash value associating the packet with a particular network flow, the flow hash value usable to track the packet and other packets associated with the particular network flow; receiving feedback for the flow from a layer below the network transport layer of the client device, the flow being identified using the flow hash value, the feedback indicating queuing conditions associated with the flow; and adjusting built in backoff mechanisms normally provided by the network transport layer based on the current queuing conditions; wherein the current queuing conditions include an indication as to whether a socket associated with the flow is flow controlled as the result of a number of packets accumulating in a transmit queue reaching a specified threshold and wherein the built in backoff mechanisms provided by the transport layer are responsively disabled. ### Claim 11 (depends on 10) The machine-readable medium as in claim 10 wherein adjusting the built in backoff mechanisms comprises disabling a retransmit function provided by the transport layer. ### Claim 12 (depends on 11) The machine-readable medium as in claim 11 wherein the transport layer is a TCP transport layer and the flow contains TCP packets. ### Claim 13 (depends on 11) The machine-readable medium as in claim 11 wherein the transport layer is a UDP transport layer and the flow contains UDP packets. ### Claim 14 (depends on 10) The machine-readable medium as in claim 10 wherein adjusting the built in backoff mechanisms comprises adjusting a retransmit timer provided by the transport layer, the retransmit timer indicating a duration at which the transport layer waits before attempting to retransmit after failing to receive an acknowledgement (ACK). ### Claim 15 (depends on 14) The machine-readable medium as in claim 14 wherein a socket associated with the flow is marked as flow controlled at a network layer, the flow control mark indicating that new packets for the socket should be delayed. ### Claim 16 (depends on 15) The machine-readable medium as in claim 15 wherein if an application associated with the flow continues to send data, packets for the flow are dropped if the socket is a user datagram protocol (UDP) socket. ### Claim 17 (depends on 10) The machine-readable medium as in claim 10 wherein adjusting built in backoff mechanisms provided by the transport layer comprises disabling explicit congestion notification (ECN) provided by the transport layer. ### Claim 18 (depends on 17) The machine-readable medium as in claim 17 further comprising enabling ECN when current queuing conditions improve.