Method and apparatus for controlling transmission flow using explicit rate control and queuing without data rate supervision
View Patent ↗Packet flow rate control techniques are enhanced by the interactive and early invocation of packet queuing to control short flows of packets and to eliminate undershoot and overshoot of a targeted flow rate. Packet queuing involves the scheduled release of packets in accordance with flow policies (priorities) to achieve a pre-selected outgoing target flow rate. The combination of controlled packet queuing and packet flow rate control with appropriate mechanisms for favoring one over the other improves the efficiency of data transmission.
1. In a digital data communication network employing packets for conveying information, a method for use at a controller between a data source and a data destination in a flow path for controlling flow of data, the method comprising:
receiving, at the controller, a data packet of a Transport Control Protocol (TCP) data flow from a data source;
queuing, the data packet of the TCP data flow on a queue and subsequently transmitting the data packet at a scheduled delay to achieve a target rate for the TCP data flow, if a measured rate of the TCP data flow exceeds the target rate or a prior packet of the data flow is stored on the queue;
entering a queue drain-down phase when a first threshold number of packets of the TCP data flow are stored on the queue, wherein the queue drain-down phase comprises:
queuing the data packet of the TCP data flow on a queue and subsequently transmitting the data packet at a scheduled delay to achieve a target rate for the TCP data flow, if a prior packet of the data flow is stored on the queue;
bypassing, after entering the queue drain-down phase, the queuing step of the drain-down phase for subsequent packets of the TCP data flow when the number of packets of the TCP data flow stored on the queue falls below a second threshold number of packets; and
controlling window size, amount of acknowledged data and timing of response of acknowledgments of data in the flow path between the data source and the data destination.
2. The method according to claim 1 wherein said queuing step is initiated immediately at the start of a TCP data flow.
3. The method according to claim 1 , wherein the data packet comprises data, and wherein the method further comprises determining whether the data packet includes a new acknowledgment of data; and, if so, creating a first new packet including the data of the received packet and a second new packet including the new acknowledgment of data; and applying separate processing to the first and second new packets.
4. The method according to claim 1 wherein the first and second threshold are the same.
5. The method according to claim 3 further comprising modifying one or more attributes of the acknowledgment of data corresponding to the second new packet.
6. The method according to claim 5 wherein the modifying step comprises one or more of: modifying an advertised window size, modifying an amount of data acknowledged, and queuing the second new packet for a scheduled delay.
7. The method of claim 1 wherein synchronization or reset packets are scheduled for immediate transmission.