CN112152934A - Explicit feedback data flow control - Google Patents

Abstract

The present invention is explicit feedback data flow control. The present invention discloses a flow control method, system and protocol implemented at a first endpoint connected to a network system for communication with a second endpoint connected to the network system, the method comprising: maintaining an explicit rate , where the first endpoint sends data packets to the second endpoint at an explicit rate; when a feedback FC (Flow Control) packet or message is received from the control system (the component is located inside the network system) or the second endpoint , adjust the explicit rate according to the FC packet or message; the adjustment of the explicit rate does not depend on the acknowledgment of the data sent by the second endpoint; when the rate represented by the FC packet or message is different from the explicit rate, the explicit rate is Adjusted to the rate indicated in the FC packet or message.

Description

Explicit feedback data flow control

technical field

The present invention relates to methods, systems and protocols for data flow control in data networks, and in particular to a control mechanism aimed at maximizing the throughput of a path between 2 endpoints, where there is fairness to data flow sharing a path.

Background technique

In the current Internet architecture, transport is a layer 4 function, on top of a layer 3 function of routing. The purpose of the transport layer is to move data (or packets) from one endpoint to another. Today, data volumes are often large and data movement becomes a data flow; therefore, "data flow control" becomes a key layer 4 function. There are many different aspects of data flow control, including: connection control, congestion control, buffer control, transmission control, rate control, and reliability control. As of this writing, standard transport layer protocols include TCP (Transmission control protocol, Transmission Control Protocol) and UDP (Userdatagram protocol, User Datagram Protocol). TCP provides connection control, reliability control, transmission control and buffering control, while UDP only provides connection control.

It is well known that TCP suffers an exponential throughput drop when the RTT (round trip time) between 2 endpoints increases. For example, when the RTT is increased from 1ms to 10ms, the TCP throughput may drop by 40%-60%; when the RTT is increased to 100ms, the throughput may drop by 90%-95%. In response to this poor performance issue, the networking industry moves content to the edge through CDN (content distribution network) or MEC (mobile edgecomputing) operators.

However, moving content to the edge is an expensive proposition, as server costs (machines and power) are about 4 to 6 times the network cost. It makes sense to improve TCP performance to avoid moving data to the edge without incurring high costs in CDN and/or MEC.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to providing systems, protocols and methods for transmitting data at an explicit rate at a data sender at Internet Layer 4.

The receiver side of an endpoint pair (as shown in Figure 1, endpoint 1 and endpoint 2 form an endpoint pair) maintains a measure of the rate of data flow received at that end. In addition, at fixed time intervals, or when an event of abnormal data movement is detected at the receiver side, the receiver transmits a measurement of the data flow rate to the sender side or from the in-network control system.

The sender side of an endpoint pair partially or fully adjusts its transmission rate based on the measured data flow rate received at the sender side, either sent by the receiver side or sent from an in-network control system.

The sender sends a data flow control (FC) packet to the receiver in the endpoint pair. The FC packet enables the in-network control system to calculate the explicit (possibly optimal and fair) rate of the endpoint pair, while the in-network control system The control system is connected to the network system. The FC packet for an endpoint pair contains the explicit (or best fair) rate for the endpoint pair. Optionally, the in-network control system calculates an explicit rate for the endpoint pair. The in-network control system can modify the explicit rate of the endpoint pair carried by the FC packet.

The sender side of an endpoint pair maintains an explicit rate variable, while the sender side sends packets to the receiver side at a rate equal to the explicit rate. The explicit rate maintained at the sender side of the endpoint pair is adjusted based on feedback information carried by the FC packets received from the receiver side of the endpoint pair or from the in-network flow control subsystem. The receiver of the endpoint pair can use the FC packet as the feedback sent to the sender of the endpoint pair.

When the two ends of an endpoint pair are connected via a wireless medium (such as a radio communication link in a cellular network, or a satellite network or Wi-Fi network, etc.), an in-network control system or receiver endpoint sends a special data flow control packet to the sender endpoint. Alternatively, the in-network control system sends a special data flow control packet to each of the sender endpoint and the receiver endpoint. Special flow control packets may contain estimates of packet loss statistics (eg, average rates) or information about the wireless channels in the path. This special control packet may contain information about the FEC (Forward error correction, forward error correction) method that can be used by both endpoints. In addition, special control packets may contain information about the temporal variation of the available bandwidth in the wireless channels in the endpoint pair path.

For an endpoint pair, the calculation of the explicit rate variable at the sender's endpoint does not take into account the size of the available buffer (left to receive endpoint data from the sender) on the receiver's side.

For an endpoint pair, the calculation of the explicit rate variable at the sender's endpoint does not take into account the receiver's acknowledgment of packets sent by the sender.

Description of drawings

FIG. 1 is a schematic diagram of a method for implementing explicit feedback data flow control provided by an embodiment of the present invention.

Detailed ways

Below in conjunction with the accompanying drawings, the present invention is further described by means of embodiments, but the scope of the present invention is not limited in any way.

In a specific implementation, endpoint 1 in FIG. 1 sends data to endpoint 2 in FIG. 1 , and the rate of sending data is dynamically adjusted according to the specific conditions of the network.

Figure 1 endpoint 1 holds an explicit rate V and sends data to Figure 1 endpoint 2 at this explicit rate V,

(1) After a fixed time interval I, endpoint 2 in FIG. 1 sends feedback to endpoint 1 in FIG. 1, and endpoint 1 in FIG. 1 adjusts the transmission rate of data according to the feedback received. On the other hand, endpoint 1 in FIG. 1 sends a data flow control packet to endpoint 2 in FIG. 1, and the in-network control system in FIG. 1 Endpoint 1 sends feedback, and endpoint 1 in Figure 1 adjusts the rate of sending data according to the feedback.

(2) When the endpoint 2 of FIG. 1 detects an abnormality, the endpoint 2 of FIG. 1 sends feedback to the endpoint 1 of FIG. 1, and the endpoint 1 of FIG. 1 adjusts the transmission rate of the data according to the received feedback. On the other hand, endpoint 1 in FIG. 1 sends a data flow control packet to endpoint 2 in FIG. 1, and the in-network control system in FIG. 1 Endpoint 1 sends feedback, and endpoint 1 in Figure 1 adjusts the rate of sending data according to the feedback.

When the endpoint 1 in Figure 1 and endpoint 2 in Figure 1 are connected by a wireless medium,

(1) The in-network control system in Fig. 1 sends a special data flow control packet to endpoint 1 in Fig. 1. In addition, the in-network control system in Fig. 1 can also send a special data packet to endpoint 1 in Fig. 1 and endpoint 2 in Fig. 1. flow control package. This special data flow control packet can contain information about the FEC (forward error correction) method, and can also contain information about the change in the available bandwidth of the wireless channel in the path between endpoint 1 in Figure 1 and endpoint 2 in Figure 1. In 1, the two endpoints can adjust their sending rates and other behaviors based on this information.

(2) The in-network control system of Fig. 1 or the endpoint 2 of Fig. 1 sends a special data flow control packet to the endpoint 1 of Fig. 1. This special data flow control packet may contain information about the FEC (forward error correction) method, and may also contain information on changes in the available bandwidth of the wireless channel in the path between endpoint 1 in Figure 1 and endpoint 2 in Figure 1 , the two endpoints in Figure 1 can adjust their sending rates and other behaviors based on this information.

The calculation and determination of the sending rate of endpoint 1 in Fig. 1 does not depend on the buffer size of endpoint 2 in Fig. 1 and the acknowledgment data packet sent by endpoint 2 in Fig. 1.

Claims (9)

1. A flow control method implemented at a first endpoint connected to a network system, wherein the first endpoint communicates with a second endpoint connected to the network system, the method comprising: maintain an explicit rate, where the first endpoint sends packets to the second endpoint at a rate that matches the explicit rate; When receiving a feedback FC (FlowControl, flow control) packet or message sent by the control system (an internal component connected to the network system) or the second endpoint, adjust the explicit rate according to the information carried in the FC packet or message; Explicit rate adjustments do not depend on acknowledgements sent by the first endpoint for data received at the second endpoint. 2. The method according to claim 1, wherein when the speed represented by the FC package or the message is different from the explicit rate kept at the first endpoint, the explicit rate of the first endpoint is changed to the FC package or the message The indicated rate carried; the explicit rate is adjusted independently of the size of the available data buffer at the second endpoint, which is used for received data: the rate indicated in the FC packet or message is at The second endpoint measures the rate at which the first endpoint is sending. 3. The method of claim 2, wherein the rate indicated in the FC packet or message is a rate calculated by a control system. 4. A network system implementing a flow control mechanism at a first endpoint connected to the network system to communicate with a second endpoint connected to the network system, the mechanism comprising: maintain an explicit rate, where the first endpoint sends packets to the second endpoint at a rate that matches the explicit rate; When receiving a feedback FC (FlowControl, flow control) packet or message sent by the control system (an internal component connected to the network system) or the second endpoint, adjust the explicit rate according to the information carried in the FC packet or message; Explicit rate adjustments do not depend on acknowledgements sent by the first endpoint for data received at the second endpoint. 5. network system according to claim 4, wherein when receiving FC bag or message, when representing the speed different from the explicit rate that the first endpoint keeps, the first endpoint explicit rate is changed to FC package or The indicated rate carried in the message: the explicit rate is adjusted, independent of the available data buffer size of the second endpoint, which is used to receive data packets sent from the first endpoint: FC data packets or messages The rate shown is the rate at which the first endpoint transmits as measured at the second endpoint. 6. The network system of claim 5, wherein the rate indicated in the FC packet or message is the rate calculated by the control system. 7. A network system implements a flow control mechanism at a first endpoint connected to the network system to communicate with a second endpoint connected to the network system, the mechanism comprising: maintain an explicit rate, where the first endpoint sends packets to the second endpoint at a rate that matches the explicit rate; Implement forward error correction (FEC, Forward error correction) encoding on the data sent from the first endpoint to the second endpoint; When receiving a feedback FC (flow control) packet or message sent by the control system (an internal component connected to the network system) or the second endpoint, adjust the FEC encoding method according to the FC packet or message; Explicit rate adjustments do not depend on acknowledgements sent by the first endpoint for data received at the second endpoint. 8. The network system according to claim 7, wherein, when receiving an FC packet or a message representing an explicit rate different from the explicit rate maintained by the first endpoint, the explicit rate of the first endpoint is Change to the indicated rate carried by the FC packet or message; the explicit rate is adjusted without depending on the size of the available data buffer of the second endpoint, which is used to receive data packets sent from the first endpoint; FC The rate shown in the packet or message is the rate sent by the first endpoint measured at the second endpoint. 9. The network system of claim 8, wherein the rate indicated in the FC packet or message is a rate calculated by a control system.

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