KR20100034553A - Appratus for tcp congestion control, a method thereof and recorded medium recorded with a program executing the same - Google Patents

Abstract

PURPOSE: An apparatus for a TCP congestion control, a method thereof and a recorded medium recorded with a program executing the same are provided to perform congestion control in consideration of rearrangement of a packet. CONSTITUTION: If the number of received duplicate response of a transceiver(201) is over a duplicate response threshold value, a controller(204) performs a first congestion. If the transceiver receives an acknowledgement response to the first congestion control before the expiration of the verification timer(202), the controller verifies the generation of packet rearrangement. The controller performs a first resetting of more than one of duplicate response threshold value, a slow start threshold value, a congestion window.

Description

Apparatus for TCP congestion control, a method approximately and recorded medium recorded with a program executing the same}

The present invention relates to TCP congestion control, and more particularly, to a TCP congestion control apparatus, a method thereof, and a recording medium on which the program is recorded.

Congestion control of TCP is a necessary technique for efficient resource utilization among multiple network users.Congestion control is based on the collected situation evidence based on the collected situation evidence. By spontaneously reducing transmission performance, it overcomes congestion and utilizes network resources smoothly between the source (hereinafter referred to as 'first device') and the destination (hereinafter referred to as 'second device'). This is the technique that makes it possible.

Here, congestion refers to a phenomenon in which certain packets are not processed correctly when a packet that exceeds the capability of a router that delivers a packet to another network enters the network.

According to the prior art, TCP transmits the sequence number of the packet to the first device for the packet received by the second device for reliability, indicating that the packet arrived safely.

Here, if the second device receives a packet out of order, the second device sends the order number corresponding to the order to be received again to indicate that the packet did not arrive normally. In this case, when the order number of the response received by the first device is the same, this is called a duplicate response, and when an order number larger than the previously received order is received, it is called an affirmative response.

According to the prior art, since a large number of such duplicate responses occur when packet loss occurs, the conventional TCP collects such duplicate responses based on a situation and performs congestion control.

More specifically, if three or more duplicate responses are received for one sequence number for fast congestion control, it is determined that the corresponding packet is lost, and the loss is determined to be caused by congestion in the network and congestion control is performed. . When congestion control occurs, the performance is greatly reduced by halving the transmission rate for the session, and the packet which is determined to be lost is transmitted again.

However, according to the related art, when unnecessary congestion control occurs, there is a problem in that the performance of the session cannot be efficiently used due to a wrong mechanism even though it is not congested.

Packet redordering refers to a phenomenon in which packets are interspersed during a transmission process so that a packet transmitted first by the first device arrives at the second device later than a packet sent later.

According to the prior art, there is a problem that packet incidence of relocation is not high and is not well considered as a cause of duplicate response. Recently, due to the development of network equipment and the development of algorithms, the incidence of packet relocation is increasing. According to the prior art, there is a problem that unnecessary congestion control occurs due to packet relocation, causing TCP performance degradation.

 Therefore, there is a need for developing a new congestion control scheme considering packet relocation.

An object of the present invention is to propose a congestion control performing apparatus for performing congestion control in consideration of packet rearrangement, a method thereof, and a recording medium on which the program is recorded.

Another object of the present invention is to propose a congestion control performing apparatus for recovering a degraded TCP performance when a congestion control is performed due to packet relocation, a method and a recording medium on which the program is recorded.

According to an aspect of the present invention, an apparatus for controlling congestion of a transmission control protocol (TCP), the apparatus comprising: a transceiver for transmitting and receiving a combined network and data; A verification timer including a predetermined timer; Congestion control that performs congestion control using one or more of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery part; And a controller for driving the verification timer when the transceiver receives a duplicate response, wherein the controller controls the congestion control execution unit when the number of duplicate responses received by the transceiver is greater than or equal to the duplicate response threshold to control the first congestion. And if the transceiver receives an acknowledgment according to the first congestion control before the verification timer expires, verifies that packet reordering has occurred, and the duplicate response threshold and slow start threshold (Slow Start). An apparatus for performing congestion control is provided that first resets one or more of a threshold, an Ssthresh, and a congestion window Cwnd.

The controller may control the congestion control execution unit to perform a second congestion control when the number of duplicate responses received by the transceiver unit is less than the duplicate response threshold value and the verification timer expires. The response threshold may be reset second.

을 이용하여 상기 중복응답임계값을 제1 재설정할 수 있다.In addition, the control unit is an equation

The duplicate response threshold may be first reset using.

Where dt is the duplicate response threshold, dt _s is the new value to be reset to the duplicate response threshold, and dt _pre is The previous duplicate response threshold, dt _M is the number of duplicate responses received until the packet relocation has been verified, and α is a specified real number between 0 and 1, inclusive.

In addition, the controller may first reset one or more of the slow start threshold point (Ssthresh) and the congestion window (cwnd) using the following equation.

[Equation]

Slow start Threshold = _current slow start threshold _before

Congestion window _present = 2 Х Congestion window _present

The controller may second reset the duplicate response threshold to three.

In addition, the verification timer may be a size of a packet return time (RTT).

According to another aspect of the present invention, an apparatus for controlling congestion of a transmission control protocol (TCP), the apparatus comprising: a transceiver for transmitting and receiving data to and from a combined network; A verification timer including a predetermined timer and driving when the transceiver receives a duplicate response; Congestion control that performs congestion control using one or more of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery part; And a controller for controlling the transceiver, the verification timer, and the mixing control unit, wherein the congestion control unit performs the first congestion control when the number of duplicate responses received by the transceiver unit is greater than or equal to the duplicate response threshold. The controller verifies that packet reordering has occurred when the transceiver receives an acknowledgment according to the first congestion control before the verification timer expires, and the duplicate response threshold and the slow start threshold (Slow Start). Provided is a congestion control performing device, characterized in that the second reset of at least one of a threshold, a Ssthresh, and a congestion window (Cwnd).

The congestion control unit may perform a second congestion control when the number of duplicate responses received by the transceiver unit is less than the duplicate response threshold value and the verification timer expires, and the control unit performs the second congestion control. In response to the duplicated response threshold may be reset.

According to another aspect of the present invention, a method of controlling a congestion control (TCP) congestion control device comprising: (a) driving a verification timer when receiving a duplicate response; (b) If the number of duplicate responses received is greater than or equal to the duplicate response threshold, one of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery. Performing a first congestion control using the above; And (c) verifying that packet reordering has occurred when receiving an acknowledgment according to the first congestion control before the verification timer expires, the duplicate response threshold, a slow start threshold, A congestion control method is provided that includes first resetting one or more of Ssthresh and a congestion window (Cwnd).

Further, after the step (a) and before the step (b), if the number of the duplicated responses received (d1) is less than the duplicated response threshold and the verification timer expires, the sum of additional increases / additive increase / Performing second congestion control using one or more of Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery; And (d2) resetting the duplicate response threshold value according to the second congestion control.

을 이용하여 상기 중복응답임계값을 제1 재설정할 수 있다. In addition, the step (c) is the equation

The duplicate response threshold may be first reset using.

Where dt is the duplicate response threshold, dt _s is the new value to be reset to the duplicate response threshold, and dt _pre is The previous duplicate response threshold, dt _M is the number of duplicate responses received until the packet relocation has been verified, and α is a specified real number between 0 and 1, inclusive.

In addition, the step (c) may first reset one or more of the slow start threshold (Ssthresh) and the congestion window (cwnd) using the following equation.

[Equation]

Slow start Threshold = _current slow start threshold _before

Congestion window _present = 2 Х Congestion window _present

According to another aspect of the present invention, a program of instructions that can be executed by a congestion control device is implemented to perform congestion control, and a recording medium recording a program that can be read by the congestion control device. A method comprising: (a) driving a verification timer when receiving a duplicate response; (b) If the number of duplicate responses received is greater than or equal to the duplicate response threshold, one of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery. Performing a first congestion control using the above; And (c) verifying that packet reordering has occurred when receiving an acknowledgment according to the first congestion control before the verification timer expires, the duplicate response threshold, a slow start threshold, There is provided a recording medium having recorded thereon a program for executing a first resetting step of at least one of Ssthresh and a congestion window Cwnd.

An apparatus for performing congestion control according to the present invention, a method thereof, and a recording medium on which the program is recorded have an advantage of performing congestion control in consideration of packet relocation.

In addition, when congestion control due to packet relocation is performed, there is an advantage of recovering the degraded TCP performance.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate a thorough understanding of the present invention, the same reference numerals are used for the same means regardless of the number of the drawings.

1 is a diagram illustrating a connection between a packet transmitting apparatus and a receiving apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a source apparatus 100 (Source, hereinafter referred to as 'first apparatus') according to an embodiment of the present invention is a destination apparatus (destination, hereinafter, hereinafter, 'second' through a network 150). Device ').

The network 150 may be applied with various parallel processing techniques such as multi path routing and route fluttering for load balancing of the network.

The first device 100 may be various terminals capable of transmitting and receiving data, such as a computer and a mobile terminal, and transmit a packet, such as a router (for example, reference numeral 102) to which the terminal is connected according to an environment to which the present invention is applied. It is apparent to those skilled in the art in view of the technical idea of the present invention that it can be a relay device.

Hereinafter, a description will be given on the assumption that the first device 100 is a terminal in order to facilitate understanding and explanation of the present invention, but the present invention is not limited thereto.

Up to now, it has been described with reference to FIG. 1 that the first device 100 and the second device 110 can be connected through the network 150.

Hereinafter, the configuration of the first apparatus 100 will be described with reference to FIG. 2.

2 is a block diagram illustrating a configuration of the first device 100 according to the first embodiment of the present invention.

Referring to FIG. 2, the first apparatus 100 according to the first embodiment of the present invention may include a transceiver 201, a verification timer 202, a congestion control execution unit 203, and a controller 204. have.

The transceiver 201 may transmit / receive data between the second device 110 through the network 150 to which the first device 100 is connected.

The verification timer 202 may include a predetermined timer.

Here, it will be apparent to those skilled in the art that the size value of the timer included in the verification timer 202 may be designated as various values according to the environment to which the present invention is applied.

For example, the verification timer 202 may include a timer equal to the size of the packet return time (RTT).

The congestion control unit 203 performs congestion control using one or more of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery. can do.

Here, AIMD, Slow Start, Fast Retransmit, and Fast Recovery are techniques known to those skilled in the art at the time of filing the present invention, and therefore, the gist of the present invention is clearly stated. Detailed description is omitted except for parts related to the present invention.

The controller 204 may control the transceiver 201, the verification timer 202, and the congestion control execution unit 203. Hereinafter, the functions of the control unit 204 according to the first embodiment of the present invention will be described.

<First function of control unit 204>

According to the first embodiment of the present invention, when the transceiver 201 receives a duplicate response, the controller 204 may drive the verification timer 202.

<2nd function of the control part 204>

In addition, according to the first embodiment of the present invention, the control unit 204 performs the first congestion control by controlling the congestion control unit 203 when the number of duplicate responses received by the transceiver unit is greater than or equal to the duplicate response threshold. Can be. At this time, if the transceiver 201 receives an acknowledgment according to the first congestion control before the verification timer 202 expires, the controller 204 verifies that the packet relocation has occurred, duplicate response threshold, slow start One or more of a slow start threshold (hereinafter referred to as 'ssthresh') and a congestion window (hereinafter referred to as 'cwnd') may be reset.

Here, the congestion window cwnd is the amount of data transmitted to the network 150 before the first device receives the ACK message.

Here, the first congestion control and the first reset are named to distinguish them from the congestion control and the reset performed under different conditions according to the embodiment of the present invention.

According to the prior art, there is a problem that packet rearrangement is not considered.

More specifically, according to the prior art, the size of the duplicate response threshold value is determined by the number of duplicate responses at the moment of packet relocation, and thus there is a problem that the universality is inferior.

In addition, according to the related art, since the duplicated response threshold once increased takes a long time to reflect the network situation, it cannot effectively cope with congestion, and unnecessarily expires the retransmission timer, causing TCP degradation. There is a problem.

Hereinafter, the number of duplicate responses received until packet relocation is verified is called a duplicate response length. The present invention proposes a method for deriving a new duplicate response threshold value through the duplicate response length. The redundant response length is a result limited to the network condition at the time of measurement, and a large difference occurs in the value depending on the size of the congestion window (Cwnd) at the time. However, note that the magnitude of this value can roughly infer the degree of packet relocation in the current network.

The present invention proposes a method of resetting a duplicate response threshold value through a duplicate response length and performing congestion control using the reset duplicate response threshold value.

According to the first embodiment of the present invention, when the transceiver 201 receives an acknowledgment according to the first congestion control before the verification timer 202 expires, the controller 204 relocates the packet. Can be verified to have occurred. In this case, the controller 204 may first reset one or more of a duplicate response threshold, a slow start threshold, and a congestion window cwnd in order to restore the performance of TCP which has been unnecessarily degraded.

More specifically, the controller 204 may first reset one or more of the duplicate response threshold value, the slow start threshold point (Ssthresh), and the congestion window (Cwnd) using Equation 1 below.

[Equation 1]

Where dt is the duplicate response threshold, dt _s is the new value to be reset to the duplicate response threshold, and dt _pre is The previous duplicate response threshold, dt _M is the number of duplicate responses received until the packet relocation has been verified, and α is a specified real number between 0 and 1, inclusive.

Therefore, according to the first embodiment of the present invention, the control unit 204 may not continuously reduce the duplicate response threshold when congestion control according to packet relocation is performed.

)으로 재설정할 수 있다.More specifically, the control unit 204 applies the weight (1-α) and the weight (α) to the duplicate response length (dt _M ) and the previous duplicate response threshold value (dt _pre ), respectively, and then adds the new sum of the two values. Duplicate Response Threshold (

Can be reset.

This reset duplicated response threshold can delay the performance of fast retransmission and fast recovery.

Therefore, according to the first embodiment of the present invention, there is an advantage in that it is possible to reset a universal duplicate response threshold suitable for application in a rapidly changing network environment. In addition, this prevents congestion control due to packet relocation, thereby preventing unnecessary performance degradation and thereby efficiently using network resources.

In addition, according to the first embodiment of the present invention, if unnecessary congestion control according to packet rearrangement is verified, the controller 204 may adjust two factors related to TCP to recover the degraded TCP performance through unnecessary congestion control.

In more detail, the controller 204 may adjust the slow start threshold point Ssthreh and the congestion window Cwnd using Equation 2 below.

[Equation 2]

Slow start Threshold = _current slow start threshold _before

Congestion window _present = 2 Х Congestion window _present

For example, the controller 204 may restore the reduced transmission rate by increasing the size of the congestion window Cwnd. Here, as the congestion window Cwnd increases, the corresponding session may have a high transmission rate.

For example, the controller 204 may restore the slow start threshold to a value before congestion control occurs. Here, the slow start threshold (Ssthreth) is a factor that determines the size variation of the congestion window. Therefore, slow start threshold (Ssthreth) is also a major factor in TCP session performance.

Therefore, according to the first embodiment of the present invention, by restoring the size of two elements that are unnecessarily limited in relation to congestion, unnecessary performance degradation due to packet relocation can be recovered.

According to the first embodiment of the present invention, after the first congestion control is performed by the congestion control execution unit 203, if a positive response according to the first congestion control is received before expiration of the verification timer 202, The congestion control by the controller 204 has been described as verified.

If the corresponding packet is lost, a first congestion control may be performed according to the loss, and an acknowledgment according to the first congestion control may be received before expiration of the verification timer 202. In this case, since the round trip time from the packet to the acknowledgment indicates the situation of the network, the response to the retransmitted packet within the verification timer may mean that the resources of the network are abundant. Therefore, according to the embodiment of the present invention, the control unit 204 may determine that congestion control is unnecessary in this case, as described above.

<3rd function of the control part 204>

According to the first embodiment of the present invention, the controller 204 may initialize the duplicate response threshold if it is incorrectly set.

The duplicate response threshold changes frequently, and if such a duplicate response threshold increases unnecessarily in spite of using a gentle adjustment method according to an embodiment of the present invention, it may not be possible to control the congestion in time. As such, when congestion control does not occur in a timely manner, the controller 204 may determine that the duplicate response threshold is set incorrectly, and reset the duplicate response threshold to a predetermined value.

For example, the transmission / reception unit 201 receives the duplicate response and the verification timer 202 is driven, but the transmission / reception unit 201 may not receive the positive response until the verification timer 202 expires. If at this time, even congestion control through fast retransmission quick recovery does not occur, it can be determined that the duplicate response threshold is excessively increased. According to an embodiment of the present invention, in this case, the control unit 204 resets the duplicate response threshold to a predetermined value, and is further delayed by the size of the verification timer so that the congestion control unit 203 may perform congestion control. .

Here, it will be apparent to those skilled in the art in view of the technical spirit of the present invention that the controller 204 may reset the duplicate response threshold to various values according to the environment to which the present invention is applied.

The function of each component of the first apparatus 100 according to the embodiment of the present invention has been described above with reference to FIG. 2.

Here, the divisions for the components in the present specification are intended to be clear that they are only divided by the main functions in charge of each component. That is, the two or more components described above may be combined into one component, or one component may be divided into two or more parts for each of the more detailed functions. Each of the components described above may additionally perform some or all of the functions of other components in addition to the main functions of the components, and some of the main functions of the components are different from each other. Of course, it may be carried out exclusively by. Therefore, the presence or absence of each component described through this specification should be interpreted functionally, and for this reason the configuration of the components according to the congestion control device according to an embodiment of the present invention can achieve the object of the present invention It is clearly noted that within limits, this may differ from FIG. 2.

Hereinafter, the functions of each component according to the second embodiment of the present invention will be described. In more detail, the control unit 204 may determine the condition determination for controlling each component by the component itself.

More specifically, according to the second embodiment of the present invention, the verification timer 202 may be driven when the transceiver 201 receives a duplicate response.

In addition, according to the second embodiment of the present invention, the congestion control unit 203 may perform the first congestion control when the number of duplicate responses received by the transceiver unit is greater than or equal to the duplicate response threshold.

In addition, according to the second embodiment of the present invention, the congestion control unit 203 is the second when the number of duplicate responses received by the transceiver unit 201 is less than the duplicate response threshold value and the verification timer 202 expires. Congestion control can be performed.

Further, according to the second embodiment of the present invention, the controller 204 may reset the duplicate response threshold to a predetermined value according to the first congestion control.

Further, according to the second embodiment of the present invention, when the acknowledgment response to the packet retransmitted by the transceiver 201 is received before the verification timer 202 expires according to the second congestion control, it is duplicated as described above. Degraded TCP performance can be recovered by resetting one or more of the response threshold, slow start threshold (Ssthresh), and congestion window (Cwnd).

As described above, it is apparent to those skilled in the art in view of the technical spirit of the present invention that the functions of each component of the congestion control device 100 according to the embodiment of the present invention may be implemented in various details or integrated in spite of the name.

3 is a flowchart illustrating a method in which a congestion control device performs congestion control according to an embodiment of the present invention.

As described above with reference to FIG. 2, since each component of the congestion control apparatus 100 according to the embodiment of the present invention may be implemented in various ways, the following description will be made with reference to FIG. 3. It will be described that the first device 100 described as an example is the entire subject.

In addition, in the description with reference to FIG. 3, the description overlapping with the above description with reference to FIG. 2 will not be described in detail in order to clarify the gist of the congestion control method.

Referring to FIG. 3, in operation S302, the first device 100 may receive a duplicate response.

Here, the redundant response may be transmitted by the second device 110, which is a receiving side, to the first device 100 according to packet relocation or packet loss.

Subsequently, in operation S304, the first device 100 may drive the verification timer in response to receiving the duplicate response.

This has been described above in the first function of the controller 204 with reference to FIG. 2.

Subsequently, when the number of duplicate response receptions is greater than or equal to the duplicate response threshold in step S306, the first apparatus 100 may determine that congestion has occurred and perform first congestion control in step S314.

Subsequently, when the acknowledgment of the retransmitted packet according to the first congestion control is received by the first device 100 before the verification timer 202 expires in steps S316 and S318, the first device 100 rearranges the packet. According to the first congestion control is performed, it is possible to recover the degraded TCP performance in step S320.

Step S306, step S314, step S316, step S318, and step S320 have been described in detail in the second function of the controller 204 with reference to FIG. 2.

If the verification timer 202 expires despite the number of duplicate responses received by the first device 100 in steps S306 and S308 being less than the duplicate response threshold value, the first device 100 returns a duplicate response threshold value. It may be determined that it is set incorrectly. In this case, in operation S312, the first device 100 may reset the incorrectly set duplicate response threshold to a predetermined value, and perform congestion control by delaying the reset duplicate response threshold by the reset value.

Step S306, step S308, and step S312 have been described in detail in the function 3 of the controller 204 with reference to FIG. 2.

So far, the congestion control method according to the embodiment of the present invention has been described with reference to FIG. 3.

4 and 5 are diagrams illustrating a second function of the controller 204 described above with reference to FIG. 2.

3 and 4, when the first device 100 receives a duplicate response in step S302 of FIG. 3 (402), the driving timer 202 may be driven in step S304.

When the first device 100 receives the duplicate responses as many as n duplicate response thresholds (404), in step S314, as an example of the first congestion control, fast retransmission and fast recovery may be performed (406). .

When the first device 100 receives an acknowledgment of the retransmitted packet according to the first congestion control until the verification timer 202 expires in steps S316 and S318 (408), the first device 100 receives the first response. 1 congestion control may be determined as unnecessary congestion control according to packet rearrangement (410). In this case, it is described above with reference to FIGS. 2 and 3 that the first device 100 may recover the degraded TCP performance in step S320.

3 and 5, when the first device 100 does not receive an acknowledgment of the retransmitted packet according to the first congestion control in step S316 until the black timer 100 expires (502), the first The apparatus 100 may determine that the first congestion control is appropriate congestion control performed for reasons such as packet loss.

So far, the second function of the controller 204 has been described in detail with reference to FIGS. 3, 4, and 5.

FIG. 6 is a diagram illustrating a topology for simulation according to an exemplary embodiment of the present invention, and FIGS. 7 and 8 are simulation results of varying transmission rate variations occurring in a link between routers.

The topology consists of four nodes and two types of links: the first device (Source), the second device (Destination), (R1), and (R2). (Link 1) has a 10Mbps rental bandwidth and 1ms propagation delay, and (Link 2) has a 3Mbps rental bandwidth and average propagation delay of 50 + 200τms. At this time, the standard deviation was (200τ) / 3 ms, and τ was set at 0.2 interval with a value between 0 and 2. The error model is applied, and the error rate is 0.001.

As a configured network parameter, a buffer having a size of 400 segments is installed in the first device (Source) and the second device (Destination), and the size of the segment is defined as 1500 bytes. The maximum size of the congestion window was set to 500 segments. In order to generate a packet relocation, the value was changed to a specific time interval, and the interval was simulated with a size of 50 ms and 250 ms, and a total of 1000 seconds was performed by starting transmission at 10 seconds and ending transmission at 1010 seconds. Packet relocation occurs according to random numbers, and the seed value is simulated using a total of 20 different values.

7 and 8, the path delay factor (τ) is a value for determining the propagation delay time (average 50 + 200τ ms, and the standard deviation is (200τ) / 3 ms) of the link between the two routers. It is assumed that the value is changed at 0.2 intervals.

Goodput, which is the Y-axis, represents the actual amount of data transmitted by the first device to the second device. In this case, the size of the retransmitted data may not be included in the actual amount of data.

The switch rate changes the propagation delay of the link between two routers in order to randomly rearrange packets in a single link topology. The time interval is the switch rate.

The error rate is a value to generate a single packet loss in the topology and has a 0.1% chance of packet drop.

7 and 8, it can be seen that the congestion control method according to the embodiment of the present invention exhibits about 8% higher performance than the TCP-DAD (TCP Dynamically Adjusted Duptresh).

This performance difference occurs in the TCP-DAD of the prior art because the duplicate response threshold changes rapidly every time packet relocation occurs. Rapidly increasing duplicate response thresholds are likely to result in a situation where the retransmission timer 202 expires. However, since the congestion control method according to the embodiment of the present invention uses the duplicate response length, which is the number of duplicate responses received until packet relocation is verified, the duplicate response threshold is gradually increased, which is more stable than that of TCP-DAD. Has a value. In addition, the present invention is able to cope with the congestion faster, showing a higher performance in the simulation environment.

Congestion control method method according to an embodiment of the present invention can be implemented in the form of program instructions that can be executed by various computer means may be recorded on a computer readable medium. Computer-readable media may include, alone or in combination with the program instructions, data files, data structures, and the like.

The program instructions recorded on the computer readable medium may be those specially designed and constructed for the present invention, or may be known and available to those skilled in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Hardware devices specially configured to store and execute program instructions such as magneto-optical media and ROM, RAM, flash memory and the like. In addition, the above-described medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like including a carrier wave for transmitting a signal specifying a program command, a data structure, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

1 is a diagram illustrating a connection between a packet transmitter and a receiver according to an embodiment of the present invention.

2 is a block diagram illustrating a configuration of a first device 100 according to a first embodiment of the present invention.

3 is a flowchart illustrating a method for congestion control performed by a congestion control device according to an embodiment of the present invention.

4 and 5 illustrate a second function of the controller 204 described above with reference to FIG. 2.

6 illustrates a topology for simulation in accordance with an embodiment of the present invention.

7 and 8 are simulation results by varying the frequency of the transmission rate change occurring in the link between each router.

<Description of the symbols for the main parts of the drawings>

100: first device (Source)

201: transceiver

202: Verification timer

203: congestion control unit

204: control unit

Claims (16)

An apparatus for controlling congestion of a transmission control protocol (TCP), A transceiver for transmitting and receiving the combined network and data; A verification timer including a predetermined timer; Congestion control that performs congestion control using one or more of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery part; And When the transceiver receives a duplicate response includes a control unit for driving the verification timer, The control unit controls the congestion control execution unit to perform a first congestion control when the number of duplicate responses received by the transceiver unit is equal to or greater than a duplicate response threshold value, and before the verification timer expires, the control unit performs the first congestion control. Upon receipt of a positive response, verify that packet reordering has occurred, and reset one or more of the duplicate response threshold, Slow Start threshold, Ssthresh, and congestion window Cwnd. Congestion control performing device, characterized in that The method of claim 1, If the number of duplicate responses received by the transceiver is less than the duplicate response threshold and the verification timer expires, the controller controls the congestion control execution unit to perform a second congestion control and the duplicate response threshold. And a second reset of the value. The method according to claim 1 or 2, The control unit is

Congestion control device, characterized in that for resetting the redundant response threshold value first. Where dt is the duplicate response threshold, dt _s is the new value to be reset to the duplicate response threshold, and dt _pre is The previous duplicate response threshold, dt _M is the number of duplicate responses received until the packet relocation has been verified, and α is a specified real number between 0 and 1, inclusive. The method according to claim 1 or 2, And the control unit first resets one or more of a slow starting threshold point (Ssthresh) and a congestion window (cwnd) using the following equation. [Equation] Slow start Threshold = _current slow start threshold _before Congestion window _present = 2 Х Congestion window _present The method of claim 2, And the control unit resets the overlap response threshold value to 3 secondly. The method according to claim 1 or 2, And the verification timer is a size of a packet reciprocating time (RTT). An apparatus for controlling congestion of a transmission control protocol (TCP), A transceiver for transmitting and receiving the combined network and data; A verification timer including a predetermined timer and driving when the transceiver receives a duplicate response; Congestion control that performs congestion control using one or more of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery part; And A control unit for controlling the transceiver, the verification timer and the mixing control performing unit, The congestion control unit performs the first congestion control when the number of duplicate responses received by the transceiver unit is equal to or greater than the duplicate response threshold value. The control unit verifies that packet reordering has occurred when the transceiver receives an acknowledgment according to the first congestion control before the verification timer expires, and the duplicate response threshold and a slow start threshold And a second reset of at least one of Ssthresh and a congestion window Cwnd. The method of claim 1, The congestion control performing unit performs a second congestion control when the number of duplicate responses received by the transceiver unit is less than the duplicate response threshold value and the verification timer expires. And the control unit resets the duplicate response threshold value according to the second congestion control. In a congestion control device to control congestion of a transmission control protocol (TCP), (a) driving a verification timer when receiving a duplicate response; (b) If the number of duplicate responses received is greater than or equal to the duplicate response threshold, one of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery. Performing a first congestion control using the above; And (c) Verifying that packet reordering has occurred when receiving an acknowledgment according to the first congestion control before the verification timer expires, the duplicate response threshold, Slow Start threshold, Ssthresh And resetting at least one of a congestion window (Cwnd). 10. The method of claim 9, After step (a) but before step (b) (d1) Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, if the number of duplicated responses received is less than the duplicated response threshold and the verification timer expires. Performing a second congestion control using at least one of Fast Recovery and Fast Recovery; And and (d2) resetting the duplicate response threshold value according to the second congestion control. 11. The method according to claim 9 or 10, Step (c) is the equation

Congestion control method, characterized in that to reset the duplicated response threshold value first. Where dt is the duplicate response threshold, dt _s is the new value to be reset to the duplicate response threshold, and dt _pre is The previous duplicate response threshold, dt _M is the number of duplicate responses received until the packet relocation has been verified, and α is a specified real number between 0 and 1, inclusive. 11. The method according to claim 9 or 10, Step (c) is a congestion control method characterized in that the first reset of at least one of the slow start threshold (Ssthresh) and the congestion window (cwnd) using the following equation. [Equation] Slow start Threshold = _current slow start threshold _before Congestion window _present = 2 Х Congestion window _present In a recording medium on which a program of instructions that can be executed by a congestion control device is implemented to perform congestion control, and which records a program that can be read by the congestion control device, (a) driving a verification timer when receiving a duplicate response; (b) If the number of duplicate responses received is greater than or equal to the duplicate response threshold, one of Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, and Fast Recovery. Performing a first congestion control using the above; And (c) Verifying that packet reordering has occurred when receiving an acknowledgment according to the first congestion control before the verification timer expires, the duplicate response threshold, Slow Start threshold, Ssthresh And a program for executing a first reset of one or more of a congestion window (Cwnd). The method of claim 13, After step (a) but before step (b) (d1) Additive Increase / Multiplicative Decrease, Slow Start, Fast Retransmit, if the number of duplicated responses received is less than the duplicated response threshold and the verification timer expires. Performing a second congestion control using at least one of Fast Recovery and Fast Recovery; And (d2) a recording medium having recorded thereon a program for executing the second reset of the duplicate response threshold value according to the second congestion control. The method according to claim 13 or 14, Step (c) is the equation

And a first reset of the duplicate response threshold using a recording medium. Where dt is the duplicate response threshold, dt _s is the new value to be reset to the duplicate response threshold, and dt _pre is The previous duplicate response threshold, dt _M is the number of duplicate responses received when verifying packet relocation, and α is a specified real number between 0 and 1, inclusive. The method according to claim 13 or 14, Step (c) is a recording medium recording a program, characterized in that for resetting the at least one of the slow start threshold (Ssthresh) and the congestion window (cwnd) using the following equation. [Equation] Slow start Threshold = _current slow start threshold _before Congestion window _present = 2 Х Congestion window _present

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