JP2014027444A - Transmission buffer size estimation device, transmission buffer size estimation method, and transmission buffer size estimation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a maximum value of a transmission buffer size of a transmitter without depending on transmission processing performance of the transmitter.SOLUTION: A transmission buffer size estimation device receives a data packet transmitted from a transmitter 300 and stores the received data in a reception buffer 12; transmits an ACK response to the received data to the transmitter 300, after the received data is processed and the reception buffer 12 becomes empty; calculates a transmission buffer size for the transmitter 300 from difference between a sequence number of the received data and a confirmation response number of the ACK response; and compares the calculated transmission buffer size with a previously calculated transmission buffer size and takes the maximum value as a transmission buffer size of the transmitter 300.

Description

  The present invention relates to a technique for estimating a transmission buffer size of a data transmission apparatus.

  Computers deployed on a communication network such as the Internet are roughly classified into a transmission device that transmits data in response to a request from the client side and a reception device that receives the data returned from the server side that makes the request. The

  Each of these devices realizes data transfer by communication, but an event that the communication speed becomes slow may occur during data transfer. There are various causes of the event. One of the causes is that the transmission buffer capacity of the transmission device is insufficient, and the data transfer efficiency between the devices may be reduced.

  However, since the transmission buffer size is a value that is normally undisclosed that is uniquely determined by the transmission device, it is necessary to investigate the device specifications and allocated capacity of the transmission device that is the communication destination in order to know it. It is difficult to obtain the actual value with the device.

  In this regard, according to the prior art of Patent Document 1, a technique for estimating the maximum capacity of a retransmission buffer of a transmission device based on retransmitted data by not actively performing a reception response to data from the transmission device. Is disclosed.

  That is, an ACK response is not returned for the data transmitted from the transmission apparatus, and the data is stored in the retransmission buffer of the transmission apparatus. Thereafter, when the retransmission timer expires, the data stored in the retransmission buffer is retransmitted, and the retransmission buffer size is estimated by measuring the number of retransmissions.

JP 2011-61536 A

  However, when an algorithm for gradually increasing the amount of transmission data with the passage of time is applied in the transmission processing of the transmission apparatus, even if the conventional technique of Patent Document 1 is used, the transmission buffer of the transmission apparatus The size cannot be estimated accurately.

  That is, for example, according to the slow start algorithm, if the number of segments to be transmitted gradually increases and then the retransmission timer expires, it is determined that congestion has occurred in the communication network and the amount of transmission data is reduced. (Refer to FIG. 6) Since this suppresses the amount of data stored in the retransmission buffer, it is possible to estimate the size of the retransmission buffer used at that time, but the actual allocation or device specification is possible. It is difficult to estimate the upper retransmission buffer size.

  The present invention has been made in view of the above problems, and an object of the present invention is to estimate the maximum value of the transmission buffer size of the transmission device without depending on the transmission processing performance of the transmission device.

  The transmission buffer size estimation device according to claim 1, wherein the transmission buffer size estimation device receives a data packet transmitted from the transmission device and stores the reception data in a reception buffer; and the reception data is processed and the reception buffer is empty. After that, the data transmission means for transmitting an acknowledgment for the received data to the transmitting device, and the estimated value of the transmission buffer size of the transmitting device based on the control data related to the received data or the usage status of the receiving buffer Buffer size estimation means for calculating and using the maximum value as a transmission buffer size of the transmission device in comparison with the previously calculated estimation value.

  According to the present invention, a data packet transmitted from a transmitting apparatus is received, the received data is stored in a reception buffer, and an acknowledgment for the received data is transmitted after the received data is processed and the reception buffer becomes empty. The transmission buffer size of the transmission device is calculated based on the control data related to the received data or the usage status of the reception buffer, and compared with the previously calculated estimation value. Since the data size transmitted from the transmission device is always maximized because of the size, the maximum value of the transmission buffer size of the transmission device can be estimated without depending on the transmission processing performance of the transmission device.

  The transmission buffer size estimation device according to claim 2 is the transmission buffer size estimation device according to claim 1, wherein the buffer size estimation means calculates the difference between the sequence number of the reception data and the confirmation response number of the confirmation response. An estimated value of the transmission buffer size is calculated.

  4. The transmission buffer size estimation device according to claim 3, wherein the buffer size estimation means is configured to calculate the transmission buffer size from a buffer usage amount of the reception data stored in the reception buffer. It is characterized by calculating an estimated value of.

  The transmission buffer size estimation device according to claim 4 is the transmission buffer size estimation device according to any one of claims 1 to 3, wherein the data packet transmits the confirmation response after transmitting the confirmation response. Or one or more segments received during the period.

  The transmission buffer size estimation method according to claim 5, wherein a computer receives a data packet transmitted from a transmission device and stores the received data in a reception buffer; and the reception data is processed and the reception is performed. After the buffer is emptied, a data transmission step of transmitting an acknowledgment for the received data to the transmitting device, and the transmission buffer size of the transmitting device based on the control data related to the received data or the usage status of the receiving buffer A buffer size estimating step of calculating an estimated value and comparing the estimated value with a previously calculated estimated value and setting a maximum value as a transmission buffer size of the transmitting apparatus.

  A transmission buffer size estimation program according to claim 6 causes a computer to execute the transmission buffer size estimation method according to claim 5.

  According to the present invention, it is possible to estimate the maximum value of the transmission buffer size of the transmission device without depending on the transmission processing performance of the transmission device.

It is a figure which shows the functional block structure of a receiver. It is a figure which shows the processing flow of a receiver. FIG. 3 is a reference diagram of the processing flow of FIG. 2. It is a figure which shows the processing flow of a receiver. FIG. 5 is a reference diagram of the processing flow of FIG. 4. It is explanatory drawing of a prior art.

  Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different modes and should not be construed as being limited to the description of the present embodiment.

  In the first embodiment, the TCP header information (control data) of the data packet communicated between the transmission device and the reception device is used. In the second embodiment, the use status of the reception buffer of the reception device. A method for estimating the transmission buffer size of the transmission apparatus will be described using FIG.

[First Embodiment]
In the first embodiment, as an example, a method for estimating a transmission buffer size from the difference between a sequence number and an acknowledgment number will be described.

  First, a general communication flow control technique between computers will be described. When performing data communication between two computers connected to a communication network, a data transfer request is made from a client-side receiving device to a server-side transmitting device, and the data transfer processing from the transmitting device to the receiving device is triggered by this request. Be started.

  When the receiving device receives the segment of the transfer target data, it immediately returns an ACK response. After receiving the ACK response, the transmitting device transmits the next segment according to the reception buffer size of the receiving device.

  The reception buffer size referred to here is the usage amount or usage rate of the reception buffer, and the transmission apparatus changes the number of segments scheduled to be transmitted according to the usage status. For example, even if the maximum value of the reception buffer size is 5000 bytes, if 1000 bytes are being used, the next segment is transmitted with a maximum value of 4000 bytes.

  In the transmission apparatus, data transmission between computers is realized by repeatedly performing the transmission process while sequentially shifting the window indicating the segment to be transmitted to the segment at the subsequent position.

  Such flow control is generally called a sliding window method, and is usually used in a connection type protocol such as TCP (Transmission Control Protocol). It is assumed that the transmission apparatus to be used below is mounted with such TCP.

  In addition, the transmission device uses a slow start algorithm during data transmission processing. The slow start algorithm is an algorithm that performs transmission processing by gradually increasing the amount of data to be transmitted. While receiving the ACK response, data communication between computers is realized by gradually increasing the number of segments transmitted at a time.

  Therefore, since the transmission apparatus according to the present embodiment performs transmission processing using the sliding window method and the slow start algorithm, for example, when one segment is first transmitted and an ACK response is received, the next segment is selected. Send two. Here, assuming that one segment size is 1000 bytes, 3000 bytes are used out of 5000 bytes, which is the maximum value of the reception buffer size at the present time, so the next transmission process is executed with the remaining 2000 bytes as the maximum value. Will do.

  On the other hand, for such a transmission apparatus, a reception apparatus that receives data from the transmission apparatus has a transmission buffer size estimation function for estimating the transmission buffer size of the transmission apparatus, and has a plurality of functions as shown in FIG. Department. FIG. 1 is a diagram illustrating a functional block configuration of a receiving apparatus (transmission buffer size estimating apparatus).

  The receiving device 100 is communicably connected to the transmitting device 300 via a communication network 500 such as the Internet or an in-house LAN (Local Area Network), and includes a data receiving unit 11, a receiving buffer 12, and a data information acquiring unit. 13, a memory 14, a data transmission unit 15, and a buffer size estimation unit 16. Hereinafter, each functional unit will be described.

  The data reception unit 11 has a function of receiving a data packet transmitted from the transmission device 300 through the communication network 500 and storing the received data in the reception buffer 12.

  The data information acquisition unit 13 has a function of acquiring the sequence number of the received data, further acquiring the confirmation response number of the ACK response made for the reception, and storing it in the memory 14.

  The data transmission unit 15 always maximizes the data size transmitted from the transmission device 300, so that the usage amount or usage rate of the reception buffer 12 becomes zero, that is, after the reception buffer 12 becomes empty. It has a function of performing an ACK response (acknowledgment response) to received data.

  The buffer size estimation unit 16 calculates an estimated value of the transmission buffer size of the transmission device 300 from the difference between the sequence number in the memory 14 and the acknowledgment number, and compares the estimated value with the previously calculated estimation value to determine the maximum value. It has a function to set the transmission buffer size.

  Such a receiving apparatus 100 can be realized by a computer including a storage unit such as a memory, a calculation / control unit such as a CPU, and a display unit such as a monitor. Further, processing performed by the receiving apparatus 100 can be executed by a program.

  Note that FIG. 1 mainly shows characteristic function units considered necessary for the description of the present invention. However, existing functions that the receiving apparatus originally has as a computer, for example, data in the receiving buffer 12 are processed. Of course, the function to delete is also provided.

  Next, the operation of the receiving apparatus 100 will be described with reference to FIGS. FIG. 2 is a diagram illustrating a processing flow of the receiving apparatus. FIG. 3 is a reference diagram of the processing flow. In order to reliably estimate the transmission buffer size, it is assumed that the capacity of the reception buffer 12 (reception buffer size) is sufficiently larger than the transmission buffer size.

  First, in response to a data transfer request from the receiving apparatus 100 to the transmitting apparatus 300, a three-way handshake is performed between the receiving apparatus 100 and the transmitting apparatus 300, and a maximum segment size (MSS) is obtained. After the decision is made, a session is established. For example, the MSS is determined to be 1000 bytes.

  Next, the data receiving unit 11 of the receiving device 100 receives the packet transmitted from the transmitting device 300 through the communication network 500 (step S101), and whether the type of the packet is a fin packet (Yes) or not (No) ) Is determined (step S102).

  If the determination result in step S102 is No, if the data transfer process is not terminated after the session is established, the data reception unit 11 stores the segment in the syn packet in the reception buffer 12 because the syn packet is mainly received. (Step S103).

  Subsequently, the data receiving unit 11 determines whether the reception of the syn packet is continued (Yes) or not (No) (Step S104). If Yes, the process returns to Step S103 to select the next segment being received. Store in the reception buffer 12.

  On the other hand, if the determination result in step S104 is No, the data information acquisition unit 13 acquires the sequence number SEQ # (Sequence Number) of the received segment and stores it in the memory 14 (step S105).

  The sequence number is a number that is arbitrarily given by the transmitting device 300 when the data transfer is first, and is given according to the ACK response received from the receiving device 100, and is obtained from the TCP header of the packet. Can do.

  For example, when only the segment having the sequence number SEQ # = 1 is initially received by the slow start algorithm, only the SEQ # = 1 is stored in the memory 14.

  Next, after the data processing by the receiving apparatus 100 is completed for the segment in the reception buffer 12 (step S106), the data information acquisition unit 13 uses the reception buffer 12 in zero or the usage rate, that is, receives data. It is determined whether the buffer 12 is empty (Yes) or not (No) (step S107).

  The data processing here is processing for arbitrarily processing a segment in the receiving buffer and deleting it from the receiving buffer 12, and is generally executed by the receiving device 100 as a computer in order to make free space in the receiving buffer. Process.

  Next, when the determination result in step S107 is Yes, the data information acquisition unit 13 calculates the minimum number m by acquiring and comparing all sequence numbers SEQ # stored in the memory 14 (step S108). .

  According to the above example, since only SEQ # = 1 is stored in the memory 14, in this case, m = 1 is set without performing comparison. If the determination result in step S107 is No, the process returns to step S105, and the received sequence number SEQ # of the next segment is acquired and stored in the memory 14.

  Next, the data information acquisition unit 13 instructs the data transmission unit 15 to return an ACK response in order to respond to the transmission device 300 that the data transfer of the segment transmitted from the transmission device 300 has been normally completed. The data transmission unit 15 adds an acknowledgment number ACK # (Acknowledgement Number) and transmits an ACK response to the transmission device 300 (step S109).

  According to the above example, only the segment with the sequence number SEQ # = 1 is received, and since MSS = 1000, the data from the 1001st is required next, so the acknowledgment number ACK # = 1001 is given. Send an ACK response.

  Here, in the conventional case, an ACK response is transmitted immediately after the segment is received. In the case of the prior art disclosed in Patent Document 1, the buffer size is estimated using a retransmission timer without performing an ACK response.

  On the other hand, in this embodiment, transmission of the ACK response is intentionally delayed, and the ACK response is performed after the reception buffer 12 becomes empty. As described above, the transmission device 300 adjusts the number of segments according to the reception buffer size of the reception device 100 (the usage amount and usage rate of the reception buffer 12), and therefore transmits the ACK after emptying the reception buffer 12. By performing the response, the number of segments transmitted from the transmission device 300 can always be maximized.

  If the maximum value of the reception buffer size is 10000 bytes, the transmission apparatus 300 can always perform all transmission processes with the maximum value of 10000 bytes. Therefore, the buffer size estimation unit 16 at the subsequent stage can accurately calculate the maximum value of the transmission buffer size of the transmission apparatus 300.

  Next, the data information acquisition unit 13 acquires the acknowledgment number ACK # of the ACK response transmitted to the transmission device 300 in step S109 and stores it in the memory 14 (step S110). According to the above example, since the acknowledgment number ACK # = 1001, the ACK # = 1001 is stored in the memory 14.

  Next, the data information acquisition unit 13 calculates the maximum number M by acquiring and comparing all the acknowledgment number ACK # stored in the memory 14 (step S111). According to the above example, only ACK # = 1001 is stored in the memory 14 as an acknowledgment number, and in this case, M = 1001 without comparison.

  Next, the buffer size estimation unit 16 calculates the difference between the minimum number m and the maximum number M, and sets it as the current value Buffer1 (= M−m) of the transmission buffer size (step S112). According to the above example, since m = 1 and M = 1001 are calculated, Buffer1 = 1000 is calculated.

  Next, the buffer size estimation unit 16 compares the current value Buffer1 of the transmission buffer size with the previously calculated value Buffer2 of the transmission buffer size obtained previously, and the maximum value Buffer3 (= Max {Buffer1, Buffer2} of the transmission buffer size) ) Is calculated (step S113). When the initial value of Buffer2 is set to 0, according to the above example, Buffer3 = 1000 is calculated.

  Next, the buffer size estimation unit 16 sets the maximum value Buffer3 of the transmission buffer size as the previous calculated value Buffer2 (step S114). According to the above example, Buffer2 = 1000 is calculated.

  Next, the buffer size estimation unit 16 deletes the sequence number and the acknowledgment number from the memory 14, and clears the current value Buffer1 and the maximum value Buffer3 of the transmission buffer size (step S115).

  Thereafter, the estimation processing in steps S101 to S115 is repeatedly executed until the determination result in step S102 becomes Yes.

  For example, when the estimation process is performed for the second time, the segment of sequence number SEQ # = 1001, 2001 (ACK response of acknowledgment number ACK # = 1001 is transmitted and each ACK response of next acknowledgment number ACK # = 2001, 3001 is transmitted. 2 segments received until the time of transmission is received, m = 1001 is calculated, and since acknowledgment numbers ACK # = 2001 and 3001, M = 3001 is calculated, and Buffer1 = 3001 -1001 = 2000, Buffer3 = Max {2000,1000} = 2000 = Buffer2

  Further, in the third estimation process, segments of sequence numbers SEQ # = 3001, 4001, 5001, 6001 (acknowledgment number ACK # = 2001, 3001 ACK responses are transmitted and the next acknowledgment number ACK # = 4 segments received before transmitting each ACK response of 4001, 5001, 6001, 7001), m = 3001 is calculated, and the acknowledgment number ACK # = 4001,5001,6001, Since 7001, M = 7001 is calculated, and Buffer1 = 7001-3001 = 4000, Buffer3 = Max {4000,2000} = 4000 = Buffer2 is calculated.

  Thereafter, when the transfer processing for all segments is completed and a fin packet is received, the previous calculation value Buffer2 is set as the estimation result of the transmission buffer size of the transmission device 300, and the session with the transmission device 300 is disconnected (step S116). .

  According to the present embodiment, the data packet transmitted from transmitting apparatus 300 is received, the received data is stored in reception buffer 12, and the received data is processed and received buffer 12 is emptied. Is transmitted to the transmitting apparatus 300, the transmission buffer size of the transmitting apparatus 300 is calculated from the difference between the sequence number of the received data and the acknowledgment number of the ACK response, and the maximum is compared with the previously calculated transmission buffer size. Since the value is set to the transmission buffer size of the transmission device 300, the number of segments transmitted from the transmission device 300 is always maximized. Even for the transmission device 300 to be used, the maximum value of the transmission buffer size of the transmission device 300 is set. It can be constant.

  As a result, a decrease in communication speed due to insufficient transmission buffer capacity of the transmission device 300 can be grasped at a remote location. For example, the administrator of the transmission device 300 sets the transmission buffer size of the transmission device 300 to an appropriate value according to the estimation result. It is possible to speed up communication by making adjustments such as correction / expansion and releasing the limit capacity of the transmission buffer only when communicating with a specific partner. The same applies to a second embodiment to be described later.

  Further, in the case of the conventional technique of Patent Document 1, the estimated time of the transmission buffer size depends on the retransmission timer of the transmission device 300. On the other hand, in the case of the present embodiment, the delay of the ACK response that greatly affects the estimated time depends on the receiving device 100, not the transmitting device 300, and therefore it is possible to provide an estimated time that is not affected by other devices. The same applies to a second embodiment to be described later.

  In this embodiment, the difference between the sequence number and the acknowledgment number is used when calculating the transmission buffer size. However, the data size included in the data column in the TCP header information is used as it is as the transmission buffer size. May be.

  In this embodiment, the case where transmission processing is performed using the slow start algorithm is taken as an example. However, if the maximum value is calculated compared to the transmission buffer size calculated in the past, the transmission buffer size of the transmission device 300 is set. Since it can be estimated, the transmission apparatus 300 having an arbitrary algorithm can be set as an estimation target without being limited to such an algorithm. The same applies to a second embodiment to be described later.

[Second Embodiment]
In the second embodiment, as an example, a method for estimating the transmission buffer size from the buffer usage of the reception buffer will be described. The receiving apparatus 100 according to the present embodiment is configured by the same functional units as those in the first embodiment (see FIG. 1). Hereinafter, each functional unit will be described.

  The data reception unit 11 has a function of receiving a data packet transmitted from the transmission device 300 through the communication network 500 and storing the received data in the reception buffer 12.

  The data information acquisition unit 13 has a function of acquiring the buffer usage of the reception buffer 12 used for the reception data and storing it in the memory 14.

  The data transmission unit 15 always maximizes the data size transmitted from the transmission device 300, so that the usage amount or usage rate of the reception buffer 12 becomes zero, that is, after the reception buffer 12 becomes empty. It has a function to make an ACK response to received data.

  The buffer size estimation unit 16 calculates an estimated value of the transmission buffer size of the transmission device 300 from the buffer usage in the memory 14, and compares the estimated value with a previously calculated estimation value to the transmission buffer size of the transmission device 300. It has a function to do.

  Next, the operation of the receiving apparatus 100 will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram illustrating a processing flow of the reception apparatus. FIG. 5 is a related reference diagram of the processing flow.

  First, triggered by a data transfer request from the receiving apparatus 100 to the transmitting apparatus 300, a three-way handshake is performed between the receiving apparatus 100 and the transmitting apparatus 300, and a session is established. For example, the MSS is determined to be 1000 bytes.

  Next, the data receiving unit 11 of the receiving device 100 receives the packet transmitted from the transmitting device 300 through the communication network 500 (step S201), and whether the type of the packet is a fin packet (Yes) or not (No) ) Is determined (step S202).

  When the determination result in step S202 is No, when the data transfer process is not terminated after the session is established, the syn packet is mainly received. Therefore, the data reception unit 11 stores the segment in the syn packet in the reception buffer 12. (Step S203).

  Subsequently, the data receiving unit 11 determines whether the reception of the syn packet is continued (Yes) or not (No) (Step S204). If Yes, the process returns to Step S203 to select the next segment being received. Store in the reception buffer 12.

  On the other hand, if the determination result in step S204 is No, the data information acquisition unit 13 acquires the buffer usage amount UBS (Used Buffer Size) of the segment stored in the reception buffer 12 and stores it in the memory 14 (step S205). .

  For example, when only one segment is initially received and stored in the reception buffer 12 by the slow start algorithm, the buffer usage of the reception buffer 12 is calculated as 1000 bytes because the MSS is 1000 bytes. Only UBS = 1000 is stored in the memory 14.

  Next, after the data processing by the receiving apparatus 100 is completed for the segment in the reception buffer 12 (step S206), the data information acquisition unit 13 uses the reception buffer 12 in zero or the usage rate, that is, receives data. It is determined whether the buffer 12 is empty (Yes) or not (No) (step S207).

  Next, when the determination result in step S207 is Yes, the data information acquisition unit 13 returns an ACK response to respond to the transmission apparatus 300 that the data transfer of the segment transmitted from the transmission apparatus 300 has been normally completed. The data transmission unit 15 is instructed to do so, and the data transmission unit 15 transmits an ACK response to the transmission device 300 with an acknowledgment number ACK # (step S208). Refer to the first embodiment for the operational effect of ACK response after the reception buffer 12 becomes empty.

  Next, the buffer size estimation unit 16 acquires the buffer usage from the memory 14 and sets it as the current value Buffer1 of the transmission buffer size (step S209). According to the above example, since UBS = 1000, Buffer 1 = 1000 is calculated.

  Next, the buffer size estimation unit 16 compares the current value Buffer1 of the transmission buffer size with the previously calculated value Buffer2 of the transmission buffer size obtained previously, and the maximum value Buffer3 (= Max {Buffer1, Buffer2} of the transmission buffer size) ) Is calculated (step S210). When the initial value of Buffer2 is set to 0, according to the above example, Buffer3 = 1000 is calculated.

  Next, the buffer size estimation unit 16 sets the maximum value Buffer3 of the transmission buffer size as the previous calculated value Buffer2 (step S211). According to the above example, Buffer2 = 1000 is calculated.

  Next, the buffer size estimation unit 16 deletes the buffer usage from the memory 14 and clears the current value Buffer1 and the maximum value Buffer3 of the transmission buffer size (step S212).

  Thereafter, the estimation processing in steps S201 to S212 is repeatedly executed until the determination result in step S202 becomes Yes.

  For example, when the estimation process is performed for the second time and two segments are received, UBS = 2000 is calculated, and Buffer1 = 2000, Buffer3 = Max {2000,1000} = 2000 = Buffer2.

  For example, when four segments are received in the third estimation process, UBS = 4000 is calculated, Buffer1 = 4000, Buffer3 = Max {4000,2000} = 4000 = Buffer2.

  Thereafter, when the transfer processing for all segments is completed and the fin packet is received, the previous calculation value Buffer2 is set as the estimation result of the transmission buffer size of the transmission device 300, and the session with the transmission device 300 is disconnected (step S213). .

  According to the present embodiment, the data packet transmitted from transmitting apparatus 300 is received, the received data is stored in reception buffer 12, and the received data is processed and received buffer 12 is emptied. Is transmitted to the transmission device 300, the transmission buffer size of the transmission device 300 is calculated from the buffer usage of the segments stored in the reception buffer 12, and the maximum value is transmitted compared with the previously calculated transmission buffer size. Since the transmission buffer size of the device 300 is used, the number of segments transmitted from the transmission device 300 is always maximized. Therefore, a transmission device that uses a slow start algorithm at the time of transmission processing without depending on the transmission processing performance of the transmission device 300 Even if it is 300, the maximum value of the transmission buffer size of the transmission device 300 is estimated. Rukoto can.

  In the present embodiment, the transmission buffer size is estimated from the buffer usage of the reception buffer 12, but the reception device 100 knows the maximum size of the reception buffer 12 in its own device, and therefore uses the buffer usage rate. The usage amount may be calculated.

DESCRIPTION OF SYMBOLS 100 ... Reception apparatus 11 ... Data reception part 12 ... Reception buffer 13 ... Data information acquisition part 14 ... Memory 15 ... Data transmission part 16 ... Buffer size estimation part 300 ... Transmission apparatus 500 ... Communication network S101-S116, S201-S213 ... Step

Claims (6)

Data receiving means for receiving a data packet transmitted from a transmitting device and storing the received data in a reception buffer;
Data transmitting means for transmitting an acknowledgment for the received data to the transmitting device after the received data is processed and the receive buffer is emptied;
Calculate an estimated value of the transmission buffer size of the transmission device based on the control data related to the received data or the usage status of the reception buffer, and compare the estimated value calculated previously with the maximum value to the transmission buffer size of the transmission device Buffer size estimation means
A transmission buffer size estimation apparatus comprising: The buffer size estimation means includes:
2. The transmission buffer size estimation apparatus according to claim 1, wherein an estimated value of the transmission buffer size is calculated from a difference between a sequence number of the received data and an acknowledgment number of the acknowledgment. The buffer size estimation means includes:
2. The transmission buffer size estimation device according to claim 1, wherein an estimated value of the transmission buffer size is calculated from a buffer usage amount of the reception data stored in the reception buffer. The data packet is
4. The transmission buffer size estimation apparatus according to claim 1, wherein the transmission buffer size estimation apparatus is one or more segments received between the transmission of the confirmation response and the transmission of the next confirmation response. By computer
A data reception step of receiving a data packet transmitted from the transmission device and storing the received data in a reception buffer;
A data transmission step of transmitting an acknowledgment to the reception data to the transmission device after the reception data is processed and the reception buffer is empty;
Calculate an estimated value of the transmission buffer size of the transmission device based on the control data related to the received data or the usage status of the reception buffer, and compare the estimated value calculated previously with the maximum value to the transmission buffer size of the transmission device A buffer size estimation step, and
A transmission buffer size estimation method characterized by comprising:   A transmission buffer size estimation program for causing a computer to execute the transmission buffer size estimation method according to claim 5.

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