JP2015015555A - Device, method and program for transmission rate control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission rate control device capable of appropriately control a parallel simulation parameter to effectively improve a throughput.SOLUTION: A transmission rate control device for controlling a transmission rate when transmitting data using a plurality of parallel connections simulated in a connection at the same time includes: communication network state monitor means 3 for monitoring the communication state of a communication network; parallel simulation parameter change means 4 for increasing or decreasing a value of a parallel simulation parameter capable of identifying the number of parallel connections, on the basis of connection state information indicative of the communication state; and congestion control means 2 for determining the transmission rate on the basis of the parallel simulation parameter changed by the parallel simulation parameter change means 4.

Description

  The present invention relates to a transmission rate control device, a transmission rate control method, and a transmission rate control program capable of efficiently adjusting a transmission rate according to the state of a communication network.

  With the progress of technology, the data transfer speed of communication network devices is rapidly increasing. However, the data transfer technology using TCP (Transmission Control Protocol) does not fully use the performance of the communication network, and the problem that the throughput (transmission efficiency) in the data transfer is low has emerged against the increase in data transfer speed. ing.

  Specifically, in general TCP congestion control, the transmission rate improvement speed is slow. In addition, the amount of decrease in the transmission rate when congestion is detected is large. For this reason, once congestion is detected, it takes a long time until the transmission rate in data transfer reaches a transmission rate that can use up the performance of the communication network.

  In order to solve the above problems, efforts are being made to improve TCP congestion control. One of the approaches is MulTCP described in Non-Patent Document 1.

  MulTCP described in Non-Patent Document 1 pays attention to improving throughput by transmitting data by using a plurality of TCP connections in combination, and N parallel TCP connections in one TCP connection. And the congestion window size cwnd is adjusted.

  Specifically, when a normal ACK (ACKnowledgement) packet (acknowledgment response) is received, cwnd is increased or decreased as in Expression (1). Also, when duplicate ACK packets are received three times in succession, cwnd is increased or decreased as in equation (2).

  cwnd = cwnd + N / cwnd Formula (1)

  cwnd = cwnd × (N−0.5) / N (2)

  By performing the congestion control as described above, MulTCP quickly uses up the performance of the communication network by simulating a parallel TCP connection. As a result, MulTCP can improve the throughput in data transfer.

  Further, Patent Document 1 describes a method for reducing the number of paths for reducing power consumption. In the method for reducing the number of routes described in Patent Document 1, the usage rate of each route is biased, and the usage rate of the route to be reduced is set to 0, and then the route is reduced.

JP 2012-039303 A

J. et al. Crowcroft and P.C. Oechslin, “Differentiated End-to-End Internet Services using a Weighted Proportional Fair Sharing Sharing TCP,” ACM Computer Communication Review, vol. 28, issue 3, pp. 53-69, ACM New York, NY, USA, July 1998.

  In data transmission using parallel TCP connections, MulTCP that simulates parallel TCP connections, etc., if the parallel simulation parameter that simulates the number of parallel TCP connections and the number of connections is increased, the throughput is up to a certain extent. improves.

  However, if the number of TCP connections and the parallel simulation parameters are increased too much, congestion control is over-controlled and packet loss is induced. That is, in data transmission using parallel TCP connections, MulTCP that simulates parallel TCP connections, and the like, if the number of TCP connections and parallel simulation parameters are too large, the throughput may decrease.

  In other words, when using a parallel TCP connection or MulTCP that simulates a parallel TCP connection, the problem is to appropriately adjust the number of TCP connections and parallel simulation parameters according to the state of the communication network that changes from moment to moment. is there.

  Also, with the method described in Patent Document 1, it is possible to reduce routes without causing waste in communication network performance. However, this method has a problem that it takes time to reduce the route.

  Therefore, the present invention provides a transmission rate control apparatus, a transmission rate control method, and a transmission rate control program that can appropriately control parallel simulation parameters and effectively improve throughput.

  A transmission rate control apparatus according to the present invention is a transmission rate control apparatus for controlling a transmission rate when data is transmitted using a plurality of parallel connections simulated in a connection, and the communication state of a communication network Communication network status monitoring means for monitoring, parallel simulation parameter changing means for increasing / decreasing a parallel simulation parameter capable of specifying the number of a plurality of parallel connections based on communication status information indicating the communication status, and parallel simulation parameter change And a congestion control means for determining a transmission rate based on a parallel simulation parameter by the means.

  The transmission rate control method according to the present invention is a transmission rate control method executed in a transmission rate control device that controls a transmission rate when data is transmitted using a plurality of parallel connections simulated in a connection. Thus, the communication status of the communication network is monitored, and the parallel simulation parameter capable of specifying the number of parallel connections is increased or decreased based on the communication status information indicating the communication status. The transmission rate is determined based on the above.

  The transmission rate control program according to the present invention is a transmission rate control program executed in a transmission rate control apparatus that controls a transmission rate when data is transmitted using a plurality of parallel connections simulated in the connection. In the transmission rate control device, the monitoring process for monitoring the communication state of the communication network, the parallel simulation parameter that can specify the number of parallel connections, the increase / decrease to increase / decrease based on the communication state information indicating the communication state And a determination process for determining a transmission rate based on the parallel simulation parameter increased or decreased.

  According to the present invention, it is possible to appropriately control the parallel simulation parameters and effectively improve the throughput.

1 is a system configuration diagram showing a configuration example of a first embodiment of a transmission rate control apparatus according to the present invention. 2 is a block diagram illustrating a configuration example of a first embodiment of a data transmission device 20. FIG. 4 is a flowchart showing an operation of a parallel simulation parameter increasing process of the first embodiment of the data transmission device 20. 4 is a flowchart illustrating an operation of a parallel simulation parameter reduction process of the first embodiment of the data transmission device 20. It is a block diagram which shows the structural example of 2nd Embodiment of the user terminal. It is a block diagram which shows the structural example of 2nd Embodiment of the data transmitter. It is a flowchart which shows the operation | movement of the parallel simulation parameter reduction process of 2nd Embodiment of the data transmitter. It is a block diagram which shows the outline | summary of the transmission rate control apparatus by this invention.

Embodiment 1. FIG.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram showing a configuration example of a first embodiment of a transmission rate control apparatus according to the present invention.

  A transmission rate control system 100 shown in FIG. 1 includes a user terminal 10 and a data transmission device 20 that is a transmission rate control device. The user terminal 10 is connected to the data transmission device 20 via the communication network 30 so as to be communicable.

  The user terminal 10 is a terminal used by a user to request and acquire data via the communication network 30 or the data transmission device 20. The user terminal 10 is, for example, a PC (Personal Computer). Note that the user terminal 10 may be a mobile terminal or the like.

  When a user requests data acquisition, the user terminal 10 transmits a data request to the data transmission device 20 or the origin server via the communication network 30. Then, when the data requested by the user is distributed from the data transmission device 20 or the origin server, the user terminal 10 presents the distributed data to the user.

  The data transmission device 20 is a device that establishes a connection such as TCP to the user terminal 10 and transmits data requested by the user terminal 10. In this embodiment, the case where the data transmission apparatus 20 establishes a TCP connection with the user terminal 10 is taken as an example. The data transmission device 20 is, for example, an origin server that holds data requested by a user.

  Further, the data transmission device 20 may be a relay server device that is installed in the communication network 30 and terminates data communication between the origin server and the user terminal 10 once. In other words, the data transmission device 20 may be arranged in the middle of a route through which the origin server transmits data to the user terminal 10. In this case, the data transmission device 20 is a cache server, a proxy server, an edge server, or the like.

  In the above case, there is another communication network (not shown) behind the data transmission device 20 when viewed from the user terminal 10, an origin server or the like (not shown) that holds data requested from the user terminal 10. Also good.

  Further, the data transmission device 20 may be a data communication device that constitutes the communication network 30. In this case, the data transmission device 20 is a P-GW (Packet Data Network Gateway), an S-GW (Serving Gateway), or the like.

  Next, a detailed configuration of the data transmission device 20 will be described with reference to FIG. FIG. 2 is a block diagram illustrating a configuration example of the data transmission device 20 according to the first embodiment.

  The data transmission apparatus 20 shown in FIG. 2 includes data transmission / reception means 21, congestion control means 22, communication network state monitoring means 23, burst loss detection means 24, and parallel simulation parameter change means 25.

  The data transmission / reception unit 21 has a function of transmitting data based on the congestion window size and transmission rate set in the congestion control unit 22. In addition, when the data transmitting / receiving unit 21 receives an ACK packet from the user terminal 10, the data transmitting / receiving unit 21 notifies the congestion control unit 22, the communication network state monitoring unit 23, and the burst loss detection unit 24 of the received ACK packet information. It has a function.

  When the data transmission / reception means 21 obtains a data request message from the user terminal 10, the data transmission / reception means 21 transmits the requested data to the user terminal 10 by TCP based on the congestion window size and the transmission rate set in the congestion control means 22. To do.

  Further, when the data transmission / reception means 21 receives an ACK packet for the transmission packet from the user terminal 10 during data transmission, the data transmission / reception means 21 receives the state information of the communication network 30 and the information described in the received ACK packet as the congestion control means 22. To the communication network state monitoring means 23 and the burst loss detecting means 24.

  The information notified to the congestion control means 22 is, for example, a round trip time RTT (Round Trip Time) required for data transmission, an ACK sequence number described in the received ACK packet, and a reception window size RWIN (Receive Window). .

  In addition to the above, the information notified to the congestion control unit 22 may include information exchanged by normal TCP communication. Information exchanged by normal TCP communication includes time stamp information TSval (TS Value), TSecr (TS Echo Reply), ECN (Explicit Connection Notification) option information, etc. described in the received ACK packet. is there.

  The information notified to the communication network state monitoring unit 23 is, for example, a round trip delay time RTT related to data transmission. Further, the information notified to the communication network state monitoring unit 23 is not limited to the above, and may be information that can be measured or acquired by normal TCP communication. Information that can be measured or acquired by normal TCP communication includes a packet loss occurrence notification in data transmission.

  The information notified to the burst loss detection means 24 is a packet loss occurrence notification. The packet loss occurrence notification is a partial packet non-arrival notification obtained by using the extended function. The extended function used in the packet loss occurrence notification includes, for example, a function using a SACK (Selective Acknowledgment) option or a NACK (Negative Acknowledgment) packet.

  Further, the packet loss occurrence notification is not limited to the above, and may be an arrival notification of a duplicate ACK packet that is a possibility of packet loss.

  Further, when the data transmission device 20 is an origin server, the data transmission device 20 holds all original data therein. Therefore, the data transmission / reception means 21 can transmit data with the congestion window size and transmission rate set in the congestion control means 22.

  Further, when the data transmission device 20 is a relay server device or a data communication device, the data transmission device 20 can replicate the original data as a cache in its own storage area in advance. Further, the data transmission device 20 can temporarily store a data stream transmitted from the origin server as a buffer. As a result, the data transmission / reception means 21 does not depend on the throughput of the communication network (not shown) between the origin server and the data transmission apparatus 20, and the data is transmitted with the congestion window size and transmission rate set in the congestion control means 22. Can be sent.

  As a method for acquiring a data request message by the data transmission / reception means 21 when the data transmission device 20 is a relay server device or a data communication device, for example, a request message transmitted from the user terminal 10 to the origin server is transmitted from the user terminal 10 to the origin server. There is a method in which a router or the like installed in the middle of the route to the data transmission device 20 transfers to the data transmission / reception means 21 instead of the origin server based on conditions such as header information of the request message.

  The method for acquiring the data request message is not limited to the above acquisition method. For example, the user terminal 10 explicitly specifies the data transmission device 20 as a proxy and transmits the request message to the data transmission / reception means 21. But you can.

  In addition, for example, when the user terminal 10 attempts to send a request message to the origin server and performs address resolution of the destination with a DNS (Domain Name System) server or the like, the DNS server or the like obtains a data request message. Instead of this, a method of returning the address of the data transmission device 20 may be used. The method for obtaining the data request message is not limited to the above method, and other methods may be used.

  When the congestion control means 22 is notified of the state information of the communication network 30 and the information described in the ACK packet from the data transmission / reception means 21, the congestion control means 22 is based on the parallel simulation parameter N set in the parallel simulation parameter change means 25. It has a function to increase / decrease the congestion window size and transmission rate.

  For example, the congestion control unit 22 increases or decreases the congestion window size or transmission rate based on the parallel simulation parameter N set in the parallel simulation parameter change unit 25 when receiving a notification such as packet loss from the data transmission / reception unit 21. To do.

  As a method for increasing / decreasing the congestion window size and the transmission rate by the congestion control means 22, for example, as in Non-Patent Document 1, there is a method for increasing / decreasing cwnd by Expression (1) and Expression (2). In addition to this method, the method of increasing / decreasing the congestion window size and the transmission rate is, for example, changing the value of N in Equations (1) and (2) to a × N or N + b using constants a and b. A method of increasing / decreasing cwnd by an equation is also possible.

  The communication network state monitoring unit 23 has a function of storing the notified information when the data transmitting / receiving unit 21 is notified of the state information of the communication network 30 or the information described in the ACK packet. Note that the communication network state monitoring unit 23 may store one or more pieces of information notified in the past. Further, the communication network state monitoring unit 23 calculates and stores one or more of the occurrence frequency, the occurrence interval, and the statistical value such as the average or the variance regarding the stored information with respect to the value corresponding to the stored information. It has the function to do.

  The communication network state monitoring unit 23 stores the notified state information when, for example, the state information of the communication network 30 such as RTT or packet loss is notified from the data transmitting / receiving unit 21.

  The value calculated and stored by the communication network state monitoring unit 23 is, for example, a normalized RTT variance value. The value calculated and stored is not limited to the above, and may be, for example, an estimated queue amount obtained by multiplying the difference between the round trip delay and the minimum round trip delay by the throughput in transmission by the data transmitting / receiving unit 21.

  The value calculated and stored by the communication network state monitoring unit 23 may be a packet loss occurrence frequency or a packet loss occurrence interval. As a packet loss detection method, for example, there is a method of determining that a packet loss has occurred when a missing number of packets or bytes greater than or equal to a predetermined value occurs between sequence numbers indicated by SACK.

  Further, the packet loss detection method is not limited to the above method, and for example, a method in which arrival of a NACK packet having a packet number or a byte number greater than or equal to a predetermined value is regarded as occurrence of packet loss may be used. Alternatively, a method may be considered in which the arrival of duplicate ACK packets having a number of packets or bytes greater than or equal to a predetermined value is considered as packet loss.

  The burst loss detection unit 24 has a function of detecting occurrence of a burst loss related to data transmission of the ACK packet from the information of the ACK packet received by the data transmission / reception unit 21.

  The burst loss detecting unit 24 determines whether or not a burst loss has occurred when receiving a packet loss occurrence notification from the data transmitting / receiving unit 21. As a method for determining whether or not a burst loss has occurred, for example, there is a method for determining that a burst loss has occurred when the amount of continuous packet loss exceeds a preset threshold.

  The method for determining whether or not burst loss has occurred is not limited to the above method, and the severity of burst loss is determined according to the magnitude of a value obtained by subtracting a preset threshold value from the continuous packet loss amount. It is also possible to do it. The continuous packet loss amount is, for example, the number of packets or bytes continuously missing between the sequence numbers indicated by SACK.

  Further, the continuous packet loss amount is not limited to the above-described content, and may be the number of continuously missing packets or the number of bytes indicated by the NACK packet. Further, the continuous packet loss amount may be the arrival number of duplicate ACK packets.

  The parallel simulation parameter changing unit 25 has a function of acquiring status information stored from the communication network state monitoring unit 23 or a statistical value of the calculated state information and determining whether to increase the parallel simulation parameter. The parallel simulation parameter changing unit 25 has a function of decreasing the parallel simulation parameter when notified from the burst loss detecting unit 24 that a burst loss has occurred.

  The parallel simulation parameter changing unit 25 acquires the state information or the state information statistical value from the communication network state monitoring unit 23 when the communication network state monitoring unit 23 stores the state information or calculates or stores the state information statistical value. Then, it is determined whether or not to increase the parallel simulation parameter.

  As a method for determining whether or not to increase the parallel simulation parameter, for example, there is a method for determining that the parallel simulation parameter is to be increased when the normalized RTT variance value is smaller than a preset threshold value.

  The method for determining whether or not to increase the parallel simulation parameter is not limited to the above method. For example, when the estimated queue amount is smaller than a preset threshold, the method for determining that the parallel simulation parameter is to be increased is also used. Good.

  The method for determining whether to increase the parallel simulation parameter may be a method for determining that the parallel simulation parameter is to be increased when the frequency of occurrence of packet loss is smaller than a preset threshold. Alternatively, a method may be used in which it is determined that the parallel simulation parameter is increased when the packet loss occurrence interval is larger than a preset threshold.

  The increase amount of the parallel simulation parameter is, for example, 1. Further, the increase amount is not limited to 1, and may be a fixed value other than 1, for example. Further, the increase amount may be a variation value corresponding to the magnitude of the difference between the state information stored by the communication network state monitoring unit 23 or the statistical value of the calculated state information and a preset threshold value.

  The parallel simulation parameter changing unit 25 decreases the parallel simulation parameter when the burst loss detecting unit 24 determines the occurrence of the burst loss. The reduction amount of the parallel simulation parameter is 1, for example. Further, the amount of decrease is not limited to 1, and may be a fixed value other than 1, for example. Further, the decrease amount may be a fluctuation value corresponding to the seriousness of the burst loss determined by the burst loss detecting means 24.

  In the present embodiment, the congestion control unit 22, the communication network state monitoring unit 23, the burst loss detection unit 24, and the parallel simulation parameter changing unit 25 are realized by, for example, a CPU (Central Processing Unit) that operates according to a program.

  The data transmission / reception means 21 is realized by, for example, a CPU that operates according to a program and a communication control device such as a communication network card.

  Hereinafter, the operation when the data transmitting apparatus 20 in the present embodiment increases the parallel simulation parameter will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart showing the operation of the parallel simulation parameter increasing process of the data transmission device 20 according to the first embodiment.

  When the data transmission / reception means 21 obtains a data request message from the user terminal 10, the data transmission / reception means 21 transmits the requested data to the user terminal 10 by TCP based on the congestion window size and the transmission rate set in the congestion control means 22. (Step S11).

  When the data transmission / reception means 21 receives the ACK packet for the transmission packet from the user terminal 10, the data transmission / reception means 21 obtains the state information of the communication network 30 and the information described in the received ACK packet from the congestion control means 22 and the communication network state monitoring means 23. To the burst loss detecting means 24 (step S12).

  The communication network state monitoring unit 23 stores the notified information when the data transmitting / receiving unit 21 is notified of the state information of the communication network 30 or the information described in the ACK packet. The communication network state monitoring unit 23 may include the notified information in a list of past information stored. The communication network state monitoring unit 23 calculates and stores statistical values such as frequency, occurrence interval, average, and variance for the stored information values (step S13).

  The parallel simulation parameter changing unit 25 acquires the stored state information or the calculated statistical value of the state information when the communication network state monitoring unit 23 stores the state information or calculates or stores the statistical value of the state information. It is then determined whether to increase the parallel simulation parameter (step S14).

  If it is determined that the parallel simulation parameter is to be increased (Yes in step S14), the parallel simulation parameter changing unit 25 increases the parallel simulation parameter N set therein (step S15). If it is determined that the parallel simulation parameter is not increased (No in step S14), the data transmission device 20 advances the process to step S16.

  The congestion control unit 22 receives the parallel information set in the parallel simulation parameter changing unit 25 when notified from the data transmitting / receiving unit 21 of the state information of the communication network 30 and the information described in the ACK packet received by the data transmitting / receiving unit 21. Based on the simulation parameters, the congestion window size and transmission rate are increased or decreased (step S16). After the congestion control unit 22 changes the transmission rate or the like, the data transmission device 20 ends the parallel simulation parameter increase process.

  Note that the burst loss detection means 24 also determines whether or not a burst loss has occurred based on the information notified from the data transmission / reception means 21. Here, the burst loss detecting means 24 determines that no burst loss has occurred. The parallel simulation parameter changing unit 25 receives the determination result from the burst loss detecting unit 24 and does not change the parallel simulation parameter.

  Next, the operation when the data transmitting apparatus 20 in the present embodiment reduces the parallel simulation parameter will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart illustrating the operation of the parallel simulation parameter reduction process of the first embodiment of the data transmission device 20.

  When the data transmission / reception means 21 obtains a data request message from the user terminal 10, the data transmission / reception means 21 transmits the requested data to the user terminal 10 by TCP based on the congestion window size and the transmission rate set in the congestion control means 22. (Step S21).

  When the data transmission / reception means 21 receives the ACK packet for the transmission packet from the user terminal 10, the data transmission / reception means 21 sends the state information of the communication network 30 and the information described in the received ACK packet to the congestion control means 22 and the burst loss detection means 24. The communication network state monitoring means 23 is notified (step S22).

  When the burst loss detecting means 24 is notified of the occurrence of a packet loss from the data transmitting / receiving means 21, it determines whether or not a burst loss has occurred in the generated packet loss (step S23).

  When the burst loss detecting unit 24 determines that a burst loss has occurred (Yes in step S23), the parallel simulation parameter changing unit 25 decreases the parallel simulation parameter (step S24). If the burst loss detection unit 24 determines that no burst loss has occurred (No in step S23), the data transmission device 20 advances the process to step S25.

  The congestion control unit 22 receives the parallel information set in the parallel simulation parameter changing unit 25 when notified from the data transmitting / receiving unit 21 of the state information of the communication network 30 and the information described in the ACK packet received by the data transmitting / receiving unit 21. Based on the simulation parameters, the congestion window size and transmission rate are increased or decreased (step S25). After the congestion control unit 22 changes the transmission rate or the like, the data transmission device 20 ends the parallel simulation parameter reduction process.

  Note that the communication network state monitoring unit 23 also stores information notified from the data transmitting / receiving unit 21 and stores statistical values calculated from the stored information. Here, the parallel simulation parameter changing unit 25 determines that it is not necessary to increase the parallel simulation parameter from the information stored in the communication network state monitoring unit 23 or the statistical value of the calculated information, and changes the parallel simulation parameter. do not do.

  When the transmission rate control system of this embodiment is used, it is possible to appropriately control the parameter N simulating the number of parallel TCP connections and effectively improve throughput even when the state of the communication network changes. it can.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. Note that the configuration example of the transmission rate control system 100 in the second embodiment of the present invention is the same as the description in the first embodiment, and thus the description thereof is omitted.

  FIG. 5 is a block diagram illustrating a configuration example of the second embodiment of the user terminal 10. The user terminal 10 shown in FIG. 5 includes burst loss observation / notification means 11.

  The burst loss observing / notifying means 11 detects the occurrence of a burst loss related to data transmission from the arrival status of the data packet received from the data transmitting / receiving means 21 and notifies the data transmitting / receiving means 21 of the detected occurrence status of the burst loss. Have The burst loss observation / notification means 11 is realized by a CPU that operates according to a program, for example.

  When receiving a data packet from the data transmitting / receiving unit 21, the burst loss observing / notifying unit 11 determines whether or not a burst loss related to data transmission has occurred based on the arrival status of the received data packet.

  As a method for determining whether or not a burst loss has occurred, for example, there is a method for determining that a burst loss has occurred when the amount of continuous packet loss exceeds a preset threshold.

  The method for determining whether or not burst loss has occurred is not limited to the above method, and the severity of burst loss is determined according to the magnitude of a value obtained by subtracting a preset threshold value from the continuous packet loss amount. It is also possible to do it.

  The continuous packet loss amount is, for example, the number of packets or the number of bytes continuously missing between the sequence numbers of the arrival packets.

  The continuous packet loss amount is not limited to the above contents, and may be the number of continuous arrivals of data packets with an ECN option representing a CE (Congestion Encountered) state.

  The burst loss observation / notification unit 11 notifies the data transmission / reception unit 21 of the occurrence of a burst loss when it is determined that a burst loss has occurred. The burst loss occurrence notification method includes, for example, a method in which a flag or message indicating the occurrence of burst loss in accordance with a predetermined format is added to a header of a normal ACK packet and returned.

  Further, the burst loss occurrence notification method is not limited to the above method. For example, apart from the normal ACK packet, a method of returning a packet representing the occurrence of burst loss in accordance with a predetermined format may be used.

  FIG. 6 is a block diagram illustrating a configuration example of the second embodiment of the data transmission device 20. The data transmission apparatus 20 shown in FIG. 6 includes data transmission / reception means 21, congestion control means 22, communication network state monitoring means 23, and parallel simulation parameter changing means 25. Descriptions of the data transmitting / receiving unit 21, the congestion control unit 22, the communication network state monitoring unit 23, and the parallel simulation parameter changing unit 25 are the same as those described in the first embodiment, and are therefore omitted.

  Hereinafter, the operation when the data transmitting apparatus 20 according to the present embodiment decreases the parallel simulation parameter will be described with reference to the flowchart of FIG. FIG. 7 is a flowchart showing the operation of the parallel simulation parameter reduction process of the second embodiment of the data transmission device 20.

  When the data transmission / reception means 21 obtains a data request message from the user terminal 10, the data transmission / reception means 21 transmits the requested data to the user terminal 10 by TCP based on the congestion window size and the transmission rate set in the congestion control means 22. (Step S31).

  When receiving the data packet from the data transmitting / receiving unit 21, the burst loss observing / notifying unit 11 determines whether or not a burst loss related to data transmission has occurred from the arrival status of the received data packet (step S32). .

  If it is determined that a burst loss has occurred (Yes in step S32), the burst loss observation / notification unit 11 notifies the data transmission / reception unit 21 of the occurrence of a burst loss (step S33). When it is determined that no burst loss has occurred (No in step S32), the burst loss observation / notification unit 11 advances the process to step S34.

  When the data transmission / reception means 21 receives the ACK packet for the transmission packet from the user terminal 10, the data transmission / reception means 21 receives the state information of the communication network 30 and the information described in the received ACK packet from the congestion control means 22, the communication network state monitoring means 23, (Step S34).

  Next, the data transmitting / receiving unit 21 checks whether or not the burst loss occurrence / notification unit 11 has been notified of the occurrence of the burst loss (step S35). When the occurrence of the burst loss is notified (Yes in step S35), the data transmitting / receiving unit 21 notifies the occurrence of the burst loss to the parallel simulation parameter changing unit 25 (step S36). When the occurrence of the burst loss is not notified (No in step S35), the data transmitting device 20 advances the process to step S38.

  The parallel simulation parameter changing unit 25 decreases the parallel simulation parameter when notified of the occurrence of the burst loss from the data transmitting / receiving unit 21 (step S37).

  The congestion control means 22 is based on the parallel simulation parameters set in the parallel simulation parameter change means 25 when notified from the data transmission / reception means 21 of the state information of the communication network 30 and the information described in the received ACK packet. Next, the congestion window size and the transmission rate are increased or decreased (step S38). After the congestion control unit 22 changes the transmission rate or the like, the data transmission device 20 ends the parallel simulation parameter reduction process.

  Note that the communication network state monitoring unit 23 also stores information input from the data transmission / reception unit 21 and stores statistical values calculated from the stored information. Here, the parallel simulation parameter changing unit 25 determines that it is not necessary to increase the parallel simulation parameter from the information stored in the communication network state monitoring unit 23 or the statistical value of the calculated information, and changes the parallel simulation parameter. do not do.

  When the transmission rate control system of this embodiment is used, the burst loss observation / notification means directly observes and notifies the burst loss, and in the first embodiment, estimation is performed by a function using a SACK option or a NACK packet. The burst loss that has been made can be detected more accurately. Therefore, it is possible to appropriately control the parallel simulation parameters with higher accuracy and effectively improve the throughput.

  Next, the outline of the present invention will be described. FIG. 8 is a block diagram showing an outline of a transmission rate control apparatus according to the present invention. A transmission rate control device 1 according to the present invention is a transmission rate control device that controls a transmission rate when data is transmitted using a plurality of parallel connections simulated in a connection, and is used for communication in a communication network. The communication network state monitoring unit 3 (for example, the communication network state monitoring unit 23 and the burst loss detecting unit 24) that monitors the state, and a parallel simulation parameter that can specify the number of a plurality of parallel connections, communication indicating the communication state Parallel simulation parameter changing means 4 (for example, parallel simulation parameter changing means 25) for increasing / decreasing based on the state information, and congestion control means 2 for determining the transmission rate based on the parallel simulation parameters by the parallel simulation parameter changing means 4 (for example, Congestion control means 22).

  With such a configuration, the transmission rate control apparatus can appropriately control the parallel simulation parameters and effectively improve the throughput.

  The communication network state monitoring means 3 calculates and stores one or more of a value indicating past communication state information, an occurrence frequency of the stored communication state information, an occurrence interval, and a statistical value of the communication state, The parallel simulation parameter changing unit 4 may determine whether or not to increase the parallel simulation parameter based on the value stored in the communication network state monitoring unit 3.

  With such a configuration, the transmission rate control apparatus can control the parallel simulation parameter using the past communication state information and the calculated value.

  The communication network state monitoring means 3 calculates and stores the normalized variance value of the round-trip delay, the estimated queue amount obtained by multiplying the difference between the round-trip delay and the minimum value by the throughput, and the parallel simulation parameter changing means 4 The communication status information or the calculated value may be compared with a preset threshold value to determine whether to increase the parallel simulation parameter.

  With such a configuration, the transmission rate control apparatus can control the parallel simulation parameter using the normalized variance value of the round-trip delay and the estimated queue amount.

  The communication network state monitoring means 3 detects the occurrence of burst loss in data transmission based on the information in the received ACK packet, and the parallel simulation parameter changing means 4 determines the parallel simulation parameter based on the occurrence of burst loss. It may be decreased.

  With such a configuration, this transmission rate control device can detect the occurrence of burst loss in data transmission and can control the parallel simulation parameters based on the detection of the occurrence of burst loss.

  The communication network state monitoring means 3 measures the continuous packet loss amount based on the missing number of packets or bytes indicated by SACK or NACK, or the number of packets or bytes of duplicate ACKs that arrive continuously. When the packet loss amount exceeds a preset threshold, it may be determined that a burst loss has occurred.

  With such a configuration, the transmission rate control apparatus can detect occurrence of a burst loss using SACK, NACK, or duplicate ACK.

  Further, the communication network state monitoring means 3 receives from the terminal information on occurrence of burst loss in the data transmission detected based on the arrival status of the data packet received by the terminal that is the data transmission destination, and the parallel simulation parameter changing means 4 may reduce the parallel simulation parameter based on the occurrence of burst loss.

  With such a configuration, the transmission rate control apparatus can appropriately control the parallel simulation parameters with higher accuracy and effectively improve the throughput.

  Further, the communication network state monitoring means 3 is the data with ECN option indicating the number of packets or bytes continuously missing between the sequence numbers of the arrival packets by the terminal that is the data transmission destination, or the CE state. The amount of continuous packet loss may be measured based on the number of consecutive packet arrivals, and information that determines that a burst loss has occurred may be received from the terminal when the amount of continuous packet loss exceeds a preset threshold.

  With such a configuration, the transmission rate control device can detect the occurrence of a burst loss from the amount of continuous packet loss of arrival packets.

  The present invention is suitable not only for parameter control in congestion control in data communication simulating parallel TCP connections, but also for control processing for the number of connections used when establishing and communicating with parallel TCP connections. Applied. The present invention is also applied in combination with a known method of controlling a transmission rate at an ACK packet return timing in a receiving terminal that downloads content using parallel connections.

DESCRIPTION OF SYMBOLS 1 Transmission rate control apparatus 10 User terminal 11 Burst loss observation / notification means 20 Data transmission apparatus 21 Data transmission / reception means 2, 22 Congestion control means 3, 23 Communication network state monitoring means 24 Burst loss detection means 4, 25 Parallel simulation parameter change means 30 Communication Network 100 Transmission Rate Control System

Claims (9)

A transmission rate control device for controlling a transmission rate when transmitting data using a plurality of parallel connections simulated in a connection,
A communication network state monitoring means for monitoring a communication state of the communication network;
Parallel simulation parameter changing means for increasing / decreasing a parallel simulation parameter capable of specifying the number of the plurality of parallel connections based on communication state information indicating the communication state;
A transmission rate control device comprising: a congestion control unit that determines the transmission rate based on the parallel simulation parameter by the parallel simulation parameter changing unit. The communication network state monitoring means calculates and stores one or more of a value indicating past communication state information, an occurrence frequency of the stored communication state information, an occurrence interval, and a statistical value of the communication state,
The transmission rate control apparatus according to claim 1, wherein the parallel simulation parameter changing unit determines whether or not to increase the parallel simulation parameter based on a value stored in the communication network state monitoring unit. The communication network state monitoring means calculates and stores an estimated queue amount obtained by multiplying the normalized round-trip delay variance, round-trip delay and its minimum value by the throughput,
The transmission rate control apparatus according to claim 2, wherein the parallel simulation parameter changing means compares the communication state information or the calculated value with a preset threshold value to determine whether or not to increase the parallel simulation parameter. The communication network state monitoring means detects occurrence of burst loss in data transmission based on information in the received ACK packet,
The transmission rate control apparatus according to any one of claims 1 to 3, wherein the parallel simulation parameter changing unit decreases the parallel simulation parameter based on the occurrence of the burst loss. The communication network state monitoring means determines whether the number of packets or the number of bytes indicated by SACK (Selective ACKnowledgement) or NACK (Negative ACKnowledgement), or the number of consecutive ACK packets that have arrived continuously. The transmission rate control apparatus according to claim 4, wherein a burst loss is determined when the continuous packet loss amount exceeds a preset threshold value. The communication network state monitoring means receives from the terminal information on occurrence of burst loss in data transmission detected based on the arrival status of the data packet received by the terminal that is the data transmission destination,
The transmission rate control apparatus according to any one of claims 1 to 3, wherein the parallel simulation parameter changing unit decreases the parallel simulation parameter based on the occurrence of the burst loss. The communication network state monitoring means is the ECN (Explicit) indicating the number of packets or bytes continuously lost between the sequence numbers of the arrival packets, or the CE (Congestion Encountered) state. (Congestion Notification) The continuous packet loss amount is measured by the number of continuous arrivals of data packets with an option, and when the continuous packet loss amount exceeds a preset threshold, information that determines that a burst loss has occurred is received from the terminal. The transmission rate control device according to claim 6 for receiving. A transmission rate control method executed in a transmission rate control device that controls a transmission rate when transmitting data using a plurality of parallel connections simulated in a connection,
Monitor the communication status of the communication network,
A parallel simulation parameter capable of specifying the number of the plurality of parallel connections is increased or decreased based on communication state information indicating the communication state,
The transmission rate control method, wherein the transmission rate is determined based on the parallel simulation parameter increased or decreased. A transmission rate control program executed in a transmission rate control device for controlling a transmission rate when transmitting data using a plurality of parallel connections simulated in a connection,
In the transmission rate control device,
Monitoring process to monitor the communication status of the communication network,
The parallel simulation parameter that can specify the number of the plurality of parallel connections is increased / decreased based on communication state information indicating the communication state, and the transmission rate is determined based on the increased / decreased parallel simulation parameter. A transmission rate control program for executing a decision process to decide.

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