JP4042696B2 - Communication system, communication terminal, and communication program - Google Patents

Description

  The present invention relates to a communication system, a communication terminal, and a communication program, and more particularly, to a communication system, a communication terminal, and a communication program that enable control of a transmission rate according to a path between communication terminals and a communication situation.

  A typical transport layer protocol is TCP (Transmission Control Protocol). In TCP, the transmission rate is controlled by adjusting a parameter called window size. The window size represents the amount of packets transmitted during 1 RTT (Round Trip Time). Further, RTT (Round Trip Time) is a time from when a packet is transmitted until an ACK packet returned from the receiving side as a confirmation response to the packet is received.

  The window size is adjusted using the reception status of the ACK packet. A number is assigned to the ACK packet to identify which transmission packet corresponds to the ACK packet. When the number assigned to the ACK packet is not duplicated and the packet is transmitted from the transmission side and the ACK packet for the packet is received in the number order within the predetermined time, the window size is increased. On the other hand, if the transmitting side receives an ACK packet of the same number or does not receive an ACK packet for the packet within a certain time after transmitting the packet, the transmitting side determines that the packet is discarded, that is, The window size is reduced by determining that congestion has occurred in the network.

  In TCP, in the transmission rate control as described above, it is reported that a plurality of TCP connections that pass through the same bottleneck link in the same network environment acquire a bandwidth that is evenly distributed with the bottleneck link bandwidth. (D.Chiu, R.Jain, “Analysis of the Increase Ad Decrease Algorithms for Congestion Avoidance in Computer Networks,” Journal of Networks Ad ISDN, Vol17, No.1, June 1989, pp.1-14: (non-patent Reference 1)). In addition, the Reno version (W. Stevens, “TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms,” RFC 2001, Jan 1997: (Non-Patent Document 2)) can be cited as a widely used TCP. . Depending on the application using TCP, there are those that require high bandwidth and those that do not, so it is possible to improve the link utilization rate by controlling the priority of throughput according to the TCP connection, Control for giving priority of throughput to the Reno version TCP connection is not realized. The following prior art exists as a solution to such a problem.

  TCP-Nice (A. Venkataram Ai et al. “TCP Nice: A MechAism for Background Transfers,” http://www.cs.utexas.edu/users/ arun / pubs / nice.pdf: (Non-Patent Document 3)) and TCP-LP (D.Niclescu, BR Badrinath, “TCP-LP: A Distributed Algorithm for Low Priority Data Transfer,” Proceeding of IEEE INFOCOM2003, April: ( Non-patent document 4)) and the like have been proposed.

  The transmission rate is controlled under the condition that the degree of congestion is lighter than that of a normal TCP connection. Specifically, instead of packet loss, the window size is increased until the observed RTT exceeds a certain value (threshold value), and when the observed RTT exceeds a certain value, the window size is decreased by half. .

D. Chiu, R. Jain, “Analysis of the Increase Ad Decrease Algorithms for Congestion Avoidance in Computer Networks,” Journal of Networks Ad ISDN, Vol17, No.1, June 1989, pp.1-14 W. Stevens, “TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms,” RFC2001, Jan 1997 A.VenkataramAi et al. “TCP Nice: A MechAism for Background Transfers,” http://www.cs.utexas.edu/users/arun/pubs/nice.pdf D.Niclescu, B.R.Badrinath, “TCP-LP: A Distributed Algorithm for Low Priority Data Transfer,” Proceeding of IEEE INFOCOM2003, April S. keshav, B. Landfeldt, A. Seneviratne, B. Melander, P. Gunningberg, “Packet-Pair Flow Control,” IEEE / ACM Transactions on Networking, Feb 1995

  The first problem of the conventional method is that it is desirable to maintain the transmission rate in the physical band of the bottleneck link if there is no traffic other than the own between the transmitting and receiving terminals. TCP-Nice is a control that increases the window size monotonically (linearly) until the observed RTT exceeds a certain value, so that the link cannot be used effectively.

  The second problem of the conventional method is that, as described above, it is desirable to maintain the transmission rate in the physical band of the bottleneck link if there is no traffic between the transmitting and receiving terminals. In a certain TCP-LP, the observed RTT is monotonously increased until a certain value is exceeded, and if it exceeds a certain value, the window size is decreased, so even when there is no other traffic between the transmitting and receiving terminals, The RTT observed due to the influence of own traffic exceeds a certain value, the window size is reduced by half, and the link utilization rate decreases.

  The third problem of the conventional method is that when the bottleneck link is shared with other traffic, you want to specify the allocated bandwidth according to the data characteristics that you want to send, but the conventional techniques TCP-LP and TCP-Nice Then, if the state where the observed RTT exceeds the threshold and shares the bottleneck link with other traffic, the window size is maintained at one packet, so that the traffic for one's traffic depends on the data characteristics This means that bandwidth cannot be allocated.

  A first object of the present invention is a communication system and communication capable of controlling a packet to be transmitted with the physical band upper limit value of the bottleneck link when there is no other traffic on the bottleneck link between the transmitting and receiving terminals. It is to provide a terminal and a communication program.

  A second object of the present invention is to provide a communication system, a communication terminal, and a communication program capable of determining a transmission rate when other traffic exists on a bottleneck link between transmitting and receiving terminals according to data characteristics. .

  A third object of the present invention is to provide a communication system, a communication terminal, and a communication program, which enable priority control of throughput from the start of packet transmission and minimize the influence on other traffic.

  A fourth object of the present invention is to perform estimation of the physical band upper limit value and the minimum RTT of the bottleneck link, thereby improving the accuracy of estimation, and improving the accuracy of throughput priority control, It is to provide a communication terminal and a communication program.

  A fifth object of the present invention is to provide a communication system, a communication terminal, and a communication program that can perform data communication by performing transmission rate allocation control so as not to affect other traffic.

  A sixth object of the present invention is to provide a communication system, a communication terminal, and a communication program in which each terminal can select a route and a relay destination according to data characteristics.

The present invention that achieves the above object is a communication system that transmits and receives data between a plurality of terminals via a network, in which a transmitting terminal determines whether or not there is other traffic on a link with a receiving terminal. The data transmission rate is set to two types of target transmission rates, an upper limit and a lower limit , depending on whether the other traffic is present or not.

The communication system of the present invention according to claim 2 is characterized in that the upper limit of the target transmission rate is a physical band upper limit value of a bottleneck link between the transmitting and receiving terminals .

In the communication system of the present invention according to claim 3 , the minimum RTT is increased from a state in which the minimum RTT is kept constant from a plurality of pieces of information including a window size in data communication and an RTT obtained for the window size. The transmission rate obtained by dividing the window size at the transition boundary by the minimum RTT is set as the upper limit of the target transmission rate .

The communication system according to a fourth aspect of the present invention is characterized in that the lower limit of the target transmission rate is determined based on characteristics of a link and data with a terminal on the receiving side.

The communication system of the present invention according to claim 5 is characterized in that the presence / absence of other traffic in the link with the terminal on the receiving side is determined from the magnitude relationship between the observed RTT and the minimum RTT .

The communication system of the present invention according to claim 6 controls the transmission rate to be the upper limit target transmission rate when observing an RTT lower than the minimum RTT, and observes an RTT higher than the minimum RTT. In this case, the transmission rate is controlled to be the lower limit target transmission rate .

The communication system of the present invention according to claim 7 is characterized in that the upper limit target transmission rate and the minimum RTT are determined based on a transmission rate and an RTT observed for the transmission rate during data transmission. .

The communication system of the present invention according to claim 8 is characterized in that the upper limit target transmission rate and the minimum RTT are obtained by transmitting a test packet to the receiving terminal .

The communication system of the present invention according to claim 9 is characterized in that the upper limit target transmission is based on measurement by transmission of a test packet to the receiving terminal and transmission rate and RTT observed for the transmission rate during data transmission. Determining a rate and said minimum RTT .

In a communication system according to a tenth aspect of the present invention, the transmitting terminal notifies the receiving terminal of the previous period of the upper limit target transmission rate, the minimum RTT, and a reception buffer size .

The communication system of the present invention of claim 11 is provided with a management terminal for managing a path state between the transmission / reception terminal and the transmission / reception terminal. The terminal is requested to acquire the route state information, and the transmission side terminal controls the transmission rate to the upper limit target transmission rate or the lower limit target transmission rate based on the route state information from the management terminal. And performing data communication .

In the communication system according to the twelfth aspect of the present invention, the transmission-side terminal requests the route state information from the management terminal after establishing a connection, and the target terminal is based on the route state information obtained from the management terminal. The transmission rate and the minimum RTT are determined, and the transmission rate is controlled .

In the communication system according to the thirteenth aspect of the present invention, the management terminal periodically updates route state information between the specific terminals, notifies the specific terminals, and the specific terminal on the transmission side The target transmission rate and the minimum RTT are determined based on the path state information, and the transmission rate is controlled .

In the communication system according to the fourteenth aspect of the present invention, the upper limit target transmission rate determined based on the path state information from the management terminal is such that no other traffic exists in the communication path to the terminal on the receiving side. It is characterized by the maximum transmission rate .

The present invention of claim 15 is a transmission rate setting method for a communication system for transmitting and receiving data between a plurality of terminals via a network, wherein the transmitting terminal is connected to another terminal in the link with the receiving terminal. Determining the presence or absence of traffic;
And a step of setting the data transmission rate to two types of target transmission rates, an upper limit and a lower limit , depending on whether the other traffic is present or not.

The transmission rate setting method of the present invention according to claim 16 is characterized in that an upper limit of the target transmission rate is set as a physical band upper limit value of a bottleneck link between the transmitting and receiving terminals .

  According to the communication system, communication terminal, and communication program of the present invention, the following effects are achieved.

  First, when there is no other traffic on the bottleneck link between the transmitting and receiving terminals, control is performed so that packets are transmitted at the physical band upper limit value of the bottleneck link, so the link utilization rate is improved.

  Secondly, even when the bottleneck link is shared with other traffic, the transmission rate when other traffic exists on the bottleneck link between the transmitting and receiving terminals can be determined according to the data characteristics. For this reason, for example, it is possible to specify a minimum required bandwidth.

  Thirdly, by providing a means for estimating the physical band upper limit value and the minimum RTT of the bottleneck link between the transmitting and receiving terminals separately from the data transmission / reception control unit, it becomes possible to perform priority control of throughput from the start of packet transmission. It is possible to minimize the influence on other traffic.

  Fourth, it is possible to improve the accuracy of estimation by estimating the physical band upper limit value and the minimum RTT of the bottleneck link between the transmitting and receiving terminals even at the start of packet transmission and during packet transmission. The accuracy of priority control is also improved.

  Fifth, by arranging a management terminal that manages the path state between terminals that perform data communication, each terminal does not affect other traffic by acquiring path state information obtained from the management terminal. In addition, transmission rate allocation control is performed, and data communication can be performed.

  Sixth, by notifying the physical band upper limit value, the minimum RTT, and the reception buffer size of the bottleneck link obtained by data transfer to the communication partner terminal, each terminal can change the route and relay destination according to the data characteristics. Can be selected.

  A first embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, terminals S1 to Sn are arranged on the network. Further, data communication is performed between the terminals S1 to Sn.

  Since all of the terminals S1 to Sn have the same internal configuration, the terminal S1 will be described below for explanation.

  FIG. 2 is a block diagram showing an internal configuration of the data transmission / reception control unit L100 of the terminal S1. The data transmission / reception control unit L100 includes a target transmission rate estimation unit L101, a target transmission rate determination storage unit L102, an RTT threshold value determination storage unit L103, a target transmission rate selection unit L104, a transmission rate control unit L105, a packet transmission unit L106, and a packet reception unit. L107, the RTT measurement part L108, and the RTT determination part L109 are provided. Each component will be described below.

  The target transmission rate estimation unit L101 estimates the physical bandwidth of the bottleneck link between terminals that transmit and receive data based on the transmission rate value notified from the transmission rate control unit L105 and the RTT notified from the RTT measurement unit L108. I do. The estimation method in this case will be described in detail below with reference to FIG.

(Target transmission rate A estimation method using inline measurement)
A method for determining the transmission rate A will be described. While communication is being performed between the transmitting and receiving terminals, information is obtained by combining RTTs obtained for a certain window size and other window sizes. When a large number of sets are collected and plotted with the horizontal axis as the window size and the vertical axis as the RTT, a plurality of RTTs are obtained for each of a plurality of window sizes having different sizes as shown in FIG.

  If the window size does not exceed a certain value, the amount of traffic flowing in the bottleneck link between the transmitting and receiving terminals becomes the upper limit of the physical bandwidth of the bottleneck link when communication is performed with the window size observing the minimum RTT (RTT_min). Since it has not reached, the minimum RTT (RTT_min) with respect to the window size is almost equal.

  When the window size exceeds a certain value, packets are accumulated in the buffer of the bottleneck link router even if there is no other traffic (cross traffic) in the bottleneck link between the transmitting and receiving terminals, and the minimum RTT (RTT_min) Will increase. Also, the minimum RTT (RTT_min) increases until the buffer of the bottleneck link router is full. Here, for example, as shown in FIG. 20, in the network composed of terminals S1 to S6, the bottleneck link means that when terminal S1 is a transmitting terminal and terminal S4 is a receiving terminal, between terminal S2 and terminal S3. Corresponds to the link.

  The transmission rate in this case is a value obtained by dividing the window size (WA) at the boundary where the minimum RTT (RTT_min) is kept constant in FIG. 19 and transitioning to the increasing trend by the minimum RTT (RTT_min). Thus, this value can be estimated as the upper limit value of the physical bandwidth of the bottleneck link. This value is the target transmission rate A. The target transmission rate estimation unit L101 estimates the target transmission rate A as described above.

  The target transmission rate determination storage unit L102 determines and stores the target transmission rates A and B. The target transmission rate A is a rate value notified from the target transmission rate estimation unit L101 described above, and the target transmission rate B is determined as a value smaller than the target transmission rate A. For example, a value obtained by dividing the packet size by the observed RTT, or a value determined according to data characteristics, which is smaller than the target transmission rate A is used.

  The RTT threshold value determination storage unit L103 acquires the window size and RTT pair information obtained by the above estimation method from the target transmission rate estimation unit L101, and determines and stores the minimum RTT (RTT_min) in FIG. 19 as the RTT threshold value. In the present invention, since the transmission rate is controlled with the window size equal to or smaller than the window size WA in FIG. 19, when the RTT observed on the transmission side exceeds RTT_min, it is determined that other traffic exists.

  The RTT determination unit L109 determines whether there is other traffic between the transmitting and receiving terminals using the RTT obtained from the RTT measurement unit L108 and the RTT threshold obtained from the RTT threshold determination storage unit L103.

  In this embodiment, the transmission rate is controlled with the maximum value of the window size (the amount of packets transmitted during one RTT) as the window size WA of FIG. 19, and this is observed when there is no other traffic between the transmitting and receiving terminals. The RTT is the minimum RTT (RTT_min) in FIG.

  When other traffic flows into the bottleneck link, packets start to be accumulated in the buffer of the bottleneck link router. For example, in the RTT measuring unit L108 of the terminal S1 on the transmission side in FIG. 20, the RTT exceeding the minimum RTT (RTT_min) Observe. Accordingly, when the measured RTT exceeds the RTT threshold, the RTT determination unit L109 determines that other traffic exists between the transmitting and receiving terminals, and sets the value “0”. When the RTT is the RTT threshold, the transmitting and receiving terminals It is determined that no other traffic exists between them, and the value “1” is notified to the target transmission rate selection unit L104.

  When the value “0” is notified as information from the RTT determination unit L109 (other traffic exists on the bottleneck link between the transmission and reception terminals), the target transmission rate selection unit L104 uses the target transmission as the target transmission rate. When the rate B is selected and “1” is notified (no other traffic exists on the bottleneck link between the transmitting and receiving terminals), the target transmission rate A is selected as the target transmission rate. The selected result is notified to the transmission rate control unit L105.

  The transmission rate control unit L105 determines the transmission rate by comparing the current transmission rate with the target rate notified from the target transmission rate selection unit L104, and notifies the packet transmission unit L106 and the target transmission rate estimation unit L101. Here, when the target transmission rate is B, the transmission rate is set to B regardless of the current transmission rate, and when the target transmission rate is A, the transmission rate is set when the current transmission rate is smaller than A. Is increased to the target transmission rate A. When the current transmission rate is equal to or higher than the target transmission rate A, the transmission rate is set to A.

  The packet transmission unit L106 transmits a packet at the transmission rate notified from the transmission rate control unit L105.

  The packet receiving unit L107 receives a packet transmitted from another terminal and an ACK (acknowledgment) packet for the transmitted packet.

  The RTT measuring unit L108 measures RTT (round trip delay time) using the transmission time of the data packet and the reception time of the ACK (acknowledgment) packet. The measured RTT is notified to the RTT determination unit L109 and the RTT threshold value determination storage unit L103.

(Description of operation)
Next, the operation of the first embodiment of the present invention will be described in detail with reference to FIG. 2, FIG. 3, and FIG.

  When S1 to Sn transmit data in FIG. 1, since the terminals S1 to Sn perform the same operation, consider a case where the terminal S1 performs data communication as a transmitting terminal.

  In FIG. 3, when a connection is established (step P1), first, the target transmission rate estimation unit L101 makes an inquiry to the target transmission rate determination storage unit L102 and the RTT threshold value determination storage unit L103, and the history obtained in the past communication It is checked whether information (target transmission rates A and B and the RTT threshold value) is stored (step P2). If the history information is stored, the target transmission rates A and B and the RTT threshold are determined based on the stored values (step P3). If the history information is not stored, group information including a pair of RTTs for a certain window size during packet transmission and other window sizes is acquired, and target transmission rates A, B, and RTT thresholds are estimated (step P4). The target transmission rate A, B, and RTT threshold value estimation processing will be described later.

  In the following description, the history information (target transmission rates A and B and the RTT threshold) is stored separately when the connection is established and when it is not.

  When history information is stored in step P2, at the start of packet transmission, the transmission rate control unit L105 initializes the transmission rate (step P5). In this initialization, for example, a value obtained by dividing the packet size by the RTT threshold value (RTT_min) stored in the RTT threshold value determination storage unit L103 or the target transmission rate B is set as the transmission rate.

  The packet transmission unit L106 transmits a packet at the transmission rate notified from the transmission rate control unit L105 (step P6). When an ACK packet is returned as a confirmation response to the transmission packet from the receiving side, reception is performed by the packet receiving unit L107 (step P7).

  When the ACK packet is received, the RTT measurement unit L108 measures the RTT using the time when the packet is transmitted and the time when the ACK packet for the transmission packet is received (step P8).

  The RTT determination unit L109 compares the RTT notified from the RTT measurement unit L108 with the RTT threshold notified from the RTT threshold value determination storage unit L103, and determines whether there is other traffic on the bottleneck link between the transmitting and receiving terminals. (Step P9).

  In this embodiment, since the window rate (the amount of packets transmitted during one RTT) is controlled within the window size WA or less, the transmission rate is controlled. Therefore, when there is no other traffic on the bottleneck link between the transmitting and receiving terminals, The transmitting terminal observes the RTT of RTT_min in FIG. When other traffic exists on the bottleneck link between the transmitting and receiving terminals, an RTT larger than RTT_min is observed. Therefore, if the RTT is larger than the RTT threshold, it is determined that other traffic is present on the bottleneck link. If the RTT is equal to the RTT threshold, it is determined that there is other traffic on the bottleneck link. It decides not to do so, and notifies the target transmission rate selection unit L104 of the value “1”. The target transmission rate selection unit L104 selects the target transmission rate B when receiving the notification of the value “0” from the RTT determination unit L109, and selects the target transmission rate A when receiving the notification of the value “1”. The result is notified to the transmission rate control unit L105 (steps P10 and P11).

  When receiving the notification of the target transmission rate B, the transmission rate control unit L105 sets the transmission rate to B. When the notification of the target transmission rate A is received, the current transmission rate is compared with A, and if the current transmission rate is smaller than the target transmission rate A, the transmission rate is increased to the target transmission rate A. If the current transmission rate is equal to or higher than the target transmission rate A, the transmission rate is maintained or set to the target transmission rate A (step P12).

  The transmission rate control unit L105 notifies the determined transmission rate to the packet transmission unit L106 (step P13). If packet transmission has not ended (step P14), packet transmission is performed at the determined transmission rate (step P6). If packet transmission has ended, the connection is ended (step P15).

  The flow of the target transmission rate A, B, RTT threshold value estimation process when no history information is stored in step P2 will be described below.

  The transmission rate controller L105 initializes the transmission rate. In the initialization in this case, since the RTT is not the stored known value, the window size is set to 1 packet as the transmission rate. In addition, the transmission rate is notified to the target transmission rate estimation unit L101, and the packet transmission unit L106 is notified to transmit a packet at the transmission rate.

  When an ACK packet is returned from the receiving side as a confirmation response to the transmission packet, the packet receiving unit L107 receives the ACK packet. When reception is performed, the RTT is measured using the time when the packet is transmitted by the RTT measurement unit L108 and the time when the ACK packet for the transmission packet is received, and the target transmission rate estimation unit L101 is notified.

  The target transmission rate estimator L101 stores group information including a set of RTTs for a window size (amount of packets transmitted during one RTT) and a window size (amount of packets transmitted during one RTT). The transmission rate control unit L105 controls the transmission rate using a conventional TCP transmission rate control method. The target transmission rate estimation unit L101 collects the set information as described above, and estimates the target transmission rates A and B and the RTT threshold by the estimation method described above (step P4).

  When the target transmission rates A and B and the RTT threshold are determined, the subsequent operation (operation after step P5) is the same as when history information is stored at the time of connection establishment.

  By controlling the transmission rate as described above, as shown in FIG. 21, when other traffic exists, the target transmission rate B is set, and when no other traffic exists, target transmission is performed. Rate A (the upper limit value of the physical bandwidth) is set.

(Effect of Example 1)
The effects of the first embodiment will be described. If there is no other traffic on the bottleneck link between the transmitting and receiving terminals, the conventional method increases the transmission rate until the observed RTT exceeds a certain value, and if the observed RTT exceeds a certain value, Since the transmission rate is reduced, the link utilization rate is reduced. However, in this embodiment, the transmission rate is controlled by determining whether there is other traffic on the bottleneck link from the magnitude relationship between the observed RTT and the RTT threshold, and therefore, between the transmitting and receiving terminals. When there is no other traffic on the bottleneck link, packets are transmitted at the target transmission rate A (the upper limit value of the physical bandwidth of the bottleneck link), thereby improving the link utilization rate. The problem is solved.

  Also, in the conventional method, when the observed RTT exceeds a certain value, it is estimated that other traffic exists and the window size is reduced to half or one packet. However, in this embodiment, there is other traffic. If so, the transmission rate is decreased to the target transmission rate B. Since the target transmission rate B can be determined according to the data characteristics, for example, it is possible to specify the minimum required bandwidth, and the third problem of the conventional method can be solved.

  A second embodiment of the present invention will be described in detail with reference to the drawings. The network configuration is the same as that in FIG. 1, terminals S1 to Sn are arranged on the network, and data communication is performed between the terminals S1 to Sn.

  Again, since the terminals S1 to Sn have the same internal configuration, the terminal S1 will be described. Referring to FIG. 4, the terminal S1 according to the second embodiment includes a route state estimation unit M10 and a data transmission / reception control unit M100.

  The path state estimation unit M10 measures the bandwidth between the transmission and reception terminals and the RTT, and estimates the physical band upper limit value and the minimum RTT of the bottleneck link between the transmission and reception terminals from the measurement result. M11, the path | route state measurement part M12, and the path | route state information storage part M13 are provided.

  The data transmission / reception control unit M100 performs transmission rate control based on the physical band upper limit value and the minimum RTT of the bottleneck link estimated by the path state estimation unit M10. The data transmission / reception control unit M100 includes a target transmission rate determination storage unit M101, a target transmission rate selection unit M102, a transmission rate control unit M104, a packet transmission unit M105, a packet reception unit M106, an RTT measurement unit M107, an RTT determination unit M108, an RTT. A threshold determination storage unit M103 is provided. Each component will be described below.

  The route state estimation unit M10 has a function of estimating a route state between transmitting and receiving terminals and a function of storing route state information.

  Here, the path state information is information including the physical band upper limit value and the minimum RTT of the bottleneck link.

  The estimation of the physical band upper limit value of the bottleneck link is performed by, for example, the estimation method described in the first embodiment of the present invention or the Packet-Pair method (S. keshav, B. Landfeldt, A. Seneviratne, B. Melander, P. Gunningberg, “Packet-Pair Flow Control,” IEEE / ACM Transactions on Networking, Feb 1995: (Non-Patent Document 5)).

  In this Packet-Pair method, measurement packets having the same packet size are transmitted continuously (without a time interval) to the receiving side. When the measurement packet passes through the bottleneck link, the reception side observes the arrival time interval of the measurement packet. (When the receiving side receives the measurement packet, the receiving side may return a response packet having a size smaller than the measuring packet to the transmitting side, and the transmitting side may measure the arrival time interval of the measuring packet). The physical band upper limit value of the bottleneck link is equal to the value obtained by dividing the measurement packet size by the arrival time interval.

  The minimum RTT is calculated using the estimation method described in the first embodiment and the packet-pair method by using the time when the measurement packet is transmitted and the arrival time of the packet returned as a response on the receiving side. The result is calculated and then estimated. The estimated result is stored in the route state information storage unit M13. In addition, the stored result is notified to the data transmission / reception control unit M100 and used to determine the transmission rate.

  The data transmission / reception control unit M100 has a function equivalent to TCP (Transmission Control Protocol) which is one of the transport layer protocols of the OSI reference model. Connection establishment, suspension, termination, confirmation response function, and retransmission control function.

  The target transmission rate determination storage unit M101 determines and stores two target transmission rates A and B. The target transmission rate A is the physical band upper limit value of the bottleneck link notified from the path state information storage unit M13. The target transmission rate B is determined by a value smaller than the target transmission rate A. As the target transmission rate B, for example, a value that is determined by a value obtained by dividing the packet size by the RTT or a value according to the data characteristics and smaller than the target transmission rate A is used.

  The RTT threshold value determination storage unit M103 stores the value notified from the route state information storage unit M13 as the RTT threshold value. At this time, the value notified from the route state information storage unit M13 is a value equal to the minimum RTT (RTT_min) in FIG.

  The RTT determination unit M108 determines whether there is other traffic between the transmitting and receiving terminals using the RTT obtained from the RTT measurement unit M107 and the RTT threshold obtained from the RTT threshold value determination storage unit M103.

  In this embodiment, the transmission rate is controlled with the maximum value of the transmission rate as the target transmission rate A, and the RTT observed when there is no other traffic between the transmitting and receiving terminals is the minimum RTT (RTT_min in FIG. 19). )

  When other traffic flows into the bottleneck link, packets start to be accumulated in the buffer of the bottleneck link router. For example, in the RTT measuring unit M107 of the terminal S1 on the transmission side in FIG. 20, the RTT value exceeding the minimum RTT (RTT_min) Observe. Therefore, when the RTT exceeds the RTT threshold, it is determined that other traffic exists between the transmitting and receiving terminals, and the value is “0”. When the RTT is the RTT threshold, other traffic exists between the transmitting and receiving terminals. It judges that it is not, and notifies the value “1” to the target transmission rate selection unit M102.

  The target transmission rate selection unit M102 selects one of the two target transmission rates A and B in the target transmission rate determination storage unit M101 based on the information notified from the RTT determination unit M108.

  When RTT is less than or equal to the RTT threshold, it is determined that no other traffic exists on the path between the transmitting and receiving terminals, and the target transmission rate A is selected as the target transmission rate. Conversely, when the RTT is greater than the RTT threshold Determines that there is other traffic between the transmitting and receiving terminals and selects the target transmission rate B as the target transmission rate. The selected result is notified to the transmission rate control unit M104.

  The transmission rate control unit M104 determines the transmission rate by comparing the target transmission rate notified from the target transmission rate selection unit M102 with the current transmission rate. When the target transmission rate is B, the transmission rate is set to B regardless of the current transmission rate. When the target transmission rate is A, when the current transmission rate is smaller than A, the transmission rate is increased to the target transmission rate A. If the current transmission rate is equal to or higher than the target transmission rate A, the transmission rate is set to A.

  The packet transmission unit M105 transmits a packet according to the transmission rate notified from the transmission rate control unit M104.

  The packet receiving unit M106 is a part that receives an ACK packet as a feedback for a packet transmitted from another terminal or a transmitted packet.

  The RTT measurement unit M107 measures the RTT using the transmission time of the transmission packet and the reception time of the ACK packet returned to the transmission packet, and performs the RTT determination unit M108.

(Description of operation)
Next, the operation of the second embodiment of the present invention will be described in detail with reference to FIGS.

  Since the operations when S1 to Sn transmit data in FIG. 1 are the same, the case where the terminal S1 performs data communication as a transmitting terminal is considered here.

  In FIG. 5, the route state estimation unit M10 of the terminal S1 estimates the bottleneck link and the minimum RTT between the transmitting and receiving terminals. In this estimation process, first, a measurement packet is transmitted from the measurement packet transmitting / receiving unit M11 (step Q1). Then, an ACK packet is received as feedback from the receiving terminal (step Q2).

  The path state measurement unit M12 estimates the physical band upper limit value and the minimum RTT of the bottleneck link from the measurement values, and notifies the path state information storage unit M13 (steps Q3 and Q4). The path state information storage unit M13 stores the physical band upper limit value and the minimum RTT notified from the path state measurement unit M12 (step Q5).

  When the connection is established (step Q6), the path state information storage unit M13 notifies the target transmission rate determination storage unit M101 and the RTT threshold determination storage unit M103 of the bottleneck physical bandwidth upper limit value and the minimum RTT, respectively. Is done.

  The RTT threshold value determination storage unit M103 determines and stores the RTT threshold value based on the notified minimum RTT. Further, the target transmission rate determination storage unit M101 sets the notified physical band upper limit value as the target transmission rate value A, and gives the target transmission rate value B as a value smaller than A (step Q7). For example, the target transmission rate value B may be a value obtained by dividing the packet size by the RTT threshold value stored in the RTT threshold value determination storage unit M103, or a transmission rate value depending on the data characteristics.

  When the target transmission rate values A and B and the RTT threshold are determined, the transmission rate control unit M104 initializes the transmission rate (step Q8). In this initialization, for example, a value obtained by dividing the packet size by RTT or the target transmission rate B is set as the transmission rate.

  The transmission rate is notified from the transmission rate control unit M104 to the packet transmission unit M105, and the packet transmission unit M105 transmits the packet at the notified transmission rate (step Q9).

  When an ACK (acknowledgement) packet for the transmission packet is returned from the receiving terminal, the packet receiving unit M106 receives the ACK packet (step Q10).

  Thereafter, the RTT measurement unit M107 calculates the RTT using the transmission time of the transmission packet and the reception time when the ACK packet returned to the transmitted packet is received (step Q11).

  The RTT determination unit M108 compares the RTT notified from the RTT measurement unit M107 with the RTT threshold notified from the RTT threshold value determination storage unit M103, and determines whether there is other traffic on the link between the transmitting and receiving terminals ( Step Q12). When there is no other traffic between the transmitting and receiving terminals, the transmitting terminal S1 observes RTT_min in FIG. When other traffic exists between the transmitting and receiving terminals, packets start to be accumulated in the buffer of the bottleneck link router, and RTT exceeding the RTT threshold is observed. Therefore, when RTT is larger than the RTT threshold, it is determined that other traffic exists on the bottleneck link between the transmitting and receiving terminals, and when the RTT is equal to or less than the RTT threshold, other values are set for the bottleneck link between the transmitting and receiving terminals. And the value “1” is notified to the target transmission rate selection unit M102 (steps Q13 and Q14).

  The target transmission rate selection unit M102 is notified of the target transmission rates A and B from the target transmission rate determination storage unit M101 and is notified of the value “0” from the RTT determination unit M108. When “1” is notified, the target transmission rate A is selected and notified to the transmission rate control unit M104.

  When receiving the notification of the target transmission rate B from the target transmission rate selection unit M102, the transmission rate control unit M104 sets the transmission rate to B. When the notification of the target transmission rate A is received, the notified target transmission rate is compared with the current transmission rate. When the target transmission rate is the target transmission rate A and the current transmission rate is smaller than A, the transmission rate Is increased to the target transmission rate A. If the current transmission rate is equal to or higher than the target transmission rate A, the transmission rate is maintained or set to the target transmission rate A (step Q15).

  Transmission rate control unit M104 notifies packet transmission unit M105 of the determined transmission rate (step Q16). If packet transmission has not ended (step Q17), packet transmission is performed at the determined transmission rate (step Q9). If packet transmission has ended, the connection is ended (step Q18).

(Effect of the second embodiment)
The effect of the second embodiment will be described. If there is no other traffic on the bottleneck link between the transmitting and receiving terminals, the conventional method increases the transmission rate until the observed RTT exceeds a certain value, and if the observed RTT exceeds a certain value, Since the transmission rate is reduced, the link utilization rate is reduced. However, in this embodiment, since the transmission rate control is performed by determining whether there is other traffic on the bottleneck link from the magnitude relationship between the observed RTT and the RTT threshold, the bottle between the transmitting and receiving terminals is controlled. When there is no other traffic on the neck link, packets are transmitted at the target transmission rate A (the upper limit of the physical bandwidth of the bottleneck link), so the link utilization rate is improved, and the first and second problems of the conventional method The point has been eliminated.

  In the conventional method, when the observed RTT exceeds a certain value, it is estimated that other traffic exists, and the window size is reduced to half or one packet. However, in this embodiment, other traffic is reduced. If it is determined that it exists, the transmission rate is decreased to the target transmission rate B. Since the target transmission rate B can be determined according to the data characteristics, for example, it is possible to specify the minimum required bandwidth, and the third problem of the conventional method can be solved.

  In the first embodiment, when no past communication history remains, until the bottleneck link physical band upper limit value and the minimum RTT are estimated, other traffic sharing the bottleneck link between the transmitting and receiving terminals is used. On the other hand, the priority control of the throughput could not be performed, but the physical band upper limit value and the minimum RTT of the bottleneck link are given at the start of packet transmission, so the priority control of the throughput is possible from the start of packet transmission Thus, it is possible to minimize the influence on other traffic.

  A third embodiment of the present invention will be described in detail with reference to the drawings. The network configuration is the same as that in FIG. 1, terminals S1 to Sn are arranged on the network, and data communication is performed between the terminals S1 to Sn.

  Again, since the terminals S1 to Sn have the same internal configuration, the terminal S1 will be described. Referring to FIG. 6, the terminal S1 according to the third embodiment includes a route state estimation unit N10 and a data transmission / reception control unit N100.

  The path state estimation unit N10 measures the bandwidth between the transmission and reception terminals and the RTT, and estimates the physical band upper limit value and the minimum RTT of the bottleneck link between the transmission and reception terminals from the measurement result. N11, a route state measurement unit N12, and a route state information storage unit N13.

  The data transmission / reception control unit N100 performs transmission rate control based on the physical band upper limit value and the minimum RTT of the bottleneck link estimated by the path state estimation unit N10. The data transmission / reception control unit N100 includes a target transmission rate determination storage unit N101, a target transmission rate selection unit N102, a transmission rate control unit N104, a packet transmission unit N105, a packet reception unit N106, an RTT measurement unit N107, an RTT determination unit N108, and an RTT. A threshold determination storage unit N103 is provided. Each component will be described below.

  The route state estimation unit N10 has a function of estimating a route state between transmitting and receiving terminals and a function of storing route state information.

  The path state information is information including the physical band of the bottleneck link and the minimum RTT. As described in the second embodiment, the estimation method of the physical bandwidth of the bottleneck link is the same as the estimation method described in the first embodiment and the Packet-Pair method (described in Non-Patent Document 5). Method) is used. The details are omitted here.

  The minimum RTT is calculated using the estimation method described in the first embodiment and the packet-pair method by using the time when the measurement packet is transmitted and the arrival time of the packet returned as a response on the receiving side. The result is calculated and then estimated. The estimated result is stored in the route state information storage unit N13. The stored result is notified to the data transmission / reception control unit N100 and used for determining the transmission rate.

  The data transmission / reception control unit N100 has a function equivalent to TCP (Transmission Control Protocol) which is one of the transport layer protocols of the OSI reference model. Connection establishment, suspension, termination, confirmation response function, and retransmission control function.

  The target transmission rate determination storage unit N101 determines two target transmission rates A and B for each terminal on the receiving side based on the path state information notified from the path state information estimation unit N10. The target transmission rate A is the maximum transmission rate value that can be output when there is no other traffic on the route to the receiving terminal, and the target transmission rate B is a value smaller than A. As the target transmission rate B, a value obtained by dividing the packet size by the RTT or a transmission rate value instructed by the application in accordance with the data characteristics and smaller than the target transmission rate A is used.

  Further, the target transmission rate determination storage unit N101 also performs estimation of a path state using the transmission rate value notified from the transmission rate control unit N104 and the RTT measured by the RTT measurement unit N107. For estimation during data transmission, the estimation method based on inline measurement already described in the first embodiment is used. The target transmission rate determination storage unit N101 estimates the target transmission rate A by this estimation method.

  The target transmission rate determination storage unit N101 determines and stores two target transmission rates A and B. The target transmission rate A is set as the physical band upper limit value of the bottleneck link notified from the path state information storage unit N13. The target transmission rate B is determined with a value smaller than the target transmission rate A. The target transmission rate B is determined by, for example, a value obtained by dividing the packet size by RTT, or a value according to data characteristics. Even during packet transmission, the transmission rate value is obtained from the transmission rate control unit N104 and the RTT value is obtained from the RTT measurement unit N107, and the physical band upper limit value of the bottleneck link is estimated.

  The RTT threshold value determination storage unit N103 acquires the window size and RTT set information obtained by the above estimation method from the target transmission rate determination storage unit N101, determines the minimum RTT (RTT_min) in FIG. 19 as the RTT threshold value, and stores it. To do. In the present invention, since the transmission rate is controlled with the window size equal to or smaller than the window size WA in FIG. 19, when the RTT observed on the transmission side exceeds RTT_min, it is determined that other traffic exists.

  The RTT determination unit N108 determines whether there is other traffic between the transmitting and receiving terminals using the RTT obtained from the RTT measurement unit N107 and the RTT threshold obtained from the RTT threshold determination storage unit N103.

  In this embodiment, the transmission rate is controlled with the maximum value of the transmission rate as the target transmission rate A, and the RTT observed when there is no other traffic between the transmitting and receiving terminals is the minimum RTT (RTT_min in FIG. 19). )

  When other traffic flows into the bottleneck link, packets start to be accumulated in the buffer of the bottleneck link router. For example, in the RTT measuring unit N107 of the terminal S1 on the transmission side in FIG. 20, the RTT value exceeding the minimum RTT (RTT_min) Observe. Accordingly, when the measured RTT exceeds the RTT threshold, the RTT determination unit N108 determines that other traffic exists between the transmitting and receiving terminals, and sets the value “0”. When the measured RTT is the RTT threshold, the transmitting and receiving terminals It is determined that no other traffic exists between them, and the value “1” is notified to the target transmission rate selection unit N104.

  The target transmission rate selection unit N102 selects one of the two target transmission rates A and B in the target transmission rate determination storage unit N101 based on the information notified from the RTT determination unit N108. When RTT is less than or equal to the RTT threshold, it is determined that no other traffic exists on the path between the transmitting and receiving terminals, and the target transmission rate A is selected as the target transmission rate. Conversely, when the RTT is greater than the RTT threshold Recognizes that there is other traffic between the transmitting and receiving terminals and selects the target transmission rate B as the target transmission rate. The selected result is notified to the transmission rate control unit N104.

  The transmission rate control unit N104 determines the transmission rate by comparing the target transmission rate notified from the target transmission rate selection unit N102 with the current transmission rate. When the target transmission rate is B, the transmission rate is set to B regardless of the current transmission rate. When the target transmission rate is A, when the current transmission rate is smaller than A, the transmission rate is increased to the target transmission rate A. If the current transmission rate is equal to or higher than the target transmission rate A, the transmission rate is set to A.

  The packet transmission unit N105 transmits a packet according to the transmission rate notified from the transmission rate control unit N104.

  The packet receiving unit N106 is a part that receives an ACK packet as a feedback for a packet transmitted from another terminal or a transmitted packet.

  The RTT measurement unit N107 measures the RTT using the transmission time of the transmission packet and the reception time of the ACK packet returned to the transmission packet.

(Description of operation)
Next, the operation of the third embodiment of the present invention will be described in detail with reference to FIG. 1, FIG. 6, and FIG.

    Since the operations when S1 to Sn transmit data in FIG. 1 are the same, the case where the terminal S1 performs data communication as a transmitting terminal is considered here.

  In FIG. 7, the terminal S1 transmits a test packet from the test packet transmitting / receiving unit N11 to the specific terminals S2 to Sn at the path state estimating unit N10 of FIG. (Step R2), and the physical bandwidth upper limit value and the RTT are measured (step R3). The measurement result is transferred to the path state measurement unit N12, and the minimum RTT and the physical bandwidth upper limit value are estimated from the measurement result and notified to the path state information storage unit N13 (step R4). The path state information storage unit N13 stores the notified physical band upper limit value and minimum RTT (step R5).

  When the connection is established (step R6), the path state information storage unit N13 notifies the target transmission rate determination storage unit N101 and the RTT threshold value determination storage unit N103 of the bottleneck physical bandwidth upper limit value and the minimum RTT, respectively. Is done.

  The RTT threshold value determination storage unit N103 determines and stores the RTT threshold value based on the notified minimum RTT. On the other hand, the target transmission rate determination storage unit N101 sets the notified physical band upper limit value as the target transmission rate value A, and gives the target transmission rate value B as a value smaller than A (step R7). For example, as the target transmission rate value B, a value obtained by dividing the packet size by RTT, or a transmission rate value depending on data characteristics can be considered.

  When the target transmission rate values A and B and the RTT threshold value are determined, the transmission rate control unit N104 performs transmission rate processing (step R8). In this initialization, for example, a value obtained by dividing the packet size by the RTT threshold value stored in the RTT threshold value determination storage unit N103 or the target transmission rate B is set as the transmission rate.

  The transmission rate control unit N104 notifies the transmission rate to the packet transmission unit N105, and the packet transmission unit N105 transmits the packet at the notified transmission rate (step R9).

  When an ACK (acknowledgment) packet for the transmission packet is returned from the receiving terminal, the packet receiving unit N106 receives the ACK packet (step R10).

  Thereafter, the RTT measurement unit N107 calculates the RTT using the transmission time of the transmission packet and the reception time when the ACK packet returned to the transmitted packet is received (step R11).

  The calculated RTT is notified to the target transmission rate determination storage unit N101 and the RTT determination unit N108.

  The RTT determination unit N108 compares the RTT notified from the RTT measurement unit N107 with the RTT threshold notified from the RTT threshold determination storage unit N103, and determines whether there is other traffic on the link between the transmitting and receiving terminals ( Step R12). When there is no other traffic between the transmitting and receiving terminals, the transmitting terminal S1 observes the minimum RTT (RTT_min) in FIG. When other traffic exists between the transmitting and receiving terminals, packets start to be accumulated in the buffer of the bottleneck link router, and the RTT exceeding the RTT threshold is observed. Therefore, when RTT is larger than the RTT threshold, it is determined that other traffic exists on the bottleneck link between the transmitting and receiving terminals, and when the RTT is equal to or less than the RTT threshold, other values are set for the bottleneck link between the transmitting and receiving terminals. And the target transmission rate selection unit N102 is notified of the value “1” (steps R13 and R14).

  Further, when the target transmission rate selection unit N102 is notified of the target transmission rates A and B from the target transmission rate determination storage unit N101 and is notified of the value “0” from the RTT determination unit N108, the target transmission rate B is set to the value When “1” is notified, the target transmission rate A is selected and notified to the transmission rate control unit N104.

  The transmission rate control unit N104 compares the target transmission rate notified from the target transmission rate selection unit N102 with the current transmission rate. When the target transmission rate is the target transmission rate A, if the current transmission rate is smaller than the target transmission rate A, the transmission rate is increased to the target transmission rate A, and the current transmission rate is equal to or higher than the target transmission rate A. In this case, the transmission rate is maintained or set to the target transmission rate A. When the target transmission rate is B, the transmission rate is set to B in any case (step R15).

  The determined transmission rate is notified to the target transmission rate determination storage unit N101 and the packet transmission unit N105 (step R16).

  If packet transmission has not ended (step R20), packet transmission is performed at the determined transmission rate (step R9). If packet transmission has ended, the connection is ended (step R21).

  The target transmission rate determination storage unit N101 is notified of the upper limit of the physical bandwidth of the bottleneck link from the path state information storage unit N13 and stores it as the target transmission rate A, but also notifies it from the transmission rate control unit N104. Information about the transmission rate and the RTT notified from the RTT measuring unit N107 are obtained, and the estimation of the bottleneck link physical band upper limit and the minimum RTT is established even after the connection is established by using the estimation method described above. (Step R17). If the estimation result is different from the stored content, the target transmission rate and the RTT threshold are updated (step R7). Otherwise, the estimation result is ignored (step R19).

(Effect of the third embodiment)
The effect of the third embodiment will be described. If there is no other traffic on the bottleneck link between the transmitting and receiving terminals, the conventional method increases the transmission rate until the observed RTT exceeds a certain value, and if the observed RTT exceeds a certain value, Since the transmission rate is reduced, the link utilization rate is reduced. However, in this embodiment, since the transmission rate control is performed by determining whether there is other traffic on the bottleneck link from the magnitude relationship between the observed RTT and the RTT threshold, the bottle between the transmitting and receiving terminals is controlled. When there is no other traffic on the neck link, packets are transmitted at the target transmission rate A (the upper limit of the physical bandwidth of the bottleneck link), so the link utilization rate is improved, and the first and second problems of the conventional method The point has been eliminated.

  In the conventional method, when the observed RTT exceeds a certain value, it is estimated that other traffic exists, and the window size is reduced to half or one packet. However, in this embodiment, other traffic is reduced. If it is determined that it exists, the transmission rate is decreased to the target transmission rate B. Since the target transmission rate B can be determined according to the data characteristics, for example, it is possible to specify the minimum required bandwidth, and the third problem of the conventional method can be solved.

  In the first embodiment, when no past communication history remains, until the bottleneck link physical band upper limit value and the minimum RTT are estimated, other traffic sharing the bottleneck link between the transmitting and receiving terminals is used. On the other hand, the priority control of the throughput could not be performed, but the physical band upper limit value and the minimum RTT of the bottleneck link are given at the start of packet transmission, so the priority control of the throughput is possible from the start of packet transmission Thus, it is possible to minimize the influence on other traffic.

  Further, even during packet transmission, by estimating the upper limit of the physical bandwidth of the bottleneck link and the minimum RTT, it is possible to improve the accuracy of estimation, and the accuracy of priority control of throughput is also improved.

  A fourth embodiment of the present invention will be described in detail with reference to the drawings. In the fourth embodiment, as shown in FIG. 8, a management terminal K10 that manages the path states of the terminals S1 to Sn is arranged in the network composed of the terminals S1 to Sn.

  FIG. 9 shows the internal structure of the terminal according to the fourth embodiment. Again, since the terminals S1 to Sn have the same internal configuration, the terminal S1 will be described.

  The terminal S1 includes a route state information estimation unit W10 and a data transmission / reception control unit W100.

  The route state estimation unit W10 includes a measurement packet transmission / reception unit W11, a route state measurement unit W12, and a route state information acquisition / notification unit W13.

  The data transmission / reception control unit W100 includes a target transmission rate determination storage unit W101, a target transmission rate selection unit W102, an RTT threshold value determination storage unit W103, a transmission rate control unit W104, a packet transmission unit W105, a packet reception unit W106, and an RTT measurement unit. W107 and RTT determination unit W108.

  FIG. 10 is a block diagram showing an internal configuration of the management terminal K10. The management terminal K10 includes a route state estimation request unit K11, a communication state management unit K12, a route state information acquisition / notification unit K13, and a route state information storage unit K14. Is provided. Each component will be described below.

  When the path state estimation unit W10 is requested to estimate the path state between the management terminal K10 and a certain receiving terminal, the measurement packet transmitting / receiving unit W11 transmits a measurement packet to the certain receiving terminal, The state measurement unit W12 estimates the physical band upper limit value and the minimum RTT of the bottleneck link between the transmitting and receiving terminals (path state information: the physical band upper limit value of the bottleneck link, the minimum RTT).

  As described in the second embodiment, the estimation method of the physical bandwidth of the bottleneck link is the same as the estimation method described in the first embodiment and the Packet-Pair method (described in Non-Patent Document 5). Method) is used. The details are omitted here.

  The minimum RTT is calculated by using the estimation method described in the first embodiment and the packet-pair method, using the time when the measurement packet is transmitted and the arrival time of the packet returned as a response on the receiving side. Calculate the minimum value as the estimation result.

  The estimated result is notified to the route state information acquisition / notification unit W13, and the reception buffer size is notified to the management terminal K10 as the route state information and terminal information. The notification of the reception buffer size greatly affects transmission rate control when the terminals S2 to Sn are requested to relay. This is because if the reception buffer is small, the transmission rate is kept low, and if the reception buffer is large, a high transmission rate can be obtained. Further, after the connection is established, the physical band upper limit value and the minimum RTT of the bottleneck link are acquired from the management terminal K10, and notified to the target transmission rate determination storage unit W101 and the RTT threshold determination storage unit W103, respectively.

  The data transmission / reception control unit W100 has a function equivalent to TCP (Transmission Control Protocol) which is one of the transport layer protocols of the OSI reference model. Specifically, connection establishment, suspension, termination, confirmation response function, and retransmission control function.

  The target transmission rate determination storage unit W101 determines and stores two target transmission rates A and B. The target transmission rate A is the upper limit of the physical bandwidth of the bottleneck link that the path state information acquisition / notification unit W13 acquires from the management terminal K10 after the connection is established. The target transmission rate B is determined by a value smaller than the target transmission rate A. As the target transmission rate B, for example, a value obtained by dividing the packet size by the RTT, or a value corresponding to the data characteristics and a value smaller than the target transmission rate A is used.

  The RTT threshold value determination storage unit W103 determines and stores the RTT threshold value depending on the minimum RTT acquired by the route state information acquisition / notification unit W13 from the route state information management terminal K10. At this time, the value notified from the route state information acquisition / notification unit W13 is a value equal to the minimum RTT (RTT_min) in FIG.

  The RTT determination unit W108 determines whether there is other traffic between the transmitting and receiving terminals using the RTT obtained from the RTT measurement unit W107 and the RTT threshold obtained from the RTT threshold value determination storage unit W103.

  In this embodiment, transmission rate control is performed with the maximum value of the transmission rate as the target transmission rate A, and the RTT observed when there is no other traffic between the transmitting and receiving terminals is the minimum RTT (RTT_min) in FIG. It becomes.

  When other traffic flows into the bottleneck link, packets start to be accumulated in the buffer of the bottleneck link router, and the RTT measurement unit W107 of the terminal S1 on the transmission side observes an RTT value exceeding the minimum RTT (RTT_min). Therefore, when the RTT exceeds the RTT threshold, it is determined that other traffic exists between the transmitting and receiving terminals, and the value is “0”. When the RTT is the RTT threshold, other traffic exists between the transmitting and receiving terminals. It judges that it is not, and notifies the value “1” to the target transmission rate selection unit W102.

  The target transmission rate selection unit W102 selects one of the two target transmission rates A and B in the target transmission rate determination storage unit W101 based on the information notified from the RTT determination unit W108.

  If RTT is equal to or less than the RTT threshold, it is determined that no other traffic exists on the path between the transmitting and receiving terminals, and the target transmission rate A is selected as the target transmission rate. Conversely, if RTT is greater than the RTT threshold, Then, it is determined that other traffic exists between the transmitting and receiving terminals, and the target transmission rate B is selected as the target transmission rate. The selected result is notified to the transmission rate control unit W104.

  The transmission rate control unit W104 determines the transmission rate by comparing the target transmission rate notified from the target transmission rate selection unit W102 with the current transmission rate. When the target transmission rate is B, the transmission rate is set to B regardless of the current transmission rate. When the target transmission rate is A, when the current transmission rate is smaller than A, the transmission rate is increased to the target transmission rate A. If the current transmission rate is equal to or greater than A, the transmission rate is set to A.

  The packet transmission unit W105 transmits a packet according to the transmission rate notified from the transmission rate control unit W104.

  The packet receiving unit W106 is a part that receives an ACK packet as a feedback for a packet transmitted from another terminal or a transmitted packet.

  The RTT measurement unit W107 measures the RTT using the transmission time of the transmission packet and the reception time of the ACK packet returned to the transmission packet.

  The route state information management terminal K10 includes a route state estimation request unit K11, a communication state management unit K12, a route state information acquisition / notification unit K13, and a route state information storage unit K14.

  The route state information acquisition / notification unit K13 acquires the result of the terminal estimating the route state information, notifies the route state information storage unit K14, and requests the route state information from the transmission side terminal after the connection is established. In response to this, the route state information is acquired from the route state information storage unit K14 and notified to the terminal. When the transmission side terminal requests route state information, it notifies the communication state management unit K12 of the terminal with which communication is performed.

  The route state information storage unit K14 stores a route state estimation result performed by a terminal under management.

  The communication state management unit K12 receives notification of which terminal is communicating from the route state information acquisition / notification unit K13, and stores the terminal. In order to cause the terminal to estimate the route state, the measurement packet flows on the communication route and notifies the route information estimation request unit K11 of information on the terminal that is not performing communication so as not to affect the communication. To do.

  The route state estimation request unit K11 makes a route state estimation request to a terminal that is not performing communication notified from the communication state management unit K12.

(Description of operation)
Next, the operation of the fourth embodiment of the present invention will be described in detail with reference to FIG. 9, FIG. 10, FIG. 11 and FIG.

  The operation when S1 to Sn transmits data in FIG. 8 is the same, but here, consider a case where terminal S1 performs data communication as a transmitting terminal and terminal S2 as a receiving terminal.

  In FIG. 11, the route state information management terminal K10 sends a route state estimation request from the route state estimation request unit K11 to the terminals S1 to Sn (step D1). The route state estimation unit W10 of each terminal performs estimation upon receiving the estimation request notification. The measurement result and the reception buffer size are acquired by the path state information acquisition / notification unit K13, and are notified and stored in the path state information storage unit K14 (step D2).

  In FIG. 12, when a connection is established (step D7), the route state information acquisition / notification unit W13 of the terminal S1 requests route state information from the management terminal K10 (step D8).

  The connection establishment notification and the request for route state information from the transmission terminal S1 are received by the route state information acquisition / notification unit K13 of the route state information management terminal K10 (step D3). The route state information acquisition / notification unit K13 notifies the communication state management unit K12 that communication is performed between the terminals S1 and S2, and stores the information in the communication state management unit K12 (step D4).

  Further, the route state information and the reception buffer size are acquired from the route state information storage unit K14 and notified to the transmission terminal S1 (step D6).

  The path state information acquisition / notification unit W13 acquires the path state, notifies the physical band upper limit value of the bottleneck link to the target transmission rate W101, and notifies the RTT threshold value determination storage unit W103 of the minimum RTT.

  The target transmission rate determination storage unit W101 sets the notified band as the target transmission rate value A, and the target transmission rate value B is given as a value smaller than A. As the target transmission rate value B, for example, a packet size divided by the currently observed RTT or a transmission rate value depending on data characteristics can be considered. On the other hand, the RTT threshold value determination storage unit W103 determines the RTT threshold value based on the notified minimum RTT (step D9).

  The management terminal K10 notifies the terminal that is not communicating from the communication state management unit K12 (in this case, the terminal S1 and the terminal S2) to the route state estimation request unit K11, and the communication performed by the terminals S1 to Sn. So that the terminal that has received the notification estimates the path state, and obtains the estimation result and the reception buffer size (steps D1 and D2).

  When the target transmission rate value and the RTT threshold are determined, the transmission rate control unit W104 initializes the transmission rate (step D10), notifies the packet transmission unit W105 of the transmission rate, and the packet transmission unit W105 is notified of the transmission rate. Packets are transmitted at the transmission rate (step D11).

  When an ACK (acknowledgment response) packet for the transmission packet is returned from the receiving terminal, the packet receiving unit W106 receives the ACK packet (step D12).

  Thereafter, the RTT measurement unit W107 calculates the RTT using the transmission time of the transmission packet and the reception time when the ACK packet returned to the transmitted packet is received (step D13).

  The calculated RTT is notified to the RTT determination unit W108, and the RTT determination unit W108 compares the calculated RTT and the RTT threshold value notified from the RTT threshold value determination storage unit W103 when the RTT is larger than the RTT threshold value. When the RTT is equal to or less than the RTT threshold, the value “1” is notified to the target transmission rate selection unit (step D14).

  Further, when the target transmission rate selection unit W102 is notified of the target transmission rates A and B from the target transmission rate determination storage unit W101 and is notified of the value “0” from the RTT determination unit W108, the target transmission rate B is set to the value When “1” is notified, the target transmission rate A is selected and notified to the transmission rate control unit W104 (steps D15 and D16).

  The transmission rate control unit W104 compares the target transmission rate notified from the target transmission rate selection unit W102 with the current transmission rate. When the target transmission rate is the target transmission rate A, if the current transmission rate is smaller than A, the transmission rate is increased to the target transmission rate A. If the current transmission rate is equal to or higher than the target transmission rate A, The transmission rate is maintained or the target transmission rate A is set. When the target transmission rate is B, the transmission rate is set to B in any case (step D17).

  The determined transmission rate is notified to the transmission rate transmission unit W105 (step D18).

    If packet transmission is not completed (step D19), packet transmission is performed at the determined transmission rate (step D11). If packet transmission is completed, the connection is terminated (step D20), and the connection termination is routed. The communication state management unit K12 of the state information management terminal K10 is notified (step D21).

(Effect of the fourth embodiment)
The effect of the third embodiment will be described. If there is no other traffic on the bottleneck link between the transmitting and receiving terminals, the conventional method increases the transmission rate until the observed RTT exceeds a certain value, and if the observed RTT exceeds a certain value, Since the transmission rate is reduced, the link utilization rate is reduced. However, in this embodiment, since the transmission rate control is performed by determining whether there is other traffic on the bottleneck link from the magnitude relationship between the observed RTT and the RTT threshold, the bottle between the transmitting and receiving terminals is controlled. When there is no other traffic on the neck link, packets are transmitted at the target transmission rate A (the upper limit of the physical bandwidth of the bottleneck link), so the link utilization rate is improved, and the first and second problems of the conventional method The point has been eliminated.

  In the conventional method, when the observed RTT exceeds a certain value, it is estimated that other traffic exists, and the window size is reduced to half or one packet. However, in this embodiment, other traffic is reduced. If it is determined that it exists, the transmission rate is decreased to the target transmission rate B. Since the target transmission rate B can be determined according to the data characteristics, for example, it is possible to specify the minimum required bandwidth, and the third problem of the conventional method can be solved.

  Since the management terminal K10 knows which terminal is performing communication, the management terminal K10 estimates the physical band upper limit value and the minimum RTT of the bottleneck link to each terminal so as not to affect other communication. It becomes possible to make it.

  A fifth embodiment of the present invention will be described in detail with reference to the drawings. The network configuration is the same as that in FIG. 1, terminals S1 to Sn are arranged on the network, and data communication is performed between the terminals S1 to Sn.

  Again, since the terminals S1 to Sn have the same internal configuration, the terminal S1 will be described.

  FIG. 13 shows the internal configuration of the terminal S1 according to the fifth embodiment. The terminal S1 includes an information notification acquisition unit X10 and a data transmission / reception control unit X100.

  The information notification acquisition unit X10 includes a route state / terminal information notification acquisition unit X11 and a route state / terminal information storage unit X12.

  The data transmission / reception control unit X100 includes a target transmission rate estimation unit X101, a target transmission rate determination storage unit X102, an RTT threshold determination storage unit X103, a target transmission rate selection unit X104, a transmission rate control unit X105, a packet transmission unit X106, a packet reception Part X107, RTT measurement part X108, and RTT determination part X109. Each component will be described below.

  The route state / terminal information notification obtaining unit X11 obtains route state information (the bottleneck link physical bandwidth and the minimum RTT between the transmitting and receiving terminals) from the target transmission rate determination storage unit X101 and the RTT threshold value determination storage unit X103, and the terminal S2 ~ Sn is notified of the path state information and the size of the reception buffer of the terminal itself.

  The notified route state information and the reception buffer size are stored in the route state / terminal information storage unit X12. The path state information is the physical bandwidth and the minimum RTT of the bottleneck link between terminals, and the terminal information is the reception buffer size.

  By notifying each terminal of route state information (bottleneck link physical bandwidth, minimum RTT), depending on data characteristics (for example, when high bandwidth is required or when real-time performance is required) A route can be selected. In addition, when requesting relay from the terminals S2 to Sn, it is possible to select a relay destination according to the data characteristics by notifying the reception buffer size indicating the reception capability of the terminal.

  The target transmission rate estimation unit X101 uses the transmission band notified from the transmission rate control unit X105 and the RTT notified from the RTT measurement unit X108, and the physical band upper limit value of the bottleneck link between the transmission and reception terminals (target transmission rate A). Estimate As the estimation method, the estimation method based on inline measurement already described in the first embodiment is used. The target transmission rate determination storage unit N101 estimates the target transmission rate A by this estimation method.

  The target transmission rate determination storage unit X102 determines target transmission rates A and B and stores them. The target transmission rate A is a rate value notified from the target transmission rate estimation unit X101, and the target transmission rate B is determined to be a value smaller than the target transmission rate A. The target transmission rate B is determined according to, for example, a value obtained by dividing the packet size by the RTT threshold value stored in the RTT threshold value determination storage unit X103, or data characteristics.

  The RTT threshold value determination storage unit X103 obtains, from the target transmission rate estimation unit X101, the window size and RTT set information obtained by the estimation method shown in the first embodiment, and obtains the minimum RTT (RTT_min) in FIG. 19 as the RTT threshold value. As determined and memorized. In the present invention, since the transmission rate is controlled with the window size equal to or smaller than the window size WA in FIG. 19, when the RTT observed on the transmission side exceeds the minimum RTT (RTT_min), other traffic exists. It is possible to judge.

  The RTT determination unit X109 determines whether there is other traffic between the transmitting and receiving terminals using the RTT obtained from the RTT measurement unit X108 and the RTT threshold obtained from the RTT threshold determination storage unit X103.

  In this embodiment, transmission rate control is performed with the maximum value of the window size (the amount of packets transmitted during one RTT) being the window size WA of FIG. 19, and this is observed when there is no other traffic between the transmitting and receiving terminals. The RTT is the minimum RTT (RTT_min) in FIG.

  When other traffic flows into the bottleneck link, packets start to be accumulated in the buffer of the bottleneck link router, and the RTT measurement unit X108 of the terminal S1 on the transmission side observes an RTT value exceeding the minimum RTT (RTT_min). Accordingly, when the measured RTT exceeds the RTT threshold, the RTT measuring unit X108 determines that there is other traffic between the transmitting and receiving terminals, and sets the value “0”. When the RTT is the RTT threshold, the transmitting and receiving terminals It is determined that no other traffic exists between them, and the value “1” is notified to the target transmission rate selection unit X104.

  The target transmission rate selection unit X104 selects the target transmission rate B when the value “0” is notified as information from the RTT determination unit X109 (other traffic exists on the bottleneck link between the transmitting and receiving terminals). When the value “1” is notified (no other traffic exists on the bottleneck link between the transmitting and receiving terminals), the target transmission rate A is selected. The selected result is notified to the transmission rate control unit X105.

  The transmission rate control unit X105 determines the transmission rate by comparing the current transmission rate with the target rate notified from the target transmission rate selection unit X104, and notifies the packet transmission unit X106 and the target transmission rate estimation unit X101. When the target transmission rate is B, the transmission rate is B, and when the target transmission rate is A, when the current transmission rate is smaller than A, the transmission rate is increased to the target transmission rate A, and the current transmission rate is If it is equal to or higher than the target transmission rate A, the transmission rate is set to A.

  The packet transmission unit X106 transmits a packet at the transmission rate notified from the transmission rate control unit X105.

The packet receiving unit X107 receives a packet transmitted from another terminal and an ACK (acknowledgment) packet for the transmitted packet. Further, the RTT measuring unit X108 measures the RTT (round trip delay time) using the transmission time of the data packet and the reception time of the ACK (acknowledgment) packet. The measured RTT is notified to the RTT determination unit X109.

(Description of operation)
Next, the operation of the fifth embodiment of the present invention will be described in detail with reference to FIGS. 13, 14 and 19. FIG.

  When S1 to Sn transmit data in FIG. 1, since the terminals S1 to Sn perform the same operation, consider a case where the terminal S1 performs data communication as a transmitting terminal.

  In FIG. 14, when a connection is established (step E1), first, the target transmission rate estimation unit X101 makes an inquiry to the target transmission rate determination storage unit X102 and the RTT threshold determination storage unit X103, and the history obtained in the past communication It is checked whether information (target transmission rates A and B and the RTT threshold value) is stored (step E2). If they are stored, the target transmission rates A and B and the RTT threshold are determined based on the stored values (step E3). If the history information is not stored, group information is obtained by combining the window size during packet transmission and the RTT for the window size, and the target transmission rates A, B, and the RTT threshold are estimated (step E4). ),decide.

  In the following description, the history information (target transmission rates A and B and the RTT threshold) is stored separately when the connection is established and when it is not.

  When history information is stored in step E2, at the start of packet transmission, the transmission rate control unit X105 initializes the transmission rate (step E5). In this initialization, for example, a value obtained by dividing the packet size by the RTT threshold value (RTT_min) stored in the RTT threshold value determination storage unit X103, or the target transmission rate B is set as the transmission rate.

  The packet transmission unit X106 transmits the packet at the transmission rate notified from the transmission rate control unit X105 (step E6). When an ACK packet is returned as a confirmation response to the transmission packet from the reception side, the packet reception unit X107 receives the packet (step E7).

  When the ACK packet is received, the RTT is measured by using the time when the RTT measuring unit X108 transmits the packet and the time when the ACK packet corresponding to the transmission packet is received (step E8).

  The RTT determination unit X109 compares the RTT notified from the RTT measurement unit X108 with the RTT threshold notified from the RTT threshold determination storage unit X103, and determines whether there is other traffic on the bottleneck link between the transmitting and receiving terminals. (Step E9).

  In this embodiment, since the window size (the amount of packets transmitted during one RTT) is controlled within the window size WA or less, if there is no other traffic on the bottleneck link between the transmitting and receiving terminals, the transmitting terminal The RTT of the RTT threshold (RTT_min) in FIG. 19 is observed. When other traffic exists on the bottleneck link between the transmitting and receiving terminals, an RTT larger than the RTT threshold (RTT_min) is observed. Therefore, if the RTT is larger than the RTT threshold, it is determined that other traffic is present on the bottleneck link. If the RTT is equal to the RTT threshold, it is determined that there is other traffic on the bottleneck link. It decides not to do so, and notifies the target transmission rate selection unit X104 of the value “1”. The target transmission rate selection unit X104 selects the target transmission rate B when receiving the notification of the value “0” from the RTT determination unit X109, and selects the target transmission rate A when receiving the notification of the value “1”. The result is notified to the transmission rate control unit X105 (steps E10 and E11).

  When receiving the notification of the target transmission rate B, the transmission rate control unit X105 sets the transmission rate to B. When the notification of the target transmission rate A is received, the current transmission rate is compared with A, and if the current transmission rate is smaller than the target transmission rate A, the transmission rate is increased to the target transmission rate A. When the current transmission rate is equal to or higher than the target transmission rate A, the above is maintained or set to the target transmission rate A (step E12). The transmission rate control unit X105 notifies the packet transmission unit X106 of the determined transmission rate (step E13).

  If packet transmission has not ended (step E14), packet transmission is performed at the determined transmission rate (step E6). If packet transmission has ended, the connection is ended (step E15).

  The route state / terminal information notification obtaining unit X11 obtains route state information from the route state / terminal information storage unit X12, and notifies the route state information and the size of the reception buffer to the terminals S2 to Sn (step E16).

  If no history information is stored, the transmission rate control unit X105 initializes the transmission rate. In the initialization in this case, since the RTT is not the stored known value, the window size is set to 1 packet as the transmission rate. Further, the transmission rate is notified to the target transmission rate estimation unit X101, and the packet transmission unit L106 is notified to transmit a packet at the transmission rate.

  When an ACK packet is returned from the receiving side as a confirmation response to the transmission packet, the packet receiving unit X107 receives the ACK packet. When reception is performed, RTT is measured using the time when the RTT measuring unit X108 transmits the packet and the time when the ACK packet for the transmission packet is received, and the target transmission rate estimating unit X101 is notified.

  The target transmission rate estimation unit X101 stores group information that is a set of RTTs for the window size (amount of packets transmitted during 1 RTT) and the window size (amount of packets transmitted during 1 RTT). The transmission rate control unit X105 controls the transmission rate using a conventional TCP transmission rate control method. The target transmission rate estimation unit L101 collects a plurality of sets of information and determines the target transmission rates A and B and the RTT threshold value by the estimation method shown in the first embodiment. Further, the target transmission rate A and the RTT threshold value are notified from the target transmission rate determination storage unit X102 and the RTT threshold value determination storage unit X103 to the route state / terminal information notification acquisition unit X12, respectively.

  When the target transmission rates A and B and the RTT threshold are determined, the subsequent operation (operation after step E5) is the same as when history information is stored at the time of connection establishment.

(Effects of the fifth embodiment)
The effects of the first embodiment will be described. If there is no other traffic on the bottleneck link between the transmitting and receiving terminals, the conventional method increases the transmission rate until the observed RTT exceeds a certain value, and if the observed RTT exceeds a certain value, Since the transmission rate is reduced, the link utilization rate is reduced. However, in this embodiment, the transmission rate is controlled by determining whether there is other traffic on the bottleneck link from the magnitude relationship between the observed RTT and the RTT threshold, and therefore, between the transmitting and receiving terminals. When there is no other traffic on the bottleneck link, packets are transmitted at the target transmission rate A (the upper limit value of the physical bandwidth of the bottleneck link), thereby improving the link utilization rate. The problem is solved.

  Further, in the conventional method, when the observed RTT exceeds a certain value, it is estimated that other traffic exists, and the window size is reduced to half or “1”. If it is determined that it exists, the transmission rate is decreased to the target transmission rate B. Since the target transmission rate B can be determined according to the data characteristics, for example, it is possible to specify the minimum required bandwidth, and the third problem of the conventional method can be solved.

  By reporting the bottleneck link physical band upper limit value, minimum RTT, and reception buffer size obtained by data transfer to the communication partner terminal, each terminal can select the route and relay destination according to the data characteristics. It becomes.

  A sixth embodiment of the present invention will be described in detail with reference to the drawings. The network configuration is the same as that in FIG. 1, terminals S1 to Sn are arranged on the network, and data communication is performed between the terminals S1 to Sn.

  Again, since the terminals S1 to Sn have the same internal configuration, the terminal S1 will be described.

  Referring to FIG. 15, a terminal S1 according to the sixth embodiment includes a route state estimation unit Y10 and a data transmission / reception control unit Y100.

  The route state estimation unit Y10 measures the bandwidth between terminals and RTT. It has a function of estimating the route state from the measured result, and includes a test packet transmitting / receiving unit Y11, a route state measuring unit Y12, a route state / terminal information storage unit Y13, and a route state / terminal information notification obtaining unit Y14. .

  The data transmission / reception control unit Y100 has a function of performing transmission rate control depending on the route state information estimated by the route state estimation unit Y10, and includes a target transmission rate determination storage unit Y101, a target transmission rate selection unit Y102, a transmission rate. A control unit Y104, a packet transmission unit Y105, a packet reception unit Y106, an RTT measurement unit Y107, an RTT determination unit Y108, and an RTT threshold value determination storage unit Y103 are provided. Each component will be described below.

  The route state estimation unit Y10 has a function of estimating a route state between transmitting and receiving terminals and a function of storing route state information. The path state information is the physical bandwidth and the minimum RTT of the bottleneck link. The estimation of the physical bandwidth of the bottleneck link is as follows. As described in the second embodiment, the estimation method of the physical bandwidth of the bottleneck link is the same as the estimation method described in the first embodiment. An estimation method using a method (method described in Non-Patent Document 5) is used. The details are omitted here.

  The minimum RTT is calculated by using the estimation method described in the first embodiment and the packet-pair method, using the time when the measurement packet is transmitted and the arrival time of the packet returned as a response on the receiving side. Calculate the minimum value as the estimation result. The estimated result is stored in the route state information storage unit Y12. The stored result is notified to the data transmission / reception control unit Y100 and used to determine the transmission rate.

  Further, the path state / terminal information notification acquisition unit Y14 notifies the terminals S2 to Sn of the path state information (bottleneck link physical band, minimum RTT) and the reception buffer size obtained from the path state / terminal information storage unit Y13. . This makes it possible to select a route according to data characteristics (for example, when a high bandwidth is required or when real-time performance is required). In addition, when requesting relay from the terminals S2 to Sn, it is possible to select a relay destination according to the data characteristics by notifying the reception buffer size indicating the reception capability of the terminal.

  The data transmission / reception control unit Y100 has a function equivalent to TCP (Transmission Control Protocol), which is one of the transport layer protocols of the OSI reference model. Connection establishment, suspension, termination, confirmation response function, retransmission control function It is.

  The target transmission rate determination storage unit Y101 determines and stores two target transmission rates A and B. The target transmission rate A is set as the physical band upper limit value of the bottleneck link notified from the path state information storage unit Y13. The target transmission rate B is determined by a value smaller than the target transmission rate A. The target transmission rate B is determined by, for example, a value obtained by dividing the packet size by RTT, or a value according to data characteristics.

  The RTT threshold value determination storage unit Y103 stores the value notified from the route state / terminal information storage unit Y13 as the RTT threshold value. At this time, the value notified from the route state / terminal information storage unit Y13 is equal to the minimum RTT (RTT_min) in FIG.

  The RTT determination unit Y108 determines whether there is other traffic between the transmitting and receiving terminals using the RTT obtained from the RTT measurement unit Y107 and the RTT threshold obtained from the RTT threshold determination storage unit Y103.

  In this embodiment, transmission rate control is performed with the maximum value of the transmission rate as the target transmission rate A, and the RTT observed when there is no other traffic between the transmitting and receiving terminals is the minimum RTT (RTT_min) in FIG. It becomes.

  When other traffic flows into the bottleneck link, packets start to be accumulated in the buffer of the bottleneck link router, and the RTT measurement unit Y107 of the terminal S1 on the transmission side observes an RTT value exceeding the minimum RTT (RTT_min). Accordingly, when the measured RTT exceeds the RTT threshold, the RTT measurement unit Y107 determines that other traffic exists between the transmitting and receiving terminals, and sets the value “0”. When the RTT is the RTT threshold, the transmitting and receiving terminals It is determined that no other traffic exists between them, and the value “1” is notified to the target transmission rate selection unit Y104.

  The target transmission rate selection unit Y102 selects one of the two target transmission rates A and B in the target transmission rate storage unit based on the information notified from the RTT determination unit Y108. If RTT is equal to or less than the RTT threshold, it is determined that no other traffic exists on the path between the transmitting and receiving terminals, and the target transmission rate A is selected as the target transmission rate. Conversely, if RTT is greater than the RTT threshold, The target transmission rate B is selected as the target transmission rate by recognizing that there is other traffic between the transmitting and receiving terminals. The selected result is notified to the transmission rate control unit Y104.

  The transmission rate control unit Y104 determines the transmission rate by comparing the target transmission rate notified from the target transmission rate selection unit Y102 with the current transmission rate. When the target transmission rate is B, the transmission rate is B, and when the target transmission rate is A, when the transmission rate is lower than A, the transmission rate is increased to the target transmission rate A, and the current transmission rate is the target transmission. If it is equal to or greater than rate A, the transmission rate is set to A.

  The packet transmission unit Y105 transmits a packet according to the transmission rate notified from the transmission rate control unit Y104.

  The packet receiving unit Y106 is a part that receives an ACK packet as a feedback for a packet transmitted from another terminal or a transmitted packet.

  The RTT measurement unit Y107 measures the RTT using the transmission time of the transmission packet and the reception time of the ACK packet returned to the transmission packet.

(Description of operation)
Next, the operation of the sixth embodiment of the present invention will be described in detail with reference to FIG. 1, FIG. 15, and FIG.

  When S1 to Sn transmit data in FIG. 1, since the terminals S1 to Sn perform the same operation, consider a case where the terminal S1 performs data communication as a transmitting terminal.

  In FIG. 16, the route state estimation unit Y10 of the terminal S1 estimates the bottleneck link and the minimum RTT between the transmitting and receiving terminals. In this estimation process, first, a measurement packet is transmitted from the measurement packet transmitting / receiving unit Y11 (step F1). Then, an ACK packet from the receiving terminal is received (step F2).

  The route state measurement unit Y12 estimates the physical band of the bottleneck link and the minimum RTT from the measured values, and notifies the route state / terminal information storage unit Y13 (steps F3 and F4). The route state / terminal information storage unit Y13 stores the physical bandwidth upper limit value and the minimum RTT notified from the route state measurement unit Y12, and the route state / terminal information notification acquisition unit Y14 receives the route state information from the route state information storage unit Y13. Is notified to the terminals S2 to Sn (step F5).

  When the connection is established (step F6), the path state / terminal information storage unit Y13 notifies the target transmission rate storage unit Y101 and the RTT threshold determination storage unit Y103 of the bottleneck physical band and the minimum RTT, respectively. The

  The RTT threshold value determination storage unit Y103 determines and stores the RTT threshold value depending on the notified minimum RTT. The target transmission rate determination storage unit Y101 sets the notified physical band upper limit value as the target transmission rate value A, and gives the target transmission rate value B as a value smaller than A (step F7). For example, as the target transmission rate value B, a value obtained by dividing the packet size by RTT, or a transmission rate value depending on data characteristics can be considered.

  When the target transmission rate values A and B and the RTT threshold value are determined, the transmission rate control unit Y104 initializes the transmission rate (step E8). In this initialization, for example, a value obtained by dividing the packet size by RTT or the target transmission rate B is set as the transmission rate.

  The transmission rate is notified from the transmission rate control unit Y104 to the packet transmission unit Y105, and the packet transmission unit Y105 transmits the packet at the notified transmission rate (step E9).

  When an ACK (acknowledgment) packet for the transmission packet is returned from the receiving terminal, the packet receiving unit Y106 receives the ACK packet (step E10).

  Thereafter, the RTT measurement unit Y107 calculates the RTT using the transmission time of the transmission packet and the reception time when the ACK packet returned to the transmitted packet is received (step E11).

  The RTT determination unit Y108 compares the RTT notified from the RTT measurement unit Y107 with the RTT threshold notified from the RTT threshold determination storage unit Y103, and determines whether there is other traffic on the link between the transmitting and receiving terminals ( Step E12). When there is no other traffic between the transmitting and receiving terminals, the transmitting terminal S1 observes RTT_min in FIG. When other traffic exists between the transmitting and receiving terminals, packets start to be accumulated in the buffer of the bottleneck link router, and the RTT exceeding the RTT threshold is observed. Therefore, when RTT is larger than the RTT threshold, it is determined that other traffic exists on the bottleneck link between the transmitting and receiving terminals, and when the RTT is equal to or less than the RTT threshold, other values are set for the bottleneck link between the transmitting and receiving terminals. And the value “1” is notified to the target transmission rate selection unit Y102 (steps E13 and E14).

  The target transmission rate selection unit Y102 is notified of the target transmission rates A and B from the target transmission rate determination storage unit Y101 and is notified of the value “0” from the RTT determination unit Y108. When “1” is notified, the target transmission rate A is selected and notified to the transmission rate control unit Y104.

  When receiving the notification of the target transmission rate B from the target transmission rate selection unit Y102, the transmission rate control unit Y104 sets the transmission rate to B. When the notification of the target transmission rate A is received, the notified target transmission rate is compared with the current transmission rate. When the target transmission rate is the target transmission rate A and the current transmission rate is smaller than A, the transmission rate Is increased to the target transmission rate A. If the current transmission rate is equal to or higher than the target transmission rate A, the transmission rate is maintained or set to the target transmission rate A (step E15).

  The transmission rate control unit Y104 notifies the determined transmission rate to the packet transmission unit Y105 (step E16). If packet transmission has not ended (step E17), packet transmission is performed at the determined transmission rate (step E9). If packet transmission has ended, the connection is ended (step E18).

(Effect of the sixth embodiment)
The effect of the sixth embodiment will be described. If there is no other traffic on the bottleneck link between the transmitting and receiving terminals, the conventional method increases the transmission rate until the observed RTT exceeds a certain value, and if the observed RTT exceeds a certain value, Since the transmission rate is reduced, the link utilization rate is reduced. However, in this embodiment, since the transmission rate control is performed by determining whether there is other traffic on the bottleneck link from the magnitude relationship between the observed RTT and the RTT threshold, the bottle between the transmitting and receiving terminals is controlled. When there is no other traffic on the neck link, packets are transmitted at the target transmission rate A (the upper limit of the physical bandwidth of the bottleneck link), so the link utilization rate is improved, and the first and second problems of the conventional method The point has been eliminated.

  In the conventional method, when the observed RTT exceeds a certain value, it is estimated that other traffic exists, and the window size is reduced to half or one packet. However, in this embodiment, other traffic is reduced. If it is determined that it exists, the transmission rate is decreased to the target transmission rate B. Since the target transmission rate B can be determined according to the data characteristics, for example, it is possible to specify the minimum required bandwidth, and the third problem of the conventional method can be solved.

  In the first embodiment, when no past communication history remains, until the bottleneck link physical band upper limit value and the minimum RTT are estimated, other traffic sharing the bottleneck link between the transmitting and receiving terminals is used. On the other hand, the priority control of the throughput could not be performed, but the physical band upper limit value and the minimum RTT of the bottleneck link are given at the start of packet transmission, so the priority control of the throughput is possible from the start of packet transmission Thus, it is possible to minimize the influence on other traffic.

  By notifying the obtained physical bandwidth, minimum RTT, and reception buffer size of the bottleneck link to the terminal serving as a communication partner, each terminal can select a route and a relay destination according to data characteristics.

  A seventh embodiment of the present invention will be described in detail with reference to the drawings. The network configuration is the same as that in FIG. 1, terminals S1 to Sn are arranged on the network, and data communication is performed between the terminals S1 to Sn.

  Again, since the terminals S1 to Sn have the same internal configuration, the terminal S1 will be described.

  Referring to FIG. 17, the terminal S1 according to the seventh embodiment includes a route state estimation unit Z10 and a data transmission / reception control unit Z100.

  The route state estimation unit Z10 measures the bandwidth between terminals and RTT. It has a function of estimating a route state from the measured result, and includes a test packet transmitting / receiving unit Z11, a route state measuring unit Z12, a route state / terminal information storage unit Z13, and a route state / terminal information notification acquiring unit Z14. .

  The data transmission / reception control unit Z100 has a function of performing transmission rate control depending on the route state information estimated by the route state estimation unit Z10, and includes a target transmission rate determination storage unit Z101, a target transmission rate selection unit Z102, a transmission rate. A control unit Z104, a packet transmission unit Z105, a packet reception unit Z106, an RTT measurement unit Z107, an RTT determination unit Z108, and an RTT threshold value determination storage unit Z103 are provided. Each component will be described below.

  The route state estimation unit Z10 has a function of estimating a route state between transmitting and receiving terminals and a function of storing route state information. The path state information is information including the physical bandwidth of the bottleneck link and the minimum RTT. As described in the second embodiment, the physical bandwidth of the bottleneck link is estimated by the estimation method described in the first embodiment or the Packet-Pair method (the method described in Non-Patent Document 5). The method is used. The details are omitted here.

  The minimum RTT is calculated by using the estimation method described in the first embodiment and the packet-pair method, using the time when the measurement packet is transmitted and the arrival time of the packet returned as a response on the receiving side. Calculate the minimum value as the estimation result. The estimated result is stored in the route state information storage unit Z12. The stored result is notified to the data transmission / reception control unit Z100 and used for determining the transmission rate.

  Further, the path state / terminal information notification acquisition unit Z14 notifies the terminals S2 to Sn of the path state information (bottleneck link physical band, minimum RTT) obtained from the path state / terminal information storage unit Z13 and the reception buffer size. . This makes it possible to select a route according to data characteristics (for example, when a high bandwidth is required or when real-time performance is required). In addition, when requesting relay from the terminals S2 to Sn, it is possible to select a relay destination according to the data characteristics by notifying the reception buffer size indicating the reception capability of the terminal.

  The data transmission / reception control unit Z100 has a function equivalent to TCP (Transmission Control Protocol), which is one of the transport layer protocols of the OSI reference model. An acknowledgment function, a retransmission control function, and a congestion control function.

  The target transmission rate determination storage unit Z101 determines two target transmission rates A and B for each terminal on the receiving side based on the route state information notified from the route state information estimation unit. The target transmission rate A is the maximum transmission rate value that can be output when there is no other traffic on the route to the receiving terminal, and the target transmission rate B is a value smaller than A. As the target transmission rate B, a value obtained by dividing the packet size by the RTT or a transmission rate value instructed by the application in accordance with the data characteristics and smaller than the target transmission rate A is used.

  Further, the target transmission rate determination storage unit Z101 also performs estimation of the path state using the transmission rate value notified from the transmission rate control unit Z104 and the RTT measured by the RTT measurement unit Z107. For estimation during data transmission, the estimation method based on inline measurement already described in the first embodiment is used. The target transmission rate determination storage unit Z101 estimates the target transmission rate A by this estimation method.

  The target transmission rate determination storage unit Z101 determines and stores two target transmission rates A and B. About the target transmission rate A, it is set as the physical band value upper limit value of the bottleneck link notified from the path | route state information storage part Z13. The target transmission rate B is determined with a value smaller than the target transmission rate A. The target transmission rate B is determined by, for example, a value obtained by dividing the packet size by RTT, or a value according to data characteristics. Even during packet transmission, the transmission rate value is obtained from the transmission rate control unit Z104 and the RTT value is obtained from the RTT measurement unit Z107, and the physical band value upper limit value of the bottleneck link is estimated.

  The RTT threshold value determination storage unit Z103 stores the value notified from the route state information storage unit Z13 as the RTT threshold value. At this time, the value notified from the route state / terminal information storage unit Z13 is equal to the minimum RTT (RTT_min) in FIG.

  The RTT determination unit Z108 determines whether there is other traffic between the transmitting and receiving terminals using the RTT obtained from the RTT measurement unit Z107 and the RTT threshold obtained from the RTT threshold value determination storage unit Z103.

  In this embodiment, the transmission rate is controlled with the maximum value of the transmission rate as the target transmission rate A, and the RTT observed when there is no other traffic between the transmitting and receiving terminals is the minimum RTT (RTT_min in FIG. 19). )

  When other traffic flows into the bottleneck link, packets start to be accumulated in the buffer of the bottleneck link router, and the RTT measurement unit Z107 of the terminal S1 on the transmission side observes an RTT value exceeding the minimum RTT (RTT_min). Accordingly, when the measured RTT exceeds the RTT threshold, the RTT measuring unit Z107 determines that there is other traffic between the transmitting and receiving terminals, and sets the value “0”. When the RTT is the RTT threshold, the transmitting and receiving terminals It is determined that no other traffic exists between them, and the value “1” is notified to the target transmission rate selection unit Z104.

  The target transmission rate selection unit Z102 selects one of the two target transmission rates A and B in the target transmission rate determination storage unit Z101 based on the information notified from the RTT determination unit Z108. If RTT is equal to or less than the RTT threshold, it is determined that no other traffic exists on the path between the transmitting and receiving terminals, and the target transmission rate A is selected as the target transmission rate. Conversely, if RTT is greater than the RTT threshold, The target transmission rate B is selected as the target transmission rate by recognizing that there is other traffic between the transmitting and receiving terminals. The selected result is notified to the transmission rate control unit Z104.

  The transmission rate control unit Z104 determines the transmission rate by comparing the current transmission rate with the target transmission rate notified from the target transmission rate selection unit Z102. When the target transmission rate is B, the transmission rate is set to B regardless of the current transmission rate. When the target transmission rate is A, when the transmission rate is lower than A, the transmission rate is increased to the target transmission rate A. When the current transmission rate is equal to or higher than the target transmission rate A, the transmission rate is set to A.

  The packet transmission unit Z105 transmits a packet according to the transmission rate notified from the transmission rate control unit Z104.

  The packet receiving unit Z106 is a part that receives an ACK packet as a feedback for a packet transmitted from another terminal or a transmitted packet.

  The RTT measurement unit Z107 measures the RTT using the transmission time of the transmission packet and the reception time of the ACK packet returned to the transmission packet.

(Description of operation)
Next, the operation of the seventh embodiment of the present invention will be described in detail with reference to FIG. 1, FIG. 17, and FIG.

    Since the operations when S1 to Sn transmit data in FIG. 1 are the same, the case where the terminal S1 performs data communication as a transmitting terminal is considered here.

  In FIG. 18, the route state estimation unit Z10 of the terminal S1 estimates the bottleneck link and the minimum RTT between the transmitting and receiving terminals. In this estimation process, first, a measurement packet is transmitted from the measurement packet transmitting / receiving unit Z11 (step G1). Then, an ACK packet is received as feedback from the receiving terminal (step G2).

  The path state measurement unit Z12 estimates the physical band upper limit value and the minimum RTT of the bottleneck link from the measured values, and notifies the path state / terminal information storage unit Z13 (steps G3 and G4). The route state / terminal information storage unit Z13 stores the physical bandwidth upper limit value and the minimum RTT notified from the route state measurement unit Z12. The route state / terminal information notification acquisition unit Z14 acquires route state information from the route state information storage unit Z13 and notifies the terminals S2 to Sn (step G5).

  When the connection is established (step G6), the bottleneck physical bandwidth upper limit value and the minimum RTT are respectively sent from the route state / terminal information storage unit Z13 to the target transmission rate storage unit Z101 and the RTT threshold value determination storage unit Z103. Be notified.

  The RTT threshold value determination storage unit Z103 determines and stores the RTT threshold value based on the notified minimum RTT. On the other hand, the target transmission rate determination storage unit Z101 sets the notified physical band upper limit value as the target transmission rate value A, and gives the target transmission rate value B as a value smaller than A (step G7). For example, as the target transmission rate value B, a value obtained by dividing the packet size by RTT, or a transmission rate value depending on data characteristics can be considered.

  When the target transmission rate values A and B and the RTT threshold value are determined, the transmission rate control unit Z104 performs transmission rate processing (step G8). In this initialization, for example, a value obtained by dividing the packet size by the RTT threshold or the target transmission rate B is set as the transmission rate.

  The transmission rate control unit Z104 notifies the transmission rate to the packet transmission unit Z105, and the packet transmission unit Z105 transmits the packet at the notified transmission rate (step G9).

  When an ACK (acknowledgment) packet for the transmission packet is returned from the receiving terminal, the packet receiving unit Z106 receives the ACK packet (step G10).

  Thereafter, the RTT measurement unit Z107 calculates the RTT using the transmission time of the transmission packet and the reception time when the ACK packet returned to the transmitted packet is received (step G11).

  The calculated RTT is notified to the target transmission rate determination storage unit Z101 and the RTT determination unit Z108.

  The RTT determination unit Z108 determines whether there is other traffic in the path between the transmitting and receiving terminals by comparing the RTT notified from the RTT measurement unit Z107 and the RTT threshold notified from the RTT threshold value determination storage unit Z103. (Step G12). When there is no other traffic between the transmitting and receiving terminals, the transmitting terminal S1 observes the minimum RTT (RTT_min) in FIG. When other traffic exists between the transmitting and receiving terminals, packets start to be accumulated in the buffer of the bottleneck link router, and the RTT exceeding the RTT threshold is observed. Therefore, when RTT is larger than the RTT threshold, it is determined that other traffic exists on the bottleneck link between the transmitting and receiving terminals, and when the RTT is equal to or less than the RTT threshold, other values are set for the bottleneck link between the transmitting and receiving terminals. And the target transmission rate selection unit Z102 is notified of the value “1” (steps G13 and G14).

  Further, when the target transmission rate selection unit Z102 is notified of the target transmission rates A and B from the target transmission rate determination storage unit Z101 and is notified of the value “0” from the RTT determination unit Z108, the target transmission rate B is When “1” is notified, the target transmission rate A is selected and notified to the transmission rate control unit Z104.

  The transmission rate control unit Z104 compares the target transmission rate notified from the target transmission rate selection unit Z102 with the current transmission rate. When the target transmission rate is the target transmission rate A, if the current transmission rate is smaller than the target transmission rate A, the transmission rate is increased to the target transmission rate A, and the current transmission rate is equal to or higher than the target transmission rate A. In this case, the transmission rate is maintained or set to the target transmission rate A. When the target transmission rate is B, the transmission rate is B in any case. When the target transmission rate is B, the transmission rate is set to B in any case (step G15).

  The determined transmission rate is notified to the target transmission rate determination storage unit Z101 and the packet transmission unit Z105 (step G16).

  If packet transmission has not ended (step G20), packet transmission is performed at the determined transmission rate (step G9). If packet transmission has ended, the connection is ended (step G21).

  The target transmission rate determination storage unit Z101 is notified of the upper limit value of the physical bandwidth of the bottleneck link from the path state information storage unit Z13, and not only stores it as the target transmission rate A but also notifies it from the transmission rate control unit Z104. Information about the transmission rate and the RTT notified from the RTT measuring unit Z107 is obtained, and the estimation method described above is used to estimate the physical band upper limit value and the minimum RTT of the bottleneck link even after the connection is established. (Step G17). If the estimation result is different from the stored content, the target transmission rate and the RTT threshold are updated (step G7). Otherwise, the estimation result is ignored (step G19).

(Effect of the seventh embodiment)
The effect of the seventh embodiment will be described. If there is no other traffic on the bottleneck link between the transmitting and receiving terminals, the conventional method increases the transmission rate until the observed RTT exceeds a certain value, and if the observed RTT exceeds a certain value, Since the transmission rate is reduced, the link utilization rate is reduced. However, in this embodiment, since the transmission rate control is performed by determining whether there is other traffic on the bottleneck link from the magnitude relationship between the observed RTT and the RTT threshold, the bottle between the transmitting and receiving terminals is controlled. When there is no other traffic on the neck link, packets are transmitted at the target transmission rate A (the physical bandwidth of the bottleneck link), so the link utilization rate is improved, and the first and second problems of the conventional method are solved. It has been resolved.

  In the conventional method, when the observed RTT exceeds a certain value, it is estimated that other traffic exists, and the window size is reduced to half or one packet. However, in this embodiment, other traffic is reduced. If it is determined that it exists, the transmission rate is decreased to the target transmission rate B. Since the target transmission rate B can be determined according to the data characteristics, for example, it is possible to specify the minimum required bandwidth, and the third problem of the conventional method can be solved.

  In the first embodiment, when no past communication history remains, until the bottleneck link physical band upper limit value and the minimum RTT are estimated, other traffic sharing the bottleneck link between the transmitting and receiving terminals is used. On the other hand, the priority control of the throughput could not be performed, but the physical band upper limit value and the minimum RTT of the bottleneck link are given at the start of packet transmission, so the priority control of the throughput is possible from the start of packet transmission Thus, it is possible to minimize the influence on other traffic.

  Even during packet transmission, by estimating the upper limit of the physical bandwidth of the bottleneck link and the minimum RTT, the accuracy of estimation can be improved, and the accuracy of priority control of throughput is improved.

  By notifying the obtained physical band upper limit value, the minimum RTT, and the reception buffer size of the bottleneck link to the terminal serving as the communication partner, each terminal can select a route and a relay destination according to the data characteristics.

  Note that the functions of the terminal and the management terminal in each of the above-described embodiments can be realized by, for example, providing the computer device with the functions of the above-described units. Specifically, it may be realized by executing a program that achieves each function in software by the CPU. When the functions of the terminals and the management terminal are realized by software, a communication program for realizing the functions is loaded and executed on a computer processing device (CPU) capable of program control. This communication program is stored in a magnetic disk, a semiconductor memory, or other recording medium, loaded from the recording medium to a computer processing apparatus, and controls the operation of the CPU, thereby achieving a unique function as each apparatus.

  The present invention has been described with reference to the preferred embodiments. However, the present invention is not necessarily limited to the above embodiments. It goes without saying that various modifications can be made without departing from the scope of the present invention.

It is a figure which shows the network structure to which this invention is applied. It is a block diagram which shows the internal structure of the data transmission / reception control part of the terminal by 1st Example of this invention. It is a flowchart which shows the flow of operation | movement of the 1st Example of this invention. It is a block diagram which shows the internal structure of the terminal by the 2nd Example of this invention. It is a flowchart which shows the flow of operation | movement of the 2nd Example of this invention. It is a block diagram which shows the internal structure of the path | route state estimation part of a terminal and the data transmission / reception control part by 3rd Example of this invention. It is a flowchart which shows the flow of operation | movement of the 3rd Example of this invention. It is a figure which shows the network structure which has arrange | positioned the management terminal which manages the path | route state to which this invention is applied. It is a block diagram which shows the internal structure of the terminal by the 4th Example of this invention. It is a block diagram which shows the internal structure of the management terminal by the 4th Example of this invention. It is a flowchart which shows the flow of operation | movement of the management terminal by the 4th Example of this invention. It is a flowchart which shows the flow of operation | movement of the transmission terminal by the 4th Example of this invention. It is a block diagram which shows the internal structure of the terminal by the 5th Example of this invention. It is a flowchart which shows the flow of operation | movement of the transmission terminal by the 5th Example of this invention. It is a block diagram which shows the internal structure of the terminal by the 6th Example of this invention. It is a flowchart which shows the flow of operation | movement of the transmission terminal by the 6th Example of this invention. It is a block diagram which shows the internal structure of the terminal by the 7th Example of this invention. It is a flowchart which shows the flow of operation | movement of the transmission terminal by the 7th Example of this invention. It is a figure explaining the estimation method in the case of estimating the physical band of the bottleneck link between the transmission / reception terminals by the target transmission rate estimation part. It is a network structural example which consists of a some terminal, Comprising: It is a figure for demonstrating a bottleneck link. It is a figure which shows the example of control of the transmission rate by this invention.

Explanation of symbols

S1 to Sn: Transmission terminals L100, M100, N100, W100, X100, Y100, Z100: Data transmission / reception control unit M10, N10, W10, Y10, Z10: Path state estimation unit X10: Information notification acquisition unit M13, N13, K14: Route state information storage unit W13, K13: Route state information acquisition / notification unit L103, M103, N103, W103, X103, Y103, Z103: RTT threshold value determination storage unit L109, M108, N108, W108, X109, Y108, Z108: RTT Determination unit L108, M107, N107, W107, X108, Y107, Z107: RTT measurement unit L101, X101: target transmission rate estimation unit L102, M101, N101, W101, X102, Y101, Z101: target transmission rate determination storage unit L104, M 102, N102, W102, X104, Y102, Z102: Target transmission rate selection unit L105, M104, N104, W104, X105, Y104, Z104: Transmission rate control unit L107, M106, N106, W106, X107, Y106, Z106: Packet Receiving units L106, M105, N105, W105, X106, Y105, Z105: Packet transmitting unit M11: Test packet transmitting / receiving units M12, N12, W12, Y12, Z12: Path state measuring units N11, W11, Y11, Z11: Measuring packet transmission / reception Part X11, Y14, Z14: Route state / terminal information notification acquisition unit X12, Y13, Z13: Route state / terminal information storage unit K11: Route state estimation request unit K12: Communication state management unit

Claims (38)

A communication system for transmitting and receiving data between a plurality of terminals via a network,
The transmitting terminal determines the presence or absence of other traffic in the link with the receiving terminal, and the data transmission rate is divided into two types , upper limit and lower limit , depending on whether the other traffic is present or not. The target communication rate is set to a target communication rate.   The communication system according to claim 1, wherein the upper limit of the target transmission rate is a physical band upper limit value of a bottleneck link between the transmitting and receiving terminals. Window size in data communication and R obtained for the window size
A transmission rate obtained by dividing the window size at the boundary where the minimum R T T is changed from the state where the minimum R T T is kept constant by the minimum R T T from a plurality of pieces of information including T T as a set, The communication system according to claim 1, wherein the upper limit of the target transmission rate is set.   The communication system according to any one of claims 1 to 3, wherein the lower limit of the target transmission rate is determined based on characteristics of a link and data with a terminal on the receiving side. R T T being observed and the minimum R T
5. The communication system according to claim 4, wherein the presence / absence of other traffic in the link with the terminal on the receiving side is determined from the magnitude relationship of T 1. R T T below the minimum R T T
, The transmission rate is controlled to be the upper limit target transmission rate, and when R T T exceeding the minimum R T T is observed, the transmission rate is set to the lower limit target transmission rate. 6. The communication system according to claim 4, wherein the communication system is controlled to be a rate. R observed during data transmission for the transmission rate and the transmission rate
The communication system according to any one of claims 4 to 6, wherein the upper limit target transmission rate and the minimum R T T are determined based on T T. By transmitting a test packet to the receiving terminal, the upper limit target transmission rate and the minimum R
T T is acquired, The communication system of any one of Claims 4-7 characterized by the above-mentioned. Measurement by transmission of test packet to the receiving terminal and transmission rate and R observed for the transmission rate during data transmission
The communication system according to any one of claims 4 to 8, wherein the upper limit target transmission rate and the minimum R T T are determined based on T T. The terminal on the transmitting side has the target transmission rate at the upper limit, the minimum R
The communication system according to any one of claims 4 to 9, wherein T T and a reception buffer size are notified. A management terminal for managing a path state between the transmission / reception terminal and the transmission / reception terminal is provided.
The terminal is requested to measure the path state information including T T to acquire the path state information, and the transmission-side terminal sets the transmission rate to the upper limit target transmission based on the path state information from the management terminal. 5. The data communication is performed by controlling to a rate or a lower limit target transmission rate.
The communication system according to any one of 0. The terminal on the transmission side requests the route state information from the management terminal after establishing a connection, and based on the route state information obtained from the management terminal, the target transmission rate and the minimum RT
The communication system according to claim 11, wherein T is determined and transmission rate is controlled. The management terminal periodically updates route state information between the specific terminals and notifies the specific terminal, and the specific terminal on the transmission side transmits the target transmission based on the route state information. Rate and minimum R
The communication system according to claim 11, wherein T T is determined and transmission rate is controlled. The upper limit target transmission rate determined based on route state information from the management terminal is set to a maximum transmission rate when there is no other traffic in the communication route to the receiving terminal. Claim 1
The communication system according to 1. A transmission rate setting method of a communication system for transmitting and receiving data between a plurality of terminals via a network,
A step in which the transmitting terminal determines whether or not there is other traffic on the link with the receiving terminal;
A step of setting a data transmission rate to two types of target transmission rates of an upper limit and a lower limit depending on whether the other traffic is present or not   16. The transmission rate setting method according to claim 15, wherein the upper limit of the target transmission rate is a physical band upper limit value of a bottleneck link between the transmitting and receiving terminals. Window size in data communication and R obtained for the window size
A transmission rate obtained by dividing the window size at the boundary where the minimum R T T is changed from the state where the minimum R T T is kept constant by the minimum R T T from a plurality of pieces of information including T T as a set, 16. The upper limit of the target transmission rate is defined as claim 15.
The transmission rate setting method described in 1. The transmission rate setting method according to any one of claims 15 to 17, wherein the lower limit of the target transmission rate is determined based on characteristics of a link between the receiving terminal and data. A communication terminal that transmits and receives data via a network,
The communication terminal on the transmission side determines the presence or absence of other traffic on the link with the terminal on the reception side, and the data transmission rate is set to an upper limit and a lower limit of 2 depending on whether or not there is the other traffic. A communication terminal comprising means for setting a target transmission rate of a kind . The upper limit of the target transmission rate is a physical band upper limit value of a bottleneck link between the transmitting and receiving terminals.
The communication terminal according to 9. Window size in data communication and R obtained for the window size
A transmission rate obtained by dividing the window size at the boundary where the minimum R T T is changed from the state where the minimum R T T is kept constant by the minimum R T T from a plurality of pieces of information including T T as a set, The upper limit of the target transmission rate is set as an upper limit.
The communication terminal according to 9. The lower limit of the target transmission rate is determined based on characteristics of a link and data with a terminal on the receiving side.
The communication terminal according to any one of claims 9 to 14. R T T being observed and the minimum R T
3. The communication terminal according to claim 2, wherein the presence / absence of other traffic on the link with the receiving-side terminal is determined from the magnitude relationship of T 1. R T T below the minimum R T T
When the transmission rate is controlled to be the upper limit target transmission rate, and when R T T exceeding the minimum R T T is observed,
3. The transmission rate is controlled to be the lower limit target transmission rate.
The communication terminal according to claim 2 or claim 2. R observed during data transmission for the transmission rate and the transmission rate
The communication terminal according to any one of claims 2 to 24, wherein the upper limit target transmission rate and the minimum R T T are determined based on T T. By transmitting a test packet to the receiving terminal, the upper limit target transmission rate and the minimum R
The communication terminal according to any one of claims 2 to 24, further comprising means for acquiring T T. Measurement by transmitting a test packet to the receiving terminal and transmission rate and R observed for the transmission rate during data transmission
The communication terminal according to any one of claims 2 to 26, wherein the upper limit target transmission rate and the minimum R T T are determined based on T T. The transmitting terminal transmits the upper limit target transmission rate, the minimum RT to the receiving terminal in the previous period.
The communication terminal according to any one of claims 2 to 2, wherein T and a reception buffer size are notified. A communication program that operates on a communication terminal that transmits and receives data via a network and controls a transmission rate.
On the communication terminal on the transmission side, the presence / absence of other traffic in the link with the terminal on the reception side is determined, and the data transmission rate is set to an upper limit and a lower limit depending on whether or not the other traffic exists. A communication program that executes a function of setting two types of target transmission rates. 3. The function of setting the upper limit of the target transmission rate to a physical band upper limit value of a bottleneck link between the transmitting and receiving terminals.
9. The communication program according to 9. Window size in data communication and R obtained for the window size
A transmission rate obtained by dividing the window size at the boundary where the minimum R T T is changed from the state where the minimum R T T is kept constant by the minimum R T T from a plurality of pieces of information including T T as a set, 3. A function of setting an upper limit of the target transmission rate.
9. The communication program according to 9. 3. The function of determining a lower limit of the target transmission rate based on characteristics of a link and data with a terminal on the receiving side.
The communication program according to any one of claims 9 to 31. R T T being observed and the minimum R T
The communication program according to claim 32, having a function of determining the presence or absence of other traffic on a link with a receiving terminal from the magnitude relationship of T 1. R T T below the minimum R T T
, The transmission rate is controlled to be the upper limit target transmission rate, and when R T T exceeding the minimum R T T is observed, the transmission rate is set to the lower limit target transmission rate. 4. A function of controlling to be a rate.
The communication program according to claim 2 or claim 3. R observed during data transmission for the transmission rate and the transmission rate
The communication program according to any one of claims 3 to 34, which has a function of determining the upper limit target transmission rate and the minimum R T T based on T T. By transmitting a test packet to the receiving terminal, the upper limit target transmission rate and the minimum R
The communication program according to any one of claims 3 to 35, which has a function of acquiring T T. Measurement by transmission of test packet to the receiving terminal and transmission rate and R observed for the transmission rate during data transmission
The communication program according to any one of claims 3 to 36, which has a function of determining the upper limit target transmission rate and the minimum R T T based on T T. The transmitting terminal transmits the upper limit target transmission rate, the minimum RT to the receiving terminal in the previous period.
The communication program according to any one of claims 3 to 3, which has a function of notifying T and a reception buffer size.

Images