JP2006279730A - Congestion control method, transmitting apparatus, and receiving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accomplish congestion control that does not employ a reciprocative delay time or one-way delay time of packets. <P>SOLUTION: Not an absolute time such as a delay time but a relative time (jitter, interval) of arrival packets is observed to infer a network congestion state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a congestion control method for controlling the communication speed of packet communication using IP (Internet Protocol) or the like.

  In the Internet, IP, which is a best effort protocol, is used. For the purpose of ensuring communication reliability, TCP (Transmission Control Protocol) is generally used as an upper protocol of IP. TCP has a retransmission control function for performing data arrival compensation and a communication speed control function for adjusting the speed.

  TCP communication speed control is realized by a mechanism that dynamically changes the window size, that is, the transmission buffer size. There are two purposes used. The first is to match the buffer size on the receiving side. This is flow control, which realizes a communication speed according to the capability of the receiving side. The second is used for congestion control to obtain a communication speed suitable for the congestion state of the network.

  Various methods have been proposed and implemented as a congestion control mechanism. There is a method called TCP Reno as a general congestion control method. In TCP Reno flow control, control is performed such that the window size is gradually increased, that is, the communication speed is increased, and if a data loss occurs during transfer, the window size is halved.

There is also a method called TCP Vegas. This is the RTT (Round between the sender and receiver)
The window size is controlled based on Trip Time (round trip delay time). When the network is congested, a phenomenon is observed in which the amount of data accumulated in the queues of routers in the network increases and the delay time increases, and the window size is controlled based on this observation result. This is intended to realize communication that does not cause data loss, and can be said to be control that improves throughput by reducing the number of times of performing retransmission control.

  An RTT measurement method will be described with reference to FIG. First, the transmission side device 1 sends out a packet 3 in which the time of the clock 2 built in the transmission side device 1 is marked toward the reception side. The packet passes through the network, reaches the receiving side as packet 5, and is sent out as a return packet 6 toward the transmitting side. On the transmission side, the arrival time of the returned packet 7 is compared with the time stamped on the packet 7 to calculate the RTT.

  TCP Vegas has many advantages over TCP Reno, such as less jitter and less delay (for example, see Non-Patent Document 1 for TCP Vegas).

L. Brakmo, L.M. Peterson, “TCP Vegas: End to End Congestion Aviation on a Global Internet, IEEE Journal on Selected Area in Communication”, Vol. 8, pg. 1465-1480, October 1995

  TCP Vegas uses a round trip delay time such as RTT, but does not accurately represent the congestion status in the network. This is because the delay time changes depending on the congestion state of the return path.

  In addition, in order to accurately represent the congestion situation in the network, it is desirable to perform control using a one-way delay time from the transmission side to the reception side, but in order to match the clocks of the transmission side and the reception side, It is necessary to prepare a highly accurate clock such as cesium or rubidium.

  In view of such circumstances, an object of the present invention is to realize congestion control that does not use a round-trip delay time or a one-way delay time of a packet.

  First, the basic concept of the present invention will be described. The congestion state of the network can be estimated by measuring a delay time such as RTT. This is because, when the network is congested, packets are accumulated in a buffer (queue) in a transmission device such as a router in the network, so that the delay time is increased.

  Although the delay time here is an absolute time, for example, when the network congestion is beginning, the time interval between transmission packets is gradually increasing. This can be observed as jitter, for example.

  In the present invention, congestion control is performed by utilizing the fact that the congestion state of the network can be estimated by observing the relative time of arrival packets, not the absolute time such as delay time.

  That is, a first aspect of the present invention is a congestion control method that is applied to a transmission apparatus in unicast packet communication in which transmission and reception are one-to-one, and controls a communication speed according to a congestion state in the network.

  Here, a feature of the present invention is that the transmitting device is a statistic including an average value or a variance value regarding a time interval variation of the plurality of packets transmitted from a receiving side of the plurality of packets transmitted from the own device. A step of receiving information and a step of reducing a communication speed when the average value or the variance value is larger than a reference threshold value are executed.

  Alternatively, the present invention is a congestion control method in which transmission and reception are applied to a transmission apparatus in a one-to-n multicast packet communication and the communication speed is controlled according to the congestion state in the network.

  Here, a feature of the present invention is that the transmitting device is an average value or a dispersion value related to a time interval variation of the plurality of packets transmitted from a plurality of receiving sides of the plurality of packets multicast-transmitted from the own device. And a step of reducing the communication speed when the largest average value or variance value among the average values or variance values received from a plurality of receiving sides is larger than a reference threshold value. There is a place to execute.

  In addition, the present invention is applied to a receiving apparatus in unicast packet communication in which transmission and reception are one-to-one or multicast packet communication in which transmission and reception are one-to-n, and the communication speed is set according to the congestion state in the network. This is a congestion control method to be controlled.

  Here, a feature of the present invention is that the receiving device receives a plurality of packets transmitted from a transmitting side, and includes a statistic including an average value or a variance value regarding a time interval variation of the received plurality of packets. The step of calculating the information and the step of transmitting the calculated statistical information to the transmitting side are performed.

  The plurality of packets are, for example, measurement packets for measuring a packet sequence that is a target for controlling the communication speed or time information used for controlling the communication speed.

  The statistical information including the average value or the variance value regarding the time interval variation of the packet is obtained, for example, as a result of measuring the jitter or interval time of a plurality of packets transmitted from the transmission device to the reception device. Statistical information.

  Further, when TCP is used for the unicast packet communication, for example, the communication speed is varied by changing the window size.

  For example, the communication speed is controlled such that the communication speed from the transmission device is always increased, and the communication speed is decreased when the average value or the variance value is larger than a reference threshold value.

  According to this, the congestion control can be realized simply by controlling the communication speed of lowering the communication speed of the transmitting device when the average value or the variance value is larger than the threshold value, so that the control procedure can be simplified. Can do.

  Alternatively, the communication speed can be decreased when the average value or the variance value is larger than a reference threshold value, and the communication speed can be increased when the average value or the variance value is smaller.

  According to this, since the maximum communication speed can be maintained within a range in which congestion does not occur while performing congestion avoidance, network utilization efficiency can be kept high.

  A second aspect of the present invention is a transmission apparatus that performs one-to-one unicast packet communication between transmission and reception, and a feature of the present invention is that a receiving side of a plurality of packets transmitted from the own apparatus Means for receiving statistical information including an average value or variance value relating to time interval fluctuations of the plurality of packets transmitted from the network, and means for reducing communication speed when the average value or variance value is greater than a reference threshold value It is in the place with.

  Alternatively, the present invention is a transmitting apparatus that performs one-to-n multicast packet communication between transmission and reception, and a feature of the present invention is that a plurality of reception sides of a plurality of packets that are multicast transmitted from the own apparatus Means for receiving statistical information including an average value or variance value relating to time interval fluctuations of the plurality of packets transmitted, and the largest average value or variance among the average values or variance values received from a plurality of receiving sides And means for reducing the communication speed when the value is larger than a reference threshold value.

  A third aspect of the present invention is a receiving apparatus that performs one-to-one unicast packet communication for transmission and reception or one-to-n multicast packet communication for transmission and reception. The means for receiving a plurality of packets transmitted from the transmitting side and calculating the statistical information including the average value or the variance value regarding the time interval variation of the received plurality of packets, and transmitting the calculated statistical information And means for transmitting to the side.

  Further, the plurality of packets are, for example, measurement packets for measuring a packet sequence that is a target for controlling the communication speed or time information used for controlling the communication speed.

  By using the method and apparatus according to the present invention, it is possible to realize congestion control that does not use a round-trip delay time or a one-way delay time of a packet, and it is possible to accurately represent a congestion state in a network. In addition, the necessity of preparing a high-accuracy clock such as cesium or rubidium is eliminated.

(First Example)
The configurations of the transmitting apparatus and the receiving apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 3, 4, and 5. FIG. FIG. 3 is a block diagram of the transmission apparatus of the first embodiment. FIG. 4 is a block diagram of the receiving apparatus of the first embodiment. FIG. 5 is a flowchart showing the procedure of the congestion control method of the first embodiment.

  As shown in FIG. 3, the first embodiment is applied to the transmission device 8 in unicast packet communication in which transmission and reception are one-to-one, and a congestion control method for controlling the communication speed according to the congestion state in the network. It is.

  Here, the feature of the first embodiment is that the transmitting device 8 shown in FIG. 3 is transmitted from the receiving side of a plurality of packets transmitted from its own device (S1) as shown in FIG. Receiving statistical information including a jitter value as an average value or variance value regarding a time interval variation of a plurality of packets (S5), and reducing a communication speed when the jitter value is larger than a reference threshold (S6) , S7).

  In step S <b> 5, the communication speed calculation unit 21 receives a jitter value as statistical information from the receiving device 9. Further, the communication speed calculation unit 21 compares the received jitter value with the threshold value in step S6, and calculates the communication speed based on the comparison result. In step S7, the output control unit 22 decreases the communication speed according to the calculation result.

  Further, as shown in FIG. 4, the first embodiment is applied to a receiving device 9 in unicast packet communication in which transmission and reception are one-to-one or multicast packet communication in which transmission and reception are one-to-n. It is a congestion control method for controlling the communication speed according to the congestion state.

  Here, the feature of the first embodiment is that the receiving device 9 shown in FIG. 4 receives (S2) and receives a plurality of packets transmitted from the transmitting side as shown in FIG. A step (S3) of calculating statistical information including a jitter value as an average value or a variance value regarding a time interval variation of a plurality of packets, and a step of transmitting the calculated statistical information to the transmission side (S4) are executed. is there.

  In step S <b> 2, the jitter calculation unit 30 receives a packet from the transmission device 8. Further, the jitter calculation unit 30 performs jitter calculation as step S3. The packet generation unit 25 mounts the jitter value calculated by the jitter calculation unit 30 in the packet in step S4 and transmits the packet to the transmission device 8 via the output buffer 26 and the output unit 27.

  The plurality of packets are measurement packets for measuring a packet sequence that is a target for controlling the communication speed or time information used for controlling the communication speed.

  Further, the statistical information including the average value or the variance value regarding the time interval variation of the packet calculated by the jitter calculating unit 30 of the receiving device 9 is the jitter or the plurality of packets transmitted from the transmitting device 8 to the receiving device 9. This is statistical information obtained as a result of measuring the interval time with the receiving device 9. In this embodiment, the jitter value is used.

  In addition, when TCP is used for the unicast packet communication, the output control unit 22 of the transmission device 8 varies the communication speed by changing the window size of the output buffer 17.

  Alternatively, the output control unit 22 performs control so as to constantly increase the communication speed from the transmission device 8, and lowers the communication speed when the jitter value is larger than a reference threshold value, or uses the jitter value as a reference value. When it is larger than the threshold, the communication speed is decreased, and when it is smaller, the communication speed is increased.

  The present embodiment can be implemented as a program that, when installed in a general-purpose information processing apparatus, causes the information processing apparatus to realize functions corresponding to the transmission apparatus 8 or the reception apparatus 9 of the present embodiment. This program is recorded in a recording medium and installed in the information processing apparatus, or installed in the information processing apparatus via a communication line, so that the information processing apparatus has each function of the transmission apparatus 8 or the reception apparatus 9. The corresponding function can be realized.

  In the following, the first embodiment will be described in more detail.

  A first embodiment of the present invention in unicast packet communication with one-to-one transmission and reception will be described with reference to FIGS. 2, 3, 4, and 5. FIG. FIG. 2 is an image diagram of unicast packet communication.

  First, as shown in step S1, data is transmitted from the data processing unit 15 to the packet generation unit 16 from the transmission device 8 and packetized. Thereafter, the data is sent to the output buffer 17 and output from the output unit 18.

  Next, the output packet sequence 10 passes through the network and arrives at the reception device 9 as a packet sequence 11 as shown in step S2. Here, the packet intervals t1,..., Tn of the packet sequence 10 are known in advance, for example, the packet intervals are equal intervals, or time stamps are recorded in the packets. The packet sequence passes through the input unit 28 and is input to the input buffer 29. The data is sent to the data processing unit 24.

  Next, as shown in step S <b> 3, the jitter calculator 30 calculates the jitter from the time information of the packet sequence 11.

  Next, the jitter is sent to the packet generator 25 to generate a packet for the transmission apparatus. Then, it passes through the output buffer 26, passes through the output unit 27, and the packet 13 storing the jitter information is transmitted to the transmitter 8 as shown in step S4.

  Next, as shown in step S <b> 5, the packet 12 arrives at the input unit 19. Thereafter, the data passes through the input buffer 20, and the communication speed calculation unit 21 calculates the communication speed based on the jitter value as shown in step S6. By transmitting the information to the output control unit 22 and controlling the output buffer 17, the communication speed is controlled as shown in step S7.

  Here, the jitter may be a dispersion value related to the time interval of the packet sequence or an average value of the packet intervals. Alternatively, a difference value obtained by comparing the time from the first packet to the target packet with the time when the packet was transmitted may be used. In this embodiment, all the packets are used as jitter calculation targets. However, all the packets need not be used, for example, every ten jitter calculation targets.

  In addition to data that is subject to communication speed control, measurement measurement packets may be transmitted at regular intervals, and jitter may be calculated from the measurement packets. When calculating the jitter, if the transmission interval of the measurement packet is known in advance, the jitter may be calculated from that value, or the time transmitted from the transmission side is imprinted on the measurement packet, and the measurement is performed at the reception side. It is also possible to compare the time stamped on the packet with its own clock and calculate the jitter value from the difference value of the comparison result.

(Second embodiment)
The configurations of the transmitting apparatus and the receiving apparatus according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a block diagram of the transmission apparatus of the second embodiment. FIG. 8 is a block diagram of a receiving apparatus according to the second embodiment. FIG. 9 is a flowchart showing the procedure of the congestion control method of the second embodiment.

  As shown in FIG. 7, the second embodiment is a congestion control method that is applied to a transmission apparatus 31 in multicast packet communication in which transmission and reception are one-to-n and controls the communication speed according to the congestion state in the network. is there.

  Here, the feature of the second embodiment is that the transmission device 31 shown in FIG. 7 is transmitted from a plurality of reception sides of a plurality of packets multicast-transmitted (S8) from its own device, as shown in FIG. A step (S12) of receiving statistical information including an average value or a jitter value as a variance value regarding the time interval fluctuations of the plurality of packets, and the largest jitter value among the jitter values received from the plurality of receiving sides; The step (S13, S14, S15) of decreasing the communication speed when the threshold value is larger than the reference threshold is executed.

  In step S12, the jitter value holding unit 50 receives and holds a jitter value as statistical information from the receiving device 9. The jitter value selection unit 51 selects the largest jitter value from among the jitter values held in the jitter value holding unit 50 in step S13. The communication speed calculation unit 52 compares the jitter value selected as step S14 with the threshold value, and calculates the communication speed based on the comparison result. The output control part 53 reduces communication speed according to the calculation result as step S15.

  Further, as shown in FIG. 9, the receiving devices 32 to 34 of the second embodiment shown in FIG. 8 receive a plurality of packets transmitted from the transmitting side (S9), and the times of the received plurality of packets. A step (S10) of calculating statistical information including an average value or a variance value regarding the interval variation and a step (S11) of transmitting the calculated statistical information to the transmission side are performed.

  In step S <b> 9, the jitter calculation unit 59 receives a packet from the transmission device 31. Further, the jitter calculation unit 59 performs jitter calculation as step S10. The packet generation unit 60 mounts the jitter value calculated by the jitter calculation unit 59 in the packet in step S11 and transmits the packet to the transmission device 31 via the output buffer 61 and the output unit 62.

  The plurality of packets are measurement packets for measuring a packet sequence that is a target for controlling the communication speed or time information used for controlling the communication speed.

  Further, the statistical information including the average value or the variance value regarding the time interval variation of the packet calculated by the jitter calculation unit 59 of the reception devices 32 to 34 includes a plurality of pieces of statistical information transmitted from the transmission device 31 to the reception devices 32 to 34. This is statistical information obtained as a result of measuring the jitter or interval time of the packet with the receiving devices 32 to 34. In this embodiment, the jitter value is used.

  Further, the output control unit 53 of the transmission device 31 performs control so as to constantly increase the communication speed from the transmission device 31, and lowers the communication speed when the average value or the variance value is larger than a reference threshold value. Alternatively, the communication speed is decreased when the average value or the variance value is larger than a reference threshold value, and the communication speed is increased when it is smaller.

  The present embodiment can be implemented as a program that, when installed in a general-purpose information processing apparatus, causes the information processing apparatus to realize functions corresponding to the transmission apparatus 31 or the reception apparatuses 32-34 of the present embodiment. This program is recorded on a recording medium and installed in the information processing apparatus, or installed in the information processing apparatus via a communication line, so that each function of the transmission apparatus 31 or the reception apparatuses 32 to 34 is added to the information processing apparatus. The functions corresponding to each can be realized.

  In the following, the second embodiment will be described in more detail.

  A second embodiment of the present invention in multicast packet communication in which transmission and reception are 1 to n will be described with reference to FIGS. 6, 7, 8, and 9. FIG. 6 is an image diagram of multicast packet communication.

  First, as shown in step S8, data is transmitted from the data processing unit 44 to the packet generation unit 54 from the transmission device 31 and packetized. Thereafter, the data is sent to the output buffer 46 and output from the output unit 47.

  Next, the output packet sequence 35 passes through the network and arrives at the n receiving devices 32 to 34 as the packet sequence 36 as shown in step S9. Here, the packet intervals t1,..., Tn of the packet sequence 35 are assumed to be known in advance, for example, the packet intervals are equal intervals, or time stamps are recorded in the packets. The packet sequence passes through the input unit 57 and is input to the input buffer 58. Data is sent to the data processing unit 56.

  Next, as shown in step S <b> 10, the jitter calculation unit 59 calculates jitter from the time information in the packet sequence 36.

  Next, jitter is sent to the packet generator 60 to generate a packet for the transmitter 31. Then, after passing through the output buffer 61, passing through the output unit 62, the packets 37 to 39 storing the jitter information are transmitted to the transmission device 31 as shown in step S <b> 11.

  Next, as shown in step S <b> 12, packets 40 to 42 arrive at the input unit 48. Thereafter, it passes through the input buffer 49 and is stored in the jitter value holding unit 50. Then, as shown in step S13, the jitter value selection unit 52 selects a jitter value to be used for calculating the communication speed.

  Here, in the selection of the jitter value, a value having the largest jitter value may be used when network congestion starts. Alternatively, a jitter value exceeding a certain range may be excluded and the largest jitter value remaining may be used.

  Next, as shown in step S14, the communication speed calculation unit 52 calculates the communication speed based on the jitter value. By transmitting the information to the output control unit 53 and controlling the output buffer 46, the communication speed is controlled as shown in step S15.

  Here, the jitter may be a dispersion value related to the time interval of the packet sequence or an average value of the packet intervals. Alternatively, a difference value obtained by comparing the time from the first packet to the target packet with the time when the packet was transmitted may be used. In this embodiment, all packets are used as jitter calculation targets. However, it is not necessary to use all packets such as every ten jitter calculation targets. In addition to data that is subject to communication speed control, measurement measurement packets may be transmitted at regular intervals, and jitter may be calculated from the measurement packets. When calculating the jitter, if the transmission interval of the measurement packet is known in advance, the jitter may be calculated from that value, or the time transmitted from the transmission side is imprinted on the measurement packet, and the measurement is performed at the reception side. Jitter may be calculated from the difference value of the comparison result by comparing the time stamped on the packet with its own clock.

  By using the method and apparatus according to the present invention, it is possible to realize congestion control that does not use a round-trip delay time or a one-way delay time of a packet, and it is possible to accurately represent a congestion state in a network. In addition, the necessity of preparing a high-accuracy clock such as cesium or rubidium is eliminated. Thereby, the convenience and service quality in network management can be improved.

The figure explaining the measuring method of RTT. The image figure of the unicast communication of a 1st Example. The block block diagram of the transmitter of a 1st Example. The block block diagram of the receiver of a 1st Example. The flowchart which shows the procedure of the congestion control method of a 1st Example. The image figure of the multicast communication of 2nd Example. The block block diagram of the transmitter of a 2nd Example. The block block diagram of the receiver of a 2nd Example. The flowchart which shows the procedure of the congestion control method of 2nd Example.

Explanation of symbols

1, 8, 31 Transmitter 2 Clock 3, 5, 6, 7, 12, 13, 37-42 Packet 4, 9, 32-34 Receiver 10, 11, 35, 36 Packet sequence 15, 24, 44, 56 Data processing unit 16, 25, 54, 60 Packet generation unit 17, 26, 46, 61 Output buffer 18, 27, 47, 62 Output unit 19, 28, 48, 57 Input unit 20, 29, 49, 58 Input buffer 21 52 Communication speed calculation unit 22, 53 Output control unit 30, 59 Jitter calculation unit 50 Jitter value holding unit 51 Jitter value selection unit S1 to S15 Steps

Claims (13)

In a congestion control method in which transmission and reception are applied to a transmission apparatus in one-to-one unicast packet communication, and the communication speed is controlled according to the congestion state in the network,
The transmitter is
Receiving statistical information including an average value or a variance value regarding a time interval variation of the plurality of packets transmitted from the reception side of the plurality of packets transmitted from the device;
And a step of reducing the communication speed when the average value or the variance value is larger than a reference threshold value. In a congestion control method in which transmission and reception are applied to a transmission device in 1-to-n multicast packet communication, and the communication speed is controlled according to the congestion state in the network,
The transmitter is
Receiving statistical information including an average value or a variance value regarding a time interval variation of the plurality of packets transmitted from a plurality of reception sides of the plurality of packets multicast-transmitted from the own device;
A congestion control method comprising: a step of reducing a communication speed when the largest average value or variance value among the average values or variance values received from a plurality of receiving sides is larger than a reference threshold value. . In a congestion control method in which transmission and reception are applied to a receiving apparatus in one-to-one unicast packet communication or transmission and reception are in one-to-n multicast packet communication, and the communication speed is controlled according to the congestion state in the network. ,
The receiving device is:
Receiving a plurality of packets transmitted from the transmission side and calculating statistical information including an average value or a variance value regarding a time interval variation of the received plurality of packets;
And a step of transmitting the calculated statistical information to the transmission side.   4. The congestion control method according to claim 1, wherein the plurality of packets are measurement packets for measuring a packet sequence that is a target for controlling a communication speed or time information used for controlling the communication speed. 5.   The statistical information including the average value or the variance value regarding the time interval variation of the packet is a statistic obtained as a result of measuring the jitter or interval time of a plurality of packets transmitted from the transmission device to the reception device by the reception device. The congestion control method according to claim 1, wherein the congestion control method is information.   5. The congestion control method according to claim 1, wherein when TCP is used for the unicast packet communication, the communication speed is varied by changing a window size.   The congestion control according to any one of claims 1 to 4, wherein control is performed so as to constantly increase a communication speed from the transmission device, and the communication speed is decreased when the average value or the variance value is larger than a reference threshold value. Method.   5. The congestion control method according to claim 1, wherein when the average value or the variance value is larger than a reference threshold, the communication speed is decreased, and when the average value or the variance value is smaller, the communication speed is increased. In a transmission apparatus that performs one-to-one unicast packet communication between transmission and reception,
Means for receiving statistical information including an average value or a variance value regarding a time interval variation of the plurality of packets transmitted from the reception side of the plurality of packets transmitted from the own device;
And a means for reducing the communication speed when the average value or the variance value is larger than a reference threshold value. In a transmission apparatus in which transmission and reception perform multicast packet communication of 1 to n,
Means for receiving statistical information including an average value or a variance value regarding a time interval variation of the plurality of packets transmitted from a plurality of receiving sides of the plurality of packets multicast-transmitted from the own device;
A transmission apparatus comprising: means for decreasing a communication speed when the largest average value or variance value among the average values or variance values received from a plurality of receiving sides is larger than a reference threshold value. In a receiving apparatus in which transmission and reception perform one-to-one unicast packet communication or transmission and reception perform one-to-n multicast packet communication,
Means for receiving a plurality of packets transmitted from the transmission side and calculating statistical information including an average value or a variance value regarding a time interval variation of the received plurality of packets;
Means for transmitting the calculated statistical information to the transmitting side.   11. The transmission device according to claim 9, wherein the plurality of packets are measurement packets for measuring a packet sequence to be controlled for communication speed or time information used for controlling the communication speed.   The receiving device according to claim 11, wherein the plurality of packets are measurement packets for measuring time series used for controlling a communication rate or a packet sequence to be controlled.

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