KR20040058032A - File transfer management system and method, and storage media having program thereof - Google Patents

Abstract

PURPOSE: A file transmission management system is provided to automatically assign a buffer size in accordance with a bandwidth of a network while transmitting a file between a transmission server and a user terminal, and to periodically monitor a network state, thereby improving file transmission performance and guaranteeing QoS. CONSTITUTION: A user terminal(100) comprises as follows. A buffer setup portion(110) transmits test packets to a destination, measures the round-trip times of the test packets and time intervals to calculate a buffer size value, and sets the buffer size value to a buffer size for file transmitting, then returns the calculated buffer size value to the destination. A monitoring portion(120) transmits the test packets to the destination while transmitting or receiving a file to or from the destination, measures an average round-trip time of the returned test packets, and checks whether the measured time exceeds a preset reference value. If so, a managing portion(130) requests an outer device to assign QoS.

Description

FILE TRANSFER MANAGEMENT SYSTEM AND METHOD, AND STORAGE MEDIA HAVING PROGRAM THEREOF

The present invention relates to a file transfer management system and method capable of periodically monitoring the network status and guaranteeing end-to-end quality of service, and a recording medium storing the program.

Today's Internet offers only a single service called Best Effort. However, as the Internet is commercialized, the demand for service quality is rapidly increasing.

Some argue that fiber optics and Wavelength Division Multiplexing (WDM) technology will ensure sufficient bandwidth to automatically provide a Quality of Service (QoS).

Another argues that a mechanism for providing QoS is needed because new applications will be developed that will deplete no matter how much bandwidth the network provides.

However, in the current situation, there is a problem in that it is difficult to guarantee a reliable bandwidth to the user due to the limitation of network resources, and it is difficult to transmit a large amount of data at high speed with low loss.

In particular, in the case of a large amount of data such as data that requires the use of a supercomputer and data requiring high performance arithmetic processing, there is a problem in that it cannot sufficiently satisfy the demand of network resources.

The present invention has been made to solve the above problems, the present invention relates to a file transfer management system and method that can guarantee the end-to-end quality of service dynamically by periodically monitoring the network status and to a recording medium storing the program will be.

Another object of the present invention is to provide a file transfer management system and method capable of automatically allocating a buffer size according to a bandwidth of a network during a file transfer between a transmission server and a user terminal, and a recording medium storing the program.

1 is a block diagram showing an embodiment of a file transfer management system according to the present invention.

2 shows a method for network measurement.

3 is a view illustrating that the time interval is increased by delaying an interval between test packets in a bottleneck link.

4 is a diagram illustrating a TCP header structure.

5 is a flowchart illustrating an embodiment of a file transfer management method according to the present invention;

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

10, 20: network connection device 30: file server

100: user terminal 110: buffer setting unit

120: monitoring unit 130: management unit

200: service quality automation server

In order to achieve the above object, an embodiment of the present invention transmits a test packet to a destination on a network, measures a returned test packet, sets a buffer size for file transfer, and sets a network state while transmitting a file to the destination. The present invention provides a file transfer management system including a user terminal that monitors and requests service quality allocation from an external device when a predetermined reference value is exceeded.

In addition, in the present invention, the user terminal transmits a test packet to the destination and calculates a buffer size value by measuring a round trip time and a time interval of the returned test packet and then buffers the calculated buffer size value for a file transfer. A buffer setting unit which sets a size and returns the calculated buffer size value to the destination; A monitoring unit which transmits a test packet to the destination while transmitting a file to the destination or receiving a file from the destination, and measures an average round trip time of the test packet returned from the destination to monitor whether a preset reference value is exceeded; And a management unit for requesting service quality allocation to the external device when the average round trip time measured by the monitoring unit exceeds the reference value.

In the present invention, the buffer setting unit calculates a buffer size by dividing the size of the test packet by the average of the measured time interval, and then multiplying the averaged round trip time by the calculated bandwidth to calculate a buffer size value. The above problem is solved as a transmission management system.

Also, in the present invention, the buffer setting unit calculates an average and a standard deviation including the calculated buffer size value to a buffer size value previously returned to the destination, and the calculated buffer size value is out of the standard deviation. The above-described problem is solved by a file transfer management system, wherein the calculated average is set as a buffer size for file transfer.

Further, in the present invention, the buffer setting unit stores the buffer size value returned to the destination, and solves the above-mentioned problems as a file transfer management system.

Also, in the present invention, the buffer setting unit and the monitoring unit transmits two or more test packets to the destination in succession, and uses a packet pair model for measuring a returned test packet. The above problem is solved.

In addition, in the present invention, the test packet solves the above-mentioned problems as a file transfer management system, which uses ICMP (Internet Control Message Protocol).

In addition, in the present invention, when the average round trip time measured by the monitoring unit is less than the reference value again, the management unit requests the release of the quality of service already assigned to the external device as described above as a file transfer management system Solve the problem.

In addition, in the present invention, the external device is a file quality management system, characterized in that the service quality automation server for assigning or releasing a predetermined quality of service to the network connection device in response to a request from the user terminal. Solve.

In order to achieve the above object, another embodiment of the present invention includes the steps of: (a) transmitting a test packet to a destination on the network and measuring the returned test packet to set a buffer size for file transfer; (b) monitoring network status while sending a file to or receiving a file from the destination; And (c) requesting an external device to assign service quality when the monitored network state exceeds a predetermined reference value.

Further, in the present invention, step (a) comprises the steps of (a1) measuring the round trip time and the time interval of the test packet returned by sending a test packet to the destination; (a2) calculating a buffer size value using the measured round trip time and time interval of the test packet and setting a buffer size for file transfer to the calculated buffer size value; And (a3) returning the calculated buffer size value to the destination.

In the present invention, the step (a2) is to calculate the bandwidth by dividing the size of the test packet by the average of the measured time interval, and then calculate the buffer size value by multiplying the calculated bandwidth by the average round trip time The above problem is solved as a file transfer management method.

Further, in the present invention, step (a2) calculates an average and a standard deviation including the calculated buffer size value to a buffer size value previously returned to the destination, and wherein the calculated buffer size value is the standard deviation. The above problem is solved as a file transfer management method, which sets the calculated average as a buffer size for file transfer.

In addition, in the present invention, the step (a3) solves the above-described problem as a file transfer management method, characterized in that for storing the buffer size value returned to the destination.

Further, in the present invention, step (b) transmits a test packet to the destination while transmitting a file to or receiving a file from the destination, and measuring an average round trip time of the test packet returned from the destination. The above-mentioned problem is solved as a file transfer management method characterized by monitoring whether a preset reference value is exceeded.

Further, in the present invention, the step (a) and the step (b) is characterized by using a packet pair model for transmitting two or more test packets in succession to the destination and measuring the returned test packets The problem mentioned above is solved as a transmission management method.

In addition, in the present invention, the test packet solves the above-mentioned problems as a file transfer management method, characterized in that it uses the Internet Control Message Protocol (ICMP).

Further, in the present invention, the step (c) is a file transfer management, characterized in that the request for the release of the quality of service already assigned to the external device, when the network state monitored in the step (b) is again below the reference value The problem mentioned above is solved as a method.

Another embodiment of the present invention to achieve the above object is (a) transmitting a test packet to a destination on the network and measuring the returned test packet to set the buffer size for file transfer; (b) monitoring network status while sending a file to or receiving a file from the destination; And (c) a recording medium recording a file transfer management program comprising a process of requesting an external device to assign a quality of service when the monitored network state exceeds a predetermined reference value.

In addition, in the present invention, the process (a) comprises: (a1) a process of measuring a round trip time and a time interval of a test packet returned by sending a test packet to the destination; (a2) calculating a buffer size value using the measured round trip time and time interval of the test packet and setting a buffer size for file transfer to the calculated buffer size value; And (a3) a process of returning the calculated buffer size value to the destination.

In addition, in the present invention, the process (a2) calculates a bandwidth by dividing the size of the test packet by an average of the measured time intervals, and then multiplies the averaged round trip time by the calculated bandwidth to calculate a buffer size value. The above problem is solved by the recording medium.

Further, in the present invention, the process (a2) calculates an average and a standard deviation including the calculated buffer size value to a buffer size value previously returned to the destination, and the calculated buffer size value is the standard deviation. The above problem is solved as a recording medium, wherein the calculated average is set as a buffer size for file transfer.

In addition, in the present invention, the process (a3) solves the above-described problem as a recording medium, characterized in that for storing the buffer size value returned to the destination.

Also, in the present invention, the process (b) transmits a test packet to the destination while transmitting a file to or receiving a file from the destination, and measures an average round trip time of the test packet returned from the destination. The above-mentioned problem is solved by a recording medium characterized by monitoring whether a preset reference value is exceeded.

In the present invention, the (a) process and the (b) process use a packet pair model for transmitting two or more test packets to the destination in succession and measuring the returned test packets. The above problem is solved as a medium.

In addition, in the present invention, the test packet solves the above-described problems as a recording medium, characterized in that it uses the Internet Control Message Protocol (ICMP).

In the present invention, the process (c) is a recording medium, characterized in that for requesting the release of the quality of service already assigned to the external device, when the network state monitored in the process (b) again becomes less than the reference value. The above problem is solved.

The objects, features and advantages of the present invention will be more readily understood by reference to the accompanying drawings and the following detailed description.

The present invention proposes a file transfer management system which is implemented to automatically allocate a buffer size according to a bandwidth of a network and periodically monitor network conditions to dynamically guarantee end-to-end quality of service.

Preferred embodiments of the invention include embodiments such as computer systems and computer program products programmed to carry out the methods of the invention. According to an embodiment of a computer system, a set of instructions for carrying out a method resides in one or more memories, which may be stored as a computer program product on a recording medium such as a CD-ROM or the like.

1 is a block diagram showing an embodiment of a file transfer management system according to the present invention. Referring to FIG. 1, the file transfer management system includes a user terminal 100, and the user terminal 100 is connected to the file server 30 through a network. The network is provided with network connection devices 10 and 20 for connecting the network.

In the present embodiment, the network is a network to which a differential services model is applied, and the network connection devices 10 and 20 are routers.

The user terminal 100 transmits a test packet to a destination on a network, measures a test packet returned from the destination, and sets a buffer size for file transmission. In the following description, a case where the destination is the file server 30 will be described as an example.

Next, the user terminal 100 transmits a file to or receives a file from the file server 30, and in the present embodiment, a file using a file transfer protocol (FTP). It is desirable to transmit or receive the message.

FTP is the most widely used protocol for file transfer over TCP / IP networks and has the advantage of using a reliable method.

When the user terminal 100 transmits a file to the file server 30 or receives a file from the file server 30, the user terminal 100 monitors the network state and requests an external device to assign a quality of service when the predetermined reference value is exceeded. In the following description, the external device will be described taking the case of the service quality automation server 40 as an example.

The service quality automation server 40 which has received a request for service quality assignment from the user terminal 100 allocates a predetermined service quality to the corresponding network connection device 10 or 20. In this way, if the quality of service is dynamically allocated according to the network state, the data loss rate can be minimized and a reliable network state can be provided.

A detailed description of the user terminal 100 is as follows.

As shown in FIG. 1, the user terminal 100 includes a buffer setting unit 110, a monitoring unit 120, and a management unit 130.

The buffer setting unit 110 transmits a test packet to the file server 30 and measures a round trip time and a time interval of the returned test packet. For example, the buffer setting unit 110 uses 31 test packets of the same size, and the test packet preferably uses ICMP.

2 is a diagram illustrating a method for network measurement.

There are two methods of measuring network traffic: passive and active. The passive method is to select a point on the path (router, switch, link, etc.) to collect and analyze the traffic passing through and to characterize the network traffic passing through the selection point.

On the other hand, the active method is to artificially inject test packets into the network to check the state of the network (packet delay, loss rate, etc.).

In general, two methods should be appropriately used to manage the network, but the present invention uses an active method to check the network status while the file is being transferred.

Figure 3 shows that the interval between test packets in the bottleneck link is delayed to increase the time interval.

Bandwidth prediction techniques are largely divided into two types. First, there is a technology that can find out the bandwidth for each link with a single packet model, and there is a packet pair model used in the present invention.

The packet pair model is a technique for measuring the bandwidth of a bottleneck link existing on a path by sending a test packet and measuring a time interval between two packets coming back. The packet pair model assumes that two consecutive packets have the same path and that no other background traffic is interrupted between the two packets.

Finally, there is a packet tailgating model, which is a hybrid of the two models described earlier.

As shown in FIG. 3, when the time interval Pb is increased in the bottleneck link, even if the next link guarantees fast transmission, the time difference Pr is always maintained.

The buffer setting unit 110 calculates a buffer size value by measuring a round trip time and a time interval of the returned test packet, and sets the calculated buffer size value as a buffer size for file transfer.

The buffer setting unit 110 calculates the bandwidth by dividing the size of the test packet by the average of the measured time intervals, and calculates the buffer size value by multiplying the calculated bandwidth by the average round trip time.

For example, when 31 test packets are returned, 30 time intervals can be measured. The measured time intervals are sorted in descending order to extract 10 median values and 10 averages are calculated. After calculating the average of the time interval in this way, the bandwidth is calculated by dividing the size of the test packet by the average of the time intervals.

The buffer size is then calculated by multiplying the bandwidth by the average round trip time of the test packet. The average round trip time is obtained by arranging the measured round trip times in descending order, extracting 11 median values, and calculating the average.

The buffer setting unit 110 returns the calculated buffer size value to the file server 30 and stores the buffer size value returned to the file server 30.

4 shows a TCP header structure, in which the "Window" field indicates how much more space remains in the receiving buffer. FTP is also one of the TCP / IP application protocols, so you can use the "Window" field.

Since the default buffer size of the user terminal 100 and the file server 30 varies greatly depending on the system, determine the most appropriate optimal value in the path between the user terminal 100 and the file server 30 to determine both sides. This can improve file transfer performance.

If you adjust the window field properly, you can get more than double the performance. By default, up to 16 powers of 2 can be displayed, but up to 30 powers of 2 can be displayed with the option.

In this embodiment, the buffer setting unit 110 is preferably set to the buffer size for file transfer by the following process.

That is, the buffer setting unit 110 checks whether the buffer size value previously returned to the file server 30 is stored.

If there is a buffer size value previously returned, the average and standard deviation including the buffer size value calculated by the above process are calculated in the buffer size value previously returned to the file server 30. In this example, the mean and standard deviation over the past 20 times are calculated.

The buffer setting unit 110 determines whether the calculated buffer size value is within the standard deviation, and sets the average of the past 20 times as the buffer size for file transfer when the standard deviation is out of the standard deviation.

If the buffer size value calculated using the measured value does not deviate from the standard deviation or there is no buffer size value previously returned, the calculated buffer size value is used as it is.

Meanwhile, while the user terminal 100 transmits a file to the file server 30 or receives a file from the file server 30, the monitoring unit 120 transmits a test packet to the file server 30 and returns the test. Measure the average round trip time of a packet.

For example, 10 test packets of the same size are transmitted to the file server 30 at intervals of 2 seconds, and the round trip time of the test packets returned from the file server 30 is measured to calculate an average. In this case, it is preferable that the test packet uses ICMP as in the buffer setting unit 110.

The reason for measuring round trip time is that the buffer size value returned may not be appropriate if the network condition is not good at the time of file transfer.

The monitoring unit 120 monitors whether the measured round trip time average value exceeds the reference value. When the average value exceeds the reference value, the management unit 130 determines that the network condition is deteriorated and requests the service quality automation server 40 to allocate the service quality.

When the average value is again lower than or equal to the reference value in the monitoring unit 120, the management unit 130 requests the release of the service quality already assigned to the service quality automation server 40.

For example, the monitoring unit 120 calculates an average value using four intermediate values of the round trip time, and monitors whether the average value exceeds the reference value five times or more for 10 seconds or more. When the average value exceeds the reference value five times in a row for 10 seconds or more, the management unit 130 requests the service quality assignment to the service quality automation server 40.

If the average value is stabilized five or more times after the service quality assignment is applied, the management unit 130 requests the service quality automation server 40 to release the service quality that has already been assigned.

The quality of service automation server 40, which is requested to allocate the quality of service from the user terminal 100, enters the network connection device 10 and the exit side on the network path through user authentication and a service level assignment (SLA). The network connection device 20 assigns a predetermined quality of service.

In addition, when the request for the release of the quality of service is received from the user terminal 100, the quality of service allocated to the inlet side network connection device 10 and the outlet side network connection device 20 is released.

5 is a flowchart illustrating an embodiment of a file transfer management method according to the present invention.

Referring to FIG. 5, the present invention transmits a test packet to a destination on a network and sets a buffer size for file transfer by measuring a returned test packet (S) (S200 to S230), or transmitting a file to a destination. (B) step (S240) of monitoring a network state while receiving a file from a destination, and (c) step (S250) of requesting service quality allocation to an external device if the monitored network state exceeds a predetermined reference value. do.

In this embodiment, steps (a) and (b) use a packet pair model for continuously sending two or more test packets to the destination and measuring the returned test packet, and the test packet preferably uses ICMP. Do.

In step S250, when the network state monitored in step S240 again becomes lower than or equal to the reference value, the controller 250 requests the release of the quality of service already allocated to the external device.

Step (a) is a step of measuring the round trip time and time interval of the test packet returned by sending the test packet to the destination (S200), calculating the buffer size value using the measured round trip time and time interval of the test packet and file Setting the buffer size for transmission to the calculated buffer size value (S210 ˜ S220), and returning the calculated buffer size value to the destination (S230).

Step S210 calculates the bandwidth by dividing the size of the test packet by the average of the measured time intervals, and then calculates the buffer size value by multiplying the calculated bandwidth by the average round trip time.

Step S220 calculates the mean and standard deviation including the calculated buffer size value to the buffer size value previously returned to the destination, and if the calculated buffer size value is outside the standard deviation, calculate the average buffer size for file transfer. Set to.

Although not shown in the drawing, step S230 stores the buffer size value returned to the destination.

In step S240, the test packet is transmitted to the destination while the file is transmitted to or received from the destination, and the average round trip time of the test packet returned from the destination is measured to monitor whether the preset reference value is exceeded.

In the present invention configured as described above, the file transfer management system automatically allocates the buffer size according to the bandwidth of the network, periodically monitors the network state, and dynamically guarantees end-to-end quality of service with reference to FIGS. 1 and 5. If described in detail as follows.

First, when a user accesses the file server 30 using the user terminal 100 and logs in, the file server 30 checks whether the user is a registered user.

If the user is identified as a legitimate user, the buffer setting unit 110 of the user terminal 100 transmits 31 test packets using ICMP to the file server 30 to measure the round trip time and time interval of the test packets returned. (S200).

The buffer setting unit 110 calculates a buffer size value using the measured round trip time and time interval (S210), and the buffer size value returned to the file server 30 is stored in the buffer setting unit 110. Check if it is.

If there is a buffer size value previously returned to the buffer setting unit 110, the average and standard deviation for the past 20 times including the buffer size value calculated using the measured value are calculated.

Then, it is determined whether the buffer size value calculated using the measured value is included within the standard deviation, and when the standard deviation is out of the range, the average of the past 20 times is calculated as the buffer size value.

If the buffer size value calculated using the measured value does not deviate from the standard deviation, or the buffer size value previously returned to the buffer setting unit 110 is used, the calculated buffer size value is used as it is.

The buffer setting unit 110 sets the buffer size value calculated by the above process as the buffer size for file transfer (S220), and returns the calculated buffer size value to the file server 30 (S230). At this time, the buffer size value returned to the file server 30 is preferably stored in the buffer setting unit 110.

When the buffer sizes of the user terminal 100 and the file server 30 are automatically adjusted, the user terminal 100 transmits a large file to the file server 30 or starts receiving the file from the file server 30. .

In addition, while transmitting a file to the file server 30 or receiving a file from the file server 30, the monitoring unit 120 of the user terminal 100 files 10 test packets using ICMP at intervals of 2 seconds. The round trip time is measured by transmitting to the server 30 (S240). At this time, all test packets used are the same size.

The monitoring unit 120 calculates an average value using four intermediate values of the round trip time, and monitors whether the average value exceeds the reference value five times for 10 seconds or more. If the average value exceeds the reference value five times in a row for 10 seconds or more, the management unit 130 requests the service quality allocation to the service quality automation server 40 (S250).

The quality of service automation server 40, which is requested to allocate the quality of service from the user terminal 100, enters the network connection device 10 and the exit side on the network path through user authentication and a service level assignment (SLA). The network connection device 20 assigns a predetermined quality of service.

After the service quality assignment is applied, if the average value becomes lower than the reference value again, the management unit 130 requests the release of the service quality already allocated to the service quality automation server 40.

The quality of service automation server 40 that is requested to release the quality of service from the user terminal 100 releases the quality of service allocated to the inlet side network connection device 10 and the outlet side network connection device 20.

In this way, the network state is monitored during file transfer to ensure the quality of service of the network connection devices 10 and 20, and when the file transfer ends, the quality of service assigned to the network connection devices 10 and 20 is released.

Finally, the user logs out of the file server 30.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention as defined in the appended claims.

As described above, the present invention can improve the file transfer performance by automatically allocating a buffer size according to the bandwidth of the network during the file transfer between the file server and the user terminal.

In addition, by monitoring the network condition periodically while the large file is being transmitted, guaranteeing end-to-end quality of service, it is possible to minimize delay or loss of data.

It also provides the foundation for extending end-to-end quality of service technology that was confined to the backbone.

In addition, users can be assured of reliable bandwidth, low latency, low loss, and high transmission services. This suggests a new direction of distributed processing applications that have shown limitations due to the limitation of network resources, and has the advantage of bringing about the development of new multimedia applications.

Claims (27)

Test packet is sent to the destination on the network and the returned test packet is measured to set the buffer size for file transfer, and the network status is monitored during the file transfer to the destination, and the service quality is transmitted to the external device when the predetermined threshold value is exceeded File transfer management system comprising a user terminal requesting an assignment. The method of claim 1, wherein the user terminal The test packet is transmitted to the destination, the round trip time and the time interval of the returned test packet are measured, the buffer size is calculated, and the calculated buffer size value is set as the buffer size for the file transfer. A buffer setting unit that returns a value of the buffer size; A monitoring unit which transmits a test packet to the destination while transmitting a file to the destination or receiving a file from the destination, and measures an average round trip time of the test packet returned from the destination to monitor whether a preset reference value is exceeded; And And a management unit for requesting service quality allocation to the external device when the average round trip time measured by the monitoring unit exceeds the reference value. The method of claim 2, wherein the buffer setting unit After calculating the bandwidth by dividing the size of the test packet by the average of the measured time interval, the file size management system characterized in that to calculate the buffer size value by multiplying the average round trip time by the calculated bandwidth. The method of claim 2, wherein the buffer setting unit Compute the mean and standard deviation including the calculated buffer size value to the buffer size value previously returned to the destination, and if the calculated buffer size value is out of the standard deviation, calculate the calculated mean for file transfer. File transfer management system, characterized in that the buffer size setting. The method of claim 2, wherein the buffer setting unit And a buffer size value returned to the destination. The method according to any one of claims 2 to 5, wherein the buffer setting unit and the monitoring unit use a packet pair model for continuously sending two or more test packets to the destination and measuring the returned test packets. File transfer management system characterized in that. The method according to any one of claims 2 to 5, The test packet is a file transfer management system, characterized in that using the ICMP (Internet Control Message Protocol). The method of claim 2, wherein the management unit And when the average round trip time measured by the monitoring unit is lower than or equal to the reference value, requesting the release of the quality of service already allocated to the external device. The method of claim 1, wherein the external device And a service quality automation server for allocating or releasing a predetermined service quality to a network connection device according to a request from the user terminal. (a) transmitting a test packet to a destination on a network and measuring a returned test packet to set a buffer size for file transfer; (b) monitoring network status while sending a file to or receiving a file from the destination; And and (c) requesting an external device to assign a quality of service when the monitored network state exceeds a predetermined reference value. The method of claim 10, wherein step (a) (a1) measuring a round trip time and a time interval of a test packet returned by transmitting a test packet to the destination; (a2) calculating a buffer size value using the measured round trip time and time interval of the test packet and setting a buffer size for file transfer to the calculated buffer size value; And (a3) returning the calculated buffer size value to the destination. The method of claim 11, wherein step (a2) And calculating a bandwidth by dividing the size of the test packet by an average of measured time intervals, and then multiplying the calculated bandwidth by an average round trip time to calculate a buffer size value. The method of claim 11, wherein step (a2) Compute the mean and standard deviation including the calculated buffer size value to the buffer size value previously returned to the destination, and if the calculated buffer size value is out of the standard deviation, calculate the calculated mean for file transfer. File transfer management method characterized in that the buffer size setting. The method of claim 11, wherein step (a3) And a buffer size value returned to the destination. The method of claim 10, wherein step (b) The test packet is transmitted to the destination while the file is transmitted to or received from the destination, and the average round trip time of the test packet returned from the destination is measured to monitor whether the preset reference value is exceeded. File transfer management method. 16. A packet pair model according to any one of claims 11 to 15, wherein step (a) and step (b) transmit two or more test packets in succession to the destination and measure a returned test packet. File transfer management method comprising the use of. The method according to any one of claims 11 to 15, The test packet is a file transfer management method, characterized in that using the ICMP (Internet Control Message Protocol). The method of claim 10, wherein step (c) If the network status monitored in the step (b) is less than the reference value again, the file transfer management method characterized in that for requesting the release of the quality of service already assigned to the external device. (a) sending a test packet to a destination on the network and measuring the returned test packet to set a buffer size for file transfer; (b) monitoring network status while sending a file to or receiving a file from the destination; And (c) a recording medium recording a file transfer management program including a process of requesting an external device to assign a quality of service when the monitored network state exceeds a predetermined reference value. 20. The process of claim 19, wherein the process (a) (a1) a process of measuring a round trip time and a time interval of a test packet returned by sending a test packet to the destination; (a2) calculating a buffer size value using the measured round trip time and time interval of the test packet and setting a buffer size for file transfer to the calculated buffer size value; And (a3) a process for returning the calculated buffer size value to the destination. The process of claim 20 wherein the process (a2) And calculating a bandwidth by dividing the size of the test packet by an average of measured time intervals, and then calculating a buffer size value by multiplying the calculated bandwidth by an average round trip time. The process of claim 20 wherein the process (a2) Compute the mean and standard deviation including the calculated buffer size value to the buffer size value previously returned to the destination, and if the calculated buffer size value is out of the standard deviation, calculate the calculated mean for file transfer. A recording medium, characterized in that for setting the buffer size. The process of claim 20, wherein the process (a3) And a buffer size value returned to the destination. The process of claim 19, wherein the process (b) The test packet is transmitted to the destination while the file is transmitted to or received from the destination, and the average round trip time of the test packet returned from the destination is measured to monitor whether the preset reference value is exceeded. Recording medium. 25. A packet pair model according to any one of claims 20 to 24, wherein the (a) process and the (b) process send two or more test packets consecutively to the destination and measure a returned test packet. Recording medium, characterized in that using. The method according to any one of claims 20 to 24, The test packet is a recording medium, characterized in that using the ICMP (Internet Control Message Protocol). The process of claim 19, wherein the process (c) And (b) requesting the release of the quality of service already assigned to the external device when the network condition monitored by the process becomes lower than or equal to the reference value.