JPH04111648A - Data transfer system - Google Patents

Abstract

PURPOSE:To keep a time required for retransmission to be a prescribed time or below by providing a check point insertion control is changed in response to a throughput of a network. CONSTITUTION:A transmission counter 3a of a check point insertion control device 3 counts a transmission quantity of a data transfer device 4 to calculate a throughput per unit time. An insertion timing calculator 3b receives the throughput to calculate an insertion interval according to a prescribed function to calculate the insertion interval so that the insertion number of a check point is at a constant rate per time.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a data transfer system, and particularly to a check used to retransmit data when a failure occurs in data transfer between computers connected via a network. This invention relates to a data transfer system with an improved point insertion method.

[Conventional technology]

If a failure occurs during data transfer, in order to be able to transmit data from the point where data transfer was interrupted, checkpoints, which are delimiter information, are generally inserted into the data to be transferred, and the data up to each checkpoint is It is confirmed that the data has been transferred without errors at each checkpoint as described above, and if a failure occurs, the data is retransmitted starting from the last confirmed checkpoint.

Regarding this, for example, IS 08571-
4p27. The description of Section Four is helpful.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, as shown in Fig. The data transfer unit, which is composed of the checkpoint insertion type 2a that inserts checkpoints and the data transfer device 4, inserts the above-mentioned checkpoints every fixed amount based on the size of the transferred data, so the network When a change occurs in the throughput, the following problems occur.

(1) When the throughput of the network used for data transfer increases, the number of checkpoint transmissions per unit time increases, reducing the efficiency of data transfer.

(2) If the throughput of the network used for data transfer becomes low, the time it takes to transfer data again when a failure occurs increases.

The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in the conventional technology, and to reduce the time required for retransmission for a certain period of time when retransmission is interrupted due to a failure. To provide a data transfer system which inserts checkpoints into transferred data without transmitting unnecessary checkpoints.

[Means for Solving the Problems] The above object of the present invention is to insert a plurality of checkpoints into data transferred between computers connected via a network, so that when a failure occurs during data transfer, normal operation is performed. A data transfer method having a function of retransmitting data starting from a checkpoint at which transfer is completed, characterized by providing a checkpoint insertion control mechanism that changes checkpoint insertion intervals according to network throughput. achieved by the system.

[Effect]

In the data transfer system according to the present invention, a checkpoint insertion control mechanism is provided that changes the checkpoint insertion interval according to the network throughput, and, for example, checkpoints are inserted at a fixed rate per time according to the network throughput. As you would send with
This determines the insertion position of the checkpoint. Thereby, the above-mentioned problems can be solved.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a system configuration diagram showing an embodiment of the present invention. In the figure, 1 is the aforementioned data reader, 2 is a checkpoint inserter that inserts a checkpoint into transmission data according to the timing generated by a checkpoint insertion control mechanism 3, which will be described later, and 4 is the aforementioned data transfer device. ing. Checkpoint insertion control mechanism 3 above
a transmission amount counter 3a that receives a data transmission amount signal from the data transfer device 4; an insertion timing calculation type 3b that receives system transmission throughput information from the count value of the transmission amount counter 3a and calculates a checkpoint insertion timing; It consists of an insertion timing generator 3C that generates an insertion timing signal based on the output of the insertion timing calculator 3b.

The operation of the system of this embodiment configured as described above will be explained below.

The data reader 1 reads data from the data file and passes this data to the checkpoint inserter 2. The checkpoint inserter 2 inserts checkpoints ( C, P) is inserted, and the data with the checkpoint (C, P) inserted is passed to the data transfer device 4. The data transfer device 4 transmits the data with the checkpoint (c, p) inserted to the data receiving side 5 via the network.

Here, in the checkpoint insertion control mechanism 3, the transmission amount by the data transfer device 4 is counted by the transmission counter 3a, and the throughput per unit time is calculated. The insertion timing calculator 3b receives this as input and calculates the insertion interval according to a function f (x) for calculating the insertion interval so that the number of insertions of checkpoints (C, P) becomes a constant rate per time.

FIG. 2 schematically shows the state of checkpoints (C, P) inserted between data. Here, the insertion interval of checkpoints (C:, P) is, for example, 10 to 20
The rate may be about once per second.

For example, the following method can be used as the function f (x) for timing calculation described above.

(1) A method to keep the time spent on retransmission within a certain amount of time % formula % () X Transfer rate per second (bit/5ec) This method uses the value of Calculate and if this is within a certain range,
Checkpoint (C, P) insertion interval f according to the above formula
(x).

(2) In addition to the method in (1) above, a method that takes into account cases where the line speed is slow. In order to prevent the line speed from becoming extremely short, when the line speed is below a certain level, the checkpoint (c, p) is inserted at a predetermined interval of b bytes, and when the line speed exceeds this, is a method that performs the same calculation as in (1) above. The value above is, for example,
It is set to 4096 (bit/5ec).

(3) A method that has two retransmission times for fast and slow line speeds, that is, depending on the value of This essentially changes the calculation formula.

In the checkpoint inserter 2, the insertion timing calculator 3b calculates f(x) using one of the above methods.
Based on the timing, checkpoints (C, P) are inserted between the data as shown in Figure 2, and
The data with the checkpoint (C, P) inserted is passed to the data transfer device 4. The data transfer device 4 transmits the data with the checkpoint (c, p) inserted to the data receiving side 5 via the network.

According to the above embodiment, with a simple configuration, when retransmission is interrupted due to a failure, the time required for retransmission is kept below a certain period of time, and the transferred data is checked without sending unnecessary checkpoints. This has the effect of realizing a data transfer system that inserts points.

It should be noted that the above-mentioned example shows an example of the present invention, and it goes without saying that the present invention should not be limited thereto.

〔Effect of the invention〕

As described in detail above, according to the present invention, multiple checkpoints are inserted into data transferred between computers connected via a network, and even if a failure occurs during data transfer, the data is transferred normally. In a data transfer method that has the function of retransmitting data starting from the checkpoint that has been completed, we have provided a checkpoint insertion control mechanism that changes the checkpoint insertion interval according to the network throughput. The present invention has the remarkable effect of realizing a data transfer system in which the time required for retransmission is kept below a certain period of time, and checkpoints are inserted into transferred data without sending unnecessary checkpoints. It is something to play.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram showing one embodiment of the present invention;
The figure is a diagram showing the checkpoint insertion situation in the example.
The figure is a system configuration diagram showing a conventional technique. 1, data reader, 2: checkpoint inserter,
3: Checkpoint insertion control mechanism, 3a: Transmission amount counter, 3b: Insertion timing calculator, 3c: Insertion timing generator, 4: Data transfer device, 5. Data receiving device. Figure f (x) f (xi

Claims (1)

[Claims] (1) Inserting multiple checkpoints in data transferred between computers connected via a network,
Checkpoint insertion that changes the checkpoint insertion interval according to network throughput in a data transfer method that has the function of retransmitting data from the checkpoint after the successfully transferred data when a failure occurs during data transfer. A data transfer system characterized by having a control mechanism.