JPH04287452A - Communication data warrant system - Google Patents

Abstract

PURPOSE:To realize the communication data warrant system easily coping with mixture of a general MODEM and an MNP MODEM without missing of a data at data communication release in the MODEM connection communication using the MNP MODEM. CONSTITUTION:In the case of data communication between a host computer 12 and a terminal equipment 11 via a packet exchange network 16, an MNP MODEM 14, a telephone exchange network 15 and an MNP 13 in this order, when transmission of all data is finished, the host computer 12 generates a packet to interrupt a line. When an interrupt packet is generated, a communication data warrant control section 21 provided in the packet exchange 17 sets a preset communication data warrant time to a timer 22 and the line (access information path) is released after lapse of a communication warrant time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to communication data guarantee systems, and particularly to modems with error-free control over public telephone lines, such as MNP (Microcom Network
Protocol) This relates to a communication data guarantee system for terminals when communication is released when a modem is connected.

0002

2. Description of the Related Art Conventional modem connection communications lack error-free control and data compression control. Therefore, errors (missing characters, garbled characters, etc.) that occur in the public telephone network between modems are sent directly to the terminal or host computer, creating a problem. For this reason, in modem connection communications such as Pason communications, errors occur during start-stop synchronization.
In addition to the demand for free communication, there is also a demand for faster communication.

[0003] Based on such a request, the modem itself is equipped with an error correction function, error correction processing is performed between the modems, and communication can be performed in a synchronous manner between the modems.
NP modem was developed.

According to the modem connection communication using this MNP modem (see FIGS. 4(a) and 4(b)), the terminal 4-MN
Error-free communication is possible without synchronization between P modem 1 and between host 5 and MNP modem 2.
Since synchronous data communication can be performed between the P modems and the MNP modem has a compression function, these functions can improve the execution throughput. Furthermore, Figure 4 (a
) is an example of data communication between the terminal 4 and the host 5 via the public telephone network 3, and FIG. 4(b) is an example of data communication via the public telephone network 3 and the packet switching network 6.

FIG. 5 is an explanatory diagram showing data exchange in modem communication using an MNP modem. Sending side M
The NP adds an error detection code FCS (Frame Check Sequence) required by the CRC method to each frame, and also attaches a number indicating the transmission order, and sends it to the destination MNP modem in a synchronous manner, and the receiving side When the MNP receives frame data, it performs error detection, and if there is no error, it attaches the sent number and returns a link confirmation frame to the sending MNP (
(See Figure 5(a)).

[0006] However, since sending a link confirmation frame for each data frame is inefficient, in reality, the transmitting MNP sends data frames one after another even if no link confirmation is received. - MNP sends MNP DF1 to DF5, and the receiving MNP also stops sending link confirmation data one by one. In other words, if the next data frame is sent within 135 milliseconds,
It does not send a link confirmation frame, but if it exceeds 135 milliseconds, it sends a link confirmation frame LF5 (see Figure 5(b)).
. If a transmission error is detected by the CRC error check, the receiving MNP checks the correct data received just before.
Send a data frame (eg DF2). As a result, the transmitting MNP recognizes that a transmission error has occurred in the data frame DF3, retransmits the data frame DF3, and thereafter transmits data frames in sequence.

[0007]

[Problem to be Solved by the Invention] In conventional modem connection communication that does not use an MNP modem, data does not remain in the modem, and therefore, when data communication is released, the access information path is immediately transmitted after the last data is transmitted. There is no problem in cutting it off.

However, in modem connection communication using an MNP modem, the MNP modem has a built-in buffer for error correction processing and the like, and data is retained in the buffer. When an error is detected, the data retention time becomes relatively long because it takes time to notify the error detection, receive retransmitted data, etc. Therefore, in modem connection communication using an MNP modem, if the access information path is immediately disconnected after the final data is sent, there is a problem that data will be lost if an error occurs in the MNP modem and data remains. arise.

From the foregoing, it is an object of the present invention to provide a communication data guarantee system in which data is not lost when data communication is released in modem connection communication using an MNP modem. Another object of the present invention is to easily handle the coexistence of conventional general modems and MNP modems, and to prevent communication data from being lost when data communication is released, regardless of which modem is being used for communication. The purpose is to provide a guarantee method.

Still another object of the present invention is that even if the communication speed of the modem is different and the data retention time in the modem is different,
An object of the present invention is to provide a communication data guarantee method that can prevent data loss.

[0011]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. 11 is a terminal, 12 is a host computer, 1
3 and 14 are MNP modems, 15 is a public telephone network, 16 is a packet switching network, 17 is a packet switch, 21 is a communication data guarantee control unit in the packet switch, and 22 is a timer.
It is.

0012

[Operation] When data communication is performed between the host computer 12 and the terminal 11 via the packet switching network 16 → MNP modem 14 → telephone switching network 15 → MNP modem 13, when all data transmission is completed, The host computer 12 generates a packet for disconnecting the line. When such a disconnected packet occurs, the packet switch 17
A communication data guarantee control section 21 provided in the communication data guarantee controller 21 sets a preset communication data guarantee time in a timer 22, and releases the line (access information path) after the communication guarantee time has elapsed.

[0013] Since the configuration is as above, the data is MN
If the communication data guarantee time is set to be equal to the maximum time that the data remains in the P modems 13 and 14, data will not be lost when the data communication is released. Additionally, if the line release timing is controlled depending on whether data is being communicated with the terminal via an MNP modem or a general modem other than MNP, it is possible to Even if MNP modems are used together, it can be easily handled. Furthermore, if the release timing is controlled according to the communication speed of the MNP modem, even if the data retention time in the MNP modem is different, the line can be disconnected after the corresponding minimum time without data loss.

[0014]

Embodiment Overall Configuration FIG. 2 is a block diagram of an embodiment of the communication data guarantee system of the present invention, and the same parts as in FIG. 1 are given the same reference numerals. In the figure, 11 and 11' are terminals, 12 is a host computer, 13 and 14 are MNP modems, 15 is a public telephone network, and 16
1 is a packet switching network, 17 is a packet switch, 18 is a console provided in the switch, and 19 and 20 are general modems.

[0015] The MNP modem 13 is connected to the terminal 11,
MNP modem 14 is connected to port 1 of packet switch 17. Further, the general modem 19 is connected to the terminal 11', and the general modem 20 is connected to the port 2 of the packet switch 17.
is connected to. In the packet switch 17, 21
2 is a communication data guarantee control unit that performs control to prevent data loss when data communication is released; 22 is a timer that measures the communication data guarantee time; and 23 is a storage unit that stores the type of modem and the communication data guarantee time. It is.

The storage unit 23 stores the type of modem connected to each port of the packet switch 17, whether it is a general modem or an MNP modem, and, in the case of an MNP modem, the guaranteed communication data time t. The communication data guarantee time t stored in association with each port is
It depends on the communication speed of the modem, and is set to be slightly larger than the maximum time that data stays in the MNP modem. still,
Setting of data in the storage section 23 is performed from the console 18.

Overall Operation FIG. 3 is a flowchart of the processing of the communication data guarantee control unit 21 when data communication is released. When the host computer 12 has finished transmitting all data to the terminal 11 or 11' via a predetermined port, it sends a packet to the packet switching network to disconnect the line (step 101).
... Occurrence of data communication release factor

When the communication data guarantee control unit 21 of the packet switch 17 receives a disconnection request packet from the host computer 12, it determines the type of modem connected to the port that was transmitting data to the terminal. is identified from the data stored in the storage unit 23 (step 102), and if it is a general modem, an instruction is immediately given to disconnect the line, and the line is disconnected (step 105). ...Access information pass release

[0019]
On the other hand, if the modem connected to the port that was transmitting data to the terminal is an MNP modem, the guaranteed communication data time corresponding to the MNP modem is read from the storage section 23 and set in the timer 22. , monitor the elapse of the time (steps 103, 104). When the communication data guarantee time has elapsed, a line disconnection instruction is given and the line is disconnected (step 105). ...Access information pass release

Although the case where data is transmitted from a computer via a packet-switched network has been described above, the present invention can also be applied to communications that do not use a packet-switched network. that's all,
Although the present invention has been described with reference to examples, the present invention can be modified in various ways according to the gist of the present invention as described in the claims, and the present invention does not exclude these modifications.

[0021]

As described above, according to the present invention, in communication using a modem connection type having error-free control, when data to be sent to a terminal remains in the modem during error-free control, the data Even if a communication release factor occurs, the access path is not released until all accumulated data is sent to the terminal, so no data will be lost when data communication is released.

Further, according to the present invention, the line release timing is controlled depending on whether data communication is being performed with the terminal via an MNP modem or a general modem other than the MNP modem. Since I configured it like this,
Even if conventional general modems and MNP modems coexist, it can be easily handled. That is, in general modem connection communication, the access path can be immediately released.

Furthermore, according to the present invention, since the communication data guaranteed time is controlled according to the communication speed of the MNP modem, etc., even if the data retention time in the MNP modem differs, the minimum time corresponding to each Afterwards, you can disconnect the line without losing data.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is a flowchart of communication data guarantee control of the present invention.

FIG. 4 is a configuration diagram of conventional modem connection communication.

FIG. 5 is an explanatory diagram of error-free communication of the MNP modem.

[Explanation of symbols]

11...terminal 12...Host computer 13,14...MNP modem 15...Public phone network 16...Packet switching network 17...Packet switch 21...Communication data guarantee control unit 22...Timer

Claims (3)

[Claims] [Claim 1] In a communication data guarantee method of a data communication system in a modem connection type having error-free control, a data communication release factor occurs when data communication is performed with a terminal via the modem. A communication data guarantee method characterized in that an access information path is released after a preset time has elapsed. 2. The communication data guarantee system according to claim 1, wherein the release timing is changed depending on the communication speed of the modem. 3. The release timing is determined depending on whether data communication is being performed with the terminal via a modem that has error-free control or a modem that does not have error-free control. 2. The communication data guarantee system according to claim 1, wherein the communication data guarantee system switches between the two.