JP2917355B2 - Communication line switching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used for a communication line switching system, and particularly connected to a center-side modem and this center-side modem via a 4-wire dedicated line. With a remote modem
The present invention relates to a communication line switching system for switching a communication line between a center-side modem and a remote-side modem to a pair of public lines when a line fault occurs.

〔Overview〕

The present invention relates to a communication line switching system for switching a communication line between a center-side modem and a remote-side modem connected via a 4-wire dedicated line from a dedicated line to two sets of public lines when a line failure occurs. In, measure the amount of data transmission in the uplink and downlink,
In the event of a line failure, the line with the higher data transmission amount is assigned in advance by assigning the line with the higher data transmission amount between the upstream line and the downstream line to the line with the higher line quality among the two sets of public lines. Even if it is difficult to keep the communication, it is possible to always perform communication with less transmission error.

[Conventional technology]

Conventionally, a center-side modem and a remote-side modem connected to the center-side modem via a 4-wire dedicated line are provided, and communication between the center-side modem and the remote-side modem when a line failure occurs. In a communication line switching method for switching a line from a four-wire dedicated line to two public lines, a line that is considered to have a large data transmission amount among an up line and a down line is set in advance, and the line connected when a line failure occurs is set. Of the public lines of the book, the line with the better line quality is automatically assigned to the line set to have a large data transmission amount.

[Problems to be solved by the invention]

However, according to such a conventional communication line switching method, when it is difficult to determine in advance the line with the higher data transmission amount, the public line with the higher line quality is replaced with the line with the higher data transmission amount. There is a disadvantage that the process of reducing the rate of occurrence of transmission errors cannot be performed by the assignment.

It is an object of the present invention to provide a communication line switching system that can always perform communication with a small transmission error even when it is difficult to set a line with a large data transmission amount in advance by eliminating the above-mentioned drawbacks. To provide.

[Means for solving the problem]

The present invention provides a center-side modem, a remote-side modem connected to the center-side modem via a 4-wire dedicated line, and two sets of public units connected to the center-side and remote-side modems, respectively. A communication line switching system including switching means for switching a communication line from the dedicated line to the public line when a line failure occurs.
The center-side modem includes a data transmission amount counting unit that constantly measures the data transmission amount of the communication line by the dedicated line into an uplink line and a downlink line and outputs a result signal, and the connected public line And a quality measuring unit for measuring the line quality of the line and outputting a signal of the result, wherein the switching unit switches from the dedicated line to the public line based on the outputs of the data transmission amount counting unit and the quality measuring unit. It is characterized by including.

In the present invention, the data transmission amount counting unit and the quality measuring unit may be included in the remote modulation / demodulation device instead of the center modulation / demodulation device.

[Action]

In the present invention, the data transmission amounts of the uplink and the downlink are counted in advance, and when the line fails, the number of lines is reduced to four.
When switching from a line-type leased line to two sets of public lines, the line quality of the two connected public lines is measured, and the public line with the better line quality is automatically assigned to the line with the larger data transmission amount. .

Therefore, even when it is difficult to set a line with a large data transmission amount in advance, communication with a small transmission error can always be performed.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention.

In this embodiment, a center-side modem 10, a remote-side modem 20 connected to the center-side modem 10 via a 4-wire dedicated line 41, a public line 42 to the center-side modem 10 and 44, the public lines 43 and 45 to the remote modem 20, the public lines 42 and 43, and the public line 44.
And an exchange network 30 connecting the 45.

The center-side modulator / demodulator 10 is connected to the remote-side modem 20 via the public lines 42 and 44 via the network control units 14 and 15 and the dedicated line 41 and the network control units 14 and 15 via the public network. A modem unit 11 connected to the lines 42 and 44, and a quality measuring unit 17 for measuring the line quality of the public lines 42 and 44,
A data transmission amount counting unit 18 that counts the amount of data transmission on the uplink and the downlink based on a signal from the modulation / demodulation unit 11.
A line switching unit 12 for switching the line from the dedicated line 41 to the public lines 42 and 44, a switching signal transmitting unit 16 for transmitting a line switching signal to the remote modem 20, and a data transmission amount counting unit 18. Based on the signal and the signal from the quality measuring unit 17, the network control units 14 and 15, the line switching unit 12, and the switching signal transmitting unit 16
And a control unit 13 for controlling the above.

The remote-side modem 20 includes network control units 24 and 25 for receiving a call from the center-side modem 10, a line switching unit 22 for switching a line from a dedicated line 41 to public lines 43 and 45, and a center switch. A switching signal receiving unit 26 that receives a line switching signal from the side modulation / demodulation device 10, and a control unit 23 that controls the line switching unit 22 based on signals from the network control units 24 and 25 and the switching signal receiving unit 26, It has a modem 21 connected to public lines 43 and 45 via a dedicated line 41 and network controllers 24 and 25.

A feature of the present invention is that, in FIG. 1, the data transmission amount of the communication line by the dedicated line 41 is continuously measured in the center-side modem 10 separately for the up line and the down line, and the resulting signal is output. The transmission amount counting unit 18 and the quality measuring unit 17 that measures the line quality of the public lines 42 and 44 and outputs a signal of the result are provided.

Next, with respect to the operation of the first embodiment, it is assumed that a line failure occurs in the dedicated line 41 and the communication line is switched from the dedicated line 41 to the public lines 42 and 43 and 44 and 45 via the switching network 30. Will be explained. Note that the line switching unit 12 of the center-side modem 10 and the line switching unit 22 of the remote-side modem 20 are
It is assumed that the connection state has been switched to the dedicated line 41. It is also assumed that the amount of downlink data transmitted before the occurrence of the line failure is greater than the amount of uplink data transmission.

While the center-side modem 10 and the remote-side modem 20 are communicating, the center-side modem 10
The data transmission amount counting section 18 in the inside constantly counts the transmitted data amount, that is, the downlink data transmission amount, and the received data amount, that is, the uplink data transmission amount, based on the signal from the modem section 11.

Now, a line failure occurs in the dedicated line 41, and the line is switched to the dedicated line 41.
When switching to the public lines 42 and 43 and 44 and 45 via the switching network 30 from, the control unit 13 of the center-side modem 10 controls the network control unit 14 and the network control unit 15, and via the conversion network 30, Calls are made to the public lines 43 and 45 of the remote modem 20, and the network controllers 24 and 25 of the remote modem 20 are called, so that the public lines 42 and 43 and the public line 44
45 is connected. Thereafter, the quality measuring unit 17 of the center-side modem 10 measures the line quality of the public lines 42 and 43 and the lines 44 and 45.

When the line quality of the public lines 42 and 43 is better than the line quality of the public lines 44 and 45, the control unit 13 of the center-side modem 10 controls the switching signal transmitting unit 16 by the signal from the data transmission amount counting unit 18, A signal indicating that the public lines 42 and 43 are used as the downlink is transmitted to the remote modem 20, and the line switch 12 is controlled to control the uplink to the network controller 15 and the downlink to the network controller 14. Switch to the side.

In the remote modulator / demodulator 20, the switching signal receiver 26 detects a signal transmitted from the center modem 10 indicating that the public lines 42 and 43 are used as the downlink, and the controller 23 controls the line switching unit 22 to switch the up line to the network control unit 25 side and the down line to the network control unit 24 side.

When the line quality of the public lines 44 and 45 is better than the line quality of the public lines 42 and 43, the lines are similarly configured to use the public lines 44 and 45 as the down lines and the public lines 42 and 43 as the up lines. Switch.

When the data transmission amount counting section 18 of the center-side modem 10 records that the data transmission amount of the uplink is larger than the data transmission amount of the downlink until the time of occurrence of the failure, the same operation is performed. The public line with the better line quality is automatically switched to the upstream line.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 1 shows a second embodiment in which
Instead of the quality measuring unit 17 and the data transmission amount counting unit 18 provided in 10, a quality measuring unit 27 and a data transmission amount counting unit 28 are provided in the remote-side modem 20, and the switching signal transmitting unit 16 switches the switching signal transmitting unit 16. The switching signal receiving unit 26 is replaced by a switching signal transmitting unit 26a in the receiving unit 16a.
The same operation as in the figure is performed.

〔The invention's effect〕

As described above, the present invention automatically determines which one of the up-link and down-link has the larger data transmission amount from the communication amount performed in the past, and sets two lines from the 4-wire dedicated line in case of line failure. When switching to the public line with the higher data transmission amount, the public line with the better line quality of the two connected public lines is automatically assigned to the line with the larger data transmission amount. Even if it is difficult to set the line in advance, there is an effect that communication with few transmission errors can always be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 2 is a block diagram showing a second embodiment of the present invention. 10: Center-side modulator / demodulator, 11, 21 ... Modulator / demodulator, 12,
22 ... Line switching unit, 13, 23 ... Control unit, 14, 15, 24, 25
...... Network controller, 16, 26a Switching signal transmitter, 16a, 26
… Switching signal receiving unit, 17, 27 …… Quality measuring unit, 18, 28…
Data transmission amount counting unit, 20 remote modem unit, 30 switching network, 41 dedicated line, 42 to 45 public line.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04M 11/00-11/10 H04B 1/74 H04L 1/22 H04M 3/22-3/36

Claims (2)

(57) [Claims] 1. A center-side modem, a remote-side modem connected to the center-side modem via a 4-wire dedicated line, and two sets of modems connected to the center-side and remote-side modems, respectively. A public line, wherein the center-side and remote-side modems include switching means for switching a communication line from the dedicated line to the public line when a line failure occurs. A data transmission amount counting unit for constantly measuring the data transmission amount of the communication line by the dedicated line separately for the uplink line and the downlink line and outputting a signal of the result, and measuring the line quality of the connected public line and the result. A quality measuring unit that outputs a signal of the data transmission amount counting unit and the quality measuring unit based on an output of the quality measuring unit. A communication line switching system including means for switching from the dedicated line to the public line. 2. A center-side modem, a remote-side modem connected to the center-side modem via a 4-wire dedicated line, and two sets of modems connected to the center-side and remote-side modems, respectively. A public line, wherein the center-side and remote-side modems each include a switching unit that switches a communication line from the dedicated line to the public line when a line fault occurs. A data transmission amount counting unit for constantly measuring the data transmission amount of the communication line by the dedicated line separately for the uplink line and the downlink line and outputting a signal of the result, and measuring the line quality of the connected public line and the result. And a quality measuring unit that outputs a signal of the data transmission amount counting unit and the quality measuring unit. A means for switching from the dedicated line to the public line.