JPH02122755A - Communication line switching system - Google Patents

Abstract

PURPOSE:To efficiently use a public line by monitoring the fault of a private line by either MODEMs set oppositely, and automatically switching the private line to the public line when the fault occurs. CONSTITUTION:At the MODEM 1, a control part 24 sends data from a subchannel modulation part 12 to the MODEM 2 via the private line 7, and takes out only a subchannel from the private line 8 at a filter part 13, and monitors the data from a demodulation part 14. At the MODEM 2, a control part 39 takes out only the subchannel from reception data on the line 7 at a filter part 28, and monitors the data from a demodulation part 29, and sends first data from a modulation part 27 when receiving the first data via the line 8. The MODEM 1, when receiving second data, judges that the fault occurs in the line 7, and sends the telephone number of the public line 5, and the MO DEM 2 detects it, and the control part 39 switches a line from a line 7 side to a line 5 side. Also, the MODEM 1 switches the line from the line 7 side to a public line 3 side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication line switching system, and more particularly to a communication line switching system when switching a communication line between modems from a private line to a public line.

[Conventional technology]

Conventionally, this type of communication line switching system has been used in a configuration where two opposing modems communicate via a leased line, and if a failure occurs in the leased line, the switch is switched from the leased line to the public line. In order to switch the communication line, a maintenance person operates a communication line switching device that is connected in advance between the modem and the leased line. Also, when switching from a leased line to a public line, it is often unclear whether there is a problem with the sending or receiving line of the leased line.
The sending/receiving lines were switched to public lines as a pair.

[Problem to be solved by the invention]

In the conventional communication line switching method described above, if the leased line cannot be switched to a public line due to a failure, after the maintenance person learns that a failure has occurred in the leased line, he or she can switch to the location where the communication line switching equipment is installed. The disadvantage is that it takes a long time from the occurrence of a failure to the completion of line switching because the communication lines must be manually switched.

In addition, it is not known whether there is a problem in the transmitting line or the receiving line of the dedicated line, and instead of switching only one line, both lines are switched, which doubles the charge for using the public line. It has the disadvantage of being loose.

[Means to solve the problem]

In the communication line switching system of the present invention, a first modem is connected to a second modem via a dedicated line, and each of the first and second modems has a different frequency band from a data channel. a sub-channel modulation section that extracts only sub-channel data from received data, and a sub-channel demodulation section that demodulates the sub-channel data,
The first modem transmits the first data from the transmission line to the second modem through the subchannel, and transmits the first data to the second modem.
When the modulation/demodulation device receives the first data in the sub-channel demodulation unit, the first data is transmitted to the second data, and when the first data cannot be received, the second data is transmitted to the second data.
a transmission means for the modem to transmit data from the transmission line on the sub-channel; and when the first modem receives the second data in the sub-channel demodulation unit, the transmission line is switched from the private line to the public line. , switching means for switching the reception line from the private line to the public line when no data is received, and then switching the transmission line from the private line to the public line when the second data is received. are doing.

〔Example〕

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

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

In FIG. 1, in this embodiment, the modem 1 is connected to the leased line 7.
, 8, and the modem 1 includes a data channel modulator 1o, a data channel demodulator 11, a subchannel modulator 12 whose frequency band is different from the data channel, and a receiver. A filter unit 13 that extracts only sub-channel data from the data, a sub-channel demodulator 14 that demodulates the sub-channel data, and a selection signal transmitter 15 that makes a call to the modem W2 of the public lines 3 and 4. , a switch section (hereinafter referred to as SW) 22 for switching whether to send the selection signal from the selection signal sending section 15 to either the public line 3 or 4; It has a line connection section 16.17, a 5w 23.40 for switching from the private line 7.8 to the connection of the public line 3.4, and a control section 24 for controlling each of the above sections and each SW. includes a data channel modulator 25, a data channel demodulator 26, and a subchannel modulator 27 whose frequency band is different from that of the data channel.
A filter unit 28 that extracts only sub-channel data from received data, a sub-channel demodulation unit 29 that demodulates the sub-channel data, a calling signal detection unit 3o that detects calling signals from public lines 5 and 6, and a public line 5.6 to the inside of the modem device 2;
5W for switching from leased lines 7 and 8 to public lines 5 and 6
37.38 and the above parts.

The control unit 39 includes a control unit 39 that controls each switch.

The modem 1 is equipped with transformers (hereinafter referred to as T) 18, 19, 2 in order to connect to the public line 3.4 and the private line 7.8.
0.21, and similarly the modem 2 is connected to public lines 5, 6.
and T3B, 34, 35 for connecting to dedicated lines 7, 8
．． It has 36.

Next, in the above-described configuration, if a failure occurs in the dedicated lines 7 and 8 connected to the modem 1, the public lines 3, 4,
5.6, the operation of switching to the connection with the modulation/demodulation device 2 will be explained.

The control section 24 of the modem 1 connects the 5W40 to the leased line 7 side, connects the 5W23 to the leased line 8 side, and connects the line connection section 16 to the leased line 8 side.
．． 17 is not connected to T18 and T19.

The three control units of the modem 2 connect the 5W37 to the leased line 7 side, connect the 5W38 to the leased line 8 side, and connect the line connection unit 31.
32 is connected to the calling signal detection section 30.

In the modulation/demodulation device 1, the control unit 24 continues to send the first data from the sub-channel modulation unit 12 to the modulation/demodulation device 2 via the dedicated line 7. Also, the filter section 13 extracts only the subchannel from the data received from the dedicated line 8, and determines whether the data demodulated from the subchannel demodulation section 14 is the first data, the second data, or whether any data is received. We are monitoring to see if this is the case.

In the modulation/demodulation device 2, the three control units extract only the subchannels from the data received from the leased line 7 using the filter unit 28,
It monitors whether the data demodulated from the two sub-channel demodulators is the first data or whether no data is received, and when the first data is received, the sub-channel modulator 2
The first data is sent from 7 via the dedicated line 8, and if no data is received, the second data is sent. Further, the ringing signal detection section 30 checks whether there is a telephone call on the public line 5.6.

By the method described above, when the modulation/demodulation device 1 receives the first data, it recognizes that the dedicated lines 7 and 8 are normal. If the second data is received, it is recognized that a fault has occurred in the dedicated line 7, and the preset modem 2
In order to send out the telephone number of the public line 5 connected as the reception line side of , the 5W 22 is connected to the T18 side, and the selection signal sending section 15 sends out a dial signal. In the modem 2, when the calling signal detection section 30 detects the calling signal, the control section 39 switches the 5W 37 from the leased line 7 side to the public line side. In the modem 1 as well, the control unit 24 switches the 5W 40 from the dedicated line 7 side to the public line 3 side.

By the switching operation described above, the connection of the dedicated line 7 between the modem devices 1 and 2 can be switched to the connection of the public lines 3 and 5.

The modem 2 is the first modem. If the second data is not received, it can be seen that a failure has occurred in the leased line 8.
Since it is possible that a fault has occurred in the dedicated line 7, first, the connection of the dedicated line 8 between the modulators 1 and 2 is switched to the connection of the public lines 4 and 6, and the secondary channel The demodulator 14 monitors the data received, and if the first data is received, it is recognized that the leased line 7 is normal, and if the second data is received, it is recognized that a failure has occurred in the leased line 7 as well. modem device 1.2 using the method described above.
The connection of the dedicated line 7 between them is switched to the connection of the public line 3.5.

As explained above, the modem 1 uses the public line 7.8 when a failure occurs in the dedicated line 7.8. It becomes possible to automatically switch the connection with the modulation/demodulation device 2 by 3.4° 5.6.

〔Effect of the invention〕

As explained above, the present invention provides a switching means that monitors failures in the transmission line and reception line of the private line in one of the opposing modems, and automatically switches the private line to the public line if a failure occurs. This eliminates the need for maintenance personnel to go to the location where the communication line switching device is installed and switch from the leased line to the public line when a failure occurs in the leased line, as was the case in the past. To use public lines efficiently and economically by making it possible to switch a faulty line from a dedicated line to a public line without the need for maintenance personnel to investigate whether the fault has occurred in the line or the receiving line. It has the effect of

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing one embodiment of the present invention. 1.2... Modulation/demodulation equipment, 3, 4, 5.6... Public line, 7.8... Private line, 9. ...Public network, 10.2
5... Data channel modulation section, 11.26... Data channel demodulation section, 12.27... Sub channel modulation section, 13.28... Filter section, 14.29... Sub channel demodulation section , 15... selection signal sending unit, 16.17
...31.32...Line connection section, 18.19,20
゜21...Trans (T), 22.23.37,38
゜40...Switch (SW), 24.39...Control unit.

Claims (1)

[Claims] A first modem is connected to a second modem via a dedicated line, and each of the first and second modems includes a sub-channel modulator having a frequency band different from that of the data channel, and a receiver. A filter section that extracts only sub-channel data from data, and a sub-channel demodulation section that demodulates the sub-channel data; If the second modulation/demodulation device receives the first data in the sub-channel demodulation section, the first data is transmitted to the device, and if the first data cannot be received, the second modulation/demodulation device receives the first data. sending means for the second modem to send data from a transmission line through a sub-channel; and when the first modem receives the second data in a sub-channel demodulation section, the transmission line is connected to the dedicated line; If no data is received, the receiving line is switched from the dedicated line to the public line, and when the second data is received, the transmitting line is switched from the dedicated line to the public line. 1. A communication line switching system comprising: switching means.