JP2615514B2 - Line backup device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line backup device for backing up a dedicated line by a switched line when a failure occurs in the dedicated line in a communication system.

Generally, as a method of performing communication between opposing stations, there is a method of using a dedicated line.

According to this communication method, the opposing stations are always connected, so that when a communication request occurs,
There is an advantage that it is not necessary to call each other.

However, this communication method has a problem that communication cannot be performed if a failure occurs in the dedicated line.

Therefore, in a communication method using a dedicated line, a method for backing up a failure in the dedicated line is desired.

[0006]

2. Description of the Related Art As a backup method for a dedicated line,
Conventionally, a method of using a switching service of a communication network has been considered.

According to this line backup method, when a failure occurs in the dedicated line, communication can be continued by calling the opposite station by dialing.

By the way, as a form of the communication system,
Various forms are contemplated.

One of them is a form in which a plurality of communication devices are provided on one of the opposite stations and one communication device is provided on the other.

For example, when communication is performed between a remote station and a center, there is a form in which a plurality of terminal devices are provided in the remote station and communication is performed between these and a host computer of the center.

As a form in which one station is provided with a plurality of communication devices, for example, there is a so-called collective modem.

This collective modem is one in which a plurality of communication devices called a so-called modem unit are housed in one subrack.

Here, the modem unit is a kind of communication device having not only a modulation / demodulation function but also a communication function by a dedicated line and a communication function by a switched line.

[0014] Also in this collective modem, a method is usually employed in which communication is performed using a dedicated line, and when a failure occurs in the dedicated line, communication is performed using a switched line.

In this case, conventionally, as shown in FIG. 4, a dial backup unit 12 (1) to 12 (4) is provided for each of the modem units 11 (1) to 11 (4), so that a dedicated line is provided. When a failure occurs, this dedicated line is backed up by a switched line.

Here, the dial backup unit 1
2 (1) to 12 (4) are the modem units 11 (1) to 11 (11).
This is an interface for connecting (4) to a switched line.

However, such a configuration has a problem that the number of modem units that can be mounted on the subrack is greatly limited by the number of dial backup units.

[0018]

As described above, in the conventional line backup device for a collective modem, since a dial backup unit is provided for each modem unit, the mounting of the modem unit on the subrack is carried out. There is a problem that the number is greatly limited by the dial backup unit.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a line backup device capable of relaxing the limitation on the number of modem units mounted by the dial backup unit.

[0020]

FIG. 1 is a block diagram showing the principle configuration of the present invention.

In the figure, 21 (1) to 21 (n) are communication devices. 22 (1) to 22 (n) are the communication devices 21
(1) This is a dedicated line connected to 21 (n). 23 is
It is a switching line of a communication network.

24 (1) to 24 (n) are a plurality of communication devices 2
1 (1) to 21 (n), and when the corresponding communication device 21 (1) to 21 (n) originates a call,
Dedicated lines 22 (1) -22 connected to (1) -21 (n)
This is a failure detecting means for detecting whether or not a failure has occurred in (n).

Reference numeral 25 denotes a plurality of communication devices 21 (1) to 21 (n) based on the detection results of the failure detection means 24 (1) to 24 (n) when the communication devices 21 (1) to 21 (n) transmit. 21 (n), a predetermined communication device is selected, and the communication devices 21 (1) to 21 (n) are selected.
At the time of an incoming call, a plurality of communication devices 21 based on the selection control information sent from the opposite station via the switching line 23.
Communication device selection means for selecting a predetermined communication device from (1) to 21 (n).

Reference numeral 26 denotes switching line connecting means for connecting the communication device selected by the communication device selecting means 25 to the switching line 23.

[0025]

In the above configuration, for example, the communication device 21 (1)
When a fault occurs in the leased line 22 (1) connected to the communication device 21 (1) during transmission, the fault is detected by the fault detecting means 2.
Detected by 4 (1).

As a result, the communication device 21 (1) is selected by the communication device selection means 25.

The selected communication device 21 (1) is connected to the switching line 23 by the switching line connecting means 26.

On the other hand, while the communication device 21 (1) is receiving a call, the communication device 21 (1) is selected based on the selection control information sent from the opposite station via the switching line 23, and the switching line 2 is selected.
3 is connected.

Although the details are omitted, the other communication devices 21
(2) Dedicated line 22 (2) -22 connected to 21 (n)
The same applies when a failure occurs in (n).

Therefore, according to the present invention, one switching line connecting means 26 is connected to a plurality of communication devices 21 (1) to 21 (21).
(n) can be shared.

Thus, for example, even when the present invention is applied to a line backup device for a collective modem, the limitation on the number of modem units mounted by the dial backup unit can be eased.

[0032]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a block diagram showing the configuration of one embodiment of the present invention.

In the following description, a case where the present invention is applied to a line backup device of a collective modem will be described as a representative.

In the following description, a collective modem having four modem units will be described as a representative.

In the figure, reference numeral 31 denotes a collective modem.
41 is a station facing the station provided with the collective modem 31;
For example, a communication device provided in a center, for example, a host computer.

The collective modem 31 has four modem units 32 (1) to 32 (4) and these four modem units 3 (3) to 32 (4).
It has a dial backup unit 33 which is also used for 2 (1) to 32 (4).

Here, the modem units 32 (1) to 32 (32)
(4) has a communication function using a dedicated line and a switched line.

The dial backup unit 33
Has a function as an interface for connecting each of the modem units 32 (1) to 32 (4) to the switching line.

Each of the modem units 32 (1) to 32 (4)
Each is connected to the dial backup unit 33 via one data transmission line 34 (1) to 34 (4).

Each of the modem units 32 (1) to 32 (32)
(4) is a 10-bit control bus 35 (1), for example.
Through 35 (4) through the dial backup unit 33
It is connected to the.

Each of the control buses 35 (1) to 35 (4) will be described in detail later, but 8 bits out of 10 bits are used as transmission lines for network control information and 2 bits are used as transmission lines for switch control information. Is being used.

Each of the modem units 32 (1) to 32 (4)
Each is connected to the host computer 41 via dedicated lines 51 (1) to 51 (4).

The dial backup unit 33 is connected to a host computer 41 via exchange lines 53 and 54 of a communication network 52.

FIG. 3 is a block diagram showing the configuration of the modem unit 32 (1) and the dial backup unit 33.

The modem units 32 (2) to 32 (4)
Has the same configuration as that of the modem unit 32 (1), and a description thereof will be omitted.

In the modem unit 32 (1), 321
Is a data terminal unit. The data terminal unit 321 exchanges data with the host computer 41.

Reference numeral 322 denotes a modulation / demodulation unit. This modem 3
22 is the data terminal unit 321 to the host computer 4
1 is modulated, and the data sent from the host computer 41 to the data terminal unit 321 is demodulated.

The reference numeral 323 designates the modem 322 as a dedicated line 51.
This is a line section that functions as an interface for connecting to (1).

The line section 323 is connected to the modem sections 322 to 322.
In addition to a transformer for connecting the 342 to the dedicated line 51 (1), it has a low-pass filter for removing noise and various test functions.

Reference numeral 324 denotes a switch for switching the connection target of the modem 322 between the line 323 and the dial backup unit 33.

That is, the movable contact a of the switch section 324 is connected to the fixed contact b when data is exchanged via the dedicated line 51 (1).

Thus, the modulation / demodulation unit 322 is connected to the line unit 3
23.

On the other hand, when data is exchanged via the exchange lines 53 and 54, the connection is made to the fixed contact c.

Thus, the modem 322 is connected to the dial backup unit 33 via the data transmission line 34 (1).

325 is a control unit. This control unit 325
Performs exchange control such as transmission and reception by transmitting and receiving, for example, 8-bit network control information to and from the communication network 52 via the dial backup unit 33.

The network control information is transmitted to the control bus 35 (1)
Are transmitted using a line for 8 bits (hereinafter referred to as a "network control information transmission line"). In the figure, 3
51 (1) is this network control information transmission line.

Further, the control unit 325 controls the data terminal unit 32
1 has a function of detecting whether or not a failure has occurred in the leased line 51 (1) during transmission.

This detection is performed by monitoring the signal state of the modem 322.

That is, if a failure occurs in the dedicated line 51 (1) while the data terminal unit 321 is transmitting, the modem unit 3 (1)
The quality of the signal in 22 is reduced.

The control unit 325 detects that a failure has occurred in the dedicated line 51 (1) by detecting the quality deterioration.

In this case, when a failure is detected, the detection output switches from "0" to "1".

The detection result is supplied to the switch unit 324, and one control line (hereinafter, referred to as "switch control information transmission line") 35 of the control bus 35 (1).
It is supplied to the dial backup unit 33 via 2 (1).

The movable contact "a" of the switch section 324 is switched from the fixed contact "b" to the fixed contact "c" when the control section 325 obtains a detection result indicating that a failure has occurred in the dedicated line 51 (1).

The above-mentioned dial backup unit 33
Is a dial backup unit (hereinafter referred to as “DBU
331, 332) and a selection circuit 333.

The DBU units 331 and 332 are interfaces for connecting the modem units 32 (1) to 32 (4) to the switching lines 53 and 54.

That is, the DBU units 331 and 332
Performs disassembly and assembly of frames, establishment of synchronization, control of a protocol used for transfer of control information, and the like.

The selection circuit 333 includes the switch sections 1A and 2A
And a switch control unit 3A.

Here, the switch unit 1A selects any two data transmission lines from the four data transmission lines 34 (1) to 34 (4) and connects them to the DBU units 331 and 332, respectively. .

On the other hand, the switch unit 2A selects any two network control information transmission lines from the four network control information transmission lines 351 (1) to 351 (4) and connects them to the DBUs 331 and 332, respectively. I do.

The selection operation of the switch sections 1A and 2A is controlled by the switch control section 3A.

That is, the switch control unit 3A is transmitting data from the data terminal unit 321 of each of the modem units 32 (1) to 32 (4) (the data terminal unit 321 is not transmitting data from the host computer 41).
), Each modem unit 32
Based on the detection results supplied from the control units 325 of (1) to 32 (4) via the switch control information transmission lines 352 (1) to 352 (4), the selection operation of the switch units 1A and 2A is controlled. .

For example, when the detection result supplied from the control unit 325 of the modem unit 32 (1) via the switch control information transmission line 352 (1) is “1”, the switch control unit 3A switches the switch unit 1A. , 2A, the data transmission line 34 (1) and the network control information transmission line (1), respectively.
Instruct the selection of.

As a result, the data transmission line 34 (1) and the network control information transmission line 351 (1)
31.

In this state, if the detection result supplied from the control unit 325 of the modem unit 32 (2) via the switch control information transmission line 352 (2) is "1", for example, the switch control unit 3A is a switch unit 1
A and 2A, respectively, the data transmission line 34 (2)
To select the network control information transmission line (2).

As a result, the data transmission line 34 (2) and the network control information transmission line 351 (2) are connected to the DBU 332.

On the other hand, when the host computer 41 is transmitting data (when the host computer 41 is transmitting data to the data terminal unit 321), the switch control unit 3A transmits the data from the host computer 41 via the exchange lines 53 and 54. Based on the received switch control information, the selection operation of the switch units 1A and 2A is controlled.

In this case, the switch control information sent from the host computer 41 is stored in the DBU units 331 and 33.
2 to the switch control unit 3A.

The switch control information supplied from the DBU units 331 and 332 to the switch control unit 3A is, for example, 3-bit digital information.

In this case, the contents of the switch control information are as follows. "000": No selection required "001": Selection of data transmission line 34 (1) and network control information transmission line 351 (1) "010": Data transmission line 34 (2) and network control information transmission line 351 (2) Selection of “011”: selection of data transmission line 34 (3) and network control information transmission line 351 (3) “100”: selection of data transmission line 34 (4) and network control information transmission line 351 (4)

The switch control section 3A controls the selection operation of the switch sections 1A and 2A based on the switch control information, and decodes the switch control information into 1-bit data.

The decoded switch control information is
The switch units of the corresponding modem units 32 (1) to 32 (4) via one switch control information transmission line 353 (1) to 353 (4) in the control buses 35 (1) to 35 (4). 32
4 is supplied.

For example, when the 3-bit switch control information is “001”, the switch control information “1” is set in the switch section 324 of the modem unit 32 (1) via the switch control information transmission line 343 (1). Is supplied.

Thus, the movable contact a of the switch section 324 of the modem unit 32 (1) is switched from the fixed contact b to the fixed contact c.

Note that the DBU is sent from the host computer 41.
As a method of transmitting the switch control information to the units 331 and 332, for example, a method of transmitting the switch control information using a dial-back tone signal or a method of transmitting the switch control information using a one-chip FSK (frequency shift keying) modem can be considered.

The operation of the above configuration will be described.

When no fault has occurred in the dedicated line 51 (1), the movable contact a of the switch section 324 of the modem unit 32 (1) is connected to the fixed contact b.

As a result, the data transmitted from the data terminal 321 to the communication device 41 is modulated by the modem 322 and then transmitted to the line 32 via the switch 324.
3 is supplied.

Then, the data is supplied from the line section 323 to the host computer 41 via the dedicated line 51 (1).

On the other hand, data transmitted from the host computer 41 to the data terminal unit 321 of the modem unit 32 (1) is supplied to the line unit 323 via the dedicated line 51 (1).

Then, the signal is supplied from the line section 323 to the modulation / demodulation section 322 via the switch section 324, demodulated by the modulation / demodulation section 322, and then supplied to the data terminal section 321.

When a failure occurs in the dedicated line 51 (1), the communication between the data terminal unit 321 and the host computer 41 is switched to the exchange service of the communication network 52.

The switching operation in this case is performed by the data terminal unit 3
21 differs depending on whether it is transmitting or receiving.

When the data terminal unit 321 is transmitting a signal, the control unit 325 detects whether a failure has occurred in the dedicated line 51 (1).

When a detection result indicating that a failure has occurred is obtained, the control section 325 outputs switch control information "1".

The switch control information is transmitted to the switch unit 32
4 and to the switch controller 3A via the switch control information transmission line 351 (1).

As a result, the movable contact a of the switch section 324 is switched from the fixed contact b to the fixed contact c.

In the switch units 1A and 2A, the data transmission line 34 (1) and the network control information transmission line 3
51 (1) is selected.

The selected data transmission line 34 (1) and network control information transmission line 351 (1)
31.

Thus, the line connection request information output from the control unit 325 is transmitted to the switch unit 2A and the DBU unit 33.
1. It is supplied to the host computer 41 via the communication network 52.

Thus, the DBU unit 32 (1) and the host computer 41 are connected by the exchange line 53.

Therefore, the data terminal unit 321 and the host computer 41 can exchange data with each other via the exchange line 53.

On the other hand, when the data terminal unit 321 is receiving a call, the host computer 41 uses the dedicated line 51 (1).
Is detected as to whether a failure has occurred.

When a failure occurs in the dedicated line 51 (1), for example, the D
The line connection request information is sent to the BU unit 331.

As a result, the host computer 41 and D
The BU 331 is connected via the switching line 53.

At this time, switch control information for instructing selection of the modem unit 32 (1) is also sent from the host computer 41.

Based on this switch control information, the DBU
The unit 331 supplies 3-bit switch control information “001” to the switch control unit 3A.

As a result, in the switch sections 1A and 2A, the data transmission line 34 (1) and the network control information transmission line 352 (1) are selected, respectively.

Further, the switch section 324 is transmitted from the switch control section 3A via the switch control information transmission line 353 (1).
Is supplied with 1-bit switch control information “1”.

Thus, the movable contact a of the switch section 324 is switched from the fixed contact b to the fixed contact c.

As a result, data can be exchanged between the host computer 41 and the data terminal unit 321 via the exchange line 53.

Although the description is omitted, the exclusive line 51
Similar processing is performed when a failure occurs in (2) to 52 (4).

According to this embodiment described in detail above, the modem unit 32 by the dial backup unit 33
(1) The limitation on the number of implementations of (32) can be relaxed.

This is the dial backup unit 3
3 is provided with a selection circuit 333, and one dial backup unit 33 is connected to four modem units 32 (1) to 32 (32).
This is because (4) is also used.

Further, according to this embodiment, two DBUs
Since the units 331 and 332 are provided, it is possible to cope with a case where a failure occurs simultaneously in two dedicated lines.

Although the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment.

For example, in the above embodiment, the case where the dial backup unit 33 has a plurality of DBU units has been described.

However, in the present invention, one DBU unit may be provided.

In the above embodiment, the case where the present invention is applied to a line backup device of a collective modem has been described.

However, the present invention can be applied to a general line backup device of a communication system having a plurality of communication devices in one station.

In addition, it goes without saying that the present invention can be variously modified and implemented without departing from the scope of the invention.

[0121]

As described in detail above, according to the present invention,
It is possible to provide a line backup device capable of relaxing the restriction on the number of mounted modem units by the dial backup unit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle configuration of a line backup device according to the present invention.

FIG. 2 is a block diagram showing the overall configuration of one embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a main part of FIG. 2;

FIG. 4 is a block diagram showing a configuration of a conventional line backup device in a collective modem.

[Explanation of symbols]

21 (1) to 21 (n) Communication device 22 (1) to 22 (n) Dedicated line 23 Switched line 24 (1) to 24 (n) Failure detecting means 25 Communication device selecting means 26 Switching line connecting means 331,332 Switching line connection means (DBU
333) Communication device selection means (selection circuit) 1A Data transmission line selection means (switch section) 2A Network control information transmission line selection means (switch section) 3A Control means (switch control section)

Claims (3)

(57) [Claims] 1. A line backup device to which a plurality of communication devices are connected, has a communication function by a dedicated line and a switched line, and backs up by the switched line when a failure occurs in the dedicated line. Provided in each of a plurality of communication devices connected to the, when the corresponding communication device outgoing, failure detection means for detecting whether a failure has occurred in the dedicated line connected to the communication device, Connected to the failure detection means, when transmitting the communication device, based on the detection result of the failure detection means, select a communication device in which a failure has occurred in the connected dedicated line from the plurality of communication devices, When an incoming call is received by the communication device, a communication device in which a failure has occurred in a dedicated line to be connected is selected from the plurality of communication devices based on selection control information sent from the opposite station. Communication device selection means, and switching line connection means connected to the communication device selection means and the switching line, and connecting the communication device selected by the communication device selection means to the switching line. Line backup device. 2. The communication device selection means, comprising: a data transmission line selection means for switching and selecting a transmission line of data exchanged between the plurality of communication devices and the opposite station; Network control information transmission line selection means for switching and selecting a transmission line of network control information exchanged with a switched communication network; detection results of the failure detection means and selection control information sent from the opposite station 2. The line backup according to claim 1, further comprising: control means for controlling a switching selection operation of the data transmission line selection means and the network control information transmission line selection means based on the following. apparatus. 3. The communication device selection means is configured to select a predetermined plurality of communication devices from the plurality of communication devices, and the switched line connection device is selected by the communication device selection device. 2. The line backup device according to claim 1, wherein a plurality of communication devices are connected to the switching line.