JPH06332814A - Transmission line switching system - Google Patents

Abstract

PURPOSE:To improve the secrecy of transmission information and to reduce power consumption relating to a transmission line switching system for switching an in-use transmission line to a stand-by transmission line in a data system provided with the stand-by transmission line substitutable at the time of the fault generation of the transmission line along the in-use transmission line used for information transmission. CONSTITUTION:This system is provided with transmission means 111-11N for respectively transmitting the transmission information to redundantly constituted transmission lines in a full duplex system, monitoring means 131-13N for obtaining and monitoring intervals on the time base of the transmission information received respectively from the transmission lines and a control means 15 for performing the stand-by redundant control of the transmission means 111-11N based on the large/small relation of the interval on the time base obtained by the monitoring means 131-13N and a threshold value matched to the transmission system of the transmission line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in a data system having a working transmission line used for information transmission and a spare transmission line which can be replaced when a failure occurs in the working transmission line, switches the working transmission line to the protection transmission line. The present invention relates to a transmission line switching method.

[0002]

2. Description of the Related Art In a data transmission system, in order to avoid interruption of communication due to a failure in a transmission path, a transmission path is duplicated to smoothly switch a failed working transmission path to a backup transmission path. Many switching methods are adopted.

FIG. 5 is a diagram showing a configuration example of a conventional transmission path switching system. In the figure, transmission information to be sent to the upstream transmission path (hereinafter, simply referred to as “transmission information U”) is given to the modulation inputs of the transmission terminal station devices 52 _H1 and 52 _S1 via the control device 51 ₁ , and these are transmitted. The modulated output of the transmission terminal station device 5 is transmitted via the transmission lines 50 _HU and 50 _SU , respectively.
2 _H2 , connected to the demodulation input of 52 _S2 . Transmission terminal device 5
The demodulated outputs of 2 _H2 and 52 _S2 are connected to the corresponding inputs of the controller 51 ₂ and the transmission information U is available at its output. Transmission information to be sent to the downlink transmission path (hereinafter, simply referred to as “transmission information D”) is given to the modulation inputs of the transmission terminal station devices 52 _H2 and 52 _S2 via the control unit 51 ₂ , and these transmission terminal stations are transmitted. The modulation outputs of the devices are connected to the demodulation inputs of the transmission terminal devices 52 _H1 and 52 _S1 via transmission lines 50 _HD and 50 _SD , respectively. The demodulated outputs of the transmission terminal devices 52 _H1 and 52 _S1 are connected to the corresponding inputs of the control device 51 ₁ , and the transmission information D is obtained at the output thereof.

In the control device 51 ₁ , the transmission information U is given to the input of the branch circuit (H) 53 ₁ , and its two outputs are connected to the modulation inputs of the transmission terminal station devices 52 _H1 and 52 _S1 , respectively. The demodulated outputs of the transmission terminal devices 52 _H1 and 52 _S1 are respectively connected to the first and second contacts of the selection circuit 54 ₁ , and the transmission information D is obtained at the common contacts corresponding to these contacts.

In the control device 51 ₂ , the transmission information D is given to the input of the branch circuit (H) 53 ₂ , and its two outputs are connected to the modulation inputs of the transmission terminal station devices 52 _H2 and 52 _S2 , respectively. The demodulated outputs of the transmission terminal devices 52 _H2 and 52 _S2 are respectively connected to the first and second contacts of the selection circuit 54 ₂ , and the transmission information U is obtained at the common contacts corresponding to these contacts.

In the transmission path switching system having such a configuration, the common contact of the selection circuit 54 ₁ is normally connected to the demodulation output of the transmission terminal station device 52 _H1 , and the common contact of the selection circuit 54 ₂ is the transmission terminal device. It is connected to the demodulation output of 52 _H2 . Therefore, the transmission information U and the transmission information D are transmitted and received via the transmission lines 50 _HU and 50 _HD , respectively.

Further, since the transmission information U is given to the modulation input of the transmission terminal device 52 _S1 via the branch circuit 53 ₁ ,
It is sent to the transmission line 50 _SU at the same time. Furthermore, the transmission information D
Is given to the modulation input of the transmission terminal device 52 _S2 via the branch circuit 53 ₂ , so that it is simultaneously sent to the transmission line 50 _SD .

However, in such a state, for example, when some trouble occurs in the transmission line 50 _HU ,
The control device 51 ₂ detects the occurrence of the failure based on a predetermined communication control procedure and connects the common contact of the selection circuit 54 ₂ to the demodulation output of the transmission terminal station device 52 _S2 , so that the transmission line 50 _HU The transmission information U received via the transmission line 50 _SU , which is a backup transmission line, is obtained via the transmission terminal device 52 _S1 . Furthermore, if a failure occurs on the transmission path 50 _HD ,
The control device 51 ₁ similarly switches the transmission line to the transmission line 50 _SD which is a backup transmission line.

[0009] In between this control apparatus 51 _{1-51 2} mutually, the transmission path of the working replacement scheme is formed, the reliability suppressed to a small value the probability that the communication is interrupted by the fault occurring in the transmission path of the working High data transmission is achieved.

[0010]

By the way, in such a conventional transmission line switching system, particularly in a system for transmitting and receiving military information or the like requiring high confidentiality, the transmission line 50 in which the information is duplicated is used. _HU , 50 _SU (50 _HD , 5
Since it is sent in parallel with 0 _SD ), there is a high possibility that information will be leaked.

Further, the control device 51₁(51₂) Or transmission terminal
Device 52_S1(52_S2), Unpredictable transmission line switching
In order to respond promptly in exchange, a spare transmission line 50_SU,
Fifty _SDThe circuits involved in
I didn't. Therefore, especially in an emergency, the control device 51
₁(51₂) And transmission terminal equipment 52_H1, 52_S1(52_H2, 52
_S2) Is installed outdoors and the drive power is supplied by the battery.
Power consumption is high in the system that must be obtained by
In some cases, the reliability of the circuit described above may deteriorate.

It is an object of the present invention to provide a transmission path switching system capable of increasing the confidentiality of transmission information and reducing power consumption.

[0013]

FIG. 1 is a block diagram showing the principle of the invention described in claim 1. In FIG. The present invention obtains transmission means 11 _{1 to} 11 _N for individually transmitting transmission information to a transmission line having a redundant structure of a full-duplex system, and an interval on the time axis of transmission information individually received from the transmission line. Monitoring means 1
3 _{1 to} 13 _N , the transmission means 11 _{1 to} 11 _N stand by based on the magnitude relation between the time axis interval obtained by the monitoring means 13 _{1 to} 13 _N and the threshold value adapted to the transmission method of the transmission path. And a control means 15 for performing redundant control.

FIG. 2 is a block diagram showing the principle of the invention described in claim 2. According to the present invention, in the transmission path switching method according to claim 1, a monitor signal generating means 21 for generating a monitor signal adapted to a transmission method of a redundantly configured transmission path.
And monitor signal transmitting means 23 ₁ to 23 _N for individually transmitting the monitor signals generated by the monitor signal generating means 21 to the redundant transmission lines, and the control means 15 includes:
Monitor signal transmitting means 23 ₁ to 2 in parallel with the standby redundancy control
It is characterized in that it includes means for setting the 3 _N individually to the corresponding transmission means 11 _{1 to} 11 _N in a standby state in a contradictory manner.

[0015]

In the transmission path switching system according to the _{first aspect} , the monitoring means 13 _{1 to} 13 _N obtain the intervals on the time axis of the transmission information individually received from the redundantly configured transmission paths, and the control means 15 If the interval on the time axis obtained in this way is less than the threshold suitable for the transmission method, the transmission means 11
_The transmission information is transmitted to the transmission path through any one of _{1 to} 11 _N , and all the remaining transmission means are set to the standby state. However, when the transmission information is exceeded, the transmission information is set to the non-standby transmission means. Recognizing that a failure has occurred in the corresponding transmission path, the transmission means is set to the standby state, and any one of the remaining transmission means is removed from the standby state to continue transmission of the transmission information.

That is, since the transmission path is secured by controlling the redundantly configured transmission path by the standby redundancy system, and the transmission information is transmitted through only one of such transmission paths, Compared with the conventional example in which the transmission information is transmitted in parallel to the transmission line, the possibility that the transmission information is leaked due to an unauthorized access to the transmission line is significantly reduced, and the confidentiality of the transmission information is improved.

In the transmission path switching method according to the second aspect, the control means 15 includes all the monitor signal transmitting means corresponding to the individual transmitting means set to the standby state among the transmitting means 11 _{1 to} 11 _N. Is set to non-standby, and the monitor signal transmitting means corresponding to the transmitting means set to non-standby is set to standby.

That is, since the monitor signal is constantly transmitted via the monitor signal transmitting means respectively corresponding to all the spare transmission lines that do not transmit the transmission information, the opposing individual transmission lines are provided through these spare transmission lines. In this monitoring means, the spare transmission line in which the failure has occurred is recognized prior to switching,
It becomes possible to exclude from the switching destination of the current transmission path.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 3 is a diagram showing an embodiment corresponding to the invention described in claim 1.

The difference between this embodiment and the conventional example shown in FIG. 5 is that instead of the control devices 51 ₁ and 51 ₂ , a control device 31 ₁
31 ₂ , and the transmission terminal equipment 52 _H1 , 52 _H2 , 52 _S1 ,
52 _S2 instead of optical transmission terminal equipment 32 _H1 , 32 _H2 , 3
It is equipped with 2 _S1 and 32 _S2 .

In the optical transmission terminal device 32 _H1 , the control device 31
_The transmission information U given through ₁ is the transmission drive circuit (DR
V) 33 _H1 and electro-optical conversion circuit (E / O) 34 _H1 to the transmission line 50 _HU . The inputs of the opto-electric conversion circuit (O / E) 35 _H1 and the monitor circuit 36 _H1 are:
The transmission line 50 _HD is connected.

In the optical transmission terminal device 32 _S1 , the control device 31
_The transmission information U given through ₁ is the transmission drive circuit (DR
V) 33 _S1 and the electro-optical conversion circuit (E / O) 34 _S1 are connected to the transmission line 50 _SU . The inputs of the optical-electrical conversion circuit (O / E) 35 _S1 and the monitor circuit (MON) 36 _S1 are connected to the transmission line 50 _SD .

[0023] The control unit 31 _1, the transmission information U is applied to one contact of the buffer circuit (BUF) 37 ₁ of the input and the selection circuit 38 _1, the output of the buffer circuit 37 ₁ while the other contact of the selecting circuit 38 ₁ Connected to. Selection circuit 38
The common contact ₁ is connected to the inputs of the transmission drive circuits 33 _H1 and 33 _S1 , and the outputs of the opto-electric conversion circuits 35 _H1 and 35 _S1 are directly connected to output the transmission information D. Monitor circuit 36 _H1 , 36
The output of _S1 is connected to the corresponding input of the supervisory control circuit (SVC) 39 ₁ , and its two outputs are connected to the inputs of the control signal transmission circuits (D) 40 _1H and 40 _1S , respectively. The output of the control signal transmission circuit 40 _1H is connected to the control input of the transmission drive circuit 33 _H1 , and the output of the control signal transmission circuit 40 _1S is connected to the control inputs of the selection circuit 38 ₁ and the transmission drive circuit 33 _S1 .

Since the control device 31 ₂ has the same configuration as the control device 31 ₁ , the reference numeral of the corresponding component is shown by adding " ₂ " as the first sub-number, and The description is omitted. Further, regarding the optical transmission terminal device 32 _H2 , the control device 31 ₂ and the transmission path 50 _HU , 5
Since it is composed of a circuit formed in the same way as the optical transmission terminal device 32 _S1 between the _HD and 0 _HD , " _H2 " is added to the number of the corresponding component as a sub-number, and the description thereof is given. Is omitted. Furthermore, the optical transmission terminal apparatus 32 _S2 is because it is composed of a circuit formed in the same manner as the optical transmission terminal apparatus 32 _H1 between the transmission line 50 _SU, 50 _SD and control device 31 _2, in which , " _S2 " is added to the number of the corresponding component as a subscript, and the description thereof is omitted.

Further, regarding the correspondence between this embodiment and the block diagram shown in FIG. 1, the transmission drive circuits 33 _H1 and 33 _H3
S1 (33 _H2 , 33 _S2 ) and electro-optical conversion circuit 34 _H1 ,
_{34 S1 (34 H2, 34 S2} ) corresponds to the transmission unit 11 ₁ to 11 _N, the monitor circuit _{36 H1, 36 S1 (36 H2} , 36 S2) and the monitor control circuit 39 ₁ (39 ₂₎ Monitoring means 13 ₁ ~
Corresponding to 13 _N , the monitor control circuit 39 ₁ (39 ₂ ) and the control signal transmission circuits 40 _1H , 40 _1S (40 _2H , 40 _2S ) correspond to the control means 15.

The operation of this embodiment will be described below. In the control device 31 ₁ , the monitoring control circuit 39 ₁ continuously sends a transmission ON control signal (hereinafter, simply referred to as an “ON signal”) to the transmission drive circuit 33 _H1 via the control signal transmission circuit 40 _1H during normal operation. And the transmission drive control circuit 33 _S1 and the selection circuit 38 ₁ are continuously supplied with a transmission off control signal (hereinafter, simply referred to as “off signal”) via the control signal transmission circuit 40 _1S . The transmission information U is directly given to the common contact of the selection circuit 38 ₁ according to such an OFF signal without passing through the buffer circuit 37 ₁ , and the transmission information U is transmitted to the optical transmission terminal device 3.
It is transmitted to the 2 _H1 and 32 _S1 sides.

In the optical transmission terminal device 32 _S1 , the transmission drive circuit 33 _S1 stops its operation and stands by in response to the above-mentioned OFF signal. Therefore, no optical signal is emitted to the transmission line 50 _SU via the electro-optical conversion circuit 34 _S1 .

In the optical transmission terminal device 32 _H1 , the transmission drive circuit 33 _H1 operates according to the ON signal described above, and the instantaneous value of the transmission information U transmitted via the control device 31 ₁ is a specified value. To the electric-optical conversion circuit 34 _H1 . The electro-optical conversion circuit 34 _H1 converts the transmission information U thus converted into an optical signal and outputs the optical signal to the transmission line 50 _HU .

On the other hand, in the optical transmission terminal station device 32 _S2 , the optical-electrical conversion circuit 35 _S2 sets the output end thereof to the unpowered and ungrounded state because the optical signal is not received from the transmission line 50 _SU . In the optical transmission terminal device 32 _H2 , the optical-electrical conversion circuit 35
_{Since H2} sequentially converts the optical signal received through the transmission path _50HU into an electric signal, the transmission information U is restored and obtained at the output end. Further, the monitor circuit 36 _H2 similarly takes in an optical signal received through the transmission path 50 _HU , and when it judges that the signal is normal, it sends out the result of the judgment.

In the control device 31 ₂ , the supervisory control circuit 39 ₂ controls the control signal transmission circuit 40 according to such a determination result.
_An ON signal is given to the transmission drive circuit 33 _H2 and the selection circuit 38 ₂ via _2H , and an OFF signal is given to the transmission drive circuit 33 _S2 via the control signal transmission circuit 40 _2S . Selection circuit 38
Transmission information D is given to the _two common contacts in response to such an OFF signal without passing through the buffer circuit 37 _2. The transmission information is transmitted to the optical transmission terminal station devices 32 _H2 and 32 _S2 .

In the optical transmission terminal device 32 _H2 , the transmission drive circuit 33 _H2 operates according to the above-mentioned ON signal, and the instantaneous value of the transmission information D transmitted via the control device 31 ₂ is a specified value. To the electric-optical conversion circuit 34 _H2 . The electro-optical conversion circuit 34 _H2 converts the transmission information D thus converted into an optical signal and outputs it to the transmission path 50 _HD .

In the optical transmission terminal device 32 _S2 , the transmission drive circuit 33 _S2 stops its operation and stands by in response to the above-mentioned OFF signal. Therefore, no optical signal is emitted to the transmission path 50 _SD via the electro-optical conversion circuit 34 _S2 .

In the optical transmission terminal device 32 _S1 , the optical-electrical conversion circuit 35 _S1 sets its output end to the unpowered and ungrounded state because no optical signal is received from the transmission line 50 _SD . In the optical transmission terminal device 32 _H1 , the optical-electrical conversion circuit 35 _H1 sequentially converts the optical signal received through the transmission path 50 _HD into an electrical signal, so that the transmission information D is restored at the output end. can get.

Therefore, normally, the transmission information U is transmitted via the transmission line 50 _HU , but is not transmitted to the backup transmission line 50 _SU , and the transmission information D is transmitted via the transmission line 50 _HD. Is not transmitted to the spare transmission line 50 _SD .

Further, in the state where the transmission information U and the transmission information D are normally transmitted in this way, the monitor circuits 36 _H2 and 36 _H1 are respectively connected to the active transmission lines 50 _HU and 5 _HU .
0 _HD is continuously monitored for normality based on a predetermined transmission procedure, and the buffer circuit 37 ₁ ,
37 ₂ sequentially stores the transmission information U and the transmission information D on the memory of the last-in / first-out method.

In such a state, the monitor circuit 36 _H2 sends an alarm signal when it detects, for example, some failure that has occurred in the transmission line 50 _HU . In the control device 31 ₂ , when the monitoring control device 39 ₂ recognizes such an alarm signal, the monitoring control device 39 ₂ starts the operation of the transmission drive circuit 33 _S2 via the control signal transmission circuit 40 _2S , and in parallel, the control signal transmission circuit 4 2 S.
The operation of the transmission drive circuit 33 _H2 is stopped via 0 _2H , and the common contact of the selection circuit 38 ₂ is switched to the buffer circuit 37 ₂ side.

Therefore, the emission of the optical signal to the transmission path 50 _HD is interrupted, and the transmission drive circuit 33 _S2 transmits the transmission information U accumulated prior to the buffer circuit 37 ₂ via the electro-optical conversion circuit 34 _S2. It is emitted to the transmission path 50 _SD by converting it into electric light.

In the optical transmission terminal device 32 _H1 , the monitor circuit 3
When 6 _H1 detects that the optical signal received from the transmission path 50 _HD has stopped, it sends an alarm signal to that effect. In the control device 31 ₁ , when the supervisory control circuit 39 ₁ recognizes such an alarm signal, it stops the operation of the transmission drive circuit 33 _H1 via the control signal transmission circuit 40 _1H , and in parallel, the control signal transmission circuit 40 _1S. The operation of the transmission drive circuit 33 _S1 is started via the switch, and the common contact of the selection circuit 38 ₁ is switched to the buffer circuit 37 ₁ side.

Therefore, the emission of the optical signal to the transmission line 50 _HU is interrupted, and the transmission drive circuit 33 _S1 transmits the transmission information D accumulated prior to the buffer circuit 37 ₁ via the electro-optical conversion circuit 34 _S1. It is emitted to the transmission line 50 _SU by the electric-optical conversion.

Therefore, the transmission path of the transmission information U is currently in use.
Transmission line 50_HUTo backup transmission line 50 _SUCan be switched to
At the same time, the transmission path of the transmission information D is the current transmission path 50._HDFrom
Backup transmission line 50_SDCan be switched to. In addition, the transmission line 5
0_HUFrom the time when the
Transmission information given within the time required to complete replacement
Buffer circuits for U and transmission information D, respectively
37₁, 37₂By setting the storage capacity of the
Transmission line 50 without missing_SU, 50_SDSent to
It

As described above, according to this embodiment, the current transmission
When the transmission information is normally transmitted and received via the route,
Transmission drive circuit 33 corresponding to the spare transmission line_S1, 33
_S2(33 _H1, 33_H2) By stopping the operation of
Unnecessarily sending transmission information to these spare transmission lines
Without fail, ensure the transmission line in use when it fails
The communication path is secured by switching to the backup transmission path.

Therefore, highly reliable data transmission becomes possible while suppressing the possibility of leakage of transmission information, and in particular, high confidentiality required for military data transmission systems can be obtained. In addition, since it is not necessary to always operate the transmission drive circuits 33 _S1 , 33 _S2 (33 _H1 , 33 _H2 ) corresponding to the spare transmission line in order to quickly respond to unpredictable transmission line switching, power consumption is reduced. It is reduced and reliability is improved.

FIG. 4 is a diagram showing an embodiment corresponding to the invention described in claim 2. In FIG. In the figure, those having the same functions and configurations as those shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted here.

On the configuration of this embodiment and the embodiment shown in FIG.
The difference is that the optical transmission terminal device 32_H1, 32_H2, 32_S1Three
Two_S2Instead of the optical transmission terminal equipment 41_H1, 41_H2,
41 _S1, 41_S2Is equipped with.

In the optical transmission terminal device 41 _H1 , the transmission drive circuit 33 _H1 is always set to the operating state, and its input end is connected to the common contact of the switching circuit 42 _H1 . Switching circuit 4
One contact of 2 _H1 is connected to the output of the monitor signal generating circuit (G) 43 _H1 . The transmission information U is given to the other contact of the switching circuit 42 _H1 via the control device 31 ₁ , and the control signal sending circuit 40 _1H is _{supplied to} the control input of the switching circuit 42 _H1.
The output of is connected. Note that the optical transmission terminal station device 41 _S1 has the same configuration as the optical transmission terminal station device 41 _H1 and the transmission information U is similarly given via the control device 31 _1. Add subscripts to the components
_The same reference number as " _S1 " is given and its description is omitted. Further, regarding the optical transmission terminal devices 41 _H2 and 41 _S2 ,
Since the configuration is the same as that of the optical transmission terminal devices 41 _S1 and 41 _H1 , respectively, and the transmission information D instead of the transmission information U is given via the control device 31 ₂ , here, the corresponding constituent elements are assigned subscript numbers. _{Are assigned} the same reference numerals as " _H2 " and " _S2 " and the description thereof is omitted.

Regarding the correspondence between this embodiment and the block diagram shown in FIG. 2, the monitor signal generating circuits 43 _H1 , 4 _H
3 _S1 (43 _H2 , 43 _S2 ) corresponds to the monitor signal generating means 21, and switching circuits 42 _H1 , 42 _S1 (42 _H2 , 42 _S2 ),
Transmission drive circuit _{33 H1, 33 S1 (33 H2} , 33 S2) and electro - optical conversion circuit _{34 H1, 34 S1 (34 H2} , 34 S2) corresponds to the monitor signal transmitting means 23 ₁ ~ 23 _N.

The operation of this embodiment will be described below. In this embodiment, the current transmission lines 50 _HU , 50 _HD (50 _SU , 5
0 _SD ), transmission and reception of transmission information, and protection of the transmission lines 50 _SU , 50
For the procedure to switch to _SD (50 _HU , 50 _HD ),
Since it is the same as the embodiment shown in FIG. 3, its explanation is omitted here.

Monitor signal generation circuit 43_H1, 43_H2, 43
_S1, 43_S2Are transmission lines 50 _HU, 50_HD5,
0_SU, 50_SDSent to the network to determine the normality of these transmission lines.
Continuously generate a monitor signal that gives a judgment criterion
It

Switching circuit 42 corresponding to the spare transmission line
_S1 and 42 _S2 (42 _H1 and 42 _H2 ) are control signal transmission circuits 40 _1S and 40 _2S from the supervisory control devices 39 ₁ and 39 ₂ , respectively.
The connection destination of the common contact is set according to the alarm signal and the control signal given via (40 _1H , 40 _2H ), and the above-mentioned is applied to the input end of the transmission drive circuits 33 _S1 , 33 _S2 (33 _H1 , 33 _H2 ). Give a monitor signal. Therefore, such a monitor signal, a spare transmission line _{50 SU, 50 SD (50 HU} , 50 HD) optical transmission terminal apparatus 41 _S2 facing through, 41 _S1 (4
1 _H2 , 41 _H1 ) is always transmitted.

Optical transmission terminal equipment 41 _S2 , 41 _S1 (41 _H2 ,
41 _H1 ), monitor circuits 36 _S2 , 36 _S1 (41 _H2 , 4
1 _H1 ) monitors whether such a monitor signal is constantly received from the corresponding transmission path, and when the monitor signal is interrupted, sends an alarm signal indicating that.

When the supervisory control circuits 39 ₂ and 39 ₁ of the control devices 31 ₂ and 31 ₁ recognize such an alarm signal, they recognize that a failure has occurred in the corresponding backup transmission line, Exclude from the switching destination of the current transmission path.

As described above, according to the present embodiment, it is constantly monitored whether or not a failure has occurred in the backup transmission line in parallel with the transmission / reception of the transmission information via the active transmission line. In the redundant data transmission system, it is possible to confirm that the backup transmission line is normal and switch the transmission line reliably.In addition, in the data transmission system in which the transmission line is redundantly configured, the It is possible to select a normal spare transmission line accurately and smoothly switch the transmission line when the transmission line fails.

In this embodiment, the optical transmission terminal equipment 41 is used.
_The monitor signal generation circuits 43 _H1 , 43 _S1 , 43 _H2 , and 43 _S2 are individually mounted on the _H1 , 41 _S1 , 41 _H2 , and 41 _S2 .
The present invention is not limited to such a configuration, and for example, the monitor signal generating circuits 43 _H1 , 43 _S1 (43 _H2 , 43 _S2 ) may be degenerated and a single monitor signal generating circuit may be mounted.

Further, in the present embodiment, the transmission drive circuit 3
3 _H1 , 33 _S1 (33 _H2 , 33 _S2 ) switching circuit 42 _H1 ,
Although the monitor signal is given through 42 _S1 (42 _H2 , 42 _S2 ), the present invention is not limited to such a configuration, and for example, monitor signal generation circuits 43 _H1 , 43 _S1 (43 _H2 , 43 _S2 )
_S2 ) is newly provided with a transmission drive circuit directly connected to the output, and these transmission drive circuits and transmission drive circuits 42 _H1 , 42
Alternatively, _S1 (42 _H2 , 42 _S2 ) may be operated alternately, or the transmission drive circuit newly provided in this way may be duplicated in the electro-optical conversion circuit in the subsequent stage and similarly operated alternately.

Further, in each of the above-described embodiments, buffer circuits 37 ₁ and 37 ₂ for storing the transmission information given within the switching required time are used in order to avoid the loss of the transmission information due to the switching of the transmission path. However, such a buffer circuit employs, for example, a frame relay exchange method or a cell relay exchange method, and a workaround for the loss of transmission information is taken based on the communication procedure performed end-to-end, or the loss is allowed. It is not necessary when the present invention is applied to the data transmission system described above.

In each of the above-described embodiments, the inventions described in claims 1 and 2 are applied to the optical fiber communication system in which unprocedural data transmission is performed on the transmission path. The present invention is not limited to such a system, and, for example, if it is a system that performs transparent data transmission based on a frame synchronization method, for example, a relay line transmission system such as a digital wireless communication system using microwaves, LAN, voice and video in real time It can also be applied to a subscriber line transmission system for transmitting data to a subscriber line.

Furthermore, in each of the above-described embodiments, the monitor circuits 36 _H1 , 36 _H2 , 36 _S1 , and 36 _S2 determine whether or not there is an optical signal received from the corresponding transmission path and the content of information given by the signal. , The normality is monitored based on a predetermined procedure, but the present invention is not limited to such a monitoring method.For example, in a data transmission system adopting a frame synchronization system, the result of correlation detection of a frame synchronization pattern is detected. The presence or absence of frame synchronism may be monitored based on the same, or similar monitoring may be performed based on the value of the code error rate with respect to a predetermined threshold value or the communication procedure to be performed via the transmission path.

In each of the above embodiments, the transmission information U
It is assumed that the transmission information D is continuously given and the common contact of the selection circuits 38 ₁ and 38 ₂ is interlocked with the switching of the transmission path to switch, but the present invention is not limited to such a configuration, and for example, When the control devices 31 ₁ and 31 ₂ detect that all the transmission information accumulated in the buffer circuits 37 ₁ and 37 ₂ have been sent out, the selection circuit 38
Control may be performed to restore the common contact of ₁ and 38 ₂ to the state before switching the transmission path.

[0059]

As described above, according to the present invention, the transmission information is transmitted through only one of such transmission lines by performing the standby redundancy control of the redundantly constructed transmission line. In parallel with the redundant control, since the monitor signal is always transmitted to all the spare transmission lines where the transmission information is not transmitted, the transmission information is transmitted in comparison with the conventional example in which the transmission information is transmitted in parallel to all the transmission lines. The possibility that transmission information will be leaked due to unauthorized access to the path is greatly reduced, and the stations facing each other through these spare transmission paths will recognize it prior to switching the failed backup transmission path. However, it is possible to exclude from the switching destination of the active transmission path.

Therefore, in the data transmission system to which the present invention is applied, the redundant transmission line is used to maintain the reliability of the transmission line, while the high confidentiality of the transmission information required in the military and other fields is maintained. can get.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the invention according to claim 1.

FIG. 2 is a principle block diagram of the invention described in claim 2.

FIG. 3 is a diagram showing an embodiment corresponding to the invention described in claim 1.

FIG. 4 is a diagram showing an embodiment corresponding to the invention described in claim 2.

FIG. 5 is a diagram showing a configuration example of a conventional transmission path switching system.

[Description of Reference Signs] 11 transmitting means 13 monitoring means 15 control means 21 monitor signal generating means 22 monitor signal transmitting means 31, 51 control device 32, 41 optical transmission terminal device 33 transmission drive circuit (DRV) 34 electro-optical conversion circuit (E / O) 35 Optical-electric conversion circuit (O / E) 36 Monitor circuit 37 Buffer circuit (BUF) 38 Selection circuit 39 Supervisory control circuit (SVC) 40 Control signal sending circuit (D) 42 Switching circuit 43 Monitor signal generation Circuit (G) 50 Transmission line 52 Transmission terminal station device 53 Branch circuit (H) 54 Selection circuit

Claims (2)

[Claims] 1. A transmission means (11 _{1 to} 11 _N ) for individually transmitting transmission information to a transmission line having a redundant structure of a full-duplex system.
When the monitoring means for monitoring seeking interval on the time axis of the transmission information received separately from the transmission path and (13 ₁ ~13 _N), the monitoring means (13 ₁ ~13 _N) time obtained by The transmitting means (11 ₁ to ₁ 1) is based on the magnitude relation between the axial interval and the threshold value adapted to the transmission method of the transmission path.
1 _N ) and a control means (15) for performing standby redundancy control of the transmission line switching method. 2. The transmission path switching method according to claim 1, wherein the monitor signal generation means (21) generates a monitor signal adapted to the transmission method of the redundantly configured transmission path, and the monitor signal generation means (21). ) and a monitor signal transmitting means (23 ₁ ~ 23 _N) for transmitting individual monitor signals generated in the transmission path, which is the redundancy by the control means (15), in parallel to the standby redundancy control Monitor signal transmitting means (23 ₁ ~
23 _N ) individually corresponding transmission means (11 _{1 to} 11 _N )
And a transmission line switching method characterized by including means for setting a standby state in a contradictory manner.