JPH06318181A - Transmitting equipment for switching line - Google Patents

Abstract

(57) [Abstract] [Purpose] A transmission system in which the transmission equipment is connected by two lines, a working line 20 and a protection line 30, and switches to the protection line when the working line fails. By restricting switching back to the working line, the purpose is to avoid a secondary communication interruption. [Structure] Means 2 for detecting and holding failure recovery of the working line,
Means 3 for holding information indicating the permitted time period for switching back
And means 4 for obtaining information indicating the time and means 5 for judging that the time is within the range of the switching back permission time zone. The line switching means 1 is If the time is within the range of the switching permission time zone, the backup line 30 is switched back to the working line 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching back function at the time of failure recovery in a transmission system which switches to a protection line when a working line fails.

[0002]

2. Description of the Related Art In a transmission system in which information is transmitted between two device groups consisting of a computer and a terminal device by two transmission devices, in order to prepare for a failure of the transmission line, there are two lines, a working line and a protection line, between the transmission devices. Connecting with books is done. There are known means for detecting the line disconnection. For example, it is assumed that a control signal is constantly exchanged on the line, and if this cannot be received, a line failure has occurred. The restoration of the line can be detected when the control signal can be received.

The transmission device is provided with a line switching means and switches to the protection line when the working line fails. Also usually
Since the protection line is often inferior in performance and function to the working line, when the working line is restored, the protection line is switched back to the working line.

Conventionally, the switching to the protection line due to the failure of the working line and the switching back to the working line due to the restoration of the line have been carried out immediately by the line switching means or after a fixed time.

[0005]

Therefore, when switching back from the protection line to the working line, there is a problem that communication is interrupted because the protection line is forcibly switched to while the transmission is being carried out smoothly. . Especially, it is often important to communicate using a backup line,
There is a big problem in the way that it is interrupted again and the operation is hindered.

It is an object of the present invention to realize a line switching transmission system which avoids a secondary communication interruption by restricting switching back from a protection line to a working line when a line is restored.

[0007]

FIG. 1 shows a block diagram of an embodiment of the present invention. The figure shows a computer and a terminal device.
A transmission system in which information is transmitted between two device groups by two transmission devices. The transmission devices are connected by two lines, a working line 20 and a protection line 30, and the transmission device 10 has a line switching means 1 It is possible to switch to the protection line when the working line fails.

In one transmission device, a means 2 for detecting a failure recovery of the working line and holding a signal indicating it, and a means 3 for holding information indicating a permission time zone for switching back from the protection line to the working line. And means 4 for obtaining information indicating the time,
Means 5 for comparing the time with the information indicating the permitted time zone to determine that the time is within the range, and the line switching means 1 determines the time when the signal indicating the failure recovery is present. If it is within the permitted time zone, the backup line 30 is switched back to the working line 20.

In the invention of claim 2, the line switching means 1
Irrespective of the presence or absence of a signal indicating failure recovery, when the time falls within the permitted time zone, the backup line (30) is switched back to the working line (20) and the time goes out of the permitted time zone. At this time, if the working line (20) is in a failure state, it is switched to the protection line (30).

In the invention of claim 3, the transmission device (10) is
A means (2) for detecting a failure recovery of the working line and holding a signal indicating the failure, a means for prohibiting the start of new information transmission, and a computer or a terminal when a signal indicating the failure recovery of the working line is issued. A means for checking the interface signals with the device and confirming that they are not operating on the protection line is provided.
The line switching means prohibits the start of new information transmission when a signal indicating the recovery of the working line fault exists, and switches from the standby line to the working line when it is confirmed that the standby line is not used. Configure to bring back.

[0011]

When the signal indicating failure recovery is present, the line switching means 1 switches back from the protection line 30 to the working line 20 if the time is within the switching permission time zone.
The line switching means 1 switches back from the protection line 30 to the working line 20 by setting the switching permission time period to a time period in which the work is not performed when the protection line is not used. With this configuration, it is possible to avoid a secondary communication interruption when switching back from the protection line to the working line when the line is restored.

According to the second aspect of the present invention, when the protection line is a public line, the line is not suppressed during the time when communication is not being performed. According to the third aspect of the present invention, the secondary communication interruption can be avoided when the time zone in which the business is not performed cannot be set.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a transmission device multiplexes lines to perform information transmission between a host computer and a group of terminal devices (which may be personal computers or the like). A high-speed, high-performance dedicated line is used as the working line, and a backup line is provided as a backup in case of failure of the working line. The protection line is not necessarily the same as the working line, and a public line may be used. If the line is disconnected while the working line is in use, switching to the protection line and continuing communication are the same as in the past. In the present invention, the processing when the failed line is restored is different.

FIG. 2 is an explanatory diagram of the line switching return operation of the transmission apparatus of the present invention. It is assumed that the time for communication between the transmission device 10 and the transmission device 10a is determined to be, for example, 7:00 to 21:00. This is decided by considering working hours and some extra hours. With a little extra room, 22
The time from 6:00 to 6:00 is determined as the line switching back permission time zone and registered in the transmission device 10.

A line failure has occurred while communication is being performed on the working line. Then, the transmission device 10 switches to the protection line and performs necessary communication (shown in the figure). After a while, when the line was restored, the conventional method was to immediately switch the line back (shown in the figure). However, at this time, there may be a terminal device communicating with the host on the protection line, and the communication is interrupted.

According to the present invention, even if the working line is restored, it waits until the switching return permission time (shown in the figure) and then returns. Of course, if the recovery of the working line is within the switching back permission time zone (shown in the figure), it is returned immediately.

Even if the failure of the working line is not recovered even when the switching back permission time comes, the switching back may be performed (shown in the figure) regardless of it. Even if it is returned, communication cannot be performed because the working line is not restored, but there is no problem because communication is not originally performed during this time zone. If it recovers after that (shown in the figure), it will be the same. If the working line does not recover even after the end of this period, switch to the protection line again. When a public line is used as the backup line, this can avoid the waste of requiring a charge because the line is held down during the time when communication is not performed.

[0018]

As described above, according to the present invention,
In a transmission system in which two lines, a working line and a protection line, are switched to improve reliability, a secondary line is used when switching back to the working line when the failure of the working line is recovered from the state of using the protection line. The possibility of communication interruption can be reduced.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a line switching back operation of the transmission device of the present invention.

[Explanation of symbols]

1 line switching means 2 means for detecting a failure recovery of a working line and holding a signal indicating it 3 means for holding information indicating a switching permission time zone 4 means for obtaining information indicating a time 5 time range of a switching time zone Means to determine if it is inside 10 Transmission equipment 20 Working line 30 Protection line

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04L 29/04 29/14 9371-5K H04L 13/00 311

Claims (3)

[Claims] 1. A transmission system in which information is transmitted between two device groups consisting of a computer and a terminal device by two transmission devices, and a transmission line (20) and a protection line (30) are provided between the transmission devices. In a transmission system that is connected by a book line, has a line switching means (1) in the transmission device (10), and switches to a protection line when the working line fails, a signal indicating that the working line failure recovery is detected Means (2), means (3) for holding information indicating the permitted time zone for switching back from the protection line to the working line, means (4) for obtaining information indicating the time, and A means (5) is provided for comparing the information indicating the permitted time zone to determine that the time is within the range, and the line switching means (1) determines the time when the signal indicating the failure recovery is present. If it is within the time zone, spare A line switching transmission device (1) characterized by being configured to switch back from the line (30) to the working line (20)
0). 2. The line switching means (1) switches back from the protection line (30) to the working line (20) when the time falls within the permitted time zone regardless of the presence or absence of a signal indicating failure recovery, The line switching transmission device (10) according to claim 1, wherein, when the time is out of the range of the permitted time period, the working line (20) is switched to the protection line (30) if the working line is in a failure state. . 3. A transmission system in which information is transmitted between two device groups consisting of a computer and a terminal device by two transmission devices, and two transmission lines, a working line (20) and a protection line (30), are provided between the transmission devices. Connected by a book line, the transmission device (10) is provided with a line switching means (1), and in the line switching transmission system that switches to the protection line when the working line fails, the failure recovery of the working line is detected and Means (2) for holding the indicated signal, means for prohibiting the start of new information transmission, and when a signal indicating the recovery of the failure of the working line is issued, the interface signals with the computer and the terminal device are checked, and these are reserved. A means for confirming that the line is not operating is provided, and the line switching means prohibits the start of new information transmission when a signal indicating the restoration of the failure of the working line exists, and the protection line is used. When it was confirmed that no line switching transmission apparatus and returning switch from the protection line to the working line.