JPH0677976A - Transmission line reconstituting method for circular transmission system - Google Patents

Abstract

PURPOSE:To reduce the outage time of a system function by disconnecting the fault position of a transmission line and performing reconstitution in a short time after the fault generation of a present system even in the case of double fault in which both of present system and spare system transmission lines are turned to the fault. CONSTITUTION:A transmitter 4 disabling the reception of the time fill for a certain time instructs switching to a spare system transmission line 6 to transmitters 1, 2 and 3 and when it can not be received, the transmitter 4 suppress the sending of the time fill to each transmission line and tries to disconnect itself. When the time fill can not be received for a certain time since the transmitter 4 suppresses the sending of the time fill to the spare system transmission line 6, the transmitter 2 instructed the switching to the spare system transmission line 6 instructs switching to a present system transmission line 5 to the transmitter 1 and 3 and performs loop back. Further, when time fill can not be received for a certain time, the transmitter 3 instructed the transmission line switching to the present system transmission line 5 instructs switching to the spare system transmission line 6 to the transmitters 1 and 2 and performs loop back.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for disconnecting and reconstructing a faulty part of a transmission line in a ring transmission system.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a conventional ring transmission system disclosed in, for example, Japanese Unexamined Patent Publication No. 62-181544, in which four transmission devices are connected. In the figure, 1 to 4 are independent synchronous transmission devices connected to this system, 5 is an annular active transmission line, and 6 is an annular backup transmission line. The directions of the signals transmitted through the active transmission path 5 and the standby transmission path 6 are opposite to each other as shown by the arrows. Here, each transmission device has the same configuration with respect to the transmission system, and the same applies to the transmission path. Normally, the working transmission line 5 is used, and when a failure occurs in the working transmission line 5, it is switched to the protection transmission line 6 and used as the working.

Next, the operation of the ring transmission system having the configuration shown in FIG. 5 in the case of a double failure of the transmission path in which both the active transmission path 5 and the protection transmission path 6 are defective will be described with reference to the drawings. FIG. 4 is a flowchart showing the flow of processing executed by each transmission device. FIG. 6 is a diagram showing an example of a transmission path failure of both systems in which failure points 7 and 8 occur between different transmission devices. 7 to 9 are diagrams showing a state in which the transmission path is reconfigured in order. First, it is assumed that a disconnection failure occurs in the active transmission line 5 between the transmission devices 2 and 4 during data transmission using the active transmission line 5, and at the same time, the transmission devices 3 and 4 are transmitted. It is assumed that a disconnection failure has already occurred in the backup transmission line 6 between the above and the above (see FIG. 6). Since the failure has occurred at the failure point 8 of the active transmission path 5, the transmission apparatus 4 cannot receive the time fill sent by the transmission apparatus 2 and detects a clock abnormality (establishes the first time fill monitoring). ). Since the time fill cannot be received even if the clock is monitored for a fixed time (N seconds), the transmission device 4 determines that the time fill cannot be received (step 12) and sends a special pattern to the active transmission line 5 (step 13). . This special pattern is a specific signal for instructing the transmission device that has received the special pattern to switch the transmission path. This special pattern is received by the transmission devices 3, 1 and 2 in this order (steps 21 and 22), and all the transmission devices switch the transmission path (step 14). As a result, the backup transmission line 6 becomes the active transmission line, and each transmission device sends a time fill to the backup transmission line 6, while monitoring the received time fill for a fixed time (N seconds) (step
15). Here, since the disconnection fault has occurred in the backup transmission line 6 between the transmission devices 3 and 4, the transmission devices 1, 2, and 3 can receive the time fill, but the transmission device 4 cannot receive the time fill ( Second time fill monitoring established). Therefore, the transmission device 4 cannot receive the time fill even if the transmission path is switched. Therefore, as shown in FIG. 7, the transmission apparatus 4 performs loopback switching in which the active transmission path 5 is input and the standby transmission path 6 is output ( Step 16), time fill for a certain time (N
Seconds) to monitor (step 17). However, since there is a disconnection fault in the active transmission line 5 between the transmission devices 2 and 4, the transmission device 4
Cannot receive timefill (third timefill monitoring established). Therefore, the transmission device 4 sends out the special pattern to the backup transmission line 6 (step 18). This special pattern passes through the backup transmission line 6, and is transmitted to the transmission devices 2, 1, 2.
It is received in the order of 3 (steps 21 and 22). Transmission device 2,
1 and 3 switch the transmission path to the active transmission path 5 (step
14), the time fill is monitored for a fixed time (N seconds) (steps 15 for transmission devices 2, 1 and 3 and step 1 for transmission device 4)
9). The transmission device 3 cannot receive the time fill because the transmission device 4 is performing loopback switching (the fourth time fill monitoring is established). Also, the transmission device 4 cannot receive the time fill because of a disconnection failure in the active transmission line 5 between the transmission device 2 and the transmission device 4. First, since the transmission device 3 cannot receive the time fill after receiving the special pattern, as shown in FIG.
Is input and the active transmission path 5 is output, and loopback switching is performed (step 16), and the time fill is set to a fixed time (N
Seconds) to monitor (step 17). Further, since the transmission device 4 cannot receive the time fill even if the special pattern is sent after the loopback switching, the sending device 4 stops sending the time fill to the backup transmission line 6. On the other hand, since the transmission device 3 cannot receive the time fill even after the loopback switching (the fifth time fill monitoring is established), the active transmission line 5
The special pattern is sent to (step 18). This special pattern is received by the transmission devices 1 and 2 in this order through the active transmission line 5 (steps 21 and 22). The transmission devices 1 and 2 switch the transmission path to the backup transmission path 6 (step 14) and monitor the time fill for a fixed time (N seconds) (step 15). The transmission device 3 receives the time fill sent by the transmission device 1 (step 19), but the transmission device 2 cannot receive the time fill because the transmission device 4 inhibits the time fill transmission (the sixth time). Timefill monitoring established). Since the transmission device 2 cannot receive the time fill after switching the transmission lines, as shown in FIG. 9, loopback switching is performed with the active transmission line 5 as the input and the standby transmission line 6 as the output (step 16). By doing so, the time fill sent by the transmission device 1 can be received (step 17). As a result, as shown in FIG. 9, the transmission device 4 is disconnected from the current transmission path, but the transmission devices 1, 2 and 3 can receive the time fill, the failure points 7 and 8 are disconnected, and the reconfiguration is completed.

[0004]

In the conventional ring-shaped transmission system, the above operation is performed in the case of a double failure of the transmission path in which both the active transmission path and the standby transmission path are obstructed. It takes a long time (6 N seconds or more) because time fill monitoring for a certain time (N seconds) must be established a total of 6 times from the occurrence of a failure until the failure point of the transmission line is separated and the reconstruction is completed. There was a problem that it would end up. This is because the entire system is out of function for a long time, which can be a fatal drawback in a system that requires a reliable response at all times.

The present invention has been made in order to solve the above-mentioned problems, and even in the case of a double failure of a transmission line in which both the active transmission line and the standby transmission line become obstacles, The purpose of the present invention is to obtain a transmission line reconfiguration method for a ring-shaped transmission system that can shorten the time of function stoppage of the entire system in a short time from the occurrence of a failure to the point of failure of the transmission path and complete the reconfiguration. .

[0006]

In the ring transmission system according to the present invention, when the transmission device which cannot receive the time fill for a certain period of time cannot receive the time fill even after the instruction to switch the transmission path, the transmission of the time fill is suppressed. On the other hand, if the transmission device that received the transmission path switching instruction cannot receive the time fill for a certain period after switching the transmission path, the transmission apparatus that loops back so that the transmission path before switching is input and the transmission path after switching is output. Be prepared.

[0007]

In the transmission line reconfiguration method of the ring transmission system according to the present invention, when the transmission device which cannot receive the time fill for a certain period of time cannot receive the time fill even after the transmission line switching instruction, the transmission of the time fill is suppressed. While trying to separate this transmission device from the transmission path,
On the other hand, when the transmission device that received the transmission path switching instruction cannot receive the time fill for a certain period of time after switching the transmission path, the transmission path is looped back so that the transmission path before switching is input and the transmission path after switching is output. Reconfigure.

[0008]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing a processing flow of a transmission line reconfiguration method of a ring transmission system according to an embodiment of the present invention, and FIGS. 2 and 3 show a state in which the transmission line is reconfigured in order. FIG. In the figure, the same parts as those in FIGS. 5 to 9 are designated by the same reference numerals, and the description thereof will be omitted.

Next, the operation of the transmission line reconfiguration method of this embodiment will be described. For example, let us consider a case in which there is a failure in the transmission path of both systems such that failure points 7 and 8 occur between different transmission devices as shown in FIG. First, when data is transmitted using the active transmission path 5, the transmission devices 2 and 4
It is assumed that a disconnection failure has occurred in the active transmission path 5 between the transmission lines 3 and 4 and a disconnection failure has already occurred in the protection transmission path 6 between the transmission devices 3 and 4 (see FIG. 6).
Since a failure has occurred at the failure point 8 of the active transmission line 5,
The transmission device 4 cannot receive the time fill sent by the transmission device 2 and detects a clock abnormality (step 31). Since the time fill cannot be received even if the clock is monitored for a fixed time (N seconds) (first time fill monitoring is established), the transmission device 4 judges that the time fill cannot be received (step 32), and the active transmission line 5 is set. The special pattern is transmitted (step 33). This special pattern is transmitted by the transmitter 3,
The signals are received in the order of 1 and 2 (steps 37 and 38), and all the transmission devices switch the transmission path (steps 34 and 40). As a result, the backup transmission line 6 becomes the working transmission line, and each transmission device sends a time fill to the backup transmission line 6,
On the other hand, the received time fill is monitored for a fixed time (N seconds) (steps 35 and 41). Here, since the disconnection fault has occurred in the backup transmission line 6 between the transmission devices 3 and 4, the transmission devices 1, 2, and 3 can receive the time fill, but the transmission device 4 cannot receive the time fill ( Second time fill monitoring established). Therefore, since the transmission device 4 cannot receive the time fill even if the transmission line is switched, it stops sending the time fill to the backup transmission line 6 as shown in FIG. 2 (step 36). As a result, the transmission device 2 cannot receive the time fill (the third time fill monitoring is established). Therefore, since the transmission device 2 cannot receive the time fill after receiving the special pattern, it transmits the special pattern to the backup transmission line 6 (step 42), inputs the active transmission line 5 as shown in FIG. The loopback is switched to output (step 43), and the time fill is monitored for a fixed time (N seconds) (step 44). On the other hand, the special pattern output from the transmission device 2 passes through the backup transmission line 6 and is received by the transmission devices 1 and 3 in that order (steps 45 and 4).
6). The transmission devices 1 and 3 switch the transmission path to the active transmission path 5 (step 47) and set the time fill to a fixed time (N seconds).
Monitor (step 48). The transmission devices 1 and 2 can receive the time fill, but the transmission device 3 cannot receive the time fill because the transmission device 4 has stopped sending the time fill (the fourth time fill monitoring). Established). Therefore, since the transmission device 3 cannot receive the time fill after receiving the special pattern, it transmits the special pattern to the active transmission line 5 (step 42) and inputs the standby transmission line 6 as shown in FIG. Loopback switching is performed with 5 as the output (step 43), and the time fill is monitored for a fixed time (N seconds) (step 44). On the other hand, the transmission device 3
This special pattern output from the device passes through the active transmission line 5 and is received by the transmission devices 1 and 2 in that order (steps 37 and 3).
8). The transmission device 1 switches the transmission path to the backup transmission path 6 (step 40) and monitors the time fill for a fixed time (N seconds) (step 41). Since the transmission device 2 is performing loopback switching, nothing is done. As a result, as shown in FIG. 9, the transmission device 4 is disconnected from the current transmission line,
The transmission devices 1, 2 and 3 can receive the time fill, the faulty parts 7 and 8 are separated, and the reconfiguration is completed. Therefore, according to this method, the time fill monitoring for the fixed time (N seconds) is established only 4 times in total from the occurrence of the failure in the active system to the disconnection of the failure point in the transmission line and the completion of the reconfiguration. (4N seconds).

[0010]

As described above, according to the present invention, when the transmission device which cannot receive the time fill for a certain period of time cannot receive the time fill even after the transmission path switching instruction, the transmission of the time fill is suppressed and the one-way transmission is performed. The transmission device that receives the path switching instruction loops back so that the transmission path before switching is input and the transmission path after switching is output when the time fill cannot be received for a certain period after switching the transmission path. Even in the case of a failure in the transmission paths between the transmission devices, the transmission paths can be reconfigured in a short time and reliably, so that it is possible to reduce the time during which the entire system stops functioning.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing flow of a transmission line reconfiguration method of a ring transmission system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which transmission lines are reconfigured in order in a transmission line reconfiguration method of a ring transmission system according to an embodiment of the present invention.

FIG. 3 is a diagram showing a state in which the transmission line is reconfigured in order in the transmission line reconfiguration method of the ring transmission system according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a processing flow of a transmission path reconfiguration method of a conventional ring transmission system.

FIG. 5 is a diagram showing a configuration of a conventional ring transmission system.

FIG. 6 is a diagram showing an example of a transmission path failure of both systems in which two failure points occur between different transmission devices.

FIG. 7 is a diagram showing a state in which the transmission lines are reconfigured in order in the transmission line reconfiguration method of the conventional ring transmission system.

FIG. 8 is a diagram showing a state in which the transmission line is reconfigured in order in the transmission line reconfiguration method of the conventional ring transmission system.

FIG. 9 is a diagram showing a state in which the transmission line is reconfigured in order in the transmission line reconfiguration method of the conventional ring transmission system.

[Explanation of symbols]

 1 to 4 Independently synchronized transmission device 5 Circular working transmission line 6 Circular backup transmission line 7 and 8 Fault location

Claims (1)

[Claims] 1. A transmission system, comprising: a plurality of transmission devices; and two annular transmission lines connected to these transmission devices, the transmission directions of which are opposite to each other. The transmission device uses one of the transmission lines as an active system. It has a loop-back function that can send and receive data as a transmission line, keep the other as a standby transmission line, and loop back so that one of the transmission lines is the input side and the other is the output side. In the ring transmission system, the transmission device instructs the downstream transmission device to switch to the backup transmission line when it cannot receive the time fill from the upstream transmission device for a certain period of time, and also switches itself to the backup transmission line, and still When the time fill cannot be received for a certain period of time, it suppresses the transmission of its own time fill to the upstream transmission device,
On the other hand, the transmission device that receives the transmission path switching instruction loops back so that the transmission path before switching is the input side and the transmission path after switching is the output side when the time fill cannot be received for a certain period of time after switching the transmission path. A method for reconfiguring a transmission line of a ring transmission system.