JP2802370B2 - Loop network failure automatic recovery method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic recovery method for a fixed fault in a reverse double loop network in which no supervisory control station exists.

Conventional technology Conventionally, as shown in FIG.
To 6000 are connected by the reverse double loop transmission lines of the working system and the protection system, and transmission right is sequentially given to each station by a specific frame circulating on the loop transmission line.
Is well known.

Conventionally, for loop network failures, when it is detected that the clock of the transmission line is lost, first switch the loop transmission line to check whether it operates normally. A loopback operation for connecting both transmission paths via the station is performed, and finally two stations are looped back to reconfigure the loop system.

In the above loopback method, the receivers of the stations at both ends of the failure point recognize the failure of the partner (the cable of the transmission line connected to the adjacent station or the receiver of the station) and perform the reconfiguration. for that reason,
If there is a fixed failure in both the working and protection receiving systems in the same station, that is, if both working and protection receivers fail simultaneously, or if both working and protection receiving connectors are connected If a fixed failure occurs, or if the cables connected to both the working and protection systems receive a fixed failure at the same time, it is only the station that detects the failure and performs the failure recovery operation. The back operation occurs only at one station where a failure has occurred, resulting in a one-sided loop-back configuration, and the network is not normally reconfigured.

[Problem to be Solved by the Invention] An object of the present invention is to solve such a conventional drawback, when a fixed failure occurs in both the working and standby receiving systems of one station, the station is voluntarily activated. Another object of the present invention is to provide a loop network failure automatic recovery system which can recognize that both the working system and the protection system of the own station have a fixed failure and take appropriate measures.

"Means for Solving the Problems" The loop network failure automatic recovery method of the present invention comprises:
A data transmission system in which a plurality of stations are connected by a reverse double loop transmission line of a working system and a protection system, and clock synchronization of the loop transmission line is an independent synchronization system in which all stations have an oscillator and generate a transmission clock. At
Storage means for storing transmission line switching history in each station;
A transmission clock disconnection detection circuit for detecting the transmission clock disconnection as a clock abnormality, and the station that first detects the clock abnormality performs switching of the loop transmission path and stores the fact that the switching operation has been performed in the storage means, After the switching, if a clock abnormality is detected again at the same station, the fact that the previous switching operation has been performed is written in the storage means. It recognizes that there is, and stops the operation of both the active and standby oscillators of the own station without looping back the own station, thereby causing the stations at both ends of the own station to loop back.

Embodiment FIG. 1 is a block diagram of a station used in an embodiment of the present invention.

The station is connected to optical fiber cables 1A, 1B, 2A, 2B. The optical fiber cables 1A and 2A are working transmission paths, and the optical fiber cables 1B and 2B are protection transmission paths.
The active transmission lines 1A and 2A are connected to the optical module 4,
1B and 2B are connected to the optical module 5. The input from the transmission line 1A is input to the optical module 4, and after being subjected to photoelectric conversion, is separated into data and a clock.
Then, the clock is output to the signal line 103B. Similarly, an input from the transmission line 1B is input to the optical module 5, and after being subjected to photoelectric conversion, is separated into data and a clock. The data is output to the signal line 101A and the clock is output to the signal line 101B.

The signal lines 100A, 100B, 101A, 101B, 102A, 102B, 103A, 103B are connected to the changeover switch 6. It is instructed by the signal line 120 from the control circuit 15 to the changeover switch 6 whether to use the active transmission line A system, the B system, or the loopback configuration, and the connection of the signal line is switched according to the content of the instruction. . In the case of the current operation in the A system, the signal lines 103A and 103B are connected to the data signal line 104 and the clock signal line 105, the data signal line 104 is connected to the system switching instruction signal detecting circuit 9, and the clock signal line 105 is connected to the transmission clock disconnection detecting circuit. 7 and the signal lines 100A and 100B are connected to the signal lines 110 and 111. That is, the active transmission unit and the reception unit are connected internally. At this time B
The signal lines 101A and 101B from the system optical module 5 are connected to the signal lines 102A and 102B, respectively. That is, the protection system transmission unit and the reception unit are not connected to the inside, and the B system transmission line becomes the protection system and is bypassed. . Signal line 10 for current operation in B system
1A and 101B are connected to the data signal line 104 and the clock signal line 105, and the data signal line 104 is connected to the system switching instruction signal detecting circuit 9.
The clock signal line 105 is connected to the transmission clock disconnection detection circuit 7, and the signal lines 102A and 102B are connected to the signal lines 110 and 111. At this time, the signal line 103 from the A-system optical module 4
A and 103B are connected to signal lines 100A and 100B, respectively, and the A-system transmission line becomes a standby system and is bypassed. In the loopback configuration, if there is a failure on the transmission line 1A, 2B side, the signal line 101A,
101B is connected to the data signal line 104 and the clock signal line 105, and the data signal line 104 is connected to the system switching instruction signal detection circuit 9
The clock signal line 105 is connected to the transmission clock disconnection detection circuit 7, and the signal lines 100A and 100B are connected to the signal lines 110 and 111. When there is a fault on the transmission lines 2A and 1B, the signal line 103
A and 103B are connected to the data signal line 104 and the clock signal line 105, and the data signal line 104 is connected to the system switching instruction signal detection circuit 9.
Further, the clock signal line 105 is connected to the transmission clock disconnection detection circuit 7, and the signal lines 102A and 102B are connected to the signal lines 110 and 111.

The output signal line 106 from the transmission clock interruption detecting circuit 7 generates an output only when the transmission clock interruption is detected. This output signal line 106 is connected to the self-station detected one-side fault storage circuit 10 and the gate circuit 13 as transmission line switching history storage means. The other input of the gate circuit 13 is connected to an output signal line 107 of the self-detection one-side fault storage circuit 10. Output signal line 107
Is turned on when the stored contents exist in the one-side fault storage circuit 10 detected by the own station, and the gate circuit 13 is opened. The output signal line 108 of the gate circuit 13 is connected to the optical module power control circuit 14
And the power of the transmission units of the optical modules 4 and 5 is turned off by the output of the signal line 108.

The transmission clock supply circuit 12 is a circuit that generates a clock of the transmission line, is input to the changeover switch 6 via the signal line 111, and is connected to the signal line 100B or 102B. The system switching instruction signal generation circuit 11 is a circuit that generates a signal for instructing another station to switch the transmission line to be used.
The output of the system switching instruction signal generating circuit 11 enters the changeover switch 6 via the signal line 110 and flows to the signal line 100A or 102A.

Next, the operation of the station when there is a fixed failure in the active and standby receiving systems of one station will be described. As shown in FIG. 2, the fixed fault has occurred in the receiving systems 1A and 1B of the station 1000. 1A is the receiving system of the A system transmission line,
At first it is working system. 1B is a receiving system of the B-system transmission line, which is a standby system at first. Here, the failure recovery operation will be described with reference to FIGS. The monitoring of the transmission path state at the station receiver such as the transmission clock interruption is performed only on either 1A or 1B. First, when the above-mentioned fixed failure occurs, this is detected on the 1A side. The state of the transmission path, that is, the clock cutoff state is detected by the transmission clock cutoff detection circuit 7 from the optical module 4 via the changeover switch 6 in FIG. When the clock disconnection is detected, the system switching instruction signal generating circuit 11 is started, a system switching instruction signal is generated, and the
The light is transmitted from the optical module 4 to the optical transmission path through the changeover switch 6. At the same time, when the transmission line clock disconnection detection circuit 7 detects the transmission line clock disconnection, the circuit uses the signal line 106 to store the self-station detected single-system failure state in the self-station detected single-system failure storage circuit 10. Then, after a certain period of time, the changeover switch 6 is set to the optical module 5 side to use the transmission line B for the transmission line. When each station other than the station 1000 receives the system switching instruction signal, each station detects the system switching instruction signal by the system switching instruction signal detecting circuit 9 and sets the changeover switch 6 to the optical module 5 side as in the case of 1000 to use. The transmission path is assumed to be a B system. Then the clock flows to the B system and
The system 1000 performs data transmission, but the receiving system 1B of the station 1000 has a fault. Therefore, in the station 1000, the transmission clock loss detection circuit 7 detects the clock loss. Then, an attempt is made to store in the self-station detected one-system fault storage circuit 10 by the signal line 106, but since the self-station detected one-system fault has already been stored, the signal line 107 is on and the gate circuit 13 is open, The signal passing through the signal line 106 passes through the gate circuit 13 and the signal line 108, and activates the optical module power control circuit 14. Upon receiving the signal 108, the optical module power supply control circuit 14 stops the power supply of the transmission units of the optical modules 4 and 5. Thereby, the station 6000 in FIG. 2 detects a transmission line clock cut in the B-system transmission line and performs a loopback operation. After that, the station 6000 sends a system switching instruction signal. Therefore, the used transmission path returns to the A-system, and this time, the station 2000 detects the clock cut of the A-system transmission path, and the station 2000 performs a loop-back operation. Thus, the network reconfiguration at the time of failure is completed.

[Effects of the Invention] As described above, according to the present invention, it is possible to reconfigure a loop network due to a fixed failure of two reception systems of the same station. Therefore, the loop network can be reconfigured not only when the station has two receivers, the connectors connected to the receivers, but also when the cable is fixed, or when the connectors are incorrectly connected due to the addition or removal of stations. Become. Therefore, in addition to automatically reconfiguring the network for failures during operation of the loop network, the network is automatically reconfigured even if a cable is incorrectly connected during construction such as adding or removing a station during operation. It is possible to significantly improve the reliability of the loop network.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example in a station in an embodiment of the present invention, FIG. 2 is a block diagram showing a dual loop network system for explaining the operation in the embodiment of the present invention, and FIG. FIG. 3 is a block diagram showing a double loop network using a book transmission line as an active system and a standby system.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-36104 (JP, A) JP-A-55-138944 (JP, A) JP-A-57-84645 (JP, A) JP-A-60-1985 136444 (JP, A) JP-A-62-32742 (JP, A) JP-A-63-266940 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 12/42-12 / 437 JICST file (JOIS) WPI (DIALOG)

Claims (1)

(57) [Claims] A plurality of stations are connected by a reverse double loop transmission line of a working system and a protection system, all the stations have oscillators, and an independent synchronization method for generating a transmission clock is performed by clock synchronization of the loop transmission line. In the data transmission system used in the system, each station has one of a working transmission unit and a receiving unit connected to the working loop and a protection transmitting unit and a receiving unit connected to the protection loop. A switch for switching between an operation state in which the transmission unit is connected to the inside and a bypass state in which the reception unit is connected to the transmission unit without connecting the other to the inside. A transmission clock disconnection detection circuit for detecting a clock abnormality, a self-station detected single-system failure storage circuit for storing the clock abnormality when the clock abnormality is detected, A system switching instruction signal generating circuit for transmitting a system switching instruction signal to the transmitting unit in the above-mentioned operating state when a lock abnormality is detected, and the above-mentioned switching switch when a system switching instruction signal is detected from the receiving unit in the above-mentioned operating state. Means for switching, and after sending the system switching instruction signal,
Means for switching the changeover switch; and a state in which the changeover switch is changed after the predetermined time, and a state in which the clock abnormality is stored in the self-station-detection one-system fault storage circuit. Means for stopping the operation of the active transmission unit and the standby transmission unit when an abnormality is detected; and, after switching the switch based on the system switching instruction signal, the transmission clock disconnection detection circuit. A means for switching the changeover switch to a loopback state in which the working transmission unit and the protection reception unit are internally connected when a clock abnormality is detected in the loop. method.