JP3255357B2 - Facility loopback method and optical transmission device in optical transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facility loopback method for isolating a failure in an optical transmission system in which a plurality of optical transmission apparatuses exist, and an optical transmission apparatus having a facility loopback function.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a part of an optical transmission system. FIG. 2 shows three optical transmission devices NE1, NE2, and NE3 connected by an optical fiber cable. Each of the optical transmission devices NE1, NE2, and NE3 performs bidirectional communication by, for example, a LAPD communication procedure. In addition, data transferred between the devices includes RSOH (Regene
rator section overhead), and RSOH includes Dcc (Data Communication Channel) as a control channel.
The communication method in which l) is defined is taken as an example. Note that RS
Dcc defined as OH is hereinafter referred to as Dccr.

FIG. 3 shows an optical transmission device NE1, NE2, NE
FIG. 3 is a block diagram showing a configuration of No. 3; In the figure, a signal input from an optical fiber cable 11 is converted into an electric signal by an optical-electrical converter 1 and converted into a serial-parallel
Is input to Parallel data from the serial-parallel converter 2 is input to the RSOH processing unit 3.

In the RSOH processing section 3, a frame synchronizing circuit 31 synchronizes frames, and a descrambler circuit 3
2 performs descrambling of data. The Dccr extraction circuit 33 extracts the Dccr included in the overhead part and outputs it to the Dccr communication protocol unit 4. The overhead terminating unit 34 extracts a portion other than Dccr in the overhead, and performs a process according to the extracted data. Then, the data portion other than the overhead in the received data is transferred to the block that processes the data portion.

[0005] RSOH is added to the data to be transmitted by an overhead insertion unit 51. In the RSOH portion, the Dccr output by the Dccr communication protocol unit 4 is set by the Dccr insertion unit 52. Thereafter, the data is scrambled by a scramble circuit 53, framed by a frame generation circuit 54, and output to the parallel-serial converter 6. The parallel-serial converter 6 converts the input data into a serial signal and outputs the serial signal to the electro-optical converter 7. The electro-optical converter 7 converts an input signal into an optical signal and sends it to the optical fiber cable 12.

When a fault occurs in a line, it is necessary to first specify where in the system the fault has occurred. Generally, each optical transmission device has a loopback function. As one of the loopback functions, there is a facility loopback that returns an input optical signal as it is. Therefore, when a failure occurs in a line, a facility loopback is performed in each optical transmission device. FIG.
As shown in (1), the facility loopback is executed by inputting the output of the serial-parallel converter 2 to the parallel-serial converter 6.

If the same signal as the transmission signal is returned by the facility loopback, it is confirmed that no fault has occurred on the path to the loopback point.
Therefore, by sequentially changing the loopback point, the location where the failure has occurred can be specified.

[0008]

However, when the above facility loopback is executed, Dc
The control message contained in cr is returned as it is. Therefore, a formal response message to the control message is not sent. LAPD two-way communication is established by exchanging a control message and a response message sequentially. However, if a facility loopback is performed, the exchange of the control message and the response message is not established. That is, the relationship between the control message and the response message is broken by the facility loopback, and thereafter, LAPD two-way communication cannot be performed. Therefore, in order to return to a state where communication can be performed when the facility loopback is performed, maintenance personnel must go to the loopback point and perform processing such as returning the device settings to the normal state, and analyze the line failure. There is a problem that it takes time and effort.

Accordingly, an object of the present invention is to provide a facility loopback method and an optical transmission apparatus in an optical transmission system capable of continuing LAPD communication even when performing a facility loopback.

[0010]

A facility loopback method in an optical transmission system according to the present invention extracts a region including a control message in received data, creates a response message to the control message, and generates a control message in the received data. It is configured to insert an area including the response message into data other than the area including the and wrap around.
Here, the area including the control message in the received data is, for example, RSOH.

[0011] An optical transmission apparatus according to the present invention comprises an overhead extracting means for extracting overhead in received data, an overhead inserting means for inserting overhead into transmission data, and a response to a control message included in the overhead extracted by the overhead extracting means. Communication control means for outputting a new overhead including a message to the overhead insertion means, and loopback means for returning data other than the area including the control message in the received data from the overhead extraction means to the overhead insertion means. Things. Here, the overhead extraction means is Dc
The overhead insertion unit inserts a new Dccr, and the loopback unit is configured to loop back data other than Dccr in the received data from the overhead extraction unit to the overhead insertion unit. May be used.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a facility loopback according to the present invention. In the figure, a signal input from an optical fiber cable 11 is converted into an electric signal by an optical-electrical converter 1 and is converted into a serial signal.
It is input to the parallel converter 2. The serial-parallel converter 2 converts input data into parallel data. Then, the parallel data from the serial-parallel converter 2 is input to the RSOH processing unit 3.

In the RSOH processing unit 3, a frame synchronizing circuit 31 synchronizes frames, and a descrambler circuit 3
2 performs descrambling of data. The Dccr extraction circuit 33 extracts the Dccr included in the overhead part and outputs it to the Dccr communication protocol unit 4.

When the execution of the facility loopback is instructed, the data after the Dccr extraction is sent from the Dccr extraction circuit 33 to the Dcr instead of the overhead terminal 34.
It is provided to the cr insertion section 52. The instruction to execute the facility loopback is included in, for example, overhead.
Therefore, if it is included in the Dccr, the Dccr communication protocol unit 4 determines whether or not to perform the facility loopback, and can perform control to switch the output destination of the data after the Dccr extraction from the Dccr extraction circuit 33. . The instruction to execute the facility loopback is Dc.
If it is included in overhead other than cr, Dc
It is determined whether or not a part that processes overhead other than cr performs a facility loopback, and when the facility loopback is performed, for example, control is performed so that the loopback is performed from the next frame.

The Dccr communication protocol unit 4
The control message contained in the ccr can be analyzed. Therefore, a response message to the control message can be created. Dccr including the response message is transmitted from Dccr communication protocol unit 4 to Dccr.
Output to the insertion unit 52.

Therefore, in this embodiment, the Dccr extraction circuit 33 is an implementation example of the overhead extraction means.
The ccr insertion unit 52 is an implementation example of an overhead insertion unit, and the Dccr communication protocol unit 4 is an implementation example of a communication control unit. Also, the loopback means is Dccr.
The data output destination other than
This is realized by a portion that switches to the ccr insertion unit 52.

The Dccr insertion unit 52 includes a Dccr extraction unit 3
The Dccr output by the Dccr communication protocol unit 4 is set to the data returned in step 3. Scramble circuit 5
3 scrambles the data created by the Dccr insertion unit 52 and outputs the data to the frame generation circuit 54. The frame generation circuit 54 converts the scrambled signal into a frame and outputs the frame to the parallel-serial converter 6. The parallel-serial converter 6 converts the input data into a serial signal and outputs the serial signal to the electro-optical converter 7. The electro-optical converter 7 converts an input signal into an optical signal and sends it to the optical fiber cable 12.

If the same signal (other than Dccr) as the transmission signal is returned, the side instructing the facility loopback can determine that no fault has occurred in the path to the loopback point. Moreover, in this case, a response message to the control message is transmitted. Therefore,
Even if the facility loopback is performed, the relationship between the control message and the response message does not collapse,
Thereafter, LAPD bidirectional communication can be performed.

[0019]

As described above, according to the present invention, a facility loopback method and an optical transmission apparatus in an optical transmission system extract an area including a control message in received data and create a response message to the control message. In addition, since the area including the response message is inserted into the data other than the area including the control message in the received data and is folded back, the communication protocol control portions in the respective optical transmission devices are in a state where data transmission and reception can be performed with each other. LAPD even if the facility loops back
There is an effect that communication can be continued.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a facility loopback according to the present invention.

FIG. 2 is a block diagram illustrating a part of the optical transmission system.

FIG. 3 is a block diagram illustrating a configuration of an optical transmission device.

FIG. 4 is a block diagram for explaining a conventional facility loopback.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical-electric converter 2 Serial-parallel converter 3 RSOH processing part 3 4 Dccr communication protocol part 6 Parallel-serial converter 7 Electric-optical converter 11,12 Optical fiber cable 31 Frame synchronization circuit 32 Scrambler circuit 33 Dccr Extraction circuit 34 Overhead termination unit 51 Overhead insertion unit 52 Dccr insertion unit 53 Scramble circuit 54 Frame generation circuit

Claims (4)

(57) [Claims] 1. A facility loopback method in an optical transmission system for performing a facility loopback of returning an input signal in an optical transmission system in which a plurality of optical transmission devices are present, the method comprising: Extracting a response message to the control message, inserting an area including the response message into data other than the area including the control message in the received data, and looping back the data. Method. 2. The facility loopback method in an optical transmission system according to claim 1, wherein the area including the control message in the received data is a regenerator section overhead. (3)Optical transmission system with multiple optical transmission devices
Facility loop bar that folds input signal in system
An optical transmission device having a locking function,  Sends and receives data with overhead added to the information part
Overhead extraction for extracting the overhead in the received data.
Output means and overhead insertion for inserting overhead into transmission data
Means included in the overhead extracted by the overhead extracting means.
Including a response message to the
Communication for outputting the overhead to the overhead insertion means.
An optical transmission device having control means, the data other than the area including the control message in the received data.
From the overhead extraction means to the overhead insertion
It is characterized by having loopback means to be folded back to the input means
Optical transmission device. 4. An overhead extracting means for extracting a data communication channel in a regenerator section overhead, an overhead inserting means for inserting a data communication channel in a regenerator section overhead, and a loopback means, 4. The data other than the data communication channel in the data is looped back from the overhead extracting means to the overhead inserting means.
An optical transmission device according to claim 1.