JPH10336079A - Transmission line changeover system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a wavelength multiplexer to be used continuously in a state that a fault continues by building up an inactive channel for a multiplex signal uninterruptibly on the occurrence of the fault in the wavelength multiplexer. SOLUTION: When an input section of a wavelength multiplexer with a wavelength λ1 sent from a transmitter side is faulty, an alarm detection circuit 51 detects the fault. When the circuit 51 detects the fault, an attenuator 53 limits an output power of the multiplex signal synthesized by a synthesizer 21. A demultiplexer 24 at a receiver side demultiplexes the multiplex signal and a wavelength selection filter 25 selects an optical signal for each wavelength. Since the power of the multiplex signal is decreased, the power of the optical signals with all wavelength bands λ1-λn after demultiplexing is decreased. Since the power of all optical signals is not more than a prescribed level, transmission channels are simultaneously switched on an uninterruptible path SW to build up a standby transmission channel for the multiplex signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength multiplexing system combining a wavelength multiplexing device for multiplexing a plurality of optical transmission devices by wavelength multiplexing and a hitless path switching device (hitless path SW). The present invention relates to a transmission line switching method for constructing a non-operating line of a multiplexed signal without an instantaneous interruption when a failure occurs on the wavelength multiplexing apparatus side and preventing continuous use of the multiplexed signal in a state where the failure has occurred.

[0002]

2. Description of the Related Art First, with reference to FIG. 2, a conventional wavelength multiplexing system will be outlined.

A wavelength division multiplexing system comprises a plurality of wavelength division multiplexing devices 1
The wavelength multiplexing device 11 is connected to the wavelength multiplexing device 12 via the system 0 transmission line, and the wavelength multiplexing device 13 is connected to the wavelength multiplexing device 14 via the system 1 transmission line. Each of the wavelength multiplexing devices 11 to 14 has the same configuration. For example, the wavelength multiplexing device 11 includes a multiplexer 21, a transmission side amplifier 22, a reception side amplifier 23, a demultiplexer 24, and a plurality of wavelength selection filters ( BPF) 25.

Further, the illustrated wavelength multiplexing system includes a plurality of non-interruptible path switching devices (non-interruptible path switches) 31 to 34, and as shown in FIG.
3 is connected to the wavelength multiplexing devices 11 and 13, and the hitless path switches SW32 and 34 are connected to the wavelength multiplexing devices 12 and 14 (in the illustrated example, two hitless path SWs are connected to each wavelength multiplexing device). Although an example of connection is shown, n (n is an integer of 2 or more) non-interruptible paths SW are actually connected to each wavelength multiplexing apparatus.

Now, it is assumed that the zero-system transmission line is selected by each uninterrupted path SW. Paying attention to the wavelength multiplexing device 11, the multiplexer 21 receives optical signals of different wavelengths from each other, multiplexes each optical signal, and outputs the multiplexed optical signal as a multiplexed optical signal. Then, the multiplexed optical signal is amplified by the transmission-side amplifier 22 and output to the system 0 transmission line as an output optical signal.

On the other hand, the wavelength multiplexing device 11 is
2 receives the output optical signal as an input optical signal, and amplifies the input optical signal by the receiving-side amplifier 23. The amplified input optical signal (multiplexed signal) is demultiplexed (separated) by the demultiplexer 24, and a signal having the wavelength selected by each wavelength selection filter 6 is output.

Now, assuming that n uninterruptible path switches SW are connected to the wavelength multiplexing apparatus 11, optical signals of wavelengths λ1 to λn are transmitted from the first to n-th uninterrupted path switches SW, respectively. You. The multiplexer 21 performs wavelength multiplexing on the wavelengths λ1 to λn, and the optical signal multiplexed on the wavelengths λ1 to λn is amplified in the optical output power by the transmission side amplifier 22 and transmitted to the transmission line. On the receiving side (wavelength multiplexing device 12), the optical multiplexed signal attenuated through the transmission path is amplified by the receiving side amplifier 23, and then the splitter 24 and the wavelength selection filter 2 are amplified.
5, wavelength separation of λ1 to λn is performed. Then, the output of the wavelength selection filter 25 is provided to the first to n-th uninterruptible path SW located on the receiving side.

[0008]

In each of the uninterrupted paths SW located on the downstream side, path switching is independently performed based on the separated signals. If there is a failure, one uninterrupted path SW selects the 0-system transmission path and another uninterrupted path SW selects the 1-system transmission path. That is, there is a case where both the 0-system and 1-system transmission lines become active. When performing maintenance work, if the cause of the failure is on the wavelength multiplexing equipment side, all the uninterruptible path SWs are artificially and simultaneously forcedly switched so that the working line is not affected, and then the maintenance work is performed. Need to do.

An object of the present invention is to provide a transmission line switching system in which both the 0-system and 1-system transmission lines do not become working transmission lines.

[0010]

According to the present invention, there are provided a first transmission line and a second transmission line, wherein the first transmission line is a working transmission line and the second transmission line is a standby transmission line. Receiving a plurality of optical signals of different wavelengths on the transmitting side, multiplexing the plurality of optical signals and sending them to the receiving side as a multiplexed signal, and demultiplexing the multiplexed signal on the receiving side to separate the plurality of optical signals. Used in a transmission system adapted to obtain, detecting means for detecting an abnormality of each of the plurality of optical signals on the transmission side and transmitting an abnormality signal when at least one has an abnormality, and responding to the abnormality signal. Attenuating means for reducing the output level of the multiplexed signal, and on the receiving side, when the plurality of optical signals are equal to or less than the predetermined value, each of the first and second transmission lines transmits a protection transmission signal. Switching means for switching between the transmission line and the working transmission line Is the transmission line switching method is obtained, characterized in that is. And the detecting means is, for example,
A plurality of detectors each of which detects an abnormality for each of the plurality of optical signals and outputs a failure signal, and an OR circuit which is connected to the plurality of detectors and outputs the abnormality signal when receiving at least one of the failure signals; have.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, in the example shown in FIG.
For the same components as the wavelength division multiplexing system shown in
The same reference numerals are given and the description is omitted.

The illustrated wavelength multiplexing system includes a plurality of wavelength multiplexing devices 41 to 44. The wavelength multiplexing device 41 is connected to a wavelength multiplexing device 42 via a 0-system transmission line, and the wavelength multiplexing device 43 is connected to a 1-system. It is connected to a wavelength multiplexing device 44 via a transmission line. Each of the wavelength multiplexing devices 41 to 44 has the same configuration. For example, the wavelength multiplexing device 41 includes a multiplexer 21, a transmission side amplifier 22, a reception side amplifier 23, and a demultiplexer 2.
4 and a plurality of wavelength selection filters (BPFs) 25. Further, the wavelength multiplexing device 41 includes a plurality of alarm detection circuits (ALM) 51, an OR circuit (OR) 52, and an attenuator (ATT) 53.

The illustrated wavelength division multiplexing system includes a plurality of non-interruptible path switching devices (non-interruptible path switches) 31 to 34. As shown in FIG. 13 and the uninterrupted path SW32
And 34 are connected to the wavelength multiplexing devices 12 and 14 (in the illustrated example, two uninterrupted paths S
Although an example in which W is connected is shown, n (n is an integer of 2 or more) non-interruptible paths SW are actually connected to each wavelength multiplexing apparatus.

In the wavelength division multiplexing system shown in FIG. 1, before the optical signals of a plurality of different wavelengths transmitted from the uninterrupted path SW on the transmission side are input to the multiplexer 21, the respective alarm detection circuits 51
Monitor by. Then, the monitoring result of each alarm detection circuit 51 is input to the OR circuit 52. If the monitoring result of any of the alarm detection circuits 51 is abnormal, the OR circuit 52 outputs, for example, an abnormal signal (high-level signal). Then, this abnormal signal is given to the attenuator 53.

The multiplexed signal multiplexed by the multiplexer 21 is amplified by the transmission-side amplifier 22 and then transmitted to the transmission line via the attenuator 53. When the attenuator 53 receives an abnormal signal, the multiplexed signal is multiplexed. Output signal power. That is, for example, the attenuation amount of the 0 system is controlled.

On the receiving side, the multiplexed input signal is amplified by the receiving side amplifier 23 and then separated by the demultiplexer 24. Then, the separated signals are selected by the wavelength selection filter 25, and the signals of each wavelength are output to the hitless path SW.

Now, assuming that an optical signal of the wavelength λ1 on the transmitting side causes a failure at the input section of the wavelength multiplexing apparatus, an abnormality is detected by one of the alarm detection circuits 51 (referred to as the alarm detection circuit 51 of the wavelength λ1). Is done. Alarm detection circuit 51 of wavelength λ1
Is monitored via the OR circuit 52.
Will be given to

The multiplexed signal multiplexed by the multiplexer 21 is amplified by the transmission-side amplifier 22, but has a wavelength λ1.
Since the optical signal has a failure, the attenuation of the attenuator 53 is controlled, the output power of the multiplexed signal is reduced, and the multiplexed signal is transmitted to the transmission line.

On the receiving side, the multiplexed input signal is applied to a duplexer 24 via a receiving-side amplifier 23, where it is split. Then, the separated signals are respectively selected by the wavelength selection filter 25 and given to the hitless path SW as described above.

At this time, as described above, since the power of the multiplexed input signal is reduced, all the wavelengths λ1
That is, the power of .about..lambda.n is also reduced. Therefore,
Even at a wavelength other than the wavelength λ1 in which the failure occurred, the instantaneous uninterrupted path SW
Can switch all at once, and construct a spare transmission line for multiplexed signals. That is, the system is simultaneously switched from system 0 to system 1.

[0022]

As described above, according to the present invention, a wavelength multiplexing device for multiplexing a plurality of optical transmission devices by wavelength multiplexing,
In a wavelength division multiplexing system combined with an uninterrupted path switching device (uninterrupted path SW), when a failure occurs on the wavelength multiplexing side, a non-operational line of a multiplexed signal can be constructed without an instantaneous interruption. Recovery can be performed promptly, and an unstable one-system operation state can be avoided in a shorter time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a transmission line switching system according to the present invention.

FIG. 2 is a block diagram for explaining a conventional transmission path switching method.

[Description of Signs] 21 Multiplexer 22 Transmitting Amplifier 23 Receiving Amplifier 24 Demultiplexer 25 Wavelength Selection Filter (BPF) 51 Alarm Detection Circuit (ALM) 52 OR Circuit (OR) 53 Attenuator (ATT) 31-34 None Instantaneous interruption path SW

Claims (3)

[Claims] A first transmission path including a first transmission path and a second transmission path;
The transmission line is used as a working transmission line, and the second transmission line is used as a protection transmission line. The transmission side receives a plurality of optical signals of different wavelengths, multiplexes the plurality of optical signals, and multiplexes them as a multiplexed signal to the reception side. The transmitting side is used in a transmission system in which the multiplexed signal is demultiplexed on the receiving side to obtain the plurality of optical signals, and the transmitting side detects an abnormality of each of the plurality of optical signals and detects at least one of the plurality of optical signals. Detecting means for transmitting an abnormal signal when there is an abnormality, and attenuating means for reducing the output level of the multiplexed signal in response to the abnormal signal; A transmission line switching method for switching the first and second transmission lines to a standby transmission line and an active transmission line, respectively, when the value is equal to or less than 2. The transmission line switching system according to claim 1, wherein the transmitting side multiplexes the plurality of optical signals into a multiplexed signal, and amplifies the multiplexed signal to form a multiplexed signal. A transmitting side amplifier for transmitting to the working transmission line, the receiving side receiving the multiplexed signal via the working transmission line, amplifying the multiplexed signal to form an amplified multiplexed signal. Transmission path switching comprising: an amplifier; a demultiplexer for separating the amplified multiplexed signal into the plurality of optical signals; and a wavelength selection filter for selecting the plurality of optical signals according to wavelength. method. 3. The transmission line switching system according to claim 1, wherein said detection means detects an abnormality for each of said plurality of optical signals and outputs a failure signal, respectively, and said plurality of detection means. A transmission line switching system, comprising: an OR circuit that is connected to a device and outputs the abnormal signal when receiving at least one of the fault signals.