JP3324970B2 - Optical path signal terminal equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SDH (Synchronous
The present invention relates to a technology for accommodating a signal in an optical path network. In particular, it relates to signal conversion between an SDH signal transmitted at an electrical level and an optical path signal transmitted at an optical level.

[0002]

2. Description of the Related Art The development of wavelength division multiplexing (WDM) technology, which makes full use of the broadband characteristics of light, and an optical path network in which wavelength routing is introduced into a path layer have been actively developed. Existing SDH network, ATM network, PDH
(Asynchronous digital hierarchy, Presiochronous Did
ital Hierachy)
Since the DH network is being replaced with the SDH network, and the ATM network is mainly based on the SDH-based ATM system for accommodating cells in the SDH path, it is important to accommodate the SDH signal in the optical path network.

FIG. 13 is a diagram for briefly explaining a conventional switching network for connecting subscriber terminals. The subscribers 11 and 18 are connected via an exchange (SW) 12, a transit exchange (SW) 13, transmission terminal stations (LTs) 14, 15, a transit exchange (SW) 16, and an exchange (SW) 17. The subscriber 11 and the exchange 12 and the exchange 17 and the subscriber 18 are connected by a line of, for example, 64 kb / s, and are connected between the exchange 12, the transit exchange 13 and the transmission terminal 14, and the transmission terminal 15 respectively. Between the transit exchange 16 and the exchange 17 is, for example, 52 Mb obtained by time-division multiplexing a 64 kb / s line.
It is connected by an it / s path. Transmission terminal stations 14, 15
In between, this path is further multiplexed and transmitted.

FIG. 14 is a diagram for explaining path connection of an SDH signal via an SDH path cross-connect. Each of the transit exchanges (SW) 21-1 to 21-4 is a transmission terminal station (L
T) 22-1 to 22-4 and 23-1 to 23-4 are connected to the SDH path cross connect (XC) 25. FIG. 14 shows one path between each of the transit switches 21-1 and 21 to 21-4. Transmission terminal station 22-1
Transmission between 22-4 and 23-1 to 23-4 is performed by a time-division multiplexed path, and the SDH path cross-connect 2
5, the path of each path is set.

FIG. 15 is a diagram for explaining an example of a configuration in which the path connection shown in FIG. 14 is realized by an optical path network. In this case, instead of the transmission terminal station, the optical path terminal stations 26-1 to 26-
3 are used, and the optical path terminal stations 26-1 to 26-3 are connected to the optical path cross-connect 2 via the wavelength division multiplex link.
7 is connected. An optical path is arbitrarily set between the optical path terminal stations 26-1 to 26-3 and accommodated in a wavelength division multiplex link using a wavelength division multiplexing technique (for such an optical path network, for example, Literature: Kenichi Sato, Satoshi Okamoto, "Development of Optical Path Layer Technology", 1992 IEICE Autumn Conference SB-7-1, detailed in September 1992).

[0006] The optical path signal is composed of a main signal and an optical path monitoring signal. The optical path monitor signal includes an optical path monitor signal multiplexed at the electrical level in the same frequency band as the main signal (mainly used for monitoring the quality of the main signal) and an optical path monitor signal multiplexed at a frequency band different from the main signal. Multiplexed optical path monitoring signals (mainly used for management and identification of main signal type) are used (Reference: Satoru OKAMOTO, Kimio OG)
UCHI, and Kenichi SATO, "Network architecture and
management concepts for optical transportnetwork
s ", Procceedings on IEEE / IFIP 1996 Network Operati
ons and Managements Symbosium (NOMS'96), pp.1-111,199
April 2006, see Japanese Patent Application No. 8-49751, "Wavelength multiplexing optical communication monitoring method."

As described above, when an optical path signal is wavelength-multiplexed and transmitted through a wavelength division multiplexing link, the optical path monitoring signal and the wavelength division multiplexing optical path monitoring signal included in a partial area of the optical path signal are converted. Transmitted together. The optical path monitoring signal and the wavelength multiplexing optical path monitoring signal are monitored, and if a failure occurs in an optical fiber or a transmission device, the optical path is reestablished as a route that bypasses the failure location to recover from the failure. Done.

Next, the SDH transmission system will be described.
In the SDH transmission method, information is transferred in units of VCs (Virtual Containers) configured by a payload for transmitting information and a path overhead added to the payload. When a VC signal is accommodated in a transmission medium such as an optical fiber, a synchronous transfer module (Synchronous transfer module) is used.
A frame called a Transfer Module (hereinafter referred to as STM) is formed. First, a pointer (AU pointer: Ad) for managing a difference in frame phase between the STM signal and the VC signal.
(Ministrative Unit Pointer) is added to the VC signal, and then time division multiplexing is performed to generate an AU signal. An STM-N signal is generated by time-division multiplexing N AU signals and adding a section monitoring signal. This STM-N signal is sent to an optical fiber after being subjected to electro-optical conversion. At the receiving end, the reverse process is performed (reference: "SDH").
Transmission method, see Ohm, ISBN4-274-03430-5). S
When wavelength-division-multiplexed transmission of a DH signal is performed, a plurality of STM-
The N signals are converted into optical signals of different wavelengths and transmitted.

[0009] When a failure occurs in the transmission medium or the transmission device, the VC is re-edited to a route that bypasses the failure location, thereby recovering the failure. At this time, the terminal device at the fault end generates a signal in which all bits of the STM-N signal and the VC signal have a logical value of "1", and performs processing for retaining the frame phase in place of the lost signal. It is prescribed to do. In this case, since the SDH path monitoring signal of the VC does not have a valid value, a failure in units of a VC is detected, and a bypass operation of the VC is performed.

A conventional signal format for accommodating an SDH signal in an optical path network will be described with reference to FIGS. 16 shows a VC signal, FIG. 17 shows an STM-N signal, FIG. 18 shows an AU signal, and FIG. 19 shows an optical path signal. In the formats shown in these figures, the horizontal axis takes time, and time elapses from left to right. Signals are read out in the vertical direction with the upper left of the figure as the starting point and the lower right of the figure as the ending point (hereinafter, the drawing showing the signal format follows the drawing).

The VC signal has a VC-
11, VC-12, VC-2, VC-3, VC-4, V
Different formats are defined such as C-4-4c and VC-4-16c. FIG. 16 shows that VC-
4 shows a signal format. VC-4 is 260 × 9
It consists of a byte payload area P and a 9-byte path monitoring signal area PO. The STM-N signal is a signal in which such a VC signal is multiplexed, and as shown in FIG. 17, a 9 × (261 × N) byte payload area,
3 × (9 × N) byte section monitoring signal area S1,
It has a section monitor signal area S2 of 5 × (9 × N) bytes and an AU pointer area a of 1 × (9 × N) bytes.

[0012]

A conventional optical path signal and S
The signal format is different from the STM-N signal in the DH transmission method. Therefore, when transferring an SDH signal through an optical communication network, it is necessary to convert the SDH signal format into the optical path signal format.

In particular, when an STM-N signal is accommodated in an optical path, an optical path monitoring signal area is provided and an optical path monitoring signal is inserted therein as shown in FIG. It is necessary to increase the transmission speed.

Further, when a failure occurs in the optical communication network, both a failure recovery operation by a detour operation of an optical path in the optical communication network and a failure recovery operation by a detour operation of a VC signal in SDH operate. As a result, there is a problem that required network resources increase.

It is an object of the present invention to provide an optical path signal terminal device capable of inserting an optical path monitoring signal without increasing the signal length. I do.

[0016]

A first aspect of the present invention is an optical path signal terminal used as a transmitting end of an optical path terminal, wherein one or a plurality of SDs transmitted by an electric signal are transmitted.
An electric signal terminating means for terminating the H signal and outputting an electric signal for transmission to an optical path; inserting an electric level optical path monitoring signal into the electric signal; converting the obtained signal into an optical signal; in the optical path signal terminal station device provided with a light path termination means for outputting as an optical path signal an optical path termination means,
It is characterized by including means for inserting an optical path monitoring signal instead of the SDH section monitoring signal included in the SDH signal.

The electric signal terminating means includes means for processing an SDH section monitoring signal included in the SDH signal, and a plurality of VHs for demultiplexing the SDH signal processed by this means.
A multiplexing / demultiplexing means for converting the multiplexed signal into a C signal, a plurality of VC signals output from the multiplexing / demultiplexing means, and adding an AU pointer to convert the signal into an AU signal,
Multiplexing means for further multiplexing the signal and outputting an electric signal in the form of an optical path signal, wherein the means for inserting the optical path monitor signal of the electric level in a predetermined area of the electric signal in the form of the optical path signal. Good to insert. In particular, it is preferable to insert an optical-level optical path monitoring signal into an area corresponding to the area of the SDH section monitoring signal in the SDH signal format (referred to as “section overhead”) for the electrical signal in the optical path signal format.

A plurality of optical path terminating means are provided, a multiplexing means is provided corresponding to each of the plurality of optical path terminating means, and a switch circuit for switching and connecting signals between the multiplexing means and the demultiplexing means is provided. Can be. It is also possible to provide a plurality of multiplexing means and a plurality of optical path terminating means, and to provide a switch circuit for exchanging and connecting signals between the output of the multiplexing means and the input of the optical path terminating means.

Preferably, the optical path terminating means includes means for adding an optical path monitoring signal having a different optical level from the electrical level optical path monitoring signal to the optical path signal. This adding means may be configured to perform wavelength division multiplexing of the optical path signal and the optical level monitoring signal at the optical level, or may be configured to apply modulation different from the main signal to the optical path signal.

A second aspect of the present invention is an optical path signal terminal device used as a receiving end of an optical terminal, the optical path terminating means for receiving an optical path signal and converting the signal into an electric signal, The electric signal output from the termination means is converted to one or a plurality of SDs.
In the optical path signal terminal station device provided with an electrical signal termination means for converting the H signal, the optical path signal is a signal of SDH section does not include the monitor signal format of an SDH signal, an electrical signal termination means And a means for inserting an SDH section monitoring signal in place of the optical path monitoring signal included in the optical path signal received by the optical path terminating means.

The optical path terminating means includes means for converting an optical path signal into an electric signal, and then extracting an optical path monitoring signal having an electric level added to a predetermined area of the electric signal. Multiplexing / demultiplexing means for demultiplexing an electric signal output from the optical path terminating means and converting it into a plurality of VC signals, and multiplexing the plurality of VC signals output from the demultiplexing means and adding an AU pointer to the AU. It is preferable to include a multiplexing means for converting the signal into a signal and a means for adding an SDH section overhead to the AU signal output from the multiplexing means.

The optical path signal is added with an electrical level optical path supervisory signal in the area of the SDH section supervisory signal in the SDH signal format, and the optical path terminating means includes an optical path signal containing the electrical level optical path supervisory signal. And an electrical signal terminating means for demultiplexing the electrical signal output from the optical path terminating means, including the electrical level optical path monitoring signal, and converting the signal into a plurality of VC signals. Means for rewriting the area of the SDH section monitor signal included in the plurality of VC signals output by the demultiplexing means, and multiplexing the output of the rewriting means to AU
A multiplexing unit for converting the AU signal into an AU signal by adding a pointer, and a unit for adding an SDH section monitoring signal to the AU signal output from the multiplexing unit may be included.

A plurality of optical path terminating means are provided, a multiplexing / demultiplexing means is provided for each of the plurality of optical path terminating means, and a switch for switching and connecting a signal between the multiplexing / demultiplexing means and the multiplexing means. A circuit can be provided.
A plurality of optical path terminating means and a plurality of demultiplexing means are provided,
A switch circuit for exchanging signals between the outputs of the plurality of optical path terminating means and the inputs of the plurality of demultiplexing means may be provided.

The optical path terminating means may include means for separating an optical path monitoring signal having a different optical level from the optical level monitoring signal from the optical path signal.

The optical path terminal station includes a plurality of optical path signal terminal apparatuses for the transmitting end described above.
Optical carrier waves having different wavelengths are assigned to the terminal equipment,
It is possible to provide a wavelength multiplexing means for wavelength division multiplexing the output optical signals of these optical path signal terminal equipments and sending them to the optical transmission line. Also, a plurality of optical path signal terminal devices for the receiving end described above are provided, and optical carrier signals having different wavelengths are allocated to the respective optical path signal terminal devices, and a wavelength multiplexed optical signal from the optical transmission line is separated. Wavelength separation means for outputting the signal to each optical path signal terminal device.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) The configuration of the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing an optical path signal terminal device according to a first embodiment of the present invention, and FIG. 2 is a diagram showing a format of an optical path signal.

This embodiment is used as a transmitting end of an optical path terminal, and transmits one or more SDs transmitted by an electric signal.
In order to output an electric signal for terminating the H signal and sending the signal to the optical path, input lines 111 to 1 from which the SDH signal arrives
14, an SDH section monitoring signal processing circuit 121 to 124 for terminating the SDH signal and processing an SDH section monitoring signal included in the SDH signal. Separation circuits 131 to 134 for converting into VC signals of
A plurality of VC signals output from the separation circuits 131 to 134 are multiplexed and converted into an AU signal by adding an AU pointer, and the obtained plurality of AU signals are further multiplexed.
A multiplexing circuit 141 that outputs an electric signal in an optical path signal format is provided. Also, a first optical path monitoring signal insertion circuit 211 for inserting an electrical level optical path monitoring signal in place of the SDH section monitoring signal included in the SDH signal in order to convert the electric signal into an optical signal and output the signal, An electro-optical conversion circuit 212 for converting an electric signal in an optical path signal format to which an optical path monitoring signal of an electric level is added into an optical signal, and an optical path monitoring signal of an optical level different from the electric level optical path monitoring signal; Second optical path monitoring signal insertion circuit 21 added to optical path signal
3, the first and second optical path monitoring signal insertion circuits 21
1 and 213 for controlling addition and multiplexing of an optical path monitoring signal.

The SDH signal (STM-N signal) input to the SDH signal input lines 111 to 114 is composed of 9 × (270 × N) bytes of data as shown in FIG. , Section monitor signal area S1 (3 ×
(9 × N) bytes), section monitor signal area S2 (5
× (9 × N) bytes), AU pointer area a (1 × (9
× N) bytes), payload area P (9 × (261 ×
N) bytes). The SDH section monitoring signal processing circuits 121 to 124 read data in the section monitoring signal areas S1 and S2 and perform necessary processing. This process is described in the ITU-T Recommendation
G.708 "Network node interface for the synch- ronou
s digital hierachy ".

SDH section monitor signal processing circuit 121
The SDH signal processed by the.
To 134. In the separation circuits 131 to 134,
The STM-N signal is separated into N signals, and only the payload area (VC signal) P (9 × 261 bytes) is extracted and output. In the illustrated example, the SDH signal input lines 111 to
The STM-4 signal is input to each of 114 and the separation circuit 1
At 31 to 134, four payload signals (VC signals) are output.

The payload signals separated by the separation circuits 131 to 134 are input to a multiplexing circuit 141. The multiplexing circuit 141 adds AU to the input 16 payload signals.
Add a pointer. The format of the signal to which the AU pointer is added (AU signal) is as shown in FIG.
It is composed of four areas: an undefined area U1, an undefined area U2, an AU pointer area a, and a payload area P. Further, the multiplexing circuit 141 performs byte interleave multiplexing processing on the 16 AU signals.

The output of the multiplexing circuit 141 is input to the optical path monitoring signal insertion circuit 211. Optical path monitoring signal insertion circuit 2
11 is an optical path monitoring signal control device 21
4 is inserted. The signal into which the optical path monitoring signal is inserted is transmitted to the electro-optical conversion circuit 21.
At 2, the electric signal is converted into an optical signal. The optical path monitor signal insertion circuit 213 inserts the optical path monitor signal sent from the optical path monitor signal controller 214 into this optical signal.

As shown in FIG. 2, the optical path signal output from the optical path monitoring signal insertion circuit 211 is composed of four areas: an optical path monitoring signal area O1, O2, an AU pointer area a, and a payload area P. You. The multiplex number N is 16 in this example.

In this embodiment, as the multiplexing circuit 141, S
A circuit for multiplexing DH signals is used. Therefore, the format of the optical path signal is also the same as that of the SDH section monitor signal except that the optical path monitor signal is inserted instead of the SDH section monitor signal.
It has the form of an H signal. When another format is used as the multiplexing format by the multiplexing circuit 141, the present invention can be similarly implemented using a signal format corresponding to the other format. The important point is that an optical path monitoring signal is inserted instead of the SDH section monitoring signal.

The electro-optical conversion circuit 212 can variably set the wavelength of an output optical signal, and can be realized by, for example, a variable wavelength laser. Further, the wavelength of the output optical signal can be fixed.

The insertion of the optical path monitoring signal at the optical level by the optical path monitoring signal insertion circuit 213 may use an optical signal having a wavelength different from the wavelength of the main signal. Modulation may be applied. Such an example is shown in FIGS. In the configuration example shown in FIG.
11 generates a continuous light, and outputs the continuous light to an optical modulator 31.
2 modulates with the main signal. In this case, an optical path monitoring signal at an optical level can be added by superimposing the optical path monitoring signal on the drive signal input to the laser diode 311. In the configuration example shown in FIG. 4, the laser diode 313 is directly modulated by the main signal. Also in this case, by superimposing the optical path monitoring signal at the optical level on the drive signal input to the laser diode 313, the optical path monitoring signal at the optical level can be added.

FIG. 5 is a block diagram showing an optical path signal terminal apparatus according to a second embodiment of the present invention. This embodiment is different from the first embodiment in that a switch circuit 611 is added to the first embodiment.
The editing of the H signal is performed.

SDH signal input lines 111-114, SDH
The operations of the section monitor signal processing circuits 121 to 124 and the separation circuits 131 to 134 are common to the first embodiment of the present invention.

The payload signals (VC signals) output from the separation circuits 131 to 134 have their spatial positions interchanged by the switch circuit 611. In this embodiment, a 16 × 16 switch is used, and 16 VC signals can be freely distributed to both the multiplexing circuit 621 and the multiplexing circuit 622.

The multiplexing processing is performed by the multiplexing circuits 621 and 622 on the payload signal distributed by the switch circuit 611. The multiplexing circuits 621 and 622 add AU pointers to the eight input payload signals. further,
The multiplexing circuits 621 and 622 perform byte interleave multiplexing processing on the eight AU signals.

The outputs of the multiplexing circuits 621 and 622 are sent to the transmitting end optical path signal terminating circuits 631 and 632, respectively.
The transmission end optical path signal termination circuits 631 and 632 respectively
The multiplexing circuit 6 includes the optical path monitoring signal insertion circuit 211, the electro-optical conversion circuit 212, the optical path monitoring signal insertion circuit 213, and the optical path monitoring signal control device 214 shown in the first embodiment.
21 and 622, the output of the optical path monitoring signal at the electrical level is inserted into the output, the electrical-optical conversion, and the processing of the addition of the optical path monitoring signal at the optical level are performed. .

As described above, it is possible to configure an optical path signal terminal device that can separate an SDH signal into a VC signal and provide an editing function at a VC signal level. Thus, when a failure occurs in the optical path signal output line 641 or 642, the transmission path of the optical path signal can be quickly switched.

FIG. 6 is a block diagram showing an optical path signal terminal equipment according to a third embodiment of the present invention. This embodiment uses VC
An editing process is performed by the switch circuit 711 after signal multiplexing, so that the optical path terminal device is configured using small switches.

SDH signal input lines 111-114, SDH
The operations of the section monitoring signal processing circuits 121 to 124 and the separation circuits 131 to 134 are common to those of the first embodiment.

The payload signals (VC signals) output from the separation circuits 131 to 134 are combined with the multiplexing circuits 621 and 622.
Is subjected to multiple processing. In the multiplexing circuits 621 and 622,
An AU pointer is added to the eight input payload signals. Further, in the multiplexing circuits 621 and 622, eight A
The U signal is byte-interleaved multiplexed.

The signals multiplexed by the multiplexing circuits 621 and 622 are switched in spatial position by the switch circuit 711. The switch circuit 711 does not perform the switching operation on the VC signal, but performs the switching operation on the output signals of the multiplexing circuits 621 and 622.
11 is different.

The output of the switch circuit 711 is sent to the transmitting end optical path signal terminating circuits 631 and 632. The transmitting end optical path signal terminating circuits 631 and 632 are respectively the first optical path monitoring signal inserting circuit 211, the electro-optical conversion circuit 212, the second optical path monitoring signal inserting circuit 213 and the second optical path monitoring signal inserting circuit 213 shown in the first embodiment.
An optical path monitoring signal control device 214 is provided, and the switch circuit 7
Each of the outputs of 11 performs an insertion process of an optical path monitoring signal at an electrical level, an electro-optical conversion, and an addition of an optical path monitoring signal at an optical level, and outputs the optical path signal to optical path signal output lines 641 and 642 as optical path signals.

In this embodiment, a 2 × 2 switch is used as the switch circuit 711 and the SDH signal input line 11
A function of freely distributing the group of SDH signals input from the SDH signal input lines 113 and 114 and the group of SDH signals input from the SDH signal input lines 113 and 114 to two optical path signal output lines 641 and 642 is provided. . As the switch circuit 711, a switch having a larger size can be used as the number of SDH signal input lines and optical path signal output lines increases. Even in that case, a switch having a smaller number of inputs and outputs than the switch circuit 611 used in the second embodiment of the present invention can be applied.

FIG. 7 is a block diagram showing an optical path signal terminal apparatus according to a fourth embodiment of the present invention.
An example of the configuration of an optical path signal terminal device at a receiving end that converts the signal into a signal and outputs the signal is shown.

The optical path signal terminal equipment includes an optical path monitoring signal extracting circuit 812 for separating an optical level optical path monitoring signal from an optical path signal, and an opto-electrical conversion circuit for converting the optical path signal into an electric signal. 813; an optical path monitoring signal extracting circuit 814 for extracting an optical path monitoring signal of an electrical level from the optical path signal converted into an electrical signal; and an optical path for processing two optical path monitoring signals of an optical level and an electrical level Monitor signal control device 815 and optical path monitor signal extraction circuit 81
4 for demultiplexing and converting the electric signal output from the P.4 into a plurality of VC signals, and multiplexing the plurality of VC signals output from the separation circuit 911 and adding an AU pointer to convert the signal into an AU signal. Multiplexers 921 to 924
And SDH section monitoring signal insertion circuits 931 to 934 which insert SDH section monitoring signals into AU signals output from the multiplexing circuits 921 to 924 and output the SDH section monitoring signals to SDH signal output lines 941 to 944.

The optical path monitor signal extracting circuit 812 responds to the optical path signal input from the optical path signal input line 811
The optical path monitor signal superimposed at the optical level is demodulated. This demodulation process separates the wavelength when the optical path supervisory signal is wavelength-multiplexed with the optical path signal, and branches the optical signal when the optical path supervisory signal is superimposed with modulation different from the optical path signal. And then do it. Thereby, the optical path monitoring signal can be demodulated without destroying the payload area serving as the main signal. The demodulated optical path monitor signal is sent to the optical path monitor signal controller 815.

The photoelectric conversion circuit 813 converts the optical path signal processed by the optical path monitoring signal extracting circuit 812 into an electric signal.

The optical path monitor signal extracting circuit 814 extracts the optical path monitor signals in the optical path monitor signal areas O1 and O2 shown in FIG. 2 from the electric signal output from the photoelectric converter 813, and controls the optical path monitor signal. Send to device 815. The extracted optical path monitoring signal areas O1 and O2 are in an undefined state, and may be any data.

The separating circuit 911 separates the payload area of the signal from the optical path monitoring signal extracting circuit 814 and outputs the separated signal as an individual VC signal. In this example, the separation circuit 911
Are converted into 16 VC signals.

Each of the multiplexing circuits 921 to 924 converts a plurality of (in this case, four) VC signals from the separation circuit 911 into AU signals by performing multiplexing processing and adding an AU pointer. Furthermore, the data is output after being subjected to byte interleave multiplexing processing.

SDH section monitor signal insertion circuit 931
934 add an SDH section monitor signal to each output of the multiplexing circuits 921 to 924, and output them to the SDH signal output lines 941 to 944 as SDH signals. In this embodiment, an SDH signal with N = 4 in the STM-N signal format shown in FIG. 17 is output.

FIG. 8 is a block diagram showing an optical path signal terminal apparatus according to a fifth embodiment of the present invention. In this embodiment, two optical path signal input lines 1011 and 1012, an optical path monitoring signal extracting circuit 812, an optical-electrical conversion circuit 813,
It includes two receiving-end optical path signal terminating circuits 1021 and 1022 each including an optical path monitoring signal extracting circuit 814 and an optical path monitoring signal control device 815, and two separating circuits 1031 and 1032 each equivalent to the separating circuit 911. The fourth embodiment is different from the fourth embodiment in that a switch circuit 1041 for enabling the editing of the SDH signal converted from the optical path signal is provided.

The receiving end optical path signal terminating circuits 1021, 10
22 and the operations of the separation circuits 1031 and 1032 are common to those of the fourth embodiment. The spatial position of the VC signal output from the separation circuits 1031 and 1032 can be switched by the switch circuit 1041. In this embodiment, a 16 × 16 switch is used, and 16 VCs are used.
The signal can be freely distributed to the multiplexing circuits 921 to 924.

V distributed by the switch circuit 1041
The C signal is supplied to the multiplexing circuits 921 to 924 as in the fourth embodiment.
Are subjected to a process of adding an SDH section monitor signal in SDH section monitor signal insertion circuits 931 to 934, and then output from SDH signal output lines 941 to 944.

As described above, the optical path signal is separated into the VC signal, and the optical path signal terminal device capable of providing the editing function at the VC signal level can be constituted.

FIG. 9 is a block diagram showing an optical path signal terminal equipment according to a sixth embodiment of the present invention. This embodiment uses VC
By performing editing processing in the switch circuit 1111 before separation into signals, an optical path terminal device is configured using small switches.

The operations of the optical path signal input lines 1011 and 1012 and the receiving end optical path signal termination circuits 1021 and 1022 are the same as those of the fifth embodiment.

Receiving end optical path signal terminating circuits 1021, 10
In the signal output from 22, the switching of the spatial position is performed by the switch circuit 1111. In this embodiment, a 2 × 2 switch is used as the switch circuit 1111, and the optical path signal input from the optical path signal input line 1011 and the optical path signal input from the optical path signal input line 1012 are converted into two SDHs. Signal output line group (SDH signal output lines 941, 9
42 and the SDH signal output lines 943, 944).

The switch circuit 1111 separates the separation circuit 103
1, 1032 are converted to VC signals. The VC signal is subjected to multiplexing processing by multiplexing circuits 921 to 924, and SDH section monitoring signal inserting circuits 931 to 93
After receiving the process of adding the SDH section monitoring signal in step 4, the signal is output from the SDH signal output lines 941 to 944.

FIG. 10 is a block diagram showing an optical path signal terminal equipment according to a seventh embodiment of the present invention. This embodiment is different from the fourth embodiment in that the SDH path monitor signal rewriting circuits 1211 to 12
26 enables flexible network operation.

The optical path signal input line 811, the optical path monitoring signal extracting circuit 812, the photoelectric conversion circuit 813, the optical path monitoring signal extracting circuit 814, and the optical path monitoring signal controller 815.
The operations of the receiving end optical path signal terminating circuit 821 and the separating circuit 911 are the same as those of the fourth embodiment.

The 16 VCs output from the separation circuit 911
The signals are sent to the SDH path monitor signal rewriting circuit 1211, respectively.
To 1226. In this application, VC-3, VC-4, VC-4-4c , VC-4 are basically used as VC signals.
Although -16c is the target, here, VC-4 will be described as an example. As shown in FIG. 16, the VC-4 signal includes a path monitoring signal area PO (9 bytes) and a payload area P.
(9 × 260 bytes). The SDH path monitor signal rewriting circuits 1211 to 1226 are circuits that set free values given from outside to the path monitor signal area PO.

SDH path supervisory signal rewriting circuit 1211-1
VC in which the path monitoring signal area PO has been rewritten in 226
The signal is input to multiplexing circuits 921 to 924, and multiplexed. Further, the outputs of the multiplexing circuits 921 to 924 are connected to SDH section monitoring signal insertion circuits 931 to 934, respectively.
Are connected, and an SDH section monitor signal is added to
The DH signal is completed and output to the SDH signal output lines 941 to 944.

In this embodiment, the configuration in which the SDH path supervisory signal rewriting circuits 1211 to 1226 are added to the fourth embodiment is used. However, the configuration of the fifth and sixth embodiments using the switch circuit is also different. By connecting the SDH path monitor signal rewriting circuits 1211 to 1226 to the outputs of the circuits 1031 and 1032, the same effect as in the seventh embodiment can be obtained.

The rewriting of the SDH path monitor signal is executed when a failure occurs in the optical path signal input from the optical path signal input line 811 or the like. It is stipulated that when a failure occurs in the optical path signal, the separation circuit 911 outputs a signal in which all bits are logic “1” as a VC signal (see ITU-T Recommendation G.783 “Characteristi”).
cs of synchronous digital hierachy (SDH) equipment f
In this case, since the path monitoring signal area of the VC signal does not have a valid value, a failure may be recognized in the SDH network and the failure recovery function of the SDH network may operate. Since the network also has a failure recovery function, it is desirable in network operation that a failure in the optical path network can be recovered without performing a failure recovery in the SDH network. SD by path monitoring signal rewriting circuit
The SDH path monitoring signal can be set so that failure recognition is not performed in the H network.

FIG. 11 is a block diagram showing an eighth embodiment of the present invention. The present invention is applied to an optical path terminal device which outputs an optical path signal multiplexed with a wavelength by using an SDH signal as an input. An example is shown below.

The optical path terminal equipment terminates the SDH signal, converts the signal into an optical path signal, and outputs the signal (in this example, 3 bits).
) Optical path signal terminating devices 1421-1423,
Optical carrier waves having different wavelengths are assigned to these optical path signal terminating devices 1421 to 1423. A multiplexing circuit 1431 and a link monitoring signal insertion circuit 144 for inserting a link monitoring signal into the wavelength multiplexed optical signal transmitted from the wavelength multiplexing circuit 1431 to the wavelength multiplexing link 1451.
1 is provided.

In this embodiment, the optical path signal termination device 14
21 and 1422 each have one optical carrier λ1, λ
2 is assigned, and the optical path signal terminator 1423 shows an example in which two optical carriers λ3 and λ4 are assigned. In this case, the optical path signal termination equipment 1421 and 1422 may be used an optical path signal terminal station device described in the first embodiment, the optical path signal termination equipment 1423 in the second or third embodiment An optical path signal terminal device having the configuration shown can be used. Although a configuration in which a plurality of types of optical path signal terminal devices are mixed is shown here, a configuration in which only one type of optical path signal terminal device shown in each embodiment is arranged is also possible. .

The SDH signal input from the SDH signal input line 1411 is transmitted to the optical path signal terminators 1421-1423.
Is accommodated in the optical path signal. Different wavelengths are assigned to the optical carrier of the optical path signal, and the wavelength multiplexing circuit 143
Multiplexed by one. The wavelength-multiplexed optical path signal is input to a link monitor signal insertion circuit 1441 where a link monitor signal is inserted. This link monitor signal is an optical signal using an optical carrier having a wavelength different from the wavelength path signal group, and is used for transmitting information on the wavelength multiplexed wavelength path signal group to an adjacent optical path terminal device or the like. used. In this embodiment, the optical carrier wavelength of the link monitor signal is λ
Use 0.

The link supervisory signal insertion circuit 1441 provides a function of wavelength-multiplexing an optical path signal group already wavelength-multiplexed and a link supervisory signal. Therefore, a configuration in which the wavelength multiplexing circuit 1431 is also used as a link monitoring signal insertion circuit is possible. The optical path signal group and the link monitoring signal are
It is input to the wavelength multiplex link 1451.

FIG. 12 is a block diagram showing a ninth embodiment of the present invention, in which the SDH signal contained in the wavelength-multiplexed optical path signal input from the wavelength division multiplexing link is extracted, and the signal is output to the SDH signal output line. For the optical path terminal equipment to output,
The example which implemented this invention is shown.

This optical path terminal equipment terminates an optical path signal, converts the signal into an SDH signal, and outputs it.
) Optical path terminators 1541 to 1543, and optical carrier waves having different wavelengths are assigned to the respective optical path terminators 1541 to 1543.
A link monitoring signal extracting circuit 1521 for extracting a link monitoring signal from the wavelength multiplexed optical signal input from 511, and a wavelength separation for separating the wavelength multiplexed optical signal from the wavelength multiplexing link 1511 and outputting to the optical path terminating devices 1541 to 1543. A circuit 1531.

In this embodiment, the optical path signal termination device 15
41, 1542 each have one optical carrier λ1, λ
2 is assigned and the optical path signal terminator 1543 is assigned two optical carriers λ3 and λ4. In this case, the optical path signal termination equipment 1541, 1542, correspondingly may be used an optical path signal terminal station device shown in the fourth or seventh embodiment, the optical path signal termination equipment 1543 fifth or sixth The optical path signal terminal device having the configuration shown in the embodiment can be used. Although a configuration in which a plurality of types of optical path signal terminal devices are mixed is shown here, a configuration in which only one type of optical path signal terminal device shown in each embodiment is arranged is also possible. .

An optical path signal group and a link monitor signal wavelength-multiplexed from the wavelength multiplex link 1511 are input to a link monitor signal extracting circuit 1521. Link monitoring signal extraction circuit 1
At 521, only the wavelength of the link monitoring signal is separated. In this embodiment, it is assumed that a wavelength λ0 is assigned as a link monitoring signal.

The optical path signal group input to the wavelength separation circuit 1531 is separated according to the wavelength. In this example,
An example is shown in which four wavelengths λ1, λ2, λ3, and λ4 are used as wavelengths.

In this embodiment, the link monitoring signal extracting circuit 1
Although the configuration in which the 521 and the wavelength separation circuit 1531 are separate circuits has been described, a configuration in which a link monitoring signal and an optical path signal are separated by a single wavelength separation circuit is also possible.

The separated optical path signals are input to optical path signal terminators 1541 to 1543, and are converted into SDH signals. The converted SDH signal is output via SDH signal output line 1551.

As described above, since the mutual conversion between the SDH signal and the optical path signal is realized via the VC signal, a switch circuit and an SDH path monitoring signal rewriting circuit can be added, and the optical path signal can be added. In addition to the optical path signal terminating function of mutual conversion of signals and SDH signals, an editing function between SDH signals and optical path signals and a failure recovery function closed to an optical path network can be provided.

[0083]

As described above, according to the present invention,
The SDH signal can be converted into the optical path signal without changing the format of the SDH signal. That is, the optical path monitoring signal can be inserted without increasing the signal length. Further, the output of the optical path signal can be selected for a plurality of output lines. Further, it is possible to separate and process the failure of the optical communication network and the failure of the SDH network. In this way, an optical path signal terminal device that can cope with various use situations can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical path signal terminal apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a format of an optical path signal.

FIG. 3 is a diagram illustrating a configuration example for superimposing an optical path monitoring signal at an optical level on an optical path signal.

FIG. 4 is a diagram showing another configuration example for superimposing an optical path monitoring signal at an optical level on an optical path signal.

FIG. 5 is a block diagram of an optical path signal terminal device according to a second embodiment of the present invention.

FIG. 6 is a block diagram of an optical path signal terminal device according to a third embodiment of the present invention.

FIG. 7 is a block diagram of an optical path signal terminal device according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram of an optical path signal terminal apparatus according to a fifth embodiment of the present invention.

FIG. 9 is a block diagram of an optical path signal terminal apparatus according to a sixth embodiment of the present invention.

FIG. 10 is a block diagram of an optical path signal terminal device according to a seventh embodiment of the present invention.

FIG. 11 is a block diagram of an optical path terminal device according to an eighth embodiment of the present invention.

FIG. 12 is a block diagram of an optical path terminal device according to a ninth embodiment of the present invention.

FIG. 13 is a diagram for briefly explaining a conventional switching network for connecting subscriber terminals.

FIG. 14 is a diagram illustrating path connection of an SDH signal via an SDH path cross-connect.

FIG. 15 is a view for explaining a configuration example in a case where the path connection shown in FIG. 14 is realized by an optical path network;

FIG. 16 is a diagram showing a signal format of a VC signal.

FIG. 17 is a diagram showing a signal format of an STM-N signal.

FIG. 18 is a diagram showing a signal format of a conventional AU signal.

FIG. 19 is a diagram showing a signal format of a conventional optical path signal.

[Explanation of symbols]

11, 18 subscribers 12, 17 exchanges 13, 16, 21-1 to 21-4 transit exchanges 14, 15, 22-1 to 22-4, 23-1 to 23-4
Transmission terminal station 25 SDH path cross connect 26-1 to 26-3 Optical path terminal station 27 Optical path cross connect 111 to 114 SDH signal input line 121 to 124 SDH section monitoring signal processing circuit 131 to 134, 911, 1031 and 1032 Circuits 141, 621, 622, 921 to 924 Multiplexing circuits 211, 213 Optical path monitoring signal insertion circuit 212 Electro-optical conversion circuits 214, 815 Optical path monitoring signal control devices 311, 313 Laser diodes 312 Optical modulators 611, 711, 1041, 1111 Switch circuit 631, 632 Transmission end optical path signal termination circuit 641, 642 Optical path signal output line 811, 1011, 1012 Optical path signal input line 812, 814 Optical path monitoring signal extraction circuit 813 Opto-electric conversion circuit 931 to 934 SDH Section monitoring No. insertion circuits 941 to 944, 1551 SDH signal output lines 821, 1021, 1022 Receiving end optical path signal termination circuits 1211 to 1226 SDH path monitoring signal rewriting circuits 1411 SDH signal input lines 1421 to 1423 Optical path signal termination devices 1431 Wavelength multiplexing circuits 1441 link monitor signal insertion circuit 1451, wavelength multiplex link 1521 link monitor signal extraction circuit 1531 wavelength separation circuit 1541 to 1543 optical path terminator

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-79629 (JP, A) JP-A-5-252162 (JP, A) JP-A-9-247106 (JP, A) Shiragaki, Hemi, Fujiwara, Proposal and Examination of Implementation Method of Operation, Management and Maintenance (OAM) Function in Optical Network, IEICE General Conference, Japan, IEICE, March 10, 1995, Communication in 1995 2,530 pages Cannon Hwu and Stanley Chum, International Gateway For SDH and SONET Interconnection, PROCEEDINGS OF THE GLOBE INTERNATIONAL CO., LTD. EE E, 1994 year, pp. 725-734 (58) investigated the field (Int.Cl. ^7, DB name) H04J 3/00 - 3/26 H04L 5/22 - 5/26 H04B 10/00 JICST file (JOIS )

Claims (16)

(57) [Claims] An electric signal terminating means (121 to 124, 13) for terminating one or a plurality of SDH signals transmitted by an electric signal and outputting an electric signal for sending to an optical path.
1-134, 141), and an optical path monitoring signal of an electric level is inserted into this electric signal,
In the optical path signal terminal station device provided with a light path termination means (211-214) The resulting signal is converted into an optical signal and outputs it as an optical path signal, the optical path termination means, said electrical signal termination means 3. An optical path signal terminal device comprising: means (211) for inserting the optical path monitoring signal in place of the SDH section monitoring signal included in the terminated SDH signal. 2. An electric signal termination means for processing an SDH section monitor signal included in an SDH signal.
21 to 124), demultiplexing means (131 to 134) for demultiplexing the SDH signal processed by this means and converting it into a plurality of VC signals, and multiplexing a plurality of VC signals output from the demultiplexing means. Multiplexing means (141) for converting the signal into an AU signal by adding an AU pointer to the AU signal, further multiplexing the plurality of AU signals obtained, and outputting an electric signal in the form of an optical path signal. 2. The optical path signal terminal device according to claim 1, wherein the optical path signal terminal device inserts the optical level monitoring signal of the electrical level into a predetermined area of the electrical signal of the optical path signal format. 3. The method according to claim 2, wherein the predetermined area is SDH.
3. The optical path signal terminal apparatus according to claim 2, wherein the area corresponds to an area of the SDH section monitor signal in the signal format. 4. A method according to claim 1, wherein said optical path terminating means comprises a plurality (631, 6).
32) are provided, and the multiplexing means (621, 622) are provided corresponding to each of the plurality of optical path terminating means, and a switch circuit () for exchanging and connecting signals between the multiplexing means and the multiplexing / demultiplexing means. The optical path signal terminal device according to claim 2, further comprising (611). 5. A plurality of said multiplexing means (621, 622) and a plurality of said optical path terminating means (631, 632) are provided, respectively, between an output of said plurality of multiplexing means and an input of a plurality of optical path terminating means. 3. The optical path signal terminal device according to claim 2, further comprising a switch circuit (711) for switching and connecting a signal to the optical path signal terminal. 6. The light according to claim 1, wherein said optical path terminating means includes means for adding an optical path monitoring signal having a different optical level from the electrical level optical path monitoring signal to the optical path signal. Path signal terminal equipment. 7. An optical path signal terminal device according to claim 6, wherein said adding means (213) performs wavelength division multiplexing of the optical path signal and an optical path monitoring signal of an optical level. 8. The optical device according to claim 6, wherein said adding means superimposes an optical path monitoring signal at an optical level on the optical path signal with a modulation different from a modulation of a main signal transmitted by the optical path signal. Path signal terminal equipment. 9. An optical path terminating means (812-815) for receiving an optical path signal and converting it into an electric signal, and converting an electric signal output from the optical path terminating means into one or a plurality of SDH signals and outputting the signal. Electrical signal termination means (9
In the optical path signal terminal station device and a 11 to 924), the optical path signal is in the form of a signal that does not include the SDH section supervisory signal of the SDH signal, the electrical signal termination means, said optical path termination means Replaces the optical path monitoring signal included in the received optical path signal with SDH.
Means for inserting section monitoring signal (931-934)
An optical path signal terminal device comprising: 10. The optical path terminating means includes means for converting an optical path signal into an electric signal and extracting an optical path monitoring signal having an electric level added to a predetermined area of the electric signal (814). The electric signal terminating means demultiplexes an electric signal output from the optical path terminating means to convert the electric signal into a plurality of VC signals, and converts the plurality of VC signals output from the demultiplexing means into a plurality of VC signals. Multiplexing means (921 to 924) for multiplexing and converting to an AU signal by adding an AU pointer
10. The optical path signal terminal device according to claim 9, further comprising: means (931 to 934) for inserting an SDH section monitoring signal into the AU signal output from the multiplexing means. 11. An optical path signal is added with an electrical level optical path monitor signal in the area of the SDH section monitor signal in the SDH signal format. The optical path terminating means includes an optical path including the electrical level optical path monitor signal. The electric signal terminating means converts the electric signal output from the optical path terminating means into a plurality of VC signals by demultiplexing the electric signal including the electric level optical path monitoring signal. Demultiplexing means (91
1), a means (1211-1226) for rewriting the area of the SDH section monitoring signal included in the plurality of VC signals output by the demultiplexing means, and multiplexing the output of the rewriting means and adding an AU pointer. AU
10. The optical path signal terminal device according to claim 9, further comprising multiplexing means (921 to 924) for converting the signal into a signal, and means (931 to 934) for adding an SDH section monitoring signal to the AU signal output from the multiplexing means. . 12. The optical path terminating means includes a plurality (102).
1, 1022), and corresponding to each of the plurality of optical path terminating means, the demultiplexing means (1031, 1032).
32. The optical path signal terminal device according to claim 29, further comprising a switch circuit for switching and connecting signals between said demultiplexing means and said multiplexing means. 13. The optical path terminating means (1021, 10)
22) and a plurality of multiplexing / demultiplexing means (1031, 1032), respectively, and a switch circuit (1111) for exchanging signals between the outputs of the plurality of optical path terminating means and the inputs of the plurality of multiplexing / demultiplexing means. 10. The optical path signal terminal device according to claim 9, comprising: 14. The optical device according to claim 9, wherein said optical path terminating means includes means (812) for separating an optical path monitoring signal at a different optical level from the optical level monitoring signal from the optical path signal. Path signal terminal equipment. 15. A plurality of optical path signal terminal apparatuses according to claim 1, comprising a plurality of optical path signal terminal apparatuses,
Different optical carrier wavelengths each other are assigned to their respective optical path signal terminal station device, the wavelength to be transmitted to the optical transmission line by wavelength division multiplexing the output optical signals of these optical path signal terminal station <br/> device Hikaripa scan terminal apparatus provided with a multiplexing means (1431). 16. A plurality of optical path signal terminal apparatuses according to claim 9, comprising a plurality of optical path signal terminal apparatuses, each of which is assigned an optical carrier having a different wavelength. , Hikaripa scan terminal apparatus having a wavelength separation means (1531) for a wavelength division multiplexed optical signal and outputting the separated to each optical path signal terminal apparatus from the optical transmission line.