JP3324988B2 - Optical path signal termination device and optical path signal device - 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
Digital Hierachy) 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 an optical path network in which a wavelength division multiplexing (WDM) technique and a wavelength routing, which make full use of the wide bandwidth of light, are introduced into a path layer has been actively developed.
Existing SDH networks, ATM networks, PDHs (Asynchronous Digital Hierarchy, Presiochronous Digital H
ierachy) network is assumed to be accommodated, but the PDH network is being replaced by the SDH network, and the ATM network
Since the SDH-based ATM system accommodated in the path is the mainstream, it is important to accommodate the SDH signal in the optical path network.

FIG. 3 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. And between the transit exchange 16 and the exchange 17 is, for example, 52 Mb obtained by time-division multiplexing a 64 kb / s line.
/ S path. This path is further multiplexed and transmitted between the transmission terminal stations 14 and 15.

FIG. 4 is a diagram illustrating 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, 23-1 to 23-4, and connected to the SDH path cross connect (XC) 25.
FIG. 4 shows one path between each of the transit exchanges 21-1 and 21-2 to 21-4.

Transmission terminal stations 22-1 to 22-4 and 23-1 to 23-1
The transmission to / from 23-23 is performed by a time-division multiplexed path, and the paths of the individual paths are set by the SDH path cross-connect 25. 4. Adjacent SW and LT in FIG.
(For example, between SW21-1 and LT22-1)
Or a section between adjacent LTs (for example, LTs 22-1 and 23-
1) or a section between the adjacent LT and XC (for example, LT
23-1 and XC25) is called an SDH section.

FIG. 5 is a diagram for explaining an example of a configuration in a case where the path connection shown in FIG. 4 is realized by an optical path network. In this case, the optical path terminal stations 26-1 to 26-3 are used in place of the transmission terminal stations, and the optical path terminal stations 26-1 to 26-3 are respectively connected to the optical path cross-connect 27 via the wavelength division multiplexing link. Connected to. 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, References: Kenichi Sato, Satoshi Okamoto "Development of Optical Path Layer Technology", IEICE Autumn Conference SB-7-1, September 1992, or
Literature: Satoshi Okamoto, Kenichi Sato "S using WDM optical path
DH ATM ATM Network Configuration, 1998 IEICE General Conference, B-10-93, March 1998).

[0007] 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. Two types of signals, which are used for pilot tone superimposition type optical path monitoring signals (mainly used for management and identification of main signal types) (Reference: Satoru O)
KAMOTO and Kenichi SATO "Inter-network interface fo
r photonic transport networks and SDH transport ne
tworks ", Proceeding on IEEE Globecom'97, pp.850-855,
November 1997, JP-A-9-247106, "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, an optical path monitor signal and a pilot tone superimposed type optical path monitor included in a partial area of the optical path signal. The signals are transmitted together.

Next, an SDH transmission method and a conventional technique for accommodating an SDH signal in an optical path will be described. In the SDH transmission method, a VC (Vir) composed of a payload for transmitting information and a path overhead added to the payload.
(tual Container) is transferred as a unit.
FIG. 6 shows a format example of the VC signal. When a VC signal is accommodated in a transmission medium such as an optical fiber, a frame called a synchronous transfer module (STM) is formed.

First, a pointer (AU pointer: Administrator) for managing a difference in frame phase between the STM signal and the VC signal.
(rative Unit Pointer) is added to the VC signal, and then time division multiplexing is performed to generate an AU signal. AU signal to N
An STM-N signal is generated by performing time division multiplexing and adding a section monitoring signal. FIG. 7 shows an example of the format of the STM-N 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 (document: “SDH transmission method”,
Ohmsha, see ISBN4-274-03430-5).

A technique for accommodating a conventional SDH signal in an optical path will be described with reference to FIG. SDH section monitoring signal processing circuit 111, separating circuit 112, SDH path monitoring signal processing circuit 113, multiplexing circuit 114, optical path monitoring signal processing circuit 11 as a configuration for converting an SDH signal into an optical path signal
5. An electro-optical conversion circuit 116, a pilot tone superimposed type optical path monitor signal processing circuit 117 is an optical path signal terminating device, and a pilot tone superimposed type optical path monitor signal processing circuit 124 configured to convert an optical path signal into an SDH signal. ,
Photoelectric conversion circuit 123, optical path monitoring signal processing circuit 12
2. Separation circuit 121, SDH path monitoring signal processing circuit 12
0, the multiplexing circuit 119, and the SDH section monitoring signal processing circuit 118 are defined as optical path signal devices.

An SDH signal transmitted as an STM-N signal through an optical fiber is converted into an electric signal.
The section monitor signal is removed by the H section monitor signal processing line 111, and an AU signal is generated. The section monitor signal that needs to be output to the outside is sent to the SDH section monitor signal controller 131 via the signal output line 141.

On the other hand, the AU signal is sent to a demultiplexing circuit 112 and demultiplexed, and a VC signal (a single signal or a plurality of signals) is extracted. As shown in FIG. 7, the VC signal includes a payload area P and a path monitoring signal area PO, and the SDH path monitoring signal processing circuit 113
The path monitoring signal of each VC signal is read, and processing such as error monitoring is performed.

Next, the multiplexing circuit 114 performs time division multiplexing to generate an AU signal, and the optical path monitoring signal processing circuit 115 adds an optical path monitoring signal to the AU signal. Thus A
FIG. 9 shows an optical path signal obtained by adding an optical path monitoring signal to the U signal.

An SDH signal is accommodated in the payload area P in the form of a VC signal, and a signal sequence having a frame structure of 9 rows and 270 × N columns from the AU pointer area a and the optical path monitoring signal areas O1 and O2. Is formed. This signal train is electro-optically converted by an electro-optical conversion circuit 116, and a pilot tone superimposed type optical path monitor signal processing circuit 117 adds a pilot tone superimposed type optical path monitor signal, thereby completing the optical path signal and converting the SDH signal. It can be accommodated in an optical path.

On the receiving side that generates the SDH signal from the optical path signal, the reverse process is performed. When a wavelength path signal is transmitted to an optical fiber, wavelength multiplexing transmission is performed. Therefore, the optical path signals transmitted to the same optical fiber need to be light having different wavelengths.

[0017]

The above-mentioned conventional SDH
In an optical path signal terminator that converts a signal into an optical path signal,
The feature is that the frame format of the optical path signal and the frame format of the STM-N signal are the same,
There is an advantage that an existing SDH signal processing LSI can be used as an optical path signal processing LSI. Therefore, the SDH section is terminated at the optical path signal terminator, but the SDH section is not defined between the optical path signal terminators. This is because SW21-1 and OL in FIG.
The section of T26-1, the section of SW21-2 and OLT26-2, the section of OLT26-3 and SW21-3 have SDH sections, but the section of OLT26-1 and 26-2 and the section of OLT26-1 and OXC27. Etc. means that there is no SDH section.

Therefore, in a communication network monitoring and control system which assumes that an SDH section exists between the OLTs 26-1 and 26-2, since there is no information transmission mechanism and status notification mechanism as an SDH section, communication is not performed. There is a problem that causes a problem in network management.

The present invention has been made in such a background, and provides an optical path signal terminating device and an optical path signal device capable of directly transmitting an SDH section supervisory signal as an optical path supervisory signal. The purpose is to:
An object of the present invention is to provide an optical path signal termination device and an optical path signal device capable of setting a virtual SDH section between SDH devices connected to the optical path signal termination device. An object of the present invention is to provide an optical path signal terminating device and an optical path signal device that can cope with existing communication network management software assuming that SDH sections are continuous over the entire network.

[0020]

According to the present invention, an SDH section monitoring signal processed by an optical path signal terminating device and output to the outside is branched into two inside the device, one is externally output, and the other is an optical path monitoring signal. An optical path monitor signal, which is sent out as input data of the signal generation block, is processed by the optical path signal device and output to the outside, is branched into two inside the device, one of which is externally output, and the other is of the SDH section monitor signal generation block. The information is transmitted as input data, and necessary information can be provided to a communication network management control system assuming that an SDH section exists.

In the optical path terminating device according to the present invention, the SDH section monitor signal and the optical path monitor signal are input / output to / from the device as separate devices, and the optical path monitor signal is converted from the SDH section monitor signal to the optical path monitor signal inside the device. The path monitor signal can be directly transferred to the SDH section monitor signal.

Therefore, a data communication channel, an order wire, and a communication channel for automatic switching, which are defined as a part of the SDH section monitoring signal, are set between the SDH devices through the optical paths set between the optical path signal terminating devices. It is possible to do. This makes it possible to provide an optical path signal terminating device and an optical path signal device that can provide a virtual SDH section for a communication network management control system that assumes the existence of an SDH section.

That is, a first aspect of the present invention is an optical path signal terminating device, in which means for removing a section monitor signal included in an incoming electric signal, and the section monitor signal is removed by the remover. An optical path signal terminating device comprising: means for applying an optical path monitoring signal to an electric signal; and means for converting the electric signal to which the optical path monitoring signal has been added by the applying means into an optical signal.

Here, a feature of the present invention resides in that a means for replacing a part of the section monitoring signal removed by the removing means with a part of the optical path monitoring signal is provided.

A second aspect of the present invention is an optical path signal device, which converts an incoming optical signal into an electrical signal, removes an optical path monitoring signal included in the electrical signal, and removes the signal. Means for adding a section monitoring signal to the electric signal from which the optical path monitoring signal has been removed by the means for performing the optical path monitoring signal.

Here, the feature of the present invention resides in that there is provided means for replacing a part of the optical path monitoring signal removed by the removing means with a part of the section monitoring signal.

It is preferable that the replacing means includes means for synchronizing the phase of the section monitoring signal with the phase of the optical path monitoring signal prior to the replacement.

Thus, the SDH section monitoring signal can be transmitted as it is as the optical path monitoring signal, and a virtual SDH section can be set between the SDH apparatuses connected to the optical path signal terminating device. Therefore, it is possible to cope with existing communication network management software assuming that SDH sections are continuous in the entire network.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a main part of an optical path signal termination device and an optical path signal device according to an embodiment of the present invention. FIG. 2 is a block diagram of a main part of the monitoring signal selection circuit according to the embodiment of the present invention.

The present invention relates to an optical path signal terminating apparatus and an optical path signal apparatus as shown in FIG. 1, wherein the optical path signal terminating apparatus is an SDH section which is means for removing a section monitor signal included in an incoming electric signal. The monitoring signal processing circuit 111 and the SDH section monitoring signal processing circuit 11
1. An optical path monitoring signal processing circuit 115 which is a means for adding an optical path monitoring signal to the electric signal from which the section monitoring signal has been removed by 1; and an electric signal to which the optical path monitoring signal has been added by the optical path monitoring signal processing circuit 115 Is an optical path signal terminating device including an electro-optical conversion circuit 116 which is means for converting the optical path signal into an optical signal.

Here, the feature of the present invention is that S
A supervisory signal branch circuit 151 which is means for replacing a part of the section supervisory signal removed by the DH section supervisory signal processing circuit 111 with a part of the optical path supervisory signal.
And a monitor signal selection circuit 153.

The optical path signal device is a photoelectric conversion circuit 123 for converting an incoming optical signal into an electric signal.
An optical path monitoring signal processing circuit 122 as means for removing an optical path monitoring signal included in the electric signal; and a section monitoring signal into an electric signal from which the optical path monitoring signal has been removed by the optical path monitoring signal processing circuit 122. This is an optical path signal device including an SDH section monitoring signal processing circuit 118 which is a means for providing a signal.

Here, a feature of the present invention is that a supervisory signal branch is a means for replacing a part of the optical path supervisory signal removed by the optical path supervisory signal processing circuit 122 with a part of the section supervisory signal. The circuit 152 and the monitor signal selection circuit 154 are provided.

Monitor signal selection circuits 153 and 1154
As shown in FIG. 2, prior to replacement, the phase adjustment memories 211 and 21 are means for synchronizing the phase of the section monitoring signal and the phase of the optical path monitoring signal.
2 and a data read control unit 220.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an optical path signal terminating device that converts an SDH signal into an optical path signal and outputs the converted signal, and an optical path signal S
Both optical path signaling devices that convert and output DH signals are described.

S input from the SDH signal input line 101
The DH signal is sent to the SDH section monitor signal processing circuit 111.
Is input to The SDH signal, as shown in FIG.
It is composed of (270 × N) bytes of data, and includes section monitor signal area S1 (3 × (9 × N) bytes), section monitor signal area S2 (5 × (9 × N) bytes), AU It is divided into a pointer area a (1 × (9 × N) bytes) and a payload area P (9 × (261 × N) bytes).

SDH section monitoring signal processing circuit 111
Performs necessary processing for reading data in the section monitoring signal areas S1 and S2. About this processing, ITU-T
Recommendation G.708 "Network node interface for th
e synchronous digital hierarchy ".

The read section monitor signal is
Exactly the same SDH section monitor signal is generated by the SDH section monitor signal control device 131 and the monitor signal branch circuit 151 via the signal output line 141 and sent to the monitor signal selection circuit 153.

SDH section monitoring signal processing circuit 111
The SDH signal processed in is input to the separation circuit 112. The separation circuit 112 separates the STM-N signal into VC signal units and outputs. In the example shown, four VCs
The signal is stored in the payload area P.

Each VC signal is sent to the SDH path monitor signal processing circuit 113. The SDH path monitor signal processing circuit 113 reads a path monitor signal of each VC signal,
Processing such as error monitoring is performed. This process is also ITU-T Reco
mmendation Defined in G.708. Next, the VC signal is sent to the multiplexing circuit 114, and after the AU pointer is added to the input 16 payload signals, it is byte-interleaved multiplexed.

The output of the multiplexing circuit 114 is input to the optical path monitoring signal processing circuit 115. Optical path monitoring signal processing circuit 1
Reference numeral 15 inserts the optical path monitoring signal sent from the monitoring signal selection circuit 153 into the input signal. The signal into which the optical path monitoring signal is inserted is converted from an electric signal to an optical signal in the electro-optical conversion circuit 116. The pilot tone superimposition type optical path monitor signal processing circuit 117 superimposes the optical path monitor signal sent from the optical path monitor signal controller 132 on this optical signal. The completed optical path signal is output to the optical path signal output line 102.

The conversion from the optical path signal to the SDH signal is realized by the reverse operation. Next, the operation of the monitor signal selection circuit 153 will be described with reference to FIG. The SDH section monitor signal and the optical path monitor signal have the same data length and transfer rate, but each have an SDH section monitor signal processing circuit 111.
The optical path monitoring signal controller 132 inputs the SDH signal frame phase and the optical path signal frame phase to the monitoring signal selection circuit 153. The input data is written into the phase adjustment memories 211 and 212. The data read control unit 220 adjusts the read address or write address of the memory via the address control lines 221 and 222 according to the phase difference of the input data, and aligns the phase of the data read from the memory.

The data read control unit 220 selects either the SDH section monitor signal or the optical path monitor signal in accordance with the monitor signal according to a predetermined order.
A part of the data of the optical path supervisory signal is replaced by the SDH section supervisory signal, or conversely, a part of the data of the SDH section supervisory signal is replaced by the optical path supervisory signal and the supervisory signal output 2
23.

As described above, a part of the SDH section supervisory signal is inserted as it is as a part of the optical path supervisory signal.
An optical path signal termination device inserted as a part of the section monitoring signal can be configured.

[0045]

As described above, according to the present invention,
The SDH section monitor signal can be transmitted as it is as the optical path monitor signal. As a result, a virtual SDH section can be set between the SDH devices connected to the optical path signal terminating device. For this reason, S
It is possible to cope with existing communication network management software assuming that DH sections are continuous, and this has the effect of reducing the cost of developing new software.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of an optical path signal termination device and an optical path signal device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a main part of a monitoring signal selection circuit according to the embodiment of the present invention.

FIG. 3 is a diagram simply illustrating a conventional switching network for connecting subscriber terminals.

FIG. 4 is a diagram illustrating path connection of an SDH signal via an SDH path cross-connect.

FIG. 5 is a view for explaining a configuration example when the path connection shown in FIG. 4 is realized by an optical path network;

FIG. 6 is a diagram showing a format example of a VC signal.

FIG. 7 is a diagram showing a format example of an STM-N signal.

FIG. 8 is a diagram illustrating a conventional technique for accommodating an SDH signal in an optical path.

FIG. 9 is a diagram illustrating an optical path signal obtained by adding an optical path monitoring signal to an AU 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 101 SDH signal input line 102 Optical path signal output line 103 Optical path signal input line 104 SDH signal output line 111, 118 SDH Section monitoring signal processing circuit 112, 121 Separation circuit 113, 120 SDH path monitoring signal processing circuit 114, 119 Multiplexing circuit 115, 122 Optical path monitoring signal processing circuit 116 Electro-optical conversion circuit 117, 124 Pilot tone superimposed optical path monitoring signal processing Circuit 123 Photoelectric conversion circuit 131 SDH section monitoring signal control device 132 Optical path monitoring signal control device 141 Signal output line 151, 152 Monitoring signal branch circuit 153, 154 Monitoring signal selection circuit 201 SDH section monitoring signal 202 Optical path monitoring signal 21 , 212 for phase adjustment memory 220 data read control unit 221 and 222 the address control lines 223 monitors signal output

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI H04J 14/02 (56) References JP-A-10-200495 (JP, A) JP-A-4-79629 (JP, A) JP-A-5-252162 (JP, A) JP-A-9-247106 (JP, A) Cannon Hwu and Stanley Chum, International Gateway For SDH and SONET CONNECTION CONNECTION CONNECTION CONFIGURATION , 1994, 725-734 Satoru Okamoto and Ken-ichi Sato, Inter-Network Interf. ce for Photonic T ransport Networks and SDH Transport Networks, IEEE, 1997 years, 850-855 Satoru Okamoto, Ki mio Oguchi and Ken -ichi Sato, Network Architecture and Management Conepts for Optical Trans port Ntworks, IEEE, 1996 years, 1-11 Page Hamazumi, Okamoto, Koga, A Study on Optical Path Monitoring Method Using Pilot Tones in Optical Path Networks, IEICE Technical Report OCS96-66, Japan, The Institute of Electronics, Information and Communication Engineers, November 1996, 45- 52 (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04J 3/00-3/26 H04L 5/22-5/26 H04B 10/00 H04J 14/00 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A means for removing a section monitor signal included in an incoming electric signal, a means for providing an optical path monitor signal to the electric signal from which the section monitor signal has been removed by the remover, and a means for providing the optical path monitor signal Means for converting an electrical signal to which an optical path monitoring signal has been added into an optical signal according to the section monitoring signal, wherein the section monitoring signal removed by the removing means
Defined as part of the section monitor signal
Data communication channel, order wire, communication for automatic switching
An optical path signal terminating device comprising: means for replacing channel data with a part of the optical path monitoring signal. Means for converting an incoming optical signal into an electrical signal; means for removing an optical path monitoring signal included in the electrical signal; and means for removing the optical path monitoring signal from the electrical signal by the removing means. Means for providing a section monitoring signal, wherein a part of the optical path monitoring signal removed by the removing means is defined as a part of the section monitoring signal.
Data communication channel, order wire, automatic switching
An optical path signal processing device, comprising: means for replacing data with a data of a communication channel . Wherein said replacing means, optical path signal termination equipment according to claim 1 further comprising means for synchronizing the phase of said optical path supervisory signal of the section supervisory signal prior to replacement. 4. The replacement means according to claim 1, wherein
The phase of the section monitor signal and the optical path monitor signal.
3. The optical path according to claim 2, further comprising means for synchronizing the phase of the signal.
Signal processing device.