JPH06164613A - Optical loop network - Google Patents

Abstract

(57) [Abstract] [Purpose] If there is a node to which power is not supplied in the optical loop network, information can be transmitted through the loop through the node. [Configuration] Optical switch 100 of node bypass unit 90,
200 switches depending on the presence / absence of a power source. If there is no power source, the signal processing devices 5 and 50 are bypassed, and if they are present, the signal processing device is connected to the transmission lines 7 and 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop-shaped optical loop network in which a plurality of nodes are connected by at least two transmission lines, an active transmission line for transmitting an optical signal and a standby transmission line. .

[0002]

2. Description of the Related Art Conventionally, in a system constituted by an optical loop network, by constructing an optical signal transmission line by a dual transmission line of an active system and a standby system, a transmission line failure, a route switching, and a node failure are caused. In addition, when the transmission line failure or node failure actually occurs, the system is moved to a reduced system configuration excluding the failure point to secure communication. For this reason, failure avoidance operations such as loopback using an optical switch, transmission path switching, or node bypass are usually adopted in such cases.

As such a loop network system, a system using two 2 × 2 optical changeover switches is disclosed in Japanese Patent Application No. 62-298, which is invented by Tetsuo Yoshizawa and others.
No. 932 “Optical Loop Network System”. This conventional technique will be described below with reference to the drawings.

FIG. 9 is a conceptual diagram of an optical loop network system. In the figure, 1a to 1d are nodes, 6 is a working transmission line, and 7 is a backup transmission line. In the figure, in the working transmission line 6, information is transmitted counterclockwise through the nodes 1a to 1d, and in the backup transmission line 7, information is transmitted clockwise in the nodes 1a to 1d, which is the reverse of the working transmission line. Has been done.

FIG. 10 is an explanatory diagram showing a case where a failure occurs in the same section on both the working and protection transmission lines in the optical loop network system as shown in FIG.
That is, in FIG. 10, it is assumed that a transmission line failure (disconnection point) has occurred between the nodes 1a and 1d, and the failure point is indicated by F.

In this case, a normal loopback state is entered in order to deal with the failure. That is, in the node 1a, the return of information from the working transmission line 6 to the protection transmission line 7 is performed as indicated by the broken line route, and in the node 1d, the return of information from the protection transmission line 7 to the working transmission line 6 is performed using the broken line route. Perform as shown in. That is, by performing such loopback and shifting to a degenerate system configuration that bypasses the faulty point F, optical information transmission is enabled.

Next, the node bypass will be described. Node bypass refers to the function of a signal processing device connected to the backup transmission line when the signal processing device (not shown) connected to the active transmission line for information transmission / reception at each node fails. Is to substitute.

FIG. 11 shows a conventional node (FIG. 9,
FIG. 11 is a block diagram showing a configuration example of a node in FIG. 10). In the figure, 1, 10 and 11 are nodes,
Reference numeral 2 is an optical switching unit, 3 is a signal processing unit, 4 and 4a are optical switching switches, and 5 and 50 are signal processing devices for transmitting and receiving information.

As shown in FIG. 11, the node 1 is composed of an optical switching section 2 and a signal processing section 3 having an optical signal input / output device (not shown). Light switching unit 2 is 2x
The signal processing unit 3 includes the 2 type optical changeover switches 4 and 4a.
Is composed of an active signal processor 5 and a spare signal processor 50. The optical changeover switches 4 and 4a and the signal processing devices 5 and 50 are connected via transmission lines 6a, 6b, 7a and 7b.

The optical changeover switch 4 has a working transmission line 6 with the node 10 and a backup transmission line 7 with the node 11.
node c that is connected to c and is adjacent to node 1
Output signals from 0 and 11 are input, and the optical transmission switch 4a further includes a working transmission path 6c between the node 11 and
The backup transmission line 7 is connected to the node 10, and the output signal of the optical changeover switch 4a is transmitted to the node 10 and the node 11.
It is designed to be output to.

Here, the 2 × 2 optical changeover switches 4 and 4a are
As shown in FIG. 12, the switching operation is performed. That is, FIG. 12 is an explanatory diagram showing a mode of a switching operation of the optical changeover switch. Specifically, the 2 × 2 optical changeover switches 4 and 4a are
Operation 1 (a pair of contacts on the input side and a pair of contacts on the output side are connected in parallel) and operation 2 (a pair of contacts on the input side and a pair of contacts on the output side are cross-connected) selectively shown in FIG. It can be taken to

Since such a switching operation is possible, when there is no failure in the system, in FIG. 11, the connection state of the optical changeover switches 4 and 4a is the operation 1 shown in FIG. By setting the state of
The communication on the working transmission path and the communication on the protection transmission path can be independently secured.

In FIG. 11, in the case where the current signal processing device 5 fails, in order to switch to the spare signal processing device 50 and perform node bypass, the optical changeover switches 4 and 4a.
It is clear that both should be set to the state of the operation 2 shown in FIG.

In the case of a failure (disconnection) of both the working and protection transmission lines in the same section as shown in FIG. 10,
Move to loopback. In this case, the operating state of the optical changeover switch depends on the relative position of the fault point and the node,
It may be set to either operation 1 or operation 2.

That is, in the node adjacent to the fault point, the optical changeover switch on the side adjacent to the fault is set to the state of operation 2 in FIG. 12, while the optical changeover switch on the opposite side is set to the state of operation 1 in FIG. Set. For nodes that are not adjacent to the point of failure, switch both optical switches
Both are set in the same manner as in the state of operation 1 in FIG. 12, that is, in the normal state.

[0016]

As described above,
In the prior art, in the optical loop network as shown in FIG. 9, when a failure occurs in a transmission line, node bypass and loopback are possible, but when power is not supplied to the node, that is, node power is supplied. 11 is turned on, or when the power supply unit of the node fails, the signal processing device 5 in the node 1 of FIG.
Since no power is supplied to 50 and 50, the signal processing device cannot operate (transmit and receive information),
There is a drawback that information transmission on the optical loop via the node cannot be performed.

The present invention has been made in order to remedy the above-mentioned drawbacks of the prior art. Since power is not supplied to a node which constitutes an optical loop network, information in the node is not supplied. It is an object of the present invention to provide such an optical loop network that enables information transmission in the optical loop network through the node even when the signal processing device that performs the transmission / reception operation does not operate.

[0018]

To achieve the above object, according to the present invention, a plurality of nodes are connected by at least two transmission lines, a working transmission line for transmitting an optical signal and a standby transmission line. In the optical loop network, the working transmission path for transmitting an optical signal in a certain direction around the loop and the optical signal for transmitting in a reverse direction opposite to the one direction at any node therein. With the backup transmission line, the active transmission line and the backup transmission line are pulled in to the node so that the same input side enters and the same output side goes out.

A first switch that switches depending on the presence / absence of power is provided on the input side of the node, and a second switch that is similarly switched on the output side of the node, and a third switch that switches depending on the presence or absence of power. , A fourth switch which is switched depending on the presence or absence of a power source is provided in the node.

[0020]

The first switch provided on the input side of the node operates when power is not supplied to the node.
Cross-connect the working transmission line and the backup transmission line,
When the power is supplied, in order to keep the working transmission line and the backup transmission line in parallel, it is switched depending on the presence or absence of the power supply, and the second switch provided on the output side of the node is also switched in the same manner.

The third switch provided in the node operates the active signal processing device provided in the node when the power is not supplied to the node. When the working transmission line bypasses and passes through, and power is supplied,
So that the working transmission line is connected to the working signal processing device,
It switches depending on the presence or absence of power.

The fourth switch provided in the node operates the spare signal processing device provided in the node when the power is not supplied to the node. When the backup transmission line bypasses and passes through, and power is supplied,
So that the backup transmission line is connected to the backup signal processing device,
It switches depending on the presence or absence of power.

In this way, when power is not supplied to the node forming the optical loop network, the signal processing device for transmitting / receiving information in the node may not operate. Also, information transmission in the optical loop network can be performed through the node.

[0024]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a configuration diagram showing a first embodiment of the present invention.
In FIG. 1, the same numbers as those in FIG. 11 indicate the same things, and in addition, 90 is a node bypass unit, 1
00 and 200 are 2 × 2 optical changeover switches, respectively.
There is the node N between the node 10 and the node 11,
The circuit elements forming the node N are shown.

In FIG. 1, the node bypass unit 90 has two
Comprised of two 2 × 2 optical changeover switches 100, 200,
The signal processing device 5 is connected to the transmission lines 6d and 6e, and the signal processing device 50 is connected to the transmission lines 7d and 7e. The optical changeover switch 4 is connected to the transmission lines 6a and 7a, and the optical changeover switch 4a is connected to the transmission lines 6b and 7b.

As a 2 × 2 optical changeover switch, for example, Takashi Kurokawa et al., 1990 International Topical.
Document number published in Meeting on PHOTONIC SWITCHING
13C-35, Title "Optical Switches using Liquid Crystal
It is possible to use a liquid crystal optical switch of s "(optical switch using liquid crystal).

Due to such a configuration, the node bypass section 90 has two 2 × 2 optical changeover switches 100 and 200 when power is not supplied to the node.
By switching from the connection state when the power is supplied, the signal processing devices 5 and 50 can be automatically bypassed.

When the signal processing device is connected to the transmission line,
Signal processing is performed to receive information addressed to the node and to send information to other nodes, but when power is not supplied to the node, the signal processing device is also inoperable. In this case, By bypassing the node, information transmission between other nodes is not disturbed.

The circuit operation in each of the case where the power is supplied to the node and the case where the power is not supplied will be described below with reference to the corresponding drawings.
FIG. 2 shows an operation state of the optical changeover switch when power is supplied to the node in the configuration shown in FIG.

Referring to FIG. Optical changeover switches 4 and 4
a, 100, and 200 are all in the state of operation 1 in FIG. 12, and the optical signal sent through the optical changeover switch 4 and the transmission line 6a is the optical changeover switch 100, the transmission line 6d, and the signal processing device 5. Through the transmission line 6e, the optical changeover switch 100, and the transmission line 6b to the optical changeover switch 4a. The optical signals sent via the optical changeover switch 4 and the transmission line 7a are the optical changeover switch 200, the transmission line 7d, the signal processing device 50, the transmission line 7e, the optical changeover switch 200, and the transmission line 7.
It is output to the optical changeover switch 4a through b.

That is, when power is supplied to the node, the optical changeover switches 100 and 200 simply input a signal to the signal processing devices 5 and 50, and the signals from the signal processing devices 5 and 50 are inputted to the optical changeover switch 4a. , And the equivalent operation is exactly the same as in the case of the prior art of FIG. That is, the loopback in the case where both the active and standby transmission lines are disconnected, which is possible in the conventional technique, or the node bypass in the case where the signal processing device 5 or 50 fails, is still possible.

FIG. 3 shows an operating state of the optical changeover switch in the configuration shown in FIG. 1 when the node is not supplied with power. Optical changeover switches 4, 4a, 10
Both 0 and 200 are in the state of operation 2 in FIG. It is premised that the optical changeover switch is a switch that automatically switches from the state of operation 1 in FIG. 12 to the state of operation 2 depending on the presence or absence of a power source.

The optical signal sent from the node 10 through the working transmission line 6 is the optical changeover switch 4, the transmission line 7a, the optical changeover switch 200, the transmission line 7b, and the optical changeover switch 4.
a through the transmission path 6c and output to the node 11. The optical signal sent from the node 11 via the backup transmission line 7c passes through the optical changeover switch 4, the transmission line 6a, the optical changeover switch 100, the transmission line 6b, the optical changeover switch 4a, and the transmission line 7 to the node 10. Is output. That is, when power is not supplied to the node, the signal processing devices 5 and 50 in the node can be completely bypassed.

FIG. 4 shows a 2 × 2 optical changeover switch for the current system,
It is a block diagram which shows the 2nd Example which used two for each of a standby system. In the figure, the node bypass unit 90,
The connection relationship between the signal processing devices 5, 50 and the optical changeover switches 4, 4a is exactly the same as in the case of the first embodiment.

Next, the internal connection of the node bypass section 90 will be described. The node bypass unit 90 has four 2 × 2
Optical changeover switches, 100, 101, 200 and 201
Composed of.

FIG. 5 shows an operating state of the optical changeover switch in the configuration shown in FIG. 4 when power is supplied to the node. Optical switch 100, 101, 200,
Both 201 are in the state of operation 1 of FIG. 12, and the optical signal sent via the optical changeover switch 4 and the transmission line 6a is the optical changeover switch 100, the transmission line 6e, the signal processing device 5, and the transmission line 6d. , Is output to the optical changeover switch 4a through the optical changeover switch 101 and the transmission path 6b. The optical signal sent through the optical changeover switch 4 and the transmission line 7a passes through the optical changeover switch 200, the transmission line 7e, the signal processing device 50, the transmission line 7d, the optical changeover switch 201, and the transmission line b. 4a is output.

That is, when power is supplied to the node, the optical changeover switches 100 and 101 simply perform the operation of inputting signals to the signal processing devices 5 and 50, and the optical changeover switches 200 and 201 perform signal processing. Only the operation of guiding the signals output from the devices 5 and 50 to the optical changeover switch 4a is performed, and the equivalent operation is exactly the same as in the case of the conventional technique of FIG. That is, the loopback in the case where both the active and standby transmission lines are disconnected, which is possible in the conventional technique, or the node bypass in the case where the signal processing device 5 or 50 fails, is still possible.

FIG. 6 shows an operating state of the optical changeover switch in the configuration shown in FIG. 4 when the node is not supplied with power. Optical changeover switches 4, 4a, 100, 10
1, 200 and 201 are all in the state of operation 2 in FIG.

The optical signal sent from the node 10 through the working transmission line 6 is the optical changeover switch 4, the transmission line 7a, the optical changeover switch 200, the transmission line 7f, the optical changeover switch 201, the transmission line 7b, the optical changeover switch 4a. , And is output to the node 11 via the transmission path 6c. Also, from the node 11 to the backup transmission line 7
The optical signal sent via c is the optical changeover switch 4,
Transmission line 6a, optical changeover switch 100, transmission line 6f, optical changeover switch 101, transmission line 6b, optical changeover switch 4a,
It is output to the node 10 through the transmission line 7. That is, when power is not supplied to the node, the node can be completely bypassed.

Although shown by broken lines in FIG. 6, it is possible to adopt a configuration in which the optical changeover switches 101 and 100 and 201 and 200 are connected by transmission lines 6g and 7g, respectively. It is also possible to connect the optical attenuator after adjusting it so that the signal level does not become excessive. With this configuration, when the power of the node is turned on, only the power of the optical switch in the node bypass unit is forcibly stopped (state of operation 2).
As a result, the signals transmitted from the signal processing devices 5 and 50 are received by the signal processing devices 5 and 50 themselves, so that the transmission / reception circuits of the signal processing devices 5 and 50 can perform self-diagnosis.

The embodiment described with reference to FIGS. 4 to 6 is
In the node bypass section 90, the optical changeover switch is the switch 10 arranged on the input side of the signal processing device 5.
It consists of two, 0 and a switch 101 placed on the output side,
The signal processing device 50 is composed of two switches, a switch 200 arranged on the input side and a switch 201 arranged on the output side.

As described above, since the input side and the output side of the signal processing device use separate switches, a relatively weak signal input to the signal processing device and a relatively strong signal output from the signal processing device. If the interference between the input side and the output side uses the same switch (Fig. 1).
(3) Compared with FIG. 3), there is an advantage that it can be less.

FIG. 7 is a block diagram showing a third embodiment using two 1 × 2 optical changeover switches. This embodiment is the second
The 2 × 2 optical changeover switch in the embodiment is replaced with 1 × 2 optical changeover switches 102, 103, 202 and 203. When power is not supplied to the 1 × 2 optical changeover switch, the movable contact is connected to a specific terminal.
So to speak, a switch having a self-holding function is used.

In FIG. 7, as an example, the node is not powered and therefore the 2 × 2 optical changeover switches 4, 4a and 1 are used.
The case where power is not supplied to the × 2 optical changeover switch is shown. When power is supplied to the 1 × 2 optical changeover switch, the movable contact takes the connection state shown by the broken line. By configuring the optical changeover switch in this way and connecting the node bypass section 90, the signal processing devices 5 and 50, and the optical changeover switches 4 and 4a in exactly the same manner as in the second embodiment, the second Since the operation can be performed in exactly the same way as in the embodiment, further description will be omitted. However,
In the case of this embodiment, self-diagnosis of the signal processing device is impossible.

FIG. 8 is a block diagram showing a fourth embodiment using four 1 × 2 optical changeover switches. However, in order to avoid complexity, only the inside of the node bypass unit 90 is shown. In this embodiment, a 2 × 2 optical changeover switch is constructed by using four 1 × 2 optical changeover switches and four optical couplers for each of the active system and the standby system.

In the figure, 104, 105, 106,
107, 204, 205, 206 and 207 are 1 × 2 optical changeover switches having a self-holding function, 108, 109 and 1
Reference numerals 10, 111, 208, 209, 210 and 211 are optical couplers. Further, the connection between the node bypass section 90 and the signal processing devices 5 and 50 and the optical changeover switches 4 and 4a,
Since the operation of this embodiment is the same as that of the self-diagnosis in the second embodiment, further description will be omitted.

In this embodiment, the positions of the optical changeover switches (106, 107, 206, 207) and the optical couplers (110, 111, 210, 211) on the node 11 side are exchanged, or an optical coupler is used. It is also possible to adopt a configuration in which it is replaced with a 1 × 2 optical changeover switch. As the 1 × 2 optical changeover switch having the self-holding function used in the third and fourth embodiments, the movable optical fiber type 1
A × 2 optical changeover switch can be applied.

[0048]

As described above, according to the present invention,
In an optical loop network, when power is not supplied to a specific node, that is, before powering on the node, or when the power supply unit of the node fails,
There is an advantage that it is possible to configure a degenerate network that excludes nodes to which power is not supplied, even if power is not supplied to a specific node, because signals can be transmitted through the node.

When the power of the node is turned on, the power of only the optical switch is turned off, so that the signal processing device itself receives the signal transmitted from the signal processing device of the node, thereby performing self-diagnosis in Layer 1. The effect that can be performed also occurs.

Further, in the node bypass section, when the optical changeover switch is composed of two switches arranged on the input side and the output side of the signal processing device, power is applied to the node. During normal communication, the optical signal transmitted from the signal processing device of the node does not interfere with the reception signal in the receiving section of the signal processing device of the node (the input side switch and the output side switch are physically Therefore, there is an advantage that it can be applied even when the crosstalk attenuation amount allowed for the optical changeover switch used is small.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing an operating state of an optical changeover switch when power is supplied to a node in FIG.

FIG. 3 is a block diagram showing an operating state of the optical changeover switch when power is not supplied to the node in FIG. 1.

FIG. 4 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

5 is a block diagram showing an operation state of the optical changeover switch when power is supplied to the node in FIG. 4. FIG.

FIG. 6 is a block diagram showing an operating state of the optical changeover switch when power is not supplied to the node in FIG. 4;

FIG. 7 is a block diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 8 is a block diagram showing a main part of a configuration of a fourth exemplary embodiment of the present invention.

FIG. 9 is a conceptual diagram of an optical loop network system.

FIG. 10 is an explanatory diagram for explaining a situation in the optical loop network system in the case where both the working and protection transmission lines have a failure in the same section.

FIG. 11 is a block diagram showing a configuration example of a conventional node.

FIG. 12 is an explanatory diagram of the operation of the 2 × 2 optical changeover switch.

[Explanation of symbols]

1a, 1b, 1c, 1d ... Node, 2 ... Optical switching unit, 3 ...
Signal processing units, 4, 4a ... Optical changeover switches, 5, 50 ... Signal processing device, 6 ... Working transmission line, 7 ... Standby transmission line, 6a,
6b, 6c, 6d, 6e, 6f, 6g ... Transmission line, 7a,
7b, 7c, 7d, 7e, 7f, 7g ... Transmission line 10,
11 ... Node, 90 ... Node bypass section, 100, 10
1 ... 2 × 2 optical changeover switch, 200, 201 ... 2 × 2 optical changeover switch, 102, 103, 104, 105, 10
6, 107 ... 1 × 2 optical changeover switch, 202, 203,
204, 205, 206, 207 ... 1 × 2 optical switch, 108, 109, 1110, 111 ... Optical coupler, 2
08, 209, 210, 211 ... Optical coupler

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 8220-5K H04B 9/00 H

Claims (2)

[Claims] 1. A loop-shaped optical loop network in which a plurality of nodes are connected by at least two transmission lines of an active transmission line and an auxiliary transmission line for transmitting an optical signal, and at any node among them, The working transmission line that transmits an optical signal in a certain direction around the loop and the backup transmission line that transmits an optical signal in a reverse direction opposite to the one direction enter from the same input side and have the same output. As if going out from the side, the working transmission line and the protection transmission line are pulled into the node, and when power is not supplied to the node, a cross connection is made between the working transmission line and the protection transmission line, When being supplied, the first switch, which is switched depending on the presence / absence of a power supply, is switched to the input side of the node in order to keep the working transmission line and the protection transmission line in parallel. A switch is provided on the output side of the node, and for the active signal processing device provided in the node, when the power is not supplied to the node, the active signal processing device transmits the active signal processing device. Provided in the node and a third switch that switches depending on the presence / absence of power so that the working transmission path is connected to the working signal processing device when the power supply is being supplied by bypassing the path to the through. For the spare signal processing device that is installed, when power is not supplied to the node,
When the backup transmission line bypasses the backup signal processing device and passes through, and power is supplied, the backup transmission line is switched depending on the presence or absence of power so that the backup transmission line is connected to the backup signal processing device. An optical loop network characterized in that the switch and the switch are provided in the node. 2. The optical loop network according to claim 1, wherein the third switch includes an input side switch arranged on an input side and an output side switch arranged on an output side of the current signal processing device. An optical loop comprising two switches, wherein the fourth switch comprises two switches, an input switch disposed on the input side and an output switch disposed on the output side of the spare signal processing device. network.