JP4055442B2 - Optical multiplexing / demultiplexing device and ring network - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical multiplexer / demultiplexer used for constructing a ring network of an optical wavelength division multiplexing transmission system.
[0002]
[Prior art]
In recent years, with the spread of the Internet and multimedia communication, the demand for large-capacity communication channels has increased, and optical wavelength division multiplexing (WDM) transmission technology for multiplexing a plurality of wavelength lights and transmitting them with a single optical fiber is expected. Has been. As a typical network to which this WDM transmission technology can be applied, a ring network in which a plurality of node devices are connected in a ring shape with optical fibers is known.
[0003]
Each node device constituting an optical communication ring network includes an optical add / drop multiplexer (OADM) device. The optical add / drop device inserts an optical signal into the ring (add) and transmits an optical signal from the ring. Separation (Drop) and relay of optical signals flowing in the ring are realized. When WDM transmission is realized in a ring network, the optical multiplexer / demultiplexer adds (adds) an optical signal by multiplexing the optical signal flowing through the ring with the specific wavelength light allocated to each node device, and adds it to the ring. The optical signal is separated (Drop) by demultiplexing the specific wavelength light from the flowing optical signal, and the optical signal flowing through the ring is relayed by passing the optical signal other than the specific wavelength light.
[0004]
A ring network is usually applied to a backbone network that connects cities, regions, and the like, so high reliability is required. Therefore, each node device is provided with various recovery capabilities corresponding to optical fiber breaks and optical multiplexing / demultiplexing device failures. For example, each node device is connected by a plurality of optical fibers, a part (usually half of the optical fibers) is used as a working line, and the rest is used as a protection line for switching when a working line fails. Also, there is a configuration in which redundancy is provided by providing each component of the optical multiplexer / demultiplexer corresponding to the working line and the protection line.
[0005]
This switching method between the working line and the protection line is recommended, for example, in Telecordia (former Bellcore) GR-1400-CORE “SONET Dual-Fed Unidirectional Path Switched Ring (UPSR) Equipment generic Criteria”.
[0006]
A conventional configuration of the above-described optical multiplexer / demultiplexer will be described with reference to FIGS. 22 and 23. FIG.
[0007]
FIG. 22 is a block diagram showing the configuration of the first conventional optical multiplexing / demultiplexing device, and FIG. 23 is a block diagram showing the configuration of the second conventional optical multiplexing / demultiplexing device.
[0008]
As shown in FIG. 22, the first conventional optical multiplexing / demultiplexing device includes a first OADM unit 117 that performs multiplexing / demultiplexing and relaying of an optical signal flowing in the first line as the working line. ₁ And a second OADM unit 117 that performs multiplexing / demultiplexing and relaying of the optical signal flowing in the second line as the protection line ₂ And the first OADM unit 117. ₁ The optical signal output from the first line and the first OADM unit 117 is monitored. ₁ A first failure detection unit 111 for detecting whether or not a failure has occurred and a second OADM unit 117 ₂ The optical signal output from the second line and the second OADM unit 117 is monitored. ₂ A second failure detection unit 112 that detects whether or not a failure has occurred, and a node state that selects a valid line from the first line and the second line from the failure detection results by the first failure detection unit 111 and the second failure detection unit 112 The determination unit 113, the input signal selection unit 114 that is a switch that outputs an optical signal from the line selected by the node state determination unit 113, and the first OADM unit 117. ₁ The first optical branch circuit 115 that divides the optical signal output from the signal and supplies the optical signal to the input signal selection unit 114 and the first failure detection unit 111, respectively, and the second OADM unit 117 ₂ The second optical branch circuit 116 that divides the optical signal output from the first optical signal and supplies the optical signal to the input signal selection unit 114 and the second fault detection unit 112, and the client that is the main processing device in the node device via the transponder unit 118 The first OADM unit 117 divides the signal of the specific wavelength light supplied from the first OADM unit 117. ₁ And the second OADM unit 117 ₂ And a third optical branch circuit 120 to be supplied to each.
[0009]
Among the node devices including the optical multiplexer / demultiplexer of the first conventional example, the node device that separates the optical signal is the first OADM unit 117 from the optical signal flowing in the first line. ₁ Is used to demultiplex only the specific wavelength light and supply it to the first optical branch circuit 115. At this time, the optical signal which is not demultiplexed is sent to the first line as it is. Similarly, the second OADM unit 117 is obtained from the optical signal flowing in the second line. ₂ Is used to demultiplex only the specific wavelength light and supply it to the second optical branch circuit 116. At this time, the optical signal that is not demultiplexed is sent to the second line as it is.
[0010]
The first optical branch circuit 115 includes a first OADM unit 117. ₁ The optical signal (specific wavelength light) output from the first line and the first OADM unit 117 are monitored by the first failure detection unit 111 by monitoring one of the divided optical signals. ₁ Detects whether a failure has occurred. Similarly, the second optical branch circuit 116 includes the second OADM unit 117. ₂ The second optical signal (specific wavelength light) output from the first optical signal is monitored and one of the divided optical signals is monitored by the second failure detection unit 112, whereby the second line and the second OADM unit 117 are monitored. ₂ Detects whether a failure has occurred.
[0011]
The node state determination unit 113 determines a usable line among the first line and the second line from the failure detection results by the first failure detection unit 111 and the second failure detection unit 112. The input signal selection unit 114 outputs the optical signal of either the first line or the second line selected by the node state determination unit 113. The optical signal output from the input signal selection unit 114 is supplied to the client via the transponder unit 118.
[0012]
On the other hand, the node device that adds (Adds) the optical signal supplies the optical signal (specific wavelength light) from the client to the third optical branch circuit 120 via the transponder unit 118. The first OADM unit 117 is divided. ₁ And the second OADM unit 117 ₂ Supply to each.
[0013]
First OADM unit 117 ₁ Transmits the optical signal (specific wavelength light) from the client to the optical signal flowing in the first line. Similarly, the second OADM unit 117 ₂ Transmits the optical signal (specific wavelength light) from the client to the optical signal flowing in the second line.
[0014]
In a ring network composed of a plurality of node devices each provided with the optical multiplexing / demultiplexing device of the first conventional example, an optical signal (specific wavelength light) is transmitted to both the first line and the second line from the node device that transmits the optical signal. In the node device that receives the optical signal, a bidirectional communication path is formed by receiving the optical signal from the effective line of the first line and the second line.
[0015]
Since the optical multiplexer / demultiplexer of the first conventional example includes an OADM unit corresponding to the working line and the protection line, it provides recovery capability against optical fiber failure and failure recovery capability of the OADM unit, respectively. can do.
As shown in FIG. 23, the second conventional optical multiplexing / demultiplexing device includes a first OADM unit 127 that performs multiplexing / demultiplexing and relaying of an optical signal flowing in the first line, which is a working line. ₁ And a second OADM unit 127 that performs multiplexing / demultiplexing and relaying of the optical signal flowing in the second line as the protection line ₂ And the first OADM unit 127. ₁ The first transponder unit 128 has a function of monitoring the optical signal from the terminal and detecting whether or not a failure has occurred. ₁ And the second OADM unit 127. ₂ The second transponder unit 128 has a function of monitoring the optical signal from and detecting the presence or absence of a failure. ₂ It is the structure which has. The first transponder unit 128 ₁ The first transponder unit 128 ₁ And the second transponder unit 128 ₂ When the first line is determined to be an effective line from the failure detection result by the first transponder unit 128 ₁ The second transponder unit 128 relays the optical signal transmitted from the client to the client. ₂ The first transponder unit 128 ₁ And the second transponder unit 128 ₂ When the second line is determined to be an effective line from the failure detection result by the second transponder unit 128 ₂ The optical signal transmitted from the client to the client is relayed. In addition, the second conventional optical multiplexer / demultiplexer includes a first transponder unit 128. ₁ And the second transponder unit 128 ₂ The optical signal outputted from the optical signal is multiplexed and supplied to the client, and the optical signal supplied from the client is divided, and the first transponder unit 128 is divided. ₁ And the second transponder unit 128 ₂ And an optical branch circuit 130 that respectively supplies the optical branch circuit 130.
[0016]
Among the node devices including the second conventional optical multiplexer / demultiplexer, the node device that separates the optical signal drops from the optical signal flowing in the first line to the first OADM unit 127. ₁ The first transponder unit 128 is used to demultiplex only the specific wavelength light. ₁ To supply. At this time, the optical signal which is not demultiplexed is sent to the first line as it is. Similarly, the second OADM unit 127 is obtained from the optical signal flowing in the second line. ₂ The second transponder unit 128 is used to demultiplex only the specific wavelength light. ₂ To supply. At this time, the optical signal that is not demultiplexed is sent to the second line as it is.
[0017]
First OADM unit 127 of the second conventional example ₁ And the second OADM unit 127. ₂ The first transponder unit 128 ₁ And the second transponder unit 128 ₂ An optical signal (specific wavelength light) is supplied to
[0018]
First transponder unit 128 ₁ And the second transponder unit 128 ₂ Includes a failure detection circuit for detecting the occurrence of a failure in the optical signal, determines a usable effective line of the first line and the second line, and outputs an optical signal supplied from the effective line.
[0019]
The optical multiplexing circuit 124 includes a first transponder unit 128. ₁ Alternatively, the second transponder unit 128 ₂ Combines the optical signals output from and outputs to the client.
[0020]
On the other hand, the node device that inserts (Adds) the optical signal divides the optical signal (specific wavelength light) from the client by the optical branch circuit 130, and the first transponder unit 128. ₁ And the second transponder unit 128 ₂ Distribute to each.
[0021]
First transponder unit 128 ₁ The first OADM unit 127 receives the optical signal from the client. ₁ To the first OADM unit 127 ₁ Is the first transponder unit 128 ₁ The optical signal (specific wavelength light) supplied from is combined with the optical signal flowing in the first line and sent out. Similarly, the second transponder unit 128 ₂ The second OADM unit 127 receives the optical signal from the client. ₂ To the second OADM unit 127. ₂ Is the second transponder unit 128. ₂ The optical signal (specific wavelength light) supplied from is combined with the optical signal flowing in the second line and transmitted.
[0022]
In a ring network composed of a plurality of node devices each provided with the optical multiplexing / demultiplexing device of the second conventional example, an optical signal (specific wavelength light) is transmitted to both the first line and the second line from the node device that transmits the optical signal. In the node device that receives the optical signal, a bidirectional communication path is formed by receiving the optical signal from the effective line of the first line and the second line.
[0023]
The optical multiplexer / demultiplexer according to the second conventional example includes an OADM unit and a transponder unit corresponding to the working line and the protection line, respectively. Therefore, the recovery capability against the optical fiber disconnection failure, the failure recovery capability of the OADM unit, And the fault recovery capability of the transponder unit can be provided.
[0024]
However, in the optical multiplexer / demultiplexer of the first conventional example, it is necessary to prepare an OADM for each of the first line as the working line and the second line as the protection line. In addition, there is a problem that the capacity required for the installation location increases.
[0025]
Further, in the optical multiplexer / demultiplexer of the second conventional example, it is necessary to prepare an OADM unit and a transponder unit for the first line and the second line, respectively, so the scale, price, power consumption, and installation location of the node device The capacity required for the above is further increased as compared with the first conventional example.
[0026]
In order to solve such a problem, for example, an optical multiplexer / demultiplexer configured as shown in FIG. 24 is known.
[0027]
FIG. 24 is a block diagram showing the configuration of the third conventional optical multiplexer / demultiplexer.
[0028]
As shown in FIG. 24, the optical multiplexer / demultiplexer of the third conventional example monitors the optical signal from the first line which is the working line, detects the presence or absence of the failure, and the protection line. The second failure detection unit 132 that monitors the optical signal from the second line and detects whether a failure has occurred, and the first line from the failure detection results by the first failure detection unit 131 and the second failure detection unit 132 A node state determination unit 133 that selects an available effective line among the second lines, and a switch that outputs an optical signal from either the first line or the second line selected by the node state determination unit 133. The optical signal from the input signal selection unit 134, the first optical branch circuit 135 that divides the optical signal from the first line and supplies it to the input signal selection unit 134 and the first failure detection unit 131, respectively, and the optical signal from the second line Split , The second optical branch circuit 136 supplied to the input signal selection unit 134 and the second failure detection unit 132, the demultiplexing of the optical signal output from the input signal selection unit 134, and the optical signal supplied from the client And an OADM unit 137 that relays an optical signal flowing through the network, and a transponder unit 138 that relays an optical signal transmitted and received between the OADM unit 137 and the client.
[0029]
Among the node devices including the optical multiplexer / demultiplexer device of the third conventional example, the node device that separates the optical signal is divided by the first optical branch circuit 135 by dividing the optical signal from the first line. Is detected by the first failure detection unit 131 to detect whether or not a failure has occurred in the first line. Similarly, the optical signal from the second line is divided by the second optical branch circuit 136, and one of the divided optical signals is monitored by the second failure detection unit 132, thereby detecting the presence or absence of a failure in the second line.
[0030]
The node state determination unit 133 determines usable valid lines among the first line and the second line from the failure detection results by the first failure detection unit 131 and the second failure detection unit 132. The input signal selection unit 134 outputs an optical signal from either the first line or the second line selected by the node state determination unit 133. However, when both the first line and the second line are valid, for example, an optical signal is output from the first line which is the working line.
[0031]
The OADM unit 137 demultiplexes only the specific wavelength light allocated to itself from the optical signal output from the input signal selection unit 134 and supplies the demultiplexed light to the client via the transponder unit 138. At this time, the optical signal that is not demultiplexed is sent to the supply source line through the third optical branch circuit 140.
[0032]
On the other hand, a node device that adds (adds) an optical signal supplies an optical signal (specific wavelength light) from a client to the OADM unit 137 via the transponder unit 138, and combines the optical signal flowing through the network by the OADM unit 137. Then, it is divided by the optical branch circuit 140 and distributed to the first line and the second line, respectively.
[0033]
In the optical multiplexer / demultiplexer of the third conventional example, since the OADM unit 137 and the transponder unit 138 are used in common for the first line and the second line, only the failure recovery capability for optical fiber breakage can be provided. Compared with the second conventional example, the scale, price, power consumption, capacity required for the installation location, and the like of the node device can be reduced.
[0034]
[Problems to be solved by the invention]
As described above, in the optical multiplexer / demultiplexer of the first conventional example and the optical multiplexer / demultiplexer of the second conventional example, an OADM unit is prepared for the first line that is the working line and the second line that is the standby line. (In the second conventional example, both the OADM unit and the transponder unit are necessary), there is a problem that the size, price, power consumption, capacity required for the installation location, and the like of the node device increase.
[0035]
On the other hand, in the optical multiplexing / demultiplexing device of the third conventional example, the OADM unit 137 and the transponder unit 138 are commonly used for the first line and the second line. Scale, price, power consumption, capacity required for installation location, etc. can be reduced.
[0036]
However, in the configuration of the third conventional example, since the optical signal output from the OADM unit 137 is transmitted to the first line and the second line through the optical branch circuit 140, a failure is detected when a ring network is configured. There is a problem that the failure detection result is not notified from the node device to the subsequent node device.
[0037]
For example, consider a case where a ring network is configured as shown in FIG. 25 and FIG. 26 to be described later show an example in which the first node device 301, the second node device 302, and the third node device 303 are connected in a ring shape using the first line and the second line. In addition, the arrows in FIGS. 25 and 26 indicate optical signal transmission / reception paths, respectively. Further, in FIG. 25 and FIG. 26, in order to make the operation easy to understand, the first failure detection unit 131, the second failure detection unit 132, the node state determination unit 133, the first optical branch circuit 135, and the second optical branch circuit 136 are illustrated. The omitted configuration is shown.
[0038]
From the state where a communication path is formed between the first node device 301 and the second node device 302 using the first line as shown in FIG. 25, the first node device 301 and the second node device as shown in FIG. When the optical fiber of the first line between 302 is disconnected, the input signal selection unit 134 of the second node device 302 switches the path so as to supply an effective optical signal from the second line to the OADM unit 137. On the other hand, the third optical branch circuit 140 of each node device sends the optical signal from the OADM unit 137 to the first line and the second line regardless of the switching operation of the second node device 302. As a result, as shown in FIG. 26, the optical signal transmitted from the second node device 302 is returned to the second node device 302 through the third node device 303 at the subsequent stage. That is, in the optical multiplexer / demultiplexer of the third conventional example, even if a ring network is constructed, it is impossible to restore the communication path when an optical fiber breakage occurs. There was a problem that was limited to (point-to-point) networks.
[0039]
The present invention has been made to solve the above-described problems of the prior art, and provides an optical multiplexer / demultiplexer and a ring network capable of realizing a recovery capability against a failure with an inexpensive configuration. For the purpose.
[0040]
[Means for Solving the Problems]
In order to achieve the above object, an optical multiplexer / demultiplexer of the present invention inserts a specific wavelength optical signal assigned to each client, separates the specific wavelength optical signal, and relays an optical signal flowing through the network into the network. An optical multiplexing / demultiplexing device including an OADM unit,
A first failure detection unit that monitors an optical signal from the first line as a working line and detects whether or not a failure has occurred;
A second failure detection unit that monitors an optical signal from the second line, which is a standby line, and detects whether or not a failure has occurred;
A node state determination unit for determining an available effective line among the first line and the second line from a failure detection result by the first failure detection unit and the second failure detection unit;
The optical signal from the line determined to be an effective line by the node state determination unit is output to the OADM unit. Then, the line determined to have a failure in the node state determination unit is cut off, and the input of the optical signal from the line is stopped. An input signal selection unit to
A first optical branch circuit that divides an optical signal from the first line and supplies the optical signal to the input signal selection unit and the first failure detection unit, respectively;
A second optical branch circuit that divides an optical signal from the second line and supplies the optical signal to the input signal selection unit and the second failure detection unit, respectively;
The specific wavelength optical signal supplied from the client via the OADM unit and the optical signal relayed by the OADM unit are output to a line in which no failure has occurred in the node state determination unit Then, the line determined to have a fault in the node state determination unit is cut off, and the output of the optical signal to the line is stopped. Output signal distribution / blocking section to
It is the structure which has.
[0041]
At this time, the node state determination unit
When the own apparatus is designated as a master node, the specific wavelength optical signal supplied from the client to the line in which the occurrence of a failure is detected is sent from the output signal distribution / cutoff unit to a predetermined cycle. You may make it send out by the time width decided beforehand for every.
[0042]
On the other hand, a ring network of the present invention includes a plurality of node devices including the optical multiplexing / demultiplexing device,
A working line connecting the node devices 1st line And a protection line Second line When,
With
The plurality of node devices are connected in a ring shape by the first line and the second line.
[0043]
(Function)
In the optical multiplexing / demultiplexing device and ring network as described above, an optical signal is output to a line that is determined not to have a failure by the output signal distribution / cutoff unit, and output of the optical signal to the line in which the failure has occurred is stopped. Therefore, when a failure occurs, the failure detection results are sequentially propagated to the node devices in the subsequent stage of the network, and the communication path formed between the arbitrary node devices is restored using the line where no failure has occurred. Therefore, a ring network can be constructed.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described with reference to the drawings.
[0045]
FIG. 1 is a block diagram showing a configuration example of the optical multiplexing / demultiplexing device of the present invention, and FIGS. 2 and 3 are block diagrams showing a configuration example of the OADM unit shown in FIG.
[0046]
As shown in FIG. 1, the optical multiplexing / demultiplexing device according to the present invention includes a first failure detection unit 11 that monitors an optical signal from a first line that is a working line and detects whether a failure has occurred, and a protection line. A second failure detection unit 12 that monitors an optical signal from the second line and detects whether or not a failure has occurred, and the first line and the second line from the failure detection results by the first failure detection unit 11 and the second failure detection unit 12. Among the lines, a node state determination unit 13 that determines a usable effective line, and a line that is determined to be an effective line by the node state determination unit 13 (however, only one of the first line and the second line is effective) ) And the first optical branch that divides the optical signal from the first line and supplies the optical signal to the input signal selector 14 and the first failure detector 11 respectively. Circuit 15 and a second circuit A second optical branch circuit 16 that divides the optical signal from the optical signal and supplies the optical signal to the input signal selection unit 14 and the second fault detection unit 12, respectively, and the demultiplexing of the optical signal output from the input signal selection unit 14, from the client Through the OADM unit 17 that performs multiplexing of the supplied optical signals and relays the optical signals that flow through the network, the transponder unit 18 that relays optical signals transmitted and received between the OADM unit 17 and the client, and the transponder unit 18 The output signal distribution / cutoff unit 20 is an optical switch that outputs an optical signal supplied from a client to a line in which it is determined that no failure has occurred in the node state determination unit 13.
[0047]
In addition, the 1st failure detection part 11 and the 2nd failure detection part 12 can be comprised with the simple detector using the photoelectric conversion element which detects the presence or absence of optical input, for example. Further, the first optical branch circuit 15 and the second optical branch circuit 16 can be constituted by a known coupler made of, for example, an optical fiber. The node state determination unit 13 outputs a signal for switching between the input signal selection unit 14 and the output signal distribution / cutoff unit 20 including optical switches based on the failure detection results by the first failure detection unit 11 and the second failure detection unit 12. Consists of logic circuits to generate. In addition, it is preferable that the node state determination unit 13 includes a plurality of timer circuits used at the time of a line restoration operation described later.
[0048]
As shown in FIG. 2, the OADM unit 17 includes two optical circulators 21, a fiber grating 22, an optical filter 23, and an optical coupler 24. Alternatively, as shown in FIG. 3, an ODMUX (Optical Demultiplexing) unit 31 and an OMUX (Optical Multiplexing) unit 32 are included. The OADM unit shown in FIGS. 2 and 3 has a configuration well known to those skilled in the art and is not directly related to the features of the present invention.
[0049]
In such a configuration, among the node devices provided with the optical multiplexing / demultiplexing device of the present invention, in the node device that separates the optical signal, the optical signal from the first line is divided by the first optical branch circuit 15. The first failure detection unit 11 monitors one of the divided optical signals to detect whether a failure has occurred in the first line. Similarly, the optical signal from the second line is divided by the second optical branch circuit 16, and one of the divided optical signals is monitored by the second failure detection unit 12, thereby detecting whether or not a failure has occurred in the second line.
[0050]
The node state determination unit 13 determines an available effective line among the first line and the second line from the failure detection results by the first failure detection unit 11 and the second failure detection unit 12. The input signal selection unit 14 outputs an optical signal from either the first line or the second line selected by the node state determination unit 13. However, when both the first line and the second line are valid, for example, an optical signal is output from the first line which is the working line.
[0051]
The OADM unit 17 demultiplexes the specific wavelength light allocated to itself from the optical signal output from the input signal selection unit 14 and supplies the demultiplexed light to the client via the transponder unit 18. At this time, the optical signal that is not demultiplexed is sent to the supply source line through the output signal distributor / blocker 20.
[0052]
On the other hand, in a node device that inserts (adds) an optical signal, an optical signal (specific wavelength light) from a client is supplied to the OADM unit 17 via the transponder unit 18 and is combined with the optical signal flowing through the network by the OADM unit 17. Then, it is supplied to the output signal distribution / cutoff unit 20.
[0053]
The output signal distribution / blocking unit 20 stops the optical output to the line where the failure is detected according to the determination result of the node state determination unit 13, and is supplied from the OADM unit 17 to the line where the failure has not occurred. Send an optical signal.
[0054]
When a plurality of node devices including such an optical multiplexing / demultiplexing device are connected in a ring shape as shown in FIG. 4, for example (in FIG. 4, the first node device 101, the second node device 102, and the third node The device 103 is connected in a ring shape using the first line and the second line), and the input signal selection unit 14 of each node device is effective among the optical input signals of the first line and the second line. A drop path is secured by supplying the optical signal of the line (where no fault has occurred) to the OADM unit 17. Further, the output signal distribution / cut-off unit 20 secures an insertion path by sending an optical signal to a line in which no failure has occurred among the first line and the second line. Further, the output signal distribution / shut-off unit 20 stops the output of the optical signal to the line in which the failure has occurred, and the failure information generated on the input side of the first line or the second line is transmitted to the subsequent stage (first line). Or it propagates to the node device on the output side of the second line. That is, in the subsequent node device, optical signal input from the preceding node device through the line in which the failure has occurred stops, so the failure detection unit detects the occurrence of the failure by detecting the optical input interruption. .
[0055]
For example, from the state where a communication path is formed between the first node device 101 and the second node device 102 using the first line as shown in FIG. 4, the first node device 101 and the second node as shown in FIG. When the optical fiber of the first line connecting the node devices 102 is disconnected, the input signal selection unit 14 of each node device switches so as to supply the optical signal from the effective second line to the OADM unit 17, and each node device The output signal distribution / cut-off unit 20 performs switching so as to transmit the optical signal from the OADM unit 17 to the second line in which no failure has occurred. As a result, the communication path between the first node device 101 and the second node device 102 is restored using a line (second line) in which no failure has occurred. 4 and 5, in order to make the operation easy to understand, the first failure detection unit 11, the second failure detection unit 12, the node state determination unit 13, the first optical branch circuit 15, and the second optical branch circuit 16. A configuration in which is omitted is shown. In addition, the arrows in FIGS. 4 and 5 indicate optical signal transmission / reception paths, respectively.
[0056]
Therefore, when the node device including the optical multiplexing / demultiplexing device of the present invention is used, an optical signal is output to a line determined to have no failure by the output signal distribution / cutoff unit, and the light for the line in which the failure has occurred is output. Since the signal output is stopped, when a failure occurs, the failure detection result is sequentially propagated to the node devices at the subsequent stage of the network, and the communication path formed between any node devices uses a line where no failure has occurred. Restored. Therefore, it is possible to construct a ring network and to provide a recovery capability against a failure of an optical fiber.
[0057]
Next, the operation of the optical multiplexing / demultiplexing device of the present invention shown in FIG. 1 will be described in detail with reference to the drawings.
[0058]
The optical multiplexer / demultiplexer shifts to the following five states (a) to (e) depending on whether or not a failure has occurred in each line.
[0059]
(A) State 1: Both the first line and the second line are normal.
[0060]
At this time, the optical multiplexer / demultiplexer secures a drop path by supplying the optical signal flowing in the first line to the OADM unit 17 through the input signal selecting unit 14. In addition, the optical signal output from the OADM unit 17 is sent to the first line and the second line through the output signal distribution / cutoff unit 20, respectively, thereby securing an insertion path. That is, in state 1, a bidirectional communication path between arbitrary node devices is secured using the first line.
[0061]
(B) State 2: A failure occurs on the first line, and the second line is normal.
[0062]
At this time, the optical multiplexer / demultiplexer secures a drop path by supplying the optical signal flowing in the second line to the OADM unit 17 through the input signal selecting unit 14. Further, the optical signal output from the OADM unit 17 is sent to the second line through the output signal distribution / cutoff unit 20 to secure an insertion path.
[0063]
In the state 2, since the output signal distribution / cutoff unit 20 stops the optical output to the first line, the occurrence of the failure is sequentially notified to the node devices connected to the subsequent stage (output side) of the first line. That is, the node device at the rear stage (output side) of the first line detects the failure of the first line by detecting the optical signal stop of the first line. Therefore, in state 2, a bidirectional communication path between any node devices is secured using the second line. Further, the failure information on the first line is sequentially propagated to the subsequent node devices.
[0064]
(C) State 3: The first line is in the process of recovering from a failure, and the second line is in a normal state.
[0065]
At this time, the optical multiplexer / demultiplexer secures a drop path by supplying the optical signal flowing in the second line to the OADM unit 17 through the input signal selecting unit 14 as in the state 2. Further, the optical signal output from the OADM unit 17 is sent to the second line through the output signal distribution / cutoff unit 20 to secure an insertion path.
[0066]
In the state 3, for example, each node device connected to the subsequent stage (output side) of the first line detects the optical signal sent from the output signal distribution / cutoff unit 20 to the first line at every predetermined cycle, Failure recovery is sequentially notified to the node device. Therefore, in state 3, a bidirectional communication path between any node devices is secured using the second line. Further, the failure recovery information on the first line is sequentially propagated to subsequent node devices. Each node device determines that the restoration of the first line has been completed when the state 3 has passed a predetermined time (for example, 200 ms), and transitions to the state 1.
[0067]
(D) State 4: A failure occurs in the second line, and the first line is normal.
[0068]
At this time, the optical multiplexer / demultiplexer secures a drop path by supplying the optical signal flowing in the first line to the OADM unit 17 through the input signal selecting unit 14. Further, the optical signal output from the OADM unit 17 is sent to the first line through the output signal distribution / cutoff unit 20 to secure an insertion path.
[0069]
In state 4, since the output signal distribution / shut-off unit 20 stops the optical output to the second line, the node devices connected to the subsequent stage (output side) of the second line are sequentially notified of the occurrence of the failure. That is, the node device at the rear stage (output side) of the second line detects the failure of the second line by detecting the stop of the optical signal of the second line. Therefore, in the state 4, a bidirectional communication path between arbitrary node devices is secured using the first line. Further, the failure information of the second line is sequentially propagated to the subsequent node devices.
[0070]
(E) State 5: A state in which a failure has occurred in both the first line and the second line.
[0071]
At this time, the optical multiplexer / demultiplexer stops the input of the optical signal from the first line and the second line to the OADM unit 17 by the input signal selection unit 14 and cuts off the drop path. Further, the output signal distribution / cutoff unit 20 stops the transmission of the optical signal output from the OADM unit 17 to the first line and the second line, and cuts off the add path.
[0072]
In the state 5, since the output signal distribution / shut-off unit 20 stops the optical output to the first line and the second line, respectively, the node devices connected to the subsequent stage (output side) of the first line and the second line fail. The occurrences are notified sequentially. That is, the node device at the rear stage (output side) of the first line detects the failure of the first line by detecting the stop of the optical signal from the first line. Similarly, the node device at the rear stage (output side) of the second line detects the failure of the second line by detecting the stop of the optical signal from the second line. Therefore, in the state 5, the bidirectional communication path between arbitrary node devices is blocked. Further, the failure information of the first line and the second line is sequentially propagated to the node device at the subsequent stage.
[0073]
To summarize the above, each state of the node device can be represented by a node state table shown in FIG. Of the configurations of the input signal selection unit and the output signal distribution / cutoff unit shown in FIG. 6, the numbers indicating the connection relationship indicate the input / output terminal numbers of the input signal selection unit 14 and the output signal distribution / cutoff unit 20, respectively. (See FIG. 1).
[0074]
Next, the operation of the optical multiplexer / demultiplexer when the line is normal, when a line failure occurs, and when the line failure is restored will be described with reference to the drawings.
[0075]
In the following, the first node device 201 to the fifth node device 205 including the optical multiplexing / demultiplexing device shown in FIG. 1 are connected in a ring shape with two optical fibers as shown in FIG. A ring network will be described as an example. In the following, as shown in FIG. 7B, a bidirectional communication path is formed between the first node device 201 and the fourth node device 204, and between the second node device 202 and the third node device 203. A case where an optical fiber breakage occurs will be described.
[0076]
(1) When both the first line and the second line are normal:
In this case, since the optical signals are normally input to the optical multiplexing / demultiplexing device from the first line and the second line, the first failure detection unit 11 and the second failure detection unit 12 of each node device have the first line and It is determined that no failure has occurred in the second line, and all of the first node device 201 to the fifth node device 205 are in the state 1.
[0077]
Accordingly, the optical signal inserted (added) from the first node device 201 passes through the first line which is the working line, is relayed by the second node device 202 and the third node device 203, and is separated by the fourth node device 204. (Drop). On the other hand, the optical signal inserted (added) from the fourth node device 204 passes through the first line which is the working line, relays through the fifth node device 205, and is dropped by the first node device 201. . That is, a bidirectional communication path is formed between the first node device 201 and the fourth node device 204 using the first line.
[0078]
(2) When a failure occurs on the first line and the second line is normal:
When the optical fiber of the first line between the second node device and the third node device is disconnected from the state where both the first line and the second line are normal, first, from the first line to the third node device 203 Therefore, the first line failure is detected by the first failure detection unit 11 of the third node device 203.
[0079]
As shown in the state transition diagram of FIG. 8, the third node device 203 makes a transition from the state 1 to the state 2, determines that a failure has occurred in the first line by the node state determination unit 13, and sets the second line as an effective line. Select. Further, according to the determination result of the node state determination unit 13, the input signal selection unit 14 supplies an effective optical signal from the second line to the OADM unit 17, and the output signal distribution / cutoff unit 20 outputs the optical signal to the first line. Stops sending.
[0080]
Since the input of the optical signal from the third node device 203 through the first line stops in the fourth node device 204, the optical fiber in the first line between the third node device 203 and the fourth node device 204 is disconnected. Will be in the same state as when For this reason, the fourth node device 204 also changes to the state 2 and stops sending the optical signal to the first line.
[0081]
Subsequent fifth node device 205, first node device 201, and second node device 202 also transition to state 2 in the same manner as third node device 203 and fourth node device 204, respectively. At this stage, all the node devices 201 to 205 all transit to the state 2 and a ring is formed using the second line. FIG. 9 shows the state transition of each node device at this time.
[0082]
Therefore, the optical signal inserted (Add) from the first node device 201 passes through the second line which is a protection line, is relayed through the fifth node device 205, and is dropped at the fourth node device 204. On the other hand, the optical signal inserted (added) from the fourth node device 204 passes through the second line, which is a protection line, relays through the third node device 203 and the second node device 202, and is separated by the first node device 201. (Drop). That is, the line is restored by forming a bidirectional communication path between the first node device 201 and the fourth node device 204 using the second line which is a protection line. Even when a line failure occurs between other node devices on the first line, the bidirectional communication path is restored using the second line in the same procedure.
[0083]
(3) When a failure occurs on the second line and the first line is normal:
When the optical fiber of the second line between the second node device 202 and the third node device 203 is disconnected from the state where both the first line and the second line are normal, first, the second node device 202 is connected to the second line. Since the input of the optical signal from the line is eliminated, the failure of the second line is detected by the second failure detection unit 12 of the second node device 202.
[0084]
As shown in the state transition diagram of FIG. 8, the second node device 202 makes a transition from the state 1 to the state 4, determines that a failure has occurred in the second line by the node state determination unit 13, and sets the first line as an effective line. Select. Further, according to the determination result of the node state determination unit 13, the input signal selection unit 14 supplies an effective optical signal from the first line to the OADM unit 17, and the output signal distribution / cutoff unit 20 outputs an optical signal to the second line. Stops sending.
[0085]
When the optical signal of the second line between the first node device 201 and the second node device 202 is disconnected, the first node device 201 stops the optical signal from the second node device 202 through the second line. Will be in the same state. For this reason, the first node device 201 also changes to the state 4 and stops sending the optical signal to the second line.
[0086]
The subsequent fifth node device 205, fourth node device 204, and third node device 203 also transition to state 4 in the same manner as the second node device 202 and the first node device 201. At this stage, all the node devices 201 to 205 all transit to the state 4 and a ring is formed using the first line. FIG. 10 shows the state transition of each node device at this time.
[0087]
Accordingly, the optical signal inserted (added) from the first node device 201 passes through the first line which is the working line, is relayed by the second node device 202 and the third node device 203, and is separated by the fourth node device 204. (Drop). On the other hand, the optical signal inserted (added) from the fourth node device 204 passes through the first line which is the working line, is relayed through the fifth node device 205, and is dropped by the first node device 201. That is, a bidirectional communication path is formed between the first node device 201 and the fourth node device 204 using the first line which is a working line. When a line failure occurs between other node devices on the second line, a bidirectional communication path is formed using the first line in the same procedure.
[0088]
(4) When a failure occurs on both the first line and the second line:
In the following description, the optical fiber of the first line connecting the second node device 202 and the third node device 203 is disconnected from the normal state of both the first line and the second line, and then the second node device 202 and the third line are connected. A case where the second line optical fiber connecting the node devices 203 is disconnected will be described.
[0089]
When the optical fiber of the first line between the second node device 202 and the third node device 203 is disconnected, as described above, the first node device 201 to the fifth node device all transition to the state 2 and use the second line. Thus, a bidirectional communication path is formed between the first node device 201 and the fourth node device 204.
[0090]
Subsequently, when the optical fiber of the second line between the second node device 202 and the third node device 203 is disconnected, the second node device 202 also eliminates the input of the optical signal from the second line. The failure of the second line is detected by the unit 12. At this time, the second node device 202 makes a transition from the state 2 to the state 5 as shown in the state transition diagram of FIG. 8, and the node state determination unit 13 has failed in both the first line and the second line. judge.
[0091]
The input signal selection unit 14 disconnects the connection between the first line and the second line and the OADM unit 17 according to the determination result of the node state determination unit 13 and blocks the separation path. Further, the output signal distribution / cutoff unit 20 stops the transmission of the optical signal to the first line and the second line according to the determination result of the node state determination unit 13, and blocks the insertion (Add) path.
[0092]
Since the first node device 201 also stops the input of the optical signal from the second node device 202 through the second line, the optical fiber in the second line between the first node device 201 and the second node device 202 is disconnected. It becomes the same state as when it was done. For this reason, the first node device 201 also transitions to the state 5 and stops sending the optical signal to the second line.
[0093]
Subsequent fifth node device 205, fourth node device 204, and third node device 203 also transition to state 5 in the same manner as second node device 202 and first node device 201. At this stage, all the node devices 201 to 205 all transit to the state 5, and all the optical signals flowing through the first line and the second line are lost. FIG. 11 shows the state transition of each node device at this time.
[0094]
Therefore, the optical signal from the first node device 201 and the optical signal from the fourth node device 204 are blocked, and the communication path between the first node device 201 and the fourth node device 204 is blocked. Note that, when a line failure occurs between other node devices on the first line and the second line, the communication path is blocked in the same procedure. Also, when the optical fiber of the second line is disconnected first, and then the optical fiber of the first line is disconnected, each node device transitions from the state 4 to the state 5 in the same procedure and the communication path is interrupted. .
[0095]
(5) During line restoration:
In the present invention, it is detected whether or not the line has been recovered by inserting an optical signal for line monitoring from the optical multiplexer / demultiplexer at predetermined intervals determined in advance to the line where the occurrence of the failure is detected. As an optical signal for line monitoring, a method using a dedicated wavelength light different from an optical signal used for normal communication can be considered, but this method requires additional cost. In the present invention, failure recovery is detected without increasing the cost by periodically inserting an optical signal used for normal communication into a line where the occurrence of the failure is detected.
[0096]
When inserting an optical signal for line monitoring into a line, the node device needs to generate an optical signal in which a plurality of wavelength lights are multiplexed. When the OADM unit 17 includes an optical amplifier or the like, a method using its spontaneous emission (ASE) is also conceivable, but here, an optical signal supplied from the client to the OADM unit 17 is used. Further, among the node devices constituting the ring, a node device to which at least one channel of specific wavelength light is allocated is designated as a master node, and an optical signal transmitted from the master node is used for line monitoring. In the following, an example in which the first node device 201 is designated as the master node among the node devices configuring the ring network illustrated in FIG. 7B will be described.
[0097]
The master node is in a state where a line failure is detected by the optical multiplexer / demultiplexer, that is, state 2 (first line: failure, second line: normal), state 4 (first line: normal, second line: failure) ), And in state 5 (first line: failure, second line: failure), a predetermined time width (for example, 100 ms) for a line in which the failure is detected every predetermined period (for example, 2 seconds). An optical signal (specific wavelength light) is transmitted. The optical signal for line monitoring is transmitted by the node state determination unit 13 to the output signal distribution / cutoff unit 20 so that the optical signal having a specific wavelength supplied from the client is transmitted to the line where the failure is detected.
[0098]
Each state of this master node is defined as follows.
[0099]
The state of the optical multiplexing / demultiplexing device of the master node has four states, state 21, state 44, state 51, and state 52 described below.
[0100]
(A) State 21: A failure occurs in the first line, and the second line is normal.
[0101]
At this time, the optical multiplexer / demultiplexer of the master node secures a drop path by outputting the optical signal from the second line to the OADM unit 17 by the input signal selecting unit 14.
[0102]
Further, the optical signal output from the OADM unit 17 is transmitted to both the first line and the second line by the output signal distribution / cutoff unit 20, thereby securing an insertion path for the second line and the second line. An optical signal for line monitoring is inserted into one line.
[0103]
A communication path between arbitrary node devices is secured using the second line, and the optical signal for line monitoring is propagated to the subsequent node device through the first line.
[0104]
(B) State 41: A failure occurs in the second line, and the first line is normal.
[0105]
At this time, the optical multiplexing / demultiplexing device of the master node secures a drop path by outputting the optical signal from the first line to the OADM unit 17 by the input signal selecting unit 14.
[0106]
Further, the optical signal output from the OADM unit 17 is sent to both the first line and the second line by the output signal distribution / cutoff unit 20, thereby ensuring an insertion path for the first line and the second line. An optical signal for line monitoring is inserted into two lines.
[0107]
A communication path between arbitrary node devices is secured using the first line, and the optical signal for line monitoring is propagated to the subsequent node device via the second line.
[0108]
(C) State 51: A state in which a failure has occurred in both the first line and the second line, and the failure recovery of the first line is monitored.
[0109]
At this time, the optical multiplexing / demultiplexing device of the master node disconnects the first and second lines and the OADM unit 17 by the input signal selection unit 14 and disconnects the drop path.
[0110]
On the other hand, the optical signal output from the client via the OADM unit 17 is sent to the first line by the output signal distribution / cutoff unit 20 at predetermined intervals, so that the optical signal for line monitoring is sent to the first line. Insert. The optical signal for line monitoring is propagated from the master node to the subsequent node device through the first line.
[0111]
(D) State 52: A state in which a failure has occurred in both the first line and the second line, and the failure recovery of the second line is monitored.
[0112]
At this time, the optical multiplexing / demultiplexing device of the master node disconnects the first and second lines and the OADM unit 17 by the input signal selection unit 14 and disconnects the drop path.
[0113]
On the other hand, an optical signal output from the client via the OADM unit 17 is sent to the second line by the output signal distribution / cutoff unit 20 at a predetermined cycle, so that an optical signal for line monitoring is sent to the second line. insert. The optical signal for line monitoring is propagated from the master node to the subsequent node device through the second line.
[0114]
In summary, each state of the master node can be represented by a node state table shown in FIG. Of the configurations of the input signal selection unit 1 and the output signal distribution / cutoff unit shown in the node state table of FIG. 12, the numbers indicating the connection relationship are the input / output of the input signal selection unit 14 and the output signal distribution / cutoff unit 20. Terminal numbers are shown (see FIG. 1).
[0115]
Next, the operation of each node device at the time of line restoration will be described with reference to the drawings.
[0116]
When monitoring line recovery, there is also a method of simultaneously realizing the above-described state 51 and state 52 by simultaneously inserting optical signals for line monitoring into the first line and the second line. However, the procedure for line recovery will be described below by taking as an example the case of performing failure recovery monitoring for the first line and failure recovery monitoring for the second line separately.
[0117]
(5-1) Recovery procedure when the first line fails:
First, when the optical fiber in the first line between the second node device 202 and the third node device 203 is disconnected from a state where a bidirectional communication path is formed between the first node device 201 and the fourth node device 204 ( The recovery procedure for the first line will be described with reference to FIG.
[0118]
When the optical fiber of the first line between the second node device 202 and the third node device 203 is disconnected, the first node device 201 to the fifth node device 205 all change to the state 2 as described above, and the second line Is used to form a communication path between the first node device 201 and the fourth node device 204.
[0119]
At this time, as shown in FIG. 13, the first node device 201 that is the master node uses the output of the first timer circuit (not shown) to transition to the state 21 every predetermined period (for example, 2 seconds). The failure detection unit 11 monitors whether an optical signal is input from the first line.
[0120]
The input signal selection unit 14 of the master node continues to output the optical signal input from the second line in the normal state to the OADM unit 17. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to both the first line and the second line, and secures an insertion path (Add) by the second line and the first line. An optical signal for line monitoring is inserted.
[0121]
Here, when an optical signal input is detected by the first failure detection unit 11, it is considered that transmission / reception of optical signals through the first line has been resumed by the second node device 202 to the fifth node device 205, respectively. Therefore, it is determined that the failure of the first line has been recovered, and the master node transits to state 1.
[0122]
When the first failure detection unit 11 does not detect an optical signal input, it returns to the state 2 after a certain time (for example, 100 ms, after the second timer has been counted) using the output of the second timer circuit (not shown). To do.
[0123]
On the other hand, in the second node device 202 subsequent to the master node (first node device 201), when the first failure detection unit 11 detects the optical signal input, it determines that the optical input from the first node device 201 has been restored. To state 3.
[0124]
At this time, the input signal selection unit 14 of the second node device 202 continues to output the optical signal input from the second line in the normal state to the OADM unit 17. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to both the first line and the second line, and secures an insertion path (Add) by the second line and the first line. An optical signal for line monitoring is inserted.
[0125]
The first failure detection unit 11 of the second node device 202 determines that the first line has been restored when an optical signal is continuously input for a certain time (for example, 200 ms) or longer, and transitions from state 3 to state 1. . Further, when the input of the optical signal is stopped within the predetermined time (for example, 200 ms), the state 3 is returned to the state 2.
[0126]
The optical signal for line monitoring output from the first node device 201 that is the master node is an optical signal within the monitoring time of state 3 (here, 200 ms) that stops after continuing for a certain time (for example, 100 ms). The second node device 202 returns to the state 2 without moving from the state 3 to the state 1 only by detecting the optical signal for line monitoring.
[0127]
In the third node device 203 subsequent to the second node device 202, the case where the optical fiber disconnection state of the first line between the second node device 202 and the third node device 203 continues is described below (5- 1-A) is executed, and (5-1-B) is executed when the optical fiber is disconnected from the disconnected state.
[0128]
(5-1-A) When the optical fiber disconnection state of the first line between the second node device 202 and the third node device 203 continues:
In this case, since the optical signal stop state through the first line from the second node device 202 is continued, the third node device 203 maintains the state 2. Further, the fourth node device 204 and the fifth node device 205 subsequent to the third node device 203 operate similarly to the third node device 203 and maintain the state 2.
[0129]
Further, the first node device 201 (master node) following the fifth node device 205 starts counting at the time of transition to the state 21 because the input state of the optical signal from the fifth node device 205 is continued. After the count by the second timer circuit (here, for example, 100 ms) is completed, the state 2 is restored.
[0130]
At this time, the second node device 202 returns from the state 3 to the state 2 because the optical signal input from the first node device 201 through the first line stops. FIG. 14 shows the state transition of each node device at this time.
[0131]
With the above operation, the bidirectional communication path between the first node device 201 and the fourth node device 204 using the second line is continued, and the monitoring procedure at the time of line recovery for the first line by the master node is repeated.
[0132]
(5-1-B) When the first line between the second node device 202 and the third node device 203 is restored from the optical fiber disconnection state:
In this case, the third node device 203 transitions to the state 3 on the assumption that the optical input from the second node device 202 has been resumed in order to detect the input of the optical signal by the first failure detection unit 11.
[0133]
The input signal selection unit 14 of the third node device 203 continues to output the optical signal input from the second line in the normal state to the OADM unit 17. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to both the first line and the second line, and secures an insertion path (Add) by the second line. An optical signal for line monitoring is inserted into the line.
[0134]
The first failure detection unit 11 of the third node device 203 determines that the first line has been restored when an optical signal is continuously input for a certain time (for example, 200 ms) or longer, and transitions from state 3 to state 1. . In addition, when the input of the optical signal is stopped within the predetermined time (for example, 200 ms), the state 3 is returned to the state 2.
[0135]
The fourth node device 204 and the fifth node device 205 subsequent to the third node device 203 also operate in the same manner as the third node device 203, and transition to state 1.
[0136]
Further, when the first node device 201 (master node) following the fifth node device 205 detects the resumption of the input of the optical signal from the fifth node device 205, the second node device 202 to the fifth node device 205 Since the line monitoring optical signal has returned through one line, it is determined that the failure of the first line has been recovered, and a transition is made to state 1.
[0137]
Further, in the second node device 202 subsequent to the first node device 201, the optical signal that has passed through the first line from the first node device 201 is continuously input for a certain time (for example, 200 ms) or more, so the first line Transitions from state 3 to state 1.
[0138]
Since the third node device 203 to the fifth node device 205 subsequent to the second node device 202 operate in the same manner as the second node device 202, all the node devices 201 to 205 all change to the state 1. FIG. 15 shows the state transition of each node device at this time.
[0139]
With the above operation, the ring network returns to a normal state, and a bidirectional communication path between the first node device 201 and the fourth node device 204 is formed using the first line.
[0140]
(5-2) Recovery procedure when the second line fails:
Next, when the optical fiber of the second line between the second node device 202 and the third node device 203 is disconnected from a state where a bidirectional communication path is formed between the first node device 201 and the fourth node device 204. The recovery procedure for the second line will be described with reference to (see FIG. 7B) as an example.
[0141]
When the optical fiber of the second line between the second node device 202 and the third node device 203 is disconnected, the first node device 201 to the fifth node device 205 all transition to the state 4 as described above, and the first line The communication path between the first node device 201 and the fourth node device 204 using the is maintained.
[0142]
At this time, as shown in FIG. 13, the first node device 201 as the master node makes a transition to the state 41 every predetermined period (for example, 2 seconds) using the output of the first timer circuit (not shown). The failure detection unit 12 monitors whether an optical signal is input from the second line.
[0143]
The input signal selection unit 14 of the master node continues to output the optical signal input from the first line in the normal state to the OADM unit 17. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to both the first line and the second line, and secures an insertion path (Add) by the first line and the second line. An optical signal for line monitoring is inserted.
[0144]
Here, when the optical signal input is detected by the second failure detection unit 12, it is considered that the transmission / reception of the optical signal through the second line is resumed by the second node device 202 to the fifth node device 205, respectively. Therefore, it is determined that the failure of the second line has been recovered, and the master node transits to state 1.
[0145]
If the optical signal input is not detected by the second failure detection unit 12, the output returns to the state 4 after a certain time (for example, 100 ms, after the second timer is counted) using the output of the second timer circuit (not shown). To do.
[0146]
On the other hand, in the fifth node device 205 subsequent to the master node (first node device 201), when the second failure detection unit 12 detects the optical signal input, it determines that the optical input from the first node device 201 has been restored. To state 1.
[0147]
At this time, the input signal selection unit 14 of the fifth node device 205 continues to output the optical signal input from the first line in the normal state to the OADM unit 17. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to both the first line and the second line, and secures an insertion path (Add) by the first line and the second line. An optical signal for line monitoring is inserted.
[0148]
The fourth node device 204 and the second node device 203 subsequent to the fifth node device 205 operate in the same manner as the fifth node device 205 and make a transition to the state 1.
[0149]
In the second node device 202 subsequent to the third node device 203, the state where the optical fiber disconnection state of the second line between the second node device 202 and the third node device 203 continues is described below (5- 2-A) is executed and (5-2-B) is executed when the optical fiber is disconnected from the disconnected state.
[0150]
(5-2A) When the optical fiber disconnection state of the second line between the second node device 202 and the third node device 203 continues:
In this case, since the optical signal stop state through the second line from the third node device 203 is continued, the second node device 202 maintains the state 4.
[0151]
In addition, the succeeding first node device 201 (master node) continues to be in a state where the input of the optical signal from the second node device 202 is interrupted. Then, for example, the state returns to the state 4 after the count of 100 ms) is completed.
[0152]
At this time, the fifth node device 205 returns from the state 1 to the state 4 because the optical signal input from the first node device 201 is stopped. The subsequent fourth node device 204 and third node 203 operate in the same manner as the fifth node device 205, and all of the first node devices 201 to 5205 are in the state 4. FIG. 16 shows the state transition of each node device at this time.
[0153]
With the above operation, the bidirectional communication path between the first node device 201 and the fourth node device 204 using the first line is continued, and the monitoring procedure at the time of line restoration for the second line by the master node is repeated.
[0154]
(5-2B) When the optical fiber disconnection state of the second line connecting the second node device 202 and the third node device 203 is restored:
In this case, since the second node device 202 detects the input of the optical signal by the second failure detection unit 12, the second node device 202 makes a transition to the state 1 on the assumption that the optical input from the third node device 203 has been resumed.
[0155]
The input signal selection unit 14 of the second node device 202 continues to output the optical signal input from the first line in the normal state to the OADM unit 17. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to both the first line and the second line, and secures an insertion path (Add) by the first line. An optical signal for line monitoring is inserted into the line.
[0156]
When the first node device 201 (master node) following the second node device 202 detects the resumption of the input of the optical signal from the second node device 202, the second line of the second node device 202 to the fifth node device 205. Thus, the line monitoring optical signal has returned, so it is determined that the failure of the second line has been recovered, and the state transitions to state 1.
[0157]
In this way, all the node devices 201 to 205 all transition to the state 1. FIG. 17 shows the state transition of each node device at this time.
[0158]
With the above operation, the ring network returns to a normal state, and a bidirectional communication path between the first node device 201 and the fourth node device 204 using the first line is maintained.
[0159]
(5-3) Recovery procedure when the first line and the second line fail:
Next, from the state where a bidirectional communication path is formed between the first node device 201 and the fourth node device 204, the optical fibers of the first line and the second line between the second node device 202 and the third node device 203 are used. The recovery procedure for the first line and the second line will be described by taking as an example the case where each of them is disconnected (see FIG. 7B).
[0160]
When the optical fibers of both the first line and the second line between the second node device 202 and the third node device 203 are disconnected, the first node device 201 to the fifth node device 205 are all in the state 5 as described above. All the optical signals flowing on the first line and the second line are lost.
[0161]
At this time, the first node device 201 serving as a master node alternately transits to the state 51 and the state 52 every predetermined cycle (for example, 2 seconds) using the output of the first timer circuit (not shown).
[0162]
When the first node device 201 is in the state 51, the input signal selection unit 14 blocks output of optical signals from the first line and the second line to the OADM unit 17, respectively. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to the first line at predetermined intervals, and inserts an optical signal for line monitoring into the first line.
[0163]
The first failure detection unit 11 monitors whether an optical signal is input from the first line. If an optical signal is input, the first failure detection unit 11 performs line monitoring through the first lines of the second node device 202 to the fifth node device 205. Therefore, it is determined that the failure of the first line has been restored, and the state transitions to state 4. Further, after the transition to the state 51, when no optical signal is input to the first failure detection unit 11, the state returns to the state 5 after a certain time (for example, 100 ms) has elapsed (after the second timer is finished).
[0164]
When the first node device 201 is in the state 51, the subsequent second node device 202 makes a transition to the state 4 because the optical signal input from the first node device 201 is resumed through the first line.
[0165]
The input signal selection unit 14 of the second node device 202 outputs the optical signal input from the first line to the OADM unit 17. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to the first line, and secures an insertion path through the first line.
[0166]
The third node device 203 subsequent to the second node device 202 is described below when the optical fiber disconnection state of the first line between the second node device 202 and the third node device 203 continues (5- 3-A) is executed, and (5-3-B) is executed when the optical fiber is disconnected from the disconnected state.
[0167]
(5-3-A) When the optical fiber disconnection state of the first line between the second node device 202 and the third node device 203 continues:
In this case, the third node device 203 maintains the state 5 because the optical signal stop state from the second node device 202 that has passed through the first line is continued. Further, the subsequent fourth node device 204 and fifth node device 205 operate similarly to the third node device 203 and maintain the state 5.
[0168]
Furthermore, the first node device 201 (master node) following the fifth node device 205 counts when the state transitions to the state 51 because the light input interruption state from the fifth node device 205 through the first line continues. After the counting of the second timer (in this case, 100 ms) started, the state 5 is restored.
[0169]
The second node device 202 following the first node device 201 returns from the state 4 to the state 5 because the input of the optical signal from the first node device 201 through the first line is stopped. FIG. 18 shows the state transition of each node device at this time.
[0170]
With the above operation, the communication path is kept disconnected, and the master node transitions to the state 52 after a predetermined period (for example, 2 seconds), and detects the line recovery of the second line (5-3-C) described later. To execute the process.
[0171]
(5-3-B) When the optical fiber disconnection state of the first line between the second node device 202 and the third node device 203 is restored:
In this case, the third node device 203 transits to the state 4 to detect the optical signal from the second node device 202 that has passed through the first line by the first failure detection unit 11, and the output signal distribution / cutoff unit 20 The optical signal output from the OADM unit 17 is sent to the first line. Further, the subsequent fourth node device 204 and fifth node device 205 operate in the same manner as the third node device 203 and transition to state 4.
[0172]
Further, since the first node device 201 (master node) following the fifth node device 205 detects the optical signal from the fifth node device 205 through the first line by the first failure detection unit, the failure of the first line Is determined to have recovered, and the state 4 is entered.
[0173]
With the above operation, all the node devices in the ring network transit to the state 4, and a bidirectional communication path is formed by the first line. FIG. 19 shows the state transition of each node device at this time.
[0174]
On the other hand, when the first node device 201 is in the state 52, the input signal selection unit 14 blocks the output of the optical signal from the first line and the second line to the OADM unit 17, respectively. The output signal distributor / shut-off unit 20 sends the optical signal output from the OADM unit 17 to the second line at predetermined intervals, and inserts an optical signal for line monitoring into the second line.
[0175]
The second failure detection unit 12 monitors whether or not an optical signal is input from the second line. If an optical signal is input, the second failure detection unit 12 performs line monitoring through the second lines of the second node device 202 to the fifth node device 205. Therefore, it is determined that the failure of the second line has been restored, and the state transitions to state 2. If no optical signal is input to the second failure detection unit 12 after the transition to the state 52, the state returns to the state 5 after a certain time (for example, 100 ms) has elapsed (after the second timer has ended).
[0176]
When the first node device 201 is in the state 52, the subsequent fifth node device 205 transitions to the state 2 because the optical signal input from the first node device 201 is resumed through the second line.
[0177]
The input signal selection unit 14 of the fifth node device 205 outputs the optical signal input from the second line to the OADM unit 17. Further, the output signal distribution / cutoff unit 20 sends the optical signal output from the OADM unit 17 to the second line, and secures an add path by the second line.
[0178]
The fourth node device 204 and the third node device 203 subsequent to the fifth node device 205 operate in the same manner as the fifth node device 205 and make a transition to the state 2.
[0179]
The second node device 202 executes (5-3-C) described later when the optical fiber disconnection state of the second line between the second node device 202 and the third node device 203 continues, and the optical fiber When the disconnection state is recovered, (5-3-D) described later is executed.
[0180]
(5-3-C) When the optical fiber disconnection state of the second line between the second node device 202 and the third node device 203 continues:
In this case, the second node device 202 maintains the state 5 because the optical signal stop state from the third node device 203 through the second line is continued.
[0181]
The first node device 201 (master node) following the second node device 202 starts counting at the time of transition to the state 52 because the light input interruption state from the second node device 202 through the second line continues. After the counting of the second timer (here, 100 ms) is completed, the state returns to state 5.
[0182]
Further, the fifth node device 205 following the first node device 201 returns from the state 2 to the state 5 because the input of the optical signal from the first node device 201 through the second line is stopped. The fourth node device 204 and the third node device 203 subsequent to the fifth node device 205 operate similarly to the fifth node device 205 and return to the state 5. FIG. 20 shows the state transition of each node device at this time.
[0183]
With the above operation, the communication path is kept disconnected, and the master node transitions to state 51 after a predetermined period (for example, 2 seconds), and executes the process for detecting the line recovery of the first line described above.
[0184]
(5-3-D) When the optical fiber disconnection state of the second line between the second node device 202 and the third node device 203 is restored:
In this case, the second node device 202 transits to the state 2 in order to detect the optical signal from the third node device 203 that has passed through the second line by the second failure detection unit 12, and the output signal distribution / cutoff unit 20 The optical signal output from the OADM unit 17 is sent to the second line.
[0185]
Since the first node device 201 (master node) following the second node device 202 detects the optical signal from the second node device 202 through the second line by the second failure detection unit, the failure of the second line is recovered. Transition to state 2 is determined.
[0186]
With the above operation, all the node devices in the ring make a transition to the state 2, and a communication path is formed by the second line. FIG. 21 shows the state transition of each node device at this time.
[0187]
As described above, by using the node device including the optical multiplexing / demultiplexing device of the present invention, it is possible to construct a ring network and to provide a recovery capability against an optical fiber failure. In addition, since the OADM unit and the transponder unit are commonly used for the first line and the second line, the size, price, power consumption, capacity required for the installation location, and the like of the node device can be reduced.
[0188]
Note that the node device provided with the optical multiplexing / demultiplexing device of the present invention is not limited to the ring configuration shown in FIG. 7 (a), but when the opposite (point-to-point) network shown in FIG. Needless to say, the ability to recover from an unforeseen failure can be provided.
[0189]
Metro networks, which are expected to grow in the future and are installed in general buildings and factories, are strongly required to be smaller, consume less power, and be less expensive.
[0190]
In a metro network, an IP network using a router is considered to be mainstream. In such a network, fault recovery capability for optical fiber breaks that occur relatively frequently is required, but it is possible to recover from faults such as device faults that occur relatively low by using the router's detour function. become. However, the router's detour function may disconnect the line for several minutes before the failure is recovered. There is also a possibility that a detour cannot be secured.
[0191]
Therefore, for the backbone network that requires high reliability, the configurations of the first conventional example and the second conventional example based on the UPSR recommendation are desirable, but the downsizing of the device configuration, low power consumption, and low price are more strongly demanded. It is effective to use a node device provided with the optical multiplexing / demultiplexing device of the present invention in a metro network.
[0192]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0193]
The optical signal is output to the line that is determined not to have a failure by the output signal distribution / cutoff unit, and the output of the optical signal to the line in which the failure has occurred is stopped. The communication path is sequentially propagated to the node devices in the subsequent stage of the network, and the communication path formed between the arbitrary node devices is restored using a line in which no failure has occurred. Therefore, not only the opposite network but also a ring network can be constructed, and a recovery capability against an optical fiber failure can be provided.
[0194]
In addition, since the OADM unit and the transponder unit are commonly used for the first line and the second line, the size, price, power consumption, capacity required for the installation location, and the like of the node device can be reduced.
[0195]
Further, when the own apparatus is designated as a master node, the specific wavelength optical signal supplied from the client to the line where the occurrence of the failure is detected is preliminarily set at predetermined intervals predetermined by the output signal distribution / cutoff unit. By sending the message with a predetermined time width, it is possible to detect the recovery from the failure with an inexpensive configuration.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of an optical multiplexing / demultiplexing device according to the present invention.
FIG. 2 is a block diagram showing an example of the configuration of the OADM unit shown in FIG.
FIG. 3 is a block diagram showing another configuration example of the OADM unit shown in FIG. 1;
4 is a diagram illustrating an example in which a ring network is configured with node devices including the optical multiplexing / demultiplexing device illustrated in FIG. 1, and is a schematic diagram illustrating a state in which a communication path is formed in a normal state.
5 is a diagram illustrating an example in which a ring network is configured with node devices including the optical multiplexing / demultiplexing device illustrated in FIG. 1, and is a schematic diagram illustrating how a communication path is restored when a failure occurs.
6 is a node state table collectively showing states of node devices including the optical multiplexing / demultiplexing device shown in FIG. 1; FIG.
7 is a diagram illustrating an example in which a ring network is configured by node devices including the optical multiplexing / demultiplexing device illustrated in FIG. 1. FIG. 7 (a) is a block diagram in a normal state, and FIG. It is a block diagram including an occurrence location.
8 is a state transition diagram showing an operation of a node device including the optical multiplexing / demultiplexing device shown in FIG.
FIG. 9 is a schematic diagram illustrating state transition of each node device when a failure occurs in the first line between the second node device and the third node device illustrated in FIG. 7;
10 is a schematic diagram showing state transition of each node device when a failure occurs in the second line between the second node device and the third node device shown in FIG. 7; FIG.
11 shows a state transition of each node device when a failure occurs in the second line from the state in which a failure has occurred in the first line between the second node device and the third node device shown in FIG. 7; It is a schematic diagram.
12 is a node status table collectively showing the status of the master nodes of the ring network shown in FIG.
13 is a state transition diagram showing an operation of a master node of the ring network shown in FIG.
14 is a schematic diagram showing a state transition of each node device when a failure occurs in the first line between the second node device and the third node device shown in FIG. 7 and the failure state continues. FIG. is there.
FIG. 15 is a schematic diagram showing a state transition of each node device when a failure occurs in the first line between the second node device and the third node device shown in FIG. 7 and the failure state is recovered; is there.
16 is a schematic diagram showing a state transition of each node device when a failure occurs in the second line between the second node device and the third node device shown in FIG. 7 and the failure state continues. FIG. is there.
FIG. 17 is a schematic diagram showing a state transition of each node device when a failure occurs in the second line between the second node device and the third node device shown in FIG. 7 and the failure state is recovered; is there.
FIG. 18 is a diagram illustrating a configuration of each node device when a failure occurs in the first line and the second line between the second node device and the third node device illustrated in FIG. 7 and the failure state of the first line continues. It is a schematic diagram which shows a state transition.
FIG. 19 is a diagram of each node device when a failure occurs in the first line and the second line between the second node device and the third node device illustrated in FIG. 7 and the failure state of the first line is recovered; It is a schematic diagram which shows a state transition.
20 shows faults in the first line and the second line between the second node device and the third node device shown in FIG. 7, and the failure of each node device when the failure state of the second line continues. It is a schematic diagram which shows a state transition.
FIG. 21 shows the failure of each node device when a failure occurs in the first line and the second line between the second node device and the third node device shown in FIG. 7 and the failure state of the second line is recovered; It is a schematic diagram which shows a state transition.
FIG. 22 is a block diagram showing a configuration of a first conventional optical multiplexer / demultiplexer.
FIG. 23 is a block diagram showing a configuration of a second conventional optical multiplexer / demultiplexer.
FIG. 24 is a block diagram showing a configuration of a third conventional optical multiplexer / demultiplexer.
25 is a diagram illustrating an example in which a ring network is configured with node devices including the optical multiplexing / demultiplexing device illustrated in FIG. 24, and is a schematic diagram illustrating a state in which a communication path is formed in a normal state.
26 is a diagram illustrating an example in which a ring network is configured with node devices including the optical multiplexing / demultiplexing device illustrated in FIG. 24, and is a schematic diagram illustrating a state in which a communication path cannot be formed when a failure occurs.
FIG. 27 is a block diagram illustrating a configuration of a network in which node devices having optical multiplexing / demultiplexing devices are arranged to face each other.
[Explanation of symbols]
11 First failure detection unit
12 Second failure detection unit
13 Node state determination unit
14 Input signal selector
15 First optical branch circuit
16 Second optical branch circuit
17 OADM Department
18 Transponder section
20 Output signal distribution / cutoff section
21 Optical circulator
22 Fiber grating
23 Optical filter
24 Optical coupler
31 ODMUX
32 OMUX
101, 201 first node device
102, 202 Second node device
103, 203 Third node device
204 Fourth node device
205 fifth node device

Claims (7)

An optical multiplexing / demultiplexing device including an OADM that performs insertion of a specific wavelength optical signal assigned to each client, separation of the specific wavelength optical signal, and relay of an optical signal flowing through the network, to the network,
A first failure detection unit that monitors an optical signal from the first line as a working line and detects whether or not a failure has occurred;
A second failure detection unit that monitors an optical signal from the second line, which is a standby line, and detects whether or not a failure has occurred;
A node state determination unit for determining an available effective line among the first line and the second line from a failure detection result by the first failure detection unit and the second failure detection unit;
An optical signal from a line determined to be an effective line by the node state determination unit is output to the OADM unit, a line determined to have a failure at the node state determination unit is blocked, and the line from the line An input signal selector for stopping the input of an optical signal ;
A first optical branch circuit that divides an optical signal from the first line and supplies the optical signal to the input signal selection unit and the first failure detection unit, respectively;
A second optical branch circuit that divides an optical signal from the second line and supplies the optical signal to the input signal selection unit and the second failure detection unit, respectively;
The specific wavelength optical signal supplied from the client via the OADM unit and the optical signal relayed by the OADM unit are output to a line determined as having no failure by the node state determination unit An output signal distribution / cut-off unit that cuts off a line determined to have a failure in the node state determination unit and stops outputting an optical signal to the line ;
An optical multiplexer / demultiplexer. The node state determination unit
When the own apparatus is designated as a master node, the specific wavelength optical signal supplied from the client to the line in which the occurrence of a failure is detected is sent from the output signal distribution / cutoff unit to a predetermined cycle. The optical multiplexing / demultiplexing device according to claim 1, wherein the optical multiplexing / demultiplexing device is transmitted at a predetermined time width every time. A plurality of node devices comprising the optical multiplexing / demultiplexing device according to claim 2;
A first line that is a working line connecting the node devices and a second line that is a protection line;
With
A ring network in which the plurality of node devices are connected in a ring shape by the first line and the second line. A plurality of node devices comprising the optical multiplexing / demultiplexing device according to claim 2;
At least one first line as a working line connecting the node devices and at least one second line as a protection line;
With
A counter network in which the node devices arranged opposite to each other are connected by the first line and the second line. An optical multiplexer / demultiplexer that performs insertion of a specific wavelength optical signal assigned to each client to the network, separation of the specific wavelength optical signal, and relay of an optical signal flowing through the network,
A first failure detection unit that monitors an optical signal from the first line as a working line and detects whether or not a failure has occurred;
A second failure detection unit that monitors an optical signal from the second line, which is a standby line, and detects whether or not a failure has occurred;
A node state determination unit for determining an available effective line among the first line and the second line from a failure detection result by the first failure detection unit and the second failure detection unit;
Outputs an optical signal from a line determined to be an effective line by the node state determination unit, blocks a line determined to have a failure at the node state determination unit, and inputs an optical signal from the line An input signal selection unit for stopping
A first optical branch circuit that divides an optical signal from the first line and supplies the optical signal to the input signal selection unit and the first failure detection unit, respectively;
A second optical branch circuit that divides an optical signal from the second line and supplies the optical signal to the input signal selection unit and the second failure detection unit, respectively;
The specific wavelength optical signal supplied from the client and the optical signal to be relayed are output to the line determined that no failure has occurred in the node state determination unit, and the node state determination unit An output signal distribution / shut-off unit that shuts off the line determined to be faulty and stops the output of the optical signal ;
An optical multiplexer / demultiplexer. Failure for restoring a communication path formed between any of the node devices when a failure occurs in the first line that is a working line and the second line that is a protection line that connects a plurality of node devices A recovery method,
An optical multiplexing / demultiplexing device included in the node device that performs insertion of a specific wavelength optical signal assigned to each client to the network, separation of the specific wavelength optical signal, and relay of an optical signal flowing through the network,
Monitoring the optical signals from the first line and the second line, respectively, to detect the presence or absence of failure,
A usable effective line is determined from the first line and the second line from the detection result of the occurrence of the failure,
From the optical signal obtained from the line determined to be the effective line, a specific wavelength optical signal assigned to each client is demultiplexed and supplied to the client,
A fault that outputs a specific wavelength optical signal output from the client to a line that is determined not to have a failure, blocks the line that has been determined to have the failure, and stops outputting an optical signal Recovery method. The optical multiplexer / demultiplexer is
When a node device having its own device is designated as a master node, the specific wavelength optical signal supplied from the client to the line where the occurrence of a failure is detected is determined in advance at predetermined intervals. The failure recovery method according to claim 6, wherein the failure recovery method is performed with a time width.

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