JP2000078176A - Communication network and communication network node device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ring system, which can effectively utilize auxiliary resources to be used in the case of fault or maintenance and reduces a delay difference between active and detour paths at the time of maintenance. SOLUTION: When a disconnection fault occurs on the optical fiber of an active ring 101 between nodes 106 and 109 in the state of constituting the ET path of wavelength λ1 from the node 109 to a node 107 on a reserve ring 104, a supervisory controller in the node 107 detects the fault on an optical path 601, performs messaging to related nodes in order to disconnect a short path (reserve path 602) on the reserve ring 104 and disconnects the ET path of wavelength λ1 from the node 109 to the node 107. When the disconnection of the ET path is confirmed, the node 107 requests the transmission of main signal light through the reserve ring 104 to the node 106. According to that request, at the node 106, an optical switch is changed over for sending light to the reserve ring 104 as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication network using optical communication and the like, and more particularly to a network configuration, a node device, a failure recovery method, and a maintenance system.

[0002]

2. Description of the Related Art In order to respond to a demand for increasing the capacity of communication, in an optical communication network, means for increasing the capacity in one optical transmission line by performing wavelength multiplexing is employed. In order to operate such a network efficiently, an optical ADM (Add / Drop MDM) that switches at the wavelength unit of an optical signal and separates and inserts an optical signal in a communication network node.
An optical ADM ring system in which nodes are connected to form a ring topology has been studied.

As an optical ADM ring system, a four-fiber bidirectional path / switching ring (hereinafter abbreviated as Bi-Path system) is being studied (Shiragaki, Hemi: "Bi-directional Path-
Proposal of switched wavelength multiplexing self-healing ring "IEICE 1998 General Conference B-10-147, 1998.
reference).

[0004] In the following description, the term "separation" means to output a signal obtained by decomposing a signal transferred in a network node to another communication device in the node. Insertion means that in a network node, a signal from another communication device in the node is multiplexed with a transmission signal and transmitted to another node. Passing means that some or all of the transmitted signals are not separated or inserted into other communication devices in the own node, and wavelengths or time slots are not interchanged as they are, or are spatially connected. This means that the data is transmitted to another node by changing the wavelength or changing the time slot. or,
Here, an optical path is defined as a period from when an electric signal is converted to an optical signal at a certain node and sent to another node, until the electric signal is converted again into an electric signal. In the following, the light path is 1
Wavelengths correspond.

FIG. 21 is a block diagram showing the above-mentioned conventional system. In FIG. 21, reference numerals 2101 and 2103 denote working optical rings for transmitting optical signals in opposite directions.
Reference numeral 2 denotes a spare optical ring for transmitting an optical signal in a direction opposite to 2101, and reference numeral 2104 denotes a spare optical ring for transmitting an optical signal in a direction opposite to 2103.

[0006] Wavelength multiplexed optical signals are transmitted in the optical fiber of each ring, and each wavelength constitutes an optical path. In the Bi-Path system, by switching 1 × 2 optical switches provided in each node, it is possible to select whether to transmit light to the working ring or to the spare ring in the opposite direction, and to transmit the optical signal. As for the separated output, a configuration is used which can select whether to separate and output the optical signal of the working ring or to separate the optical signal of the spare ring which is the reverse transmission. In FIG. 21, 1 × 2 switches 2110 and 2109 have the function.

Next, a brief description will be given of the failure recovery operation in FIG. When the working optical path 2131 is configured using the wavelength λ1 between the node 2106 and the node 2107 and a failure of the fiber of the working optical ring 2101 occurs between the node 2106 and the node 2107, the working optical path is 2131 is detected, and a switching request is sent to the node 2106 which is the starting point of the optical path. Upon receiving this switching request, the node 2106 switches the optical switch 2110, and the active optical path 21
A backup optical path 2132 is formed in a direction opposite to that of the optical path 31, and recovery is performed by detouring.

[0008] In the configuration of the Bi-Path system and the failure recovery method, exchange of control messages for failure recovery is performed by SO.
NET line protection (eg, TH Wu, “Fib
er Network Service Survivability, ”Artech house,
1992), the exchange between the node 2107 and the node 2106 may be performed several times on the ring.
For example, high-speed failure recovery of about 50 msec can be performed. Also, if a method of performing loop-back switching such as SONET line protection is used with light, it is necessary to consider the case where the ring goes around two rounds. Had to design the ring.

However, in the Bi-Path system, since loopback switching is not performed, there is an advantage that the ring size can be set to a distance capable of optical transmission (Shiragaki, Hemi: "Bi-directional Path"). Proposal of -switched WDM Self-Healing Ring "IEICE 19
1998 General Conference B-10-147, 1998.). As described above, the Bi-Path method is capable of high-speed failure recovery, and
There is an advantage that the size of the ring can be set to one time (not 倍) the optical transmission distance.

On the other hand, at present, the capacity of communication is increasing, and it is necessary to increase the number of available paths as much as possible. Therefore, it has been considered to accommodate low-priority communication in an optical path configured on a spare ring to increase the amount of communication that can be accommodated. Hereinafter, the working path configured on the spare ring is referred to as an ET path (ET: Extra traf
fic. Standby access).

When the ET path is used, when no failure occurs, the bandwidth available for the entire system increases, and the use efficiency of the ring system increases. However, since the ET path is a communication with a low priority, if a failure occurs in the working optical path on the working ring, the failure recovery takes precedence and hinders the failure recovery of the working optical path in the working ring. ET
The path is cut off.

[0012]

When a path between two nodes is considered on the Bi-Path ring, a clockwise path and a counterclockwise path can be considered. Usually, the path having the smaller number of hops is considered. Since the path is used as the working path, the ET path is configured on a spare ring having a large number of hops.

However, when recovering from a failure, a detour path having a large number of hops is formed. If an ET path using a wavelength of λm exists on this detour path, it is necessary to disconnect the ET path. In order to construct a backup path (λm) having a large number of hops, the number of ET paths that must be separated increases, and many users using the ET path suffer failures. That is, the use efficiency of the ET pass is poor.

Also, during maintenance of the ring system (for example, replacement of an optical switch), a long bypass path must be formed in the backup ring, and the total number of hops of the ET path that must be disconnected increases. , The use efficiency of the ET pass deteriorates.

When the conventional technique is used, it is necessary to switch between a path having a large number of hops and a path having a small number of hops during maintenance. Therefore, when transmitting a signal, the delay time is large because the delay difference is large. In order to perform instantaneous interruption switching, it is necessary to use a memory to absorb the delay difference in order to equalize the delays of the two paths. However, the large delay difference increases the required memory capacity.

Further, in the prior art, since a path is always switched to a path having a large number of hops, especially in an ultra-long distance ring, the number of nodes involved in the switching increases and the failure recovery time increases.

Further, since the switching destination candidate is only a backup path having a large number of hops (a backup path transmitted in a direction opposite to the working path), the reliability at the time of failure is low.

An object of the present invention is to provide an ET even at the time of trouble or maintenance.
It is possible to construct a detour path with high path utilization efficiency and a small delay difference, high-speed failure recovery is possible depending on the failure condition even with an ultra-long-distance ring, and build a highly reliable ring system at the time of failure It is in.

[0019]

A communication network according to the present invention comprises a plurality of communication node means for inserting and separating signals, and a plurality of transmission paths, wherein the plurality of communication node means comprises the plurality of transmission paths. At least a first ring so as to form the same network topology by the connections of
Forming a second ring, a third ring, and a fourth ring, wherein the first ring transmits a working signal either clockwise or counterclockwise, and reserves resources for the working signal of the first ring; The spare resources of the second ring transmitting signals in the opposite direction to the first ring and the fourth ring transmitting signals in the same direction as the first ring are shared by a plurality of working signals. The third ring transmits a working signal in a direction opposite to that of the first ring, and transmits a signal in a direction opposite to the third ring as a backup resource for the working signal of the third ring. By using the second ring spare resource for transmitting a signal in the same direction as the fourth ring and the third ring to be used among a plurality of working signals,

A signal is inserted at an i-th communication node means of the plurality of communication node means and terminated at a j-th communication node means via the first ring.
A detour configured in the second ring or the fourth ring as a detour configured for recovery or maintenance of communication failure, and an mth communication node among the plurality of communication node means. Means for inserting a signal by means and terminating the signal at the n-th communication node means via the third ring; Alternatively, a detour provided in the second ring is used.

In another embodiment of the communication network of the present invention, the communication network comprises a plurality of communication node means for inserting and separating signals, and a plurality of transmission paths, wherein the plurality of communication node means are connected to the plurality of transmission paths. At least a first ring and a second ring so as to form the same network topology by the connection of the first ring, the first ring transmits a signal either clockwise or counterclockwise;
In the ring, the signal is transmitted in the opposite direction to the first ring, and the first ring is transmitted in the working signal group transmitted in the second ring and the first ring in a transmission band. The second ring has a protection resource band shared between working signals, and the second ring has a working signal group transmitted by the first ring and a working signal group transmitted by the second ring within a transmission band. Characterized by having a spare resource band shared among the plurality of communication node means, wherein a signal is inserted by an i-th communication node means of the plurality of communication node means, and a signal is inserted through the first ring. As a bypass configured for failure recovery and maintenance of the first communication terminating the signal at the j-th communication node means, a spare resource band of the second ring or a spare resource band of the first ring is used. Using the configured communication path, Second terminating the signal at the n-th communication node means via the m-th communication node means inserted signals in to the second ring of the communication node means
A communication path configured by the spare resource band of the first ring or the spare resource band of the second ring can be used as a bypass configured for recovery or maintenance of communication failure. I have.

Also, in the communication network node device of the present invention, a plurality of or a single multiplexed signal input terminal for inputting a multiplexed signal, a plurality of or a single inserted input terminal for inserting a signal, and the multiplexed signal input terminal are input to the multiplexed signal input terminal. Plural or single demultiplexed output terminals for outputting a demultiplexed signal obtained by demultiplexing a multiplexed signal, and a plurality of multiplexed signal output terminals for multiplexing and outputting the signal input to the insertion input terminal and the demultiplexed signal. Insertion / demultiplexing means, plural or single external input terminals connected to other nodes, plural or single external output terminals connected to other nodes, plural or single switch means, plural or single merge means And a plurality or single signal input terminals, and a plurality or single signal output terminals, wherein the external input terminal is connected to a multiplex signal input terminal of the insertion / demultiplexing means, A plurality of the insertion / separation devices, wherein a heavy signal output terminal is connected to the external output terminal, the signal input terminal is connected to the switch means, and the external output terminal connected to the multiplexed signal output terminal is connected to the same node. The insertion input end of the multiplexing means and the insertion input end of the insertion / separation means connected to a node different from the same node are connected to the output end of the switch means, and the external input end connected to the multiplexed signal input end. The separation output terminals of the plurality of insertion / demultiplexing units connected to the same node and the separation output terminals of the insertion / separation / multiplexing units connected to nodes different from the same node are connected to the input terminals of the merging unit, The merging means is connected to the signal output terminal.

In another embodiment of the communication network node apparatus according to the present invention, a plurality of or a single multiplex signal input terminal for inputting a multiplex signal, a plurality or a single insertion input terminal for inserting a signal, and the multiplex signal input terminal are provided. A multiplexed signal input to the multiplexed signal and a multiplexed / demultiplexed signal output to output a multiplexed / demultiplexed signal, and a multiplexed signal output terminal to multiplex and output the signal input to the insertion input terminal and the multiplex / demultiplexed signal. A plurality of insertion / separation multiplexing means, a plurality of or a single external input terminal connected to another node, a plurality of or a single external output terminal connected to another node, a plurality of or a single switch means, a plurality or a A single merging unit, a plurality or a single signal input terminal, a plurality or a single signal output terminal, exchange of control information with another node, and switching control of the optical switch unit based on the control information The external input terminal is connected to a multiplex signal input terminal of the insertion / demultiplexing means, the multiplex signal output terminal of the insertion / demultiplexing means is connected to the external output terminal, A signal input terminal is connected to the switch means, and the external output terminal connected to the multiplexed signal output terminal is connected to the same node. An insertion input end of the insertion / separation / multiplexing means connected to the output end of the switch means;
Separation output terminals of the plurality of insertion / demultiplexing units, wherein the external input terminals connected to the multiplexed signal input terminal are connected to the same node, and separation of the insertion / demultiplexing unit connected to a node different from the same node. An output terminal is connected to an input terminal of the merging unit, and the merging unit is connected to the signal output terminal.

According to still another embodiment of the communication network node apparatus of the present invention, a plurality of or a single multiplex signal input terminal for inputting a multiplex signal, a plurality or a single insertion input terminal for inserting a signal, and the multiplex signal input are provided. Multiple or single demultiplexed output terminals for outputting a demultiplexed signal obtained by demultiplexing a multiplexed signal input to an end, and a multiplexed signal output terminal for multiplexing and outputting the signal input to the insertion input terminal and the demultiplexed signal. , A plurality or single external input terminals connected to other nodes, a plurality or single external output terminals connected to other nodes, and a plurality or single devices having multiple output terminals Switch means, a plurality or a single merging means,
A plurality or a single signal input terminal, a plurality or a single signal output terminal, a plurality of or a single signal monitoring means for monitoring a signal input to the merging means, and the optical switch means for exchanging control information with another node The external input terminal is connected to a multiplex signal input terminal of the insertion / demultiplexing means, and the multiplex signal output terminal of the insertion / demultiplexing means is connected to the external output terminal. Connected
The signal input terminal is connected to the switch means, and the external output terminal connected to the multiplexed signal output terminal is connected to the same node. A plurality of insertion / demultiplexing units each having an input terminal connected to a node connected to an output terminal of the switch unit and an external input terminal connected to the multiplexed signal input terminal connected to the same node; A separation output end of the multiplexing means and a separation output end of the insertion separation multiplexing means connected to a node different from the same node are connected to an input end of the joining means, and the joining means is connected to the signal output end; The control unit controls the switch unit based on a monitoring result of a signal input to the merging unit by the signal monitoring unit and a result of transmission and reception of control information with the other node. It is characterized in.

Further, according to the failure recovery method of the present invention, the first communication existing in a ring network having a communication path for a control message in which a spare resource for forming a bypass communication path is shared by a plurality of working signals. In the method for recovering communication failure from an input terminal of a network node device to an output terminal of a second communication network node device present in the ring network, the second communication network comprises:
When the node device detects the communication failure, a control message is exchanged between the first communication network node device and the second communication network node device using the communication path for the control message, The first
A communication network node device, the second communication network node device, and a communication network node device between the first communication network node device and the second communication network node device. By switching the switch means provided, if there is a low-priority communication path that hinders the configuration of the detour path, the communication path is disconnected, and the communication path is detoured in the opposite direction to the communication path or detoured in the same direction. A communication path, and recovers from the communication failure.

In another embodiment of the failure recovery method according to the present invention, a spare resource for forming a bypass communication path is shared by a plurality of working signals, and a spare resource is formed in addition to the communication path formed using the working resource. And a second communication network node existing in the ring network from an input end of a first communication network node device existing in the ring network having a communication channel for control messages. In the method of recovering from communication failure to the output terminal of the device, a priority determination method of switching to a detour in the opposite direction to the communication or a detour in the same direction as a switching destination is determined in advance, When the second communication network node device detects the communication failure, the first communication network node uses the communication path for the control message. Wherein a location second communication network
Exchanging control messages between the node devices, the first communication network node device, the second communication network node device, and the first communication network node device and the second communication network A communication network between the node device and the switching device provided in the node device, which prevents a detour having a first priority determined based on the priority determination method from being formed; The active communication path using the backup resource is disconnected, an attempt is made to switch to a detour having the first priority, and if it is possible to configure a detour having the first priority, the first communication is performed. If the communication failure recovery is completed by switching to the detour having the priority, and it is not possible to configure the detour having the first priority, The first communication network node device exchanges a control message between the first communication network node device and the second communication network node device by using a communication channel for the control message, and 2 communication network node device, and switching means provided in a communication network node device between the first communication network node device and the second communication network node device, thereby switching the communication network node device. Disconnecting the working communication path using the spare resource, which hinders the formation of a bypass having the second priority determined based on the priority determination method,
By switching to a detour having the priority of (i), the communication failure recovery is completed.

Further, according to the communication network maintenance method of the present invention, the spare resources constituting the bypass communication path are present from the input terminal of the first communication network node device existing in the ring network shared by a plurality of working signals. In a method for maintaining communication to an output end of a second communication network node device existing in a ring network, the first communication network node device, the second communication network device, and the first communication network device include: By using a switch provided in a communication network device and a communication network device located between the second communication network device and a detour for transmitting a signal in a direction opposite to the communication or a detour for transmitting a signal in the same direction. The communication is maintained by switching.

A twenty-first invention is a communication device, comprising:
A first input terminal to which a working signal from the first route is input, a first output terminal to which a working signal from the first route is output,
A second input terminal to which a spare signal from the first route is input, a second output terminal to which a spare signal from the first route is output, and a working signal from the second route. A third input terminal for inputting, a third output terminal for outputting a working signal from the second route, and a fourth input terminal for receiving a spare signal from the second route.
, A fourth output terminal from which a preliminary signal from the second path is output, a switch means, first and second insertion signal input terminals, and first and second branch signal outputs. A connection between the first, second, and fourth input terminals and the first branch signal output terminal; and a connection between the second, third, and fourth input terminals. A connection with the second branch signal output terminal, a connection between the first insertion signal input terminal and the first, second, and fourth output terminals, and a second insertion signal input terminal And the second, third, and fourth output terminals can be connected.

According to a twenty-second aspect, in the communication apparatus according to the twenty-first aspect, the third and fourth insertion signal input terminals to which the low-priority communication is input and the low-priority communication are output. The switching means also has a third and a fourth branch signal output terminal, and the switch means includes a connection between the second input terminal and the third branch signal output terminal, and a connection between the fourth input terminal and the fourth input terminal. , A connection between the third insertion signal input terminal and the second output terminal, and a connection between the fourth insertion signal input terminal and the fourth output terminal. It is characterized by being.

According to a twenty-third aspect of the present invention,
23. The communication apparatus according to claim 1, wherein a signal monitoring means is connected to the input terminal, the output terminal, the branch signal output terminal, and the insertion signal input terminal.

A twenty-fourth aspect of the present invention is the communication apparatus according to the twenty-third aspect, wherein the means for exchanging control / monitoring information with another node, and exchanging information from the signal monitoring means and exchanging the control / monitoring information. The switching control of the switching means is performed based on information from the performing means.

[0032] A twenty-fifth invention is a communication device, comprising:
A first input terminal to which a working signal from the first route is input, a first output terminal to which a working signal from the first route is output,
A second input terminal to which a spare signal from the first route is input, a second output terminal to which a spare signal from the first route is output, and a working signal from the second route. A third input terminal for inputting, a third output terminal for outputting a working signal from the second route, and a fourth input terminal for receiving a spare signal from the second route.
, A fourth output terminal from which a preliminary signal from the second path is output, a switch means, first and second insertion signal input terminals, and first and second branch signal outputs. And the switch means can arbitrarily set a connection state with each of the input terminals, each of the insertion signal input terminals, each of the output terminals, and each of the branch signal output terminals.

A twenty-sixth invention is a communication device, comprising:
A first input terminal to which a working signal from the first route is input, a first output terminal to which a working signal from the first route is output,
A second input terminal to which a spare signal from the first route is input, a second output terminal to which a spare signal from the first route is output, and a working signal from the second route. A third input terminal for inputting, a third output terminal for outputting a working signal from the second route, and a fourth input terminal for receiving a spare signal from the second route.
, A fourth output terminal from which a preliminary signal from the second path is output, switch means, first to fourth insertion signal input terminals, and first to fourth branch signal outputs. And the switch means can arbitrarily set a connection state with each of the input terminals, each of the insertion signal input terminals, each of the output terminals, and each of the branch signal output terminals.

A twenty-seventh invention is a communication device, comprising:
A first input terminal to which a working signal from the first route is input, a first output terminal to which a working signal from the first route is output,
A second input terminal to which a spare signal from the first route is input, a second output terminal to which a spare signal from the first route is output, and a working signal from the second route. A third input terminal for inputting, a third output terminal for outputting a working signal from the second route, and a fourth input terminal for receiving a spare signal from the second route.
, A fourth output terminal from which a preliminary signal from the second path is output, switch means, first to fourth insertion signal input terminals, and first to fourth branch signal outputs. And a fifth and sixth branch signal output terminals from which low-priority communication is input, and fifth and sixth branch signal output terminals from which low-priority communication is output. Is characterized in that the connection state with each of the input terminals, each of the insertion signal input terminals, each of the output terminals, and each of the branch signal output terminals can be arbitrarily set.

According to a twenty-eighth aspect, in the communication network according to the first aspect, the communication node means is an optical communication node means, the transmission path is an optical transmission path, and the communication is wavelength multiplexed optical communication. The first to fourth rings are rings formed by connecting optical signals in wavelength units.

In each node of the communication network according to the present invention, for example, an optical switch is connected so that the optical path on the clockwise working ring can be switched to either the clockwise backup ring or the counterclockwise backup ring. I do.

When a failure occurs in a transmission path or the like, the node that has detected the failure sends a failure recovery request to the transmitting node.
When the transmitting node that has received the failure recovery request can recover the failure by using one of the alternative path having the smaller number of hops among the alternative path configured on the clockwise backup ring and the alternative path configured on the counterclockwise backup ring ( For example, when a failure occurs in only one fiber of the working ring), the failure recovery is performed. If it is not possible to recover from a fault with a bypass path having a small number of hops (when a breakage fault occurs in a fiber of a plurality of rings at the same point), a method of recovering a failure using a bypass path having a large number of hops is used. Is used.

For example, first, an attempt is made to recover from a fault with a detour having a small number of hops, and if the fault does not recover after a certain period of time, a fault is recovered with a detour having a large number of hops. This can be realized. When performing maintenance, it is possible to switch to a detour with a small number of hops.

[0039]

FIG. 1 is a block diagram of a wavelength division multiplexing optical communication network according to a first embodiment of the present invention. In FIG. 1, reference numerals 105 to 109 denote optical communication network nodes. These nodes are connected by connecting the fibers to form a ring topology.
Fiber rings.

Reference numerals 101 and 103 denote working rings, 102 and 1
04 represents a spare ring. As shown by arrows in the drawing, the working rings 101 and 103 transmit optical signals in opposite directions, the working ring 101 and the protection ring 102 transmit optical signals in opposite directions, and the working ring 103 and the protection ring 104 transmit light signals in opposite directions. The optical signal is transmitted in the reverse direction.

From the node 107, the separated signals 111, 1
12 is output after being wavelength multiplexed and demultiplexed. Separation signal 111
Is an optical signal wavelength-division-multiplexed and separated from the working ring 101, and the separated signal 112 is an optical signal wavelength-division-multiplexed and separated from the working ring 103 (when no failure occurs). Also, the insertion signals 121, 12
2 is inserted as an optical signal. The insertion signal 121 is an optical signal to be inserted into the working ring 101, and the insertion signal 122
Is an optical signal to be inserted into the working ring 103 (when no failure occurs).

Assuming that two waves λ1 and λ2 in the 1.5 μm band are used as the main signal light for transmitting data in the ring, for example, the insertion signals 121 and 122 are transmitted to the working rings 101 and 103 which are opposite to each other. Since it is inserted, it is possible to allocate an optical signal having a wavelength of λ1. In addition to the main signal light, a 1.3 μm band control signal light (wavelength: λs) is transmitted in a wavelength multiplexed manner with the main signal light in order to exchange control signals between adjacent nodes. The control signal light is 1.3 μm.
Even if the m band is not used, if it is not used for the main signal light and can be separated from the main signal light, another wavelength (for example,
1.51 μm (currently, it cannot be used as main signal light because it is out of the band of the optical amplifier used for main signal light, and can be used as control signal light). In the above description, only the node 107 has been described.
Other nodes have similar functions.

FIG. 2 is a block diagram showing the configuration of nodes 105 to 109 used in the wavelength division multiplexing optical communication network of the present invention shown in FIG. In FIG. 2, node 200
Are external signal light input terminals 202, 204, 214, 216
And external signal light output terminals 201, 203, 213, and 215
And each is connected to another node using an optical fiber.

In the following, for convenience of explanation, the node 200 is
The connection relationship with another node will be described with reference to the position of the node 107 in FIG.

The optical fiber of the working ring 101 is connected from the node 109 to the external input terminal 204, and is connected from the external output terminal 213 to the node 108. The optical fiber of the spare ring 102 is connected to the external input terminal 214 from the node 108 and from the external output terminal 203 to the node 1.
09 is connected. The optical fiber of the working ring 103 is connected from the node 108 to the external input terminal 216 and from the external output terminal 201 to the node 109. The optical fiber of the spare ring 104 is connected to the external input terminal 202 from the node 109, and is connected to the external output terminal 215.
To the node 108.

Reference numerals 230 and 231 denote optical switch units for switching for failure recovery and maintenance. 217-220
Denotes an optical ADM unit, which wavelength-multiplexes and demultiplexes the input wavelength-division multiplexed signal light in the 1.5 μm band to output an optical signal toward the branch output terminal, or converts the wavelength-multiplexed signal light input from the external input terminal. Are multiplexed with the optical signal from the insertion end and output to the output end 201.

Reference numerals 242, 244, 246, and 248 denote control signal separators for separating optical signals input from the external input terminals, and converting the 1.5 μm wavelength-multiplexed main signal light into optical ADM units 217 to 220, respectively. And the control signal light (λs) of 1.3 μm is input to the monitoring control device 221. As a control signal separator, a wavelength of 1.3 μm band and 1.5 μm
It is possible to use a WDM coupler that separates the wavelengths in the m band.

Reference numerals 205 and 208 denote demultiplexing output terminals for outputting an optical signal (λ1) demultiplexed by wavelength division.
Reference numeral 2 denotes a separation input end for inputting a single-wave optical signal (λ1), and includes a SONET terminator and an ATM switch (for example, TH Wu, “Fiber Network Service Surviva”).
other network devices are connected, such as bility, “Artech house, 1992.” Here, for simplicity of explanation, an example in which only one wave (λ1) is separated and input is shown. The number of signals to be separated and output and the number of signals to be separated and input need not be 1. When there are a plurality of signals to be separated and inserted, a plurality of optical switch units may be arranged in parallel and connected to the optical ADM unit.

Reference numerals 222 to 225 denote optical splitters.
A part (for example, 10% of optical power) of an optical signal output by wavelength division multiplexing and demultiplexing from the M unit is tapped and connected to the monitoring controller 221, and most of the remaining optical signal (for example, 90%
Is output to the optical switch units 230 and 231.

Reference numeral 221 denotes a supervisory controller,
The optical signal tapped at 5 is monitored, and the optical ADM unit 217 to
220, a switching control signal is transmitted to the optical switch units 230 and 231. The monitoring controller 221 includes an interface between an optical signal and an electric signal, a memory, a CPU, and the like. In FIG. 2, the electric signals related to the control in the node are indicated by broken lines.

By installing an optical receiver at the input end of the monitoring controller 221, the bit error rate of the input optical signal is monitored to monitor the transmission quality of the optical signal (for example, a SONET frame is used as the optical signal. And monitoring the bit error rate by monitoring the B1 byte; TH Wu, “Fiber Network Service Survivab
ility, "Artech House, 1992). The monitoring controller 221 is connected to the optical switch units 230 and 231, and the optical ADM units 217 to 220, and controls the switching between them based on information of the monitoring control unit. I do.

External output terminals 201, 203, 213, 21
The control signal multiplexers 241, 243,
245 and 247 are connected, and a control signal light (1.3 μm band) transmitted from the monitoring controller 221 to another node is transmitted.
And a main signal light (1.5 μm band). As the control signal multiplexer, a WDM coupler can be used similarly to the control signal separator.

By superimposing and separating the control signal light on the main signal light using the control signal separator and the control signal multiplexer, it is possible to exchange control signals with other nodes. Since the control signal light from the other node is input to the monitoring controller 221 and the optical signal monitoring result of the own node is also obtained, the switching based on the control information from the other node and the monitoring of the optical signal of the own node are performed. Both switching based on the result is possible.

The control signal light can carry a destination node, an optical path name, and control contents as information. For example, when assigning information to the position and value of a framed bit such as SONET section overhead, the first 8 bits of the framed bit string are assigned to the destination node name, and the next 8 bits are assigned to the failure recovery control message. Can be assigned to By using a frame configuration in which a total of 16 bit strings are connected by time division multiplexing for the number of wavelengths, optical path switching request messages for the number of wavelengths can be transmitted collectively.
This message includes an ET path disconnection instruction and a disconnection confirmation message.

As shown in the node configuration of FIG. 2, these messages always terminate between nodes, so that information can be transferred for each node. Since the message relating to the working ring 101 and the message relating to the protection ring 104 are transmitted in the same direction, by further multiplexing them for a further time, the information transferred on the working ring 101 and the information transferred on the protection ring 104 are both transmitted. Can be transferred on the ring. Similarly, the message to be transferred on the working ring 103 and the backup ring 10
2 can be forwarded on each ring.

Although the control signal light is electrically terminated between adjacent nodes, the control message includes the destination node,
Since the communication partner node can be specified, a communication path for a control message between the two nodes can be configured by this control message.

Next, each block in the node 200 will be described. FIG. 3 is a block diagram of the optical switch unit (230 or 231) used in FIG. In FIG. 3, the optical switch unit 300 includes input / output terminals 301 and 304.
308, 1 × 2 optical couplers 314, 315 and 1 ×
It is composed of three optical switches 309 and 312. The input / output terminals 301 and 304 to 308 are connected to, for example, the optical switch unit 2.
When used as 30, the output terminals 301 and 304 are
Reference numerals 305 to 308 are used as input terminals, and the optical switch unit 23 is used.
When used as 1, 301 and 304 are input terminals, 30
5 to 308 are used as output terminals.

When the optical switch section 300 is used as the optical switch section 231 of FIG. 2, the insertion end 209 is connected to the input / output end 301, the insertion end 212 is connected to the input / output end 304, and the input / output end 308 is connected to the optical input / output end 308. The input / output terminal 307 is connected to the optical ADM unit 219, and the input / output terminal 306 is connected to the optical ADM unit 2
18, the input / output terminal 305 is connected to the optical ADM unit 217.

By employing the above connection relationship, a 2 × 4 switch function having the following switching function is realized using the optical switch unit 231. That is, the optical signal input to the insertion end 209 is
In addition to the spare ring 102, it can be transmitted to the spare ring 104. Similarly, the optical signal input to the insertion end 212 can be transmitted to the spare ring 102 in addition to the working ring 103 and the spare ring 104.

When the optical switch unit 300 is used as the optical switch unit 230 in FIG. 2, the optical splitter 222 is at the input / output end 308, the optical splitter 223 is at the input / output end 307, and the optical splitter 224 is at the input / output end. An optical branching device 225 is connected to the terminal 306 and the input / output terminal 305, respectively, to realize a 4 × 2 switching function having the following switching function. That is, optical signals from any of the working ring 101, the spare ring 102, and the spare ring 104 can be output to the separation output terminal 205. Similarly, any of the working ring 103, the spare ring 104, and the spare ring 102 can be output. Can be output to the separation output end 208 as well.

FIG. 4 shows the 1 × 3 optical switch 309 of FIG.
FIG. 3 is a block diagram illustrating an example of a configuration of a 312. In FIG. 4, the 1 × 3 optical switch 400 includes input / output terminals 401 to 40.
4. Optical gate type optical switches 405 to 407 and optical coupler 408. As the gate optical switches 405 to 407, a mechanical optical switch can be used. Further, as the optical coupler 408, a fiber fusion-type optical coupler can be used.

FIG. 5 shows the optical ADM unit 2 used in FIG.
It is a block diagram which shows the example of a structure of 17-220. In the optical ADM section 500 of FIG. 5, reference numeral 501 denotes a multiplexed signal input terminal for inputting a wavelength-multiplexed signal light, and reference numeral 506 denotes a multiplexed signal output terminal for outputting a wavelength-multiplexed optical signal. 50
Reference numerals 2 and 503 denote demultiplexed signal output terminals for wavelength multiplexing and demultiplexing the optical signal input to the multiplexed signal input terminal 501. 5
Reference numerals 04 and 505 denote insertion signal input terminals, which input optical signals of corresponding wavelengths to the optical ADM unit.

Reference numeral 514 denotes a wavelength multiplexing / demultiplexing device, and 507 denotes a wavelength multiplexing / demultiplexing device. AWG (Arrayed-Waveguide Grating: for example, K. Okamoto et al, “Fabrication of unequalc.
hannel spacing arrayed-waveguide demultiplexer mod
ules, "Electron. Lett, 1995, vol. 31, no. 17, p.
p. 1464-1465) can be used. If the wavelength multiplexing device and the wavelength multiplexing / demultiplexing device have a function of multiplexing wavelengths or performing wavelength multiplexing / demultiplexing, AWGs are not necessarily used.
There is no need to use. For example, a diffraction grating or a combination of a fiber Bragg grating (a filter having a periodic structure in a fiber) is provided with a function of multiplexing wavelengths and wavelength division demultiplexing. Applicable.

Reference numerals 510 and 511 denote optical gate switches, and it is possible to use a mechanical optical switch or a gate switch using a semiconductor optical amplifier. 512, 513
Is an optical splitter that splits the power of the input light into two, outputs one to separate output terminals 502 and 503, and outputs the other to optical gates 510 and 511, respectively.
Reference numerals 508 and 509 denote optical couplers, which are inserted signal input terminals 5.
A signal obtained by combining the signal lights from the optical gates 04 and 505 and the outputs from the optical gates 510 and 511 is output.

The wavelength multiplexing / demultiplexing device 507 is connected to the optical coupler 50.
The wavelength multiplexed light obtained by multiplexing the outputs from the signals 8 and 509 is output. The optical couplers 508 and 509 change the optical gate 510 and the optical gate 511 to an ON state or an OFF state, thereby transmitting a signal to be input to the wavelength-multiplexed wave combiner 507.
It is possible to select between the output from the optical splitters 512 and 513 and the output from the insertion signal input terminals 504 and 505 (the insertion signal input terminal side depends on the operation of the optical switch unit 231). Switching between On / Off states is possible). In the configuration of FIG. 5, the optical splitters 512 and 513
Therefore, an optical signal is always output to the branch signal output terminal.

The optical ADM unit 500 is different from the optical ADM unit 2 in FIG.
20, the control signal separator 244 is connected to the multiplexed signal input terminal 501, the multiplexed signal output terminal 506 is connected to the control signal multiplexer 245, and the optical switch unit 231 is used.
Is connected to the insertion signal terminal 504 and the separated signal output terminal 50
3 is connected to the optical splitter 225. Other optical ADM units perform the same connection.

By using the above-described node configuration of FIG. 2 for each node of FIG. 1, each node, when an optical signal is inserted from the insertion end 209, the working ring 101,
Optical signals can be transmitted to both the spare ring 102 and the spare ring 104. Similarly, insertion end 2
When an optical signal is inserted into the ring 12, the optical signal can be transmitted to any of the working ring 103, the spare ring 104, and the spare ring 102.

The branch output terminal 205 has the current ring 1
01, the spare ring 102, and the spare ring 104 can be output. Similarly,
The branch output terminal 208 can output an optical signal from any one of the working ring 103, the spare ring 104, and the spare ring 102. Therefore, the optical switch units 230 and 231, the optical ADM unit 21 of each node
By switching between 7 and 220, it is possible to configure a detour optical path on either the clockwise backup ring or the counterclockwise backup ring for a failure of the working optical path on a certain working ring. .

Next, the failure recovery operation when the network of FIG. 1 is configured using the node configuration of FIG. 2 will be described with reference to FIGS.

As a method of allocating a path on the ring, there are a method of allocating a clockwise path and a method of allocating a counterclockwise path. Either of these optical paths has a smaller or equal number of hops. Hereinafter, the one with a smaller number of hops is called a short path, and the one with a larger number of hops is called a long path. When the number of hops is equal, the one transmitting in the same direction as the working optical path is called a short path, and the path transmitting in the opposite direction to the working optical path is called a long path.

When recovering from a failure of a ring composed of nodes having the configuration shown in FIG. 2, since the insertion signal and the separation signal can be connected to either the clockwise or counterclockwise spare ring, a short It is possible to select whether to use a method of configuring a path to perform failure recovery or a method of configuring a long path to perform failure recovery.

More specifically, in FIG.
In response to the failure of the working optical path 601 on the route from the node 106 to the node 109 to the node 107 on the
04 (counterclockwise transmission) using node 106 → node 10
9 → bypass path of the path of node 107 (backup optical path 60
2: a short path) to form a fault recovery, and the node 1 using the spare ring 102 (clockwise transmission).
There is a method of configuring a bypass path (backup optical path 603: long path) of the route from 06 → node 105 → node 108 → node 107.

When an ET path is configured on the spare ring, if possible, it is possible to reduce the number of ET paths to be separated by configuring a short path and performing fault recovery.
For example, if all the optical paths having one hop number on the spare ring have a wavelength of λ1 and all paths having one hop number are used as ET paths, the spare optical path 602 (short path) is configured. In the case of performing a fault recovery by performing the operation, it is necessary to disconnect two ET paths.
(Long path) for recovery from failure
It is necessary to separate ET paths.

Therefore, in the ring network having the node configuration shown in FIG. 2, considering the efficiency of use of the ET path at the time of a failure, the priority of the failure recovery is determined by the detour to the short path and the long recovery. If the failure is recovered by detouring to the path, the effect on the ET path (the number of ET path disconnections) at the time of failure recovery can be reduced.

Hereinafter, a ring having the node configuration shown in FIG.
A failure recovery method that reduces the influence on the ET path using a network will be described.

FIG. 6 shows control signals and operation steps in each node when a detour to a short path is performed after a failure occurs in the network of FIG.

Reference numeral 601 denotes a working optical path (wavelength: λ1) for transferring a working main signal light, which is transmitted from a node 106 (source node (transmission node): hereinafter abbreviated as S node) to a node 109;
And is terminated at a node 107 (destination node (reception node): hereinafter abbreviated as D node).
Normally, the spare ring is not used, and an optical path is set in the spare ring and used only when a failure occurs.
The setting of the optical path in the working ring and the spare ring is realized by switching the switching state of the optical switch units 230 and 231 and by switching the switching state (On state / Off state) of the optical gates 510 and 511 in FIG. .

Now, on the spare ring 104, the node 10
It is assumed that an ET path of wavelength λ1 is configured from 9 to the node 107. In such a state, the node 10
The failure recovery operation when a failure occurs only in the optical fiber of the working ring 101 between the node 6 and the node 109 will be specifically described.

In this case, since the optical fiber is broken,
The optical path 601 stops arriving at the terminal node 107. First, the monitoring controller 221 in the node 107 detects that the optical signal branched from the optical splitter 225 does not come, and recognizes the failure of the optical path 601. (Step 1).

When the supervisory controller 221 detects a failure in the working optical path 601, it attempts to recover from the failure. At this time, as described above, first, it tries to recover from the failure by detouring to the short path. In order to disconnect the short path (backup path 602) on the backup ring 104, messaging is performed to the concerned node.

Since an ET path having a wavelength of λ1 is used between the node 109 and the node 107 as an ET path related to the construction of the backup optical path 602, first,
Switch so that the node 107 does not receive the ET path,
An instruction to stop transmission of the ET path is transferred to the node 109 using a 1.3 μm band control signal light (step 2). Specifically, after receiving the control signal light, the node 109
By switching the gate switches in the optical switch units 230 and 231 in the node 107 and the node 107, the ET path can be separated.

When the node 107 as the D node confirms the disconnection of the ET path, the request to transmit the main signal light to the backup ring 104 is transferred to the node 106 as the S node (step 3). The request message first arrives at the node 109. When the node 109 recognizes that the request destination of the arrived message is the node 106 and is not addressed to its own node, the node 109 does not process any information and proceeds to the next. Forward to the node as is.

When the node 106 receives a request to switch to its own node in a state where signal light is transmitted only to the working ring 101 in order to form the working path 601, the node 106 according to the request receives the request. The optical switch is switched so that light is also transmitted (step 4). Specifically, an optical signal is input to the input / output terminal 301 in FIG. 3, the input / output terminal 308 is connected to the working optical ring 101, and the spare ring 104 is connected to the input / output terminal 306. When the optical switch 309 has the configuration as shown in FIG. 4 and no fault occurs, only the gate type optical switch 407 is in the On state, but the gate type switch 405 is also in the On state. Switch so that

When the operation in step 4 is completed, the node 106 transfers the fact to the D node (node 107) using the 1.3 μm band control signal light (step 5).
If the optical ADM unit at the node 109 in the middle is not in a switch state for forming the backup optical path 602, switching is performed to achieve such a state. Specifically, on / off switching of the optical gate of the optical ADM unit 500 of the node in the middle is performed.

When the node 107 receives the content of step 5, the node 107 switches to receive the optical signal from the spare ring 104 (step 6). Specifically, assuming that the optical switch unit 230 in FIG. 2 has the configuration in FIG. 3, a state in which an optical signal from the working ring 101 is being received (only the gate type optical switch 407 in FIG. 4 is in an On state). The state can be realized by switching to a state in which the optical signal from the standby ring 104 is received (only the gate type optical switch 405 is in the On state in FIG. 4). In step 6, the D node 107 recognizes the recovery of the failed optical path.

After the end of step 6, the fact is transferred to S node 106 using the control signal light (step 7). S
When the operation performed in step 6 is confirmed at the node 106,
The S node recognizes the completion of the failure recovery (step 8).

In the above operation example, the case where a failure occurs only in the working optical ring 101 is shown. In this case, the failure recovery is performed by switching to the short path configured on the spare ring. The number of ET paths to be separated can be reduced.

Next, the working ring 101 and the spare ring 10
The operation in the case where a break failure occurs in both the fibers 4 will be described with reference to FIG.

In this case, the same operation as in FIG. 6 is performed up to step 5. However, since the fiber breakage fault has occurred in the spare ring 104, the content to be transferred in step 3 is not transferred to the D node 107. Therefore, the operation described with reference to FIG. 6 cannot be performed in the node 107, and the completion of the failure recovery in step 8 in FIG. 6 cannot be confirmed. Each node holds in advance the time required until step 8 in FIG. 6, and if the failure recovery check in step 8 in FIG. 6 cannot be performed within that time, the detour to the short path is performed. It is determined that the recovery from the failure due to is impossible, and the failure recovery operation by detour to the long path is started.

In order to recover from a failure by detouring to the long path, first, the spare ring 1 constituting the long path
The ET path using λ1 used on 02 is disconnected (step B6). Thereafter, an optical signal is transmitted to the spare ring 102 (step B7). More specifically, the node 106 has the same configuration as the node 200 in FIG. 2, and will be described with reference to FIGS. 2, 3, and 4. Before the failure, only the gate type optical switch 407 was in the ON state. When trying to make a detour to the short path (step 4)
Gate type optical switch 407 and gate type optical switch 405
Was turned on. In step B7, the gate type optical switches 407 and 406 are set to the On state because the detour to the long path is attempted.

When the operation in step B7 is completed, the fact is transferred to the D node using the control signal light (step B7).
8). Since the switching by the detour in the short path direction cannot be performed, the transfer of the control information by the control signal light is also performed along the long path direction. When the optical ADM unit of the node in the middle of the messaging is not configured to form the backup optical path 603, switching is performed to configure the backup optical path 603. Specifically, the optical gate 51 of FIG.
By switching 0, the optical gate through which λ1 passes in the spare optical ring 102 is turned on.

The D node 107 that has received the message in step B8 switches to receive the optical signal from the backup ring 102, and forms a detour path using a long path (step B9). Specifically, FIGS. 2, 3, and 4
Can be realized by replacing only the gate type optical switch 406 in FIG. 4 with the ON state. Finally, the S node (node 106) is notified that the failure recovery has been completed (step B).
10), the S node recognizes that the failure recovery has been completed, and the failure recovery operation ends (step B11).

FIG. 8 shows a sequence chart of the inter-node communication and the operation in the node in the case of the recovery from the failure due to the detour to the short path (FIG. 6). The vertical axis is the time axis, and the lower the time, the later the time. Also,
FIG. 9 shows a sequence chart of the inter-node communication and the operation in the node in the case of the failure recovery by the detour to the long path (FIG. 7).

As described above, in the ring network having the node configuration shown in FIG. 2, if a detour to a short path is possible according to the type of fault,
This section describes the operation to recover from a failure by detouring to a path, and to detour to a long path if detouring to a short path is not possible. Therefore, it is possible to reduce the number of ET paths to be disconnected at the time of recovery from a failure, and to configure a ring network with high ET path use efficiency.

Also, in maintenance, it is not necessary to detour to a long path, and maintenance can be performed by detour to a short path. Also, there is an effect that the use efficiency at the time of maintenance increases. Since high speed is not required during maintenance,
This can be performed without using signaling for protection.

Further, since the short path passes through the same path as the working path, by making a detour to the short path,
The delay difference is small, and the instantaneous interruption time at the time of switching is short. Since the delay difference is small, the memory capacity required for instantaneous interruption switching can be reduced.

In addition, since the detour to the long path is not always performed at the time of recovery from a failure, if the recovery from the failure is possible by the detour to the short path, the number of nodes involved in switching is reduced. Time is reduced. This is particularly effective for very long haul rings.

Further, since there are two detour candidates at the time of failure, a short path and a long path, the reliability is improved. In particular, laying the fibers of the ring transmitting signals in the same direction in different fiber conduits improves reliability.
For example, when laying a fiber on a highway, if fibers transmitting signals in the same direction are dispersed on both sides of the highway, even if one fiber is cut, there is a high possibility that the other fiber is not cut. The possibility of switching to the short path is increased.

In the above description, the working ring 1 is
The case where a failure has occurred in 01 and 103 has been described. However, even when a failure has occurred in the optical fibers of all the rings at the same point, the failure recovery can be performed in the same manner. However, depending on the location of the fault, the direction in which control messages are transmitted may be along a short path or a long path.
What happens along the path is different.

As long as the control message can be transmitted, the control information may be transmitted to either side. However, when the control message is transmitted in both directions, it may be possible to transmit the control message along a short path. If the control message arrives at the destination node first,
If the path becomes valid but control messages cannot be transferred in the short path direction due to a failure, the transmission of control messages along the long path becomes valid.

In this embodiment, the method for recovering from the failure of the optical signal of λ1 has been described. However, if the configuration and method of the present invention are used, a failure unit can be provided for any single failure in a wavelength multiplexed system. All optical paths (source nodes,
It is possible to perform a failure recovery of the terminal node (including different end nodes). Hereinafter, this will be described.

When a single fault occurs in a fiber or a node, a fault occurs in the number of wavelength-multiplexed optical paths.
Since the protection ring is shared by the working signals of the working ring, the protection ring is not used when no failure occurs. Therefore, if the same wavelength as that of the working optical path is assigned to the spare ring, the spare optical path can be assigned without wavelength collision (that the same wavelength is assigned to the optical path in one optical fiber and cannot be separated). is there.

Therefore, for any single failure, the failure of all the optical paths passing therethrough can be recovered. In addition, even when multiple failures occur, it is possible to cope if either the short path or the long path can be configured.

As described above, recovery from the failure of the working optical path of the working ring 101 is performed by using the protection ring 102 which is a shared protection resource, or
The method of performing the failure recovery using the protection ring 104 and the node configuration have been described. The working ring 103 (signal transmission in the opposite direction to the working ring 101) and the protection ring 10
4. The same node configuration and failure recovery method can be applied to the spare ring 102. After the failure recovery operation, the failure point of the optical fiber is confirmed, and when the repair of the working ring 101 is completed by fusion splicing of the optical fiber, the spare resources are shared, so that in preparation for the next failure, the working fiber is used. If the optical path 601 is restored to be transmitted using the working ring 101, the spare resources can be used effectively.

Next, a second embodiment will be described. In the first embodiment, the configuration and method of the four-fiber ring have been described, but in the second embodiment, the case of the two-fiber ring will be described. A two-fiber ring has a clockwise ring and a counterclockwise ring. λ1
It is assumed that four wavelengths .lambda. To .lambda.4 are wavelength multiplexed, and .lambda.1 and .lambda.2 are allocated to the wavelength of the working optical path and .lambda.3 and .lamda. Λ1 in the clockwise ring,
The spare resources corresponding to the working optical path configured using λ2 can be assigned to λ3 and λ4 of the counterclockwise ring, and the working optical path configured using λ1 and λ2 in the counterclockwise ring. Can be allocated to λ3 and λ4 of the clockwise ring.

Therefore, a two-fiber ring can be considered in the same way as a four-fiber ring. The resources of λ1 and λ2 of the clockwise ring correspond to the working ring 101 of FIG. 1, and λ3 and λ4 of the counterclockwise ring correspond to the spare ring 10 of FIG.
2, the left-handed rings λ1 and λ2 correspond to the working ring 103 in FIG. 1 and the right-handed rings λ3 and λ4 correspond to the spare ring in FIG. 1. Logically, the first embodiment. It can be understood that the same operation as that of the four-fiber ring described in (1) is possible.

The node configuration uses λ1 and λ2 for the working optical path and λ3 and λ4 for the standby optical path.
Compared to the four-fiber node configuration of FIG.
1, input end 202, input end 216, output end 215, light A
The output terminals of the optical switch unit 231 are all connected to the optical ADM units 219 and 220 without using the DM units 217 and 218.
A wavelength converter is provided between the optical switch unit 231 and the optical ADM units 219 and 220 and between the optical switch unit 230 and the optical ADM units 219 and 220.

When the path of the working system λ1 is input to the standby system, wavelength conversion is performed through a wavelength converter of λ1 → λ3,
Match the wavelengths of the working system and the standby system. As a wavelength converter, use a method that converts an optical signal to an electrical signal once using a photodiode, and then modulates the laser light of a desired wavelength using the electrical signal to convert it to another wavelength. Is possible.

By using the second embodiment, the same effects as in the first embodiment can be obtained. The difference from the first embodiment is that the number of fibers used (the number of rings) is half. Therefore, when the optical fiber laying cost accounts for a large part of the cost, especially when only two fiber rings can be constituted, it is particularly effective. The point is that it gets bigger.

In the second embodiment, a wavelength converter having a fixed wavelength output is inserted in the node configuration shown in FIG. 2. However, it is obvious that the present invention can be applied to a wavelength converter having a variable wavelength output. It is. In this case, the method of allocating the backup optical path can be flexibly changed, so that it is more effective to cope with multiple failures than to use a fixed wavelength converter.

In the second embodiment, a method of converting an optical signal into an electric signal and then converting it again into an optical signal is used as a wavelength converter. It is obvious that the present invention can be implemented even by using the cross gain modulation effect and the wavelength converter using the cross phase modulation effect.

Next, a third embodiment will be described as an application system of the present invention. The third embodiment is a case of a two-fiber ring, as in the second embodiment, and the first ring and the second ring transmit optical signals in opposite directions. The wavelength for transmitting the working signal of the first ring is λ
1, λ2 is used. As a backup resource, the wavelength λ of the second ring for the working optical path of the wavelength λ1 of the first ring
1. Second working optical path of wavelength λ2 of first ring
Is used. Λ3 and λ4 are used as wavelengths for transmitting the working signal of the second ring. As spare resources, λ3 of the first ring is used for the working optical path of the wavelength λ3 of the second ring, and λ4 of the first ring is used for the working optical path of the wavelength λ4 of the second ring.

As described above, if the same wavelength is assigned to the two-fiber ring as the working and protection wavelengths for the rings that transmit in opposite directions, it is necessary to use the wavelength converter used in the second embodiment. Disappears. In the second embodiment, it is necessary to switch and transmit the working optical path λ1 and the protection optical path λ3 at a certain source node. However, according to the third embodiment, the wavelength used for the working optical path is changed. This is because there is no need for wavelength conversion since the wavelengths used for the backup optical path are the same.

When the third embodiment is used, the same effects as those described in the second embodiment are obtained, except that the wavelength converter becomes unnecessary.

In the embodiment of the present invention, the optical switch unit 2
Although described using the configuration of FIG. 3 as 30, 231,
Various configurations other than the configuration of FIG. 3 are conceivable for the optical switch unit.

FIG. 10 shows another example of the configuration of the optical switch section, which is prepared for a failure of the 1 × 3 optical switches 309 and 312. In FIG. 10, 1010, 10
11 is an optical coupler; 1001 to 1008 are input / output terminals;
09 and 312 are 1 × 3 optical switches, 310 and 311 are 1
× 2 optical switch. In this configuration, the optical coupler 10
The optical signal is divided into two by 10 and 1011, and also connected to the 1 × 2 optical switches 310 and 311 and the 1 × 3 optical switch 3
09, 312 failures were addressed.

When the optical switch unit 1000 is used as the optical switch unit 231, the input / output terminal 1005 has a working optical signal forming a working optical path on the working ring 101, and the input / output terminal 1008 has a direction opposite to 1005. A working optical signal to be transmitted and constituting a working optical path is inserted into the working ring 103, and a working optical signal input to 1008 is inserted into the input / output terminal 1007.

If a failure occurs in the optical switch 309, the optical switch 310 is used instead. However, in the case of a double failure (a failure of the optical switch 309 and a failure of the long path), since the optical switch 310 is not connected in the short path direction, it cannot handle short path switching.

FIG. 11 shows another example of the configuration of the optical switch unit configured to cope with the double failure. In FIG. 11, the 1 × 3 optical switches 309 and 312 are duplicated in preparation for the failure in the configuration of FIG. 3, and the optical switch 310 and the optical coupler 314, Since the optical switch 311 and the optical coupler 315 are connected, the optical switch 309,
Even if a failure occurs in 311, the optical switches 310, 311
Can completely substitute for each other (ie,
The optical switches 310 and 311 are respectively
9 and 312). Therefore, it is possible to cope with a failure of an optical switch in addition to a failure of a fiber on a ring.

FIG. 12 shows another example of the configuration of the optical switch section. In the optical switch of FIG. 10, the number of input / output terminals on the insertion or branch side is changed to four instead of two. . That is, in FIG. 10, the optical signal input to the input / output terminal 1001 is branched by the optical coupler 1010 to form a standby system. However, the configuration is applicable to a system having the function outside the optical switch unit. is there. I / O terminal 120
The optical signal input to 2 is the same as the input / output terminal 1201 and is a standby optical signal of the input / output terminal 1201. Similarly, an optical signal input to the input / output terminal 1203 is the same as the input / output terminal 1204 and is a standby optical signal of the input / output terminal 1204.

FIG. 13 shows another example of the configuration of the optical switch section. In the optical switch shown in FIG. 11, the number of input / output terminals on the insertion or branch side is four instead of two. . That is, in FIG. 11, the optical signal input to the input / output terminal 1101 is split by the optical coupler 1010 to form a standby system. However, the configuration is applicable to a system having the function outside the optical switch unit. is there. I / O terminal 130
The optical signal input to 2 is the same as the input / output terminal 1301 and is a standby optical signal of the input / output terminal 1301. Similarly, the optical signal input to the input / output terminal 1303 is the same as the input / output terminal 1304 and is a standby optical signal for the input / output terminal 1304.

FIG. 14 shows still another example of the configuration of the optical switch section. In FIG. 14, 1401 to 140
Reference numeral 8 denotes an input / output terminal, 1411 to 1414 denote 1 × 4 optical couplers, and 1415 to 1418 denote 1 × 4 optical switches. According to this switch configuration, since a 4 × 4 non-blocking switch is configured, the switching destination is limited in FIG.
The degree of freedom of switching is increased as compared with the switch configuration of FIG. Furthermore, if the configuration is made using 2 × 4 optical switches, the degree of freedom of switching can be further increased.

Also, various configurations other than the configuration shown in FIG. 4 are conceivable for the form of the 1 × 3 optical switch.

FIG. 15 shows another configuration example of the 1 × 3 optical switch. In FIG. 15, the 1 × 3 optical switch 1500 includes input / output terminals 1501 to 1504 and 1 × 2 optical switches 1507 and 1508. In this configuration example, since the 1 × 3 switch function is realized by combining the 1 × 2 switches, the cost can be reduced. In general, a 1 × 1 switch does not use one input / output terminal of a 1 × 2 switch (eg, a mechanical optical switch), and one 1 × 2 switch and one 1 × 1 switch are used. Since the costs are almost the same, there is an effect that the cost of the 1 × 3 switch is reduced as compared with FIG.

FIG. 16 shows another configuration example of the 1 × 3 optical switch. This 1 × 3 optical switch 1600 is
In the 1 × 3 optical switch of FIG. 4, the configuration is such that the gate type optical switch 405 is omitted. By using the 1 × 3 optical switch 1600 in combination with, for example, the 1 × 3 optical switch 400 in FIG. 4, the present invention can be applied.

That is, 1 in the optical switch section of the S node
Even if the S node transmits the optical signal to the working ring at the time of recovery from a failure and the D node selects the optical signal from the spare ring at the detour, there is no problem even if the configuration of FIG. 16 is used for the × 3 switch. Conversely, even if the configuration of FIG. 16 is used for the 1 × 3 switch in the optical switch unit of the D node, the configuration of FIG. 4 is used for the S node, and the D node is always connected to the working ring, Thus, the optical signal can be prevented from being transmitted to the working ring, and thus the present invention can be applied to the present invention.

Therefore, the configuration shown in FIG.
The present invention can be implemented by using any of the configurations using the configuration of FIG. 16 on the D node side, the configuration of FIG. 16 on the D node side, and the method of using the node of FIG. 4 on the S node side. The use of the configuration of FIG. 16 has an advantage that the number of gate switches used can be reduced as compared with the configuration of FIG.

When the configuration shown in FIG. 16 is used for an S node, in order to prevent the working optical signal from arriving at the terminal node in the event of a failure, only the wavelength of the optical signal in which a failure has occurred at an intermediate node is required. Can be used.

FIG. 17 shows another configuration example of the 1 × 3 optical switch. In FIG. 17, 1700 is 1 × 3
Optical switches, 1701 to 1704 are input / output terminals, 1711
Is a gate type optical switch, 1712 is a 1 × 2 optical switch,
Reference numeral 408 denotes an optical coupler. Also in this configuration example, the number of switches can be reduced as compared with the optical switch of FIG. 4, and cost can be reduced.

FIG. 18 shows still another configuration example of the 1 × 3 optical switch. In FIG. 18, 1800 is 1
× 3 optical switches, 1801-1804 are input / output terminals, 18
Reference numeral 12 denotes a 1 × 2 optical switch, and reference numeral 408 denotes an optical coupler.
This 1 × 3 optical switch 1800 corresponds to the 1 × 3 optical switch in FIG. 16, and the two gate switches in FIG. 16 are replaced with one 1 × 2 switch, so that the cost can be further reduced. Can be achieved.

Also, the configuration of the optical ADM unit is shown in FIG.
In addition to the above configuration, for example, the configuration of FIG. 19 or FIG. 20 can be used.

The optical ADM unit 1900 shown in FIG. 19 has a 2 × wavelength multiplexing / demultiplexing unit 514 and a wavelength multiplexing / multiplexing unit 507.
2 optical switches 1908 and 1909 are inserted, and the insertion signal input terminals 1902 and 1903 and the separated signal output terminal 190 are inserted.
4, 1905. FIG.
In the above configuration, the optical signal is always output to the separation signal output terminal. However, in this configuration, when the distribution selection type (multicast type) is not used as the 2 × 2 optical switch, 2 × 2
It is output to the separation signal output terminal only when the optical switch is in the cross state.

In the optical ADM unit 2000 shown in FIG.
A part of the output of the wavelength division multiplexer 514 is directly connected to the wavelength division multiplexer 507, and the other part is separated signal output terminal 200.
It is directly connected to 2.

For example, in the node of FIG. 2, the configuration of FIG. 20 is used as the configuration of the optical ADM unit connected to the working ring, and the configuration of FIG. 5 is used as the optical ADM unit connected to the spare ring. Although the configuration of the working optical path is fixed, the configuration of FIG. 5 is used for the standby system, so that the configuration can be changed, and it is possible to perform fault recovery and maintenance. According to this configuration, since the optical switch and the optical coupler required for the optical switch are not used in the active optical ADM unit, the cost is reduced accordingly.

The optical AD connected to the working ring
A configuration in which not all the connections in the M unit are fixed connections but only some of the connections in the optical ADM unit are fixed connections as shown in FIG. 20 and other connections are variable using an optical switch 510 as shown in FIG. In this case, the effect of reducing the number of optical switches and the like for the fixed connection portion can be obtained.

As shown in FIG. 22, a device (integrated optical switch unit) constituted by integrating the optical switch unit 230 and the optical switch unit 231 of FIG.
The present invention can be realized without any trouble even if connected to the M section. In FIG. 22, reference numerals 2201 and 2202 denote external output terminals, 2203 and 2202.
Reference numeral 204 denotes an external input terminal to which another network device is connected. Reference numerals 2205 to 2208 denote output terminals connected to the multiplexer. Reference numerals 2209 to 2212 denote input terminals connected from the demultiplexer. Reference numerals 2217 to 2220 denote optical couplers, and reference numerals 2213 to 2216 denote 1 × 3 optical switches. 2212 and 2208 are connected to the clockwise working ring, 2211 and 2207 are connected to the clockwise spare ring, 2210 and 2206 are connected to the counterclockwise spare ring, and 2209 and 2205 are connected to the counterclockwise working ring. Thus, the failure recovery of the present invention can be performed.

A configuration different from that of FIG. 22 will be described with reference to FIG. FIG. 22 shows that the signal input from the optical ADM unit in FIG. 2 cannot be output to another optical ADM unit without being output to the branch output terminal side, but FIG. 25 shows a configuration (signal Can be set so as to pass through as it is). 25, reference numerals 2501 and 2502 denote external output terminals;
Reference numerals 3 and 2504 denote external input terminals to which other network devices are connected. Reference numerals 2505 to 2508 denote output terminals connected to the multiplexer. 2509 to 2512 are input terminals connected from the demultiplexer. 2500 denotes a 6 × 6 optical switch, which uses a non-blocking optical switch. nxn
Non-blocking switches are described, for example, in the literature (A. Himeno and M. Kob
ayashi, "4x4 Optical-Gate matrix switch," IEEE J.
As shown in FIG. 1 of LightwaveTechnol., Vol. LT-3, no.2, April 1985), n n-branch optical splitters are connected to input / output terminals, and each input terminal and all input terminals are connected via the optical splitter. This can be realized by using a configuration in which output terminals are connected, each output terminal is connected to all input terminals, and a gate optical switch is arranged between the input side optical splitter and the output side optical splitter. 2512, 2508 are connected to the clockwise working ring, 2511, 2507 are connected to the clockwise spare ring, 2510, 2506 are connected to the counterclockwise spare ring, and 2509, 2505 are connected to the counterclockwise working ring. Thus, the failure recovery of the present invention can be performed. By using the configuration of FIG.
12. By connecting the output terminal 2508, the input terminal 25
It is possible to pass the signal input to 12 as it is to the next node.

The connection for transmitting the signal to the next node without adding / dropping the signal is possible, so that the configuration of the working signal can be made flexible. In the configuration shown in FIG. 22, when passing a signal without adding / dropping, it is necessary to realize the signal by making the optical ADM unit in FIG. 2 pass. Therefore, the cooperative operation of FIG. 22 with the optical ADM unit was necessary. However, if the configuration of FIG. 25 is used, a signal passing state can be configured by itself, and no cooperative operation is required.
Control becomes simple. Another advantage of this configuration is that, since a non-blocking switch is used as the optical switch 2500, it is possible to make a switching setting such that an input signal is returned in the direction of the input signal as it is. For example, input terminal 2
Assuming that the 512 and the output terminal 2509 are connected to the same network node, the 6 × 6 switch unit 2500 is switched and the input signal is directly connected to the input terminal 2512 by connecting the input terminal 2512 and the output terminal 2509. It is possible to set to return to. Since this is possible, it is possible to remotely confirm whether or not the signal transmitted by the user at the time of maintenance reaches the adjacent node.

As shown in FIG. 23, the present invention can be implemented even if the branch signal output terminal and the insertion signal input terminal are duplicated in the integrated optical switch unit. In FIG. 23, reference numerals 2301 to 2304 denote external output terminals,
An external input terminal 308 is connected to another network device. In the configuration of FIG. 22, when two network devices were connected to the external input terminal and the external output terminal, there was no spare optical transmission line. In the configuration of FIG. 23, the number of external output terminals and external input terminals is two in comparison with the configuration of FIG.
Double and half can be used for spare. 22
Output terminals 05 to 2208 are connected to the multiplexer. Input terminals 2309 to 2312 are connected to the demultiplexer. Reference numerals 2325 to 2332 denote optical couplers, and reference numerals 2317 to 2324 denote 1 × 3 optical switches.
Connect 2316 and 2312 to the clockwise working ring,
15 and 2311 are connected to the clockwise spare ring, and 231
4,2310 to the counterclockwise spare ring, 231
By connecting 3,2309 to the counterclockwise working ring, the present invention can be implemented.

A structure different from that of FIG. 23 will be described with reference to FIG. FIG. 23 shows that the signal input from the optical ADM unit in FIG. 2 cannot be output to another optical ADM unit without being output to the branch output terminal side, but FIG. 26 shows a configuration (signal Can be set so as to pass through as it is). 26, reference numerals 2601 to 2504 denote external output terminals;
Reference numerals 5 to 2608 denote external input terminals to which other network devices are connected. Output terminals 2609 to 2612 are connected to the multiplexer. 2613 to 2616 are input terminals connected from the demultiplexer. Reference numeral 2600 denotes an 8 × 8 optical switch, which uses a non-blocking optical switch. 261
6, 2612 to the clockwise working ring, 2615,
Connect 2611 to the clockwise spare ring,
610 to the counterclockwise spare ring, 2613, 26
By connecting 09 to the counterclockwise working ring, the failure recovery of the present invention can be performed.

The connection for transmitting the signal to the next node without dropping / adding the signal is possible, so that the configuration of the working signal can be made flexible. In the configuration of FIG. 23, when passing a signal without dropping and adding, it is necessary to realize the optical ADM unit of FIG. 2 by making it pass. Therefore, the cooperative operation of FIG. 22 with the optical ADM unit was required. However, if the configuration of FIG. 26 is used, a signal passing state can be configured by itself, and no cooperative operation is required.
Control becomes simple. Further, in the configuration of FIG. 26, since a non-blocking switch is used as 2600, it is possible to perform switching setting such that an input signal is returned in the direction of the input signal as it is. Since this is possible, it is possible to remotely confirm whether or not the signal transmitted by the user at the time of maintenance reaches the adjacent node.

Further, input / output terminals for low-priority signals are provided at the branch output end side and the insertion end side so that low-priority signals can be accommodated in the spare ring. The present invention can be implemented by using an integrated optical switch having a function of accommodating the optical switch. FIG. 24 shows a configuration example in which the ET path can be accommodated at an input / output terminal different from the working signal and the backup signal. In FIG. 24, reference numerals 2401-2404, 2433, and 2434 denote external output terminals.
Reference numerals 8 and 2435 and 2436 denote external input terminals to which other network devices are connected. In the configuration of FIG. 22,
When two network devices were connected to the external input terminal and the external output terminal, there was no spare optical transmission line. In the configuration of FIG. 24, one clockwise or counterclockwise working signal can be connected to the working or protection input / output terminal of another network device. For example, the current signal is output to 2401, and the standby signal is output to 2402. Such working / spare pairs are designated as 2403, 2404, and 24.
05 and 2406 and 2407 and 2408. Further, reference numerals 2433 to 2436 can be used for input and output of low priority signals. Output terminals 2409 to 2412 are connected to the multiplexer. 2413-241
Reference numeral 6 denotes an input terminal connected from the demultiplexer. 242
Reference numerals 5 to 2432 denote optical couplers.
Is a 1 × 3 optical switch. 2416, 2412 are connected to the clockwise working ring, 2415, 2411 are connected to the clockwise spare ring, 2414, 2410 are connected to the counterclockwise spare ring, and 2413, 2409 are connected to the counterclockwise working ring. Thus, the failure recovery of the present invention can be performed.

Another configuration will be described with reference to FIG. FIG.
4 cannot output the signal input from the optical ADM unit in FIG. 2 to another optical ADM unit without outputting the signal to the branch output terminal side, but FIG. It is a configuration that can be set so that it passes as it is). FIG.
2701 to 2706 are external output terminals, 2707 to 271
Reference numeral 2 denotes an external input terminal to which another network device is connected. In the configuration of FIG. 27, one clockwise or counterclockwise working signal can be connected to the working or protection input / output terminal of another network device. For example, the current signal is output to 2702, and the standby signal is output to 2703. Such working / spare pairs are 2704 and 2705,
708 and 2709 and 2710 and 2711. Furthermore, 2701, 2706, 2707, 271
2 can be used for input and output of low priority signals.
2713 to 2716 are output terminals connected to the multiplexer. Reference numerals 2717 to 2720 denote input terminals connected from the demultiplexer. Reference numeral 2700 denotes a 10 × 10 optical switch, which uses a non-blocking optical switch. 2720, 2716
Are connected to the clockwise working ring, 2719 and 2715 are connected to the clockwise spare ring, 2718 and 2714 are connected to the counterclockwise spare ring, and 2717 and 2713 are connected to the clockwise working ring. It is possible to implement the fault recovery of the invention.

The connection for transmitting the signal to the next node without adding / dropping the signal is possible, so that the configuration of the working signal can be given flexibility. In the configuration of FIG. 24, when passing a signal without dropping and adding, it is necessary to realize the optical ADM unit of FIG. 2 by making it pass. Therefore, the cooperative operation of FIG. 22 with the optical ADM unit was necessary. However, if the configuration of FIG. 27 is used, a signal passing state can be configured by itself, and no cooperative operation is required.
Control becomes simple. Also, in the configuration of FIG. 27, since a non-blocking switch is used as 2700, it is possible to make a switching setting such that the input signal is returned in the direction of the input signal as it is. Since this is possible, it is possible to confirm whether or not the signal transmitted by the user at the time of maintenance reaches the adjacent node.

The present invention can be implemented by adding a signal monitoring device to those input / output terminals. By always monitoring the signal on the input side and output side of the switch unit, switching at the time of failure can be speeded up. As the monitoring of the signal, the bit error rate of the signal and whether the identifier given to the signal is a predetermined one (whether there is no erroneous connection) is monitored.

Further, a means for transmitting / receiving control / monitoring information to / from another node is added. Based on information obtained from signal monitoring means and information obtained by transmitting / receiving control / monitoring information to / from another node, a switch is provided. The present invention can also be implemented by controlling the units. Thereby, the fault recovery is automated.

In the description of the embodiment of the present invention, no description has been given as to how the optical path is configured as a whole on the ring, but as long as the transfer of the control signal by another wavelength forms a loop. The working optical path itself for a certain wavelength does not have to form a loop. For example, even when only one working optical path with the wavelength of λ1 exists in the ring, the control signal is transferred at another wavelength between adjacent nodes at another wavelength, and signaling between nodes can be performed. Therefore, the present invention can be implemented.

As an embodiment of the present invention, the case where one or two optical fibers have a breakage failure has been described with reference to FIGS. 6 and 7, but more optical fibers are required at the same point. The present invention can be carried out even when a failure occurs in the system.

In the embodiment of the present invention, a fiber fault at the same point has been described. However, even if a fiber fault occurs at a different point, a short path or a long path may occur.
The present invention can be applied as long as a detour by a path can be configured and control messages can be exchanged.

In the embodiment of the present invention, the case of a fiber failure has been described. However, in the case of another failure such as a node failure, a failure of only a certain wavelength (for example, a failure of an optical transmitter of a certain wavelength) is possible. It is possible to perform a failure recovery in a similar manner.

In the embodiment of the present invention, the method of monitoring the bit error rate is used as the monitoring of the optical path. However, the monitoring may be performed by using the method of monitoring the optical power. The optical power monitoring means can be realized, for example, by installing a photodiode at the input end and monitoring the photocurrent. In addition, optical S / N (signal to noise ratio)
It is also possible to apply a method of monitoring Light S /
As a method of monitoring N, for example, it can be realized by obtaining the S / N of light by obtaining the ratio of ASE (spontaneous emission light noise) to signal light.

In the embodiment of the present invention, a sequence chart as shown in FIGS. 8 and 9 is used as a failure recovery procedure, but it is not always necessary to use the same one. For example, the ET path is separated from both the S node and the D node of the ET path first, and then the bypass spare optical path is configured. However, even if only the S node of the ET path is separated, the wavelength of the ET path can be reduced. Since the optical signal does not exist on the spare ring and wavelength collision does not occur, it is possible to configure a bypass path.

In this case, the D node of the ET path
Since the path is not cut off, the optical signal may suddenly stop coming, or the optical signal of a different destination may be received, and the D-node may be confused. If used, it is possible to make the D node of the ET path recognize that fact.

In the embodiment of the present invention, the failure recovery method is changed from short path switching to long path switching if a short path switching completion message is not returned after a predetermined time has elapsed. It is not always necessary to use the same method. For example, if any node recognizes that failure recovery by short path switching is not possible, a method to prevent short path switching by messaging from that node may be used. It is possible.

In the present embodiment, the detour to the short path is preferentially performed regardless of the existence of the ET path.
The present invention can be implemented without any problem by a method of performing a failure recovery operation with a priority based on whether or not a T path exists.
For example, ET on the spare ring that constitutes a short path
There is a path and ET is on the ring that makes up the long path
If a path does not exist, a method of recovering from a failure by detouring to a long path may be used.

In the embodiment of the present invention, the switching method is used in preference to the short path. However, the priority determination method of the switching destination can be implemented without using this method.
For example, E that must be disconnected for fault recovery
It is also possible to use a method of determining the priority in consideration of the total number of hops of the T path, the total transmission distance, the traffic, and the like.

In the embodiment of the present invention, the ring using the optical path in the wavelength division multiplexing system has been described.
The present invention can be applied to a system in which paths such as SONET and SDH are time-multiplexed. However, in the present invention, since the transmission distance of the optical signal can be reduced by not performing the loop-back switch, the ring length can be increased, so that the optical network in which the optical signal passes through the node as light can be used. In this case, the application of the present invention increases the effectiveness (in the SONET ring, the optical signal is converted into an electric signal for each node to reproduce the signal).

The optical path is a single optical path, whether it is an optical signal of 2.5 Gb / s or an optical signal of 10 Gb / s, so that the optical path of 2.5 Gb / s and the optical path of 10 Gb / s s
Even in a system in which the optical paths are mixed, the same node configuration and failure recovery method as in the first embodiment can be used, and the flexibility is high.

If signaling between nodes is possible even if the signal speed of each working optical path is different, what is shared in the spare ring is a spare wavelength serving as a spare resource and is independent of the optical signal speed. This is because any signal speed (a range in which transmission is possible) can be handled due to the nature.

[0160] Regardless of the signal format of the optical path, even if signals of any signal format coexist, switching is performed by an optical switch, and if signaling between nodes is possible, the optical switch is independent of the signal format. Is possible.

In the embodiment of the present invention, the method using the optical path in the wavelength division multiplexing system has been described.
TM VP (Virtual Path) and VC (Virtual Channel)
The present invention can be applied to l) as long as it is a ring network.

In the embodiment of the present invention, 1.
Although an optical signal having a wavelength of 5 μm band and an optical signal having a wavelength of 1.3 μm are used for the control signal system, the use of these wavelengths is limited as long as the main signal system and the control signal system can be separated. However, the present invention can be applied to an optical signal having an arbitrary wavelength.

In the embodiment of the present invention, an example has been described in which a frame structure is used as a method for transferring a control signal to another node, and a destination node name is assigned to the first 8 bits and a control message is assigned to the next 8 bits. However, the present invention is not limited to this, and any bit allocation method may be used as long as the request for path failure recovery is transmitted to the source node. In addition, there is no need to assign information to bits, and message-oriented communication can be used. It is also possible to use packet communication, frame relay, and communication using ATM.

In the embodiment of the present invention, an example in which an optical signal having a wavelength different from that of the main signal is used as the control signal transfer means has been described. However, the present invention is not limited to this. Any means can be used. For example, control information may be exchanged between nodes using a system in which a wireless signal or a subcarrier is superimposed on an optical signal and transmitted, or control signals may be exchanged using a telephone line.

Also, the present invention can be implemented by using a method of exchanging control monitoring information with another node using a control monitoring area in the time-division multiplexed main signal light.

In the embodiment of the present invention, the event of detecting the failure of the own node termination signal has been described as a trigger for starting the failure recovery operation. However, the failure recovery operation is notified by a failure notification from another node or another network device. May be started. For example, a method may be used in which a node at a stage preceding the node terminating the optical path (wavelength: λ1) detects a failure of the optical path having the wavelength of λ1 and notifies the terminal node of the abnormality to cause a failure recovery operation. The present invention can be implemented without hindrance.

As an embodiment of the present invention, when the traffic between nodes is symmetrical in the up direction and the down direction,
The present invention can be applied to any case where the traffic between nodes is asymmetric in the uplink and downlink directions (for example, in a system having only downlink communication).

In the embodiment of the present invention, a method in which one ring system uses one fault recovery method has been described. However, the present invention is not limited to this.
The present invention can also be realized by combining the method with another method such as a conventional 1 + 1 protection method. For example, for each wavelength, λ
1, λ2 is a failure recovery method by the 1 + 1 method, λ3, λ4
Can be used for the fault recovery according to the present invention.

In the embodiment of the present invention, the optical switch 40
Although mechanical optical switches are used as the optical switches 5 to 406, 510, and 511, any optical switch that satisfies performance such as crosstalk and loss can be used as an optical switch using the electro-optic effect or an optical switch using the thermo-optic effect. Alternatively, any optical switch such as an optical gate switch using a semiconductor optical amplifier can be employed.

In the embodiments of the present invention, the optical switches 230 and 231, for example, have been described based on the configuration shown in FIG. 3. However, the present invention can be configured using switches of different sizes and configurations. That is, in the case of a system having n spare rings having shared spare resources for the working signal, it is necessary to use (n + 1) × 1 optical switches in order to be able to switch to all the working rings and the spare ring. The present invention can be configured using a larger m × n switch that includes the function of such a switch.

Further, the present invention can be realized without any trouble even in a configuration having a switch function having a function of returning a signal input for maintenance and inspection to a transmitting node as it is.

In the embodiment of the present invention, the optical switches 230 and 231 are used as the switches of the S node and the D node. However, the optical switches 230 and 231 are directly connected to the demultiplexed output terminal and demultiplexed input terminal without switching. After converting the signal to an electric signal, protection may be performed by an electric switch. As the electric switch, either an electric switch for spatially switching or an electric switch for switching a time-division multiplexed signal obtained by time-division multiplexing, A
The present invention can be embodied without any problem even in an ATM switch that switches a connection established by a cell like a TM switch.

In the embodiment of the present invention, an example has been described in which an optical coupler having a branching ratio of 10:90 is used for monitoring an optical signal. However, the present invention is not limited to this. If not, the optical power splitting ratio and the coupling ratio can be set arbitrarily.

In the embodiment of the present invention, the case of a four-node, two-wavelength ring has been described. However, the present invention is not limited to this. It is obvious that the invention can be applied.

In the embodiment of the present invention, a configuration in which all optical signals can be inserted and separated is used as the optical ADM unit. However, the present invention is applicable to a configuration in which not all wavelengths can be inserted and separated. Clearly applicable.

In the embodiments of the present invention, it is assumed that a wavelength multiplexed system is used. However, it is apparent that the present invention can be implemented even when the number of wavelength multiplexing is one.

In the embodiment of the present invention, the case where the wavelength multiplexing technique is applied as the optical multiplexing technique has been described. However, the present invention is also applicable to a system to which other multiplexing techniques such as polarization multiplexing, time multiplexing, and spatial multiplexing are applied. The present invention can be implemented. For example, to apply the present invention to a spatial multiplexing system, a bundle of a plurality of optical fibers is treated as an optical fiber group, nodes are connected to the ring topology by the optical fiber group, and a ring configured by the optical fiber group is formed. This can be realized by treating it as one ring. For example, if there are four rings in the fiber group, it is possible to perform failure recovery in the same manner as in the first embodiment, and if there are two rings in the fiber group, the second embodiment is used. , Can be handled in the same manner as in the third embodiment.

As an embodiment of the present invention, the case of two fibers and four fibers has been described, but the present invention is not limited to this. For example, from the four-fiber system, the number of spare rings serving as shared spare resources is increased clockwise and counterclockwise one by one, and the optical switch 30 used for failure recovery is used.
If 9,312 is a 1 × 4 switch, the present invention can be applied to a 6-fiber ring. Further, as described in the second and third embodiments, if a part of the band resource can be used as the working resource and the rest can be used as the spare resource, it is not necessary to use the two-fiber ring. The present invention is applicable to a three-fiber ring and a four-fiber ring.

When a system for transmitting an optical signal bidirectionally in one fiber is used, there is only one ring physically, but it is logically regarded as two oppositely rotating rings. The configuration and method of the present invention can be applied. By using this technique, physically, the present invention can be applied by using a smaller number of rings than the number of rings described in the embodiment of the present invention.

In the embodiment of the present invention, an example in which an AWG is used as a wavelength multiplexer and a wavelength demultiplexer has been described. However, a device using a diffraction grating, a fiber Bragg grating (a periodic structure in a fiber), Any one having a function of multiplexing wavelengths or wavelength multiplexing / demultiplexing, such as a combination of filters having filters and filters, can be used.

In the embodiment of the present invention, an optical amplifier is not used in an optical communication node or an optical transmission line. However, it is obvious that the present invention can be implemented without trouble even in a system using it.

In the embodiment of the present invention, an optical communication network in which an optical signal passes through a node in the middle without being converted into an electric signal without being converted into an electric signal has been described. May be inserted. By incorporating such a device, it is possible to lengthen the ring, to reproduce a signal as an interface with a separation signal and an insertion signal, and to monitor an optical signal. When a device that converts an electric signal into an optical signal and then converts the signal into an optical signal is configured in the optical path, the device can be operated as a gate switch by controlling whether the device emits light or not. It is possible. For example, an optical-electrical-optical converter that can configure both a state of outputting light and a state of not outputting light can operate as a gate switch.
05 to 407.

It is obvious that the present invention can be implemented irrespective of where the optical signal is converted into the electric signal and the electric signal is converted into the optical signal. For example, it may exist at the input end or output end of the optical switch unit.
In that case, it is obvious that the present invention can be implemented even if an electric switch for switching electric signals is used instead of the optical switch in the embodiment of the present invention.

In the embodiment of the present invention, a case was described in which an optical path having no wavelength conversion was used in the middle, but a wavelength converter was inserted in the ring network and wavelength conversion was performed in the middle. May be treated as an optical path. Examples of the wavelength converter include a method of once converting an optical signal into an electric signal and then converting it again into an optical signal using a light source of a desired wavelength, a method using mutual gain modulation, mutual phase modulation, and four-wave mixing. But it can be applied.

In the case where a wavelength converter is used, the wavelength is reused in the spare ring by allocating the spare optical path well (the same wavelength is used again in the same ring).
Therefore, resistance to multiple faults such as double faults is improved.

In the embodiment of the present invention, no light is transmitted when no failure occurs in the spare ring. However, in order to confirm whether or not a failure has occurred in the transmission system using the spare ring, the failure is determined. The present invention can also be applied to a system using a method of transmitting an optical signal even when no error occurs. For example, the protection ring is periodically operated to configure all the protection paths, and the protection optical path is periodically monitored. When a failure is detected or a switch request message is received, the protection path for monitoring is set. May be stopped and a method of configuring only a spare optical path for recovery from a failure may be used.

In the embodiment of the present invention, a description has been given of the recovery from a failure in one-way communication in either the left-handed or right-handed working path. However, in the present invention, each shared spare resource is independently allocated. Since the detours can be formed independently of each other, the present invention can be applied even when both clockwise communication and counterclockwise communication faults occur simultaneously.

However, if a failure occurs in one direction (for example, communication from the A node to the B node), a method of switching in both directions (both communication from the A node to the B node and communication from the B node to the A node) is adopted. Obviously, the present invention can be implemented even if used.

In the embodiment of the present invention, the configuration of a network consisting of one ring network and the method of recovering from a failure have been described. However, the present invention is applicable to a case where the entire network is a connection of a plurality of ring networks. Is possible. If a failure occurs in the m-th ring network when a plurality of optical paths configured in each ring are connected to form an optical path, the failure of the m-th ring is independent of the other rings. The fault recovery as described in the embodiment may be performed in the system closed inside. Note that the entire network does not necessarily have to be a network in which only a plurality of ring networks are connected. For example, even if the entire network includes a configuration in which the ring network is connected by an optical transmission line having a working system and a protection system, even if the entire network includes a failure, a failure in the ring network may occur. Thus, the present invention can be applied.

In the embodiment of the present invention, the case where the optical transmission line has a ring topology has been described, but the present invention is not limited to this. For example, even in a mesh network in which a plurality of network nodes exist and are randomly connected, if the optical signals for each wavelength are connected so as to form a ring topology, the present invention can be implemented. is there. This will be described with reference to FIG. In FIG. 28, 2801 to 2809
Is a network node. Each node is equipped with a wavelength multiplexing device and a wavelength multiplexing / demultiplexing device.
Branching is possible. 2811 to 2815 are optical links. Wavelength multiplex transmission is performed in each optical link. The network node has multiple optical links (optical transmission paths between nodes)
Connected by In each link, a clockwise working wavelength, a counterclockwise working wavelength, a clockwise spare wavelength, and a counterclockwise spare wavelength are selected, and when they are connected, virtually, as shown by the thick line in FIG. It is possible to configure a ring for each wavelength. Here, the wavelength used in each link does not necessarily have to be the same as long as each node has a wavelength conversion function. For example, to construct a virtual clockwise working ring, the wavelength of λ1 in the optical link 2811, the wavelength of λ2 in the optical link 2812, the wavelength of λ1 in the optical link 2813, the wavelength of λ2 in the optical link 2814, Optical link 2
At 815, the wavelength is connected by λ3. The present invention can be implemented by constructing four such virtual rings and assigning them to the working clockwise, spare, working left, and spare rings.

[0191]

According to the present invention, when a detour to a short path on the ring is possible at the time of a fault, recovery from the fault by detour to the short path can be performed, and detour to the short path is not possible. When possible, recovery is performed by detouring to the long path, so if the recovery from the short path is possible, the number of ET paths to be disconnected can be reduced, and the number of ET paths at the time of recovery can be reduced. Operational efficiency increases. In addition, since maintenance such as replacement of parts can be dealt with by switching the short path, the number of ET paths to be disconnected is reduced, and the use efficiency of ET paths during maintenance is increased.

Further, since the short path passes through the same path as the working path, by making a detour to the short path,
Since the delay difference is small, the instantaneous interruption time at the time of switching is short, and the delay difference is small, the memory capacity required for instantaneous interruption switching can be reduced.

In addition, since the detour to the long path is not always performed at the time of recovery from the failure, if the recovery from the failure is possible by the detour to the short path, the number of nodes involved in the switching is reduced. Time is reduced. This is particularly effective for very long haul rings.

In addition, since there are two detour candidates at the time of failure, a short path and a long path, reliability is improved.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a node used in FIG. 1;

FIG. 3 is a block diagram showing an optical switch unit used in FIG. 2;

FIG. 4 is a block diagram showing a 1 × 3 optical switch used in FIG. 3;

FIG. 5 is a block diagram showing an optical ADM unit used in FIG. 2;

FIG. 6 is a diagram illustrating a failure recovery operation (a detour to a short path) used in the first embodiment.

FIG. 7 is a diagram illustrating a failure recovery operation (a detour to a long path) used in the first embodiment.

FIG. 8 is a sequence chart illustrating a failure recovery operation (a detour to a short path) used in the first embodiment.

FIG. 9 is a sequence chart illustrating a failure recovery operation (detour to a long path) used in the first embodiment.

FIG. 10 is a block diagram showing another embodiment of FIG. 3;

FIG. 11 is a block diagram showing another embodiment of FIG. 3;

FIG. 12 is a block diagram showing another embodiment of FIG. 3;

FIG. 13 is a block diagram showing another embodiment of FIG. 3;

FIG. 14 is a block diagram showing another embodiment of FIG. 3;

FIG. 15 is a block diagram showing another embodiment of FIG. 4;

FIG. 16 is a block diagram showing another embodiment of FIG. 4;

FIG. 17 is a block diagram showing another embodiment of FIG. 4;

FIG. 18 is a block diagram showing another embodiment of FIG. 4;

FIG. 19 is a block diagram showing another embodiment of FIG. 5;

FIG. 20 is a block diagram showing another embodiment of FIG. 5;

FIG. 21 is a block diagram showing a conventional example.

FIG. 22 is a block diagram showing an embodiment in which a switch on the sending side and a switch on the receiving side are integrated.

FIG. 23 is a block diagram showing another embodiment of FIG. 22;

FIG. 24 is a block diagram showing another embodiment of FIG. 22;

FIG. 25 is a block diagram showing another embodiment of FIG. 22;

FIG. 26 is a block diagram showing another embodiment of FIG. 23;

FIG. 27 is a block diagram showing another embodiment of FIG. 24;

FIG. 28 is a network configuration diagram showing another embodiment of FIG. 1;

[Explanation of symbols]

 101, 103 Working ring 102, 104 Spare ring 105-109 Node 201, 203, 215, 213 Output end 202, 204, 214, 216 Input end 205, 208 Branch output end 209, 212 Insertion end 217-220 Optical ADM section 221 Monitoring controller 222-225 Optical splitter 230, 231 Optical switch unit 241, 243, 245, 247 Control signal multiplexer 242, 244, 246, 248 Control signal demultiplexer 309-312 1 × 3 optical switch 313-316 Optical couplers 405 to 407 Gate type optical switch 408 Optical coupler 507 Wavelength multi-plexer 508, 509 Optical coupler 510, 511 Optical gate 512, 513 Optical splitter 514 Wavelength demultiplexer 601 Active optical path 602 Spare optical path 603 Spare light Pass 1010, 101 1 Optical Couplers 1411 to 1414 Optical Couplers 1415 to 1418 1 × 4 Optical Switch 1507, 1508 1 × 2 Optical Switch 1711 Gate Optical Switch 1712, 1812 1 × 2 Optical Switch 1908, 1909 2 × 2 Optical Switch 2109, 2110 1 × 2 optical switch 2131 working optical path 2132 standby optical path

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04M 3/00 H04L 11/20 C H04Q 3/52 101 (72) Inventor Naoya Hemi Shibago, Minato-ku, Tokyo 7-1-1, NEC Corporation (72) Inventor Hitoshi Takeshita 5-7-1, Shiba, Minato-ku, Tokyo Nippon Electric Corporation (72) Hiroshi Shimomura 5-7-1, Shiba, Minato-ku, Tokyo No. 1 Inside NEC Corporation

Claims (28)

[Claims] 1. A plurality of communication node means for inserting and separating signals and a plurality of transmission paths, wherein the plurality of communication node means form the same network topology by connecting the plurality of transmission paths. And at least a first ring, a second ring, a third ring, and a fourth ring, wherein the first ring transmits a working signal either clockwise or counterclockwise, and Spare resources for the second ring and the fourth ring for transmitting signals in the same direction as the first ring as a spare resource for a working signal of the ring Is shared among a plurality of working signals, the working signal is transmitted in the third ring in a direction opposite to that of the first ring, and the third ring is used as a backup resource for the working signal of the third ring. By using the second ring spare resource for transmitting a signal in the same direction as that of the fourth ring and the third ring for transmitting a signal in the opposite direction to a plurality of working signals, Failure recovery and maintenance of a first communication in which a signal is inserted by an i-th communication node means of a plurality of communication node means and a signal is terminated by a j-th communication node means via the first ring As a detour configured for the above, using a detour configured in the second ring or the fourth ring,
Failure recovery of the second communication, in which a signal is inserted at the mth communication node means of the plurality of communication node means and terminated at the nth communication node means via the third ring, A communication network using a detour configured for the fourth ring or the second ring as a detour configured for maintenance. 2. A communication system comprising: a plurality of communication node means for inserting and separating signals; and a plurality of transmission paths, wherein the plurality of communication node means form the same network topology by connecting the plurality of transmission paths. At least a first ring and a second ring as described above, wherein the first ring transmits the working signal in one of clockwise or counterclockwise directions, and the second ring transmits the working signal to the second ring. 1 in the opposite direction to the first ring, wherein the first ring is in a transmission band between a working signal group transmitted by the second ring and a working signal group transmitted by the first ring. The second ring has a spare resource band shared and transmitted in the opposite direction to the working signal, and the second ring includes a working signal group transmitted by the first ring and the second ring within the transmission band. Current transmitted By having a spare resource band shared between the signal groups and transmitted in the opposite direction to the working signal, a signal is inserted at the i-th communication node means of the plurality of communication node means, and A spare resource band of the second ring or the first resource is used as a bypass for recovery or maintenance of a first communication which terminates a signal at a j-th communication node means via one ring. Using a communication path constituted by the spare resource band of the ring, inserting a signal at the mth communication node means of the plurality of communication node means, and performing the nth communication via the second ring. A communication path configured by a spare resource band of the first ring or a spare resource band of the second ring as a bypass configured for recovery or maintenance of a second communication terminating a signal at a node means. To use Communication network to the butterflies. 3. The communication network according to claim 1, wherein said communication node means is an optical communication node means, said transmission path is an optical transmission path, and said communication is optical communication. . 4. The communication network according to claim 3, wherein said optical communication is wavelength multiplexed optical communication. 5. The communication network according to claim 1, wherein said communication network is a part of an entire network. 6. A multiplexed signal input terminal for inputting a multiplexed signal, a multiplexed signal input terminal for inserting a signal, a multiplexed signal input terminal for inserting a multiplexed signal, and a multiplexed signal obtained by demultiplexing the multiplexed signal input to the multiplexed signal input terminal. A plurality of insertion / separation / multiplexing means having a plurality or a single separation / output terminal for outputting a separation signal, and a multiplex signal output terminal for multiplexing and outputting the signal input to the insertion input terminal and the multiplex / demultiplex signal; A plurality or a single external input terminal connected to a node; a plurality or a single external output terminal connected to another node; a plurality or a single switch means; a plurality or a single merging means; and a plurality or a single signal An input terminal, comprising a plurality or a single signal output terminal, wherein the external input terminal is connected to a multiplex signal input terminal of the insertion / demultiplexing means, and a multiplex signal output terminal of the insertion / demultiplexing means is connected to the external output terminal. Contact Wherein the signal input terminal is connected to the switch means, and the external output terminal connected to the multiplexed signal output terminal is connected to the same node. A plurality of the insertion / demultiplexing units connected to different nodes are connected to an output terminal of the switch unit, and the external input terminals connected to the multiplexed signal input terminal are connected to the same node. A separation output terminal of the insertion / demultiplexing unit and a separation output terminal of the insertion / demultiplexing unit connected to a node different from the same node are connected to an input terminal of the joining unit, and the joining unit is connected to the signal output terminal. A communication network node device. 7. A multiplexed signal input terminal for inputting a multiplexed signal, a multiplexed signal input terminal for inserting a signal, a multiplexed signal input terminal for inserting a multiplexed signal and a multiplexed signal input to the multiplexed signal input terminal. A plurality of insertion / separation / multiplexing means having a plurality or a single separation / output terminal for outputting a separation signal, and a multiplexed signal output terminal for multiplexing and outputting the signal input to the insertion input terminal and the multiplex / demultiplex signal; One or more external input terminals connected to another node, two or more external output terminals connected to another node, one or more switch means, one or more merge means, and one or more signal inputs And a plurality of or a single signal output terminal; and a plurality or a single control means for transmitting / receiving control information to / from another node and performing switching control of the switch means based on the control information. An end is connected to a multiplexed signal input end of said insertion / demultiplexing means, a multiplexed signal output end of said insertion / demultiplexing means is connected to said external output end, said signal input end is connected to said switch means, The external input terminal connected to the output terminal is connected to the same node. The external input terminal connected to the output terminal of the switch means and the external input terminal connected to the multiplexed signal input terminal is connected to the same node. A communication output terminal of the insertion / demultiplexing means connected to the input end of the joining means; and the joining means connected to the signal output end. Network node apparatus. 8. A multiplexed signal input terminal for inputting a multiplexed signal, a multiplexed signal input terminal for inserting a signal, a multiplexed signal input terminal for inserting a multiplexed signal and a multiplexed signal input to the multiplexed signal input terminal are demultiplexed. A plurality of insertion / separation / multiplexing means having a plurality or a single separation / output terminal for outputting a separation signal, and a multiplex signal output terminal for multiplexing and outputting the signal input to the insertion input terminal and the multiplex / demultiplex signal; A plurality or a single external input terminal connected to a node, a plurality or a single external output terminal connected to another node, a plurality or a single switch means having a plurality of output terminals, and a plurality or a single merging means A plurality of or a single signal input terminal; a plurality of or a single signal output terminal; a plurality of or a single signal monitoring means for monitoring a signal input to the merging means; and an optical switch for exchanging control information with another node. hand The external input terminal is connected to a multiplex signal input terminal of the insertion / demultiplexing means, and the multiplex signal output terminal of the insertion / demultiplexing means is connected to the external output terminal. Connected, the signal input terminal being connected to the switch means, the external output terminal being connected to the multiplexed signal output terminal being connected to the same node, and the insertion input terminals of the plurality of insertion / demultiplexing means being connected to the same node. A plurality of input / output terminals of the insertion / demultiplexing unit connected to a different node are connected to an output terminal of the switch unit; and the external input terminals connected to the multiplex signal input terminal are connected to the same node. A separation output terminal of the insertion / demultiplexing unit and a separation output terminal of the insertion / demultiplexing unit connected to a node different from the same node are connected to an input terminal of the joining unit. The merging means is connected to the signal output end, and the control means controls the switch based on a monitoring result of a signal input to the merging means of the signal monitoring means and a result of transmission and reception of control information with the other node. A communication network node device for controlling means. 9. The optical communication system according to claim 6, wherein said insertion / demultiplexing means is an optical signal insertion / demultiplexing means.
Or a communication network node device according to claim 8. 10. The communication network / node apparatus according to claim 6, wherein said insertion / demultiplexing means is means for performing insertion / demultiplexing by wavelength. 11. The insertion / separation multiplexing means connected to the working ring includes a fixed connection, and the insertion / separation means connected to the spare ring has switching means inside the insertion / separation means. 9. The communication network node device according to claim 6, wherein the internal connection is variable by switching the communication network node device. 12. A spare resource for forming a bypass communication path is shared by a plurality of working signals, and is supplied from an input end of a first communication network node device existing in a ring network having a communication path for control messages. In a method for recovering communication failure to an output terminal of a second communication network node device existing in the ring network, the control message is transmitted when the second communication network node device detects the communication failure. A control message is exchanged between the first communication network node device and the second communication network node device by using a communication channel for the first communication network node device; Communication network node equipment,
And switching the switching means provided in the communication network node device between the first communication network node device and the second communication network node device, thereby giving priority to the configuration of a detour. If there is a communication path with a low degree of communication, the communication path is disconnected, the communication path is switched to a detour in the opposite direction to the communication path or a detour in the same direction, and communication failure recovery is performed. Network failure recovery method. 13. A spare resource for forming a bypass communication path is shared by a plurality of working signals, and a working communication path using spare resources is formed in addition to a communication path formed using working resources. Recovery method for communication from an input terminal of a first communication network node device existing in a ring network having a communication path for communication to an output terminal of a second communication network node device existing in the ring network. In this case, a priority determining method for switching to a detour in the opposite direction to the communication or a detour in the same direction as a switching destination when a failure occurs is determined in advance, and the second communication network node When a device detects the communication failure, the first communication network node device and the second communication network use the control message communication channel. Exchanging control messages between the first communication network node device, the second communication network node device, and the first communication network node device.
A communication network between said second communication network node device and said second communication network node device.
By switching the switch means provided in the node device, disconnecting the working communication path using the spare resources that hinders formation of a bypass having the first priority determined based on the priority determination method, Attempt to switch to the detour having the first priority, and if it is possible to configure the detour having the first priority, switch to the detour having the first priority. If the communication failure recovery is completed and it is not possible to configure a detour having the first priority, the first communication network node device and the first communication network node device are connected to each other using the communication path for the control message. A control message is exchanged between second communication network node devices, and the first communication network node device, the second communication network node device, and the second A second priority determined on the basis of the priority determination method by switching switch means provided in a communication network node device between the communication network node device and the second communication network node device. Disconnecting the working communication path using the backup resource that hinders the formation of a detour having the above, and performing the fault recovery of the communication by switching to the detour having the second priority. Characteristic communication network failure recovery method. 14. The communication network according to claim 13, wherein said priority is determined by using a method of giving priority to a detour which requires less disconnection of a working communication path using said spare resources. Disaster recovery method. 15. The communication network failure recovery method according to claim 13, wherein a method of prioritizing a detour having a small number of hops is used as the method of determining the priority. 16. The communication network failure recovery method according to claim 13, wherein a method of prioritizing a detour having a short transmission distance is used as a method of determining said priority. 17. The communication network node device according to claim 6, wherein the first communication network node device and the second communication network node device are the communication network node device according to claim 6. 14. The failure recovery method according to claim 12 or claim 13, wherein 18. The failure recovery method according to claim 12, wherein said ring network is a part of a section of the whole network. 19. A second communication system in which a spare resource constituting a bypass communication path is present in the ring network from an input end of a first communication network node device existing in the ring network shared by a plurality of working signals. In a system for maintaining communication to an output end of a communication network node device, the first communication network node device, the second communication network node device, and the first communication network node device A detour for transmitting a signal in the opposite direction to the communication or a detour for transmitting a signal in the same direction by using switch means provided in the communication network node device between the communication network node device and the second communication network node device A communication network maintenance method, wherein the communication is maintained by switching to a communication network. 20. A first input terminal for receiving a working signal from a first route, a first output terminal for outputting a working signal from the first route, and a first route. A second input terminal to which a standby signal from the first route is input, a second output terminal to which a standby signal from the first route is output, and a third input terminal to which a working signal from the second route is input. , A third output terminal from which a working signal from the second route is output, a fourth input terminal to which a spare signal from the second route is input, and a second route. A fourth output terminal from which a spare signal is output from the switch, a switch means,
And a second insertion signal input terminal, and first and second branch signal output terminals, wherein the first, second, and fourth input terminals and the first
, The connection between the second, third, and fourth input terminals and the second branch signal output terminal, the first insertion signal input terminal and the second 1. Connection between the second, fourth and fourth output terminals and connection between the second insertion signal input terminal and the second, third, and fourth output terminals are possible. A communication device characterized by the above-mentioned. 21. A first input terminal to which a working signal from a first route is input, a first output terminal to which a working signal from the first route is output, and a first route. A second input terminal to which a standby signal from the first route is input, a second output terminal to which a standby signal from the first route is output, and a third input terminal to which a working signal from the second route is input. , A third output terminal from which a working signal from the second route is output, a fourth input terminal to which a spare signal from the second route is input, and a second route. A fourth output terminal from which a spare signal is output from the switch, a switch means,
And second working insertion signal inputs, first and second protection insertion signal inputs, first and second working branch signal outputs, and first and second protection insertion signals. A switch for connecting the first, second and fourth input terminals to the first working branch signal output terminal; Connection between the fourth input terminal and the first spare branch signal output terminal;
Connection between the second and fourth input terminals and the first working branch signal output terminal, and connection of the third, second, and fourth input terminals to the second working branch A connection with a signal output terminal, a connection between the third, second, and fourth input terminals and the second spare branch signal output terminal; and a first working insertion signal input terminal. And the connection between the first, second, and fourth output terminals, and the connection between the first spare insertion signal input terminal and the first, second, and fourth output terminals. Connection, connection between the first working insertion signal input terminal and the third, second, and fourth output terminals, and connection between the second working insertion signal input terminal and the third, Connection between the second and fourth output terminals, connection between the second spare insertion signal input terminal and the third, second, and fourth output terminals; A communication device, characterized in that the communication device is capable of: 22. It also has third and fourth insertion signal input terminals to which low-priority communication is input, and third and fourth branch signal output terminals to which low-priority communication is output, The switch means includes a connection between the second input terminal and the third branch signal output terminal, and a connection between the fourth input terminal and the fourth input terminal.
, A connection between the third insertion signal input terminal and the second output terminal, and a connection between the fourth insertion signal input terminal and the fourth output terminal. 22. The communication device according to claim 21, wherein: 23. A signal monitoring means connected to the input terminal, the output terminal, the branch signal output terminal, and the insertion signal input terminal. 23. The communication device according to claim 22. 24. A means for exchanging control / monitoring information with another node, and controlling switching of said switch means based on information from said signal monitoring means and information from said means for exchanging control / monitoring information. 24. The method according to claim 23, wherein:
The communication device as described. 25. A first input terminal to which a working signal from the first route is input, a first output terminal to which a working signal from the first route is output, and a first route. A second input terminal to which a standby signal from the first route is input, a second output terminal to which a standby signal from the first route is output, and a third input terminal to which a working signal from the second route is input. , A third output terminal from which a working signal from the second route is output, a fourth input terminal to which a spare signal from the second route is input, and a second route. A fourth output terminal from which a spare signal is output from the switch, a switch means,
And a second insertion signal input terminal, and a first and a second branch signal output terminal, wherein the switch means is each of the input terminals, each of the insertion signal input terminals, each of the output terminals, and each of the branch signal outputs. A communication device wherein a connection state with an end can be arbitrarily set. 26. A first input terminal to which a working signal from the first route is input, a first output terminal to which a working signal from the first route is output, and a first route. A second input terminal to which a standby signal from the first route is input, a second output terminal to which a standby signal from the first route is output, and a third input terminal to which a working signal from the second route is input. , A third output terminal from which a working signal from the second route is output, a fourth input terminal to which a spare signal from the second route is input, and a second route. A fourth output terminal from which a spare signal is output from the switch, a switch means,
A fourth to a fourth insertion signal input terminal and a first to a fourth branch signal output terminal, wherein the switch means is each of the input terminals, each of the insertion signal input terminals, each of the output terminals, and each of the branch signal outputs. A communication device wherein a connection state with an end can be arbitrarily set. 27. A first input terminal for receiving a working signal from a first route, a first output terminal for outputting a working signal from the first route, and a first route. A second input terminal to which a standby signal from the first route is input, a second output terminal to which a standby signal from the first route is output, and a third input terminal to which a working signal from the second route is input. , A third output terminal from which a working signal from the second route is output, a fourth input terminal to which a spare signal from the second route is input, and a second route. A fourth output terminal from which a spare signal is output from the switch, a switch means,
To the fourth to fourth insertion signal input terminals, the first to fourth branch signal output terminals, the fifth and sixth insertion signal input terminals to which low-priority communication is input, and the low-priority communication to output. And the switch means arbitrarily sets a connection state with each of the input terminals, each of the insertion signal input terminals, each of the output terminals, and each of the branch signal output terminals. A communication device characterized by being configurable. 28. The communication node means is an optical communication node means, the transmission path is an optical transmission path, the communication is wavelength-division multiplexed optical communication, and the first to fourth rings are of wavelength unit. The communication network according to claim 1, wherein the communication network is a ring configured by connecting optical signals.