JP2002009803A - Communication network, communication network node unit, and fault recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To build up a ring system that can use a long total length for a ring, efficiently accommodate optical paths and conduct insertion, separation, multiplexing of an optical signal at a low cost. SOLUTION: Active optical paths as many as possible are assigned to active rings 101, 103, and standby rings 102, 104 are used for the respective common resources. On the occurrence of a fault in the active optical path 401 such as a broken optical fiber between nodes 105 and 106, for example, a termination node 108 transmits a switch request to a source node 106 without conducting loopback switching so as to change the source node 106, then to bypass to a standby optical path 402 to recover the fault.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication network, a communication network node device, and a failure recovery system.

[0002]

2. Description of the Related Art In the following, the term "separation" means to output a signal obtained by decomposing a signal transferred from 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 the wavelengths and time slots are not replaced as they are, or are spatially connected. This means that the transmission is performed to another node by changing the wavelength or changing the time slot. Hereinafter, an optical path is defined as a period from a time when an electric signal is converted into an optical signal at a certain node and transmitted to another node until the signal is converted again into an electric signal.

[0003] In order to meet the demand for large capacity communication,
In optical communication networks, wavelength multiplexing allows
Means have been taken to increase the capacity in the optical transmission line of the book. In order to operate such a network efficiently, an optical ADM (Add / Drop Multiplexer) for switching and wavelength division of an optical signal at a communication network node to separate and insert the optical signal.
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 ring and a two-fiber unidirectional ring are considered.

[0004] A four-fiber ring is a system having four rings constituted by fibers, and a two-fiber ring is a system having two rings constituted by fibers.

A four-fiber ring has conventionally been used as a bidirectional ring. A bi-directional ring means a ring that communicates with each other using clockwise and counterclockwise signals on the same path when communication between certain nodes is considered. The four rings are used as a working ring for transmitting clockwise working signal light, a counterclockwise working ring, a counterclockwise spare ring for a clockwise working ring, and a spare ring for a counterclockwise working ring. . When a failure occurs in all the fibers between certain nodes, as shown in FIG. 10, the connection is switched to a spare fiber that transmits in the opposite direction at the node before the failure point (a loopback switch). It is possible to perform disaster recovery (for example,
AF Elrefaie, "Multiwavelength survivable r
ing network architectures "in Proc. ICC '93,
pp. 1245-1251, 1993.). In FIG. 10, reference numerals 1005 to 1008 denote communication nodes. 1021
Is a working optical path passing through the working ring 1001, and is terminated from the node 1006 through the nodes 1005 and 1008 to the node 1007. Now, if a break fault occurs in the fiber between the node 1005 and the node 1008, the nodes 1005 and 1
At 008, the wavelength multiplexed signal is switched to the spare ring 1002 while being multiplexed so as to be looped back (loopback switching), and a detour 1022 is formed to perform failure recovery. After all, at the time of failure recovery, the optical signal is transmitted to the nodes 1006 and 100
5, node 1006, node 1007, node 100
8. Since the signal passes through the route of the node 1007, optical transmission over a longer distance than one round of the ring is performed. At this time, in the case of a failure in the bidirectional ring, wavelength multiplexed signal light is switched collectively for each fiber.

[0006] Two fiber rings have traditionally been used as unidirectional rings. The unidirectional ring means, for example, that communication between nodes is normally performed by all clockwise signals. For unidirectional rings, 1+
Use a single protection scheme (eg, H. Toba et.
al., "An optical FDM-based self-healing rin
g network employing arrayed waveguide grating
filters and EDFA's with level equalizers, "
IEEE J. on Select. Areas Commun. Vol. 14,
no.5, pp. 800-813). FIG. 11 is a diagram for explaining failure recovery using the 1 + 1 protection method. 1
Reference numerals 101 and 1103 represent working rings, and reference numerals 1102 and 1104 represent spare rings. As shown in FIG. 11, in the 1 + 1 protection scheme, a transmission side node (source node) previously transmits a backup optical path 1122 optically transmitted clockwise on the standby ring 1102 and an optical transmission clockwise on the working ring 1101 in advance. To the working optical path 1121 to be transmitted. The receiving node can receive the clockwise signal and the counterclockwise signal by switching the switch, so that when a failure occurs, the reception node switches to receive the signal having no failure. By doing so, it is possible to perform failure recovery. Since clockwise and counterclockwise signals are always flowing in communication between certain nodes,
In particular, it can be said that the working signal always flows in both clockwise and counterclockwise directions without distinction from the working signal and the spare signal.

By using a two-fiber unidirectional ring, it is possible to apply the 1 + 1 protection method, so that it is possible to perform failure recovery at a very high speed. When the 1 + 1 protection scheme is used with a two-fiber unidirectional ring, loopback is not performed from the viewpoint of optical transmission, so that the optical transmission distance does not become longer than one round of the ring.

[0008] In addition, SONET (for example, TH Wu,
"Fiber Network Service Survivability," Artech
house, 1992), a two-fiber unidirectional ring may be used to perform failure recovery by looping back the failure section (loopback) (eg, TH Wu, "Fib").
er Network Service Survivability, "Artech hou
se, 1992). As explained for the 4-fiber ring,
Since loopback is performed, the total transmission distance may be longer than one round of the ring.

On the other hand, by using a four-fiber bidirectional ring, failure recovery is performed at a relatively high speed (SONET).
In the case of the above, about 50 msec) is possible.

[0010] By using the above configuration, it is possible to configure a communication network that performs fault recovery at high speed.

[0011]

However, by using a two-fiber unidirectional ring (1 + 1 protection method), a backup path is prepared for the working path in such a way that a path opposite to the working path on the ring corresponds to 1: 1. Therefore, it is necessary to always transmit the optical signal, and the use efficiency is reduced and the cost is increased.

On the other hand, if a system that performs loopback is used for recovery from a failure such as a four-fiber bidirectional ring, if a path close to one round of the ring is used as the working path, it will be close to two rounds by loopback. Optical transmission must be performed. Even when a path of about half a ring is used as a working path, optical transmission for about one and a half rounds must be performed.

An object of the present invention is to construct a ring system having a path recovery efficiency and a failure recovery function capable of setting a long overall ring length. It is to reduce the cost.

[0014]

According to a first aspect of the present invention, there is provided a communication network / node apparatus, wherein a plurality of or a single multiplex signal input terminal for inputting a multiplex signal and a plurality or a single insertion input terminal for inserting a signal are provided. The multiplexed signal input to the multiplexed signal input terminal outputs a demultiplexed signal that is demultiplexed and demultiplexed, and a plurality of or a single demultiplexed output terminal is multiplexed with the signal input to the insertion input terminal and the demultiplexed signal and output. Plural or single insertion / demultiplexing means having a multiplexed signal output terminal, plural or single external input terminals connected to other nodes, plural or single external output terminals connected to other nodes, and plural outputs A plurality of or a single switch means having an end, a plurality of or a single merging means, a plurality or a single signal input end, and a plurality or a single signal output end, wherein the external input end of the insertion / separation / multiplexing means Is connected to the heavy signal input, multiple-signal output end of said insertion demultiplexing means connected to said external output terminal, said signal input end connected to said switching means,
The switch means is connected to an insertion input end of the insertion / separation / multiplexing means, a separation output end of the insertion / separation / multiplexing means is connected to the junction means, and the junction means is connected to the signal output end. I do.

According to a second aspect of the present invention, there is provided a communication network node device, wherein 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 plurality of or a single demultiplexed output terminal that outputs a demultiplexed signal obtained by demultiplexing the input multiplexed signal, and a multiplexed signal output terminal that multiplexes and outputs the signal input to the insertion input terminal and the demultiplexed signal. A plurality or a single insertion / separation / multiplexing means, a plurality or a single external input terminal connected to another node, a plurality or a single external output terminal connected to another node, and a plurality or a single device having a plurality of output terminals , A plurality of or a single merging means, a plurality of or a single signal input terminal, a plurality or a single signal output terminal, and exchange of control information with other nodes, and based on the control information, the optical switch. A plurality or a single control means for controlling switching of the means, 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. The signal input end is connected to the switch means, the switch means is connected to the insertion input end of the insertion / separation / multiplexing means, the separation output end of the insertion / separation / multiplexing means is connected to the merging means, The merging means is connected to the signal output terminal.

According to a third aspect of the present invention, there is provided a communication network node device, wherein 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 plurality of or a single demultiplexed output terminal that outputs a demultiplexed signal obtained by demultiplexing the input multiplexed signal, and a multiplexed signal output terminal that multiplexes and outputs the signal input to the insertion input terminal and the demultiplexed signal. A plurality or a single insertion / separation / multiplexing means, a plurality or a single external input terminal connected to another node, a plurality or a single external output terminal connected to another node, and a plurality or a single device having a plurality of output terminals Switch means, a plurality or a single merging means, a plurality or a single signal input end, a plurality or a single signal output end, and a plurality or a single signal monitoring means for monitoring a signal input to the merging means A plurality of or a single control means for exchanging control information with another node and controlling switching of the optical switch means, wherein the external input terminal is connected to a multiplex signal input terminal of the insertion / demultiplexing means, A multiplexed signal output terminal of the multiplexing means is connected to the external output terminal, the signal input terminal is connected to the switch means, and the switch means is connected to an insertion input end of the insertion / separation / multiplexing means; Is connected to the merging means, the merging means is connected to the signal output end, and the control means monitors a signal input to the merging means of the signal monitoring means and a signal from the other node. The switching device is controlled based on a result of the transfer of the control information.

According to a fourth aspect of the present invention, there is provided the communication network node device according to the first, second, or third aspect, wherein the insertion / demultiplexing means is an optical signal insertion / demultiplexing means. I do.

According to a fifth aspect of the present invention, in the communication network / node apparatus according to the first, second, or third aspect, the insertion / demultiplexing means is means for performing wavelength insertion / demultiplexing. And

The operation of the present invention will be described below.

In the system described in the present invention, when a failure occurs, failure recovery is performed by using a shared spare resource and setting and switching a detour around the path in which the failure has occurred in the reverse direction in units of optical paths. In addition, there is no need to perform loop-back switching, and there is no need to perform one or more rounds of optical transmission. or,
In the present invention, the path switching method is used. However, since the spare resources are shared, the path accommodation efficiency is increased. This is because, when the conventional 1 + 1 protection method is used, the backup path must always be operated, so that one wavelength in one round of the ring and a maximum of two paths (up and down directions between certain nodes). However, in the system described in the present invention, since the spare resources are shared among all the working resources, the number of nodes between the maximum adjacent nodes in one wavelength in one working ring (the number of nodes) ) Alone can accommodate the path. Since the loopback is not performed and the path accommodation efficiency is simultaneously improved, the cost of the communication network is reduced.

In particular, in the case of a wavelength division multiplexing system, it is difficult to monitor wavelengths in units originally bundled, and it is necessary to perform management in units of wavelengths. The cost can be reduced because it can be introduced as it is. In particular, a system having a small number of paths, such as a wavelength multiplexing system (the number of paths does not increase because there is a physical restriction on the number that can be wavelength multiplexed) or a system handling a high speed signal in which many low speed signals are multiplexed. When the present invention is applied to the present invention, the number of paths to be managed can be reduced, the management cost is reduced, and the effect is further increased.

[0022]

Next, embodiments of the present invention will be described with reference to the drawings.

The first embodiment will be described with reference to FIG. FIG. 1 is a block diagram of an optical wavelength division multiplexing communication network according to a first embodiment of the present invention. 105-1
08 is an optical communication network node. These nodes form a four fiber ring by connecting the fibers to form a ring topology. 101 and 103 represent working rings, and 102 and 104 represent spare rings. Each node includes a clockwise working signal processing unit (121 in node 108) for processing a clockwise working ring signal, and a counterclockwise working signal processing unit (node 108 for processing a counterclockwise working signal). Has 122). The clockwise working section is the working ring 101
And the signal (at the time of failure) of the counterclockwise spare ring 102 are handled. The counterclockwise working signal processing unit handles the signal of the counterclockwise working ring 103 and the signal of the clockwise backup ring 104 (when a failure occurs). Each node separates and inserts the wavelength-multiplexed demultiplexed signal. For example, from the node 105, the optical signals 109 to 112 are wavelength division multiplexed and output. Reference numerals 109 and 110 denote optical signals wavelength-division multiplexed and demultiplexed from the working ring 101, and reference numerals 111 and 112 denote optical signals wavelength multiplexed and demultiplexed from the working ring 103. 1
Optical signals 13 to 116 are inserted. Reference numerals 113 and 114 denote optical signals to be inserted into the working ring 101.
Is an optical signal to be inserted into the working ring 103. During the ring, two wavelengths λ1 and λ2 in the 1.5 μm band are used as the wavelength of the main signal light for transmitting data. Thus, for example, 113,
It is possible to assign a wavelength of λ1 to 115 and a wavelength of λ2 to 114 and 116. In addition to the main signal light, a 1.3 μm band control signal light (wavelength: λs) for exchanging control signals between adjacent nodes is wavelength-multiplexed with the main signal light and transmitted. Although the separation signal and the insertion signal are shown only for the node 105, the other nodes 106 to 108 have the same functional configuration.

FIG. 2 shows a clockwise working signal processing unit 200 (12 in FIG.
1) is shown. Reference numerals 201 and 205 denote external input terminals.
Reference numerals 4208 denote external output terminals, each of which is connected to another node using an optical fiber. The optical fiber of the working ring 101 is connected from the node 105 to the external input terminal 201, and is connected from the external output terminal 208 to the node 107. The optical fiber of the spare ring 102 is connected from the node 107 to the external input terminal 205, and is connected from the external output terminal 204 to the node 105. 221,
A control signal separator 223 separates an optical signal input from an external input terminal, and sends out a 1.5 μm wavelength-multiplexed main signal light to the optical ADM units 209 and 210, respectively.
μm control signal light (λs)
Input to 6. As the control signal separators 221 and 223, it is possible to use a WDM coupler that separates a wavelength in the 1.3 μm band and a wavelength in the 1.5 μm band. 202,
203 denotes an optical signal (λ1 or λ2) demultiplexed by wavelength division.
, And 206 and 207 are separate input terminals for inputting one-wave optical signal (λ1 or λ2), and are respectively a SONET terminator and an ATM switch (eg, TH Wu, “Fiber Network”). ServiceSurviv
209, 210 are optical ADM units. The optical ADM unit 209 performs wavelength multiplexing on wavelength multiplexed light input from the external input terminal 201. 218,220 separated
, Or multiplexed and output to the external output terminal 208. The optical ADM unit 210 demultiplexes the wavelength-division multiplexed light input from the external input terminal 205 into 217, 21
9 or multiplexed and output to the external output terminal 204. Reference numerals 217 to 220 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, connected to the monitoring controllers 215 and 216, and most of the remaining optical signals (for example, 90 % Of the optical power) is output to the optical switch 213 and the optical switch 214.

Reference numerals 211 to 214 denote 2 × 1 optical switches, and mechanical optical switches can be used. Optical switches 213 and 214 are connected to wavelength-division multiplexed outputs from optical ADM units 209 and 210 using an optical fiber, and optical signals input to external input terminal 201 are wavelength-division multiplexed or externally input. One of the wavelength division multiplexed optical signals input to the terminal 205 is selected and output to the demultiplexing output terminals 202 and 203, respectively. Similarly, an optical signal of one wavelength is input to each of the optical switches 212 and 211, and by switching the optical switches 212 and 211, the wavelengths are multiplexed by the optical ADM units 209 and 210, respectively, and the external output terminals 208 and 204 are output. Can be selected to output to either of the above.

Reference numerals 215 and 216 denote monitoring controllers, which monitor the tapped optical signals, and switch the optical switches 211 to 214.
To send a switching control signal. Monitoring controller 215, 2
In step 16, an optical receiver is installed at the input end of the monitoring control unit to monitor the bit error rate of the input optical signal and monitor the transmission quality of the optical signal (using a SONET frame as the optical signal and using B1 It is possible to monitor the bit error rate by monitoring the bytes; for example, TH Wu,
"Fiber Network Service Survivability," Artec
h house, 1992). In the node 108, the clockwise working signal processor normally monitors the error rate of the optical signal transmitted from the external input terminal 201 to the working ring 101, and determines whether the optical signal is transmitted normally. to manage. The monitoring control unit is connected to the optical switches 211 to 214, and according to information of the monitoring control unit, the optical switches 211 to 214.
It is possible to switch.

Control signal multiplexers 222 and 224 are connected in front of the external output terminals 204 and 208, respectively.
The control signal light (1.3 μm band) transmitted from the monitoring controllers 215 and 216 to other nodes and the main signal light (1.5 μm band)
Band) is wavelength-multiplexed. As the control signal multiplexer, a WDM coupler can be used similarly to the control signal separators 221 and 223. Control signal separators 221, 22
3. By superimposing and separating the control signal light on the main signal light using the control signal multiplexers 222 and 224, it is possible to exchange control signals with other nodes.

Since the control signal light from the other node is also input to the monitoring control unit, both the switching based on the control information from the other node and the switching based on the monitoring result of the optical signal of the own node are possible. .

The counterclockwise working signal processing section can also use the same configuration as 200 in FIG. Similarly, a clockwise working signal processing section, a counterclockwise working signal processing section, and a working ring 10
3. It is possible to connect to the spare ring 104. Nodes other than the node 108 can also be configured similarly and connected to the optical fiber of the ring.

FIG. 3 shows an optical ADM unit 2 used in FIG.
09, 210. Reference numeral 300 denotes an optical ADM unit. Reference numeral 301 denotes a multiplexed signal input terminal for inputting a wavelength-multiplexed signal light, and reference numeral 306 denotes a multiplexed signal output terminal for outputting a wavelength-multiplexed optical signal. Reference numerals 302 and 303 denote demultiplexed signal output terminals for demultiplexing and outputting the optical signal input to the multiplexed signal input terminal 301. 304 and 305 are insertion signal input terminals for inputting one-wave optical signal. 314 is a wavelength multiplexing / demultiplexing device, 307 is a wavelength multiplexing wave device, and AWG
(Arrayed-waveguide grating
g: For example, K. Okamoto et al., "Fabrication of
unequal channel spacing arrayed-waveguidedemul
tiplexer modules, "Electron. Lett., 1995, vo
l.31, no.17, pp.1464-1465.) can be used. Reference numerals 310 and 311 denote optical gate switches, and a mechanical optical switch or a gate switch using a semiconductor optical amplifier can be used. 312,313
Is an optical splitter that splits the power of the input light into two, outputs one to separate output terminals 302 and 303, and outputs the other to optical gates 310 and 311 respectively. 3
Reference numerals 08 and 309 denote optical couplers.
4. Signal light from insertion signal 305 and optical gates 310 and 3
11 are combined and output. 3
Reference numeral 07 outputs wavelength-multiplexed light obtained by multiplexing the outputs from the optical couplers 308 and 309. Optical gate 310, optical gate 3
By turning 11 on or off, it is possible to select whether the signal to be input to the wavelength division multiplexer 307 is from the output of the optical splitter or from the insertion signal input terminal. It is possible. In the configuration of FIG. 3,
Since the light is branched by the optical branching devices 312 and 313, an optical signal is always output to the branch signal output terminal.

Next, a description will be given of a failure recovery operation using the node configuration of FIG. 2 and the network of FIG. 1 with reference to FIGS.

FIG. 4 shows a main signal, a control signal after the occurrence of a fault, and operation steps in each node in the network of FIG. Hereinafter, an optical path is defined as a period from a time when an electric signal is converted into an optical signal at a certain node and sent to another node until the electric signal is converted again into an electric signal. 1 for optical path
Wavelengths correspond. Reference numeral 401 denotes a working optical path for transferring the working main signal light, which is terminated at the node 108 from the node 106 (source node: transmission node) via the node 105 and uses the wavelength of λ1. Normally, the spare ring is not used, and an optical path is set in the spare ring and used only when a failure occurs. In the spare ring, all nodes are set in advance so that all optical signals arriving from other nodes pass through as they are. this is,
This can be realized by setting the optical gates 310 and 311 in FIG. 3 to the On state in the spare ring. Now node 1
A failure recovery operation when a break failure occurs in all the optical fibers between the optical fiber 06 and the node 105 will be described. Since the optical fiber is broken, the optical path 401 is connected to the terminal node 108.
The monitoring controller 215 in the clockwise working signal processing unit of the node 108 first detects the deterioration of the bit error rate and recognizes the failure of the optical path 401 (step 1).

When the supervisory controller detects a fault in the working optical path, the node 108 switches the optical switch 213 to select and output the optical signal from the spare ring 102 (external input terminal 205) (step 2), and the source node 106 The monitoring controller is set in advance so that the switching request message is transmitted to the destination in the direction in which no failure has occurred using the control signal light (λS) (step 3). The control signal light includes
The information can include a destination node, an optical path name, and control contents. For example, this can be realized by allocating information to the position and value of a framed bit such as SONET section overhead. For example, the first 8 bits of the framed bit string are assigned to the destination node name, the next 8 bits are assigned to the identifier of the optical path, and the next 1 bit is assigned whether or not a switching request is required. If a frame configuration in which a total of 17-bit bit strings are connected by the number of wavelengths is used, optical path switching request messages for the number of wavelengths can be transmitted collectively. In this case, it is possible to send a message amount that can cope with a single failure that an optical fiber between certain nodes is broken.

Using the control system set as described above, when the node 108 recognizes a failure in (step 1), the node 108 selects a signal from the backup ring 102 (the same wavelength as the working optical path: λ1). Then, the optical switch 213 is switched (step 2), and sends an identifier of the working optical path and a switch request message (λS) to the source node (step 3).

The node 107 receives the control signal light, but transfers the control signal light to the node 106 as it is not a message addressed to the own node (step 4). When the control signal light arrives at the node 106, it is a message addressed to the own node.
The optical switch corresponding to 2 is switched and the working ring 101 is switched.
The optical signal (.lambda.1) of the working optical path 401 transmitted to the backup ring 102 is transmitted to the backup ring 102 (step 5). Node 10
7 is not set to receive the light having the wavelength of λ1 of the standby ring 102, and is set in a state where the optical signal is allowed to pass through to the other node in advance, and the node 108 is set to the wavelength of λ1 of the standby ring 102. (Step 2), the optical switch 21 of the node 108
Reference numeral 3 selectively outputs the optical signal of the wavelength λ1 from the protection ring 102 (formation of the protection light path 402), and the failure of the working light path 401 is recovered by using the protection light path 402.

In the present embodiment, after step 2 (switching of the optical switch 213), step 3 (sending a switch request message to the source node) is executed, but (step 2) and (step 3) The present invention can be practiced without any trouble even if the order is reversed. If the time required for message transmission governs the failure recovery speed, the message is transmitted first, so that the overall failure time is reduced.

FIG. 5 shows a sequence chart of the inter-node communication and the operation at the node. The vertical axis is the time axis,
The lower the time, the later the time.

FIG. 6 shows an example of a flowchart of control to be provided in the monitoring controller of each node in order to realize this sequence. Reference numeral 601 denotes a branch, which is classified according to whether or not a failure in the terminal signal of the own node is detected. The act of recognizing the failure of the own node termination signal is defined as (step 1). A procedure 602 confirms that no failure has occurred in the own node and recognizes that the failure recovery has been completed (step 6). 605 is a procedure,
By switching the optical switch, an arrangement for receiving an optical signal from the spare ring is made (step 2). A procedure 606 transmits a control message to the source node of the failed optical path (step 3). 603
Is a branch, and it is determined whether a control signal sent from another node is addressed to the own node. Reference numeral 607 denotes a procedure. When a control message addressed to another node arrives, the control message is directly transferred to the other node (step 4). Reference numeral 604 denotes a branch, which determines whether the arrived control signal is a switch request addressed to the own node. Reference numeral 608 denotes a procedure, which refers to the identifier of the optical path specified by the arrived control signal and switches the corresponding optical path to be transmitted to the backup ring.

If such a flowchart is applied to each node, a failure recovery as shown in FIG. 4 can be performed.

In the above, the method of recovering the failure of the working optical path having the wavelength of λ1 has been described. It is possible to perform failure recovery of all the optical paths passing through (including different source nodes and terminal nodes). This will be described below. 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 that transmits a signal in the direction opposite to the transmission direction of the working ring, wavelength collision (the same wavelength is assigned to the optical path in one optical fiber and can be separated). It is possible to allocate a backup optical path without the loss. Accordingly, for any single failure, the failure of all the optical paths passing therethrough can be recovered. Further, even when multiple failures occur, it is possible to cope with the situation where the route opposite to the working optical path is safe.

The method of recovering the failure of the working optical path of the working ring 101 using the spare ring 102 as a shared spare resource and its node configuration have been described above. The working ring 103 (the reverse of the working ring 101) has been described. The same node configuration and failure recovery method can be applied to the backup ring 104 and the same ring. 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 resource is shared, so that in preparation for the next failure, The original path is restored so that transmission is performed using the working optical path 401 without using the optical path 402.

By using the first embodiment, failure recovery is performed without performing loopback switching, so that the transmission distance of the optical signal can be reduced. Therefore, when the distance over which the light can be transmitted as it is is determined, it is possible to configure a ring having a longer overall length than a system that performs loopback. Also, unlike the 1 + 1 protection, the spare resources are not used exclusively, and the spare resources are shared, so that the number of working optical paths to be operated can be increased. In the 1 + 1 method, when the shortest route is set as the communication in the up direction, the down direction always uses the route in the same direction as the shortest route, so that the accommodation of the optical path becomes inefficient. For example, in the 1 + 1 method, 1
At one wavelength, only two optical paths can be formed per ring (in FIG.
2 and the optical path from node 1107 to node 1106).
By using this configuration, for example, as shown in FIG. 7, up to four optical paths can be configured with one wavelength. In FIG. 7, reference numerals 701 to 704 denote working optical paths whose wavelength is λ1,
101 indicates a working ring and 102 indicates a spare ring. 70
The protection resource for the working optical paths 1 to 704 is the protection ring 102, which is shared between the respective working optical signals. For example, the backup optical path for the working optical path 701 uses the wavelength λ1 on the backup ring 102 in the path of node 106 → node 105 → node 108 → node 107. The backup optical path for the working optical path 702 is on the backup ring 102 from the node 107 to the node 106 to the node 105.
→ The wavelength λ1 can be used in the route of the node 108. In the section from the node 106 to the node 105 to the node 107, the same wavelength λ1 is used and shared as a backup optical path. Since these spare optical paths are independent events (for a single failure), the spare ring 102
This is because the spare resource of λ1 in the middle can be shared between the working optical paths 701 and 702. Similarly, in the case of FIG. 7, the working optical paths 701 to 7
04, the wavelength λ1 which is a spare resource of the spare ring 102.
Will be sharing. The same applies to optical paths of other wavelengths. In addition, since the spare resources are shared, a clockwise working ring and a counterclockwise working ring can be independently set for an optical path in communication between certain nodes. Setting to makes efficiency higher.

Also, messaging for failure recovery is
At best, you only need to go around the ring once, so SONET
It is possible to perform the fault recovery at the same speed as the operation speed of the fault recovery of the four-fiber bidirectional ring.

In the 1 + 1 protection method, since an optical signal is always transmitted to the protection path, the protection resource is used even when no failure occurs. On the other hand, when the present configuration and method are used, when no failure occurs, a spare resource can be used, and a low-priority optical path can flow there (standby access). When a failure occurs because the priority is low, it may be used as a backup optical path for another high-priority optical path, but it is possible to configure a low-priority optical path when no failure occurs. There are advantages.

Further, in the SONET system, if a signal that bundles paths is monitored in units of a monitoring line (a unit of a signal in which a path between adjacent nodes is multiplexed), the quality of a path signal (for example, an error rate) can be reduced. It was possible to do. However, in a wavelength division multiplexing system, it is originally necessary to always manage wavelengths between nodes, and it is difficult to operate a management system only by managing a bundle of optical paths.
Therefore, the configuration and method of the present invention can be applied to a management and monitoring system in the case of performing a fault recovery for each optical path, which is more effective.

In the current SONET system, 50M
Although b / s is handled as a path unit, a path managed by handling switching in a path group unit (for example, a 2.5 Gb / s unit in which a 50 Mb / s signal is bundled) in which these are bundled. And the effect of applying this method increases. Even in the case of light, since the number of wavelength multiplexes is limited to some extent due to physical restrictions, the number of paths does not increase very much, which is more effective.

Also, by using the first embodiment, even if a failure occurs, only the terminal node and the source node of the optical path need to switch to recover the failure of the optical path. A node in the middle of the path only needs to transfer the switching request message sent from the terminal node to the source node, so that control is simple and the fault recovery speed is high.

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 allocated 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. Can be allocated to λ3 and λ4 of the clockwise ring. Therefore, 2
A fiber ring can be considered in the same manner as a four-fiber ring. The resources of λ1 and λ2 of the clockwise ring correspond to the working ring 101 of FIG.
3, .lambda.4 correspond to the spare ring 102 of FIG. 1, the left-handed rings .lambda.1, .lambda.2 correspond to the working ring 103 of FIG. 1, and the right-handed rings .lambda.3, .lambda.4 correspond to the spare ring of FIG. Specifically, 4 described in the first embodiment.
It can be seen that the same operation as the fiber ring is possible. In the node configuration, λ1 and λ2 are used for the working optical path and λ3 and λ4 are used for the backup optical path. Therefore, as compared with the four-fiber node configuration in FIG.
12 is inserted between the output end of the optical switch 12 and the optical ADM unit 209, and a wavelength converter for converting an input optical signal into λ1 is inserted between the output end of the optical switch 212 and the optical ADM unit 210. Is inserted between the output terminal of the optical switch 211 and the optical ADM unit 209, and a wavelength converter for converting the input optical signal into λ2 is inserted between the output terminal of the optical switch 211 and the output terminal of the optical switch 211. It is necessary to insert a wavelength converter for converting an input optical signal into λ4 between the optical ADM unit 210 and the optical ADM unit 210. 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.

The use of the second embodiment has the same effects as those of the first embodiment. The difference from the first embodiment is that the number of fibers used (the number of rings) is half, so that it is particularly effective when the optical fiber laying cost accounts for a large part of the cost or when only two fiber rings can be constituted by all means. Is increased.

In the second embodiment, a wavelength converter having a fixed wavelength output is inserted into 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 second ring transmit optical signals in opposite directions. The wavelength for transmitting the working signal of the first ring is λ
1, λ2, and as a spare resource, the wavelength λ of the second ring to 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. [Lambda] 3 and [lambda] 4 are used as the wavelengths for transmitting the working signal of the second ring, and the first resource is used as a spare resource for the working optical path of the second ring at the wavelength [lambda] 3.
Λ3 of the first ring and λ4 of the first ring are used for the working optical path of the wavelength λ4 of the second ring. If the same wavelength is assigned to the two fiber rings as the working wavelength and the protection wavelength as the working wavelength and the protection wavelength, respectively,
It is no longer necessary to use the wavelength converter used in the embodiment. In the second embodiment, in a certain source node, the wavelength λ1 is used for the working optical path and the wavelength λ3 is used for the backup optical path.
Since the wavelength converter was used, a wavelength converter was necessary. However, if the third embodiment is used, the wavelength used for the working optical path and the wavelength used for the backup optical path are the same, so that there is no need for wavelength conversion. is there.

When the third embodiment is used, the same effects as those described in the second embodiment are obtained, except that the wavelength converter is not required.

In the embodiment of the present invention, the case of a fiber failure has been described. However, it is obvious that the same method can be used to recover from a failure such as a node failure.

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 can be performed by using the method of monitoring the optical power. This can be realized by installing a photodiode at the input end and monitoring its photocurrent. Other, light S
It is possible to apply monitoring / N (signal-to-noise ratio). The S / N of light can be obtained by obtaining the ratio between ASE (spontaneous emission light noise) and signal light.

In the embodiment of the present invention, a sequence as shown in FIG. 5 is used. However, for example, the present invention can be implemented without any trouble even if the order of step 2 and step 3 is changed.

In the embodiment of the present invention, a flowchart as shown in FIG. 6 is used for controlling each node. However, it is apparent that the same control is not necessarily used. For example, branch 603 and its associated procedure 6
07 and the branch 604 and the accompanying procedure 608 are grouped in reverse order (after the branch procedure 602, the branch 60
It is obvious that the present invention can be implemented without any problem.

In the embodiment of the present invention, a ring using an optical path in a wavelength division multiplexing system has been described.
It is obvious that the present invention can be applied to a system in which paths such as SONET and SDH are time-multiplexed. However, since the transmission distance of the optical signal can be reduced by not performing the loopback switch, it is possible to increase the ring length. Is more effective in applying (the SONET ring converts an optical signal into an electric signal for each node and reproduces the signal). Also, the optical path is 10 Gb / s regardless of the optical signal of 2.5 Gb / s.
Irrespective of the optical signal, there is only one optical path.
Even in a system in which a Gb / s optical path and a 10 Gb / s optical path coexist, the same node configuration and failure recovery method as in the first embodiment can be used, and flexibility is high. .

In the embodiment of the present invention, a method using an optical path in a wavelength division multiplexing system has been described.
TM VP (Virtual Path) and VC (Vi
It is obvious that the present invention can be applied to a real channel as long as it is a ring network.

In the embodiment of the present invention, the configuration of FIG. 3 is used as the configuration of the optical ADM unit. However, the configuration of FIG. 8 and the configuration of FIG. 9 can be used.

FIG. 8 shows another embodiment of the configuration shown in FIG. 3, in which a 2 × 2 optical switch is inserted between the wavelength division multiplexer 314 and the wavelength division multiplexer 307. It is configured to switch to an insertion signal input terminal or a separation signal output terminal. In the configuration of FIG. 3, an 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, the 2 × 2 optical switch is used. It is output to the separation signal output terminal only when it is in the cross state.

FIG. 9 shows another embodiment of the configuration shown in FIG. 3, in which a part of the output of the wavelength division multiplexer is directly connected to the wavelength division multiplexer, and another part is output. Is directly connected to the separation signal output terminal. These cannot switch the operation of separation and insertion, but the failure recovery operation of the present invention can be performed by applying to the optical ADM unit of FIG.

Even if other configurations or a combination of these configurations are used, a multiplexed signal is input, a part of the multiplexed signal is output, a part of the multiplexed signal is input to the multiplexer, and a part is input to the multiplexer. It is obvious that the present invention can be applied to any configuration that can input an insertion signal.

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. Obviously it is not.

In the embodiment of the present invention, a frame structure is used as a method of transferring a control signal to another node. The first 8 bits are a destination node name, the next 8 bits are an optical path identifier, and the next 1 bit. , The presence / absence of a switching request is assigned. However, even if this is not the same, any bit assignment method may be used as long as the request for path failure recovery is transmitted to the source node. Also, there is no need to assign information to bits,
It is also possible to use message-oriented communication. It is also possible to use packet communication, frame relay, and communication using ATM.

In the embodiment of the present invention, an optical signal having a wavelength different from that of the main signal is used as the control signal transfer means.
It is obvious that there is no need to use a different wavelength from the main signal, and any medium that can transfer control information can be applied. For example, the present invention can be applied to a case where control information is exchanged between nodes using a system in which a radio signal or a subcarrier is superimposed on an optical signal and transmitted, or a control signal is exchanged using a telephone line. it is obvious.

In the embodiment of the present invention, the event of detecting the failure of the own node termination signal is used as a trigger for starting the failure recovery operation. However, the failure recovery operation is started by a failure notification from another node or another network device. However, it is clear that the present invention can be practiced without hindrance. For example,
Even if a method is used in which a node at a stage preceding the node that terminates 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, a failure recovery operation is performed to perform the failure recovery. The invention can be implemented without hindrance.

In the configuration of the present invention, when no failure has occurred, the spare ring is set to allow all optical signals to pass. However, this setting can also be performed when a switch request message arrives from the terminal node. It is obvious that the present invention is applicable. However, if this method is used, the optical gate is switched after the switch request message arrives, so that the failure recovery time may be delayed.

In the embodiment of the present invention, a case has been described where the traffic between nodes is symmetrical in the upstream and downstream directions. However, when the traffic between nodes is asymmetric in the upstream and downstream directions (for example, System with only one-way communication)
However, it is obvious that the present invention can be applied.

In the embodiment of the present invention, a system using one fault recovery system in one ring system has been described. However, the present invention can be realized by combining the configuration and method of the present invention with other systems such as the conventional 1 + 1 protection system. It is. For example, for each wavelength, λ1 and λ2 can be used for the failure recovery method by the 1 + 1 method, and λ3 and λ4 can be used for the failure recovery according to the present invention. Further, it is not always necessary to detour in the direction opposite to the direction of transmission of the working optical path. For example, when a failure occurs only in the working ring between nodes and the spare ring is safe, a detour is assigned to the shortest path on the spare ring. In this case, the switch request message is sent in both clockwise and counterclockwise directions.

In the embodiment of the present invention, the optical switch 21
Although a mechanical optical switch is used as 1-214, any optical switch that satisfies the performance such as crosstalk and loss can be used as an optical switch using the electro-optical effect, an optical switch using the thermo-optical effect, or a semiconductor optical switch. The present invention can be implemented by an optical gate switch using an amplifier.

In the embodiment of the present invention, the optical switch 21
An optical switch in which a signal is not distributed to another path when a certain path in the switch is made conductive as 1 to 214 is used. For example, a distribution selection type switch having a configuration in which a semiconductor gate switch is connected to the branch side of an optical coupler ( It is obvious that the present invention can be applied even if a switch capable of multicasting is used, if the multicast function is blocked by a gate.

In the embodiment of the present invention, the optical switch 21
A 2 × 1 optical switch was used as 1-214.
The present invention is applicable to a switch having a different size and configuration from one switch. For example, as the optical switch 212, 2
It is possible to connect a spare network device to the input terminal of the optical switch to which the separate input terminal 207 is not connected by applying the × 2 switch. In addition, a distribution selection type 2 × 2 switch is used as the optical switch 213, one of the output terminals of the optical switch is connected to the separation output terminal 202, and the other is connected to the optical signal monitoring device to monitor the optical signal. Obviously, the present invention can be practiced without any trouble.

1 × 2 optical switch 21 for switching the transmission side
The distribution-selection type optical switch used as 1 or 212 can be realized by a configuration in which an optical gate switch (a switch that switches between passing and not passing light) is connected to a branch portion of the coupler. In addition, it is also possible to use a configuration in which the optical gate switch is connected to one output terminal of the optical gate switch and the optical gate switch is not connected to the other output terminal. The output of the optical switch to which the optical gate switch is connected may be connected to the spare ring, and the output of the optical switch to which the optical gate switch is not connected may be connected to the working ring. Normally, it is necessary to prevent signal light from flowing through the spare ring, so it is necessary to connect an optical gate switch and turn on / off the signal. However, even if an optical signal flows through the working ring, the optical switch 21 at the terminal node may be used.
3, 214, it is possible to select the optical signal of either the working ring or the spare ring.

Further, in the case of a system having n spare rings having a shared spare resource for the working signal, in order to enable switching to all the working rings to the working ring, (n +
1) It is necessary to use a × 1 optical switch. It is obvious that the present invention can be applied to a general mxn switch in which a plurality of such switches are integrated.

In the embodiment of the present invention, the optical switches 211 to 214 are used as the switches on the transmission side and the reception side. However, the optical switches 211 to 214 are directly connected to the demultiplexed output terminal and demultiplexed input terminal without switching, and It is obvious that the present invention can be implemented by performing protection by an electric switch after converting a signal into an electric signal.

As the electric switch, an electric switch for spatially switching, an electric switch for switching a time-division multiplexed signal obtained by time-division multiplexing, and a connection established by a cell like an ATM switch. The present invention can be practiced without any problem even with an ATM switch that switches between.

In the embodiment of the present invention, an optical coupler having a branching ratio of 10:90 is used for monitoring an optical signal. However, if there is no problem in optical level design, the optical power branching ratio and coupling ratio are particularly limited. It is self-evident that nothing is done.

In the embodiment of the present invention, the case of a four-node, two-wavelength ring has been described. However, it is obvious that the present invention can be applied to a system other than the number of nodes and the number of multiplexed wavelengths.

In the embodiment of the present invention, a configuration in which all optical signals can be inserted and separated is used. However, it is apparent that the present invention can be applied to a configuration in which not all wavelengths can be inserted and separated.

Although the embodiment of the present invention is based on the premise that a wavelength multiplexed system is used, it is clear 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 examined. However, the present invention can be implemented even if other multiplexing techniques such as polarization multiplexing, time multiplexing, and spatial multiplexing are applied. Clearly, it is possible. 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 constituted by the optical fiber group is connected to one. The present invention can be applied by treating it as a 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. If there are two rings in the fiber group, the second embodiment can be used. This is because it can be handled in the same manner as in the third embodiment.

As an embodiment of the present invention, a case of two fibers and a case of four fibers have been described, but the present invention is not limited to this. For example, if a spare ring serving as a shared spare resource is increased clockwise and counterclockwise one by one from a four-fiber system and a switch used for failure recovery is a 3 × 1 switch, the present invention can be applied to a six-fiber ring. it can. 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 logically it can be regarded as two rings around opposite directions. 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, the receiving node switches the ring to be received by using a switch. However, when a failure occurs, the optical signal of the failed one is not input to the receiving node (the source node switches to send a signal to the detour), so the receiving node: Only the optical signal from the non-failed ring is input to the signal termination node. Therefore, it is not necessary to select which ring to receive by using an optical switch, and the present invention can be implemented without any trouble by using an optical coupler. Therefore, as an example of the merging means in the claims of the present invention, it is possible to use a coupler type such as an optical coupler for adding power or a switching type such as the optical switch described in the embodiment of the present invention. is there.

In the embodiment of the present invention, an AWG is used as a wavelength multiplexer and a wavelength demultiplexer. However, an AWG using a diffraction grating, a fiber Bragg grating (a fiber having a periodic structure in a fiber). It is obvious that the present invention can be implemented without any trouble if a device having a function of multiplexing wavelengths or performing wavelength multiplexing / demultiplexing, such as a combination of filters having a configuration, is used.

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

In the embodiment of the present invention, the optical communication network has been described in which an optical signal passes through a node on the way without being converted into an electric signal without converting the optical signal into an electric signal. It is obvious that the present invention can be carried out without any trouble even if a device for converting the data into the data is inserted.
By installing such a device, the length of the ring can be increased.

In the embodiment of the present invention, an optical path without wavelength conversion is used as an optical path. However, a wavelength converter is inserted into a ring network, and an optical path with wavelength conversion performed as an optical path is used as an optical path. Even if handled, the present invention can be implemented without any trouble. As a wavelength converter, a method of once converting an optical signal into an electric signal and then converting it again to an optical signal using a light source of a desired wavelength, a method using mutual gain modulation, mutual phase modulation, four-wave mixing, etc. But it can be applied. By using the wavelength converter, it is possible to reuse the wavelength in the spare ring by allocating the spare optical path well (to reuse the same wavelength in the same ring), so that multiple failures such as a double failure are caused. Resistance is improved.

In the embodiment of the present invention, the spare ring does not transmit light when no failure occurs.
The present invention can be applied to a method of transmitting an optical signal even when no failure has occurred in order to confirm whether or not a failure has occurred in the transmission system using the backup ring. For example,
The backup ring is periodically operated to configure all the backup paths, and the backup optical path is periodically monitored. When a failure is detected or a switch request message is received, the backup path is configured for monitoring. Instead, a method of configuring only a spare optical path for failure recovery 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, both the right-handed communication and the left-handed communication failure occur simultaneously. Even so, the present invention can be applied. This is because, in the present invention, each of the shared spare resources is independently assigned, and each of them can form a detour independently.

[0092]

According to the present invention, since the failure recovery is performed without performing the loop-back switch, the total transmission distance of the optical signal can be reduced. Therefore, when the distance over which light can be transmitted as it is is determined, it is possible to configure a ring having a longer overall length than a system that performs loopback. Also, unlike the 1 + 1 protection, the spare resources are not used exclusively, and the spare resources are shared, so that the number of working optical paths to be operated can be increased. Therefore, it is possible to realize a ring system having a failure recovery function having both features of path accommodation efficiency and a long overall ring length, and to construct a communication network at low cost.

[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 showing a clockwise working signal processing unit used in FIG. 1;

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

FIG. 4 is a diagram illustrating a failure recovery operation used in the first embodiment.

FIG. 5 is a sequence chart illustrating a failure recovery operation used in the first embodiment.

FIG. 6 is a flowchart in one node illustrating a failure recovery operation used in the first embodiment.

FIG. 7 is a diagram for explaining an effect of the system used in the first embodiment.

FIG. 8 is a block diagram showing another embodiment of FIG. 3;

FIG. 9 is a block diagram showing another embodiment of FIG. 3;

FIG. 10 is a block diagram showing a conventional example.

FIG. 11 is a block diagram showing a conventional example.

[Explanation of symbols]

 101, 103 working ring 102, 104 spare ring 200 clockwise working signal processing section 211-214 optical switch 215, 216 monitoring controller 217-220 optical splitter 310, 311 optical gate 401 working optical path 402 spare optical path 1021 working light Path 1022 Backup optical path 1121 Working optical path 1122 Backup optical path

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04J 14/02 H04B 9/00 H H04L 12/42 F-term (Reference) 5K002 DA02 DA04 DA09 DA11 EA33 FA01 5K031 AA02 AA08 CA08 CA15 DA11 DA19 DB14 EA01 EB02 EB05

Claims (5)

[Claims] A demultiplexed signal obtained by demultiplexing a plurality of single signal input terminals for inputting a multiplex signal, a plurality of single input terminals for inserting a signal, and a multiplex signal input to the multiplex signal input terminal. And / or a single or multiple insertion / demultiplexing unit having a plurality of / single demultiplexing output terminals for outputting a signal and a multiplexed signal output terminal for multiplexing and outputting the signal input to the insertion input terminal and the demultiplexed signal, and another node. A plurality or a single external input terminal connected to the other 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 and a plurality or a single signal output terminal, wherein the external input terminal is connected to a multiplex signal input terminal of the insertion / separation / multiplexing means, and a multiplex signal output terminal of the insertion / separation / multiplexing means; Said Unit, the signal input end is connected to the switch means, the switch means is connected to the insertion input end of the insertion / separation / multiplexing means, and the separation output end of the insertion / separation / multiplexing means is connected to the merging means. A communication network node device, wherein said connection means is connected to said signal output terminal. 2. A demultiplexed signal obtained by demultiplexing a plurality of single signal input terminals for inputting a multiplex signal, a plurality of single input terminals for inserting a signal, and a multiplex signal input to the multiplex signal input terminal. And / or a single or multiple insertion / demultiplexing unit having a plurality of / single demultiplexing output terminals for outputting a signal and a multiplexed signal output terminal for multiplexing and outputting the signal input to the insertion input terminal and the demultiplexed signal, and another node. A plurality or a single external input terminal connected to the other 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, Plural or single signal input terminal, plural or single signal output terminal, plural or single control means for exchanging control information with other nodes and performing switching control of the optical switch means based on the control information. Wherein 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, and the signal input terminal is connected to the switch means. The switch means is connected to an insertion input end of the insertion / demultiplexing means, the separation output end of the insertion / demultiplexing means is connected to the joining means, and the joining means is connected to the signal output end. Characteristic communication network node device. 3. A demultiplexed signal obtained by demultiplexing a plurality of single signal input terminals for inputting a multiplex signal, a plurality of single input terminals for inserting a signal, and a multiplex signal input to the multiplex signal input terminal. And / or a single or multiple insertion / demultiplexing unit having a plurality of / single demultiplexing output terminals for outputting a signal and a multiplexed signal output terminal for multiplexing and outputting the signal input to the insertion input terminal and the demultiplexed signal, and another node. A plurality or a single external input terminal connected to the other 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 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 of The external input terminal is connected to the multiplexed signal input terminal of the insertion / demultiplexing means, and the multiplexed signal output terminal of the insertion / demultiplexing means is connected to the external output terminal. Connected, the signal input end is connected to the switch means, the switch means is connected to the insertion input end of the insertion / separation / multiplexing means, the separation output end of the insertion / separation / multiplexing means is connected to the merging means, A joining means is connected to the signal output terminal, and the control means controls the switching means based on a result of monitoring of a signal input to the joining 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 performing control. 4. The apparatus according to claim 1, wherein said insertion / separation / multiplexing means is an optical signal insertion / separation / multiplexing means.
Or a communication network node device according to claim 3. 5. The communication network node apparatus according to claim 1, wherein said insertion / demultiplexing means is means for performing wavelength insertion / demultiplexing.