JP2000295262A - Network and system for wavelength multiplex optical communication and optical branching insertion circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength multiplex optical communication network, a wavelength multiplex optical communication system and an optical branching insertion circuit that can be applicable to branching/insertion of a plurality of optional wavelengths, reduce a required hardware quantity in a node and simplify the configuration. SOLUTION: In the network, a plurality of nodes are interconnected as a ring by using a plurality of optical fibers, a half each of the optical fibers are used for clockwise and counter clockwise optical communication, and an optical logic network is formed in the nodes by signal channels. Each node is provided with a plurality of optical branching insertion circuits 101, 102, a transmission section 111 that selects a plurality of wavelengths, assigns the wavelengths to output a signal channel, a reception section 112 that receives a signal channel 3, and transmission lines 103-106 that are placed among the optical branching insertion circuits, the transmission section and the reception circuit, and through which a plurality of wavelengths to be branched or inserted at the nodes are transmitted. Despite the configuration above, communication with other node can be made by using a plurality of wavelengths for the branched or inserted wavelengths from/to the nodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing optical communication network, a wavelength division multiplexing optical communication apparatus, and an optical add / drop circuit. More specifically, a wavelength division multiplexing transmission line is connected in a ring via a plurality of nodes. Technology that can be applied to the addition and dropping of arbitrary multiple wavelengths in a communication network, and that can reduce the required amount of hardware in a node and simplify the configuration, and an optical path. Technology that can respond to failures in nodes by performing switching at the time of failure as a unit, especially when using the two-fiber bidirectional ring network wavelengths, use 4-fiber bidirectional without interrupting normal communication The present invention relates to a technology capable of responding to an increase in communication demand by expanding to a ring network.

[0002]

2. Description of the Related Art A conventional wavelength division multiplexing optical communication network will be described with reference to an example. (Prior Art 1) FIG. 15 is a diagram illustrating wavelength division multiplexing (WDM), which is an example of a conventional wavelength multiplexing optical communication network.
FIG. 1 is a schematic configuration diagram showing a th division multiplexing (ring division) network, in which reference numerals 901a to 901e are nodes, 902 is an optical fiber constituting a wavelength multiplexing transmission line,
Reference numeral 903a denotes an optical path accommodated in the optical fiber 902 during normal optical communication, and reference numeral 903b denotes an optical path accommodated in the optical fiber 902 when a failure occurs in optical communication. Here, these signal channels for performing logical connection between the nodes using the wavelength as routing information are referred to as optical paths.

In this WDM ring network, wavelength multiplexed optical signals are input / output via an optical path 903a during normal optical communication. That is, the optical signal input to the node 901a is transmitted in the clockwise direction in FIG.
1c. Here, for example, as shown in FIG. 16, when a failure 904 occurs between the nodes 901a and 901b of the optical path 903a, these nodes 901
a and 901b cannot be transmitted. Therefore, the wavelength-division multiplexed optical signal input to the node 901a is divided into the nodes 901e, 901d, and 9 in the counterclockwise direction in the figure.
01c, the optical path 9 passing through the node 901b, and then going clockwise through the nodes 901b and 901c.
The data is output from the node 901b using the data 03b.

FIG. 17 is a block diagram showing an example of a conventional wavelength-division multiplexing optical communication network. The node configuration of a two-fiber unidirectional ring capable of dropping and inserting an arbitrary wavelength is applied to a two-fiber bidirectional ring. It is a general notation. This wavelength division multiplexing optical communication network is described, for example, in L. Berthelon et al., Proc. GLOBECOM 96, pp. 311-
315, 1996, or A. Mariconda et al., Proc. ECOC
96, ThD.1.10, 1996, etc., are generally described by applying a node configuration of a two-fiber unidirectional ring capable of dropping and inserting an arbitrary wavelength to a two-fiber bidirectional ring.

In this wavelength division multiplexing optical communication network, the function of adding / dropping wavelengths is realized by a single wavelength 2 × 2 optical switch including the case where it is realized by a wavelength filter. Is a fixed wavelength light source, and does not include a wavelength conversion function.
In general, switching in the event of a failure is considered in these ring networks, but switching is not considered here for simplicity (an example of performing switching will be described later in Related Art 2).

A node provided with this wavelength division multiplexing optical communication network includes optical fibers 911 to 914 connecting two adjacent nodes A and C (not shown) having the same structure as that of the node B (1000). An optical path is provided between nodes with a number of M waves in the form of a full mesh.
This wavelength division multiplexing optical communication network has at least N-1
Optical add / drop circuit 100 for inserting / dropping an arbitrary wavelength of a wave
1, 1002, and optical add / drop circuits 1001, 100
Reference numeral ₂ denotes wavelength separators 1003 and 1004 for demultiplexing the input wavelength-multiplexed optical signal of the M wave, and 2 × 2 optical switches 1005 _{1 to} 1005 _{M / 2} and 100 for dropping and adding one wavelength.
6 _{1 to} 1006 _{M / 2} and wavelength couplers (or wavelength multiplexers) 1007 and 1008 for multiplexing M wavelengths.

The wavelength division multiplexing optical communication network
Is an optical path terminating circuit (transmitter and receiver)
Communication unit), and the optical path termination circuit transmission unit 1009
Fixed wavelength light sources 1010 having different wavelengths₁~ 101
0_MAnd M modulations that superimpose an electric signal on the light signal of the light source
Container 1011₁~ 1011_MAnd M electrical signal inputs 101
2 ₁-1012_MAnd an optical path termination circuit receiving unit 101
3 is an M signal for converting an optical signal of each wavelength into an electric signal.
Optical signal termination circuit 1014₁-1014_MAnd M electricity
Signal output 1015₁-1015_MAnd here
The optical fiber 911 is an optical signal input from the node A.
And the optical fiber 912 is input from the other node C.
The optical signal 913 is inserted into the node C.
The optical fiber 914 accommodates the output optical signal and is connected to a node.
A stores the optical signal output to A.

The two-way communication between the node B and another node is performed as follows. Here, the direction of nodes A → B → C is defined as clockwise, and the direction of nodes C → B → A is defined as counterclockwise. For clockwise communication, M / 2 waves are used starting with the smaller index assigned to each wavelength of the M waves.
For counterclockwise communication, M
/ 2 waves are used. If the same wavelength is used for communication in both directions, the required number of wavelengths is M / 2, but
Here, in a general ring network, consider the standby system,
In that case, the remaining M / 2 waves of each optical fiber are kept as M waves in consideration of the fact that they are generally used for the standby system. In addition, the reason for using different wavelength groups for clockwise communication and counterclockwise communication is to prevent wavelength competition in the optical add / drop circuit at the time of switching when considering the standby system. Will be described in Related Art 2 below.

The clockwise optical path to the node B and another node, for example, the node C, is connected to the electric signal inputs 1012 ₁ to 1012 _{1.
One of} λ ₁ to λ _{M / 2} modulated by any one of 012 _{M / 2} is inserted into the optical add _/ drop circuit 1001, and the optical fiber is transmitted through _{one of} the optical switches 1005 _{1 to} 1005 _{M / 2.} 913. On the other hand, the optical path from the node C to the node B is a counterclockwise communication.
_{One of M / 2 + 1 to} λ _M is assigned, and is input to the corresponding node B by the optical fiber 912, and any _one of the optical switches 10061 to 1006 _{M / 2} in the optical add _/ drop circuit 1002 is The signal is output to the optical path terminating circuit receiving unit 1013 via the optical path terminating circuit 1013.

In this wavelength-division multiplexing optical communication network, in order to make it possible to add and drop an arbitrary wavelength at the node, the wavelength of the M wave can be added and dropped by the optical add / drop circuit, and two wavelength separations can be performed. All 2 split by the vessel
It is necessary to connect M wavelengths to the optical path termination circuit. Therefore, in order to generate an optical path at an arbitrary wavelength in the optical path terminating circuit transmitting section, it is necessary to provide a modulator for all of the 2M waves, and in the optical path terminating circuit receiving section, any of the 2M waves is required. In order to receive wavelengths, it is necessary to provide optical signal termination circuits for all of them.

(Prior Art 2) FIG. 18 is a block diagram showing an example of a conventional wavelength division multiplexing optical communication network having a switching function. An optical fiber 91 connecting two adjacent nodes A and C having the same structure as the node.
1 to 914, and 2 × 2 optical switches 1103, 1 that switch between each fiber in units of M-wavelength multiplexed optical signals.
104, and provides an optical path between nodes with a required number of wavelengths of M waves in a full mesh form.

This wavelength division multiplexing optical communication network includes optical add / drop circuits 1101 and 1102 for inserting / dropping at least N-1 arbitrary wavelengths.
Reference numeral 1102 denotes wavelength demultiplexers 1105 and 1106 for demultiplexing an input wavelength-multiplexed optical signal of M-wave, and 2 × 2 optical switches 1107 _{1 to} 110 for dropping and inserting one wavelength.
Comprises respectively 7 _M, 1108 ₁ ~1108 _M, wavelength coupler for multiplexing the M wavelengths (or wavelength multiplexer) 1109, 1110 and the.

The wavelength division multiplexing optical communication network comprises optical path terminating circuits 1111 and 11 for setting optical paths.
It includes a 16, optical path termination circuit transmitting unit 1111 of M fixed wavelength light source 1112 having different wavelengths ₁ ～1112 _M
And M 1: 2 optical branch circuits 11111 to 1113 for splitting the outputs of the fixed wavelength light sources 1112 _{1 to} 1112 _M into two.
And _M, and the 2M modulator 1114 ₁ ～1114 _2M for superimposing an electric signal into an optical signal of the light source, 2M present electrical signal input 1
A 115 ₁ ~1115 _2M, and the 2M optical signal termination circuits 1117 ₁ ~1117 _2M optical path termination circuit receiving section 1116 for converting an optical signal of each wavelength into an electric signal,
2M electric signal outputs 1118 _{1 to} 1182 _M are provided.

These 2M modulators 1114 _{1 to} 111 ₁
4 modulator _{1114 M / 2 + 1 ~1114 3M} / 2 of _2M is reserved modulator, 2M pieces of optical signal termination circuits 1117 ₁ to
Optical signal termination circuit 1117 _{M / 2 + 1 to} 11 of 1117 _{2M
173M / 2} is a spare optical signal termination circuit. Here, the optical fiber 911 accommodates the optical signal input from the node A, the optical fiber 912 inserts the optical signal input from the other node C, and the optical fiber 913 converts the optical signal output to the node C. The optical fiber 914 accommodates the optical signal output to the node A. Also, 2 × 2 optical switch 1
Reference numerals 103 and 1104 denote the optical add / drop circuit 1 that converts the optical signal input from the node A when no failure occurs.
The optical signal input from the node C is set to be output to the node C through the optical add / drop circuit 101.
It is set to output to A via 101.

In this wavelength division multiplexing optical communication network, in switching at the time of failure, a bidirectional path between certain nodes is assigned different wavelengths so that communication can be continued without performing wavelength conversion on the failed optical path. It is composed of two unidirectional paths. In this example, in the direction from the node A to the node B, that is, in the clockwise communication, λ ₁ to λ _{M / 2}
Using the communication in the normal, λ _{M / 2 + 1} a to [lambda] _M were used for communication failure, the direction from the node B to node A, i.e. the communication counterclockwise λ ₁ ~λ _{M / 2} Is used for communication at the time of failure, and λ
_{M / 2 + 1 to} λ _M are used for normal communication. Λ ₁ and λ _{M / 2 + 1} correspond to the clockwise and counterclockwise optical paths between the nodes, respectively. Similarly, λ _{M / 2} and λ _M correspond to the clockwise and counterclockwise optical paths between the nodes. Wavelengths are assigned so as to correspond to the respective optical paths. Normally, both fibers transmit an M / 2 wavelength multiplexed optical signal.

Here, the switching operation when a failure occurs in the ring network will be described with reference to FIGS. In this ring network, when a failure 904 occurs inside the ring network, the wavelength division multiplexing section including all the optical paths accommodated in the optical fiber in which the failed optical path 903a is multiplexed is set as a switching unit, and At the nodes 901a and 901b at both ends of the section where 904 has occurred, the optical signals input to the nodes are switched by the 2 × 2 optical switches 1103 and 1104.

For example, when a failure occurs between the node B and the node A, the optical switch 1103 outputs the signal (λ) input from the node C through the optical fiber 912.
_{M / 2 + 1 to} λ _M ) are changed so as to be input to the optical add _/ drop circuit 1101, and the optical add _/ drop circuit 1001 changes the wavelength (λ _{M / 2 +) of the} optical path to be terminated at the node B. _{1 to} λ _M ) are branched, the wavelengths (λ ₁ to _M ) of the optical paths to be inserted at the node B are inserted, and output to the node C via the optical switch 1104 again. At this time, the optical switch 1
104 does not require a route change.

In addition, among the wavelengths (λ ₁ to _M ) inserted by the optical add / drop circuit 1101, the modulator 1114 is originally used.
_{3M / 2 + 1} ~ 1114 Modulated at _2M , optical add _/ drop circuit 110
2 and should have been output to the optical fiber 914 via the optical switch 1104 (λ _{M / 2 + 1 to} λ _M ).
Is pre modulator 1114 _M / 2 + ₁ ~1114 1 wavelength λ is the original inserted in OADM circuit 1101 is input to the (OADM circuit 1101 by driving the _M to [lambda] _{M / 2}
There does not conflict with λ _{M / 2 + 1} ~λ _M to be be inserted by the switching). On the other hand, the wavelength (λ _{1 to} λ _{M / 2} ) input from the node A and originally supposed to be branched at the node B
Are input from the node C by switching, and are converted into electric signals by the spare optical signal termination circuits 1117M _{+ 1 to} 1173M _{/ 2} .

[0019]

By the way, the wavelength division multiplexing ring network of the prior art 1 has an advantage that the form of the logical connection between the nodes, that is, the optical path demand pattern is not restricted, but the typical between the nodes. Assuming a full mesh connection, which is a logical connection form, each node only needs to add and drop N-1 waves out of the total number of wavelengths of 2M. , The number of modulators in the optical path termination circuit, and the number of optical signal termination circuits are extremely redundant as compared with the required number N-1. Also,
Even when optical paths equal to or more than the number of optical paths corresponding to the full mesh are accommodated in the ring network, the wavelengths to be dropped and inserted at each node are at most N orders, and the number of wavelengths M is N ² In any case, the configuration is redundant.

In order to solve these problems, a plurality of optical signal transmission lines accommodating individual wavelengths branched by the optical add / drop circuit are manually connected to the number of optical signal termination circuits. It is necessary to manually connect the optical signal transmission lines accommodating individual wavelengths to be inserted by the optical add / drop circuit to the number of modulators, and it is difficult to insert / drop an arbitrary wavelength by automatic setting. Was.

Further, in the wavelength division multiplexing optical communication network having the switching function according to the prior art 2, when switching at the time of a failure, the nodes 901 at both ends of the section where the failure 904 has occurred.
Since the loopback switching is performed in units of the wavelength multiplexing section at a and 901b, the number of sections between nodes through which the optical path passes at the time of failure is 3 (N-1) when the number of nodes is a maximum and N is an odd number. / 2, 3N / 2-1 for even numbers,
Therefore, there is a problem that the path length of the optical path is generally increased, the influence of delay and the like is increased, and the possibility that a large number of regenerative repeaters is required is increased. Was difficult.

Further, in this wavelength division multiplexing optical communication network, in order to cope with equipment failure such as a modulator or an optical add / drop circuit, an optical path other than the 2 × 2 optical switches 1103 and 1104 used when a failure occurs between nodes. It was necessary to separately provide a duplexing mechanism corresponding to each wavelength in the termination circuit. Further, since the switching is performed in units of the wavelength division multiplex section, even when a failure occurs in some of the optical paths in the same wavelength division multiplex section, the switching operation extends to other normal optical paths. There was a problem.

As described above, in the node device using the conventional wavelength division multiplexing optical communication network, it is necessary to solve the following problems in order to enable add / drop of arbitrary plural wavelengths. (1) In order to transmit an optical signal of a single wavelength between the optical add / drop circuit and the optical path termination circuit, M × (the number of fibers between nodes) optical transmission lines were required. (2) In order to insert / drop an arbitrary N-1 wavelength from M waves, it is necessary to provide M optical signal termination circuits on the receiving side of the optical path termination circuit.

(3) In order to overcome the above problem, an optical signal transmission such as an optical fiber is performed between an optical add / drop circuit and an optical path terminating circuit and between a wavelength generating source in the optical path terminating circuit and a switch. It had to be manually connected depending on the road. (4) Since the switching unit at the time of the failure is a plurality of optical paths accommodated in the same fiber, that is, a wavelength multiplexed optical signal, the switching is performed at the nodes at both ends of the transmission line where the failure has occurred. Loopback is required, which increases the path length of the optical path, and there is a problem that the influence of delay increases in a large-scale network. In such a case, a large number of regenerative repeaters are required to satisfy the transmission characteristics.

(5) Switching of wavelength multiplexed optical signal unit 2
The × 2 optical switch has a problem that communication cannot be continued when a failure occurs in a node.
In order to solve this problem, it is necessary to provide a mechanism for switching each wavelength unit in addition to the 2 × 2 optical switch. In addition, when this mechanism is provided, a switch for switching from a wavelength for performing normal communication for all of the M waves to a wavelength for the standby system is required in the transmission unit and the reception unit of the optical path termination circuit.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in consideration of the above circumstances. It can be applied to insertion, reduces the required amount of hardware in the node, simplifies the configuration, and responds to failure in the node by switching at the time of failure in optical path units It is an object of the present invention to provide a wavelength multiplexing optical communication network, a wavelength multiplexing optical communication device, and an optical add / drop circuit.

[0027]

In order to solve the above-mentioned problems, the present invention provides the following wavelength division multiplexing optical communication network, wavelength division multiplexing optical communication apparatus, and optical add / drop circuit. That is, the wavelength division multiplexing optical communication network according to claim 1 is:
A plurality of nodes are connected in a ring shape using a plurality of optical fibers, and half of the optical fibers connected between the nodes perform clockwise and counterclockwise optical communication, and signals accommodated in the optical fibers In a wavelength division multiplexing optical communication network in which an arbitrary logical network is formed in the node by a channel, each of the nodes selects a plurality of optical add / drop circuits and a plurality of wavelengths in any combination to be inserted in the node. A transmitting unit that performs wavelength allocation and outputs a signal channel;
A receiving unit for inputting the signal channel, provided between the optical add / drop circuit and the transmitting unit, and between the optical add / drop circuit and the receiving unit, and any one to be dropped and inserted at the node. A transmission path for transmitting a plurality of wavelengths, wherein communication is performed with another node using the arbitrary plurality of wavelengths as add / drop wavelengths in the node.

According to a second aspect of the present invention, in the wavelength multiplexing optical communication network according to the first aspect, the transmitting unit includes a light source that outputs a plurality of different specific wavelengths, and a plurality of light sources arbitrarily selected from the wavelengths. An optical switch for selecting a wavelength is provided.

According to a third aspect of the present invention, in the wavelength multiplexing optical communication network according to the first aspect, the transmitting unit includes a light source for outputting light of an arbitrary wavelength at least for the number of wavelengths to be inserted. It is characterized by being provided.

According to a fourth aspect of the present invention, in the wavelength multiplexing optical communication network according to the second aspect, the light source is divided into a plurality of light source groups each outputting light of a plurality of different wavelengths, Each of these light source groups is provided with an optical switch for selecting light of an arbitrary wavelength from the light of the plurality of wavelengths.

According to a fifth aspect of the present invention, there is provided a wavelength division multiplexing optical communication network according to any one of the first to fourth aspects, wherein an electric signal to be superimposed on each of a plurality of selected wavelengths is provided. When the optical communication by the signal channel on which one of the branched electric signals is superimposed is interrupted, the other of the divided electric signals is superimposed on the optical signal having the same wavelength as that of the signal channel. A signal is inserted between the nodes into an optical add / drop circuit connected to an optical fiber that performs optical communication in the opposite direction to the signal channel.

According to a sixth aspect of the present invention, in the wavelength division multiplexing optical communication network according to the fifth aspect, when no failure occurs in optical communication, an electric signal different from the electric signal is transmitted to the signal. A new signal channel is formed by superimposing the optical signal on the optical signal having the same wavelength as the channel and inserting the optical signal into an optical add / drop circuit connected to an optical fiber for performing communication in the opposite direction to the signal channel between nodes. Optical communication is performed, and when a failure occurs in the optical communication, the optical communication using the new signal channel is interrupted, and the optical communication before the optical communication is performed is restored.

A wavelength multiplexing optical communication network according to a seventh aspect is the wavelength multiplexing optical communication network according to any one of the first to fourth aspects, wherein each of a plurality of selected wavelengths is branched into two, and each of the two wavelengths is divided into two. When the communication by the signal channel of the optical signal of one wavelength on which the electric signal is superimposed is interrupted, the electric signal is superimposed on the optical signal of the other branched wavelength, and the optical signal is interposed between the nodes. It is characterized by being inserted into an optical add / drop circuit connected to an optical fiber for performing optical communication in the opposite direction.

The wavelength division multiplexing optical communication network according to claim 8 is the wavelength division multiplexing optical communication network according to any one of claims 1 to 4, wherein the optical add / drop circuit includes:
One or two of a wavelength coupler, a wavelength multiplexer, a wavelength separator, and a wavelength multiplexer / demultiplexer, and a plurality of optical switches are integrated.

According to a ninth aspect of the present invention, there is provided the wavelength multiplexing optical communication network according to any one of the first to fourth aspects, wherein the transmission path uses a wavelength multiplexed signal light to transmit light. It is characterized in that it is a wavelength multiplexing transmission line for performing signal transmission.

According to a tenth aspect of the present invention, there is provided a wavelength division multiplexing optical communication network according to any one of the first to fourth aspects, wherein two optical fibers are provided between each of the adjacent nodes. The optical fiber transmits an optical signal multiplexed by the same number of wavelengths each performing normal optical communication and a wavelength used only when a failure occurs in the optical communication, and transmits the optical signal to the normal optical communication. The combination of the wavelength to be used and the wavelength to be used only when the failure has occurred is the same for all the optical fibers that perform optical communication in the same direction.
The optical fiber for performing either one of the optical communication in the clockwise direction and the counterclockwise direction is characterized by a different combination from the optical fiber performing the other optical communication.

The wavelength division multiplexing optical communication network according to claim 11 is characterized in that a plurality of wavelength division multiplexing optical communication networks according to claim 10 are cross-connected.

A wavelength multiplexing optical communication network according to a twelfth aspect is the wavelength multiplexing optical communication network according to the eleventh aspect, wherein one of the plurality of wavelength multiplexing optical communication networks is connected to one of the wavelength multiplexing optical communication networks. Is characterized in that the other wavelength division multiplexing optical communication network is cross-connected without interrupting the communication.

The wavelength multiplexing optical communication device according to claim 13 is
N nodes are connected in a ring between each node using two or four optical fibers, and half of the optical fibers between the nodes perform clockwise and counterclockwise communication, and Due to the optical path accommodated in the fiber, at least M waves (M = (N ² −1) / 4, 4 in the case of two fibers)
In the case of a fiber, M = (N ² −1) / 8, N = 2k, 2k
With +1 (k is an integer of 1 or more) as the required number of wavelengths, nodes can be connected in a full mesh or full mesh or higher, and each optical path is identified by a different wavelength, and the two nodes communicate with each other via two-way communication. In a wavelength division multiplexing optical communication network using optical fibers for equalizing nodes, each node includes a plurality of optical add / drop circuits serving as add / drop circuits for optical signals having different wavelengths, an optical path termination circuit, and an optical path termination circuit. A plurality of wavelength multiplexing transmission lines for transmitting signal light between the circuit and the add / drop circuit;
An optical fiber that transmits a wavelength-division multiplexed optical signal input from one adjacent node, an optical fiber that transmits a wavelength-division multiplexed optical signal output to the other adjacent node, and a plurality of wavelengths multiplexed at the node. Wavelength-multiplexed optical transmission line for transmitting the optical signal, and a wavelength-multiplexed optical transmission line for transmitting an optical signal in which a plurality of wavelengths to be inserted at the node are multiplexed. A wavelength-division multiplexed optical transmission line for transmitting an optical signal in which a plurality of branched wavelengths are multiplexed is connected to an optical path termination circuit receiving unit, and an optical signal in which a plurality of wavelengths to be inserted at the node is multiplexed. The wavelength-division multiplexed optical transmission line to be transmitted is connected to an optical path terminating circuit transmitting section, and the optical path terminating circuit transmitting section has an M wave wavelength generation source and a wavelength selection or wavelength variable circuit. At least any N-1 waves from The optical path termination circuit transmission unit includes a wavelength coupler or a wavelength multiplexer for multiplexing at least the selected N-1 waves, and the wavelength coupler or the wavelength multiplexer includes: A plurality of wavelengths to be inserted by the optical add / drop circuit of the node are input, and the optical path terminating circuit receiving unit is separated from a wavelength separator that splits the wavelength multiplexed optical signal input from the optical add / drop circuit. And an optical switch for outputting a plurality of wavelengths to desired routes, and at least N-1 optical signal termination circuits for converting optical signals of the respective wavelengths output by the optical switch into electrical signals. And

According to a fourteenth aspect of the present invention, there is provided a wavelength division multiplexing optical communication apparatus.
14. The wavelength division multiplexing optical communication device according to claim 13, wherein the M
The wavelength generation source of the wave is constituted by a shared light source having a fixed wavelength, and at least N-1 waves can be selected by an optical switch.

According to a fifteenth aspect of the present invention, there is provided a wavelength division multiplexing optical communication apparatus.
14. The wavelength division multiplexing optical communication device according to claim 13, wherein the M
It is characterized in that the wave wavelength generation source is constituted by at least N-1 variable wavelength light sources capable of transmitting M waves.

According to a sixteenth aspect of the present invention, there is provided a wavelength division multiplexing optical communication apparatus.
15. The wavelength division multiplexing optical communication device according to claim 14, wherein the M
The source of the waves alpha pieces (alpha is an integer of 2 or more) is divided into shared light source, each of the shared light source is divided can send an M _i wave _{(ΣM i = M, 2 ≦} i ≦ α) Each shared light source is connected by using a plurality of small-scale optical switches, and is capable of selecting and transmitting at least an arbitrary wavelength of at least N-1 waves from M waves by the optical switch network.

According to a seventeenth aspect of the present invention, there is provided a wavelength division multiplexing optical communication apparatus.
17. The optical path according to claim 13, wherein an electric signal superimposed on at least each of the selected N-1 wavelengths is branched into two, and one of the electric signals is superimposed on each of the two. When the communication due to is interrupted, the other two branched electric signals are superimposed on the optical signal having the same wavelength as the optical path, and the optical signal is transmitted between the nodes in a direction opposite to the optical path. The communication can be performed by inserting the optical fiber into an optical add / drop circuit connected to an optical fiber.

The wavelength multiplexing optical communication device according to claim 18 is
17. The wavelength-division multiplexing optical communication device according to claim 13, wherein at least each of the selected N-1 wavelengths is branched into two, and communication is performed by an optical path of one wavelength on which an electric signal is superimposed. In case of interruption,
Superimposes an electric signal on the other of the two branched wavelengths,
Communication can be performed by inserting the optical signal between nodes using an optical add / drop circuit connected to an optical fiber that performs communication in the opposite direction to the optical path.

The wavelength multiplexing optical communication device according to claim 19,
19. The wavelength-division multiplexing optical communication device according to claim 17, wherein in a state where no failure occurs in the ring network, the same electrical signal as the electrical signal superimposed on the failed optical path at the time of the failure is superimposed. An optical fiber that superimposes an electric signal different from the electric signal on an optical signal having the same wavelength as the optical path, and performs communication of the optical signal between nodes in a direction opposite to the optical path is connected to the optical path. A new optical path is formed by the optical add / drop circuit, and communication is performed. When a failure occurs, communication by the new optical path is interrupted and communication by the original optical path is continued.

The wavelength multiplexing optical communication device according to claim 20 is
14. The wavelength multiplexing optical communication device according to claim 13, wherein the optical signal transmission between the optical add / drop circuit and the optical path terminating circuit transmitting unit and the optical path terminating circuit receiving unit is performed using a wavelength multiplexed optical transmission line. And

According to a twenty-first aspect of the present invention, there is provided a wavelength division multiplexing optical communication apparatus.
N nodes are connected in a ring between each node using a plurality of wavelength multiplexing transmission lines, and half of the wavelength multiplexing transmission lines between the nodes perform clockwise and counterclockwise communication. By using an optical path, at least nodes can be connected to each other in a full mesh or full mesh or more.Each optical path is identified by a different wavelength, and a two-way communication between the same nodes uses a wavelength multiplexing transmission line that makes the transit nodes equal. In a wavelength division multiplexing optical communication network, two wavelength division multiplexing transmission lines are provided between adjacent nodes, and the two wavelength division multiplexing transmission lines are used only for the wavelength for performing normal communication and for the time of failure. Transmits an optical signal in which half the wavelength used is multiplexed by half, and the wavelength used for normal communication,
The combination of wavelengths used only at the time of failure is common to all nodes for the wavelength multiplexing transmission line that performs communication in the same direction, and normal communication is performed on the wavelength multiplexing transmission line that performs clockwise communication. The wavelength used for communication is used only when a failure occurs in a wavelength multiplexing transmission line that performs counterclockwise communication, and the wavelength used only when a failure occurs in a wavelength multiplexing transmission line that performs clockwise communication is a half wavelength. Each node is used for performing normal communication in a wavelength multiplexing transmission line that performs clockwise communication, and each node includes a plurality of optical add / drop circuits that serve as drop / add circuits for optical signals having different wavelengths, and a receiving unit. A plurality of wavelength multiplexing transmission lines for transmitting signal light between the optical path termination circuit and the add / drop circuit, wherein the optical add / drop circuit includes an adjacent node. And the wavelength multiplexing transmission path for transmitting a wavelength-multiplexed optical signal et input, the wavelength multiplexing transmission path for transmitting a wavelength-multiplexed optical signal output to the other adjacent node,
Of a plurality of wavelengths branched by the node, a wavelength multiplexed optical transmission line for transmitting an optical signal in which only the wavelength for normal communication is multiplexed, and only a wavelength used only at the time of failure are multiplexed. A wavelength multiplexing optical transmission line for transmitting an optical signal, and a wavelength multiplexing optical transmission line for transmitting an optical signal in which only a wavelength for performing normal communication among a plurality of wavelengths inserted at the node is multiplexed. A wavelength multiplexing optical transmission line for transmitting an optical signal in which only wavelengths used only at the time of failure are multiplexed is connected, and a plurality of wavelengths for normal communication that are branched at the node are multiplexed. Wavelength multiplexed optical transmission lines for transmitting optical signals transmitted through the optical path termination circuits and wavelength multiplexed optical transmission lines for transmitting optical signals in which a plurality of wavelengths are multiplexed and used only at the time of failure are connected to the optical path termination circuit receiver. , Inserted at said node, A wavelength-division multiplexed optical transmission line for transmitting an optical signal in which a plurality of wavelengths are multiplexed for constant communication and a wavelength-division multiplexed optical transmission line for transmitting an optical signal in which a plurality of wavelengths are multiplexed used only at the time of a failure. Each is connected to the optical path termination circuit transmission unit, and the wavelength multiplexing transmission line between the optical add / drop circuit and the optical path termination circuit is separated into those used for normal communication and those used only at the time of failure. It is characterized by having.

The wavelength division multiplexing optical communication device according to claim 22 is
A wavelength multiplexing optical communication device using a plurality of wavelength multiplexing optical communication devices according to claim 21, wherein the two fiber bidirectional ring is configured using these wavelength multiplexing optical communication devices. A four-fiber bidirectional ring network is constructed by newly adding the wavelength division multiplexing optical communication device according to claim 21 to each node of the ring network without interrupting normal communication of the network.

According to a twenty-third aspect of the present invention, there is provided an optical add / drop circuit for dropping / adding an arbitrary plurality of wavelengths of an optical signal in which a plurality of wavelengths are multiplexed, wherein the plurality of wavelengths to be dropped / added is a wavelength group normally used. It is characterized in that it is separated into other wavelength groups and output.

According to a first aspect of the present invention, in an optical communication network in which a plurality of nodes are connected in a ring using a plurality of optical fibers, an add / drop circuit capable of dropping / adding a plurality of wavelengths, The wavelength multiplexing optical communication network is provided with a wavelength multiplexing transmission line for transmitting signal light between the optical path terminating circuits for setting and between the optical add / drop circuit and the optical path terminating circuit.

Here, in order to set, for example, a full-mesh optical path in a ring network composed of N nodes so that the required number of wavelengths is M, the transmitting side of each node is connected to another node. Has a function of selecting a desired N-1 wavelength from M wavelengths for performing optical communication with a plurality of wavelengths, and a plurality of selected wavelengths are inserted into an optical add / drop circuit using a wavelength multiplexing transmission line. On the receiving side of this node, a plurality of wavelengths are branched from the optical add / drop circuit, and the branched wavelengths are transmitted to the optical path terminating circuit using a wavelength multiplexing transmission line.

According to a second aspect of the present invention, the function of selecting a desired N-1 wavelength from the M wavelengths described in the first aspect is provided by an M-wave fixed wavelength light source group and M × M ′. This is achieved by combining optical switches (M 'is, for example, N-1) or by using variable wavelength light sources capable of transmitting M wavelengths as many as the number of wavelengths to be selected. Here, the number of wavelengths to be dropped and added at each node is the required number of wavelengths M of the ring network (M = (N ² −1) / 4 for ^two fibers, M = for four fibers).
(N ² −1) / 8, N = 2k, 2k + 1 (k is an integer of 1 or more)) (N−1 for a full mesh)
Focusing on the wavelength), each node selects only the desired number of wavelengths, so that the required hardware amount in the optical path termination circuit can be reduced to a number corresponding to the number of wavelengths to be added and dropped. A configuration that can be used.

According to a third aspect of the present invention, a wavelength generation source composed of an M-wave fixed wavelength light source group and an M × M ′ optical switch described in the second aspect is combined with a plurality of fixed wavelength light source groups. This is achieved by combining small optical switches. Here, when the number of nodes in the ring network is large, that is, when the required number of wavelengths M in the network is large, it is necessary to realize a wavelength generation source with a small-scale optical switch without necessarily using a single large-scale optical switch. In addition, it is possible to increase the number of wavelength generation sources by an optical switch in units of a small-scale fixed wavelength sharing light source according to the number of optical paths dropped and inserted by the node.

A fourth aspect of the present invention resides in that when a failure occurs in the ring network, switching to a protection optical path is performed in units of individual failed optical paths to continue communication. Here, by providing the node with a mechanism for switching the optical path as a unit, it is possible to cope with a failure in the node such as a failure of the optical add / drop circuit and the optical path terminating circuit, and further, the wavelength multiplexed optical signal as a unit A configuration capable of suppressing an increase in the path length of the standby optical path, which has been a problem when switching, is provided.

A fifth aspect of the present invention is to provide a service by a new optical path using a wavelength of a standby system in a ring network, that is, an extra traffic using the above-mentioned node in a state where no failure has occurred. Is to do. Here, an optical path is provided in which the wavelength selected from the wavelength generation source is branched into two, and information to be provided is superimposed on one of the two paths.
On the other hand, a new optical path in which information of extra traffic is superimposed is provided, and if a failure occurs in the optical path with information to be provided, the service by the optical path with information of extra traffic is interrupted, The configuration is such that communication can be continued by releasing the wavelength to the failed optical path.

According to the above configuration, when an optical path corresponding to at least a full mesh is set between nodes,
Focusing on the fact that the number of wavelengths to be dropped / added at a certain node is generally smaller than the required number of wavelengths in the ring network (about one-tenth of the required number of wavelengths), the constraint that arbitrary wavelengths can be dropped / added is considered. While keeping this, the minimum necessary number of wavelengths is selected from the optical path termination circuit. As a result, the required amount of hardware in the optical path termination circuit is reduced. In addition, by transmitting a plurality of wavelengths transmitted and received from the optical path termination circuit using a wavelength multiplexing transmission line with the optical add / drop circuit, an optical path between the optical drop / add circuit and the optical path termination circuit is transmitted. It is possible to reduce the number of transmission paths, that is, the number of connections.

Further, by performing full mesh connection between nodes by an optical path using wavelength multiplexing, not only the number of required optical fibers can be reduced, but also the efficiency of using wavelengths in the optical fibers can be increased. Thereby, a ring network can be constructed economically and efficiently. Protection against failures that occur during the optical communication of the ring network can be handled by protecting the node, such as the failure of the optical path termination circuit or the optical add / drop circuit, by protecting the optical path as a unit. The optical path length at the time can be reduced. Therefore, a ring network having a larger diameter can be configured with a small number of regenerators. In addition, when no failure has occurred, by superimposing extra traffic information on the wavelength of the standby system, it is possible to increase the wavelength utilization efficiency and provide services of different quality grades in one ring network. It becomes possible.

A sixth aspect of the present invention is to extend the ring network based on a two-fiber bidirectional ring to cope with an increase in communication demand, and to provide a wavelength multiplexing transmission line between nodes after the expansion. Is divided into a wavelength multiplexing transmission line in which only wavelengths used for normal communication are multiplexed and a wavelength multiplexing transmission line in which only wavelengths used only at the time of failure are multiplexed. It can be operated. According to the configuration described above, even when operating as a two-fiber bidirectional ring, the wavelength combiner and wavelength separator in the node are used for normal communication and for wavelength used only at the time of failure. The optical path for normal communication is less susceptible to failure.

In order to realize the introduction of the optical path into the ring-structured network at low cost, the two-fiber bidirectional ring is used as the initial operation mode, and when all the wavelengths are used, two more fibers are used. Assuming that the system is to be added, a configuration excellent in expandability can be obtained.
Also, at the time of addition, of the wavelengths of the original two-fiber bidirectional ring, only the wavelength used only at the time of a failure is accommodated in the wavelength multiplexing transmission line between the added nodes, so that it is usual between the nodes. A wavelength multiplexing transmission line in which only the wavelengths performing the above communication are multiplexed and a wavelength multiplexing transmission line in which wavelengths used only at the time of failure are multiplexed are separated. As a result, even if a failure occurs in a wavelength multiplexing transmission line or a hardware in a node involving a wavelength used only at the time of failure, normal communication is not affected at all.

[0060]

Embodiments of the present invention will be described below with reference to the drawings. Note that in each embodiment of the present invention, N nodes are connected in a ring shape using two or four optical fibers between each node, and half of the optical fibers between each node are clockwise. And optical communication in a counterclockwise direction, and the optical path accommodated in the optical fiber
For example, when connecting in a full mesh state, M waves (M = (N ² −1) / 4 for ² fibers, M = (N ² −1) / 8 for 4 fibers, N = 2k, 2k + 1 (k
Is an integer greater than or equal to 1) considering the required number of wavelengths,
Each node is connected to a full mesh or full mesh or higher, each optical path is identified by a different wavelength, and bidirectional communication between the same nodes is performed by using an optical fiber that makes the passing nodes equal. Although applied to networks, the present invention is not limited to this wavelength division multiplexing optical communication network.

Here, similarly to the above-mentioned conventional technology, these signal channels for performing logical connection between nodes using wavelength as routing information are referred to as optical paths. In the drawings, the same components are denoted by the same reference numerals or reference numerals with different alphabetic characters added to the end, and the description will be omitted as appropriate.

[First Embodiment] FIG. 1 is a schematic diagram showing a wavelength division multiplexing (WDM) ring network which is a wavelength division multiplexing optical communication network according to a first embodiment of the present invention. Reference numerals 1a to 1e denote nodes, reference numeral 2 denotes an optical fiber constituting a wavelength multiplexing transmission line, and reference numeral 3a denotes an optical fiber 2.
A working optical path accommodated in the network and used during normal optical communication, 3b
A backup optical path accommodated in the optical fiber 2 and used when a failure occurs in normal optical communication.

In this WDM ring network, during ordinary optical communication, wavelength multiplexed optical signals are input / output via the working optical path 3a. That is, the optical signal input to the node 1a is output from the node 1c via the node 1b in the clockwise direction in the figure. Here, for example, as shown in FIG. 2, when a failure 4 occurs between the nodes 1a and 1b of the working optical path 3a, transmission between the nodes 1a and 1b cannot be performed. The wavelength multiplexed optical signal to be output is output from the node 1c in the counterclockwise direction in the figure using the backup optical path 3b passing through the nodes 1e and 1d.

FIG. 3 is a configuration diagram showing a node configuration of this WDM ring network. A wavelength multiplexing transmission line according to claim 20 is provided for a two-fiber ring having two fibers between nodes. This is an example in which wavelength generation and wavelength selection functions provided in an optical path termination circuit of a wavelength division multiplexing optical communication network are implemented by a combination of an M wavelength sharing light source and an optical switch.

The wavelength division multiplexing optical communication network comprises optical fibers 103 to 106 (the conventional optical fiber 21) between optical add / drop circuits 101 and 102 and two adjacent nodes.
01 to 2104), and the optical path termination circuit transmission unit 11
1 and the optical path terminating circuit receiving unit 112, the optical path terminating circuit transmitting unit 111 and the wavelength multiplexing transmission lines 107-1 provided between the optical path terminating circuit receiving unit 112 and the optical add / drop circuit.
10 is provided.

The optical add / drop circuit 101 includes an optical fiber 10
3, the optical signal is transmitted from the adjacent node, and the branched optical signal is transmitted to the wavelength separator 113 in the optical path termination circuit receiver 112 using the wavelength multiplexing transmission line 108, and the optical path termination circuit transmitter A configuration in which a plurality of wavelengths selected from 111 and transmitted using the wavelength multiplexing transmission path 107 via the wavelength coupler 114 are inserted, and an optical signal is transmitted to an adjacent node different from the node using the optical fiber 104 It is.

The optical add / drop circuit 102 transmits an optical signal from an adjacent node via an optical fiber and converts the branched optical signal into a wavelength separator 115 in an optical path termination circuit receiver 112 using a wavelength multiplexing transmission line 110. To
A plurality of wavelengths selected by the optical path terminating circuit transmitting unit 111 and transmitted using the wavelength multiplexing transmission line 109 via the wavelength coupler 116 are inserted, and the optical fiber 106 is used to insert a plurality of wavelengths into an adjacent node different from the node concerned. This is a configuration for transmitting an optical signal. Here, the optical fibers 103 and 105 receive optical signals from different adjacent nodes.

Next, the functions and configurations of the optical path terminating circuits (optical path terminating circuit transmitting section 111 and optical path terminating circuit receiving section 112) will be described in detail. The optical path terminating circuit transmitting unit 111 of the present embodiment has a shared light source 117 of M wavelengths and a scale to which the output of the shared light source 117 is input is M × M ′ (M
≧ M '≧ N-1) and the optical switch 118 is an electrical signal input 119 ₁ ~119 _2M' modulator 1 for superimposing information on the respective wavelengths of the light output from the optical switch 118
20 _{1 to} 120 _{2 M ′} , optical signal transmission paths 121 _{1 to} 121 _{2M ′} through which respective wavelengths on which information is superimposed are transmitted, and wavelength couplers 114 and 116 for wavelength-multiplexing these.

The optical path terminating circuit receiving section 112 includes wavelength demultiplexers 113 and 115 for demultiplexing the wavelength multiplexed optical signals transmitted from the optical add / drop circuits 101 and 102 into respective wavelengths.
M × M ′ optical switches 122 and 123 (M ≧ M ′ ≧ N−1) for outputting the separated wavelengths to a desired route;
Optical signal terminating circuits 124 ₁ to 124, which convert the respective wavelengths output from the M ′ optical switches 122 and 123 into electric signals.
_'And a wavelength demultiplexer 113 and 115 optical signal terminating circuit 124 ₁ ~124 _2M' 124 _2M optical signal transmission line _{125 1 ~125 2M, 126 1 ~126} 2M ' for transmitting optical signals between the optical signal Electric signal outputs 127 _{1 to} 127 _{2M ′} for outputting signals converted into electric signals by the termination circuits 124 _{1 to} 124 _{2M ′} .

Next, the features of the WDM ring network according to the present embodiment will be described by taking N = 15 as an example of the number N of nodes. The required number of wavelengths M (= (N ² −1) / 4) for logically connecting the nodes of the two-fiber bidirectional ring with N = 15 in a full mesh state is M = 56. At this time, each node needs to add and drop 14 waves in order to communicate with the other 14 nodes. That is, the total number of wavelengths 11 inputted from the optical fibers 103 and 105 in FIG.
14 wavelengths from 2 (= 56 × 2) are added to the optical add / drop circuit 1
The signal is branched by using 01 and 102 and transmitted to the optical path termination circuit. The optical path terminating circuit transmitting section 111 selects the same 14 wavelengths as the branched wavelength and selects the 14
The optical signal is transmitted to two adjacent nodes using optical fibers 104 and 105. here,
The N-1 wavelengths dropped and inserted at each node of the two-fiber bidirectional ring according to the present embodiment are composed of only different wavelengths.

In the present embodiment, 1
Four waves are split into seven waves, and each optical signal contains seven waves.
The signal is input by the optical fibers 103 and 105. As well
The optical signal including each of the seven waves is transmitted to the optical fiber 104,
It is output to 106. Here, the optical path termination circuit transmission unit
The M × M ′ optical switch 118 in 111 has M (= 56)
Select only desired N-1 (= 14) wavelengths from wavelengths
And the modulator 120 ₁ ~ 120_{2M '}Send to. Also,
M × M ′ optical switch 12 of optical path termination circuit receiver 112
2, 123, each of the branched wavelengths
Signal termination circuit 124₁~ 124_{2M '}Output to These M ×
By using the M 'optical switch, the conventional
M wavelengths (order N^Two)
The required number of modulators and optical signal termination circuits required by N-
Reduce to one, and similarly separate and combine wavelengths on the scale of M wavelengths
Of wavelength separators and wavelength combiners that needed to be used
Can be reduced to the N-1 wavelength scale.

In this embodiment, the case where the required number of wavelengths M for full mesh connection is 56 when N = 15 has been described. However, M is a value larger than the required number of wavelengths (for example, 64).
In an optical communication network that can provide a wave, it is possible to set an optical path of 15 mesh or more between full nodes. In this case, it is possible to add and drop N-1 or more wavelengths at each node. In this case, the number of modulators and optical signal terminating circuit in the optical path termination circuit can be suppressed to the order of N compared with the order of N ² in the conventional example, as well as the wavelength demultiplexer and the wavelength coupler The scale can be reduced to the order of N.

As described above, in the wavelength division multiplexing optical communication network of the present embodiment, the scale of the wavelength coupler, the number of modulators, the scale of the wavelength separator, the number of optical signal termination circuits, Advantages such as reduction in the number of connections between the add / drop circuit and the optical path termination circuit transmission unit and the optical path termination circuit reception unit can be obtained. As a result, the physical scale of the optical path termination circuit can be reduced, and the cost of the optical path termination circuit can be reduced.

As described above, the scale of the optical switch required in the optical path termination circuit transmitting unit and the receiving unit to connect the N nodes in a full mesh form is M × (N−1) (M '= N-1). Here, by setting M ′ = M, of the above advantages, the number of modulators and optical signal termination circuits can be equivalent to that of the conventional example. The output of the optical switch does not necessarily have to be M, and the optical switch may be set so that at least N-1 waves can be selected. In addition, if the configuration is such that an M wave is actually output, any logical connection form can be supported as in the conventional example. Also in this case, it is possible to minimize the number of output wavelengths according to each logical connection form.

The present embodiment can also be applied to a four-fiber bidirectional ring in which nodes are connected by four fibers. In this case, each of the optical add / drop circuit, the wavelength multiplexed optical transmission line, the wavelength coupler, and the wavelength separator in FIG. 3 is divided into two, and the divided wavelength coupler and the wavelength separator are at least divided into two. A wavelength multiplexing transmission line is provided for splitting and multiplexing the wavelengths of (N-1) / 2 waves and transmitting an optical signal in which these wavelengths are multiplexed between an optical add / drop circuit and an optical path termination circuit. If the split optical add / drop circuit is configured to be capable of splitting at least (N-1) / 2 waves from at least M wavelengths (= (N ² -1) / 8), Good.

[Second Embodiment] FIG. 4 is a block diagram showing an optical path terminating circuit transmitting section of a wavelength division multiplexing optical communication network according to a second embodiment of the present invention. In a ring network connected by a fiber, an optical path terminating circuit transmitting unit using a variable wavelength light source according to claim 15 is a configuration example. Optical path termination circuit transmission unit 111a of the present embodiment
Is a variable wavelength light source 203 ₁ capable of transmitting M wavelengths.
And ～203 _14, the optical signal transmission line 121 ₁ to 121 _14, each of the wavelengths superimposed information is transmitted, and a wavelength coupler 201 and 202 them to wavelength multiplexing (or wavelength multiplexer) I have. These wavelength couplers 201, 20
2 is connected to wavelength multiplexed optical transmission lines 107 and 109 for transmitting respective optical signals to the optical add / drop circuit.

Next, the optical path terminating circuit transmitting section of this embodiment
The feature of 111a is as follows: N = N
15 will be described as an example. In the present embodiment, the first implementation
Full mesh between nodes by optical path described in the form of
The selection of 14 wavelengths at each node at the time of connection
Variable wavelength light source 203 ₁ ~ 203 ₁₄ Line independently
Will be done. That is, each tunable wavelength light source 20
3 ₁ ~ 203 ₁₄ Transmit different wavelengths from each other
Are multiplexed by the two wavelength couplers 201 and 202 in units of seven waves.
The Rukoto. This makes the modulator and optical signal termination circuit necessary.
Reduction of required number and scale of wavelength demultiplexer and wavelength coupler
With respect to the reduction of the effect, the same effect as in the first embodiment can be obtained.
Can be

The present embodiment can also be applied to a four-fiber bidirectional ring in which nodes are connected by four fibers. In this case, the wavelength coupler 20 shown in FIG.
1, 202, and the wavelength-division multiplexed optical transmission lines 107 and 109 are each divided into two, and each component is capable of communicating at least the number of wavelengths M ((N ² −1) / 8). Configure a communication device.

[Third Embodiment] FIG. 5 is a block diagram showing an optical path termination circuit transmitting section of a wavelength division multiplexing optical communication network according to a third embodiment of the present invention, and FIG. FIG. 9 is a configuration diagram illustrating a modified example of the circuit transmission unit, where the number of nodes
Alternatively, a ring network connected by four fibers is a configuration example of a wavelength generation source and a wavelength selection circuit of an optical path termination circuit transmission unit using a variable wavelength light source according to claim 16.

The wavelength generation source and the wavelength selection circuit of the present embodiment shown in FIG. 5 are examples in which the M-wave shared light source 117 and the M × M ′ optical switch 118 described in the first embodiment are divided into a plurality. Yes, α that can transmit different p-waves
Fixed wavelength sharing light sources 301 _{1 to} 301 α, α p × p optical switches 302 _{1 to} 302 α both having p input / output optical signals, and one wavelength selected for α inputs P α × 1 optical switches 303 _{1 to} 303 _p
Optical signal transmission line 30 connecting between p × p optical switches 302 _{1 to} 302α and α × 1 optical switches 303 _{1 to} 303 _p
4 and an optical signal transmission line 305 for outputting the wavelength selected by the α × 1 optical switches 303 _{1 to} 303 _p . Here, each of the divided shared light sources is M _i wave (i
If it is to generate an integer of 2 or more), the number of wavelengths that can be generated as a whole is represented by? M _i.

A wavelength generation source and a wavelength selection circuit which is a modification of the present embodiment shown in FIG. 6 is an example in which a shared light source 117 for M-waves and an M × M ′ optical switch 118 are divided into a plurality of pieces, similarly to FIG. And α fixed wavelength sharing light sources 401 _{1 to} 401 α capable of transmitting different p waves, and α p × p optical switches 402 each having p input and output optical signals.
1 and ₁ ～402Arufa, the respective optical signals: and M optical branching 403 ₁ to 403 _M branch to m, alpha present in the input to the 1
M × p α × 1 optical switches 404 ₁ to select the wavelength
404 _{m · p} , an optical signal transmission line 405 connecting between the p × p optical switches 402 _{1 to} 402α and the α × 1 optical switches 404 _{1 to} 404 _{m · p} , and the α × 1 optical switches 404 ₁ to
Optical signal transmission line 4 for outputting the wavelength selected at 404 _{m · p}
06. FIG. 6 shows a case where m = 2 for simplicity.

In this embodiment, for the sake of simplicity, an example of splitting a fixed wavelength sharing light source for M waves when the relationship M = p × α holds between the required number of wavelengths M in the ring and p and α. However, the method of dividing the shared light source includes a case where the above equation is not satisfied.

Here, the feature of the present embodiment will be described with reference to a case where a mesh optical path is set in a two-fiber bidirectional ring, taking N = 15 as an example of the number of nodes N. In the present embodiment, 14 waves are added and dropped at each node. The required number of wavelengths in the ring network in this case is 56 wavelengths. Here, considering the case where the ring network is configured by a 64-wavelength multiplexed optical transmission line (M = 64), it is necessary for each node to select at least 14 waves in order to communicate with another node. For example, if the wavelength generation source and the wavelength selection switch are divided so that p = 4 and α = 16 in FIG. 5, any 16 wavelengths can be selected at each node. Therefore, it is possible to configure at least a full mesh optical path network.

Here, the values of p and α are not unique.
For example, it is possible to set p = 8 and α = 8. In this case, each node can select an arbitrary wavelength from eight waves, but, for example, cannot be set between nodes. Therefore, as shown in FIG.
3 ₁ to 403 _M was inserted between the p × p optical switch 402 ₁ ～402Arufa and alpha × 1 optical switch 404 ₁ to 404 _{m · p,} by arbitrarily selectable 16 wavelengths at maximum, full Mesh connection becomes possible. As described above, if the coefficient m is set so that a desired number of wavelengths can be obtained, for example, an optical path having an arbitrary logical connection form including a full mesh can be set for an arbitrary combination of p and α. it can.

In this embodiment, at least a full-mesh optical path is set between nodes.
The wavelength selective switch network is configured so that the wavelength of the wave can be selected. However, as described in claim 5, the shared light source is divided by connecting a plurality of shared light sources in parallel using a plurality of optical switches. Light sources can be sequentially added. That is, when a new optical path is set after a full-mesh optical path is set between nodes, only a shared light source including a required wavelength may be sequentially added. At this time, if the wavelengths are allocated to the optical paths so that the newly required wavelengths become as common as possible at each node, the number of fixed wavelength sharing light sources of p-waves added to each node can be efficiently increased. Can be reduced. This makes it possible to economically increase the communication capacity of the optical path of the ring network.

If a full-mesh optical path is not necessarily required between nodes, it is sufficient to configure each node to select only a desired number of wavelengths (<14). In this case, the number of the p-wave fixed wavelength sharing light sources may be smaller than α.
For example, only a common light source including a necessary wavelength may be provided at the beginning, and a common light source including only an unnecessary wavelength may be added as needed. At this time, if the wavelength allocation is performed for each optical path so that the wavelength required at each node is as common as possible, the number of fixed wavelength sharing light sources of p-waves to be provided at each node can be efficiently increased. Thus, the introduction of an economical optical path can be achieved.

The configuration shown in the present embodiment, in which the wavelength generation source using the shared light source and the wavelength selector are sequentially added, is different from the case where the function is realized using the variable wavelength light source according to the third aspect. Is also applicable. In that case, the variable wavelength light sources corresponding to the number of optical paths to be dropped / added at each node to the optical path terminating circuit transmitting section as necessary, and the optical signal terminating circuit to the optical path terminating circuit receiving section, respectively. What is necessary is just to provide.

[Fourth Embodiment] FIG. 7 is a block diagram showing an optical path termination circuit transmitting section and an optical path termination circuit receiving section of a wavelength division multiplexing optical communication network according to a fourth embodiment of the present invention. FIG. 8 is a block diagram showing a modified example of the optical path terminating circuit transmitting section and the optical path terminating circuit receiving section, and relates to a ring network in which nodes are connected by two or four optical fibers, respectively. It is a structural example of the optical path terminating circuit transmitting unit described.

The optical path terminating circuit transmitting section 111b of this embodiment shown in FIG. 7 uses the wavelength of at least N-1 waves selected by each node in the two-fiber ring node configuration described in the first embodiment. This is an example in which the optical path is duplicated. This optical path terminating circuit transmitting unit 111b includes:
M-wave shared light source 117 and M × M ′ as wavelength generation sources
An optical switch 118 (M ≧ M ′ ≧ N−1), a 1: 2 optical branch 500 _{1 to} 500 _{M ′} that branches the selected wavelength into two,
Modulators 501 ₁ to 501 that superimpose an electric signal on each wavelength
501 _{2M '} and 1: 2 branches 503 _{1 to} 503 which divide the electric signal to be inputted from the electric signal inputs 502 _{1 to} 502 _M' into two.
And 03 _{M ',} ON / OFF switch 504 is a gate for each One of the branched electric signals _{1-504
M ′} and wavelength couplers 505 and 506 for multiplexing wavelengths to be inserted into the optical add / drop circuits 101 and 102 (see FIG. 3). The wavelength couplers 505 and 506 are connected to wavelength multiplexing optical transmission lines 107 and 109 for transmitting an optical signal having a wavelength to be inserted.

The optical path terminating circuit receiving section 112b is connected to the wavelength multiplexing transmission lines 108 and 110 for transmitting the optical signals including the wavelengths branched from the optical add / drop circuits 101 and 102, and to split the wavelengths. Separators 507, 508
M × M ′ optical switches 509 and 510 for sending the demultiplexed wavelength to a desired route, optical signal termination circuits 511 _{1 to} 511 _{2M ′} for converting a received optical signal into an electric signal, 2 × 1 switches 512 _{1 to} 512 _{M ′} for selecting one of the two electric signals. Here, the electric signal inputs 502 _{1 to} 502 _{M ′} are respectively the electric signal outputs 51
3 _{1 to} 513 _{M ′} , and the correspondence is equivalent to two optical paths set bidirectionally between the node and another node.

An optical path terminating circuit transmitting unit as a modification of the present embodiment shown in FIG. 8 is selected by each node in the node configuration in the case where the ring network of the first embodiment is configured by four fiber rings. This is an example in which N-1 waves are duplicated. The optical path terminating circuit transmitter 111c includes an M-wave shared light source 117 and an M × M ′ optical switch 118 as wavelength generating sources, and a 1: 2 optical branch 500 _{1 to} 500 _{M ′ that} branches the selected wavelength into two. Modulators 501 _{1 to} 501 _{2M ′} for superposing an electric signal on each wavelength, and an electric signal input 50
_'Two branches an input electrical signal to be from 1: 2 branches _{503 1 ~503 M' 2 1 ~502} M and, ON / OFF switch 504 ₁ is the gate for each One of the branched electric signals ～504 _{M ′} and wavelength couplers 601 to 604 that combine wavelengths to be inserted into the optical add / drop circuits (see the optical add / drop circuits 101 and 102 in FIG. 3). The wavelength couplers 601 to 604 have wavelength multiplexed optical transmission lines 505 to 505 for transmitting an optical signal having a wavelength to be inserted.
508 (corresponding to the wavelength multiplexing optical transmission lines 107 and 109 in FIG. 3) are connected to each other.

The optical path terminating circuit receiving section 111c includes a wavelength multiplexing transmission line (FIG. 3) for transmitting an optical signal containing a wavelength branched from an optical add / drop circuit (corresponding to the optical add / drop circuits 101 and 102 in FIG. 3). Wavelength multiplexing optical transmission lines 108 and 110
Wavelength demultiplexer 605 for demultiplexing the wavelength of the optical signal from
To 608 and M for sending the demultiplexed wavelength to a desired route.
× M ′ optical switches 609 to 612 and optical signal termination circuits 511 _{1 to} 511 _{2M ′} for converting received optical signals into electric signals
And 2 × for selecting one of the two received electric signals
1 switch 512 _{1 to} 512 _{M ′} . Here, two optical paths electrical signal input 502 ₁ to 502 M _'is an electrical signal output 513 ₁ ~513 _M' respectively corresponding to, the correspondence set in both directions between the node and another node Is equivalent to

Here, the feature of the optical path terminating circuit transmitting section and the optical path terminating circuit receiving section of the present embodiment is that a failure has occurred in the ring network, and communication by an optical path of a certain wavelength has been interrupted. In such a case, the O
The N / OFF switch is turned on, and the 1: 2 branch 503 is set.
_{1 to} 503 _{M '} is superimposed on an optical signal having the same wavelength as the wavelength from which the communication was originally performed, and an optical path opposite to the original optical path is generated. The point is that the switching is performed in units of. At this time, the optical path set between certain nodes that has suffered a failure switches the nodes at the start point and the end point of the optical path as switching points. In other words, this is different from the conventional wavelength multiplexing optical communication network in which nodes at both ends of a section where a failure has always occurred are switching points.

Here, the reverse optical path for realizing communication at the time of a failure is operated as a standby system of the original optical path. That is, in each of FIGS. 7 and 8, when an optical path in which the information of the electric signal input 502 ₁ is superimposed by the modulator 501 ₁ is set to perform communication from the node to a certain node, The optical path for performing communication from the communication node to the node is an optical path termination circuit receiving unit 112.
b (112c), a path is set by the M × M ′ optical switch 509 (609) so as to be input to the optical signal termination circuit 511 ₁ and the optical signal termination circuit 511 ₁ in is converted into an electric signal, 2 × 1
Is output to the electrical signal output 513 ₁ via the switch 512 _1.

On the other hand, when a failure occurs in the optical path on which the information of the electric signal input 502 ₁ is superimposed, the two-branched electric signal is transmitted to the ON / OFF switch 504.
_The communication is continued by setting _{M '/ 2 + 1} to the ON state and modulating the signal by the modulator 501 _{M' + 1} . On the other hand, in the optical path terminating circuit receiving unit 112b (112c), a new optical path generated as a standby system for continuing communication to the node is received by the optical signal terminating circuit 511 _{M ′ +1} and an electric signal is received. converted to, 2 × 1 selected by the switch 512 _1, is output to the electrical signal output 513 _1.

Another aspect of the present embodiment is that the provision of the above-described switching mechanism in units of wavelength allows the failure in the node (such as an optical add / drop circuit failure or a modulator failure) to be prevented by the failure. The point is that communication of the failed optical path can be continued. That is, the electric signal input 502 ₁
If the optical path superimposed with the information on the optical path has a failure in the node, for example, if the modulator 501 ₁ or the wavelength coupler 505 fails, the ON / OFF switch of the two branched electric signals is performed. The communication is continued by setting 504 _{M ′ / 2 + 1} to the ON state and modulating the signal by the modulator 501 _{M ′ + 1} . On the other hand, the optical path terminating circuit receiving unit receives a new optical path generated as a standby system in order to continue communication to the node in the optical signal terminating circuit 511 _{M ′ + 1, and then} converts the signal into an electric signal. conversion, 2 × 1 selected by the switch 512 _1, is output to the electrical signal output 513 _1.

In order to enable the above switching operation, FIG.
In the two-fiber ring of the above, half of the wavelength used for normal communication and half of the wavelength used for failure are respectively multiplexed on two optical fibers between the nodes, and the wavelength normally used for the clockwise optical fiber is The counterclockwise optical fiber is used only at the time of failure, and the wavelength used at the time of failure in the clockwise optical fiber is used only at the normal time in the counterclockwise optical fiber. Also, regarding the optical path set between certain nodes, the wavelength assigned to the optical path performing clockwise optical communication between nodes during normal operation and the wavelength assigned to the optical path performing counterclockwise optical communication differ. The other normal wavelength is assigned to each standby optical path.

In the four-fiber ring shown in FIG. 8, two optical fibers for performing clockwise and counterclockwise optical communication exist between nodes, each of which has an optical fiber for performing normal optical communication and a standby optical fiber. Includes optical fiber used as a system.

[Fifth Embodiment] FIG. 9 is a block diagram showing an optical path terminating circuit transmitting section and an optical path terminating circuit receiving section of a wavelength division multiplexing optical communication network according to a fifth embodiment of the present invention. This is an example of the configuration of the optical path termination circuit transmission unit according to claim 18 for a ring network in which nodes are connected by two fibers. This optical path termination circuit transmitting section 111d
Is at least N−N selected at each node in the two-fiber ring node configuration described in the first embodiment.
This is an example in which an optical path based on one wavelength is duplicated.

The optical path terminating circuit transmitting section 111d includes an M-wave shared light source 117 as a wavelength generating source, an M × M ′ optical switch 118, and a modulator 701 for superimposing an electric signal on each of the selected wavelengths. _{1 to} 701 _{M ′} and 1: 2 optical branch 702 ₁ to divide the optical signal on which the electric signal is superimposed into two.
702 _{M ′} and ON / OFF switches 703 _{1 to} 703 which are gates for one of the branched optical signals.
_{M ′} and wavelength couplers 704 and 705 for multiplexing wavelengths to be inserted into the optical add / drop circuits 101 and 102. These wavelength couplers 704 and 705 are used to transmit wavelength-multiplexed optical transmission lines 107 and 10 for transmitting an optical signal having a wavelength to be inserted.
9 respectively.

The optical path terminating circuit receiving section 112d has a wavelength for demultiplexing the wavelengths of the optical signals from the wavelength multiplexing transmission lines 108 and 110 for transmitting the optical signals including the wavelengths branched from the optical add / drop circuits 101 and 102. Separators 507 and 508, M × M ′ optical switches 509 and 510 for sending the demultiplexed wavelength to a desired route, and different M × M ′ optical switches 50
2 × 1 optical switches 706 _{1 to} 706 _{M ′} for selecting the input of optical signals from each of the optical signals 9 and 510, and optical signal termination circuits 707 _{1 to} 707 for converting received optical signals into electric signals.
07 _{M '} . Here, the electric signal input 502 ₁
５０２502 _{M ′} are electric signal outputs 513 ₁ ５513 _{M ′, respectively.}
Corresponding to two optical paths set bidirectionally between the node and another node.

Here, the feature of the optical path terminating circuit transmitting section and the optical path terminating circuit receiving section of the present embodiment is that, similarly to the fourth embodiment, a failure occurs in a ring network or a node. When communication via an optical path of a certain wavelength is interrupted, ON / OFF of the optical path termination circuit receiving unit
An optical add / drop circuit to which a switch is turned ON, and an optical fiber for performing communication in a reverse direction to the original optical path is connected to a new optical path generated by the optical signal branched by the 1: 2 optical branch. Communication can be performed by inserting the In addition, the protection optical path is generated at the level of the optical signal, and as a result, switching is performed by the optical switch.

At this time, as in the fourth embodiment, the optical path set between certain failed nodes is switched using the nodes at the start point and the end point of the optical path as switching points. That is, in FIG.
_If the optical path on which information _{1 is} superimposed by the modulator 7011 is set to perform communication from the node to a certain node, the optical path performing communication from the node to the node is an optical path termination. The wavelength separator 50 of the circuit receiver 112d
7 and 2 × 1 by the M × M ′ optical switch 509.
The route is set to be input to the optical switch 706 ₁ ,
The light signal is converted into an electric signal by the optical signal termination circuit 707 ₁ , and then output to the electric signal output 513 ₁ .

On the other hand, when a failure occurs in the optical path on which the information of the electric signal input 502 ₁ is superimposed in the ring network or the node concerned, the 1: 2 optical branching 702 ₁ causes 2
ON / OFF switch 703 _{M '/ 2 + 1 for the} split optical signal
Is turned on to multiplex with the wavelength coupler 705 to continue communication. On the other hand, the optical path termination circuit receiver 1
In 12d, new light path generated as a standby system to continue communication to the node is demultiplexed by the wavelength demultiplexer 508, the M × M 'optical switch 510 to the 2 × 1 optical switch 706 ₁ The route is set to be input, received by the optical signal termination circuit 707 ₁ and converted into an electric signal,
Thereafter, output to an electrical signal output 513 _1.

This embodiment is also applicable to a four-fiber ring, as in the third embodiment. In this case, each of the wavelength coupler and the wavelength separator shown in FIG. 9 is divided into two, and the divided wavelength coupler and the wavelength separator separate and divide at least (N-1) / 2 wavelengths. A wavelength-division multiplexing optical communication network having a wavelength-division multiplexing transmission line for multiplexing and transmitting an optical signal in which these wavelengths are multiplexed between the optical add / drop circuit and the optical path terminator may be configured.

As described above, by using the wavelength division multiplexing optical communication network of the present embodiment, it is possible to realize protection in which an optical path is set as a switching unit, and it is possible to cope with a device failure in a node. It is possible to reduce the optical path length at the time.

[Sixth Embodiment] FIG. 10 is a block diagram showing an optical path termination circuit transmitting section and an optical path termination circuit receiving section of a wavelength division multiplexing optical communication network according to a sixth embodiment of the present invention. FIG. 11 is a block diagram showing a modified example of the optical path termination circuit transmission section and the optical path termination circuit reception section, and relates to a ring network in which nodes are connected by two or four optical fibers, respectively. It is a structural example of the optical path terminating circuit transmitting unit described.

The optical path terminating circuit transmitting section 111e of the present embodiment shown in FIG. 10 uses the wavelength of at least N-1 waves selected in each node in the two-fiber ring node configuration described in the first embodiment. The optical path is duplicated, and an electric signal of information different from the information to be provided (hereinafter referred to as extra traffic) is superimposed on one of the optical paths, and the service by the extra traffic is interrupted. This is an example provided when no occurrence has occurred.

The optical path terminating circuit transmitting section 111e includes an M-wave shared light source 117 as a wavelength generating source, an M × M ′ optical switch 118, and a selected wavelength of 1: 2.
Optical splitters 500 _{1 to} 500 _{M ′} , electric signal inputs 502 _{1 to} 502 _{M ′} accompanied by information to be provided originally, and modulators 501 _{1 to} 501 _{M ′} for superimposing electric signals on respective wavelengths, are originally provided. _'and the electrical signal input 801 ₁ ~801 _M with extra traffic _information' 2 branches 503 ₁ ~ 503 _M and the electrical signal with the information to be provided originally which is branched: 1 to 2 branches the electrical signal with information should 2 × 1 switch 80 for selecting between an electric signal with extra traffic information
21 _{1 to} 802 _{M ′,} and wavelength couplers 505 and 506 for multiplexing wavelengths to be inserted into the optical add / drop circuit. These wavelength couplers 505 and 506 have wavelength-multiplexed optical transmission lines 107 and 10 for transmitting an optical signal having a wavelength to be inserted.
9 respectively.

This optical path terminating circuit receiving section 112 e
Transmits optical signals containing wavelengths dropped from add / drop circuits
Wavelengths of optical signals from the wavelength multiplexing transmission lines 108 and 110
Wavelength demultiplexers 507 and 508 for demultiplexing the
M × M ′ optical switch 509 for sending the length to a desired route,
510 and an optical signal for converting a received optical signal into an electric signal
Termination circuit 511₁~ 511_{2M '}The received information is
If the information is to be provided, an electric signal output 513 is provided.₁To 5
13_{M '}Output, and in the case of extra traffic, electricity
Signal output 805₁~ 805_{M '}1 × 2 switch to output to
803₁~ 803 _{M '}And of the two received electrical signals
2 × 1 switch 804 for selecting one₁~ 804_{M '}And
Have. Here, the electric signal input 502₁~ 502_{M '}
Are electrical signal outputs 513, respectively.₁~ 513_{M '}Corresponding to
Electrical signal input 801₁~ 801_{M '}Is an electric signal output
Power 805₁~ 805_{M '}And the corresponding relationship is
Two optical paths set bi-directionally between a node and another node
Is equivalent to

An optical path terminating circuit transmitting section 111f, which is a modification of the present embodiment shown in FIG. 11, is selected by each node in the node configuration in the case where the ring network of the first embodiment is composed of four fiber rings. At least N-1 wavelengths are duplicated, and an electric signal of information different from the information to be provided is superimposed on each one optical path,
This is an example in which the service based on the extra traffic is provided when no failure has occurred.

This optical path terminating circuit transmitting section 111f includes an M-wave shared light source 117 as a wavelength generation source, an M × M ′ optical switch 118, and a 2-to-1 branch of the selected wavelength.
Optical splitters 500 _{1 to} 500 _{M ′} , electrical signal inputs 502 _{1 to} 502 _{M ′} with information to be provided originally, and modulators 501 _{1 to} 501 _{2 M ′} for superimposing electrical signals on the respective wavelengths are originally provided. _'and the electrical signal input 801 ₁ ~801 M with extra traffic _information' 2 branches 503 ₁ ~503 M and the electrical signal with the information to be provided originally which is branched: 1 to bifurcated electrical signal with information should 2 × 1 switch 80 for selecting between an electric signal with extra traffic information
2 _{1 to} 802 _{M ′} , wavelength couplers 601 and 604 for multiplexing the wavelength of the optical path with the information to be provided, and the wavelength of the optical path with either the information to be provided or the extra traffic information. Wavelength combiners 602, 6 to be combined
03. These wavelength couplers 601 to 604
Are connected to wavelength multiplexing optical transmission lines 505 to 508 (corresponding to the wavelength multiplexing optical transmission lines 107 and 109 in FIG. 3) for transmitting optical signals in which these wavelengths are multiplexed.

The optical path termination circuit receiving section 112f
Wavelength separator that demultiplexes only the wavelength of the optical path of the information to be provided
605, 608 and the information or
The wavelength of the optical path with any of the traffic information
Wavelength separators 606 and 607 and the demultiplexed wavelength
M × M ′ optical switches 609 to 61 for sending out to a desired route
2. Optical signal termination for converting received optical signals to electrical signals
Circuit 511₁~ 511_{2M '}And the information received
If the information is power information, the electric signal output 513₁~ 513
_{M '}To an electric signal in case of extra traffic
Output 805₁~ 805_{M '}1 × 2 switch 80 to output to
3₁~ 803_{M '}And one of the two received electric signals
2x1 switch 804 to select₁~ 804_{M '}With
ing. Here, the electric signal input 502₁~ 502_{M '}Haso
513 each electrical signal output₁~ 513_{M '}Corresponding to electricity
Signal input 801₁~ 801_{M '}Is the electrical signal output 8
05 ₁~ 805_{M '}And the corresponding relationship is
And two other optical paths set bidirectionally between other nodes.
Hit.

Here, the feature of the optical path terminating circuit transmitting section and the optical path terminating circuit receiving section of the present embodiment is that, when no failure occurs in the ring network, the information to be provided is provided. Provide at least as many optical paths as the full mesh, and at the same time provide multiple extra-traffic optical paths, and if a failure occurs in the ring network, use the In order to continue communication, the service is to interrupt the service by the optical path of the extra traffic. That is, the fourth or fifth embodiment is characterized in that the standby system is released to provide extra traffic at normal times.

That is, in the two-fiber ring shown in FIG.
Communication of information that should be provided using an optical path
The electrical signal in the optical path termination circuit transmitting unit 111e.
Input 502₁Information of the modulator 501₁Superimposed by the wavelength
The signal is multiplexed with another wavelength using the coupler 505, and
Communication to a certain node. Also, some node
The optical path that communicates with the relevant node is an optical path termination circuit.
Demultiplexed by the wavelength separator 507 of the receiving unit 112e,
The optical signal termination circuit 511 is operated by the M 'optical switch 509. ₁To
The route is set to be input. And the optical signal termination
Circuit 511₁Is converted to an electric signal by 2 × 1 switch
804₁Through the electrical signal output 513₁Is output to.

At the same time, in the optical path termination circuit transmitting section 111e, the extra traffic information of the electric signal input 801 _{M ′ / 2 + 1} is transmitted to the modulator 501 via the 2 × 1 switch 802 _{M ′ / 2} .
_It is input to _{M ′ + 1} , superimposes extra traffic information on the optical signal, is multiplexed with another wavelength by the wavelength coupler 506, and realizes communication by a new optical path between the node and the node. In the optical path termination circuit receiving unit 112e,
An optical path for performing extra traffic communication from a certain node to the node is demultiplexed by the wavelength separator 508, and M ×
The path is set by the M ′ switch 510 so that the signal is output to the optical signal termination circuit 511 _{M ′ + 1} , and the optical signal termination circuit 511 is set.
It is converted to an electric signal at _{M '+ 1} . Then, a path is set by the 1 × 2 switch 803 _{M ′ / 2 + 1} so as to be output to the electric signal output 805 _{M ′ / 2 + 1} .

On the other hand, when a failure occurs in the optical path on which the information of the electric signal input 502 ₁ is superimposed, at least the service by the extra traffic of the electric signal input 801 _{M ′ / 2 + 1} and the electric signal output 805 _The service by the extra traffic output to _{M ′ / 2 + 1} is interrupted, and the optical path terminating circuit transmitting section 111e transmits the 2 × 1 switch 802
_{According to M ′ / 2 + 1} , the signal of the branched electric signal input 502 ₁ is selected, and the optical path termination circuit receiving unit 112 e selects 1
An electric signal input to the × 2 switch 803 _{M ′ / 2 + 1} and accompanied with information to be provided is branched by the switch 803 _{M ′ / 2 + 1} so as to be output to the electric signal output 513 ₁ , and the 2 × 1 switch 803 _{M ′ / 2 + 1 is} branched. switch 804 ₁ selects the electrical signal, so that the output into an electrical signal output 513 _1.

That is, when information to be provided originally is communicated using the optical path in the four-fiber ring of FIG. 11, the information of the electric signal input 502 ₁ is transmitted to the modulator 501 _{1 in the} optical path termination circuit transmitting section 111f. And multiplexes with the wavelength of the optical path accompanied by other information to be originally provided using the wavelength coupler 601 to realize communication from the node to a certain node. An optical path for performing communication from a certain node to the node is demultiplexed by the wavelength separator 605 of the optical path termination circuit receiving unit 112f, and the M × M ′ optical switch 609 is used.
By such way path to be input is set to an optical signal termination circuit 511 _1, is converted into an electric signal by the optical signal termination circuit 511 _1, 2 × 1 switch 804 ₁ through an electrical signal output 51
3 is output to the _1.

At the same time, the optical path termination circuit transmitting section 111f
Is the electrical signal input 801_{M '/ 2 + 1}Extra traffic
Information is 2x1 switch 802_{M '/ 2 + 1}Through the modulator 50
1_{M ' +1}Input to the optical signal and extra traffic information
Is superimposed, and another extra traffic is
Multiplexed with the wavelength of the optical path of the
Communication with a new optical path is realized. Ma
In addition, in the optical path termination circuit receiving unit 112f, a certain node
To communicate extra traffic to the node
The path is split by the wavelength separator 607, and the M × M ′ switch
611, an optical signal termination circuit 511_{M '+ 1}Will be output to
The route is set, and the optical signal termination circuit 511 is set. _{M '+ 1}At electricity
Is converted into a signal and the 1 × 2 switch 803_{M '/ 2 + 1}By
Air signal output 805_{M '/ 2 + 1}Route is set to output to
It is.

On the other hand, the electric signal input 502₁Information
If a failure occurs in the optical path on which
Electrical signal input 801_{M '/ 2 + 1}Due to extra traffic
Service and electric signal output 805_{M '/ 2 + 1}Output to
Suspend service by Xtra traffic. Light path
In the termination circuit transmission unit 111f, the 2 × 1 switch 802
_{M '/ 2 + 1}The electric signal input 502 which has been branched₁of
The signal is selected, and the optical path termination circuit receiving section 112f selects 1
× 2 switch 803_{M '/ 2 + 1}Entered in the
The electric signal accompanying the information_{M '/ 2 + 1}By
Electric signal output 513₁Branch to output to
Itch 804₁Selects this electrical signal and outputs the electrical signal
513₁Will be output to

As described above, by using the wavelength division multiplexing optical communication network of this embodiment, within one ring network, services of different quality grades, such as a service that is continued even when a failure occurs and a service that is interrupted when a failure occurs, are provided. Services can be provided simultaneously.

[Seventh Embodiment] FIG. 12 is a block diagram showing a wavelength division multiplexing optical communication network according to a seventh embodiment of the present invention.
1 is an example configured by the wavelength multiplexing optical communication network described in 1. In this wavelength division multiplexing optical communication network, an optical path termination circuit of the wavelength division multiplexing optical communication network of the fourth embodiment of the present invention shown in FIG. A plurality of wavelengths to be added and dropped are divided into a wavelength group used at normal time and a wavelength group other than the wavelength group, and a connection is made to an optical add / drop circuit which is input / output. .

This wavelength division multiplexing optical communication network comprises optical add / drop circuits 101g and 102g, wavelength division multiplexing transmission lines 103 to 106 provided between two adjacent nodes,
Wavelength multiplexing transmission lines 107a, 107b, 108a, 108 provided between the optical path terminating circuit transmitting section 111g and the optical path terminating circuit receiving section 112g, and between the optical path terminating circuits 111g, 112g and the optical add / drop circuits 101g, 102g.
b, 109a, 109b, 110a, 110b.

The optical add / drop circuit 101g transmits a wavelength-multiplexed transmission line 103 from an adjacent node to an optical signal in which only the wavelengths for normal communication are multiplexed out of the branched optical signals. Using the multiplexed transmission line 108a, the wavelength separator 60 in the optical path termination circuit receiver 112g
5, and the optical signal in which only the wavelength used only at the time of the failure is multiplexed is transmitted to the wavelength separator 606 using the wavelength multiplexed optical transmission line 108b. At this time, of the wavelengths selected by the optical path terminating circuit transmitting unit 111g, only the wavelength for performing normal communication is inserted into the optical add / drop circuit 101g via the wavelength coupler 601 using the wavelength multiplexing transmission line 107a. The wavelength used only at the time of failure is inserted into the optical add / drop circuit 101g via the wavelength coupler 602 using the wavelength multiplexing transmission line 107b.

The optical signal inserted into the optical add / drop circuit 101g is multiplexed with other wavelengths not branched at the node, and transmitted to an adjacent node different from the node using the wavelength multiplexing transmission line 104. You.

The optical add / drop circuit 102g transmits the optical signal from the other adjacent node through the wavelength multiplexing transmission line 105, and converts the branched optical signal into the wavelength multiplexing transmission line 109a,
The signal is transmitted to the wavelength separators 607 and 608 in the optical path terminating circuit receiving unit 112g by using the optical path terminating circuit transmitting unit 111g.
A plurality of wavelengths transmitted using the wavelength multiplexing transmission lines 109a and 109b are inserted through 604, and the optical signal is transmitted to an adjacent node different from the node using the wavelength multiplexing transmission line 106.

At this time, the wavelengths to be dropped and added are separated into a wavelength group used for normal communication and a wavelength group used only at the time of failure, similarly to the optical add / drop circuit 101g described above. Wavelengths used only at the time of failure are multiplexed on the multiplex transmission lines 109a and 110a, and wavelengths for normal communication are multiplexed on the wavelength multiplex transmission lines 109b and 110b. Here, the wavelength multiplexing transmission line 10
Reference numerals 3 and 105 denote optical signal inputs from different adjacent nodes.

Next, the optical path termination circuits 111g and 112g
Will be described. The optical path termination circuit transmission unit 111g includes a fixed wavelength sharing light source 117 of M wavelengths,
An optical switch 118 having a scale of M × M ′ (M ≧ M ′ ≧ N−1), modulators 5011 to 5012M ′ for superimposing information on respective wavelengths by inputting an electric signal, and respective modulators on which information is superimposed. Optical signal transmission path 121 through which wavelength is transmitted
_{1 to} 1212M _', and wavelength couplers 601, 602, 603 and 604 for wavelength-multiplexing these transmitted wavelengths.

The optical path terminating circuit receiving section 112g includes wavelength demultiplexers 605 and 608 for demultiplexing the optical signals transmitted from the optical add / drop circuits 101g and 102g and multiplexing only the wavelengths for normal communication into respective wavelengths. And wavelength demultiplexers 606 and 607 for demultiplexing an optical signal in which only wavelengths used only at the time of failure are multiplexed into respective wavelengths, and M / 2 × M '/ for outputting the demultiplexed wavelength to a desired route. Two-optical switch 613, 614, 615, 616 (M ≧ M ′ ≧ N−1)
And M / 2 × M '/ 2 optical switches 613, 614, 61
5 and 616 for converting each wavelength output to an electric signal, and between the wavelength separators 613, 614, 615 and 616 and the optical signal termination circuits 5111 to 5112M '. An optical signal transmission line for transmitting an optical signal;
Electrical signal outputs 5131 to 513M 'for outputting signals converted to electrical signals at 5112M'.

Next, a wavelength for performing normal communication and a wavelength used only at the time of failure, which are features of the wavelength division multiplexing optical communication network of the present embodiment, are separated and added and dropped by the optical add / drop circuit. An example will be described using N = 15 as the number of nodes N. For example, the required number of wavelengths M (= (N2-1) / 4) for logically connecting the nodes of a two-fiber bidirectional ring with N = 15 in a full mesh state is M = 56.
It is. At this time, each node needs to add and drop 14 waves to perform normal communication with the other 14 nodes, and needs to add and drop the same number of 14 wavelengths as wavelengths used at the time of failure. That is, in FIG. 12, equal 14 wavelengths are selected from the 56 wavelengths input from the wavelength multiplexing transmission lines 103 and 105, respectively, into the optical add / drop circuits 101g and 101g.
02g, and divide them into optical path termination circuits 111.
g, 112g.

In the optical path terminating circuit transmitting section 111g, the same 14 wavelengths as the branched wavelengths are selected, each wavelength is divided into two by 1: 2 optical branching, and each of the two branched wavelengths is a normal one. Wavelengths used only for communication and failures are used, and seven wavelengths used for normal communication are input to the wavelength separator 601.
, A wavelength different from the seven wavelengths is input as a wavelength used only at the time of failure, and 14 wavelengths are input to the optical add / drop circuit 101g.

On the other hand, the 14 wavelengths inputted to the optical add / drop circuit 102g are similarly composed of 7 wavelengths each for normal communication and at the time of failure. The seven wavelengths used for normal communication are equal to the seven wavelengths input as wavelengths used only at the time of failure among the 14 wavelengths input to the optical add / drop circuit 101g, and are used only at the time of failure. These seven wavelengths are equal to the seven wavelengths input as wavelengths used for normal communication among the wavelengths input to the optical add / drop circuit 101g.

As shown in the present example, the wavelength for performing normal communication and the wavelength used only at the time of failure are separated, so that the wavelength coupler and the optical path termination circuit in the optical path termination circuit transmission unit 111g are separated. The wavelength demultiplexer in the receiving unit 112g only needs to be able to perform demultiplexing and multiplexing of seven wavelengths, respectively. Conventional wavelength multiplexing in which a wavelength used for normal communication and a wavelength used only for failure are not separated. Compared with the optical communication network, the size of the wavelength coupler and the wavelength separator can be reduced by half.

As described above, in the wavelength division multiplexing optical communication network of the present embodiment, it is possible to separate the wavelength used for normal communication from the wavelength used only at the time of failure, thereby reducing the wavelength coupler scale and the wavelength separator scale. The advantage that reduction can be achieved is obtained. As a result, it is possible to improve the simplicity of manufacturing due to downsizing of the optical component, and to realize that the failure of the optical component involving only the wavelength used at the time of failure does not affect normal communication.

In the present embodiment, in a state where no failure has occurred, a service different from that in normal communication is superimposed on a wavelength used only at the time of failure. Here, the extra traffic described in claim 14 is not implemented, but the ON / O of the optical path termination circuit transmission unit 111g in FIG.
The FF switches 5041 to 504M ′ are changed to 2 × 1 switches, an electric signal serving as an extra traffic is input to each 2 × 1 switch, and the FF switches 5041 to 504M ′ are used only when a failure occurs in the optical path termination circuit receiving unit 112g of FIG. A 1 × 2 switch is inserted after the M / 2 × M ′ / 2 switches 614 and 615 to which the wavelength is input, and one output of the 1 × 2 switch is input to the 2 × 1 switch, and the other is used as extra traffic. This can be dealt with by providing a configuration for outputting.

In the present embodiment shown in FIG. 12, a wavelength division multiplexing optical communication network is configured based on a configuration having four wavelength couplers and four wavelength splitters as optical path terminating circuits. Each of the two optical add / drop circuits has a configuration in which an optical signal multiplexed only with a wavelength for normal communication and an optical signal multiplexed only with a wavelength used only at the time of failure are separately input / output. If this is the case, the wavelength demultiplexer and wavelength demultiplexer that separate and combine those wavelengths are separated into those for normal communication wavelengths and those for extra traffic wavelengths. Not as long.

Further, the switching of the optical path is not necessarily performed by the ON / OFF switches 5041 to 504M 'for electric signals.
Need not be performed at the electrical level, for example, may be performed at the optical level by using an ON / OFF switch for an optical signal.

Further, in the present embodiment, the case where the switching at the time of failure is performed for each optical path has been described, but it is also possible to perform switching in units of M waves multiplexed on the wavelength multiplexing transmission line between nodes. . In this case, the wavelength multiplexing transmission lines 103 and 105 are input to the optical add / drop circuits 101g and 102g via 2 × 2 optical switches, and the wavelength multiplexing transmission lines (optical fibers) 104 and 106 are input via 2 × 2 optical switches. Connection to the 2 × 2 optical switch of the adjacent node.

[Eighth Embodiment] FIGS. 13 and 14
Is a configuration diagram illustrating a wavelength division multiplexing optical communication network according to an eighth embodiment of the present invention, and a two-fiber bidirectional ring that provides extra traffic according to claim 21 in the seventh embodiment; In this example, a two-fiber system is added and a four-fiber bidirectional ring is used to meet new optical path demands.

The optical add / drop circuit 101 in this embodiment
g, 102g, optical fibers 103 to 106, optical path termination circuit transmission section 111h, and optical path termination circuit reception section 112h.
Shows a two-fiber bidirectional ring wavelength multiplexing optical communication network that supports extra traffic. Before adding an optical fiber, the wavelength multiplexing transmission lines 107a and 108a are connected to the optical add / drop circuit 101g.
The wavelength multiplexing transmission lines 109b, 110b are connected to an optical add / drop circuit 102g, and the wavelengths of the optical paths for performing normal communication are respectively connected to these wavelength multiplexing transmission lines 107a, 108a, 109b, 110b. It is a multiplexed configuration.

The wavelength-division multiplexing transmission lines 107b and 108b are connected to the optical add / drop circuit 101g.
Reference numerals 09a and 110a are connected to the optical add / drop circuit 102g, and these wavelength multiplexing transmission lines 107b and
In b, 109a, and 110a, wavelengths for performing communication by extra traffic are multiplexed.

The optical path terminating circuit transmitting unit 111h is an example in which extra traffic is performed for the seventh embodiment, and an M-wave shared light source 117 as a wavelength generating source and an M ×
M ′ optical switch 118, 1: 2 optical branching 500 _{1 to} 500 _{2M ′ for} bifurcating the selected wavelength, electric signal input 502 _{1 to} 502M _′ with information to be provided, Modulators 501 _{1 to} 501 _{M ′} for superimposing electric signals
When, two branches the electrical signal with the information to be provided originally 1: _'and the electrical signal input 801 ₁ ~801 _M with extra traffic _information' 2 branches 503 ₁ ~503 _M and, should provide originally branched 2 × 1 switches 802 _{1 to} 802 _{M ′} for selecting an electric signal with information and an electric signal with extra traffic information, and wavelength couplers 601 to 604 for multiplexing wavelengths to be inserted into the optical add / drop circuit. ing. The wavelength multiplexing optical transmission line 1 for transmitting an optical signal having a wavelength to be inserted is provided to the wavelength couplers 601 to 604.
07a, 107b, 109a, and 109b are connected respectively.

The optical path terminating circuit receiving section 112h includes wavelength separators 605 to 608 and M / 2 × M '/ 2 optical switches 613 to 616 for sending the demultiplexed wavelength to a desired route.
When the optical signal terminating circuit 511 ₁ ~511 M for converting a received optical signal into an electric signal _'and an electrical signal output 513 ₁ ~513 M if the received information is the information to be provided _originally'
1 × 2 switch 803 _{1 that} outputs the signal to an electric signal output 805 ₁ to 805 _{M ′ in} the case of extra traffic
803 _{M ′} and 2 × 1 switches 804 _{1 to} 804 _{M ′} for selecting one of the two received electric signals. Here, the electrical signal input 502 ₁ to 502 _{M 'is} an electrical signal output 513 ₁ ~513 _M' respectively corresponding to the electrical signal input 801 ₁ ~801 _{M 'are} each an electrical signal output 805 ₁
.. 805 _{M ′} , and the corresponding relationship corresponds to two optical paths set bidirectionally between the node and another node.

FIG. 14 shows an example in which a two-fiber bidirectional ring having substantially the same configuration is newly added to the wavelength multiplexing optical communication network which is the two-fiber bidirectional ring of FIG. The added two-fiber bidirectional ring includes optical add / drop circuits 101i and 102i and optical fibers 103i to 103i between nodes.
106i, optical path termination circuit transmission section 111i, optical path termination circuit reception section 112i, and optical add / drop circuits 101i, 10
2i and a wavelength division multiplexing transmission line connecting between the optical path terminating circuits 111i and 112i.

Here, the communication direction of input from the optical fiber 103 and output to the optical fiber 104 and the optical fiber 10
The communication direction of input from the optical fiber 5i and output to the optical fiber 106i is the same, and the communication direction of input from the optical fiber 105 and output to the optical fiber 106 is the same as that of the optical fiber 103i.
The communication directions of the input and output to the optical fiber 104i are the same, and the two communication directions perform clockwise / counterclockwise communication with each other.

[0146] When the extension is performed, first, the extra traffic accommodated in the existing two-fiber bidirectional ring is exchanged. Before the start of the accommodation change, as shown in FIG. 13, the extra traffic is transmitted from the optical path terminating circuit transmitting units 111h and 112h of the existing wavelength division multiplexing optical communication device via the wavelength division multiplexing transmission lines 107b and 109a. 101g and 102g, and the wavelength division multiplexing transmission line 1 from the optical add / drop circuits 101g and 102g.
08b, 110a via the optical path termination circuit receiving section 112
h.

For the accommodation change, these communications are temporarily stopped, the wavelength multiplexing transmission lines 107b and 108b are connected to the input / output of the optical add / drop circuit 101i on the extension side, respectively, and the wavelength multiplexing transmission lines 109a and 110a are connected. This is performed by connecting to the input and output of the optical add / drop circuit 102i on the additional side, respectively. After the connection change of the wavelength multiplexing transmission line is completed, the service based on the extra traffic can be resumed. During this time, the normal communication accommodated in the wavelength multiplexing transmission lines 107a, 108a, 109b, 110b of the original two-fiber bidirectional ring continues to be operated without interruption.

Subsequently, in order to respond to new communication demands, wavelength multiplexing transmission lines 107c to 110d output from the optical path terminating circuit transmitting section 111i and the optical path terminating circuit receiving section 112i on the extension side, and optical branching. Insertion circuit 101g, 1
02g, 101i, and 102i. Due to the replacement of the extra traffic, the optical fiber 103
Of the M wavelengths accommodated in each of the optical fibers 103 to 106, 103i to 106i, half of the M wavelengths are used as wavelengths for performing normal communication or wavelengths for extra traffic.
The remaining M / 2 wavelengths respectively accommodated in 106 are used for a new normal communication service, and the optical fiber 103 is used.
The remaining M / 2 wavelengths respectively accommodated in i to 106i are used for a new extra traffic service.

For this reason, in order to superimpose ordinary communication information on the M / 2 wave not used in the optical fibers 103 and 104, the wavelength coupler 601i in the optical path terminating circuit transmitting section 111i on the extension side is used. The input of the optical add / drop circuit 101g is connected by a wavelength multiplexing transmission line 107c, and the wavelength separator 605i in the optical path termination circuit receiver 112i is connected to the output of the optical add / drop circuit 101g by a wavelength multiplexing transmission line 108c. I do.

Next, in order to superimpose ordinary communication information on the M / 2 wave not used in the optical fibers 105 and 106, the wavelength coupler 604i in the optical path terminating circuit transmitting section 111i on the extension side is used. The input of the optical add / drop circuit 102g is connected by a wavelength multiplexing transmission line 109d, and the wavelength separator 608i in the optical path termination circuit receiver 112i and the output of the optical add / drop circuit 102g are connected by a wavelength multiplexing transmission line 110d. I do. As described above, the optical fibers 103 to 106 contain only the wavelengths for normal communication.

On the other hand, in order to superimpose extra traffic information on M / 2 waves not used in the optical fibers 103i and 104i, an additional optical path terminating circuit transmitting unit 1 is added.
11i and the optical add / drop circuit 101
i and the input of i are connected by a wavelength multiplexing transmission line 107d,
Wavelength separator 606i in optical path termination circuit receiver 112i
And the output of the optical add / drop circuit 101i are connected by a wavelength multiplexing transmission line 108d.

Next, in order to superimpose the information of the extra traffic on the M / 2 wave not used in the optical fibers 105i and 106i, the additional side optical path terminating circuit transmitter 1
11i and the optical add / drop circuit 102
i and the input of i are connected by a wavelength multiplexing transmission line 109c,
Wavelength separator 607i in optical path termination circuit receiver 112i
And the output of the optical add / drop circuit 102i are connected by a wavelength multiplexing transmission line 110c. As described above, the optical fiber 10
In 3i to 106i, only the wavelength for performing the communication by the extra traffic is accommodated.

In the above expansion, for example, the following wavelength allocation is performed. That is, as shown in FIG.
In a fiber bidirectional ring, each optical fiber 103
To 106 each transmit an optical signal in which M wavelengths (λ _{1 to} λ _M ) are multiplexed. In the optical fibers 103 and 104, [lambda] _{1 to} [lambda] _{M / 2} are used for normal communication, and a few of them are dropped and added by the optical add _/ drop circuit 101g, and light is dropped and added by the wavelength multiplexing transmission lines 107a and 108a. transmitted between the circuit 101g and the optical path termination circuit transmitting portion 111h and an optical path termination circuit receiving section 112h, λ _{M / 2 + 1} using the to [lambda] _M to communication by extra-traffic, the number wave light branching and insertion of the The signal is added and dropped by the circuit 101g, and the signal is transmitted between the optical add / drop circuit 101g and the optical path terminating circuit transmitting unit 111h and the optical path terminating circuit receiving unit 112h by the wavelength multiplexing transmission lines 107b and 108b.

In the optical fibers 105 and 106, λ
_{1 to} λ _{M / 2} are used for extra traffic communication,
Among them, several waves equal in wavelength to the wavelengths transmitted through the wavelength multiplexing transmission lines 107a and 108a are output from the optical add / drop circuit 102g.
Multiplexed transmission lines 109a, 109
Between the OADM circuit 102g and the optical path termination circuit transmitting portion 111h and an optical path termination circuit receiving section 112h transmitted by 0a, using λ _{M / 2 + 1} ~λ _M normal communications during said of them Several waves equal in wavelength to the wavelength multiplexed transmission lines 107b and 108b are added and dropped by the optical add / drop circuit 102g, and the wavelength multiplexed transmission lines 109b and 110b are added.
Thus, the signal is transmitted between the optical add / drop circuit 102g and the optical path terminating circuit transmitting unit 111h and the optical path terminating circuit receiving unit 112h.

With such a configuration, the λ _{M / 2 + 1} of the wavelength-division multiplexing transmission lines 107b and 108b is changed by accommodating extra traffic accompanying the addition of a two-fiber system.
To λ _M are added and dropped by the optical add / drop circuit 101i, and the wavelengths of the wavelength multiplexed transmission lines 109a and 110a are
Several waves of _{1 to} λ _{M / 2} are added and dropped by the optical add _/ drop circuit 102i. Further, the optical path terminating circuit transmitting unit 111i and the optical path terminating circuit receiving unit 112 on the extension side
i and optical add / drop circuits 101g, 102g, 101i,
102i, the wavelength multiplexing transmission line 10
7c, the light branching and insertion as a wavelength where the wavelength-multiplexed transmission lines 107 b, the number wave equal to a wavelength that is transmitted by 108b performs normal communication when out of λ _{M / 2 + 1} ~λ _M transmitted using 108c Among the wavelengths λ ₁ to λ _{M / 2 that} are dropped and inserted in the circuit 101g and transmitted using the wavelength multiplexing transmission lines 109d and 110d, several waves equal to the wavelength transmitted in the wavelength multiplexing transmission lines 107a and 108a are generated. The wavelength is added and dropped by the optical add / drop circuit 102g as a wavelength at which communication is performed in a normal state.

The wavelength multiplexing transmission lines 107d and 108
In the optical add _/ drop circuit 101i, several wavelengths equal to the wavelengths transmitted through the wavelength multiplexing transmission lines 107a and 108a out of λ ₁ to λ _{M / 2} transmitted using d are used as the wavelengths for performing communication by extra traffic. Λ _{M / 2 + 1} which is added and dropped and transmitted using the wavelength multiplexing transmission lines 109c and 110c.
To λ _M, the wavelength multiplexing transmission lines 107b and 108b
Is added and dropped by the optical add / drop circuit 102i as a wavelength for performing communication by extra traffic.

In this embodiment, the M-wave fixed wavelength sharing light source 117i and the M × M M-wavelength-wavelength shared light source 117i are independent of the original two-fiber bidirectional ring optical-path termination circuit transmitter 111h. 'The optical switch 118i is provided, but the optical path terminating circuit transmitting unit 111i on the additional side is used.
Is the same as the wavelength selected by the optical path termination circuit transmitter 111h of the original two-fiber bidirectional ring, the M-wave fixed wavelength sharing light sources 117 and M are transmitted by the optical path termination circuit transmitter 111h. × M ′ The optical switch 118 branches the wavelengths selected by the optical switch 118, and the respective wavelengths are divided into 1: 2 optical branches 500i in the optical path terminating circuit transmitter 111i on the additional side.
By inputting 1 to 500 iM ', the same effect as in the present embodiment can be obtained.

As described above, in the wavelength division multiplexing optical communication network in which the two-fiber bidirectional ring of this embodiment is added,
The normal communication is not stopped at the time of expansion, and after the expansion, the wavelength multiplexing transmission line between the nodes is supported with the wavelength multiplexing transmission line supporting the normal communication and communication at the time of failure or communication by extra traffic. There is an advantage that the signal can be separated into a wavelength multiplexing transmission line. As a result, when the optical path is introduced, it is not necessary to use a four-fiber bidirectional ring for the demand that can be supported by a two-fiber bidirectional ring, and a ring network with high wavelength use efficiency is constructed. Can provide services economically.

Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described structure, but achieves the objects of the present invention and has the effects of the present invention. Changes can be made as appropriate within the range.

[0160]

As described above, according to the wavelength division multiplexing optical communication network of the present invention, by using individual optical paths as switching units, the path length of the optical path at the time of failure can be reduced. It is possible to cope with a failure in a node by a mechanism for switching in units of optical paths. In addition, the wavelength selection function provided in the transmission unit reduces the size of the wavelength coupler, reduces the number of modulators, reduces the size of the wavelength separator, increases the wavelength generation source and the wavelength selection unit or the wavelength variable light source unit, By making full mesh connection between nodes, wavelength resources can be effectively used.

As described above, the physical scale of the optical path termination circuit can be reduced, the cost of the optical path termination circuit can be reduced, a larger-scale ring network can be constructed, and an economical ring network can be constructed using a full-mesh optical path. be able to. Further, when providing an extra traffic service, services of different quality grades can be simultaneously provided within one ring network.

Further, the wavelengths added and dropped by the optical add / drop circuit are separated and added into a wavelength group used for normal communication and a wavelength group used at the time of a fault or extra traffic, and the wavelength is added and dropped. The maximum scale of the wavelength coupler and the wavelength separator in the path termination circuit can be reduced by half. By separately managing each of the wavelength coupler and the wavelength demultiplexer for communication at normal time and for failure or extra traffic, optical communication at normal time can be performed at the time of failure or wavelength for extra traffic. It is completely unaffected by coupler or wavelength separator failures.

In the optical add / drop circuit, the wavelength group used for normal communication and the wavelength group used in the event of a fault or extra traffic can be added / dropped, so that the input / output of these wavelength groups can be independent. If provided, there is no particular limitation on the configuration of the optical path termination circuit, and the switching unit can be made to correspond to either the optical path unit or the M wavelength unit. As a result, it is possible to simplify manufacturing by reducing the scale of required optical components, improve reliability, improve the arbitrariness of the optical path termination circuit configuration, select the switching unit according to the application area, and expand the ring network economically Becomes possible.

According to the wavelength division multiplexing optical communication apparatus of the thirteenth aspect of the present invention, the number of connections between the optical add / drop circuit and the optical path terminating circuit transmitting section and the optical path terminating circuit receiving section can be reduced. The number of signal termination circuits can be reduced. By changing the setting of the optical switch, the above two points can be achieved without manual connection. By using each optical path as a switching unit, the path length of the optical path at the time of failure can be reduced. A mechanism for switching in units of optical paths can cope with a failure in a node.

In addition, the size of the wavelength coupler is reduced, the number of modulators is reduced, the size of the wavelength separator is reduced, the wavelength generation source and the expandability of the wavelength selector or the wavelength tunable light source are increased, and the distance between nodes is fully improved. Advantages such as effective use of wavelength resources by mesh connection can be obtained. As a result, the physical scale of the optical path termination circuit can be reduced, the cost of the optical path termination circuit can be reduced, a larger-scale ring network can be constructed, and an economical ring network can be constructed using a full-mesh optical path. .
In addition, when providing extra traffic services, services of different quality grades can be provided simultaneously in one ring network.

According to the wavelength division multiplexing optical communication apparatus of the present invention, the wavelength added and dropped by the optical add / drop circuit is used for a wavelength group used for normal communication and for a failure or extra traffic. Since the wavelengths are separated and added to the wavelength group to be added, the maximum scale of the wavelength coupler and the wavelength separator in the optical path termination circuit can be reduced to half. Since each of the wavelength coupler and the wavelength separator can be separately managed for communication at normal time and for failure or extra traffic, the failure or failure of the wavelength coupler or wavelength separator for extra traffic occurs. On the other hand, normal communication is not affected at all.

In the case of expansion, it is only necessary to change the connection of the wavelength multiplexing transmission line for a failure or extra traffic, without interrupting the normal communication. After the four-fiber bidirectional ring is formed by the above connection change, the wavelength group used for normal communication and the wavelength group used at the time of failure or extra traffic are accommodated in different wavelength multiplexing transmission lines. In the case of a failure or a failure of the wavelength multiplexing transmission line accommodating the wavelength used for the extra traffic, the problem that normal communication is not affected is overcome.

In addition, an optical add / drop circuit that can separate and add a wavelength group used for normal communication and a wavelength group used at the time of failure or for extra traffic is provided independently of the input / output of these wavelength groups. There is a feature that the configuration of the optical path terminating circuit is not particularly limited as long as the switching is performed, and that the switching unit can correspond to both the optical path unit and the M wavelength unit. As a result, simplification of manufacturing by reducing the scale of required optical components, improvement of reliability, optionality of optical path termination circuit configuration, selection of switching unit according to application area, and economical expansion of ring network are realized. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a wavelength division multiplexing (WDM) ring network that is a wavelength division multiplexing optical communication network according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation of a WDM ring network which is a wavelength division multiplexing optical communication network according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a node configuration of a WDM ring network that is a wavelength division multiplexing optical communication network according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating an optical path termination circuit transmission unit of a wavelength division multiplexing optical communication network according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram illustrating an optical path termination circuit transmission unit of a wavelength division multiplexing optical communication network according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram illustrating a modified example of an optical path termination circuit transmission unit of a wavelength division multiplexing optical communication network according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram illustrating an optical path termination circuit transmission unit and an optical path termination circuit reception unit of a wavelength division multiplexing optical communication network according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram illustrating a modified example of an optical path termination circuit transmission unit and an optical path termination circuit reception unit of a wavelength division multiplexing optical communication network according to a fourth embodiment of the present invention.

FIG. 9 is a configuration diagram illustrating an optical path termination circuit transmission unit and an optical path termination circuit reception unit of a wavelength division multiplexing optical communication network according to a fifth embodiment of the present invention.

FIG. 10 is a configuration diagram illustrating an optical path terminating circuit transmitting unit and an optical path terminating circuit receiving unit of a wavelength division multiplexing optical communication network according to a sixth embodiment of the present invention.

FIG. 11 is a configuration diagram illustrating a modified example of an optical path termination circuit transmission unit and an optical path termination circuit reception unit of a wavelength division multiplexing optical communication network according to a sixth embodiment of the present invention.

FIG. 12 is a configuration diagram illustrating a wavelength division multiplexing optical communication network according to a seventh embodiment of the present invention.

FIG. 13 is a configuration diagram illustrating a wavelength division multiplexing optical communication network according to an eighth embodiment of the present invention.

FIG. 14 is a configuration diagram showing a modification of the wavelength division multiplexing optical communication network according to the eighth embodiment of the present invention.

FIG. 15 is a schematic configuration diagram showing a WDM ring network which is an example of a conventional wavelength division multiplexing optical communication network.

FIG. 16 is an explanatory diagram showing an operation of a conventional WDM ring network.

FIG. 17 is a configuration diagram illustrating an example of a conventional wavelength division multiplexing optical communication network.

FIG. 18 is a configuration diagram illustrating an example of a conventional wavelength division multiplexing optical communication network having a switching function.

[Explanation of symbols]

1a-1e node 2 optical fiber 3a working optical path 3b backup optical path 4 failure 101,102 optical add / drop circuit 103-106 optical fiber 107-110 wavelength multiplexing transmission line 111,111a-111h optical path termination circuit transmission unit 112, 112a~112h optical path termination circuit receiving section 113, 115 wavelength demultiplexer 114 wavelength coupler 117 shared source 118 optical switch 119 ₁ ~119 _{2M 'electrical} signal input 120 ₁ to 120 _2M' modulator 121 ₁ to 121 _{2M '} Optical signal transmission paths 122, 123 M × M' Optical switches 124 _{1 to} 124 _{2 M '} Optical signal termination circuits 125 _{1 to} 125 _{2 M} , 126 _{1 to} 126 _{2 M'} Optical signal transmission paths 127 ₁ to 127 _{2 M '} Electric signal output 201 , 202 wavelength coupler 203 _{1-203 14} variable wavelength light source 301 ₁ ~301α fixed wavelength shared light source 3 2 ₁ ~302α p × p optical switch 303 ₁ ~303 _p α × ₁ optical switches 304, 305 optical signal transmission line 401 ₁ ~401α fixed wavelength shared light source 402 ₁ ~402α p × p optical switch 403 ₁ to 403 _M light Branch 404 _{1 to} 404 _{m · p} α × 1 Optical switch 405, 406 Optical signal transmission line 500 _{1 to} 500 _{M ′} 1: 2 optical branch 501 _{1 to} 501 _{2M ′} modulator 502 _{1 to} 502 _{M ′} electric signal input 503 ₁ ５０503 _{M ′} 1: 2 branch 504 ₁ ５０504 _{M ′} ON / OFF switch 505, 506 Wavelength combiner 507,508 Wavelength separator 509,510 M × M ′ optical switch 511 ₁ ５512 _{M ′} optical signal termination circuit 512 _{1 to} 512 _{M ′} 2 × 1 switch 601 to 604 Wavelength coupler 605 to 608 Wavelength separator 609 to 612 M × M ′ optical switch 701 _{1 to} 701 _{M ′} modulator 702 _{1 to} 702 _{M '} 1: 2 optical branching 703 _{1 to} 703 _M' ON / OFF switch 704, 705 Wavelength coupler 706 _{1 to} 706 _{M '} 2 × 1 optical switch 707 _{1 to} 707 _M' optical signal termination circuit 801 ₁ to 801 _{M '} electric signal input 802 _{1 to} 802 _M' 2 × 1 switch 803 _{1 to} 803 _{M '} 1 × 2 switch 804 _{1 to} 804 _M' 2 × 1 switch 805 _{1 to} 805 _{M '} electric signal output

Claims (23)

[Claims] 1. A plurality of nodes are connected in a ring using a plurality of optical fibers, and half of the optical fibers connected between the nodes perform clockwise and counterclockwise optical communication.
In a wavelength division multiplexing optical communication network in which an arbitrary logical network is formed in the node by a signal channel accommodated in the optical fiber, each of the nodes includes a plurality of optical add / drop circuits and an optional A transmitting unit that selects a plurality of wavelengths combined, performs wavelength allocation, and outputs a signal channel, a receiving unit that inputs the signal channel, between the optical add / drop circuit and the transmitting unit, and the optical branch. A transmission line provided between the insertion circuit and the reception unit, for transmitting any one of a plurality of wavelengths to be dropped and added at the node; and WDM optical communication network for communicating with a plurality of nodes. 2. The wavelength multiplexing apparatus according to claim 1, wherein the transmitting unit includes a light source that outputs a plurality of different specific wavelengths, and an optical switch that selects an arbitrary plurality of wavelengths from the wavelengths. Optical communication network. 3. The wavelength-division multiplexing optical communication network according to claim 1, wherein the transmission unit is provided with light sources for outputting light of an arbitrary wavelength at least for the number of wavelengths to be inserted. 4. The light source according to claim 1, wherein the light source divides the light source into a plurality of light source groups each of which outputs a plurality of light beams having different wavelengths. 3. The wavelength division multiplexing optical communication network according to claim 2, further comprising a switch. 5. An optical signal to be superimposed on each of a plurality of selected wavelengths is split into two, and when optical communication by a signal channel on which one of the split electric signals is superimposed is interrupted, the signal is split. The other electric signal is superimposed on an optical signal having the same wavelength as that of the signal channel, and the optical signal is inserted into an optical add / drop circuit connected to an optical fiber that performs optical communication between the nodes in a direction opposite to the signal channel. The wavelength division multiplexing optical communication network according to any one of claims 1 to 4, wherein: 6. When no failure occurs in optical communication,
An optical add / drop multiplexer connected to an optical fiber that superimposes an electric signal different from the electric signal on an optical signal having the same wavelength as the signal channel and performs communication between the nodes in a direction opposite to the signal channel. The optical signal is inserted into a circuit, a new signal channel is formed, optical communication is performed, and when a failure occurs in the optical communication, the optical communication using the new signal channel is interrupted and the optical communication before the optical communication is performed is performed. The wavelength division multiplexing optical communication network according to claim 5, wherein communication is restored. 7. When communication of a selected one of a plurality of wavelengths is branched into two and an optical signal of one wavelength on which an electric signal is superimposed is interrupted by a signal channel,
Superimposing an electric signal on the other optical signal of the other wavelength, and inserting the optical signal between the nodes into an optical add / drop circuit connected to an optical fiber performing optical communication in the opposite direction to the signal channel; The method according to any one of claims 1 to 4, wherein
2. A wavelength division multiplexing optical communication network according to claim 1. 8. The optical add / drop circuit integrates one or two of a wavelength coupler, a wavelength multiplexer, a wavelength separator, and a wavelength multiplexer / demultiplexer, and a plurality of optical switches. The wavelength division multiplexing optical communication network according to any one of claims 1 to 4, wherein: 9. The wavelength-multiplexed transmission line according to claim 1, wherein said transmission line is a wavelength-multiplexed transmission line for performing optical signal transmission using wavelength-multiplexed signal light. Multiplexed optical communication network. 10. An optical fiber between two adjacent nodes is used, and these optical fibers are used only when a normal optical communication is performed and when a failure occurs in the optical communication. An optical signal multiplexed with the same number of wavelengths is transmitted, and a combination of the wavelength used for the normal optical communication and the wavelength used only when the failure occurs is used to perform optical communication in the same direction. Regarding the optical fiber, the same combination is used between all nodes, and the optical fiber that performs one of clockwise or counterclockwise optical communication is a different combination from the optical fiber that performs one of the other optical communication. The wavelength division multiplexing optical communication network according to any one of claims 1 to 4, wherein: 11. A wavelength division multiplexing optical communication network comprising a plurality of wavelength division multiplexing optical communication networks according to claim 10 cross-connected. 12. A wavelength multiplexing optical communication network, wherein one wavelength multiplexing optical communication network is cross-connected to another wavelength multiplexing optical communication network without interrupting the optical communication. Claim 1
2. The wavelength division multiplexing optical communication network according to 1. 13. N nodes are connected in a ring shape using two or four optical fibers between each node, and half of the optical fibers between each node are clockwise and counterclockwise communication. By using an optical path accommodated in the optical fiber, at least M waves (M = (N ² −1) / 4 for ^two fibers, M = (N ² −1) / 8 for four fibers, N = 2k, 2k + 1
(K is an integer of 1 or more)), and the nodes can be connected to each other in a full mesh or a full mesh or more with the required number of wavelengths. Each optical path is identified by a different wavelength and passes through bidirectional communication between the same nodes. In a wavelength division multiplexing optical communication network using optical fibers for equalizing nodes, each node includes a plurality of optical add / drop circuits serving as add / drop circuits for optical signals having different wavelengths, an optical path termination circuit, and an optical path termination circuit. And a plurality of wavelength multiplexing transmission lines for transmitting signal light between the add / drop circuits, wherein the optical add / drop circuit includes an optical fiber that transmits a wavelength multiplexed optical signal input from one adjacent node, and the other. An optical fiber for transmitting a wavelength multiplexed optical signal output to an adjacent node of the optical fiber, and a wavelength multiplexed optical transmission line for transmitting an optical signal in which a plurality of wavelengths branched at the node are multiplexed; A wavelength-multiplexed optical transmission line for transmitting an optical signal in which a plurality of wavelengths inserted in the node is multiplexed is connected, and an optical signal in which a plurality of wavelengths branched in the node is multiplexed is transmitted. The wavelength multiplexed optical transmission line is connected to an optical path termination circuit receiving unit, and the wavelength multiplexed optical transmission line for transmitting an optical signal in which a plurality of wavelengths inserted at the node is multiplexed is an optical path termination circuit transmitting unit. The optical path terminating circuit transmitting unit has a wavelength generation source of an M wave, a wavelength selection or a wavelength variable circuit, and has a function of selecting at least an arbitrary N-1 wave from the M waves, The optical path terminating circuit transmission unit includes a wavelength coupler or a wavelength multiplexer for multiplexing at least the selected N-1 waves, and the wavelength coupler or the wavelength multiplexer includes an optical add / drop multiplexer of the node. Input multiple wavelengths to be inserted in the circuit The optical path terminating circuit receiving section, a wavelength separator for demultiplexing the wavelength multiplexed optical signal input from the optical add / drop circuit, and an optical switch for outputting a plurality of separated wavelengths to a desired route, A wavelength division multiplexing optical communication device comprising at least N-1 optical signal termination circuits for converting optical signals of respective wavelengths output by the optical switch into electric signals. 14. The M-wavelength wavelength generation source is constituted by a shared light source having a fixed wavelength, and at least N-wavelength is controlled by an optical switch.
14. The wavelength division multiplexing optical communication device according to claim 13, wherein one wave can be selected. 15. The wavelength generation source of the M wave is M
14. The wavelength division multiplexing optical communication device according to claim 13, comprising at least N-1 variable wavelength light sources capable of transmitting waves. 16. generation source alpha number of the M-wave (alpha is an integer of 2 or more) is divided into shared light source, each of the shared light source is divided in M _i wave (? M _i = M, 2 ≦ i ≦ α), each shared light source is connected using a plurality of small-scale optical switches, and the optical switch network can select and transmit at least an arbitrary wavelength of at least N−1 waves from M waves. The wavelength division multiplexing optical communication device according to claim 14. 17. An electric signal superimposed on at least each of the selected N-1 wavelengths is bifurcated, and when communication via an optical path on which one electric signal is superimposed is interrupted, the other bifurcated one is used. Is superimposed on an optical signal having the same wavelength as the optical path, and the optical signal is inserted into an optical add / drop circuit connected to an optical fiber for performing communication in the opposite direction to the optical path between nodes. 17. Communication can be performed by performing
The wavelength division multiplexing optical communication device according to any one of the above. 18. When at least the selected N-1 wavelengths are bifurcated, and when communication via an optical path of one wavelength on which an electric signal is superimposed is interrupted, the other wavelength is bifurcated. Communication can be performed by superimposing an electric signal and inserting the optical signal between the nodes in an optical add / drop circuit connected to an optical fiber that performs communication in the opposite direction to the optical path. Claim 13
17. The wavelength division multiplexing optical communication device according to any one of items 16 to 16. 19. A modulator that superimposes an electric signal identical to an electric signal superimposed on an optical path that has failed at the time of a failure in a state where no failure has occurred in the ring network.
An optical add / drop switch in which an optical signal different from the electrical signal is superimposed on an optical signal having the same wavelength as that of the optical path, and an optical fiber for performing communication in a direction opposite to the optical path between the nodes is connected to the optical signal. 19. A new optical path is constructed and communication is performed by inserting it in a circuit, and when a failure occurs, communication using the new optical path is interrupted and communication using the original optical path is continued. A wavelength-division multiplexing optical communication device according to any of the preceding claims. 20. An optical signal transmission between an optical add / drop circuit and an optical path terminating circuit transmitting unit and an optical path terminating circuit receiving unit using a wavelength multiplexed optical transmission line.
3. The wavelength division multiplexing optical communication device according to 3. 21. N nodes are connected in a ring between each node by using a plurality of wavelength multiplexing transmission lines, and half of the wavelength multiplexing transmission lines between the nodes are clockwise and counterclockwise. Around the network, at least nodes can be connected in a full mesh or full mesh or more by optical paths, each optical path is identified by a different wavelength, and wavelength multiplexing enables bidirectional communication between the same nodes to equalize transit nodes. In a wavelength multiplexing optical communication network performed using multiplexed transmission lines, two wavelength multiplexing transmission lines are provided between adjacent nodes, and each of the two wavelength multiplexing transmission lines performs normal communication. Transmits an optical signal in which half the wavelength and the wavelength used only at the time of failure are multiplexed by half, and the combination of the wavelength used for normal communication and the wavelength used only for failure is in the same direction. The wavelength multiplexing transmission line that carries out the communication of the above is common to all nodes, and the wavelength used for normal communication on the wavelength multiplexing transmission line that carries out the clockwise communication is counterclockwise. The wavelength used only when a failure occurs in a wavelength multiplexing transmission line that performs communication and is used only when a failure occurs in a wavelength multiplexing transmission line that performs clockwise communication is usually used in a wavelength multiplexing transmission line that performs counterclockwise communication. Each node is provided with a plurality of optical add / drop circuits serving as add / drop circuits for optical signals having different wavelengths, and includes an optical path terminating circuit including a receiving unit and a transmitting unit, and A plurality of wavelength multiplexing transmission lines for transmitting signal light between the optical path terminating circuit and the add / drop circuit, wherein the optical add / drop circuit has a wavelength multiplexing transmission for transmitting a wavelength multiplexed optical signal input from an adjacent node; A transmission path, a wavelength-division multiplexing transmission path for transmitting a wavelength-division multiplexed optical signal output to the other adjacent node, and, of a plurality of wavelengths branched by the node, only a wavelength for normal communication is multiplexed. Wavelength-multiplexed optical transmission line for transmitting an optical signal, a wavelength-multiplexed optical transmission line for transmitting an optical signal in which only wavelengths used only at the time of a failure are multiplexed, and a plurality of wavelengths inserted at the node. Among them, a wavelength multiplexing optical transmission line for transmitting an optical signal multiplexed only with a wavelength for normal communication and a wavelength multiplexing optical transmission line for transmitting an optical signal multiplexed only with a wavelength used only at the time of failure. Are connected at the node, a wavelength-multiplexed optical transmission path for transmitting an optical signal in which a plurality of wavelengths for normal communication are multiplexed, and a plurality of wavelengths used only at the time of failure. Wavelength multiplexing for transmitting multiplexed optical signals Each of the transmission lines is connected to an optical path termination circuit receiving unit, and is inserted at the node, a wavelength multiplexed optical transmission line that transmits an optical signal in which a plurality of wavelengths performing normal communication are multiplexed, Each of the wavelength multiplexing optical transmission lines for transmitting an optical signal in which a plurality of wavelengths are multiplexed and used only at the time of a fault is connected to an optical path terminating circuit transmitting section, and wavelength multiplexing between the optical add / drop circuit and the optical path terminating circuit is performed. A wavelength division multiplexing optical communication device characterized in that the multiplexed transmission path is separated into a transmission path used for normal communication and a transmission path used only at the time of failure. 22. A wavelength division multiplexing optical communication device using a plurality of wavelength division multiplexing optical communication devices according to claim 21, wherein the two-fiber bidirectional ring configured using these wavelength division multiplexing optical communication devices, A four-fiber bidirectional ring network is constructed by newly adding the wavelength multiplexing optical communication device according to claim 21 to each node of the ring network without interrupting normal communication of the two-fiber bidirectional ring network. A wavelength division multiplexing optical communication device characterized by the above-mentioned. 23. An optical signal in which a plurality of wavelengths are multiplexed, a plurality of arbitrary wavelengths are dropped and inserted, and the plurality of wavelengths to be dropped and added are separated into a wavelength group normally used and a wavelength group other than the wavelength group. And an optical add / drop circuit.