JPH10271071A - Optical communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a system to attain communication among many nodes with a small wavelength multiplexity and to flexibly revise a topology of an optical communication network. SOLUTION: A system is provided with a plurality of optical communication networks 11, 13. Each optical communication network includes a plurality of nodes 11a-13d, each having a path changeover function and optical fiber networks 15a, 15b interconnecting the nodes. The optical fiber network for each optical communication network is made up of an active optical fiber 15a forming a predetermined topology and a standby optical fiber 15b contributing to revision of a topology with the path changeover function of the node. An exchange 17 is connected to node sets 19a-19d each consisting of a node selected from a plurality of optical communication networks one by one without duplication. The other ends of the exchange 17 are connected to subscribers 21a-21d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication system.

[0002]

2. Description of the Related Art For example, Document I (O plus
E), No. 194, pp. 75-79, pp. 100-105, especially p. 77, Fig. 3)
In the configuration, each node of the optical communication network is configured by an optical cross-connect that switches a path according to a wavelength, and each node is connected by an optical fiber capable of transmitting wavelength-multiplexed light.
An optical communication network is disclosed.

[0003] According to this conventional optical communication network, a route passing through the optical communication network can be made different for each wavelength. Therefore, by using the light having the wavelength λn, a signal can be transmitted to the node n in the optical communication network.

[0004]

By the way, when trying to construct a larger-scale optical communication system by directly following the concept of the conventional optical communication network, it is necessary to increase the number of nodes and to increase the wavelength multiplexing degree. It is necessary to change the device configuration in response to the increase in wavelength multiplexing.

However, at present, the wavelength multiplicity is 32
Degree is the limit. Further, as the wavelength multiplexing degree is increased, it is necessary to increase the types of signal light sources and wavelength filters. In addition, it is considered that the configuration of the node becomes complicated. Therefore, if the concept of the conventional optical communication network is directly followed, it is considered that there is naturally a limit to simply constructing a large-scale optical communication system.

[0006] The problem of the limit of multiplexing and the problem of complicated device configuration is not limited to the case of using the multiplexing system of wavelength multiplexing. It is considered that this also occurs when spatial multiplexing is used in which optical fibers are connected by an optical fiber bundle.

When the number of nodes is increased and the wavelength multiplicity is increased, an optical communication system of a reasonable scale can be obtained. However, when the number of nodes is simply increased and the wavelength multiplicity is increased, The flexibility when changing the topology of the optical communication network is poor.

Therefore, there is a demand for an optical communication system capable of setting the wavelength multiplicity within the range of the multiplicity of the current multiplexing system, realizing a large-scale optical communication system, and flexibly adapting to topology changes.

[0009]

According to the present invention, there is provided an optical communication system for performing communication using an optical signal multiplexed in a predetermined system, comprising: a plurality of optical communication networks, Includes a plurality of nodes having a path switching function and an optical fiber network connecting these nodes, and furthermore, an optical fiber network for each optical communication network forms a predetermined topology (network form) for each optical communication network. A plurality of optical communication networks, each of which comprises a working optical fiber and a spare optical fiber which is enabled by a path switching function of the node to contribute to a change in topology. One end is connected to at least two of these optical communication networks via one node of each of these optical communication networks, and the other end is connected to a subscriber or the like, and the subscriber or the like is connected to the at least two optical communication networks. Characterized in that at least one comprises a switch for selectively connecting to one of the networks.

The operation of the optical communication system of the present invention will be described with reference to an example of a simplified optical communication system. This will be described with reference to FIG.

Here, an optical communication system including two optical communication networks 11 and 13 is considered. Naturally, two optical communication networks 1
1 and 13 respectively have four nodes 11a to 11d (1
3a to 13d) are provided in a ring shape, and these nodes are connected by optical fibers 15a capable of transmitting optical signals by a predetermined multiplexing method (wavelength multiplexing in this case). These optical fibers 15a are currently used active optical fibers (shown by thick solid lines in FIG. 1).
And Further, a spare optical fiber 1 is connected between nodes.
5b (shown by a thick broken line in FIG. 1).

Further, in the optical communication network 11, the optical communication network 1
When an optical signal of wavelength λ1 is input to node 1, the optical signal is output to node 11 a.
1b, consider an example in which each node is configured such that an optical signal of wavelength λ3 is output to node 11c and an optical signal of wavelength λ4 is output to node 11d. Similarly, in the optical communication network 13, the optical signal having the wavelength λ1 is transmitted to the node 13a, the optical signal having the wavelength λ2 is transmitted to the node 13b, and the optical signal having the wavelength λ3 is transmitted to the node 13a.
Consider an example in which each node is configured so that the optical signal of c and the wavelength λ4 is output to the node 13d.

The switch 17 can be connected to the two optical communication networks 11 and 13 in such an arrangement that the connection required by the optical communication system can be made according to the concept of the present invention. In the case of FIG. 1, an example is shown in which the exchange 17 is connected to each of a pair of nodes 19 a to 19 d including nodes selected one by one from the two optical communication networks 11 and 13 without duplication. Of course, each exchange 17 is connected to a medium (hereinafter, referred to as a subscriber 21a to 21d in FIG. 1) which the subscriber 21x and / or a lower communication network 21y or the like which desires communication, such as a subscriber 21x. An example is shown.

Here, the subscriber 21 can communicate only with the four nodes only with the optical communication network 11 or only with the optical communication network 13. However, the switching of the optical communication network by the exchange 17 causes the subscribers 21 to switch to the optical communication network 11.
In addition, optical communication can be performed with the optical communication network 13. Therefore,
The subscribers 21 can selectively perform optical communication with eight nodes. In addition, although the optical communication can be selectively performed with the eight nodes, the wavelength multiplicity of each of the optical communication networks 11 and 13 can be kept at 4. Of course, the number of optical communication networks similar to the optical communication networks 11 and 13 is further increased, and by connecting the waveguides from the exchange 17 to the nodes of the increased optical communication networks respectively, the subscribers 21 Can further increase the number of nodes that can perform optical communication. Even so, the wavelength multiplicity of each of the optical communication networks 11 and 13 may remain at 4. Therefore, it is considered that a large-scale optical communication system can be realized without increasing the multiplicity.

Using only one optical communication network, subscribers 21
The characteristics of the present invention can be understood in comparison with the point that, in order to perform optical communication with eight nodes, it is necessary to prepare eight nodes in one optical communication network and set the wavelength multiplicity to eight.

Further, in the optical communication system according to the present invention,
If you want to change the topology of each optical communication network 11, 13,
The change can be made by activating any of the spare optical fibers. Depending on how the topology is changed, the working optical fiber may be used as it is, or an arbitrary optical fiber of the working optical fiber may be changed to a spare optical fiber. For example, in the optical communication network 11 of FIG.
c and the standby optical fiber between the nodes 11a and 11b and the active optical fiber between the nodes 11b and 11c are respectively used as the standby optical fibers. By changing the topology of the optical communication network 11 to the node 1
It is changed to a ring network of 1a, node 11c, and node 11d. Therefore, the feature of the present invention that the topology of the optical communication network can be flexibly changed can be understood.

The above operation is not limited to the example using wavelength multiplexing, but can also be obtained in other multiplexing systems. For example, in the case of packet multiplexing, a large-scale optical communication system can be constructed while reducing the types of headers. Also, in the case of spatial multiplexing using an optical fiber bundle, a large-scale optical communication system can be constructed while keeping the number of optical fibers small.

Therefore, according to the optical communication system of the present invention, it is possible to realize a large-scale optical communication system within the range of the multiplexing degree of the current multiplexing method and easily and with excellent flexibility in changing the topology. it is conceivable that.

In practicing the present invention, each of the plurality of nodes is connected to an optical cross-connect unit and an Add.D
It is preferable to adopt a configuration including a rop portion.

Here, the optical cross-connect unit is responsible for switching the path of the multiplexed optical signal at the node, which will be described later in detail. According to this optical cross-connect unit, switching between the working optical fiber and the standby optical fiber can be easily performed.

On the other hand, the Add / Drop unit is provided between the optical cross-connect unit and the optical switch, and inputs an arbitrary optical signal conforming to the multiplex system from the subscriber or the like to the optical cross-connect unit. Also, a specific optical signal predetermined for the node is output from the multiplexed optical signal to the subscriber or the like. According to the Add / Drop unit, transmission and reception of an optical signal between the optical communication network and the exchange are facilitated.

In practicing the present invention, it is preferable that the optical cross-connect unit is an optical cross-connect unit that switches paths based on an optical signal separation element defined by the multiplexing method. In this case, individual optical signals in the multiplexed optical signal can be easily routed. Here, the multiplexing method can typically be wavelength multiplexing, packet multiplexing, or subcarrier multiplexing. Alternatively, a method in which these are combined can be used. The optical signal separation element can be a wavelength in wavelength multiplexing, a header in packet multiplexing, and a subcarrier in subcarrier multiplexing.

Further, in practicing the present invention, the optical cross-connect section includes a plurality of wavelength demultiplexing elements, a plurality of multiplexing elements, an output terminal group of the plurality of wavelength demultiplexing elements, and the plurality of multiplexing elements. The input terminal group of the element and the Add-Dro
It is preferable to use an optical matrix switch for controlling the connection relationship between the p units.

In the case of the configuration including the plurality of wavelength demultiplexing elements, the working optical fiber and the spare optical fiber on the input side at each node can be connected to the plurality of wavelength demultiplexing elements without overlapping.
Further, the working optical fiber and the spare optical fiber on the output side can be connected to a plurality of multiplexing elements without overlapping (see FIG. 3). Then, the optical matrix switch routes each optical signal in the wavelength-multiplexed optical signal so as to match the required communication path. Therefore, an optical communication system according to the present invention, which is suitable for handling wavelength-multiplexed optical signals, is realized.

In practicing the present invention, the optical cross-connect section is an M × N optical matrix switch, and the Add-Drop section is provided between a part of its input terminal and a part of its output terminal. May be configured by an M × N optical matrix switch to which is connected. In this configuration,
The configuration of the optical cross connect unit can be simplified.

In practicing the present invention, it is preferable that each optical communication network is a ring network or a bus network.
In this case, the control of the optical communication network can be easily performed as compared with the case where the mesh network is used.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an optical communication system according to the present invention will be described below with reference to the accompanying drawings.
However, the drawings used in the description are only schematically shown to the extent that the present invention can be understood. Further, in each of the drawings used for the description, the same components are denoted by the same reference numerals, and the duplicate description thereof may be omitted.

1. First Embodiment FIG. 2 is a diagram for explaining one embodiment of the optical communication system according to the present invention.

The optical communication system according to the first embodiment includes first to fourth four optical communication networks 31, 33, 35, 3
7 is provided as an example.

In this case, each of the first to fourth optical communication networks 31 to 37 is an example having seven nodes. That is, the first optical communication network 31 includes the nodes 31a to 31a.
31g, and the second optical communication network 33 includes the nodes 33a to 33g.
33g, and the third optical communication network 35 includes the nodes 35a to 35a.
35g, and the fourth optical communication network 37 includes nodes 37a to
37 g. The node is a node that distributes optical signals (route switching), inputs (Add) an optical signal from a subscriber or the like to an optical communication network, and outputs (Drop) an optical signal from an optical communication network to a subscriber or the like. Part. This configuration will be described later.

However, these first to fourth optical communication networks 31
In each of Nos. To 37, a node currently available as an optical communication node is different. Specifically, in the first optical communication network 31, 31a, 31b, 31c, 31d, 31
The six nodes indicated by e and 31g are currently available for optical communication. In the second optical communication network 33,
Five nodes 33a, 33b, 31e, 33f, and 33g are currently available for optical communication. In the third optical communication network 35, 35b, 35c, 35
The four nodes indicated by d and 35e are currently available for optical communication. In the fourth optical communication network 37,
Four nodes denoted by 37c, 37d, 37e, and 37f are currently available for optical communication. Each of the optical communication networks 31 to 37 is an example in which nodes usable for optical communication constitute a ring network.

In each of the optical communication networks 31 to 37, which node can be used for optical communication is not limited to the above example, but can be determined according to the design of the optical communication system. Of course, in each of the optical communication networks 31 to 37, all of the nodes may be nodes usable for optical communication. In order to make the nodes usable for optical communication, the nodes to be used may be sequentially connected by optical fibers. The connection between the optical fiber and the node
The connection between the optical fiber and the node may be made effective by the path switching function of the node (the details will be described later with reference to FIG. 3). Here, the optical fiber effectively connected to the node is referred to as a working optical fiber 15a (shown by a thick solid line in FIG. 2). On the other hand, an optical fiber which is not connected to the node at present but is set as the working optical fiber 15a by a path switching function (described later) of the node is referred to as a spare optical fiber 15b (shown by a thick broken line in FIG. 2). . The topology of the optical communication network can be changed by replacing the spare optical fiber with the working optical fiber.

In implementing the invention, node 3
1a, 33a, 35a and 37a are grouped as one set.
Nodes 31b, 33b, 35b and 3
7b are provided in one station as a set,..., And the nodes 31g, 33g, 35g and 37g are provided as a set and provided in another station.

In each optical communication network, the way of arranging optical fibers between nodes is arbitrary according to the design of the optical communication system. Further, the number of spare optical fibers prepared for one node can be arbitrarily determined. In the example of FIG.
The connection of each optical fiber between nodes is performed by each optical communication network 31 to
37 are the same.

Each working optical fiber and each spare optical fiber provided between the nodes are typically constituted by one optical fiber in which light of different wavelengths is multiplexed. However, this is only an example, and the working optical fiber and the spare optical fiber may be an optical fiber bundle that realizes spatial multiplexing.

In the optical communication system according to the first embodiment, one end is a subscriber 21 (21a to 21a in FIG. 2).
g. ) And the other end is connected to a plurality of optical communication networks 31 to 3.
7 exchanges respectively connected to one node of at least two of the optical communication networks 7 and selectively connecting the subscribers or the like to one of the nodes connected to the other end. (Indicated by 39a to 39g in FIG. 2).

More specifically, in the present embodiment, each of the exchanges 39a to 39g is a node (for example, 31a, 33a, 35) provided at the same station among the nodes of each optical communication network.
a, 37a). Therefore,
For example, the exchange 39a connects the subscriber 21a to the node 3
1a, 33a, 35a, and 37a. However, in the case of the example of FIG. 2, the optical fiber going from the node 35a to the other node 35b or 35g is a spare optical fiber, so that the subscriber 21a can use the other nodes 35b to 35g in the optical communication network 35. Is not connected.
Of course, if the optical fibers from the node 35a to the nodes 35b and 35g are connected to be working optical fibers, the subscribers 21a can be connected to the remaining nodes 35b to 35g in the optical communication network 35.

Next, the configuration of each node of each of the optical communication networks 31 to 37 will be described by taking the node 31e as an example. This description will be made with reference to FIGS. Here, FIG. 3A shows the first node 31e.
FIG. 3B is an explanatory diagram of a second example of the node 31e. However, in order to make it easier to understand the connection relationship with the exchange 39e and the like, the exchange 39e and the subscribers 21e etc.
Are also illustrated.

Each of the nodes 31e shown in FIG. 3 includes an optical cross-connect unit 41 and an Add / Drop unit 43.

The optical cross-connect unit 41 is responsible for switching the path of the multiplexed optical signal. Add ・ D
The rop unit 43 inputs an arbitrary optical signal conforming to the multiplexing method from the subscriber 21 to the cross-connect unit,
A specific optical signal predetermined for the node is output from the multiplexed optical signals.

In this case, the optical cross-connect unit 41 includes first and second two wavelength demultiplexing elements 41a and 41b,
First and second two multiplexing elements 41c and 41d, output terminal groups of these wavelength demultiplexing elements 41a and 41b, input terminal groups of multiplexing elements 41c and 41d, and Add / Drop
An optical matrix switch 41e for controlling the connection relationship between the units 43 is provided.

Here, here: the optical fiber connected to the input terminal of the first wavelength demultiplexing element 41a becomes the spare optical fiber 15b (however, the one between the node 31b); The optical fiber connected to the input terminal of the wave element 41b becomes the working optical fiber 15a (however, the one between the node 31d), and the optical fiber connected to the output terminal of the first multiplexing element 41c is The optical fiber 15b (however, the one between the node 31f) is used. The optical fiber connected to the output terminal of the second multiplexing element 41d is connected to the working optical fiber 15a (however, the node 3f).
1g). Therefore, as shown in FIG. 3A, the optical matrix switch 41e in this case performs switching so as to make the connection between the second wavelength demultiplexing element 41b and the second multiplexing element 41d effective. I do. However, the optical matrix switch 41e
Switches the optical signal of the predetermined wavelength λn to the node 31e so as to be connected to the Add / Drop unit 43.

Here, the second wavelength demultiplexing element 41
If the optical matrix switch 41e is operated so as to connect between the first multiplexing element 41c and the first multiplexing element 41c, the optical fiber connected to the first multiplexing element 41c becomes the working optical fiber, and The optical fiber connected to the second multiplexing element 41d is now a spare optical fiber. as a result,
Node 31e is connected to node 31f. Further, an optical matrix switch (not shown) at the node 31f
Is operated such that the optical fiber between the node 31f and the node 31g is enabled. Then, the topology of the first optical communication network 31 is changed to 31a, 31b, 31c, 31
It is also possible to change to a topology in which each node is connected in order, such as d, 31e, 31f, 31g.

On the other hand, here, the Add / Drop unit 43 converts the optical signal of the specific wavelength λn or the optical signal of the specific packet or channel therein into the switching equipment 3.
Send to 9e side. The exchange 39e sends this optical signal to the subscriber 21e who wants to communicate. In addition, 2
When an optical signal is input from 1e to the Add / Drop unit 43 via the exchange 39e, the Add / Drop unit 43
An optical signal conforming to the multiplex system used in this optical communication system is sent to the optical matrix switch 41e. For example, in the case of wavelength multiplexing and when it is necessary to transmit an optical signal of wavelength λ3, for example, such an optical signal is added
The rop unit 43 sends the signal to the optical matrix switch 41e. The optical signal thus input is transmitted to the optical matrix switch 4
At 1e, switching is performed so as to be input to the second multiplexing element 41d in this case.

In order for the Add / Drop unit 43 to send an optical signal conforming to the multiplexing system used in this optical communication system to the optical matrix switch 41e, Add
Such a signal generator may be provided in the d-Drop section 43 or in the subscriber 21e itself. As such a signal generator, for example, in the case of wavelength multiplexing, an optical signal generator including a group of light sources (for example, semiconductor lasers) emitting various wavelengths that need to be used in wavelength multiplexing can be used. .

In the node of the second example shown in FIG. 3B, the output terminal of the optical matrix switch 41e is connected to the Add / Drop section 43 via the multiplexing element 41g.
The optical signal input from the Add / Drop unit 43 to the optical communication network is connected to the optical matrix switch 41e via the wavelength demultiplexing element 41f.

In the node of the second example, light of a plurality of wavelengths can be output to the subscriber 21e and the like, and light of a plurality of wavelengths can be output from the subscriber 21e, as compared with the first example. It can be input to an optical communication network.

In the optical communication system according to the first embodiment, since six nodes are currently available in the first optical communication network 31, the routing of each node is performed by using six types of wavelengths. it can. Also, the second optical communication network 33
In this case, each node can be routed by using five types of wavelengths. In each of the third optical communication network 35 and the fourth optical communication network 37, routing of each node can be performed by using four types of wavelengths. Moreover, each optical communication network 3
Since 1 to 37 are independent, there is no problem even if the same wavelength is used in each of the optical communication networks 31 to 37. In addition, subscribers 21
In this case, a is a total of 19 nodes of 6 nodes in the first optical communication network 31, 5 nodes in the second optical communication network 33, and 4 nodes in the fourth optical communication network 37. Can communicate with this number of nodes. However, the number of communicable nodes can be changed by changing the topology of each optical communication network.
In the example of FIG. 2, the subscriber 21a can communicate with a maximum of 4 × 7 = 28 nodes.

Also, for example, the first to fourth optical communication networks 31
-37 is changed to a topology in which seven nodes are connected in a ring, and a switch is provided for each set of nodes selected one by one from each communication network without duplication. Communication between × 7 = 49 nodes becomes possible. Even so, the wavelength multiplicity is only seven. Note that the topology can be changed here by changing the spare optical fiber to the working optical fiber by the path switching function of the node (the optical cross-connect unit 41 in this embodiment).

2. Second Embodiment In the first embodiment, an example has been described in which the path switching of the optical signal in the optical cross-connect unit 41 is performed based on the wavelength. That is, an optical signal for each wavelength is obtained by the wavelength demultiplexing elements 41a and 41b (see FIG. 3), and the optical signal for each wavelength is switched by the optical matrix switch 41e. However, the optical cross-connect unit may change the path while maintaining the wavelength multiplexed light, and the Add / Drop unit may perform signal separation (here, separation of a specific wavelength) based on an optical signal separation element determined by the multiplexing method. .
The second embodiment is an example.

FIG. 4 is an explanatory diagram of a first example of the second embodiment, and mainly shows a node portion. Also in this case, the description will be given using the node 31e as an example. Further, which optical fiber is the working optical fiber or the standby optical fiber is the same as the example in FIG.

In the node 31e of the second embodiment, the optical cross-connect section is constituted by an M × N optical matrix switch 45. Between the part of the input terminal and the part of the output terminal of the M × N optical matrix switch 45,
The Add / Drop unit 47 (details will be described later) is connected. Also, the input working optical fiber 15a and the standby optical fiber 15b are separately connected to the remaining input terminals of the optical matrix switch 45, and the output working optical fiber 15a and the standby optical fiber 15b are separately connected to the remaining output terminals. Connected to

The Add / Drop unit 47 includes a wavelength demultiplexing element 47a, a multiplexing element 47b, and a wavelength demultiplexing element 47b.
It is composed of an optical switch 47c provided between each output terminal of a and each input terminal of the multiplexing element 47b, and a light source that emits various wavelengths, for example, a semiconductor laser (not shown). The wavelength demultiplexing element 47a demultiplexes the wavelength multiplexed light input from the optical matrix switch 45. The group of optical switches 47c outputs light of a desired wavelength to the exchange 39e (and thus the subscriber 21e) and outputs the other light to the multiplexing device 4.
7b. Also, the subscriber or the like 21e is connected to the optical communication network 31.
When a signal is transmitted to the optical switch 47c, the group of optical switches 47c inputs light having a desired wavelength from light from a light source (not shown) to the multiplexing element 47b. The multiplexing element 47 b multiplexes the light input to the input terminal and outputs the multiplexed light to the optical matrix switch 45.

Therefore, the first embodiment of the second embodiment
Optical cross-connect part 45 and Add-Drop
The unit 47 can also connect the subscriber 21e and the optical communication network.

Next, a second example of the second embodiment will be described. This second example is suitable for Add / Drop when adding / dropping a wavelength-multiplexed and packet-multiplexed optical signal.
This is an example having a p-part. This description will be made mainly with reference to FIG. Here, this diagram is a diagram mainly focusing on the Add / Drop section in the optical communication system of the second example.

In the second example of the second embodiment, A
The dd / Drop unit 47 is divided into a branching unit 47d and a branching unit 47.
e, an amplification section 47f and an exchange section 47g.

The branching section 47d is connected to the optical cross-connect section 45.
(See FIG. 4) The optical signal transmitted from FIG. The splitter 47e splits one of the lights split by the splitter 47d for each wavelength. Of the light divided for each wavelength,
The optical signal requiring 1a is transmitted to the subscriber 21 via the exchange 39e.
e. The amplifying unit 47f amplifies the optical signal to recover the power of the other optical signal branched by the branching unit 47d and sends the amplified optical signal to the switching unit 47g. The switching unit 47g deletes a signal of a predetermined packet from the optical signal input thereto, and inserts a packetized optical signal that the subscriber 21e wants to transmit to the optical communication network. According to the second example, it is possible to realize an optical communication system capable of handling wavelength-multiplexed and packet-multiplexed optical signals.

The Add used in the second example is
-The Drop section is based on the patent 2509332 of the present applicant.
Therefore, further detailed description is omitted here.

Next, a third example of the second embodiment will be described. The third example is an example in which the optical fiber network portion configured by connecting the spare optical fibers 15b is also an effective and independent optical communication network. This is an example in which the utilization efficiency of the optical fiber is increased. This will be described with reference to FIG. Here, FIGS. 6A and 6B are diagrams mainly focusing on nodes in the optical communication system of the third example of the second embodiment. Also in this case, the description will be given using the node 31e as an example.

In the third example of the second embodiment, the optical cross-connect unit 45 connects the working optical fibers 15a on the input and output sides thereof and also connects the spare optical fibers 15b. . Then, in the path connecting the working optical fibers 15a and the spare optical fiber 15a.
The Add / Drop units 47 are respectively arranged in the paths connecting b with each other. The details will be described below.

For example, in the example of FIG. 6A, the optical cross-connect section is composed of two optical matrix switches, an input-side optical matrix switch 45a and an output-side optical matrix switch 45b. Then, the input-side spare optical fiber 15b and the working optical fiber 15a are connected to the input terminals of the input-side optical matrix switch 45a. Also,
The output side spare optical fiber 15b and the working optical fiber 15a are connected to the output terminals of the output side optical matrix switch 45b.
Connect. In this case, each of the optical matrix switches 45a and 45b is connected such that the input side and output side spare optical fibers 15b are connected to each other, and the input side and output side working optical fibers 15a are connected to each other. Set the route. However, each optical matrix switch 4
5A and 45b, in the path of the working optical fiber and in the path of the standby optical fiber, respectively.
A dd / Drop unit 47 is provided.

The example of FIG. 6B is an example in which two optical matrix switches 45a and 45b used in FIG. 6A are replaced with one optical matrix switch.

6A and 6B, it can be understood that the optical fiber network using the working optical fiber and the optical fiber network using the backup optical fiber are independent and effective optical communication networks. Therefore, it is understood that the utilization efficiency of the optical fiber can be improved.

[0064]

As is apparent from the above description, the optical communication system of the present invention comprises a plurality of optical communication networks, each of which comprises a plurality of nodes having a path switching function and an optical connection between them. In addition, the optical fiber network for each optical communication network includes a working optical fiber that forms a predetermined topology for each optical communication network and a spare optical fiber that contributes to the change of the topology. , Comprising a plurality of optical communication networks. Further, one end is connected to at least two optical communication networks of the plurality of optical communication networks via one node of each of the optical communication networks, and the other end is connected to a subscriber or the like. At least one switch for selectively connecting the switch to one of the at least two optical communication networks.
I have it.

For this reason, since each optical communication network is cut off by the exchange, it becomes an independent optical communication network. Therefore,
Even if, for example, optical multiplex communication using the same wavelength is performed in each optical communication network, communication becomes possible. This makes it possible to easily configure a large-scale optical communication system with a small number of multiplexes.

By changing the spare optical fiber to the working optical fiber, the topology of each optical communication network can be easily changed. Therefore, it is possible to realize an optical communication system that can flexibly respond to a change in topology.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the operation of the present invention.

FIG. 2 is an explanatory diagram of the first embodiment.

FIG. 3 is an explanatory diagram of a configuration example of a node;

FIG. 4 is an explanatory diagram of a first example of the second embodiment,
FIG. 3 is a diagram mainly focusing on nodes.

FIG. 5 is an explanatory diagram of a second example of the second embodiment;
FIG. 3 is a diagram mainly focusing on an Add / Drop unit.

FIG. 6 is an explanatory diagram of a third example of the second embodiment;
FIG. 3 is a diagram mainly focusing on nodes.

[Description of Signs] 11, 13, 31, 33, 35, 37: Optical communication networks 11a to 11d, 13a to 13d, 31a to 31g, 3
3a to 33g, 35a to 35g, 37a to 37g: Node 15a: Optical fiber (working optical fiber) 15b: Optical fiber (standby optical fiber) 17, 39a to 39g: Switch 19a to 19d: Node set 21a to 21g: Join 21x: subscriber 21y: lower communication network 41: optical cross-connect unit 41a, 41b, 41f: wavelength demultiplexing device 41c, 41d, 41g: multiplexing device 41e: optical matrix switch 43: Add / Drop unit 45: Optical cross-connect portions 45a and 45b of the second embodiment: optical matrix switches 47: Add / drop portions of the second embodiment 47a: wavelength demultiplexing devices 47b: multiplexing devices 47c: optical switches 47d: branch portions 47e: Demultiplexing unit 47f: Amplifying unit 47g: Exchange unit

Claims (8)

[Claims] 1. An optical communication system for performing communication using optical signals multiplexed by a predetermined method, comprising: a plurality of optical communication networks, each of which has a plurality of nodes having a path switching function; And the optical fiber network for each optical communication network is enabled by a working optical fiber forming a predetermined topology for each optical communication network and a path switching function of the node. And a spare optical fiber contributing to a change in topology, comprising a plurality of optical communication networks, wherein at least two of the plurality of optical communication networks have one of each of the optical communication networks. At least one switch having one end connected via a node and the other end connected to a subscriber or the like, and selectively connecting the subscriber or the like to one of the at least two optical communication networks. Optical communication system characterized by the. 2. The optical communication system according to claim 1, further comprising: an optical communication network having the same number of nodes as each of the optical communication networks; and selecting one of the switches from each of the optical communication networks. An optical communication system characterized by being connected to a node (however, when a plurality of switches are used, these switches are not connected to the same node of the same optical communication network). 3. The optical communication system according to claim 1, wherein each of the plurality of nodes is configured to switch a path of the multiplexed optical signal at the node, and an optical cross-connect unit. And an optical switch provided between the optical switches, inputting an arbitrary optical signal conforming to the multiplexing method from the subscriber or the like to the optical cross-connect unit, and determining the node in advance from among the multiplexed optical signals. Add-Drop for outputting a specific optical signal to the subscriber or the like
And an optical communication system comprising: 4. The optical communication system according to claim 3, wherein the optical cross-connect unit is an optical cross-connect unit that switches a path based on an optical signal separation element defined by the multiplexing method. Optical communication system. 5. The optical communication system according to claim 3, wherein the optical cross-connect unit includes a plurality of wavelength demultiplexing elements, a plurality of multiplexing elements, and an output terminal group of the plurality of wavelength demultiplexing elements. The input terminal group of the plurality of multiplexing elements and the Add
An optical communication system comprising an optical matrix switch for controlling a connection relationship between the Drop units. 6. The optical communication system according to claim 3, wherein the optical cross-connect unit is an M × N optical matrix switch between a part of its input terminal and a part of its output terminal. Mx to which the Add / Drop unit is connected
An optical communication system comprising N optical matrix switches (where M and N are integers of 2 or more;
Each other may be the same. ). 7. The optical communication system according to claim 1, wherein an optical fiber network portion configured by connecting the spare optical fibers is also an independent optical communication network. 8. The optical communication system according to claim 1, wherein each of the optical communication networks is a ring network or a bus network.