JP4473622B2 - Optical cross-connect system - Google Patents

Description

  The present invention relates to an optical cross connect (OXC) system for connecting networks, particularly a system having a mechanism for detecting disconnection of an optical line, and a GMPLS (Generalized MPLS (Multi-Protocol Label Switching)). The present invention relates to a suitable OXC system.

  In recent years, standardization work for GMPLS, which introduces MPLS technology to optical networks, has been promoted in the Internet Engineering Task Force (IETF), the International Telecommunication Union Telecommunication standardization sector (ITU-T), the Optical Internetworking Forum (OIF), and the like. .

  The MPLS is a technique in which an identifier called a “label” is inserted in an IP packet header, and a concept of “path”, which is a unit of a circuit on which a network operator operates a network, is incorporated into an IP network area. Yes, GMPLS intends to unify management of all networks by performing path management shared with the MPLS, TDM network (Time Division Multiplexing), WDM (Wavelength Division Multiplexing) network, and OXC network.

  Such a WDM network or OXC network managed by GMPLS does not use packet technology as in IP (Internet Protocol). For this reason, in the WDM network and the OXC network, the label information cannot be inserted into the packet header. Therefore, in the GMPLS, the WDM device and the OXC device are connected by a control link such as Ethernet (registered trademark) or optical fiber different from the optical fiber for data transmission, and the label information is exchanged on the control link. That is, the data system network and the control system network are separated. In other words, only conventional data is transmitted in the WDM path and OXC path, and no GMPLS data flows. The WDM path information (wavelength information) and OXC path information (port number information) are labels in the IP packet header. Insert into the value field. In this way, in the GMPLS network, topology information in the WDM network and the OXC network can also be collected from the router.

  In this background, the present invention particularly refers to an optical line break detection mechanism for detecting an “optical line break” in an OXC network. When this disconnection of the optical line is detected, a route switching operation for detouring the location of the optical line disconnection is performed with reference to the topology information and the like.

The following [Patent Document 1] to [Patent Document 6] are known techniques related to the present invention. However, none of these known techniques disclose or suggest the “detection of optical line disconnection using monitor light”, which is the idea of the present invention.
Japanese Patent Laid-Open No. 4-120916 Japanese Patent Laid-Open No. 11-275014 Japanese Patent Laid-Open No. 2001-258084 JP 2003-134154 A JP 2003-195244 A JP 2003-298633 A

  First, a general optical cross connect (OXC) system will be described with reference to the drawings.

  FIG. 28 is a diagram showing a basic configuration of a general OXC system.

  In this figure, reference numeral 10 represents an optical cross-connect system (hereinafter also referred to as an OXC system), and the core thereof is an optical cross-connect section (hereinafter also referred to as an OXC section) 11. The OXC unit 11 is usually provided with more than 100 ports 12, for example. However, for the sake of simplicity, the figure shows eight ports 12, that is, Port1 to Port8.

  Each port 12 is provided with an optical transmission / reception unit (OS / OR) 13 that transmits and receives an optical main signal. OS represents Optical Sender, and OR represents Optical Receiver. In the figure, “OS1 / OR1” to “OS8 / OR8” are shown.

  Input light to a certain port 12 is transferred as output light from another predetermined port 12 and travels to another station. The switching of a path from one input port to another output port at this time is set by a predetermined path switching management table. This table is the wavelength switch / forwarding table 14 shown in the lower part of the figure. Examples of the above-described path switching in the OXC system 10 having such a basic configuration are as shown in FIGS. Note that the above-mentioned situation differs between “when a unidirectional connection is requested” and “when a bidirectional connection is requested”.

FIG. 29 is a diagram illustrating the state of FIG. 28 at the time of unidirectional connection,
FIG. 30 is a diagram illustrating the state of FIG. 28 during bidirectional connection. Note that the same reference numerals or symbols are given to the same components throughout the drawings.

  Referring to FIG. 29, an optical main signal (wavelength λ1) from a certain station (X) is input to the optical transmission / reception unit (OR1) 13 of the port 12 (Port 1), and according to the wavelength switch / forwarding table 14 of this figure, The signal is transmitted from the optical transmission / reception unit (OS6) 13 of the port 12 (Port 6) to the other station (Y) as an optical main signal of wavelength λ6.

  Under the unidirectional connection shown in the figure, the transmission route and the reception route are allowed to take different routes in the communication between the two stations (XY).

  On the other hand, referring to FIG. 30, the transmission / optical main signal (λ1) from a certain station (X) and the reception / optical main signal (λ1) to the station (X) are respectively connected to OR1 and OS1 of the optical transceiver 13. Through the port (Port 1) 12 of the optical cross-connect unit 11. On the other hand, the reception / optical main signal (λ6) from the other station (Y) communicating with a certain station (X) and the transmission / optical main signal (λ6) to the station (Y) are transmitted / received respectively. It enters and exits at the port (Port 6) 12 of the optical cross-connect unit 11 through the OR 1 and OS 1 of the unit 13. The path setting between the two ports (Port 1 to Port 6) is performed in accordance with the wavelength switch / forwarding table 14 in the lower part of the figure.

  Under the bidirectional connection shown in FIG. 30, in the communication between the two stations (XY), the transmission route and the reception route must take exactly the same route. Therefore, comparing the unidirectional connection type shown in FIG. 29 with the bidirectional connection type shown in FIG. 30, the latter bidirectional connection type requires much simpler management for the operation of the OXC network. There are advantages. The OXC system of the present invention, which will be described later, can be suitably used for bidirectional connection type having such advantages, that is, bidirectional transmission communication of light.

  Furthermore, the present invention is suitably used not for an OXC system using a two-core optical fiber as shown in FIG. 30, but for an OXC system using a single-core optical fiber (described later). That is, it is preferably used when mutual transmission communication is performed between the opposing stations and the OXC system 10 by using one optical fiber for each port using the optical main signal.

  Comparing the above-described mutual transmission communication using one optical fiber and the above-described mutual transmission communication using two optical fibers, the former one optical fiber is more advantageous in terms of operation and cost of the OXC network. Is also advantageous from the probability of an optical line break.

  However, from the viewpoint of “detection of disconnection of the optical line”, the OXC system 10 linked to the single-core optical fiber may be disadvantageous than the OXC system 10 linked to the two-core optical fiber. I will explain this in more detail.

  Suppose now that the single-core optical fiber is broken somewhere. Then, since the input light is cut off on the OR side of the optical transmission / reception unit 13, the disconnection can be immediately detected and an alarm can be issued. This is a disconnection detection method based on “Loss of Light” (LOL). In the OXC system compatible with GMPLS, only detection of an optical line disconnection using this LOL is clearly defined. That is, at present, there is only an optical line disconnection detection method using this LOL.

  However, it has been found that the detection of an optical line break by the LOL detection method is not perfect. The reason is that when one optical fiber is disconnected, the optical main signal from the other party is disconnected, and the LOL is detected by the OR of the optical transmission / reception unit 13, and the disconnection detection is originally intended. Nevertheless, there is a case where such a LOL is not actually detected. Considering the case where LOL is not detected in this way, the cause is not the optical main signal from the other party, but the optical main signal transmitted by the OS of the optical transceiver 13 to the one optical fiber by itself. Turned out to be. I will explain this in more detail.

  In general, a phenomenon of light reflection can occur in the disconnected portion of the optical fiber. This is because the broken part works like a mirror. Then, the optical main signal sent by the OS of the optical transmission / reception unit 13 to the optical fiber is reflected by the mirror at the disconnected portion and returned to the OR of the optical transmission / reception unit 13. As a result, the OR receives the return light of the optical main signal transmitted by the OS paired therewith, that is, the return optical main signal, so that the LOL cannot be detected. As described above, according to the current optical line break detection method using the LOL detection defined in the GMPLS-compliant OXC system, it is impossible to completely detect all the optical line breaks generated on one optical fiber. There is a problem. Therefore, there is a situation in which no alarm is generated from the OXC system 10 even though two stations facing each other across the OXC system 10 cannot actually communicate with each other. .

  Therefore, an object of the present invention is to provide an OXC system that can prevent the original LOL detection from being hindered by the return light from the disconnected portion of the optical main signal transmitted by itself.

  FIG. 1 is a diagram showing a basic configuration of an OXC system according to the present invention.

  In this figure, the constituent elements characterizing the present invention are an optical coupler unit 20, a monitor light transmission unit 21, and a disconnection determination unit 22, which cooperate with the optical cross-connect unit (OXC unit) 11 described above. Thus, an optical cross-connect system (OXC system) 10 that can reliably detect an optical line break is constructed.

As shown in the figure, this OXC system 10
(A) an OXC unit 11 having a plurality of ports 12; (b) a combination of optical main signals S provided for each port 12 and bidirectionally transmitted between the single optical fiber 15 and the port 12; An optical coupler unit 20 that performs wave division and demultiplexing; and (c) an optical monitor signal that is combined with the optical main signal S and transmitted to the optical fiber 15 in the optical coupler unit 20, and the wavelength of the optical main signal S And (d) an optical signal from the optical fiber 15 is received through the optical coupler unit 20, and the received optical signal is included in the received optical signal. And a disconnection determining means 22 that determines that an optical line disconnection has occurred on the optical fiber 15 when the return light monitor signal M ′ is detected.

  Here, the return light monitor signal M ′ is a signal returned when the light monitor signal M is reflected at the disconnection portion of the optical fiber 15 described above. Accordingly, a return signal of the optical main signal S is also generated at the same time, which is indicated by S ′ in the figure.

  In this case, due to the return optical main signal S ′, the port 12 is erroneously recognized as receiving the optical main signal S from the other station even though the optical line is disconnected at the port 12. Originally, the LOL should be detected and an alarm should be generated, but such an alarm is not issued (described above).

  Therefore, the present invention combines the optical monitor signal M with the optical main signal S and sends it to the single optical fiber 15. In this case, it is important that the wavelength (λm) of the optical monitor signal M is different from the wavelength (λs) of the optical main signal S. Then, means for detecting the return light M ′ of the optical monitor signal M caused by the disconnection of the optical line using the specific wavelength λm as a clue is provided at the port. In FIG. 1, the disconnection determination means 22 corresponds to that.

  Then, even if the LOL detection unit originally in the port cannot detect the LOL by the return light main signal S ′, the return light monitor signal M ′ is detected by the disconnection determination means 22 (detection of λm). As a result, it is possible to detect the disconnection of the optical line. In addition, the optical line break can be detected by detecting the return light main signal S ′ by the break judging means 22 without detecting the optical monitor signal M (detection of λs). At first glance, it can be considered. However, the break detection by the return light main signal S ′ cannot actually be performed. This is because the original optical main signal S reaches not only the optical fiber 15 but also the disconnection determination means 22 by the wraparound in the optical coupler unit 20, and the return optical main signal S 'is always received by the means 22. Because it ends up. That is, the means 22 is always in an optical line disconnection detection state and keeps issuing an alarm even though the optical line disconnection has not actually occurred. This is why the optical monitor signal M having a wavelength different from that of the optical main signal S is introduced.

  Thus, when the disconnection determination means 22 determines that an optical line disconnection has occurred through the optical monitor signal M, the GMPLS-compliant OXC system 10 provides information on the occurrence of the optical line disconnection or the optical line disconnection. The corresponding port information generated is sent to the GMPLS control network.

  That is, the present invention is characterized in that, when the disconnection determination means 22 determines that an optical line disconnection has occurred, the optical line disconnection information is transmitted to the GMPLS control network under which the optical cross-connect system 10 is subordinate. To do. Here, the GMPLS control network will be briefly described.

  FIG. 2 is a diagram showing a general hierarchical structure of the GMPLS network.

  In this figure, reference numeral 17 represents the above-described data system NW (network), in which the OXC system 10 as the object of the present invention is arranged. This also includes a packet switch (SW) and the like.

  The above-described control system NW (network) 16 placed at the higher level collectively manages the entire data system network 17 in common. The “GMPLS control network” shown in FIG. 1 refers to this control system network 16.

  According to the OXC system 10 of FIG. 1, the optical fiber cost is greatly reduced by first applying the single-core optical fiber type. However, due to the application of the single-core optical fiber type, the reliability of the LOL detection is lower than that of the double-core optical fiber type with respect to the LOL detection due to the return light main signal S ′ when the optical line is disconnected. Resulting in.

  Therefore, by introducing the optical monitor signal M according to the present invention, the optical fiber cost is greatly reduced (halved) while ensuring the reliability of LOL detection almost equal to that of the two-core optical fiber type (FIGS. 28 to 30). Can be realized at the same time. In order to realize this, the present invention provides Examples 1 to 5 described later.

  (1) In Example 1 (FIG. 3), the light emission part (31) and light-receiving part (32) of monitor light, and an optical switch (33) are employ | adopted. The advantage is that it is possible to specify the port number of the port connected to the optical fiber 15 causing the optical line disconnection and notify the GMPLS control network (16).

  (2) In the second embodiment (FIG. 7), a monitoring optical coupler (43) is employed instead of the optical switch (33) in the first embodiment. In this case, since an optical coupler is used instead of an expensive optical switch, there is an advantage that the cost is reduced.

  (3) In the third embodiment (FIG. 11), any one of the optical main signals input to the OXC system 10 is used as the optical monitor signal M, so that the light emitting unit (31) of the first embodiment is unnecessary. Become cheaper. However, in place of the light receiving unit (32) of the first embodiment, it is necessary to adopt a wavelength analyzing unit (54) such as a spectrum analyzer. However, such a spectrum analyzer is originally built in the OXC system 10 in recent years. If this is used, it can be realized at a lower cost.

  (4) In the fourth embodiment (FIG. 15), since the optical switch (53) employed in the third embodiment is integrated into the OXC unit 11, it can be realized smaller and cheaper than the third embodiment. .

  (5) In Example 5 (FIG. 19), in place of the optical switch and the optical coupler employed in the above example, an optical wavelength tunable filter (73) whose use has begun to attract attention in recent years is used. . Thereby, modularization of the optical line disconnection detection mechanism can be realized.

FIG. 3 is a diagram showing the overall configuration of the OXC system based on the first embodiment of the present invention.
FIG. 4 is a diagram illustrating the signal flow in FIG.
FIG. 5 is a diagram showing an example of the table 14 that defines the signal flow in FIG.

Referring first to FIG. 3, the monitor light sending means 21 of FIG. 1 includes a monitor light generation unit 31 that generates an optical monitor signal M and sends it to the optical coupler unit 20 corresponding to each port 12. The disconnection determination means 22 in FIG.
A monitor light detection unit 32 that receives the optical signal from the optical coupler unit 20 and detects the presence or absence of the return light monitor signal M ′;
An optical switch 33 that switches a path of light to be formed between the optical coupler unit 20 corresponding to each port 12, the monitor light generation unit 31, and the monitor light detection unit 32;
A controller 34 that sequentially switches the light path in the optical switch 33 and determines the presence or absence of the return light monitor signal M ′ for each port 12 in cooperation with the monitor light detector 32;
Consists of.

  In the present invention, an “ODC” (Optical Directional Coupler) is used as an example of the optical coupler unit 20 as shown in the figure.

  In the first embodiment, the optical switch 33 includes two light input / output terminals respectively assigned to the monitor light generation unit 31 and the monitor light detection unit 32, and n (n is 2 or more) corresponding to each port 12. It is a 2: n-type optical switch comprising n (n = 8) optical input / output terminals respectively assigned to an integer, n = 8 in the example shown in the figure.

  Next, referring to FIGS. 4 and 5, the optical main signal input from the optical fiber 15 to the optical coupler unit 20 of the port 12 (Port 6) passes through the OR 6 of the optical transmission / reception unit 13 and is further routed according to the table 14-1 of FIG. Through the set OXC unit 11, the port 12 (Port 1) is reached, where it is sent to the optical fiber 15 again through the OS 1 of the optical transceiver 13 and the optical coupler unit 20. Similarly, the optical main signal input from the optical fiber 15 to the optical coupler unit 20 of the port 12 (Port 1) passes through the OR 1 of the optical transceiver unit 13 and further passes through the OXC unit 11 routed according to the table 14-1 of FIG. Then, it reaches the port 12 (Port 6), where it is sent to the optical fiber 15 again through the OS 6 of the optical transceiver 13 and the optical coupler unit 20. The above is the same for other ports, and normal path switching of the OXC system 10 is performed as described above.

  The present invention provides an optical line break detection mechanism comprising the above-described monitor light sending means 21 and a break determination means 22 including a control unit 34 for detecting an optical line break in parallel with the normal operation described above. The control unit 34 provides and controls the control. Therefore, an operation flow of the control unit 34 will be described.

  FIG. 6 is a flowchart showing an operation example of the control unit 34 shown in FIGS.

  Step S11: The control unit 34 periodically switches the optical switch (2: n-type optical switch) 33 to sequentially access the port 12 from Port 1 to Port 8 in order, and each port, the optical monitor signal M and the monitor light detection unit ( ORx) 32 and a light path are formed.

  Step S12: The controller 34 determines whether or not the monitor light detector (ORx) 32 has returned and detected monitor light (λx).

  Step S13: If the determination result is Yes, the control unit 34 checks the port number (Port 1 to Port 8) of the detection port 12.

  Step S14: The control unit 34 further notifies the GMPLS control network (NW) 16 shown in FIG. 2 of the checked port number.

  The operation model of the first embodiment described above with reference to FIGS. 3 to 6 is shown below. This behavior model assumes the case of FIG.

  The ODC (20) is a “3: 1” ODC, which is an optical coupler having three optical input / output terminals inside the station and one optical input / output terminal outside the station. The signal is multiplexed to the “1” input / output terminal, and the optical signal at the “1” input / output terminal is demultiplexed to the “3” input / output terminal. For convenience of explanation, the left side of the OXC system 10 shown in FIG. 4 is called the West side, and the right side is called the East side.

  First, the flow of the optical signal input from the East side to the Port 6 direction of the port 12 is first input to the outside of the station of the “3: 1” ODC (20) and demultiplexed to the “3” input / output terminal inside the station. Is done. The demultiplexed wave is input to the OR 6 of the optical transmission / reception unit, switched to Port 1 (λ 1) according to the GMPLS wavelength switch / forwarding table 14, and further input to OS 1 in the optical transmission / reception unit of Port 1 (λ 1). When the signal is input inside the station side of the “3: 1” ODC (20) on the West side, it is multiplexed at the “1” input / output terminal outside the station, and is output from the West side as the optical main signal (λ1) S. . At this time, the optical monitor signal M for detecting the disconnection of the optical line is sent from the monitor light generation unit (OSx) 31 via the monitor light 2: n optical switch (SW) 33 to each “3: 1” ODC ( 20) is input to the “1” input / output terminal inside the station, and further transmitted along with the optical main signal (λ1) S to the outside of the station.

  The remaining two waves demultiplexed at the above-described Port 6 are input to the OS 6 and the monitor light 2: n light SW 33, respectively, but since the optical signal input to the OS 6 side is noise, the optical isolator built in the OS 6 Etc. are removed.

  Now, assume that an optical line break occurs. In this case, the optical main signal (λ1) S and the optical monitor signal M are turned back to the local station side from the cut section of the cable forming the optical fiber 15 by the above-described mirror. At this time, since the return light main signal (λ1) S ′ is input to Port1 (λ1), LOL cannot be detected when the light level is high. In other words, the disconnection of the optical line cannot be detected. However, since the return light monitor signal (λx) M ′ is input to the monitor light detection unit (ORx) 32, when the monitor light M ′ is detected by this ORx, it can be determined that the optical line is disconnected. it can.

  Therefore, the control unit 34 searches for the output port (12) in use from the wavelength switch / forwarding table 14 of the GMPLS control network 16, and determines the port 12 to which the monitor light M ′ is returned by the optical SW 33. Then, the GMPLS control network 16 is notified of the port number where the optical line break has occurred, and route switching processing or the like is performed.

  Since the entire embodiment 1 can be grasped by the description of the above operation model, finally, specific examples of a few constituent elements characteristic of the embodiment 1 are shown in the drawings.

FIG. 23 is a diagram showing a specific example of the optical coupler unit (ODC) 20 in FIG.
FIG. 24 is a diagram showing a specific example of the optical switch 33 of FIG.
FIG. 25 is a diagram showing a detailed example of one unit in FIG.

  Referring first to FIG. 23, the optical coupler unit 20 in this figure shows the ODC (20) at the uppermost left end in FIG. However, the other ODC (20) has the same configuration.

  In this figure, the end face of the optical waveguide 110 is joined to the end face of the optical fiber 15, the end face of the optical waveguide 111 is an end face subjected to antireflection treatment, and the end face of the optical waveguide 112 is joined to the OS 1 side of the optical transmission / reception unit 13. The end face of the optical waveguide 113 is joined to the OR1 side of the optical transmission / reception unit 13, and the end face of the optical waveguide 114 transmits and receives monitor light (M / M ′) to and from the optical switch 33. Is an end face subjected to antireflection treatment.

  Next, referring to FIG. 24, the optical switch 33 in FIG. 3 is composed of a total of 14 1 × 2 optical switches (121, 122, 123, etc.), with 1 × 2 optical switch as a unit.

  The 1 × 2 optical switches 121 and 122 at the left end are coupled to the monitor light generation unit 31 and the monitor light detection unit 32, respectively, while the four 1 × 2 optical switches 123 at the right end have eight ports (Port 1 to Port 1). Port 8). The light input from the 1 × 2 optical switch 121 is output from any one of the rightmost 1 × 2 optical switches 123 to any one of Port 1 to Port 8 by electrically controlling the corresponding 1 × 2 optical switch. The

  Conversely, the light input from these Port 1 to Port 8 is output from the leftmost 1 × 2 optical switch 122 by electrically controlling the corresponding 1 × 2 optical switch.

  Referring to FIG. 25, each of the above 1 × 2 optical switches is configured as shown in the figure, for example, and is electrically controlled by the control unit 34 in FIG. 3 to control the light path. In the waveguide type optical switch as shown in this figure, the electro-optic switch 130 applies a voltage to the optical coupling portion by forming the coupling length of the optical coupling portions 136 and 137 and the waveguide interval to a predetermined size. If not, the optical power shifts from the first waveguide 131 to the second waveguide 132 by 100%. Further, when an electric switch (not shown) is turned on by the control unit 34 and a voltage is applied to the optical coupling unit, the optical power transferred to the second optical waveguide 132 is transferred to the first optical waveguide 131 again. The sub-waveguide 133 travels. In the figure, 134 is a drive electrode (drive voltage V), and 135 is a ground electrode (voltage E).

FIG. 7 is a diagram showing an overall configuration of an OXC system based on the second embodiment of the present invention.
FIG. 8 is a diagram illustrating the signal flow in FIG.
FIG. 9 is a diagram showing an example of the table 14 that defines the signal flow in FIG.

Referring first to FIG. 7, the monitor light sending means 21 in FIG. 1 generates an optical monitor signal M and sends it to the optical coupler unit 20 corresponding to each port 12, as in FIG. 3 (Example 1). 1 and the disconnection judging means 22 in FIG.
A monitor light detection unit 32 that receives the optical signal from the optical coupler unit 20 and detects the presence or absence of the return light monitor signal M ′;
A monitoring optical coupler 43 that forms a light branch path between the optical coupler unit 20 corresponding to each port 12, a monitor light generation unit 31, and a monitor light detection unit 32;
A control unit 34 for determining the presence or absence of a return light monitor signal M ′ from the monitoring optical coupler 43 in cooperation with the monitor light detection unit 32;
Consists of.

  In the second embodiment, the monitoring optical coupler 43 includes two light input / output terminals respectively assigned to the monitor light generator 31 and the monitor light detector 32, and n (n is 2) corresponding to each port 12. This is a 2: n-type optical directional coupler comprising the above integers, n (n = 8 in the example shown in the figure), n (n = 8) optical input / output terminals respectively assigned to the optical coupler units 20.

  Next, referring to FIGS. 8 and 9, the normal path switching of the OXC system 10 is performed in the same manner as in the first embodiment (FIGS. 4 and 5). On the other hand, the optical line break detection mechanism according to the second embodiment is different from the first embodiment in that the monitoring optical coupler 43 is used.

  That is, in the second embodiment, a “3: 1” ODC (20) is installed in each port 12 of the OXC unit 11, and “2: n” (n = 8) ODC (43) is transmitted to the transmitted light therefrom. The monitor light (OSx, λx) (M) is multiplexed via the via. When the optical line is disconnected, the monitor light is input through a route of “3: 1” ODC (20) → “2: n” ODC (43) → ORx (32). When the return monitor light (λx) M ′ is detected, the optical line disconnection is notified to the GMPLS control network 16, and the optical line disconnection port is determined by comparing with the information of the adjacent station. Such a series of operations is controlled by the control unit 34. Therefore, an operation flow of the control unit 34 will be described.

  FIG. 10 is a flowchart illustrating an operation example of the control unit 34 illustrated in FIGS. 7 and 8.

  Step S <b> 21: The controller 34 determines whether or not the return monitor light (λx), that is, the return light monitor signal M ′ is detected by the monitor light detector (ORx) 32.

  Step S22: If the determination result is Yes, it means that an optical line break has been detected, and the control unit 34 notifies the GMPLS control network (NW) 16 of this.

  Step S23: The control unit 34 checks the state of the station adjacent to the OXC system 10 through the GMPLS control network 16 and checks it.

  Step S24: The control unit 34 checks whether or not the optical line disconnection is detected in the adjacent station by the above check.

  Step S25: If the optical line disconnection is detected (Yes) in Step S24, it is determined that the optical line 15 connected to the port 12 connected to the adjacent station has an optical line disconnection. The route is switched.

  The specific configuration of the monitoring optical coupler (2: n-type optical directional coupler) 43 that is characteristic of the second embodiment is the same as that of FIG. Further increased configuration.

FIG. 11 is a diagram showing an overall configuration of an OXC system based on the third embodiment of the present invention.
FIG. 12 is a diagram illustrating the signal flow in FIG.
FIG. 13 is a diagram showing an example of the table 14 that defines the signal flow in FIG.

First, referring to FIG. 11, the monitor light sending means 21 of FIG. 1 is configured as follows in the third embodiment. That is, the input is made from a second port (for example, Port 6) 12 different from the first port (for example, Port 1) 12 that outputs the first optical main signal S1 and is a port of interest for detection of an optical line break. The second optical main signal S2 having a wavelength different from that of the first optical main signal S1 is used as the above-described optical monitor signal M, and the optical coupler unit 20 corresponding to the first port (Port1) via the OXC unit 11 is used. Thus, the first optical main signal S1 is combined. Further, the disconnection judging means 22 in FIG.
A wavelength analysis unit 54 that receives the optical signal from the optical coupler unit 20 and detects the presence or absence of the return optical monitor signal M ′;
An optical switch 53 for switching a light path to be formed between the optical coupler unit 20 corresponding to each port 12 and the wavelength analysis unit 54;
A control unit 34 that sequentially switches the light path in the optical switch 53 and determines the presence or absence of a return light monitor signal M ′ for each port 12 in cooperation with the wavelength analysis unit 54;
Consists of.

  Specifically, the optical switch 53 includes one optical input terminal assigned to the wavelength analyzing unit 54 and n corresponding to each port 12 (n is an integer of 2 or more, n = 8 in the example in the figure). The n-type optical switch (SW) includes n (n = 8) light input / output terminals respectively assigned to the optical coupler units 20.

  Thus, the control unit 34 manages the wavelengths of the optical main signals (S1, S2,...) Assigned to each port 12, and the optical signal detected by the wavelength analysis unit 54 corresponds to the return light monitor signal M ′. Identify whether or not to do so. If applicable, it can be determined that the optical fiber 15 connected to the port is disconnected.

  The wavelength analyzing unit 54 is shown as “sparener” (spectrum analyzer) in the drawing.

  Next, referring to FIG. 12 and FIG. 13, the normal path switching of the OXC system 10 is performed in the same manner as in the first embodiment (FIGS. 4 and 5). On the other hand, the optical line break detection mechanism according to the third embodiment is different from the first embodiment in that the optical switch 53 and the wavelength analyzing unit (sparener) 54 are used.

  That is, in the third embodiment, a “4: 1” ODC 20 is installed in each optical port 12 of the OXC unit 11 and another wavelength light of another port 12 is used as monitor light (M ′). The optical main signal S6 on the OR6 side in the port 12 (Port 6) input to the optical switch 53 as the main signal light from the East side is switched to the two ports of the OS1 side and the monitor light port (for example, the above [Patent Document] 3] Point-to-Multipoint optical path switching unit). As a result, the optical signal of wavelength λ1 that is the optical main signal S1 and the optical signal of wavelength λ6 that is the optical monitor signal M are combined and output to the West side. The “1: n” optical switch 53 periodically switches each port 12, and the spectrum analyzer 54 determines which port 12 the monitor light is returned to and notifies the GMPLS control network 16. Such a series of operations is controlled by the control unit 34. Therefore, an operation flow of the control unit 34 will be described.

  FIG. 14 is a flowchart illustrating an operation example of the control unit 34 illustrated in FIGS. 11 and 12.

  Step S31: The controller 34 determines in advance which other port's optical signal each port 12 uses as the monitor light (M), and manages it.

  Step S32: The control unit 34 periodically and sequentially switches each optical input / output end of the 1: n type optical switch (SW) 53, and the wavelength of the optical signal detected by the wavelength analyzing unit (sparener) 54 and each port. The monitor light (M) wavelength determined every 12 is collated.

  Step S33: It is determined whether or not the collation result indicates that a predetermined monitor light has been detected for the port 12 of interest.

  Step S34: If the determination result is Yes, the port number of the port that detected the monitor light is checked.

  Step S35: The control unit 34 notifies the GMPLS control NW 16 that an optical line break has occurred in one port 12 corresponding to the checked port number.

  A specific example of the optical switch (1: n type optical switch) 53 characteristic of the third embodiment is shown in the drawing.

  FIG. 26 is a diagram showing a specific example of the optical switch 53 of FIG. This figure corresponds to the configuration of FIG. 24 described above, which is a total of seven 1 × 2 optical switches, and the description of FIG. 24 and FIG. 25 is applied as it is.

FIG. 15 is a diagram showing an overall configuration of an OXC system based on the fourth embodiment of the present invention.
FIG. 16 is a diagram illustrating the signal flow in FIG.
FIG. 17 is a diagram showing an example of the table 14 defining the signal flow in FIG.

First, referring to FIG. 15, the monitor light sending means 21 of FIG. 1 is configured as follows, as in the third embodiment. That is, the input is made from a second port (for example, Port 6) 12 different from the first port (for example, Port 1) 12 that outputs the first optical main signal S1 and is a port of interest for detection of an optical line break. In the optical coupler unit 20 corresponding to the first port (Port 1) via the OXC unit 11, the second optical main signal S2 having a wavelength different from that of the first optical main signal S1 is used as the optical monitor signal M. The optical main signal S1 is combined with the first optical main signal S1. On the other hand, the disconnection determination means 22 in FIG.
In the OXC unit 11, a monitor path unit 63 (FIG. 16) that receives an optical signal from the optical coupler unit 20 and routes it to a further monitoring port 64;
A wavelength analysis unit 54 that receives the optical signal from the optical coupler unit 20 output from the monitor port 64 and detects the presence or absence of the return optical monitor signal M ′;
The controller 34 sequentially switches the light path between the monitoring port 64 and each port 12 of the OXC unit 11 and determines the presence or absence of the return light monitor signal M ′ for each port 12 in cooperation with the wavelength analyzer 54. When,
Consists of.

  Thus, the control unit 34 manages the wavelengths of the optical main signals (S1, S2,...) Assigned to each port 12, and the optical signal detected by the wavelength analysis unit 54 corresponds to the return light monitor signal M ′. Identify whether or not to do so. If applicable, it can be determined that the optical fiber 15 connected to the port is disconnected.

  Next, referring to FIGS. 16 and 17, the normal path switching of the OXC system 10 is performed in the same manner as in the first embodiment (FIGS. 4 and 5). On the other hand, the optical line disconnection detection mechanism under the fourth embodiment is different from the third embodiment in that the monitor port 64 newly provided in the OXC unit 11 is used.

  That is, in the fourth embodiment, the function of the 1: n type optical switch 53 provided outside in the third embodiment is provided inside the OXC unit 11. The OXC unit 11 includes a monitor port 62 used as monitor light and a spectrum analyzer port 64. When all the ports 62 used as monitor light are periodically switched to the monitor port 64 one by one and the monitor light is returned at each port 12, it is determined that an optical line break has occurred at that port. , Contact the GMPLS control network 16.

  Here, the reason why each monitor light port must be viewed one by one is that, for example, in FIG. 16, assuming that the Port 1 side and the Port 6 side that use the monitor port 64 in common use the port 64 at the same time, East This is because the main signal light (λ6) S2 from the side is also detected by the wavelength analyzing unit (sparener) 54, and it cannot be determined whether the optical line on the Port 1 side is disconnected or the optical line on the Port 6 side is disconnected.

  The series of operations described above is controlled by the control unit 34. Therefore, an operation flow of the control unit 34 will be described.

  FIG. 18 is a flowchart showing an operation example of the control unit 34 shown in FIGS. 15 and 6.

  Step S41: Same as step 31 in FIG. 14 (Example 3).

  Step S42: Corresponds to step S32 of FIG. 14, but the third embodiment and the fourth embodiment are greatly different in this step S42. That is, in this step S42, the monitoring port 62 of each port (Port 1 to Port 8) is sequentially and periodically switched to the common monitoring port 64 connected to the wavelength analysis unit (spare) 54. Then, the wavelength of the optical signal detected by the spectrum analyzer (54) is compared with the wavelength of the monitor light (M) determined in advance for each port 12. The subsequent operation is the same as in FIG. 14 (Example 3).

  Step S43: Same as step S33 in FIG.

  Step S44: Same as step S34 in FIG.

  Step S45: Same as step S35 in FIG.

FIG. 19 is a diagram showing an overall configuration of an OXC system based on the fifth embodiment of the present invention.
FIG. 20 is a diagram illustrating the signal flow in FIG.
FIG. 21 is a diagram showing an example of the table 14 defining the signal flow in FIG.

First, referring to FIG. 19, the monitor light transmitting means 21 of FIG. 1 is configured as follows, as in FIG. 11 (Example 3). That is, the input is made from a second port (for example, Port 6) 12 different from the first port (for example, Port 1) 12 that outputs the first optical main signal S1 and is a port of interest for detection of an optical line break. In the optical coupler unit 20 corresponding to the first port (Port 1) via the OXC unit 11, the second optical main signal S2 having a wavelength different from that of the first optical main signal S1 is used as the optical monitor signal M. The optical main signal S1 is combined with the first optical main signal S1. On the other hand, the disconnection determination means 22 in FIG.
A monitor light detection unit (ORx) 32 that receives the optical signal from the optical coupler unit 20 and detects the presence or absence of the return light monitor signal M;
An optical wavelength tunable filter 73 that is provided between the optical coupler unit 20 corresponding to each port 12 and the monitor light detection unit 32 and has a variable pass wavelength;
The control unit 34 that sequentially switches the pass wavelength in the optical wavelength tunable filter 73 corresponding to each port 12 and determines the presence or absence of the return optical monitor signal M ′ for each port 12 in cooperation with the monitor light detection unit 32;
Consists of.

  More specifically, the optical wavelength tunable filter 73 is composed of a first optical wavelength tunable filter 73-1 and a second optical wavelength tunable filter 73-2, as shown in FIG. The optical wavelength tunable filter 73-1 cooperates only with, for example, the first port group (Port 1 to Port 4) on the West side set as the first port, and the second optical wavelength tunable filter 73-2 is configured as described above. For example, it is divided into two so as to cooperate only with the second port group (Port 5 to Port 8) on the East side set as the second port. The reason for dividing into two in this way is that if the optical signals on the West side and the East side are merged by a single optical wavelength variable filter, the two cannot be distinguished from each other.

  Thus, the control unit 34 manages the wavelength of the optical main signal S allocated to each port 12 and determines whether the optical signal detected by the monitor light detection unit 32 corresponds to the return light monitor signal M ′. Identify. If applicable, it can be determined that the optical fiber 15 connected to the port is disconnected.

  Next, referring to FIG. 20 and FIG. 21, the normal path switching of the OXC system 10 is performed in the same manner as in the first embodiment (FIGS. 4 and 5). On the other hand, the optical line break detection mechanism according to the fifth embodiment is different from the previous embodiments in that the optical wavelength variable filter 73 is used. The optical wavelength tunable filter 73 is known as an acousto-optic tunable filter (AOTF) in, for example, the aforementioned [Patent Document 5], and one configuration example thereof is shown in FIG. 27 described later. By using such AOTF, a wavelength analysis function equivalent to the case of using the spectrum analyzer (54) described above can be exhibited.

  Next, the controller 34 in the fifth embodiment will be described with reference to the drawings.

  FIG. 22 is a flowchart showing an operation example of the control unit 34 shown in FIGS. 19 and 20.

  Step S51: Corresponds to step S31 of FIG. 14 (Embodiment 3), but in Embodiment 5, the wavelength of the monitor light is managed by the control unit 34 separately in the West direction and the East direction (FIG. 20). See OATF (W) 73-1 and OATF (E) 73-2).

  Step S52: The control unit 34 controls the OATFs 73-1 and 73-2 so that the monitor light of each port 12 is sequentially drawn into the monitor light detection unit (ORx) 32 periodically. When the optical signal is output by ORx (32), the monitor light (M ′) is detected.

  Step S53: Same as step S33 in FIG.

  Step S54: Same as step S34 in FIG.

  Step S55: Same as step S35 in FIG.

  Finally, a specific example of AOTF (73-1, 73-2) shown in FIG. 20 will be described with reference to FIG.

  An AOTF shown in FIG. 27 is an optical element that uses the acoustooptic effect, and selects a wavelength by using mode conversion based on the interaction between SAW (Surface Acoustic Wave) and light. SAW is generated by applying an RF (Radio Frequency) signal to an IDT (Inter Digit Transducer). By changing the frequency of the RF signal, the wavelength of light for mode conversion is changed. Can do. Further, by applying a plurality of RF signals having different frequencies and applying them to the IDT to generate a plurality of SAWs having different wavelengths, it is possible to mode-convert light having a plurality of frequencies having different wavelengths. Since light having a wavelength that has undergone mode conversion by SAW and light having a wavelength that has not been mode-converted can be separated by a polarization separation element, an optical waveguide and a SAW waveguide are provided on a substrate that produces an acoustooptic effect. By providing them so as to interact with each other and combining them with a polarization separation element, it is possible to configure an AOTF in which a plurality of wavelengths can be selected and the selection wavelengths are variable.

The embodiment of the present invention described in detail above is as follows.
(Appendix 1)
An optical cross-connect unit having a plurality of ports;
An optical coupler unit that is provided for each of the ports and performs multiplexing and demultiplexing of an optical main signal bidirectionally transmitted between the single optical fiber and the port;
Monitor light transmission means for transmitting the optical monitor signal having a wavelength different from the wavelength of the optical main signal, the optical monitor signal being combined with the optical main signal and transmitted to the optical fiber in the optical coupler unit When,
A disconnection determination that determines that an optical line disconnection has occurred on the optical fiber when an optical signal from the optical fiber is received via the optical coupler unit and a return optical monitor signal is detected in the received optical signal. Means,
An optical cross-connect system characterized by comprising
(Appendix 2)
When the disconnection determination unit determines that the optical line disconnection has occurred, the optical line disconnection information is transmitted to the GMPLS control network under which the optical cross-connect system is placed. Optical cross-connect system.
(Appendix 3)
The monitor light generation unit is configured by a monitor light generation unit that generates the optical monitor signal and transmits it to the optical coupler unit corresponding to each port, and (i) the optical signal from the optical coupler unit A monitor light detection unit that receives and detects the presence or absence of the return light monitor signal; and (ii) is formed between the optical coupler unit corresponding to each port, the monitor light generation unit, and the monitor light detection unit. An optical switch for switching the light path; and (iii) control for sequentially switching the light path in the optical switch and determining the presence or absence of the return light monitor signal for each of the ports in cooperation with the monitor light detection unit. The optical cross-connect system according to appendix 1, wherein the disconnection determination unit is configured by a unit.
(Appendix 4)
The optical switch includes two light input / output terminals respectively assigned to the monitor light generation unit and the monitor light detection unit, and n (n is an integer of 2 or more) corresponding to each port. The optical cross-connect system according to supplementary note 3, wherein the optical cross-connect system is a 2: n-type optical switch including n optical input / output terminals respectively assigned to.
(Appendix 5)
The monitor light generation unit is configured by a monitor light generation unit that generates the optical monitor signal and transmits it to the optical coupler unit corresponding to each port, and (i) the optical signal from the optical coupler unit A monitor light detection unit that receives and detects the presence or absence of the return light monitor signal; and (ii) an optical coupler between each of the ports, the monitor light generation unit, and the monitor light detection unit. The disconnection determining means includes: a monitoring optical coupler that forms a branch path; and (iii) a control unit that determines the presence or absence of the return light monitor signal from the monitoring optical coupler in cooperation with the monitoring light detection unit. The optical cross-connect system according to appendix 1, which is configured.
(Appendix 6)
The monitoring optical coupler includes two light input / output terminals respectively assigned to the monitor light generation unit and the monitor light detection unit, and n (n is an integer of 2 or more) corresponding to each port. The optical cross-connect system according to appendix 3, wherein the optical cross-connect system is a 2: n-type optical directional coupler comprising n optical input / output terminals respectively assigned to the coupler section.
(Appendix 7)
The monitor light transmitting means is input from a second port that is different from the first port that outputs the first optical main signal and is the port of interest for detection of the disconnection of the optical line. The second optical main signal having a wavelength different from that of the first optical main signal is used as the optical monitor signal in the optical coupler unit corresponding to the first port via the optical cross-connect unit. (I) a wavelength analysis unit that receives the optical signal from the optical coupler unit and detects the presence or absence of the return light monitor signal; and (ii) each of the above-described optical main signals. An optical switch that switches a path of light to be formed between the optical coupler unit corresponding to the port and the wavelength analysis unit; and (iii) sequentially switches the path of the light in the optical switch and cooperates with the wavelength analysis unit. Before each port Optical cross-connect system according to Note 1, wherein the configuring the cross-sectional determination means and determining the control unit whether the returning light monitor signal, by.
(Appendix 8)
The optical switch includes one optical input terminal allocated to the wavelength analysis unit and n optical input units allocated to the n optical coupler units corresponding to the ports (n is an integer of 2 or more). The optical cross-connect system according to appendix 7, wherein the optical cross-connect system comprises an output end.
(Appendix 9)
The control unit manages the wavelength of the optical main signal assigned to each port, and identifies whether the optical signal detected by the wavelength analysis unit corresponds to the return optical monitor signal The optical cross-connect system according to appendix 7, wherein
(Appendix 10)
The first optical main signal input from a second port different from the first port that outputs the first optical main signal, which is the port of interest for detecting the disconnection of the optical line. The second optical main signal having a different wavelength is combined with the first optical main signal at the optical coupler unit corresponding to the first port via the optical cross-connect unit as the optical monitor signal. And (i) a path switching unit that receives the optical signal from the optical coupler unit and routes it to a further monitoring port in the optical cross-connect unit; ii) a wavelength analysis unit that receives an optical signal from the optical coupler unit output from the monitoring port and detects the presence or absence of the return optical monitor signal; and (iii) the monitoring port of the optical cross-connect unit. And a controller that sequentially switches the optical path between the port and each port and determines the presence or absence of the return light monitor signal for each port in cooperation with the wavelength analyzer. The optical cross-connect system according to appendix 1, which is configured.
(Appendix 11)
The control unit manages the wavelength of the optical main signal assigned to each port, and identifies whether the optical signal detected by the wavelength analysis unit corresponds to the return optical monitor signal The optical cross-connect system according to appendix 10, wherein
(Appendix 12)
The first optical main signal input from a second port different from the first port that outputs the first optical main signal, the port being focused on for detecting the disconnection of the optical line A second optical main signal having a wavelength different from that of the first optical main signal is combined with the first optical main signal at the optical coupler unit corresponding to the first port via the optical cross-connect unit as the optical monitor signal. (I) a monitor light detection unit that receives the optical signal from the optical coupler unit and detects the presence or absence of the return light monitor signal; and (ii) each of the above An optical wavelength variable filter having a variable pass wavelength provided between the optical coupler unit corresponding to the port and the monitor light detecting unit; and (iii) sequentially switching the pass wavelength in the optical wavelength variable filter corresponding to each port. Together with the above Optical cross-connect system according to Note 1, wherein the configuring the cross-sectional determination means and determining the control unit the presence or absence of the return light monitor signal for each said port in cooperation to Nita light detection unit, by.
(Appendix 13)
The optical wavelength tunable filter includes a first optical wavelength tunable filter and a second optical wavelength tunable filter, wherein the first optical wavelength tunable filter is a first port set as the first port. 13. The optical cross-connect according to appendix 12, wherein the second optical wavelength tunable filter is configured to cooperate only with a second port group set as the second port. system.
(Appendix 14)
The control unit manages the wavelength of the optical main signal allocated to each port, and identifies whether the optical signal detected by the monitor light detection unit corresponds to the return light monitor signal The optical cross-connect system according to appendix 12, wherein:

  The present invention can be applied to the case of detecting an optical line break in a bidirectional optical communication system using a single-core optical fiber by using GMPLS management function information.

It is a figure which shows the basic composition of the OXC system which concerns on this invention. It is a figure showing the general hierarchical structure of a GMPLS network. It is a figure which shows the whole structure of the OXC system based on Example 1 of this invention. FIG. 4 is a diagram illustrating a signal flow in FIG. 3. It is a figure which shows an example of the table 14-1 which prescribes | regulates the flow of the signal in FIG. It is a flowchart which shows the operation example of the control part in Example 1 of this invention. It is a figure which shows the whole structure of the OXC system based on Example 2 of this invention. It is a figure which illustrates the flow of the signal in FIG. It is a figure which shows an example of the table 14-2 which prescribes | regulates the flow of the signal in FIG. It is a flowchart which shows the operation example of the control part in Example 2 of this invention. It is a figure which shows the whole structure of the OXC system based on Example 3 of this invention. It is a figure which illustrates the flow of the signal in FIG. It is a figure which shows an example of the table 14-3 which prescribes | regulates the flow of the signal in FIG. It is a flowchart which shows the operation example of the control part in Example 3 of this invention. It is a figure which shows the whole structure of the OXC system based on Example 4 of this invention. It is a figure which illustrates the flow of the signal in FIG. It is a figure which shows an example of the table 14-4 which prescribes | regulates the flow of the signal in FIG. It is a flowchart which shows the operation example of the control part in Example 4 of this invention. It is a figure which shows the whole structure of the OXC system based on Example 5 of this invention. It is a figure which illustrates the flow of the signal in FIG. It is a figure which shows an example of the table 14-5 which prescribes | regulates the flow of the signal in FIG. It is a flowchart which shows the operation example of the control part in Example 5 of this invention. It is a figure which shows the specific example of the optical coupler part (ODC) 20 of FIG. It is a figure which shows the specific example of the optical switch 33 of FIG. It is a figure which shows the detailed example of one unit in FIG. It is a figure which shows the specific example of the optical switch 53 of FIG. It is a figure which shows the specific example of AOTF (73-1, 73-2) of FIG. It is a figure which shows the basic composition of a general system. It is a figure which illustrates the mode of FIG. 28 at the time of a unidirectional connection. It is a figure which illustrates the mode of FIG. 28 at the time of bidirectional | two-way connection.

Explanation of symbols

10. Optical cross-connect system (OXC system)
11 ... Optical cross-connect part (OXC part)
12 ... Port 13 ... Optical transceiver (OS / OR)
14. Optical switch / forwarding table (route switching management table)
DESCRIPTION OF SYMBOLS 15 ... Single optical fiber 16 ... GMPLS control network 20 ... Optical coupler part 21 ... Monitor light transmission means 22 ... Disconnection determination means 31 ... Monitor light generation part 32 ... Monitor light detection part 33 ... Optical switch 34 ... Control part 43 ... Monitor Optical coupler 53 ... Optical switch 54 ... Wavelength analyzing unit 63 ... Monitor path unit 64 ... Monitoring port 73 ... Optical wavelength variable filter 73-1 ... First optical wavelength variable filter 73-2 ... Second optical wavelength variable filter

Claims (2)

An optical cross-connect unit having a plurality of ports;
An optical coupler unit that is provided for each of the ports and performs multiplexing and demultiplexing of an optical main signal bidirectionally transmitted between the single optical fiber and the port;
Monitor light transmission means for transmitting the optical monitor signal having a wavelength different from the wavelength of the optical main signal, the optical monitor signal being combined with the optical main signal and transmitted to the optical fiber in the optical coupler unit When,
A disconnection determination that determines that an optical line disconnection has occurred on the optical fiber when an optical signal from the optical fiber is received via the optical coupler unit and a return optical monitor signal is detected in the received optical signal. Means, and
The monitor light transmitting means is input from a second port that is different from the first port that outputs the first optical main signal and is the port of interest for detection of the disconnection of the optical line. The second optical main signal having a wavelength different from that of the first optical main signal is used as the optical monitor signal in the optical coupler unit corresponding to the first port via the optical cross-connect unit. (I) a wavelength analysis unit that receives the optical signal from the optical coupler unit and detects the presence or absence of the return light monitor signal; and (ii) each of the above-described optical main signals. An optical switch that switches a path of light to be formed between the optical coupler unit corresponding to the port and the wavelength analysis unit; and (iii) sequentially switches the path of the light in the optical switch and cooperates with the wavelength analysis unit. Before each port Optical cross-connect system characterized by configuring the cross-sectional determination means and determining the control unit whether the returning light monitor signal, by. An optical cross-connect unit having a plurality of ports;
An optical coupler unit that is provided for each of the ports and performs multiplexing and demultiplexing of an optical main signal bidirectionally transmitted between the single optical fiber and the port;
Monitor light transmission means for transmitting the optical monitor signal having a wavelength different from the wavelength of the optical main signal, the optical monitor signal being combined with the optical main signal and transmitted to the optical fiber in the optical coupler unit When,
A disconnection determination that determines that an optical line disconnection has occurred on the optical fiber when an optical signal from the optical fiber is received via the optical coupler unit and a return optical monitor signal is detected in the received optical signal. Means, and
The first optical main signal input from a second port different from the first port that outputs the first optical main signal, the port being focused on for detecting the disconnection of the optical line A second optical main signal having a wavelength different from that of the first optical main signal is combined with the first optical main signal at the optical coupler unit corresponding to the first port via the optical cross-connect unit as the optical monitor signal. And (i) a path switching unit that receives the optical signal from the optical coupler unit and sets the route to a further monitoring port in the optical cross-connect unit, and (Ii) a wavelength analysis unit that receives an optical signal from the optical coupler unit output from the monitoring port and detects the presence or absence of the return optical monitor signal; and (iii) the monitoring unit of the optical cross-connect unit. And a controller that sequentially switches the optical path between the port and each port and determines the presence or absence of the return light monitor signal for each of the ports in cooperation with the wavelength analyzer. An optical cross-connect system characterized by comprising

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