Remote optical path switching node and monitoring method thereof

Abstract

The objective of the present disclosure is to enable confirmation of a connection between optical fibers using test light from an accommodating station, even when a point-to-point connection is being carried out in an optical fiber network.　Disclosed is a remote optical path switching node for connecting two loop networks in which optical fibers are connected in a loop, wherein the two loop networks comprise an upper loop close to a tester that emits test light and a lower loop far from the tester, said remote optical path switching node comprising: an optical cross-connect connected to the optical fibers constituting the lower loop; a testing optical coupler that is connected to a testing optical fiber for propagating test light in the upper loop, and that can be connected to the optical cross-connect; a control unit for controlling connection of the optical cross-connect and the testing optical coupler; and a light extraction unit for detecting the test light propagated in the upper loop and emitted from the testing optical coupler or the optical cross-connect.

Description

[Technical Field]

[0001] The present disclosure relates to monitoring optical fiber connections in point-to-point connections in an optical fiber network. [Background technology]

[0002] In optical fiber networks, particularly in access networks that connect communication devices installed in exchanges with user-side communication terminals (hereinafter referred to as user terminals), optical fiber switching is carried out to connect optical fiber to any route or change the route in order to use the facilities efficiently during installation and maintenance.

[0003] By transmitting test light from the accommodating station to this remote optical path switching node, it is possible to check the switching of optical fiber at the remote optical path switching node. However, when point-to-point connections are used in an optical fiber network, depending on the connection mode of the point-to-point connection, it may not be possible to check the switching of optical fiber even if test light is transmitted from the accommodating station.

[0004] For example, in an optical fiber network in which optical fibers are connected in a loop to form a loop network and loop networks are connected in multiple stages, a remote optical path switching node is installed to connect the loop networks together. When checking the connection of this remote optical path switching node, there are cases where it is not possible to confirm the switching of optical fibers even when test light is transmitted from the accommodation station. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Tomohiro Kawano, Tatsuya Fujimoto, Kazuhide Nakae, Hiroshi Watanabe, Kazunori Katayama, "Study on remote optical path switching nodes for future optical access networks," 2021 Institute of Electronics, Information and Communication Engineers General Conference, B-13-16, 2021 [Non-patent document 2] Hiroshi Watanabe, Tomohiro Kawano, Chisato Fukai, Ryo Koyama, Kazuhide Nakae, Tatsuya Fujimoto, Yoshiteru Abe, Kazunori Katayama, "Remote Optical Path Switching Nodes Operating in Multistage Loop-Type Optical Access Networks," 2021 IEICE Society Conference, BK-2-3, 2021 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to enable checking the connection between optical fibers using test light from an access point, even when point-to-point connections are made in an optical fiber network. [Means for solving the problem]

[0007] The optical fiber network of the present disclosure comprises two loop networks connected in a loop shape using the remote optical path switching node of the present disclosure, a test optical fiber for transmitting test light to the remote optical path switching node, and a tester for injecting test light into the test optical fiber.

[0008] The two loop networks include an upper loop close to a tester that emits test light, and a lower loop far from the tester. The remote optical path switching node of the present disclosure comprises: an optical cross connect connected to the optical fiber that constitutes the lower loop; a test optical coupler connected to a test optical fiber that propagates test light in the upper loop and connectable to the optical cross connect; a control unit that controls the connection between the optical cross connect and the test optical coupler; an optical extraction unit that detects test light that propagates through the upper loop and is output from the test optical coupler or the optical cross-connect; It is equipped with:

[0009] A monitoring method for a remote optical path switching node according to the present disclosure is a monitoring method executed by a remote optical path switching node according to the present disclosure, the control unit connects the upper loop and the lower loop, or connects the lower loops to each other, using the optical cross connect and the test optical coupler; An optical extractor detects the test light that propagates through the upper loop and is emitted from the test optical coupler or the optical cross-connect.

[0010] the test optical coupler has four ports; the first and second ports of the test optical coupler are respectively connected to optical fibers of different directions in the upper loop network; The test optical coupler may output test light input to a first port to a fourth port that is a different direction from the first port, and may output test light input to a second port to a third port that is a different direction from the second port.

[0011] the optical cross-connect has four ports; a third port and a fourth port of the optical cross-connect are respectively connected to optical fibers of different directions in the lower loop network; The control unit may connect the lower loops to each other by connecting a first port of the optical cross-connect to the third port of the test optical coupler and connecting a second port of the optical cross-connect to the fourth port of the test optical coupler.

[0012] the optical cross-connect has four ports; a third port and a fourth port of the optical cross-connect are respectively connected to optical fibers of different directions in the lower loop network; The control unit (i) connecting a fourth port of the test optical coupler to an optical fiber of the upper loop; connecting a third port of the test optical coupler to a first port of the optical cross-connect; connecting a first port to a third port in the optical cross-connect; or (ii) connecting a third port of the test optical coupler to an optical fiber of the upper loop; connecting a fourth port of the test optical coupler to a second port of the optical cross-connect; By connecting the second port to the fourth port in the optical cross-connect, The upper loop and the lower loop may be connected.

[0013] The optical cross connect, the test optical coupler, and the optical extractor may be integrally configured.

[0014] The above disclosures can be combined as much as possible. [Effects of the Invention]

[0015] The present disclosure makes it possible to check the connection between optical fibers using test light from an access point, even when point-to-point connections are made in an optical fiber network. [Brief explanation of the drawings]

[0016] [Figure 1] An example of a multistage loop wiring and a remote optical path switching node configuration is shown. [Figure 2] An example of the connection state of optical lines when passing through a station building is shown. [Figure 3] An example of the connection state of optical lines when a PtoP connection is made is shown below. [Figure 4] An example of a state when a PtoP connection is made is shown below. [Figure 5] 1 shows an example of the configuration of a remote optical path switching node. [Figure 6] 1 shows an example of the configuration of a remote optical path switching node. [Figure 7] An example of a method for checking the optical fiber connection status within a remote optical path switching node when a PtoP connection is made will be shown. [Figure 8]FIG. 10 is an explanatory diagram of a method for checking the optical fiber connection state within a remote optical path switching node in the case of a PtoP connection. [Figure 9] FIG. 10 is an explanatory diagram of a method for checking the optical fiber connection state within a remote optical path switching node in the case of a PtoP connection. [Figure 10] 10 illustrates an example of a connection state of optical paths according to an embodiment of the present disclosure. [Figure 11] 1 illustrates an example of an optical fiber connection state within a remote optical path switching node according to an embodiment of the present disclosure. [Figure 12] 10 illustrates an example of a connection state of optical paths according to an embodiment of the present disclosure. [Figure 13] 1 illustrates an example of an optical fiber connection state within a remote optical path switching node according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0018] (Network configuration) The configuration of the optical fiber network of the present disclosure is shown in Figure 1. The optical fiber network of the present disclosure includes an access station 12 and a loop network. The access station 12 includes, for example, an access station distribution frame 21, a tester 22, an in-house optical path switching node 23, and a node Ops (Operation system) 24. The access station 12 may be connected to other Ops 26, such as an underground optical maintenance system, via an API (Application Programming Interface) 25. The tester 22 is a device that emits test light, and the test light is input to the optical fiber of the upper loop in the access station distribution frame 21.

[0019] FIG. 1 shows an example in which optical fibers are connected in a loop to form a loop network, and the loop networks are connected in multiple stages. A remote optical path switching node 11 that connects the loop networks is placed where the loops overlap. The loop closest to the accommodation station 12 is defined as the upper loop, and the loop connected to the upper loop is defined as the lower loop. FIG. 1 shows a configuration using three lower loops. The remote optical path switching node 11 that connects the upper loop and the lower loop has the function of changing the route of the optical fiber. To switch, the accommodation station 12 issues an instruction (signal) to the remote optical path switching node 11, and the remote optical path switching node 11 performs the switch based on that instruction (see Non-Patent Documents 1 and 2).

[0020] Examples of using the optical network shown in Fig. 1 are shown in Fig. 2, Fig. 3, and Fig. 4. Fig. 2 shows a configuration in which a user terminal 13A is connected to a user terminal 13B (not shown) connected beyond an accommodation station 12 via a remote optical path switching node 11. Figs. 3 and 4 show a configuration in which a user terminal 13A is connected to a user terminal 13B via a remote optical path switching node 11 without going through an accommodation station 12.

[0021] The examples in Figures 3 and 4 are called Point to Point connections (hereinafter defined as P to P connections) because user terminal 13A and user terminal 13B are considered as points and these two points are connected. Figure 2 also connects user terminal 13A to user terminal 13B (not shown) located behind the accommodating station, so it is also treated as a P to P connection. In this disclosure, the connections shown in Figures 2 and 3 are called P to P connections from an upper loop to a lower loop, and the connection shown in Figure 4 is called a P to P connection between lower loops.

[0022] In Figure 2, when the accommodating station 12 and the user terminal 13A are connected on a single-core basis, the accommodating station 12 can check the connection status at the remote optical path switching node 11 by inserting test light into the communication optical fiber F1U, which is the working optical fiber, using the optical coupler of the accommodating station distribution frame 21 and receiving a signal from the remote optical path switching node 11.

[0023] 5 and 6 show an example of the internal structure and functions of the remote optical path switching node 11. The remote optical path switching node 11 comprises an optical cross connect 31 in the center, two optical extractors 35#1 and 35#2, a photodiode (PD) 33, a storage capacitor 34, and a control unit 32. The remote optical path switching node 11 is connected to communication optical fibers F0U, F1U, F0L, and F1L, and is also connected to a power supply control fiber SC.

[0024] The optical cross connect 31 has four ports P11 to P14, with port P11 functioning as a first port, port P12 functioning as a second port, port P13 functioning as a third port, and port P14 functioning as a fourth port. In this disclosure, an example is shown in which ports P11 and P12 are connected to optical fibers F0U and F1U of an upper loop, and ports P13 and P14 are connected to optical fibers F0L and F1L of a lower loop.

[0025] 5 shows an example of a PtoP connection from the upper loop to the lower loop shown in FIG. 3. When the PtoP connection shown in FIG. 3 is implemented, the PtoP connection is established by connecting ports P12 and P13 of the optical cross-connect 31. To confirm that ports P12 and P13 are connected, it is necessary to transmit test light through the optical fiber connecting ports P12 and P13. However, both ends of the communication optical fiber F1U and the communication optical fiber F0L are connected to user terminals 13A and 13B, respectively, and therefore test light from the tester 22 cannot be sent from the communication optical fiber F1U to the communication optical fiber F0L. As a result, the exchange 12 cannot confirm whether the optical fiber is connected at the remote optical path switching node 11 (see Non-Patent Document 2).

[0026] Figure 6 shows an example of a PtoP connection between the lower loops shown in Figure 4. When the PtoP connection shown in Figure 4 is implemented, the PtoP connection is established by connecting ports P13 and P14 of the optical cross connect 31. In this case, as in Figure 3, the optical fiber from the tester 22 cannot be connected to the optical fiber in the PtoP section. Therefore, the test light from the exchange 12 cannot be sent to the PtoP section, and the port information indicating that the optical fibers F0L and F1L are connected cannot be obtained.

[0027] With current technology, in the case of a PtoP connection between an upper loop and a lower loop as shown in Fig. 3 and a PtoP connection between lower loops as shown in Fig. 4, port information cannot be obtained because test light cannot be sent from the accommodation station 12 to the communication optical fiber used in the PtoP section. Therefore, when checking the optical fiber connection status within the remote optical path switching node 11 from the accommodation station 12, the five steps shown in Fig. 7 are required. These steps will be explained with reference to Figs. 8 and 9.

[0028] 8 and 9, it is desired to connect user terminals 13A and 13B together. To do this, the accommodating station 12 issues an instruction to the remote optical path switching node 11. In accordance with the instruction from the accommodating station 12, the control unit 32 in the remote optical path switching node 11 operates the optical cross connect 31 to connect the user terminal 13A and the user terminal 13B.

[0029] It is necessary to confirm that the connection has been made. To do this, a dedicated light is used for the test. The communication light uses a wavelength of 1310nm to 1550nm. On the other hand, the test light has a wavelength of 1650nm. A different wavelength from the communication light is used for the test light. To input this test light, an optical coupler 14 is installed on one of the user terminals 13A. The optical coupler 14 has multiple ports and is of the 2x2 type. The test light is input from an available port.

[0030] The accommodation station 12 issues an instruction to the remote optical path switching node 11 to detect the connection of the optical fiber, and makes preparations in advance (S101). Test light is inserted from the optical coupler 14 of the user terminal 13A toward the user terminal 13B (S102). In this step, the test light passes through the interior of the remote optical path switching node 11 for the first time. The remote optical path switching node 11 confirms that the test light has passed through. At this time, the communication light can be read from an optical extraction unit previously provided inside the remote optical path switching node 11 (S103). The remote optical path switching node 11 can send the read port information to the accommodation station 12 (S104). The accommodation station 12 receives the result that the test light has passed through the remote optical path switching node 11 (S105). By performing the above five steps, it is possible to confirm that user terminal 13A and user terminal 13B are connected.

[0031] Here, the instruction notified from the accommodating station 12 to the remote optical path switching node 11 in step S101 is to extract the test light passing through the communication optical fiber inside the remote optical path switching node 11 using the optical extraction units 35#1 and 35#2, and to transmit port information of the extracted light to the accommodating station 12. The port information is information about which port connected to the communication optical fiber the test light passed through, and specifically, the optical fiber number of the communication optical fiber can be exemplified.

[0032] When the accommodating station 12 acquires port information in the remote optical path switching node 11 using the method described in FIG. 7, the following problem occurs. First problem: It is necessary to configure the equipment so that test light can be transmitted from the user terminal 13 side. Second problem: Since the user's consent is required to transmit the test light, the test light cannot be transmitted at any time. Third problem: Providing a separate optical fiber on the user terminal 13 side just for transmitting test light is operationally inefficient.

[0033] (First embodiment of the invention) Fig. 10 shows an example of a network configuration according to an embodiment of the present disclosure. Fig. 11 shows an example of a remote optical path switching node. In this embodiment, the upper loop is provided with test optical fibers F0T and F1T that connect the accommodation station 12 and the remote optical path switching node 11. By being provided with these configurations, the remote optical path switching node 11 of this embodiment can transmit test light from the accommodation station 12 to the optical fiber used for the PtoP connection, even in the case of a PtoP connection from the upper loop to the lower loop.

[0034] The remote optical path switching node 11 according to this embodiment includes a test optical coupler 41. The test optical coupler 41 has four ports P41 to P44, with the port P41 functioning as a first port, the port P42 functioning as a second port, the port P43 functioning as a third port, and the port P44 functioning as a fourth port.

[0035] In this disclosure, port P41 and port P42 are connected to test optical fibers F0T and F1T (0 system, 1 system), respectively, which are different paths in the upper loop. The test optical fibers F0T and F1T are connected to the accommodation station 12, which is provided with a tester 22 that emits test light. The test light is emitted from the accommodation station 12 and reaches the test optical coupler 41.

[0036] The test optical coupler 41 outputs the test light incident on the first port P41 to a port P44 on a different route from the port P41, and outputs the test light incident on the port P42 to a port P43 on a different route from the port P42.

[0037] The optical cross connect 31 has four ports P11 to P34. The ports P13 and P14 are connected to optical fibers F0L and F1L of different directions in the lower loop, respectively.

[0038] Port P43 can be connected to either optical fiber F0U of the upper loop or port P11 of the optical cross connect. Port P44 can be connected to either optical fiber F1U of the upper loop or port P12 of the optical cross connect. The control unit 32 can connect the ports of the optical cross connect 31 to each other and the optical cross connect 31 to the test optical coupler 41.

[0039] In the case of a PtoP connection from an upper loop to a lower loop, the optical cross-connect 31 is not connected from port P12 to port P13, but rather port P11 and port P13 are connected, and the connection is from user terminal 13A to user terminal 13B via test optical coupler 41.

[0040] The configuration is such that the communication optical fiber F1U of the user terminal 13B is connected to port P44, and port P43 of the test optical coupler 41 is connected to port P11 of the optical cross connect 31. Furthermore, port P11 of the optical cross connect 31 is connected to port P13, and port P13 of the optical cross connect 31 is connected to the communication optical fiber F0L of the user terminal 13A, thereby constructing an optical path from the user terminal 13B to the user terminal 13A.

[0041] When test light is inserted from the exchange 12 into the test optical fiber F1T, the test light enters port P42, passes through ports P43 and P11, and exits from port P13. The light extraction unit 35#1 extracts the test light from the optical fiber F0L connected to port P13. This makes it possible to detect port information on the optical fiber F0L (in this embodiment, the optical fiber number of the communication optical fiber F0L connected to port P13).

[0042] When test light is inserted into the test optical fiber F0T (0 system), the test light is input to port P41 and output from port P44. The light extraction unit 35#2 extracts the test light from the optical fiber F1U. This makes it possible to detect port information for the optical fiber F1U (in this embodiment, the optical fiber number of the communication optical fiber F1U connected to port P44).

[0043] Therefore, in this embodiment, port information can be detected by the optical extraction units 35#1 and 35#2, and the control unit 32 transmits the detection results to the accommodating station 12, making it possible to grasp port information between the accommodating station 12 and the user terminal 13 (between user terminal 13A and terminal 13B).

[0044] In the present embodiment, an example has been shown in which the port P44 of the test optical coupler 41 is connected to the optical fiber F1U of the upstream loop, the port P43 of the test optical coupler 41 is connected to the port P11 of the optical cross connect 31, and the port P11 is connected to the port P13 in the optical cross connect 31, but the present disclosure is not limited to this. For example, the control unit 32 may connect the port P43 of the test optical coupler 41 to the optical fiber F0U of the upstream loop, connect the port P44 of the test optical coupler 41 to the port P12 of the optical cross connect 31, and connect the port P12 to the port P14 in the optical cross connect 31.

[0045] (Second embodiment of the invention) Fig. 12 shows an example of a network configuration according to an embodiment of the present disclosure. Fig. 13 shows an example of a remote optical path switching node according to this embodiment. The basic configuration is the same as that of the first embodiment. However, the remote optical path switching node 11 of this embodiment enables test light to be transmitted from the accommodation station 12 to the optical fiber used for the PtoP connection, even in the case of a PtoP connection between lower loops.

[0046] In the case of a PtoP connection in which lower loops are connected to each other, the control unit 32 connects the port P11 of the optical cross connect 31 to the port P43 of the test optical coupler 41, and connects the port P12 of the optical cross connect 31 to the port P44 of the test optical coupler 41.

[0047] Furthermore, the control unit 32 connects the user terminal 13A to the user terminal 13B as shown in FIG. The communication optical fiber F0L of the user terminal 13A →Port P13 of Optical Cross Connect 31 →Port P11 of Optical Cross Connect 31 → Port P43 of test optical coupler 41 → Port P44 of test optical coupler 41 →Port P12 of Optical Cross Connect 31 →Port P14 of Optical Cross Connect 31 →Communication optical fiber F1L of user terminal 13B

[0048] By constructing such an optical path, when test light is added from the exchange 12 to the test optical fiber F1T, the test light enters port P42, passes through ports P43 and P11, and exits from port P13. The optical extractor 35#1 extracts the test light from the optical fiber F0L connected to port P13. This makes it possible to detect port information on the optical fiber F0L (in this embodiment, the optical fiber number of the communication optical fiber F0L connected to port P13).

[0049] When test light is inserted into the test optical fiber F0T, the test light enters port P41, passes through ports P44 and P12, and exits from port P14. The light extraction unit 35#2 extracts the test light from the optical fiber F1L connected to port P14. This makes it possible to detect port information on the optical fiber F1L (in this embodiment, the optical fiber number of the communication optical fiber F1L connected to port P14).

[0050] Therefore, in this embodiment, port information can be detected by the optical extraction units 35#1 and 35#2, and the control unit 32 can transmit the detection results to the accommodating station 12, thereby confirming the connection of the optical fiber between the accommodating station 12 and the user terminal 13 (between user terminal 13A and terminal 13B).

[0051] As described above, the present disclosure allows testing to be performed from the accommodation station 12 without installing an optical coupler 14 in the building managed by the user terminal, eliminating time constraints. Furthermore, there is no need to prepare optical fiber for testing on the user terminal side. Therefore, the present disclosure can improve operational efficiency.

[0052] In the above embodiment, the optical cross connect 31, the test optical coupler 41, and the optical extractors 35#1 and 35#2 are configured as separate components, but two or more of these may be configured as an integrated unit. [Explanation of symbols]

[0053] 11: Remote optical path switching node 12: Storage station 13: User terminal 14: Optical coupler 21: Distribution frame for receiving station 22: Test equipment 23: In-house optical path switching node 24: Node Ops 25:API 26: Other Ops 31: Optical cross connect 32: Control unit 33:PD 34: Storage capacitor 35:Light extraction part

Claims

1. A remote optical path switching node that connects two loop networks in which optical fibers are connected in a loop, The two loop networks include an upper loop close to a tester that emits test light, and a lower loop far from the tester; an optical cross connect connected to the optical fiber that constitutes the lower loop; a test optical coupler connected to a test optical fiber that propagates test light in the upper loop and connectable to the optical cross connect; a control unit that controls the connection between the optical cross connect and the test optical coupler; an optical extraction unit that detects test light that propagates through the upper loop and is output from the test optical coupler or the optical cross-connect; A remote optical path switching node comprising:

2. the test optical coupler has four ports; the first and second ports of the test optical coupler are respectively connected to optical fibers of different directions in the upper loop; the test optical coupler outputs the test light input to the first port to a fourth port that is a path different from the first port, and outputs the test light input to the second port to a third port that is a path different from the second port. The remote optical path switching node according to claim 1 .

3. the optical cross-connect has four ports; a third port and a fourth port of the optical cross-connect are respectively connected to optical fibers of different directions in the lower loop; the control unit connects the first port of the optical cross connect to the third port of the test optical coupler and connects the second port of the optical cross connect to the fourth port of the test optical coupler, thereby connecting the lower loops to each other. The remote optical path switching node according to claim 2 .

4. the optical cross-connect has four ports; a third port and a fourth port of the optical cross-connect are respectively connected to optical fibers of different directions in the lower loop; The control unit (i) connecting a fourth port of the test optical coupler to the optical fiber of the upper loop; connecting a third port of the test optical coupler to a first port of the optical cross-connect; connecting a first port to a third port in the optical cross-connect; or (ii) connecting a third port of the test optical coupler to the optical fiber of the upper loop; connecting a fourth port of the test optical coupler to a second port of the optical cross-connect; connecting the second port to the fourth port in the optical cross-connect; connecting the upper loop and the lower loop; The remote optical path switching node according to claim 2 .

5. two or more of the optical cross connect, the test optical coupler, and the optical extraction unit are integrally configured; The remote optical path switching node according to claim 1 .

6. a remote optical path switching node according to any one of claims 1 to 5; a test optical fiber for transmitting test light to the remote optical path switching node; a tester for injecting test light into the test optical fiber; Equipped with Fiber optic network.

7. A monitoring method executed by a remote optical path switching node connecting two loop networks in which optical fibers are connected in a loop, comprising: The two loop networks include an upper loop close to a tester that emits test light, and a lower loop far from the tester; The remote optical path switching node an optical cross connect connected to the optical fiber that constitutes the lower loop; a test optical coupler connected to a test optical fiber that propagates test light in the upper loop and connectable to the optical cross connect; a control unit that controls the connection between the optical cross connect and the test optical coupler; Equipped with the control unit connects the upper loop and the lower loop, or connects the lower loops to each other, using the optical cross connect and the test optical coupler; an optical extraction unit that detects test light that propagates through the upper loop and is output from the test optical coupler or the optical cross-connect; Monitoring method.

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