JP2016115962A - Pon (passive optical network) system and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability of communication.SOLUTION: A PON system has a first PON where a communication device is connected with a plurality of upper terminators, and a second PON where the communication device is connected with a plurality of lower terminators. The communication device has a communication unit communicating with any one of the plurality of upper terminators via any one of a plurality of optical transmission paths connecting the plurality of upper terminators and the communication device, and a changeover unit for switching the optical path used by the communication device to any one of a plurality of optical paths depending on the fault state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a PON system and a communication device.

  In recent years, FTTH (Fiber To The Home) has been introduced along with the spread of broadband services. FTTH is a PON system as a main form.

  The PON system includes one station-side terminal device (OLT: Optical Line Terminal), at least one subscriber-side terminal device (ONU: Optical Network Unit), and an optical splitter that connects the OLT and the ONU.

FIG. 31 is a diagram illustrating an example of a PON system. As illustrated in FIG. 31, the PON system 1000 includes an OLT 1100 and a plurality of ONUs 1300 ₁ via optical transmission paths 1200 _{1 to} 1200 _n (for example, fiber transmission paths) and a 1 to n (n is a natural number) optical splitter 1700. A network that performs point-to-multipoint communication with ˜1300 _n . As a typical standard of the gigabit class PON, there is EPON (Ethernet (registered trademark) PON) standardized by IEEE 802.3. For example, 10G-class 10G-EPON is standardized in EPON, for example, in the IEEE 802.3av study group.

As a PON system, a cascade PON in which a plurality of PONs are connected in multiple stages has also been proposed (see, for example, Non-Patent Document 1). Cascade PONs can accommodate a large number of ONUs that exceed the limit of the number of branches in a single PON. FIG. 32 is a diagram illustrating an example of a cascade PON system. As shown in FIG. 32, the cascade PON 2000 includes an OLT 2100, a plurality of ONUs 2130 _{21 to} 2130 _xz , m optical splitters 2170 _{1 to} 2170 ₃ (the number of branches is arbitrary), and a plurality of cascades that are communication devices. Node devices (hereinafter referred to as C nodes) 2150 _{11 to} 2150 _xy .

The optical transmission line 2120 ₁ is connected to the OLT 2110 via the optical splitter 2170 ₁ . Furthermore, the C node 2150 _11, is a plurality of ONU2130 ₂₁ ~2130 _2m, and C nodes 2150 _21, are connected through an optical splitter 2170 _2. Further, the C node 2150 ₂₁ is connected to the C node 2150 _xy . Thus, the cascade PON 2000 forms a multistage PON system. Such a cascade PON can reduce the cost because the optical transmission line from the OLT to the optical splitter can be shared by a plurality of ONUs.

Masashi Tadokoro, Akihisa Fujiwara, Hirotaka Urakawa, Hiroshi Wang, Kenichi Suzuki, “Examination of Cascade PON Using 10G-EPON System”, IEICE Society Conference, B-8-47, September 9, 2014

  However, the above-described conventional technology has a problem that the reliability of communication is low. Specifically, in the above technique, a cascade PON can accommodate a large number of ONUs, but the number of ONUs arranged under one OLT or a C node at a higher position increases. For this reason, for example, the cascade PON is connected to an optical transmission line connecting the OLT and the C node (for example, an optical transmission line under the splitter) or a device at a higher position due to a failure of the upper C node. When communication cannot be performed, there is a problem that all ONUs arranged below the failed C node cannot communicate.

  In order to solve the above-described problems and achieve the object, the PON system of the present invention includes a first PON in which a communication device is connected to a plurality of higher-order terminal devices, and the communication device is connected to a lower-order terminal device. A PON system having a second PON, wherein the communication device is configured to pass through any one of a plurality of optical transmission lines to which the plurality of higher-level terminal devices and the communication device are connected. A communication unit that communicates with any one of a plurality of higher-level termination devices, and an optical transmission path used by the communication unit is selected from the plurality of optical transmission paths according to a failure situation. And a switching unit for switching to a road.

  According to the present invention, it is possible to improve the reliability of communication.

FIG. 1 is a diagram illustrating a configuration of a PON system according to the first embodiment. FIG. 2 is a diagram illustrating a configuration of the C node according to the first embodiment. FIG. 3 is a diagram illustrating the configuration of the C-ONU according to the first embodiment. FIG. 4 is a diagram illustrating a configuration of the C-OLT according to the first embodiment. FIG. 5 is a diagram illustrating a configuration of the switching unit according to the first embodiment. FIG. 6 is a sequence diagram showing a flow of switching processing in the PON system according to the first embodiment. FIG. 7 is a sequence diagram showing a flow of switching processing in the PON system according to the first embodiment. FIG. 8 is a sequence diagram showing a flow of switching processing in the PON system according to the first embodiment. FIG. 9 is a diagram illustrating a configuration of a PON system according to a modification. FIG. 10 is a diagram illustrating a configuration of a PON system according to a modification. FIG. 11 is a diagram illustrating a configuration of a PON system according to a modification. FIG. 12 is a diagram illustrating a configuration of the C node according to the second embodiment. FIG. 13 is a diagram illustrating a configuration of a switching unit according to the second embodiment. FIG. 14 is a flowchart illustrating a flow of a C node switching process according to the second embodiment. FIG. 15 is a flowchart illustrating a flow of C node switching processing according to the second embodiment. FIG. 16 is a diagram illustrating the configuration of the C node according to the third embodiment. FIG. 17 is a diagram illustrating a configuration of a switching unit according to the third embodiment. FIG. 18 is a diagram illustrating a configuration of a connection unit according to the third embodiment. FIG. 19 is a flowchart illustrating a flow of a C node switching process according to the third embodiment. FIG. 20 is a flowchart illustrating a flow of a C node switching process according to the third embodiment. FIG. 21 is a diagram illustrating the configuration of the C node according to the fourth embodiment. FIG. 22 is a diagram illustrating a configuration of the C node according to the fifth embodiment. FIG. 23 is a diagram illustrating the configuration of the C node according to the sixth embodiment. FIG. 24 is a diagram illustrating a configuration of a switching unit according to the sixth embodiment. FIG. 25 is a diagram illustrating a configuration of the C node according to the seventh embodiment. FIG. 26 is a diagram illustrating a configuration of a switching unit according to the seventh embodiment. FIG. 27 is a diagram illustrating a configuration of the C node according to the eighth embodiment. FIG. 28 is a diagram illustrating a configuration of a C-ONU according to the eighth embodiment. FIG. 29 is a diagram illustrating the configuration of the C node according to the ninth embodiment. FIG. 30 is a diagram illustrating a configuration of the C-OLT according to the ninth embodiment. FIG. 31 is a diagram illustrating an example of a PON system. FIG. 32 is a diagram illustrating an example of a cascade PON system.

  Hereinafter, embodiments of a PON system according to the present application will be described in detail with reference to the drawings. Note that the PON system according to the present application is not limited by this embodiment.

[First Embodiment]
In the following embodiments, the configuration of the PON system according to the first embodiment, the configuration of the C node, and the overall processing flow of the PON system will be described in order, and finally the effects of the first embodiment will be described. To do.

[Configuration of PON system]
The PON system 1 includes a first PON in which a communication device (for example, a C node) is connected to a plurality of upper terminal devices (for example, OLT and C nodes), and a communication device that is a lower terminal device (for example, an ONU or C node). And a second PON connected to the PON system. With respect to this point, the configuration of the PON system 1 according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of a PON system 1 according to the first embodiment. PON system 1, as shown in FIG. 1, a plurality of OLT 10 ₁ to 10 _2, and a plurality of _{ONUs 30} 21 _{to 30 2m,} a plurality of C nodes ₅₀ 11 _{to 50 1n} and _{50 21,} a plurality of optical splitters 70 ₁ and a 70 _3.

In the example of FIG. 1, the PON system 1 includes a first PON in which a C node 50 ₁₁ (corresponding to a communication device) is connected to a plurality of OLTs 10 ₁ to 10 ₂ (corresponding to an upper terminal device), and a C node 50 _11. Is a multi-stage PON system having a plurality of ONUs 30 ₂₁ to 30 _2m (corresponding to a low-order terminal device) and a second PON connected thereto. In the PON system 1, the C node 50 ₁₁ forms a plurality of optical transmission lines 20 _{1 to} 20 ₂ with a plurality of OLTs 10 ₁ to 10 ₂ .

In the _{following, OLT10 1 ~10 2, ONU30 21} ~30 2m, C node ₅₀ 11 _{to 50 1n} and _{50 21,} an optical splitter ₇₀ 1-70 _3, when no light transmission path ₂₀ 1 to 20 ₂ individually distinguished Are sometimes referred to as OLT 10, ONU 30, C node 50, optical splitter 70, and optical transmission line 20.

  In the PON system 1, a plurality of OLTs 10 perform point-to-multipoint communication with a plurality of ONUs 30 via an optical transmission line. For example, in the PON system 1, the downstream signals transmitted from the OLT 10 to each ONU 30 are multiplexed using wavelength division multiplexing (WDM) technology or time division multiplexing (TDM) technology, and all the ONUs 30 connected to the OLT 10 are connected. Alternatively, it is a multistage PON system in which PONs having at least one downstream wavelength that can be received in common by some ONUs 30 are connected in multiple stages.

In the example of FIG. 1, PON system 1 has a lower optical splitter 70 ₁ only node C, to a lower optical splitter 70 ₁ may have a ONUs 30. Further, the lower C nodes _{50 21,} there may be C node 50 and ONUs 30. Further, the upper terminal apparatus is not limited to the OLT 10 and may be the C node 50.

  The OLT 10 is a device placed on the station side for terminating an optical signal from the ONU 30 installed on the subscriber side and transferring the signal to various service nodes. For example, the OLT 10 is a center-installed conversion device between node-side electrical signals such as video, telephone, and LAN and optical signals. As an example, the OLT 10 forms a plurality of optical transmission lines 20 with each of a plurality of C nodes 50 subordinate to the OLT 10.

  The ONU 30 is a device placed on the subscriber side in order to terminate the optical signal from the OLT 10 installed on the station side and transfer the signal to various service nodes. For example, the ONU 30 performs conversion between a transmission signal on an optical fiber and a transmission signal corresponding to various terminal devices such as a telephone.

  The C node 50 is a node device that connects a PON and another PON so that they can communicate with each other. Specifically, the C node 50 has a function of communicating with the OLT 10 or the C node 50 located at a higher position than the C node 50. Further, the C node 50 has a function of communicating with the ONU 30 or the C node 50 located at a lower position than the C node 50.

  The optical splitter 70 is a component for equally distributing optical signals in order to share the OLT 10 among a plurality of users in the PON system 1 used for optical access. The optical splitter 70 is formed by connecting, for example, Y-shaped PLC (Planar Lightwave Circuit) waveguides in a tree shape.

In the example of FIG. 1, a plurality of OLT 10 ₁ to 10 _2, and a plurality of _{ONUs 30} 21 _{to 30 2m,} a plurality of node C ₅₀ 11 _{to 50 1n} and _{50 21,} via a plurality of optical splitters ₇₀ 1 to 70 ₃ Connected. Specifically, C node _{50 11,} via the optical splitter 70 _1, to form an optical transmission line 20 ₁ with the OLT 10 _1. Also, C node _{50 11,} via the optical splitter 70 _2, to form the optical transmission line 20 ₂ with the OLT 10 _2. In other words, C node ₅₀ 11 is connected the other OLT 10 ₂ both non OLT 10 _1, belonging to a plurality of OLT 10 ₁ to 10 _2. Ie, C node _{50 11,} as a redundant path, to form the optical transmission path 20 ₂ from the optical splitter 70 ₂ between the OLT 10 _2. Incidentally, C node 50 ₁₁ is not limited to the example of FIG. 1, it may be formed a plurality of redundant paths.

In the PON system 1, a plurality of OLTs 10 ₁ to 10 ₂ share the situation with each other. For example, a higher-level device of the main system OLT 10 ₁ via the network 5, to share OLT 10 ₂ and the C-node _{50 11} information such as link status and fault status is a secondary system host device in real time. Accordingly, in the PON system 1, for example, when a failure occurs in OLT 10 _1, it is possible to switch the communication route to the OLT 10 _2.

Also, the C-node _{50 11,} via the optical splitter 70 _3, is connected to a plurality of _{ONUs 30} 21 _{to 30 2m} working under the C node _{50 11.} Also, the C-node _{50 11,} via the optical splitter 70 ₃ is connected to the C node _{50 21} working under. Thus, C node _{50 11} is connected in multiple stages. The number of branches by the plurality of optical splitters 70 ₁ to 70 ₃ is not limited to the example shown in FIG. 1, and may be branched to an arbitrary number.

  Thus, the PON system 1 has a redundant path between the C node 50 and the OLT 10. Thereby, since the PON system 1 can use a redundant path at the time of a failure, the reliability of the system can be improved. For example, since the PON system 1 provides a redundant path in a communication path where a failure is likely to occur, the reliability of the system can be efficiently increased.

[Configuration of C node]
The C node 50 is connected to a plurality of upper devices (corresponding to upper terminal devices) included in the first PON and lower devices (corresponding to lower terminal devices) included in the second PON. In this regard, the C node 50 according to the first embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating a configuration of the C node according to the first embodiment. As shown in FIG. 2, the C node 50 includes a cascade ONU (hereinafter referred to as “C-ONU 51”) 51, a cascade OLT 52 (hereinafter referred to as “C-OLT 52”), and a switching unit 53. Have.

The C-ONU 51 is a communication function unit on the subscriber side that is connected to the upper terminal apparatus via an optical transmission line. For example, the C-ONU 51 is connected to a plurality of higher-level devices 80 ₁ to 80 _n (for example, the OLT 10 and the C node 50) located above the C node 50 via the optical splitters 70 ₁ to 70 _n . For example, the C-ONU 51 forms optical transmission paths 20 _{1 to} 20 _n with the host devices 80 ₁ to 80 _n . In the following description, when the upper devices 80 ₁ to 80 _n are not distinguished from each other, they may be referred to as upper devices 80.

Further, C-ONU 51 via the optical splitter 70 _3, a plurality of lower devices ₉₀ 1 to 90 _n in from the C-node 50 to a lower position (eg, ONUs 30 and the C-node 50) is connected to. In the following, when the lower devices 90 _{1 to} 90 _n are not distinguished, they may be expressed as lower devices 90.

  Here, the configuration of the C-ONU 51 shown in FIG. 2 will be described in detail with reference to FIG. FIG. 3 is a block diagram showing a configuration of the C-ONU according to the first embodiment. As shown in FIG. 3, the C-ONU 51 includes a power supply unit 101, an external calculation processing unit 102, a storage unit 103, an additional function unit 104, a communication unit 105, a detection unit 106, and a notification unit 107. Have.

  The power supply unit 101 performs power supply control. For example, the power supply unit 101 controls power supply to the C-ONU 51. The external calculation processing unit 102 performs various calculations. For example, the external calculation processing unit 102 performs a calculation executed by an MPCP processing unit 110b described later. The storage unit 103 stores various types of information. For example, the storage unit 103 stores various types of firmware. The storage unit 103 is used as a buffer during frame processing in the PON signal processing unit 110 described later. The additional function unit 104 arbitrarily has various other functions. For example, the additional function unit 104 notifies an alarm when an error occurs in various processes in the PON signal processing unit 110 or the like. The C-ONU 51 may have other various functional units not shown.

The communication unit 105 communicates with various devices. Specifically, the communication unit 105 includes a plurality of communication units 105 via any one of the plurality of optical transmission lines 20 _{1 to} 20 _n to which the plurality of higher-level devices 80 ₁ to 80 _n and the C node 50 are connected. Communication with any one of the higher-level terminal devices among the higher-level devices 80 ₁ to 80 _n .

  For example, the communication unit 105 communicates with the OLT 10, another C node 50, the C-OLT 52, and the like. As an example, the communication unit 105 performs communication via any one of the plurality of optical transmission lines 20 formed between the OLT 10 and the other C node 50 that are higher than the C node 50. . In another example, the communication unit 105 communicates with the C-OLT 52 via the switching unit 53.

  As illustrated in FIG. 3, the communication unit 105 includes a C-OLT connection port 108, a PON-IF port 109, and a PON signal processing unit 110.

  The C-OLT connection port 108 and the PON-IF port 109 process signals from the outside. For example, the connection port 108 with the C-OLT transmits and receives signals to and from the C-OLT 52 via the switching unit 53. The PON-IF port 109 transmits and receives signals to and from the host device 80.

  The PON signal processing unit 110 controls processing for various signals (for example, frames) transmitted and received by the C node 50, for example. As shown in FIG. 3, the PON signal processing unit 110 includes an upstream signal processing unit 110a, an MPCP processing unit 110b, and a downstream signal processing unit 110c.

  For example, the upstream signal processing unit 110a reproduces an upstream burst signal. Further, the uplink signal processing unit 110a performs processing for converting a serial uplink signal into parallel. Further, the uplink signal processing unit 110a performs error correction on the uplink signal.

  For example, the MPCP processing unit 110b performs processing for notifying the timing of signal transmission. In addition, the MPCP processing unit 110b performs processing for a transmission timing request or inquiry received from a transmission request source (for example, the OLT 10 or the C node 50).

  For example, the downlink signal processing unit 110c reproduces a downlink burst signal. Further, the downlink signal processing unit 110c performs a process of converting a serial downlink signal into parallel. In addition, the downlink signal processing unit 110c performs error correction on the downlink signal.

The detection unit 106 monitors and detects a failure for an arbitrary part. Specifically, the detection unit 106 detects a failure in the optical transmission path connected to the external device. For example, the detection unit 106 detects a failure that has occurred in the plurality of optical transmission lines 20 _{1 to} 20 _n connected to the plurality of higher-level devices 80 ₁ to 80 _n . As an example, the detection unit 106 of the light transmission path ₂₀ 1 to 20 _n, for detecting a fault occurring in the optical transmission path 20 ₁ used in the communication. In another example, the detection unit 106 detects a failure that has occurred in the host device 80 or the optical splitter 70.

  The notification unit 107 notifies information related to a failure. For example, the notification unit 107 notifies the host device 80 of the failure information via the PON-IF port 109 when the detection unit 106 detects a failure. In another example, the notification unit 107 receives failure information via the connection port 108 with the C-OLT 52 and transmits the received failure information to the higher-level device 80. In another example, the notification unit 107 receives the failure information of the C-OLT 52 inbound or outbound, and transmits the received failure information to the higher-level device 80. Note that the notification unit 107 may receive failure information via an external communication line. Further, the notification unit 107 notifies the host device 80 of a communication path switching request when the communication path needs to be switched.

Returning to the description of FIG. 2, the C-OLT 52 is a communication function unit on the station side that is connected to the lower-level terminal device via an optical transmission line. For example, C-OLT52 via the optical splitter 70 _3, a plurality of lower devices ₉₀ 1 to 90 _n in from the C-node 50 to a lower position (eg, ONUs 30 and the C-node 50) is connected to.

  Here, the configuration of the C-OLT 52 shown in FIG. 2 will be described in detail with reference to FIG. FIG. 4 is a block diagram showing a configuration of the C-OLT according to the first embodiment. As shown in FIG. 4, the C-OLT 52 includes a power supply unit 111, an external calculation processing unit 112, a storage unit 113, an additional function unit 114, a communication unit 115, a detection unit 116, and a notification unit 117. Have.

  The power supply unit 111 performs power supply control. For example, the power supply unit 111 controls power supply to the C-OLT 52. The external calculation processing unit 112 performs various calculations. For example, the external calculation processing unit 112 performs a calculation executed by the MPCP processing unit 120b described later. The storage unit 113 stores various types of information. For example, the storage unit 113 stores various types of firmware. The storage unit 113 is used as a buffer during frame processing in the PON signal processing unit 120 described later. The additional function unit 114 arbitrarily has various other functions. For example, the additional function unit 114 notifies an alarm when an error occurs in various processes in the PON signal processing unit 120 or the like. Note that the C-OLT 52 may have other various functional units not shown.

The communication unit 115 communicates with various devices. Specifically, the communication unit 115 communicates with the lower order terminal device. For example, the communication unit 115 communicates with the lower devices 90 _{1 to} 90 _n (for example, the ONU 30 or the C node 50 at a lower position).

  As illustrated in FIG. 4, the communication unit 115 includes a PON-IF port 118, a connection port 119 to the C-ONU, and a PON signal processing unit 120.

  The PON-IF port 118 and the connection port 119 with the C-ONU process signals from the outside. For example, the PON-IF port 118 transmits and receives signals to and from the lower level device 90 belonging to the PON at the lower level. The connection port 119 with the C-ONU transmits / receives a signal to / from the C-ONU 51 in the apparatus located higher than the C-OLT 52.

  The PON signal processing unit 120 controls processing for various signals (for example, frames) transmitted and received by the C node 50, for example. As shown in FIG. 4, the PON signal processing unit 120 includes an upstream signal processing unit 120a, an MPCP processing unit 120b, and a downstream signal processing unit 120c.

  For example, the upstream signal processing unit 120a reproduces an upstream burst signal. Further, the upstream signal processing unit 120a performs processing for converting a serial upstream signal into parallel. Further, the uplink signal processing unit 120a performs error correction on the uplink signal.

  For example, the MPCP processing unit 120b performs a process of notifying the timing of signal transmission. In addition, the MPCP processing unit 120b performs processing for a transmission timing request or inquiry received from a transmission request source (for example, the C-ONU 51 or the lower-level device 90).

  For example, the downlink signal processing unit 120c reproduces a downlink burst signal. Further, the downlink signal processing unit 120c performs processing for converting a serial downlink signal into parallel. Further, the downlink signal processing unit 120c performs error correction on the downlink signal.

  The detection unit 116 monitors and detects a failure for an arbitrary part. Specifically, the detection unit 116 detects a failure in the optical transmission line connected to the external device. For example, the detection unit 116 detects a failure in an optical transmission line connected to the lower apparatus 90 (for example, the ONU 30 or the C node 50). In another example, the detection unit 116 detects a failure that has occurred in the subordinate device 90 or the optical splitter 70.

  The notification unit 117 notifies information related to the failure. For example, when the detection unit 116 detects a failure, the notification unit 117 notifies the C-ONU 51 of failure information via the connection port 119 with the C-ONU. In another example, the notification unit 117 notifies the failure information to the C-ONU 51 that connects the failure information inbound or outbound. Further, the notification unit 117 notifies the C-ONU 51 of a communication path switching request when the communication path needs to be switched.

The switching unit 53 switches the communication path according to the state of communication failure. Specifically, the switching unit 53 switches an optical transmission line used by the communication unit 125 described later to one of a plurality of optical transmission lines according to a failure state. For example, the switching unit 53 switches from a communication path in which a failure has occurred to another communication path in which no failure has occurred. As an example, the switching unit 53, when the optical transmission path 20 ₁ failure is detected that generated by the detection unit 126 to be described later, to switch from the optical transmission line 20 ₁ in the optical transmission line 20 _2. Thereby, since the switch part 53 can be connected with the other high-order apparatus 80, it can eliminate a communication failure and can continue communication.

  The configuration of the switching unit 53 shown in FIG. 2 will be described in detail with reference to FIG. FIG. 5 is a block diagram illustrating a configuration of the switching unit according to the first embodiment. As illustrated in FIG. 5, the switching unit 53 includes a power supply unit 121, an external calculation processing unit 122, a storage unit 123, an additional function unit 124, a communication unit 125, a detection unit 126, and a notification unit 127. Have.

  The power supply unit 121 performs power supply control. For example, the power supply unit 121 controls power supply to the switching unit 53. The external calculation processing unit 122 performs various calculations. For example, the external calculation processing unit 122 performs a calculation executed by a switching processing unit 130 described later. The storage unit 123 stores various types of information. For example, the storage unit 123 stores various types of firmware. The storage unit 123 is used as a buffer during frame processing in the switching processing unit 130 described later. The additional function unit 124 arbitrarily has various other functions. For example, the additional function unit 124 notifies an alarm when an error occurs in various processes in the switching processing unit 130 or the like. Note that the switching unit 53 may have other various functional units not shown.

  The communication unit 125 communicates with various functional units. Specifically, the communication unit 125 communicates with the C-ONU 51, the C-OLT 52, and the like. As illustrated in FIG. 5, the communication unit 125 includes a connection port 128 for C-OLT, a connection port 129 for C-ONU, an instruction unit 131, and a switching processing unit 130.

  The connection port 128 with the C-OLT transmits and receives signals to and from the C-OLT 52, for example. The connection port 129 with the C-ONU transmits and receives signals to and from the C-ONU 51, for example.

  The instruction unit 131 instructs switching processing. Specifically, the instruction unit 131 receives switching information for requesting switching of a communication path. Then, the instruction unit 131 transmits a switching instruction to the switching processing unit 130 when receiving the switching information. For example, the instruction unit 131 receives the switching information from the main C-ONU 51 via the connection port 129 with the C-ONU. Then, the instruction unit 131 transmits a switching instruction to the switching processing unit 130 based on the received switching information.

  The instruction unit 131 transmits and receives a switching status indicating a status related to switching of the communication path. Specifically, the instruction unit 131 receives the switching status from the switching processing unit 130. Then, the instruction unit 131 transmits the received switching status to the higher-level device 80 via the connection port 129 with the C-ONU.

  The switching processing unit 130 executes communication path switching processing. Specifically, the switching processing unit 130 executes communication path switching processing based on switching information received from the higher-level device 80 via the connection port 129 with the C-ONU. The reason why the switching process is executed in accordance with the instruction from the host apparatus 80 is because preparations such as a table rewriting process for changing the signal transmission destination on the host apparatus 80 side such as the OLT 10 can be made. For example, when the switching processing unit 130 receives a switching instruction from the instruction unit 131, the switching processing unit 130 switches the instructed communication path. Note that the switching processing unit 130 is not limited to the instruction from the higher-level device 80, and may switch the communication path at an arbitrary timing based on the failure information of the C node.

  The detection unit 126 performs failure monitoring and detection for an arbitrary part. Specifically, the detection unit 126 monitors the state of the connection port 128 with the C-OLT that is the processing unit in the conduction path of the main signal, the connection port 129 with the C-ONU, and the like, and a failure has occurred. Detect that.

  The notification unit 127 notifies information related to the failure. For example, when the detection unit 126 detects a failure, the notification unit 127 notifies the C-ONU 51 of failure information via the connection port 129 with the C-ONU. In addition, the notification unit 127 receives failure information from the C-ONU 51 inbound or outbound. Further, the notification unit 127 notifies the C-ONU 51 of a communication path switching request when the communication path needs to be switched.

  The failure detection is not limited to the C node 50 but may be performed by the OLT 10. Further, the upper device 80 may detect a communication failure with the lower device 90. In this case, for example, the C node 50 or the OLT 10 at a higher position switches from the communication path in which the failure has occurred to another communication path in which the failure has not occurred. Further, the lower device 90 may detect a communication failure with the upper device 80. In this case, for example, the C node 50 at a lower position switches from the communication path in which the failure has occurred to another communication path in which no failure has occurred.

[Processing procedure]
Next, the flow of switching processing in the PON system 1 according to the first embodiment will be described with reference to FIG. FIG. 6 is a sequence diagram showing a flow of switching processing in the PON system according to the first embodiment.

  In the example of FIG. 6, the main host device 80 (for example, the OLT 10 or the C node 50 at a higher position) that is actually communicating with the C node 50 at a position lower than the upper device 80 indicates a failure. If detected, communication using a redundant (secondary) communication path is started.

  Specifically, as shown in FIG. 6, the master host device 80 periodically transmits a failure status notification request to the master C node 50 that is actually communicating. For example, the master host device 80 communicates with the main C node 50 connected to the optical transmission line used for communication among the optical transmission lines connected to the master host device 80. A failure status notification request is transmitted (step S101).

  When the communication state is normal, the main C node 50 transmits a failure status notification indicating that the communication state is normal to the main host device 80 (step S102). Then, when receiving the failure status notification from the primary C node 50, the primary host device 80 transmits the failure status notification to the secondary host device 80 (step S103). When the communication status is normal, the master host device 80 and the master C node 50 repeatedly execute the above-described steps S101 to S103 every predetermined period.

  Thereafter, it is assumed that a failure has occurred in the main C node 50. In this case, the primary host device 80 first transmits a failure status notification request indicating the communication state to the primary C node 50 (step S104).

  Then, since a failure or the like occurs and the communication state is not normal, the primary C node 50 transmits a failure status notification for switching the communication path to the primary host device 80 (step S105). That is, when the main C node 50 detects a failure and determines that the path needs to be switched, the main C node 50 requests permission to switch the communication path from the upper host apparatus 80.

  Then, when receiving the failure status notification for switching the communication path, the primary host device 80 sends a failure status notification including a switching standby request for requesting switching to the secondary host device 80. Transmit (step S106). As a result, the subordinate host apparatus 80 prepares for switching.

  Further, the master host device 80 transmits a switching instruction for instructing switching of the communication path to the master C node 50 (step S107). In other words, the master host device 80 transmits a path switching instruction to the main C node 50 at an arbitrary timing, thereby causing the main C node 50 to switch the communication path.

  After that, when receiving the switching instruction, the primary C node 50 is connected to the optical transmission line connected to the secondary C node 50 that is not used for communication among the optical transmission lines connected to the higher-level device 80. The communication path is switched (step S108).

  Then, when the communication path is switched by the primary C node 50, the secondary C node 50 transmits a switching completion notification to the secondary host device 80 (step S109). That is, the secondary C node 50 notifies the secondary host device 80 of the execution result of the path switching control.

  Thereafter, the secondary higher-level device 80 transmits a failure status notification request to the secondary C node 50 (step S110). When the communication state is normal, the subordinate C node 50 transmits a failure status notification indicating that the communication state is normal to the subordinate higher-level device 80 (step S111). When the secondary host device 80 receives the failure status notification from the secondary C node 50, the secondary host device 80 transmits the failure status notification to the primary host device 80 (step S112). In other words, when the subordinate upper apparatus 80 successfully switches to the communication path of the subordinate C node 50, the subordinate upper apparatus 80 periodically sends a failure status notification request to the subordinate C node 50. Monitor and notify fault status.

  In the above switching process, the subordinate higher-level device 80 may instruct the switching. This point will be described with reference to FIG. FIG. 7 is a sequence diagram showing a flow of switching processing in the PON system according to the first embodiment.

  Specifically, the PON system 1 first executes processing similar to steps S101 to S106 shown in FIG. When the secondary host device 80 receives the failure status notification from the primary host device 80, the secondary host device 80 transmits a switching instruction to switch the communication path to the primary host device 80 (step S3). S127). Further, the subordinate higher-level device 80 transmits a switching instruction for instructing switching of the communication path to the main C-node 50 (step S128). Thereafter, the PON system 1 executes the same processing as steps S108 to S112 shown in FIG.

  In this way, in the PON system 1, the subordinate upper apparatus 80 issues a switching instruction. As a result, in the PON system 1, the secondary host device 80 can take the lead and execute the switching process. Therefore, a failure occurs in the primary host device 80 and the secondary host device 80 becomes the primary system. This is effective when communication is taken over instead of the host device 80.

  Further, the above switching process may be performed based on the determination by the C node 50. For example, the primary C node 50 in which a failure has occurred switches the communication path according to the judgment of the primary C node 50 when it is impossible or difficult to notify the host device 80 of a failure notification or a route switching request. Execute. This point will be described with reference to FIG. FIG. 8 is a sequence diagram showing a flow of switching processing in the PON system according to the first embodiment.

  Specifically, as shown in FIG. 7, the master host device 80 periodically transmits a failure status notification request to the master C node 50 that is actually communicating. For example, the master host device 80 communicates with the main C node 50 connected to the optical transmission line used for communication among the optical transmission lines connected to the master host device 80. A failure status notification request is transmitted (step S141).

  Then, when the communication state is normal, the main C node 50 transmits a failure status notification indicating that the communication state is normal to the main host device 80 (step S142). Then, when receiving the failure status notification from the primary C node 50, the primary host device 80 transmits the failure status notification to the secondary host device 80 (step S143). When the communication status is normal, the master host device 80 and the master C node 50 repeatedly execute the above-described steps S141 to S143.

  Thereafter, it is assumed that a failure has occurred that makes it impossible to transmit a failure notification or a route switching request notification to the main C node 50. In this case, first, the master host device 80 transmits a failure status notification request to the master C node 50 (step S144).

  Thereafter, the primary C node 50 detects a failure without transmitting a failure status notification to the primary host device 80 (step S145). Then, the main C node 50 does not transmit a failure status notification for switching the communication path to the higher-level device 80, and the sub-system that is not used for communication among the optical transmission paths connected to the higher-level device 80. The communication path is switched to the optical transmission path connected to the C node 50 (step S146).

  Then, when the communication path is switched by the primary C node 50, the secondary C node 50 transmits a switching completion notification to the secondary host device 80 (step S147). That is, the secondary C node 50 notifies the secondary host device 80 of the execution result of the path switching control.

  Thereafter, the subordinate higher-level device 80 transmits a failure status notification request to the subordinate C node 50 (step S148). When the communication state is normal, the subordinate C node 50 transmits a failure status notification indicating that the communication state is normal to the subordinate higher-level apparatus 80 (step S149). Then, when receiving the failure status notification from the secondary C node 50, the secondary host device 80 transmits the failure status notification to the primary host device 80 (step S150).

[Effect of the first embodiment]
As described above, the PON system 1 according to the first embodiment includes the first PON in which the C node 50 is connected to the plurality of higher-level devices 80 and the second PON in which the C node 50 is connected to the lower-level device 90. In the PON system having the PON, the C node 50 includes a plurality of host devices via any one of the plurality of optical transmission paths 20 to which the plurality of host devices 80 and the C node 50 are connected. 80, a communication unit 105 that communicates with any one of the higher-level devices, and a switching unit that switches an optical transmission line used by the communication unit 105 to any one of a plurality of optical transmission lines according to a failure state. 53.

  Thereby, since the PON system 1 which concerns on 1st Embodiment can eliminate a communication failure by switching communication to a redundant path when a communication failure generate | occur | produces, it can improve reliability. For example, since the PON system 1 can suppress the influence of the communication disabled state due to the failure of the host device or the failure of the optical transmission path below the optical splitter, the communication can be continued even if a communication failure occurs.

[Modification]
(Host device dedicated for backup)
In the above embodiment, the PON system 1 has an example in which the C node 50 has a first PON connected to a plurality of higher-level devices 80 and a second PON in which the C node 50 is connected to a lower-level device 90. Indicated. Here, the PON system 1 may have a host device dedicated for backup.

In this regard, the configuration of the PON system 2 according to the modification will be described with reference to FIG. FIG. 9 is a diagram illustrating a configuration of a PON system 2 according to a modification. As shown in FIG. 9, the PON system 2 includes a plurality of OLTs 10 ₁ to 10 _n , a plurality of C nodes 50 ₁₁ to 50 _1n, and a plurality of optical splitters 70 ₁ to 70 _n .

Here, OLT 10 ₂ is a higher-level apparatus 80 of the backup only. For example, OLT 10 ₂ is a higher-level apparatus 80 of the secondary system performing the actual backup OLT 10 ₁ and OLT 10 _n is a higher-level device 80 of the main system are communicating.

Specifically, OLT 10 ₂ via the optical splitter 70 _2, is connected to a plurality of C nodes ₅₀ 11 _{to 50 1n} belonging under the OLT 10 ₁ and OLT 10 _n. For example, OLT 10 ₂ via the optical splitter 70 _2, the optical transmission path ₂₀ 21 _{to 20 2n} sub system is formed with a plurality of C nodes ₅₀ 11 _{to 50 1n.} That, OLT 10 _2, as a PON sub system to back up OLT 10 ₁ and OLT 10 _n as a PON of the main system.

The secondary optical transmission paths 20 _{21 to} 202 _n may form a plurality of redundant paths with the C nodes 50 ₁₁ to 50 _{1 n} , respectively. For example, C node ₅₀ 11, a plurality of optical transmission paths may be formed not only the optical transmission line _{20 21} of the secondary system with the OLT 10 _2. Further, the secondary optical transmission lines 20 _{21 to} 202 _n may be connected to each C node in such a manner that a plurality of redundant paths of PONs are assumed at once.

As a result, the PON system 2 can secure a redundant path between the C nodes 50 ₁₁ to 50 _1n belonging to the other OLTs 10 ₁ to 10 _n by the sub system OLT 10 ₂ . A route can be constructed.

In the PON system 2, even when the C node 50 that requires multiple redundant paths into a single PON present, may be used OLT 10 ₂ forming the PON sub system described above. In this case, when the number of branches of the secondary PON is larger than that of the primary PON, an excess optical transmission path may be used as the optical transmission path of the secondary PON. If the number of branches of the secondary PON is smaller than that of the primary PON, the secondary PON may be configured by sharing a plurality of secondary host devices.

(Construction of sub system by extra optical transmission line)
In the above modification, the PON system 2 has an example having a host device dedicated for backup. Here, the PON system 2 may construct a subordinate host device using an extra optical transmission line.

In this regard, the configuration of the PON system 3 according to the modification will be described with reference to FIG. FIG. 10 is a diagram illustrating a configuration of a PON system 3 according to a modification. PON system 3, as shown in FIG. 10, it has a plurality of OLT 10 ₁ to 10 _2, a plurality of node C ₅₀ 11 _{to 50 1n,} a plurality of the optical splitters ₇₀ 1 to 70 _2.

Specifically, OLT 10 ₁ via the optical splitter 70 ₁ is connected to a plurality of C-node _{50 11-50 12} belonging under the OLT 10 _1. For example, OLT 10 ₁ via the optical splitter 70 _1, the optical transmission line ₂₀ 11 _{to 20 1n} the secondary system is formed between the plurality of C-node _{50 11-50 12.}

OLT 10 ₂ via the optical splitter 70 ₂ is connected to the C node _{50 1n} belonging under the OLT 10 _2. For example, OLT 10 ₂ via the optical splitter 70 _2, the optical transmission path _{20 2n} are formed between the C node _{50 1n.}

Further, OLT 10 ₂ is connected to the C node _{50 12} belonging under the OLT 10 _1. For example, OLT 10 ₂ via the optical splitter 70 _2, the optical transmission line 20 _S is formed between the C node _{50 12.} That, OLT 10 _2, together with the C-node ₅₀ the main system of the host apparatus _1n belonging under the OLT 10 _2, operates as a secondary system of a host device C nodes _{50 12} belonging under the OLT 10 _1.

  As a result, the PON system 3 can construct a subordinate higher-level device using an extra optical transmission line, and can efficiently provide a subordinate redundant route. For example, the PON system 3 constructs a secondary redundant path at a lower cost without separately constructing a backup dedicated host device by using an excess optical transmission path of a host device that mainly performs communication. be able to.

(Multiple redundant routes)
In the above embodiment, the PON system 1 has an example in which the C node 50 has a first PON connected to a plurality of higher-level devices 80 and a second PON in which the C node 50 is connected to a lower-level device 90. Indicated. Here, in the PON system 1, the C node 50 may be connected to the host device 80 by a plurality of redundant paths.

In this regard, the configuration of the PON system 4 according to the modification will be described with reference to FIG. FIG. 11 is a diagram illustrating a configuration of a PON system 4 according to a modification. PON system 4, as shown in FIG. 11, a plurality of OLT 10 ₁ to 10 _2, and a plurality of _{ONUs 30} 21 _{to 30 2m,} a plurality of node C ₅₀ 11 _{to 50 1n} and _{50 21,} a plurality of optical splitters 70 ₁ It is connected via a 70 _3.

Specifically, the C node 50 ₁₁ forms a plurality of optical transmission lines 20 _1n and optical transmission lines 20 _b with the OLT _{10 1} via the optical splitter 70 ₁ . Also, C node _{50 11,} via the optical splitter 70 _2, to form the optical transmission line 20 _S between the OLT 10 _2. That is, in the example of FIG. 11, C node ₅₀ 11, in addition to the optical transmission line 20 _S is a redundant path between the optical transmission line _{20 1n} and OLT 10 ₂ between the OLT 10 _1, the optical transmission line 20 Further redundant paths are formed by _b .

  As a result, the PON system 4 forms a plurality of redundant paths with the host device, so that communication reliability can be further improved. For example, the PON system 4 has a failure in the optical transmission path at the lower stage of the optical splitter connected to the upper system of the main system with which the C node is mainly communicating, or a failure in the communication unit with the upper side apparatus of the C node. When this occurs, communication disconnection can be avoided. In addition, since the PON system 4 switches to a redundant path without changing the host device with which the C node communicates, the PON system 4 can be used in the same device as compared with the case where the optical transmission path is switched to another host device to restore communication. The switch can be completed. For this reason, the PON system 4 can simplify the switching procedure and switching process on the upper apparatus side. Therefore, the PON system 4 can select a suitable switching means and route according to the degree of failure by using a plurality of redundant route selection means.

[Second Embodiment]
In the first embodiment described above, the case where the C node 50 includes one C-ONU 51 has been described. However, the C node 50 may include a plurality of C-ONUs 51. Specifically, the C node 250 according to the second embodiment includes a plurality of C-ONUs 251 _{11 to} 251 _nn connected to a plurality of higher-level devices 80 ₁ to 80 _n via the optical transmission line 20, and a plurality of C-ONUs 251 _{11 to} 251 _nn . C-ONUs 251 _{11 to} 251 _{nn and} a C-OLT 52 connected to a lower level device 90 included in the second PON is further included in the C node 250, and the communication unit 225 includes C C communicates with any _{one of the} plurality of higher-level devices 80 ₁ to 80 _n included in the first PON via any one of the plurality of C-ONUs 251 _{11 to} 251 _nn included in the node 250, and the C included in the C node 250 communicates with the lower device ₉₀ 1 to 90 _n included in the second PON via -OLT52, switching unit 253, C-O having the C node 250 in response to a failure situation By switching the connection with either T52 and the plurality of _C-ONU251 11 ~251 _nn, any of the plurality of _C-ONU251 11 ~251 plurality of host systems ₉₀ 1 to 90 _n included in the first PON of _nn Switch the C-ONU that communicates with Koka. This point will be described in detail with reference to FIG. In the following, functional units that exhibit the same functions as those in the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

[Configuration of C node]
FIG. 12 is a diagram illustrating a configuration of the C node 250 according to the second embodiment. As illustrated in FIG. 12, the C node 250 includes a plurality of C-ONUs 251 _{11 to} 251 _nn , a C-OLT 52, and a switching unit 253. In the following, C-ONUs 251 _{11 to} 251 _nn may be referred to as C-ONUs 251 respectively.

The plurality of C-ONUs 251 _{11 to} 251 _nn have the same functions as the C-ONU 51 according to the first embodiment. In addition, the plurality of C-ONUs 251 _{11 to} 251 _nn are optically transmitted via the optical splitter 70 and the primary or secondary host devices 80 ₁ to 80 _n (for example, the OLT 10 or the C node 250 at a higher position). Connected by way 20.

The switching unit 253 is connected to the plurality of C-ONUs 251 _{11 to} 251 _nn and the C-OLT 52. Then, the switching unit 253 switches communication paths that connect the plurality of C-ONUs 251 _{11 to} 251 _nn and the C-OLT 52. This point will be described with reference to FIG.

  FIG. 13 is a diagram illustrating a configuration of the switching unit 253 according to the second embodiment. As illustrated in FIG. 13, the switching unit 253 is different from the switching unit 53 illustrated in FIG. 5 in that it includes a communication unit 225 and a detection unit 226.

The communication unit 225 communicates with the higher-level devices 80 ₁ to 80 _n included in the first PON via any one of the plurality of C-ONUs 251 _{11 to} 251 _nn included in the C node 250. Communication is performed with the lower-level devices 90 _{1 to} 90 _n included in the second PON via the C-OLT 52 having the same. Specifically, the communication unit 225 includes connection ports 229 _{1 to} 229 _n with a plurality of C-ONUs, a switching processing unit 230, and an instruction unit 231 as compared with the communication unit 125 illustrated in FIG. The point is different. Connection ports 229 _{1 to} 229 _n with a plurality of C-ONUs are connected to a plurality of C-ONUs 251 _{11 to} 251 _nn , respectively. Thereby, the connection ports 229 _{1 to} 229 _n with the plurality of C-ONUs communicate with the plurality of C-ONUs 251 _{11 to} 251 _nn , respectively.

Switching processor 230, by switching the connection with either C-OLT52 and a plurality of _C-ONU251 11 ~251 _nn having the C node 250 in response to a failure situation, a plurality of _C-ONU251 11 ~251 _nn Among them, the C-ONU that communicates with the higher-level devices 80 ₁ to 80 _n included in the first PON is switched. Specifically, the switching processing unit 230, when a failure is detected in the main C-ONU 251 that is being used for communication, preliminary conduction that enables signal communication with the OLT 10 or the C node 50 that is in a higher position. The connection is switched to another C-ONU as a route. Thereby, the switching processing unit 230 can maintain communication even when a failure occurs in the C-ONU being used.

The instruction unit 231 is different from the instruction unit 131 in that it receives switching information from the C-ONUs 251 _{11 to} 251 _nn via the connection ports 229 _{1 to} 229 _n with the C-ONU. The instruction unit 231 is different from the instruction unit 131 in that the received switching status is transmitted to the C-ONUs 251 _{11 to} 251 _nn via the connection ports 229 _{1 to} 229 _n with the C-ONU.

The detection unit 226 monitors and detects a failure for an arbitrary part. Specifically, the detection unit 226 includes a connection port 128 to the C-OLT that is a processing unit on the conduction path of the main signal, connection ports 229 _{1 to} 229 _n to the C-ONU, the switching processing unit 230, and the like. Monitor the status of and detect that a failure has occurred. The detection unit 226 detects a failure in the optical transmission line connected to the external device. For example, the detection unit 226 detects a failure that has occurred in the C-OLT 52 or the C-ONUs 251 _{11 to} 251 _nn . The detection unit 226 may detect a failure of each unit in the apparatus. For example, the detection unit 226 detects a failure that has occurred in the power supply unit 121, the external calculation processing unit 122, the storage unit 123, the additional function unit 124, the communication unit 225, and the notification unit 127.

[Processing procedure]
Next, with reference to FIG. 14, a description will be given of the flow of switching processing when the host device 80 (for example, the OLT 10 or the host C node 250) performs the switching instruction. For example, when the failure is about to occur but the communication is possible, the higher-level device 80 performs the switching instruction. FIG. 14 is a flowchart showing a flow of switching processing in the C node 250 according to the second embodiment.

  For example, as shown in FIG. 14, the upper device 80 determines whether or not a failure detection or switching request has been received from the lower C node 250 (step S201). Here, when receiving a failure detection or switching request (step S201; present), the higher-level device 80 determines whether communication can be taken over to another higher-level device (for example, the OLT 10 connected to the redundant path). Determination is made (step S202).

  Here, when it is determined that the communication can be taken over to the OLT 10 connected to the redundant path (step S202; Yes), the higher-level device 80 transmits a switching instruction to switch the communication path to the redundant path to the C node 250 ( Step S203).

  Thereafter, the host device 80 determines whether or not a switching completion notification has been received from the C node 250 (step S204). Here, when it is determined that the switching completion notification has been received from the C node 250 (step S204; success), the host device 80 completes the path switching process (step S205).

  On the other hand, when the host device 80 has not received a failure detection or switching request (step S201; no or unnecessary), the host device 80 determines whether or not communication with the C node 250 is possible (step S206). Here, if the upper device 80 determines that communication with the C node 250 is possible (step S206; acceptable), it maintains the communication path (step S208). Further, even when the host device 80 determines that communication cannot be taken over by the redundant OLT 10 (step S202; impossibility), it maintains the communication path (step S208). Even when the host device 80 determines that the switch completion notification has not been received from the C node 250 (step S204; no or failure), the host device 80 maintains the communication path (step S208).

  Thereafter, the higher-level device 80 executes Step S201 again. If it is determined that communication with the C node 250 is not possible (step S206; impossibility), the host device 80 executes a C node subject switching process described later (step S207).

  Note that the host device 80 may stop the switching process when the switching process is repeatedly executed any number of times. Further, the host device 80 independently issues a switching instruction when periodic status notification from the C node 250 is lost or when it is determined that notification from the C node 250 to the host device 80 is difficult due to a failure. You may go.

  Further, the switching process is not limited to the upper apparatus 80 such as the OLT 10 and the upper C node 250 but may be performed mainly by the lower C node 250. For example, the C node 250 executes the switching process itself when it is difficult to receive a switching instruction from the host device 80 in a situation where a failure has occurred, or when the switching instruction is unnecessary. This point will be described in detail with reference to FIG. FIG. 15 is a flowchart showing a flow of switching processing in the C node 250 according to the second embodiment.

  For example, as shown in FIG. 15, the C node 250 determines whether or not a failure has been detected (step S210). Here, when the C node 250 detects a failure (step S210; acceptable), the C node 250 determines whether communication with the higher-level device 80 is possible (step S211). If it is determined that communication with the host device 80 is possible (step S211; yes), the switching process of the host device 80 main body shown in FIG. 14 is executed (step S213).

  On the other hand, when it is determined that communication with the host device 80 is impossible or unnecessary (step S211; impossible or unnecessary), the C node 250 determines whether communication can be taken over to the OLT 10 connected to the redundant path. (Step S214). Here, when the C node 250 determines that communication can be taken over to the OLT 10 connected to the redundant path (step S214; Yes), the C node 250 executes path switching control (step S215).

  Thereafter, the C node 250 determines the switching result (step S216). Here, when the C node 250 determines that the switching is successful (step S216; success), the C node 250 transmits a switching completion notification to the higher-level device 80 (step S218). Then, the lower C node 250 completes the path switching (step S219).

  On the other hand, when it is determined that the switching has failed (step S216; failure), the C node 250 transmits a switching failure notification (step S220). Then, the C node 250 maintains the communication path (step S221).

  Note that the C node 250 maintains the communication path even when it is determined that communication cannot be taken over to the OLT 10 connected to the redundant path (step S214; NO) (step S221). Also, the C node 250 maintains the communication path (step S221) even when no failure is detected (step S210; no). Thereafter, the C node 250 executes Step S210 again. Note that the C node 250 may stop the switching process when the switching process is repeatedly executed any number of times.

[Effect of the second embodiment]
As described above, the C node 250 according to the second embodiment includes a plurality of C-ONUs 251 _{11 to} 251 _nn connected to the plurality of higher-level apparatuses 80 ₁ to 80 _n via the optical transmission line 20, and a plurality of A C-OLT 52 connected to any one of the C-ONUs 251 _{11 to} 251 _nn and connected to the lower level device 90 included in the second PON is further included in the C node 250, and the communication unit 225 includes a C node The C-node included in the C node 250 communicates with any of the plurality of higher-level devices 80 ₁ to 80 _n included in the first PON via any one of the plurality of C-ONUs 251 _{11 to} 251 _nn included in the C node 250. communicates with the lower device ₉₀ 1 to 90 _n included in the second PON via the OLT52, switching unit 253, C-O having the C node 250 in response to a failure situation By switching the connection with either T52 and the plurality of _C-ONU251 11 ~251 _nn, any of the plurality of _C-ONU251 11 ~251 plurality of host systems ₉₀ 1 to 90 _n included in the first PON of _nn Switch the C-ONU that communicates with Koka.

  As a result, the C node 250 according to the second embodiment has a communication failure due to a failure of the main C-ONU, an optical transmission line connected from the upper optical splitter to the C-ONU is disconnected or deteriorated, etc. When a communication failure occurs due to the communication, the communication path can be switched, so that the communication can be continued. For example, the C node 250 according to the second embodiment can recover communication by switching to the C-ONU 251 that can communicate with the host device 80.

  In addition, since the C node 250 according to the second embodiment has a single C-OLT 52, the upper PON section is required to have higher reliability than the lower PON section, and This is suitable when low cost is required in the lower PON section. For example, in the C node 250 according to the second embodiment, a communication company that prioritizes reliability manages the upper PON section, and an administrator such as an apartment house that prioritizes low cost manages the lower PON section. Suitable for etc.

  In addition, the C node 250 according to the second embodiment can simplify the switch configuration of the path switching unit by reducing the number of C-OLTs 52 included in the C node 250, so that components to be used The score can be reduced. For this reason, the C node 250 according to the second embodiment can reduce the cost of the C node 250.

[Third Embodiment]
In the second embodiment, the case where the C node 250 includes one C-OLT 52 has been described. However, the C node 250 may include a plurality of C-OLTs 52. Specifically, the C node 350 according to the third embodiment is connected to any of the plurality of C-ONUs 251 _{11 to} 251 ₂₁ , and is connected to the lower devices 90 _{1 to} 90 _n included in the second PON and the light. The C node 350 further includes a plurality of C-OLTs 352 _{1 to} 352 _n connected via the transmission line 20, and the communication unit 325 is connected to the second via any _{one of the} plurality of C-OLTs 352 _{1 to} 352 _n . It communicates with the lower device ₉₀ 1 to 90 _n included in the PON of the switching unit 353, and one of the plurality of C-OLT352 ₁ ~352 _n having the C node 350 in response to a failure situation C-ONU251 ₁₁ ~ by switching the connection with the 251 _nn, C that communicates with the lower device ₉₀ 1 to 90 _n included in the second PON of the plurality of C-OLT352 ₁ ~352 _n Switching the OLT.

[Configuration of C node]
FIG. 16 is a diagram illustrating a configuration of the C node 350 according to the third embodiment. C node 350 is connected with one of a plurality of _C-ONU251 11 ~251 _nn, a plurality of C-OLT352 ₁ connected through the lower apparatus 90 and the optical transmission line included in the second PON ～352 _n is further in C node 350. Specifically, as illustrated in FIG. 16, the C node 350 includes a plurality of C-OLTs 352 _{1 to} 352 _n , a switching unit 353, and a connection unit 354, as compared to the C node 250 illustrated in FIG. It has different points. Hereinafter, the plurality of C-OLTs 352 _{1 to} 352 _n may be referred to as a plurality of C-OLTs 352, respectively.

The plurality of C-OLTs 352 _{1 to} 352 _n have the same functions as the C-OLT 52 according to the second embodiment. Further, the plurality of C-OLTs 352 _{1 to} 352 _n are connected to a lower level device 90 (for example, the ONU 30 or the C node 350) located at a lower level than the C node 350. The plurality of C-OLTs 352 _{1 to} 352 _n are connected to the connection unit 354, respectively. The plurality of C-OLTs 352 _{1 to} 352 _n are connected to an optical transmission line at a lower position through an optical coupler, an optical switch, or an optical filter. Accordingly, the plurality of C-OLTs 352 _{1 to} 352 _n communicate with the lower level device 90.

In this embodiment, since a plurality of C-ONUs 251 _{11 to} 251 _nn are mounted in the C node 350, the main system (operation system) used for communication among the plurality of C-ONUs 251 _{11 to} 251 _nn. The C-ONU notifies the failure information and the switching instruction. Further, when communication is difficult in the main (active) C-ONU, another communicable C-ONU may notify the upper terminal apparatus of failure information and a switching instruction.

The switching unit 353 is connected to the plurality of C-ONUs 251 _{11 to} 251 _nn and the plurality of C-OLTs 352 _{1 to} 352 _n . Then, the switching unit 353 switches communication paths that connect the plurality of C-ONUs 251 _{11 to} 251 _nn and the plurality of C-OLTs 352 _{1 to} 352 _n . This point will be described with reference to FIG.

  FIG. 17 is a diagram illustrating a configuration of the switching unit 353 according to the third embodiment. As illustrated in FIG. 17, the switching unit 353 is different from the switching unit 253 illustrated in FIG. 13 in that the communication unit 325 is included.

The communication unit 325 communicates with the lower device 90 included in the second PON via any of the plurality of C-OLTs 352 _{1 to} 352 _n . Specifically, the communication unit 325 is different from the communication unit 225 illustrated in FIG. 13 in that the communication unit 325 includes connection ports 328 _{1 to} 328 _n with a plurality of C-OLTs and a switching processing unit 330. Connection ports 328 _{1 to} 328 _n with a plurality of C-OLTs are connected to the main C-OLT and the sub C-OLT.

  Specifically, the switching unit 353, when a failure is detected in the main C-ONU or C-OLT that is being used for communication, other C-ONUs that are standby conduction paths through which signals can be communicated. Or switch the connection to C-OLT. Thereby, the switching unit 353 can maintain communication even when a failure occurs in the C-ONU or C-OLT in use.

  Here, when switching the C-OLT, the switching unit 353 causes the downstream optical signal from the C-OLT before switching to a lower position in order to normally communicate with the C-OLT after switching and the lower-level device 90. A certain ONU 30 or C node 350 is prevented from receiving. For example, the switching unit 353 stops the C-OLT downstream optical signal before switching. In this case, the switching unit 353 connects the plurality of C-OLTs 352 with an optical coupler, and connects the plurality of C-OLTs 352 to an optical transmission line at a lower position.

  In addition, the optical signal to the lower stage (downstream optical signal) may not be stopped due to a failure of the C-OLT or the like. In this case, for example, by using an optical switch that can connect the lower optical transmission line to an arbitrary C-OLT, an optical signal (downstream optical signal) to the lower stage of the failed C-OLT is eliminated.

The connection unit 354 connects the plurality of C-ONUs 251 _{11 to} 251 _nn and the lower devices 90 located at positions lower than the plurality of C-OLTs 352 _{1 to} 352 _n through an optical transmission line. For example, the connection unit 354 connects the lower device 90 (for example, the ONU 30 or the C node 350) located at a position lower than the C node 350 and a plurality of C-OLTs 352 _{1 to} 352 _n to make the optical signal conductive. This point will be described with reference to FIG.

  FIG. 18 is a diagram illustrating a configuration of the connection unit 354 according to the third embodiment. As shown in FIG. 18, for example, when an optical switch is used, the connection unit 354 includes a power supply unit 331, an external calculation processing unit 332, a storage unit 333, an additional function unit 334, and a communication unit 335. , A detection unit 336 and a notification unit 337.

  The power supply unit 331 performs power supply control. For example, the power supply unit 331 controls power supply to the connection unit 354. The external calculation processing unit 332 performs various calculations. For example, the external calculation processing unit 332 performs a calculation executed by a switching processing unit 340 described later. The storage unit 333 stores various types of information. For example, the storage unit 333 stores various types of firmware. The storage unit 333 is used as a buffer during frame processing in the switching processing unit 340 described later. The additional function unit 334 arbitrarily has various other functions. For example, the additional function unit 334 notifies an alarm when an error occurs in various processes in the switching processing unit 340 or the like. Note that the connection unit 354 may have other various functional units not shown.

The communication unit 335 communicates with various devices. Specifically, the communication unit 335 communicates with the lower device 90 included in the second PON via any _{one of the} plurality of C-OLTs 352 _{1 to} 352 _n . For example, the communication unit 335 communicates with the OLT 10, the other C node 350, the C-OLT 352, and the like. As illustrated in FIG. 14, the communication unit 335 includes an optical port 338, optical ports 339 _{1 to} 339 _n , a switching processing unit 340, and an instruction unit 341.

The optical port 338 and the optical ports 339 _{1 to} 339 _n process signals from the outside. For example, the optical port 338 transmits and receives signals to and from the lower device 90. The optical ports 339 _{1 to} 339 _n transmit and receive signals to and from the switching unit 353 and the C-OLTs 352 _{1 to} 352 _n .

  The instruction unit 341 instructs switching processing. For example, the instruction unit 341 receives switching information from the switching unit 353 or the C-OLT that is actually performing communication. Then, the instruction unit 341 transmits a switching instruction to the switching processing unit 340 based on the received switching information.

The switching processing unit 340 switches the connection between any _{one of the} plurality of C-OLTs 352 _{1 to} 352 _n included in the C node 350 and the lower-level device 90 according to the failure status, so that the plurality of C-OLTs 352 _{1 to} 352 _n Among them, the C-OLT that communicates with the lower level device 90 included in the second PON is switched. Specifically, the switching processing unit 340 interlocks with the switching unit 353 to ensure a communication path between the C-OLT and the lower-level device 90. For example, the switching processing unit 340 selects an optical path so that the selected C-OLT and the lower device 90 can communicate with each other. As an example, when the switching processing unit 340 receives a switching instruction from the instruction unit 341, the switching processing unit 340 performs switching of the instructed communication path.

  Here, the switching processing unit 340 may switch the communication path based on switching information from the C-OLT. Further, the switching processing unit 340 may switch the communication path based on the switching information from the switching unit 353.

  The detection unit 336 monitors and detects a failure for an arbitrary part. Specifically, the detection unit 336 monitors the state of the communication path and detects that a failure has occurred in the communication path. For example, the detection unit 336 detects a failure that has occurred in a communication path connected to the C-ONU 251 or the C-OLT 352.

  The notification unit 337 notifies information related to the failure. Specifically, the notification unit 337 transmits failure information to the C-OLT 352 or the switching unit 353 when the detection unit 336 detects a failure. Note that the notification unit 337 may transfer the switching request information when the optical path needs to be switched.

[Processing procedure]
Next, the flow of switching processing in which the host device 80 (for example, the OLT 10 or the upper C node 350) performs processing will be described with reference to FIG. FIG. 19 is a flowchart showing a flow of switching processing in the C node 350 according to the third embodiment.

  For example, as shown in FIG. 19, the upper device 80 determines whether or not a failure detection or switching request has been received from the lower C node 350 (step S301). Here, when the host device 80 has not received a failure detection or switching request (step S301; no or unnecessary), the host device 80 determines whether or not communication with the C node 350 is possible (step S302). If the host device 80 determines that communication with the C node 350 is not possible (step S302; impossibility), the host device 80 performs a switching process of the C node 350 as described later (step S303).

  On the other hand, when it is determined that communication with the C node 350 is possible (step S302; acceptable), the higher-level device 80 maintains the communication path (step S304). Thereafter, the higher-level device 80 executes Step S301 again.

  Further, when receiving a failure detection or switching request (step S301; present), the higher-level device 80 determines whether communication can be taken over to another higher-level device (for example, an OLT connected to a redundant path). (Step S305). Note that information regarding whether or not to switch to another higher-level device may be acquired in advance regardless of the switching request from the C node. Further, whether or not it is possible to switch to another higher level device may be confirmed again by the primary OLT (active system) with respect to the secondary OLT (standby) after the switching request.

  Here, when the host device 80 determines that communication cannot be taken over to the OLT connected to the redundant path (step S305; No), the host apparatus 80 maintains the communication path (step S304). On the other hand, when the host device 80 determines that communication can be taken over to the OLT connected to the redundant path (step S305; acceptable), it determines whether the failure of the C-ONU 251 or the failure of the C-OLT 352 (step S306). ).

  Then, the higher-level device 80 instructs the C node 350 in which the failure has occurred to perform a switching instruction to switch to a path that allows normal communication according to the situation of the failure location. For example, when the host device 80 determines that the failure is in the C-OLT 352 (step S306; C-OLT failure), the master C-OLT in which the failure has occurred is replaced with another normal C-OLT (standby). ) Is transmitted (step S307). On the other hand, when the host device 80 determines that the failure is in the C-ONU 251 (step S306; C-ONU failure), the master C-ONU in which the failure has occurred is replaced with another normal C-ONU (standby). ) Is transmitted (step S308). When the host device 80 determines that both the C-OLT 352 and the C-ONU 251 have failed (step S306; both failed), the host C-OLT and C-ONU in which the failure has occurred. A switching instruction to switch both to normal C-OLT and C-ONU is transmitted (step S309).

  Thereafter, the host device 80 determines whether or not a switching completion notification has been received from the C node 350 in which the failure has occurred (step S310). Here, when it is determined that the switching completion notification has been received from the C node 350 (step S310; success), the host device 80 completes the path switching process (step S311).

  On the other hand, when it is determined that the switching completion notification has not been received from the C node 350 (step S310; no or failure), the higher-level device 80 maintains the communication path (step S304). Thereafter, the higher-level device 80 executes Step S301 again.

  The host device 80 may maintain communication by switching the route to a normal port when a failure occurs in a port or the like. In this case, the host device 80 also switches the C-OLT 352 and the C-ONU 251 that are used when the port is changed.

  Further, the host device 80 may stop the switching process when the switching process is repeatedly executed any number of times. Further, the host device 80 independently issues a switching instruction when the periodic notification from the C node 350 is lost or when it is determined that the notification from the C node 350 to the host device 80 is difficult due to a failure. You may go. In addition, when the C node 350 has a function of performing communication by switching wavelengths to the C-OLT 352 and the lower-level device 90, the switched C-OLT does not interfere with the optical signal output by the failed C-OLT. The downstream optical signal may be output. In this case, the lower level device 90 switches to receive the wavelength corresponding to the C-OLT after switching.

  Further, the switching process is not limited to the host device 80 such as the OLT 10 or the upper C node 350, but may be performed mainly by the lower C node 350. For example, when the C node 350 located at the lower level is difficult to notify the host apparatus 80 of a failure, or when it is difficult to receive a switching instruction from the host apparatus 80 in a situation where a failure has occurred, the switching instruction is unnecessary For example, the switching process is executed by itself. This point will be described in detail with reference to FIG. FIG. 20 is a flowchart showing a flow of switching processing in the C node 350 according to the third embodiment.

  For example, as shown in FIG. 20, the lower C node 350 determines whether or not a failure has been detected (step S320). Here, when detecting a failure (step S320; present), the C node 350 determines whether or not communication with the higher-level device 80 is possible (step S321). When it is determined that communication with the host device 80 is possible (step S321; acceptable), the C node 350 executes switching processing of the host device 80 as shown in FIG. 19 (step S322).

  On the other hand, when it is determined that communication with the host device 80 is impossible or unnecessary (step S321; impossible or unnecessary), the C node 350 determines whether communication with the OLT connected to the redundant path is possible (step S323). ). Here, if the C node 350 determines that communication with the OLT connected to the redundant path is possible (step S323; acceptable), the C node 350 executes path switching control (step S324).

  First, the C node 350 determines whether the failure of the C-ONU 251 or the failure of the C-OLT 352 (step S325). Then, the C node 350 switches to a path that allows normal communication according to the situation of the failure location. For example, when the C node 350 determines that the failure is in the C-OLT 352 (step S325; C-OLT failure), the C-OLT in the failed main system is switched to another normal C-OLT. (Step S326). On the other hand, when the C node 350 determines that the failure is in the C-ONU 251 (step S325; C-ONU failure), the C-ONU in the failed main system is switched to another normal C-ONU. (Step S327). When the C node 350 determines that both the C-OLT 352 and the C-ONU 251 are faulty (step S325; both are faulty), the C-OLT and C-ONU of the main system in which the fault has occurred. Both are switched to other normal C-OLT and C-ONU (step S328).

  Thereafter, the C node 350 determines the switching result (step S329). Here, when the C node 350 determines that all switching has succeeded (step S329; all succeeded), the C node 350 transmits a switching completion notification to the host device 80 (step S330). Then, the C node 350 completes the path switching (step S331).

  On the other hand, when it is determined that the switching has failed (step S329; failure), the C node 350 transmits a switching failure notification (step S332). Then, the C node 350 maintains the communication path (step S333). Further, the C node 350 maintains the communication path even when a failure is not detected (step S320; no) (step S333). Also, when the C node 350 determines that communication with the OLT connected to the redundant path is impossible (step S323; No), the C node 350 maintains the communication path (step S333).

  Thereafter, the C node 350 executes Step S320 again. Note that the C node 350 may stop the switching process when the switching process is repeatedly executed any number of times. In addition, when a failure occurs in a port or the like, the C node 350 may maintain communication by switching the route to a normal port. In this case, the C node 350 also switches the C-OLT 352 and the C-ONU 251 used in accordance with the port change.

[Effect of the third embodiment]
As described above, the C node 350 according to the third embodiment is connected to any one of the plurality of C-ONUs 251 _{11 to} 251 _nn and is connected to the lower devices 90 _{1 to} 90 _n included in the second PON and the light. The C node 350 further includes a plurality of C-OLTs 352 _{1 to} 352 _n connected via the transmission line 20, and the communication unit 325 is connected to the second via any _{one of the} plurality of C-OLTs 352 _{1 to} 352 _n . It communicates with the lower device ₉₀ 1 to 90 _n included in the PON of the switching unit 353, and one of the plurality of C-OLT352 ₁ ~352 _n having the C node 350 in response to a failure situation C-ONU251 ₁₁ ~ by switching the connection with the 251 _nn, communicates with the lower device ₉₀ 1 to 90 _n included in the second PON of the plurality of C-OLT352 ₁ ~352 _n Switch the -OLT.

  As a result, the C node 350 according to the third embodiment has a communication failure due to a failure of the main C-ONU or C-OLT, or an optical transmission line connected from the upper optical splitter to the C-ONU. When a communication failure occurs due to disconnection or deterioration, the signal path in the C node 350 can be switched to another path that can be communicated, so that communication can be recovered.

  In addition, since the C node 350 according to the third embodiment includes a plurality of C-OLTs 352 in the C node 350, even if a malfunction occurs in the C-OLT that is actually performing communication, Since it can switch to C-OLT, it can respond to the failure and malfunction of C-OLT. For this reason, the C node 350 according to the third embodiment can cope with both C-OLT and C-ONU failures in the C node 350, so that the reliability of the communication path can be further improved. it can.

[Fourth Embodiment]
In the second embodiment, the case where the C node 250 includes a plurality of C-ONUs 251 has been described, but the plurality of C-ONUs 251 may be detachable. This point will be described in detail with reference to FIG. In the following, functional units that exhibit the same functions as those in the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

[Configuration of C node]
FIG. 21 is a diagram illustrating the configuration of the C node 450 according to the fourth embodiment. As illustrated in FIG. 21, the C node 450 includes a plurality of C-ONUs 451, a C-OLT 52, and a switching unit 253.

  The plurality of C-ONUs 451 are C-ONUs that can be arbitrarily attached and detached. For example, the plurality of C-ONUs 451 are physically removable network cards and the like. As an example, a plurality of C-ONUs 451 have a communication failure due to a failure of the main C-ONU or a communication failure due to disconnection or deterioration of the optical transmission line connected from the upper optical splitter to the C-ONU. In such a case, it is replaced with another normal C-ONU (spare).

[Effect of the fourth embodiment]
As described above, the C node 450 according to the fourth embodiment includes a plurality of detachable C-ONUs 451.

  As a result, the C node 450 according to the fourth embodiment can arbitrarily attach and detach the C-ONU, so that the C-ONU in which a failure / failure has occurred can be easily replaced with a normal C-ONU. it can. For this reason, the C node 450 according to the fourth embodiment can easily recover the function of the C node. Also, the C node 450 according to the fourth embodiment can easily change the configuration of the number of C-ONUs to be installed according to the failure rate / failure rate of the C-ONU and the optical transmission line section. it can.

[Fifth Embodiment]
In the third embodiment, the case where the C node 350 includes a plurality of C-ONUs 251 and a plurality of C-OLTs 352 has been described. However, the plurality of C-ONUs 251 and C-ONUs 351 can be attached and detached, respectively. There may be. This point will be described in detail with reference to FIG. In the following, functional units that exhibit the same functions as those in the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

[Configuration of C node]
FIG. 22 is a diagram illustrating a configuration of the C node 550 according to the fifth embodiment. As illustrated in FIG. 22, the C node 550 includes a plurality of C-ONUs 451 _{1 to} 451 _n , a plurality of C-OLTs 552 _{1 to} 552 _n , a switching unit 353, and a connection unit 354.

The plurality of C-ONUs 451 _{1 to} 451 _n are arbitrarily detachable C-ONUs. The plurality of C-OLTs 552 _{1 to} 552 _n are C-OLTs that can be arbitrarily attached and detached. For example, the plurality of C-ONUs 451 _{1 to} 451 _n and the plurality of C-OLTs 552 _{1 to} 552 _n are physically removable network cards or the like. As an example, a plurality of C-ONUs 451 _{1 to} 451 _n and a plurality of C-OLTs 552 _{1 to} 552 _n are connected to a C-ONU from a communication failure due to a failure of the main C-ONU or C-OLT, or from the upper optical splitter. Alternatively, when a communication failure due to disconnection or deterioration occurs in the optical transmission line connected to the C-OLT, the optical transmission line is detached and replaced with another normal C-ONU or C-OLT (standby).

[Effect of Fifth Embodiment]
As described above, the C node 550 according to the fifth embodiment includes a plurality of detachable C-ONUs 451 _{1 to} 451 _n and a plurality of C-OLTs 552 _{1 to} 552 _n .

  As a result, the C node 550 according to the fifth embodiment can arbitrarily attach and detach the C-ONU and C-OLT, so that a C-ONU or C-OLT in which a failure / failure has occurred can be -Can be easily exchanged with ONU or C-OLT. For this reason, the C node 550 according to the fifth embodiment can easily recover the function of the C node. The C node 550 according to the fifth embodiment includes C-ONUs, C-OLTs, and the number of C-ONUs and C-OLTs to be installed according to the failure rate / failure rate of the optical transmission line section. The configuration can be easily changed.

[Sixth Embodiment]
In the second and fourth embodiments described above, the case where the C node 250 and the C node 450 have a plurality of C-ONUs 251 has been described. However, an arbitrary number of C-ONUs can be operated simultaneously. May be. Specifically, the C node 650 according to the sixth embodiment includes a plurality of higher-level devices 80 ₁ to 80 ₁ included in the first PON among the plurality of C-ONUs 251 _{11 to} 251 _nn included in the C node 650. 80 _n or at the same time to operate two or more of the C-ONU as C-ONU performing communications. This point will be described in detail with reference to FIG. In the following, functional units that exhibit the same functions as those in the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

[Configuration of C node]
FIG. 23 is a diagram illustrating a configuration of the C node 650 according to the sixth embodiment. As illustrated in FIG. 23, the C node 650 includes a switching unit 653 as compared with the C node 250 illustrated in FIG.

The switching unit 653 is a C-ONU that communicates with any _{one of the} plurality of higher-level devices 80 ₁ to 80 _n included in the first PON among the plurality of C-ONUs 251 _{11 to} 251 _nn included in the C node 650. The above C-ONUs are operated simultaneously. Specifically, the switching unit 653 differs from the switching unit 253 in that it includes a switching processing unit 630.

The switching processing unit 630 operates any C-ONU among a plurality of C-ONUs 251 _{1 to} 251 _n included in the C node 650 and causes them to communicate simultaneously. That is, the switching unit 653 distributes and processes signals by operating an arbitrary number of C-ONUs in accordance with the signal processing load situation in the C node 650. For example, as illustrated in FIG. 23, the switching unit 653 secures processing paths Li for a plurality of signals that pass through the C-ONU 251 ₁₁ , the C-ONU 251 ₂₁ , the C-ONU 251 _2n, and the C-ONU 251 _n1. . This point will be described with reference to FIG.

FIG. 24 is a diagram illustrating a configuration of the switching unit 653 according to the sixth embodiment. As illustrated in FIG. 24, the switching unit 653 ensures a conduction path 1 and a conduction path m for signals connected to a plurality of C-ONUs. For example, when the instruction unit 231 receives a load distribution instruction from the C-ONU, the switching unit 653 sets a communication path based on the load distribution instruction. Then, the switching unit 653 forms a signal conduction path among the C-ONU 251 ₁₁ , the C-ONU 251 ₂₁ , the C-ONU 251 _2n, and the C-ONU 251 _n1 , thereby performing communication by a plurality of C-ONUs. Perform load balancing.

[Effect of the sixth embodiment]
As described above, in the C node 650 according to the sixth embodiment, the switching unit 653 includes a plurality of higher ranks included in the first PON among the plurality of C-ONUs 251 _{11 to} 251 _nn included in the C node 650. Two or more C-ONUs are operated simultaneously as C-ONUs that communicate with any of the devices 80 ₁ to 80 _n .

  Thereby, since the C node 650 according to the sixth embodiment can distribute the load to a plurality of C-ONUs, the load of one C-ONU can be reduced. For example, the C node 650 according to the sixth embodiment maintains a high level of signal processing capability in the entire C node by installing a plurality of C-ONUs having low information processing capability and low cost and distributing the load. be able to.

[Seventh Embodiment]
In the third embodiment and the fifth embodiment described above, the C node 350 and the C node 550 have been described as having a plurality of C-ONUs and a plurality of C-OLTs. C-ONUs and any number of C-OLTs may be operated simultaneously. Specifically, the C node 750 according to the seventh embodiment includes the lower devices 90 _{1 to} 90 _n included in the second PON among the plurality of C-OLTs 352 _{1 to} 352 _n included in the C node 750. Two or more C-OLTs are operated simultaneously as C-OLTs that communicate with each other. This point will be described in detail with reference to FIG. In the following, functional units that exhibit the same functions as those in the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

[Configuration of C node]
FIG. 25 is a diagram illustrating a configuration of the C node 750 according to the seventh embodiment. As illustrated in FIG. 25, the C node 750 includes a switching unit 753 and a connection unit 754, as compared with the C node 350 illustrated in FIG.

Among the plurality of C-OLTs 352 _{1 to} 352 _n included in the C node 750, the switching unit 753 includes two or more C-OLTs as C-OLTs that communicate with the lower devices 90 _{1 to} 90 _n included in the second PON. The OLT is operated simultaneously. Specifically, the switching processing unit 730 of the switching unit 753 causes any C-ONU among the plurality of C-ONUs 251 _{11 to} 251 _nn included in the C node 750 to operate and communicate, and the C node 750 includes Any C-OLT among a plurality of C-OLTs 352 _{1 to} 352 _n is operated to perform communication. That is, the switching unit 753 distributes and processes signals by operating an arbitrary number of C-ONUs and an arbitrary number of C-OLTs according to the load status of signal processing in the C node 750.

For example, as illustrated in FIG. 25, the switching unit 753 includes a plurality of signals that pass through the C-ONU 251 ₁₁ , the C-ONU 251 ₂₁ , the C-ONU 251 _nn , the C-OLT 352 _1, and the C-OLT 352 _n . A processing path Li is secured. This point will be described with reference to FIG.

  FIG. 26 is a diagram illustrating a configuration of the switching unit 753 according to the seventh embodiment. The switching unit 753 is different from the switching unit 353 in that the communication unit 725 is included. The communication unit 725 is different from the communication unit 325 in that it includes a switching processing unit 730.

As illustrated in FIG. 26, the switching processing unit 730 includes a signal conduction path 1-1 that connects a plurality of C-ONUs 251 _{11 to} 251 _nn and a plurality of C-OLTs 352 _{1 to} 352 _n , and a conduction path m−. 1, a conduction path 1-m, and a conduction path mn are secured. For example, when the instruction unit 231 receives a load distribution instruction from the C-ONU, the switching processing unit 730 sets a communication path based on the load distribution instruction. The switching processing unit 730 forms a plurality of signal conduction paths between the C-ONU 251 ₁₁ , the C-ONU 251 ₂₁ , the C-ONU 251 _nn , the C-OLT 352 _1, and the C-OLT 352 _n. The communication load is distributed between the C-ONU and the plurality of C-OLTs.

The connection unit 754 connects the C-ONU and the C-OLT. Specifically, the connection unit 754 is operated by the C-ONU operated by the switching unit 753 among the plurality of C-ONUs 251 _{11 to} 251 _{nn and} the switching unit 753 among the plurality of C-OLTs 352 _{1 to} 352 _n. Connected to the C-OLT.

[Effect of the seventh embodiment]
As described above, the C node 750 according to the seventh embodiment includes the subordinate devices 90 _{1 to} 90 _n included in the second PON among the plurality of C-OLTs 352 _{1 to} 352 _n included in the C node 750. Two or more C-OLTs are operated simultaneously as C-OLTs that perform communication.

  Thus, the C node 750 according to the seventh embodiment can distribute the load to a plurality of C-ONUs and a plurality of C-OLTs, so the load of the C-ONUs and C-OLTs per unit Can be reduced. For example, the C node 750 according to the seventh embodiment has a high signal processing capability in the entire C node by mounting a plurality of C-ONUs and C-OLTs having low information processing capability and low cost and distributing the load. Can be maintained.

[Eighth Embodiment]
In the second embodiment, the fourth embodiment, and the sixth embodiment described above, the case where the C node has a plurality of C-ONUs 251 _{11 to} 251 _nn has been described. You may pause. Specifically, in the C node 850 according to the eighth embodiment, the C-ONU included in the C node 850 is at least one C among a plurality of C-ONUs 851 _{11 to} 851 _nn included in the C node 850. -The other C-ONU is paused at an arbitrary timing while the ONU is operated. This point will be described in detail with reference to FIG. In the following, functional units that exhibit the same functions as those in the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

[Configuration of C node]
FIG. 27 is a diagram illustrating a configuration of the C node 850 according to the eighth embodiment. As illustrated in FIG. 27, the C node 850 includes a plurality of C-ONUs 851 _{11 to} 851 _nn as compared to the C node 250 illustrated in FIG.

The plurality of C-ONUs 851 _{11 to} 851 _nn arbitrarily suspend (sleep) C-ONUs in which no task such as signal processing occurs and signal transmission does not cause a failure even when suspended. In the example of FIG. 27, _C-ONU851 21 ~851 _nn of the plurality of _C-ONU851 11 ~851 _nn is at rest. Therefore, C-ONU851 ₁₁ of the plurality of _C-ONU851 11 ~851 _nn is the signal processing path Li. This point will be described with reference to FIG.

  FIG. 28 is a diagram illustrating a configuration of a C-ONU 851 according to the eighth embodiment. As illustrated in FIG. 28, the C-ONU 851 further includes a pause unit 891 (corresponding to a lower pause unit) compared to the C-ONU 51.

The pause unit 891 controls the pause of the C-ONU 851. Specifically, the pause unit 891 pauses another C-ONU at an arbitrary timing in a state where at least one C-ONU is operated among a plurality of C-ONUs 851 _{11 to} 851 _nn included in the C node 850. Let For example, the suspension unit 891 monitors the traffic conducted to the C-ONU 851 at the connection port 108 with the PON-IF port 109, the PON signal processing unit 110, and the C-OLT. Then, the pause unit 891 starts control for sleeping the C-ONU 851 when it is determined that the inflow of traffic is equal to or less than an arbitrary value.

  Here, the pause unit 891 may start sleep at an arbitrary timing mainly by the C-ONU 851. Further, the pause unit 891 may obtain permission from the higher-level device 80 as to whether or not to execute sleep. For example, the pause unit 891 transmits a sleep request to the OLT 10 or the C node 850 at a higher position via the PON-IF port 109. In addition, the pause unit 891 receives a sleep permission from the OLT 10 or the C node 850 at a higher position via the PON-IF port 109.

  Then, the sleep unit 891 starts sleep when sleep permission is obtained from the OLT 10 or the C node 850 at a higher position. In addition, when the C-ONU 851 is set as a standby system (non-operating system) from the higher-level device 80, the suspension unit 891 may start sleep assuming that there is no signal inflow. As a result, the suspension unit 891 can place the C-ONU in a suppressed state, so that power supply to the suspended C-ONU can be minimized. For this reason, the pause unit 891 can reduce power consumption by the C-ONU.

  In addition, the pause unit 891 may monitor the heat generation state of each part of the C node 850 and operate the C-ONU alternately according to the temperature state. As a result, the hibernation unit 891 concentrates heat generation in a part of the part, and can reduce the risk due to the degradation of the C node and the thermal runaway of the device due to the thermal load of the devices.

[Effect of the eighth embodiment]
As described above, in the C node 850 according to the eighth embodiment, the C-ONU included in the C node 850 includes at least one C-ON among the plurality of C-ONUs 851 _{11 to} 851 _nn included in the C node 850. A pause unit 891 is provided that pauses another C-ONU at an arbitrary timing while the ONU is operated.

  As a result, the C node 850 according to the eighth embodiment can leave other C-ONUs while leaving at least one C-ONU, thereby reducing power consumption while maintaining the system. it can.

  Further, even in the host system 80 of the secondary system and the host system 80 used in a mixture of the main system and the sub system, when there is no signal inflow, the apparatus that does not receive the signal is paused to reduce power consumption. And may be suppressed. In addition, when a redundant configuration of a plurality of primary PONs is performed with a small number of secondary PONs, if the traffic is less than the capacity of the secondary PONs, the communication path is switched to the secondary PONs and the host system of the primary system Power consumption may be reduced and suppressed by pausing 80.

[Ninth Embodiment]
In the third embodiment, the fifth embodiment, and the seventh embodiment described above, the C node has been described as having a plurality of C-ONUs and a plurality of C-OLTs. -The ONU and C-OLT may be arbitrarily paused. Specifically, in the C node 950 according to the ninth embodiment, the C-OLT included in the C node 950 includes at least one C-OLT 952 _{1 to} 952 _n included in the C node 950. While the OLT is operating, the other C-OLT is paused at an arbitrary timing. This point will be described in detail with reference to FIG.

[Configuration of C node]
FIG. 29 is a diagram illustrating the configuration of the C node 950 according to the ninth embodiment. As illustrated in FIG. 29, the C node 950 includes a plurality of C-ONUs 851 _{11 to} 851 _nn and a plurality of C-OLTs 952 _{1 to} 952 _{n as} compared to the C node 350 illustrated in FIG.

The plurality of C-OLTs 952 _{1 to} 952 _n arbitrarily pause (sleep) a C-OLT in which no signal processing or the like task occurs and no signal transmission failure occurs even when paused. In the example of FIG. 29, among the plurality of C-OLTs 952 _{1 to} 952 _n , C-OLTs 952 _{2 to} 952 _n are dormant. Therefore, C-OLT952 ₁ of the plurality of C-OLT952 ₁ ~952 _n is the signal processing path Li. This point will be described with reference to FIG.

  FIG. 30 is a diagram illustrating the configuration of the C-OLT 952 according to the ninth embodiment. As illustrated in FIG. 30, the C-OLT 952 further includes a pause unit 991 (corresponding to a higher pause unit) as compared to the C-OLT 352.

The pause unit 991 pauses another C-OLT at an arbitrary timing in a state in which at least one C-OLT among a plurality of C-OLTs 952 _{1 to} 952 _n included in the C node 950 is operated. Specifically, the pause unit 991 pauses another C-OLT at an arbitrary timing in a state where at least one C-OLT is operated among a plurality of C-OLTs 952 _{1 to} 952 _n included in the C node 950. Let

  For example, the suspension unit 991 monitors traffic conducted to the C-OLT 952 in the connection port 119 with the C-ONU, the PON-IF port 118, and the PON signal processing unit 120. Then, the pause unit 991 starts control for performing sleep of the C-ONU 851 and the C-OLT 952 when it is determined that the inflow of traffic is equal to or less than an arbitrary value.

  Here, the pause unit 991 may start sleep at an arbitrary timing mainly by the C-OLT 952. Further, the pause unit 991 may obtain permission from the higher-level device 80 as to whether or not to execute sleep. For example, the sleep unit 991 transmits a sleep request to the C-ONU 851 or the OLT 10 or the C node 950 at a higher position via a connection port with the C-ONU. In addition, the suspension unit 991 receives a sleep permission from the C-ONU 851 or the higher-level device 80 at a higher position via the connection port with the C-ONU. Then, the sleep unit 991 starts sleep when sleep permission is obtained from the host device 80.

  In addition, when the C-OLT 952 is set as a standby system (non-operating system) from the higher-level device 80, the suspension unit 991 may start sleep assuming that there is no signal inflow. In addition, when a communication path is established with the C-ONU 851, the suspension unit 991 may make a sleep request to the C-ONU 851, obtain a sleep permission from the C-ONU 851, and start sleep. .

  As a result, the suspension unit 991 can place the C-ONU 851 and the C-OLT 952 in a suppressed state, so that power supply to the suspended C-ONU 851 and the C-OLT 952 can be minimized. For this reason, the sleep unit 991 can reduce power consumption by the C-ONU 851 and the C-OLT 952.

  Further, the pause unit 991 may monitor the heat generation state of each part of the C node 950 and arbitrarily operate the C-ONU 851 and the C-OLT 952 according to the temperature state. As a result, the hibernation unit 991 concentrates heat generation in a part of the part, and can reduce the risk due to the degradation of the C node and the thermal runaway of the device due to the thermal load of the devices.

[Effect of the ninth embodiment]
As described above, in the C node 950 according to the ninth embodiment, the C-OLT included in the C node 950 is at least one C-OLT among the plurality of C-OLTs 952 _{1 to} 952 _n included in the C node 950. A pause unit 991 is provided that pauses another C-OLT at an arbitrary timing in a state where is operated.

  Accordingly, the C node 950 according to the ninth embodiment can maintain the system because it can pause other C-ONUs and C-OLTs while leaving at least one C-ONU and C-OLT. Power consumption can be reduced as it is.

  Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  Each component of each device illustrated in the above embodiments is functionally conceptual and does not necessarily have to be the same as the physically illustrated component. That is, the specific form of distribution / integration of each device (for example, the form shown in FIG. 2) is not limited to the one shown in the figure, and all or a part thereof can be changed in arbitrary units depending on various loads and usage conditions. It can be configured functionally or physically distributed and integrated. For example, the C-ONU 51 and the C-OLT 52 may be integrated as one unit, while the switching unit 53 may be distributed between the communication unit 105 and the detection unit 106. Further, for example, the notification unit 107 may be connected as an external device of the C node 50 via a network. Further, the functions of the C node 50 described above may be realized by having each of the detection unit 106 and the notification unit 107 connected to a network and cooperating with each other. Further, all or any part of each processing function performed in each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

  Further, in the above embodiment, in the C node, the C-ONU, the C-OLT, and the switching unit each have a detection unit and a notification unit. Here, in the C node, each of the C-ONU, the C-OLT, and the switching unit may not necessarily include the detection unit and the notification unit. Specifically, at least redundant parts may have a detection unit and a notification unit. For example, only the C-ONU may include a detection unit and a notification unit, and may detect and notify a failure.

  In addition, all or a part of the processes described as being automatically performed among the processes described in the above embodiments can be manually performed. Alternatively, all or part of the processing described as being performed manually can be automatically performed by a known method.

1 PON system 10 OLT
20 Optical transmission line 30 ONU
50 C node 51 C-ONU
52 C-OLT
53 Switching unit 70 Optical splitter

Claims (8)

A PON system having a first PON (Passive Optical Network) in which a communication device is connected to a plurality of upper terminal devices and a second PON in which the communication device is connected to a lower terminal device,
The communication device
Communication for communicating with any one of the plurality of higher-order terminal devices via any one of the plurality of optical transmission lines to which the plurality of higher-order terminal devices and the communication device are connected And
A PON system comprising: a switching unit that switches an optical transmission line used by the communication unit to one of the plurality of optical transmission lines according to a failure state. A communication device connected to a plurality of upper terminal devices included in the first PON and a lower terminal device included in the second PON,
Communication for communicating with any one of the plurality of higher-order terminal devices via any one of the plurality of optical transmission lines to which the plurality of higher-order terminal devices and the communication device are connected And
And a switching unit that switches an optical transmission line used by the communication unit to any one of the plurality of optical transmission lines according to a failure state. A plurality of lower terminators connected to the plurality of upper terminators via an optical transmission line;
The communication device further includes an upper terminal device connected to any one of the plurality of lower terminal devices and connected to a lower terminal device included in the second PON,
The communication unit is
Communicates with any of a plurality of higher-order terminal devices included in the first PON via any of a plurality of lower-order terminal devices included in the communication device, and passes through the higher-order terminal device included in the communication device. Communicate with the lower-end device included in the second PON,
The switching unit is
A plurality of higher-order terminations included in the first PON among the plurality of lower-order termination devices by switching connection between the higher-order termination device and any of the plurality of lower-order termination devices in the communication device according to a failure situation The communication apparatus according to claim 2, wherein a lower terminal apparatus that communicates with any one of the apparatuses is switched. The switching unit is
Two or more lower-level terminal devices are operated simultaneously as lower-level terminal devices that communicate with any one of a plurality of higher-level terminal devices included in the first PON among a plurality of lower-level terminal devices included in the communication device. The communication device according to claim 3. The lower-end terminal device included in the communication device is:
The low-order sleep part which makes another low-order termination apparatus pause at arbitrary timing in the state which operated the at least 1 low-order termination apparatus among the several low-order termination apparatuses which have in the said communication apparatus is characterized by the above-mentioned. Or the communication apparatus of 4. The communication device further includes a plurality of upper terminal devices connected to any of the plurality of lower terminal devices and connected to the lower terminal devices included in the second PON via an optical transmission line,
The communication unit is
Communicate with the lower-level termination device included in the second PON via any of the plurality of higher-level termination devices;
The switching unit is
By switching the connection between any one of the plurality of higher-order terminal devices in the communication device and the lower-order terminal device according to the failure status, the lower-order terminal device included in the second PON among the plurality of higher-order terminal devices; The communication apparatus according to any one of claims 2 to 5, wherein an upper terminal apparatus that performs communication is switched. The switching unit is
The two or more upper terminal devices are operated simultaneously as upper terminal devices that communicate with the lower terminal devices included in the second PON among a plurality of upper terminal devices included in the communication device. 6. The communication device according to 6. The upper terminal device in the communication device is:
7. A high-level pause unit configured to pause other high-level termination devices at an arbitrary timing in a state where at least one high-level termination device is operated among a plurality of high-level termination devices included in the communication device. Or the communication apparatus of 7.

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