Communication system, station-side device, management method, and management control program

Abstract

A communication system according to the present invention is provided with: a station-side device; a home-side device and a management home-side device individually connected to a communication line connected to the station-side device; and a management device that communicates with the station-side device via the management home-side device. The station-side device includes: a first reception unit that receives first control information from the management home-side device via the communication line, the first control information being transmitted from the management device to the management home-side device and serving to control the communication line to which the home-side device is connected; an execution unit that executes, on the basis of the first control information received by the first reception unit, first control processing including controlling the communication line to which the home-side device is connected; and a first transmission unit that transmits the result of the execution of the first control processing by the execution unit to the management home-side device via the communication line in order to provide the management device with the result of the execution.

Description

Communication system, station side device, management method, and management control program

[0001] This application claims priority from Japanese Patent Application No. 2023-201897, filed November 29, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0002] A PON (Passive Optical Network) system is a P2MP (Point to Multipoint) optical communication system that uses optical fiber as a transmission path. The PON system includes a PON line, which is an optical fiber network branched by an optical splitter, an optical line terminal (OLT) at the central office connected to the trunk fiber of the PON line, and optical network units (ONUs) at the residential side connected to each of the branch fibers of the PON line.

[0003] Conventionally, a management device for managing a PON system is connected to a dedicated management port provided in an OLT (for example, see Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2018-170578

[0005] A communication system according to one aspect of the present disclosure includes an optical line terminal; an optical network unit and a management optical line terminal, each connected to a communication line connected to the optical line terminal; and a management device that communicates with the optical line terminal via the management optical line terminal. The optical line terminal includes a first receiving unit that receives, from the management optical line, first control information for controlling the communication line to which the optical line terminal is connected, transmitted from the management device to the management optical line terminal; an executing unit that executes, based on the first control information received by the first receiving unit, a first control process including control of the communication line to which the optical line terminal is connected; and a first transmitting unit that transmits, to the management device, a result of execution of the first control process by the executing unit.

[0006] FIG. 1 is a diagram showing an example of the overall configuration of a communication system according to a first embodiment. FIG. 2 is a block diagram showing an example of the internal configuration of an OLT according to the first embodiment. FIG. 3 is a block diagram showing an example of the internal configuration of an ONU-C according to the first embodiment. FIG. 4 is a functional block diagram showing an example of the functions of an OLT according to the first embodiment. FIG. 5 is a sequence diagram showing an example of connection operations between an OLT, an ONU, an ONU-C, and a management device in the communication system according to the first embodiment. FIG. 6 is a sequence diagram showing an example of management operations of an OLT and an ONU in the communication system according to the first embodiment. FIG. 7 is a block diagram showing an example of the internal configuration of an OLT according to a second embodiment. FIG. 8 is a diagram showing an example of the overall configuration of a communication system according to a third embodiment. FIG. 9 is a block diagram showing an example of the internal configuration of an OLT according to the third embodiment. FIG. 10 is a diagram showing an example of the overall configuration of a communication system according to a fifth embodiment.

[0007] <Problem to be Solved by the Present Disclosure> In conventional PON systems, the OLT and management device are installed in facilities (hereinafter also referred to as "carrier sites") owned by carriers (telecommunications carriers that own their own communication lines and provide communication services), and the PON system has been used by carriers to provide access services such as Internet connection and telephone lines to users. In recent years, efforts have been made to increase the transmission distance of PON systems through the use of higher PON speeds, coherent reception technology, and the like. Such long-distance, high-capacity PON systems enable carriers to provide communication services that connect user sites one-to-many. In this case, because the OLT is installed at a user site (e.g., a user's data center), the problem becomes how to connect the management device installed at the carrier site to the OLT.

[0008] <Effects of the Present Disclosure> According to the present disclosure, it is possible to connect a station device and a management device using a communication line.

[0009] <Outline of Embodiments of the Present Disclosure> Below, an outline of embodiments of the present disclosure will be listed and described.

[0010] (1) A communication system according to this embodiment includes an optical line terminal (OLT), an optical network unit (ONU) and a management optical network unit (MAN) connected to a communication line connected to the ONU, and a management device that communicates with the ONU via the management optical line terminal. The ONU includes: a first receiver that receives, from the management optical line, first control information for controlling the communication line to which the ONU is connected, the first control information being transmitted from the management optical line terminal to the management optical line terminal; an execution unit that executes, based on the first control information received by the first receiver, a first control process including control of the communication line to which the ONU is connected; and a first transmitter that transmits a result of the execution of the first control process by the execution unit to the management optical line terminal to provide the result to the management device. This enables the optical line terminal and the management device to be connected using the communication line.

[0011] (2) In the above (1), the communication lines may include a trunk communication line and a first branch communication line and a second branch communication line branching from the trunk communication line, the optical network unit may be connected to the first branch communication line, and the management optical network unit may be connected to the second branch communication line. This allows the management device to be connected to the trunk communication line via the second branch communication line.

[0012] (3) In the above (1), the communication lines may include a first communication line and a second communication line different from the first communication line, the first communication line may be connected to the optical line terminal and the optical network unit, and the second communication line may be connected to the optical line terminal and the management optical network unit. This allows the management device to be connected to the second communication line different from the first communication line to which the optical line terminal is connected.

[0013] (4) In any one of (1) to (3) above, the optical line terminal may include: a second receiver that receives, from the management optical line, second control information for controlling the optical network unit, the second control information being transmitted from the management optical line to the management optical network unit; a second transmitter that transmits the second control information received by the second receiver to the optical network unit; a third receiver that receives, from the optical network unit, a result of a second control process that the optical network unit has executed based on the second control information; and a third transmitter that transmits the result of the second control process to the management optical network unit via the communication line to provide the result of the second control process received by the third receiver to the management optical network unit. This allows the management device to manage the optical network units.

[0014] (5) In any one of (1) to (4) above, the management home apparatus may include a first connection unit connected to the communication line and a second connection unit connected to the management apparatus, thereby allowing the management apparatus to be connected to the communication line via the management home apparatus.

[0015] (6) In any one of (1) to (5) above, the communication line may be an optical communication line, the management home device may transmit a first frame that is an Operations, Administration, Maintenance (OAM) frame defined by a communication standard used on the optical communication line and that stores the first control information, the first receiving unit may receive the first frame that stores the first control information, and the first transmitting unit may transmit a second frame that is the OAM frame that stores a result of executing the first control information. This allows information used for management (the first control information and the result of executing the first control process) to be transmitted and received between the management home device and the optical line device using the OAM frame.

[0016] (7) In any one of (1) to (5) above, the communication line may be an optical communication line, the management home appliance may transmit a first frame, which is a user frame that stores the first control information and is different from an OAM frame defined by a communication standard used on the optical communication line, the optical line device may include a processor and a communication processing circuit that executes predetermined communication processing for communication between the optical line device, the optical line device, and the management home appliance, the communication processing circuit may output the first frame received from the management home appliance to the processor, the processor may output a second frame, which is a user frame that includes a result of execution of the first control processing, to the communication processing circuit, and the communication processing circuit may transmit the second frame to the management home appliance. This allows information used for management to be input / output to a processor provided in the optical line device using the user frame.

[0017] (8) In any one of (1) to (7) above, the optical line terminal may include: a search unit that searches for an activated management optical line terminal when the optical line terminal is not logically connected to the optical line terminal and the management optical line terminal; a first connection unit that establishes a connection between the optical line terminal and the management optical line terminal when the activated management optical line terminal is found by the search unit; a first authentication unit that authenticates the management optical line terminal when the connection between the optical line terminal and the management optical line terminal is established; a second connection unit that establishes a connection between the optical line terminal and the management optical line terminal when authentication by the first authentication unit is successful; and a second authentication unit that authenticates the management optical line terminal when the connection between the optical line terminal and the management optical line terminal is established. This makes it possible to establish a logical connection between the optical line terminal, the management optical line terminal, and the management optical line terminal.

[0018] (9) In any one of (1) to (8) above, the system may include a first management home device that is the management home device, and a second management home device connected to the communication line that is connected to the optical line device, wherein the management device is switchable from a first communication mode in which it communicates with the optical line device via the first management home device to a second communication mode in which it communicates with the optical line device via the second management home device. This makes it possible to provide redundancy to the connection path between the management device and the optical line device.

[0019] (10) In the above (9), the communication lines may include a first communication line and a second communication line different from the first communication line, the first communication line may be connected to the optical line terminal, the optical network terminal, and the second management optical network terminal, and the second communication line may be connected to the optical line terminal and the first management optical network terminal. This allows the management device and the optical network terminal to be connected via the second communication line if a failure occurs on the first communication line.

[0020] (11) In the above (10), the optical line terminal may include a first communication module connected to the first communication line and a second communication module connected to the second communication line, whereby if a failure occurs in the first communication module, the second communication module can connect the management device and the optical line terminal.

[0021] (12) An optical line terminal according to this embodiment is an optical line terminal connected to a communication line to which an optical network unit is connected, and includes: a first receiver that receives, from the management optical line, first control information for controlling the communication line to which the optical network unit is connected, the first control information being transmitted to the management optical line from a management device that is capable of communicating with the optical line terminal via a management optical line terminal connected to the management optical line; an execution unit that executes, based on the first control information received by the first receiver, a first control process including control of the communication line to which the optical network unit is connected; and a first transmitter that transmits a result of the execution of the first control process by the execution unit to the management optical line to provide the result to the management device. This makes it possible to connect the optical line terminal and the management device using the communication line connecting the optical line terminal and the optical network unit.

[0022] (13) A management method according to this embodiment is a management method for managing optical line devices connected to a communication line to which an optical network unit is connected, the management method including the steps of: transmitting, from a management device capable of communicating with the optical line device via a management optical line device connected to the communication line, first control information for controlling the communication line to which the optical network unit is connected to the management optical line device; transmitting the first control information from the management optical line device to the optical line device via the communication line; executing, by the optical line device, a first control process including control of the communication line to which the optical network unit is connected based on the first control information; transmitting a result of the first control process from the optical line device to the management optical line device via the communication line; and transmitting a result of the first control process from the management optical line device to the management optical line device. This makes it possible to connect the optical line device and the management device using the communication line connecting the optical line device and the optical line device.

[0023] (14) A management control program according to this embodiment is a management control program for managing an optical line terminal connected to a network element, the management control program causing a computer to execute the following steps: receiving, via the communication line, from a management optical line terminal, first control information for controlling the communication line to which the optical line terminal is connected. The first control information is transmitted to the management optical line terminal from a management optical line terminal capable of communicating with the optical line terminal via a management optical line terminal connected to the management optical line terminal; executing, based on the received first control information, a first control process including control of the communication line to which the optical line terminal is connected; and transmitting, via the communication line, a result of the execution of the first control process to the management optical line terminal in order to provide the result of the execution of the first control process to the management optical line terminal. This makes it possible to connect the optical line terminal and the management device using the communication line connecting the optical line terminal and the optical line terminal.

[0024] The present disclosure can be realized not only as a communication system having the above-described characteristic configuration, an optical line terminal device included in the communication system, a management method having characteristic processing steps, and a management control program that causes the optical line terminal device to execute the characteristic processing, but also as a management device included in the communication system, a management optical line terminal device included in the communication system, some or all of the optical line terminal device being realized as a semiconductor integrated circuit, some or all of the management device being realized as a semiconductor integrated circuit, or some or all of the management optical line terminal device being realized as a semiconductor integrated circuit.

[0025] <Details of Embodiments of the Present Disclosure> Hereinafter, details of embodiments of the present disclosure will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any manner.

[0026] In the following embodiment, an example will be described in which the communication system is a system including an optical line terminal for optical communication. However, the communication system is not limited to a system including an optical line terminal. The communication system according to this embodiment may also be a system including communication devices other than optical line terminals, such as wireless communication devices and wired communication devices. The terms "optical line terminal" and "network terminal" used here do not limit the location where each device is set up.

[0027] [1. First Embodiment] [1-1. Communication System] Fig. 1 is a diagram showing an example of the overall configuration of a communication system according to the first embodiment. As shown in Fig. 1, a communication system 10 is an optical communication system and includes an optical line terminal (OLT) 11, a plurality of optical network units (ONUs) 12, and a PON line 13. Note that in this embodiment, an Ethernet PON such as a GE-PON (Gigabit Ethernet-PON) or a 10G-EPON (10 Gigabit Ethernet-PON) will be described. In the following description, the PON line 13 refers to a physical communication line that does not include a logical line or a communication service.

[0028] The OLT 11 is connected to a user's data center via a higher-level network 50 .

[0029] A customer communication device can be connected to a UNI (User Network Interface) port (not shown) of the ONU 12. The number and type of customer communication devices connected to the ONU 12 are not particularly limited. For example, the customer communication device may be a terminal such as a personal computer, or a relay device such as a router or gateway. In other words, the customer communication device may be connected to the ONU 12 via a network including a relay device.

[0030] A PON line 13 is connected to the OLT 11. The PON line 13 is an optical communication line including optical splitters 14A and 14B and optical fibers 15A, 15B, 16A, and 16B. The PON line 13 includes trunk optical fibers 15A and 15B and multiple branch optical fibers 16A and 16B. A first end of the trunk optical fiber 15A is connected to the OLT 11. A second end of the trunk optical fiber 15A and a first end of the trunk optical fiber 15B are connected via the optical splitter 14B. The second end of the trunk optical fiber 15B, i.e., the end opposite to the end connected to the optical splitter 14B, is connected to the optical splitter 14A. A plurality of branch optical fibers 16A are connected to the optical splitter 14A. An ONU 12 is connected to each branch optical fiber 16A. The trunk optical fibers 15A and 15B according to the first embodiment are an example of a trunk communication line, and the branch optical fiber 16A according to the first embodiment is an example of a first branch communication line.

[0031] The communication system 10 further includes an ONU-C17, which is a management home device, and a management device 18. A first end of a branch optical fiber 16B is connected to the optical splitter 14B. A second end of the branch optical fiber 16B is connected to the ONU-C17. The branch optical fiber 16B according to the first embodiment is an example of a second branch communication line. However, the ONU-C17 only needs to be connected to one of the branch lines of the PON, and is not limited to the connection topology shown in FIG. 1 .

[0032] A management device 18 is connected to the ONU-C 17 via a communication cable. The management device 18 is a terminal for maintenance and management of the communication system 10. The management device 18 is used by an administrator who manages the communication system 10. In this embodiment, the communication cable connecting the ONU-C 17 and the management device 18 is an Ethernet cable.

[0033] No customer communication device is connected to the UNI port of the ONU-C 17. That is, the ONU-C 17 is connected to the PON line 13 and the management device 18, and is used for communication between the OLT 11 and the management device 18.

[0034] For example, the PON line 13, the OLT 11, the ONUs 12, the ONU-C 17, and the management device 18 are included in a carrier network. The OLT 11 and the ONUs 12 are located at different user sites.

[0035] An optical signal transmitted from the OLT 11 and transmitted through the trunk optical fiber 15A is branched by the optical splitter 14B. The branched optical signal is transmitted to the optical splitter 14A through the trunk optical fiber 15B, and then transmitted to the ONU-C 17 through the branch optical fiber 16B.

[0036] The optical signal transmitted through the trunk optical fiber 15B is split by the optical splitter 14A. The split optical signal is transmitted to each ONU 12 through a branch optical fiber 16A.

[0037] The optical signals transmitted from each ONU 12 pass through the branch optical fiber 16A and are combined at the optical splitter 14A. The combined optical signal is transmitted to the OLT 11 through the trunk optical fiber 15B, the optical splitter 14B, and the non-trunk optical fiber 15A.

[0038] The optical signal transmitted from ONU-C 17 passes through branch optical fiber 16B and is input to optical splitter 14B. The optical signal input from branch optical fiber 16B to optical splitter 14B is merged with the optical signal transmitted from optical splitter 14A through trunk optical fiber 15B, and is transmitted through trunk optical fiber 15A to OLT 11. The optical splitters 14A and 14B used in PON line 13 do not require an external power supply and passively branch or multiplex optical signals from the input optical signals.

[0039] After the connection between the OLT 11 and the ONU 12 is established, the customer communication device can access the upper network 50 via the ONU 12 and the OLT 11. The upstream optical signal transmitted through the branch optical fiber 16A is merged at the optical splitter 14A. Similarly, the upstream optical signal transmitted through the branch optical fiber 16B is merged at the optical splitter 14A with the upstream optical signal transmitted through the trunk optical fiber 15B. Therefore, multiplexing is required to prevent collisions between optical signals of the same wavelength after merging. In the communication system 10, time division multiplexing is performed in accordance with, for example, MPCP (Multi-Point Control Protocol).

[0040] [1-2. Internal Configuration of OLT] The OLT 11 according to the first embodiment has one line port, and is connected to one trunk optical fiber 15A at this line port.

[0041] 2 is a block diagram showing an example of the internal configuration of the OLT 11 according to the first embodiment. As shown in FIG. 2, the OLT 11 according to the first embodiment includes one management module 21 and one line control module 22.

[0042] [1-2-1. Configuration of the Line Control Module] The line control module 22 controls communications on the PON line 13. The line control module 22 is an example of a communications module. The line control module 22 is, for example, a "PON unit" that operates as an OSU (Optical Subscriber Unit) of the PON. The line control module 22 is, for example, a circuit module that can be attached and detached to the housing of the OLT 11. Note that the line control module 22 may also be fixed to the housing of the OLT 11. The line control module 22 controls communications with the ONU 12 and ONU-C 17, which are opposite devices.

[0043] The line control module 22 includes a processor 221 , a non-volatile memory 222 , a volatile memory 223 , a PON processing circuit 224 , a PHY 225 which is a transceiver, and an optical transceiver 226 .

[0044] The volatile memory 223 is a semiconductor memory such as a static random access memory (SRAM) or a dynamic random access memory (DRAM). The nonvolatile memory 222 is a rewritable nonvolatile memory such as a flash memory. The nonvolatile memory 222 stores a computer program (not shown) for line control and data (not shown) used to execute this program.

[0045] The processor 221 is, for example, a CPU (Central Processing Unit). However, the processor 221 is not limited to a CPU. The processor 221 may be a GPU (Graphics Processing Unit). The processor 221 is configured to be able to execute a computer program. However, the processor 221 may be, for example, an ASIC (Application Specific Integrated Circuit) or a programmable logic device such as a gate array or FPGA (Field Programmable Gate Array). In this case, the ASIC or programmable logic device is configured to be able to execute the same functions as the above-mentioned line control program.

[0046] The PHY 225 is a device corresponding to the physical layer in the OSI reference model, and is, for example, a transceiver for backplane Ethernet. The PHY 225 is connected to the PHY 215, which is a transceiver of the management module 21, via a signal line 228. The PHY 225 and the PHY 215 are connected to the processor 221 and the processor 211, respectively. This allows the processor 221 of the line control module 22 to communicate with the processor 211 of the management module 21.

[0047] The optical transceiver 226 is an optical device (for example, a pluggable optical transceiver) including a circuit for transmitting and receiving optical signals. The optical transceiver 226 constitutes the line port 19. The optical transceiver 226 is optically connected to the trunk optical fiber 15A (see FIG. 1) and electrically connected to the PON processing circuit 224. Therefore, in the first embodiment, the ONU-C 17 is connected via the PON line 13 to the line port to which the ONU 12 is connected.

[0048] The optical transceiver 226 converts optical signals into electrical signals and vice versa. That is, the optical transceiver 226 converts upstream optical signals from the ONU 12 into electrical signals. The optical transceiver 226 converts downstream electrical signals from the PON processing circuit 224 into optical signals.

[0049] The PON processing circuit 224 is an example of a communication processing circuit, and is made up of an integrated circuit that executes predetermined communication processing in accordance with the PON communication standard.

[0050] If a frame included in the upstream signal is a data frame for the upper network 50, the PON processing circuit 224 transmits the frame to the upper network 50. If a frame included in the downstream signal is a data frame for a customer communication device connected to the ONU 12, the PON processing circuit 224 causes the optical transceiver 226 to transmit the frame.

[0051] The processor 221 and the PON processing circuit 224 are capable of transmitting data according to the Ethernet protocol. When an OAM frame (an OAM frame defined in IEEE 802.3ah) is included among the frames contained in an upstream signal, the PON processing circuit 224 distinguishes the OAM frame from other frames. Specifically, the PON processing circuit 224 can extract the OAM frame from the upstream signal and output the extracted OAM frame to the processor 221. The processor 221 outputs (transmits) the OAM frame to the management module 21, as described below.

[0052] When the processor 221 accepts (receives) an OAM frame from the management module 21 as described below, it outputs the accepted OAM frame to the PON processing circuit 224. The PON processing circuit 224 inserts the OAM frame accepted from the processor 221 between frames in the downstream signal. The process of inserting an OAM frame between frames in the downstream signal in the PON processing circuit is an example of a "transmission process."

[0053] [1-2-2. Configuration of Management Module] The management module 21 is connected to the line control module 22 and manages the line control module 22. The management module 21 is, for example, a circuit module that can be attached and detached to the housing of the OLT 11. Note that the management module 21 may also be fixed to the housing of the OLT 11.

[0054] The management module 21 includes a processor 211, a nonvolatile memory 212, a volatile memory 213, an interface 214, and a PHY 215. The basic configurations of the processor 211, nonvolatile memory 212, volatile memory 213, and PHY 215 are the same as those of the processor 221, nonvolatile memory 222, volatile memory 223, and PHY 225, so a description thereof will be omitted. Note that, hereinafter, a description of hardware elements that are the same as hardware elements that have already been described will be omitted.

[0055] The non-volatile memory 212 stores a management control program 216, which is a computer program, and data (not shown) used to execute the management control program 216. The management control program 216 is a computer program for maintenance management of the OLT 11.

[0056] As described above, the PHY 215 is connected to the PHY 225 , which is a transceiver of the line control module 22 , by a signal line 228 .

[0057] The interface 214 can exchange data with external devices. The interface 214 is an input / output device and includes, for example, a Universal Serial Bus (USB) port or an SD card slot. Furthermore, the interface 214 may be a network interface, for example, an Ethernet interface. A flash memory (USB memory) connectable to a USB port and a flash memory (SD card) connectable to an SD card slot are connected to the interface 214 (not shown). Furthermore, the interface 214 may be connected to a maintenance terminal or a server (not shown).

[0058] The management module 21 can use the OAM protocol. The processor 211 of the management module 21 can communicate with the management device 18 using OAM frames. As will be described later, the management device 18 transmits OAM frames including first control information for managing the OLT 11. In the following description of the embodiment, it is assumed that the PON line 13 connected to the OLT 11 is also included in the management targets of the management device 18. The ONU-C 17 transmits the OAM frames received from the management device 18 to the OLT 11 as optical signals. Upon receiving the OAM frames, the line control module 22 of the OLT 11 distinguishes the received OAM frames from other frames and outputs the OAM frames to the management module 21. As a result, the processor 211 acquires the OAM frames transmitted from the management device 18.

[0059] The processor 211 can also generate OAM frames and output them to the line control module 22. PON frames are transmitted and received over the PON links (the link between the OLT 11 and the ONU 12, and the link between the OLT 11 and the ONU-C 17). In the PON frame, the LLID (Logical Link ID) of the control target is included in the preamble to specify the destination. The processor 211 specifies the destination by including the LLID (Logical Link ID) of the ONU 12 and the ONU-C 17 in the preamble of the OAM frame. In a more specific example, the OAM frame is an extended OAM frame, and destination and sender information is stored in an area of ​​the extended OAM frame that can be freely defined by the telecommunications carrier (hereinafter also referred to as the "user area"). The information storage area in the OAM frame is similar below. The line control module 22 transmits the OAM frame provided by the management module 21 to the PON line 13 as an optical signal. When the ONU-C17 receives the OAM frame in which the LLID of the ONU-C17 is stored, it transmits the received OAM frame to the management device 18. As a result, the management device 18 receives the OAM frame transmitted from the processor 211.

[0060] 3 is a block diagram showing an example of the internal configuration of an ONU-C according to the first embodiment. The ONU-C 17 according to the first embodiment includes a processor 171, a non-volatile memory 172, a volatile memory 173, a PON processing circuit 174, an optical transceiver 175, an interface 176, and a UNI port 177.

[0061] The processor 171, for example, controls the entire ONU-C 17. For example, a computer program for setting up the ONU-C 17 is stored in the nonvolatile memory 172. The processor 171 can set up the ONU-C 17 by executing this program.

[0062] The optical transceiver 175 is optically connected to the branch optical fiber 16 B and electrically connected to the PON processing circuit 174 .

[0063] The PON processing circuit 174 is an integrated circuit that executes predetermined communication processing in accordance with the PON communication standard. The PON processing circuit 174 establishes an MPCP link with the OLT 11 (PON processing circuit 224) and also establishes an OAM link. This enables transmission and reception of OAM frames to and from the OLT 11.

[0064] The UNI port 177 is connected to the PON processing circuit 174. A communication device capable of Ethernet communication can be connected to the UNI port 177. In this embodiment, no device is connected to the UNI port 177.

[0065] The interface 176 is capable of exchanging data with external devices. The interface 176 includes an Ethernet interface. The interface 176 is connected to the management device 18 and is capable of sending and receiving Ethernet frames to and from the management device 18. The interface 176 is connected to the processor 171. The processor 171 is capable of communicating with the management device 18 via the interface 176 using the Ethernet protocol.

[0066] An OAM frame transmitted from the management device 18 is received by the interface 176 and output from the interface 176 to the processor 171. The processor 171 outputs the OAM frame from the management device 18 to the PON processing circuit 174. The PON processing circuit 174 outputs the OAM frame received from the processor 171 to the optical transceiver 175. The optical transceiver 175 converts the upstream signal (OAM frame) consisting of an electrical signal from the PON processing circuit 174 into an optical signal.

[0067] The optical transceiver 175 converts the downstream optical signal from the OLT 11 into an electrical signal. If the frame included in the downstream signal is an OAM frame, the PON processing circuit 174 outputs the frame to the processor 171.

[0068] Specifically, when an OAM frame is included among the frames contained in the downstream signal, the PON processing circuit 174 distinguishes the OAM frame from other frames. The PON processing circuit 174 extracts only the OAM frame from the downstream signal and outputs the OAM frame to the processor 171. The processor 171 outputs the OAM frame received from the PON processing circuit 174 to the interface 176. The interface 176 transmits the OAM frame received from the processor 171 to the management device 18. The PON processing circuit 174 discards frames other than the OAM frame included in the downstream signal.

[0069] [1-4. Functions of the OLT] FIG. 4 is a functional block diagram showing an example of functions of the OLT according to the first embodiment.

[0070] The OLT 11 has the functions of a search unit 111, a first connection unit 112, a first authentication unit 113, a second connection unit 114, a second authentication unit 115, a permission acceptance unit 116, a third connection unit 117, a first receiving unit 119, an execution unit 120, a first transmitting unit 121, a second receiving unit 122, a second transmitting unit 123, a third receiving unit 124, and a third transmitting unit 125. The functions of the search unit 111, the first connection unit 112, the first authentication unit 113, the second connection unit 114, the second authentication unit 115, the permission acceptance unit 116, the third connection unit 117, the first receiving unit 119, the execution unit 120, the first transmitting unit 121, the second receiving unit 122, the second transmitting unit 123, the third receiving unit 124, and the third transmitting unit 125 are realized by the processor 211 executing the management control program 216.

[0071] When the management device 18 and the ONU-C 17 are connected to each other, the management device 18 can activate the ONU-C 17. For example, an administrator operates the management device 18 to activate the ONU-C 17. For example, when the ONU-C 17 is activated, activation information is stored in the nonvolatile memory 172 of the ONU-C 17.

[0072] The search unit 111 searches for an activated ONU-C17 when the OLT 11 has not established an MPCP link or an OAM link with the ONU 12 or the ONU-C17. For example, the search unit 111 searches for an activated ONU-C17 by transmitting a specific search signal to the trunk optical fiber 15A connected to the line port 19. An activated ONU-C17 does not respond to the search signal, but an activated ONU-C17 transmits a specific response signal when it receives the search signal. The search signal and response signal are transmitted and received to establish an MPCP link and an OAM link between the OLT 11 and the ONU 12 or the ONU-C17, where an MPCP link and an OAM link have not been established. Note that the management device 18 does not necessarily have the function of enabling and disabling the ONU-C17. In this case, ONU-C17 is always valid, and the search unit 111 can search for ONU-C17.

[0073] When the search unit 111 finds an enabled ONU-C17, the first connection unit 112 establishes a logical connection between the OLT 11 and the ONU-C17, i.e., an MPCP link and an OAM link. That is, a predetermined connection sequence is executed between the OLT 11 and the ONU-C17, and a logical connection between the OLT 11 and the ONU-C17 is established. In the following description, the establishment of an MPCP link and an OAM link between the OLT 11 and the ONU 12 or the ONU-C17 is also referred to as a "logical connection."

[0074] When a logical connection between the OLT 11 and the ONU-C 17 is established, the first authentication unit 113 authenticates the ONU-C 17. For example, authentication information for authenticating the ONU-C 17 is stored in the nonvolatile memory 212 of the OLT 11. The authentication information is, for example, the MAC address or authentication code of the ONU-C 17. The first authentication unit 113 transmits a request for authentication information to the ONU-C 17. Specifically, the first authentication unit 113 transmits an OAM frame including the request information. For example, the request information is stored in an area of ​​the extended OAM frame that can be freely defined by the telecommunications carrier. Upon receiving the request, the ONU-C 17 transmits the authentication information to the OLT 11. Specifically, the ONU-C 17 transmits an OAM frame including the authentication information. Upon receiving the authentication information, the first authentication unit 113 compares the received authentication information with the authentication information stored in the nonvolatile memory 212. If the received authentication information matches the authentication information stored in the nonvolatile memory 212, the authentication is successful, and if the received authentication information does not match the authentication information stored in the nonvolatile memory 212, the authentication fails.

[0075] If the authentication by the first authentication unit 113 is successful, the second connection unit 114 establishes a connection (here, an Ethernet link) between the OLT 11 and the management device 18. That is, a predetermined connection sequence is executed between the OLT 11 and the management device 18, and a connection between the OLT 11 and the management device 18 is established.

[0076] When a connection between the OLT 11 and the management device 18 is established, the second authentication unit 115 authenticates the management device 18. For example, authentication information for authenticating the management device 18 is stored in the nonvolatile memory 212 of the OLT 11. The authentication information is, for example, the MAC address or authentication code of the management device 18 (for example, a code different from the authentication code of the ONU-C 17 described above). The second authentication unit 115 transmits a request for authentication information to the management device 18. Specifically, the second authentication unit 115 transmits an OAM frame including the request information. Upon receiving the request, the management device 18 transmits the authentication information to the OLT 11. Specifically, the management device 18 transmits an OAM frame including the authentication information. Upon receiving the authentication information, the second authentication unit 115 compares the received authentication information with the authentication information stored in the nonvolatile memory 212. If the received authentication information matches the authentication information stored in the nonvolatile memory 212, the authentication is successful, and if the received authentication information does not match the authentication information stored in the nonvolatile memory 212, the authentication fails. However, when authentication of the management device 18 is performed as in this embodiment, authentication of the ONU-C 17 may be omitted.

[0077] If the authentication of the management device 18 is successful, the management device 18 transmits a search permission for the ONU 12 to the OLT 11. The OLT 11, having received the search permission, searches for the ONU 12. If the OLT 11 receives a response signal from the ONU 12 as a result of the search, the OLT 11 inquires of the management device 18 as to whether a logical connection with the ONU 12 is possible. When the management device 18 receives the inquiry as to whether a logical connection with the ONU 12 is possible, for example, it executes an authentication process for the ONU 12. Specifically, the management device 18 holds authentication information for the ONU 12. The authentication information is, for example, the MAC address or authentication code of the ONU 12 (for example, a code different from the authentication codes of the ONU-C 17 and the management device 18 described above). For example, the response signal from the ONU 12 includes the authentication information. The OLT 11 includes the authentication information received from the ONU 12 in an inquiry about the availability of a logical connection with the ONU 12. The management device 18 compares the received authentication information with the authentication information it holds. If the received authentication information matches the authentication information it holds, authentication is successful. If the received authentication information does not match the authentication information it holds, authentication fails. If authentication of the ONU 12 is successful, the management device 18 transmits permission for a logical connection with the ONU 12 (connection permission) to the OLT 11. For example, an administrator can operate the management device 18, causing the management device 18 to transmit permission for connection with the ONU 12. Specifically, the management device 18 transmits an OAM frame including connection permission information. The permission receiving unit 116 receives the connection permission from the management device 18.

[0078] When the permission receiving unit 116 receives permission to connect to the ONU 12, the third connecting unit 117 establishes a logical connection between the OLT 11 and the ONU 12. That is, a predetermined connection sequence is executed between the OLT 11 and the ONU 12, and a logical connection between the OLT 11 and the ONU 12 is established.

[0079] The first receiving unit 119 receives first control information for controlling the OLT 11 from the ONU-C 17 via the PON line 13. The first control information has been transmitted from the management device 18 to the ONU-C 17. Specifically, the management device 18 transmits an OAM frame including the first control information. The OAM frame transmitted from the management device 18 is converted into an optical signal in the ONU-C 17 and transmitted to the PON line 13. The first receiving unit 119 receives the OAM frame transmitted over the PON line 13.

[0080] The execution unit 120 executes a first control process based on the first control information received by the first receiving unit 119. The first control process is a process for managing the OLT 11. For example, the first control process is a process for reading a value in a specific area of ​​the volatile memory 213. For example, the specific area is an area for storing setting values ​​of the OLT 11. In another example, the first control process is a process for rewriting a value in a specific area of ​​the volatile memory 213, i.e., a process for changing the setting of the management module 21. In yet another example, the first control process is a process for reading a setting value stored in an area of ​​the volatile memory 223 of the line control module 22. In yet another example, the first control process is a process for rewriting a value in a specific area of ​​the volatile memory 223, i.e., a process for changing the setting of the line control module 22.

[0081] The first transmitting unit 121 transmits the first processing result to the ONU-C 17 via the PON line 13 in order to provide the management device 18 with the execution result of the first control processing by the executing unit 120 (hereinafter also referred to as the "first processing result"). Specifically, the first transmitting unit 121 transmits an OAM frame including the first processing result. The OAM frame transmitted to the PON line 13 as an optical signal is received by the ONU-C 17. The ONU-C 17 converts the OAM frame of the received optical signal into an electrical signal and transmits the converted OAM frame to the management device 18.

[0082] The second receiving unit 122 receives second control information for controlling the ONU 12 from the ONU-C 17 via the PON line 13. The second control information has been transmitted from the management device 18 to the ONU-C 17. Specifically, the management device 18 transmits an OAM frame including the second control information. The user area of ​​this OAM frame stores identification information of the ONU 12 to be controlled as the destination. The OAM frame transmitted from the management device 18 is converted into an optical signal in the ONU-C 17 and transmitted to the PON line 13. The second receiving unit 122 receives the OAM frame transmitted over the PON line 13.

[0083] The second transmitting unit 123 identifies the ONU 12 to be controlled from the destination information specified in the user area of ​​the OAM frame received by the second receiving unit 122. The second transmitting unit 123 transmits the second control information to the ONU 12 to be controlled. Specifically, the second transmitting unit 123 stores the LLID of the ONU 12 to be controlled in the preamble of the OAM frame including the second control information, and transmits the OAM frame to the PON line 13. The OAM frame transmitted to the PON line 13 as an optical signal is received by the ONU 12 to be controlled.

[0084] The ONU 12 executes a second control process based on the received second control information. The second control process is a process for managing the ONU 12. For example, the second control process is a process for reading a setting value stored in a volatile memory (not shown) provided in the ONU 12. In another example, the second control process is a process for rewriting a setting value in the volatile memory of the ONU 12, i.e., a process for changing the setting of the ONU 121.

[0085] The ONU 12 transmits an OAM frame including the execution result of the second control process (hereinafter also referred to as the "second process result") to the OLT 11. Specifically, the ONU 12 transmits the OAM frame including the second process result as an optical signal to the PON line 13. The user area of ​​the OAM frame stores identification information of the management device 18 as the destination.

[0086] The third receiving unit 124 receives, from the ONU 12, an execution result (second processing result) of the second control processing executed in the ONU 12 based on the second control information. Specifically, the third receiving unit 124 receives an OAM frame including the second processing result transmitted through the PON line 13.

[0087] The third transmitter 125 transmits the second processing result received by the third receiver 124 to the ONU-C 17 via the PON line 13 to provide the second processing result to the management device 18. Specifically, the third transmitter 125 identifies that the destination is the management device 18 from the user area of ​​the OAM frame received by the third receiver 124. If the destination is the management device 18, the logical link established between the OLT 11 and the ONU-C 17 is used. The third transmitter 125 replaces the LLID in the preamble of the OAM frame containing the second processing result with the LLID of the ONU-C 17, and transmits the OAM frame to the PON line 13. The OAM frame transmitted to the PON line 13 as an optical signal is received by the ONU-C 17. The ONU-C 17 converts the OAM frame of the received optical signal into an electrical signal, and transmits the converted OAM frame to the management device 18 .

[0088] The management device 18 includes, for example, a display. The management device 18 displays the received first processing result or second processing result on the display. This allows the administrator to check the first processing result or second processing result.

[0089] [1-5. Management Operation of Communication System] Hereinafter, the management operation of the communication system 10 by the management device 18 will be described.

[0090] FIG. 5 is a sequence diagram showing an example of a connection operation between the OLT, the ONU, the ONU-C, and the management device in the communication system 10. In FIG.

[0091] The OLT 11, ONU 12, ONU-C 17, and management device 18 start connection operations from a state in which they are not logically connected. First, a connection sequence between the management device 18 and ONU-C 17 is executed, and a connection between the management device 18 and ONU-C 17 is established (step S1). For example, in step S1, MAC addresses are exchanged between the management device 18 and ONU-C 17, which are connected by an Ethernet cable.

[0092] Next, the ONU-C17 transmits the authentication information to the management device 18 (step S2). The management device 18 compares the authentication information stored therein with the received authentication information, and executes authentication processing for the ONU-C17.

[0093] If the authentication of the ONU-C 17 is successful, the management device 18 activates the connected ONU-C 17 (step S3). For example, the administrator can operate the management device 18 to activate the ONU-C 17.

[0094] The OLT 11 searches for the activated ONU-C 17, for example, by periodically transmitting a search signal to the PON line 13 (step S4). Specifically, the search signal is broadcast and transmitted not only to the ONU-C 17 but also to the ONU 12. However, for simplicity, FIG. 5 shows the search signal transmitted only to the ONU-C 17. Upon receiving the search signal, the activated ONU-C 17 transmits a response signal (step S5). When the OLT 11 receives the response signal, a connection sequence between the OLT 11 and the ONU-C 17 is executed, and a logical connection (MPCP link and OAM link) between the OLT 11 and the ONU-C 17 is established (step S6). Meanwhile, even if the ONU 12 receives the search signal in step S4 and transmits a response signal, a logical connection with the OLT 11 is not established due to authentication failure.

[0095] When a logical connection between the OLT 11 and the ONU-C 17 is established, the ONU-C 17 transmits authentication information to the OLT 11 (step S7). Specifically, the authentication information of the ONU-C 17 is stored in the nonvolatile memory 172 of the ONU-C 17. The processor 171 reads the authentication information from the nonvolatile memory 172 and generates an OAM frame including the authentication information. The LLID of the ONU-C 17 is stored in the preamble of this OAM frame, and the identification information of the OLT 11 (e.g., a MAC address assigned to the management module 21 of the OLT 11) is stored in the user area as the destination, and the identification information of the ONU-C 17 (e.g., a MAC address assigned to the ONU-C 17) is stored as the source. The processor 171 outputs the generated OAM frame to the PON processing circuit 174. The PON processing circuit 174 transmits the input OAM frame to the optical transceiver 175. The OAM frame transmitted from the ONU-C 17 is received by the OLT 11.

[0096] The OAM frame is received by the optical transceiver 226 of the line control module 22 in the OLT 11. The PON processing circuit 224 outputs the OAM frame to the processor 221. The processor 221 outputs the OAM frame from the PHY 225 to the management module 21 via the signal line 228. The OAM frame is input to the processor 211 via the PHY 215.

[0097] The processor 211 confirms that the identification information of the OLT 11 is specified as the destination in the user area of ​​the OAM frame. The authentication information of the ONU-C 17 is stored in the nonvolatile memory 212 of the OLT 11. The processor 211 reads the authentication information from the nonvolatile memory 212. The processor 211 compares the authentication information extracted from the received OAM frame with the authentication information read from the nonvolatile memory 212, and executes authentication processing for the ONU-C 17.

[0098] If the OLT 11 successfully authenticates the ONU-C 17, a connection sequence between the management device 18 and the OLT 11 is executed, and a logical connection between the management device 18 and the OLT 11 is established (step S8).

[0099] Once a logical connection between the management device 18 and the OLT 11 is established, the management device 18 transmits authentication information to the OLT 11. Specifically, the management device 18 transmits an OAM frame including the authentication information (step S9). The user area of ​​this OAM frame stores the identification information of the OLT 11 as the destination and the identification information of the management device as the sender. The ONU-C 17 transmits the OAM frame received from the management device 18 as an optical signal to the OLT 11 via the PON line 13 (step S10). The transmission path of the OAM frame within the OLT 11 is the same as the transmission path within the OLT 11 of the OAM frame including the authentication information of the ONU-C 17 described above, and therefore a description thereof will be omitted.

[0100] The nonvolatile memory 212 of the OLT 11 stores authentication information for the management device 18. The processor 211 reads the authentication information from the nonvolatile memory 212. The processor 211 compares the authentication information extracted from the received OAM frame with the authentication information read from the nonvolatile memory 212, and executes authentication processing for the management device 18.

[0101] If the OLT 11 successfully authenticates the management device 18, the management device 18 transmits a search permission for the ONU 12 to the OLT 11. Specifically, the management device 18 transmits an OAM frame including the search permission for the ONU 12 (step S11). The user area of ​​this OAM frame stores the identification information of the OLT 11 as the destination and the identification information of the management device as the sender. The ONU-C 17 transmits the OAM frame received from the management device 18 as an optical signal to the OLT 11 via the PON line 13 (step S12).

[0102] The processor 211 of the OLT 11 receives the OAM frame. The processor 211 references the user area of ​​the OAM frame and confirms that the destination is the OLT 11 and the sender is the management device 18. The processor 211 extracts a discovery permission from the OAM frame and determines that discovery of the ONU 12 is permitted.

[0103] The OLT 11 searches for the ONU 12, for example, by periodically transmitting a search signal to the PON line 13 (step S13). When the ONU 12 receives the search signal, it transmits a response signal including authentication information for the ONU 12 (step S14). The search signal is also received by the ONU-C 17, but the ONU-C 17, which has already established a logical connection with the OLT 11, does not transmit a response signal. When the OLT 11 receives the response signal from the ONU 12, it transmits an inquiry regarding whether or not a connection to the ONU 12 is possible (step S15). Specifically, the processor 211 of the OLT 11 generates an OAM frame including an inquiry regarding whether or not a connection is possible. The user area of ​​this OAM frame stores the identification information of the management device as the destination and the identification information of the OLT 11 as the source. The OLT 11 transmits this OAM frame to the PON line 13 (step S15). When ONU-C17 receives the connection availability inquiry OAM frame, it transmits the OAM frame to the management device 18, which is the destination (step S16). Specifically, the optical signal OAM frame is received by the optical transceiver 175 of ONU-C17 and converted into an electrical signal. The PON processing circuit 174 outputs the OAM frame to the processor 171. When the processor 171 confirms that the identification information of the management device 18 is specified as the destination in the user area of ​​the OAM frame, it transmits the OAM frame to the management device 18 via the interface 176.

[0104] When the management device 18 receives the connection availability inquiry OAM frame, it references the user area and confirms that the destination is the management device 18 and the sender is the OLT 11. The management device 18 extracts authentication information for the ONU 12 from the OAM frame. The management device 18 stores the authentication information for the ONU 12. The management device 18 compares the authentication information extracted from the received OAM frame with the stored authentication information and performs authentication processing for the ONU 12.

[0105] If the management device 18 successfully authenticates the ONU 12, the management device 18 transmits a permission to connect to the ONU 12 to the OLT 11. Specifically, the management device 18 transmits an OAM frame including permission to connect to the ONU 12 (step S17). The user area of ​​this OAM frame stores the identification information of the OLT 11 as the destination and the identification information of the management device as the sender. The ONU-C 17 transmits the OAM frame received from the management device 18 as an optical signal to the OLT 11 via the PON line 13 (step S18).

[0106] The processor 211 of the OLT 11 receives the OAM frame, extracts the connection permission from the OAM frame, and determines that the connection with the ONU 12 is permitted.

[0107] When the connection between the OLT 11 and the ONU 12 is permitted, a connection sequence between the OLT 11 and the ONU 12 is executed, and a logical connection between the OLT 11 and the ONU 12 is established (step S19).

[0108] This completes the connection operation of the OLT, ONU, ONU-C, and management device in the communication system 10.

[0109] Figure 6 is a sequence diagram showing an example of an OLT management operation (hereinafter also referred to as a "first management operation") and an ONU management operation (hereinafter also referred to as a "second management operation") in the communication system 10 of the first embodiment.

[0110] In the first management operation, the management device 18 transmits first control information to the OLT 11. Specifically, the management device 18 transmits an OAM frame including the first control information (step S101). The user area of ​​this OAM frame stores identification information of the OLT 11 as the destination and identification information of the management device 18 as the source. The ONU-C 17 transmits the OAM frame received from the management device 18 as an optical signal to the OLT 11 via the PON line 13 (step S102).

[0111] The OAM frame of the optical signal is converted into an electrical signal by the optical transceiver 226 of the line control module 22. The PON processing circuit 224 extracts the OAM frame from the upstream signal and outputs the extracted OAM frame to the processor 221. The processor 221 outputs the OAM frame including the first control information from the PHY 225 to the management module 21 via the signal line 228. The OAM frame is input to the processor 211 via the PHY 215.

[0112] The processor 211 of the OLT 11 extracts the first control information from the received OAM frame, and executes the first control process based on the first control information (step S103).

[0113] The OLT 11 transmits a first processing result, which is the execution result of the first control information, to the management device 18. Specifically, the processor 211 generates an OAM frame including the first processing result, and outputs the generated OAM frame from the PHY 215 to the line control module 22 via the signal line 228. The user area of ​​this OAM frame stores identification information of the management device 18 as the destination, and identification information of the OLT 11 as the source. The OAM frame is input to the processor 221 via the PHY 225. The processor 221 outputs the input OAM frame to the PON processing circuit 224. The PON processing circuit 224 causes the optical transceiver 226 to transmit the input OAM frame (step S104).

[0114] The optical signal of the OAM frame transmitted from the OLT 11 is received by the ONU-C 17. The PON processing circuit 174 of the ONU-C 17 outputs the OAM frame to the processor 171. When the processor 171 confirms that the identification information of the management device 18 is specified as the destination in the user area of ​​the OAM frame, it transmits the OAM frame from the interface 176 to the management device 18 (step S105). The management device 18 receives the OAM frame and displays the first processing result contained in the OAM frame, for example, on a display. This completes the first management operation.

[0115] In the second management operation, the management device 18 transmits second control information to the ONU 12 via the OLT 11. Specifically, the management device 18 transmits an OAM frame including the second control information (step S111). In the user area of ​​this OAM frame, identification information of the ONU 12 to be controlled is stored as the destination, and identification information of the management device 18 is stored as the source. The ONU-C 17 transmits the OAM frame received from the management device 18 as an optical signal to the OLT 11 via the PON line 13 (step S112).

[0116] The OAM frame of the optical signal is converted into an electrical signal by the optical transceiver 226 of the line control module 22. The PON processing circuit 224 extracts the OAM frame from the downstream signal and outputs the extracted OAM frame to the processor 221. The processor 221 outputs the OAM frame including the second control information from the PHY 225 through the signal line 228 to the management module 21. The OAM frame is input to the processor 211 via the PHY 215.

[0117] When the processor 211 recognizes that the destination is specified as the ONU 12 in the user area of ​​the received OAM frame, it outputs the OAM frame to the line control module 22. The OAM frame is output to the PON processing circuit 224 via the processor 221. The PON processing circuit 224 outputs the OAM frame to the optical transceiver 226, and the optical transceiver 226 transmits the optical signal of the OAM frame to the PON line 13. The OAM frame transmitted through the PON line 13 is received by the ONU 12 to be controlled (step S113).

[0118] A processor (not shown) of the ONU 12 extracts the second control information from the received OAM frame and executes the second control process based on the second control information (step S114).

[0119] The ONU 12 transmits the second processing result, which is the execution result of the second control information, to the management device 18 via the OLT 11. Specifically, the ONU 12 transmits an OAM frame including the second processing result as an optical signal to the PON line 13. The user area of ​​this OAM frame stores identification information of the management device 18 as the destination and identification information of the ONU 12 as the sender. The OAM frame transmitted over the PON line 13 is received by the OLT 11 (step S115).

[0120] When the processor 211 of the OLT 11 recognizes that the destination of the received OAM frame is the management device 18, it outputs the OAM frame to the line control module 22. The OAM frame is output to the PON processing circuit 224 via the processor 221. The PON processing circuit 224 outputs the OAM frame to the optical transceiver 226, and the optical transceiver 226 transmits the optical signal of the OAM frame to the PON line 13. The OAM frame transmitted through the PON line 13 is received by the ONU-C 17 (step S116).

[0121] The PON processing circuit 174 of ONU-C17 outputs the received OAM frame to the processor 171. When the processor 171 recognizes that the destination of the OAM frame is the management device, it transmits the OAM frame to the management device 18 (step S117). The management device 18 receives the OAM frame and displays the second processing result included in the OAM frame, for example, on a display. This completes the second management operation.

[0122] 2. Second Embodiment Referring to FIG. 3, in the second embodiment, the management device 18 is connected to the UNI port 177 instead of the interface 176 of the ONU-C 17 .

[0123] 7 is a block diagram showing an example of the internal configuration of an OLT according to the second embodiment. As shown in Fig. 7, the OLT 11 according to the second embodiment further includes an L2 switch 23. The other configurations of the communication system according to the second embodiment are the same as those of the communication system 10 according to the first embodiment, and therefore, description thereof will be omitted.

[0124] The L2 switch 23 includes a plurality of ports. A first port 231 of the L2 switch 23 is connected to the upper network 50. A second port 232 of the L2 switch 23 is connected to the PON processing circuit 224. A third port 233 of the L2 switch 23 is connected to the interface 214. Here, the interface 214 includes an Ethernet interface.

[0125] In the first embodiment, OAM frames were used to communicate between the management device 18 and the OLT 11 and ONU 12, but in the second embodiment, Ethernet frames (user frames) capable of accommodating user data (data communicated between the upper network 50 and the lower network) are used for communication between the management device 18 and the OLT 11 and ONU 12. Hereinafter, frames used for communication between the management device 18 and the OLT 11 or ONU 12 are also referred to as "OAM user frames."

[0126] An OAM user frame includes a destination address field and a source address field. The destination address field stores the MAC address of the destination. The source address field stores the MAC address of the source. The data field of the OAM user frame stores the MAC address of the final destination.

[0127] For example, in an OAM user frame (a frame storing authentication information of the management device 18, a frame storing first control information, etc.) transmitted from the management device 18 to (the management module 21 of) the OLT 11, the destination address field stores the MAC address of the management module 21 of the OLT 11, and the source address field stores the MAC address of the management device 18. The data field of this OAM user frame stores the MAC address of the management module 21 of the OLT 11 as the final destination.

[0128] The frame received by the OLT 11 is output from the PON processing circuit 224 to the second port 232 of the L2 switch 23. The MAC address assigned to the management module 21 is specified as the destination of the OAM user frame transmitted from the management device 18. The L2 switch 23 outputs the OAM user frame, for which the MAC address of the management module 21 is specified as the destination, from the third port 233 to the interface 214. The interface 214 outputs the input OAM user frame to the processor 211. The processor 211 confirms that the MAC address of the management module 21 is specified as the final destination in the data field of the OAM user frame, and recognizes that the final destination of this frame is the management module 21.

[0129] For example, in an OAM user frame (such as a frame storing the first processing result) sent from OLT 11 to management device 18, the MAC address of management device 18 is stored in the destination address field, and the MAC address of management module 21 of OLT 11 is stored in the source address field.

[0130] The processor 211 outputs the generated OAM user frame to the interface 214, and the interface 214 outputs the input OAM user frame to the third port 233 of the L2 switch 23. Since the destination of the OAM user frame input from the interface 214 to the third port 233 is the MAC address of the management device 18, the L2 switch 23 outputs this OAM user frame from the second port 232 to the PON processing circuit 224. The OAM user frame is output from the PON processing circuit 224 to the optical transceiver 226 and transmitted to ONU-C17 via the PON line 13. The ONU-C17 transmits the received OAM user frame from the UNI port 177 to the management device 18.

[0131] For example, in an OAM user frame (such as a frame storing second control information) transmitted from the management device 18 to the ONU 12, the destination address field stores the MAC address of the management module 21 of the OLT 11, and the source address field stores the MAC address of the management device 18. The data field of this OAM user frame stores the MAC address of the ONU 12 to be controlled as the final destination.

[0132] The destination of the OAM user frame transmitted from the management device 18 is specified as the MAC address assigned to the management module 21. The L2 switch 23 outputs the OAM user frame, for which the MAC address of the management module 21 is specified as the destination, from the third port 233 to the interface 214. The interface 214 outputs the input OAM user frame to the processor 211. The processor 211 confirms that the MAC address of the ONU 12 is specified as the final destination in the data field of the OAM user frame, and rewrites the destination of the OAM user frame to the MAC address of the ONU 12, which is the final destination.

[0133] The processor 211 outputs the OAM user frame, the destination of which has been rewritten to the MAC address of the ONU 12, to the interface 214, and the interface 214 outputs the input OAM user frame to the third port 233 of the L2 switch 23. Since the destination of the OAM user frame input from the interface 214 to the third port 233 is the MAC address of the ONU 12, the L2 switch 23 outputs this OAM user frame from the second port 232 to the PON processing circuit 224. The OAM user frame is output from the PON processing circuit 224 to the optical transceiver 226 and transmitted to the ONU 12 to be controlled via the PON line 13.

[0134] For example, in an OAM user frame (such as a frame storing the second processing result) transmitted from the ONU 12 to the management device 18, the destination address field stores the MAC address of the management module 21 of the OLT 11, and the source address field stores the MAC address of the ONU 12 to be controlled. The data field of this OAM user frame stores the MAC address of the management device 18 as the final destination.

[0135] The destination of the above-mentioned OAM user frame transmitted from the ONU 12 is specified as the MAC address assigned to the management module 21. The L2 switch 23 outputs the OAM user frame, for which the MAC address of the management module 21 is specified as the destination, from the third port 233 to the interface 214. The interface 214 outputs the input OAM user frame to the processor 211. The processor 211 confirms that the MAC address of the management device 18 is specified as the final destination in the data field of the OAM user frame, and rewrites the destination of the OAM user frame to the MAC address of the management device 18, which is the final destination.

[0136] The processor 211 outputs the OAM user frame, the destination of which has been rewritten to the MAC address of the management device 18, to the interface 214, and the interface 214 outputs the input OAM user frame to the third port 233 of the L2 switch 23. Since the destination of the OAM user frame input from the interface 214 to the third port 233 is the MAC address of the management device 18, the L2 switch 23 outputs the OAM user frame from the second port 232 to the PON processing circuit 224. The OAM user frame is output from the PON processing circuit 224 to the optical transceiver 226 and transmitted to the ONU-C17 via the PON line 13. The ONU-C17 transmits the received OAM user frame from the UNI port 177 to the management device 18.

[0137] A MAC address different from the MAC address of the management module 21 is specified as the destination of the data frame received by the UNI of the ONU 12 and transmitted from the ONU 12 to the PON line 13 .

[0138] The L2 switch 23 transmits a data frame, the destination of which is a MAC address different from the MAC address of the management module 21 , from the first port 231 to the upper network 50 .

[0139] A downstream signal data frame transmitted from the upper network 50 is input to a first port 231 of the L2 switch 23. The L2 switch 23 outputs the downstream signal data frame input to the first port 231 from a second port 232 to the PON processing circuit 224.

[0140] 3. Third Embodiment 3-1. Communication System FIG. 8 is a diagram showing an example of the overall configuration of a communication system according to the third embodiment.

[0141] The OLT 11A according to the third embodiment includes a first line port 131 and a second line port 132. The first line port 131 is connected to a first PON line 13A. The second line port 132 is connected to a second PON line 13B that is different from the first PON line. The first PON line 13A is an example of a first communication line, and the second PON line 13B is an example of a second communication line.

[0142] The first PON line 13A is an optical communication line including an optical splitter 14A1 and optical fibers 151 and 16A1. The first PON line 13A includes one trunk optical fiber 151 and multiple branch optical fibers 16A1. The optical splitter 14A1 is connected to the end of the trunk optical fiber 151, i.e., the end opposite to the end connected to the first line port 131 of the OLT 11. The optical splitter 14A1 is connected to multiple branch optical fibers 16A1. An ONU 12A is connected to each of the branch optical fibers 16A1.

[0143] The second PON line 13B is an optical communication line including optical splitters 14A2 and 14B and optical fibers 152A, 152B, 16A2, and 16B. The second PON line 13B includes trunk optical fibers 152A and 152B and multiple branch optical fibers 16A2 and 16B. A first end of the trunk optical fiber 152A is connected to the OLT 11A. A second end of the trunk optical fiber 152A and a first end of the trunk optical fiber 152B are connected via the optical splitter 14B. The second end of the trunk optical fiber 152B, i.e., the end opposite to the end connected to the optical splitter 14B, is connected to the optical splitter 14A2. A multiple branch optical fibers 16A2 are connected to the optical splitter 14A2. An ONU 12B is connected to each of the branch optical fibers 16A2. The trunk optical fibers 152A and 152B according to the third embodiment are another example of a trunk communication line. The branch optical fiber 16A2 according to the third embodiment is another example of a first branch communication line.

[0144] The second PON line 13B in the third embodiment has the same configuration as the PON line 13 in the first embodiment. That is, a first end of a branch optical fiber 16B is connected to the optical splitter 14B. A second end of the branch optical fiber 16B is connected to the ONU-C17. A management device 18 is connected to the ONU-C17 via a communication cable. The branch optical fiber 16B in the third embodiment is another example of a second branch communication line. However, the ONU-C17 only needs to be connected to any branch line of the PON, and is not limited to the connection configuration shown in FIG. 8 . Note that the configurations of the ONU-C17, ONUs 12A and 12B, and management device 18 in the third embodiment are the same as the configurations of the ONU-C17, ONUs 12A, 12B, and management device 18 in the first embodiment, and therefore description thereof will be omitted.

[0145] [4-2. Internal Configuration of OLT] As described above, the OLT 11A according to the third embodiment includes the first line port 131 and the second line port 132. The OLT 11A is connected to two trunk optical fibers 151, 152A at the first line port 131 and the second line port 132.

[0146] Fig. 9 is a block diagram showing an example of the internal configuration of an OLT 11A according to the third embodiment. As shown in Fig. 9, the OLT 11A according to the third embodiment includes one management module 21A and two line control modules 22A and 22B.

[0147] The line control module 22A is connected to the first PON line 13A and controls communications on the first PON line 13A. The line control module 22B is connected to the second PON line 13B and controls communications on the second PON line 13B. The line control module 22A is an example of a first communication module, and the line control module 22B is an example of a second communication module. The line control module 22A controls communications with the ONU 12A, which is the opposing device. The line control module 22B controls communications with the ONU 12B and ONU-C 17, which are opposing devices.

[0148] The line control module 22A includes a processor 221A (first processor), a non-volatile memory 222A, a volatile memory 223A, a PON processing circuit 224A (first communication processing circuit), a PHY 225A, and an optical transceiver 226A. The line control module 22B includes a processor 221B (second processor), a non-volatile memory 222B, a volatile memory 223B, a PON processing circuit 224B (second communication processing circuit), a PHY 225B, and an optical transceiver 226B. The basic configuration of the line control modules 22A and 22B is the same as the basic configuration of the line control module 22 described in the first embodiment, so description thereof will be omitted.

[0149] The optical transceiver 226A of the line control module 22A is connected to the trunk optical fiber 151. The optical transceiver 226A constitutes the first line port 131. The optical transceiver 226B of the line control module 22B is connected to the trunk optical fiber 152A. The optical transceiver 226B constitutes the second line port 132.

[0150] The PON processing circuit 224A of the line control module 22A executes a predetermined communication process (first communication process) conforming to the PON communication standard for communication between the OLT 11 and the ONU 12A. The PON processing circuit 224B of the line control module 22B executes a predetermined communication process (second communication process) conforming to the PON communication standard for communication between the OLT 11 and the ONU 12B and the ONU-C 17.

[0151] The OLT 11A includes an L2 switch 23A. The L2 switch 23A includes a plurality of ports. A first port 231A of the L2 switch 23A is connected to the upper network 50. A second port 232A of the L2 switch 23A is connected to the PON processing circuit 224A of the line control module 22A. A third port 233A of the L2 switch 23A is connected to the PON processing circuit 224B of the line control module 22B.

[0152] A downstream signal frame from the upper network 50 is input to the first port 231A of the L2 switch 23A. The downstream signal includes a data frame addressed to the MAC address of a customer access point included in the lower network.

[0153] The L2 switch 23A outputs data frames addressed to the MAC address of a customer access device connected to an ONU 12A connected to the first PON line 13A from the second port 232A to the line control module 22A. When the PON processing circuit 224A of the line control module 22A receives the data frames from the L2 switch 23A, it outputs the received data frames to the optical transceiver 226A. The optical transceiver 226A transmits the input data frames as optical signals to the first PON line 13A. The ONU 12A receives the data frames transmitted over the first PON line 13A and transmits the received data frames to the destination customer access device.

[0154] The L2 switch 23A outputs data frames addressed to the MAC address of a customer access device connected to an ONU 12B connected to the second PON line 13B from the third port 233A to the line control module 22B. When the PON processing circuit 224B of the line control module 22B receives the data frames from the L2 switch 23A, it outputs the received data frames to the optical transceiver 226B. The optical transceiver 226B transmits the input data frames as optical signals to the second PON line 13B. The ONU 12B receives the data frames transmitted over the second PON line 13B and transmits the received data frames to the destination customer access device.

[0155] The management module 21A is connected to the line control modules 22A and 22B and manages the line control modules 22A and 22B.

[0156] The management module 21A includes two PHYs 215A1 and 215A2. Each of the PHYs 215A1 and 215A2 is connected to the processor 211 by a signal line. The line control module 22A includes a PHY 225A, and the line control module 22B includes a PHY 225B. In the line control module 22A, the PHY 225A is connected to the processor 221A by a signal line. In the line control module 22B, the PHY 225B is connected to the processor 221B by a signal line. The PHY 225A1 of the line control module 22A is connected to the PHY 215A1 of the management module 21A by a signal line. The PHY 225B1 of the line control module 22B is connected to the PHY 215A2 of the management module 21A by a signal line. The other configurations of the management module 21A are the same as those of the management module 21 according to the first embodiment.

[0157] For example, as the first control process, processor 211 can output a command to processor 221A based on the first control information. Processor 221A can output a response to the command received from processor 211 to processor 211. Processor 211 receives the response from processor 221A. In another example, processor 211 can output a command to processor 221B based on the first control information as the first control process. Processor 221B can output a response to the command received from processor 211 to processor 211. Processor 211 receives the response from processor 221B.

[0158] In the third embodiment, OAM frames defined in IEEE802.3ah are used for communication between the management device 18 and the OLT 11A, communication between the management device 18 and the ONU 12A, and communication between the management device 18 and the ONU 12B.

[0159] In an OAM frame (such as an OAM frame storing first control information) transmitted from the management device 18 to the OLT 11A, the identification information of the OLT 11A is specified as the destination in the user area, and the identification information of the management device 18 is specified as the source. The OAM frame transmitted from the management device 18 to the second PON line 13 via the ONU-C 17 is received by the optical transceiver 226B of the OLT 11A and output as an electrical signal from the optical transceiver 226B to the PON processing circuit 224B. The PON processing circuit 224B outputs the input OAM frame to the processor 221B. The processor 221B outputs the OAM frame from the PHY 225B to the processor 211 of the management module 21A. The processor 211 confirms that the identification information of the OLT 11A is specified as the destination in the user area of ​​the OAM frame, and recognizes that the destination of this OAM frame is the OLT 11A (the management module 21A of the OLT 11A).

[0160] In an OAM frame transmitted from the management device 18 to the ONU 12A (such as an OAM frame storing second control information for the ONU 12A as the control target), the identification information of the ONU 12A is specified as the destination in the user area, and the identification information of the management device 18 is specified as the sender. The OAM frame transmitted from the management device 18 to the second PON line 13 via the ONU-C 17 is received by the optical transceiver 226B of the OLT 11A and output as an electrical signal from the optical transceiver 226B to the PON processing circuit 224B. The PON processing circuit 224B outputs the input OAM frame to the processor 221B. The processor 221B outputs the OAM frame from the PHY 225B to the processor 211 of the management module 21A.

[0161] The processor 211 confirms that the identification information of the ONU 12A is specified as the destination in the user area of ​​the OAM frame, and recognizes that the destination of this OAM frame is the ONU 12A. The processor 211 outputs the OAM frame to the line control module 22A via the PHY 215A1.

[0162] The OAM frame is output from the PHY 225A to the PON processing circuit 224A via the processor 221A. The PON processing circuit 224A causes the optical transceiver 226A to transmit the input OAM frame to the first PON line 13A.

[0163] In an OAM frame transmitted from management device 18 to ONU 12B (such as an OAM frame storing second control information whose control target is ONU 12B), the identification information of ONU 12B is specified as the destination in the user area, and the identification information of management device 18 is specified as the sender. This OAM frame is provided to processor 211 in the same manner as the OAM frame whose destination is ONU 12A described above.

[0164] The processor 211 confirms that the identification information of the ONU 12B is specified as the destination in the user area of ​​the OAM frame, and recognizes that the destination of this OAM frame is the ONU 12B. The processor 211 outputs this OAM frame to the line control module 22B via the PHY 215A2.

[0165] The OAM frame is output from the PHY 225B via the processor 221B to the PON processing circuit 224B. The PON processing circuit 224B causes the optical transceiver 226B to transmit the input OAM frame to the second PON line 13B. However, the processor 221A or 221B of the line control module 22A or 22B may refer to the user area of ​​the OAM frame to confirm the destination. For example, if ONU 12A or ONU 12B is specified as the destination in the user area of ​​the OAM frame, the processor 221A or 221B may output the OAM frame to the PON processing circuit 224A or 224B instead of the processor 211. This allows the OAM frame to be transferred to the PON line 13A or 13B without passing through the processor 211.

[0166] 4-3. Management Operation of Communication System The following describes the management operation of the communication system 10A according to the third embodiment. Note that a description of the same operations as those of the communication system 10 according to the first embodiment will be omitted.

[0167] 6 . In the first management operation, the management device 18 transmits first control information to the OLT 11A. Specifically, the management device 18 transmits an OAM frame including the first control information (step S101). In the user area of ​​this OAM frame, identification information of the OLT 11A is stored as the destination, and identification information of the management device 18 is stored as the sender. The OAM frame is received by the OLT 11A via the ONU-C 17 (step S102).

[0168] When the OLT 11A recognizes that the destination of the received OAM frame is the OLT 11A and the sender is the management device 18, it executes a first control process. The OLT 11A transmits the execution result of the first control process (first process result) to the management device 18 (step S104). In the user area of ​​the OAM frame that stores the first process result, identification information of the management device 18 is stored as the destination, and identification information of the OLT 11A is stored as the sender. The OAM frame is received by the management device 18 via the ONU-C 17 (step S105). This completes the first management operation.

[0169] Next, a second management operation of the communication system 10A will be described. This second management operation is for managing the ONU 12A connected to the first PON line 13A. In this operation, the management device 18 transmits second control information for managing the ONU 12A connected to the first PON line 13A to the ONU 12A via the OLT 11A. Specifically, the management device 18 transmits an OAM frame including the second control information (step S111). The user area of ​​this OAM frame stores the identification information of the ONU 12A to be controlled as the destination, and the identification information of the management device 18 as the sender. The OAM frame is received by the OLT 11A via the ONU-C 17 (step S112).

[0170] Upon receiving the OAM frame, the OLT 11A recognizes that the destination of this OAM frame is the ONU 12A, and transmits the OAM frame to the ONU 12A via the first PON line 13A (step S113).

[0171] When ONU 12A recognizes that the destination of the received OAM frame is ONU 12A and the sender is management device 18, it executes a second control process. ONU 12A transmits the execution result of the second control process (second process result) to management device 18 via OLT 11A. In the user area of ​​the OAM frame containing the second process result, identification information of management device 18 is stored as the destination, and identification information of ONU 12A is stored as the sender. The OAM frame of the upstream signal transmitted on first PON line 13A is received by OLT 11A (step S115).

[0172] Upon receiving the OAM frame, the OLT 11A recognizes that the destination of this OAM frame is the management device 18. The OLT 11A transmits the OAM frame to the second PON line 13B (step S116).

[0173] The OAM frame is received by the ONU-C 17 and transmitted from the ONU-C 17 to the management device 18 (step S117). This completes the second management operation.

[0174] In the communication system 10A according to the third embodiment, it is also possible to execute a second management operation for managing the ONU 12B connected to the second PON line 13B. In this operation, the OAM frame including the second control information transmitted from the management device 18 stores the identification information of the ONU 12B as the destination in the user area. Otherwise, the second management operation is similar to the second management operation for managing the ONU 12A described above, and therefore a description thereof will be omitted.

[0175] In the illustrated embodiment, two PHYs 215A1 and 215A2 are provided in the management module 21A, and the processor 211 is connected to the processor 221A of the line control module 22A via PHY 215A1 (and PHY 225A), and to the processor 221B of the line control module 22B via PHY 215A2 (and PHY 225B). However, the present invention is not limited to this. Instead of PHYs 215A1 and 215A2, an L2 switch may be provided in the management module 21A, with the processor 211 connected to a first port of the L2 switch, the processor 221A connected to a second port via PHY 225A, and the processor 221B connected to a third port via PHY 225B.

[0176] [5. Fourth Embodiment] [5-1. Internal Configuration of OLT] In the fourth embodiment, similarly to the second embodiment, the management device 18 is connected to the UNI port 177, not to the interface 176 of the ONU-C 17. In the fourth embodiment, an OAM user frame is used for communication between the management device 18 and the OLT 11A, the ONU 12A, or the ONU 12B.

[0177] 9 . In the OLT 11A according to the fourth embodiment, the L2 switch 23A further includes a fourth port 234A. The management module 21A further includes a PHY 215A3. The fourth port 234A of the L2 switch 23A and the PHY 215A3 are connected to each other by a signal line indicated by a dashed line in the figure. The PHY 215A3 is connected to the processor 211 by a signal line indicated by a dashed line in the figure. The other configurations of the communication system according to the fourth embodiment are the same as those of the communication system 10A according to the third embodiment.

[0178] In the fourth embodiment, the PON processing circuits 224A and 224B output the OAM user frames in the upstream signals together with other frames to the L2 switch 23A.

[0179] For example, in an OAM user frame (a frame storing authentication information of the management device 18, a frame storing first control information, etc.) transmitted from the management device 18 to (the management module 21A of) the OLT 11A, the destination address field stores the MAC address of the management module 21A of the OLT 11A, and the source address field stores the MAC address of the management device 18. The data field of this OAM user frame stores the MAC address of the management module 21A of the OLT 11A as the final destination.

[0180] For example, when the L2 switch 23A receives an OAM user frame whose destination is the MAC address assigned to the management module 21A of the OLT 11A, it outputs the OAM user frame from the fourth port 234A via the PHY 215A3 to the processor 211. The processor 211 confirms that the MAC address of the management module 21A is specified as the final destination in the data field of the OAM user frame, and recognizes that the final destination of this frame is the management module 21A.

[0181] For example, in an OAM user frame (such as a frame storing the first processing result) sent from OLT 11A to management device 18, the MAC address of management device 18 is stored in the destination address field, and the MAC address of management module 21 of OLT 11A is stored in the source address field.

[0182] The processor 211 outputs the generated OAM user frame to the fourth port 234A of the L2 switch 23A via the PHY 215A3. Because the destination of the OAM user frame input to the fourth port 234A is the MAC address of the management device 18, the L2 switch 23A outputs this OAM user frame from the third port 233A to the PON processing circuit 224B. The OAM user frame is output from the PON processing circuit 224B to the optical transceiver 226B and transmitted to ONU-C17 via the second PON line 13B. The ONU-C17 transmits the received OAM user frame from the UNI port 177 to the management device 18.

[0183] For example, in an OAM user frame (such as a frame storing second control information) transmitted from the management device 18 to the ONU 12A, the destination address field stores the MAC address of the management module 21A of the OLT 11A, and the source address field stores the MAC address of the management device 18. The data field of this OAM user frame stores the MAC address of the ONU 12A to be controlled as the final destination.

[0184] The MAC address assigned to the management module 21A is specified as the destination of the OAM user frame transmitted from the management device 18. This OAM user frame is output from the fourth port 234A of the L2 switch 23A via the PHY 215A3 to the processor 211. The processor 211 confirms that the MAC address of the ONU 12A is specified as the final destination in the data field of the OAM user frame, and rewrites the destination of the OAM user frame to the MAC address of the ONU 12A.

[0185] The processor 211 outputs the OAM user frame with the rewritten destination to the fourth port 234A of the L2 switch 23A via the PHY 215A3. Because the destination of the OAM user frame input to the fourth port 234A is the MAC address of the ONU 12A, the L2 switch 23A outputs this OAM user frame from the second port 232A to the PON processing circuit 224A. The OAM user frame is output from the PON processing circuit 224A to the optical transceiver 226A and transmitted to the ONU 12A to be controlled via the first PON line 13A.

[0186] For example, in an OAM user frame (such as a frame storing the second processing result) transmitted from the ONU 12A to the management device 18, the destination address field stores the MAC address of the management module 21A of the OLT 11A, and the source address field stores the MAC address of the ONU 12A to be controlled. The data field of this OAM user frame stores the MAC address of the management device 18 as the final destination.

[0187] The destination of the OAM user frame sent from ONU 12A is specified as the MAC address assigned to the management module 21A. This OAM user frame is output from the fourth port 234A of the L2 switch 23A via PHY 215A3 to the processor 211. The processor 211 confirms that the MAC address of the management device 18 is specified as the final destination in the data field of the OAM user frame, and rewrites the destination of the OAM user frame to the MAC address of the management device 18. Thereafter, the OAM user frame is transmitted to the management device 18 via the same transmission path as the OAM user frame that stores the first processing result.

[0188] For example, in an OAM user frame (such as a frame storing the second processing result) transmitted from ONU 12B to management device 18, the destination address field stores the MAC address of management module 21A of OLT 11A, and the source address field stores the MAC address of ONU 12B to be controlled. The data field of this OAM user frame stores the MAC address of management device 18 as the final destination.

[0189] The destination of the OAM user frame sent from ONU 12B is specified as the MAC address assigned to the management module 21A. This OAM user frame is output from the fourth port 234A of the L2 switch 23A via PHY 215A3 to the processor 211. The processor 211 confirms that the MAC address of the management device 18 is specified as the final destination in the data field of the OAM user frame, and rewrites the destination of the OAM user frame to the MAC address of the management device 18. Thereafter, the OAM user frame is transmitted to the management device 18 via the same transmission path as the OAM user frame that stores the first processing result.

[0190] 5-2. Management Operation of Communication System The management operation of the communication system 10A according to the fourth embodiment will be described below. Note that a description of the same operations as those of the communication system 10 according to the first embodiment will be omitted.

[0191] Referring to FIG. 6, a first management operation of the communication system 10A will be described first. The management device 18 transmits first control information to the OLT 11A. Specifically, the management device 18 transmits an OAM user frame including the first control information (step S101). The destination of this OAM user frame is specified as the MAC address of the management module 21A, and the source is specified as the MAC address of the management device 18. In the data field of this OAM user frame, the MAC address of the management module 21A is specified as the final destination. The OAM user frame is received by the OLT 11A via the ONU-C 17 (step S102).

[0192] The OLT 11A refers to the data field of the received OAM user frame, and when it confirms that the final destination is the management module 21A, it executes the first control process using the first control information (step S103).

[0193] The OLT 11A transmits the first processing result to the management device 18 (step S104). Specifically, the processor 211 generates an OAM user frame including the first processing result. The MAC address of the management device 18 is specified as the destination of this OAM user frame, and the MAC address of the management module 21A is specified as the source. In the data field of this OAM user frame, the MAC address of the management device 18 is specified as the final destination. The OAM user frame is received by the management device 18 via the ONU-C 17 (step S105). This completes the first management operation.

[0194] Next, a second management operation of the communication system 10A will be described. Specifically, the second management operation for managing the ONU 12A connected to the first PON line 13A will be described. In this operation, the management device 18 transmits second control information for controlling the ONU 12A to the OLT 11A. Specifically, the management device 18 transmits an OAM user frame including the second control information (step S111). The destination of this OAM user frame is specified as the MAC address of the management module 21A, and the source is specified as the MAC address of the management device 18. In the data field of this OAM user frame, the MAC address of the ONU 12A is specified as the final destination. The OAM user frame is received by the OLT 11A via the ONU-C 17 (step S112).

[0195] The OLT 11A refers to the data field of the received OAM user frame, and when it confirms that the final destination is the ONU 12A, it rewrites the destination of the OAM user frame to the MAC address of the ONU 12A.

[0196] The OLT 11A transmits the OAM user frame with the rewritten destination to the ONU 12A via the first PON line 13A (step S113).

[0197] The ONU 12A transmits the second processing result to the OLT 11A (step S115). Specifically, the processor 211 generates an OAM user frame including the second processing result. The destination of this OAM user frame is specified as the MAC address of the management module 21A, and the source is specified as the MAC address of the ONU 12A. In the data field of this OAM user frame, the MAC address of the management device 18 is specified as the final destination.

[0198] The OLT 11 A refers to the data field of the received OAM user frame, and when it confirms that the final destination is the management device 18 , it rewrites the destination of the OAM user frame to the MAC address of the management device 18 .

[0199] The OLT 11A transmits the OAM user frame with the rewritten destination to the second PON line 13B (step S116). The OAM user frame is transmitted from the ONU-C 17 to the management device 18 (step S117). This completes the second management operation.

[0200] In the communication system 10A according to the fourth embodiment, it is also possible to execute a second management operation for managing the ONU 12B connected to the second PON line 13B. In this operation, the MAC address of the ONU 12B is stored as the final destination in the data field of an OAM user frame including second control information transmitted from the management device 18. Other than that, this second management operation is similar to the second management operation for managing the ONU 12A described above, and therefore a description thereof will be omitted.

[0201] 6. Fifth Embodiment An example of the internal configuration of an OLT 11A according to a fifth embodiment will be described with reference to Fig. 9. In Fig. 9, the line control module 22A is shown to include one optical transceiver 226A, and the line control module 22B is shown to include one optical transceiver 226B, but in the fifth embodiment, the OLT 11A has a line control module 22A that includes multiple optical transceivers 226A, and a line control module 22B that includes multiple optical transceivers 226B.

[0202] In the line control module 22A, the PON processing circuit 224A is connected to each optical transceiver 226A. In the line control module 22B, the PON processing circuit 224B is connected to each optical transceiver 226B. Each optical transceiver 226A constitutes a first line port 131, and each optical transceiver 226B constitutes a second line port 132. The other configurations of the OLT 11A according to the fifth embodiment are the same as those of the OLT 11A according to the third embodiment.

[0203] FIG. 10 is a diagram illustrating an example of the overall configuration of a communication system according to the fifth embodiment.

[0204] In the fifth embodiment, the OLT 11A is connected to a plurality of first PON lines 13A1 and 13A2 (two in the figure) and a plurality of second PON lines 13B1 and 13B2 (two in the figure). Each of the first PON lines 13A1 and 13A2 is connected to two different optical transceivers 226A of the first line port 131 of the OLT 11A. Each of the second PON lines 13B1 and 13B2 is connected to two different optical transceivers 226B of the second line port 132 of the OLT 11A.

[0205] A communication system 10B according to the fifth embodiment includes two ONU-Cs 17A and 17B. Under normal circumstances, each of the two ONU-Cs 17A and 17B operates to distribute the load. If a failure occurs in either ONU-C 17A or 17B, the normal ONU-C is used to manage the entire first PON lines 13A1 and 13A2 and the second PON lines 13B1 and 13B2.

[0206] One first PON line 13A2 includes trunk optical fibers 151A, 151B and an optical splitter 14B1. The connection between the trunk optical fibers 151A, 151B and the optical splitter 14B1 is the same as the connection between the trunk optical fibers 15A, 15B and the optical splitter 14B shown in FIG. 1, so a description thereof will be omitted. A first end of a branch optical fiber 16B1 is connected to the optical splitter 14B1. A second end of the branch optical fiber 16B1 is connected to the ONU-C17A. A management device 18 is connected to the ONU-C17A via a communication cable.

[0207] One second PON line 13B2 includes trunk optical fibers 152A, 152B and an optical splitter 14B2. The connection between the trunk optical fibers 152A, 152B and the optical splitter 14B2 is similar to the connection between the trunk optical fibers 15A, 15B and the optical splitter 14B shown in FIG. 1, so a description thereof will be omitted. A first end of a branch optical fiber 16B2 is connected to the optical splitter 14B2. A second end of the branch optical fiber 16B2 is connected to the ONU-C17B. A management device 18 is connected to the ONU-C17B via a communication cable.

[0208] As described above, in the fifth embodiment, the connection paths between the OLT 11A and the management device 18 are made redundant. That is, the management device 18 is connected to the OLT 11A via a first connection path including the ONU-C17A, the branch optical fiber 16B1, the optical splitter 14B1, and the trunk optical fiber 151A, and is also connected to the OLT 11A via a second connection path including the ONU-C17B, the branch optical fiber 16B2, the optical splitter 14B2, and the trunk optical fiber 152A. The trunk optical fibers 151A and 151B according to the fifth embodiment are another example of a trunk communication line, and the trunk optical fibers 152A and 152B according to the fifth embodiment are yet another example of a trunk communication line. The branch optical fiber 16A1 according to the fifth embodiment is another example of a first branch communication line, and the branch optical fiber 16A2 according to the fifth embodiment is yet another example of a first branch communication line. The branch optical fiber 16B1 according to the fifth embodiment is another example of a second branch communication line, and the branch optical fiber 16B2 according to the fifth embodiment is yet another example of a second branch communication line.

[0209] The management device 18 can communicate with the OLT 11A using either a first communication mode in which the management device 18 communicates with the OLT 11A via the first PON line 13A2 via the ONU-C 17A, or a second communication mode in which the management device 18 communicates with the OLT 11A via the second PON line 13B2 via the ONU-C 17B. That is, the management device 18 can switch between the first communication mode and the second communication mode. For example, the management device 18 normally communicates with the OLT 11A using the first communication mode.

[0210] If a failure occurs in ONU-C17A or the first PON line 13A2, the management device 18 communicates with the OLT 11A using the second communication mode. This reduces the time during which communication is unavailable between the management device 18 and the OLT 11A. For example, if a failure occurs in ONU-C17A or the first PON line 13A2, the communication mode is switched from the first communication mode to the second communication mode.

[0211] In the fifth embodiment, the first PON lines 13A1 and 13A2 are connected to the first line port 131 of the line control module 22A, and the second PON lines 13B1 and 13B2 are connected to the second line port 132 of the line control module 22B. Therefore, if a failure occurs in the line control module 22A, the communication mode is switched from the first to the second communication mode. In this way, communication can be performed between the management device 18 and the OLT 11A using one of the line control modules 22A and 22B that is operating normally.

[0212] However, although ONU-C17A is connected to the first PON line 13A2 and ONU-C17B is connected to the second PON line 13B2, this is not limiting. For example, ONU-C17A and 17B may each be connected to two first PON lines 13A1 and 13A2. Even in this case, if a failure occurs in the first PON line 13A1 to which ONU-C17A is connected, communication can be performed between the management device 18 and the OLT 11A using the normal first PON lines 13A2 and ONU-C17B.

[0213] As another example, ONU-C17A and ONU-C17B may each be connected to a single first PON line 13A1. In this case, ONU-C17A may be operational (wake-up) and ONU-C17B may be inactive (sleep). For example, if a failure occurs in ONU-C17A, ONU-C17B may be woken up. Even in this case, if a failure occurs in ONU-C17A, communication can be performed between the management device 18 and the OLT 11A using the normal ONU-C17B.

[0214] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not the above-described embodiments, and includes meanings equivalent to the claims and all modifications within the scope thereof.

[0215] 10, 10A, 10B Communication system 11, 11A OLT (optical line terminal) 111 Search unit 112 First connection unit 113 First authentication unit 114 Second connection unit 115 Second authentication unit 116 Permission acceptance unit 117 Third connection unit 119 First reception unit 120 Execution unit 121 First transmission unit 122 Second reception unit 123 Second transmission unit 124 Third reception unit 125 Third transmission unit 131 First line port 132 Second line port 12, 12A, 12B ONU (optical line terminal) 13 PON line (communication line) 13A First PON line (first communication line) 13B Second PON line (second communication line) DESCRIPTION OF SYMBOLS 14A, 14B, 14A1, 14A2, 14B1, 14B2 Optical splitters 15A, 15B, 151, 151A, 151B, 152, 152A, 152B Trunk optical fibers 16A, 16B, 16A1, 16A2, 16B1, 16B2 Branch optical fibers 17 ONU-C (management home device) 17A ONU-C (first management home device) 17B ONU-C (second management home device) 171 Processor 172 Non-volatile memory 173 Volatile memory 174 PON processing circuit 175 Optical transceiver 176 Interface 177 UNI port 18 Management device 19 Line port 21, 21A Management module 211 Processor (third processor) 212 Non-volatile memory 213 Volatile memory 214 Interface 215 PHY 215A L2 switch (second Ethernet switch) 215A1 First port 215A2 Second port 215A3 Third port 215A4 Fourth port 216 Management control program 22 Line control module (communication module) 22A Line control module (first communication module) 22B Line control module (second communication module) 221 Processor 221A Processor (first processor) 221B Processor (second processor) 222, 222A, 222B Non-volatile memory 223, 223A,223B Volatile memory 224 PON processing circuit (communication processing circuit) 224A PON processing circuit (first communication processing circuit) 224B PON processing circuit (second communication processing circuit) 225, 225A, 225B PHY 226, 226A, 226B Optical transceiver (TRx) 228 Signal line 23 L2 switch 231 First port 232 Second port 233 Third port 23A L2 switch (first Ethernet switch) 231A First port 232A Second port 233A Third port 234A Fourth port 50 Upper network,

Claims

1. A communications system comprising: an optical line terminal; an optical network unit and a management optical line terminal connected to a communication line connected to the optical line terminal; and a management device communicating with the optical line terminal via the management optical line terminal, wherein the optical line terminal includes: a first receiving unit that receives, via the communication line, first control information from the management optical line terminal for controlling the communication line to which the optical line terminal is connected, the first control information being transmitted from the management device to the management optical line terminal; an executing unit that executes a first control process including control of the communication line to which the optical line terminal is connected based on the first control information received by the first receiving unit; and a first transmitting unit that transmits a result of execution of the first control process by the executing unit to the management optical line terminal to provide the result of the execution to the management device.

2. The communication system described in claim 1, wherein the communication lines include a trunk communication line, and a first branch communication line and a second branch communication line branching off from the trunk communication line, the home appliance is connected to the first branch communication line, and the management home appliance is connected to the second branch communication line.

3. The communication system according to claim 1, wherein the communication lines include a first communication line and a second communication line different from the first communication line, the first communication line is connected to the optical line terminal and the optical network unit, and the second communication line is connected to the optical line terminal and the management optical network unit.

4. The communication system according to any one of claims 1 to 3, wherein the optical line terminal includes a second receiving unit that receives, from the management optical line, second control information for controlling the optical line terminal, the second control information being transmitted from the management optical line to the management optical line terminal; a second transmitting unit that transmits the second control information received by the second receiving unit to the optical line terminal; a third receiving unit that receives, from the optical line terminal, a result of a second control process executed in the optical line terminal based on the second control information; and a third transmitting unit that transmits the result of the second control process to the management optical line terminal to provide the result of the second control process received by the third receiving unit to the management optical line.

5. A communication system according to any one of claims 1 to 4, wherein the management home device includes a first connection unit connected to the communication line and a second connection unit connected to the management device.

6. A communication system as described in any one of claims 1 to 5, wherein the communication line is an optical communication line, the management home device transmits a first frame which is an OAM frame defined by a communication standard used on the optical communication line and in which the first control information is stored, the first receiving unit receives the first frame in which the first control information is stored, and the first transmitting unit transmits a second frame which is the OAM frame in which a result of execution of the first control information is stored.

7. The communication system according to any one of claims 1 to 5, wherein the communication line is an optical communication line, the management home device transmits a first frame which is a user frame different from an OAM frame defined by a communication standard used on the optical communication line and in which the first control information is stored, the station side device includes a processor and a communication processing circuit which executes predetermined communication processing for communication between the station side device and the home device and the management home device, the communication processing circuit outputs the first frame received from the management home device to the processor, the processor outputs a second frame which is a user frame including a result of execution of the first control processing to the communication processing circuit, and the communication processing circuit transmits the second frame to the management home device.

8. The communications system according to any one of claims 1 to 7, wherein the optical line device includes: a searching unit that searches for the enabled management optical line device when the optical line device is not logically connected to either the optical line device or the management optical line device; a first connecting unit that establishes a connection between the optical line device and the management optical line device when the enabled management optical line device is found by the searching unit; a first authentication unit that authenticates the management optical line device when the connection between the optical line device and the management optical line device is established; a second connecting unit that establishes a connection between the optical line device and the management device when authentication by the first authentication unit is successful; and a second authentication unit that authenticates the management device when the connection between the optical line device and the management device is established.

9. The communication system according to any one of claims 1 to 8, comprising: a first management home device which is the management home device; and a second management home device connected to the communication line which is connected to the optical line device, wherein the management device is switchable from a first communication mode in which it communicates with the optical line device via the first management home device to a second communication mode in which it communicates with the optical line device via the second management home device.

10. The communication system described in claim 9, wherein the communication lines include a first communication line and a second communication line different from the first communication line, the first communication line is connected to the optical line terminal, the optical network terminal, and the second management optical network terminal, and the second communication line is connected to the optical line terminal and the first management optical network terminal.

11. The communication system according to claim 10, wherein the station device includes: a first communication module connected to the first communication line; and a second communication module connected to the second communication line.

12. An optical line terminal connected to a communication line to which an optical line device is connected, comprising: a first receiving unit that receives, from the management optical line, first control information for controlling the communication line to which the optical line device is connected, the first control information being transmitted to the management optical line device from a management device capable of communicating with the optical line device via a management optical line device connected to the management optical line; an executing unit that executes a first control process including control of the communication line to which the optical line device is connected based on the first control information received by the first receiving unit; and a first transmitting unit that transmits a result of execution of the first control process by the executing unit to the management optical line to provide the result of the execution to the management device.

13. A management method for managing an optical line device connected to a communication line to which an optical network device is connected, comprising: a step of transmitting, from a management device capable of communicating with the optical line device via a management optical line device connected to the communication line, to the management optical line device, first control information for controlling the communication line to which the optical network device is connected; a step of transmitting the first control information from the management optical line device to the optical line device via the communication line; a step of the optical line device executing a first control process including control of the communication line to which the optical network device is connected based on the first control information; a step of transmitting an execution result of the first control process from the optical line device to the management optical line device via the communication line; and a step of transmitting the execution result of the first control process from the management optical line device to the management optical line device.

14. A management control program for managing an optical line terminal connected to a home appliance, the management control program causing a computer to execute the following steps: receiving, via the communication line, from a management home appliance, first control information for controlling the communication line to which the home appliance is connected, the first control information being transmitted to the management home appliance from a management device capable of communicating with the optical line terminal via a management home appliance connected to the communication line; executing, based on the received first control information, a first control process including control of the communication line to which the home appliance is connected; and transmitting a result of the execution of the first control process to the management home appliance via the communication line in order to provide the result of the execution of the first control process to the management device.

Images