JP7544410B1 - PON system OLT, redundant communication device, PON system, bandwidth control method and program - Google Patents

Abstract

[Problem] To contribute to stable communication while maintaining efficient use of bandwidth in a PON system. [Solution] An OLT of a PON system comprising: a terminal line switching control unit that detects the amount of traffic between each of a plurality of accommodated ONUs, and outputs an alarm notification when the total traffic amount is greater than a predetermined first threshold; and a communication device authentication unit that outputs, when the alarm notification is output, a switching instruction to switch the connection destination from a predetermined line to a mobile line to a first communication device connected to a replaceable ONU via a predetermined line via a replaceable ONU that is at least one of the plurality of ONUs, the first communication device being a communication device that can be connected to the predetermined line and the mobile line, the plurality of ONUs being respectively connected to one end of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the OLT is connected, and the communication device connected to the replaceable ONU is the first communication device, and the first communication device is a communication device that can be connected to the predetermined line and the mobile line. [Selected Figure] Figure 1

Description

The present invention relates to an OLT for a PON system, a redundant communication device, a PON system, a bandwidth control method, and a program.

The widespread use of optical fiber lines has created a demand for services that support faster, larger-capacity communications. One technology that can achieve faster, larger-capacity communications is the Passive Optical Network (PON) system, which branches optical signals by branching optical fiber lines and then brings the branched optical signals to each subscriber's home (see, for example, Patent Document 1).

JP 2017-184006 A

The following analysis has been given by the inventor of the present invention.

The PON system is a type of optical access line that connects a communication station and an end user with an optical fiber cable, and is a system that realizes P2MP (Point to Multi Point) communication. In a PON system, the optical fiber cable transmission path is branched by an optical coupler installed along the way, and time division multiplexing (TDM) makes it possible for one device on the communication station side to accommodate multiple devices on the end user side.

Specifically, as shown in FIG. 11, the PON system 900 is composed of an OLT (Optical Line Terminal) 920, multiple ONUs (Optical Network Units) 930, an optical fiber cable 960, and an optical coupler 969. Each ONU 930 is connected to a communication device 940 via a wired cable 970.

Communication within the PON system 900 (PON communication) is performed by a time division multiplexing communication method (a communication method in which each ONU is assigned to a time slot) for both upstream and downstream. The time slots are dynamically allocated, for example, by referring to the buffer information of the ONU 930. This function is called the DBA (Dynamic Bandwidth Allocation) function. The DBA function realizes efficient upstream bandwidth without generating unused bandwidth by appropriately switching the allocated bandwidth depending on the traffic status of the upstream communication flowing through each ONU 930.

In this case, the OLT 920 and each connected ONU 930 must share the limited bandwidth. This diagram shows a configuration in which four ONUs 930 are connected as an example, but considering the economic advantages of optical fiber networks in the access area, it is expected that four or more ONUs 930 will be connected.

As the number of ONUs 930 connected to the OLT 920 increases, the bandwidth allocated to each ONU 930 decreases. Therefore, in the PON system 900, if a specific ONU 930 occupies the bandwidth, it may not be possible to ensure communication stability for other ONUs 930.

The present invention was made in consideration of the above circumstances, and aims to provide a technology that contributes to the stability of communication between the OLT and ONU of a PON system while maintaining efficient use of bandwidth.

According to a first aspect of the present disclosure,
An OLT (Optical Line Terminal) of a PON (Passive Optical Network) system,
a terminal line switching control unit that detects traffic volume between each of a plurality of optical network units (ONUs) accommodated in the network and outputs an alarm notification when a total traffic volume, which is a sum of the traffic volumes, is greater than a first threshold value;
An OLT of a PON system is provided which, when the alarm notification is output, outputs a switching instruction, which is an instruction to switch the connection destination from the specified line to a mobile line, to a first communication device connected to a replaceable ONU, which is at least one of the multiple ONUs, via the replaceable ONU, when the alarm notification is output.
The plurality of ONUs are each connected to one end of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the OLT is connected, and the other end of the optical fiber line branched by the optical coupler is connected,
The replaceable ONU is the ONU to which a communication device connected is the first communication device,
The first communication device is provided with an OLT, which is a communication device connectable to the specified line and the mobile line.

According to a second aspect of the present disclosure,
a WAN port section for connecting to an ONU (Optical Network Unit) via a predetermined line;
a mobile line WAN (Wide Area Network) module unit for connecting to the mobile line;
a connection control unit that switches a connection destination between the predetermined line and the mobile line,
The connection control unit is
When a connection is made to the ONU, a message is sent via the ONU to an OLT (Optical Line Terminal) which is a central office side device of the PON system that accommodates the ONU.
A redundant communication device is provided which switches the connection from the specified line to the mobile line when a switching instruction is received from the OLT via the ONU to which it is connected, the switching instruction being an instruction to switch the connection destination from the specified line to the mobile line.

According to a third aspect of the present disclosure,
An OLT (Optical Line Terminal) which is a central office device connected to one end of an optical fiber line;
and a plurality of ONUs (Optical Network Units) which are optical subscriber devices each connected to the other end of the optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line.
At least one of the plurality of ONUs, i.e., a replaceable ONU, is a communication device connected to the replaceable ONU via a predetermined line, the communication device being a first communication device connectable to the predetermined line and a mobile line;
The OLT includes:
a terminal line switching control unit that detects a traffic volume between each of the plurality of ONUs, and outputs an alarm notification when a total traffic volume between the plurality of ONUs is greater than a first threshold value;
There is provided a system including a communications equipment authentication unit that, when the alarm notification is output, outputs, via the replaceable ONU, an instruction to the first communications equipment to switch a connection destination from the specified line to the mobile line.

According to a fourth aspect of the present invention,
A bandwidth control method by an OLT (Optical Line Terminal) of a PON (Passive Optical Network) system, comprising:
a traffic detection step of detecting the amount of traffic between the OLT and each of a plurality of ONUs (Optical Network Units) that are optical subscriber devices accommodated in the OLT;
a determining step of outputting an alarm notification when a total traffic volume, which is the sum of the detected traffic volumes, is greater than a predetermined first threshold value;
A bandwidth control method is provided which includes a switching instruction step of, when the alarm notification is output, outputting a switching instruction, which is an instruction to switch the connection destination from a specified line to a mobile line, to a first communication device connected to the ONU via a replaceable ONU, which is at least one of the multiple ONUs.
The plurality of ONUs are each connected to one end of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the ONU is connected, and the other end of the optical fiber line branched by the optical coupler is connected,
The replaceable ONU is the ONU to which a communication device connected is the first communication device,
The first communication device is a communication device connectable to the specified line and the mobile line, and a bandwidth control method is provided.

According to a fifth aspect of the present invention,
The OLT (Optical Line Terminal) computer of the PON (Passive Optical Network) system
a traffic detection procedure for detecting the amount of traffic between each of a plurality of ONUs (Optical Network Units) that are optical subscriber devices accommodated in the OLT, the ONUs being connected to the other ends of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the OLT is connected at one end;
a determination step of outputting an alarm notification when a total traffic volume, which is the sum of the detected traffic volumes, is greater than a first threshold value;
When the alarm notification is output, a program is provided for executing a switching instruction procedure, which outputs a switching instruction, which is an instruction to switch the connection destination from the specified line to the mobile line, to a replaceable ONU, which is at least one ONU of the multiple ONUs and has a connected communication device that is a first communication device that can be connected to a specified line and a mobile line, via the ONU, to the first communication device.

According to a sixth aspect of the present invention,
A redundant communication device connected to an ONU (Optical Network Unit) of a PON (Passive Optical Network) system via a predetermined line,
a WAN port unit that is connected to the ONU via the predetermined line;
a transmission procedure for transmitting a message to an OLT (Optical Line Terminal) accommodating the ONU via the ONU when the ONU is connected to a computer of a redundant communication device including a mobile line WAN module unit connected to the mobile line;
When a switching instruction is received from the OLT via the connected ONU, which is an instruction to switch the connection destination from the specified line to the mobile line, a switching procedure for switching the connection destination from the specified line to the mobile line is provided, and a program for executing the switching procedure is provided.

These programs can be recorded on a computer-readable storage medium. The storage medium can be a non-transitory medium such as a semiconductor memory, a hard disk, a magnetic recording medium, or an optical recording medium. The present invention can also be embodied as a computer program product.

The present invention contributes to stable communications in a PON system while maintaining efficient bandwidth usage.

1A is an overall configuration diagram showing an example of the overall configuration of a PON system according to the present disclosure, and FIG. 1B is a functional block diagram showing an example of the functional configuration of an OLT according to the present disclosure. 1 is an overall configuration diagram showing an example of the overall configuration of a PON system according to the present disclosure. 1A to 1C are functional block diagrams showing examples of functional configurations of an OLT, an ONU, and a WAN redundant communication device according to the present disclosure, respectively. FIG. 2 is an explanatory diagram for explaining an example of an ONU management table according to the present disclosure. 13 is a flowchart of an example of a device recognition process according to the present disclosure. 13 is a flowchart of an example of a device recognition process according to the present disclosure. 1 is a flowchart of an example of a traffic monitoring process according to the present disclosure. FIG. 2 is a functional block diagram illustrating an example of a functional configuration of an OLT according to the present disclosure. 13 is a flowchart of an example of a process at the time of abnormal disconnection according to the present disclosure. FIG. 2 is a hardware configuration diagram showing an example of a hardware configuration of an OLT, an ONU, and a WAN redundant communication device according to the present disclosure. FIG. 1 is an overall configuration diagram of a conventional PON system.

Below, an overview of one embodiment of the present invention (hereinafter referred to as this embodiment) will be described with reference to the drawings. Note that the reference symbols in the drawings are given for convenience as an example to aid understanding, and are not intended to limit the present invention to the illustrated form. Furthermore, the connection lines between blocks in the drawings and the like referred to in the following description include both bidirectional and unidirectional lines. Unidirectional arrows are used to diagrammatically indicate the flow of the main signal (data), and do not exclude bidirectionality.

In addition, although there are ports and interfaces at the input/output connection points of each block in the diagram, they are not shown. In addition, in the following explanation, "A and/or B" is used to mean A or B, or A and B.

<<First embodiment>>
The outline of this embodiment will be described.

In this embodiment, in a PON (Passive Optical Network) system in which a WAN (Wide Area Network) redundant communication device (a communication device that can be connected to either a specified line (e.g., a wired line) or a mobile line) is connected to an ONU (Optical Network Unit), when a state occurs in which a specific ONU occupies a bandwidth, the WAN redundant communication device switches from wired communication using a specified line with an OLT (Optical Line Terminal) to wireless communication using a mobile line in order to ensure communication stability for ONUs to which the WAN redundant communication device is not connected.

The configuration of this embodiment that achieves this is explained below.

Figure 1(a) is an overall configuration diagram of a PON system 100 according to this embodiment. As shown in this figure, the PON system 100 constitutes an optical subscriber access network.

The PON system 100 of this embodiment includes an OLT device (hereinafter, OLT) 200, which is a communication device (station side device) on the operator side, and multiple ONU devices (hereinafter, ONUs) 301, 302, 303, and 304, which are communication devices (optical subscriber devices) on the subscriber side.

As an example, the PON system 100 is shown here to have four ONUs. However, the number of ONUs is not limited to this. Also, when there is no particular need to distinguish between them, they will be represented by ONU 300.

The OLT 200 is connected to one end of an optical fiber line (hereinafter, optical fiber) 600, which is an optical communication line. The other end of the optical fiber 600 is connected to the ONU 300. An optical coupler 690 for branching/gathering the optical fiber 600 is connected midway along the optical fiber 600. The optical coupler 690 branches one optical transmission path (optical fiber 600) into multiple paths. The other ends of the branched optical fibers 601, 602, 603, and 604 are connected to the ONUs 301, 302, 303, and 304, respectively. By installing the optical coupler 690 between the OLT 200 and the ONUs 300, which multiplexes and splits optical signals, multiple ONUs 300 are connected to one OLT 200.

For example, communication devices 401, 402, and 403 are connected to each ONU 301, 302, and 303 via wired cables 701, 702, and 703. In addition, for example, WAN redundant communication device (first communication device) 500 is connected to ONU (replaceable ONU) 304 via wired cable 704, and communication device 404 is further connected via wired cable 800.

Note that unless there is a need to distinguish between them, wired cables 701-704 will be represented by wired cable 700. Furthermore, communication devices 401-404 will be represented by communication device 400.

In the example shown in this figure, WAN redundant communication equipment 500 is connected to ONU 304, but it is sufficient that WAN redundant communication equipment 500 is connected to at least one of the multiple ONUs 300 in PON system 100. As described above, WAN redundant communication equipment 500 is a communication equipment that can be connected to a wired line and a mobile line. In other words, WAN redundant communication equipment 500 is an equipment that can switch the connection to the WAN line between, for example, a wired cable 700 and a mobile line.

In this embodiment, as described above, when a situation occurs in which a specific ONU 300 occupies the bandwidth, the connection of the WAN redundant communication device 500 is switched from a wired line to a mobile line.

The functional blocks of the OLT 200 of this embodiment that realize this are shown in FIG. 1(b). As shown in this figure, the OLT 200 of this embodiment includes a terminal line switching control unit 210, a communication device authentication unit 220, and a PON termination unit 230.

The terminal line switching control unit 210 detects the traffic volume between each of the multiple ONUs 300 accommodated by the OLT 200. It then determines whether the total traffic volume is greater than a predetermined threshold (first threshold). If it is determined that the total traffic volume is greater, it outputs an alarm notification to the communication device authentication unit 220.

When the communication device authentication unit 220 receives an alarm notification, it outputs a WAN line switching instruction via the replaceable ONU 304. The output destination is the WAN redundant communication device 500 connected to the replaceable ONU 304 via a wired cable 700. The WAN line switching instruction is an instruction to switch the connection from the wired line to a mobile line.

The PON termination unit 230 performs data communication with a network higher than the OLT 200, establishes links with the ONUs 300 accommodated in the OLT 200, identifies ONUs 300 that have been linked up/down, performs data communication with the ONUs 300, and controls the entire OLT 200.

As described above, in the PON system 100 of this embodiment, when the traffic volume exceeds a predetermined threshold, the WAN redundant communication device 500 is disconnected from the PON system 100, thereby ensuring communication stability for other ONUs to which the WAN redundant communication device 500 is not connected.

<<Second embodiment>>
Next, a second embodiment to which the present invention is applied will be described.

The overall configuration of the PON system 100a of this embodiment is shown in FIG. 2. The overall configuration of the PON system 100a is basically the same as the PON system 100 of the first embodiment shown in FIG. 1(a). However, instead of the OLT 200, an OLT 200a is provided.

In the PON system 100a of this embodiment, bandwidth is dynamically allocated using DBA (Dynamic Bandwidth Allocation). Therefore, as in the first embodiment, if a specific ONU 300 occupies the bandwidth, it becomes impossible to ensure communication stability for other ONUs 300.

In this embodiment, too, OLT 200a monitors the amount of traffic between ONUs 300, and if a state occurs in which a specific ONU 300 occupies the bandwidth, the connection of the WAN redundant communication device 500 is switched. Here, wired communication using a wired line with OLT 200a is switched to wireless communication using a mobile line with the WAN. This is to ensure communication stability for ONUs 300 that are not connected to WAN redundant communication device 500.

The PON system 100a of this embodiment that achieves this will be described in detail below. The following description of this embodiment will focus on the configuration that differs from the first embodiment.

The OLT 200a is a station side device that accommodates multiple ONUs 300. The OLT 200a accommodates multiple ONUs 300 using time division multiplexing (TDM) technology. The OLT 200a of this embodiment has a DBA function that dynamically allocates the bandwidth of upstream communication from the ONUs 300 to the OLT 200a according to the amount of traffic. The OLT 200a receives optical signals transmitted from the ONUs 300 and transfers them to a higher-level device or a higher-level network (e.g., the Internet, etc.). The OLT 200a also receives signals from the higher-level device or the higher-level network and transfers them to each ONU 300. The OLT 200a is responsible for controlling and monitoring the entire PON system 100a and the ONUs 300. OLT 200a connects to ONUs 301-304 via optical fiber 600, optical coupler 690, and optical fibers 601-604.

ONU300 is an optical subscriber device. It provides optical subscribers with a line for accessing networks such as the Internet. ONU300 receives optical signals sent from OLT200a and converts them into electrical signals. ONU300 then transfers the converted electrical signals to connected devices (e.g., communications devices, PCs, etc.). ONU300 also receives electrical signals sent from connected devices and converts them into optical signals. ONU300 then transfers the converted optical signals to OLT200a.

The communication device 400 is a router, a switching hub, a personal computer, etc. The WAN redundant communication device 500 is a device that allows the WAN connection to be selectively made between a wired connection via a PON system and a wireless connection via a mobile line such as LTE (Long Term Evolution). The WAN redundant communication device 500 is connected to the communication device 404 via a wired cable 800.

Figure 3(a) is a functional block diagram of OLT 200a. As shown in this figure, OLT 200a includes a terminal line switching control unit 210, a communication device authentication unit 220, and a PON termination unit 230. In addition, OLT 200a holds an ONU management table 250 that manages connected ONUs 300. In addition, it may hold a threshold value 260. As described below, threshold value 260 is used to determine whether or not PON communication traffic is congested.

Figure 3(b) is a functional block diagram of ONU 300. As shown in this figure, ONU 300 has a PON termination unit 310 and a UNI (User-Network Interface) termination unit 320.

Figure 3(c) is a functional block diagram of the WAN redundant communication device 500. As shown in this figure, the WAN redundant communication device 500 comprises a WAN port 510, a WAN connection control unit 520, and a LAN connection port unit 530. The WAN port 510 comprises a wired WAN port unit 511 and a mobile line WAN module unit 512.

The functions of each device are explained below.

[OLT]
The PON termination unit 230 basically has the same functions as the configuration of the same name in the first embodiment. That is, the PON termination unit 230 performs data communication with a network higher than the OLT 200a, establishment of links with the ONUs 300 accommodated in the OLT 200a, identification of individual information of the accommodated ONUs 300, data communication with the accommodated ONUs 300, control of the entire OLT 200a, etc.

The communication device authentication unit 220 basically has the same function as the configuration of the same name in the first embodiment. That is, the communication device authentication unit 220 manages individual information of the ONU 300 connected to the OLT 200a (accommodated by the OLT 200a). When an ONU 300 is newly connected to the OLT 200a, the individual information of the ONU 300 is acquired via the PON termination unit 230. The acquired individual information is then registered in the ONU management table 250. In addition, when the ONU 300 disconnects from the OLT 200a, the individual information of the ONU 300 may be acquired via the PON termination unit 230, and the corresponding data (record) in the ONU management table 250 may be deleted (erased). Note that, as described later, when the connection with the OLT 200a is disconnected in accordance with a switching instruction, the record itself may be left.

The communication device authentication unit 220 also manages the link state (link status) of the UNI termination unit 320 of the ONU 300. The communication device authentication unit 220 receives information indicating the link status of the UNI termination unit 320 (hereinafter simply referred to as link status) transmitted from the ONU 300. The received link status is registered in the ONU management table 250 in association with the transmitting ONU 300. The link status is information indicating whether or not any device is connected to the UNI termination unit 320. Hereinafter, a connected state is referred to as "link up" and a non-connected state is referred to as "link down."

In addition, when the device connected to the UNI termination unit 320 is a WAN redundant communication device 500, the communication device authentication unit 220 receives a message indicating that the device is a WAN redundant communication device (WAN redundant communication device notification message) via the PON termination unit 230. The WAN redundant communication device notification message is sent from the WAN connection control unit 520 of the WAN redundant communication device 500.

This allows the device connected to the UNI termination unit 320 of the ONU 300 to be ascertained as either the communication device 400 or the WAN redundant communication device 500. This information is also registered in the ONU management table 250 in association with the ONU 300. The communication device authentication unit 220 may also have a function of notifying the WAN connection control unit 520 of the WAN redundant communication device 500 that registration in the ONU management table 250 for management purposes has been completed.

In addition, when the communication device authentication unit 220 receives an excess alarm (described later) from the terminal line switching control unit 210, it issues a WAN line switching instruction to the WAN connection control unit 520 of the WAN redundant communication device 500 to switch the connection destination of the WAN line.

The terminal line switching control unit 210 monitors the traffic volume between each ONU 300 connected to the PON termination unit 230. Specifically, the terminal line switching control unit 210 acquires the upstream and downstream traffic volume for each ONU 300 connected to the PON termination unit 230, for example, for a predetermined period such as a unit time. The traffic volume is acquired independently for each ONU 300. These traffic volumes are detected and acquired, for example, using a traffic counter (counter for the number of transmitted and received frames, the number of transmitted and received bytes, etc.) that is normally provided in the OLT 200.

The terminal line switching control unit 210 also sets a threshold value 260. The threshold value 260 is used to determine the degree of bandwidth congestion in the PON section between each ONU 300 connected to the PON termination unit 230. The threshold value 260 includes a first threshold value and a second threshold value. The first threshold value is used to determine whether the total traffic volume of the PON section between the OLT 200a and the ONU 300 is exceeded during a specified period. The second threshold value is used to determine whether the traffic volume (specific traffic volume) of the PON section between the OLT 200a and the ONU 300 (304) to which the WAN redundant communication device 500 is connected to the UNI termination unit 320 is exceeded during a specified period. Information on the ONU 300 (304) to which the WAN redundant communication device 500 is connected to the UNI termination unit 320 is obtained from the communication device authentication unit 220.

The threshold 260 may be set in advance or during processing. For example, the first threshold may be determined depending on the communication rate of the PON section between the OLT 200 and the ONU 300. For example, in the case of 1GE (Gigabit Ethernet)-PON, the communication rate of the PON section is 1.25 Gbps. For example, the first threshold may be a value obtained by multiplying 80% of that (1.25 Gbps x 0.8 = 1 Gbps) by a predetermined period. The second threshold may be determined, for example, in relation to the total number of ONUs 300 accommodated in the PON system 100a. Specifically, it is calculated, for example, by the first threshold / the total number of accommodated ONUs 300. This is a value obtained by evenly allocating the first threshold to the ONUs 300 accommodated in the PON system 100a.

The terminal line switching control unit 210 performs an excess determination using the first threshold and the second threshold to determine whether the total traffic volume and the specific traffic volume are exceeded, respectively. If the excess determination determines that the traffic volume is exceeded, an alarm (excess alarm) is output. The excess alarm is output to the communication device authentication unit 220.

[ONU]
The PON terminal unit 310 is a terminal unit of the PON line, and receives control instructions from the OLT 200a and establishes communication with the OLT 200a. The PON terminal unit 310 also acquires the link status of the UNI terminal unit 320 and notifies the communication device authentication unit 220 of the OLT 200a. For example, the PON terminal unit 310 monitors the link status of the UNI terminal unit 320 at a predetermined time interval and detects that a new device has been connected (link up) or that a connection with a connected device has been cut off (link down).

The UNI termination unit 320 connects to the communication device 400 and/or the WAN redundant communication device 500 via the wired cable 700. It grasps the link status indicating that these devices are connected to the ONU 300 (link up) or that the connection between these devices and the ONU 300 has been disconnected (link down).

[WAN redundant communication equipment]
The wired WAN port unit 511 is connected to the UNI terminal unit 320 of the ONU 303 via a wired cable 700. The mobile line WAN module unit 512 is connected to a mobile line such as LTE (Long Term Evolution).

The WAN connection control unit 520 controls the entire WAN redundant communication device 500. For example, it notifies the communication device authentication unit 220 of the OLT 200a that it is the WAN redundant communication device 500. Specifically, it generates a WAN redundant device notification message and transmits it to the OLT 200a. Furthermore, when it receives a WAN line switching instruction from the communication device authentication unit 220 of the OLT 200a, it switches the connection destination of the WAN line between the wired line and the mobile line. It also controls the enabling/disabling of the functions of the wired WAN port unit 511 and the mobile line WAN module unit 512.

The LAN connection port unit 530 establishes a link with the communication device 400 via the wired cable 800 and communicates.

[ONU Management Table]
Here, a description will be given of information items stored in the ONU management table 250. Fig. 4 is a diagram showing an example of the ONU management table 250 of this embodiment. As shown in this figure, in the ONU management table 250, ONU individual information 251, link status 252, and connected device information 253 are registered for each ONU 300 connected to the OLT 200a.

The ONU individual information 251 is information that uniquely identifies each ONU 300 connected to the OLT 200a. As described above, the communication device authentication unit 220 obtains and registers the information from the connected ONU 300 via the PON termination unit 230. Note that each ONU 300 is set in advance with ONU individual information that uniquely identifies the device itself.

The link status 252 is information indicating whether or not the communication device 400 or the WAN redundant communication device 500 is connected to the UNI termination unit 320 of the ONU 310. If either device is connected, "link up" is registered, and if neither is connected, nothing is registered. Note that if neither is connected, "link down" may be registered. The link status 252 is obtained by the communication device authentication unit 220 from the connected ONU 300 via the PON termination unit 230.

The connected device information 253 is information about devices connected to the UNI termination unit 320 of the ONU 300. In the example of this embodiment, for example, the records of the ONUs 301 to 303 register the communication devices 401 to 403, respectively, and the record of the ONU 304 registers the WAN redundant communication device 500. Note that if the connected device is other than the WAN redundant communication device 500, nothing needs to be registered.

[Device identification process]
Next, a description will be given of the flow of processing in which the OLT 200a identifies a device connected to the UNI termination unit 320 of the ONU 300. First, a description will be given of the flow of the device identification processing in the case where the connected device is the WAN redundant communication device 500.

Figure 5 shows the process flow of the device identification process when the WAN redundant communication device 500 is connected in this embodiment. This process is started when the ONU 300 is connected to the OLT 200a.

In the PON system 100a, when an ONU 300 is connected to the OLT 200a, an ONU discovery process is executed to establish a link between the PON termination unit 230 of the OLT 200a and the PON termination unit 310 of the ONU 300 (step S1101).

When the ONU discovery process is completed normally, the individual information of the connected ONU 300 is notified to the communication device authentication unit 220 via the PON termination unit 230 of the OLT 200a. That is, the PON termination unit 310 of the ONU 300 transmits the individual information of its own device (ONU individual information) to the PON termination unit 230 of the OLT 200a (step S1102).

The communication device authentication unit 220 of the OLT 200a acquires individual information of the ONU 300 that has completed the ONU discovery process from the PON termination unit 230, and registers the information in the ONU individual information 251 of the ONU management table 250 (step S1103). Here, a new record is generated in the ONU management table 250 and registered.

In addition, when the ONU discovery process with OLT 200a is completed, ONU 300 enables UNI termination unit 320 (step S1104). This enables a link to be established with communication device 400 and/or WAN redundant communication device 500 connected to UNI termination unit 320.

When the link can be established, the ONU UNI discovery process is executed to establish a link between the UNI termination unit 320 and the destination device (here, the WAN redundant communication device 500) (step S1105).

The PON termination unit 310 of the ONU 300 monitors the link status of the UNI termination unit 320. When it detects a link-up (step S1106), it sends a link-up notification to the communication device authentication unit 220 of the OLT 200a (step S1107). Note that a link-up means that a link has been established with the communication device 400 or the WAN redundant communication device 500. The link-up notification is a notification that means that a link has been established.

The communication device authentication unit 220 of the OLT 200a, which has received the notification, links the ONU individual information 251 of the source ONU 300 in the ONU management table 250, and registers in the link status 252 that the UNI termination unit 320 has linked up (step S1108). In other words, it registers "link up" in the link status 252 of the record of the source ONU 300.

On the other hand, when a link is established with the ONU 300 by the above-mentioned ONU UNI discovery process, the WAN connection control unit 520 of the WAN redundant communication device 500 generates a WAN redundant communication device notification message (step S1109). The WAN redundant communication device notification message is a message notifying that it is the WAN redundant communication device 500. Then, the WAN redundant communication device notification message is transmitted to the communication device authentication unit 220 of the OLT 200a via the ONU 300 connected to the wired WAN port unit 511 (step S1110).

The communication device authentication unit 220 of the OLT 200a that received the message registers the WAN redundant communication device 500 in the ONU management table 250 (step S1111). Here, it links the ONU individual information 251 of the ONU 300 in the ONU management table 250, and registers information indicating that it is the WAN redundant communication device 500 in the connection device information 253. Then, it transmits a notification indicating that registration has been completed (registration completion notification) to the WAN connection control unit 520 of the WAN redundant communication device 500 (step S1112).

Next, we will explain the flow of the device identification process when the connected device is a communication device 400.

Figure 6 shows the process flow of the device identification process when a communication device 400 is connected. This process is started when an ONU 300 is connected to the OLT 200a.

The link establishment process between OLT 200a and ONU 300 (steps S1101 to S1103), and the link establishment process between ONU 300 and communication device 400 (steps S1104 to S1108) are the same as in the case of WAN redundant communication device 500 described above.

If the connected device is communication device 400, communication device 400 does not send any message to OLT 200a even if a connection is established with ONU 300.

Therefore, if no message is received for a predetermined period of time after step S1108, the communications device authentication unit 220 of OLT 200a recognizes that the connected device is communications device 400. Then, it links the ONU individual information 251 of the ONU 300 in the ONU management table 250, and registers information indicating that it is communications device 400 in the connected device information 253. Note that step S1108 is a process of receiving a notification that the UNI termination unit 320 has linked up, and registering it in the ONU management table 250, as described above.

Here, the communication device authentication unit 220 determines whether a predetermined period of time has elapsed (step S1121). Then, if the predetermined period of time has elapsed without receiving any message, the communication device authentication unit 220 of OLT 200a registers communication device 400 in the ONU management table 250 (step S1122). Here, information indicating that it is communication device 400 is registered in the connected device information 253 of the record in which "link up" was registered in the link status 252 in step S1108.

The "predetermined period" that the communication device authentication unit 220 uses for the determination is set in advance.

If no information is received for a specified period of time, the communication device authentication unit 220 does not need to register any information in the connected device information 253 of the ONU management table 250. In this case, for a record in which link up is registered in the link status 252 and nothing is registered in the connected device information 253, the OLT 200a interprets the connected device as the communication device 400 (not the WAN redundant communication device 500).

The OLT 200a executes this device identification process each time an ONU 300 is connected. This allows the OLT 200a to identify whether the device connected to the UNI termination unit 320 of the connected ONU 300 is a communication device 400 or a WAN redundant communication device 500.

[Traffic monitoring process]
Next, a flow of a traffic monitoring process for monitoring traffic on a PON line will be described. The OLT 200a of this embodiment monitors traffic on a PON line in the PON system 100a. When the traffic volume on the PON line becomes tight (when a state occurs in which a specific ONU 300 has exclusive use of a band), in order to stabilize communication, the WAN redundant communication device 500 switches from wired communication of the OLT 200a to communication using a mobile line.

Figure 7 shows the processing flow of the traffic monitoring process. This process is started, for example, when multiple ONUs 300 are connected to OLT 200a and at least one of them is an ONU 300 to which a WAN redundant communication device 500 is connected (hereinafter referred to as a replaceable ONU 300). Specifically, the process is started when multiple records are registered in ONU management table 250 and at least one of the records has a link status 252 of "link up" and a connection device information 253 of "WAN redundant communication device."

Here, the first threshold is assumed to be preset.

The terminal line switching control unit 210 of the OLT 200a identifies the ONUs 300 (monitored ONUs) to be monitored for traffic, and calculates the second threshold (step S1201). Here, the terminal line switching control unit 210 acquires the ONU individual information 251 of the records in which the link status 252 is linked up from the ONU management table 250. The ONUs 300 from which the ONU individual information 251 has been acquired are the ONUs to be monitored. Furthermore, the second threshold is calculated, for example, by the above method, using the number of ONUs 300 from which the ONU individual information 251 has been acquired.

The terminal line switching control unit 210 further identifies the ONU individual information 251 of the ONU (replaceable ONU) 300 whose connected device information 253 is the WAN redundant communication device 500 (step S1202). The replaceable ONU 300 is the object to be determined as to whether or not to output an alarm notification. In the example of this embodiment, it is ONU 304. The replaceable ONU 300 is included in the ONUs to be monitored.

The terminal line switching control unit 210 starts monitoring the traffic between each monitored ONU (step S1203). Then, it performs an excess determination. Here, the terminal line switching control unit 210 detects the traffic volume between each monitored ONU 300 at a predetermined time interval, and calculates the total traffic volume by adding them up (step S1204). Then, it determines whether the calculated total traffic volume exceeds the first threshold (total traffic volume > first threshold) (step S1205). If it does not exceed the first threshold, it returns to step S1204 and continues processing.

On the other hand, if the total traffic volume exceeds the first threshold, the terminal line switching control unit 210 determines whether the specific traffic volume exceeds the second threshold (specific traffic volume > second threshold) (step S1206). Note that the specific traffic volume is the traffic volume between the replaceable ONU 300 (ONU 304) identified in step S1202, as described above. If it has not been exceeded, the process returns to step S1204 and continues.

On the other hand, if the specific traffic volume exceeds the second threshold, the terminal line switching control unit 210 determines that the traffic volume is exceeded and notifies the communication device authentication unit 220 of an alarm indicating the exceedance (excess alarm) (step S1207).

The communication device authentication unit 220, which has received the excess alarm notification, generates and transmits a WAN line switching instruction, which is an instruction to switch the WAN connection, to the WAN redundant communication device 500 connected to the replaceable ONU 300 (ONU 304) (step S1208). Here, the communication device authentication unit 220 transmits the WAN line switching instruction to the WAN connection control unit 520 of the WAN redundant communication device 500 via ONU 304.

When the WAN connection control unit 520 receives the WAN line switching instruction, it first responds (replies) to the communication device authentication unit 220 of the OLT 200a that it has received the WAN line switching instruction (step S1209). After that, the mobile line WAN module unit 512 switches the WAN line connection from the wired WAN port unit 511 (step S1210). At this time, the WAN connection control unit 520 disables the function of the wired WAN port unit 511 and disconnects the link with the UNI termination unit 320 of the ONU 304 (step S1211).

When the PON termination unit 310 detects a link down (step S1212), it transmits a link down notification to the communication device authentication unit 220 of the OLT 200a (step S1213). The PON termination unit 310 monitors the link status of the UNI termination unit 320 of the ONU 304. A link down is when the link is disconnected at the UNI termination unit 320.

The communication device authentication unit 220 that received the link down notification updates the ONU management table 250 (step S1214). Here, the link status 252 registration of the record of the ONU 300 that sent the notification (here, ONU 304) is changed to "link down" and the data of the connected device information 253 is erased. Note that the ONU individual information 251 may be maintained as it is, i.e., the record itself may be left as it is.

As described above, in the WAN redundant communication device 500, the WAN line connection is switched from the wired WAN port unit 511 to the mobile line WAN module unit 512. As a result, the replaceable ONU 300 (in this embodiment, ONU 304) to which this WAN redundant communication device 500 is connected no longer uses the PON communication line, and is removed from the PON system 100a.

As described above, according to this embodiment, line congestion in the PON section is detected by the control of the OLT 200a. Then, if the PON communication line between the OLT 200a and the ONU 300 accommodated in the OLT 200a is congested, the replaceable ONU 300 is removed from the PON system 100a. This alleviates communication congestion within the PON system 100a. In other words, since the WAN redundant communication device 500 whose traffic volume exceeds the threshold is disconnected from the PON system 100a, it becomes possible to ensure communication stability for other ONUs 300 to which the WAN redundant communication device 500 is not connected.

If the WAN redundant communication device 500 is connected to a replaceable ONU 300, communication can be continued through the mobile line, so when the entire PON system 100a is taken into consideration, the communication bandwidth of both the mobile line and the PON line can be used efficiently. In other words, it becomes possible to efficiently use the communication bandwidth of the entire PON system 100a.

Furthermore, according to this embodiment, a two-stage judgment is made between the total traffic volume and the specific traffic volume. That is, the traffic volume between the OLT 200a and the replaceable ONU 300 (ONU 304) is also judged to be in excess, and if it is in excess, the replaceable ONU 300 is removed from the PON system 100a. In general, the user of the WAN redundant communication device 500 connected to the ONU 300 removed from the PON system 100a must pay communication fees for LTE, etc., and these fees may be on a pay-per-use basis. However, by performing control as in this embodiment, unnecessary switching control is prevented, and unnecessary financial burdens on the user of the WAN redundant communication device 500 can be reduced.

Therefore, according to this embodiment, communication throughout the PON system 100a can be stabilized, and the communication bandwidth can be utilized efficiently.

<<Third embodiment>>
Next, a third embodiment to which the present invention is applied will be described.

The WAN redundant communication device 500 has a WAN redundant configuration to improve the stability and robustness of communication. Here, we assume that after the traffic monitoring process in FIG. 7, there is a problem with the mobile line to which the WAN redundant communication device 500 is connected, and the connection via the mobile line is cut off.

When the mobile line is abnormally disconnected, the WAN connection control unit 520 of the WAN redundant communication device 500 activates the wired WAN port unit 511. As a result, the PON termination unit 310 of the replaceable ONU 300 (ONU 304) detects that the link status of the UNI termination unit 320 has changed to link up, and notifies the OLT 200a.

However, when the PON line is congested, that is, when the total traffic volume exceeds the first threshold and the specific traffic volume exceeds the second threshold, it is possible that a WAN line switching instruction will be received again from OLT 200a within a short period of time. As described above, the WAN line switching instruction is an instruction (notification) to switch the WAN connection destination of WAN redundant communication device 500 to the mobile line.

If the mobile line has not been restored at this point, the WAN redundant communication device 500 will not be able to connect to the mobile line, and the WAN connection control unit 520 may get caught in a WAN line switching loop.

This embodiment is capable of dealing with such situations. In other words, this embodiment is capable of preventing the WAN redundant communication device 500 from falling into a switching loop.

The overall configuration of the PON system of this embodiment is basically the same as the PON system 100a of the second embodiment. However, in this embodiment, OLT 200b is provided instead of OLT 200a. Also, the function of the WAN connection control unit 520 of the WAN redundant communication device 500 is different. Below, this embodiment will be described with a focus on the differences from the second embodiment.

In addition to the functions of the second embodiment, the WAN connection control unit 520 of this embodiment has the functions of detecting that the link with the mobile line WAN module unit 512 has been abnormally disconnected, and of sending a notification (abnormal disconnection notification) to the communication device authentication unit 220 of the OLT 200b described later, indicating that the connection of the mobile line WAN module unit 512 has been abnormally disconnected.

Furthermore, the OLT 200b of this embodiment includes a timer 270 that counts time, in addition to the components of the OLT 200a of the second embodiment. Figure 8 shows a functional block diagram of the OLT 200b of this embodiment. Note that components with the same names as those of the OLT 200a have at least the same functions as the components with the same names.

Furthermore, when the communication device authentication unit 220 receives an abnormal disconnection notification sent from the WAN redundant communication device 500, it masks the connection device information 253 of the record in the ONU management table 250 corresponding to the ONU 300 that sent the abnormal disconnection notification. The masking period (masking period) is determined in advance. After the masking period has elapsed, the communication device authentication unit 220 removes the mask from the connection device information 253.

The mask period is measured by the timer 270. That is, when the communication device authentication unit 220 receives an abnormal disconnection notification, it causes the timer 270 to start measuring time.

[Abnormal disconnection processing]
FIG. 9 shows a process flow for abnormal disconnection processing when the mobile line WAN module unit 512 of the WAN redundant communications device 500 is abnormally disconnected.

The WAN connection control unit 520 of the WAN redundant communication device 500 detects that the link of the mobile line WAN module unit 512 has been abnormally disconnected (step S2101).

The WAN connection control unit 520 enables the function of the wired WAN port unit 511 (step S2102). As a result, the WAN redundant communication device 500 is connected to the ONU 300 via the wired WAN port unit 511. In other words, it is connected to the OLT 200b via a PON line.

When the function of the wired WAN port unit 511 of the WAN redundant communication device 500 is enabled, the UNI termination unit 320 of the ONU 300 connected by the wired cable 700 establishes a link with the WAN redundant communication device 500 (step S2103). Here, as in the second embodiment, the PON termination unit 310 executes the ONU UNI discovery process and establishes a link between the UNI termination unit 320 and the WAN redundant communication device 500.

The PON termination unit 310 monitors the link status of the UNI termination unit 320. Then, when the ONU 300 detects that it has linked up with the WAN redundant communication device 500 (step S2104), it transmits a link-up notification to the communication device authentication unit 220 of the OLT 200b to notify the ONU of the link-up (step S2105).

The communication device authentication unit 220 of OLT 200b that received the link-up notification registers the link-up notification in the ONU management table 250 (step S2106). Here, the fact that the UNI termination unit 320 of ONU 300 has linked up is registered in association with the individual information of the sending ONU 300 (here, ONU 304).

At this time, the ONU 300 includes its own device's individual information in the link-up notification and sends it. If there is a record in the ONU management table 250 that has the individual information as ONU individual information 251, the communication device authentication unit 220 registers the individual information in the link status 252 of the record. On the other hand, if there is no such record, a new record is added and registered.

When the WAN redundant communication device 500 links up with the ONU 300, the WAN connection control unit 520 of the WAN redundant communication device 500 generates a WAN redundant device notification message (step S2107). The link up is performed between the wired WAN port unit 511 of the WAN redundant communication device 500 and the UNI termination unit 320 of the ONU 300 connected by the wired cable 700. The WAN redundant device notification message is a message for notifying the communication device authentication unit 220 of the OLT 200b that it is the WAN redundant communication device 500. At this time, the WAN redundant device notification message includes a notification (abnormal disconnection notification) that means that the mobile line WAN module unit 512 has been abnormally disconnected. Then, the WAN connection control unit 520 transmits the message to the communication device authentication unit 220 of the OLT 200b via the ONU 300 connected to the wired WAN port unit 511 (step S2108).

The communication device authentication unit 220 of the OLT 200b that receives the WAN redundant device notification message including the abnormal disconnection notification registers it in the ONU management table 250 (step S2109). Here, it links it to the ONU individual information 251 of the ONU 300 in question, and registers information indicating that it is a WAN redundant communication device 500 in the connection device information 253.

The communication device authentication unit 220 of the OLT 200b determines whether or not a notification that the mobile line has been abnormally disconnected has been received from the WAN redundant communication device 500 (step S2110). That is, it determines whether or not an abnormal disconnection notification is included in the WAN redundant device notification message.

When an abnormal disconnection notification is received from the WAN redundant communication device 500, the communication device authentication unit 220 masks the connected device information 253 of the corresponding ONU 300 in the ONU management table 250 (step S2111). Here, it masks the fact that the communication device connected to the UNI termination unit 320 of the corresponding ONU 300 is the WAN redundant communication device 500.

Then, the communication device authentication unit 220 starts counting the mask period using the timer 270 (step S2112). The mask period is set in advance.

When the masking period has elapsed (step S2113), the communication device authentication unit 220 removes the masking from the ONU management table 250 (step S2114). After removing the masking, the communication device authentication unit 220 transmits a registration completion notification to the WAN connection control unit 520 of the WAN redundant communication device 500 (step S2115).

If no abnormal disconnection notification has been received from the WAN redundant communication device 500 in step S2110, the process proceeds to step S2115. Then, the communication device authentication unit 220 of the OLT 200b sends a registration completion notification to the WAN connection control unit 520 of the WAN redundant communication device 500.

During this process, OLT 200b continues to monitor the traffic volume. Even if the communication device authentication unit 220 receives an excess alarm notification from the terminal line switching control unit 210, if the connection device information 253 is masked, the communication device authentication unit 220 does not send a WAN line switching instruction to the WAN redundant communication device 500. The excess alarm notification is sent from the terminal line switching control unit 210 when the total traffic volume exceeds the first threshold.

As described above, according to this embodiment, the same effects as those of the above embodiments can be obtained. Furthermore, according to this embodiment, when the mobile line WAN module unit 512 of the WAN redundant communication device 500 is abnormally disconnected, the WAN connection control unit 520 can be prevented from falling into a WAN line switching loop by the control of the OLT 200b.

<Modification 1>
In the above embodiments, when the total traffic volume exceeds the first threshold and the specific traffic volume exceeds the second threshold in the PON system 100 (100a, hereinafter represented by 100, and the same applies to the others), the ONU 300 to which the WAN redundant communication device 500 is connected is disconnected from the PON system 100. However, the present invention is not limited to this method.

For example, if the total traffic volume exceeds a first threshold, the ONU 300 to which the WAN redundant communication device 500 is connected may be disconnected from the PON system 100 regardless of the specific traffic volume.

In this modified example, the number of judgments is reduced compared to the above embodiment, making it possible to achieve the desired effect with simpler processing.

<Modification 2>
In addition, in the above-described embodiments and modifications, a case has been described in which the WAN redundant communication device 500 is connected to one ONU 300 (hereinafter, referred to as a replaceable ONU 300). However, a plurality of replaceable ONUs 300 may be connected to the OLT 200 (200a, 200b).

In this case, for example, in step S1206 above, all replaceable ONUs 300 whose specific traffic volume exceeds the second threshold value may be configured to be disconnected from the PON system 100.

In addition, in step S1206, among the replaceable ONUs 300 whose specific traffic volume exceeds the second threshold, only the replaceable ONU 300 with the largest traffic volume may be disconnected from the PON system 100. In this case, the second threshold is recalculated and updated each time one replaceable ONU 300 is disconnected (for example, after the traffic monitoring process returns Yes in step S1206). In other words, the second threshold is calculated using the latest number of ONUs 300 (including replaceable ONUs 300) in the PON system 100. Subsequent processing is then performed using the updated second threshold.

Furthermore, the second threshold may not be used, and in step S1205, if the total traffic volume exceeds the first threshold, the replaceable ONU 300 with the largest traffic volume among the replaceable ONUs 300 may be configured to be disconnected from the PON system 100.

Furthermore, in the above traffic monitoring process, after step S1205 is determined to be Yes, the terminal line switching control unit 210 may refer to the ONU management table 250 to determine whether or not there is a replaceable ONU 300 that can be disconnected. If there is not, the process from S1206 onwards is not performed.

<Modification 3>
In the above embodiments and modifications, the first threshold, the second threshold, and the third threshold are described as being preset, but are not limited thereto. For example, at the beginning of the traffic monitoring process, the terminal line switching control unit 210 may be configured to calculate the thresholds according to the number of connected ONUs 300.

<Modification 4>
In addition, in each of the above embodiments and modifications, the traffic monitoring process is started when a plurality of ONUs 300 are registered and at least one of them becomes a replaceable ONU 300, but this is not limiting. For example, the traffic monitoring process may be started in response to an instruction from a user and ended according to an instruction from the user.

<Modification 5>
In the above embodiments and modifications, the OLT 200 collects the status of the ONU 300 by receiving a WAN redundant device notification message or by waiting for a predetermined period of time after receiving the link-up notification. However, the method of collecting the status of the ONU 300 is not limited to this. For example, the OLT 200 may inquire the ONU 300 that has received the ONU individual information at a predetermined time interval and collect the link status.

In addition, traffic volume may be detected on the ONU 300 side, and the OLT 200 may collect the traffic volume from each ONU 300 at a predetermined time interval.

[Hardware configuration]
The above-mentioned OLT 200, ONU 300, and WAN redundant communication device 500 may be realized by, for example, a general-purpose information processing device.

As shown in FIG. 10, for example, a general-purpose information processing device includes a CPU (Central Processing Unit) 191, a main storage device (memory) 192, an auxiliary storage device 193, a communication I/F 194, and an expansion I/F 195, which are interconnected by an internal bus.

The CPU 191, for example, loads a program stored in the auxiliary storage device 193 into the main storage device 192 and executes the program to realize the above-mentioned functions and to centrally control the entire device. Note that one or more processors such as an MPU (Micro Processing Unit) may be used instead of the CPU 191.

The main memory 192 is a memory such as a RAM (Random Access Memory). The main memory 192 is a work area used by the CPU 191 when processing programs executed by the device.

The auxiliary storage device 193 is, for example, a ROM (Read Only Memory), a HDD (Hard Disk Drive), or a SSD (Solid State Drive). The auxiliary storage device 193 stores various programs executed by the device. The auxiliary storage device 193 may include storage media such as a flexible disk, a hard disk, an optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, or a DVD.

The programs stored in the auxiliary storage device 193 can be provided as program products recorded on a non-transitory computer-readable storage medium. The auxiliary storage device 193 can be used to store various programs recorded on the non-transitory computer-readable storage medium for the medium to long term.

The communication I/F 194 is an interface for inputting and outputting signals and data via wired or wireless connections. In this embodiment, an optical fiber 600, a wired cable 700, a mobile line, etc. are connected. Each device transmits and receives information (data) required for processing between other devices via the communication I/F 194.

The expansion I/F 195 is an interface for connecting a display device, an input device, etc. The display device is, for example, an LCD monitor. The input device is, for example, a device that accepts user operations such as a keyboard or a mouse.

The above-mentioned functions of each device are realized by the CPU 191 loading the programs stored in the auxiliary storage device 193 into the main storage device 192 and executing them.

The ONU management table 250 is constructed, for example, in the auxiliary storage device 193. The threshold value 260 is also stored in the auxiliary storage device 193.

The hardware configuration of each device is not limited to this. Furthermore, each function (server) of each device may be implemented, for example, in an integrated circuit (IC) dedicated to each process, an application specific integrated circuit (ASIC), a system on chip (SOC), a field programmable gate array (FPGA), etc.

In addition, the programs that realize the above-mentioned functions of each device can be recorded on a computer-readable storage medium. The storage medium can be a non-transient medium such as a semiconductor memory, a hard disk, a magnetic recording medium, or an optical recording medium. The present invention can also be embodied as a computer program product.

In the process flow used in the above explanation, multiple steps (processes) are described in order, but the order in which each step is performed is not limited to the order described. For example, the order of the steps shown in the figure can be changed to the extent that does not interfere with the content, such as performing each process in parallel.

Although the above describes various embodiments and variations of the present invention, the present invention is not limited to the above-described embodiments, and various modifications that can be understood by those skilled in the art can be made. Furthermore, each embodiment and variation can be combined with other embodiments as appropriate. Furthermore, for example, the network configuration and the configuration of each element shown in each drawing are examples to aid in understanding the present invention, and are not limited to the configurations shown in these drawings.

Finally, preferred embodiments of the present invention will be summarized as follows: A part or all of the above-described embodiments can be described as follows, but are not limited to the following.
(Appendix 1)
An OLT (Optical Line Terminal) of a PON (Passive Optical Network) system,
a terminal line switching control unit that detects traffic volume between each of a plurality of optical network units (ONUs) accommodated in the network and outputs an alarm notification when a total traffic volume, which is a sum of the traffic volumes, is greater than a first threshold value;
a communication device authentication unit that outputs, when the alarm notification is output, a switching instruction, which is an instruction to switch a connection destination from the predetermined line to a mobile line, to a first communication device connected to a replaceable ONU that is at least one ONU of the plurality of ONUs via the replaceable ONU;
The plurality of ONUs are each connected to one end of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the OLT is connected, and the other end of the optical fiber line branched by the optical coupler is connected,
The replaceable ONU is the ONU to which a communication device connected is the first communication device,
The first communication device is an OLT of a PON system, which is a communication device connectable to the specified line and the mobile line.
(Appendix 2)
In the OLT of the PON system described in Supplementary Note 1,
It is desirable that, when the total traffic volume is greater than the first threshold value, the terminal line switching control unit further detects a specific traffic volume, which is the traffic volume between the replaceable ONU, and outputs the alarm notification only when the specific traffic volume is greater than a predetermined second threshold value.
(Appendix 3)
In the OLT of the PON system according to claim 1 or 2,
An ONU management table for managing the ONUs accommodated therein is further provided,
The communication device authentication unit
receiving a message from the first communication device via the replaceable ONU when the first communication device is connected to the replaceable ONU;
When the message is received, the connected device information is registered in the ONU management table in association with the information for identifying the replaceable ONU;
It is preferable that the connected device information is information indicating that the device connected to the replaceable ONU is the first communication device.
(Appendix 4)
In the OLT of the PON system described in Supplementary Note 3,
The communication device authentication unit
When receiving an abnormal disconnection notification from the first communication device via the replaceable ONU, register information indicating that the device connected to the replaceable ONU is the first communication device in the connected device information of the ONU management table in association with the replaceable ONU, and
Masking the connected device information in the ONU management table for a predetermined masking period;
the abnormal disconnection notification is a notification transmitted from the first communication device after switching a connection to the mobile line, and indicates that the mobile line has been abnormally disconnected;
When the connected device information is masked in the ONU management table, it is preferable that the communication device authentication unit does not output the switching instruction to the first communication device even if the alarm notification is output.
(Appendix 5)
a WAN (Wide Area Network) port section for connecting to an ONU (Optical Network Unit) via a predetermined line;
a mobile line WAN module unit for connecting to a mobile line;
a connection control unit that switches a connection destination between the predetermined line and the mobile line,
The connection control unit is
When a connection is made to the ONU, a message is sent via the ONU to an OLT (Optical Line Terminal) which is a central office side device of the PON system that accommodates the ONU.
A redundant communication device that switches a connection from the specified line to the mobile line when a switching instruction is received from the OLT via the ONU to which it is connected, the switching instruction being an instruction to switch a connection destination from the specified line to the mobile line.
(Appendix 6)
In the redundant communication device according to claim 5,
The connection control unit is
If the connection to the mobile line is disconnected due to an abnormality in the mobile line, it is desirable to switch the connection to the specified line, connect to the ONU, and send a notification to the OLT via the ONU indicating that the mobile line has been abnormally disconnected.
(Appendix 7)
An OLT (Optical Line Terminal) which is a central office device connected to one end of an optical fiber line;
and a plurality of ONUs (Optical Network Units) which are optical subscriber devices each connected to the other end of the optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line,
At least one of the plurality of ONUs, i.e., a replaceable ONU, is a communication device connected to the replaceable ONU via a predetermined line, the communication device being a first communication device connectable to the predetermined line and a mobile line;
The OLT includes:
a terminal line switching control unit that detects a traffic volume between each of the plurality of ONUs, and outputs an alarm notification when a total traffic volume between the plurality of ONUs is greater than a first threshold value;
a communication device authentication unit that outputs, when the alarm notification is output, an instruction to the first communication device via the replaceable ONU to switch a connection destination from the specified line to the mobile line.
(Appendix 8)
A bandwidth control method by an OLT (Optical Line Terminal) of a PON (Passive Optical Network) system, comprising:
a traffic detection step of detecting the amount of traffic between the OLT and each of a plurality of ONUs (Optical Network Units) that are optical subscriber devices accommodated in the OLT;
a determining step of outputting an alarm notification when a total traffic volume, which is the sum of the detected traffic volumes, is greater than a predetermined first threshold value;
a switching instruction step of outputting, when the alarm notification is output, a switching instruction which is an instruction to switch a connection destination from a predetermined line to a mobile line to a first communication device connected to at least one of the plurality of ONUs via a replaceable ONU which is an ONU of the plurality of ONUs;
The plurality of ONUs are each connected to one end of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the ONU is connected, and the other end of the optical fiber line branched by the optical coupler is connected,
The replaceable ONU is the ONU to which a communication device connected is the first communication device,
A bandwidth control method, wherein the first communication device is a communication device that can be connected to the specified line and the mobile line.
(Appendix 9)
The OLT (Optical Line Terminal) computer of the PON (Passive Optical Network) system
a traffic detection procedure for detecting the amount of traffic between each of a plurality of ONUs (Optical Network Units) that are optical subscriber devices accommodated in the OLT, the ONUs being connected to the other ends of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the OLT is connected at one end;
a determination step of outputting an alarm notification when a total traffic volume, which is the sum of the detected traffic volumes, is greater than a first threshold value;
A program for executing, when the alarm notification is output, a switching instruction procedure for outputting, via an ONU to a replaceable ONU, which is at least one ONU of the multiple ONUs and has a connected communication device that is a first communication device that can be connected to a specified line and a mobile line, a switching instruction that is an instruction to the first communication device to switch the connection destination from the specified line to the mobile line.
(Appendix 10)
A redundant communication device connected to an ONU (Optical Network Unit) of a PON (Passive Optical Network) system via a predetermined line,
a WAN (Wide Area Network) port unit that connects to the ONU via the predetermined line;
A computer of a redundant communication device including a mobile line WAN module unit for connecting to a mobile line,
a transmission procedure for transmitting a message via the ONU to an OLT (Optical Line Terminal) that accommodates the ONU when the ONU is connected to the OLT;
A program for executing a switching procedure for switching the connection destination from the specified line to the mobile line when a switching instruction is received from the OLT via the connected ONU, which is an instruction to switch the connection destination from the specified line to the mobile line.
The form of Supplementary Note 7 can be developed into the form of Supplementary Note 2-4 and/or Supplementary Note 6, similarly to Supplementary Note 1 and/or Supplementary Note 5. The forms of Supplementary Note 8 and Supplementary Note 9 can be developed into the form of Supplementary Note 2-4, similarly to Supplementary Note 1. The form of Supplementary Note 10 can be developed into the form of Supplementary Note 6, similarly to Supplementary Note 5.

The disclosure of Patent Document 1 is incorporated herein by reference. Within the framework of the entire disclosure of the present invention (including the scope of claims), and further based on the basic technical ideas, modifications and adjustments of the embodiments and variants are possible. Furthermore, within the framework of the disclosure of the present invention, various combinations and selections of the various disclosed elements (including each element of each claim, each element of each embodiment or variant, each element of each drawing, etc.) are possible. In other words, the present invention naturally includes various modifications and corrections that a person skilled in the art would be able to make in accordance with the entire disclosure, including the scope of claims, and the technical ideas. In particular, with regard to the numerical ranges described in this document, any numerical value or subrange included within the range should be construed as being specifically described, even if not otherwise specified.

100: PON system, 100a: PON system, 191: CPU, 192: main storage device, 193: auxiliary storage device, 194: communication I/F, 195: extension I/F,
200: OLT, 200a: OLT, 200b: OLT, 210: terminal line switching control unit, 220: communication device authentication unit, 230: PON termination unit, 250: ONU management table, 251: ONU individual information, 252: link status, 253: connection device information, 260: threshold, 270: timer,
300: ONU, 301: ONU, 302: ONU, 303: ONU, 304: ONU, 310: PON terminal section, 320: UNI terminal section,
400: communication device, 401: communication device, 402: communication device, 403: communication device, 404: communication device,
500: WAN redundant communication device, 510: WAN port, 511: wired WAN port unit, 512: mobile line WAN module unit, 520: WAN connection control unit, 530: LAN connection port unit,
600: optical fiber, 601: optical fiber, 602: optical fiber, 603: optical fiber, 604: optical fiber, 690: optical coupler,
700: Wired cable, 701: Wired cable, 702: Wired cable, 703: Wired cable, 704: Wired cable,
800: Wired cable,
900: PON system, 920: OLT, 930: ONU, 940: communication equipment, 960: optical fiber cable, 969: optical coupler, 970: wired cable

Claims (10)

An OLT (Optical Line Terminal) of a PON (Passive Optical Network) system,
a terminal line switching control unit that detects traffic volume between each of a plurality of optical network units (ONUs) accommodated in the network and outputs an alarm notification when a total traffic volume, which is a sum of the traffic volumes, is greater than a first threshold value;
a communication device authentication unit that outputs, when the alarm notification is output, a switching instruction, which is an instruction to switch a connection destination from the predetermined line to a mobile line, to a first communication device connected to a replaceable ONU that is at least one ONU of the plurality of ONUs via the replaceable ONU;
The plurality of ONUs are each connected to one end of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the OLT is connected, and the other end of the optical fiber line branched by the optical coupler is connected,
The replaceable ONU is the ONU to which a communication device connected is the first communication device,
The first communication device is an OLT of a PON system, which is a communication device connectable to the specified line and the mobile line. 2. The OLT of the PON system according to claim 1,
The terminal line switching control unit, when the total traffic volume is greater than the first threshold value, further detects a specific traffic volume, which is the traffic volume between the replaceable ONU, and outputs the alarm notification only when the specific traffic volume is greater than a predetermined second threshold value. 3. An OLT of a PON system according to claim 1,
An ONU management table for managing the ONUs accommodated therein is further provided,
The communication device authentication unit
receiving a message from the first communication device via the replaceable ONU when the first communication device is connected to the replaceable ONU;
When the message is received, the connected device information is registered in the ONU management table in association with the information for identifying the replaceable ONU;
The connected device information is information indicating that the device connected to the replaceable ONU is the first communication device. An OLT of a PON system according to claim 3,
The communication device authentication unit
When receiving an abnormal disconnection notification from the first communication device via the replaceable ONU, register information indicating that the device connected to the replaceable ONU is the first communication device in the connected device information of the ONU management table in association with the replaceable ONU;
Masking the connected device information in the ONU management table for a predetermined mask period;
the abnormal disconnection notification is a notification transmitted from the first communication device after switching a connection to the mobile line, and indicates that the mobile line has been abnormally disconnected;
When the connected device information is masked in the ONU management table, the communication device authentication unit does not output the switching instruction to the first communication device even if the alarm notification is output. a WAN (Wide Area Network) port section for connecting to an ONU (Optical Network Unit) via a predetermined line;
a mobile line WAN module unit for connecting to a mobile line;
a connection control unit that switches a connection destination between the predetermined line and the mobile line,
The connection control unit is
When a connection is made to the ONU, a message is sent via the ONU to an OLT (Optical Line Terminal) which is a central office side device of the PON system that accommodates the ONU.
A redundant communication device that switches a connection from the specified line to the mobile line when a switching instruction is received from the OLT via the ONU to which it is connected, the switching instruction being an instruction to switch a connection destination from the specified line to the mobile line. 6. The redundant communication device according to claim 5,
The connection control unit is
A redundant communication device that, when the connection to the mobile line is disconnected due to an abnormality in the mobile line, switches the connection to the specified line, connects to the ONU, and sends a notification to the OLT via the ONU indicating that the mobile line has been abnormally disconnected. An OLT (Optical Line Terminal) which is a central office device connected to one end of an optical fiber line;
and a plurality of ONUs (Optical Network Units) which are optical subscriber devices each connected to the other end of the optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line,
At least one of the plurality of ONUs, i.e., a replaceable ONU, is a communication device connected to the replaceable ONU via a predetermined line, the communication device being a first communication device connectable to the predetermined line and a mobile line;
The OLT includes:
a terminal line switching control unit that detects a traffic volume between each of the plurality of ONUs, and outputs an alarm notification when a total traffic volume between the plurality of ONUs is greater than a first threshold value;
a communication device authentication unit that outputs, when the alarm notification is output, an instruction to the first communication device via the replaceable ONU to switch a connection destination from the specified line to the mobile line. A bandwidth control method by an OLT (Optical Line Terminal) of a PON (Passive Optical Network) system, comprising:
a traffic detection step of detecting the amount of traffic between the OLT and each of a plurality of ONUs (Optical Network Units) that are optical subscriber devices accommodated in the OLT;
a determining step of outputting an alarm notification when a total traffic volume, which is the sum of the detected traffic volumes, is greater than a predetermined first threshold value;
a switching instruction step of outputting, when the alarm notification is output, a switching instruction which is an instruction to switch a connection destination from a predetermined line to a mobile line to a first communication device connected to at least one of the plurality of ONUs via a replaceable ONU which is an ONU of the plurality of ONUs;
The plurality of ONUs are each connected to one end of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line to which the OLT is connected, and the other end of the optical fiber line branched by the optical coupler is connected,
The replaceable ONU is the ONU to which a communication device connected is the first communication device,
A bandwidth control method, wherein the first communication device is a communication device that can be connected to the specified line and the mobile line. The OLT (Optical Line Terminal) computer of the PON (Passive Optical Network) system
a traffic detection procedure for detecting the amount of traffic between each of the ONUs (Optical Network Units) connected to one end of an optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line connected to the OLT; the ONUs being a plurality of optical subscriber devices accommodated in the OLT, and the OLT and each of the ONUs being connected to the other end of the optical fiber line branched by an optical coupler inserted in the middle of the optical fiber line;
a determination step of outputting an alarm notification when a total traffic volume, which is the sum of the detected traffic volumes, is greater than a first threshold value;
A program for executing a switching instruction procedure, which, when the alarm notification is output, outputs a switching instruction to at least one ONU of the multiple ONUs, which is a replaceable ONU whose connected communication device is a first communication device that can be connected to a specified line and a mobile line, via the ONU, to the first communication device, which is an instruction to switch the connection destination from the specified line to the mobile line. A redundant communication device connected to an ONU (Optical Network Unit) of a PON (Passive Optical Network) system via a predetermined line,
a WAN (Wide Area Network) port unit that connects to the ONU via the predetermined line;
A computer of a redundant communication device including a mobile line WAN module unit for connecting to a mobile line,
a transmission procedure for transmitting a message via the ONU to an OLT (Optical Line Terminal) that accommodates the ONU when the ONU is connected to the OLT;
A program for executing a switching procedure for switching the connection destination from the specified line to the mobile line when a switching instruction is received from the OLT via the connected ONU, which is an instruction to switch the connection destination from the specified line to the mobile line.

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