Optical communication system, optical communication device, device switching method and program

Abstract

An optical communication system including a first communication device, a second communication device which communicates with the first communication device, and a third communication device which, after a device switching process, communicates with the first communication device instead of the second communication device, wherein the second communication device comprises a second communication unit which communicates with the first communication device, and a second control unit which transmits information indicating execution timing of the switching process to the third communication device and stops communication using the second communication unit in accordance with the execution timing, and the third communication device comprises a third communication unit which communicates with the first communication device, and a third control unit which, from the second communication device, acquires information indicating the execution timing and starts communication using the third communication unit in accordance with the execution timing.

Description

[Technical Field]

[0001] The present invention relates to an optical communication system, an optical communication device, a device switching method, and a program. [Background technology]

[0002] To achieve high-speed, high-capacity communications or due to aging caused by long-term operation, communication equipment may need to be replaced. In such cases, for example, to replace (switch) an existing OLT (Optical Line Terminal) with a successor OLT, it is necessary to switch the physical wiring between the OLT and ONU (Optical Network Unit). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-065575 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-111852 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-121038 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, such communication equipment upgrades required on-site manual physical wiring changes, which posed a problem of communication interruptions occurring during the switching work.

[0005] The present invention has been made in consideration of the above-described technical background, and aims to provide an optical communication system, an optical communication device, a device switching method, and a program that can suppress communication interruptions that occur when switching communication devices. [Means for solving the problem]

[0006] One aspect of the present invention is an optical communication system having a first communication device, a second communication device that communicates with the first communication device, and a third communication device that communicates with the first communication device in place of the second communication device after a device switching process, wherein the second communication device has a second communication unit that communicates with the first communication device and a second control unit that sends information indicating the execution timing of the switching process to the third communication device and stops communication by the second communication unit in accordance with the execution timing, and the third communication device has a third communication unit that communicates with the first communication device and a third control unit that obtains information indicating the execution timing from the second communication device and starts communication by the third communication unit in accordance with the execution timing.

[0007] Another aspect of the present invention is an optical communication device comprising: a communication unit that communicates with a first communication device; and a control unit that determines the execution timing of a switching process for switching the communication device that communicates with the first communication device from its own device to a second communication device, stops communication by the communication unit at a stop timing based on the execution timing, and transmits information indicating the execution timing to the second communication device that starts communication with the first communication device at a start timing based on the execution timing.

[0008] Another aspect of the present invention is a device switching method in an optical communication system having a first communication device, a second communication device that communicates with the first communication device, and a third communication device that communicates with the first communication device in place of the second communication device after a device switching process, the device switching method comprising: a transmission step in which the second communication device transmits information indicating the execution timing of the switching process to the third communication device; an acquisition step in which the third communication device acquires information indicating the execution timing from the second communication device; a second control step in which the second communication device stops communication with the first communication device in accordance with the execution timing; and a third control step in which the third communication device starts communication with the first communication device in accordance with the execution timing.

[0009] Another aspect of the present invention is a program for causing a computer to function as the optical communication device described above. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress communication interruptions that occur when switching communication devices. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating the overall configuration of a conventional optical communication system 1a. [Figure 2] 1 is a diagram showing the overall configuration of an optical communication system 1 according to a first embodiment of the present invention. [Figure 3] FIG. 10 is a diagram showing a state before switching from the existing OLT 10-1 to the successor OLT 10-2. [Figure 4] FIG. 10 is a diagram showing the state of wiring after preliminary wiring for switching the OLT. [Figure 5] FIG. 10 is a diagram showing the state of wiring after OLT switching has been performed. [Figure 6] 3 is a flowchart showing the operation of the optical communication system 1 in the first embodiment of the present invention. [Figure 7] FIG. 4 is a sequence diagram showing an OLT switching process in the first embodiment of the present invention. [Figure 8] FIG. 10 is a sequence diagram showing an OLT switching process in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an optical communication system, an optical communication device, a device switching method, and a program according to an embodiment will be described with reference to the drawings.

[0013] In the embodiment described below, wiring work is performed in advance to switch from an existing OLT (hereinafter referred to as "existing OLT") to a successor OLT (hereinafter referred to as "successor OLT"). Specifically, wiring work is performed in advance so that a redundant network port (hereinafter referred to as "redundant port") can be used as a post-switching network port (hereinafter referred to as "switching port").

[0014] In the embodiment described below, information is shared between the existing OLT and the successor OLT. Specifically, the control panels provided in the existing OLT and the successor OLT are connected to each other for communication. Then, information about the existing OLT (hereinafter referred to as "OLT information") is transmitted from the existing OLT to the successor OLT, and the timing for switching is determined based on the OLT information. When switching is performed, the presence or absence of priority frames in communication at the existing OLT is monitored, and the optimal timing is determined taking into consideration the presence or absence of wired frames.

[0015] In this way, the optical communication system, optical communication device, device switching method, and program of the embodiment have technology that suppresses communication interruptions associated with switching communication devices through advance wiring and information sharing between the existing OLT and the successor OLT.

[0016] In order to facilitate understanding of the description of the configuration of the optical communication system according to the embodiment, the configuration of an optical communication system 1a, which is an example of a conventional optical communication system, will be described below for comparison.

[0017] Fig. 1 is a diagram showing the overall configuration of a conventional optical communication system 1a. As shown in Fig. 1, the conventional optical communication system 1a includes an existing OLT 10a-1, a successor OLT 10a-2, an optical selector 20a-1, an optical selector 20a-2, an ONU 30, and an upper-level device 40.

[0018] As shown in Fig. 1, the existing OLT 10a-1 includes a control panel 11a-1 and multiple PON (Passive Optical Network) interface packages. The multiple PON interface packages include at least one PON interface package (hereinafter referred to as "PON-PKG 12-1") used for normal communication with the ONU 30 and at least one PON interface package (hereinafter referred to as "redundancy PKG 12r-1") provided for redundancy. Note that, for simplicity, Fig. 1 shows only one PON-PKG 12-1 and one redundancy PKG 12r-1.

[0019] As shown in FIG. 1, the optical selector 20a-1 includes a coupler module 21-1 and an optical switch 22-1.

[0020] The coupler module 21-1 communicatively connects the ONU 30, the PON-PKG 12-1, and the optical switch 22-1 to one another. The optical switch 22-1 communicatively connects the coupler module 21-1 to the redundant PKG 12r-1 to one another. The PON-PKG 12-1 communicatively connects the coupler module 21-1 to the upper-level device 40 to one another. The redundant PKG 12r-1 communicatively connects to the optical switch 22-1. The upper-level device 40 communicatively connects to the PON-PKG 12-1.

[0021] Before switching from the existing OLT 10a-1 to the successor OLT 10a-2, the ONU 30 and the higher-level device 40 transmit data to each other via the PON-PKG 12-1 of the existing OLT 10a-1 and the coupler module 21-1 of the optical selector 20a-1.

[0022] As shown in Fig. 1, the successor OLT 10a-2 includes a control panel 11a-2 and multiple PON interface packages. The multiple PON interface packages include at least one PON interface package (hereinafter referred to as "PON-PKG 12-2") used for normal communication with the ONU 30 and at least one PON interface package (hereinafter referred to as "redundant PKG 12r-2") provided for redundancy. Note that, for simplicity, Fig. 1 shows only one PON-PKG 12-2 and one redundant PKG 12r-2.

[0023] As shown in FIG. 1, the optical selector 20a-2 includes a coupler module 21-2 and an optical switch 22-2.

[0024] The coupler module 21-2 communicatively connects the PON-PKG 12-2 and the optical switch 22-2. The optical switch 22-2 communicatively connects the coupler module 21-2 and the redundant PKG 12r-2. The PON-PKG 12-2 communicatively connects to the coupler module 21-2. The redundant PKG 12r-2 communicatively connects to the optical switch 22-2.

[0025] Before switching from the existing OLT 10a-1 to the successor OLT 10a-2, the coupler module 21-2 and the ONU 30 are not communicatively connected to each other. Also, before switching from the existing OLT 10a-1 to the successor OLT 10a-2, the PON-PKG 12-2 and the higher-level device 40 are not communicatively connected to each other.

[0026] 1, when switching from the existing OLT 10a-1 to the successor OLT 10a-2, physical wiring is manually reconfigured. Specifically, the wiring connected from the ONU 30 to the coupler module 21-1 of the optical selector 20a-1 is reconfigured so that it connects from the ONU 30 to the coupler module 21-2 of the optical selector 20a-2. In addition, the wiring connected from the upper-level device 40 to the PON-PKG 12-1 of the existing OLT 10a-1 is reconfigured so that it connects from the upper-level device 40 to the PON-PKG 12-2 of the successor OLT 10a-2.

[0027] After switching from the existing OLT 10a-1 to the successor OLT 10a-2, the ONU 30 and the higher-level device 40 transmit data to each other via the PON-PKG 12-2 of the successor OLT 10a-2 and the coupler module 21-2 of the optical selector 20a-2.

[0028] As described above, in the conventional optical communication system 1a, when switching from the existing OLT 10a-1 to the successor OLT 10a-2, the physical wiring must be manually rewired. Therefore, in the conventional optical communication system 1a, communication interruptions and frame loss are likely to occur during the rewiring work.

[0029] First Embodiment A first embodiment of the present invention will be described below with reference to the drawings.

[0030] [Configuration of optical communication system] 2 is a diagram showing the overall configuration of an optical communication system 1 according to a first embodiment of the present invention. As shown in FIG. 2, the optical communication system 1 includes an existing OLT 10-1, a successor OLT 10-2, an optical selector 20a-1, an optical selector 20, an ONU 30, and an upper-level device 40.

[0031] As shown in Fig. 2, the existing OLT 10-1 is configured to include a control panel 11-1 and multiple PON interface packages. The multiple PON interface packages include at least one PON interface package (PON-PKG 12-1) used for normal communication with the ONU 30 and at least one PON interface package (redundancy PKG 12r-1) provided for redundancy. Note that, for simplicity's sake, Fig. 2 shows only one PON-PKG 12-1 and one redundancy PKG 12r-1.

[0032] As shown in FIG. 2, the optical selector 20 includes a coupler module 21 and an optical switch 22.

[0033] The coupler module 21 communicatively connects the ONU 30, the PON-PKG 12-1, and the optical switch 22 to one another. The optical switch 22 communicatively connects the coupler module 21 and the redundant PKG 12r-1 to one another. The PON-PKG 12-1 communicatively connects the coupler module 21 and the higher-level device 40 to one another. The redundant PKG 12r-1 is communicatively connected to the optical switch 22. The higher-level device 40 is communicatively connected to the PON-PKG 12-1.

[0034] Before switching from the existing OLT 10-1 to the successor OLT 10-2, the ONU 30 and the higher-level device 40 transmit data to each other via the PON-PKG 12-1 of the existing OLT 10-1 and the coupler module 21 of the optical selector 20.

[0035] As shown in Figure 2, the successor OLT 10-2 includes a control panel 11-2 and multiple PON interface packages. The multiple PON interface packages include at least one PON interface package (PON-PKG 12-2) used for normal communication with the ONU 30 and at least one PON interface package (redundancy PKG 12r-2) provided for redundancy. Note that, for simplicity, Figure 2 shows only one PON-PKG 12-2 and one redundancy PKG 12r-2.

[0036] In the optical communication system 1 of this embodiment, when switching from the existing OLT 10-1 to the successor OLT 10-2, wiring is performed in advance. Specifically, the control panel 11-1 of the existing OLT 10-1 and the control panel 11-2 of the successor OLT 10-2 are connected in advance of the switching. Furthermore, the coupler module 21 of the optical selector 20 and the PON-PKG 12-2 of the successor OLT 10-2 are connected in advance before the switching. Furthermore, the PON-PKG 12-2 of the successor OLT 10-2 and the higher-level device 40 are connected in advance before the switching.

[0037] The coupler module 21 of the optical selector 20 is connected to the PON-PKG 12-2 of the successor OLT 10-2 via a redundancy port of the coupler module 21. The details of the connection to the redundancy port will be explained later.

[0038] Furthermore, in the optical communication system 1 of this embodiment, when switching from the existing OLT 10-1 to the successor OLT 10-2 is performed, OLT information about the existing OLT 10-1 is transmitted from the control panel 11-1 of the existing OLT 10-1 to the control panel 11-2 of the successor OLT 10-2. As a result, the function as an OLT is taken over from the existing OLT 10-1 to the successor OLT 10-2.

[0039] The OLT information here includes, for example, the MAC (Media Access Control) address of each ONU, ONU alarm information, VLAN (Virtual Local Area Network) setting information, port information, and ONU setting information.

[0040] The control panel 11-1 of the existing OLT 10-1 and the control panel 11-2 of the successor OLT 10-2 exchange information including OLT information in real time, and automatically switch from the existing OLT 10-1 to the successor OLT 10-2 by controlling the operation of the coupler module 21 of the optical selector 20 at the appropriate timing.

[0041] After switching from the existing OLT 10-1 to the successor OLT 10-2, the ONU 30 and the higher-level device 40 transmit data to each other via the PON-PKG 12-2 of the successor OLT 10-2 and the coupler module 21 of the optical selector 20.

[0042] In this way, in the optical communication system 1 of the first embodiment, when switching from the existing OLT 10-1 to the successor OLT 10-2, wiring and transmission of OLT information are performed in advance, and the switching is performed automatically at the appropriate timing, thereby suppressing communication interruptions.

[0043] The appropriate timing is determined based on, for example, whether or not a situation in which a priority frame is being transmitted or received is occurring. A situation in which a priority frame is being transmitted or received here refers to a situation in which important communication such as an emergency call is occurring, for example. The control panel 11-1 of the existing OLT 10-1 automatically identifies the appropriate switching timing by monitoring in real time whether or not a priority frame is being transmitted or received. The control panel 11-1 of the existing OLT 10-1 transmits the identified switching timing to the control panel 11-2 of the successor OLT 10-2.

[0044] The existing OLT 10-1 and the successor OLT 10-2 automatically execute processing for switching the OLTs in a synchronized manner based on the transmitted information. Specifically, for example, the control panel 11-1 of the existing OLT 10-1 and the control panel 11-2 of the OLT 10-2 execute switching by synchronizing the timing of starting and stopping light emission based on the transmitted information.

[0045] Note that, when wiring is performed in advance for the above-described OLT switching, if a failure is detected in the PON-PKG 12-1 of the existing OLT 10-1, the failed PON-PKG 12-1 may be preferentially switched to the PON-PKG 12-2 of the successor OLT 10-2. In this case, it is possible to provide redundancy to communications by the optical communication system 1.

[0046] The OLT information transmitted from the control panel 11-1 to the control panel 11-2 may include authentication information required at the time of switching. In this case, the successor OLT 10-2 can store the authentication information in advance, which makes it possible to shorten the communication interruption time that occurs due to the authentication process at the time of switching.

[0047] By providing the above-described configuration, the optical communication system 1 according to the first embodiment does not require manual cable insertion / removal work when switching the OLT. This makes it possible to avoid long communication interruptions that occur due to physical wiring changes and the resulting frame loss. Furthermore, in the optical communication system 1 according to the first embodiment, OLT switching is performed automatically after the wiring is performed in advance. This makes it possible to perform switching at any time of the day or night, and also makes it possible to perform switching at multiple locations simultaneously.

[0048] Furthermore, by providing the above-described configuration, the optical communication system 1 according to the first embodiment can provide redundancy between the OLTs by prior wiring. This makes it possible to handle a failure in the PON-PKG 12-1 and switch the OLT in parallel.

[0049] An example of the configuration of OLT switching by the optical communication system 1 in the first embodiment will be described in more detail below with reference to Fig. 3 to Fig. 5. Fig. 3 to Fig. 5 show, from the configuration of the optical communication system 1, a part of the configuration of the existing OLT 10-1, a part of the configuration of the successor OLT 10-2, the optical selector 20, and the ONU 30.

[0050] Fig. 3 is a diagram showing the state before switching from the existing OLT 10-1 to the successor OLT 10-2. That is, Fig. 3 shows the wiring state before preliminary wiring for OLT switching is performed. Fig. 4 is a diagram showing the wiring state after preliminary wiring for OLT switching is performed. Fig. 5 is a diagram showing the wiring state after OLT switching is performed.

[0051] As shown in Figure 3, before the preliminary wiring for OLT switching is performed, the port of the coupler module 21 connected to the ONU 30 is connected to a port connected to the PON-PKG 12-1 of the existing OLT 10-1 and a redundant port connected to the redundant PKG 12r-1 of the existing OLT 10-1 via the optical switch 22.

[0052] Next, as shown in Figure 4, among the wiring that connects the redundant port of the coupler module 21 and the optical switch 22 in advance for OLT switching, the wiring on the optical switch 22 side is removed and replaced with the PON-PKG12-2 of the successor OLT 10-2.

[0053] Next, as shown in Figure 5, when the OLT is switched at the appropriate timing described above, of the wiring connecting the port connected to PON-PKG12-1 of the coupler module 21 and the PON-PKG12-1, the wiring on the PON-PKG12-1 side is removed and replaced with the port of the optical switch 22 connected to the redundant PKG12r-1.

[0054] In this way, the optical communication system 1 in this embodiment can avoid communication interruptions that occur when wiring is changed when switching OLTs by performing wiring in advance using redundant ports.

[0055] The above-described device switching method is not limited to application to PON communication systems, but can also be applied to optical access communications such as media converters.

[0056] [Operation of optical communication system] An example of the operation of the optical communication system 1 in the first embodiment will be described below. Fig. 6 is a flowchart showing the operation of the optical communication system 1 in the first embodiment of the present invention.

[0057] First, in the optical communication system 1, when switching from the existing OLT 10-1 to the successor OLT 10-2, wiring is performed in advance (step S001). Specifically, the control panel 11-1 of the existing OLT 10-1 and the control panel 11-2 of the successor OLT 10-2 are connected in advance of the switching. Furthermore, the coupler module 21 of the optical selector 20 and the PON-PKG 12-2 of the successor OLT 10-2 are connected in advance of the switching. Furthermore, the PON-PKG 12-2 of the successor OLT 10-2 and the higher-level device 40 are connected in advance of the switching.

[0058] Next, when switching from the existing OLT 10-1 to the successor OLT 10-2 in the optical communication system 1, OLT information about the existing OLT 10-1 is transmitted from the control panel 11-1 of the existing OLT 10-1 to the control panel 11-2 of the successor OLT 10-2 (step S002).

[0059] Next, when wiring is performed in advance for switching the OLT, the control panel 11-1 of the existing OLT 10-1 checks the state of the PON-PKG 12-1 (step S003).

[0060] If a failure of the PON-PKG 12-1 is detected (Yes in step S004), the control panels 11-1 and 11-2 switch the failed PON-PKG 12-1 preferentially to the PON-PKG 12-2 of the successor OLT 10-2 (step S005), and then proceed to the processing of step S009.

[0061] If no failure of the PON-PKG 12-1 is detected (step S004: No), the control panel 11-1 checks the traffic for each PON-PKG 12-1 (step S006).

[0062] If the traffic check detects that a priority frame is being transmitted (Yes in step S007), the control panel 11-1 and the control panel 11-2 wait until the transmission of the priority frame is completed (step S008), and then return to the processing of step S002.

[0063] When the traffic check does not detect that a priority frame is being transmitted (step S007: No), the control boards 11-1 and 11-2 execute OLT switching (step S009).

[0064] When the switching of all PON-PKGs 12-1 of the existing OLT 10-1 to the successor OLT 10-2 is completed (Yes in step S010), the control panels 11-1 and 11-2 perform processing associated with the completion of the OLT switching (step S011). The processing associated with the completion of the OLT switching here refers to, for example, the processing of disconnecting the wiring on the PON-PKG 12-1 side from the wiring connecting the port of the coupler module 21 connected to the PON-PKG 12-1 and the PON-PKG 12-1, as shown in FIG. 5, and replacing it with the port of the optical switch 22 connected to the redundant PKG 12r-1.

[0065] If there is a PON-PKG 12-1 for which switching to the successor OLT 10-2 has not been completed (step S010: No), the process returns to step S003, and the above process is repeated until switching to the successor OLT 10-2 is completed for all PON-PKGs 12-1 of the existing OLT 10-1. This completes the operation of the optical communication system 1 shown in the flowchart of FIG.

[0066] [Switching process sequence] An example of the sequence of the OLT switching process in the optical communication system 1 in the first embodiment will be described below. Fig. 7 is a sequence diagram showing the OLT switching process in the first embodiment of the present invention.

[0067] When switching from the existing OLT 10-1 to the successor OLT 10-2 is performed in the optical communication system 1 in the first embodiment, first, OLT information is transmitted from the control panel 11-1 of the existing OLT 10-1 to the control panel 11-2 of the successor OLT 10-2 (ACT101), as shown in Fig. 7. When the control panel 11-2 has completed acquisition of the OLT information, it returns a transmission completion notice indicating completion to the control panel 11-1 (ACT102).

[0068] When the control panel 11-1 receives the transmission completion notification sent from the control panel 11-2, it sends a signal to the PON-PKG 12-1 to be switched over for status confirmation (ACT 103). As mentioned above, checking the status of the PON-PKG 12-1 here means, for example, checking whether the PON-PKG 12-1 is malfunctioning. When the PON-PKG 12-1 receives the status confirmation signal from the control panel 11-1, it responds by returning a signal indicating its own status to the control panel 11-1 (ACT 104).

[0069] When the control panel 11-1 receives a signal from the PON-PKG 12-1 to be switched indicating that it is in a normal state, it transmits a signal to the PON-PKG 12-1 to confirm the presence or absence of a priority frame (ACT 105). The presence or absence of a priority frame here refers to the state of whether or not the PON-PKG 12-1 is transmitting a priority frame, as described above. When the PON-PKG 12-1 receives the signal to confirm the presence or absence of a priority frame from the control panel 11-1, it responds by returning a signal indicating the state of whether or not a priority frame is being transmitted to the control panel 11-1 (ACT 106).

[0070] When the control panel 11-1 receives a signal from the switching target PON-PKG 12-1 indicating that it is not transmitting a priority frame, it sends a signal to the PON-PKG 12-1 instructing it to stop emitting light (ACT 107). When the PON-PKG 12-1 receives a signal instructing it to stop emitting light from the control panel 11-1, it stops emitting light. When the PON-PKG 12-1 stops emitting light, it sends a notification to the control panel 11-1 indicating that cessation of light emission has been completed (ACT 108).

[0071] When the control panel 11-1 receives a notification from the switching target PON-PKG 12-1 indicating that the cessation of light emission has been completed, it transmits a signal indicating an instruction to start light emission of the PON-PKG 12-2 of the successor OLT 10-2 to the PON-PKG 12-2 via the control panel 11-2 (ACT109). When the PON-PKG 12-2 receives a signal indicating an instruction to start light emission from the control panel 11-1, it starts light emission. When the PON-PKG 12-2 starts light emission, it transmits a notification to the control panel 11-1 via the control panel 11-2 indicating that the start of light emission has been completed (ACT110).

[0072] Next, the ONU 30 transmits an upstream signal to the PON-PKG 12-2 of the successor OLT 10-2 (ACT 111). Upon receiving the upstream signal transmitted from the ONU 30, the PON-PKG 12-2 transmits the upstream signal to the upper level device 40 (ACT 112).

[0073] When the upper-level device 40 receives an upstream signal from PON-PKG 12-2 of the successor OLT 20-2, it changes the path of the downstream signal so that the downstream signal is transmitted to the PON-PKG 12-2 (ACT 113). In this way, the upper-level device 40 identifies the PON-PKG 12-2 that emitted light based on the received upstream signal (i.e., detects the path) and automatically determines the destination of the downstream signal. After changing the path of the downstream signal, the upper-level device 40 transmits the downstream signal to PON-PKG 12-2 of the successor OLT 10-2 via the changed path (ACT 114).

[0074] When the PON-PKG 12-2 of the successor OLT 10-2 receives the downstream signal from the higher-level device 40, it transmits a notification indicating that the downstream signal has been received to the control panel 11-2 (ACT115). When the control panel 11-2 receives a notification indicating that the downstream signal has been received from the PON-PKG 12-2, it transmits a notification indicating that the OLT switching has been completed to the control panel 11-1 of the existing OLT 10-1 (ACT116).

[0075] When the control panel 11-1 of the existing OLT 10-1 receives a notification from the control panel 11-2 of the successor OLT 10-2 indicating that the switching has been completed, it executes the same process as above for the remaining PON-PKGs 12-1 (ACT 117). When the above process is completed for all PON-PKGs 12-1, the OLT switching process in the optical communication system 1 according to the first embodiment shown in the sequence diagram of FIG. 7 is completed.

[0076] As described above, in the optical communication system 1 according to the first embodiment of the present invention, wiring work is performed in advance when switching from the existing OLT 10-1 to the successor OLT 10-2. Specifically, the wiring work is performed in advance so that a redundant port is used as a switching port. In the optical communication system 1 according to the first embodiment, information is appropriately shared between the existing OLT 10-1 and the successor OLT 10-2. Specifically, the control panel 11-1 of the existing OLT 10-1 and the control panel 11-2 of the successor OLT 10-2 are communicatively connected to each other, and OLT information is transmitted from the existing OLT 10-1 to the successor OLT 10-2. The control panel 11-1 of the existing OLT 10-1 determines the timing of switching based on the OLT information. At this time, the optimal timing is determined taking into consideration the presence or absence of priority frames in communication in the existing OLT 10-1.

[0077] With this configuration, the optical communication system 1 in the first embodiment can suppress communication interruptions due to OLT switching by prior wiring and information linkage between the existing OLT 10-1 and the successor OLT 10-2.

[0078] <Second embodiment> A first embodiment of the present invention will be described below with reference to the drawings.

[0079] In the optical communication system 1 in the first embodiment described above, communication interruptions due to OLT switching can be suppressed by prior wiring, etc. However, as shown in the processing of ACT107 to ACT110 in Fig. 7 described above, in the optical communication system 1 in the first embodiment, communication is interrupted only during the period from when the PON-PKG 12-1 of the existing OLT 10-1 stops emitting light until when the PON-PKG 12-2 of the successor OLT 10-2 starts emitting light, and frame loss may occur.

[0080] In contrast, an optical communication system according to a second embodiment described below can prevent frame loss due to communication interruptions as described above. Note that the overall configuration diagram of the optical communication system according to the second embodiment is similar to the overall configuration diagram of the optical communication system 1 according to the first embodiment shown in FIG. 2, and therefore a description thereof will be omitted. Hereinafter, the OLT switching process by the optical communication system according to the second embodiment will be described using the reference numerals assigned to the respective components of the optical communication system 1 according to the first embodiment.

[0081] [Switching process sequence] An example of the sequence of the OLT switching process in the optical communication system 1 in the second embodiment will be described below. Fig. 8 is a sequence diagram showing the OLT switching process in the second embodiment of the present invention.

[0082] When switching from the existing OLT 10-1 to the successor OLT 10-2 is performed in the optical communication system 1 in the second embodiment, first, OLT information is transmitted from the control panel 11-1 of the existing OLT 10-1 to the control panel 11-2 of the successor OLT 10-2 (ACT201), as shown in Fig. 8. When the control panel 11-2 has completed acquisition of the OLT information, it returns a transmission completion notice indicating completion to the control panel 11-1 (ACT202).

[0083] When the control panel 11-1 receives the transmission completion notification sent from the control panel 11-2, it sends a signal to the PON-PKG 12-1 to be switched over for status confirmation (ACT203). As mentioned above, checking the status of the PON-PKG 12-1 here means, for example, checking whether the PON-PKG 12-1 is malfunctioning. When the PON-PKG 12-1 receives the status confirmation signal from the control panel 11-1, it responds by returning a signal indicating its own status to the control panel 11-1 (ACT204).

[0084] When the control panel 11-1 receives a signal from the PON-PKG 12-1 to be switched indicating that it is in a normal state, it transmits a signal to the PON-PKG 12-1 to confirm the presence or absence of a priority frame (ACT 205). The presence or absence of a priority frame here refers to the state of whether or not the PON-PKG 12-1 is transmitting a priority frame, as described above. When the PON-PKG 12-1 receives the signal to confirm the presence or absence of a priority frame from the control panel 11-1, it responds by returning a signal indicating the state of whether or not a priority frame is being transmitted to the control panel 11-1 (ACT 206).

[0085] When the control panel 11-1 receives a signal from the switching target PON-PKG 12-1 indicating that a priority frame is not being transmitted, it transmits a notification to the PON-PKG 12-1 indicating an instruction to start switching the OLT (ACT 207). When the PON-PKG 12-1 receives the notification from the control panel 11-1 indicating an instruction to start switching the OLT, it transmits a notification to the higher-level device 40 indicating an instruction to change to the communication path after switching (ACT 208).

[0086] When the upper level device 40 receives a notification indicating an instruction to change the communication path from the PON-PKG 12-1 of the existing OLT 10-1 to the post-switching communication path, the upper level device 40 changes the path of the downstream signal to the notified communication path (ACT209). After changing the path of the downstream signal, the upper level device 40 transmits the downstream signal to the PON-PKG 12-2 of the successor OLT 10-2 via the changed path (ACT210).

[0087] When the PON-PKG 12-2 of the successor OLT 10-2 receives a downstream signal from the upper-level device 40, it starts buffering (holding) the received downstream signal (ACT211). In this way, in the optical communication system 1 of the second embodiment, the path of the downstream signal from the upper-level device 40 is switched before switching the OLT, and the downstream signal is buffered. This makes it possible to prevent frame loss due to communication interruption accompanying OLT switching. When the PON-PKG 12-2 starts buffering the downstream signal, it transmits a notification indicating that the downstream signal has been received to the control panel 11-1 of the existing OLT 10-1 via the control panel 11-2 (ACT212 and ACT213).

[0088] When the control panel 11-1 of the existing OLT 10-1 receives a notification indicating that a downstream signal transmitted from the PON-PKG 12-2 of the successor OLT 10-2 has been received, it transmits a signal instructing the PON-PKG 12-1, which has been confirmed to be not transmitting a priority frame in the processes of ACT205 to ACT206 above, to stop light emission (ACT214). When the PON-PKG 12-1 receives the signal instructing it to stop light emission from the control panel 11-1, it stops light emission. When the PON-PKG 12-1 stops light emission, it transmits a notification to the control panel 11-1 indicating that light emission has been stopped (ACT215).

[0089] When the control panel 11-1 receives a notification from the switching target PON-PKG 12-1 indicating that the cessation of light emission has been completed, it transmits a signal indicating an instruction to start light emission of the PON-PKG 12-2 of the successor OLT 10-2 to the PON-PKG 12-2 via the control panel 11-2 (ACT216 and ACT217). When the PON-PKG 12-2 receives a signal indicating an instruction to start light emission from the control panel 11-1, it starts light emission. When the PON-PKG 12-2 starts light emission, it transmits a notification indicating that the start of light emission has been completed to the control panel 11-1 via the control panel 11-2 (ACT218 and ACT219).

[0090] Next, when the control panel 11-2 of the successor OLT 11-2 receives a notification from the PON-PKG 12-2 indicating that the start of light emission has been completed, it transmits a signal to the PON-PKG 12-2 indicating an instruction to cancel the execution of buffering (ACT220). When the PON-PKG 12-2 receives a signal indicating an instruction to cancel the execution of buffering from the control panel 11-2, it terminates the execution of buffering. Next, the PON-PKG 12-2 transmits the buffered signals (frames) together to the ONU 30 (ACT221).

[0091] When the control panel 11-1 of the existing OLT 10-1 receives a notification from the control panel 11-2 of the successor OLT 10-2 indicating that the start of light emission has been completed, it executes the same process as above for the remaining PON-PKGs 12-1 (ACT222). When the above process is completed for all PON-PKGs 12-1, the OLT switching process in the optical communication system 1 according to the second embodiment shown in the sequence diagram of FIG. 8 is completed.

[0092] As described above, in the optical communication system 1 according to the second embodiment of the present invention, wiring work is performed in advance when switching from the existing OLT 10-1 to the successor OLT 10-2. Specifically, the wiring work is performed in advance so that a redundant port is used as a switching port. In the optical communication system 1 according to the second embodiment, information is appropriately shared between the existing OLT 10-1 and the successor OLT 10-2. Specifically, the control panel 11-1 of the existing OLT 10-1 and the control panel 11-2 of the successor OLT 10-2 are connected to each other for communication, and OLT information is transmitted from the existing OLT 10-1 to the successor OLT 10-2. The control panel 11-1 of the existing OLT 10-1 determines the timing of switching based on the OLT information. At this time, the optimal timing is determined taking into consideration the presence or absence of priority frames in communication in the existing OLT 10-1.

[0093] With this configuration, the optical communication system 1 in the second embodiment can suppress communication interruptions due to OLT switching by prior wiring and information linkage between the existing OLT 10-1 and the successor OLT 10-2.

[0094] As described above, in the optical communication system 1 according to the second embodiment of the present invention, the path of the downstream signal from the higher-level device 40 is switched and the downstream signal is buffered before switching the OLT, as in the processes of ACT209 to ACT211 in the sequence diagram shown in Fig. 8. This makes it possible to prevent frame loss due to communication interruption accompanying switching of the OLT.

[0095] As described above, the optical communication system 1 according to the second embodiment has the advantage of being able to prevent frame loss due to communication interruption caused by OLT switching. On the other hand, in the optical communication system 1 according to the first embodiment described above, frame loss due to communication interruption may occur only during the period from when the PON-PKG 12-1 of the existing OLT 10-1 stops emitting light until when the PON-PKG 12-2 of the successor OLT 10-2 starts emitting light. However, the optical communication system 1 according to the first embodiment described above does not need to be provided with a configuration for buffering downstream signals, as in the optical communication system 1 according to the second embodiment, and therefore has the advantage of being able to simplify the system configuration.

[0096] According to the above-described embodiment, the optical communication system includes a first communication device, a second communication device that communicates with the first communication device, and a third communication device that communicates with the first communication device instead of the second communication device after device switching processing. For example, the first communication device is the ONU 30 in the embodiment, the second communication device is the existing OLT 10-1 in the embodiment, and the third communication device is the successor OLT 10-2 in the embodiment.

[0097] The second communication device includes a second communication unit that communicates with the first communication device, and a second control unit that transmits information indicating the execution timing of the switching process to the third communication device and stops communication by the second communication unit according to the execution timing. For example, the second communication unit is the PON-PKG 12-1 of the existing OLT 10-1 in the embodiment, the information indicating the execution timing of the switching process is the OLT information in the embodiment, and the second control unit is the control panel 11-1 in the embodiment.

[0098] The third communication device includes a third communication unit that communicates with the first communication device, and a third control unit that acquires information indicating execution timing from the second communication device and starts communication by the third communication unit according to the execution timing. For example, the third communication unit is the PON-PKG 12-2 of the successor OLT 10-2 in the embodiment, and the third control unit is the control panel 11-2 in the embodiment.

[0099] The optical communication system may further include a switching unit. For example, the switching unit is the optical selector 20 in the embodiment. In this case, the switching unit connects to the first communication device and switches the communication path in accordance with the switching process. In this case, the switching unit and the second communication device are connected at least until the switching process is completed, and the switching unit and the third communication device are connected at least until the switching process is started.

[0100] In the above optical communication system, a redundant port may be used as the port of the switching unit connected to the third communication device.

[0101] In the above optical communication system, the second control unit may check whether or not a priority frame is being transmitted by the second communication unit, and determine the execution timing so that it is a time when a priority frame is not being transmitted.

[0102] In the above optical communication system, the second control unit may detect whether or not there is a malfunction in the second communication unit, and if there is a malfunction in the second communication unit, may determine the execution timing so that the switching process is executed with priority.

[0103] Furthermore, according to the above-described embodiment, the optical communication device includes a communication unit and a control unit. For example, the optical communication device is the existing OLT 10-1 in the embodiment, the communication unit is the PON-PKG 12-1 in the embodiment, and the control unit is the control panel 11-1 in the embodiment. The communication unit communicates with a first communication device. For example, the first communication device is the ONU 30 in the embodiment.

[0104] The control unit determines the execution timing of a switching process for switching the communication device that communicates with the first communication device from its own device to a second communication device, stops communication by the communication unit at a stop timing based on the execution timing, and transmits information indicating the execution timing to the second communication device that starts communication with the first communication device at a start timing based on the execution timing. For example, the second communication device is a successor OLT 10-2 in the embodiment, and the information indicating the execution timing is OLT information in the embodiment.

[0105] A portion of the configuration of the optical communication system 1 in the above-described embodiment may be implemented by a computer. In this case, a program for implementing the functions may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" as used herein includes hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. Furthermore, the term "computer-readable recording medium" may also include devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or telephone lines, or devices that store programs for a fixed period of time, such as volatile memory within a computer system that serves as a server or client. The program may be for implementing a portion of the above-described functions, or may be capable of implementing the above-described functions in combination with a program already stored in the computer system, or may be implemented using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0106] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Explanation of symbols]

[0107] 1, 1a... optical communication system, 11-1, 11-2, 11a-1, 11a-2... control panel, 12-1, 12-2... PON-PKG, 20, 20a-1, 20a-2... optical selector, 21, 21-1, 21-2... coupler module, 22, 22-1, 22-2... optical switch, 40... upper device

Claims

1. An optical communication system having a first communication device, a second communication device that communicates with the first communication device, and a third communication device that communicates with the first communication device instead of the second communication device after a device switching process, the second communication device, a second normal time communication unit used for normal time communication with the first communication device; a second redundant communication unit provided for redundancy and connected to the first communication device; a second control unit that transmits information indicating an execution timing of the switching process to the third communication device and performs a stop process to stop communication by the second normal communication unit in accordance with the execution timing; Equipped with the third communication device, a third normal time communication unit used for normal time communication with the first communication device; a third control unit that acquires information indicating the execution timing from the second communication device and performs a start process to start communication by the third normal mode communication unit in accordance with the execution timing; Equipped with The switching process is a process of performing the stop process and the start process after a wiring connecting to the first communication device is switched from the second redundant communication unit to the third normal communication unit. Optical communication system.

2. a switching unit that connects to the first communication device and switches the communication path in accordance with the switching process; and The switching unit and the second communication device are connected at least until the switching process is completed, The switching unit and the third communication device are connected at least until the switching process starts.

2. The optical communication system according to claim 1.

3. A redundant port is used as the port of the switching unit connected to the third communication device.

3. The optical communication system according to claim 2.

4. The second control unit checks whether or not the second normal mode communication unit is transmitting a priority frame, and determines the execution timing so as to be a timing when the priority frame is not being transmitted.

4. An optical communication system according to claim 1.

5. The second control unit detects whether or not the second normal mode communication unit has a failure, and if the second normal mode communication unit has a failure, determines the execution timing so as to execute the switching process with priority.

4. An optical communication system according to claim 1.

6. a normal communication unit used for normal communication with the first communication device; a redundant communication unit provided for redundancy and connected to the first communication device; a control unit that determines an execution timing of a switching process for switching a communication device that communicates with the first communication device from its own device to a second communication device, performs a stop process for stopping communication by the normal communication unit at a stop timing based on the execution timing, and performs a transmission process for transmitting information indicating the execution timing to the second communication device that starts communication with the first communication device at a start timing based on the execution timing; Equipped with The switching process is a process of performing the stop process and the transmission process after the wiring connecting the device itself is switched from the redundant communication unit to the communication unit of the second communication device. Optical communication equipment.

7. A device switching method in an optical communication system having a first communication device, a second communication device that has a second normal-time communication unit used for normal communication with the first communication device and a second redundant communication unit that is provided for redundancy and connected to the first communication device, and that communicates with the first communication device, and a third communication device that has a third normal-time communication unit used for normal communication with the first communication device, and that communicates with the first communication device instead of the second communication device after a device switching process, a transmission step in which the second communication device transmits information indicating the execution timing of the switching process to the third communication device; an acquisition step in which the third communication device acquires information indicating the execution timing from the second communication device; a second control step in which the second communication device performs a stop process to stop communication with the first communication device according to the execution timing; a third control step in which the third communication device performs a start process to start communication with the first communication device according to the execution timing; and The switching process is a process of performing the stop process and the start process after a wiring connecting to the first communication device is switched from the second redundant communication unit to the third normal communication unit. Device switching method.

8. A program for causing a computer to function as the optical communication device according to claim 6.

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