Link-up control method, station-side equipment and OLT

Abstract

To allow a link-up process to be performed during OLT firmware update.SOLUTION: A link-up control method for controlling link-up of a home-side device by a station-side device having a plurality of OLTs includes the steps of: determining a first OLT of the plurality of OLTs as an alternate destination for link-up processing for link-up of the home-side device under a second OLT by the second OLT that can communicate with the first OLT of the plurality of OLTs and is scheduled for firmware update; configuring the first OLT so as to be able to replace the link-up processing of the second OLT; updating firmware by the second OLT; and after the firmware update, returning the entity performing the link-up processing from the first OLT to the second OLT.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to a link-up control method, a central office device, and an OLT.

Background Art

[0002] One form of realizing FTTH (Fiber To The Home) that provides network access services to each home by optical fiber is PON (Passive Optical Network). The feature of PON is that it can provide optical access services at low cost by sharing a part of the optical fiber connecting the optical network termination device (ONU (Optical Network Unit)) provided on the customer side and the optical line terminal device (OLT (Optical Line Terminal)) provided on the central office side for communication.

[0003] In a network system including FTTH, there is often a need for functions to add new functions and improve problems. As a method for realizing such functions, there is a method of updating the firmware executed by the CPU (Central Processing Unit) in the network device. In this specification, "firmware" shall include the program code executed by the CPU inside the communication device (regardless of OLT or ONU).

[0004] While the firmware of the OLT is being updated, the processing of the OLT may stop. To solve this problem, for example, Japanese Patent Application Laid-Open No. 2014-78784 (Patent Document 1) proposes to configure the OLT with an upper processing unit and a lower processing unit. According to this configuration, while the firmware of the upper processing unit is being updated, the communication between the OLT and the ONU can be maintained by the lower processing unit.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In the configuration proposed in Japanese Patent Publication No. 2014-78784, while the firmware of the OLT's higher-level processing unit is being updated, that higher-level processing unit cannot perform the process for linking up the ONU. However, Japanese Patent Publication No. 2014-78784 does not describe this problem, and therefore does not provide a solution to it.

[0007] The purpose of this disclosure is to provide a technology that enables link-up processing to be performed during firmware updates of an OLT. [Means for solving the problem]

[0008] The link-up control method of this disclosure is a link-up control method for controlling the link-up of a customer-side device by a central office device having a plurality of OLTs, comprising the steps of: determining a first OLT among the plurality of OLTs as an alternative destination for link-up processing for the home-side device under the second OLT, which is able to communicate with the first OLT among the plurality of OLTs and is scheduled to have its firmware updated; configuring the first OLT so that it can substitute for the link-up processing of the second OLT; the second OLT updating its firmware; and after the firmware update, returning the main body for executing the link-up processing from the first OLT to the second OLT.

[0009] The central office equipment of this disclosure comprises a plurality of OLTs, the plurality of OLTs including a first OLT and a second OLT that is communicably connected to the first OLT, the second OLT having firmware, and when the second OLT is scheduled to receive a firmware update, the first OLT is determined to be the alternative destination for the link-up processing performed by the second OLT for link-up of the home-side equipment under the second OLT, the first OLT can take over the link-up processing by taking over the settings for the link-up processing performed by the second OLT from the second OLT, and when the second OLT updates its firmware, the responsibility for executing the link-up processing is returned from the first OLT to the second OLT.

[0010] The OLT of this disclosure comprises a higher-level processing unit having firmware, and a lower-level processing unit that can communicate with the higher-level processing unit and other OLTs, and is responsible for communication with the customer-side device. When there is a plan to update the firmware of the higher-level processing unit, the higher-level processing unit has the link-up processing for linking up the customer-side device delegated to another OLT through the lower-level processing unit, and after the firmware update, the responsibility for executing the link-up processing is returned from the other OLT to the higher-level processing unit. [Effects of the Invention]

[0011] According to this disclosure, a link-up process can be performed while the OLT firmware is being updated. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a PON system according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a functional block diagram of the upper-level processing unit 111 shown in Figure 1. [Figure 3] Figure 3 is a sequence diagram illustrating potential challenges that may arise when performing link-up processing during a non-interrupted firmware update. [Figure 4] Figure 4 is a sequence diagram illustrating the link-up process during uninterrupted firmware update according to an embodiment of the present disclosure. [Figure 5] Figure 5 is a diagram illustrating the flow of the link-up process under normal circumstances. [Figure 6] Figure 6 is a diagram illustrating a link-up control method that enables both firmware updates and link-up processing. [Figure 7] Figure 7 is a sequence diagram illustrating the overall flow of the link-up process according to this embodiment. [Figure 8] Figure 8 is a sequence diagram illustrating an example of the link-up process. [Figure 9] Figure 9 is a diagram illustrating the information transmitted via the communication settings unit. [Figure 10] Figure 10 shows an example of the frame format exchanged between the communication processing unit and the ONU. [Modes for carrying out the invention]

[0013] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described.

[0014] (1) A link-up control method according to one embodiment of the present disclosure is a link-up control method for controlling the link-up of a customer-side device by a central office device having a plurality of OLTs, comprising the steps of: determining a first OLT among the plurality of OLTs as an alternative destination for link-up processing for the link-up of a customer-side device under the second OLT, which is able to communicate with the first OLT among the plurality of OLTs and is scheduled to have its firmware updated; configuring the first OLT so that it can substitute for the link-up processing of the second OLT; the second OLT updating its firmware; and after the firmware update, returning the main body for executing the link-up processing from the first OLT to the second OLT.

[0015] According to this configuration, while the second OLT is updating the firmware, the first OLT can execute the link-up process for the home-side devices under the second OLT in place of the second OLT. Therefore, the link-up process can be executed during the firmware update of the second OLT. Note that the terms "first" and "second" are terms arbitrarily assigned for the sake of convenience to the OLT that is the replacement for the link-up process and the OLT scheduled to update the firmware.

[0016] (2) In the link-up control method of (1) above, while the first OLT is the replacement for the link-up process of the second OLT, the first OLT further includes a step of determining, for the home-side device to be the target of the link-up process, whether the home-side device is under the control of the first OLT or the second OLT.

[0017] According to the above configuration, while the first OLT is the replacement for the link-up process of the second OLT, the first OLT needs to handle both the link-up of the ONUs under the first OLT and the link-up of the ONUs under the second OLT. By determining whether the ONU to be the target of the link-up process is a home-side device under the control of the first OLT or the second OLT, the link-up can be executed normally.

[0018] (3) In the link-up control method of (2) above, the step of setting the first OLT includes setting the notification path to transfer the link-up notification sent from the home-side device to be the target of the link-up process to the second OLT to the first OLT. The determining step includes the step of the first OLT determining that the home-side device to be the target of the link-up process is a home-side device under the control of the second OLT based on the information included in the link-up notification when the first OLT receives the link-up notification from the second OLT.

[0019] According to the above configuration, the first OLT can determine whether the ONU to be the target of the link-up process is a home-side device under the control of the first OLT or the second OLT.

[0020] (4) A central office device according to one embodiment of the present disclosure comprises a plurality of OLTs, the plurality of OLTs including a first OLT and a second OLT that is communicatively connected to the first OLT, the second OLT having firmware, and when the second OLT is scheduled to have a firmware update, the first OLT is determined to be the alternative destination for the link-up processing performed by the second OLT for link-up of the home-side devices under the second OLT, the first OLT can take over the link-up processing by taking over the settings for the link-up processing performed by the second OLT from the second OLT, and when the second OLT updates its firmware, the responsibility for executing the link-up processing is returned from the first OLT to the second OLT.

[0021] With this configuration, while the second OLT is updating its firmware, the first OLT can take over from the second OLT and perform the link-up process for the home-side devices under the second OLT.

[0022] (5) In the central office equipment described in (4) above, each of the first OLT and the second OLT has a higher-level processing unit and a lower-level processing unit that can communicate with the higher-level processing unit and is responsible for communication with the home-side equipment, and the lower-level processing unit of the first OLT and the lower-level processing unit of the second OLT are connected to each other so as to be able to communicate with each other, and when there is a planned firmware update for the higher-level processing unit of the second OLT, the higher-level processing unit of the first OLT is configured to be able to substitute the link-up processing by receiving the settings for link-up processing from the second OLT.

[0023] In this configuration, when the firmware of the upper-level processing unit of the second OLT is updated, the upper-level processing unit of the first OLT can receive the settings for link-up processing by the second OLT via the lower-level processing unit of the second OLT and the lower-level processing unit of the first OLT. As a result, the upper-level processing unit of the first OLT can perform the link-up processing for the ONU under the second OLT on behalf of the upper-level processing unit of the second OLT.

[0024] (6) In the central office equipment described in (5) above, if the higher-level processing unit of the first OLT receives a link-up notification from the lower-level processing unit of the first OLT while the first OLT is acting as an alternative destination for the link-up processing of the second OLT, the higher-level processing unit of the first OLT determines, based on the information contained in the link-up notification, which of the first OLT or the second OLT the customer-side equipment subject to the link-up processing is under the control of.

[0025] According to the above configuration, the higher-level processing unit of the first OLT determines whether the ONU targeted for link-up processing is a customer-side device under either the first OLT or the second OLT. This enables the link-up process to be executed successfully.

[0026] (7) In the central office equipment described in (5) or (6) above, the lower processing unit of the second OLT sets up a link-up notification transfer path so that when the first OLT is able to take over the link-up processing, the link-up notification for the home-side equipment under the second OLT is transferred to the higher processing unit of the first OLT.

[0027] In this configuration, the lower-level processing unit of the second OLT forwards notifications regarding the link-up of the ONU under the second OLT to the higher-level processing unit of the first OLT, instead of the higher-level processing unit of the second OLT. As a result, the higher-level processing unit of the first OLT can perform the link-up processing for the ONU under the second OLT, instead of the higher-level processing unit of the second OLT.

[0028] (8) An OLT according to one embodiment of the present disclosure comprises a higher-level processing unit having firmware, and a lower-level processing unit that can communicate with the higher-level processing unit and other OLTs and is responsible for communication with the home-side device, wherein if there is a plan to update the firmware of the higher-level processing unit, the higher-level processing unit will have the link-up processing for linking up the home-side device be replaced by another OLT through the lower-level processing unit, and after the firmware update, the responsibility for executing the link-up processing will be returned from the other OLT to the higher-level processing unit.

[0029] This configuration allows for the provision of an OLT that can have another OLT take over the link-up processing of its subordinate customer devices while the firmware is being updated.

[0030] [Details of the embodiments of this disclosure] Embodiments of this disclosure will be described below with reference to the drawings. In the drawings, identical or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0031] In the description of embodiments of this disclosure, "link-up processing" means processing performed by the OLT to establish a logical link between the ONU and the OLT. In embodiments of this disclosure, "link-up processing" is not limited to link-up, but may also include processing such as authentication processing and health verification.

[0032] Figure 1 is a schematic diagram showing the configuration of a PON system according to one embodiment of the present disclosure. As shown in Figure 1, the PON system 10 includes a central office device 100. The central office device 100 is, for example, a termination device installed at a telecommunications carrier's relay station. Although not explicitly shown in Figure 1, the central office device 100 is connected to a higher-level network.

[0033] In embodiments of this disclosure, the central office equipment 100 includes a plurality of OLTs. As shown in Figure 1, the plurality of OLTs include OLTs 101 and 102. In embodiments of this disclosure, the form of the OLTs is not particularly limited. For example, according to one embodiment of this disclosure, OLTs 101 and 102 are small, general-purpose modules. According to such an embodiment, for example, each of OLTs 101 and 102 may be implemented in the form of a line unit housed in a housing. Alternatively, each of OLTs 101 and 102 may be implemented in the form of a line card.

[0034] For illustrative purposes, Figure 1 shows the number of OLTs (Optical Lighting Terminals) in the central office equipment 100 as 2. However, the central office equipment 100 is only required to be configured to have multiple OLTs. Therefore, the central office equipment 100 may have three or more OLTs.

[0035] Each of the OLTs, OLT101 and OLT102, is connected to an ONU via an optical fiber line. In a PON system, a single optical fiber line from the OLT is split by an optical splitter into multiple lines connected to each ONU. In the configuration shown in Figure 1, OLT101 is connected to M ONUs (ONU211~21M) via optical fiber line 11, and OLT102 is connected to N ONUs (ONU221~22N) via optical fiber line 12. Here, M and N represent any integers greater than or equal to 1. M and N may be different numbers or the same number. Each of the ONUs 211~21M is connected to OLT101 via optical fiber line 11, so they can be called "ONUs under OLT101". Similarly, each of the ONUs 221~22N is connected to OLT102 via optical fiber line 12, so they can be called "ONUs under OLT102".

[0036] OLT101 and OLT102 are connected to each other in a way that allows them to communicate with one another. This enables OLT101 and OLT102 to send and receive control signals to each other.

[0037] Each OLT includes an upper-level processing unit and a lower-level processing unit. The upper-level processing unit has firmware and manages the upper layers of the layered communication protocol. The lower-level processing unit is controlled by the upper-level processing unit and manages the lower layers of the layered communication protocol. A "layered communication protocol" is, for example, a communication protocol that follows the OSI (Open Systems Interconnection) reference model. In this case, the "upper layer" is, for example, the fourth layer (transport layer) and the layers above it, and the "lower layer" is, for example, the first layer (physical layer), the second layer (data link layer), and the third layer (network layer) of the OSI reference model. Note that the data link layer protocol includes, but is not limited to, the MPCP (Multi-Point Control Protocol) and OAM (Operations, Administration and Maintenance) protocols.

[0038] The lower-level processing unit is capable of communicating with the higher-level processing unit and is responsible for communication with the ONU. The lower-level processing unit is configured to continue communication with the ONU even if some or all of the processing of the higher-level processing unit is temporarily suspended.

[0039] Specifically, the OLT101 includes an upper-level processing unit 111 and a lower-level processing unit 112. The lower-level processing unit 112 includes a PON interface (I / F) unit 113, a communication processing unit 114, and an upper-level interface (I / F) unit 115.

[0040] The PON interface unit 113 is connected to the optical line 11 (optical fiber) and converts the optical signal (upstream signal) received from the optical line 11 into an electrical signal. On the other hand, the PON interface unit 113 converts the downstream signal, which is an electrical signal input from the communication processing unit 114, into an optical signal and sends that optical signal to the optical line 11.

[0041] The communication processing unit 114 communicates with the higher-level processing unit 111. The protocol used for communication between the higher-level processing unit 111 and the communication processing unit 114 is, for example, TCP / IP. When the communication processing unit 114 determines that an uplink signal transmitted from one of the ONUs under OLT 101, i.e., one of the ONUs 211 to 21N, is a data signal, it performs various processes to transmit the data signal from OLT 101 to the higher-level network (not shown). On the other hand, the communication processing unit 114 performs various processes to transmit downlink signals (data signals) sent from the higher-level network to OLT 101 to the ONUs under OLT 101 via the optical line 11.

[0042] Furthermore, when a control frame is transmitted to the OLT 101, the communication processing unit 114 forwards the control frame to the higher-level processing unit 111. Also, when the OLT 101 should transmit a control frame to the ONU, the communication processing unit 114 receives the control frame to be sent to the ONU from the higher-level processing unit 111 and executes processing to send the control frame to the optical line 11.

[0043] The OLT102 includes an upper-level processing unit 121 and a lower-level processing unit 122. The lower-level processing unit 122 includes a PON interface (I / F) unit 123, a communication processing unit 124, and an upper-level interface (I / F) unit 125. The functions of the upper-level processing unit 121 and the lower-level processing unit 122 are the same as those of the upper-level processing unit 111 and the lower-level processing unit 112 described above. Also, the functions of the PON interface unit 123, the communication processing unit 124, and the upper-level interface unit 125 in the lower-level processing unit 122 are the same as those of the PON interface unit 113, the communication processing unit 114, and the upper-level interface unit 115 described above. Therefore, a detailed explanation of the functions of the upper-level processing unit 121 and the lower-level processing unit 122 of the OLT102 will not be repeated below.

[0044] The lower-level processing unit 112 of OLT101 and the lower-level processing unit 122 of OLT102 are connected to each other in a way that allows them to communicate with one another. For example, the control ports of the lower-level processing units 112 and 122 are connected to each other. This allows control signals to be sent and received between OLT101 and OLT102.

[0045] Figure 2 is a functional block diagram of the higher-level processing unit 111 shown in Figure 1. Since the functional blocks of the higher-level processing unit 121 are the same as those of the higher-level processing unit 111, the functional blocks of the higher-level processing unit 111 will be described as representative below.

[0046] As shown in Figure 2, the higher-level processing unit 111 includes an update unit 131, a storage unit 132, and a control unit 133. The update unit 131 updates the firmware held by the higher-level processing unit 111 to new firmware. Specifically, the update unit 131 obtains new firmware from outside the OLT 101. The new firmware is provided to the OLT 101, for example, via a network. The update unit 131 temporarily stores the new firmware in the storage unit 132. Next, the update unit 131 reads the new firmware from the storage unit 132, for example, according to instructions from an operator, and updates the current firmware to the new firmware.

[0047] The memory unit 132 stores various types of information necessary for the processing performed by the higher-level processing unit 111. For example, the memory unit 132 stores information related to the settings of the OLT 101.

[0048] The control unit 133 performs various processes based on information stored in the memory unit 132 or information sent from the lower-level processing unit 112. For example, the control unit 133 performs link-up processing for linking up the ONU. If the firmware is updated, the control unit 133 configures settings related to updating the functions of the lower-level processing unit 112.

[0049] The firmware of the higher-level processing unit may be updated to a new firmware for purposes such as adding new functions to the OLT or fixing operational problems with the OLT. During the firmware update, all or some functions of the higher-level processing unit cannot be executed. By configuring the OLT with a higher-level processing unit and a lower-level processing unit, the lower-level processing unit can continue communication with the ONU even during the firmware update period of the higher-level processing unit. This prevents interruptions in data communication caused by the firmware update. Updating the firmware of the higher-level processing unit while maintaining communication by the lower-level processing unit will be referred to as "uninterrupted firmware update" below.

[0050] Figure 3 is a sequence diagram illustrating potential issues that may arise when performing link-up processing during a non-interrupted firmware update. As shown in Figure 3, when the OLT is started up, the initialization of the higher-level processing unit is performed (step S1). Next, the higher-level processing unit configures communication with the lower-level processing unit (step S2). As a result, the lower-level processing unit becomes capable of communicating with the higher-level processing unit and the ONU under the OLT.

[0051] Next, the firmware of the higher-level processing unit (labeled "FW" in Figure 2) is updated (step S3). Meanwhile, suppose the ONU needs to be linked up. However, while the higher-level processing unit is updating its firmware, it cannot perform the link-up process.

[0052] After the firmware update, the higher-level processing unit is restarted (step S4). During the restart of the higher-level processing unit, it cannot perform the link-up process. After the restart, the higher-level processing unit is initialized, and its functions are updated (step S5). After the restart, the higher-level processing unit can perform the link-up process.

[0053] Thus, in an OLT with a scheduled firmware update, there is a possibility that the link-up process cannot be performed at least from the start of the firmware update until the restart is completed. The embodiments of this disclosure solve this problem.

[0054] Figure 4 is a sequence diagram schematically illustrating the link-up process during uninterrupted firmware update according to an embodiment of the present disclosure. The "higher-level processing unit 1" shown in Figure 3 is one of the higher-level processing units (higher-level processing units 111 and 121) of OLT 101 and 102, respectively, and the "higher-level processing unit 2" is the other of the higher-level processing units 111 and 121. For example, the "higher-level processing unit 1" is the higher-level processing unit 111, and the "higher-level processing unit 2" is the higher-level processing unit 121. In this case, the "lower-level processing unit 1" shown in Figure 3 is the lower-level processing unit 112 of OLT 101.

[0055] Similar to the sequence shown in Figure 3, first, OLTs 101 and 102 are activated, and the initialization of the higher-level processing units 111 and 121 is performed (steps S1 and S1A). Next, the higher-level processing units 111 and 121 configure communication settings for their respective lower-level processing units (steps S2 and S2A).

[0056] During the firmware update in the higher-level processing unit 111 (step S3), and during the restart of the higher-level processing unit 111 after the firmware update (step S4), the higher-level processing unit 111 cannot perform the link-up process for the ONU under the OLT 101. However, in this case, the higher-level processing unit 121 takes over the link-up process performed by the higher-level processing unit 111. This enables the link-up of the ONU under the OLT 101.

[0057] Furthermore, after the initialization of the upper-level processing unit 111, the upper-level processing unit 111 can perform link-up processing through the lower-level processing unit 112 (step S5).

[0058] In this embodiment, two OLTs, which basically operate as independent OLTs, coordinate their respective higher-level processing units during firmware updates. If the firmware of one higher-level processing unit is being updated, the other higher-level processing unit takes over the link-up processing performed by that unit. This not only enables uninterrupted firmware updates but also allows link-up processing to be performed even during firmware updates.

[0059] Next, we will explain the link-up process by the OLT in detail. Figure 5 is a diagram illustrating the flow of the link-up process under normal circumstances. "Normal circumstances" refers to the case where there are no firmware updates. Link-up events occur, for example, when the ONU makes its initial connection to the optical line, or when the ONU is restarted.

[0060] Assume a link-up event occurs in an ONU under OLT101. In this case, the ONU transmits a link-up signal to OLT101 via the optical line 11. The link-up signal is received by the lower-level processing unit 112.

[0061] In the lower-level processing unit 112, the communication processing unit 114 receives a link-up signal via the PON interface unit 113 and forwards a link-up notification to the higher-level processing unit 111. Upon receiving the link-up notification from the lower-level processing unit 112, the higher-level processing unit 111 refers to the configuration information 134 and executes the link-up process for the ONU to link up.

[0062] The configuration information 134 is stored inside the OLT 101 (for example, in the memory unit 132 shown in Figure 2). The configuration information 134 may include information regarding communication settings between the OLT 101 and the ONU under its control.

[0063] Similarly, when a link-up event occurs in an ONU under OLT102, the ONU transmits a link-up signal to the optical line 12. In this case, the link-up signal is received by the lower-level processing unit 122 of OLT102. Upon receiving the link-up signal, the communication processing unit 124 sends a link-up notification to the higher-level processing unit 121. Upon receiving the link-up notification, the higher-level processing unit 121 refers to the configuration information 144 and executes the link-up process.

[0064] Figure 6 illustrates a link-up control method that balances firmware updates and link-up processing. In the example shown in Figure 6, the firmware of the higher-level processing unit 121 of OLT102 is updated. In this case, OLT101 is determined to be the alternative destination for the link-up processing performed by OLT102. Furthermore, OLT101 is configured to be able to substitute for the link-up processing of OLT102.

[0065] Specifically, if there is a planned firmware update, the higher-level processing unit 121 copies the configuration information 144 from OLT102 to OLT101. The configuration information 144A stored inside OLT101 is a copy of the configuration information 144 and is transferred to OLT101 via the link between OLT101 and OLT102.

[0066] Furthermore, the higher-level processing unit 121 sends a control signal to the communication processing unit 124 to change the settings of the communication processing unit 124. Similarly, the higher-level processing unit 121 sends a control signal to the communication processing unit 114 via the communication processing unit 124. As a result, when the communication processing unit 124 receives a link-up signal from the ONU under the OLT 101, the communication processing unit 124 forwards a link-up notification to the communication processing unit 114. The communication processing unit 114 forwards the link-up notification to the higher-level processing unit 111. When the higher-level processing unit 111 receives the link-up notification, it forwards a control signal for configuring the communication processing unit 124 to the communication processing unit 124 via the communication processing unit 114. For example, the higher-level processing units 111 and 121 send and receive control signals to and from the communication processing unit via their respective control ports (labeled "Port1" in Figure 6), and the communication processing units 114 and 124 send and receive control signals to and from each other via their respective communication ports (labeled "Port2" in Figure 6).

[0067] When the higher-level processing unit 111 receives a firmware update completion notification from OLT102, it forwards the latest information regarding the status of the ONU managed by OLT102 to OLT102. Furthermore, the higher-level processing unit 111 modifies the settings of the communication processing unit 124 so that link-up signals from the ONUs under OLT102 are not forwarded to OLT101. As a result, after the firmware update of OLT102, the responsibility for executing the link-up process is returned from OLT101 to OLT102.

[0068] According to the control method shown in Figure 6, OLT101 is designated as the alternative destination for the link-up process for the ONU under OLT102, which is capable of communicating with OLT101 and is scheduled for a firmware update. Then, OLT101 is configured to be able to take over OLT102's link-up process. When OLT102 updates its firmware, the responsibility for executing the link-up process is returned from OLT101 to OLT102 after the update. This makes it possible to reconcile the firmware update of OLT102 with the link-up process.

[0069] Firmware updates and ONU link-up are independent events. While an OLT firmware update is definitely scheduled, it may be unclear whether a link-up process will be necessary at the start of the firmware update. In this embodiment, even in such cases, the other OLT can be designated as an alternative for the link-up process, thereby enabling the link-up process during the firmware update. In other words, in this embodiment, if one OLT has a scheduled firmware update, it is sufficient that the other OLT is configured to be able to take over the link-up process; it is not necessarily required that both the firmware update and the link-up process be executed simultaneously.

[0070] Figure 7 is a sequence diagram illustrating the overall flow of the link-up process according to this embodiment. Similar to Figure 6, Figure 7 shows the process flow when the firmware of OLT102 is updated and OLT101 takes over the link-up process of OLT102.

[0071] First, the firmware (FW) update of the higher-level processing unit 121 is initiated (step S11). The higher-level processing unit 121 refers to its own configuration information 144 (step S12). The higher-level processing unit 121 copies the configuration information 144 to the higher-level processing unit 111 (step S13). As a result, the configuration information 144A, which is a copy of the configuration information 144, is transferred to the higher-level processing unit 111 via the communication processing unit 124 and the communication processing unit 114.

[0072] In this way, the higher-level processing unit 111 is configured to be able to substitute for the link-up processing of OLT102 by receiving settings for link-up processing from OLT102.

[0073] Next, the higher-level processing unit 121 modifies the link-up notification route to the communication processing unit 124 and the communication processing unit 114 (steps S14, S15). This modifies the route so that the link-up notification from the communication processing unit 124 is forwarded to the communication processing unit 114.

[0074] The ONU under OLT102 transmits a link-up signal (step S16). When the communication processing unit 124 receives the link-up signal from the ONU, it generates a link-up notification based on the link-up signal. The communication processing unit 124 transmits the link-up notification to the communication processing unit 114. The link-up notification is forwarded from the communication processing unit 114 to the higher-level processing unit 111 (step S17). This allows the higher-level processing unit 111 to perform the link-up processing for the ONU under OLT102 on behalf of the higher-level processing unit 121.

[0075] A link-up notification includes information identifying the ONU being linked up and information identifying the OLT to which the link-up signal is sent. While not limited to the items listed below, a link-up notification may also include, for example, the OLT's MAC (Media Access Control) address (OLTMAC), port number (Port No.), the ONU's MAC address, and the message type (see Figure 10). An example of information included in a link-up notification is shown below.

[0076] OLTMAC=AA:BB:CC:DD:EE:FF Port No=1 ONUMAC=00:11:22:33:44:55 Message type: Linkup Of the information above, "Port No=1" refers to the designation of "Port1," the control port of the higher-level processing unit shown in Figure 6.

[0077] While OLT101 acts as an alternative for OLT102's link-up processing, the higher-level processing unit 111 is responsible for processing the link-up of ONUs under OLT102, in addition to the link-up of ONUs under OLT101. Therefore, based on the link-up notification forwarded from the communication processing unit 114, the higher-level processing unit 111 determines which of OLT101 or OLT102 the ONU subject to link-up processing is under.

[0078] The higher-level processing unit 111 refers to the OLTMAC of the link-up notification received from the communication processing unit 124. The OLTMAC corresponds to an identifier for identifying the OLT. Based on the OLTMAC included in the link-up notification, the higher-level processing unit 111 can determine whether the link-up notification received from the communication processing unit 114 is a notification addressed to OLT 101 or OLT 102.

[0079] In the example shown in Figure 7, the higher-level processing unit 111 receives a link-up notification addressed to the OLT 102. In this case, the higher-level processing unit 111 refers to the configuration information 144A to obtain information for linking up the ONU under the OLT 102. The higher-level processing unit 111 then configures the communication settings of the communication processing unit 124 and the ONU according to this information (steps S19, S20). As a result, the communication processing unit 124 and the ONU that sent the link-up signal become ready for communication configuration by the higher-level processing unit 111. Therefore, the higher-level processing unit 111 executes the link-up process for the ONU.

[0080] The firmware update in the higher-level processing unit 121 is completed (step S21). The higher-level processing unit 121 sends control signals to the communication processing unit 124 and the communication processing unit 114 to change the link-up notification path (steps S21, S22). In this case, the link-up notification path is restored so that the link-up notification from the communication processing unit 124 is forwarded from the communication processing unit 124 to the higher-level processing unit 121. As a result, the execution authority for the link-up process of the ONU under the OLT 102 is returned from OLT 101 to OLT 102.

[0081] Next, the higher-level processing unit 121 requests the higher-level processing unit 111 to delete the configuration information 144A (step S23). In response to the request, the higher-level processing unit 111 deletes the configuration information 144A (step S24). This completes the series of processes.

[0082] The same process is performed when OLT102 takes over the link-up processing of OLT101. When OLT102 takes over the link-up processing of OLT101, simply swap "OLT101" (higher-level processing unit 111, communication processing unit 114) and "OLT102" (higher-level processing unit 121, communication processing unit 124) in the following explanation.

[0083] In this embodiment, the link-up process is not limited to a specific process. Figure 8 is a sequence diagram illustrating an example of the link-up process. Although not limiting to this embodiment, Figure 8 shows, as an example, a link-up process that conforms to IEEE 802.3av,ah. Furthermore, the sequence diagram in Figure 8 shows both cases without distinction: when the higher-level processing units (111,121) of each OLT perform the link-up process for the ONU under its control, and when one of the two OLTs substitutes for the link-up process of the other.

[0084] First, a link-up is performed using MPCP (Multi-point Control Protocol) to control communication between the lower-level processing units (112, 122) and the ONU (step S31). The OLT establishes a link with the new ONU according to the MPCP. Furthermore, a link-up is performed between the lower-level processing unit and the ONU using OAM (Operation Administration and Maintenance) (step S32).

[0085] Next, the lower-level processing unit sends a link-up notification to the higher-level processing unit (step S33). An example of the content of the link-up notification is shown below.

[0086] OLTMAC=AA:BB:CC:DD:EE:FF Port No=1 ONUMAC=00:11:22:33:44:55 Message type: Linkup When the higher-level processing unit receives a link-up notification, it refers to the configuration information (134, 144, or 144A) (step S34). The configuration information 144 includes, for example, the MAC address of the ONU (ONU MAC), the ports to which the ONU belongs, the ONU number, the VLANs to which it belongs, and the number of UNI (User Network Interface) ports. However, the information included in the configuration information 144 is not limited to these.

[0087] The upper-level processing unit 121 configures the lower-level processing unit 122 according to the configuration information (step S35). Once the OLT communication configuration is complete, the lower-level processing unit becomes ready for communication.

[0088] Next, the higher-level processing unit configures the ONU's communication settings (step S36). Once the ONU's communication settings are complete, the ONU becomes ready for communication. During the ONU's communication settings, proprietary messages are exchanged between the OLT and the ONU. Through message conversion in the lower-level processing unit, messages are exchanged between the ONU and the OLT according to OAM, for example, compliant with IEEE802.3av,ah. An example of the messages exchanged during the ONU's communication settings is shown below.

[0089] (1) Message before conversion: OLTMAC=AA:BB:CC:DD:EE:FF Port No=1 ONUMAC=00:11:22:33:44:55 Message type: ONU communication settings Subcategory: ONU Queue Settings (2) Translated message (IEEE 802.3av, ah compliant OAM) Dest MAC=01:80:c2:00:00:02 Src MAC = AA:BB:CC:DD:EE:FF (i.e., OLT MAC) ethType = OAM Type = 0xFE (vendor specific) OUI = 0xXXXXXX Message type: ONU communication settings Subcategory: ONU routing settings Figure 9 is a diagram illustrating the information transmitted via the communication configuration unit. Referring to Figure 9, the link-up signal transmitted from the ONU is input to the PON interface unit 123. If the firmware is not being updated in the higher-level processing unit 121 (i.e., under normal circumstances), the communication processing unit 124 sends a link-up notification to the higher-level processing unit 121. In this case, the communication processing unit 124 only needs to identify the ONU that sent the message from the LLID (Logical Link ID) contained in the received message and notify the higher-level processing unit 121. Alternatively, the communication processing unit 124 may simply notify the higher-level processing unit 121 via the bus that link processing is required.

[0090] On the other hand, if the firmware is being updated in the higher-level processing unit 121, the communication processing unit 124 forwards the link-up notification to the OLT 101 (not shown in Figure 9). In this case, the communication processing unit 124 may store the link-up notification in a frame and forward that frame to the OLT 101. The frame in which the link-up notification is stored is preferably a frame used in Layer 2 (L2) communication or Layer 3 (L3) communication, for example.

[0091] The communication processing unit 124 can determine, based on the message type, whether a message received by the communication processing unit 124 is a message for OLT communication settings or a message for ONU communication settings. If the message received by the communication processing unit 124 is a message for OLT communication settings, the communication processing unit 124 processes the message. If the message received by the communication processing unit 124 is a message for ONU communication settings, it sets up communication to the ONU using a dedicated frame format. In this case, the communication processing unit 124 is responsible for converting the control signal sent by the higher-level processing unit 121 into a dedicated frame format for the ONU.

[0092] Figure 10 shows an example of the frame format exchanged between the communication processing unit and the ONU. As shown in Figure 10, the frame includes a destination address (DA) field, a source address (SA) field, a VLAN (Virtual LAN) field, a type field, a data field, and an FCS (Frame Check Sequence) field. Note that the preamble is not shown in Figure 10.

[0093] The destination address field and source address field store the MAC address of the destination node and the MAC address of the source node, respectively.

[0094] The VLAN field is used to specify the tag header for VLAN tags. For example, if OLT102 is the source, the VLAN ID is set to 10, and if the ONU is port number 1 (Port1), the VLAN ID is set to 1001. In this case, OLT101 has a correspondence table that associates VLANs with their sources.

[0095] The type field stores the vendor-specific code 0xFE. The data field stores various information such as the message type, information to identify the ONU (LLID, MAC address, link management information), and the status of the ONU.

[0096] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and all modifications within the meaning and scope of the claims are intended to be included. [Explanation of Symbols]

[0097] 10 PON System 11,12 Fiber optic internet 100 Station side equipment 101,102 OLT 111,121 Upper processing unit 112,122 Lower processing units 113,123 PON Interface Section 114,124 Communication Processing Unit 115,125 Upper Interface Section 131 Update Department 132 Storage section 133 Control Unit 134,144,144A Configuration Information 211~21M, 221~22N ONU Steps S1-S5, S1A, S2A, S11-S24, S31-S36

Claims

1. A link-up control method that controls the link-up of a customer-side device using a central office-side device having multiple OLTs, The steps include determining a first OLT among the plurality of OLTs as an alternative destination for the link-up process for the home-side device under the second OLT, which is capable of communicating with the first OLT and has a firmware update scheduled, The steps include setting the first OLT so that it can substitute for the link-up process of the second OLT, The second OLT updates the firmware, A link-up control method comprising the step of, after the firmware update, returning the main body of execution of the link-up process from the first OLT to the second OLT.

2. The link-up control method according to claim 1, further comprising the step of determining, by the first OLT, which of the first OLT and the second OLT the home-side device subject to the link-up processing is under the control of, while the first OLT is the alternative destination for the link-up processing of the second OLT.

3. The step of setting the first OLT is: The step includes setting up a notification path to forward the link-up notification sent from the home-side device subject to the link-up process to the second OLT to the first OLT, The link-up control method according to claim 2, wherein the determination step includes, when the first OLT receives the link-up notification from the second OLT, determining, based on the information contained in the link-up notification, that the home-side device subject to the link-up process is a home-side device under the control of the second OLT.

4. It is a station-side device, It comprises multiple OLTs, and the multiple OLTs are, The first OLT and It includes a second OLT that is communicatively connected to the first OLT, the second OLT having firmware, If the second OLT has a firmware update scheduled, the first OLT is determined to be an alternative destination for the link-up process performed by the second OLT for linking up the home-side devices under its control. The first OLT can take over the link-up process by inheriting the settings for the link-up process performed by the second OLT from the second OLT. When the second OLT updates the firmware, the primary responsibility for executing the link-up process is returned from the first OLT to the second OLT, according to the station-side equipment.

5. Each of the first OLT and the second OLT is, Higher processing unit and It has a lower-level processing unit that can communicate with the aforementioned higher-level processing unit and is responsible for communication with the home-side device, The lower processing unit of the first OLT and the lower processing unit of the second OLT are connected to each other so as to be able to communicate with each other. The station-side device according to claim 4, wherein, when the higher-level processing unit of the second OLT has a scheduled firmware update, the higher-level processing unit of the first OLT is configured to be able to substitute the link-up processing by receiving the settings for the link-up processing from the second OLT.

6. The central office device according to claim 5, wherein, while the first OLT is the alternative destination for the link-up processing of the second OLT, the higher-level processing unit of the first OLT receives a link-up notification from the lower-level processing unit of the first OLT, the higher-level processing unit of the first OLT determines, based on the information contained in the link-up notification, whether the home-side device subject to the link-up processing is under the control of the first OLT or the second OLT.

7. The station-side device according to claim 5 or 6, wherein the lower-level processing unit of the second OLT sets a link-up notification transfer path so that when the first OLT is capable of performing the link-up processing, the link-up notification for the home-side device under the control of the second OLT is transferred to the higher-level processing unit of the first OLT.

8. It is OLT, A higher-level processing unit having firmware, The system comprises the above-mentioned higher-level processing unit and a lower-level processing unit that can communicate with the OLT and other OLTs in the central office-side device having other OLTs, and is responsible for communication with the home-side device. If the firmware of the higher-level processing unit is scheduled to be updated, the higher-level processing unit determines the other OLT to be the alternative destination for the link-up process for linking up the home-side devices under the OLT, transfers the settings for the link-up process to the other OLT through the lower-level processing unit, has the other OLT take over the link-up process through the lower-level processing unit, and after the firmware update, returns the execution of the link-up process from the other OLT back to the higher-level processing unit.

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