JP2012142698A - Station side device, communication system and communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a station side device which can provide a highly reliable communication system by shortening the communication stop time between the station side device and a home side device upon occurrence of an event having an impact on transmission of a communication signal, e.g. redundant switching, and to provide a communication system and a communication control method.SOLUTION: A station side device 201 communicates with one or a plurality of home side devices 202. The station side device 201 comprises: an event control unit 36 which detects an event having an impact on transmission of a communication signal to the home side devices 202, and performs processing for the event; and an abnormality detection unit 36 which transmits stop control information indicating stoppage of abnormality detection of the communication signal to the home side devices 202 before occurrence of the event detected by the event control unit 36.

Description

  The present invention relates to a station-side device, a communication system, and a communication control method, and more particularly, to a station-side device that deals with the occurrence of an event that affects transmission of a communication signal, a communication system including the station-side device, and a communication control method. .

  In recent years, the Internet has become widespread, and users can access various information on sites operated in various parts of the world and obtain the information. Along with this, devices capable of broadband access such as ADSL (Asymmetric Digital Subscriber Line) and FTTH (Fiber To The Home) are rapidly spreading.

  In IEEE Std 802.3ah (registered trademark) -2004 (non-patent document 1), a plurality of home side devices (ONU: Optical Network Unit) share an optical communication line, and a station side device (OLT: Optical Line Terminal). One method of a passive optical network (PON), which is a medium-sharing communication that performs data transmission with the network, is disclosed. That is, EPON (Ethernet (registered trademark) PON) in which all information is communicated in the form of an Ethernet (registered trademark) frame, including user information passing through the PON and control information for managing and operating the PON, and EPON An access control protocol (MPCP (Multi-Point Control Protocol)) and an OAM (Operations Administration and Maintenance) protocol are defined. By exchanging MPCP frames between the station side device and the home side device, the home side device joins and leaves, and uplink access multiplexing control is performed. Non-Patent Document 1 describes a registration method for a new home device, a report indicating a bandwidth allocation request, and a gate indicating a transmission instruction using an MPCP message.

  As a next-generation technology of GE-PON, which is an EPON that realizes a communication speed of 1 gigabit / second, 10G-EPON standardized as IEEE 802.3av (registered trademark) -2009, that is, a communication speed of 10 gigabit / second. Even in EPON equivalent to seconds, the access control protocol is predicated on MPCP.

  By the way, in general, in a network service for business, in order to provide a high quality service, it is essential to make a system redundant (redundant). Also, a highly reliable system can be provided by using a duplex system in an audio / video distribution service. In the redundant system, a redundant configuration is adopted in which each of the devices, components, and network has an active system and a standby system as required. When a failure occurs in a part of the operating system, it is possible to make the system stop time due to the failure as short as possible by performing redundant switching from the active system to the standby system.

  Even if a failure has not become apparent, the module may be replaced proactively in consideration of the deterioration tendency of characteristics, the life of parts, and the like. If the system has a redundant configuration for the module, it is possible to shorten the system stop time due to such maintenance work as much as possible.

  As an example of the redundant configuration of the station-side device in the PON system, for example, the following station-side device is disclosed in Japanese Patent Laid-Open No. 2010-206687 (Patent Document 1). That is, the overall control unit receives the maintenance replacement instruction and sets a switching time, and at this switching time, the overall control unit stops PON line control. Further, the local control unit starts PON line control at this switching time. Then, the overall control unit is maintained and replaced, and when the PON line control is performed by the local control unit, the new maintenance and replacement unit monitors the content of the PON line control by the local control unit. Then, the new overall control unit sets a switching time, and at this switching time, the local control unit stops the PON line control, and the new overall control unit replaces the local control unit with the PON by the local control unit. PON line control is started based on the result of monitoring the line control.

IEEE Std 802.3ah (registered trademark) -2004

JP 2010-206687 A

  In the station side device in the PON system, for example, when redundant switching from the active system to the standby system is performed, discontinuity occurs in the downstream optical signal from the station side device to the ONU. That is, a time lag between the downstream optical signal from the active system and the downstream optical signal from the standby system occurs in the ONU. It is difficult to make this time shift completely zero.

  Then, when the downstream optical signal is interrupted due to such a time lag of the downstream optical signal, the ONU detects a link disconnection with the station side device and executes a process for reestablishing the link with the station side device. Will do. Here, since there are generally several dozen or more ONUs communicating with the station side device, it takes a long time for all of the ONUs that detected the link break to reestablish the link with the station side device. End up.

  Further, when the ONU detects a link disconnection, the station-side device may clear the accumulated data that was scheduled to be transmitted to the ONU, and a delay due to data retransmission processing also occurs.

  The present invention has been made to solve the above-described problem, and its purpose is to stop communication between the station side device and the home side device in response to the occurrence of an event that affects transmission of communication signals such as redundancy switching. To provide a station side device, a communication system, and a communication control method capable of reducing the time and providing a highly reliable communication system.

  In order to solve the above problems, a station-side device according to an aspect of the present invention is a station-side device for communicating with one or a plurality of home-side devices, from the station-side device to the home-side device. An event control unit for detecting an event that affects transmission of a communication signal and executing processing for the event, and stop control information indicating an instruction to stop the abnormality detection of the communication signal are transmitted by the event control unit. An abnormality detection control unit for transmitting to each of the home-side devices before the detected event occurs.

  With such a configuration, it is possible to prevent the home side device from detecting a link break during the event period. Therefore, the home side device does not perform link release processing such as discovery processing, and returns to the normal state quickly. Become. For this reason, the communication disabled time in the communication system can be shortened, and the service quality can be improved. Therefore, the communication stop time between the station side device and the home side device can be shortened with respect to the occurrence of an event that affects communication signal transmission such as redundancy switching, and a highly reliable communication system can be provided.

  Preferably, the station side device receives response information for the stop control information from the home side device, and after the event ends, the response information has not arrived among the home side devices. A link control unit is provided for executing processing for resuming communication with the home device.

  With such a configuration, when there is a home side device that has not stopped the abnormality detection for some reason even if stop control information is transmitted from the station side device, communication with the home side device is appropriately restarted. Is possible.

  Preferably, the station side device further includes an active optical line unit and a standby optical line unit, and an event that affects transmission of a communication signal from the station side device to the home side device Switching from the system optical line unit to the standby system optical line unit.

  With such a configuration, it is possible to perform redundant switching or replacement from an optical line unit that requires an event to a normal optical line unit while the home side apparatus stops detecting an abnormality in the communication signal.

  Preferably, the stop control information indicates an instruction to cause the home side device to transition to a power saving mode accompanied by the stop of the abnormality detection.

  With such a configuration, it is possible to prevent the home apparatus from detecting a link break during the event period using a general-purpose power saving protocol. In addition, unnecessary power consumption of the home device during the event period can be suppressed.

  Preferably, the stop control information is control information according to a predetermined maintenance management protocol or an extended MAC (Media Access Control) control protocol, and indicates an instruction to shift to a mode for stopping the abnormality detection.

  With such a configuration, the station-side device can reliably shift the home-side device to the abnormality detection stop state or to the power saving mode accompanied by the abnormality detection stop.

  Preferably, the stop control information includes a stop period during which the abnormality detection should be stopped.

  With this configuration, after notifying the home-side device of an abnormality detection stop instruction, the home-side device reliably restarts the abnormality detection without notifying the home-side device again of the abnormality detection restart instruction from the station-side device. can do.

  More preferably, when the event ends before the end of the stop period, the abnormality detection control unit further transmits resumption control information indicating an instruction to resume the abnormality detection to each home device. .

  With such a configuration, when an event ends earlier than scheduled, communication in the communication system can be resumed earlier, so that communication failure time in the communication system can be further shortened and service quality is improved. Can be made.

  In order to solve the above problems, a communication system according to an aspect of the present invention is a communication system including one or more home-side devices and a station-side device for communicating with each of the home-side devices, An event control unit for detecting an event that affects transmission of a communication signal from the station side device to the home side device, and stop control information indicating an instruction to stop abnormality detection of the communication signal, the event control unit An abnormality detection control unit for transmitting to each of the home side devices before the event detected by the device, the home side device receives the stop control information from the abnormality detection control unit, The abnormality detection of the communication signal from the station side device is stopped.

  With such a configuration, it is possible to prevent the home side device from detecting a link break during the event period. Therefore, the home side device does not perform link release processing such as discovery processing, and returns to the normal state quickly. Become. For this reason, the communication disabled time in the communication system can be shortened, and the service quality can be improved. Therefore, the communication stop time between the station side device and the home side device can be shortened with respect to the occurrence of an event that affects communication signal transmission such as redundancy switching, and a highly reliable communication system can be provided.

  In order to solve the above problems, a communication control method according to an aspect of the present invention is a communication control in a communication system including one or more home-side devices and a station-side device for communicating with each of the home-side devices. A method in which an event that affects transmission of a communication signal from the station side device to the home side device is detected, and stop control information indicating an instruction to stop abnormality detection of the communication signal is detected. A step transmitted to each home device before the event occurs, and a step in which the home device receives the stop control information and stops detecting an abnormality in the communication signal from the station device Including.

  With such a configuration, it is possible to prevent the home side device from detecting a link break during the event period. Therefore, the home side device does not perform link release processing such as discovery processing, and returns to the normal state quickly. Become. For this reason, the communication disabled time in the communication system can be shortened, and the service quality can be improved. Therefore, the communication stop time between the station side device and the home side device can be shortened with respect to the occurrence of an event that affects communication signal transmission such as redundancy switching, and a highly reliable communication system can be provided.

  According to the present invention, it is possible to reduce a communication stop time between a station side device and a home side device and to provide a highly reliable communication system with respect to occurrence of an event affecting communication signal transmission such as redundancy switching. Can do.

It is a block diagram which shows schematic structure of the PON system which concerns on embodiment of this invention. It is a figure which shows the structure of OSU in the station side apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the home side apparatus which concerns on embodiment of this invention. It is a figure which shows the flow of the data between the station side apparatus in a PON system which concerns on embodiment of this invention when a method (A) is employ | adopted, and the sequence of the event processing in a station side apparatus. It is a figure which shows the frame transmission control of the station side apparatus in the PON system which concerns on embodiment of this invention at the time of employ | adopting a method (A). It is a figure which shows the flow of the data between the station side apparatus in a PON system which concerns on embodiment of this invention when a method (A) is employ | adopted, and the sequence of the event processing in a station side apparatus. It is a figure which shows the flow of the data between the station side apparatus in a PON system which concerns on embodiment of this invention when a method (A) is employ | adopted, and the sequence of the event processing in a station side apparatus. It is a figure which shows the flow of the data between the station side apparatus in a PON system which concerns on embodiment of this invention when a method (B) is employ | adopted, and the sequence of the event process in a station side apparatus. It is a figure which shows the flow of the data between the station side apparatus in a PON system which concerns on embodiment of this invention when a method (B) is employ | adopted, and the sequence of the event process in a station side apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Configuration and basic operation]
FIG. 1 is a block diagram showing a schematic configuration of a PON system according to an embodiment of the present invention.

  Referring to FIG. 1, a PON system 301 includes a station-side device 201, N PON lines 1 to N (203-1 to 203-N), which are optical fibers, and N optical couplers 204-1 to 204-1. 204-N and a plurality of home-side devices (ONUs) 202. The station apparatus 201 performs overall control of the optical line units (hereinafter also referred to as OSU (Optical Subscriber Unit)) 1 to N + 1 (12-1 to 12-N + 1), the concentrator 13, and the station apparatus 201. And a general control unit 11 for performing. Here, N is an integer of 1 or more. In addition, a direction from the home side device to the host network (hereinafter also referred to as “uplink”) is referred to as an uplink direction, and a direction from the uplink to the home side device is referred to as a downlink direction.

  Here, in the PON system 301, each PON line corresponds to 10G-EPON, which is an EPON that realizes a communication speed of 10 gigabits / second, and the uplink is Ethernet (registered) that realizes a communication speed of 10 gigabits / second. The description will be made on the assumption that it corresponds to the trademark. Further, description will be made on the assumption that ONU registration / leaving and bandwidth allocation to the ONU are performed by the MPCP frame, and a bandwidth request from the ONU and a sleep (operation stop) instruction to the ONU are performed by the maintenance management protocol.

  The station apparatus 201 accommodates a plurality of PON lines corresponding to 10G-EPON. One or a plurality of ONUs are connected to one PON line. The station-side apparatus 201 multiplexes data from these PON lines into an uplink having one or a plurality of communication lines. Further, the station side device 201 distributes data from the uplink and transmits it to each home side device in each PON line. Further, the station side device 201 allocates the upstream band and the downstream band of the PON line to each home side device. For example, the upstream optical signal from each home device to the station device 201 is a burst signal, and the downstream optical signal from the station device 201 to each home device is a continuous signal.

  Specifically, the station-side device 201 is connected to N PON lines 1 to N, and terminates the N PON lines. Each OSU is provided corresponding to a PON line, and transmits / receives a frame to / from one or more ONUs connected to the corresponding PON line. The PON lines 1 to N are connected to the optical couplers 204-1 to 204-N, respectively, and are connected to the respective ONUs 202 through these optical couplers.

  The station side device 201 has, for example, an N: 1 redundant configuration. That is, among N + 1 OSUs, OSU1 to N are active (current) OSUs, and OSU N + 1 is a standby (reserved) OSU. The station side device 1a may include two or more standby OSUs.

  In accordance with an instruction from the overall control unit 11, the optical switch 14 connects N + 1 OSU1 to N + 1 (12-1 to 12-N + 1) and N PON lines 1 to N (3-1 to 3-N). Switch between communication paths.

  The concentrator 13 transmits the uplink frame received from each ONU via the plurality of OSUs to the uplink. Specifically, the concentrator 13 multiplexes uplink frames from OSU 1 to N (12-1 to 12-N + 1) and transmits them to the uplink, and distributes downlink frames received from the uplink to appropriate OSUs. Perform processing.

  FIG. 2 is a diagram showing the configuration of the OSU in the station side apparatus according to the embodiment of the present invention.

  Referring to FIG. 2, OSU 12 includes a concentrator IF (Interface) unit 31, a control IF unit 32, a reception processing unit 33, a transmission processing unit 34, a PON transceiver unit 35, and a PON control unit (event control unit). , An abnormality detection control unit, a link control unit) 36, a FIFO 37 for accumulating upstream frames, and a FIFO 38 for accumulating downstream frames.

  The PON transmission / reception unit 35 is connected to one optical fiber, which is a PON line, via the optical switch 14 as a master station side starting point of the PON line. The PON transmitter / receiver 35 receives an upstream optical signal of a specific wavelength, for example, a 1310 nm band, and converts it into an electrical signal so that bidirectional communication can be performed with each ONU via the optical fiber, and then converts it into an electrical signal. In addition to outputting, the electrical signal received from the transmission processing unit 34 is converted into a downstream optical signal of another wavelength and transmitted. For example, the PON transmission / reception unit 35 converts a 10 Gbps electrical signal received from the transmission processing unit 34 into a downstream optical signal in the 1570 nm band and transmits the converted signal.

  The reception processing unit 33 reconstructs a frame from the electrical signal received from the PON transmission / reception unit 35 and distributes the frame to the PON control unit 36 or the FIFO 37 according to the type of the frame. Specifically, the data frame is output to the FIFO 37 and the control frame is output to the PON control unit 36.

  Further, the reception processing unit 33 may receive grant information indicating when to receive a frame from which logical link from the transmission processing unit 34 and output a control signal for supporting burst reception to the PON transmission / reception unit 35. Good. Further, the reception processing unit 33 may receive this grant information and filter, that is, discard, a received frame that is not indicated in the grant information. The reception processing unit 33 may output the MPCP frame by overwriting the time stamp at the time of reception.

  The concentrating IF unit 31 outputs the upstream frame stored in the FIFO 37 to the concentrating unit 13. Further, when receiving the frame from the line concentrator 13, the line concentrator IF 31 outputs it to the FIFO 38 when the frame is a normal data frame, and outputs it to the PON controller 36 when the frame is a control frame. To do.

  When receiving the control frame from the PON control unit 36, the concentration IF unit 31 outputs the control frame to the concentration unit 13 with priority over the frame from the FIFO 37 between the frame sequences from the FIFO 37.

  When the FIFO 38 or the PON control unit 36 has a frame to be transmitted, the transmission processing unit 34 receives the frame according to the priority order and outputs it to the PON transmission / reception unit 35. At this time, the transmission processing unit 34 may output the MPCP frame by overwriting the time stamp at the time of transmission.

  The PON control unit 36 performs station-side processing related to control and management of the PON line such as MPCP and OAM. That is, by exchanging MPCP messages and OAM messages with each ONU connected to the PON line, upstream access control including ONU registration, leaving and bandwidth allocation, downlink access control including bandwidth allocation, and ONU The operation management of the ONU including the sleep instruction is performed.

  Based on an instruction from the overall control unit 11, the control IF unit 32 performs settings in the concentrating IF unit 31, the reception processing unit 33, the transmission processing unit 34, and the PON control unit 36, and sets the status of each unit as a whole. Notify the control unit 11. Further, when an abnormality occurs in each of these units, the state of the unit in which the abnormality has occurred is notified to the overall control unit 11 without depending on an instruction from the overall control unit 11. Setting and status notification to the PON transceiver 35 are performed via the reception processor 33.

  FIG. 3 is a diagram showing the configuration of the home-side apparatus according to the embodiment of the present invention.

  Referring to FIG. 3, home apparatus 202 includes PON port 21, optical reception processing unit 22, buffer memory 23, transmission processing unit 24, UNI (User Network Interface) port 25, and reception processing unit 26. A buffer memory 27, an optical transmission processing unit 28, and a control unit 29.

  The optical reception processing unit 22 receives the downstream optical signal transmitted from the station side device 201 via the PON port 21, converts it into an electrical signal, reconstructs the frame from the electrical signal, and according to the type of the frame The frame is distributed to the control unit 29 or the transmission processing unit 24 via the buffer memory 23. Specifically, the optical reception processing unit 22 outputs a data frame to the transmission processing unit 24 and outputs a control frame to the control unit 29.

  The transmission processing unit 24 transmits the data frame received from the optical reception processing unit 22 to a user terminal such as a personal computer (not shown) via the UNI port 25.

  The reception processing unit 26 outputs the data frame received from the user terminal via the UNI port 25 to the optical transmission processing unit 28 via the buffer memory 27.

  The control unit 29 performs home-side processing related to control and management of the PON line such as MPCP and OAM. That is, various controls such as access control are performed by exchanging MPCP messages and OAM messages with the station-side apparatus 201 connected to the PON line. The control unit 29 generates a control frame including various control information and outputs it to the optical transmission processing unit 28 via the buffer memory 27.

  The optical transmission processing unit 28 converts the data frame received from the reception processing unit 26 and the control frame received from the control unit 29 into an optical signal, and transmits the optical signal to the station apparatus 201 via the PON port 21.

[Operation]
The PON control unit 36 in the OSU detects an event and executes processing for the event. This event is a scheduled event that affects transmission of a communication signal from the station-side apparatus 201 to the ONU. Note that the PON control unit 36 may be configured to detect the event by a notification from the overall control unit 11.

  Specifically, this event is a software update, a part replacement, and a hardware setting change or reset such as a transceiver and a receiver for the station side device. Also, switching of optical switches and changing of optical fiber connection at the time of redundant switching or replacement from its own station-side device to another station-side device. Also, switching of the optical switch and changing of the connection of the optical fiber at the time of redundant switching or replacement from the active OSU to the standby OSU in its own station side device. For example, the station-side apparatus 201 can acquire information on the scheduled execution period including the scheduled start timing of these events.

  Here, in the PON system, when the above event is executed, discontinuity occurs in the downstream optical signal from the station side device to the ONU. That is, a time lag between the downstream optical signal from the active system and the downstream optical signal from the standby system occurs in the ONU.

  When the downstream optical signal is interrupted due to such a time lag of the downstream optical signal, the ONU detects a link disconnection with the station side device. When the ONU detects link disconnection, the ONU performs re-link up, that is, processing for re-establishing the link with the station side device. In the PON system, since communication cannot be performed between the ONU and the station side device until the authentication of the ONU is successful, the communication quality deteriorates.

  As a simple method for avoiding such a problem, it can be considered that the condition for the ONU to detect link breakage based on the downstream optical signal is moderated to some extent. However, in such a method, the timing for detecting the link disconnection in the ONU may be delayed, and the undetected link disconnection may occur.

  Here, when performing redundant switching or replacement from the active OSU to the standby OSU, the switching destination OSU must take over the setting of the switching source OSU and operate. As a setting takeover method accompanying this OSU redundancy switching, there is a method of performing communication between OSUs. More specifically, OSUs directly communicate with each other and share various information. The OSU may pass all information to other OSUs by communication, or may use a memory shared between the OSUs. Alternatively, as described in Patent Document 1, it may be configured to manage each OSU as a whole.

  In the PON system according to the embodiment of the present invention, the PON control unit 36 in the station-side apparatus 201 is a stop indicating an instruction to stop detection of abnormalities of the downstream optical signal that is a communication signal, for example, detection of link disconnection, for each ONU. Control information is transmitted to each ONU before the detected event occurs. For example, the stop control information includes a stop period during which abnormality detection should be stopped.

  Specifically, the PON control unit 36 causes the ONU to sleep, for example, from the start of the above event to the completion thereof. As a result, it is possible to prevent a link break in the ONU during the event period.

  Here, the following method (A) and method (B) can be considered as a method for causing the ONU to transition to the sleep state. That is, (A) a method using a power saving protocol that is being standardized by IEEE 1904.1 (SIPON), and (B) a method using a predetermined maintenance management protocol such as extended OAM can be considered.

  In the method (A), the stop control information is a sleep instruction indicating an instruction to shift the ONU to the power saving mode accompanied by the stop of abnormality detection.

  This method (A) is highly versatile because it uses a protocol that complies with the standard. On the other hand, when the ONU detects, for example, upstream traffic, there is a possibility that a NACK is returned in response to the sleep instruction from the station side device. For this reason, there is a possibility that the ONU cannot be surely put to sleep. However, since standardization of IEEE 1904.1 (SIPON) has not been completed at the time of this application, there is a possibility that the ONU can be surely put to sleep.

  In the method (A), a sleep time is sufficient as information notified from the station side device to the ONU. That is, the station side device sets a sleep time necessary for completing the event, and causes the ONU to sleep.

  In the method (B), the stop control information is control information according to, for example, extended OAM, and is a link disconnection detection prohibition instruction indicating an instruction to shift to a mode for stopping abnormality detection.

  This method (B) is basically realized by vendor-specific definition and creation. For this reason, it is possible to surely make the target ONU sleep, but if such an extended OAM is not standardized in the future, it may lack versatility.

  Even in the method (B), the sleep time is sufficient as the information notified from the station side device to the ONU. This information may not be the sleep time, but may be a link break detection prohibition period in which the ONU does not detect link breaks, and it is not essential for the ONU to transition to a sleep state involving operation stop of the transceiver, receiver, or the like.

  Next, the operation when the station apparatus according to the embodiment of the present invention performs event processing will be described with reference to the drawings. In the embodiment of the present invention, the communication control method according to the embodiment of the present invention is implemented by operating the station side device 201. Therefore, the description of the communication control method according to the embodiment of the present invention is replaced with the following description of the operation of the station-side device 201. In the following description, FIGS. 1 to 3 are appropriately referred to.

  FIG. 4 is a diagram showing a data flow between the station side device and the home side device in the PON system according to the embodiment of the present invention and a sequence of event processing in the station side device when the method (A) is adopted. It is. FIG. 4 describes a sequence for one PON line, that is, a process between one OSU and a plurality of ONUs. Also, a case will be described in which ONUs under the OSU are ONUs 1 to 3, that is, ONUs 1 to 3 are connected to PON lines corresponding to the OSU.

  Referring to FIG. 4, first, the PON control unit 36 in the OSU detects a scheduled event (step S1).

  Next, the PON control unit 36 generates, for example, a control frame indicating a sleep instruction according to the power saving protocol, and transmits the control frame to the ONUs 1 to 3 via the transmission processing unit 34 and the PON transmission / reception unit 35 (step S2). This sleep instruction includes a sleep period TS.

  Next, the control unit 29 in the ONUs 1 to 3 receives a sleep instruction from the OSU via the PON port 21, the optical reception processing unit 22, and the buffer memory 23. Then, the control unit 29 generates a control frame indicating a sleep ACK for the received sleep instruction, and transmits the control frame to the OSU via the buffer memory 27, the optical transmission processing unit 28, and the PON port 21 (step S3).

  Next, the control unit 29 executes the sleep process at the start time tss of the sleep period TS indicated by the sleep instruction, and transitions to the sleep state (step S4).

  Next, the PON control unit 36 in the OSU performs processing for starting an event at the scheduled time tes. More specifically, the PON control unit 36 performs control to stop the operation of each unit in the OSU, for example (step S5).

  Here, the PON control unit 36 sets the start time tss of the sleep period TS indicated by the sleep instruction to a time before the scheduled time tes.

  Next, when the event ends (step S6), the PON control unit 36 executes a restart process, that is, executes a start process for each unit in the OSU (step S7).

  Next, the control unit 29 in the ONUs 1 to 3 executes the wake-up process at the end time tse of the sleep period TS indicated by the sleep instruction, and transitions from the sleep state to the normal state (step S8).

  Here, the PON control unit 36 in the OSU sets the end time tse of the sleep period TS indicated by the sleep instruction to a time after the scheduled time trf at which the restart process is completed.

  FIG. 5 is a diagram showing frame transmission control of the station side device in the PON system according to the embodiment of the present invention when the method (A) is adopted. The conditions are the same as in FIG. Moreover, the operation | movement of step S11-S15 is the same as that of step S1-S5 in the sequence shown in FIG.

  Referring to FIG. 5, first, in the normal power saving protocol, in order to enable the ONU to wake up earlier than the scheduled sleep release time when detecting upstream traffic, Even during sleep, a gate frame is periodically transmitted to the ONU. Specifically, when the ONU is in the sleep state, when the ONU receives data to be transmitted to the OSU from the user terminal, for example, when the ONU receives the data (step S16), the ONU transitions from the sleep state to the normal state. (Step S17).

  Further, the OSU periodically generates a gate frame indicating a band to be allocated to the subordinate ONU and transmits the gate frame to the ONU (step S18).

  Then, the ONU receives the gate frame from the OSU and transmits a data frame to the OSU according to the band indicated by the gate frame (step S19).

  On the other hand, in the PON system according to the embodiment of the present invention, for example, when performing redundant switching, the PON control unit 36 in the switching source OSU transmits a sleep instruction to the ONU and then gates the ONU. Stop sending frames. Specifically, when the ONU is in a sleep state, the OSU does not generate and transmit a gate frame to the ONU (step S18).

  With such a configuration, for example, when redundant switching or replacement of OSUs is performed, it is possible to prevent the ONU from getting up earlier than the scheduled time. That is, since it is possible to prevent a data frame from being transmitted from the ONU to the OSU during the event period (step S19), uplink data that could not be processed by the OSU during the event period is retransmitted from the ONU side. Generation of processing can be prevented.

  FIG. 6 is a diagram showing a data flow between the station side device and the home side device and a sequence of event processing in the station side device in the PON system according to the embodiment of the present invention when the method (A) is adopted. It is. The conditions are the same as in FIG. The operations in steps S51 and S52 are the same as those in steps S1 and S2 in the sequence shown in FIG.

  Referring to FIG. 6, for example, the PON system 301 supports only the ONU that returns a sleep ACK. In other words, the PON control unit 36 in the station side device 201 receives response information, that is, sleep ACK, by the scheduled time tes at which the event should be started among all ONUs under its control, that is, all ONUs connected to the corresponding PON line. Even if there is an ONU that has not been executed, a process for starting an event is executed at the scheduled time tes.

  Normally, when the ONU accepts the sleep instruction, the ONU returns a sleep ACK to the station-side apparatus 201, and performs the sleep process at the designated time tss indicated by the sleep instruction. Then, the ONU enters a sleep state accompanied by stoppage of link disconnection detection in the designated period TS indicated by the sleep instruction. In the process shown in FIG. 6, a sleep ACK is not returned to the station side device, and an ONU that has not performed the sleep process is allowed to detect a link disconnection due to the start of an event.

  More specifically, the control unit 29 in the ONU 1 and the ONU 2 receives a sleep instruction from the OSU. And the control part 29 produces | generates the control frame which shows sleep ACK with respect to the received sleep instruction | indication, and transmits to OSU (step S53).

  Next, the control unit 29 in the ONU 1 and the ONU 2 executes the sleep process at the start time tss of the sleep period TS indicated by the sleep instruction, and transitions to the sleep state (step S55).

  Here, it is assumed that the control unit 29 in the ONU 3 does not transmit the control frame indicating the sleep ACK to the OSU for some reason and does not transition to the sleep state (step S54).

  Next, the PON control unit 36 in the OSU receives the sleep ACK from the ONU 1 and the ONU 2. Here, the PON control unit 36 performs a process for starting an event at the scheduled time tes, although the sleep ACK is not received from the ONU 3. More specifically, the PON control unit 36 performs control to stop the operation of each unit in the OSU, for example (step S56).

  Next, when the event ends (step S57), the PON control unit 36 executes a restart process, that is, executes a start process for each unit in the OSU (step S58).

  Next, the control unit 29 in the ONU 1 and the ONU 2 executes the wake-up process at the end time tse of the sleep period TS indicated by the sleep instruction, and transitions from the sleep state to the normal state (step S59).

  Next, the PON control unit 36 in the OSU executes link re-establishment processing for resuming communication with the ONU 3 in which the response information, that is, the sleep ACK has not arrived, among the ONUs connected to the corresponding PON line (step S1). S60).

  Through the processing as described above, the subordinate ONUs can be shifted to the sleep state as much as possible, and the event can be reliably started at the scheduled time.

  FIG. 7 is a diagram showing a data flow between the station side device and the home side device in the PON system according to the embodiment of the present invention and a sequence of event processing in the station side device when the method (A) is adopted. It is. The conditions are the same as in FIG. The operations in steps S61 and S62 are the same as those in steps S1 and S2 in the sequence shown in FIG.

  Referring to FIG. 7, for example, the PON system 301 supports all the ONUs under its control. That is, the OSU continues to send a sleep instruction at predetermined intervals until all subordinate ONUs return response information, that is, sleep ACK. More specifically, the PON control unit 36 resends the sleep instruction to each ONU when there is an ONU in which the sleep ACK does not arrive even after a predetermined time has elapsed since the stop control information, that is, the sleep instruction is transmitted. After receiving the sleep ACK from each ONU, the process for starting the event is executed.

  In the process illustrated in FIG. 7, an ONU that performs a sleep process a plurality of times is allowed to appear until the OSU starts an event.

  More specifically, the control unit 29 in the ONU 1 and the ONU 2 receives a sleep instruction from the OSU. And the control part 29 produces | generates the control frame which shows sleep ACK with respect to the received sleep instruction | indication, and transmits to OSU (step S63).

  Next, the control unit 29 in the ONU 1 and the ONU 2 executes the sleep process at the start time tss of the sleep period TS indicated by the sleep instruction, and transitions to the sleep state (step S65).

  Here, it is assumed that the control unit 29 in the ONU 3 does not transmit the control frame indicating the sleep ACK to the OSU for some reason and does not transition to the sleep state (step S64).

  Next, the PON control unit 36 in the OSU receives the sleep ACK from the ONU 1 and the ONU 2. Here, since the PON control unit 36 has not received the sleep ACK from the ONU 3, the PON control unit 36 does not perform a process for starting an event.

  Next, the control unit 29 in the ONU 1 and the ONU 2 executes the wake-up process at the end time tse of the sleep period TS indicated by the sleep instruction, and transitions from the sleep state to the normal state (step S66).

  Next, the PON control unit 36 in the OSU again generates a control frame indicating a sleep instruction and transmits it to the ONUs 1 to 3. This sleep instruction includes a new sleep period TS. Here, the PON control unit 36 knows the time tse at which each ONU returns from the sleep state to the normal state, and retransmits the sleep instruction after the time tse (step S67). As a result, since the ONU is in the sleep state, it returns to the normal state without receiving the retransmitted sleep instruction, and thereafter, the event is started in the station side device 201 and the link disconnection is detected. Can be prevented.

  Next, the control unit 29 in the ONUs 1 to 3 receives a sleep instruction from the OSU. And the control part 29 produces | generates the control frame which shows sleep ACK with respect to the received sleep instruction | indication, and transmits to OSU (step S68).

  Next, the control unit 29 in the ONUs 1 to 3 executes the sleep process at the start time tss of the sleep period TS indicated by the sleep instruction, and transitions to the sleep state (step S69).

  Next, the PON control unit 36 in the OSU receives the sleep ACK from the ONU1 to ONU3, and performs a process for starting an event after the time tss (step S70).

  Through the processing as described above, it is possible to prevent the occurrence of an ONU that detects a broken link.

  The OSU may be configured to start an event when a predetermined time has elapsed even when the sleep ACK has not been received from all ONUs.

  The OSU may be configured to reliably support a specific ONU. That is, the station-side device may be configured to give priority to the ONUs, such as not starting an event until a sleep ACK is received from an ONU of a user who has signed a specific contract. More specifically, the PON control unit 36 is a case where there is an ONU in which the response information, that is, the sleep ACK does not arrive even after a predetermined time has elapsed since the stop control information, that is, the sleep instruction is transmitted. When response information has arrived from a predetermined ONU, processing for starting an event is executed. On the other hand, when a sleep ACK has not arrived from a predetermined ONU, the PON control unit 36 retransmits a sleep instruction to each ONU.

  As described above, the configuration in which the priority order is provided between the ONUs can provide a more flexible communication service.

  FIG. 8 is a diagram showing a data flow between the station side device and the home side device in the PON system according to the embodiment of the present invention and a sequence of event processing in the station side device when the method (B) is adopted. It is. The conditions are the same as in FIG.

  Referring to FIG. 8, first, the PON control unit 36 in the OSU detects a scheduled event (step S31).

  Next, the PON control unit 36 generates a control frame indicating a link disconnection detection prohibition instruction according to, for example, extended OAM, and transmits the control frame to the ONUs 1 to 3 via the transmission processing unit 34 and the PON transmission / reception unit 35 (step S32). This link disconnection detection prohibition instruction includes a link disconnection detection prohibition period TH.

  Next, the control unit 29 in the ONUs 1 to 3 receives the link disconnection detection prohibition instruction from the OSU via the PON port 21, the optical reception processing unit 22, and the buffer memory 23. Then, the control unit 29 generates a control frame indicating ACK for the received link break detection prohibition instruction, and transmits it to the OSU via the buffer memory 27, the optical transmission processing unit 28, and the PON port 21 (step S33).

  Next, the control unit 29 in the ONUs 1 to 3 stops the link break detection at the start time ths of the link break detection prohibition period TH indicated by the link break detection prohibition instruction (step S34).

  Next, the PON control unit 36 in the OSU performs processing for starting an event at the scheduled time tes. More specifically, the PON control unit 36 performs control to stop the operation of each unit in the OSU, for example (step S35).

  Here, the PON control unit 36 sets the start time ths of the link disconnection detection prohibition period TH indicated by the link disconnection detection prohibition instruction to a time before the scheduled time tes.

  Next, when the event ends (step S36), the PON control unit 36 executes a restart process, that is, executes a start process of each unit in the OSU (step S37).

  Next, the control unit 29 in the ONUs 1 to 3 restarts the link break detection at the end time the end of the link break detection prohibition period TH indicated by the link break detection prohibition instruction (step S38).

  Here, the PON control unit 36 in the OSU sets the end time “the” of the link disconnection detection prohibition period TH indicated by the link disconnection detection prohibition instruction to a time after the scheduled time trf at which this restart process is completed.

  FIG. 9 is a diagram showing a data flow between the station side device and the home side device and a sequence of event processing in the station side device in the PON system according to the embodiment of the present invention when the method (B) is adopted. It is. The conditions are the same as in FIG. Moreover, the operation | movement of step S81-S85 is the same as that of step S31-S35 in the sequence shown in FIG.

  Referring to FIG. 9, the PON control unit 36 performs resumption control indicating an instruction to resume abnormality detection when the event ends before the end of the stop period in which abnormality detection should be stopped, that is, the link breakage detection prohibition period TH. Information, that is, a link disconnection detection restart instruction is transmitted to each ONU.

  More specifically, when the event ends in a shorter time than the scheduled event period TE (step S86), the PON control unit 36 executes a restart process (step S87) and detects, for example, link breakage according to the extended OAM. A control frame indicating a restart instruction is generated and transmitted to the ONUs 1 to 3 via the transmission processing unit 34 and the PON transmission / reception unit 35 (step S88).

  Next, the control unit 29 in the ONUs 1 to 3 receives a link disconnection detection restart instruction from the OSU via the PON port 21, the optical reception processing unit 22, and the buffer memory 23. Then, the control unit 29 generates a control frame indicating ACK for the received link disconnection detection restart instruction, and transmits the control frame to the OSU via the buffer memory 27, the optical transmission processing unit 28, and the PON port 21 (step S89).

  Next, the control unit 29 in the ONUs 1 to 3 resumes link disconnection detection (step S90).

  By the way, if the downstream optical signal is interrupted due to a time lag of the downstream optical signal, it takes a long time for all of the ONUs that detect the link disconnection to reestablish the link with the station side device. Further, when the ONU detects a link disconnection, the station-side device may clear the accumulated data that was scheduled to be transmitted to the ONU, and a delay due to data retransmission processing also occurs.

  On the other hand, in the station-side device according to the embodiment of the present invention, the PON control unit 36 detects a scheduled event that affects transmission of a communication signal from the station-side device 201 to the ONU. Execute the process for Then, the PON control unit 36 transmits stop control information indicating an instruction to stop the abnormality detection of the communication signal to each ONU before the event detected by the PON control unit 36 occurs.

  In the event period such as software update and redundancy switching as described above, the downlink communication itself is cut off because no downlink frame is transmitted from the station side apparatus 201. However, the configuration in which the ONU is put to sleep during the event period has an advantage that the return of the ONU is accelerated.

  In other words, since it is possible to prevent the ONU from detecting a link break during the event period, the ONU does not perform link release processing such as discovery processing, and the return to the normal state is accelerated. For this reason, the communication disabled time in the PON system can be shortened, and the service quality can be improved.

  Therefore, in the station side apparatus according to the embodiment of the present invention, the communication stop time between the station side apparatus and the home side apparatus is shortened for the occurrence of an event that affects the transmission of communication signals such as redundancy switching, and the reliability is improved. A highly reliable communication system can be provided.

  Moreover, in the station side apparatus which concerns on embodiment of this invention, the PON control part 36 performs the process which restarts communication with ONU which response information did not arrive among each ONU after completion | finish of an event.

  With such a configuration, when there is an ONU that has not stopped abnormality detection for some reason even when stop control information is transmitted from the station-side device 201, communication with the ONU can be appropriately restarted. Become.

  Further, in the station side apparatus according to the embodiment of the present invention, the event that affects the transmission of the communication signal from the station side apparatus 201 to the ONU includes switching from the active OSU to the standby OSU.

  With such a configuration, it is possible to perform redundant switching or replacement from an OSU that requires an event to a normal OSU while the ONU stops detecting an abnormality in the communication signal.

  Moreover, in the station side apparatus which concerns on embodiment of this invention, stop control information shows the instruction | indication which changes ONU to the power saving mode accompanied by the stop of abnormality detection.

  With such a configuration, it is possible to prevent the ONU from detecting a link break during the event period by using a general-purpose power saving protocol. Further, unnecessary power consumption of the ONU during the event period can be suppressed.

  In the station apparatus according to the embodiment of the present invention, the stop control information is control information according to a predetermined maintenance management protocol, and indicates an instruction to shift to a mode for stopping abnormality detection.

  With such a configuration, the station-side apparatus 201 can reliably transition the ONU to the abnormality detection stop state or to the power saving mode accompanied by the abnormality detection stop.

  Moreover, in the station side apparatus which concerns on embodiment of this invention, stop control information contains the stop period which should stop abnormality detection.

  With such a configuration, after the abnormality detection stop instruction is notified to the ONU, the abnormality detection can be reliably restarted in the ONU without notifying the ONU again of the abnormality detection restart instruction from the station-side apparatus 201.

  Further, in the station-side device according to the embodiment of the present invention, the PON control unit 36 further performs resumption control indicating an instruction to resume abnormality detection when the event ends before the abnormality detection stop period ends. Information is transmitted to each ONU.

  With such a configuration, when an event ends earlier than scheduled, communication in the PON system can be resumed earlier, thereby further reducing the communication failure time in the PON system and improving service quality. Can be made.

  In the PON system according to the embodiment of the present invention, the PON control unit 36 is configured to transmit a sleep instruction to all ONUs connected to the corresponding PON line. It is not a thing. The PON control unit 36 may be configured to transmit a sleep instruction only to some ONUs such as the ONUs of users who have a specific service contract among subordinate ONUs.

  With such a configuration, only the data to be transmitted to some ONUs needs to be accumulated after the end of the event in the station-side apparatus 201, so the buffer capacity for accumulating data to be transmitted to the ONU is reduced. It becomes possible.

  In the PON system according to the embodiment of the present invention, the station apparatus 201 is configured to notify the ONU of the sleep period TS, but the present invention is not limited to this. The station-side apparatus 201 may not include the sleep period TS in the sleep instruction, but may transmit a sleep release instruction to the ONU after the event ends, and transition the ONU from the sleep state to the normal state.

  Further, in the PON system according to the embodiment of the present invention, the station apparatus 201 performs control to stop the ONU from detecting abnormality of the signal when an event that affects continuous signal transmission occurs. However, the present invention is not limited to this. The station-side apparatus 201 is not limited to a continuous signal. For example, in a PON system in which burst signals are transmitted from the station-side apparatus to the ONU at predetermined intervals, the station-side apparatus 201 controls the ONU to stop detecting abnormality of the burst signal. The structure to perform may be sufficient.

  In the PON system according to the embodiment of the present invention, the PON control unit 36 in the station-side device 201 detects a scheduled event that affects the transmission of the communication signal from the station-side device 201 to the ONU, and the communication signal The stop control information indicating an instruction to stop the abnormality detection is transmitted to each ONU before the event detected by the PON control unit 36 occurs. However, the present invention is not limited to this. The operation by the PON control unit 36 as described above may be executed in the ONU 202 in the PON system 301 or another device (not shown) in addition to the station-side device 201.

  Further, in the station side apparatus according to the embodiment of the present invention, the PON control unit 36 is configured to detect a scheduled event that affects transmission of a communication signal from the station side apparatus 201 to the ONU. However, the present invention is not limited to this. Not only the scheduled event, but the PON control unit 36 detects an unexpected event that affects the transmission of the communication signal from the station side device 201 to the ONU, and the PON control unit 36 stops detecting the abnormality of the communication signal. The configuration may be such that stop control information indicating an instruction is transmitted to each ONU before the event occurs.

  Moreover, in the station side apparatus which concerns on embodiment of this invention, although the method (A) and the method (B) were illustrated as a method of changing ONU to a sleep state, extended MAC (Media Access Control) control protocol is used. Method (C) is also conceivable. In the method (C), the stop control information is, for example, control information according to the extended MAC, and is a link disconnection detection prohibition instruction indicating an instruction to shift to a mode for stopping abnormality detection.

  In the station side apparatus according to the embodiment of the present invention, the PON control unit 36 transmits a sleep instruction or a link disconnection detection prohibition instruction to each ONU connected to the corresponding PON line. Here, the transmission mode of the sleep instruction or the link disconnection detection prohibition instruction may be a unicast method in which a control frame indicating the sleep instruction or the link disconnection detection prohibition instruction is individually transmitted to each ONU. A multicast method in which one control frame is collectively transmitted to a plurality of ONUs may be used.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

11 Overall Control Unit 12, 12-1 to 12-N + 1 Optical Line Unit (OSU)
DESCRIPTION OF SYMBOLS 13 Concentration part 21 PON port 22 Optical reception process part 23 Buffer memory 24 Transmission process part 25 UNI port 26 Reception process part 27 Buffer memory 28 Optical transmission process part 31 Concentration IF part 32 Control IF part 33 Reception process part 34 Transmission process part 35 PON transceiver unit 36 PON control unit (event control unit, abnormality detection control unit, link control unit)
37,38 FIFO
201 Station side equipment (OLT)
202 Home unit (ONU)
203-1 to 203-N PON line 204-1 to 204-N optical coupler 301 PON system

Claims (9)

A station-side device for communicating with one or more home-side devices,
An event control unit for detecting an event that affects transmission of a communication signal from the station-side device to the home-side device and executing processing for the event;
An abnormality detection control unit for transmitting stop control information indicating an instruction to stop abnormality detection of the communication signal to each of the home-side devices before the event detected by the event control unit occurs. Station side device. The station side device receives response information for the stop control information from the home side device,
further,
The link control part for performing the process which restarts communication with the said home side apparatus from which the said response information did not arrive among the said each home side apparatuses after completion | finish of the said event, The Claim 1 of Claim 1 Station side device. The station side device further includes an operational optical line unit and a standby optical line unit,
The event affecting the transmission of the communication signal from the station side device to the home side device includes switching from the active optical line unit to the standby optical line unit. The station side apparatus of description.   The station-side device according to any one of claims 1 to 3, wherein the stop control information indicates an instruction to cause the home-side device to transition to a power saving mode that involves stopping the abnormality detection.   The stop control information is control information according to a predetermined maintenance management protocol or an extended MAC (Media Access Control) control protocol, and indicates an instruction to shift to a mode for stopping the abnormality detection. The station side apparatus of any one of these.   The station side apparatus according to any one of claims 1 to 5, wherein the stop control information includes a stop period during which the abnormality detection is to be stopped.   The abnormality detection control unit further transmits resumption control information indicating an instruction to resume the abnormality detection to each home device when the event ends before the end of the stop period. The station side apparatus as described in. A communication system comprising one or more home-side devices and a station-side device for communicating with each home-side device,
An event control unit for detecting an event that affects transmission of a communication signal from the station side device to the home side device;
An abnormality detection control unit for transmitting stop control information indicating an instruction to stop abnormality detection of the communication signal to each home device before the event detected by the event control unit occurs,
The home apparatus receives the stop control information from the abnormality detection control unit, and stops detecting an abnormality of the communication signal from the station apparatus. A communication control method in a communication system comprising one or more home-side devices and a station-side device for communicating with each home-side device,
Detecting an event that affects transmission of a communication signal from the station side device to the home side device;
Stop control information indicating an instruction to stop the abnormality detection of the communication signal is transmitted to each home-side device before the detected event occurs; and
A communication control method comprising: receiving the stop control information at the home side device and stopping detecting an abnormality of the communication signal from the station side device.

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