JP6410620B2 - Line switching method, communication method, and subscriber side device - Google Patents

Description

  The present invention relates to a line switching method using a redundant line in a communication system including an OLT (Optical Line Terminal) and an ONU (Optical Network Unit).

  In general, a packet (hereinafter also referred to as “multicast packet”) including video data or the like distributed by multicast from an upper network is transmitted from an OLT as a station side device (station side communication device) through a physical line such as an optical fiber. A communication system such as a PON (Passive Optical Network) system that transfers data to a plurality of ONUs as a plurality of subscriber side devices (terminal side communication devices) is used. For example, in the PON system, terminal devices are further connected under these ONUs, and a control signal (hereinafter also simply referred to as “viewing request”) as a viewing request for a specific channel from the terminal devices under the control of the ONU. By receiving, the multicast packet corresponding to the channel that is the target of the viewing request is transferred from the ONU to the subordinate terminal device. In such a PON system, the multicast transfer of a packet from the station side device to the subscriber side device is called “PON multicast”.

  In such a PON system, for example, a Multicast Listener Discovery (MLD) frame as a viewing request is transmitted from the terminal device to the OLT, and OAM (Operation Administration) defined in IEEE (The Institute of Electrical and Electronic Engineers) 802.3ah is used. and Maintenance) by transmitting a frame from the OLT to the ONU and setting a filter, a method for controlling a multicast packet transferred to a terminal device has been proposed (see, for example, Patent Document 1).

  Also, in business network services that require high reliability, OLT is made redundant by terminating a plurality of OSUs (Optical Subscriber Units) that communicate with subordinate ONUs in the OLT. An enhanced communication system has been proposed. A communication system with redundant lines reduces maintenance work and maintenance costs due to OSU replacement and the like in the case of a network service for the general public at night. In such a communication system, there has been proposed a method for preventing an instantaneous interruption of communication when a redundant OSU line is switched (see, for example, Patent Document 2).

  Further, for example, when a communication failure occurs in the active line (communication link), a predetermined time may be required until the communication using the backup line is resumed. In order to solve such a problem, during a predetermined holdover period, the occurrence of a time stamp drift error, which is a disconnection factor of the communication link, is suppressed, and the time required for re-establishing the standby communication link is reduced. A shortening method has been proposed (see, for example, Patent Document 3).

JP 2010-016753 A JP 2010-147801 A International Publication No. 2012/070089

  However, in a communication system with redundant lines, for example, when a viewing request (reception request) is transmitted from a terminal under the ONU during a line switching operation, the requested multicast packet is not properly transferred to the terminal. was there. Therefore, for example, from the time of occurrence of a line abnormality (line failure) until a viewing request is again transmitted by the terminal after completion of line switching, or after the completion of line switching from the occurrence of line abnormality, There is a problem that the terminal cannot view the channel until the inquiry about whether or not there is a viewing request.

  Therefore, an object of the present invention is to promptly start reception of a multicast packet by a terminal under the control of an ONU after occurrence of a line abnormality.

  The line switching method according to the present invention includes a station-side apparatus having a plurality of optical line units including an active optical line unit and a standby optical line unit, and multicast packets transferred from any of the plurality of optical line units. And a line switching method in a communication system comprising a subscriber side device that communicates with a subordinate terminal, wherein the subscriber side device is transferred from one of the plurality of optical line units. Generating a packet signal based on a multicast packet; and when a line abnormality occurs, the station side device transfers the optical line unit for transferring the multicast packet from the working optical line unit to the standby system. A step of switching to the optical line unit, and the subscriber side device is connected to the multi-line transferred from the standby optical line unit. Characterized by a step of the packet signal based on the catcher strike packet temporarily transmitting state physical address filter condition to decide whether to transfer to the terminal.

  According to the communication method of the present invention, a multicast packet is transferred from a station side apparatus having a plurality of optical line units including an active optical line unit and a standby optical line unit, and any of the plurality of optical line units. And a communication method in a communication system comprising a subscriber side device that communicates with a subordinate terminal, wherein the subscriber side device transmits the multicast packet transferred from any of the plurality of optical line units. And a physical address filter state for determining whether or not to transfer a packet signal based on a multicast packet transferred from the standby optical line unit to the terminal when a line abnormality occurs And temporarily setting to a transparent state.

  The subscriber side apparatus of the present invention transfers multicast packets from any of the optical line units in the station side apparatus having a plurality of optical line units including the active optical line unit and the standby optical line unit. A subscriber-side device that communicates with a subordinate terminal that receives an optical network processing unit that generates a packet signal based on the multicast packet and a packet signal based on the multicast packet transferred from the optical network processing unit Whether or not to transfer a packet signal based on a multicast packet transferred from the standby optical line unit to the terminal in the physical address filter unit when a line abnormality occurs. The physical address filter state that decides the transition to a temporarily transparent state And wherein the Rukoto.

  According to the present invention, it is possible to start multicast packet reception (that is, channel viewing) at an early stage after the occurrence of a line abnormality.

1 is a system configuration diagram of a PON system for realizing a line switching method according to a first embodiment of the present invention. It is a block diagram which shows the structure of ONU shown by FIG. It is a sequence diagram which shows the communication operation | movement in the PON system shown by FIG. It is a sequence diagram which shows the communication operation | movement in the PON system for implement | achieving the line switching method which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of OLT with which the PON system as a 1st modification of the PON system for implement | achieving the line switching method demonstrated in Embodiment 1 and 2 is equipped. It is a block diagram which shows the structure of the control part shown by FIG. It is a block diagram which shows the structure of ONU with which the PON system as a 2nd modification of the PON system for implement | achieving the line switching method demonstrated in Embodiment 1 and 2 is equipped. It is a block diagram which shows the structure of the control part shown by FIG.

Embodiment 1 FIG.
FIG. 1 is a system configuration diagram of a PON system as a communication system for realizing the line switching method according to the first embodiment of the present invention. The PON system shown in FIG. 1 includes an OLT 1 as a station side device (station side communication device) and a plurality of ONUs 6_1 (ONU # 1) and 6_2 (ONU #) as a plurality of subscriber side devices (terminal side communication devices). 2) and 6_3 (ONU # 3).

  Further, the PON system shown in FIG. 1 includes a plurality of optical fibers 5_1 and 5 as a plurality of physical lines (optical transmission media) that transmit signals such as optical signals between the OLT 1 and a plurality of ONUs 6_1, 6_2, and 6_3. 5_2, 5_3, 5_4, and 5_5, and an optical splitter 4 as a splitter that is a device that branches a physical line (for example, an optical fiber).

  In the PON system shown in FIG. 1, a terminal device (hereinafter also simply referred to as “terminal”) is connected to each of the plurality of ONUs 6_1, 6_2, and 6_3. For example, the terminal device 7_1 (terminal device # 1) is connected to the ONU 6_1, the terminal device 7_2 (terminal device # 2) is connected to the ONU 6_2, and the terminal device 7_3 (terminal device 7_3 ( Terminal device # 3) is connected.

  The OLT 1 has a plurality of OSUs 2_1 (OSU # 1) and OSU2_2 (OSU # 2) including an active OSU (optical line unit) and a standby OSU, and any one of the plurality of OSUs 2_1 and 2_2. And a switch 3 for transferring a multicast packet as a data signal including video data and the like.

  The OSUs 2_1 and 2_2 are communicably connected to the ONUs 6_1, 6_2, and 6_3 through optical fibers 5_1, 5_2, 5_3, 5_4, and 5_5. Each of the plurality of OSUs 2_1 and 2_2 is connected to the switch 3. The OLT 1 performs Ethernet (registered trademark; hereinafter omitted) communication with the ONUs 6_1, 6_2, and 6_3 using the OSU 2_1 or 2_2. The OSUs 2_1 and 2_2 and the ONUs 6_1, 6_2, and 6_3 mutually transmit and receive MPCP (Multi-Point Control Protocol) messages (MPCP frames) as control frames defined in IEEE 802.3ah. For example, MPCP messages are transmitted and received between the OSUs 2_1 and 2_2 and the ONUs 6_1, 6_2, and 6_3, and ONUs 6_1, 6_2, and 6_3 are joined or disconnected, and uplink access control is performed.

  Normally, one of the plurality of OSUs (for example, OSU2_1) is operated as an active system, and the other OSUs (for example, OSU2_2) are on standby as standby systems. When a line abnormality (line failure) occurs in the active line (for example, a line communicating through OSU2_1), the multicast packet is transferred to the backup line (for example, a line communicating through OSU2_2). Each of the plurality of OSUs (for example, OSUs 2_1 and 2_2) is connected via the optical splitter 4. The standby OSU (for example, OSU2_2) stops the optical output (optical signal) while the active OSU (for example, OSU2_1) is in operation.

  The switch 3 transfers the multicast packet distributed from the upper network to any one of the plurality of OSUs 2_1 and 2_2. For example, when the OSU 2_1 as the active system is in operation, the switch 3 transfers a multicast packet to the OSU 2_1.

  When a line abnormality occurs in the active OSU 2_1, the switch 3 switches the multicast packet transfer destination to the standby OSU 2_2. That is, since the OLT 1 includes a plurality of OSUs 2_1 and 2_2, the PON system shown in FIG. 1 can be configured in a redundant configuration. If a line abnormality occurs in the standby OSU 2_2 after switching the multicast packet transfer destination to the standby OSU 2_2, the switch 3 switches the multicast packet transfer destination to the OSU 2_1 recovered from the line abnormality. Can do.

  The ONUs 6_1, 6_2, and 6_3 are communicably connected to the OSUs 2_1 and 2_2 via optical fibers (for example, optical fibers 5_1, 5_2, 5_3, 5_4, or 5_5). The ONUs 6_1, 6_2, and 6_3 perform Ethernet communication with the OSU 2_1 or 2_2 (that is, the OLT 1). For example, a multicast packet is transferred from one of the plurality of OSUs 2_1 and 2_2 to the ONUs 6_1, 6_2, and 6_3.

  The ONUs 6_1, 6_2, and 6_3 accommodate the terminal devices 7_1, 7_2, and 7_3 under their control and communicate with each other. The ONUs 6_1, 6_2, and 6_3 receive multicast control signals (hereinafter also simply referred to as “control signals”) for multicast packet viewing requests (reception requests) from the terminal devices 7_1, 7_2, and 7_3 under their control. The received multicast control signal is transmitted to the OSU (for example, OSU2_1 or 2_2) mounted on the OLT1. Further, if the multicast packet distributed from the OSU 2_1 or 2_2 is a packet to be transferred, the ONUs 6_1, 6_2, and 6_3 send the distributed multicast packets to the terminal devices 7_1, 7_2, and 7_3 connected to the respective subordinates. To deliver.

  The terminal devices 7_1, 7_2, and 7_3 are, for example, STBs (Set Top Boxes) used by subscribers of the PON system.

  FIG. 2 is a block diagram showing the configuration of the ONU 6_1 shown in FIG. However, in FIG. 2, one ONU 6_1 of the plurality of ONUs 6_1, 6_2, and 6_3 illustrated in FIG. 1 will be described as an example, but the configuration of the ONU 6_1 illustrated in FIG. 2 is the other ONU 6_2 illustrated in FIG. And 6_3 apply similarly.

  The ONU 6_1 includes a PON processing unit 10 as an optical network processing unit capable of generating a packet signal to be described later, a MAC (Media Access Control) address filter unit 11 as a physical address filter unit, and an OAM frame termination unit 12. Have. The ONU 6_1 can convert various electrical signals received from the terminal device 7_1 into optical signals (photoelectric conversion), and the various optical signals received from the OLT 1 can be converted into packet signals (for example, electrical signals) including video data. Can be converted to

  When the PON processing unit 10 receives a multicast control signal from the terminal device 7_1 as an upstream direction signal (upstream signal from the terminal devices 7_1, 7_2, and 7_3), the PON processing unit 10 converts the received multicast control signal into the received multicast control signal. An LLID (Logical Link Identifier) that is an identifier indicating its own ONU (ONU6_1 in the example shown in FIG. 2) is assigned, and the multicast control signal to which the LLID is assigned is transferred to the OLT1. The PON processing unit 10 can convert various electrical signals received from the terminal device 7_1 into optical signals (photoelectric conversion), and can transfer the optical signals toward the OLT 1. In addition, the place where the various electrical signals transferred from the terminal device 7_1 are converted into optical signals is not limited to the PON processing unit 10.

  The PON processing unit 10 can convert various optical signals received from the OLT 1 into packet signals (for example, photoelectric conversion), and transfers the converted packet signals to each unit in the ONU 6_1 or the terminal device 7_1. can do. Specifically, the PON processing unit 10 can convert a multicast packet received from the OSU 2_1 or 2_2 into a packet signal based on the received multicast packet and transfer the packet signal to each unit in the ONU 6_1 or the terminal device 7_1. However, in order to simplify the description in this specification, the packet signal transferred from the PON processing unit 10 to each unit in the ONU and the packet signal transferred from each ONU to the terminal device under each of them are referred to as “multicast”. This will also be described as “packet”. Note that the place where the various optical signals transferred from the OLT 1 are converted into packet signals is not limited to the PON processing unit 10.

  The PON processing unit 10 can detect a line abnormality between the OLT 1 and its own ONU (ONU6_1 in the example shown in FIG. 2). If a line abnormality is detected, the MAC address filter unit 11 detects a line abnormality. Notify the occurrence of For example, when a line abnormality occurs in the active OSU 2_1, the PON processing unit 10 detects a line abnormality in the active OSU 2_1 and transmits a line abnormality detection signal to the MAC address filter unit 11.

  When the PON processing unit 10 receives a unicast packet other than a multicast packet as data (downlink data or a downlink signal) in the downlink direction (direction from the upper network to the terminal devices 7_1, 7_2, and 7_3) from the OLT 1 , The assigned LLID is its own (ONU6_1 in the example shown in FIG. 2) unicast LLID. In this case, the received unicast packet is transferred to the OAM frame termination unit 12.

  When the PON processing unit 10 receives a multicast packet as downlink data (downlink data or a downlink signal) from the OLT 1, if the LLID assigned to the received multicast packet is a broadcast LLID, the PON processing unit 10 receives the multicast packet. The multicast packet is transferred to the MAC address filter unit 11.

  The OAM frame termination unit 12 terminates an OAM frame as a control frame among the packets with the unicast LLID transferred from the PON processing unit 10. Other unicast packets and the like are transferred to the terminal device (terminal device 7_1 in the example shown in FIG. 2). The OAM frame termination unit 12 transfers the MAC address as a physical address and a setting flag indicating registration or deletion of the MAC address stored in the terminated OAM frame to the MAC address filter unit 11.

  The MAC address filter unit 11 receives the multicast packet (specifically, a packet signal based on the multicast packet) transferred by the PON processing unit 10, and based on the MAC address assigned to the received multicast packet, The transmission (transfer) or discard of the received multicast packet is executed (the process of transmitting (forwarding) or discarding the multicast packet in the MAC address filter unit 11 is also referred to as “filter process”). However, when a line abnormality occurs (for example, when a notice of occurrence of a line abnormality of the active OSU2_1 is received from the PON processing unit 10), the MAC address filter unit 11 converts the multicast packet into a physical address (for example, The physical address filter state (MAC address filter state) that determines whether or not to transmit (transfer) based on the MAC address) is temporarily set to be transparent, and multicast packets can be transmitted (transferred) regardless of the physical address. it can.

  FIG. 3 is a sequence diagram showing a communication operation in the PON system shown in FIG. Based on FIG. 3, the line switching method and the communication method in the PON system shown in FIG. 1 will be specifically described.

  In the example shown in FIG. 3, a state is shown in which multicast packet CH1 (channel 1) and multicast packet CH2 (channel 2) are distributed from switch 3 to a plurality of terminal devices 7_1, 7_2, and 7_3. Yes. A case where the operation of the OLT 1 is started with the OSU2_1 as the active system and the OSU2_2 as the standby system will be described as an example. Therefore, in the example shown in FIG. 3, first, multicast packets CH1 and CH2 are distributed from the higher level network via the switch 3 (step S101), and are sent to the ONUs 6_1, 6_2, and 6_3 via the active OSU2_1. (Step S102).

  The ONUs 6_1, 6_2, and 6_3 generate packet signals based on the multicast packets CH1 and CH2 transferred from the active OSU 2_1, respectively (step S102). Specifically, the multicast packets CH1 and CH2 transferred to the ONUs 6_1, 6_2, and 6_3 are converted into packet signals in the respective PON processing units 10 (step S102).

  Since the ONUs 6_1, 6_2, and 6_3 have not received viewing requests (for example, control signals for starting viewing) from the terminal devices 7_1, 7_2, and 7_3, the multicast packets CH1 and CH2 are the ONUs 6_1, 6_2, and 6_3. It is discarded by the MAC address filter unit 11 and is not transferred to the terminal devices 7_1, 7_2, and 7_3 (step S102).

  The ONUs 6_1, 6_2, and 6_3 detect the presence / absence of a line abnormality. When the line abnormality P11 occurs in the working line (for example, a line communicating through the OSU 2_1), each of the ONUs 6_1, 6_2, and 6_3 detects the line abnormality P11 (step S103).

  When the line abnormality P11 occurs in the active OSU 2_1, the OSU 2_1 detects an input interruption (LOS: Loss of signal) of signals output from the ONUs 6_1, 6_2, and 6_3 (step S104). For example, when the OSU 2_1 does not receive a response signal for the control signal transmitted to the ONUs 6_1, 6_2, and 6_3 from the ONUs 6_1, 6_2, and 6_3, the OSU 2_1 can detect that the input is disconnected.

  For example, when the ONUs 6_1, 6_2, and 6_3 detect the line abnormality P11, respectively, when the terminal device 7_1 transmits a multicast control signal for the viewing request P12 of the multicast packet CH1 to the ONU 6_1, the line abnormality P11 of the OSU2_1. Thus, the multicast control signal does not reach OSU2_1, and OSU2_1 does not grasp the viewing request P12 of the multicast packet CH1 from the terminal device 7_1.

  The ONUs 6_1, 6_2, and 6_3 detect the line abnormality P11, and then send and receive MPCP messages to and from the standby OSU 2_2, thereby transferring the multicast packets CH1 and CH2 transferred from the switch 3 to each other. Is set to the standby OSU2_2 (step S105).

  When the forwarding destinations of the multicast packets CH1 and CH2 transferred from the switch 3 are set to the backup OSU2_2 (step S105), each of the plurality of ONUs 6_1, 6_2, and 6_3 (specifically, the MAC address filter unit) 11 MAC address filter state) shifts to a state in which multicast packets CH1 and CH2 transferred from the standby OSU2_2 are temporarily transmitted (hereinafter referred to as “transparent mode”) (step S106).

  When the ONUs 6_1, 6_2, and 6_3 and the standby OSU2_2 transmit and receive MPCP messages to each other (step S105), the OLT 1 switches the OSU that transfers the multicast packets CH1 and CH2 from the active OSU2_1 to the standby OSU2_2. The active OSU2_1 stops the optical output, and the standby OSU2_2 starts the optical output (step S107).

  The switch 3 transfers the multicast packets CH1 and CH2 distributed from the higher level network to the standby OSU2_2 (step S107). However, the timing at which each of the plurality of ONUs 6_1, 6_2, and 6_3 shifts to the transparent mode (step S106) is not necessarily greater than the timing at which the switch 3 transfers the multicast packets CH1 and CH2 to the standby OSU2_2 (step S107). There is no need to be ahead. For example, each of the plurality of ONUs 6_1, 6_2, and 6_3 shifts to the transparent mode at the same time or immediately after the timing when the switch 3 transfers the multicast packets CH1 and CH2 to the standby OSU2_2 (step S107) (step S106). May be.

  The OSU2_2 transfers the multicast packets CH1 and CH2 transferred from the switch 3 to the ONUs 6_1, 6_2, and 6_3 (step S108). The multicast packets CH1 and CH2 transferred to the ONUs 6_1, 6_2, and 6_3 are converted into packet signals in the respective PON processing units 10 (step S108).

  Each of the plurality of ONUs 6_1, 6_2, and 6_3 temporarily sets the physical address filter state that determines whether or not to forward the multicast packets CH1 and CH2 based on the MAC address during the transparent mode, to the standby system. Multicast packets (specifically, packet signals based on the multicast packets CH1 and CH2) transferred from the OSU2_2 are temporarily transferred (step S109).

  While each of the plurality of ONUs 6_1, 6_2, and 6_3 temporarily changes the physical address filter state to the transparent state (that is, during the transparent mode), multicast packets CH1 and CH2 (specifically, transferred from the standby OSU2_2) Are packet signals based on the multicast packets CH1 and CH2, respectively, regardless of whether there is a viewing request from a terminal device (for example, the terminal device 7_1, 7_2, or 7_3). Are transferred to terminal devices (for example, terminal devices 7_1, 7_2, and 7_3) under the control of the ONUs 6_1, 6_2, and 6_3) (step S109).

  After each of the plurality of ONUs 6_1, 6_2, and 6_3 enters the transparent mode and the multicast packets CH1 and CH2 are transferred to the terminal devices 7_1, 7_2, and 7_3, the OLT 1 (OSU2_2) transmits the multicast control signal to the ONU 6_1, 6_2 and 6_3 are transmitted to the terminal devices 7_1, 7_2, and 7_3, and an inquiry about the viewing state (reception state) of the multicast packets CH1 and CH2 by the terminal devices 7_1, 7_2, and 7_3 is executed (step S110).

  When any terminal device responds to the viewing request in response to the viewing state inquiry (step S110) transmitted by the OLT 1 (OSU2_2), the terminal device making the viewing request performs multicast control to the OSU2_2 via the ONU. A signal is transmitted (step S111). In the example shown in FIG. 3, since the terminal device 7_1 makes a channel 1 viewing request, in response to a viewing state inquiry from the OLT 1 (OSU2_2), a multicast control signal for receiving the multicast packet CH1 is sent to the ONU 6_1. Is transmitted to the OSU2_2 via (step S111).

  When the OSU2_2 receives the multicast control signal transmitted by the terminal device 7_1, the OLT 1 (OSU2_2) maintains the transmission of the multicast packet CH1 in the ONU 6_1 using the extended OAM frame as the control frame, and the channel 1 by the terminal device 7_1. Can be maintained (step S112).

  When OSU2_2 receives the multicast control signal for viewing request from the terminal device 7_1, OLT1 (OSU2_2) uses the extended OAM frame as the control frame to transmit the transparent state to ONUs 6_1, 6_2, and 6_3 under OSU2_2. A release instruction (stop instruction) is transmitted (step S112), and the temporary transparent state of the physical address filter state in the ONUs 6_1, 6_2, and 6_3 can be terminated (step S113). That is, the OLT 1 (OSU2_2) executes the inquiry about the viewing state of the multicast packets CH1 and CH2 by the terminal devices 7_1, 7_2, and 7_3 (steps S110 and S111), and then uses the extended OAM frame to turn on the ONUs 6_1, 6_2, and 6_3. The transmission mode can be terminated (steps S112 and S113).

  When the transparent mode ends in the ONUs 6_1, 6_2, and 6_3 under the OSU2_2, the MAC address filter unit 11 in the ONUs 6_1, 6_2, and 6_3 is based on the MAC address assigned to the multicast packet transferred from the OSU2_2. The transmission (transmission) or discarding of the multicast packet (specifically, a packet signal based on the multicast packet) is resumed.

  The switch 3 continues to transfer the multicast packets CH1 and CH2 distributed from the upper network to the OSU2_2 (step S114). The OSU2_2 transfers the multicast packets CH1 and CH2 transferred from the switch 3 to the ONUs 6_1, 6_2, and 6_3 (step S115). The multicast packets CH1 and CH2 transferred to the ONUs 6_1, 6_2, and 6_3 are converted into packet signals in the respective PON processing units 10 (step S115).

  The terminal device 7_1 responds to the OSU2_2 with a multicast control signal as a viewing request for channel 1 (step S111) in response to the viewing state inquiry by the OSU2_2 (step S110). The viewing of channel 1 (reception of the multicast packet CH1) by the terminal device 7_1 is maintained (step S116).

  After the end of the transparent mode, the multicast packets CH1 and CH2 are discarded by the MAC address filter unit 11 of the ONUs 6_2 and 6_3 until a viewing request for channel 1 or channel 2 is transmitted by the terminal devices 7_2 and 7_3.

  In the example shown in FIG. 3, the multicast packets CH1 and CH2 are requests for viewing requests from terminal devices (for example, terminal devices 7_1, 7_2, and 7_3) from when the transparent mode is started until the transparent mode is ended. Regardless of the presence or absence, it has been transferred to the terminal devices (for example, terminal devices 7_1, 7_2, and 7_3) connected to each of the ONUs (for example, ONUs 6_1, 6_2, and 6_3) (step S109). When the mode ends, the transfer of the multicast packets CH1 and CH2 to the terminal devices 7_2 and 7_3 that have not responded to the viewing request by the OSU 2_2 (step S110) is stopped. Therefore, by stopping the transfer of the multicast packets CH1 and CH2 to the terminal devices 7_2 and 7_3 that have not requested viewing, it is possible to prevent the transfer of extra multicast packets and reduce the line load.

  In the example shown in FIG. 3, the multicast packets CH1 and CH2 are multicast packets regardless of whether or not the terminal device 7_1 requests to view channel 2 from the start of the transparent mode to the end of the transparent mode. Although CH2 has been transferred to the terminal device 7_1 (step S109), when the transparent mode ends, the response to the viewing request for channel 2 (step S110) by the OSU2_2 has not been answered. Transfer of the multicast packet CH2 to the terminal device 7_1 is stopped. Therefore, by stopping the transfer of the multicast packet CH2 to the terminal device 7_1 that has not requested viewing of the channel 2, it is possible to prevent the transfer of an extra multicast packet and reduce the line load.

  According to the first embodiment, when a viewing request is transmitted from one of the terminal devices (for example, the terminal device 7_1), a line abnormality occurs on the active line (for example, a line that communicates through the OSU 2_1). Also, from the time of occurrence of line abnormality of the working system line to the time when the terminal device (for example, the terminal devices 7_1, 7_2, and 7_3) inquires about the viewing state (reception state), or the working system line. Multicast packets are transmitted to the terminal devices (for example, the terminal devices 7_1, 7_2, and 7_3) from when the abnormality occurs until the viewing request is transmitted again from the terminal device (for example, the terminal device 7_1) after the line switching is completed. Since CH1 and CH2 are transferred, the terminal device (for example, the terminal device 7_1) that has transmitted the viewing request, after the line abnormality occurs, Reception of a ticket (ie, viewing of a channel) can be started early.

Embodiment 2. FIG.
FIG. 4 is a sequence diagram showing a communication operation in the PON system for realizing the line switching method according to the second embodiment of the present invention. In the second embodiment, the constituent elements constituting the PON system as the communication system are the same as the constituent elements constituting the PON system described in the first embodiment with reference to FIGS.

  As shown in FIG. 4, in the second embodiment, when a line abnormality P11 occurs in the working line (for example, a line communicating through OSU2_1), the working OSU (for example, OSU2_1) is connected to the PON system. At the timing when the input interruption from each ONU is detected (step S104), the ONUs 6_1, 6_2, and 6_3 shift to the transparent mode (step S205), and the switching unit 3 sets the forwarding destination of the multicast packets CH1 and CH2 to the backup OSU (For example, OSU2_2) (step S206) is different from the communication operation in the first embodiment, and the other points are the same as the communication operation in the first embodiment. Therefore, in the second embodiment, the components and signals described in the first embodiment and the components, signals, and operations that are the same as or correspond to the operations in the steps illustrated in FIG. 3 are described in the first embodiment. The same reference numerals as those of the constituent elements and signals and the operations in the respective steps shown in FIG.

  The difference between the communication operation in the first embodiment and the communication operation in the second embodiment will be specifically described. In the first embodiment, after the active OSU 2_1 detects an input interruption (step S104), transmission / reception of an MPCP message (step S105) is started between the standby OSU 2_2 and the ONUs 6_1, 6_2, and 6_3. In the second embodiment, MPCP message transmission / reception (step S207) is performed between the standby OSU 2_2 and the ONUs 6_1, 6_2, and 6_3 after the active OSU 2_1 detects an input interruption (step S104). Before starting, the ONUs 6_1, 6_2, and 6_3 enter the transparent mode (step S205), and the multicast packets CH1 and CH2 (specifically, packet signals based on the multicast packets CH1 and CH2, respectively) are transmitted to the terminal devices (for example, Are transferred to the terminal devices 7_1, 7_2, and 7_3). (S206, S108, S109). Even when a line abnormality occurs in the active OSU 2_1, since the communication link between the ONUs 6_1, 6_2, and 6_3 and the standby OSU 2_2 is established, the terminal devices (for example, the terminal devices 7_1 and 7_2) are established. , And 7_3) can receive downlink signals (for example, multicast packets CH1 and CH2).

  However, the timing at which each of the plurality of ONUs 6_1, 6_2, and 6_3 shifts to the transparent mode (step S205) is not necessarily the timing at which the switch 3 transfers the multicast packets CH1 and CH2 to the standby OSU2_2 (step S206). There is no need to be ahead. For example, each of the plurality of ONUs 6_1, 6_2, and 6_3 shifts to the transparent mode at the same time or immediately after the timing when the switch 3 transfers the multicast packets CH1 and CH2 to the standby OSU2_2 (step S206) (step S205). May be.

  After the multicast packets CH1 and CH2 are transferred to the terminal devices (for example, the terminal devices 7_1, 7_2, and 7_3) (steps S206, S108, and S109), the ONUs 6_1, 6_2, and 6_3 are respectively connected to the standby OSU2_2. Then, the MPCP message is transmitted / received, and for example, uplink access control between the ONUs 6_1, 6_2, 6_3 and the OSU 2_2 is executed (step S207).

  According to the second embodiment, when a viewing request is transmitted from one of the terminal devices (for example, the terminal device 7_1), a line abnormality occurs in the active line (for example, a line that communicates through the OSU 2_1). Also, after the active OSU (eg, OSU2_1) detects the disconnection of the signal from the ONU (eg, ONUs 6_1, 6_2, and 6_3) (step S104), the standby OSU (eg, OSU2_2) ONUs (for example, ONUs 6_1, 6_2, and 6_3) shift to the transparent mode (step S207) before the MPCP message transmission / reception (step S207) is started between them and the ONUs (for example, ONUs 6_1, 6_2, and 6_3) (steps S207). S205), multicast packets CH1 and CH2 are transferred to the terminal devices (for example, terminal devices 7_1, 7_2, and 7_3). (Steps S206, S108, and S109), the terminal device (for example, the terminal device 7_1) that transmitted the viewing request receives the requested multicast packet (that is, viewing the channel) as compared to the first embodiment. You can start even earlier.

  In each of the embodiments described above, the case where the number of channels distributed from the upper network is two channels (that is, multicast packets CH1 and CH2) has been described as an example. However, the number of channels distributed from the upper network is described. May be one channel or three or more channels.

  In each of the embodiments described above, the case where the number of OSUs provided in the OLT 1 is two has been described as an example (that is, OSU2_1 and 2_2), but the number of OSUs may be three or more.

  In each of the embodiments described above, the case where the number of ONUs is three (that is, ONUs 6_1, 6_2, and 6_3) has been described as an example, but the number of ONUs is not limited to three.

First modified example.
FIG. 5 is a block diagram showing a configuration of the OLT 21 provided in the PON system as a first modification of the PON system for realizing the line switching method described in the first and second embodiments. The OLT 21 is different from the OLT 1 shown in FIG. 1 in that the OLT 21 has a control unit 8 (first control unit) that controls the switch 3 and a plurality of OSUs (for example, OSUs 2_1 and 2_2). It is the same as OLT1 shown. Therefore, in FIG. 5, the same components as those included in the OLT 1 shown in FIG. 1 are denoted by the same reference numerals as those included in the OLT 1, and description thereof is omitted. The control unit 8 can control the switch 3 so that the multicast packets CH1 and CH2 transferred by the switch 3 are transferred to any one of the plurality of OSUs 2_1 and 2_2. Further, the control unit 8 can control on / off of the optical outputs of the OSUs 2_1 and 2_2.

FIG. 6 is a block diagram showing a configuration of the control unit 8 shown in FIG.
The control unit 8 includes a processor 81 such as a CPU (Central Processing Unit), a ROM (Read Only Memory) 82, and a RAM (Random Access Memory) 83. The ROM 82 stores a program for controlling each component in the OLT 21. The RAM 83 is used as a storage area for loading a program or the like stored in the ROM 82. For example, the processor 81 loads a program into the RAM 83 and executes control of each component in the OLT 21.

Second modification.
FIG. 7 is a block diagram showing a configuration of the ONU 26 provided in the PON system as a second modification of the PON system for realizing the line switching method described in the first and second embodiments. The configuration of the ONU 26 shown in FIG. 7 is applicable to any one or more of the ONUs 6_1, 6_2, and 6_3 shown in FIG. The ONU 26 is different from the ONU 6_1 shown in FIG. 2 in that the ONU 26 includes a control unit 13 (second control unit) that controls the PON processing unit 10, the MAC address filter unit 11, and the OAM frame termination unit 12. This is the same as the ONU 6_1 shown in FIG. Therefore, in FIG. 7, the same components as those included in the ONU 6_1 shown in FIG. 2 are denoted by the same reference numerals as those included in the ONU 6_1, and description thereof is omitted.

  The control unit 13 can control the operations of the PON processing unit 10, the MAC address filter unit 11, and the OAM frame termination unit 12. For example, in each of the plurality of ONUs 6_1, 6_2, and 6_3, the control unit 13 transmits multicast packets (specifically, packet signals based on the multicast packets CH1 and CH2 respectively) transferred from the standby OSU (eg, OSU2_2). ) To the terminal devices 7_1, 7_2, and 7_3. For example, during the transparent mode (steps S106 and S205), the control unit 13 controls the MAC address filter unit 11 so that the physical address filter state in the MAC address filter unit 11 transitions to a temporary transparent state, and the standby system. Multicast packets (specifically, packet signals based on the multicast packets CH1 and CH2) transferred from the OSU (for example, OSU2_2) can be controlled to be temporarily transmitted in the MAC address filter unit 11.

FIG. 8 is a block diagram showing a configuration of the control unit 13 shown in FIG.
The control unit 13 includes a processor 131 such as a CPU, a ROM 132, and a RAM 133. The ROM 132 stores a program for controlling each component in the ONU 26 and the like. The RAM 133 is used as a storage area for loading a program or the like stored in the ROM 132. For example, the processor 131 loads a program into the RAM 133 and executes control of each component in the ONU 26.

  The first modified example and the second modified example described above can be applied to the PON system described in the first and second embodiments in an appropriate combination with each other.

  1 OLT (station side equipment), 2_1, 2_2 OSU (optical line unit), 3 switch, 4 optical splitter, 5_1, 5_2, 5_3, 5_4, 5_5 optical fiber, 6_1, 6_2, 6_3 ONU (subscriber side equipment) 7_1, 7_2, 7_3 terminal device, 8 control unit (first control unit), 10 PON processing unit, 11 MAC address filter unit, 12 OAM frame termination unit, 13 control unit (second control unit).

Claims (13)

A station-side apparatus having a plurality of optical line units including an active optical line unit and a standby optical line unit; a multicast packet is transferred from any of the plurality of optical line units; A line switching method in a communication system including a subscriber side device for performing communication,
The subscriber side device generating a packet signal based on the multicast packet transferred from any of the plurality of optical line units;
When a line abnormality occurs, the station side device switches the optical line unit for transferring the multicast packet from the working optical line unit to the standby optical line unit;
The subscriber-side device temporarily setting a physical address filter state for determining whether or not to transfer a packet signal based on a multicast packet transferred from the standby optical line unit to the terminal; A line switching method characterized by comprising:   The line switching method according to claim 1, further comprising a step in which the subscriber side device detects presence / absence of the line abnormality. In the step of temporarily setting the physical address filter state to a transparent state,
While the subscriber-side device temporarily changes the physical address filter state to the transparent state, the packet signal based on the multicast packet transferred from the backup optical line unit is determined based on whether there is a viewing request from the terminal. Regardless, the line switching method according to claim 1, wherein the line switching method is transferred to the terminal.   The line switching method according to any one of claims 1 to 3, wherein the station side device further includes a step of executing a viewing state inquiry by the terminal.   The station side device further includes a step of ending the temporary transparent state of the physical address filter state in the subscriber side device using a control frame after executing the viewing state inquiry. The line switching method according to claim 4. The station side device has a switch for transferring the multicast packet to any of the plurality of optical line units,
The step of the station side device switching the optical line unit for transferring the multicast packet from the active optical line unit to the standby optical line unit,
The line switching method according to any one of claims 1 to 5, wherein the switch is executed by transferring the multicast packet to the protection optical line unit. The station side device has a first control unit,
The step of the station side device switching the optical line unit for transferring the multicast packet from the active optical line unit to the standby optical line unit,
The line switching method according to claim 6, wherein the first control unit is executed by controlling the switch. The subscriber side device has a physical address filter unit that receives a packet signal based on a multicast packet transferred from the standby optical line unit;
The step of temporarily setting the physical address filter state to a transparent state;
The line switching method according to any one of claims 1 to 7, wherein the line switching method is executed when the physical address filter state in the physical address filter unit shifts to a temporary transparent state. The subscriber side device has a second control unit,
The step of temporarily setting the physical address filter state to a transparent state;
The line switching method according to claim 8, wherein the second control unit is executed by controlling the physical address filter unit. The step in which the subscriber side apparatus temporarily sets a physical address filter state for determining whether or not to transfer a packet signal based on the multicast packet transferred from the protection optical line unit to the terminal, to a transparent state. In
The physical address filter state in the subscriber side device determines whether or not to transfer the packet signal to the terminal based on a MAC address assigned to a packet signal based on the multicast packet. The line switching method according to any one of 1 to 9. A station-side apparatus having a plurality of optical line units including an active optical line unit and a standby optical line unit; a multicast packet is transferred from any of the plurality of optical line units; A communication method in a communication system comprising a subscriber side device for communication,
The subscriber side device generating a packet signal based on the multicast packet transferred from any of the plurality of optical line units;
Temporarily setting a physical address filter state that determines whether or not to transfer a packet signal based on a multicast packet transferred from the standby optical line unit to the terminal when a line abnormality occurs; A communication method characterized by comprising: A multicast packet is forwarded from one of the optical line units in the station side apparatus having a plurality of optical line units including the active optical line unit and the standby optical line unit, and at the same time, communicates with the subordinate terminal. A person-side device,
An optical network processing unit for generating a packet signal based on the multicast packet;
A physical address filter unit that receives a packet signal based on the multicast packet transferred from the optical network processing unit;
When a line abnormality occurs, the physical address filter state in the physical address filter unit temporarily determines whether to transfer a packet signal based on the multicast packet transferred from the standby optical line unit to the terminal. A subscriber-side device that shifts to a transparent state. While the physical address filter state in the physical address filter unit is a temporarily transparent state, the packet signal based on the multicast packet transferred from the backup optical line unit is related to whether or not there is a viewing request from the terminal. The subscriber-side device according to claim 12, wherein the subscriber-side device is transferred to the terminal.

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