JP2010057110A - Optical access system, optical communication path switching device, and optical line terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that discovery of an ONU which has requested a connection is delayed. <P>SOLUTION: An optical access system includes: an optical line terminal (OLT); a plurality of optical network units (ONUs); and an optical communication path switching device for switching an optical communication path between the OLT and each ONU. In the optical access system, in a case where an ONU is not registered in the OLT, the ONU transmits a connection request signal. The optical communication path switching device has a detector for detecting presence/no presence of a signal from the ONU and in a case where the signal of the non-registered ONU is detected, notifies the OLT about the number of detected non-registered ONUs. In accordance with the notified number of non-registered ONUs, the OLT performs discovery processing to the ONU that has requested the connection. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical access system, and more particularly to a technique for discovering an optical network device (Optical Network Unit) at high speed in an optical access system using an optical switch instead of an optical splitter.

  In recent years, FTTH (Fiber To The Home) using optical fibers has become widespread, and access networks have become faster. A typical example of FTTH is a PON (Passive Optical Network) system.

  As shown in FIG. 15, the PON system includes a plurality (N) of optical network devices (Optical Network Unit) 20 that communicate with the user terminal 10 and an optical line device (Optical Line) that communicates with the backbone network 60 via the gateway 50. Terminal) 40. The plurality of ONUs 20 and the OLT 40 are connected via an optical splitter 80 that is a passive element that does not require power supply. Thus, the PON system is a system that can realize an inexpensive access network 70.

  For example, IEEE 802.3ah (Non-Patent Document 1) standardizes EPON (Ethernet-PON) for transferring data between OLT and ONU in accordance with Ethernet (registered trademark; the same applies hereinafter). In addition, standardization of 10G-EPON with a transmission rate increased to 10 Gbps is being promoted (IEEE 802.3av (Non-Patent Document 2)).

  Since the PON represented by the above-described EPON and 10G-EPON uses an optical splitter, the optical power reaching the ONU is attenuated in inverse proportion to the number of branches (maximum accommodation number of ONUs). That is, when the number of branches is large, there is a problem that the transmission distance and the number of users that can be accommodated are limited. Also, since the downstream optical signal from the OLT to the ONU is distributed to all the ONUs, encryption is essential. Even with encryption, there is a limit to the confidentiality of communication.

  In order to solve these PON problems, there is a system including an active optical switch 90 instead of a passive optical splitter, as shown in FIG. In particular, the transmission distance and the number of users that can be accommodated can be increased by using an optical switch whose pass attenuation is close to zero. In addition, since the optical switch can be controlled so as to transmit a signal only to a specific user, it is possible to improve the confidentiality of communication without using encryption.

  An optical network system using such an optical switch is disclosed in Patent Document 1 and Patent Document 2.

  The general optical switch 90 shown in FIG. 16 can connect one route or disconnect all routes, and therefore cannot broadcast data to all the routes. Therefore, the discovery process used in the conventional EPON and 10G-EPON cannot be applied as it is.

  Here, the discovery process in the conventional EPON and 10G-EPON will be described.

  The discovery process detects an unregistered ONU using a common optical communication path, registers the detected ONU, and measures a communication distance (RTT (Round Trip Time)) between the ONU and the OLT. It is processing. With the discovery process, it is possible to control the optical splitter or the optical switch so that communication does not collide. Finally, the OLT distinguishes registered ONUs by an identifier (LLID (Logical Link ID)). FIG. 7 shows a sequence of discovery procedures in the conventional EPON and 10G-EPON.

  In the discovery process, first, since the ONU 20 is in an unregistered state, the OLT 40 uses the Discovery GATE message SIG 20 to confirm the existence of an ONU whose LLID is not determined. Discovery GATE message The SIG 20 can be distinguished from a normal GATE message by setting the Discovery flag in the message to “1”. In addition, an identifier defined for broadcasting is used as the LLID, and a multicast address is used as the destination MAC address.

  The Discovery GATE message SIG 20 transmitted from the OLT 40 arrives at all ONUs 20 connected to the optical splitter 80 via the optical splitter 80. When the unregistered ONU 20 to which no LLID has been assigned yet receives the Discovery GATE message SIG20, it transmits a REGISTER_REQ message SIG30 to request registration to the OLT 40.

  At this time, it is necessary to avoid a plurality of REGISTER_REQ messages SIG30 from colliding in the section from the optical splitter 80 to the OLT 40, but the collision cannot be completely avoided. Therefore, in order to reduce the probability of collision, each unregistered ONU 20 transmits a REGISTER_REQ message SIG30 at a time T3 waiting for a random time from the transmission start time T2 written in the Discovery GATE message SIG20.

  When the OLT 40 receives the REGISTER_REQ message SIG30 within the time specified as the Discovery Window, the OLT 40 acquires the MAC address of the ONU 20 that transmitted the REGISTER_REQ message SIG30, and manages the correspondence between the acquired MAC address of the ONU 20 and the LLID. Also, a process for assigning an LLID to the ONU 20 is started.

  In order to notify the ONU 20 of the assigned LLID, the OLT 40 transmits a REGISTER message SIG 40 in which the MAC address of the ONU 20 is a destination MAC address and the LLID is written. When the ONU 20 having this destination MAC address receives the REGISTER message SIG 40, it acquires the assigned LLID. Thereafter, the transmission source ONU 20 can be specified by transmitting the preamble of the frame transmitted by the ONU 20 including the assigned LLID. Further, it is possible to determine whether the frame transmitted from the OLT 40 is a frame addressed to itself by the preamble LLID.

  Thereafter, in order to measure the round-trip time RTT between the OLT 40 and the ONU 20, the OLT 40 transmits a GATE message SIG50 in which the ONU 20 is designated by LLID, the destination MAC address is a multicast address, and the Discovery flag is “0”.

  When the ONU 20 having the specified LLID receives the GATE message SIG50, it acquires time information (Time Stamp) T6 and transmission start time (Grant Start Time) T7 included in the GATE message SIG50. Then, the time information T6 is set in the clock of the ONU 20, and the REGISTER_ACK message SIG60 is transmitted to the OLT 40 at the transmission start time T7 with the set clock.

  The OLT 40 receives the REGISTER_ACK message SIG60 at time T8 with its own clock. Then, the OLT 40 can acquire the round-trip time RTT between the OLT 40 and the ONU 20 as RTT = T8−T7 from T8 and T7 included in the received REGISTER_ACK message SIG60.

  With the above sequence, registration of one ONU 20 (assignment of LLID) and measurement of the communication distance RTT are completed. When there are a plurality of unregistered ONUs, one Discovery GATE message SIG20, a plurality of REGISTER_REQ messages SIG30, a REGISTER message SIG40, a GATE message SIG50, and a REGISTER_ACK message SIG60 are exchanged in one discovery sequence. A plurality of ONUs can be registered by repeating the exchange of messages.

  Next, discovery processing in a system including the optical switch 90 instead of the optical splitter 80 will be described. In a system including the optical switch 90, it is necessary to first perform discovery processing for the optical switch 90. The discovery process for the optical switch 90 may be performed by considering the optical switch 90 as an ONU and using the conventional discovery process of the ONU 20 shown in FIG. After the OLT 40 registers the optical switch 90, discovery processing is performed on the ONU 20 connected to the tip of the optical switch 90.

  FIG. 8 shows a sequence of a discovery procedure when the number of unregistered ONUs is five and two ONUs can respond but three ONUs cannot respond.

  In the case of a system including an optical switch, broadcast cannot be used, unlike the case of a system including an optical splitter. For this reason, in discovery, it is necessary to check each unregistered ONU 20 using unicast. At this time, the ONU 20 may not be connected to the optical switch port, the ONU 20 may not be turned on, or the ONU 20 may not respond for some reason.

  In the sequence shown in FIG. 8, first, in order to register the first ONU 20, the OLT 40 sets the output port (destination) of the downstream optical switch of the optical switch 90 and the input port (transmission source) of the upstream optical switch. A switch port fixing message SIG10-1 for fixing is transmitted. Then, the optical switch 90 selects one of the unregistered ONUs 20 and fixes the optical communication path. Here, since the ports of the optical switch are fixed, all discovery processing messages are transferred between the single ONU 20 and the OLT 40.

  Next, the OLT 40 transmits a Discovery GATE message SIG 20-1 for discovery of the first ONU 20. At this time, since the port of the optical switch is fixed, there is no possibility that another ONU 20 and a signal collide on the optical communication path. Therefore, the ONU 20 does not need to wait for a random time when returning the REGISTER_REQ message. At this time, since the OLT 40 does not know the synchronization time (Sync Time) of the ONU 20, it performs burst transfer of a sufficiently long Sync Pattern (Burst Preamble).

  In the sequence shown in FIG. 8, the first discovery process cannot respond to the Discovery GATE message SIG20-1. Even in this case, the OLT 40 waits for a reply of the REGISTER_REQ message from the ONU 20 for the time specified by the Discovery Window, but because there is no response, the OLT 40 times out and moves to the next ONU 20 discovery process.

  For the second discovery process, the OLT 40 transmits a switch port fixed message SIG10-2, and then transmits a Discovery GATE message SIG20-2. Since there is an ONU 20 that reacts to this discovery, processing similar to that in the normal discovery phase shown in FIG. 7 (messages SIG30-2, SIG40-2, SIG50-2, and SIG60-) is performed between the ONU 20 and the OLT 40. 2).

  Thereafter, the third to fifth discovery processes are performed. In the sequence shown in FIG. 8, the discovery succeeds twice out of the five discoverys, but the response to the Discovery GATE message times out three times and the discovery fails.

  The frequency of the discovery process is not stipulated by the standards according to Non-Patent Document 1 and Non-Patent Document 2. An example of a combination of the discovery phase and the normal transfer phase is shown in FIG. As shown in the figure, a certain period of time is divided into N phases, one of which is a discovery phase and the remaining N-1 phase is a normal transfer phase as one communication set, and the processing of this phase is repeated.

  FIG. 21 shows a procedure for executing the above-described discovery phase and normal transfer phase. The OLT 40 executes the normal transfer phase S101 after executing the discovery phase S100. In S102, the number of normal transfer phases is confirmed. If the number of normal transfer phases has not reached a predetermined value (N times), the normal transfer phase S101 is repeated. On the other hand, if the number of normal transfer phases has reached a predetermined value (N times), the discovery phase S100 is executed again.

The length of one discovery phase is the time required to register all ONUs at the maximum. In one normal transfer phase, one or more ONUs 20 registered in the OLT 40 each transfer data at a predetermined time according to an instruction from the OLT 40. Further, the OLT 40 transfers data to the ONU 20.
JP 2007-174123 A JP 2007-67948 A IEEE Std 802.3ah IEEE Std 802.3av

  In the optical network system including the conventional optical switch 90 described above, since broadcasting cannot be used in the optical switch, as shown in FIG. 8, during the discovery process, the Discovery GATE message is sent to the ONU 20 to which the OLT 40 does not request connection. May be sent. As a result, there is a problem that discovery of the ONU 20 that requested the connection is delayed.

  A typical example of the present invention is as follows. That is, an optical line device connected to another network, a plurality of optical network devices each connected to a user terminal, and the optical line device installed between the optical line device and the optical network device, In an optical access system including an optical communication path switching device that switches an optical communication path between the plurality of optical network devices, the optical network device transmits a connection request signal when the optical network device is not registered in the optical line device. The optical communication path switching device includes a detector that detects the presence / absence of a signal from the optical network device, and the optical communication path switching device detects a signal from the unregistered optical network device. The optical line device is notified of the number of detected unregistered optical network devices, and the optical line device notifies the notified unregistered optical network device. As the number of location, is an optical access system, which comprises carrying out the discovery process with respect to the optical network device that requested the connection.

  According to the present invention, in an optical access system using an optical switch, discovery processing is preferentially performed for an ONU that requests connection, so that high-speed discovery processing is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
FIG. 1 is a diagram showing a configuration of an optical access system according to a first embodiment of this invention.

  The optical access system 70 includes an optical network device (ONU) 20, an optical communication path switching device (OSW) 30, and an optical line device (OLT) 40.

  A plurality of ONUs (Optical Network Units) 20 are provided according to the number of users, and are connected to the user terminals 10 to communicate with the user terminals 10. An OLT (Optical Line Terminal) 40 is connected to the gateway 50 and communicates with the backbone network 60 via the gateway 50. The OSW 30 connects the plurality of ONUs 20 and the OLT 40 and actively switches the path between the ONU 20 and the OLT 40. The optical switch of the OSW 30 includes a power monitor that detects a signal from the ONU 20.

  FIG. 2 is a block diagram illustrating a configuration of the OSW 30 according to the first embodiment.

  As described above, the OSW 30 includes the multiplexer / demultiplexer 360, the multiplexer / demultiplexer 361, the optical splitter 340, the downstream optical switch 311, the upstream optical switch 312, the 2-to-1 optical switch 350, the power monitor 313, the O / E converter 341, reception PHY / MAC logic circuit 342, port management logic circuit 343, transmission PHY / MAC logic circuit 344, E / O converter 345, driver input generation logic circuit 330, downstream optical switch driver 321 and An upstream optical switch driver 322 is provided.

  Multiplexers / demultiplexers 360 are provided (360-1 to N), receive optical signals from the ONU 20 side, and transmit optical signals to the ONU 20 side. The multiplexer / demultiplexer 361 receives the optical signal from the OLT 40 side and transmits the optical signal to the OLT 40 side. The optical splitter 340 demultiplexes downstream optical communication into the ONU 20 side and the OSW 30. In order to prevent the loss of the optical signal, a 2-to-1 optical switch may be used at the position of the optical splitter 340. The downstream optical switch 311 switches the optical communication path for downstream. The upstream optical switch 312 switches the upstream optical communication path. The power monitor 313 detects whether or not an optical signal is input to the upstream optical switch 312.

  The O / E converter 341 converts the optical signal demultiplexed from the optical splitter 340 into an electric signal. The reception PHY / MAC logic circuit 342 reads frame information from an electrical signal (MPCP (Multipoint Control Protocol) frame) converted from an optical signal. The port management logic circuit 343 manages the relationship between each port of the OSW 30 and the LLID. The transmission PHY / MAC logic circuit 344 analyzes the electrical signal from the power monitor 313 and generates an MPCP frame for transmission to the OLT 40. Then, the electrical signal is converted into an optical signal by the E / O converter 345 and transmitted as an optical signal via the 2-to-1 optical switch 350. The driver input generation logic circuit 330 receives the control signal from the port management logic circuit 343 and controls the downstream optical switch 311 and the upstream optical switch 312 via the downstream optical switch driver 321 and the upstream optical switch driver 322, respectively.

  FIG. 3A is a block diagram illustrating a configuration of the downstream optical switch 311 according to the first embodiment. The upstream optical switch 312 shown in FIG. 3B has the same configuration as the downstream optical switch 311.

  In the optical switch 311, two-to-one element optical switches are arranged in a tree shape. The optical switch 311 can control whether one of the two paths in the element optical switch is connected or both of the two paths are disconnected by a control signal input from the outside. For this reason, as the entire optical switch 311, only one route can be connected or all the routes can be disconnected. The optical switch may be any configuration as long as it can logically realize an N-to-1 configuration.

  FIG. 9 is a block diagram illustrating a configuration of the OLT 40 according to the first embodiment.

  The OLT 40 includes a multiplexer / demultiplexer 400, an O / E converter 411, a reception-side PHY / MAC logic circuit 412, a transmission-side PHY / MAC logic circuit 402, an MPCP control logic circuit 420, and a gateway-side PHY / MAC logic circuit 430. And a gateway interface 440.

  The multiplexer / demultiplexer 400 receives the optical signal from the OSW 30 side and transmits the optical signal to the OSW 30 side. The O / E converter 411 converts the received optical signal into an electrical signal. The reception side PHY / MAC logic circuit 412 controls the frame received from the OSW 30. The transmission side PHY / MAC logic circuit 402 controls a frame to be transmitted to the OSW 30. The MPCP control logic circuit 420 controls the plurality of ONUs 20 by the MPCP frame. The gateway-side PHY / MAC logic circuit 430 controls frames transmitted and received on the gateway side. The gateway interface 440 is an interface with the gateway 50.

  The hardware configuration of the OLT 40 of the present embodiment is the same as the hardware configuration of the conventional OLT 40, but the discovery process executed by the MPCP control logic circuit 420 is different.

  FIG. 10 is a block diagram illustrating a configuration of the ONU 20 according to the first embodiment.

  The ONU 20 includes a multiplexer / demultiplexer 200, an O / E converter 211, a reception side PHY / MAC logic circuit 212, a transmission side PHY / MAC logic circuit 202, an MPCP control logic circuit 220, and a terminal side PHY / MAC logic circuit 230. And a terminal interface 240.

  The multiplexer / demultiplexer 200 receives the optical signal from the OSW 30 side and transmits the optical signal to the OSW 30 side. The O / E converter 211 converts the received optical signal into an electrical signal. The receiving side PHY / MAC logic circuit 212 controls the frame received from the OSW 30. The transmission side PHY / MAC logic circuit 202 controls a frame to be transmitted to the OSW 30. The MPCP control logic circuit 220 is a logic circuit for communicating with the OLT 40. The terminal-side PHY / MAC logic circuit 230 controls frames transmitted and received on the terminal side. The terminal interface 240 is an interface with the user terminal 10.

  Note that the hardware configuration of the ONU 20 of the present embodiment is the same as the hardware configuration of the conventional ONU 20, but the discovery process executed by the MPCP control logic circuit 220 is different. Further, the ONU 20 of the present embodiment is different from the conventional ONU 20 in that it requests connection to the OLT 40 when it is not registered in the OLT 40. The connection request is realized by turning on the laser and continuously sending some value. Note that after being registered in the OLT 40 by the discovery process, the laser is turned on only during normal data transfer.

  The present embodiment is characterized in that the upstream optical switch 312 includes a power monitor 313. Therefore, a high-speed discovery method using the power monitor 313 will be described.

  When the ONU 20 that is not registered in the OLT 40 wants to connect to the optical access network 70, it operates the light emitting element (laser) and continues to send a specific signal to the OSW 30. Here, unlike the optical splitter, the upstream optical switch 312 of the OSW 30 is controlled so that only one ONU 20 and the OLT 40 are connected at the same time. Therefore, the optical signal in the laser ON state transmitted from the unregistered ONU 20 Normal communication with the ONU 20 is not hindered.

  FIG. 11 is a sequence diagram illustrating a discovery procedure according to the first embodiment. An example sequence 900 when there is no connection request from the ONU 20 and an example sequence 901 when one ONU 20 requests connection are shown. including.

  First, an example 900 when there is no ONU 20 that makes a connection request will be described.

  The OLT 40 transmits a Discovery GATEsw message SIG 80 to the OSW 30. The OSW 30 converts the optical signal demultiplexed by the optical splitter 340 into an electric signal by the O / E converter 341, and the reception PHY / MAC logic circuit 342 analyzes the converted electric signal, and this signal is converted into the OLT 40. It is determined that it is a report request frame from. Then, based on the connection request status from each ONU 20 at the present time, a REPORTsw message SIG 90 is generated, and the generated message is returned to the OLT 40 via the 2-to-1 optical switch 350.

  FIG. 14 is an explanatory diagram illustrating a configuration example of the REPORTsw message SIG 90 according to the first embodiment.

  The REPORTsw message of the first embodiment includes a destination MAC address field 800, a transmission source MAC address field 801, a TYPE / LENGTH field 802, an OPCODE field 803, a time stamp field 804, an ONU REQUEST bitmap field 805, and a data and pad field 806. And an FCS field 807.

  The REPORTsw message can be handled as a kind of MPCP message, and in order to distinguish it from other messages, a value indicating REPORTsw is entered in the OPCODE field 803. The ONU REQUEST bitmap field 805 transmits the connection request status by setting the bit at the position indicating the ONU for which a connection request is made to “1” and setting the other bits to “0”. This field may be a format indicating the number of connection requests instead of the bitmap format. This is because the OSW 30 only needs to hold the management table 500 for associating the physical port number of the OSW 30 shown in FIG. 13 with the LLID managed by the OLT 40.

  Here, in the example 900 in the case where there is no connection request in the sequence shown in FIG. 11, there is no ONU 20 that makes a connection request, so the ONU REQUEST bitmap field 805 of the REPORTsw message SIG 90 is all “0”. Also when the number of ONU REQUESTs is represented by this field 805, the field 805 is “0”. Then, a REPORTsw message SIG 90 is generated and returned to the OLT 40 via the two-to-one optical switch 350. When the OLT 40 receives the REPORTsw message SIG 90 having this content, the OLT 40 ends the discovery phase and can enter the normal transfer phase.

  An example 901 when there is a connection request in the sequence shown in FIG. 11 shows a case where one ONU 20 requests connection.

  First, the ONU 20 that requests connection to the optical access network turns on the laser and sends a specific signal SIG 101 to the OSW 30. The laser emission is controlled by the MPCP control logic circuit 420. The specific signal SIG101 transmitted by the laser need only be able to notify that the laser is ON (that is, it may be continuous light), and need not be a meaningful value as a signal of a frame or a specific number of bits. For example, the value “1” may be continuously sent. In the example 901 shown in FIG. 11, the signal SIG101 from the ONU 20 indicates that the laser is ON.

  Next, the OLT 40 transmits a Discovery GATEsw message SIG 81 to the OSW 30. The O / E converter 341 of the OSW 30 converts the optical signal demultiplexed by the optical splitter 340 into an electric signal, and the reception PHY / MAC logic circuit 342 converts the electric signal converted by the O / E converter 341. Is analyzed. By analyzing this optical signal, it is recognized that the signal to be received is a report request frame from the OLT 40.

  Next, since there is a connection request from only one ONU 20, the bit corresponding to the ONU 20 that requested the connection in the ONU REQUEST bitmap field 805 (FIG. 14) is set to “1”, and the other bits are set to “0”. To. When the ONU REQUEST bitmap field 805 indicates the number of ONU REQUESTs, this field 805 is set to “1”. Then, the REPORTsw message SIG 91 is generated, and the generated REPORTsw message SIG 91 is returned to the OLT 40 via the two-to-one optical switch 350.

  When the OLT 40 receives the REPORTsw message SIG11, the OLT 40 recognizes that one ONU 20 has issued a connection request, and starts discovery processing for one ONU 20. First, the OLT 40 transmits a switch port fixing message SIG11 for fixing the destination of the downstream optical switch 311 of the OSW 30 and the transmission source of the upstream optical switch 312. The OSW 30 that has received this switch port fixing message SIG11 generates a REPORTsw message SIG91, and fixes the path between the OLT 40 and the ONU 20 that requested the connection.

  The OLT 40 transmits the Discovery GATE message SIG21 after the time when the port fixing of the OSW 30 is completed after transmitting the switch port fixing message SIG11. The Discovery GATE message SIG 21 is transmitted from the OLT 40 via the OSW 30 to the ONU 20 that requested the connection.

  When receiving the Discovery GATE message SIG21, the ONU 20 that requested the connection sets a local timer to T1 and returns a REGISTER_REQ message SIG31 at the time T2 specified by the Discovery GATE message SIG21, as in the conventional discovery process. . Further, since the ONU 20 does not need to continue the connection request when the REGISTER_REQ message SIG31 is returned, the ONU 20 turns off the laser.

  The REGISTER_REQ message SIG31 includes the synchronization time of the ONU 20 (Sync Time). Since the switch of the OSW 30 is uniquely fixed in both the upstream and downstream directions, the REGISTER_REQ message SIG 31 reaches the OLT 40. After receiving the message SIG31, the OLT 40 performs a burst transfer of Sync Pattern (Burst Preamble) of the minimum necessary length to the ONU 20 concerned.

  Next, the OLT 40 transmits a REGISTER message SIG 41 for assigning and registering an LLID to the ONU 20 that sent the message, and a GATE message SIG 51 to which an LLID for registration confirmation is given. Here, the OLT 40 waits for the arrival of the REGISTER_REQ message SIG31 within the period of the Discovery Window. However, when an optical switch is used, since a maximum of one ONU is detected by one Discovery GATE message SIG21, the process of transmitting the next REGISTER message SIG41 may be started as soon as the REGISTER_REQ message SIG31 arrives.

  The REGISTER message SIG 41 and the GATE message SIG 51 reach the ONU 20 that requested the connection via the OSW 30. At the same time, when the OSW 30 receives the REGISTER message SIG 41, the OSW 30 recognizes the LLID assigned to the ONU 20 and manages the correspondence between the physical port numbers and the LLIDs of the currently selected downstream optical switch 311 and upstream optical switch 312. To record. Thereafter, the OSW 30 refers to the management table 500 in accordance with a request from the OLT 40 and switches the switch port.

  The ONU 20 that has received the REGISTER message SIG 41 and the GATE message SIG 51 returns the REGISTER_ACK message SIG 61 to which the LLID assigned for registration confirmation is given to the OLT 40 via the OSW 30. When this message SIG 61 reaches the OLT 40, the discovery process for the ONU 20 is completed.

  In the sequence shown in FIG. 11, the OLT 40 transmits a switch port fixed message SIG11, and the OSW 30 that has received the switch port fixed message SIG11 determines a port to be fixed. However, the OLT 40 can also transmit a switch port fixing message SIG11 that designates a port to be fixed. In this case, the OLT 40 needs to maintain the correspondence between the LLID and the port.

  FIG. 12 is a sequence diagram illustrating a discovery procedure according to the first embodiment, and illustrates sequence examples 910 and 911 when two ONUs 20 request connection by the SIG 102 and the SIG 103, respectively.

  The main differences between the sequences 910 and 911 (FIG. 12) and the sequence 901 (FIG. 11) are the following three points. The first difference is that since there are two connection requests, the two bits corresponding to the ONU 20 requesting connection in the ONU REQUEST bitmap field 805 of the REPORTsw message SIG92 returned from the OSW 30 to the OLT 40 are “1”. The other bits are “0”. Note that when the ONU REQUEST bitmap field 805 indicates the number of ONU REQUESTs, the difference is that this field 805 is “2”.

  The second difference is that the OSW 30 that has received the switch port fixing message SIG12 selects one of the two ONUs for which a connection request has been made, and fixes the path between the ONU 20 and the OLT 40.

  The third difference is that the discovery process 911 for the second ONU 20 is performed after the discovery process 910 for the first ONU 20 is completed.

  Other than the above, this is the same as the sequence 901 (FIG. 11). That is, first, as discovery processing of the first ONU 20, a switch port fixed message SIG12, a Discovery GATE message SIG22, a REGISTER_REQ message SIG32, a REGISTER message SIG42, a GATE message SIG52, and a REGISTER_ACK message SIG62 are transmitted and received. After completing the discovery process of the first ONU 20, the discovery process of the second ONU 20 includes a switch port fixed message SIG13, a Discovery GATE message SIG23, a REGISTER_REQ message SIG33, a REGISTER message SIG43, a GATE message SIG53, and a REGISTER_ACK message. SIG63 is transmitted / received.

  Even when three or more ONUs 20 request connection, it may be considered in the same manner as the extension from the sequence 901 (FIG. 11) to the sequences 910 and 911 (FIG. 12). That is, a plurality of bits corresponding to the ONU 20 requesting connection in the ONU REQUEST bitmap field 805 of the REPORTsw message SIG 92 returned from the OST 30 to the OLT 40 are set to “1”, and the other bits are set to “0”. Alternatively, when the ONU REQUEST bitmap field 805 indicates the number of ONU REQUESTs, this field 805 is set as the number of connection requests. The OSW 30 selects any one of the ONUs 20 that have requested connection, fixes the path between the selected ONU 20 and the OLT 40, and performs a discovery process with the selected ONU 20. This discovery process is repeated for the number of connection requests.

  Regarding the discovery process described above, the operations of the OLT 40, OSW 30, and ONU 20 will be described with reference to FIGS. 22, 23, and 24. FIG.

  FIG. 22 is a flowchart illustrating discovery processing executed in the OLT 40 according to the first embodiment.

  When the discovery phase is started (S110), the OLT 40 transmits a Discovery GATEsw message (S111) and waits for reception of the REPORTsw message from the OSW 30 (S112). When the REPORTsw message is received, it is determined whether or not the number of ONUs 20 requesting connection is “1” or more (S113). If the number of ONUs 20 that request connection is less than “1” as a result of the determination, the discovery phase is terminated (S121).

  On the other hand, if the number of ONUs 20 requesting connection is 1 or more, the number of ONUs 20 requesting connection is recorded, and a switch port fixed message is transmitted (S114). Further, after the switch port fixing message SIG11 is transmitted, the Discovery GATE message is transmitted after the time when the port fixing of the OSW 30 is completed (S115).

  Then, it waits for reception of a REGISTER_REQ message from the ONU 20 (S116). When the REGISTER_REQ message is received, the REGISTER message is transmitted to the ONU 20 that transmitted the REGISTER_REQ message (S117), and then the GATE message is transmitted (S118).

  Then, it waits for reception of the REGISTER_ACK message from the ONU 20 (S119). When the REGISTER_ACK message is received, the remaining number of connection request ONUs recorded in step S114 is “1” or more and the time for executing the discovery phase is reached. It is determined whether it remains (S120). As a result of the determination, if these conditions are satisfied, the discovery process can be continued. Therefore, the process returns to step S114, and the discovery process for the next ONU 20 is executed. On the other hand, if these conditions are not satisfied, the discovery phase is terminated (S121).

  FIG. 23 is a flowchart illustrating the discovery process executed in the OSW 30 according to the first embodiment.

  When the OSW 30 starts the discovery phase (S200), it waits for the Discovery GATEsw message received from the OLT 40 (S201). When receiving the Discovery GATEsw message, the power monitor 313 detects the ONU 20 that requests connection (S202). Based on the detection result, a REPORTsw message including the number of ONUs 20 requesting connection is generated, and the generated message is transmitted to the OLT 40 (S203).

  Subsequently, it is determined whether or not the number of ONUs 20 that request connection is “1” or more (S204). If the number of connection requests is “0”, the discovery phase is terminated (S211). On the other hand, if the number of connection requests is “1” or more, it is further determined whether or not there is a normal data transfer request (S205). If there is a data transfer request, the discovery phase is terminated in order to transfer the requested data (S211). On the other hand, if there is no request to transfer data, it waits for reception of a switch port fixed message from the OLT 40 (S206).

  When the switch port fixed message is received, one of the ONUs 20 having a registration request checked by the power monitor 313 is selected, and both the upstream and downstream switch ports between the ONU 20 and the OLT 40 are fixed ( S207).

  Thereafter, it waits for reception of a REGISTER message from the OLT 40 to the ONU 20 (S208). When the REGISTER message is received, the correspondence relationship between the LLID included in the REGISTER message and the physical port of the currently connected switch is recorded in the management table 500 (FIG. 13) (S209). Thereafter, the remaining number of ONUs 20 that request connection is determined (S210). If the remaining number of ONUs 20 that request connection is not "0", the process returns to step S205, and discovery processing for the next ONU 20 is executed. On the other hand, if the remaining number of ONUs 20 requesting connection is “0”, the discovery phase is terminated (S211).

  FIG. 24 is a flowchart illustrating discovery processing executed in the ONU 20 according to the first embodiment.

  The ONU 20 is in an initial state (S300) that is not registered in the OLT 40, and determines whether or not to issue a connection request to the OSW 30 when there is an access from the user terminal 10 or in a warm-up state (S301). If there is a connection request as a result of the determination, the laser output of the interface on the OSW 30 side is turned on, and some signal is continuously notified to the OSW 30 (S302).

  Then, it waits for reception of a Discovery GATE message from the OLT 40 (S303). When the Discovery GATE message is received, a REGISTER_REQ message is transmitted in order to transmit a formal connection request (registration request) to the OLT 40 (S304). Then, the laser is turned off here (S305). Thereafter, the laser is turned on only when messages and data are transmitted.

  Thereafter, the ONU 20 waits for the reception of the REGISTER message and the GATE message in order to allocate the LLID (S306). After receiving these messages, a REGISTER_ACK message is transmitted (S307), and registration in the OLT 40 is completed.

  Thereafter, since the ONU 20 is registered in the OLT 40, if communication is permitted by the GATE message from the OLT 40 during normal data transfer, data for the length of time permitted from the permitted time is transferred. be able to. In addition, it is always inspected whether the registration with the OLT 40 is canceled for some reason (S308). When the registration is canceled, the process returns to the unregistered state (S300) again and waits for re-registration.

  The configuration and operation of each part of the OLT 40, OSW 30, and ONU 20 have been described above for the discovery processing method using the power monitor 313. Next, a specific arrangement method and monitoring method of the power monitor 313 provided in the OSW 30 will be described. The configuration of the power monitor 313 provided in the OSW 30 has three types of configurations shown in FIGS. 4, 5, and 6. In order to simplify the description, the number of ports of the upstream optical switch 312 is assumed to be 2 here. The same idea should be applied when the number of ports exceeds two.

  FIG. 4 is a block diagram illustrating a configuration example of the upstream optical switch 312 according to the first embodiment of this invention.

  The upstream optical switch 312 illustrated in FIG. 4 includes an optical switch element 390, an optical splitter 370, and a power monitor 313. The optical splitter 370 is provided for all inputs from the ONU 20 side. The light branched by the optical splitter 370 is guided to the optical switch element 390 and the power monitor 313.

  Each power monitor 313 detects the presence or absence of an optical signal from the ONU 20, converts it to an electrical signal, and notifies the transmission PHY / MAC logic circuit 344. The transmission PHY / MAC logic circuit 344 notifies the presence / absence of the optical signal that the physical location of the ONU 20 requesting connection (the port to which the ONU 20 is connected) or the number of ONUs 20 requesting connection. And the ONU REQUEST bitmap field 805 of the REPORTsw message can be generated.

  The power monitor 313 may be configured integrally with the optical splitter 370 or may be configured separately from the optical splitter 370. The configuration of the optical switch 312 shown in FIG. 4 has an advantage that optical signals can be observed simultaneously at all input ports. However, when the cost required for mounting the power monitor 313 is high, the following configurations shown in FIGS. 5 and 6 are desirable.

  FIG. 5 is a block diagram illustrating another configuration example of the upstream optical switch 312 according to the first embodiment of this invention.

  The upstream optical switch 312 shown in FIG. 5 shares one power monitor 313 among a plurality of input ports, unlike the configuration of the optical switch described above (FIG. 4). At this time, in the REPORTsw message of FIG. 14, it is desirable to indicate the number of ONU REQUESTs by the ONU REQUEST bitmap field 805. FIG. 5 shows an example in which the optical switch 390 has two ports. For example, when the optical switch 390 has a 128-port input, for example, when one power monitor 313 is shared by a predetermined plurality of ports (eight ports). Good. Then, the power monitor 313 detects an optical signal from any one of the ONUs 20 sharing one power monitor 313 or an optical signal from any ONU 20 sharing one power monitor 313. The detected optical signal is converted into an electric signal, and the converted electric signal is notified to the transmission PHY / MAC logic circuit 344. The transmission PHY / MAC logic circuit 344 can know the group of the ONU 20 that has issued the connection request by this notification.

  Then, referring to the management table 500 (FIG. 13), if the number of registered ONU groups indicated by this notification is “0”, the ONU REQUEST bitmap field 805 (indicating the number of ONU REQUESTs) of the REPORTsw message contains: At least “8” corresponding to the group in which the optical signal is detected is described as the number of connection requests. If a request from another ONU group is detected, the number of connection requests is further increased by “8”.

  At this time, referring to the management table 500, if the number of registered ONU groups indicated in the notification is any one of “1” to “7”, the ONU REQUEST bitmap field 805 (the number of ONU REQUESTs) of the REPORTsw message ) Is reduced from 7 to 1 each, thereby eliminating unnecessary processing for connection requests as much as possible.

  However, since the power monitor 313 is shared by the eight ONUs 20, even if the actual number of connection requests is one, the number of requests transmitted to the OSW 30 and the OLT 40 is eight. That is, in the discovery process, there is a case where there is no response from the ONU 20 to the Discovery GATE message SIG 20 from the OLT 40 as shown in FIG.

  FIG. 6 is a block diagram illustrating another configuration example of the upstream optical switch 312 according to the embodiment of this invention.

  The upstream optical switch 312 shown in FIG. 6 is different from the configuration of the optical switch described above (FIGS. 4 and 5). 313 input. It is most preferable that the optical splitter 370 is connected to the output port of the upstream optical switch 312 as shown in FIG. 6. However, when the upstream optical switch 312 includes a plurality of stages of optical switching elements 390, the optical splitter is used. 370 may not be the final output port of the upstream optical switch 312, but may be connected to the outputs of all the optical switch elements 390 at any stage.

  In the upstream optical switch 312 shown in FIG. 6, when the OSW 30 receives the Discovery GATEsw message from the OLT 40, it sequentially switches all inputs and outputs of the upstream optical switch 312 at predetermined time intervals before sending the REPORTsw message to the OLT 40. The power monitor 313 determines the port to which the connection request signal is input. The predetermined time for switching between input and output may be set to a time longer than the time when optical signals of different inputs before and after switching do not affect each other.

  By the operation described above, the ONU REQUEST bitmap field 805 (or the number of REQUESTs using the ONU REQUEST bitmap field 805) is generated, and the generated value is transmitted to the OLT 40 as a REPORTsw message.

  Since the upstream optical switch 312 shown in FIG. 6 shares one power monitor with all input ports, there is an advantage that the mounting cost can be reduced. However, when the predetermined time for switching between input and output becomes longer than the time required for normal discovery processing due to the characteristics of the optical device, the optical switch having the above-described configuration (FIGS. 4 and 5) is desirable.

  As above, the arrangement of the power monitor 313 and the monitoring of the connection request signal have been described in detail with reference to FIGS. 4, 5, and 6. Since both configurations have advantages and disadvantages, it is desirable to select an appropriate optical switch according to the configuration of the apparatus. In terms of performance, the configuration of FIGS. 4 and 6 is desirable, and the configuration of FIG. 5 is desirable next.

  In particular, when the power monitor shown in FIG. 4 or FIG. 6 is provided, in an optical access system using an optical switch, there is no need to perform useless discovery processing with the ONU 20 without a connection request shown in FIG. Because the discovery process is performed only with the above, a high-speed discovery process is possible.

<Embodiment 2>
In the first embodiment described above, the control of the OSW 30 according to the conventional discovery processing procedure shown in Non-Patent Document 1 and Non-Patent Document 2 has been described. In the second embodiment, a description will be given of a faster discovery process than the first embodiment while reducing the number of MPCP messages necessary for the discovery process from the first embodiment.

  FIG. 18 is a sequence diagram illustrating a discovery procedure according to the second embodiment.

  Since the OLT 40 knows the number (or position) of ONUs that request connection by the REPORTsw message SIG 91, the OLT 40 transmits a DISCOVERY & REGISTER message SIG 70 in the subsequent discovery process. The DISCOVERY & REGISTER message SIG 70 is a collection of the Discovery GATE message SIG21, REGISTER message SIG41, and GATE message SIG51 of the first embodiment (FIG. 11) described above.

  When the ONU 20 receives the DISCOVERY & REGISTER message SIG70, the ONU 20 transmits a REGISTER_ACK + α message SIG71. The REGISTER_ACK + α message SIG71 is a combination of the REGISTER_REQ message SIG31 and the REGISTER_ACK message SIG61 of the first embodiment (FIG. 11) described above.

  FIG. 19 is an explanatory diagram illustrating a configuration example of the DISCOVERY & REGISTER message SIG 70 according to the second embodiment.

  This message includes a destination MAC address field 800, a source MAC address field 801, a TYPE / LENGTH field 802, an OPCODE field 810, a time stamp field 811, a field 812, a start time field 813, a length field 814, a Sync Time field 815, It includes a Discovery Information field 816, an Assigned Port field 817, a Flags field 818, a data / pad field 806, and an FCS field 807.

  The time stamp field 811 is used for time adjustment of the ONU 20. A start time field 813 and a length field 814 specify the start time and the length of the reply message, respectively. The Sync Time field 815 notifies the synchronization time of the OLT 40. The Discovery Information field 816 notifies discovery information. The Assigned Port field 817 notifies the assigned LLID. The Flags field 818 notifies information about a REGISTER flag. The other fields have the same role as the fields used in normal Ethernet frames.

  Normally, the destination address of the Discovery GATE message and the GATE message is an address defined as a MAC control address, and the destination address of the REGISTER message is the MAC address of the target ONU 20. The destination address of the DISCOVERY & REGISTER message SIG 70 of the second embodiment is a MAC control address. This is because the MAC address of the ONU 20 is unknown at the time of transmission of the DISCOVERY & REGISTER message SIG70. Further, since the optical access system to which this control is applied includes an optical switch instead of an optical splitter, the DISCOVERY & REGISTER message SIG 70 is not notified to other ONUs, and the message is surely sent to only one target ONU 20. Can be communicated.

  FIG. 20 is an explanatory diagram illustrating a configuration example of the REGISTER_ACK + α message SIG 71 according to the second embodiment.

  This message includes a destination MAC address field 800, a source MAC address field 801, a TYPE / LENGTH field 802, an OPCODE field 830, a time stamp field 831, a flag field 832, an Echoed Assigned Port field 833, an Echoed Sync Time field 834, and Pending grants. A field 835, a Discovery Information field 836, a Sync Time field 837, a laser ON time field 838, a laser OFF time field 839, a data, pad field 806, and an FCS field 807 are included.

  A flag field 832 indicates a response message for registration permission, an Echoed Assigned Port field 833 indicates an assigned LLID, and an Echoed Sync Time field 834 indicates a Sync Time notified from the OLT 40. The Pending Grant field 835 indicates the maximum number of grants from the OLT 40 that can be held by the ONU 20. The Discovery Information field 836 indicates various information for discovery. A Sync Time field 837 indicates the synchronization time of the ONU 20. The reason that the Sync Time field 837 is present in the REGISTER_ACK + α message is that the ONU 20 also receives burst transfer from the OLT 40, and therefore it is necessary to notify the OLT 40 of its own synchronization time. The laser ON time field 838 indicates the time taken for the ONU 20 to turn on the laser. The other fields have the same role as the fields used in normal Ethernet frames.

  When the ONU 20 receives the DISCOVERY & REGISTER message SIG 70, the ONU 20 generates a REGISTER_ACK + α message SIG 71 using the LLID in the Assigned Port field 817 as its own LLID, and transmits the generated REGISTER_ACK + α message SIG 71 to the OLT 40.

  The OLT 40 can know the synchronized time of the registered ONU 20 by the discovery process. Therefore, in the normal transfer after the discovery process, the burst transfer addressed to the ONU 20 can perform a minimum required Sync Pattern (Burst Preamble) burst transfer.

  The optical access system according to this embodiment has been described in detail above. The above description is only one embodiment, and various modifications can be made without departing from the technical idea and technical scope of the present invention.

It is a figure which shows the structure of the optical access system of the 1st Embodiment of this invention. It is a block diagram which shows the structure of OSW of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the downstream optical switch of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the upstream optical switch of the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the upstream optical switch of the 1st Embodiment of this invention. It is a block diagram which shows another structural example of the upstream optical switch of the 1st Embodiment of this invention. It is a block diagram which shows another structural example of the upstream optical switch of the 1st Embodiment of this invention. It is a sequence diagram which shows the conventional discovery procedure. It is a sequence diagram which shows the conventional discovery procedure. It is a block diagram which shows the structure of OLT of the 1st Embodiment of this invention. It is a block diagram which shows the structure of ONU of the 1st Embodiment of this invention. It is a sequence diagram which shows the discovery procedure of the 1st Embodiment of this invention. It is a sequence diagram which shows the discovery procedure of the 1st Embodiment of this invention. The figure which shows an example of the switch port management table which the optical switch in this invention manages. It is explanatory drawing which shows the structural example of the REPORTsw message of 1st Embodiment of this invention. It is a figure which shows the structure of the optical access system using the conventional PON. It is a figure which shows the structure of the optical access system using the conventional optical switch. It is a figure which shows the example of a combination of the conventional discovery phase and a normal transfer phase. It is a sequence diagram which shows the discovery procedure of the 2nd Embodiment of this invention. It is explanatory drawing which shows the structural example of the DISCOVERY & REGISTER message of 2nd Embodiment of this invention. It is explanatory drawing which shows the structural example of the REGISTER_ACK + (alpha) message of 2nd Embodiment of this invention. It is a flowchart which shows the execution procedure of the conventional discovery phase and normal transfer phase. It is a flowchart which shows the discovery process performed in OLT of the 1st Embodiment of this invention. It is a flowchart which shows the discovery process performed in OSW of the 1st Embodiment of this invention. It is a flowchart which shows the discovery process performed in ONU of the 1st Embodiment of this invention.

Explanation of symbols

10 User terminal 20 ONU
30 OSW
40 OLT
50 Gateway 60 Backbone network 70 Access network 80 Optical splitter 90 OSW

Claims (17)

An optical line device connected to another network; a plurality of optical network devices each connected to a user terminal; and the optical line device and the plurality of optical network devices installed between the optical line device and the optical network device In an optical access system comprising an optical communication path switching device for switching an optical communication path with an optical network device of
The optical network device transmits a connection request signal when not registered in the optical line device,
The optical communication path switching device includes a detector that detects the presence or absence of a signal from the optical network device,
The optical communication path switching device, when detecting a signal from the unregistered optical network device, notifies the optical line device of the number of the detected unregistered optical network devices,
An optical access system, wherein the optical line device performs discovery processing for an optical network device that has requested connection according to the notified number of unregistered optical network devices.   2. The optical access system according to claim 1, wherein the optical communication path switching device notifies the optical line device of the position of the unregistered optical network device together with the number of the unregistered optical network devices. The optical communication path switching device includes an upstream optical switch including an optical switch element that switches an optical communication path from the optical network device to the optical line device,
The optical access system according to claim 1, wherein one detector is connected to each input port of the upstream optical switch. The optical communication path switching device includes an upstream optical switch that switches an optical communication path from the optical network device to the optical line device,
The optical access system according to claim 1, wherein the detector is connected to a plurality of input ports of the upstream optical switch. The optical communication path switching device includes an upstream optical switch that switches an optical communication path from the optical network device to the optical line device,
The detector is connected to an output port of the optical switch element;
The optical access system according to claim 1, wherein a path between an input port and an output port of the upstream optical switch is sequentially switched in order to detect an optical network device that has requested the connection.   2. The optical access system according to claim 1, wherein the optical communication path switching device notifies the number of the unregistered optical network devices to the optical line device by an MPCP frame.   The optical access system according to claim 1, wherein the optical communication path switching device manages a correspondence relationship between a port number of the optical communication path switching device and an identifier of the optical network device. The optical communication path switching device includes an upstream optical switch that switches an optical communication path from the optical network device to the optical line device, and a downstream optical switch that switches an optical communication path from the optical line device to the optical network device. Prepared,
In the discovery process,
The optical communication path switching device fixes the port of the upstream optical switch and the port of the downstream optical switch to a port to which an optical network device targeted for discovery processing is connected,
2. The optical access system according to claim 1, wherein after the port is fixed, the optical line device transmits a message for discovery. 3. The optical communication path switching device includes an upstream optical switch that switches an optical communication path from the optical network device to the optical line device, and a downstream optical switch that switches an optical communication path from the optical line device to the optical network device. Prepared,
The discovery process for one optical network device is as follows:
Fixing the upstream optical switch port and the downstream optical switch port corresponding to any one of the optical network devices that have requested the connection;
After the fixing of the port is completed, the optical line device includes at least the time of the optical line device, the start time of the reply message, the length of the reply message, and the synchronization time of the optical line device. A procedure to send a discovery message;
After the optical network device receives the discovery message, at least the time of the optical network device, the synchronization time of the optical network device, the maximum number of responses that the optical network device can hold, and the laser of the optical network device A procedure for returning a reply message including a time required for turning on the laser and a time required for turning off the laser of the optical network device to the optical line device at the start time of the designated reply message;
After the reply message is received, the optical line device transmits a first message including an identifier of the optical network device and a second message for requesting confirmation to the optical network device; ,
After the optical network device receives the first message, the optical network device assigns an identifier included in the first message to the optical network device itself, receives the second message, and then sends a registration completion notification message. Including a procedure for sending,
9. The optical access system according to claim 8, wherein the optical line device repeats discovery processing for the one optical network device for the same number of times as the notified number of unregistered optical network devices. The optical communication path switching device includes an upstream optical switch that switches an optical communication path from the optical network device to the optical line device, and a downstream optical switch that switches an optical communication path from the optical line device to the optical network device. Prepared,
The discovery process for one optical network device is as follows:
Fixing the upstream optical switch port and the downstream optical switch port corresponding to any one of the optical network devices that have requested the connection;
After the fixing of the port is completed, the optical line device at least specifies the time of the optical line device, the start time of the reply message, the length of the reply message, the synchronization time of the optical line device, discovery information A procedure for transmitting a discovery message including an identifier assigned to the optical network device and flag information;
After receiving the discovery message, the optical network device is at least the time of the optical network device, the allocation success notification, the synchronization time of the optical network device, the maximum number of responses that the optical network device can hold, the optical A procedure for returning a confirmation message including a time required for turning on the laser of the network device and a time required for turning off the laser of the optical network device to the optical line device,
9. The optical access system according to claim 8, wherein the optical line device repeats discovery processing for the one optical network device for the same number of times as the notified number of unregistered optical network devices. In an optical communication path switching device provided in an optical access system including an optical line device that communicates with another network via a gateway, and a plurality of optical network devices each connected to a user terminal,
Switching the optical communication path between the optical line device and the plurality of optical network devices, connecting between the optical line device and the optical network device,
A detector for detecting the optical network device that is not registered in the optical line device;
When the detector detects an optical network device that is not registered in the optical line device, the number of the detected unregistered optical network devices is calculated in order to cause the optical line device to perform a discovery process. An optical communication path switching device characterized by notifying a line device. An upstream optical switch that switches an optical communication path from the optical network device to the optical line device;
12. The optical communication path switching device according to claim 11, wherein one detector is connected to each input port of the upstream optical switch. An upstream optical switch that switches an optical communication path from the optical network device to the optical line device;
12. The optical communication path switching device according to claim 11, wherein the detector is connected to a plurality of input ports of the upstream optical switch. An upstream optical switch including an optical switch element that switches an optical communication path from the optical network device to the optical line device;
The detector is connected to an output port of the optical switch element;
12. The optical communication path switching apparatus according to claim 11, wherein a path between an input port and an output port of the upstream optical switch is sequentially switched in order to detect the optical network apparatus that has requested the connection. In an optical line device that communicates with a plurality of optical network devices each connected to a terminal via an optical communication path switching device, and is connected to another network,
Receiving the number of unregistered optical network devices detected;
Instructing fixing of the port of the optical communication path switching device the same number of times as the number of unregistered optical network devices received, and repeating the process of transmitting a discovery message after the fixing of the port is completed. Optical line equipment Request fixing of the port of the optical path switching device,
After the port fixing is completed, a discovery message including at least the time of the optical line device, the start time of the reply message, the length of the reply message, and the synchronization time of the optical line device is transmitted. ,
After receiving a response to the discovery message, a first message including an identifier of the optical network device and a second message for requesting confirmation are transmitted to the optical network device. The optical communication path switching device according to claim 15. Request fixing of the port of the optical path switching device,
After the fixing of the port is completed, at least the time of the optical line device, the start time of the reply message, the length of the reply message, the synchronization time of the optical line device, discovery information, and the optical network device 16. The optical communication path switching device according to claim 15, wherein a discovery message including an identifier to be assigned and flag information is transmitted.

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