JP4728697B2 - Optical switch device and optical access network method and optical access network system using the same - Google Patents

Description

The present invention relates to an optical switch device, an optical access network method using the same, and an optical access network system . More specifically, the present invention relates to an optical switch device for improving the reliability of an optical access network, an optical access network method using the same, and an optical access network system .

  IEEE 802.3ah (Draft Amendment to Carrier Sense Multiple Access with Collision Detection (CSMA / CD) access method), the standard of IEEE (The Institute of Electrical and Electronics Engineers, Inc.) and physical layer specifications, October, 7, 2003) (Non-Patent Document 1) and ITU-T Recommendation G.983.1 (Broadband optical access sys- tems based on Passive Optical Network (PON)) Appendix IV (Access netwaok survivability) (Non-patent document 2) and ITU-T recommendation G.983.5 (A Broadban optical access system with enhanced survivability) (Non-patent document 3).

  In the prior art described in Non-Patent Document 1, PON (Passive Optical Network) using an IEEE803.ah frame with a transmission rate of 1.25 Gbits / s is defined. This conventional technique is a single system (active system only) and does not have a standby system, and does not have a function of switching to a standby system when the active system fails. Therefore, the optical access network of Non-Patent Document 1 is not configured to improve the reliability by switching from the active system to the standby system in the event of a failure, and the method is not described. FIG. 11 shows an IEEE 802.3ah frame used for communication between the OLT (center device) and the ONU (remote device). The destination of this frame can be determined by examining the LLID (Logical Link Identifier) of the IEEE 802.3ah frame.

  On the other hand, Non-Patent Document 2 describes several methods for improving the reliability of the PON network, and Non-Patent Document 3 improves the network reliability of the PON of Non-Patent Document 2. The method is specifically described. The optical access network methods described in Non-Patent Document 2 and Non-Patent Document 3 are shown in FIGS.

  FIG. 12 shows an improvement in reliability by duplicating an optical fiber in a feeder section between the OLT and the n × 2 optical splitter. That is, the configuration is such that two optical fibers, an active optical fiber and a standby optical fiber, are arranged in the feeder section. Two network interfaces are installed in the OLT, and up to n ONUs are connected to the two sides of the n × 2 optical splitter by optical fibers. An ONU is connected to each optical fiber terminal.

  In FIG. 12, since the n × 2 optical splitter which is a passive element is used, it is necessary to prevent the downstream signal from colliding on the output side (2 side port) of the n × 2 optical splitter. Here, the downstream direction of the signal means the direction in which the signal is transmitted from the OLT to the ONU, and the upstream direction means the direction in which the signal is transmitted from the ONU to the OLT. For this reason, the network interface of the OLT is normally operated only in the active system, and the standby system stops operating (stops transmission of optical signals) to prepare for a failure. When a failure in the active system is detected, the operation of the active system is performed. And the operation of the standby system is started. This method is called a so-called cold standby method, and has a drawback that the switching time between the active system and the standby system is long.

  Furthermore, there is a drawback that switching cannot be performed normally depending on the type of failure. For example, when the transmitting side of the active system of the OLT fails, it is the ONU that can detect this failure, and the ONU needs to notify the detected failure status to the OLT, but this is impossible due to the characteristics of the PON. . That is, because the transmission part of the OLT has failed, the OLT cannot control the transmission of the ONU, and the ONU can no longer transmit. Therefore, there is a big problem that when the OLT transmission unit fails, the standby system and the active system cannot be switched.

  FIG. 13 shows a method of improving reliability by preparing two n × 1 optical splitters, installing two network interfaces in each of the OLT and ONU, and simultaneously incorporating the two systems of the standby system and the active system. It is shown. That is, since the standby system and the active system are incorporated, the system is switched between the OLT and the ONU as necessary. In this switching method, the ONU needs to have two network interfaces. Therefore, there is a problem that the conventional single system ONU cannot be applied. The ONU needs to be inexpensive for the economics of FTTH (Fiber-To-The-Home) service, and it is against this to prepare a model having two network interfaces and increase the number of models. This is because the number of ONUs is one, and mass production leads to economic growth.

  Further, the method of improving the reliability as shown in FIGS. 12 and 13 is disclosed in Non-Patent Document 1 because it is specialized for B-PON (Broadband Passive Optical Network) defined in Non-Patent Document 2. It cannot be applied to the optical access network currently used.

  In order to improve the reliability of the optical access network, Patent Document 1, Patent Document 2, and Patent Document 3 can be cited as examples in which the optical fiber of the relay or trunk line is doubled. In Patent Document 1, in a configuration in which one master station device and a plurality of slave station devices are connected by an optical splitter, two optical switches are inserted between the optical splitter and the master station device, A configuration is disclosed in which the two optical switches are connected by two main optical fibers. The optical switch is controlled by an external switching instruction unit and is configured to switch between two optical fibers. With such a configuration, the time during which communication is interrupted due to an instantaneous interruption, particularly an instantaneous interruption accompanying switching of a trunk line, is reduced regardless of the amount of bandwidth allocated to each slave station device. However, it cannot be denied that having an external control unit is disadvantageous not only in apparatus cost but also in facility cost and management.

  In Patent Documents 2 and 3, the relay fiber between the lower node to which a plurality of ONUs are connected and the upper node on which the OLT is mounted is duplicated between the standby system and the active system, and switching between the standby system and the active system is performed. In this configuration, an optical switch in the second active standby switching circuit in the lower node is used. That is, the feeder section is doubled and an optical switch is used for switching itself.

JP 2002-198404 A JP 2002-368656 A JP 2003-51765 A IEEE 802.3ah (Draft Amendment to Carrier Sense Multiple Access with Collision Detection (CSMA / CD) access method and physical layer specifications, October, 7, 2003) ITU-T Recommendation G.983.1 (Broadband optical access sysytems based on Passive Optical Network (PON), Appendix IV (Access netwaok survivability) ITU-T recommendation G.983.5 (A Broadban optical access sysytem with enhanced survivability)

The object of the present invention is to solve the problems of the optical access network of the prior art, that is, (1) the switching time is long because of the cold standby system, and (2) the standby system and the active system when the OLT transmission side fails. (3) When the standby system and the active system are completely doubled, the conventional single system ONU cannot be applied and the number of types of ONUs must be newly increased. And an optical access network method and an optical access network system using the same.

Note that the optical access network methods disclosed in the above-mentioned Patent Documents 1 to 3 have unique features, but are clearly different in configuration from the present invention . Details are made clear in the best mode for carrying out the invention. Specifically, for example, there is no external optical switch switching control unit, and when the Feeder unit is duplicated, switching itself is performed. It can be mentioned that the optical switch is not used. However, the configurations disclosed in Patent Documents 1 to 3 cannot simultaneously solve the above three problems.

In the optical switch device of the present invention , the destination of the remote device that receives the packet signal is written in the packet signal transmitted in the downstream direction from the center device to the remote device side, and the packet signal transmission instruction transmitted by the remote device In the optical access network apparatus that performs the control message from the center apparatus, the upstream optical signal and the downstream optical signal of a specific wavelength transmitted through two optical fibers connected to the center apparatus are respectively demultiplexed and combined 2 An upstream multiplexer / demultiplexer, two 2 × 1 optical splitters for branching two downstream optical signals demultiplexed by the upstream multiplexer / demultiplexer, and the two 2 × 1 optical splitters Two downstream optical signals branched by the two 2 × 1 optical splitters, and two downstream optical signals converting each of the branched downstream optical signals into electrical signals, respectively. Two delay circuit units that give delay to each of the two and the downstream electrical signal converted by the two photoelectric signal converters are examined, and the state of the downstream electrical signal and the switching control information from the center device are checked. A selection control unit that issues a switching instruction, and a selection unit that selects one downstream electrical signal from among the downstream electrical signals that are converted into electricity by the two photoelectric signal conversion units in response to the instruction from the selection control unit; A reception frame analysis unit for analyzing the content of one downstream electrical signal selected by the selection unit, an n × 1 upstream optical switch element unit and n × in response to an instruction of a result analyzed by the reception frame analysis unit 2 upstream optical switch element control unit and downstream optical switch element control unit for controlling the downstream optical switch element unit, and one port on one side of the n × 1 upstream optical switch element unit, A 2 × 1 optical splitter connected to the two upstream multiplexers / demultiplexers, and an upstream optical signal of a specific wavelength transmitted through a maximum of n optical fibers connected to a maximum of n of the remote devices; N downstream multiplexers / demultiplexers for demultiplexing and combining downstream optical signals, and the n × 1 upstream optical switch element unit is configured to transmit upstream signals according to a control signal from the upstream optical switch element controller. An optical signal packet is configured to be switched on a packet basis, and n ports on the n side of the n × 1 upstream optical switch element unit are connected to the n downstream side multiplexers / demultiplexers, The × 2 downstream optical switch element unit is configured to switch a packet of the downstream optical signal on a packet basis according to a control signal of the downstream optical switch element control unit, and the n × 2 downstream optical switch element unit The two ports on the two sides are the two It is connected to the delay circuit, n number of ports of the n-side of the n × 2 downstream optical switching element is characterized by comprising connected to the n-number of the downlink-side demultiplexer.

In the optical switch device of the present invention , the destination of the remote device that receives the packet signal is written in the packet signal transmitted in the downstream direction from the center device to the remote device side, and the packet signal transmission instruction transmitted by the remote device In an optical access network that performs a control message from the center device, two units that respectively demultiplex and combine an upstream optical signal and a downstream optical signal of a specific wavelength transmitted through two optical fibers connected to the center device. The two upstream optical demultiplexers, two 2 × 1 optical splitters that split the two downstream optical signals demultiplexed by the upstream optical multiplexer / demultiplexer, and the two 2 × 1 optical splitters. Two optical signal converters for converting one of the two downstream optical signals into an electrical signal respectively, and the other downstream optical signal 2 branched by the two 2 × 1 optical splitters 2 delay circuit units that give a delay to each, and the downstream electrical signal converted by the two photoelectric signal converters, and the switching instruction by the state of the downstream electrical signal and the switching control information from the center device A selection control unit that issues an instruction, a selection unit that selects one downstream electrical signal from among the downstream electrical signals that have been converted into electricity by the two photoelectric signal conversion units in response to an instruction from the selection control unit, and the selection Receiving frame analysis unit for analyzing the content of one downstream electrical signal selected by the unit, and n × 2 upstream optical switch element unit and n × 2 downstream light in response to an instruction of the result analyzed by the reception frame analysis unit Transmitted by an upstream optical switch element controller and downstream optical switch element controller for controlling the switch element, and a maximum of n optical fibers connected to the maximum of n remote devices. Anda n stand down side demultiplexer for demultiplexing and combining the upstream optical signals and downstream optical signals having particular wavelengths, the n × 2 upstream optical switching element is of the upstream optical switching element control unit The upstream optical signal packet is switched on a packet basis according to the control signal, and the two ports on the two sides of the n × 2 upstream optical switch element section are the two upstream multiplexers / demultiplexers. And the n × 2 downstream optical switch element unit is configured to switch a packet of downstream optical signal on a packet basis according to a control signal of the downstream optical switch element control unit, and the n × 2 Two ports on the downstream side of the downstream optical switch element unit are connected to the two delay circuit units, and n ports on the n side of the n × 2 downstream optical switch element unit are connected to the n downstream side switch elements. It is characterized by being connected to a duplexer .

The packet signal is configured using a frame defined in IEEE 802.3ah, and the downstream optical switch element unit performs switching based on the LLID defined in the frame and the frame length, and the upstream optical switch element unit Then, switching can be performed based on the control message from the center device .

The optical access network method of the present invention is an optical access network method comprising a center device, a remote device, an optical switch device, and an optical fiber, wherein the optical switch device is the optical switch device of the present invention, and n × 2 ( n × 2 optical switch device comprising means for switching optical signals (n is an integer), wherein one unit is installed in the optical access network and is connected to n ports on the n side of the n × 2 optical switch device. at most n of the remote device and connected with said optical fiber, said center device is provided with two network interfaces of the current system network interface and a standby system network interface, 2 side of the n × 2 optical switching apparatus Two ports, the active network interface in the center device, and the standby network When the working optical fiber or the working network interface fails between the center device and the n × 2 optical switch device, each of which is connected to the network interface with the working optical fiber and the standby optical fiber. In addition, the working optical fiber and the working network interface are automatically switched to the standby optical fiber and the standby network interface, respectively, or between the center device and the n × 2 optical switch device. The active optical fiber and the active network interface are switched to the standby optical fiber and the standby network interface, respectively, in accordance with an instruction from the center device.

The optical access network method of the present invention is an optical access network comprising a center device, a remote device, an optical switch device, and an optical fiber, wherein the optical switch device switches m × 1 (m is an integer) optical signal. An m × 1 optical switch device comprising means for performing and an n × 2 optical switch device comprising means for switching optical signals of n × 2 (n is an integer), wherein the m × 1 light is included in the optical access network. Two switch devices, m of the n × 2 optical switch devices are installed, and one of the two m × 1 optical switch devices is an active m × 1 optical switch device, and the other is a standby system m × 1. The optical switch device is configured such that a maximum of m · n remote devices are connected to the total of m · n ports on the n side of the m n × 2 optical switch devices through the optical fiber, respectively. Location is provided with two network interfaces of the current system network interface and a standby system network interface, one of the 1 side of the current system of m × 1 optical switch and said standby system of m × 1 optical switch device The working network interface and the standby network interface in the center device are connected by the working optical fiber and the standby optical fiber, respectively, and m pieces on the m side of the working m × 1 optical switch device. K-th port (k = 1, 2, 3,... M) and k-th (m = 1) of m ports on the m-side of the standby m × 1 optical switch device. 2, 3... M) are connected to two ports on the two sides of the k-th n × 2 optical switch device by the optical fiber, respectively, and the center device and the n × 2 optical switch are connected. When the working optical fiber, the working m × 1 optical switch device, or the working network interface fails, the working optical fiber and the working m × 1 optical switch device And the active network interface are automatically switched to the standby optical fiber, the standby m × 1 optical switch device, and the standby network interface, respectively, or the center device and the n × 2 optical switch device. The active optical fiber, the active m × 1 optical switch device, and the active network interface are respectively connected to the standby optical fiber and the active m × 1 optical switch device according to an instruction from the center device. Switching to the backup network interface is characterized. Here, n of the n × 2 optical switch device may be set to 1. The 1 × 2 optical switch device may be installed in the remote device or in the vicinity of the remote device.

The optical access network method of the present invention is an optical access network method comprising a center device, a remote device, an optical switch device, and an optical fiber, wherein the optical switch device is the optical switch device of the present invention, and n × 2 ( n × 2 optical switch device comprising means for switching optical signals (n is an integer), wherein one unit is installed in the optical access network and is connected to n ports on the n side of the n × 2 optical switch device. is at most n of the remote device and connected with said optical fiber, said center device is provided with a single network interface and the 1 × 2 optical switch device of one of the 1 × 2 optical switch device One port on one side is connected to the network interface, two ports on the two sides of the n × 2 optical switch device and the front in the center device Two ports on the two sides of the 1 × 2 optical switch device are connected by an active optical fiber and a standby optical fiber, respectively, and the 1 × 2 optical switch device and the n × 2 optical switch device in the center device are connected to each other. When the working optical fiber fails, the working optical fiber is automatically switched to a standby optical fiber, or the 1 × 2 optical switch device in the center device and the n × The working optical fiber is switched to the standby optical fiber in accordance with an instruction from the center device between two optical switch devices.

The optical access network method of the present invention is an optical access network comprising a center device, a remote device, an optical switch device, and an optical fiber, wherein the optical switch device switches m × 1 (m is an integer) optical signal. An m × 1 optical switch device comprising means for performing and an n × 2 optical switch device comprising means for switching optical signals of n × 2 (n is an integer), wherein the m × 1 light is included in the optical access network. Two switch devices, m of the n × 2 optical switch devices are installed, and one of the two m × 1 optical switch devices is an active m × 1 optical switch device, and the other is a standby system m × 1. A maximum of m · n remote devices are connected to the total m · n ports on the n side of the m n × 2 optical switch devices through the optical fiber, respectively. Apparatus and a 1 × 2 optical switch device of one and one network interface to be connected to one port of one side of the 1 × 2 optical switching device to the network interface, the n × 2 The two ports on the two sides of the optical switch device and the two ports on the two sides of the 1 × 2 optical switch device in the center device are connected by an active optical fiber and a standby optical fiber, and the active m Of the m ports on the m side of the × 1 optical switch device, the k-th (k = 1, 2, 3,... M) port and the m ports on the m side of the standby m × 1 optical switch device. K-th (k = 1, 2, 3... M) of the ports are connected to the two ports on the two sides of the k-th n × 2 optical switch device by the optical fiber, respectively. Between the 1 × 2 optical switch device in the center device and the n × 2 optical switch device Thus, when the working optical fiber or the working m × 1 optical switch device fails, the working optical fiber and the working m × 1 optical switch device become the standby optical fiber and the standby m, respectively. The active optical fiber is automatically switched to the × 1 optical switch device, or between the 1 × 2 optical switch device in the center device and the n × 2 optical switch device, according to an instruction from the center device. And the active m × 1 optical switch device is switched to the standby optical fiber and the active m × 1 optical switch device, respectively. Here, n of the n × 2 optical switch device may be set to 1. The 1 × 2 optical switch device may be installed in the remote device or in the vicinity of the remote device.
The optical access network system according to the present invention is an optical access network system including a center device, a remote device, an optical switch device, and an optical fiber, wherein the optical switch device is nx 2 according to claim 1 or 2. An optical switch device comprising means for switching the optical signal of the above, wherein one unit is installed in the optical access network, and a maximum of n remote devices are provided in n ports on the n side of the n × 2 optical switch device. was connected with the optical fiber, the center device, working system network includes two network interfaces of the interface and the standby system network interface, wherein the two ports of the 2 side of the n × 2 optical switching apparatus The active network interface and the standby network in the center device When the working optical fiber or the working network interface fails between the center device and the n × 2 optical switch device, the working optical fiber and the standby optical fiber are connected to each other. The active optical fiber and the active network interface are automatically switched to the standby optical fiber and the standby network interface, respectively, or between the center device and the n × 2 optical switch device, The active optical fiber and the active network interface are switched to the standby optical fiber and the standby network interface, respectively, according to an instruction from the center device.
Furthermore, the optical access network system of the present invention is an optical access network system comprising a center device, a remote device, an optical switch device, and an optical fiber, wherein the optical switch device is nx 2 according to claim 1 or 2. An optical switching device comprising means for switching the optical signal of the optical switching device , wherein one unit is installed in the optical access network, and n ports on the n side of the n × 2 optical switching device have a maximum of n remote devices. the apparatus was connected with the optical fiber, the center device is provided with a single network interface and the 1 × 2 optical switch device of one, one port of one side of the 1 × 2 optical switch device Are connected to the network interface, two ports on the two sides of the n × 2 optical switch device and the 1 × 2 in the center device Two ports on the two sides of the switch device are respectively connected by an active optical fiber and a standby optical fiber, and between the 1 × 2 optical switch device and the n × 2 optical switch device in the center device, When the working optical fiber fails, the working optical fiber is automatically switched to a standby optical fiber, or the 1 × 2 optical switch device and the n × 2 optical switch device in the center device The active optical fiber is switched to the standby optical fiber according to an instruction from the center device.

According to the optical switch device and the optical access network method and the optical access network system using the optical switch device of the present invention , there are problems with the optical access network of the prior art, that is, (1) the switching time is long because of the cold standby system. (2) When the transmission side of the OLT fails, switching between the standby system and the active system is impossible. (3) When the standby system and the active system are completely doubled, a conventional single system ONU is used. It is possible to solve all the problems that cannot be applied and the number of types of ONUs must be newly increased.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
(Example 1)
FIG. 1 is a schematic diagram showing a first embodiment of an optical switch device according to the present invention , and corresponds to claim 1. This optical switch device can be applied to the optical access network method shown in FIGS. In the optical access network, the direction from the OLT (center device) to the ONU (remote device) is defined as the downlink direction. In the downstream direction, light having a wavelength of 1.5 μm is used. On the other hand, the direction from the ONU to the OLT is defined as the upstream direction, and light having a wavelength of 1.3 μm is used. These optical signals are wavelength-multiplexed and transmitted through an optical fiber.

  Two systems of optical signals wavelength-multiplexed with the OLT are separated into downstream optical signals and upstream optical signals in the upstream side multiplexer / demultiplexer. Each of the two downstream optical signals thus separated is branched into two downstream optical signals by a 2 × 1 optical splitter. One of the two downstream optical signals branched is input to the delay circuit unit and given a delay time, and then connected to the two sides of the n × 2 downstream optical switch element unit. The other of the two downstream optical signals branched is input to the photoelectric signal converter (O / E). The delay time given to the above-mentioned optical signal is for compensating the time required to realize the function described below performed by electricity.

  The two series of downstream optical signals input to the photoelectric signal converter (O / E) are converted into electrical signals by the photoelectric signal converter (O / E) to become two series of downstream electrical signals. The two series of downstream electric signals are input to the selection control unit and the selection unit. The selection control unit determines whether the two series of electrical signals are normal or abnormal, and instructs the selection unit to always select a normal determination electrical signal only when neither of the two series of electrical signals is abnormal. Further, the selection control unit receives the switching control information from the OLT, and instructs the selection unit to select two series of downlink electrical signals according to the contents. That is, the selection control unit is configured to perform switching based on the control information from the OLT in addition to the switching due to the above-described failure.

Further, the selection control unit instructs the downstream optical switch element control unit to select the optical signal corresponding to the electrical signal of the normal determination on the two sides (input side) of the n × 2 downstream optical switch element. To do.

If the two control signals are abnormal determinations, the selection control unit determines one of the sequences, instructs the selection unit to select the determined sequence, and the downstream optical switch element control unit, Instructs the two sides of the n × 2 downstream optical switch element to select a sequence of optical signals corresponding to a predetermined sequence of electrical signals. As a result, the selection unit always inputs a normal downlink electrical signal in the two sequences to the reception frame analysis unit. Similarly, the two sides (input side) of the n × 2 downstream optical switch element select an optical signal sequence corresponding to a normal electrical signal according to an instruction from the downstream optical switch element control unit.

The received frame analysis unit checks the destination of the ONU described in the received packet (frame) and measures the length of the packet (frame). Based on these pieces of information, the downstream optical switch element control unit determines the connection destination, connection time, and connection time of the downstream optical switch element, and performs connection control of the downstream optical switch element in units of packets (frames). The received packet (frame) analyzing unit analyzes the content of the control message in the received packet (frame) and performs upstream optical switch control. The contents of the control message are analyzed, and the destination of the received ONU, the transmission time of the ONU packet (frame), and the transmission time of the ONU packet (frame) are determined. Based on this information, the upstream optical switching element control unit, destination and connection time of the upstream optical switching element, it defines a connection time, performs connection control of upstream optical switching element in a packet (frame) unit.

As described above, the n side (output side) of the n × 2 downstream optical switch element is connected to the port corresponding to the destination ONU in units of packets as instructed by the downstream optical switch element control unit. The n side (input side) of the upstream optical switch element is connected in units of packets to the port corresponding to the ONU of the transmission source as instructed by the upstream optical switch element control unit as described above.

  The downstream signal on the n side (output side) of the n × 2 downstream optical switch element is demultiplexed and multiplexed by the upstream optical signal and downstream multiplexer / demultiplexer, and is wavelength-multiplexed to the corresponding ONU via an optical fiber. Sent.

Two systems of optical signals wavelength-multiplexed with the ONU are separated into a downstream optical signal and an upstream optical signal in the downstream multiplexer / demultiplexer. The upstream signal is input to the n × 1 upstream optical switch element unit. The upstream signal input to the n × 1 upstream optical switch element unit is switched by the n × 1 upstream optical switch element unit based on an instruction from the upstream optical switch element control unit. As described above, the n × 1 upstream optical switch control unit performs switching control of the n × 1 upstream optical switch element unit based on the analysis result of the control packet from the OLT in the reception frame analysis unit. A 2 × 1 optical splitter is connected after the output side (1 side port) of the n × 1 upstream optical switch element unit, and the output signal of the n × 1 upstream optical switch element is branched into two lines. The two series of upstream signals are demultiplexed and multiplexed by the downstream signals and upstream multiplexer / demultiplexers, respectively, and transmitted to the OLT. Since this upstream optical signal is branched by the optical splitter, signals having the same contents in both systems reach the OLT unless there is a failure in the feeder section.

(Example 2)
FIG. 2 is a schematic configuration diagram showing a second embodiment of the optical switch device according to the present invention , and corresponds to claim 2. This optical switch device can be applied to the optical access network method shown in FIGS. In FIG. 1, on the upstream side, an n × 1 upstream optical switch element unit and a 2 × 1 optical splitter are connected to realize two series of upstream signals, whereas in FIG. The configuration uses two optical switch element portions.

  The switching control of the downstream n × 2 downstream optical switch element unit is the same as in FIG. The switching control on the input side of the upstream n × 2 upstream optical switch element unit is also the same as in the case of FIG. The switching on the output side of the n × 2 upstream optical switch element depends on the content of the switching control information of the received packet sent from the OLT side, or is controlled to match the port on the input side of the n × 2 downstream optical switch element unit. Do. The content of the switching control information of the received packet sent from the OLT side is performed based on the analysis result of the selection control unit. Further, when matching with the input side port of the n × 2 downstream optical switch element unit, it is in accordance with an instruction from the selection control unit.

  The case where the IEEE 802.3ah frame is applied to the first embodiment (FIG. 1) and the second embodiment (FIG. 2) will be described. In FIG. 1 of the first embodiment, when the IEEE 802.3ah frame shown in FIG. 11 is used, the ONU destination necessary for controlling the downstream optical switch element unit in FIG. 1 is the LLID (Logical Link Identifier) in FIG. You can know by referring. In addition, the information necessary for upstream optical switch element control in FIG. 1 analyzes the contents of the GATE message specified in IEEE 802.3ah, and based on the received LLID, Timestamp, Grant Start, Grant Length, the upstream optical switch The connection destination port of the element, the connection start time, and the connection time are determined, and upstream optical switch element control is performed. The above description also applies to FIG.

(Example 3)
FIG. 3 is a schematic diagram showing the first and second embodiments of the optical access network method according to the present invention , and corresponds to claim 4. In the network configuration shown in FIG. 3, there can be considered two cases where the optical switch device shown in FIG. 1 and the optical switch device shown in FIG. 2 are applied as the n × 2 optical switch device. This is a case where a × 2 optical switch device is applied.

  In FIG. 3, the whole is configured by the OLT, the ONU, and the n × 2 optical switch device, and a so-called one-to-one configuration is provided between the OLT and the n × 2 optical switch device. Two network interfaces are installed in the OLT, and the two network interfaces are connected to two ports on the two sides of the nx2 optical switch device, respectively. From the OLT, the same optical signal is transmitted to two series of optical fibers with respect to the n × 2 optical switch device. As described with reference to FIG. 1, when the active downstream signal fails, the n × 2 optical switch device detects it and switches to the standby system. In addition, since two series of upstream signals from the n × 2 optical switch device to the OLT are the same unless there is a failure, the same optical signal flows through the optical fiber. If the upstream signal of the active system fails, the OLT detects it and switches to the standby system. That is, if the two systems are normal in the upstream and downstream in the section of the n × 2 optical switch device from the OLT, the same signal flows respectively. Switch to. If both systems are normal, the same signal is flowing, and if the currently selected active system fails, the other standby system is switched to the standby system if the other standby system is normal. It is possible to switch over only the detection time.

Therefore, the standby system is always switched to hot standby while it is in operation. Like the PON conventional technology, after detecting a failure, start up one of the systems and perform initialization before switching to cold standby. Compared with the method, the switching time can be shortened. In the prior art, as described above, it is impossible to switch due to a failure of the OLT transmitter, but in the configuration of the present invention , a failure on the transmission side of the OLT can be detected on the reception side of the n × 2 optical switch device. It is possible to switch between the active system and the standby system at the same time.

  In the optical access network method shown in FIG. 1, the system in which the upstream signal and downstream signal are transmitted may be independent and different. When inconvenience occurs in operation, the systems used for the upstream signal and downstream signal are matched by communicating with each other switching control information indicating which system is used between the ONU and the optical switch device. Can do. Furthermore, it is possible to switch the system in the n × 2 optical switch device by the switching control information from the OLT.

Example 4
Example 4 is a case where the n × 2 optical switch device shown in FIG. 2 is applied as the n × 2 optical switch device in the network configuration shown in FIG. Also in this case, a so-called one-to-one configuration is provided between the OLT and the n × 2 optical switch device. Between the OLT and the n × 2 optical switch device, the same optical signal is not sent to both the upstream and downstream systems, but an optical signal with information is sent only to the active system, and no information is transmitted to the standby system. This is a method of flowing a signal. In other words, the optical signal flows in the standby system, but no information is entered, and the transmission side is switched at the two ports of the OLT and the n × 2 optical switch device.

  When a failure is detected in the active system on the receiving side of the OLT, the network interface of the OLT is switched to instruct the n × 2 optical switch device to switch the transmitting side. The n × 2 optical switch device selects the output of the n × 2 upstream optical switch element unit in accordance with a switching instruction from the OLT, and switches the optical fiber. When a failure is detected in the active system on the reception side of the n × 2 optical switch device, the selection unit switches based on the selection control unit of the n × 2 optical switch device and instructs the OLT to switch on the transmission side. . In response to an instruction from the n × 2 optical switch device, the OLT selects the output of the n × 2 upstream optical switch element unit and switches the optical fiber. In this case as well, switching can be performed only by the time required for analyzing the switching control information from the OLT and the time of failure detection, that is, so-called hot standby switching, and switching time can be shortened compared to the cold standby method shown in the prior art. .

(Example 5)
FIG. 4 is a schematic configuration diagram showing third and fourth embodiments of the optical access network method of the present invention , and corresponds to claim 5. In the network configuration shown in FIG. 4, there can be considered two cases where the optical switch device shown in FIG. 1 and the optical switch device shown in FIG. 2 are applied as the n × 2 optical switch device, and Example 5 is shown in FIG. This is a case where an n × 2 optical switch device is applied.

An n × 2 optical switch device and an m × 1 optical switch device are connected between the OLT and the ONU. Two network interfaces are installed in the OLT, and there are two systems, a working system and a standby system, in the section between the network interface and the n × 2 optical switch device to improve reliability. In this case, in addition to the optical fiber, two m × 1 optical switch devices, ie, the active system and the standby system, are prepared, and the k th (k) of the m ports on the m side of the active system m × 1 optical switch device. = 1, 2, 3... M) and the k-th (k = 1, 2, 3... M) of the m ports on the m side of the standby m × 1 optical switch device. The ports are respectively connected to two ports on the two sides of the kth n × 2 optical switch device by optical fibers.

  Switching between the active system and the standby system is performed between the OLT network interface and the n × 2 optical switch device. Note that this switching is the same as that performed between the OLT network interface and the n × 2 optical switch device when the n × 2 optical switch device of FIG. 1 is applied to the network configuration of FIG. 3.

(Example 6)
Example 6 is a case where the n × 2 optical switch device shown in FIG. 2 is applied to the network configuration shown in FIG. In the section of the OLT network interface and the n × 2 optical switch device, there are two systems, an active system and a standby system, to improve the reliability. In this case, in addition to the optical fiber, two m × 1 optical switch devices, ie, the active system and the standby system, are prepared, and the k th (k) of the m ports on the m side of the active system m × 1 optical switch device. = 1, 2, 3... M) and the k-th (k = 1, 2, 3... M) of the m ports on the m side of the standby m × 1 optical switch device. A port is connected to each of two ports on the two sides of the kth n × 2 optical switch device by the optical fiber. Switching between the active system and the standby system is performed between the OLT network interface and the n × 2 optical switch device. This switching is the same as that performed between the OLT network interface and the n × 2 optical switch device when the n × 2 optical switch device of FIG. 2 is applied to the network configuration of FIG. 3.

(Examples 7 and 8)
FIG. 5 is a schematic configuration diagram showing fifth and sixth embodiments of the optical access network method of the present invention , and corresponds to claim 6. The network configuration in FIG. 5 is a case where n = 1 in the n × 2 optical switch device in FIG. 4. In the network configuration shown in FIG. 5, there are two cases where the optical switch device shown in FIG. 1 and the optical switch device shown in FIG. 2 are applied as the 1 × 2 optical switch device, and Example 7 is shown in FIG. This is a case where a 1 × 2 optical switch device is applied. Example 8 is a case where the 1 × 2 optical switch device shown in FIG. 2 is applied. The switching operation is basically the same as in FIG.

(Examples 9 and 10)
FIG. 6 is a schematic diagram showing the seventh and eighth embodiments of the optical access network method according to the present invention , and corresponds to claim 7. In the network configuration shown in FIG. 6, there are two cases where the optical switch device shown in FIG. 1 and the optical switch device shown in FIG. 2 are applied as the 1 × 2 optical switch device, and Example 9 is shown in FIG. This is a case where a 1 × 2 optical switch device is applied. Example 10 is a case where the 1 × 2 optical switch device shown in FIG. 2 is applied.

  In the network configuration of FIG. 6, the 1 × 2 optical switch device of FIG. 5 is installed in or near the ONU to improve the reliability of the drop section as well as the feeder section. is there. This is a configuration in which a 1 × 2 optical switch device is placed in front of the ONU, and a conventional ONU having a single network interface can be applied. That is, it is not necessary to develop a new ONU in order to improve reliability, and only one type of ONU is required.

(Examples 11 and 12)
FIG. 7 is a schematic diagram showing the ninth and tenth embodiments of the optical access network method according to the present invention , and corresponds to claim 8. In the network configuration shown in FIG. 7, there are two cases where the optical switch device shown in FIG. 1 and the optical switch device shown in FIG. 2 are applied as the 1 × 2 optical switch device and the n × 2 optical switch device. Reference numeral 11 denotes a case where the n × 2 optical switch device shown in FIG. 1 is applied. Example 12 is a case where the n × 2 optical switch device shown in FIG. 2 is applied.

  In FIG. 7, one network interface and one 1 × 2 optical switch device are installed in the OLT, and are configured by an optical fiber between the 1 × 2 optical switch device and the n × 2 optical switch device. An active optical fiber and a standby optical fiber are installed in the section (Feeder section). When a failure occurs in the working optical fiber, the configuration automatically switches to the standby optical fiber. In addition, it is configured such that the active optical fiber is switched to the standby optical fiber by the OLT control. In this case, since the 1 × 2 optical switch device and the n × 2 optical switch device can perform failure detection on the reception side, more reliable switching is possible.

(Examples 13 and 14)
FIG. 8 is a schematic block diagram showing the eleventh and twelfth embodiments of the optical access network method of the present invention , and corresponds to claim 9. In the network configuration shown in FIG. 8, there are two cases where the optical switch device shown in FIG. 1 and the optical switch device shown in FIG. 2 are applied as the 1 × 2 optical switch device and the n × 2 optical switch device. Reference numeral 13 denotes a case where the n × 2 optical switch device shown in FIG. 1 is applied. Example 14 is a case where the n × 2 optical switch device shown in FIG. 2 is applied.

  In FIG. 8, one network interface and one 1 × 2 optical switch device are installed in the OLT. Between the 1 × 2 optical switch device and the n × 2 optical switch device provided in the OLT, that is, the section composed of the m × 1 optical switch device and the optical fiber, two systems of the active system and the standby system are prepared, When a failure occurs in the active system, the system is automatically switched to the standby system. In addition, the active system is switched to the standby system under the control of the OLT. In this case, since the 1 × 2 optical switch device and the n × 2 optical switch device can perform failure detection on the reception side, more reliable switching is possible.

(Examples 15 and 16)
FIG. 9 is a schematic diagram showing the thirteenth and fourteenth embodiments of the optical access network method according to the present invention , and corresponds to the tenth aspect. In the network configuration shown in FIG. 9, there can be considered two cases where the optical switch device shown in FIG. 1 and the optical switch device shown in FIG. 2 are applied as the 1 × 2 optical switch device, and Example 14 is shown in FIG. This is a case where a 1 × 2 optical switch device is applied. The fifteenth embodiment is a case where the 1 × 2 optical switch device shown in FIG. 2 is applied. FIG. 9 corresponds to the case where n is 1 in FIG. 8, and the reliability of the feeder section is improved by using two m × 1 optical switch devices.

(Examples 17 and 18)
FIG. 10 is a schematic block diagram showing the fifteenth and sixteenth embodiments of the optical access network method of the present invention , and corresponds to claim 11. In the network configuration shown in FIG. 10, there can be two cases where the optical switch device shown in FIG. 1 and the optical switch device shown in FIG. 2 are applied as the 1 × 2 optical switch device, and Example 17 is shown in FIG. This is a case where a 1 × 2 optical switch device in which n = 1 is applied in the n × 2 optical switch device. Example 18 is a case where a 1 × 2 optical switch device in which n = 1 in the n × 2 optical switch device shown in FIG. 2 is applied. FIG. 10 shows that the 1 × 2 optical switch device after the m × 1 optical switch device in FIG. 9 is installed in or near the ONU, and the reliability of the drop section as well as the feeder section is improved. Is intended. A 1 × 2 optical switch device is placed in front of the ONU, and a conventional ONU having a single network interface can be applied. That is, it is not necessary to develop a new ONU in order to improve reliability, and only one type of ONU is required.

The optical switch device of the present invention and the optical access network using the same are the problems of the prior art in an optical access network composed of a center device, a remote device, an optical switch device, and an optical fiber, that is, (1) cold standby. Switching time is long in the system, (2) When the transmission side of the OLT fails, switching between the standby system and the working system is impossible, and (3) When the standby system and the working system are completely doubled Since it solves all the problems that conventional single-system ONUs cannot be applied and the number of types of ONUs must be newly increased, it can be widely applied to optical access networks.

It is a schematic block diagram which shows the 1st Example of the optical switch apparatus of this invention . It is a schematic block diagram which shows the 2nd Example of the optical switch apparatus of this invention . It is a schematic block diagram which shows the 1st and 2nd Example of the optical access network method of this invention . It is a schematic block diagram which shows the 3rd and 4th Example of the optical access network method of this invention . It is a schematic block diagram which shows the 5th and 6th Example of the optical access network method of this invention . It is a schematic block diagram which shows the 7th and 8th Example of the optical access network method of this invention . It is a schematic block diagram which shows the 9th and 10th Example of the optical access network method of this invention . It is a schematic block diagram which shows the 11th and 12th Example of the optical access network method of this invention . It is a schematic block diagram which shows the 13th and 14th Example of the optical access network method of this invention . It is a schematic block diagram which shows the 15th and 16th Example of the optical access network method of this invention . It is explanatory drawing which showed the IEEE 802.3ah frame structure used with an optical access network. It is a schematic block diagram of the conventional optical access network method. It is another schematic block diagram which shows the conventional optical access network method.

Explanation of symbols

OLT Center device ONU Remote device O / E Photoelectric signal converter

Claims (13)

The destination of the remote device that receives the packet signal is written in the packet signal that is transmitted in the downstream direction from the center device to the remote device side, and the control message from the center device indicates the transmission instruction of the packet signal transmitted by the remote device In the optical access network device performed in
Two upstream multiplexers / demultiplexers for respectively demultiplexing and combining upstream optical signals and downstream optical signals of specific wavelengths transmitted through two optical fibers connected to the center device;
Two 2 × 1 optical splitters that respectively branch the two downstream optical signals demultiplexed by the upstream multiplexer / demultiplexer;
Two optoelectric signal converters for converting two downstream optical signals branched by the two 2 × 1 optical splitters into electric signals,
Two delay circuit units each for giving a delay to the other two downstream optical signals branched by the two 2 × 1 optical splitters;
A selection control unit that examines the downstream electrical signals converted by the two photoelectric signal conversion units and issues a switching instruction based on the state of the downstream electrical signal and switching control information from the center device;
A selector that selects one downstream electrical signal from downstream electrical signals that have been converted into electricity by the two photoelectric signal converters in response to an instruction from the selection control unit;
A received frame analysis unit for analyzing the content of one downstream electrical signal selected by the selection unit;
An upstream optical switch element control unit and a downstream optical switch element control unit that control the n × 1 upstream optical switch element unit and the n × 2 downstream optical switch element unit in response to an instruction of a result analyzed by the reception frame analysis unit;
A 2 × 1 optical splitter connected to one port on one side of the n × 1 upstream optical switch element unit and connected to the two upstream multiplexers / demultiplexers;
N downstream side multiplexers / demultiplexers for demultiplexing / combining upstream optical signals and downstream optical signals of specific wavelengths transmitted through a maximum of n optical fibers connected to a maximum of n remote devices. And
The n × 1 upstream optical switch element unit is configured to switch packets of upstream optical signals on a packet basis according to a control signal of the upstream optical switch element control unit, and the n × 1 upstream optical switch element N ports on the n side of the unit are connected to the n downstream multiplexers / demultiplexers,
The n × 2 downstream optical switch element unit is configured to switch packets of downstream optical signals in units of packets in accordance with a control signal of the downstream optical switch element control unit, and the n × 2 downstream optical switch element Two ports on the two sides of the element section are connected to the two delay circuit sections, and n ports on the n side of the n × 2 downstream optical switch element section are connected to the n downstream multiplexer / demultiplexers. An optical switch device characterized by being connected. The destination of the remote device that receives the packet signal is written in the packet signal that is transmitted in the downstream direction from the center device to the remote device side, and the control message from the center device indicates the transmission instruction of the packet signal transmitted by the remote device In the optical access network device performed in
Two upstream multiplexers / demultiplexers for respectively demultiplexing and combining upstream optical signals and downstream optical signals of specific wavelengths transmitted through two optical fibers connected to the center device;
Two 2 × 1 optical splitters that respectively branch the two downstream optical signals demultiplexed by the upstream multiplexer / demultiplexer;
Two optoelectric signal converters for converting two downstream optical signals branched by the two 2 × 1 optical splitters into electric signals,
Two delay circuit units each for giving a delay to the other two downstream optical signals branched by the two 2 × 1 optical splitters;
A selection control unit that examines the downstream electrical signals converted by the two photoelectric signal conversion units and issues a switching instruction based on the state of the downstream electrical signal and switching control information from the center device;
A selector that selects one downstream electrical signal from downstream electrical signals that have been converted into electricity by the two photoelectric signal converters in response to an instruction from the selection control unit;
A received frame analysis unit for analyzing the content of one downstream electrical signal selected by the selection unit;
An upstream optical switch element control unit and a downstream optical switch element control unit that control the n × 2 upstream optical switch element unit and the n × 2 downstream optical switch element unit in response to an instruction of a result analyzed by the reception frame analysis unit;
N downstream side multiplexers / demultiplexers for demultiplexing / combining upstream optical signals and downstream optical signals of specific wavelengths transmitted through a maximum of n optical fibers connected to a maximum of n remote devices. And
The n × 2 upstream optical switch element unit is configured to switch packets of upstream optical signals in units of packets in accordance with a control signal of the upstream optical switch element control unit, and the n × 2 upstream optical switch element Two ports on the two sides of the unit are connected to the two upstream multiplexers / demultiplexers,
The n × 2 downstream optical switch element unit is configured to switch packets of downstream optical signals in units of packets in accordance with a control signal of the downstream optical switch element control unit, and the n × 2 downstream optical switch element Two ports on the two sides of the element section are connected to the two delay circuit sections, and n ports on the n side of the n × 2 downstream optical switch element section are connected to the n downstream multiplexer / demultiplexers. An optical switch device characterized by being connected.   The packet signal is configured using a frame defined in IEEE 802.3ah, and the downstream optical switch element unit performs switching based on the LLID defined in the frame and the frame length, and the upstream optical switch element unit Then, switching is performed based on a control message from the center device, and the optical switch device according to claim 1 or 2. In an optical access network method comprising a center device, a remote device, an optical switch device, and an optical fiber,
The optical switch device is an optical switch device comprising means for switching an nx2 optical signal according to claim 1 or 2 ,
One unit is installed in the optical access network,
A maximum of n remote devices are connected to n ports on the n side of the n × 2 optical switch device by the optical fiber, respectively.
The center device includes two network interfaces of the current system network interface and a standby system network interface,
The two ports on the two sides of the n × 2 optical switch device are connected to the active network interface and the standby network interface in the center device by an active optical fiber and a standby optical fiber, respectively.
When the working optical fiber or the working network interface fails between the center device and the n × 2 optical switch device, the working optical fiber and the working network interface are respectively connected to the standby optical fiber. Automatically switch to fiber and the backup network interface;
Alternatively, between the center device and the n × 2 optical switch device, according to an instruction from the center device, the working optical fiber and the working network interface are changed to the standby optical fiber and the standby network interface, respectively. An optical access network method characterized by switching. In an optical access network method comprising a center device, a remote device, an optical switch device, and an optical fiber,
The optical switch device includes an m × 1 optical switch device having means for switching an optical signal of m × 1 (m is an integer) and an n × unit having means for switching an optical signal of n × 2 (n is an integer). 2 optical switch devices, wherein two m × 1 optical switch devices and m n × 2 optical switch devices are installed in the optical access network, and the two m × 1 optical switch devices are: One is an active m × 1 optical switch device, the other is a standby m × 1 optical switch device,
A maximum of m · n remote devices are connected to the total of m · n ports on the n side of the m n × 2 optical switch devices by the optical fiber, respectively.
The center device includes two network interfaces of the current system network interface and a standby system network interface,
One port on one side of the active m × 1 optical switch device and the standby m × 1 optical switch device, and the active network interface and the standby network interface in the center device, respectively. Connect the system optical fiber and the standby optical fiber,
Of the m ports on the m side of the working m × 1 optical switch device, the k th (k = 1, 2, 3,... M) port and the m side of the standby m × 1 optical switch device. The k-th (k = 1, 2, 3... M) of the m ports are connected to the two ports on the two sides of the k-th n × 2 optical switch device, respectively. Connect with
When the active optical fiber or the active m × 1 optical switch device or the active network interface fails between the center device and the n × 2 optical switch device, the active optical fiber and the The active m × 1 optical switch device and the active network interface are automatically switched to the standby optical fiber, the standby m × 1 optical switch device, and the standby network interface, respectively;
Alternatively, the active optical fiber, the active m × 1 optical switch device, and the active network interface are respectively connected between the center device and the n × 2 optical switch device according to an instruction from the center device. An optical access network method comprising: switching to a system optical fiber, the active system m × 1 optical switch device, and the standby network interface.   6. The optical access network method according to claim 5, wherein n of the n × 2 optical switch device is set to 1.   The optical access network method according to claim 6, wherein the 1 × 2 optical switch device is installed in the remote device or in the vicinity of the remote device. In an optical access network method comprising a center device, a remote device, an optical switch device, and an optical fiber,
The optical switch device is an optical switch device comprising means for switching an nx2 optical signal according to claim 1 or 2 , wherein one optical switch device is installed in the optical access network,
A maximum of n remote devices are connected to the n ports on the n side of the n × 2 optical switch device by the optical fiber, respectively.
The center apparatus is provided with a single network interface and the 1 × 2 optical switch device of one, connect one port of one side of the 1 × 2 optical switch device to the network interface,
The two ports on the two sides of the n × 2 optical switch device and the two ports on the two sides of the 1 × 2 optical switch device in the center device are connected by a working optical fiber and a standby optical fiber, respectively. ,
When the working optical fiber fails between the 1 × 2 optical switch device and the n × 2 optical switch device in the center device, the working optical fiber automatically becomes a standby optical fiber. Switching,
Alternatively, the active optical fiber is switched to the standby optical fiber according to an instruction from the center device between the 1 × 2 optical switch device and the n × 2 optical switch device in the center device. Optical access network method. In an optical access network method comprising a center device, a remote device, an optical switch device, and an optical fiber,
The optical switch device includes an m × 1 optical switch device having means for switching an optical signal of m × 1 (m is an integer) and an n × unit having means for switching an optical signal of n × 2 (n is an integer). 2 optical switch devices, wherein two m × 1 optical switch devices and m n × 2 optical switch devices are installed in the optical access network, and the two m × 1 optical switch devices are: One is an active m × 1 optical switch device, the other is a standby m × 1 optical switch device,
A maximum of m · n remote devices are connected to the total m · n ports on the n side of the m n × 2 optical switch devices by the optical fiber, respectively.
Wherein the center apparatus includes a 1 × 2 optical switch device of one and one network interface to connect one port of one side of the 1 × 2 optical switch device to the network interface,
The two ports on the two sides of the n × 2 optical switch device and the two ports on the two sides of the 1 × 2 optical switch device in the center device are connected by a working optical fiber and a standby optical fiber,
Of the m ports on the m side of the working m × 1 optical switch device, the k th (k = 1, 2, 3,... M) port and the m side of the standby m × 1 optical switch device. The k-th (k = 1, 2, 3... M) of the m ports are connected to the two ports on the two sides of the k-th n × 2 optical switch device, respectively. Connect with
When the working optical fiber or the working m × 1 optical switch device fails between the 1 × 2 optical switch device and the n × 2 optical switch device in the center device, the working optical fiber And the active m × 1 optical switch device automatically switches to the standby optical fiber and the standby m × 1 optical switch device, respectively.
Or, between the 1 × 2 optical switch device and the n × 2 optical switch device in the center device, the active optical fiber and the active m × 1 optical switch device are respectively in accordance with an instruction from the center device. An optical access network method comprising switching to the standby optical fiber and the active m × 1 optical switch device.   The optical access network method according to claim 9, wherein n of the n × 2 optical switch device is 1.   11. The optical access network method according to claim 10, wherein the 1 × 2 optical switch device is installed in the remote device or in the vicinity of the remote device. In an optical access network system composed of a center device, a remote device, an optical switch device, and an optical fiber,
The optical switch device is an optical switch device comprising means for switching an nx2 optical signal according to claim 1 or 2 , wherein one optical switch device is installed in the optical access network,
A maximum of n remote devices are connected to n ports on the n side of the n × 2 optical switch device by the optical fiber, respectively.
The center device includes two network interfaces of the current system network interface and a standby system network interface,
The two ports on the two sides of the n × 2 optical switch device are connected to the active network interface and the standby network interface in the center device by an active optical fiber and a standby optical fiber, respectively.
When the working optical fiber or the working network interface fails between the center device and the n × 2 optical switch device, the working optical fiber and the working network interface are respectively connected to the standby optical fiber. Automatically switch to fiber and the backup network interface;
Alternatively, between the center device and the n × 2 optical switch device, according to an instruction from the center device, the working optical fiber and the working network interface are changed to the standby optical fiber and the standby network interface, respectively. An optical access network system characterized by switching. In an optical access network system composed of a center device, a remote device, an optical switch device, and an optical fiber,
The optical switch device is an optical switch device comprising means for switching an nx2 optical signal according to claim 1 or 2 , wherein one optical switch device is installed in the optical access network,
A maximum of n remote devices are connected to the n ports on the n side of the n × 2 optical switch device by the optical fiber, respectively.
The center apparatus is provided with a single network interface and the 1 × 2 optical switch device of one, connect one port of one side of the 1 × 2 optical switch device to the network interface,
The two ports on the two sides of the n × 2 optical switch device and the two ports on the two sides of the 1 × 2 optical switch device in the center device are connected by a working optical fiber and a standby optical fiber, respectively. ,
When the working optical fiber fails between the 1 × 2 optical switch device and the n × 2 optical switch device in the center device, the working optical fiber automatically becomes a standby optical fiber. Switching,
Alternatively, the active optical fiber is switched to the standby optical fiber according to an instruction from the center device between the 1 × 2 optical switch device and the n × 2 optical switch device in the center device. Optical access network system.

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