JP4612065B2 - Duplex optical access device and duplex path switching method thereof - Google Patents

Description

  The present invention duplicates an optical access section composed of an optical subscriber line unit (OSU) and an optical network unit (ONU) connected via an optical line, and Ethernet (registered trademark). The present invention relates to a duplexed optical access apparatus that switches between an active system and a standby system by detecting a failure using an OAM (Operation Administration Management) frame and a duplex path switching method thereof.

  The active and standby OSUs are accommodated in an optical subscriber line terminal (OLT) connected to the Ethernet wide area network via an upper node (SW).

  Conventionally, a duplex access system has a configuration in which one switching system and the other switching terminal exchange control signals with each other to select one access system as an active system (Patent Document 1).

In addition, conventional optical access devices such as ONUs and OSUs (OLTs) in the Ethernet network simply acquire life / activity monitoring and link down status, and obtain the status of the optical access device as information from the device status and path status. There was no one that realized the dual access system for switching.
JP 2003-51765 A

  In the conventional duplex access system, although the accommodation of the circuit unit is duplexed at the switching end, the selector function unit that performs route selection has a single configuration, so that if a single failure occurs in that location, the selector In some cases, the function was disabled and the redundant configuration could not be used effectively.

  In addition, the OLT is installed in the station and accommodates a plurality of lines. However, when a selector function unit is provided for each OLT, the switching function of all lines accommodated by the OLT is impossible due to the failure of the selector function part. There was a problem to become.

  The present invention relates to a duplexed optical access apparatus capable of duplexing an optical access section composed of an OSU and an ONU connected via an optical line and switching between an active system and a standby system by detecting a failure using an Ethernet OAM frame. An object of the present invention is to provide a duplex path switching method.

According to a first aspect of the present invention, there is provided a duplexed optical access apparatus for duplexing an optical access section composed of an OSU and an ONU connected through an optical line and switching between an active system and a standby system. Are connected via the control path, and the active OSU passes the user frame, the user Ethernet OAM frame, and the network Ethernet OAM frame via the first active / standby selector function unit , The standby OSU is configured to block the user frame and the user Ethernet OAM frame via the second active / standby selector function unit and pass the network Ethernet OAM frame, and the active OSU Complementary opening and closing triggered by failure detection using Ethernet OAM frame The control for switching the active OSU to the standby system and switching the standby OSU to the active system by the first active / standby selector function unit and the second active / standby selector function unit via the control path comprising a first control means for performing, the preliminary ONU that is connected to the OSU of OSU and a standby system of the working system is the active system if possible communication through OSU and optical line, if the communication is impossible Second control means for autonomously controlling processing to be used in the system is provided.

The first control unit of the OSU confirms whether or not the standby OSU has detected a failure when the active OSU detects a failure. If the standby OSU has not detected a failure , the first OSU control unit In this configuration, the link between the system ONU and the user terminal is linked up, and the active OSU is switched to the standby system, and the standby OSU is switched to the active system. Further, the first control unit of the OSU is configured to perform instantaneous interruption control for link-up after the link connected to the higher-level node is linked down when the active OSU is switched to the standby system.

According to a second aspect of the present invention, there is provided a duplex path switching method in which an optical access section composed of an OSU and an ONU connected via an optical line is duplexed to switch between an active system and a standby system. Are connected via the control path, and the active OSU passes the user frame, the user Ethernet OAM frame, and the network Ethernet OAM frame via the first active / standby selector function unit , OSU of the standby system through the second active system, the standby system selector function unit to cut off the Ethernet OAM frame of a user frame and the user, a setting for passing a network of Ethernet OAM frame, OSU of the working system is triggered failure detection using Ethernet OAM frame, the complementarily opened and closed Of the active system, the standby system selector function unit and a second working system, replacement system selector function unit switches the OSU of the working system to the protection system, via the control path toggle its control to the working system to OSU the standby The ONU connected to the active OSU and the standby OSU is autonomously controlled if the OSU can communicate with the OSU via an optical line, and autonomously controls the standby system if communication is not possible. .

  Further, the OSU checks whether or not the standby OSU has detected a failure when a failure is detected, and if the standby OSU has not detected a failure, links the link between the standby ONU and the user terminal. The active OSU is switched to the standby system, and the standby OSU is switched to the active system. In addition, when the OSU is switched from the active system to the standby system, the OSU performs instantaneous interruption control to link up after the link connected to the upper node is linked down.

  The present invention can continue operation by using the Ethernet OAM frame and switching between the active system and the standby system when a failure is detected in the duplexed optical access section. In particular, the duplexed optical access device of the present invention detects the operability of the device itself by Ethernet OAM, the physical and logical connectivity of the interface and the line, the operability of the opposing device itself, and the physical connectivity. As described above, by automatically switching the system for permitting Ethernet frame communication, redundancy is ensured and disconnection time is minimized. Thereby, the communication continuity in the optical access section is dramatically improved.

  In addition, the ONU, which is concerned about the impact on the user environment, can be installed in different places, for example, different floors, etc. by adopting a simple and independent configuration that does not have a function as a switching end, and due to risk dispersion Reliability can be improved.

FIG. 1 shows an embodiment of a duplexed optical access apparatus of the present invention.
In the figure, the duplexed optical access apparatus of this embodiment is equipped with two OSUs 11 and 12 that accommodate the line unit in the OLT 10, and the ONUs 31 and 32 are connected to the OSUs 11 and 12 via the optical lines 21 and 22, respectively. In this configuration, the optical access section is duplicated. Here, the OSU 11, the optical line 21, and the ONU 31 are the active transmission lines, and the OSU 12, the optical line 22, and the ONU 32 are the standby transmission lines.

  The OSU 11 includes a switch 15 between the OSU port 13 on the optical line side and the SNI port 14 on the network side. The OSU 12 includes a switch 18 between the OSU port 16 on the optical line side and the SNI port 17 on the network side. In addition, the switch functions of the active and standby systems are realized by the switches 15 and 18 being opened and closed in a complementary manner. The ONU 31 is configured to connect the ONU port 33 on the optical line side and the UNI port 34 on the user terminal side, and the ONU 32 is configured to connect the ONU port 35 on the optical line side and the UNI port 36 on the user terminal side.

  Here, the switch 15 of the active OSU 11 permits passage of the user frame, the user Ethernet OAM frame, and the network Ethernet OAM frame. On the other hand, the switch 18 of the standby OSU 12 blocks the user frame and the user Ethernet OAM frame and transparently transfers the network Ethernet OAM frame.

FIG. 2 shows a transfer path of the Ethernet OAM frame in the network.
In the figure, failure detection (CC: Continuity Check) is performed by transmitting and receiving connectivity check frames between the upper node (SW) on the network side and the ONU and between the OSU and the ONU via the OSU. The loopback test (LB: Loopback) and performance measurement (DM: Delay Monitor) are performed between the upper node (SW) on the network side and the ONU via the OSU, between the upper node (SW) on the network side and the OSU, Control frames are transmitted and received between the OSU and the ONU.

  Ethernet OAM checks the reception status of the connectivity check frame periodically transmitted from the opposite device and the information in the received connectivity check frame, and uses the CC function to detect abnormalities in the opposite device and communication path. The connectivity state can be grasped, and the switching process can be started in response to the detected abnormality. Similarly, when the UNI port of the ONU is linked down, the ONU periodically transmits an alarm transfer frame to notify the OSU of the alarm state, and the OSU receives the alarm transfer frame to detect an abnormality of the UNI port. The current UNI link state can be grasped by the AIS function to be detected, and the switching process can be started in response to the detected abnormality.

  The OSU controls the state of the ONU with a control frame transmitted via an optical line, and also exchanges control signals with the OSU that is paired with the active system and the standby system via the control path to transmit the active system. In this configuration, a route is selected by determining a route (OSU, optical line, ONU). At this time, there is no influence on the communication and switching functions of OSUs of other systems.

FIG. 3 shows an example of duplex path switching of the duplex optical access apparatus of the present invention.
In the figure, a user who uses a duplexed optical access apparatus having duplexed optical access sections connects user NW (network) devices 41 and 42 to ONUs 31 and 32, respectively, and further connects user NW devices 41 and 42 to each other. The user terminal 43 is connected to the user NW device 41. On the other hand, the OSUs 11 and 12 are connected to a network 53 via upper nodes (SW) 51 and 52, and further connected to a user terminal 44 as a communication partner.

  The user terminal 43 and the user terminal 44 are first connected via the user NW device 41, the active ONU 31, the optical line 21, and the OSU 11. Here, when a failure such as a failure occurs in the working transmission line (OSU 11, optical line 21, ONU 31) and the OSU 11 detects this using the Ethernet OAM frame, the OST 11 and the OSU 12 control the OLT 10. Active line transmission path failure information is exchanged via the path. In response to this, the OLT 10 changes the state of the OSU 11 from the active system to the standby system and the standby OSU 12 from the standby system to the active system. That is, the switches 15 and 18 of the OSUs 11 and 12 are complementarily opened and closed to change the system that permits the communication of the user frame and the user's Ethernet OAM frame. As a result, the user terminal 43 and the user terminal 44 are connected via the user NW device 41, the user NW device 42, the ONU 32, the optical line 22, and the OSU 12 that are switched from the standby system to the active system.

  Thus, in this embodiment, the ONUs 31 and 32 are installed by exchanging control signals between the OSUs 11 and 12 and selecting the active system and the standby system at one switching end where the OLT 10 is installed. At the other switching end, the ONUs 31 and 32 can select a route without exchanging control signals between them. The ONUs 31 and 32 are basically regarded as active or standby systems depending on the OSUs 11 and 12 connected to face each other, and lamp display and UNI interface control are performed. However, the ONUs are independent of each other. Therefore, it is completely duplicated, so that the entire system does not stop for a single failure in the house, and one failure does not directly affect the other.

FIG. 4 shows an example of the processing procedure of the duplex path switching processing method of the present invention.
In the figure, the OSU transmits / receives an Ethernet OAM frame to / from a pair of ONUs, and grasps the state by the CC, LB, DM, etc. shown in FIG. As a result, when the active OSU detects an alarm due to a failure or the like (S1), it confirms whether the standby OSU has not detected an alarm (S2). If the standby OSU detects an alarm, the switching process is stopped because the switching is impossible (S3).

  On the other hand, if the standby OSU has not detected an alarm, the UNI setting of the standby ONU is confirmed (S4). As shown in FIG. 3, this is a duplex configuration of an optical access section that provides two UNI interfaces to the user, so the UNI port of the standby ONU is set up to link up normally and the link down is performed. You can select the settings you want to keep. Therefore, when the UNI port of the standby ONU is set to link down, it is necessary to determine whether or not the user terminal is ready for link up before the switching process. Therefore, when the link down setting is made in step S4, the link up of the UNI port of the standby ONU is tried immediately before the switching process is executed (S5), and the switching process is performed when it is successful.

  When the switching process is performed due to a failure (link down) of the UNI port of the active ONU, the ONU is changed from the active system to the standby system. The ONU changed to the standby system continues the link-up trial regardless of the link-up setting or the link-down setting. After the failure is recovered and the link is up once, the UNI port is set according to the link setting of the UNI port of the standby ONU. Link-up is continued or the UNI port is set to link-down.

  As described above, when the active OSU for alarm detection confirms the link-up of the UNI port of the standby ONU where no alarm is detected, first, processing for switching the active OSU to the standby system is performed (S6). That is, the user frame transfer is stopped and the standby lamp is displayed. Next, a process of switching the standby OSU to the active system is performed (S7). That is, user frame transfer is started and the working lamp is displayed.

  When the working / standby of the active OSU and the standby OSU is switched, the working ONU is switched to the standby system (S8), the completion of switching to the standby ONU is confirmed (S9), and the standby ONU is switched to the working system ( S10), the completion of switching to the active ONU is confirmed (S11). Note that the ONU has a subordinate relationship in which the state is instructed by a control frame transferred from the OSU via the optical line. Therefore, the ONU has monitoring control / alarm processing that autonomously controls when it detects a state where it cannot communicate over the optical line (ONU port tank down, ONU port low MEG level LOC). It is configured to control as a standby system.

  Also, the OSU that has been switched from the active system to the standby system instantaneously disconnects (link down & link up) the SNI port (S12, S13). The upper node (SW) connected to the SNI port does not exchange control signals related to switching between the active system and the standby system with the duplexed optical access device. Thereby, the upper node can secure the degree of freedom. On the other hand, a layer 2 switch (L2SW) that is a network device constituting the Ethernet wide area network is connected to the upper node. The L2SW performs route selection by MAC address learning, and when the FDB (Forwarding DataBase) that is route information is flushed for some reason, the route is changed by relearning the address. The duplexed optical access device can trigger the FDB flush of the higher-level node by instantaneously interrupting the SNI port of the OSU that becomes the standby system when switching is performed.

The figure which shows embodiment of the duplexed optical access apparatus of this invention. The figure which shows the transfer path | route of the Ethernet OAM frame of a network. The figure which shows the example of duplex path | route switching of the duplex optical access apparatus of this invention. The flowchart which shows the process sequence of the duplex path | route switching method of this invention.

Explanation of symbols

10 Optical subscriber line terminal equipment (OLT)
11, 12 Optical subscriber line termination unit (OSU)
13, 16 OSU port 14, 17 SNI port 15, 18 Switch 21, 22 Optical line 31, 32 Optical network terminator (ONU)
33, 35 ONU port 34, 36 UNI port 41, 42 User NW equipment 43, 44 User terminal 50 Network 51, 52, 53 Upper node (SW)

Claims (6)

In a duplexed optical access device that duplexes an optical access section composed of an optical subscriber line termination unit (OSU) and an optical network termination unit (ONU) connected via an optical line and switches between an active system and a standby system,
The current system OSU and OSU of the spare system with is connected through the control path, OSU of the active system, a user frame via a first working system-protection system selector function unit, the user of the Ethernet passed through a OAM frame and network Ethernet OAM frame, OSU of the standby system, via a second primary system, replacement system selector function unit to cut off the Ethernet OAM frame of a user frame and user, the network of the Ethernet OAM frame Is configured to pass through,
The working OSU includes the first working / standby selector function unit and the second working / standby selector function unit that open and close complementarily upon detection of a failure using the Ethernet OAM frame. wherein switching the OSU of the working system to the standby system, the control of switching the OSU of the standby system to the active system comprises a first control means for performing via the control path by,
The ONUs connected to the active OSU and the standby OSU are autonomous when the OSU can communicate with the OSU through the optical line, and autonomous when the communication is impossible. A duplexed optical access apparatus comprising a second control means for controlling. The duplexed optical access device according to claim 1,
The first control unit of the OSU confirms whether or not the standby OSU has detected a failure when the active OSU detects a failure, and if the standby OSU has not detected a failure. The duplexed optical system is configured to link up the link between the standby ONU and the user terminal, switch the active OSU to the standby system, and switch the standby OSU to the active system. Access device. The duplexed optical access device according to claim 1,
The first control means of the OSU is configured to perform instantaneous interruption control to link up after the link connected to the upper node is linked down when the active OSU is switched to the standby system. A duplexed optical access device. In a duplex path switching method for duplexing an optical access section composed of an optical subscriber line termination unit (OSU) and an optical network termination unit (ONU) connected via an optical line, and switching between an active system and a standby system,
The current system OSU and OSU of the spare system with is connected through the control path, OSU of the active system, a user frame via a first working system-protection system selector function unit, the user of the Ethernet passed through a OAM frame and network Ethernet OAM frame, OSU of the standby system, via a second primary system, replacement system selector function unit to cut off the Ethernet OAM frame of a user frame and user, the network of the Ethernet OAM frame Is set to pass
The working OSU includes the first working / standby selector function unit and the second working / standby selector function unit that open and close complementarily upon detection of a failure using the Ethernet OAM frame. wherein switching the OSU of the working system to the standby system, the toggle its control OSU of the standby system to the active system is performed via the control path by,
The ONUs connected to the active OSU and the standby OSU are autonomous when the OSU can communicate with the OSU through the optical line, and autonomous when the communication is impossible. A dual path switching method characterized by controlling. In the duplex path switching method according to claim 4,
The OSU confirms whether or not the standby OSU has detected a failure when a failure is detected, and if the standby OSU has not detected a failure, the link between the standby ONU and the user terminal The redundant path switching method is characterized in that the active OSU is switched to the standby system, and the standby OSU is switched to the active system. In the duplex path switching method according to claim 4,
The duplex path switching method according to claim 2, wherein the OSU performs instantaneous interruption control in which a link connected to an upper node is linked down after the active system is switched to a standby system.

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