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WO2011094990A1 - 通路切换方法、系统及下行数据发送方法 - Google Patents

通路切换方法、系统及下行数据发送方法 Download PDF

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Publication number
WO2011094990A1
WO2011094990A1 PCT/CN2010/074427 CN2010074427W WO2011094990A1 WO 2011094990 A1 WO2011094990 A1 WO 2011094990A1 CN 2010074427 W CN2010074427 W CN 2010074427W WO 2011094990 A1 WO2011094990 A1 WO 2011094990A1
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WIPO (PCT)
Prior art keywords
olt
onu
path
identity information
working
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PCT/CN2010/074427
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English (en)
French (fr)
Inventor
张伟良
张德智
耿丹
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ZTE Corp
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ZTE Corp
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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q11/0067—Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/03—Arrangements for fault recovery
    • H04B10/032—Arrangements for fault recovery using working and protection systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0079—Operation or maintenance aspects
    • H04Q2011/0081—Fault tolerance; Redundancy; Recovery; Reconfigurability

Definitions

  • the present invention relates to passive optical network technologies, and in particular, to a path switching method, a system, and a downlink data sending method in a passive optical network.
  • GPON Gigabit-Capable Passive Optical Network
  • PON Passive Optical Network
  • PON Passive Optical Network
  • the GPON is composed of an optical line terminal (OLT, Optical Line Terminal) on the central office, an optical network unit (ONU), and an optical network unit (ONU).
  • ONT optical Line Terminal
  • ONU optical network unit
  • ONU optical network unit
  • the ODN Optical Distribution Network
  • the ODN consists of passive optical components such as single-mode fiber, optical splitter, and optical connector, providing an optical transmission medium for the physical connection between the OLT and the ONU.
  • the data transmission in the downlink direction (from the OLT to the ONU) is broadcast, and each ONU receives all the frames, and then according to the ONU identifier (ONU-ID), the GEM port identifier (GEM-Port ID), and the configuration. Identifies (Allocation-ID) to get the frame of my own.
  • ONU-ID the ONU identifier
  • GEM-Port ID the GEM port identifier
  • Allocation-ID Identifies
  • a downlink frame of a GPON is a Physical Control Block downstream (PCBd) and a payload.
  • PCBd Physical Control Block downstream
  • Psync Physical Synchronization
  • Ident Ident
  • PLOAMd Physical Layer Operation
  • the Administraion and Maintenance downstream domain consists of a Bit Interleaved Parity (BIP), a Plend (payload Length downstream), and an Upstream Bandwidth Map (US BWmap).
  • BIP Bit Interleaved Parity
  • Plend payload Length downstream
  • US BWmap Upstream Bandwidth Map
  • the OLT and the ONU may be far apart, up to several tens of kilometers.
  • the OLT sends (as shown in Figure 2) the downlink frame does not contain the OLT feature information.
  • the staff installs the ONU at the branch fiber access point, the OLT port information corresponding to the point needs to be obtained. To ensure that the ONU is installed in the correct PON system. If the ONU is not installed in the ODN to which the correct OLT belongs, the installed ONU may not work properly.
  • Figure 3 shows a typical network architecture in the protection mode of the existing passive optical network standard.
  • Figure 4 is a schematic diagram of another typical network architecture in the protection mode in the existing passive optical network standard.
  • Figure 3 shows the manner in which Type B protects the backbone fiber.
  • the two optical ports of the OLT namely the passive optical network line terminal optical port 0 (PON LT(O)) and port 1 (PON LT(l)) are connected to a 2:N splitter.
  • the downstream direction of the optical splitter is respectively connected to each ONU through optical fibers (the number is from N1 to #N). It is assumed that the optical port PON LT(0) of the OLT passes through the optical splitter to the path of the ONU as the primary path, and the optical port PON LT(1) of the OLT passes through the optical splitter to the ONU as the standby path.
  • FIG. 4 shows the all-fiber protection of Type C.
  • the optical port PON LT(0) of the OLT is connected to the 1:N splitter 1
  • the optical port PON LT(l) of the OLT is connected to the 1:N splitter 2
  • the two splitters respectively pass The fiber is connected to each ONU.
  • the optical port PON LT(O) of the OLT reaches the path of the ONU through the optical splitter 1 as the primary path, and the path of the optical port PON LT(1) of the OLT to the ONU through the optical splitter 2 is the standby path.
  • the alternate path is enabled as the service path of the optical network unit and the optical line terminal to maintain communication between the optical network unit and the optical line terminal.
  • Figure 5 is a schematic diagram of the logical state transition process of the optical network unit when the standby path is enabled after the failure of the existing primary path. As shown in Figure 5, it is assumed that the ONU and the OLT pass the primary path between the two, that is, PON LT (O The channel communication of the port, the ONU is in the running state (05); after the main channel is interrupted, it includes:
  • the ONU does not detect the optical signal of the OLT in the primary path, generates a loss of synchronization (LOS/LOF) alarm, and enters a pop-up state (06). After the ONU is in the pop-up state (06) for longer than the time set by the T02 timer, Enter the initial state (01);
  • LOS/LOF loss of synchronization
  • the OLT enables the alternate path, that is, the path of the PON LT(1) port, synchronizes the alternate channel related protocol configuration parameters (such as the transmitted optical power, the ONU ID, the T-CONT ID, the GEM ID, etc.), and sends the downlink optical signal to the ONU, and the ONU. Perform frame delimitation and synchronization;
  • the ONU After detecting the downlink optical signal of the OLT, the ONU cancels the LOS/LOF alarm of the OLT, and after the frame is delimited and synchronized by the standby path and the OLT, the ONU transitions from the initial state (01) to the standby state (02);
  • the ONU After receiving the uplink overhead parameter sent by the OLT, the ONU transits from the standby state ( 02 ) to the sequence number state ( 03 ); the uplink overhead parameter includes: a preamble bit type, a delimiter parameter, and a delimiter parameter.
  • the uplink overhead parameter includes: a preamble bit type, a delimiter parameter, and a delimiter parameter.
  • the ONU After receiving the EqD (Equalization Delay) message sent by the OLT, the ONU transits from the ranging state (04) to the running state (05);
  • the OLT needs to send EqD and other related data to all ONUs.
  • Each ONU needs to update its own parameters after receiving the relevant data, and the alternate path is The adjustment of the transmit power is completed between the OLT optical ports, and finally the normal working state can be restored.
  • 0LT needs to interact with 32 ONUs and complete the state as shown in Figure 5.
  • Migration process ie experiencing 01, 02, 03, 04 and 05. It can be seen that the existing path switching process has the following problems:
  • the main object of the present invention is to provide a path switching method and system in a passive optical network, which can shorten the time of path switching and quickly realize the recovery of normal communication between the ONU and the OLT.
  • Another object of the present invention is to provide a method for transmitting downlink data in a passive optical network, which ensures that the ONU is installed in the ODN to which the correct OLT belongs, and ensures normal operation of the ONU.
  • a path switching method includes:
  • the current working optical line terminal OLT sends downlink data carrying the identity information of the OLT to the optical network unit ONU;
  • the ONU receives and parses the downlink data to obtain identity information of the current working OLT.
  • the ONU detects that the identity information of the current working OLT changes, the ONU performs path switching.
  • the ONU When the ONU detects that the identity information of the current working OLT changes, the ONU performs the path switching, including:
  • the ONU When the ONU detects that the identity information of the current working OLT changes, the ONU configures its working parameters as an alternate path according to the correspondence between the identity information of the OLT and the working parameters of the ONU on the standby path. After entering the working parameters, the working parameters.
  • the current working OLT sends the downlink data carrying the identity information of the OLT to the ONU, including:
  • the OLT on the primary path sends the downlink data carrying the identity information of the OLT to the ONU; when the primary path is invalid, the standby path acts as the working path, and the OLT on the working path sends the carrying to the ONU. There is downlink data of the identity information of the OLT.
  • the ONU receives identity information from the OLT when in the following state: a standby state; or, transitions from a standby state to a sequence number state, and is in a sequence number state; or, from The standby state shifts to the serial number state, and then shifts from the serial number state to the ranging state, and is in the ranging state.
  • the ONU stores the correspondence between the identity information of the OLT on the alternate path and the working parameters of the ONU on the standby path in the following manner:
  • the OLT on the standby path sends its own identity information to the OLT on the primary path, and performs measurement of the operating parameters of all ONUs on the standby path through the OLT on the primary path;
  • the OLT on the primary path sends the identity information of the OLT on the received standby path and the measured working parameters of the measured ONU on the standby path to the corresponding ONU;
  • the ONU receives the identity information of the OLT and the working parameters of the ONU on the standby path that are sent by the OLT on the primary path, and stores the correspondence between the identity information and the working parameter.
  • the ONU stores the correspondence between the identity information of the OLT on the alternate path and the working parameters of the ONU on the standby path in the following manner:
  • the ONU stores the identity information of the OLT on the alternate path and the working parameters of the ONU on the alternate path, and the corresponding relationship between the two is the system default setting.
  • the OLT sends the downlink data carrying the identity information of the OLT by: carrying the identity information in a newly added domain in a downlink frame, where the newly added domain is located in a downlink of a downlink frame of the GPON Physical control block in the PCBd domain, or in the GEM header of the payload of the downstream frame of the GPON;
  • the identity information is carried in an existing domain in a downlink frame, where the existing domain is a downlink physical layer OAM PLOAMd domain, or a payload domain.
  • the identity information of the OLT includes one or any combination of the following: a country where the OLT is located, a city where the OLT is located, OLT identification information, slot identification information of the OLT, port identification information currently working by the OLT, and information about the transmitted optical power of the OLT. Or, The logical information that has a preset correspondence with the identity information of the actual OLT.
  • a path switching system including an optical line terminal OLT and an optical network unit ONU; when the path is used as a working path, the OLT on the working path is configured to send downlink data carrying the identity information of the OLT to the ONU;
  • the ONU is configured to store the correspondence between the identity information of the OLT on the standby path and the working parameters of the ONU on the standby path when the primary path is normally communicating; and is further configured to receive and parse the downlink data to obtain the current work.
  • the identity information of the OLT is used, and when the identity information of the current working OLT is detected, the working parameter is configured as the working parameter of the standby path according to the corresponding relationship stored by the OLT, and then enters the working state.
  • the OLT on the standby path is configured to send its own identity information to the OLT on the primary path;
  • the OLT on the primary path is used to complete the measurement of the working parameters of all the ONUs on the standby path, and send the identity information of the OLT on the received standby path and the measured working parameters of the measured ONU on the standby path. Give the corresponding ONU;
  • the ONU is configured to receive the identity information of the OLT on the standby path sent by the OLT on the primary path and the working parameter of the ONU on the standby path, and then store the correspondence between the identity information and the working parameter; or
  • the ONU stores the identity information of the OLT on the standby path and the working parameters of the ONU on the standby path, and the corresponding relationship between the two is a system default setting.
  • a method for transmitting downlink data includes:
  • the current working optical line terminal OLT sends downlink data carrying the identity information of the OLT to the optical network unit ONU;
  • the ONU receives and parses the downlink data, obtains identity information of the current working OLT, and performs Display.
  • the OLT sends the downlink data carrying the identity information of the OLT by: carrying the identity information in a newly added domain in a downlink frame, where the newly added domain is located in a downlink of a downlink frame of the GPON Physical control block in the PCBd domain, or in the GEM header of the payload of the downstream frame of the GPON;
  • the identity information is carried in an existing domain in a downlink frame, where the existing domain is a downlink physical layer OAM PLOAMd domain, or a payload domain.
  • the identity information of the OLT includes one or any combination of the following: a country where the OLT is located, a city where the OLT is located, OLT identification information, slot identification information of the OLT, port identification information currently working by the OLT, and information about the transmitted optical power of the OLT. Or,
  • the logical information that has a preset correspondence with the identity information of the actual OLT.
  • the ONU is a handheld terminal with a display.
  • the ONU displays the identity information of the OLT through a network management.
  • the OLT and the ONU quickly transfer to the standby path after the failure of the primary path, and the ONU skips the existing registration activation step.
  • the time required for the conversion of the OLT and the ONU from the primary path to the alternate path is reduced, and the communication efficiency between the OLT and the ONU is improved.
  • the OLT sends downlink data carrying the identity information of the OLT to the ONU, and the ONU receives the downlink data, and can identify and display the identity information of the current working OLT, thereby ensuring that the ONU is installed correctly. In the PON, the normal installation of the ONU is guaranteed.
  • FIG. 1 is a schematic diagram of a topology of an existing GPON system
  • FIG. 2 is a schematic diagram of a downlink frame structure of a GTC layer of an existing GPON
  • Figure 3 is a schematic diagram of a typical network architecture in the protection mode in the existing passive optical network standard
  • 4 is a schematic diagram of another typical network architecture in the protection mode in the existing passive optical network standard
  • FIG. 5 is a schematic diagram of a logical state transition process of an optical network unit when an alternate path is enabled after an existing primary path fails;
  • FIG. 6 is a schematic diagram of a downlink frame structure of a GTC layer of a GPON according to the present invention.
  • FIG. 7 is a flow chart of implementing path switching according to the present invention. detailed description
  • the downlink data sending method of the present invention includes: the OLT sends downlink data carrying the identity information of the OLT to the ONU, and the ONU receives and parses the downlink data, obtains the identity information of the current working OLT, and displays the information.
  • the identity information of the OLT can be carried in the following manner:
  • the identity information of the OLT is carried in a newly added domain in the downlink frame.
  • the newly added domain may be located in the PCBd domain of the GPON downlink frame or in the GEM frame header of the payload of the GPON downlink frame.
  • adding a domain in the PCBd field of the GPON downlink frame to carry the identity information of the OLT that transmits the downlink frame is an example.
  • FIG. 6 is a schematic diagram of a downlink frame structure of the GTC layer of the GPON according to the present invention.
  • the PON identification information (PON-ID, PON identifier) field is included in the PCBd domain of the downstream frame of the GPON, and the PON-ID field is located between the Psync domain and the Ident domain (FIG. 6 is only for the PON-ID).
  • the location gives an example, and the PON-ID can also be located elsewhere in the PCBd domain).
  • the PON-ID field is used to carry the identity information of the OLT (ie, PON-ID information), including one or any combination of the following: the country where the OLT is located (Country), the city where the OLT is located (City), and the OLT identification information (OLT-ID) ), the slot identification information (Slot-ID) of the OLT, the port identification information (Port-ID) at which the OLT is currently working, and the transmitted optical power information (Power) of the OLT.
  • the identity information used by the PON-ID domain to carry the OLT may also be logical information, that is, a code or code that has a preset correspondence with the actual information.
  • the worker selects a GPON access node and connects a device that can receive the GP0N downlink frame (for example, a handheld terminal with a display) to the access node to receive the downlink frame, and the staff receives the data according to the reception.
  • the information of the PON-ID field in the downlink frame to which it is determined determines whether the currently used access node belongs to the PON to be accessed by the ONU, thereby ensuring that the ONU is installed in the correct PON.
  • the ONU after receiving the transmitted optical power information of the OLT in the PON-ID domain, the ONU compares with the OLT optical power received by the ONU itself to calculate the link loss of the PON system.
  • Manner 2 The identity information of the OLT is carried in an existing domain in a downlink frame, such as in a PLOAMd domain (or PLOAM message), or in a payload. among them,
  • the PLOAM message carrying the identity information of the OLT is referred to herein as a PON-ID message, and the format of the PON-ID message is as shown in Table 1.
  • the first byte of the PON-ID message is the value of the ONU-ID, and the content of the byte is 11111111, indicating that the message is broadcast to all ONUs; the content of the byte is 11111110, indicating to all The registered ONU broadcasts the message; when the content of the byte is the ONU-ID 1 other than 11111111 and 11111110, the message is sent to the ONU whose ONU-ID value is ONU-ID1.
  • the content of the second byte of the PON-ID message indicates that the type of the PLOAM message is the PON identification information type.
  • the contents of the third to twelfth bytes of the PON-ID message are the identity information of the OLT, including: the country where the OLT is located, the city where the OLT is located, the OLT-ID, the Slot-ID, the Port-ID, and the transmitted optical power information of the OLT. .
  • the OLT may send the broadcast PON-ID message in a certain period; or, after receiving the PON-ID request message sent by an ONU, the OLT sends a PON-ID message to the ONU that sends the PON-ID request.
  • the format of the PON-ID request message sent by the ONU is shown in Table 2.
  • the first byte of the PON-ID request message is the value of the ONU-ID, indicating that the message is from the ONU whose ONU-ID value is ONU-ID 1.
  • the content of the second byte of the PON-ID request message indicates that the type of the PLOAM message is the PON-ID request type.
  • the identity information of the OLT may also be carried by the newly created OMCI message, and the OMCI message carrying the identity information of the OLT is referred to herein as a PON-ID message.
  • the OMCI message may include a Message type field and a Message contents field.
  • the message type field includes a PON-ID message for indicating that the message is the identity information of the OLT, for example, bit 1 to bit 5.
  • the message content field is used to carry the identity information of the OLT, including: the country where the OLT is located, and the OLT. City, OLT-ID, Slot-ID, Port-ID, OLT transmit optical power information.
  • the value of the port identifier (Port-ID) in the GEM header of the GEM frame encapsulating the OMCI It can be set to 11111110, indicating that the type of OMCI message encapsulated by the GEM frame is a PON-ID message.
  • the OLT can send the OMCI message with the message type PON-ID in a certain period. After receiving the PON-ID type OMCI message sent by the OLT, the ONU obtains the identity information of the OLT that sends the message according to the message content field of the OMCI message.
  • the ONU After the PON-ID message sent by the OLT is received by the ONU, the ONU compares with the OLT optical power received by the ONU according to the received optical power information of the OLT in the PON-ID message, and calculates the PON system link. loss.
  • FIG. 7 is a flowchart of implementing path switching according to the present invention. As shown in FIG. 7, the method includes the following steps: Step 700: When the primary path is used as the working path for normal communication, the OLT on the primary path is sent by using the foregoing mode 1 or mode 2. The downlink data of the identity information is sent to the ONU, and the ONU receives and parses the downlink data to obtain the identity of the current working OLT. The ONU stores the correspondence between the PON identity information of the OLT of the standby path and the working parameters of the ONU in the standby path.
  • This step generally includes: when the primary path is used as the working path, the OLT on the standby path sends its own identity information to the OLT on the primary path, and the OLT on the standby path completes all ONUs through the OLT on the primary path. Measurement of the working parameters on the alternate path; the OLT on the primary path sends the identity information of the OLT on the alternate path and the operating parameters of the ONU on the alternate path to all ONUs through the newly created PLOAM message or GEM frame; After receiving the foregoing information sent by the OLT on the primary path, the ONU stores the correspondence between the identity information of the OLT on the standby path and the working parameters of the ONU on the standby path; or
  • the ONU stores the identity information of the OLT on the standby path and the working parameters of the ONU on the standby path, and the corresponding relationship between the two is the system default setting. This step emphasizes that, regardless of the method, the ONU stores the identity information PON-ID and ONU of the OLT on the alternate path. Correspondence of operating parameters on the alternate path.
  • the working parameters of the primary path and the alternate path stored in the ONU in this step include the OLT identity information of the two paths, that is, the PON-ID information, the preamble bit type, the delimiter parameter (Delimiter), and the ONU transmission optical power level parameter. , EqD, Equalization Delay, and the ONU ID assigned to it by the two OLTs.
  • the PON-ID information includes the country where the OLT is located, the city where the OLT is located, the OLT identification information (OLT-ID), the slot identification information of the OLT (Slot-ID), and the identification information (Port-ID) of the current working port of the OLT.
  • the OLT transmits the optical power information, and the ONU identifies the identity of the OLT in the working state according to the PON-ID information sent by the OLT, and configures the above working parameters according to the received PON-ID information of the OLT to establish and work between the OLTs. Communication.
  • Step 701 After the primary path is invalid, the ONU synchronizes with the OLT on the standby path.
  • the ONU After the primary channel for data communication between the ONU and the OLT is invalid, the ONU generates a loss of synchronization (LOS/LOF) alarm and enters the pop-up state (06). The ONU is in the pop-up state (06) for longer than the preset duration of the T02 timer. After that, enter the initial state (01).
  • the OLT enables the alternate path to send the downlink frame, the ONU completes synchronization with the OLT, and the ONU enters the 02 state.
  • Step 702 The standby path is used as the working path, and the OLT on the standby path sends the downlink data carrying the identity information (PON-ID) to the ONU by using mode 1 or mode 2, and the ONU receives and parses the downlink data, and according to the PON in the downlink data.
  • the -ID information gets the identity of the current working OLT.
  • the ONU After the ONU finds that the identity information of the OLT is changed, the ONU configures its working parameters as the working parameters of the standby path according to the corresponding relationship between the OLT identity information stored in the alternate path and the ONU in the standby path working parameter, and then enters the working state. .
  • the OLT and the ONU quickly transfer to the standby path after the primary path fails, and the ONU skips the existing registration activation step from the 02 state to the 05 state, thereby minimizing the OLT and the The time required for the ONU to transition from the primary path to the alternate path maximizes communication efficiency between the OLT and the ONU.
  • the specific implementation of the step 702 may be: the ONU is transferred from the 02 state to the 03 state according to the existing method; and the ONU in the 03 state receives the downlink frame or the PON-ID message sent by the OLT in the mode 1 or mode 2, according to the downlink frame or
  • the PON-ID content carried in the PON-ID message obtains the identity information of the current working OLT, and the ONU configures its own working parameter as the work of the standby path according to the correspondence between the stored PON-ID of the alternate path and the working parameters of the alternate path. Parameters, ONU enters the working state. It can be seen that after the primary path fails, the OLT and the ONU quickly transfer to the standby path.
  • the ONU skips the existing registration activation step from the 03 state to the 05 state, reducing the conversion of the OLT and the ONU from the primary path to the alternate path. The time required to improve communication efficiency between the OLT and the ONU.
  • the specific implementation of the step 702 may be: the ONU shifts from the 02 state to the 03 state according to the existing method, and then shifts from the 03 state to the 04 state; the ONU of the 04 state receives the downlink frame or PON sent by the OLT in the first mode or the second mode.
  • the identity information of the current working OLT is obtained according to the PON-ID content carried in the downlink frame or the PON-ID message, and the ONU is configured according to the correspondence between the stored PON-ID of the alternate path and the working parameters of the standby path.
  • the working parameters of the slave are the working parameters of the standby path, and the ONU enters the working state.
  • the OLT and the ONU quickly transfer to the standby path, and the ONU skips the existing registration activation step from the 04 state to the 05 state, thereby reducing the conversion of the OLT and the ONU from the primary path to the alternate path.
  • the required time increases the communication efficiency between the OLT and the ONU.
  • a path switching system including 0LT and 0NU, wherein
  • 0LT includes 0LT on the primary path and 0LT on the alternate path.
  • the 0LT of the working path is used to send downlink data carrying the identity information of the 0LT to the 0NU;
  • the ONU is used to store the correspondence between the identity information of the OLT on the standby path and the working parameters of the ONU on the standby path when the primary path is normally communicating; and is also used to receive and parse the downlink number.
  • the identity information of the current working OLT is obtained; and when the identity information of the current working OLT is detected, the working parameter is configured as the working parameter of the standby path according to the corresponding relationship stored by the OLT, and then enters the working state.
  • the ONU receives the PON-ID content sent by the OLT when it is in the 02 state or the 03 state or the 04 state, and obtains the identity information of the current working OLT.
  • the ONU is based on the correspondence between the stored PON-ID of the alternate path and the working parameters of the standby path. Configure its own working parameters as the working parameters of the alternate path, and the ONU enters the working state.
  • the ONU stores the correspondence between the identity information of the OLT on the alternate path and the working parameters of the ONU on the standby path in the following manner:
  • the OLT on the standby path When the primary path is used as the working path, the OLT on the standby path is used to transmit its own identity information to the OLT on the primary path; the OLT on the primary path is used to complete the measurement of the operating parameters of all ONUs on the alternate path. And transmitting the identity information of the OLT on the received standby path and the measured working parameters of the ONU on the standby path to the corresponding ONU; the ONU is configured to receive the OLT on the alternate path sent by the OLT on the active path. The identity information and the ONU store the corresponding relationship between the identity information and the working parameters after the working parameters on the standby path;
  • the ONU stores the identity information of the OLT on the alternate path and the operating parameters of the ONU on the alternate path, and the corresponding relationship between the two is the system default setting.
  • the PON-ID content transmitted in the downlink frame proposed by the present invention may be protected by forward error correction (FEC, Forward Error Correction) coding, or may not be within the range of FEC coding.
  • FEC Forward Error Correction
  • the downlink data transmission method including the PON-ID content proposed by the present invention is also applicable to a GPON-based next generation PON system.

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Abstract

本发明提供了一种通路切换方法、系统及下行数据发送方法，该通路切换方法包括：当前工作光线路终端（OLT）向光网络单元（ONU）发送携带有该OLT的身份信息的下行数据；ONU接收并解析该下行数据，获得当前工作OLT的身份信息；当ONU检测到当前工作OLT的身份信息发生变化时，ONU执行通路切换。ONU跳过现有某些注册激活步骤，减少了OLT和ONU从主用通路到备用通路的转换所需的时间，提高了OLT和ONU之间的通信效率。

Description

通路切换方法、 系统及下行数据发送方法 技术领域
本发明涉及无源光网络技术， 尤其涉及一种无源光网络中的通路切换 方法、 系统及下行数据发送方法。 背景技术
吉比特无源光网络（ GPON , Gigabit-Capable Passive Optical Network ) 技术是无源光网络（PON ) 家族中一个重要的技术分支， 和其它 PON技术 类似， GPON也是一种采用点到多点拓朴结构的无源光接入技术。
图 1为现有 GPON系统的拓朴结构示意图， 如图 1所示， GPON由局侧的 光线路终端 （OLT, Optical Line Terminal )、 用户侧的光网络单元（ ONU, Optical Network Unit )以及光分配网络 ( ODN, Optical Distribution Network ) 组成， 通常采用点到多点的网络结构。 ODN由单模光纤、 光分路器、 光连 接器等无源光器件组成， 为 OLT和 ONU之间的物理连接提供光传输媒质。
在 GPON系统中， 下行方向 （由 OLT到 ONU ) 的数据传输采用广播 方式， 每个 ONU分别接收所有的帧， 再根据 ONU标识（ ONU-ID )、 GEM 端口标识（ GEM-Port ID )、 配置标识（ Allocation-ID )来获取属于自己的帧。 对于上行方向 （从 ONU到 OLT ) 的数据传输， 由于各个 ONU需要共享传 输媒质， 因此各个 ONU应该在 OLT安排给自己的时隙内传输上行数据。
图 2为 GPON的传输汇聚（ GTC, G-PON Transmission Convergence ) 层的下行帧结构的示意图， 如图 2所示， GPON的下行帧由下行物理控制 块（PCBd, Physical Control Block downstream )和净荷两部分组成， 其中， PCBd由物理同步域 ( Psync, Physical Synchronization )、 识别 ( Ident )域、 下行物理层操作、 管理与维护 （PLOAMd , Physical Layer Operation , Administraion and Maintenance downstream )域、 比特间插奇禺校验域 ( BIP, Bit Interleaved Parity )、信息净荷长度域 ( Plend, Payload Length downstream ) 和上行带宽映射域（US BWmap )组成。
在无源光网络部署中， 工作人员如果在如图 1所示的 PON系统中安装 ONU, 某些场景下， OLT与 ONU距离可能较远， 以至达几十公里。 按照 目前 GPON协议中 OLT发送（如图 2所示） 的下行帧中并不包含 OLT的 特征信息， 但工作人员在分支光纤接入点安装 ONU时， 需要获取该点所对 应的 OLT端口信息， 以确保 ONU安装在正确的 PON系统中。 如果不能确 保 ONU安装在正确 OLT所属的 ODN中， 可能导致安装的 ONU不能正常 工作。
另外， 在无源光网络的部署应用中， 有部分用户需要较高的安全性， 希望运营商能够提供一种保障机制来确保其业务通路不中断， 或者次一级 的要求是， 能够在业务通路中断后快速恢复。 这就对承载用户业务运行的 无源光网络提出了保护通路和快速切换通路的要求。
图 3 为现有无源光网络标准中， 保护模式下的一种典型的网络架构示 意图， 图 4为现有无源光网络标准中， 保护模式下的另一种典型的网络架 构示意图。
图 3所示是类型 B的保护主干光纤的方式。 如图 3所示， OLT的两个 光口即无源光网络线路终端光口 0 ( PON LT(O) )和端口 1 ( PON LT(l) )均 连接到一个 2: N的分光器，该分光器下行方向分别通过光纤连接到各 ONU (标号从 #1至#N共 N个） 。 假设 OLT的光口 PON LT(0)通过分光器到达 ONU的通路为主用通路， OLT的光口 PON LT(1)通过分光器到达 ONU的 通路为备用通路。 在主用通路作为光网络单元和光线路终端的服务通路中 断后， 将启用备用通路作为光网络单元和光线路终端的服务通路保持光网 络单元和光线路终端间的通信。 图 4所示是类型 C的全光纤保护方式。 如图 4所示， OLT的光口 PON LT(0)连接到 1 : N的分光器 1 , OLT的光口 PON LT(l)连接到 1 : N的分光 器 2,两个分光器分别通过光纤与各 ONU连接。假设 OLT的光口 PON LT(O) 通过分光器 1到达 ONU的通路为主用通路， OLT的光口 PON LT(l)通过分 光器 2到达 ONU的通路为备用通路。在主用通路作为光网络单元和光线路 终端的服务通路中断后， 将启用备用通路作为光网络单元和光线路终端的 服务通路保持光网络单元和光线路终端间的通信。
在图 3和图 4所示的无源光网络的现有的保护模式下， 结合图 5, 以主 用通路故障后启用备用通路的过程为例， 说明光网络单元的逻辑状态迁移 过程。
图 5 为现有主用通路故障后启用备用通路时， 光网络单元的逻辑状态 迁移过程的示意图， 如图 5所示， 假设 ONU与 OLT通过两者之间的主用 通路即 PON LT(O)口的通路通信， ONU处于运行状态（05 ) ； 主用通路中 断后， 包括：
ONU在主用通路检测不到 OLT的光信号， 产生失同步（LOS/LOF ) 告警， 并进入弹出状态（06 ) , ONU处于弹出状态（06 )的时间超过 T02 定时器设定的时长后， 进入初始状态 （01 ) ；
OLT启用备用通路即 PON LT(1)口的通路， 同步备用通路相关协议配 置参数（如发送光功率， ONU ID, T-CONT ID, GEM ID等） ， 并向 ONU 发送下行光信号， 和 ONU进行帧定界和同步；
ONU检测到 OLT的下行光信号后， 消除 OLT的 LOS/LOF告警，通过 备用通路与 OLT完成帧定界和同步后， ONU从初始状态 （01 )转入待机 状态 （ 02 ) ；
ONU接收 OLT发送的上行开销参数后从待机状态 （ 02 )转入序列号 状态（ 03 )；上行开销参数包括：前导码比特类型，定界符参数 ( Delimiter ) , OLT从主用通路切换到备用通路后， 需对其管理的 ONU的 ID进行重 新分配， 并将重新分配后的各 ONU的 ID发送至各 ONU; ONU接收 OLT 发送的 ONU-ID信息后， 从序列号状态 （03 )转入测距状态 （04 ) ；
ONU接收 OLT发送的均衡时延（ EqD, Equalization Delay ) 消息后， 从测距状态 （ 04 )转入运行状态 （ 05 ) ；
至此， ONU与 OLT间的备用通路完全建立， ONU与 OLT通过备用通 路进行信息交互。
在图 5 所示的通路切换过程中， 备用通路上建立物理层通路后， OLT 需发送 EqD等相关数据给所有 ONU, 每一个 0NU都需要在接收相关数据 后更新自身参数， 并与备用通路的 OLT光口间完成对发射功率的调整， 最 后才能恢复正常工作状态。 以图 3所示类型 B的网络结构为例来看， 当一 个 0LT所管理的 0NU共有 32个时， 在通路切换过程中， 0LT需要与 32 个 0NU交互并全部完成如图 5所示的状态迁移过程（即经历 01、 02、 03、 04和 05 ) 。 可见， 现有通路切换流程存在以下问题：
(1)每个 0NU均完成上述一系列的状态迁移，使得 0LT需负担大量的 消息传送工作；
(2) 在处理过程中， 由于 0LT和 0NU之间通路的容量有限， 在 GTC 下行帧中， 没有足够的容量存放物理层运行管理维护 （PLOAM, Physical Layer Operation Administration and Maintenance )消息来支持 32个 0NU同 时完成前述的状态迁移过程， 因此， 大部分 0NU需要等待消息， 延长了通 路切换的时间， 影响了 0NU和 0LT快速恢复正常通信， 使 0NU和 0LT 恢复正常工作基本耗时在 100 毫秒量级以上， 不能满足用户对网络故障快 速恢复的要求。 发明内容
有鉴于此， 本发明的主要目的在于提供一种无源光网络中的通路切换 方法及系统， 能够缩短通路切换的时间， 快速实现 ONU和 OLT正常通信 的恢复。
本发明的另一目的在于提供一种无源光网络中的下行数据发送方法， 能够确保 ONU安装在正确 OLT所属的 ODN中， 保证 ONU的正常工作。
为达到上述目的， 本发明的技术方案是这样实现的：
一种通路切换方法， 包括：
当前工作光线路终端 OLT向光网络单元 ONU发送携带有该 OLT的身 份信息的下行数据；
ONU接收并解析所述下行数据， 获得当前工作 OLT的身份信息； 当 ONU检测到当前工作 OLT的身份信息发生变化时， ONU执行通路切换。
所述当 ONU检测到当前工作 OLT的身份信息发生变化时， ONU执行 通路切换包括：
所述 ONU检测到当前工作 OLT的身份信息发生变化时， 根据自身存 储的备用通路上的 OLT的身份信息和 ONU在备用通路上的工作参数的对 应关系， 将自身的工作参数配置为备用通路的工作参数后进入工作状态。
所述当前工作 OLT向 ONU发送携带有该 OLT的身份信息的下行数据 包括：
当主用通路作为工作通路时， 主用通路上的 OLT向 ONU发送携带有 该 OLT的身份信息的下行数据； 当主用通路无效后， 备用通路作为工作通 路， 该工作通路上的 OLT向 ONU发送携带有该 OLT的身份信息的下行数 据。
所述 ONU在处于以下状态时收到来自所述 OLT的身份信息： 待机状 态； 或者， 从待机状态转移到序列号状态， 并处于序列号状态； 或者， 从 待机状态转移到序列号状态， 然后从序列号状态转移到测距状态， 并处于 测距状态。
ONU通过以下方式存储备用通路上的 OLT的身份信息和 ONU在备用 通路上的工作参数的对应关系：
主用通路作为工作通路时， 备用通路上的 OLT将自身的身份信息发送 给主用通路上的 OLT, 并通过主用通路上的 OLT完成对所有 ONU在备用 通路上的工作参数的测量；
主用通路上的 OLT将接收到的备用通路上的 OLT的身份信息和测量得 到的 ONU在备用通路上的工作参数发送给相应的 ONU;
所述 ONU接收到主用通路上的 OLT发送的所述备用通路上的 OLT的 身份信息和 ONU在备用通路上的工作参数后，存储所述身份信息和所述工 作参数的对应关系。
ONU通过以下方式存储备用通路上的 OLT的身份信息和 ONU在备用 通路上的工作参数的对应关系：
ONU存储备用通路上的 OLT的身份信息和 ONU在备用通路上的工作 参数， 及二者的对应关系为系统默认设置。
所述 OLT通过下述方式发送携带有所述 OLT的身份信息的下行数据： 将所述身份信息携带在下行帧中新增的一个域中， 所述新增的域位于 GPON的下行帧的下行物理控制块 PCBd域中， 或者， 位于 GPON的下行 帧的净荷的 GEM帧头中；
或者将所述身份信息携带在下行帧中的现有域中， 所述现有域为下行 物理层 OAM PLOAMd域， 或净荷域。
所述 OLT的身份信息包括下述之一或任意组合： OLT所在的国家、 OLT 所在的城市、 OLT识别信息、 OLT的槽位识别信息、 OLT当前工作的端口 识别信息、 OLT的发射光功率信息； 或者， 与实际 OLT的身份信息存在预设对应关系的逻辑信息。
一种通路切换系统， 包括光线路终端 OLT及光网络单元 ONU; 用通路作为工作通路时，工作通路上的 OLT用于向 ONU发送携带有该 OLT 的身份信息的下行数据；
所述 ONU,用于在主用通路正常通信时，存储备用通路上的 OLT的身 份信息和 ONU在备用通路上的工作参数的对应关系；还用于接收并解析所 述下行数据， 获得当前工作 OLT的身份信息； 以及用于在检测到当前工作 OLT 的身份信息发生变化时， 根据自身存储的所述对应关系将自身的工作 参数配置为备用通路的工作参数后进入工作状态。
主用通路作为工作通路时，
所述备用通路上的 OLT用于将自身的身份信息发送给所述主用通路上 的 OLT;
所述主用通路上的 OLT用于完成对所有 ONU在备用通路上的工作参 数的测量，并将接收到的备用通路上的 OLT的身份信息和测量得到的 ONU 在备用通路上的工作参数发送给相应的 ONU;
所述 ONU 用于接收到主用通路上的 OLT发送的所述备用通路上的 OLT的身份信息和 ONU在备用通路上的工作参数后存储所述身份信息和 所述工作参数的对应关系； 或者， 所述 ONU存储备用通路上的 OLT的身 份信息和 ONU在备用通路上的工作参数，及二者的对应关系为系统默认设 置。
一种下行数据发送方法， 包括：
当前工作光线路终端 OLT向光网络单元 ONU发送携带有该 OLT的身 份信息的下行数据；
ONU接收并解析所述下行数据，获得当前工作 OLT的身份信息并进行 显示。
所述 OLT通过下述方式发送携带有所述 OLT的身份信息的下行数据： 将所述身份信息携带在下行帧中新增的一个域中， 所述新增的域位于 GPON的下行帧的下行物理控制块 PCBd域中， 或者， 位于 GPON的下行 帧的净荷的 GEM帧头中；
或者将所述身份信息携带在下行帧中的现有域中， 所述现有域为下行 物理层 OAM PLOAMd域， 或净荷域。
所述 OLT的身份信息包括下述之一或任意组合： OLT所在的国家、 OLT 所在的城市、 OLT识别信息、 OLT的槽位识别信息、 OLT当前工作的端口 识别信息、 OLT的发射光功率信息； 或者，
与实际 OLT的身份信息存在预设对应关系的逻辑信息。
所述 ONU为带显示屏的手持终端。
所述 ONU通过网管显示所述 OLT的身份信息。
从上述本发明提供的技术方案可以看出， 通过本发明实现通路切换的 方法和系统， OLT和 ONU在主用通路发生故障后， 快速转移到了备用通路 上， ONU跳过现有的注册激活步驟， 减少了 OLT和 ONU从主用通路到备 用通路的转换所需的时间， 提高了 OLT和 ONU之间的通信效率。 本发明 下行数据发送的方法中， OLT向 ONU发送携带有 OLT的身份信息的下行 数据， ONU接收到下行数据可解析识别出当前工作 OLT的身份信息并进行 显示， 从而确保了 ONU安装在正确的 PON中， 保证了 ONU的正常安装。 附图说明
图 1为现有 GPON系统的拓朴结构示意图；
图 2为现有 GPON的 GTC层的下行帧结构的示意图；
图 3 为现有无源光网络标准中， 保护模式下的一种典型的网络架构示 意图； 图 4为现有无源光网络标准中， 保护模式下的另一种典型的网络架构 示意图；
图 5 为现有主用通路故障后启用备用通路时， 光网络单元的逻辑状态 迁移过程的示意图；
图 6为本发明 GPON的 GTC层的下行帧结构的示意图；
图 7为本发明实现通路切换的流程图。 具体实施方式
本发明下行数据发送方法包括： OLT向 ONU发送携带有 OLT的身份信 息的下行数据， ONU接收并解析下行数据， 获得当前工作 OLT的身份信息 并进行显示。 其中， 可以通过以下方式携带 OLT的身份信息：
方式一， 将 OLT的身份信息携带在下行帧中新增的一个域中， 该新增 的域可以位于 GPON下行帧的 PCBd域中，也可以位于 GPON下行帧的净荷的 GEM帧头中。 以在 GPON下行帧的 PCBd域增加一个域用于携带发送该下行 帧的 OLT的身份信息为例， 图 6为本发明 GPON的 GTC层的下行帧结构的示 意图。
如图 6所示， 在 GPON的下行帧的 PCBd域中包含有 PON识别信息 ( PON-ID, PON identifier )域， PON-ID域位于 Psync域和 Ident域之间 （图 6 只是对 PON-ID的位置给出了一个示例， PON-ID也可以位于 PCBd域的其它 位置）。 PON-ID域用于携带 OLT的身份信息（即 PON-ID信息）， 包括以下之 一或任意组合： OLT所在的国家（Country ), OLT所在的城市 （City )、 OLT 识别信息（OLT-ID )、 OLT的槽位识别信息（ Slot-ID )、 OLT现在工作的端口 识别信息（Port-ID )、 OLT的发射光功率信息（Power )。 当然， PON-ID域用 于携带 OLT的身份信息也可以是逻辑信息，即与实际信息存在预设对应关系 的代号或者编码。
这样， 在 GPON的部署应用中， 当工作人员需要将一个 ONU安装到 GPON系统中时， 工作人员选择一个 GPON的接入节点， 并将一个可以接收 GP0N下行帧的装置（例如， 带显示屏的手持终端）连接到该接入节点以接 收下行帧， 工作人员根据接收到的下行帧中的 PON-ID域的信息， 判断出当 前使用的接入节点是否属于 ONU将要接入的 PON, 从而确保了 ONU安装在 正确的 PON中。 进一步地， ONU接收 PON-ID域内的 OLT的发射光功率信 息后， 和 ONU自身收到的 OLT光功率进行对比， 计算出 PON系统链路损耗。
方式二， 将 OLT的身份信息携带在下行帧中的现有域中， 如 PLOAMd 域（或称 PLOAM消息） 中， 或净荷中。 其中，
携带 OLT 的身份信息的 PLOAM消息在本文中称为 PON-ID 消息， PON-ID消息的格式如表 1所示。
Figure imgf000012_0001
表 1
如表 1所示， PON-ID消息的第 1字节为 ONU-ID的值， 该字节的内容 为 11111111 , 表示向所有 ONU广播该消息； 该字节的内容为 11111110, 表 示向所有未注册激活的 ONU广播该消息； 该字节的内容为除 11111111和 11111110外的值 ONU-ID 1时， 表示该消息发送给 ONU-ID值为 ONU-ID1 的 ONU。 PON-ID消息的第 2字节的内容表示该 PLOAM消息的类型为 PON识 别信息类型。
PON-ID消息的第 3到第 12字节的内容为 OLT的身份信息，包括： OLT 所在的国家、 OLT所在的城市、 OLT-ID、 Slot-ID, Port-ID, OLT的发射光 功率信息。
OLT可以以一定的周期发送广播的 PON-ID消息； 或者， OLT在收到 某个 ONU发送的 PON-ID请求消息后， 给发送 PON-ID请求的 ONU发送 PON-ID消息。 ONU发送的 PON-ID请求消息的格式如表 2所示。
Figure imgf000013_0001
表 2
如表 2所示， PON-ID请求消息的第 1字节为 ONU-ID的值， 表示该消 息来自 ONU-ID值为 ONU-ID 1的 ONU。
PON-ID请求消息的第 2 字节的内容表示该 PLOAM 消息的类型为 PON-ID请求类型。
也可以通过新建的 OMCI消息来携带 OLT的身份信息，携带 OLT的身 份信息的 OMCI消息在本文中称为 PON-ID消息。 OMCI消息可以包括消息 类型 （ Message type )域， 以及消息内容 ( Message contents )域。 其中， 消 息类型域包括用于表示该消息为携带 OLT的身份信息的 PON-ID消息， 比 如比特 1〜比特 5; 消息内容域用于携带 OLT的身份信息， 包括： OLT所在 的国家、 OLT所在的城市、 OLT-ID、 Slot-ID, Port-ID, OLT的发射光功率 信息。 封装该 OMCI的 GEM帧的 GEM帧头中的端口标识（ Port-ID )的值 可以设置为 11111110, 表示该 GEM帧封装的 OMCI消息的类型为 PON-ID 消息。
OLT可以以一定的周期发送消息类型为 PON-ID的 OMCI消息， ONU 接收到 OLT发送的 PON-ID类型的 OMCI消息后， 根据 OMCI消息的消息 内容域获得发送该消息的 OLT的身份信息。
通过方式二， ONU接收到 OLT发送的 PON-ID 消息后， 根据接收 PON-ID消息内的 OLT的发射光功率信息后， 和 ONU自身收到的 OLT光 功率进行对比， 计算出 PON系统链路损耗。
在现有技术中的类型 B和类型 C的 PON保护结构中，当前在工作中的 通路称为主用通路， 主用通路发生故障后， OLT (和 ONU )切换到备用通 路上。 图 7为本发明实现通路切换的流程图， 如图 7所示， 包括以下步驟： 步驟 700: 主用通路作为工作通路正常通信时， 主用通路上的 OLT采用 上述方式一或方式二发送携带自身身份信息的下行数据给 ONU, ONU接收 并解析下行数据获得当前工作 OLT的身份； ONU存储备用通路的 OLT的身 份信息 PON-ID和 ONU在备用通路的工作参数的对应关系。
本步驟大致包括： 主用通路作为工作通路时， 备用通路上的 OLT将自 身的身份信息发送给主用通路上的 OLT,并且备用通路上的 OLT通过主用 通路上的 OLT完成对所有 ONU在备用通路上的工作参数的测量工作； 主 用通路上的 OLT将备用通路上的 OLT的身份信息和 ONU在备用通路上的 工作参数通过新建的 PLOAM消息或 GEM帧发送给所有 ONU; 所述 ONU 接收到主用通路上的 OLT发送的上述信息后， ONU存储备用通路上的 OLT 的身份信息和 ONU在备用通路上的工作参数的对应关系； 或者，
所述 ONU存储备用通路上的 OLT的身份信息和 ONU在备用通路上的 工作参数， 及二者的对应关系为系统默认设置。 本步驟强调的是， 不论通 过什么方法， ONU存储有备用通路上的 OLT的身份信息 PON-ID和 ONU 在备用通路上的工作参数的对应关系。
本步驟中 ONU存储的主用通路和备用通路的工作参数， 包括两个通路 的 OLT 身份信息， 即 PON-ID 信息， 前导码比特类型、 定界符参数 ( Delimiter ), ONU发送光功率水平参数、 均衡时延（EqD, Equalization Delay ), 以及两个 OLT分配给自己的 ONU ID等。 其中， PON-ID信息包括 OLT所在的国家、 OLT所在的城市、 OLT识别信息（OLT-ID )、 OLT的槽 位识别信息 （ Slot-ID )、 OLT现在工作端口的识别信息（ Port-ID )、 OLT的 发射光功率信息， ONU根据 OLT发送的 PON-ID信息识别处于工作状态 OLT的身份，并根据收到的 OLT的 PON-ID信息配置自身的上述工作参数， 以建立和工作 OLT之间的通信。
步驟 701 : 当主用通路无效后， ONU与备用通路上的 OLT实现同步。
ONU 与 OLT 间进行数据通信的主用通路无效后， ONU产生失同步 ( LOS/LOF )告警后， 进入弹出状态 （06 ), ONU处于弹出状态 （06 ) 的 时间超过预设 T02定时器的时长后， 进入初始状态 （01 )。 OLT启用备用 通路发送下行帧， ONU完成与 OLT同步， ONU进入到 02状态。
步驟 702: 备用通路作为工作通路， 备用通路上的 OLT采用方式一或方 式二发送携带自身身份信息 （ PON-ID ) 的下行数据给 ONU, ONU接收并 解析下行数据，并根据下行数据中的 PON-ID信息获得当前工作 OLT的身份。 当 ONU发现所述 OLT的身份信息变化后， ONU根据自身存储的备用通路上 的 OLT身份信息与 ONU在备用通路工作参数的对应关系将自身的工作参数 配置为备用通路的工作参数后进入工作状态。
通过本发明实现通路切换的方法， OLT和 ONU在主用通路发生故障 后，快速转移到了备用通路上， ONU跳过现有从 02状态到 05状态的注册 激活步驟， 最大限度地减少了 OLT和 ONU从主用通路到备用通路的转换 所需的时间， 最大程度地提高了 OLT和 ONU之间的通信效率。 步驟 702的具体实现也可以是： ONU按照现有方法从 02状态转移到 03状态； 03状态的 ONU收到 OLT采用方式一或方式二发送的下行帧或 PON-ID消息后， 根据下行帧或 PON-ID消息中携带的 PON-ID内容， 获得 当前工作 OLT的身份信息， ONU根据存储的备用通路的 PON-ID和备用通 路的工作参数的对应关系， 配置自身的工作参数为备用通路的工作参数， ONU进入工作状态。 可见， OLT和 ONU在主用通路发生故障后， 快速转 移到了备用通路上， ONU跳过现有从 03状态到 05状态的注册激活步驟， 减少了 OLT和 ONU从主用通路到备用通路的转换所需的时间，提高了 OLT 和 ONU之间的通信效率。
步驟 702的具体实现还可以是： ONU按照现有方法从 02状态转移到 03状态， 然后从 03状态转移到 04状态； 04状态的 ONU收到 OLT采用 方式一或方式二发送的下行帧或 PON-ID消息后，根据下行帧或 PON-ID消 息中携带的 PON-ID内容， 获得当前工作 OLT的身份信息， ONU根据存储 的备用通路的 PON-ID和备用通路的工作参数的对应关系，配置自身的工作 参数为备用通路的工作参数， ONU进入工作状态。 可见， OLT和 ONU在 主用通路发生故障后， 快速转移到了备用通路上， ONU跳过现有从 04状 态到 05状态的注册激活步驟，减少了 OLT和 ONU从主用通路到备用通路 的转换所需的时间， 提高了 OLT和 ONU之间的通信效率。
针对本发明图 7所述通路切换方法， 还提供一种通路切换系统， 包括 0LT及 0NU, 其中，
0LT包括主用通路上的 0LT和备用通路上的 0LT, 主用通路或备用通 路作为工作通路时， 工作通路的 0LT用于向 0NU发送携带有该 0LT的身 份信息的下行数据；
ONU用于在主用通路正常通信时，存储备用通路上的 OLT的身份信息 和 ONU在备用通路上的工作参数的对应关系； 还用于接收并解析下行数 据，获得当前工作 OLT的身份信息； 以及用于在检测到当前工作 OLT的身 份信息发生变化时， 根据自身存储的上述对应关系将自身的工作参数配置 为备用通路的工作参数后进入工作状态。
ONU在处于 02状态或 03状态或 04状态时收到 OLT发送的 PON-ID 内容，获得当前工作 OLT的身份信息， ONU根据存储的备用通路的 PON-ID 和备用通路的工作参数的对应关系， 配置自身的工作参数为备用通路的工 作参数， ONU进入工作状态。
ONU通过以下方式存储备用通路上的 OLT的身份信息和 ONU在备用 通路上的工作参数的对应关系：
主用通路作为工作通路时， 备用通路上的 OLT用于将自身的身份信息 发送给主用通路上的 OLT; 主用通路上的 OLT用于完成对所有 ONU在备 用通路上的工作参数的测量， 并将接收到的备用通路上的 OLT的身份信息 和测量得到的 ONU在备用通路上的工作参数发送给相应的 ONU; ONU用 于接收到主用通路上的 OLT发送的备用通路上的 OLT的身份信息和 ONU 在备用通路上的工作参数后存储该身份信息和工作参数的对应关系；
或者， ONU存储备用通路上的 OLT的身份信息和 ONU在备用通路 上的工作参数， 及二者的对应关系为系统默认设置。
需要说明的是，本发明提出的在下行帧内发送的 PON-ID内容可以受前 向纠错（ FEC , Forward Error Correction )编码的保护， 也可以不在 FEC编 码的范围内。
本发明提出的包含 PON-ID 内容的下行数据发送方法同样适用于以 GPON为基础的下一代 PON系统。
以上所述， 仅为本发明的较佳实施例而已， 并非用于限定本发明的保 护范围， 凡在本发明的精神和原则之内所作的任何修改、 等同替换和改进 等， 均应包含在本发明的保护范围之内。

Claims

权利要求书
1、 一种通路切换方法， 其特征在于， 包括：
当前工作光线路终端 OLT向光网络单元 ONU发送携带有该 OLT的身 份信息的下行数据；
ONU接收并解析所述下行数据， 获得当前工作 OLT的身份信息； 当 ONU检测到当前工作 OLT的身份信息发生变化时， ONU执行通路切换。
2、 根据权利要求 1 所述的通路切换方法， 其特征在于， 所述当 ONU 检测到当前工作 OLT的身份信息发生变化时， ONU执行通路切换包括： 所述 ONU检测到当前工作 OLT的身份信息发生变化时， 根据自身存 储的备用通路上的 OLT的身份信息和 ONU在备用通路上的工作参数的对 应关系， 将自身的工作参数配置为备用通路的工作参数后进入工作状态。
3、 根据权利要求 1所述的通路切换方法， 其特征在于， 所述当前工作 OLT向 ONU发送携带有该 OLT的身份信息的下行数据包括：
当主用通路作为工作通路时， 主用通路上的 OLT向 ONU发送携带有 该 OLT的身份信息的下行数据； 当主用通路无效后， 备用通路作为工作通 路， 该工作通路上的 OLT向 ONU发送携带有该 OLT的身份信息的下行数 据。
4、 根据权利要求 1所述的通路切换方法， 其特征在于， 所述 ONU在 处于以下状态时收到来自所述 OLT的身份信息： 待机状态； 或者， 从待机 状态转移到序列号状态， 并处于序列号状态； 或者， 从待机状态转移到序 列号状态， 然后从序列号状态转移到测距状态， 并处于测距状态。
5、 根据权利要求 2所述的通路切换方法， 其特征在于， ONU通过以 下方式存储备用通路上的 OLT的身份信息和 ONU在备用通路上的工作参 数的对应关系：
主用通路作为工作通路时， 备用通路上的 OLT将自身的身份信息发送 给主用通路上的 OLT, 并通过主用通路上的 OLT完成对所有 ONU在备用 通路上的工作参数的测量；
主用通路上的 OLT将接收到的备用通路上的 OLT的身份信息和测量得 到的 ONU在备用通路上的工作参数发送给相应的 ONU;
所述 ONU接收到主用通路上的 OLT发送的所述备用通路上的 OLT的 身份信息和 ONU在备用通路上的工作参数后，存储所述身份信息和所述工 作参数的对应关系。
6、 根据权利要求 2所述的通路切换方法， 其特征在于， ONU通过以 下方式存储备用通路上的 OLT的身份信息和 ONU在备用通路上的工作参 数的对应关系：
ONU存储备用通路上的 OLT的身份信息和 ONU在备用通路上的工作 参数， 及二者的对应关系为系统默认设置。
7、 根据权利要求 1至 6任一项所述的通路切换方法， 其特征在于， 所 述 OLT通过下述方式发送携带有所述 OLT的身份信息的下行数据：
将所述身份信息携带在下行帧中新增的一个域中， 所述新增的域位于 GPON的下行帧的下行物理控制块 PCBd域中， 或者， 位于 GPON的下行 帧的净荷的 GEM帧头中；
或者将所述身份信息携带在下行帧中的现有域中， 所述现有域为下行 物理层 OAM PLOAMd域 , 或净荷域。
8、 根据权利要求 1至 6任一项所述的通路切换方法， 其特征在于， 所 述 OLT的身份信息包括下述之一或任意组合： OLT所在的国家、 OLT所在 的城市、 OLT识别信息、 OLT的槽位识别信息、 OLT当前工作的端口识别 信息、 OLT的发射光功率信息； 或者，
与实际 OLT的身份信息存在预设对应关系的逻辑信息。
9、 一种通路切换系统， 其特征在于， 包括光线路终端 OLT及光网络单 元 ONU; 用通路作为工作通路时，工作通路上的 OLT用于向 ONU发送携带有该 OLT 的身份信息的下行数据；
所述 ONU,用于在主用通路正常通信时，存储备用通路上的 OLT的身 份信息和 ONU在备用通路上的工作参数的对应关系；还用于接收并解析所 述下行数据， 获得当前工作 OLT的身份信息； 以及用于在检测到当前工作 OLT 的身份信息发生变化时， 根据自身存储的所述对应关系将自身的工作 参数配置为备用通路的工作参数后进入工作状态。
10、 根据权利要求 9所述的通路切换系统， 其特征在于， 主用通路作 为工作通路时，
所述备用通路上的 OLT用于将自身的身份信息发送给所述主用通路上 的 OLT;
所述主用通路上的 OLT用于完成对所有 ONU在备用通路上的工作参 数的测量，并将接收到的备用通路上的 OLT的身份信息和测量得到的 ONU 在备用通路上的工作参数发送给相应的 ONU;
所述 ONU 用于接收到主用通路上的 OLT发送的所述备用通路上的 OLT的身份信息和 ONU在备用通路上的工作参数后存储所述身份信息和 所述工作参数的对应关系； 或者， 所述 ONU存储备用通路上的 OLT的身 份信息和 ONU在备用通路上的工作参数，及二者的对应关系为系统默认设 置。
11、 一种下行数据发送方法， 其特征在于， 包括：
当前工作光线路终端 OLT向光网络单元 ONU发送携带有该 OLT的身 份信息的下行数据；
ONU接收并解析所述下行数据，获得当前工作 OLT的身份信息并进行 显示。
12、 根据权利要求 11 所述的下行数据发送方法， 其特征在于， 所述 OLT通过下述方式发送携带有所述 OLT的身份信息的下行数据：
将所述身份信息携带在下行帧中新增的一个域中， 所述新增的域位于 GPON的下行帧的下行物理控制块 PCBd域中， 或者， 位于 GPON的下行 帧的净荷的 GEM帧头中；
或者将所述身份信息携带在下行帧中的现有域中， 所述现有域为下行 物理层 OAM PLOAMd域， 或净荷域。
13、 根据权利要求 11 所述的下行数据发送方法， 其特征在于， 所述 OLT的身份信息包括下述之一或任意组合： OLT所在的国家、 OLT所在的 城市、 OLT识别信息、 OLT的槽位识别信息、 OLT当前工作的端口识别信 息、 OLT的发射光功率信息； 或者，
与实际 OLT的身份信息存在预设对应关系的逻辑信息。
14、 根据权利要求 11 所述的下行数据发送方法， 其特征在于， 所述 ONU为带显示屏的手持终端。
15、 根据权利要求 11 所述的下行数据发送方法， 其特征在于， 所述 ONU通过网管显示所述 OLT的身份信息。
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