CN102149027B

CN102149027B - Path switching method, system and downlink data transmission method

Info

Publication number: CN102149027B
Application number: CN201010112527.5A
Authority: CN
Inventors: 张伟良; 张德智; 耿丹
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2010-02-05
Filing date: 2010-02-05
Publication date: 2016-08-03
Anticipated expiration: 2030-02-05
Also published as: WO2011094990A1; CN102149027A

Abstract

The invention provides a kind of path switching method, system and downlink data transmission method, this path switching method includes: work at present optical line terminal OLT sends the downlink data of the identity information carrying this OLT to optical network unit ONU；ONU receives and parses through this downlink data, it is thus achieved that the identity information of work at present OLT；When the identity information that ONU detects work at present OLT changes, ONU execution path switches.ONU skips some registration existing and activates step, decreases OLT and the ONU time needed for the primary conversion being routed to stand-by channel, improves the communication efficiency between OLT and ONU.

Description

Channel switching method and system and downlink data sending method

Technical Field

The present invention relates to a passive optical network technology, and in particular, to a method and a system for switching a path in a passive optical network, and a method for transmitting downlink data.

Background

A Gigabit-capable passive optical network (GPON) technology is an important branch of the Passive Optical Network (PON) family, and similar to other PON technologies, a GPON technology is also a passive optical access technology that adopts a point-to-multipoint topology.

Fig. 1 is a schematic diagram of a topology structure of an existing GPON system, and as shown in fig. 1, a GPON is composed of an Optical Line Terminal (OLT) on a central office side, an Optical Network Unit (ONU) on a subscriber side, and an Optical Distribution Network (ODN), and generally adopts a point-to-multipoint network structure. The ODN is composed of single-mode optical fibers, optical splitters, optical connectors, and other passive optical devices, and provides an optical transmission medium for physical connection between the OLT and the ONUs.

In a GPON system, data transmission in a downlink direction (from an OLT to an ONU) adopts a broadcast mode, each ONU respectively receives all frames, and then acquires the frames belonging to the ONU according to an ONU identifier (ONU-ID), a GEM port identifier (GEM-Port ID) and a configuration identifier (Allocation-ID). For data transmission in the upstream direction (from ONU to OLT), each ONU should transmit upstream data in the time slot it has arranged for itself, since each ONU needs to share the transmission medium.

Fig. 2 is a schematic diagram of a downlink frame structure of a transmission convergence (GTC) layer of a GPON, and as shown in fig. 2, a downlink frame of the GPON is composed of a downlink physical control block (PCBd) and a payload, where the PCBd is composed of a physical synchronization field (Psync, physical synchronization), an idle field, a downlink physical layer operation, management and maintenance (PLOAMd, physical layer operation, administration and maintenance) field, a bit interleaved parity field (BIP, binary interleaved parity), an information payload length field (Plend, payload length stream), and an uplink bandwidth map field (USBWmap).

In the passive optical network deployment, if a worker installs an ONU in the PON system shown in fig. 1, in some scenarios, the distance between the OLT and the ONU may be far, which may reach several tens of kilometers. According to the current GPON protocol, a downlink frame sent by an OLT (as shown in fig. 2) does not include characteristic information of the OLT, but when a worker installs an ONU in a branch optical fiber access point, the worker needs to acquire OLT port information corresponding to the point to ensure that the ONU is installed in a correct PON system. If it is not ensured that an ONU is installed in the ODN to which the correct OLT belongs, it may result in that the installed ONU cannot operate normally.

In addition, in the deployment application of the passive optical network, some users need higher security, and it is desirable that an operator can provide a guarantee mechanism to ensure that a service path is not interrupted, or the next level of requirement is that the operator can quickly recover after the service path is interrupted. This puts requirements on protection paths and fast switching paths for passive optical networks that carry user traffic.

Fig. 3 is a schematic diagram of a typical network architecture in a protection mode in an existing passive optical network standard, and fig. 4 is a schematic diagram of another typical network architecture in a protection mode in an existing passive optical network standard.

Fig. 3 shows the manner in which the trunk optical fiber is protected in type B. As shown in fig. 3, two optical ports pollt (0) and pollt (1) of the OLT are each connected to a 2: N optical splitter, and the downstream direction of the optical splitter is connected to each ONU through an optical fiber (N are numbered from #1 to # N). Assume that the path through which the optical port pollt (0) of the OLT reaches the ONU via the optical splitter is the active path, and the path through which the optical port pollt (1) of the OLT reaches the ONU via the optical splitter is the standby path. And after the main path serving as the service path of the optical network unit and the optical line terminal is interrupted, starting the standby path serving as the service path of the optical network unit and the optical line terminal to maintain the communication between the optical network unit and the optical line terminal.

Fig. 4 shows a type C all-fiber protection scheme. As shown in fig. 4, the optical port pollt (0) of the OLT is connected to the 1: N optical splitter 1, the optical port pollt (1) of the OLT is connected to the 1: N optical splitter 2, and the two optical splitters are connected to the respective ONUs via optical fibers. Assume that the path through which the optical port pollt (0) of the OLT reaches the ONU through the optical splitter 1 is the active path, and the path through which the optical port pollt (1) of the OLT reaches the ONU through the optical splitter 2 is the standby path. And after the main path serving as the service path of the optical network unit and the optical line terminal is interrupted, starting the standby path serving as the service path of the optical network unit and the optical line terminal to maintain the communication between the optical network unit and the optical line terminal.

In the existing protection mode of the passive optical network shown in fig. 3 and 4, a process of enabling the standby path after the failure of the main path is taken as an example to describe a logic state transition process of the optical network unit in combination with fig. 5.

Fig. 5 is a schematic diagram of a logic state transition process of an optical network unit when a backup path is enabled after a failure of an existing primary path, and as shown in fig. 5, it is assumed that an ONU communicates with an OLT through a path of a primary path, i.e., a pon lt (0) port, and the ONU is in an operating state (O5); after the main path is interrupted, the method comprises the following steps:

the ONU cannot detect the optical signal of the OLT on the main channel, generates an out-of-synchronization (LOS/LOF) alarm and enters a popup state (O6), and the ONU enters an initial state (O1) after the time of the ONU in the popup state (O6) exceeds the time set by a TO2 timer;

the OLT starts a standby channel, namely a channel of a PONLT (1) port, synchronizes relevant protocol configuration parameters (such as transmitting optical power, ONUID, T-CONTID, GEMID and the like) of the standby channel, transmits a downlink optical signal to the ONU, and performs frame delimitation and synchronization with the ONU;

after the ONU detects the downlink optical signal of the OLT, the LOS/LOF alarm of the OLT is eliminated, and after finishing frame delimitation and synchronization with the OLT through a standby channel, the ONU is switched into a standby state (O2) from an initial state (O1);

the ONU is switched from a standby state (O2) to a serial number state (O3) after receiving the uplink overhead parameters sent by the OLT; the uplink overhead parameters include: a preamble bit type, a Delimiter parameter (Delimiter), an ONU transmit optical power level parameter indicating a level of ONU transmit optical power, and other parameters.

After the OLT is switched from the main channel to the standby channel, the IDs of the ONUs managed by the OLT need to be redistributed, and the redistributed IDs of the ONUs are sent to the ONUs; after receiving the ONU-ID information sent by the OLT, the ONU switches from the serial number state (O3) to the ranging state (O4);

after receiving an equalization delay (eqD) message sent by the OLT, the ONU is switched from a ranging state (O4) to an operating state (O5);

and at this moment, a standby channel between the ONU and the OLT is completely established, and the ONU and the OLT carry out information interaction through the standby channel.

In the process of switching the path shown in fig. 5, after the physical layer path is established on the standby path, the OLT needs to send EqD and other related data to all ONUs, each ONU needs to update its own parameters after receiving the related data, and complete the adjustment of the transmission power with the OLT optical port of the standby path, so that the normal operating state can be recovered finally. Taking the network structure of type B shown in fig. 3 as an example, when 32 ONUs are managed by one OLT, in the process of switching paths, the OLT needs to interact with the 32 ONUs and complete the state transition process shown in fig. 5 (i.e., go through O1, O2, O3, O4, and O5). It can be seen that the following problems exist in the conventional path switching process:

(1) each ONU completes the series of state transitions, so that the OLT needs to bear a large amount of message transmission work;

(2) in the processing process, because the capacity of the access between the OLT and the ONU is limited, in a GTC downlink frame, there is not enough capacity to store a Physical Layer Operation Administration and Maintenance (PLOAM) message to support 32 ONUs to complete the state migration process at the same time, so most ONUs need to wait for the message, the time for access switching is prolonged, the normal communication between the ONU and the OLT is affected, the time for the ONU and the OLT to resume normal operation is basically 100 milliseconds or more, and the requirement of a user on the quick recovery of a network fault cannot be met.

Disclosure of Invention

In view of the above, the main objective of the present invention is to provide a method and a system for switching a path in a passive optical network, which can shorten the time for switching the path and quickly recover the normal communication between an ONU and an OLT.

Another object of the present invention is to provide a method for sending downstream data in a passive optical network, which can ensure that an ONU is installed in an ODN to which a correct OLT belongs, and ensure that the ONU operates normally.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a path switching method, comprising:

the method comprises the steps that a current working optical line terminal OLT sends downlink data carrying identity information of the OLT to an optical network unit ONU;

the ONU receives and analyzes the downlink data to obtain the identity information of the current working OLT; and when the ONU detects that the identity information of the current working OLT changes, the ONU executes access switching.

When the ONU detects that the identity information of the current working OLT changes, the ONU executes access switching, and the access switching comprises the following steps:

and when the ONU detects that the identity information of the current working OLT changes, the working parameter of the ONU is configured into the working parameter of the standby access according to the corresponding relation between the identity information of the OLT on the standby access stored by the ONU and the working parameter of the ONU on the standby access, and then the ONU enters a working state.

The sending, by the currently operating OLT to the ONU, the downlink data carrying the identity information of the OLT includes:

when the main path is used as a working path, the OLT on the main path sends downlink data carrying the identity information of the OLT to the ONU; and when the main channel is invalid, the standby channel is used as a working channel, and the OLT on the standby channel sends downlink data carrying the identity information of the OLT to the ONU.

The ONU receives identity information from the OLT when the ONU is in the following state: a standby state; or, the state is transferred from the standby state to the serial number state and is in the serial number state; or, the mobile station moves from the standby state to the serial number state, then moves from the serial number state to the ranging state, and is in the ranging state.

The ONU stores the corresponding relation between the identity information of the OLT on the standby channel and the working parameters of the ONU on the standby channel in the following modes:

when the main channel is used as a working channel, the OLT on the standby channel sends the identity information of the OLT to the OLT on the main channel, and the OLT on the main channel finishes the measurement of the working parameters of all the ONUs on the standby channel;

the OLT on the main path sends the received identity information of the OLT on the standby path and the measured working parameters of the ONU on the standby path to the corresponding ONU;

and after receiving the identity information of the OLT on the standby access and the working parameters of the ONU on the standby access, which are sent by the OLT on the main access, the ONU stores the corresponding relation between the identity information and the working parameters.

the ONU stores the identity information of the OLT on the standby channel and the working parameters of the ONU on the standby channel, and the corresponding relation of the identity information and the working parameters is the default setting of the system.

The OLT sends downlink data carrying identity information of the OLT in the following way:

carrying the identity information in a newly added domain in a downlink frame, wherein the newly added domain is located in a PCBd domain of a downlink frame of the GPON, or is located in a GEM frame header of a payload of the downlink frame of the GPON;

or the identity information is carried in the existing domain in the downlink frame, wherein the existing domain is the OAMPLOAMd domain of the downlink physical layer or the payload domain.

The identity information of the OLT comprises one or any combination of the following: the state of the OLT, the city of the OLT, OLT identification information, slot position identification information of the OLT, port identification information of the OLT which works currently and transmitting optical power information of the OLT; or,

and the logic information has a preset corresponding relation with the identity information of the actual OLT.

A channel switching system comprises an Optical Line Terminal (OLT) and an Optical Network Unit (ONU);

the OLT comprises an OLT on a main channel and an OLT on a standby channel, and when the main channel or the standby channel is used as a working channel, the OLT on the working channel is used for sending downlink data carrying identity information of the OLT to the ONU;

the ONU is used for storing the corresponding relation between the identity information of the OLT on the standby access and the working parameters of the ONU on the standby access when the main access is in normal communication; the OLT is also used for receiving and analyzing the downlink data to obtain the identity information of the current working OLT; and the system is used for configuring the working parameters of the OLT into the working parameters of the standby access according to the corresponding relation stored in the OLT and then entering a working state when the identity information of the OLT is detected to be changed.

When the main path is used as the working path,

the OLT on the standby path is used for sending the identity information of the OLT to the OLT on the main path;

the OLT on the main access is used for completing the measurement of the working parameters of all the ONUs on the standby access and sending the received identity information of the OLT on the standby access and the measured working parameters of the ONUs on the standby access to the corresponding ONUs;

the ONU is used for storing the corresponding relation between the identity information and the working parameters after receiving the identity information of the OLT on the standby access and the working parameters of the ONU on the standby access, which are sent by the OLT on the main access; or the ONU stores the identity information of the OLT on the standby access, the working parameters of the ONU on the standby access and the corresponding relation of the identity information and the working parameters of the ONU on the standby access as default settings of the system.

A downlink data transmission method comprises the following steps:

and the ONU receives and analyzes the downlink data, acquires and displays the identity information of the current working OLT.

The ONU is a handheld terminal with a display screen.

And the ONU displays the identity information of the OLT through a network manager.

It can be seen from the above technical solutions that, by the method and system for implementing channel switching according to the present invention, after the main channel fails, the OLT and the ONU are quickly transferred to the standby channel, and the ONU skips the existing registration activation step, thereby reducing the time required for the OLT and the ONU to switch from the main channel to the standby channel and improving the communication efficiency between the OLT and the ONU. In the method for sending the downlink data, the OLT sends the downlink data carrying the identity information of the OLT to the ONU, and the ONU receives the downlink data and can analyze and identify the identity information of the OLT which works currently and display the identity information, so that the ONU is ensured to be installed in a correct PON, and the normal installation of the ONU is ensured.

Drawings

Fig. 1 is a schematic diagram of a topology structure of a conventional GPON system;

fig. 2 is a schematic diagram of a downlink frame structure of a GTC layer of a conventional GPON;

fig. 3 is a schematic diagram of a typical network architecture in a protection mode in a conventional passive optical network standard;

fig. 4 is a schematic diagram of another typical network architecture in a protection mode in the existing passive optical network standard;

fig. 5 is a schematic diagram illustrating a logic state transition process of an optical network unit when a standby path is enabled after a failure occurs in an existing primary path;

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 the path switch according to the present invention.

Detailed Description

The downlink data sending method comprises the following steps: the OLT sends downlink data carrying the identity information of the OLT to the ONU, and the ONU receives and analyzes the downlink data, obtains the identity information of the OLT currently working and displays the identity information. The identity information of the OLT can be carried in the following modes:

in the first mode, the identity information of the OLT is carried in a newly added domain in the downlink frame, where the newly added domain may be located in a PCBd domain of the GPON downlink frame or may be located in a GEM frame header of a payload of the GPON downlink frame. Taking as an example that a domain is added to the PCBd domain of the GPON downlink frame to carry the identity information of the OLT that sends the downlink frame, fig. 6 is a schematic diagram of a downlink frame structure of the GTC layer of the GPON of the present invention.

As shown in fig. 6, a PON-ID (PON-ID) field is included in the PCBd field of the downstream frame of the GPON, and the PON-ID field is located between the Psync field and the Ident field (fig. 6 only shows an example of the location of the PON-ID, and the PON-ID may be located in other locations of the PCBd field). The PON-ID domain is used to carry identity information (i.e. PON-ID information) of the OLT, and includes one or any combination of the following: country (Country) where the OLT is located, City (City) where the OLT is located, OLT identification information (OLT-ID), Slot identification information (Slot-ID) of the OLT, Port identification information (Port-ID) where the OLT is currently operating, and Power transmission Power information (Power) of the OLT. Certainly, the PON-ID field is used to carry the identity information of the OLT, and may also be logic information, that is, a code or a code having a preset correspondence with the actual information.

In this way, in a deployment application of the GPON, when an operator needs to install an ONU in a GPON system, the operator selects an access node of the GPON, and connects a device (for example, a handheld terminal with a display screen) capable of receiving a downstream frame of the GPON to the access node to receive the downstream frame, and the operator determines whether the currently used access node belongs to a PON to which the ONU is to be accessed according to information of a PON-ID field in the received downstream frame, thereby ensuring that the ONU is installed in a correct PON. Furthermore, after receiving the optical power information of the OLT in the PON-ID domain, the ONU compares the optical power information with the OLT optical power received by the ONU itself to calculate the PON system link loss.

In the second mode, the identity information of the OLT is carried in an existing domain in the downlink frame, such as a PLOAMd domain (or called PLOAM message) or a payload. Wherein,

the PLOAM message carrying the identity information of the OLT is referred to herein as a PON-ID message, the format of which is shown in table 1.

TABLE 1

As shown in table 1, the 1 st byte of the PON-ID message is the value of the ONU-ID, and the content of this byte is 11111111, indicating that the message is broadcasted to all ONUs; the content of the byte is 11111110, which indicates that the message is broadcasted to all the ONUs which are not registered to be activated; when the content of this byte is the value ONU-ID1 other than 11111111 and 11111110, this indicates that the message is sent to an ONU whose ONU-ID value is ONU-ID 1.

The 2 nd byte content of the PON-ID message indicates that the type of the PLOAM message is a PON identification information type.

The content of the 3 rd to 12 th bytes of the PON-ID message is the identity information of the OLT, and includes: the state of the OLT, the city of the OLT, the OLT-ID, the Slot-ID, the Port-ID and the transmitting optical power information of the OLT.

The OLT can send the broadcasted PON-ID message at a certain period; or after receiving a PON-ID request message sent by a certain ONU, the OLT sends the PON-ID message to the ONU sending the PON-ID request. The format of the PON-ID request message transmitted by the ONU is shown in table 2.

TABLE 2

As shown in table 2, the 1 st byte of the PON-ID request message is the value of the ONU-ID, indicating that the message is from an ONU having an ONU-ID value of ONU-ID 1.

The content of the 2 nd byte of the PON-ID request message indicates that the type of the PLOAM message is a PON-ID request type.

The identity information of the OLT can also be carried by a 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 (Messagetype) field, and a message content (Messagecontents) field. The message type field comprises a PON-ID message used for indicating that the message carries the identity information of the OLT, such as bit 1 to bit 5; the message content domain is used for carrying the identity information of the OLT, and comprises the following steps: the state of the OLT, the city of the OLT, the OLT-ID, the Slot-ID, the Port-ID and the transmitting optical power information of the OLT. The value of Port-ID in the GEM frame header of the GEM frame encapsulating the OMCI may be set to 11111111110, indicating that the type of the OMCI message encapsulated by the GEM frame is a PON-ID message.

The OLT can send an OMCI message with a message type of PON-ID at a certain period, and the ONU obtains the identity information of the OLT sending the message according to the message content domain of the OMCI message after receiving the OMCI message of the PON-ID type sent by the OLT.

In the second mode, after receiving the PON-ID message sent by the OLT, the ONU compares the received PON-ID message with the OLT optical power received by the ONU itself to calculate the PON system link loss.

In the PON protection structures of type B and type C in the prior art, a currently operating path is called an active path, and after the active path fails, the OLT (and the ONU) switches to a standby path. Fig. 7 is a flowchart of implementing the path switching according to the present invention, as shown in fig. 7, including the following steps:

step 700: when the main channel is used as a working channel for normal communication, the OLT on the main channel sends downlink data carrying self identity information to the ONU by adopting the first mode or the second mode, and the ONU receives and analyzes the downlink data to obtain the identity of the current working OLT; the ONU stores the corresponding relation between the PON-ID of the identity information of the OLT of the standby channel and the working parameters of the ONU in the standby channel.

This step generally comprises: when the main channel is used as a working channel, the OLT on the standby channel sends the identity information of the OLT to the OLT on the main channel, and the OLT on the standby channel finishes the measurement work of the working parameters of all the ONUs on the standby channel through the OLT on the main channel; the OLT on the main path sends the identity information of the OLT on the standby path and the working parameters of the ONUs on the standby path to all the ONUs through newly built PLOAM messages or GEM frames; after the ONU receives the information sent by the OLT on the main access, the ONU stores the corresponding relation between the identity information of the OLT on the standby access and the working parameters of the ONU on the standby access; or,

and the ONU stores the identity information of the OLT on the standby access and the working parameters of the ONU on the standby access, and the corresponding relation of the identity information and the working parameters of the ONU on the standby access is the default setting of the system. This step emphasizes that the ONU stores the correspondence between the PON-ID, which is the identity information of the OLT on the back-up path, and the operating parameters of the ONU on the back-up path, regardless of the method used.

The working parameters of the active path and the standby path stored by the ONU in this step include OLT identity information of the two paths, that is, PON-ID information, a preamble bit type, a Delimiter parameter (Delimiter), an ONU-transmitted optical power level parameter, an equalization delay (EqD, EqualizationDelay), and an ONUID allocated to the two OLTs. The PON-ID information comprises the country where the OLT is located, the city where the OLT is located, OLT identification information (OLT-ID), Slot identification information (Slot-ID) of the OLT, identification information (Port-ID) of a current working Port of the OLT and transmitting optical power information of the OLT, and the ONU identifies the identity of the OLT in a working state according to the PON-ID information sent by the OLT and configures the working parameters of the ONU according to the received PON-ID information of the OLT so as to establish communication with the working OLT.

Step 701: and when the main channel is invalid, the ONU and the OLT on the standby channel realize synchronization.

After a main channel for data communication between the ONU and the OLT is invalid, the ONU enters a popup state (O6) after generating an out-of-synchronization (LOS/LOF) alarm, and enters an initial state (O1) after the time that the ONU is in the popup state (O6) exceeds the time length of a preset TO2 timer. The OLT starts a standby channel to send a downlink frame, the ONU completes synchronization with the OLT, and the ONU enters an O2 state.

Step 702: the standby channel is used as a working channel, the OLT on the standby channel sends downlink data carrying self-identity information (PON-ID) to the ONU in a first mode or a second mode, and the ONU receives and analyzes the downlink data and obtains the identity of the current working OLT according to the PON-ID information in the downlink data. And when the ONU finds that the identity information of the OLT changes, the ONU configures the working parameters of the ONU into the working parameters of the standby access according to the corresponding relation between the OLT identity information on the standby access stored by the ONU and the working parameters of the ONU on the standby access and then enters a working state.

By the method for realizing the channel switching, the OLT and the ONU are quickly transferred to the standby channel after the main channel fails, and the ONU skips the existing registration activation step from the O2 state to the O5 state, so that the time required for the OLT and the ONU to switch from the main channel to the standby channel is reduced to the maximum extent, and the communication efficiency between the OLT and the ONU is improved to the maximum extent.

The specific implementation of step 702 may also be: the ONU transitions from the O2 state to the O3 state according to the existing method; and after receiving the downlink frame or the PON-ID message sent by the OLT in the first mode or the second mode, the ONU in the O3 state acquires the identity information of the current working OLT according to the PON-ID content carried in the downlink frame or the PON-ID message, and the ONU configures the working parameters of the ONU per se as the working parameters of the standby access according to the stored corresponding relation between the PON-ID of the standby access and the working parameters of the standby access and enters the working state. Therefore, after the main channel fails, the OLT and the ONU are quickly transferred to the standby channel, and the ONU skips the existing registration activation step from the O3 state to the O5 state, so that the time required for the OLT and the ONU to switch from the main channel to the standby channel is reduced, and the communication efficiency between the OLT and the ONU is improved.

The specific implementation of step 702 may also be: the ONU is transferred from the O2 state to the O3 state and then from the O3 state to the O4 state according to the existing method; and after receiving the downlink frame or the PON-ID message sent by the OLT in the first mode or the second mode, the ONU in the O4 state acquires the identity information of the current working OLT according to the PON-ID content carried in the downlink frame or the PON-ID message, and the ONU configures the working parameters of the ONU per se as the working parameters of the standby access according to the stored corresponding relation between the PON-ID of the standby access and the working parameters of the standby access and enters the working state. Therefore, after the main channel fails, the OLT and the ONU are quickly transferred to the standby channel, and the ONU skips the existing registration activation step from the O4 state to the O5 state, so that the time required for the OLT and the ONU to switch from the main channel to the standby channel is reduced, and the communication efficiency between the OLT and the ONU is improved.

Aiming at the path switching method described in fig. 7 of the present invention, there is also provided a path switching system, comprising an OLT and an ONU, wherein,

The ONU receives the PON-ID content sent by the OLT when the ONU is in an O2 state, an O3 state or an O4 state, acquires the identity information of the current working OLT, configures the working parameters of the ONU as the working parameters of the standby channel according to the stored corresponding relation between the PON-ID of the standby channel and the working parameters of the standby channel, and the ONU enters the working state.

when the main path is used as the working path, the OLT on the standby path is used for sending the identity information of the OLT to the OLT on the main path; the OLT on the main access is used for completing the measurement of the working parameters of all the ONUs on the standby access and sending the received identity information of the OLT on the standby access and the measured working parameters of the ONUs on the standby access to the corresponding ONUs; the ONU is used for storing the corresponding relation between the identity information and the working parameters after receiving the identity information of the OLT on the standby access and the working parameters of the ONU on the standby access, which are sent by the OLT on the main access;

or the ONU stores the identity information of the OLT on the standby channel and the working parameters of the ONU on the standby channel, and the corresponding relation of the identity information and the working parameters is the default setting of the system.

It should be noted that the PON-ID content sent in the downlink frame proposed by the present invention may be protected by Forward Error Correction (FEC) coding, or may not be in the range of FEC coding.

The downlink data transmission method containing PON-ID content provided by the invention is also suitable for a GPON-based next-generation PON system.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, and any modifications, equivalents, improvements, etc. that are within the spirit and principle of the present invention should be included in the present invention.

Claims

1. A method of path switching, comprising:

the ONU receives and analyzes the downlink data to obtain the identity information of the current working OLT, and the ONU stores the corresponding relation between the PON-ID of the identity information of the OLT of the standby access and the working parameters of the ONU in the standby access; the ONU compares the transmitting optical power information of the OLT received in the identity information of the current working OLT with the OLT optical power received by the ONU, and calculates the link loss of the PON system; when the ONU detects that the identity information of the current working OLT changes, the ONU configures the working parameters of the ONU into the working parameters of the standby access according to the corresponding relation between the identity information of the OLT on the standby access stored by the ONU and the working parameters of the ONU on the standby access and then enters a working state.

2. The method according to claim 1, wherein the sending, by the currently operating OLT, the downstream data carrying the identity information of the OLT to the ONU comprises:

3. The path switching method according to claim 1, wherein the ONU receives the identity information from the OLT when it is in the following states: a standby state; or, the state is transferred from the standby state to the serial number state and is in the serial number state; or, the mobile station moves from the standby state to the serial number state, then moves from the serial number state to the ranging state, and is in the ranging state.

4. The channel switching method according to claim 1, wherein the ONU stores the correspondence between the identity information of the OLT on the back-up channel and the operating parameters of the ONU on the back-up channel by:

5. The channel switching method according to claim 1, wherein the ONU stores the correspondence between the identity information of the OLT on the back-up channel and the operating parameters of the ONU on the back-up channel by:

6. The path switching method according to any of claims 1 to 5, wherein the OLT sends downstream data carrying identity information of the OLT by:

7. The path switching method according to any of claims 1 to 5, wherein the identity information of the OLT comprises one or any combination of the following: the state of the OLT, the city of the OLT, OLT identification information, slot position identification information of the OLT, port identification information of the OLT which works currently and transmitting optical power information of the OLT; or,

8. A channel switching system is characterized by comprising an optical line terminal OLT and an optical network unit ONU;

the ONU is used for storing the corresponding relation between the identity information of the OLT on the standby access and the working parameters of the ONU on the standby access when the main access is in normal communication; the OLT is also used for receiving and analyzing the downlink data to obtain the identity information of the current working OLT; the optical line terminal is also used for comparing the transmitting optical power information of the OLT received in the identity information of the current working OLT with the OLT optical power received by the optical line terminal to calculate the PON system link loss; and the system is used for configuring the working parameters of the OLT into the working parameters of the standby access according to the corresponding relation stored in the OLT and then entering a working state when the identity information of the OLT is detected to be changed.

9. The path switching system according to claim 8, wherein when the active path is used as the working path,

10. A method for transmitting downlink data, comprising:

the ONU receives and analyzes the downlink data, obtains the identity information of the current working OLT and displays the identity information; the ONU compares the transmitting optical power information of the OLT received in the identity information of the current working OLT with the OLT optical power received by the ONU, and calculates the link loss of the PON system; wherein,

the OLT sends downlink data carrying the identity information of the OLT to the ONU, and the downlink data comprises the following steps:

carrying the identity information in a newly added domain in a downlink frame, wherein the newly added domain is located in a PCBd domain of a downlink frame of the GPON, or is located in a GEM frame header of a payload of the downlink frame of the GPON; or the identity information is carried in the existing domain in the downlink frame, wherein the existing domain is the OAMPLOAMd domain of the downlink physical layer or the payload domain.

11. The method as claimed in claim 10, wherein the identity information of the OLT includes one or any combination of the following: the state of the OLT, the city of the OLT, OLT identification information, slot position identification information of the OLT, port identification information of the OLT which works currently and transmitting optical power information of the OLT; or,

12. The method for sending downstream data according to claim 10, wherein the ONU is a handheld terminal with a display screen.

13. The method for sending downstream data according to claim 10, wherein the ONU displays the identity information of the OLT through a network manager.