WO2011150739A1 - Method, system and node device for sharing and protecting in optical transport network - Google Patents

Abstract

The embodiments of the present invention relate to data communication technique, and especially relate to a method, system and node for sharing and protecting in an optical transport network (OTN). The method includes: among node devices forming a ring structure in the OTN, a node device, which detects a fault or receives fault information from an upstream node device, determines a protection state of the current node device (101); a connection state of the current node device is switched into a determined protection state (102); the fault information is transmitted to a downstream node device when the current node device is a non-service source node device (103). With the method, system and node provided in the embodiments of the present invention, the sharing and protection in the mesh network can be realized, and higher service reliability can be achieved.

Description

 Method, system and node device for sharing protection in OTN network

 The present invention relates to a shared protection technology in an Optical Transport Network (OTN), and more particularly to a method, system and node device for sharing protection in an OTN network. Background technique

 The Optical Transmission Hierarchy (OTH) technology is a new generation of standardized digital transmission architecture introduced after the Synchronous Digital Hierarchy (SDH). The optical transport network (OTN) based on 0TH can meet the requirements of data bandwidth development. From the perspective of the entire network, OTN includes optical CHC layer (OCH) and optical multiplex section (OMS, Optical Multiplexer Section). Layer and optical transport section layer (OTS), the signal sent by the client is first digitally encapsulated, then mapped to the OCH layer, then multiplexed to the OMS layer, then processed by the OTS layer, and finally transmitted over the optical cable. .

 The OCH layer is composed of three parts, including an optical transmission unit of level k (OTUk), an Optical Data Unit of level k (ODUk), and a k-th order optical payload unit (OPUk). , Optical Payload Unit of level k ). Where k is the level, and the current standardized level is 0, 1, 2, 3, 4. The OTN network schedules services, data, and the like based on the ODUk layer, and the ODUk connection scheduling is completed by the cross scheduling unit.

There are more and more applications of mesh topology in OTN networks. Traditional ring 1+1 protection and optical channel sharing protection are not applicable in mesh networks. Moreover, the ODUk-based ring type sharing protection in the prior art needs to rely on the optical monitoring channel to transmit ODUk shared protection signaling, so that not only the sharing protection of the working ring in the mesh network can be set, but also the protection function fails when the optical monitoring channel is disconnected. There is a problem of poor reliability. Summary of the invention

 The embodiments of the present invention provide a method, a system, and a node device for sharing protection in an OTN network, which can implement sharing protection in a mesh network and have high service reliability.

 An embodiment of the present invention provides a method for sharing protection in an OTN network, where the method includes:

In the node devices that form the ring structure in the OTN network, the node device that detects the failure or receives the fault information from the upstream node device determines the protection state of the node device; and switches the connection state of the node device to the determined protection state;

 The fault information is transmitted to the downstream node device when the node device is a non-service source node device.

 The detecting, by the node device that the fault is determined, the protection state of the node device, includes: the node device detecting the multiplex section layer, the channel layer, and the k-th order optical data unit layer between the previous node device and the node device After any layer or layer fails, determine the protection status of the node device.

 The detecting, by the local device, that the multiplex section layer is faulty, includes: detecting whether the optical power of the optical passing the multiplex section layer is smaller than a preset threshold, and determining that the fault is faulty if the threshold is less than the preset threshold. Otherwise, it is judged that no failure has occurred.

 The detecting, by the node device, the fault of the channel layer, includes: detecting whether the optical power of the light passing through the channel layer is less than a preset threshold, and if it is less than a preset threshold, determining that a fault occurs; otherwise, determining that the fault does not occur And detecting whether the service frame format of the service information passing through the channel layer includes an overhead byte indicating a fault, and if yes, determining that a fault has occurred; otherwise, determining that no fault has occurred.

When the node device detects that the k-th optical data unit layer is faulty, the method includes: detecting whether the optical power of the light passing through the k-th optical data unit layer is less than a preset threshold, and if it is less than a preset threshold, determining that A failure occurs, otherwise, it is determined that no failure has occurred; and/or whether the service frame format of the service information passing through the k-th optical data unit layer is detected to include The pin byte, if it exists, is judged to be a fault, otherwise, it is judged that no fault has occurred.

 The determining the protection status of the node device includes: determining, according to the service information preset by the node device, that the node device is an intermediate node device, determining that the protection state of the node device is a through state; determining that the node device is a service sink node When the device is determined, the protection status of the node is the bridge status. When the node device is the service source node, the protection status of the node is changed.

 The switching the connection state of the node device to the determined protection state includes: determining that the protection state of the node device is a through state, and having no switching operation; determining that the protection state of the node device is a bridge state, The connection state of the node device and the device of the previous node is switched to the protection state. When the protection state of the node device is the switching state, the connection state between the node device and the next node device is switched to the protection state.

 After the local node device switches to the protection state, the service information is transmitted by using the service frame format in the k-th optical data unit layer.

 The embodiment of the invention provides a node device in an OTN network, including:

 a detecting module, configured to detect a fault condition or a node device that receives the fault information from the upstream node device, determines a protection state of the node device;

 The control module is configured to switch the connection state of the node device to the determined protection state, and the transmission module is configured to transmit the fault information to the downstream node device when the node device is a non-service source node device.

 The detecting module is configured to detect whether a multiplex section layer, a channel layer, and a k-th order optical data unit layer between the node device and the previous node device are faulty.

When the detecting module determines that the node device is an intermediate node device, determining that the protection state of the local node device is a through state; determining that the node device is a service sink node device, determining that the protection state of the local node device is a bridge state When the device of the local node is a service source node device, it is determined that the protection state of the device of the node is a switching state. When the node device is a service sink node device, the control module switches the connection state between the node device and the previous node device to the protection state; when the node device is the service source node device, the control module connects the node. The connection state between the device and its next node device is switched to the protection state.

 An embodiment of the present invention provides a system for sharing protection in an OTN network, including: at least two node devices that form a ring structure;

 The node device detects that a fault occurs or the node device that receives the fault information from the upstream node device determines the protection state of the node device; switches the connection state of the node device to the determined protection state; the node device is a non-service source The node device transmits the fault information to the downstream node device.

The method, system, and node device for sharing protection in an OTN network provided by the embodiment of the present invention determine the protection state of the node device by the node device detecting the failure or the node device receiving the failure information from the upstream node device; The connection state is switched to the determined protection state; when the local device is a non-service source node device, the failure information is transmitted to the downstream node device. The method, system, and node device for sharing protection in the OTN network provided by the embodiment of the present invention detect the fault in a timely manner by detecting the multiplex section layer, the channel layer, and the ODUk layer between the node devices, and adopt the service source node device and A protection channel between service sink nodes enables service transmission to proceed normally. In the method provided by the embodiment of the present invention, when the mesh topology is configured, the node device can be arbitrarily selected to form a ring network, and the protection channel is established, and the protection channel in the prior art is not applicable to the ring network of any composition. Therefore, the method provided by the embodiment of the present invention can be applied not only to the ring topology network structure in the OTN network, but also to the mesh topology network structure, and has a wide application range. Moreover, the method provided by the embodiment of the present invention uses the service frame format in the k-th optical data unit layer to transmit service information in the protection channel composed of the multiplex section layer, the channel layer, and the ODUk, and has more information than using the optical monitoring channel. High reliability. DRAWINGS

 1 is a schematic flowchart of a method for sharing protection in an OTN network according to an embodiment of the present invention; FIG. 2 is a schematic diagram of a ring topology network according to another embodiment of the present invention;

 3 is a schematic flowchart of a method for sharing protection in an OTN network according to another embodiment of the present invention; FIG. 4 is a schematic structural diagram of a fault in a ring topology network according to another embodiment of the present invention; FIG. 5 is a schematic diagram of an OTN network according to an embodiment of the present invention; Schematic diagram of the node device in the middle. detailed description

 The main implementation principles, the specific implementation manners, and the corresponding beneficial effects that can be achieved by the technical solutions of the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

 The embodiment of the invention provides a method for sharing protection in an OTN network, which is mainly applied to an OTN network, and the network topology structure may be a ring topology network or a mesh topology network. If it is a mesh network, it can be abstracted into one or more ring networks. For convenience of description, the ring network is taken as an example. As shown in Figure 1, the method includes the following steps:

 Step 101: In each node device that forms a ring structure in the OTN network, the node device that detects the failure or receives the fault information from the upstream node device determines the protection state of the node device;

 Specifically, the transmission channel between the node devices includes a multiplex section layer, a channel layer, and an ODUk layer, and the node device detects the multiplex section layer, the channel layer, and the k-th order optical data between the previous node device and the node device. If any layer or layers in the cell layer fail, it can be judged that a failure has been detected.

 The device detecting that the multiplex section layer is faulty includes: detecting whether the optical power of the multiplexed segment layer is smaller than a preset threshold, and if it is less than the preset threshold, determining that the fault occurs; otherwise, determining In order to not fail;

The node device detects that the channel layer is faulty, and includes: detecting whether the optical power of the light passing through the channel layer is less than a preset threshold. If the threshold is less than the preset threshold, determining that the fault occurs, Then, it is determined that no fault has occurred; and/or whether the service frame format of the service information passing through the channel layer includes the overhead byte indicating the fault, and if it exists, it is determined that the fault has occurred, otherwise, it is determined that the fault has not occurred.

 If the node device detects that the k-th optical data unit layer is faulty, the method includes: detecting whether the optical power of the light passing through the k-th optical data unit layer is less than a preset threshold, and if it is less than the preset threshold, determining that a fault occurs, otherwise , determining that no failure has occurred; and/or detecting whether the service frame format of the service information passing through the k-th optical data unit layer includes an overhead byte indicating a failure, and if so, determining that a failure has occurred; otherwise, determining that the failure has not occurred malfunction.

 After detecting the fault or receiving the fault information from the upstream node device, the node determines that the node device is the intermediate node device according to the location information preset by the node device, and then determines that the protection state of the node device is the through state, When the node device is a service sink node device, it can be determined that the protection state of the node device is the bridge state, and the connection state between the node device and the previous node device is switched to the protection state. The location information is pre-set in each node device when the topology network is deployed.

 Step 102: Switch the connection state of the node device to a determined protection state.

 Specifically, when the downstream node device is determined to be an intermediate node device according to the preset location information, the protection state of the downstream node device is determined to be a through state, and the handover operation is not performed; when the downstream node device is determined to be a service sink node device, Determining the protection status of the downstream node device as a bridge state, and switching the connection state of the downstream node device to the previous node device to the protection state; determining a node device as the service source node device according to the preset location information, determining the node The protection state of the device is the switching state, and the connection state between the node device and the next node device is switched to the protection state, so that a protection channel is formed between the service source node device and the service sink node device, so that the service source node device will be in the service state. The information is transmitted to the sink node device in the protection channel according to the service frame format in the k-th optical data unit layer.

Step 103: Send the fault information to the downstream when the node device is a non-service source node device. Node device.

 From the above description, it can be seen that the method provided by the embodiment of the present invention detects a fault in a timely manner by detecting a multiplex section layer, a channel layer, and an ODUk layer between node devices, and passes the service source node device and service. The protection channel between the sink nodes enables the service transmission to proceed normally. In the method provided by the embodiment of the present invention, when the network structure is the mesh topology network structure, the node device can be arbitrarily selected to form a ring network, and the protection channel is established, and the protection channel in the prior art is not applicable to the ring network of any composition. Therefore, the method provided by the embodiment of the present invention can be applied not only to the ring topology network structure in the OTN network, but also to the mesh topology network structure, and has a wide application range. Moreover, the method provided by the embodiment of the present invention uses the service frame format in the k-th optical data unit layer to transmit service information in the protection channel composed of the multiplex section layer, the channel layer, and the ODUk, and has more information than using the optical monitoring channel. High reliability.

 The method for sharing protection in an OTN network provided by the present invention is described in detail below by using another embodiment. The ODUk channel with shared protection in the OTN network has two ODUk rings inside and outside, one ring for transmitting traffic and the other for ringing. Provide shared protection. As shown in Figure 2, the node devices A, B, C, D, E, and F in the OTN network form a ring topology network. When there is no fault, the ODUk inner ring forms two complete closed loops (as indicated by the dotted line). The protection channel of the outer ring working service can be switched to the inner ring protection channel when there is a fault in the outer ring working. Wherein, when the ring topology network is arranged, the node device A is set as the service source node device, the node device C is set as the service sink node device, and the remaining node devices are set as the intermediate node device, assuming that between the node device A and the node device B The transmission channel has failed. As shown in FIG. 3, when the method provided by the embodiment of the present invention is used, the following steps are included:

Step 301: The node device B performs fault detection, and generates fault information after detecting the fault; the node device B monitors whether the transmission channel between the node device B and the previous node device A is normal or periodically, and between the node devices. The transmission channel includes a multiplex section layer, a channel layer, and an ODUk layer. The local device B detects the relationship between the previous node device A and the local node device B. Any one or more of the multiplex section layer, the channel layer, and the k-th order optical data unit layer may be judged to be faulty.

 As shown in FIG. 4, each node device includes a first add/drop multiplex unit and a second add/drop multiplex unit, a first circuit board and a second circuit board, a first service access board, and a second service access board. a cross-scheduling unit; wherein: the first circuit board has a pair of line side ports for connecting to the first add/drop multiplexing unit; and the second circuit board has a pair of line side ports for multiplexing with the second add/drop The first circuit board and the second circuit board respectively have two pairs of ODUk ports, one pair is a working ODUk port, and the other pair is a protection ODUk port; the first service access board and the second service access board respectively have A pair of ODUk ports; the cross-scheduling unit has multiple pairs of ODUk ports, which are respectively connected to the ODUk ports of the circuit board and the service access board. The type of access service and number of interfaces on the client varies according to the type of service access board. The client service is encapsulated into the ODUk channel through the service access board in the uplink direction, and the cross scheduling unit is responsible for cross-connecting the ODUk channel to the ODUk port of the specific circuit board, and then transmitting the output from the line port of the circuit board to the add/drop multiplexing unit. Finally, it is transmitted in the fiber optic cable.

 Wherein, the multiplex section layer is interposed between the add/drop multiplex unit and the optical cable, the channel layer is between the circuit board and the add/drop multiplex unit, and the ODUk layer is between the cross scheduling unit and the circuit board. The detection point of the multiplex section layer is set to the line side input port of the add/drop multiplex unit; the detection point of the channel layer is set to the line side input port of the circuit board; the detection point of the ODUk layer is set to the working ODUk port of the circuit board and protection On the ODUk port.

 The device B of the node detects whether the multiplex layer is faulty, and the method includes: detecting whether the optical power of the multiplexed segment layer is smaller than a preset threshold, and if the threshold is less than the preset threshold, determining that the fault occurs, Otherwise, it is judged that no failure has occurred;

If the device B detects that the channel layer is faulty, the method includes: detecting whether the optical power of the light passing through the channel layer is less than a preset threshold; if the threshold is less than the preset threshold, determining that the fault occurs; otherwise, determining that the fault has not occurred; And/or detecting service frames of service information passing through the channel layer Whether the format includes a cost byte indicating a fault, and if it exists, it is determined that a fault has occurred. Otherwise, it is determined that no fault has occurred.

 If the device B detects that the ODUk layer is faulty, the method includes: detecting whether the optical power of the light passing through the ODUk layer is less than a preset threshold, and if it is less than the preset threshold, determining that the fault occurs; otherwise, determining that the fault has not occurred. And/or detecting whether the service frame format of the service information passing through the ODUk layer includes an overhead byte indicating a failure, and if so, determining that a failure has occurred, otherwise, determining that no failure has occurred. The overhead byte indicating the fault may be an APS (Automatic Protection Switching) / PCC (Protection Control Channel) byte, an Automatic Protection Switching/Protection Communication Channel (AIS) byte, and an open OCI (Open Connection Indication) byte, locked defect (LCK, Locked defect) byte, etc.

 Step 302: The node device B determines its own protection status.

 Specifically, after determining that the device is an intermediate node device according to the preset location information, the device B can determine that the protection state of the device B is the through state and does not perform the handover operation. The location information is set in each node device when the ring topology network is arranged.

 The controller of the node device may be used to determine the location of the node device and determine the protection state, and notify the cross scheduling unit to perform the handover operation. This cross-scheduling unit can also be referred to as an actuator.

 Step 303: The node device B transmits the fault information to the downstream node device C. The downstream node device is determined by the direction in which the service information is transmitted. For example, the service transmission direction is the node device A, the node device B, and the node device C. Device C is the downstream node device of node device B.

 Step 304: After receiving the fault information, the downstream node device C determines its own protection state and bridges the protection channel.

Specifically, the node device C extracts the received fault information, and determines according to the preset location information. After determining itself as the service sink node device, it can be determined that the protection state of the node device C is the bridge state, and the connection state between the node device C and the previous node device B is switched to the protection state, thus establishing a one-way transmission. aisle.

 The controller in the node device C determines that the protection state is the bridge state, and notifies the cross-scheduling unit to bridge the service information to the protection channel, that is, the cross-scheduling unit transmits the service information through the protection ODUk port of the line board.

 Step 305, the node device C continues to transmit the fault information to the downstream node device until the service source node device A;

 Specifically, after receiving the fault information sent by the node device C, the downstream node device D determines that it is an intermediate node device, and further determines that the protection state is a through state, and does not perform a handover operation. The operation of the downstream node device E and the downstream node device F is the same as that of the node device D.

 Step 306: After receiving the fault information, the service source node A determines its own protection state and switches to the protection channel.

Specifically, the node device A extracts the received fault information, and after determining that it is the service source node device according to the preset location information, it can determine that the protection state of the node device A is a switching state, and the node device A and its next node device are determined. The connection state between B switches to the protection state, thus establishing a bidirectional transmission channel on the protection ODUk ring. In a specific implementation, after determining that the protection state is the switching state, the controller in the node device A notifies the cross-scheduling unit to bridge the service information to the protection channel, that is, the cross-scheduling unit transmits the service information through the protection ODUk port of the circuit board. The ODUk channel with shared protection in the OTN network has two internal and external ODUk rings, one for transmitting traffic and the other for sharing protection. After receiving the handover command, the cross-scheduling unit of each node device changes the connection relationship between the service access version ODUk port and the working/protecting ODUk port on the circuit board, so that the service is switched to the corresponding path. In this way, a protection channel is formed between the service source node device and the service sink node device, so that the service source node device transmits the service information to the sink node in the protection channel according to the service frame format in the k-th optical data unit layer. Ready.

 It should be noted that, in FIG. 2, if the node device A is a service source node device, the node device D is a service sink node device, and a fault occurs between the node device B and the node device C, the fault information is transmitted through the node device C and the node. After the device 0, the node device £, and the node device F reach the node device A, the fault information may continue to be transmitted to the node device B or may not be transmitted to the node device B.

 The process of switching the foregoing node devices according to their own protection states may be summarized as: each node device obtains its own protection control state according to the shared protection switching protocol, and notifies each of the executors. The shared protection switching protocol is as follows: For the fault-associated node device (the service source node device and the service sink node device), if it is a service sink node device, the bridge is connected to the protection ODUk port, and if it is the service source node device, it is switched to Protect the ODUk port; other node devices remain in the pass-through state. The "bridge" means that the connection channel between the node device and the previous node device is switched to the protection channel; "switching" means that the connection channel between the node device and the next node device is switched to the protection channel.

 When the node device detects that the fault disappears, it can notify other node devices through the protection channel, and each node device switches back to the original working path after completing the protocol interaction.

 From the above description, it can be seen that the method provided by the embodiment of the present invention detects a fault in a timely manner by detecting a multiplex section layer, a channel layer, and an ODUk layer between node devices, and passes the service source node device and service. The protection channel between the sink nodes enables the service transmission to proceed normally. The method provided by the embodiment of the present invention can be applied to a ring topology structure and a mesh topology structure in an OTN network, and thus has a wide application range. Moreover, the method provided by the embodiment of the present invention uses the service frame format in the k-th optical data unit layer to transmit service information in the protection channel composed of the multiplex section layer, the channel layer, and the ODUk, and has more information than using the optical monitoring channel. High reliability. At the same time, in the topology of the mesh, the node devices can be arbitrarily selected to form a ring network, and the protection channel is established, and the protection channel in the prior art is not applicable to the ring network of any composition.

Correspondingly, the embodiment of the present invention further provides a node device in an OTN network, as shown in FIG. 5 . As shown, including:

 The detecting module 501 is configured to detect that a fault occurs or that the node device that receives the fault information from the upstream node device determines the protection state of the node device;

 The control module 502 is configured to switch the connection state of the node device to the determined protection state. The transmission module 503 is configured to transmit the fault information to the downstream node device when the node device is a non-service source node device.

 Preferably, in another embodiment provided by the present invention, the detecting module 501 is configured to detect a multiplex section layer, a channel layer, and a k-th order optical data unit layer between the node device and the previous node device.

 Preferably, in another embodiment provided by the present invention, when the detecting module 501 determines that the node device is an intermediate node device, determining that the protection state of the local node device is a through state; determining that the node device is a service sink node device And determining that the protection status of the local node device is a bridging state; determining that the local device is a service source node device, determining that the protection state of the local node device is a switching state.

 Preferably, in another embodiment provided by the present invention, when the node device is a service sink node device, the control module 502 switches the connection state between the node device and the previous node device to a protection state; the node device When the device is a service source node, the control module 502 switches the connection state between the node device and its next node device to the protection state.

 After the service source node and the service sink node in the topology network structure are switched to the protection state, the service frame format in the k-th optical data unit layer may be used to transmit the service information in the protection channel.

From the above description, it can be seen that the node device provided by the embodiment of the present invention detects the fault in time by detecting the multiplex section layer, the channel layer, and the ODUk layer between the node devices, and passes the service source node device and A protection channel between service sink nodes enables service transmission to proceed normally. In the method provided by the embodiment of the present invention, when the mesh topology is configured, the node device can be arbitrarily selected to form a ring network, and the protection channel is established, and the protection channel in the prior art is not applicable to the ring network of any composition. Therefore, the method provided by the embodiment of the present invention may not only It is used in the ring topology network structure in the OTN network, and can be applied to the mesh topology network structure, and has a wide application range. Moreover, the method provided by the embodiment of the present invention uses the service frame format in the k-th optical data unit layer to transmit service information in the protection channel composed of the multiplex section layer, the channel layer, and the ODUk, which is more than the optical monitoring channel. High reliability.

 Correspondingly, the embodiment of the present invention further provides a system for sharing protection in an OTN network, including: at least two devices that form a ring structure node;

 The node device detects that the fault occurs or the node device that receives the fault information from the upstream node device determines the protection state of the node device; switches the connection state of the node device to the determined protection state; and the node device is the non-service source node device The fault information is transmitted to the downstream node device.

 After the service source node and the service sink node in the system are switched to the protection state, the service frame format in the k-th optical data unit layer can be used to transmit the service information in the protection channel.

From the above description, it can be seen that the method, the system, and the node device according to the embodiments of the present invention detect faults in time by detecting the multiplex section layer, the channel layer, and the ODUk layer between the node devices, and A protection channel between the service source node device and the service sink node device enables the service transmission to proceed normally. In the method provided by the embodiment of the present invention, when the mesh topology is configured, the node device can be arbitrarily selected to form a ring network, and the protection channel is established, and the protection channel in the prior art is not applicable to the ring network of any composition. Therefore, the method provided by the embodiment of the present invention can be applied not only to the ring topology network structure in the OTN network, but also to the mesh topology network structure, and has a wide application range. Moreover, the method provided by the embodiment of the present invention uses the service frame format in the k-th optical data unit layer to transmit service information in the protection channel composed of the multiplex section layer, the channel layer, and the ODUk, and has more information than using the optical monitoring channel. High reliability. The spirit and scope of the invention. Thus, it is intended that the present invention covers such modifications and variations as the modifications and variations of the invention are within the scope of the appended claims and their equivalents.

.Zll7.0/llOZN3/X3d 6C.0Sl/ll0Z OAV

Claims

Claim  A method for sharing protection in an OTN network, the method includes: detecting, by a node device that fails or receiving fault information from an upstream node device, a protection state of the node device;  Switching the connection status of the node device to a determined protection state;  The fault information is transmitted to the downstream node device when the node device is a non-service source node device.  The method according to claim 1, wherein the detecting that the faulty node device determines the protection state of the node device includes:  After detecting that any one or more of the multiplex section layer, the channel layer, and the k-th order optical data unit layer between the previous node device and the local node device fails, the node device determines the protection state of the node device.  The method according to claim 2, wherein the local node device detects that the multiplex section layer is faulty, and includes:  When detecting that the optical power of the light passing through the multiplex section layer is less than a preset decision threshold, the multiplex section layer fails.  The method according to claim 2, wherein the detecting, by the node device, that the channel layer is faulty comprises:  Detecting that the channel layer fails when the optical power of the light passing through the channel layer is less than a predetermined decision threshold; and/or  When the service frame format of the service information passing through the channel layer is detected to include an overhead byte indicating a failure, the channel layer fails. The method according to claim 2, wherein the detecting, by the local node device, that the k-th optical data unit layer is faulty comprises: The optical data unit layer fails; and/or  When the service frame format of the service information passing through the k-th optical data unit layer is detected to include an overhead byte indicating a failure, the k-th order optical data unit layer fails.  The method according to claim 2, wherein the determining the protection status of the node device comprises:  When the node device is determined to be an intermediate node device according to the service information preset by the node device, the protection state of the node device is determined to be a through state. When the device at the node is determined to be a service sink node device, the protection state of the node device is determined to be a bridge. When the node device is the service source node device, the protection status of the node device is determined to be the switching state.  The method according to claim 6, wherein the switching the connection state of the node device to the determined protection state comprises:  When it is determined that the protection state of the node device is the through state, there is no handover operation; when determining that the protection state of the node device is the bridge state, the connection state between the node device and the previous node device is switched to the protection state;  When it is determined that the protection state of the node device is the switching state, the connection state of the node device and the next node device is switched to the protection state.  The method according to claim 7, wherein after the local node device switches to the protection state, the service information is transmitted by using a service frame format in the k-th optical data unit layer.  A node device in an OTN network, comprising:  a detecting module, configured to detect a fault condition or a node device that receives the fault information from the upstream node device, determines a protection state of the node device;  The control module is configured to switch the connection state of the node device to the determined protection state, and the transmission module is configured to transmit the fault information to the downstream node device when the node device is a non-service source node device. The node device according to claim 9, wherein the detecting module is used by The device detects whether the multiplex section layer, the channel layer, and the k-th order optical data unit layer between the node device and the previous node device are faulty.  The node device according to claim 9, wherein the detecting module determines that the node device is an intermediate node device, and determines that the protection state of the node device is a through state; The node device determines that the protection state of the node device is a bridge state. When the device of the node is a service source node device, determining that the protection state of the node device is a switching state.  The node device according to claim 9, wherein, when the local node device is a service sink node device, the control module switches the connection state between the node device and the previous node device to a protection state; When the node device is a service source node device, the control module switches the connection state between the node device and the next node device to the protection state.  A system for sharing protection in an OTN network, comprising: at least two devices constituting a ring structure node;  The node device detects that a fault occurs or the node device that receives the fault information from the upstream node device determines the protection state of the node device; switches the connection state of the node device to the determined protection state; the node device is a non-service source The node device transmits the fault information to the downstream node device.