A method and system for multi-path switching network protection based on ROADM

Abstract

The application relates to a multi-path switching network protection method and system based on a ROADM, relates to the technical field of optical transmission networks in the communication industry, and comprises a plurality of ROADM sites, a network management system and an OTU module; the ROADM sites are divided into local sides and direction sides; the network management system is used for pre-configuring a main path of a service, at least one protection path and the priority of each path, configuring the parameters of a WSS module in each ROADM site, detecting a link fault alarm and triggering path switching. The application pre-sets a plurality of switching paths by manual operation or the network management and sets priorities, uses the WSS board card of the ROADM site to realize flexible scheduling of the service between different directions, does not need to depend on a complex control plane such as GMPLS and ASON, when detecting abnormalities such as fiber breakage, site power failure and board card failure, switches to the preset protection path according to the priority order, and establishes a new service optical channel by reconfiguring the WSS parameters.

Description

Technical Field

[0001] This application relates to the field of optical transmission network technology in the communications industry, and in particular to a multipath switching network protection method and system based on ROADM. Background Technology

[0002] As network scale and capacity continue to expand, the number of service connections carried is growing exponentially. To meet the ever-increasing traffic demands, DWDM (Dense Wavelength Division Multiplexing) technology has made continuous breakthroughs in transmission capacity and transmission distance, enabling optical transmission networks to gradually evolve from traditional ring and chain-type networks to more flexible mesh network structures.

[0003] However, the increasing complexity of network topology and service scale has significantly increased the difficulty of network management, network control, and service scheduling and maintenance. Traditional methods relying on manual planning and static configuration are no longer sufficient to meet the current network's requirements for flexibility, reliability, and rapid deployment. Against this backdrop, ROADM (Reconfigurable Optical Add / Drop Multiplexer) networks, with wavelength-level flexible scheduling and automated reconfiguration capabilities, have emerged. While improving network flexibility and resource utilization, ROADM also diversifies service paths, as services often have multiple reachable optical channels within the network. Currently, existing optical network protection technologies mainly employ the following two methods:

[0004] 1. Traditional OLP (Optical Line Protection) Architecture: In existing optical networks, traditional network protection is mainly implemented through OLP 1:1 or 1+1 architecture. Its advantages are simple implementation and low cost; its disadvantages are that it can only support two paths (primary / backup), cannot achieve multi-path protection, and protection switching is usually bound to physical ports, does not support the flexible scheduling capabilities of ROADM, and is difficult to adapt to the needs of complex mesh networking.

[0005] 2. WSON (Wavelength Switched Optical Network)-based Restoration Technology: End-to-end intelligent optical networks introduce a Gmpls-Ason control plane, combined with a dynamic path calculation algorithm, to recalculate and establish available optical transmission paths when a service fails, thus achieving service restoration. Its advantages include automatic routing, flexible paths, multi-hop capability, and suitability for complex networks; its disadvantages include the need for complex controller algorithms, topology databases, and real-time computing capabilities, requiring dedicated servers, resulting in high costs and making it unsuitable for low- to medium-dimensional ROADM sites and existing network upgrade scenarios. The core problem with existing technologies is that while existing ROADM sites possess characteristics such as colorless and directionless, they rely on complex control planes (such as Gmpls-Ason) to achieve flexible multi-path protection; if they do not rely on a control plane and only rely on the 1+1 protection of OLP, they lack multi-path protection capabilities. Summary of the Invention

[0006] To address the shortcomings of existing ROADM-based multipath switching network protection methods and systems, which are inherently flawed due to their design characteristics, and the fact that existing OLP structures cannot achieve multipath protection and WSON recovery technology relies on complex control planes and is costly, this application provides a ROADM-based multipath switching network protection method and system.

[0007] This application provides a multi-path switching network protection method system based on ROADM, which adopts the following technical solution: the system includes multiple ROADM sites, a network management system, and an OTU module.

[0008] The ROADM site, divided into a local side and a directional side, is the core carrier for service scheduling and path switching. The local side includes a first WSS module and a second WSS module. The first WSS module is used for adding and dropping service wavelengths, while the second WSS module is used for scheduling service wavelengths in different directions. The directional side has an N-dimensional structure with N directions. Each direction is equipped with a WSS board responsible for the ingress / egress switching and direction selection of wavelengths in that direction, enabling flexible forwarding of services between different directions.

[0009] By adopting the above scheme, the ROADM site is divided into a local side and a directional side, which can focus on the uplink / downlink processing and cross-directional scheduling functions of the service respectively, avoiding resource waste and scheduling chaos caused by overlapping module functions. The division of labor and cooperation between the first WSS module and the second WSS module not only ensures the accuracy of service wavelengths from local access or output to local, but also provides a basis for selecting multiple potential transmission paths for the service through the directional scheduling capability of the second WSS module; while the N-dimensional structure design on the directional side allows each direction to be independently configured with a WSS board, further enhancing the flexibility of wavelength switching between different directions and providing hardware-level support for the subsequent implementation of multi-path protection.

[0010] Furthermore, the OTU module is located at the source and destination sites and is used to convert electrical signals into optical signals. Its transmitting and receiving ports serve as the source and destination ports for the service, respectively, and are key components for service uplink and downlink.

[0011] By adopting the above scheme, the OTU module acts as a "photoelectric conversion hub" for service signals. At the source site, it converts the service electrical signals into optical signals that can be transmitted in the optical transmission network. At the destination site, it converts the received optical signals back into electrical signals, realizing end-to-end transmission of services. The clear source and destination roles of its transmitting and receiving ports provide a clear identifier for the network management system to identify the start and end points of services and accurately configure path parameters, ensuring that the signal transmission and reception logic remains consistent when services switch between the main path and the protection path.

[0012] Furthermore, the network management system, as the control core of the system, is used to pre-configure the main path of the service, at least one protection path and the priority of each path, configure the parameters of the WSS module in each ROADM site, including port number, service center frequency, channel bandwidth and optical power attenuation value, detect link fault alarms in real time, and trigger path switching when a fault occurs.

[0013] By adopting the above solution, the network management system achieves "full lifecycle management" of service paths: In the pre-configuration phase, technicians can plan the main path and multiple protection paths for each service based on network topology and service requirements, and set path priorities to ensure that the system can select the optimal backup path according to preset logic when a fault occurs; the unified configuration of WSS module parameters ensures the consistency of wavelength parameters for the same service in different paths, avoiding signal transmission anomalies caused by parameter mismatch; the real-time fault detection function can quickly detect anomalies such as fiber breakage, site power failure, and board failure, and automatically switch services from faulty paths to available protection paths by triggering path switching commands, significantly shortening service interruption time. In addition, the centralized control mode of the network management system does not rely on the complex Gmpls-Ason control plane, reducing system deployment and maintenance costs, and is more suitable for low- to medium-dimensional ROADM sites and existing network transformation scenarios.

[0014] Furthermore, the parameter configuration of the WSS module must meet the following requirements: each WSS module in the same service path is configured with the same service center frequency and channel bandwidth; the port number is set according to the physical connection relationship between the OTU module and the WSS module; and the optical power attenuation value is adjusted according to the optical power of each node in the link to ensure that the optical power of each service wavelength in the path remains consistent and to ensure the quality of service transmission.

[0015] Within the same service path, each WSS module uses the same service center frequency and channel bandwidth, which can avoid signal aliasing or transmission loss caused by differences in wavelength parameters and ensure service compatibility between nodes in the path. The port number is set according to the physical connection relationship between the OTU and the WSS, which can accurately match the access and output ports of the service signal and prevent service interruption caused by port mismatch. The dynamic adjustment of the optical power attenuation value can balance the optical power level of different nodes in the link, avoid nonlinear effects caused by excessive optical power or insufficient receiving sensitivity caused by excessively low optical power, thereby ensuring stable transmission quality of the service throughout the entire path.

[0016] Furthermore, the source and destination stations of the protection path are consistent with those of the main path, but the path stations are not exactly the same as those of the main path. This avoids the main path and the protection path failing simultaneously at the same fault point, thus improving the reliability of the protection.

[0017] For example, if the main path runs from source site A through sites B and C to destination site D, the protection path can be designed to run from A through sites E and F to D. The two paths have no overlapping segments on the physical link. When a fiber break occurs in segment BC of the main path, segment EF of the protection path remains unaffected, ensuring normal service transmission through the protection path. Furthermore, the selection of sites along the protection path can also consider network topology redundancy and link load, prioritizing paths with lower link load and higher node reliability to further improve the availability of the protection path.

[0018] Furthermore, to adapt to the needs of different scenarios, the first WSS module on the local side can be replaced with a multiplexer / demultiplexer (MUX / DEMUX) with a fixed channel interval to realize the multiplexing and demultiplexing function of service wavelengths, thereby reducing the deployment cost in some scenarios.

[0019] By adopting the above technical solution, in scenarios where only fixed wavelength multiplexing and demultiplexing are required and scheduling flexibility is low, such as small-to-medium-sized campus optical transmission networks or leased line services with relatively fixed service wavelength configurations, replacing the first WSS module with a multiplexer / demultiplexer can reduce the number of WSS modules used while meeting basic multiplexing / demultiplexing requirements, thereby reducing hardware procurement and maintenance costs. The multiplexer / demultiplexer has fixed channel spacing and wavelength filtering characteristics, enabling stable multiplexing and demultiplexing of preset wavelengths. Its simple operation and high reliability make it more suitable for scenarios with lower technical complexity requirements. Simultaneously, the combination of the multiplexer / demultiplexer and the second WSS module retains flexible scheduling capabilities on the directional side, ensuring the forwarding needs of services in different directions while balancing cost and functionality according to scenario characteristics, thus improving system applicability.

[0020] A multi-path switching network protection method based on ROADM, which is implemented based on the above system, specifically includes the following steps:

[0021] S1: Establish the main business path

[0022] The network management system selects the source, transit, and destination sites for the service, and configures the WSS parameters within each ROADM site along the route from the source port to the destination port to establish the main service path. Specifically, the service signal is converted from electrical to optical via the OTU module and transmitted to the uplink / downlink ports of the first WSS module. The network management system configures the parameters of the first WSS module, enabling the multiplexing of different service wavelengths. The combined wavelengths are then output through the common port of the first WSS module to the common port of the second WSS module. The uplink / downlink ports of the second WSS module are connected to the uplink / downlink ports of WSS modules in each direction. By configuring the parameters of the second WSS module, the service wavelength is scheduled to the WSS module on the direction corresponding to the target direction, thereby enabling the service to be forwarded in the specified direction and completing the establishment of the main path.

[0023] S2: Establish at least one protection path

[0024] Select the primary path to be protected and associate it with the primary path. The source and destination sites should be consistent with the primary path. Select a new path site (the new path site should not be exactly the same as the path site of the primary path to avoid the simultaneous failure of the primary and backup paths due to the same fault point). Pre-configure the WSS parameters of each path the service takes from the source port to the destination port to establish a service protection path. The WSS parameter configuration for the protection path only requires pre-configuring the WSS port number and optical power attenuation value, which are different from those of the primary path. The remaining parameters (service center frequency, channel bandwidth) should be consistent with the primary path to enable wavelength-level directional scheduling of the service during switchover. If multiple protection paths need to be established, repeat step S2 to form a multi-level protection architecture.

[0025] S3: Configuration Failover Logic

[0026] When a protection path is established, the switching trigger conditions, switching modes, and switching actions are configured through the network management system. The purpose is to enable path switching when a link failure alarm occurs. The switching trigger condition is typically a Los / LoF alarm from the OTU module. When an anomaly occurs in the link, such as fiber breakage, site power failure, or board failure, the OTU module detects the optical signal anomaly and reports an alarm. The switching modes are typically manual and automatic. Manual switching involves manually triggering the path change, while automatic switching involves the system automatically performing the path change after an alarm is detected. The switching action involves switching from the current path to the next higher priority protection path. The system deletes the WSS parameters of the current path based on the pre-configured parameters of the protection path and then automatically configures each WSS in the protection path to establish a new service optical channel.

[0027] S4: Fault Detection and Path Switching

[0028] When a failure occurs on the current service path, the system triggers the corresponding service to perform a failover according to a preset priority based on the source and destination port identifiers carried in the alarm information. After the WSS reconfiguration is completed, the service resumes transmission on the new path, achieving rapid service recovery and effectively avoiding service interruption.

[0029] By adopting the above technical solution, the system first monitors the status of the optical signal in real time through the OTU module. Once an alarm such as Los (loss of optical signal) or LoF (loss of frame) is detected, the alarm information carrying the source and destination port identifiers is immediately sent to the network management system. The network management system, according to the preset failover logic, locates the corresponding faulty service and its pre-configured protection path priority list. Subsequently, the system automatically executes the failover action: First, it deletes the parameter configuration of the WSS module in each ROADM site in the current faulty path, cutting off the optical signal transmission of the faulty path; Second, it calls the pre-configured protection path parameters according to priority order, sequentially issuing parameters to the second WSS module and the directional WSS module in all ROADM sites traversed by the protection path. For example, it switches the scheduling port of the second WSS module from the directional WSS board corresponding to the main path to the directional WSS board corresponding to the protection path, while adjusting the optical power attenuation value to match the link loss of the protection path. The entire failover process does not rely on complex dynamic path calculations; it only completes the rapid reconfiguration of the WSS module by calling the pre-configured parameters.

[0030] In summary, this application includes the following beneficial technical effects:

[0031] 1. No need to rely on complex control planes: The multi-path switching process of this invention does not rely on complex control planes such as Gmpls and Ason. It does not require maintaining a full network topology database or performing real-time path calculations. The switching decision is based on preset path relationships and priorities, which reduces system complexity and deployment costs. It is suitable for low- to medium-dimensional ROADM sites and existing network transformation scenarios, and solves the problem of high costs caused by reliance on control planes in existing technologies.

[0032] 2. Achieve flexible protection across multiple paths: Unlike the limitation of OLP structures that can only support two primary and backup paths, this invention can pre-configure multiple protection paths to form a multi-level switching architecture of primary path → first protection path → second protection path, achieving more than 1+1 protection capabilities and significantly improving the network's fault tolerance and reliability.

[0033] 3. This invention can utilize the existing capabilities of existing ROADM sites without large-scale hardware modifications. The local WSS module can be replaced with a multiplexer / demultiplexer (MUX / DEMUX) to adapt to the deployment requirements of different scenarios, reducing the cost and difficulty of existing network modifications. Attached Figure Description

[0034] Figure 1 A 4D ROADM site diagram shows the local and directional components of a ROADM site and the connection relationships between its parts.

[0035] Figure 2 The flowchart for creating the main business path illustrates the steps involved in establishing the main business path.

[0036] Figure 3 The main service path flow diagram shows the transmission path of the service in the main path.

[0037] Figure 4 The flowchart for creating a protection path illustrates the steps involved in establishing one.

[0038] Figure 5 The diagram showing the main business path and multiple protection paths illustrates the relationship between the main path and multiple protection paths.

[0039] Figure 6 The flowchart illustrates the steps involved in path switching after a failure occurs.

[0040] Figure 7 A diagram illustrating how services switch to protection path 1 when the main path fails.

[0041] Figure 8 A diagram illustrating the switch to protection path 2 when protection path 1 fails.

[0042] Figure 9The diagram shows the common port and up-and-down port of the WSS module, illustrating its port structure.

[0043] Figure 10 The alternative flowchart illustrates how the WSS used for multiplexing and demultiplexing in the local terminal of a ROADM site can be replaced with a fixed-channel-interval multiplexer / demultiplexer (MUX / DEMUX). Detailed Implementation

[0044] The present application will be further described in detail below with reference to the accompanying drawings.

[0045] This application discloses a multipath switching network protection method and system based on ROADM.

[0046] Example 1: A ROADM-based multipath switching network protection system

[0047] This embodiment provides a multi-path switching network protection system based on ROADM, suitable for 4D Mesh optical transmission networks, with the following specific structure:

[0048] The system comprises five 4D ROADM sites (SITE A, SITE B, SITE C, SITE D, and SITE E), one network management system, and multiple OTU modules. Each ROADM site is divided into a local side and a directional side. The local side includes a first WSS module and a second WSS module. The first WSS module is used for adding and dropping service wavelengths, and the second WSS module is used for scheduling service wavelengths in four directions. Each of the four directional sides is equipped with a WSS board, responsible for the ingress / egress switching and direction selection of wavelengths in the corresponding direction. The local and directional sides of the ROADM site are configured as follows: Figure 1 As shown.

[0049] The OTU modules are located at SITE A (source site) and SITE E (destination site). The OTU module's transmitting port at SITE A serves as the source port, and the OTU module's receiving port at SITE E serves as the destination port. These modules are used to convert electrical signals into optical signals to enable the uplink and downlink of services.

[0050] like Figure 2As shown, the network management system adopts an existing mature optical network management platform, which has functions such as path configuration, parameter distribution, fault detection, and switchover triggering. It is used to pre-configure the main path of the service, two protection paths, and the priority of each path (the main path has the highest priority, followed by protection path 1, and protection path 2 has the lowest priority). It configures the parameters of the WSS module in each ROADM site. The specific parameters are as follows: the service center frequency is set to 191312.5 GHz, the channel bandwidth is set to 75 GHz, the optical power attenuation value is set to 10 dB, and the port number is set according to the physical connection relationship between the OTU module and the WSS module (e.g., the first WSS module port of SITE A is set to WSS-1-5-Ad3, and the WSS board port on the directional side is set to WSS-1-3-Ad4).

[0051] In this embodiment, the source site (SITE A) and destination site (SITE E) of protection path 1 are the same as those of the main path, and the route site is SITE A→SITE C→SITE D→SITE E, which is not exactly the same as the route site of the main path (SITE A→SITE B→SITED→SITE E); the route site of protection path 2 is SITE A→SITE C→SITE B→SITE E, which further avoids overlap with the fault points of the main path and protection path 1.

[0052] Example 2: A ROADM-based multipath switching network protection method

[0053] This embodiment, based on the system of Embodiment 1, provides a multi-path switching network protection method based on ROADM, with the following specific steps:

[0054] Step 1: Establish the main business path

[0055] The network management system selects SITE A as the source site, SITE E as the destination site, and SITE B and SITE D as the transit sites. Parameters for the WSS modules in each ROADM site are configured (service center frequency 191312.5 GHz, channel bandwidth 75 GHz, optical power attenuation 10 dB, port numbers set according to physical connection relationships). The service signal is converted from electrical to optical by the OTU module at SITE A and transmitted to the up-and-down port of the first WSS module. The first WSS module parameters are configured through the network management system, causing the service wavelength to be multiplexed and output through the common port of the first WSS module to the common port of the second WSS module. The second WSS module schedules the service wavelength to the WSS board pointing towards SITE B, and it is sequentially forwarded by the WSS modules at SITE B and SITE D, finally reaching the OTU module at SITE E, completing the establishment of the main path. The service flow is as follows: Figure 3 As shown.

[0056] Step 2: Establish 2 protection paths

[0057] Establish Protection Path 1: Select the main path for association. Keep the source site SITE A and destination site SITE E unchanged. Select SITE C and SITE D as the transit sites. Pre-configure the parameters of the WSS modules in each ROADM site. The WSS port number is different from that of the main path (e.g., the port of the second WSS module in SITE A is set to WSS-1-5-Ad5). The service center frequency and channel bandwidth are the same as those of the main path. The optical power attenuation value is adjusted to 10dB according to the link optical power. Set the priority of Protection Path 1 to be lower than that of the main path.

[0058] Establish Protection Path 2: Repeat the above process, selecting SITE C and SITE B as the transit sites. Pre-configure WSS parameters (the port number is different from both the main path and Protection Path 1). Set the priority of Protection Path 2 to be lower than that of Protection Path 1. Multiple paths are displayed as follows: Figure 5 As shown.

[0059] Step 3: Configure switchover logic

[0060] Configure the switching trigger condition through the network management system to the Los / LoF alarm of the OTU module, set the switching mode to automatic switching, and the switching action is as follows: when an alarm is detected, delete the WSS parameter of the current path, automatically configure the WSS parameter of the next priority protection path, and establish a new service optical channel.

[0061] Step 4: Fault Detection and Path Switching

[0062] When a fiber break occurs between SITE B and SITE D in the main path, the OTU module of SITE D detects a Loss alarm and reports it to the network management system. Based on the source and destination port identifiers in the alarm information, the system triggers a service switchover from the main path to protection path 1 according to priority. The WSS parameters of the main path are deleted, and the WSS parameters of protection path 1 are configured. The service is then transmitted via SITE A → SITE C → SITE D → SITE E, achieving service recovery. The switchover process is as follows: Figure 6 , Figure 7 As shown.

[0063] If a board failure occurs between SITE C and SITE D in protection path 1, the system will detect the alarm and trigger a service switchover from protection path 1 to protection path 2. After WSS parameter reconfiguration, the service will be transmitted via SITE A → SITE C → SITE B → SITE E to ensure uninterrupted service. The switchover process is as follows: Figure 8 As shown.

[0064] Example 3: Alternative Solution

[0065] This embodiment provides an alternative to the above system, replacing the first WSS module on the local side of the ROADM site with a fixed-channel-interval multiplexer / demultiplexer (MUX / DEMUX) to implement the multiplexing / demultiplexing function for the service wavelength. The structure, function, and connection relationship of the remaining components are consistent with Embodiment 1. This alternative can reduce deployment costs and is suitable for scenarios with fixed service wavelengths and low requirements for scheduling flexibility. Its site structure is shown in the appendix of the alternative. Figure 10 As shown.

[0066] Working principle

[0067] The working principle of this invention is based on the wavelength-level flexible scheduling capability of ROADM. Through pre-configured multi-path and priority mechanisms, it realizes service switching and network protection, as detailed below:

[0068] I. Normal working status

[0069] Under normal operating conditions, the OTU module at the source site converts the electrical signal into an optical signal of a specific wavelength and transmits it to the up-and-down wavelength port of the first WSS module. The first WSS module, acting as the up-and-down wavelength unit, combines different service wavelengths through its common port and outputs the combined signal to the common port of the second WSS module. The second WSS module, acting as the direction scheduling unit, schedules the combined optical signal to the direction-side WSS board corresponding to the target direction according to the preset configuration of the main service path, and transmits it via fiber optic link to the next ROADM site. Each path site sequentially completes wavelength pass-through or switching of the optical signal, finally transmitting it to the second WSS module at the destination site. After being split by the first WSS module, it is received by the OTU module, completing the conversion from optical signal to electrical signal and realizing the complete transmission of the service.

[0070] II. Protection Path Pre-configuration

[0071] This invention pre-configures multiple protection paths in addition to the primary path through a network management system. The source and destination sites of the protection paths are consistent with the primary path, but the transit sites are not exactly the same as the primary path, to avoid simultaneous failure of the primary and backup paths due to the same fault point. The WSS parameters of each protection path only need to be pre-configured with port numbers and optical power attenuation values ​​different from the primary path; core parameters such as service center frequency and channel bandwidth remain consistent with the primary path, ensuring the consistency and continuity of service wavelengths after switching. Simultaneously, the network management system sets clear priorities for each protection path (e.g., primary path > protection path 1 > protection path 2), forming a multi-level switching architecture.

[0072] III. Fault Detection and Switchover Mechanism

[0073] The failover mechanism of this invention is based on real-time alarm detection of the OTU module. When a fiber breakage, site power failure, or board failure occurs, the OTU module of the affected site detects optical signal loss or frame loss anomalies, immediately generates a Los / LoF alarm, and reports it to the network management system. The network management system quickly locates the affected service and its current path based on the source and destination port identifiers carried in the alarm information, and triggers failover actions according to a preset priority order.

[0074] The failover process specifically includes: the network management system issuing commands to each ROADM site involved in the current path to delete the corresponding WSS parameter configuration; subsequently, based on the pre-configured parameters of the next priority protection path, automatically reconfiguring each WSS module in the protection path, including directional port switching and optical power adjustment. After the WSS parameter reconfiguration is completed, the service re-establishes the optical channel on the new protection path, achieving rapid service recovery.

[0075] IV. Multi-level failover architecture

[0076] When multiple protection paths need to be established, this invention adopts a multi-level switching architecture: main path → first protection path → second protection path. If the main path fails and the system switches to the first protection path, and that protection path fails again, the network management system will trigger the service to switch from the first protection path to the second protection path, and so on, until an available path is found or all priority paths have been attempted. This multi-level switching architecture achieves more than 1+1 protection capability, significantly improving the network's fault tolerance.

[0077] V. Functions of Core Components

[0078] WSS module: Implements wavelength-level optical signal scheduling and selection, supports colorless and directionless features, and is the core execution component for multipath switching.

[0079] OTU module: Enables mutual conversion between electrical and optical signals, and provides fault detection basis for switching through Los / Lof alarms.

[0080] Network management system: As the control core, it is responsible for path pre-configuration, parameter distribution, fault detection, priority determination and switchover command execution, replacing the functions of the complex control plane.

[0081] Through the above mechanism, this application utilizes a combination of pre-configured paths and WSS parameter reconfiguration to enable service switching between multiple paths at the optical layer, providing multi-level protection capabilities for optical transmission networks.

[0082] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A multi-path switching network protection system based on ROADM, comprising multiple ROADM sites, a network management system, and an OTU module, characterized in that: The ROADM site is divided into local side and directional side; The local side includes a first WSS module and a second WSS module. The first WSS module is used to implement the up-and-down switching of service wavelengths, and the second WSS module is used to implement the scheduling of service wavelengths in different directions. The directional side has an N-dimensional structure with N directions. Each direction is equipped with a WSS board, which is responsible for the input / output conversion and direction selection of wavelength in that direction. The OTU module is located at the source site and the destination site and is used to convert electrical signals into optical signals. Its transmitting port and receiving port serve as the source port and the destination port of the service, respectively. The network management system is used to pre-configure the main path of the service, at least one protection path and the priority of each path, configure the parameters of the WSS module in each ROADM site, detect link failure alarms and trigger path switching.

2. The multi-path switching network protection system based on ROADM according to claim 1, characterized in that: The parameters of the WSS module include port number, service center frequency, channel bandwidth, and optical power attenuation value. Each WSS module in the same service path is configured with the same service center frequency and channel bandwidth. The port number is set according to the physical connection relationship between the OTU module and the WSS module. The optical power attenuation value is adjusted according to the optical power of each node in the link to keep the optical power of each service wavelength in the path consistent.

3. A multi-path switching network protection system based on ROADM according to claim 2, characterized in that: The source and destination stations of the protection path are the same as those of the main path, but the path stations are not exactly the same as those of the main path, so as to avoid the main path and the protection path failing at the same fault point at the same time.

4. A multi-path switching network protection system based on ROADM according to claim 3, characterized in that: The first WSS module on the local side can be replaced with a multiplexer / demultiplexer with a fixed channel spacing to implement the multiplexing / demultiplexing function of the service wavelength.

5. A ROADM-based multipath switching network protection method, employing the ROADM-based multipath switching network protection system described in any one of claims 1-4, characterized in that: Includes the following steps: S1: Establish the main service path. Select the source site, transit site, and destination site of the service through the network management system, configure the parameters of the WSS module in each ROADM site, and complete the establishment of the main path. S2: Establish at least one protection path, select the protection path associated with the main path, keep the source site, destination site consistent with the main path, select a new path site, pre-configure the parameters of the WSS module in each ROADM site, and set the priority of each protection path. S3: Configure the switching logic, set the switching trigger conditions, switching mode and switching action; S4: Fault detection and path switching. When a link fault alarm is detected, the service is switched from the current path to the next available path according to the preset priority. A new service optical channel is established by reconfiguring the WSS module parameters to realize service recovery.

6. A multi-path switching network protection method based on ROADM according to claim 5, characterized in that: The establishment process of the main path described in S1 is as follows: the service converts the electrical signal into an optical signal through the OTU module and sends it to the up-and-down port of the first WSS module. The parameters of the first WSS module are configured through the network management system so that the wavelengths of different services are combined and output to the common port of the second WSS module through the common port of the first WSS module. Then, by configuring the parameters of the second WSS module, the service wavelength is scheduled to the WSS module on the direction side corresponding to the target direction to realize service forwarding.

7. A multi-path switching network protection method based on ROADM according to claim 6, characterized in that: The WSS parameter configuration for the protection path described in S2 only requires pre-configuring a WSS port number and optical power attenuation value that are different from those of the main path. The remaining parameters are consistent with those of the main path, which is used to realize the directional scheduling of service wavelengths at the wavelength level.

8. A multi-path switching network protection method based on ROADM according to claim 7, characterized in that: The switching trigger condition described in S3 is the Los / Lof alarm of the OTU module. The switching modes include manual switching and automatic switching. The switching action is to delete the WSS parameter of the current path and configure the WSS parameter of the protected path to establish a new service optical channel.

9. A multi-path switching network protection method based on ROADM according to claim 8, characterized in that: The link faults mentioned in S4 include three types of anomalies: fiber breakage, site power failure, and board failure. The system triggers the corresponding services to perform a switchover according to the preset priority based on the source and destination port identifiers carried in the alarm information.

10. A multi-path switching network protection method based on ROADM according to claim 9, characterized in that: When multiple protection paths need to be established, repeat S2~S3 to form a multi-level switching architecture of main path → first protection path → second protection path.

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