A method for fast perception of satellite constellation network topology status

Abstract

This invention provides a method for rapid perception of the topology status of a satellite constellation network. It deploys a multi-dimensional physical layer monitoring module, a dynamic adaptive BFD detection mechanism, the OSPF routing protocol, and a shared data exchange area between the BFD driver and the OSPF process on each satellite node. This invention utilizes physical layer signal status monitoring technology and the rapid link status detection capability of the BFD protocol to monitor the connectivity of inter-satellite links in real time. Upon detecting a fault, it immediately notifies relevant nodes via control messages. Simultaneously, it links the BFD detection results with the OSPF routing protocol, triggering immediate route recalculation, thereby shortening route convergence time. This invention constructs a cross-layer closed-loop linkage system, dynamically adjusting protocol layer detection parameters through physical layer perception data, and combining hardware acceleration to optimize the entire fault detection process. This not only accelerates fault detection and recovery but also improves the resource utilization efficiency and overall transmission efficiency of the inter-satellite network, ensuring high network reliability and stability.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and specifically to a method for rapid perception of the topology status of a satellite constellation network. Background Technology

[0002] With the continuous advancement of aerospace technology, satellite constellation networks are being used more and more widely in fields such as communication, navigation, and remote sensing. These networks typically consist of a large number of satellites, achieving data transmission and routing through inter-satellite links. However, due to the unique characteristics of the space environment, inter-satellite networks face many challenges, especially in routing management and fault recovery.

[0003] Traditional network routing protocols, such as OSPF (Open Shortest Path First) and other dynamic routing protocols, while capable of dynamic route calculation and updates, suffer from slow fault detection and convergence speeds. Dynamic routing protocols rely on periodic Hello messages to detect the status of neighboring nodes, a mechanism that is limited in inter-satellite networks by slow detection speed, long convergence time, and high resource consumption. While BFD (Bidirectional Forwarding Detection) can quickly detect link faults, it requires coordination with routing protocols to achieve rapid convergence.

[0004] In recent years, some studies have explored combining BFD with dynamic routing to improve network fault detection and recovery capabilities. For example, by linking BFD with dynamic routing, dynamic route recalculation can be triggered quickly when a link failure occurs, thereby accelerating route convergence. However, these studies have mainly focused on terrestrial networks, and their application to satellite constellation networks is not yet widespread. Furthermore, they also suffer from disadvantages such as long detection times.

[0005] Therefore, to meet the high reliability and rapid response requirements of satellite constellation networks, a state-aware method combining BFD and dynamic routing is urgently needed to achieve rapid fault detection, fast route convergence, and efficient fault recovery. This method should be adaptable to the dynamic topology, high latency, and limited bandwidth characteristics of inter-satellite networks, while reducing resource consumption and improving overall network performance. Summary of the Invention

[0006] This invention addresses the latency issues in link fault detection and route convergence of the traditional OSPF protocol in satellite constellation networks, as well as the shortcomings of existing inter-satellite link fault detection schemes in multi-layered collaborative perception of network anomalies and network health management. It provides a rapid perception method for satellite constellation network topology status. This invention utilizes physical layer signal state monitoring technology and the rapid link state detection capability of the BFD protocol to monitor inter-satellite link connectivity in real time and immediately notify relevant nodes via control messages when a fault is detected. Simultaneously, it links the BFD detection results with the OSPF routing protocol, triggering immediate route recalculation, thereby shortening route convergence time. This invention constructs a cross-layer closed-loop linkage system, dynamically adjusting protocol layer detection parameters through physical layer perception data, and combining hardware acceleration to optimize the entire fault detection process. This approach not only accelerates fault detection and recovery but also improves the resource utilization efficiency and overall transmission efficiency of the inter-satellite network, ensuring high network reliability and stability.

[0007] This invention provides a method for rapid perception of the topology status of a satellite constellation network, comprising the following steps:

[0008] S1. A multi-dimensional physical layer monitoring module, BFD protocol and OSPF routing protocol are deployed on each satellite node in the inter-satellite network. A shared data exchange area between the BFD driver and the OSPF process is created in memory to build a dynamic adaptive BFD detection mechanism.

[0009] S2. The multi-dimensional physical layer monitoring module periodically detects the signal lock status, bit error rate, and Doppler frequency shift of the local satellite's physical link and reports them to the local network management unit. After receiving the reports, the local satellite node generates BFD control messages and exchanges them periodically according to the BFD protocol. The BFD control messages include bit error rate, received signal strength, Doppler frequency shift, local satellite orbit position, and link risk flag.

[0010] When the BFD session detects an abnormality in the reported information, it automatically shortens the BFD control message sending interval and timeout time according to the dynamic adaptive BFD detection mechanism. At the same time, the status in the BFD control message is changed to Down, and a BFD control message including fault diagnosis information is generated and broadcast / multicast.

[0011] S3. The onboard router receives BFD control messages from its own satellite node or other satellite nodes and outputs them to the FPGA processor for parsing and writing into the shared data exchange area.

[0012] S4. The BFD protocol driver periodically polls and reads the shared data exchange area to determine whether the fault link identifier in the shared data exchange area is set. If yes, the BFD control message includes fault diagnosis information and proceeds to step S5. If no, it returns to step S3.

[0013] S5 and BFD protocols notify the OSPF process through a custom interrupt. The OSPF process directly reads the structure field in the shared data exchange area from the mapped user-space address space, starts the main process and triggers a local shortest path first calculation to update the routing table and avoid faulty links.

[0014] Meanwhile, the FPGA directly converts the key fault information parsed from the BFD control message into the core fields of the OSPF LSA message in real time and encapsulates it.

[0015] S6. The local node broadcasts / multicasts OSPF LSA messages containing link state changes to the entire inter-satellite network through flooding, thus completing a method for rapid perception of satellite constellation network topology status.

[0016] The satellite constellation network topology status fast perception method described in this invention, as a preferred embodiment, uses a shared data exchange area as a 64-byte aligned physical contiguous memory space, where both the BFD protocol driver and the OSPF routing process can directly access the specified structure of the shared data exchange area.

[0017] In the preferred embodiment of the satellite constellation network topology status rapid perception method described in this invention, in step S2, the physical links include inter-satellite links and satellite-to-ground links.

[0018] The multi-dimensional physical layer monitoring module captures the received signal power of the physical link in real time through a photodetector or microwave receiver;

[0019] The multi-dimensional physical layer monitoring module performs real-time bit-level verification at the physical layer coding sub-layer by comparing the pseudo-random sequence known at the transmitting end with the decoded data at the receiving end, and calculates the number of erroneous bits per unit time to obtain the real-time bit error rate.

[0020] The multi-dimensional physical layer monitoring module tracks the current frequency offset through a real-time carrier phase-locked loop. At the same time, it combines the position vectors, acceleration vectors, and historical frequency shift data of the satellite itself and neighboring satellites / ground stations to predict the frequency shift trend within a specified time period. When the predicted frequency shift is about to exceed the effective acquisition bandwidth of the receiver, it immediately reports a high link interruption risk status and provides an early warning.

[0021] The fault diagnosis information includes the fault link identifier, source satellite ID, destination satellite ID, fault detection timestamp, and inferred fault cause.

[0022] In the preferred embodiment of the satellite constellation network topology status rapid perception method described in this invention, step S2 is characterized by the following criteria for determining link status anomalies: the received signal strength is lower than a threshold P, or the bit error rate exceeds a threshold 10. -3 Or the link is marked as having a high risk of link outage.

[0023] In the preferred embodiment of the satellite constellation network topology status rapid perception method described in this invention, in step S2, when an abnormal link status is detected, the BFD control message sending interval is automatically shortened from 500ms to 100ms and the timeout time is shortened from 1500ms to 300ms according to the dynamic adaptive BFD detection mechanism.

[0024] According to the dynamic adaptive BFD detection mechanism, after maintaining a normal state for more than 3 current BFD detection cycles, the transmission interval of the BFD control protocol will automatically recover to 500ms and the timeout time will recover to 1500ms.

[0025] The satellite constellation network topology status rapid perception method described in this invention, as a preferred embodiment, includes a BFD control message that further includes a version number, status, detection mode, detection duration multiple, local satellite identifier, neighbor node identifier, negotiated minimum expected transmission interval, negotiated minimum required reception interval, and detection timeout.

[0026] The satellite constellation network topology status rapid perception method described in this invention, as a preferred embodiment, indicates that when the status in the BFD control message is 0, management is off; when the status is 1, it is off; when the status is 2, it is initialized; and when the status is 3, it is enabled (Up).

[0027] When the detection mode is 0, it is asynchronous detection; when the detection mode is 1, it is query mode.

[0028] The local satellite identifier is the local satellite ID, and the neighboring node identifier is the neighboring satellite ID; the detection timeout is the product of the detection duration and the negotiated reception interval.

[0029] In the preferred embodiment of the satellite constellation network topology status rapid perception method described in this invention, in steps S2 and S4, the fault diagnosis information includes fault link identifier, source satellite ID, destination satellite ID, fault detection timestamp, and inferred fault cause. The inferred fault cause includes signal loss, excessively high BER, Doppler exceedance, and risk warning has occurred.

[0030] The BFD control message, which includes fault diagnosis information, also includes critical physical layer snapshot information at the moment the fault occurs;

[0031] In step S5, the key fault information includes status, fault flags, and fault diagnosis information.

[0032] In a preferred embodiment of the satellite constellation network topology status rapid perception method described in this invention, in step S5, when the FPGA parses the BFD control message, if it determines that the message carries link fault information through status or risk flags, the FPGA's internal hardware logic directly converts the key fault information into OSPF LSA message core fields in real time according to predefined conversion rules. The conversion method includes the following steps:

[0033] SⅠ. Identify the BFD fault message type, extract the fault link ID, source satellite ID, destination satellite ID, fault timestamp, fault cause code, and all physical layer snapshot information. The physical layer snapshot information includes bit error rate, received signal strength, and Doppler frequency shift.

[0034] SⅡ: Convert the status field in the BFD control message to 0x00 for use in the LS Age field of the OSPF LSA message;

[0035] SⅢ, Copy the faulty link ID field from the BFD control message directly to the Link StateID field in the OSPF LSA message;

[0036] SⅣ. Copy the source satellite ID field from the BFD control message directly to the AdvertisingRouter field in the OSPF LSA message;

[0037] SⅤ, Take the last 32 bits of the fault timestamp field in the BFD control message and use them in the LSSequence Number field of the OSPF LSA message;

[0038] SVI. Write the fault cause field from the BFD control message into the Options custom flag field of the OSPF LSA message;

[0039] SⅦ. Encapsulate the fault error rate, fault signal strength, Doppler shift, track position and risk flag fields in the BFD control message as extended fields into the LSA extended field;

[0040] SⅧ, complete the encapsulation of OSPF LSA messages.

[0041] This invention is a method for rapid state perception of low-Earth orbit satellite constellation networks with closed-loop linkage from the physical layer to the protocol layer.

[0042] This solution employs a multi-layered network status monitoring and sensing technology. The physical layer supports laser / microwave signal locking monitoring mechanisms, the link layer introduces a link sensing method based on bidirectional forwarding detection, and the network layer runs the OSPF routing protocol. This, in conjunction with ground-based control measures, enables rapid detection of network anomalies and network health management. When network anomalies occur, network status monitoring provides crucial support for achieving network resilience and self-healing capabilities.

[0043] The specific technical steps of this invention are as follows:

[0044] (1) In order to enhance the resilience and self-healing capability of the constellation network, each satellite maintains its own perceived link status information and deploys a multi-dimensional physical layer monitoring module on each satellite to detect key indicators such as signal lock status, bit error rate (BER) and Doppler frequency shift of physical links (including inter-satellite and satellite-to-ground links) in real time.

[0045] (1-1) Signal Strength Detection: This module enables signal strength detection for laser or microwave links. It captures the received signal power in real time using a high-sensitivity photodetector (for laser links) or a microwave receiver (for microwave links). A signal strength threshold of P_min is set; when the received power is lower than P_min, the signal strength is considered insufficient.

[0046] (1-2) Real-time calculation of bit error rate (BER): This module performs real-time bit-level verification by comparing the pseudo-random sequence known at the transmitting end with the data decoded at the receiving end in the physical layer coding sublayer, and counts the number of erroneous bits per unit time, thereby calculating the real-time bit error rate.

[0047] (1-3) Doppler frequency shift tracking and prediction: This module tracks the current frequency offset through a real-time carrier phase-locked loop. At the same time, it combines the position vectors and acceleration vectors of the satellite itself and neighboring satellites / ground stations with historical frequency shift data to predict the frequency shift trend in the near future. When the predicted frequency shift is about to exceed the effective acquisition bandwidth of the receiver, it immediately reports the "high link interruption risk" status to provide early warning.

[0048] (2) The physical layer monitoring module reports the detected status information of each link (inter-satellite, satellite-to-ground) (signal lock-in status, BER, Doppler shift, and predicted risk status, etc.) to the satellite's local network management unit. When the physical layer monitoring module detects an anomaly (such as signal lock-in loss, BER exceeding limits, or risk level changes), it immediately triggers a report; when the status is stable, it periodically reports link health status information. By accessing this reported information, the link layer and network layer protocol stacks can perceive the real-time quality of each link on the satellite more quickly and accurately. At the same time, the satellite encapsulates this link status information into telemetry data and periodically transmits it to the ground control console for ground maintenance personnel to monitor the status of all satellite links in the network.

[0049] (3) Deploy the BFD protocol on each satellite node and build a dynamic adaptive BFD detection mechanism. This mechanism dynamically calculates and adjusts the key parameters of the BFD session based on the link quality data reported in real time by the physical layer (including signal lock status, bit error rate, Doppler frequency shift and predicted risk status), mainly the detection message sending interval and detection timeout time, in order to adapt to the dynamic changes of the satellite link.

[0050] (3-1) The BFD protocol periodically sends control messages between nodes in the inter-satellite network to detect link status in real time. When the link status is assessed as good, the default interval for sending BFD control messages is 500ms.

[0051] The control message format includes standard BFD fields: version number, state (State: 0 = AdminDown, 1 = Down, 2 = Init, 3 = Up), detection mode (DetectMode: 0 = Async, 1 = Echo), detection duration multiplier (Detect Mult), local satellite identifier (YourDiscriminator: satellite ID), neighbor node identifier (My Discriminator: neighbor satellite ID), negotiated minimum expected transmission interval (Desired Min TX Interval), negotiated minimum required reception interval (Required Min RX Interval), and detection timeout (Detect Time = Detect Mult * negotiated reception interval).

[0052] In addition, the message defines extended fields to carry physical layer and status information specific to satellite networks: extension type, value length, bit error rate (BER), received signal strength (RSSI), Doppler shift, local orbital position, and link risk flag.

[0053] (3-2) When the physical layer monitoring module reports any of the following conditions: the received signal strength is lower than the threshold P_min, or the bit error rate (BER) exceeds the threshold 10. -3 When a link is marked as "high risk of link interruption", the BFD protocol's transmission interval will be dynamically adjusted to 100ms immediately. At the same time, the negotiated minimum expected / required interval will also be updated accordingly, thereby significantly shortening the fault detection time.

[0054] (3-3) When all conditions that triggered acceleration have returned to normal levels, signal strength > P_min, BER < threshold, no "high link interruption risk" warning, and the preset recovery waiting time is reached and the normal state is maintained for more than 3 current BFD detection cycles, the BFD protocol transmission interval will automatically return to the default 500ms.

[0055] (4) When a BFD session detects a link failure (State = Down), in addition to the standard BFD Down status message, the system will generate and broadcast / multicast a special BFD fault diagnosis notification message.

[0056] This message contains detailed fault diagnosis information: the faulty link identifier (Link ID), source satellite ID, destination satellite ID (i.e., both ends of the BFD session), fault detection timestamp, inferred fault cause (including signal loss, high BER, Doppler exceedance, risk warning already issued, etc.), and key physical layer snapshot information at the moment of the fault: bit error rate at the time of the fault, signal strength at the time of the fault, Doppler frequency shift, relevant satellite orbital positions, and risk flag status. This detailed information enables relevant nodes in the network, especially neighbors and potentially affected nodes, to quickly and accurately locate the faulty link and understand the nature of the fault, providing sufficient basis for rapid route convergence and network self-healing.

[0057] (5) Deploy the OSPF routing protocol on each satellite node and achieve close linkage between the OSPF routing protocol and BFD. This aims to directly apply the rapid fault detection capability of BFD to the OSPF route convergence process, thereby greatly shortening the route recovery time.

[0058] (5-1) Creating a shared memory region: During the kernel startup phase of the onboard router's operating system, a 64-byte aligned physical contiguous memory space is pre-allocated as a shared data exchange area between the BFD driver and the OSPF process. Both the BFD protocol driver (kernel mode) and the OSPF routing process (user mode) can directly access the specified structure of this shared region.

[0059] (5-2) FPGA-Accelerated BFD Parsing and State Update: BFD messages received by the onboard router are input to the FPGA coprocessor via a high-speed interface. The FPGA hardware logic parses the BFD messages in real time, especially diagnostic notification messages, and directly writes the parsed key fields (such as State, fault flag, diagnostic information, etc.) into the corresponding predefined structure fields in the shared memory area. The BFD protocol driver periodically polls and reads the shared area data. When the driver detects that the link fault flag (bfd_fault_flag = 1) in the shared area is set, it immediately notifies the OSPF user-space process by triggering a custom interrupt.

[0060] (5-3) Fast User-Space Response in OSPF: During startup, the OSPF process maps shared memory regions in the kernel to its user-space address space via system calls such as mmap. When the OSPF process receives a custom interrupt notification triggered by the BFD driver, its interrupt handler directly reads the structure fields from the shared area in the mapped user-space address space. This mechanism completely avoids the software processing overhead of the kernel network protocol stack, significantly reducing the latency of reporting link failure events detected by BFD to the OSPF protocol body from over 20ms to less than 10ms.

[0061] (5-4) FPGA Hardware-Accelerated LSA Generation: While the FPGA is parsing the BFD message, if it determines that the message carries link fault information, such as State = Down or a valid diagnostic flag, the FPGA's internal hardware logic will directly convert the critical fault information into the core fields of the OSPF Link State Advertisement (LSA) message in real time according to predefined conversion rules. The entire conversion process is completed in a pipelined manner within the FPGA, requiring only about 3 FPGA master clock cycles. The conversion rules are as follows:

[0062] (5-4-1) Identify the BFD fault message type and extract the fault link ID, source / destination satellite ID, fault timestamp, fault cause code, and all physical layer snapshot information;

[0063] (5-4-2) Convert the State field in the BFD message to 0x00 for use in the LS Age field of the OSPF LSA message;

[0064] (5-4-3) Copy the faulty link ID field from the BFD message directly to the Link StateID field in the OSPF LSA message;

[0065] (5-4-4) Copy the source satellite ID field from the BFD message directly to the AdvertisingRouter field in the OSPF LSA message;

[0066] (5-4-5) Take the last 32 bits of the fault timestamp field in the BFD message and use them in the LSSequence Number field of the OSPF LSA message;

[0067] (5-4-6) Write the fault cause field in the BFD message into the Options custom flag field in the OSPF LSA message;

[0068] (5-4-7) Encapsulate the fields in the BFD message, such as bit error rate during failure, signal strength during failure, Doppler frequency shift, track position, and risk flag, into the LSA extended field as extended fields;

[0069] (5-4-8) Complete the encapsulation of OSPF LSA messages.

[0070] (5-5) Fast route convergence: Once the OSPF protocol learns of a link failure event through the aforementioned low-latency mechanism, its master process will be immediately scheduled. OSPF only needs to update the entries related to the failed link in the Link State Database (LSDB) and immediately trigger a local Shortest Path First (SPF) calculation. This targeted update and calculation significantly reduces route convergence time compared to traditional network-wide flooding and full SPF calculation.

[0071] (6) Based on the standard mechanism of the OSPF protocol, satellite nodes broadcast / multicast LSAs containing link state changes to the entire inter-satellite network through a reliable flooding method. Combined with the aforementioned fast fault detection and LSA generation mechanism, it ensures that all satellite nodes can receive and process these updates in a very short time, thereby keeping the link state databases (LSDBs) stored by all nodes in the network highly consistent and providing an accurate global network topology view for calculating the optimal route.

[0072] The present invention has the following advantages:

[0073] (1) Rapid Fault Detection: This invention achieves millisecond-level accurate detection and second-level interruption warning of inter-satellite link faults through deep collaboration between multi-dimensional real-time monitoring at the physical layer and a dynamic adaptive BFD protocol. Based on real-time data from the physical layer, the BFD detection frequency is dynamically adjusted and accelerated by FPGA hardware, enabling immediate detection of faults at the moment they occur and a response at the millisecond level, significantly improving the timeliness of fault detection. Compared to traditional methods relying on routing protocol timeouts or static BFD detection, this solution uses Doppler prediction to trigger risk warnings in advance and quickly marks faults when they occur, improving timeliness by two orders of magnitude. This rapid fault detection capability provides immediate feedback to the inter-satellite network, enabling network management to take swift action and avoid potential communication interruptions.

[0074] (2) Fast Route Convergence: This invention implements the linkage between BFD and OSPF protocols. When BFD detects a link failure, OSPF can respond quickly and trigger route recalculation. This mechanism significantly reduces the time required for route convergence, from tens of seconds or even minutes in the traditional way to only a few seconds. Fast route convergence not only improves the adaptability of inter-satellite networks, but also greatly enhances the network's response speed in the face of failures, ensuring the continuity and stability of critical communication tasks, which is crucial for maintaining the high availability of network services. Attached Figure Description

[0075] Figure 1 A flowchart illustrating a method for rapid perception of satellite constellation network topology status;

[0076] Figure 2 A flowchart illustrating the BFD protocol workflow for a rapid satellite constellation network topology status perception method.

[0077] Figure 3 This is a flowchart illustrating the working mechanism of a rapid satellite constellation network topology state perception method after an anomaly. Detailed Implementation

[0078] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0079] Example 1

[0080] like Figures 1-3 As shown, a method for rapid topology status awareness in satellite constellation networks combines physical layer signal status monitoring technology and the rapid link fault detection capability of the BFD (Bidirectional Forwarding Detection) protocol with the dynamic route calculation capability of the OSPF (Open Shortest Path First) protocol to achieve rapid status awareness and rapid fault recovery in satellite constellation networks. The BFD protocol monitors the inter-satellite link status in real time and immediately notifies the OSPF protocol when a fault is detected, triggering immediate route recalculation and updates. Simultaneously, a link status locking monitoring mechanism is introduced to adjust routing strategies in advance, reducing the number of route recalculations caused by link failures.

[0081] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0082] S1. Configure OSPF protocol parameters for each satellite node in the inter-satellite network: unify the area ID to the backbone area (Area 0), set the Hello interval to 10 seconds, and the Dead interval to 3 seconds; set the router priority; assign a unique satellite ID as the Router ID.

[0083] A multi-dimensional physical layer monitoring module is deployed on each satellite to monitor the signal lock status, bit error rate, and Doppler shift of the inter-satellite and satellite-to-ground links, and report the data to the local network management unit in real time. When an abnormal change in the link status is detected, it is reported immediately. If no abnormal change is detected, the link health status is judged every 1 second.

[0084] Configure the basic BFD session parameters for each node in the inter-satellite network. Default parameter settings: Detection mode = asynchronous, transmission interval = 500ms, timeout = 1500ms. When the physical layer reports a risk, automatically switch to accelerated mode, transmission interval = 100ms, timeout = 300ms.

[0085] A BFD session is initialized on the inter-satellite link, and neighbor relationships are established by exchanging BFD control messages. Under normal link conditions, the BFD control message transmission frequency is set to once every 500 milliseconds to adapt to the rapidly changing environment of the inter-satellite network.

[0086] S2. Utilize the BFD protocol to monitor the inter-satellite link in real time, ensuring real-time updates of link status information. When satellite node A detects that the RSSI (Received Signal Strength Indicator) is less than the threshold P_min, or when the bit error rate is greater than 10... -3 Alternatively, when risk_flag (used to identify risk status) = 1, the sending and receiving frequency of BFD protocol control messages will change to once every 100ms. In this case, the maximum BFD protocol link failure detection time is 300ms.

[0087] When BFD detects a link failure, State = Down, the BFD neighbor session is terminated, and the BFD module of satellite node A generates a control message containing the faulty link identifier and quickly sends it to the relevant nodes. The message includes the RSSI, BER (Bit Error Probability), Doppler shift, orbital position, etc. at the moment of the failure, so that the receiving node can quickly identify the location of the failure and take appropriate measures.

[0088] The onboard router terminal at satellite node S3 rapidly transmits BFD fault messages to the OSPF routing module. A shared area is allocated within the onboard router kernel, and the BFD protocol driver and OSPF process directly read and write to this area. When the onboard router receives a BFD message, the FPGA parses it and writes the fault flag (fault_flag = 1) to a 64-byte aligned physical contiguous shared area. The BFD driver initiates a custom hardware interrupt to notify the OSPF process, which then reads the shared area via mmap (memory mapping). By bypassing the traditional protocol stack (TCP / IP), the BFD fault detection result is reported to the OSPF routing protocol, compressing the fault notification latency to less than 10 milliseconds.

[0089] Upon receiving a BFD fault message, the OSPF routing module of the onboard router terminal at satellite node S5 immediately initiates a route recalculation process. During this process, the router assesses the impact range and updates its routing table to avoid the faulty link. The FPGA parses the BFD message, extracts the faulty link ID, endpoint satellite ID, and other information based on the fault information, encapsulates a physical layer snapshot into an OSPF LSA (Link State Advertisement), fills the LSA header, sets LS Age (time elapsed since LSA generation) to 0, and sets SeqNum (sequence number) to a monotonic counter maintained by the FPGA. This completes the direct conversion from BFD message to OSPF LSA message, shortening the processing time to 3 clock cycles.

[0090] S6. Each node in the inter-satellite network periodically (every second) broadcasts its own link status information to all other satellites in the network, ensuring that all nodes in the inter-satellite network maintain consistency in their link status information. In the event of a fault, the satellite node immediately triggers a flooded LSA via multicast address 224.0.0.5, containing fault diagnosis information.

[0091] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for rapid perception of the topology status of a satellite constellation network, characterized in that: Includes the following steps: S1. A multi-dimensional physical layer monitoring module, BFD protocol and OSPF routing protocol are deployed on each satellite node in the inter-satellite network. A shared data exchange area between the BFD driver and the OSPF process is created in memory to build a dynamic adaptive BFD detection mechanism. S2. The multi-dimensional physical layer monitoring module periodically detects the signal lock status, bit error rate, and Doppler frequency shift of the local satellite's physical link and reports them to the local network management unit. After receiving the reports, the local satellite node generates BFD control messages and exchanges them periodically according to the BFD protocol. The BFD control messages include bit error rate, received signal strength, Doppler frequency shift, local satellite orbit position, and link risk flag. When the BFD session detects an abnormality in the reported information, it automatically shortens the BFD control message sending interval and timeout time according to the dynamic adaptive BFD detection mechanism. At the same time, the status in the BFD control message is changed to Down, and a BFD control message including fault diagnosis information is generated and broadcast / multicast. S3. The onboard router receives BFD control messages from the local or other satellite nodes and outputs them to the FPGA processor for parsing and writing into the shared data exchange area. S4. The BFD protocol driver periodically polls and reads the shared data exchange area to determine whether the fault link identifier in the shared data exchange area is set. If yes, the fault diagnosis information is included in the BFD control message, and the process proceeds to step S5. If no, the process returns to step S3. S5 and BFD protocols notify the OSPF process through a custom interrupt. The OSPF process directly reads the structure field in the shared data exchange area from the mapped user-space address space, starts the main process and triggers a local shortest path first calculation to update the routing table and avoid faulty links. Meanwhile, the FPGA directly converts the key fault information parsed from the BFD control message into the core fields of the OSPF LSA message in real time and encapsulates it. S6. The local node broadcasts / multicasts OSPF LSA messages containing link state changes to the entire inter-satellite network through flooding, thus completing a method for rapid perception of satellite constellation network topology status.

2. The method for rapid perception of satellite constellation network topology status according to claim 1, characterized in that: The shared data exchange area is a 64-byte aligned physical contiguous memory space, and both the BFD protocol driver and the OSPF routing process can directly access the specified structure of the shared data exchange area.

3. The method for rapid perception of satellite constellation network topology status according to claim 1, characterized in that: In step S2, the physical links include inter-satellite links and satellite-to-ground links; The multi-dimensional physical layer monitoring module captures the received signal power of the physical link in real time through a photodetector or microwave receiver; The multi-dimensional physical layer monitoring module performs real-time bit-level verification at the physical layer coding sub-layer by comparing the pseudo-random sequence known at the transmitting end with the data decoded at the receiving end, and calculates the number of erroneous bits per unit time to obtain the real-time bit error rate. The multi-dimensional physical layer monitoring module tracks the current frequency offset through a real-time carrier phase-locked loop. At the same time, it combines the position vectors, acceleration vectors, and historical frequency shift data of the satellite itself and neighboring satellites / ground stations to predict the frequency shift trend within a specified time period. When the predicted frequency shift is about to exceed the effective acquisition bandwidth of the receiver, it immediately reports a high link interruption risk status and provides an early warning. The fault diagnosis information includes the fault link identifier, source satellite ID, destination satellite ID, fault detection timestamp, and inferred fault cause.

4. The method for rapid perception of satellite constellation network topology status according to claim 1, characterized in that: In step S2, the criteria for determining link status anomalies are: the received signal strength is lower than the threshold P, or the bit error rate exceeds the threshold 10. -3 Or the link is marked as having a high risk of link outage.

5. The method for rapid perception of satellite constellation network topology status according to claim 1, characterized in that: In step S2, when an abnormal link status is detected, the BFD control message sending interval is automatically shortened from 500ms to 100ms and the timeout time is shortened from 1500ms to 300ms according to the dynamic adaptive BFD detection mechanism. According to the dynamic adaptive BFD detection mechanism, after maintaining a normal state for more than 3 current BFD detection cycles, the transmission interval of the BFD control protocol is automatically restored to 500ms and the timeout time is restored to 1500ms.

6. The method for rapid perception of satellite constellation network topology status according to claim 1, characterized in that: The BFD control message also includes version number, status, detection mode, detection duration multiple, local identifier, neighbor node identifier, negotiated minimum expected transmission interval, negotiated minimum required reception interval, and detection timeout.

7. The method for rapid perception of satellite constellation network topology status according to claim 6, characterized in that: When the status of the BFD control message is 0, management is off; when the status is 1, it is off; when the status is 2, it is initialized; when the status is 3, it is enabled (Up). When the detection mode is 0, it is asynchronous detection; when the detection mode is 1, it is query mode. The local satellite identifier is the local satellite ID, and the neighboring node identifier is the neighboring satellite ID; the detection timeout is the product of the detection duration multiple and the negotiated reception interval.

8. The method for rapid perception of satellite constellation network topology status according to claim 1, characterized in that: In steps S2 and S4, the fault diagnosis information includes a fault link identifier, source satellite ID, destination satellite ID, fault detection timestamp, and inferred fault cause. The inferred fault cause includes signal loss, excessively high BER, Doppler overshoot, and risk warning has occurred. The BFD control message, which includes fault diagnosis information, also includes critical physical layer snapshot information at the moment the fault occurs; In step S5, the key fault information includes status, fault flag, and fault diagnosis information.

9. The method for rapid perception of satellite constellation network topology status according to claim 1, characterized in that: In step S3, when the FPGA parses the BFD control message, if it determines that the message carries link fault information through the status or risk flag, the FPGA's internal hardware logic directly converts the critical fault information into the core fields of the OSPF LSA message in real time according to predefined conversion rules. The conversion method includes the following steps: SⅠ. Identify the BFD fault message type, extract the fault link ID, source satellite ID, destination satellite ID, fault timestamp, fault cause code, and all physical layer snapshot information, wherein the physical layer snapshot information includes bit error rate, received signal strength, and Doppler frequency shift; SⅡ: Convert the status field in the BFD control message to 0x00 for use in the LS Age field of the OSPF LSA message; SⅢ, Copy the faulty link ID field from the BFD control message directly to the Link State ID field in the OSPF LSA message; SⅣ. Copy the source satellite ID field from the BFD control message directly to the Advertising Router field in the OSPF LSA message; SⅤ, Take the last 32 bits of the fault timestamp field in the BFD control message and use them in the LSSequence Number field of the OSPF LSA message; SVI. Write the fault cause field from the BFD control message into the Options custom flag field of the OSPF LSA message; SⅦ. Encapsulate the fault error rate, fault signal strength, Doppler shift, track position and risk flag fields in the BFD control message as extended fields into the LSA extended field; SⅧ, complete the encapsulation of OSPF LSA messages.

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