A low-orbit mega-constellation-oriented active hierarchical border gateway protocol routing method and system
By optimizing the routing mechanism of the LEO Giants network through the proactive hierarchical border gateway protocol routing method, the problems of network instability and high overhead of traditional BGP in the LEO Giants network are solved, and fast convergence and efficient route updates are achieved.
Patent Information
- Application Number
- CN202411391721.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-08
- Publication Date
- 2025-10-24
- Estimated Expiration
- 2044-10-08
AI Technical Summary
Traditional BGP protocols cause network instability, excessive routing overhead, and slow convergence speed in the Low Orbit Giants constellation network, making them unsuitable for the needs of highly dynamic and large-scale networks.
The active hierarchical border gateway protocol routing method is adopted. By dividing time frames and time slots, satellite partitioning and predicting satellite-to-ground connection switching, the iBGP_PATH path attribute and active route update mechanism are introduced to optimize iBGP connection and route convergence mechanism.
It accelerates route convergence, reduces network overhead, improves adaptability and stability to the low-Earth orbit giant constellation, and ensures network scalability and robustness.
Smart Images
Figure CN119233357B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of satellite network routing, in particular to an active hierarchical Border Gateway Protocol routing method and system for a low-orbit mega constellation. BACKGROUND
[0002] Low-orbit mega constellation networks are expected to become one of the most important communication infrastructures due to their great potential in providing low-latency, high-reliability, and ubiquitous connectivity services. The development of low-orbit mega constellation networks has promoted the field of satellite communication. Compared with traditional geosynchronous satellites, low-orbit satellites operate at a lower altitude, providing global coverage and high backhaul capacity. Low-orbit mega constellation networks represent a promising technology that can achieve seamless global connectivity and advanced applications to meet the demands of large-scale communication and personalized user experience in 6G.
[0003] Low-orbit satellite networks can be regarded as an independent autonomous domain, and its organic integration with different ground autonomous systems requires an inter-domain routing protocol, BGP (Border Gateway Protocol). However, the traditional BGP protocol mainly considers the accuracy of reachable routes and is customized for fixed networks. Directly using traditional BGP in low-orbit satellite networks will lead to network instability, excessive routing overhead, slow convergence speed, and other problems.
[0004] Unlike the relatively fixed topology of ground networks, space networks have high dynamic characteristics. Frequent changes in space topology will lead to frequent updates of BGP neighbor relationships and destination network segment entries. When the physical link between satellite system border routers changes, i.e., the physical link connection with the opposite satellite system is switched from one border router of the opposite system to another, the inter-system BGP neighbor relationship changes, the old BGP neighbor relationship is disconnected, and the BGP entity establishes a new neighbor relationship by sending messages. When the destination network segment entry is increased / decreased or changed, the BGP entity triggers route updates, and route information needs to be re-flooded throughout the network until convergence. For BGP, instability is a key issue. Instability of inter-domain neighbor relationships, frequent route updates, slow route convergence, and other problems will compromise the stability of low-orbit satellite networks and affect the data plane and control plane. Therefore, it is necessary to optimize the traditional BGP in combination with the satellite scale and high dynamic characteristics such as high-speed movement of nodes and frequent topology changes in the low-orbit mega constellation scenario.
[0005] Traditional BGP generally adopts full-mesh and route reflector iBGP (Internal BGP) connection strategies. The full-mesh strategy connects iBGP peers two by two, ensuring global routing optimality in small local networks, commonly known as full-mesh optimality, which we usually refer to when evaluating BGP routing. However, it is not scalable and cannot be deployed in low-orbit satellite networks. The route reflector strategy reduces iBGP connections to some extent, but route reflection may reduce network robustness to failures, introduce delayed route convergence, reduce path diversity, use suboptimal routes, and even cause data forwarding loops.
[0006] After searching the existing literature, we found that Yang Zengying et al. published an article entitled "NTD-BGP: An Inter-domain Routing Protocol for Integrated Space-Terrestrial Networks" in the Journal of Tsinghua University (Science and Technology) in 2019. This article proposes an inter-domain neighbor discovery mechanism independent of physical topology changes based on decoupling the mapping relationship between network topology and inter-domain neighbor relationships and route updates. However, this mechanism significantly reduces the interaction efficiency between eBGP (External BGP) neighbors, especially when the distance between ground stations and satellites is far.
[0007] After searching the existing literature, we found that Jinhu Zang et al. published an article entitled "A Border Gateway Protocol LRA-BGP for Integrated Satellite-terrestrial Networks" in the 2022 International Conference on Electrical, Mechanical and Computer Engineering (ICEMCE) in 2022. This article proposes a lightweight border gateway protocol (LRA-BGP) suitable for small-scale networks. Border satellites deploying LRA-BGP do not publish historical route information to the other party after neighbor relationship reconstruction, and both parties achieve route updates by activating backup route information.
[0008] In summary, these works as explorations for optimizing the border gateway protocol are a good start, but they all have limitations: (1) In terms of protocol scalability, these works only focus on adaptation in small-scale low-orbit constellations and do not consider reducing the number of iBGP connections in low-orbit mega-constellation scenarios; (2) In terms of protocol dynamic adaptability, most works lack a response method for frequent star-ground switching, leading to network instability; (3) In terms of protocol routing overhead, these works introduce additional message overhead and computational cost, which cannot adapt to low-orbit mega-constellation scenarios. SUMMARY
[0009] The application aims at the limitations of the prior art and provides an active hierarchical border gateway protocol routing method and system for a low-orbit giant constellation, so as to realize fast routing convergence and take into account protocol overhead and routing stability in a low-orbit giant constellation scenario.
[0010] Technical scheme: In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:
[0011] An active hierarchical border gateway protocol routing method for a low-orbit giant constellation, comprising the following steps:
[0012] Time frame and time slot division are performed, the satellite-ground connection switching and the throughput of each satellite in a time frame are predicted, the time frame is divided into a plurality of time slots, and the satellite network is divided into an entrance and exit satellite area, a backbone area and a non-backbone area;
[0013] iBGP connection is performed according to the satellite partition, a mechanism for performing routing update in different time slots is decided according to the time slot division, and a reference table for distributing active routing update is provided;
[0014] In a time slot using only a hierarchical convergence mechanism, hierarchical transmission and reception of UPDATE messages for exchanging routing information are performed by each partition satellite to achieve global network convergence, a new path attribute iBGP_PATH in the UPDATE message helps hierarchical routing transmission and realizes loop prevention in the domain;
[0015] In a time slot using an active routing update mechanism to assist the hierarchical convergence mechanism, the satellite actively updates the routing table entries and transmits and receives posteriori UPDATE messages for verification.
[0016] As a preferred embodiment, the satellite network division comprises:
[0017] In a time frame, the satellites involved in satellite-ground connection switching are divided into entrance and exit satellites, the satellites with a throughput exceeding a preset threshold are divided into IGP hotspot satellites, a preset number of backbone satellites are selected from the IGP hotspot satellites, and the remaining satellites are divided into non-backbone satellites.
[0018] As a preferred embodiment, the iBGP connection according to the satellite partition comprises:
[0019] At the start time of the time frame, the entrance and exit satellites are connected to the two backbone area satellites closest in physical distance using iBGP connection; the full connection strategy is used in the backbone area; and the non-backbone area satellites are connected to at least one backbone area satellite.
[0020] As a preferred embodiment, the mechanism for performing routing update in different time slots according to the time slot division comprises:
[0021] According to the constellation scale, the decision hop number is preset. If the hop number between the old and new exit / entry satellites is calculated to be less than the decision hop number, an active route update mechanism is used to assist the hierarchical convergence mechanism to perform route convergence. If the hop number between the old and new exit / entry satellites is calculated to be greater than or equal to the decision hop number, only the hierarchical convergence mechanism is used to perform route fast update.
[0022] The time point of using the active route update mechanism and the old and new exit / entry satellite Router_id pair are recorded in sequence, wherein the Router_id is the loopback address of the satellite by default, and is distributed to the exit / entry satellites and backbone area satellites at the beginning of the time frame as the reference entry of the active route update.
[0023] As a preferred embodiment, the UPDATE message adds a path attribute iBGP_PATH to help select the best path and filter the specified route. The path attribute iBGP_PATH shows the ordered sequence of router Router_id during route propagation and is saved in network byte order. The hierarchical convergence mechanism uses the path attribute AS_PATH of the traditional BGP to implement inter-domain loop prevention, and uses the added iBGP_PATH to implement intra-domain loop prevention. When forwarding the UPDATE message, the router first checks whether the router Router_id exists in the iBGP_PATH attribute of the message. If the router Router_id exists, the message is discarded. Otherwise, the router Router_id is added to the iBGP_PATH attribute of the message.
[0024] As a preferred embodiment, the hierarchical convergence mechanism stipulates that the backbone area adopts the intra-domain horizontal segmentation principle, that is, the routes learned by the backbone area satellite from its iBGP neighbor are not transmitted to other iBGP neighbors. The non-backbone area breaks the horizontal segmentation rule, prevents route loops by using the added path attribute iBGP_PATH, and reduces the number of iBGP connections of the non-backbone area satellite. The UPDATE message can only be transmitted from the backbone area to the non-backbone area. The exit / entry satellite area and the backbone area can transmit the UPDATE message to each other.
[0025] As a preferred embodiment, the satellite actively updates the route table entry and transmits and receives the posteriori UPDATE message for verification, including:
[0026] The old exit / entry satellite network segment entry of the BGP route table of the backbone area satellite is searched, the old exit / entry satellite Router_id in the entry is actively updated to the new exit / entry satellite Router_id, and the temporary entry is saved until the new exit / entry satellite network segment under the time slot is invalidated and removed;
[0027] A new exit / entry satellite network segment-new exit / entry satellite Router_id route entry is added to the BGP route table of the backbone area satellite;
[0028] The control access satellite area sends the UPDATE posterior message to the backbone area to verify the active route update entry, when the correct update, the process of sending the UPDATE posterior message does not affect the whole network convergence time; when the update error occurs, the corresponding route entry will be corrected as the route information of the UPDATE posterior message and continue to be transmitted through the hierarchical convergence mechanism.
[0029] An active hierarchical border gateway protocol routing system for a low-orbit mega constellation, comprising:
[0030] A prediction module for time frame and time slot division, predicting the satellite-ground connection switching and the throughput of each satellite in a time frame, and dividing the satellite network into access satellite area, backbone area and non-backbone area;
[0031] A decision module for iBGP connection according to satellite partition, route update mechanism in different time slots according to time slot division decision, and distribution of active route update reference table;
[0032] A hierarchical convergence mechanism implementation module for achieving whole network convergence by exchanging route information through each partition satellite hierarchical transmission and reception of UPDATE messages in time slots using hierarchical convergence mechanism, and the newly added path attribute iBGP_PATH in the UPDATE message helps hierarchical transmission of routes and realizes intra-domain loop prevention;
[0033] An active route update mechanism implementation module for active update of satellite route table entries and reception and transmission of posterior UPDATE messages for verification in time slots using active route update mechanism assisted hierarchical convergence mechanism.
[0034] A computer system comprising a memory, a processor and a computer program / instruction stored on the memory and executable on the processor, which when executed by the processor implements the steps of the active hierarchical border gateway protocol routing method for a low-orbit mega constellation.
[0035] A computer program product comprising a computer program / instruction, which when executed by a processor implements the steps of the active hierarchical border gateway protocol routing method for a low-orbit mega constellation.
[0036] Beneficial effects: The low-orbit giant constellation-oriented active hierarchical border gateway protocol routing method and system provided by the application introduces new intra-domain routing loop prevention and routing transmission mechanisms based on the traditional border gateway protocol. Unlike the full connection, route reflector, and other iBGP connection strategies of the traditional BGP, the application adopts an innovative hierarchical convergence mechanism based on the path attribute iBGP_PATH. Unlike the traditional BGP, which realizes route update by continuously withdrawing / re-announcing route prefixes, the application introduces an active route update mechanism based on star-ground switching prediction to assist the hierarchical convergence mechanism. Compared with the prior art, the low-orbit giant constellation-oriented active hierarchical border gateway protocol routing method proposed by the application takes into account the protocol overhead and route stability, accelerates the route convergence speed of the network, and improves the adaptability to the large-scale and high-dynamic characteristics of the low-orbit giant constellation. At the same time, the application also ensures the backward compatibility for the standard BGP router. BRIEF DESCRIPTION OF DRAWINGS
[0037] Figure 1 is a framework diagram of the routing system of the embodiment of the application;
[0038] Figure 2 is an update schematic diagram of the active route update mechanism in the embodiment of the application to the BGP routing table;
[0039] Figure 3 is a routing method flowchart of the embodiment of the application;
[0040] Figure 4 is a routing method experimental result comparison diagram of the embodiment of the application. DETAILED DESCRIPTION
[0041] In order to make the purpose, technical scheme and advantages of the application clearer and more apparent, the embodiments of the application are described in detail below in combination with the drawings: The embodiments are implemented on the premise of the technical scheme of the application, and give detailed implementation manners and specific operation processes. It should be understood that the specific examples described herein are only used to explain the application, and the protection scope of the application is not limited to the following embodiments.
[0042] As Figure 1As shown, the low-orbit giant constellation-oriented active hierarchical Border Gateway Protocol routing method disclosed by the embodiment of the application first performs time frame and time slot division, predicts the satellite-ground connection switching and the throughput of each satellite in a time frame, and divides the satellite network into an entrance and exit satellite area, a backbone area and a non-backbone area; then performs iBGP connection according to the satellite partition, decides the routing update mechanism in different time slots according to the time slot division, and distributes the reference table of active routing update; in the time slot using only the hierarchical convergence mechanism, each partition satellite exchanges routing information by hierarchical sending and receiving UPDATE messages to achieve global network convergence, a new path attribute iBGP_PATH is added in the UPDATE message to help hierarchical delivery of routes and realize loop prevention in the domain; in the time slot using the active routing update mechanism to assist the hierarchical convergence mechanism, the satellite actively updates the routing table entries and transmits and receives posteriori UPDATE messages for verification.
[0043] In the implementation, the snapshot technology based on the existing virtual topology can be used to predict the satellite-ground connection switching and the throughput of each satellite in each time frame.
[0044] Figure 3 As shown is the execution flow of the method described in the embodiment in a time frame. Referring to Figure 1 and Figure 3 , the detailed steps of the method described in the embodiment are as follows:
[0045] Step S1, divide the time into several time frames, predict the satellite-ground connection switching and the throughput of each satellite in a time frame, divide the time frame into several time slots and divide the satellite network into several areas.
[0046] Specifically, in a time frame, the satellites involved in the satellite-ground connection switching are divided into entrance and exit satellites, the satellites with high throughput are divided into IGP (Interior Gateway Protocol) hotspot satellites, and a proper number of backbone satellites are selected from the IGP hotspot satellites, and the remaining satellites are divided into non-backbone satellites; in a time frame, the time slots corresponding to the satellite-ground connection switching and the new and old entrance and exit satellites are saved.
[0047] Step S2, perform iBGP connection according to the satellite partition, decide the routing update mechanism in different time slots according to the time slot division, and distribute the reference table of active routing update.
[0048] Specifically, in this step, different iBGP connection methods are set according to the satellite division of the access satellite area, the backbone area and the non-backbone area. At the start time of the time frame, the access satellite adopts iBGP connection to connect to the two closest backbone satellites in physical distance. The backbone area adopts a full connection strategy to connect all the backbone satellites in pairs. The non-backbone satellite is connected to at least one backbone satellite, and additional iBGP connections of the non-backbone area can be introduced to enhance the network robustness according to the needs.
[0049] According to the constellation scale, the decision hop count is preset. Taking the export satellite as an example, if the calculated hop count between the old and new export satellites is less than the decision hop count, the active route update mechanism is used to assist the hierarchical convergence mechanism for route convergence; if the calculated hop count between the old and new export satellites is greater than or equal to the decision hop count, only the hierarchical convergence mechanism is used for route fast update; for the import satellite, the hop count between the old and new import satellites is calculated, and the rest is the same.
[0050] The time t and the old / new export satellite Router_id pair that uses the active route update mechanism are recorded in sequence through calculation, where Router_id is the loopback address of the satellite by default, and is distributed to the access satellite, the import satellite and the backbone satellite at the start of the time frame. The reference table for active route update is shown in Table 1.
[0051] Table 1 Reference table for active route update
[0052]
[0053] Step S3, judging the route update mechanism of the current time slot, when only the hierarchical convergence mechanism is used in this time slot, the hierarchical transmission and reception of UPDATE messages by each satellite in the partition exchanges route information to achieve global convergence.
[0054] In this embodiment, the UPDATE message contains several path attributes to help select the best path and filter specified routes. The hierarchical convergence mechanism introduces an innovative path attribute iBGP_PATH. The path attribute iBGP_PATH is an optional attribute of the UPDATE message, which can be set to pass / non-pass according to needs. The path attribute iBGP_PATH shows the ordered sequence of router Router_id during route propagation, and is saved in network byte order.
[0055] In this step, the hierarchical convergence mechanism uses the path attribute AS_PATH of the traditional BGP to realize the inter-domain loop prevention, and uses the newly added iBGP_PATH to realize the intra-domain loop prevention. When forwarding the UPDATE message, the router first checks whether the Router_id of the router exists in the iBGP_PATH attribute of the message. If the Router_id exists, the message is discarded; otherwise, the Router_id of the router is added to the iBGP_PATH attribute of the message, i.e., the loopback address of the router is added to the beginning of the sequence.
[0056] The backbone area adopts the intra-domain horizontal segmentation principle, i.e., the routes learned by the satellite of the backbone area from its iBGP neighbor are not transmitted to other iBGP neighbors of the satellite. The non-backbone area breaks the horizontal segmentation principle, prevents the route loop by means of the newly added path attribute iBGP_PATH, and reduces the number of iBGP connections of the satellite in the non-backbone area.
[0057] The hierarchical convergence mechanism stipulates that the UPDATE message can be transmitted from the backbone area to the non-backbone area, and the UPDATE message can be transmitted between the entry-exit satellite area and the backbone area. The standard BGP filter is modified to realize the above route filtering principle.
[0058] In step S4, when the active route update mechanism is used to assist the hierarchical convergence mechanism in the time slot, the satellite performs active update on the route table entry, and transmits and receives the posterior UPDATE message for verification.
[0059] The NEXT_HOP attribute is a necessary attribute of the UPDATE message, and indicates the border router leaving / entering an autonomous domain. In the embodiment, the next_hop_self function is enabled for the entry-exit satellite area, and the NEXT_HOP attribute of the BGP route table records the loopback address of the border satellite. When the satellite-ground connection switching occurs, taking the exit satellite as an example, the relevant BGP route entry is updated, and the NEXT_HOP attribute is converted from the Router_id of the old exit satellite to the Router_id of the new exit satellite; for the entry satellite, the same is true.
[0060] When the clock system of the satellite in the backbone area detects that the current time t matches a time t0 in the active route update reference table, the active route update mechanism is triggered, as shown in FIG. 6. Figure 2
[0061] Specifically, in this step, the active route update mechanism retrieves the old exit satellite network segment p past in the BGP route table of the satellite in the backbone area, replaces the old exit satellite loopback address Router_id past in the entry with the new exit satellite loopback address Router_id new , and saves the temporary entry until the new exit satellite network segment pnew Failure is removed.
[0062] The active route update mechanism adds a new egress satellite network segment p to the BGP route table of the backbone area satellite new - New egress satellite loopback address Router_id new route entry.
[0063] The active route update mechanism controls the ingress and egress satellite area to send the UPDATE posterior message to the backbone area to verify the active route update entry. Specifically, when the backbone area receives the message, the destination network segment in the message is searched. If the NEXT_HOP attribute is consistent with the BGP route table of the backbone area itself, the active route update result is correct. If it is not consistent, the corresponding network segment entry of the BGP route table is updated. When the update is correct, the process of sending the UPDATE posterior message does not affect the global network convergence time. When the update is incorrect, the corresponding route entry is corrected to the route information of the UPDATE posterior message and continues to be transmitted through the hierarchical convergence mechanism.
[0064] In this embodiment, the active route update mechanism is an auxiliary and supplement to the hierarchical convergence mechanism, and the hierarchical convergence mechanism is used for cross-area route information transmission.
[0065] From the above, the optimization of the border gateway protocol in the low-orbit mega constellation according to the present application can be summarized as follows: (1) scalability: ensuring the scalability of the protocol in the low-orbit mega constellation, especially minimizing the number of iBGP connections in the satellite network; (2) dynamic adaptability: adapting to highly dynamic ground-satellite link switching, improving convergence speed and maintaining network stability under frequent ground-satellite link changes; (3) route overhead: BGP message overhead and computing load, ensuring the above two characteristics while minimizing additional overhead and computing cost.
[0066] To verify the effect of the present application, the embodiment of the present application completes experiments on a self-developed high-fidelity and high-efficiency satellite internet system level simulation platform. The performance of the number of iBGP connections, message overhead, average convergence time and packet loss rate of the traditional full connection strategy, the route reflector and the embodiment of the present application are compared. The experimental results are shown in Figure 4 As shown in the table, the embodiment of the present application can effectively reduce the number of iBGP connections and BGP message overhead, and at the same time, accelerate the route convergence speed, and has obvious effect on reducing data forwarding packet loss under different satellite scales.
[0067] Based on the same inventive concept, the embodiment of the present application also discloses a low-orbit mega-constellation active hierarchical BGP routing system, comprising: a prediction module, configured to divide time frames and time slots, predict satellite-ground connection switching and throughput of each satellite in a time frame, and divide the satellite network into entry and exit satellite areas, backbone areas and non-backbone areas; a decision module, configured to make iBGP connection according to the satellite partition, make a decision on the routing update mechanism in different time slots according to the time slot division, and distribute a reference table of active routing update; a hierarchical convergence mechanism implementation module, configured to, in a time slot using the hierarchical convergence mechanism, exchange routing information by hierarchical transmission and reception of UPDATE messages by each partition satellite to achieve global network convergence, wherein a new path attribute iBGP_PATH in the UPDATE message helps hierarchical transmission of the route and realizes loop prevention in the domain; and an active routing update mechanism implementation module, configured to, in a time slot using the active routing update mechanism to assist the hierarchical convergence mechanism, update the routing table entries actively by the satellite, and verify by transmitting and receiving posteriori UPDATE messages.
[0068] Based on the same inventive concept, the embodiment of the present application also discloses a computer system, comprising a memory, a processor and a computer program / instruction stored on the memory and executable on the processor, wherein the computer program / instruction is executed by the processor to implement the steps of the low-orbit mega-constellation active hierarchical BGP routing method.
[0069] Based on the same inventive concept, the embodiment of the present application also discloses a computer program product, comprising a computer program / instruction, wherein the computer program / instruction is executed by the processor to implement the steps of the low-orbit mega-constellation active hierarchical BGP routing method.
[0070] The program / instruction code for implementing the method of the present application can be written in any combination of one or more programming languages. The program / instruction code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program / instruction code, when executed by the processor or controller, causes the steps of the method of the present application to be implemented. The program / instruction code can be executed entirely on a machine, partially on a machine, partially on a machine as a stand-alone software package, partially on a machine and partially on a remote machine or entirely on a remote machine or server. The present application does not detail what is known to those skilled in the art.
[0071] The above description is only the preferred embodiment of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.
Claims
1. A method for active hierarchical border gateway protocol routing for low earth mega-constellation, characterized in that, The method comprises the following steps: Time frame and time slot division, prediction of satellite-ground connection switching and throughput of each satellite in a time frame, and division of the satellite network into entry-exit satellite area, backbone area and non-backbone area; Internal Border Gateway Protocol (iBGP) connection according to satellite division, mechanism for route update in different time slots according to time slot division decision, and distribution of reference table for active route update; The mechanism for route update in different time slots according to time slot division decision comprises the following steps: presetting decision hop number according to constellation scale, using active route update mechanism to assist hierarchical convergence mechanism to perform route convergence if the calculated hop number between old and new exit / entry satellites is less than the decision hop number, and using only hierarchical convergence mechanism to perform route fast update if the calculated hop number between old and new exit / entry satellites is greater than or equal to the decision hop number; sequentially recording the time when the active route update mechanism is used and the old and new exit / entry satellite Router_id pairs, wherein the Router_id is the loopback address of the satellite by default, and the reference table item for active route update is distributed to the exit / entry satellites and the satellites in the backbone area at the beginning of the time frame; the hierarchical convergence mechanism stipulates that the satellites in the backbone area adopt the principle of horizontal division in the domain, i.e. the routes learned by the satellites in the backbone area from their iBGP neighbors will not be transmitted to other iBGP neighbors of the satellites; the satellites in the non-backbone area break the horizontal division rule, prevent route loop by means of the newly added path attribute iBGP_PATH, and reduce the number of iBGP connections of the satellites in the non-backbone area; the UPDATE message can only be transmitted from the satellites in the backbone area to the satellites in the non-backbone area, and the UPDATE message can be transmitted between the exit / entry satellites and the satellites in the backbone area; In the time slot where only the hierarchical convergence mechanism is used, the satellites in each division level exchange route information by transmitting and receiving UPDATE messages, and the satellites in the non-backbone area achieve global convergence by means of the hierarchical transmission of the UPDATE messages; the newly added path attribute iBGP_PATH in the UPDATE message helps to prevent loop in the domain; In the time slot where the active route update mechanism assists the hierarchical convergence mechanism, the satellites actively update the route table entries and verify the updated route table entries by transmitting and receiving posteriori UPDATE messages.
2. The method of claim 1, wherein the method is a low earth mega constellation oriented proactive hierarchical border gateway protocol routing method. The division of the satellite network comprises the following steps: In a time frame, the satellites involved in satellite-ground connection switching are divided into exit / entry satellites, the satellites with throughput exceeding a preset threshold are divided into IGP hot spot satellites, a preset number of backbone satellites are selected from the IGP hot spot satellites, and the remaining satellites are divided into non-backbone satellites.
3. The method of claim 1, wherein the method is a low earth mega constellation oriented proactive hierarchical border gateway protocol routing method. The iBGP connection according to satellite division comprises the following steps: At the beginning of the time frame, the exit / entry satellites are connected to the two satellites in the backbone area closest in physical distance by means of iBGP connection; the satellites in the backbone area are connected by means of full connection strategy; and the satellites in the non-backbone area are connected to at least one satellite in the backbone area.
4. The method of claim 1, wherein the method is a low earth mega constellation oriented proactive hierarchical border gateway protocol routing method. The UPDATE message adds a path attribute iBGP_PATH to help select the best path and filter the designated route, the path attribute iBGP_PATH shows the ordered sequence of router Router_id when the route is propagated, and is saved in network byte order; the hierarchical convergence mechanism uses the path attribute AS_PATH of the traditional BGP to implement inter-domain anti-loop, and uses the added iBGP_PATH to implement intra-domain anti-loop, when forwarding the UPDATE message, the router first checks whether the Router_id of the router exists in the iBGP_PATH attribute of the message, if the Router_id exists, the message is discarded, otherwise, the Router_id of the router is added to the iBGP_PATH attribute of the message.
5. The method of claim 1, wherein, The satellite actively updates the routing table entries and transmits and receives posterior UPDATE messages for verification, including: Retrieving the old egress / ingress satellite network segment entries of the backbone area satellite BGP routing table, actively updating the old egress / ingress satellite Router_id in the entries to the new egress / ingress satellite Router_id, and saving the entries until the new egress / ingress satellite network segment under the time slot is invalidated and removed; Adding new egress / ingress satellite network segment-new egress / ingress satellite Router_id routing entries to the backbone area satellite BGP routing table; Controlling the egress / ingress satellite area to send UPDATE posterior messages to the backbone area to verify the active routing update entries, when the update is correct, the process of sending the UPDATE posterior message does not affect the global network convergence time; when the update is incorrect, the corresponding routing entry is corrected to the routing information of the UPDATE posterior message and continues to be transmitted through the hierarchical convergence mechanism.
6. A low earth mega constellation oriented active hierarchical border gateway protocol routing system, characterized in that, Including: A prediction module for time frame and time slot division, predicting the satellite-ground connection switching and the throughput of each satellite in a time frame, and dividing the satellite network into an egress / ingress satellite area, a backbone area and a non-backbone area; A decision module for internal border gateway protocol iBGP connection according to satellite partition, time slot division decision mechanism for routing update under different time slots, and distribution of the reference table of active routing update; The mechanism for routing update in different time slots according to the time slot division decision comprises: presetting a decision hop number according to a constellation size, if a calculated hop number between old and new exit / inlet satellites is less than the decision hop number, using an active routing update mechanism to assist a hierarchical convergence mechanism to perform routing convergence; if the calculated hop number between the old and new exit / inlet satellites is greater than or equal to the decision hop number, only using the hierarchical convergence mechanism to perform routing fast update; sequentially recording a time when the active routing update mechanism is used and an old and new exit / inlet satellite Router_id pair, wherein the Router_id is a loopback address of the satellite by default, and is distributed to exit / inlet satellites and backbone area satellites at the beginning of a time frame as a reference entry for active routing update; the hierarchical convergence mechanism stipulates that the backbone area uses an intra-domain horizontal segmentation principle, that is, a route learned by a backbone area satellite from its iBGP neighbor will not be transmitted to other iBGP neighbors of the satellite; the non-backbone area breaks the horizontal segmentation rule, prevents routing loops by means of a newly added path attribute iBGP_PATH, and reduces the number of iBGP connections of the non-backbone area satellite; an UPDATE message can only be transmitted from the backbone area to the non-backbone area, and the exit / inlet satellite area and the backbone area can transmit the UPDATE message to each other; The hierarchical convergence mechanism implementation module is configured to, in a time slot in which the hierarchical convergence mechanism is used, exchange routing information by satellites in each subarea to achieve global network convergence, wherein a newly added path attribute iBGP_PATH in an UPDATE message helps hierarchical routing transmission and realizes intra-domain loop prevention. The active routing update mechanism implementation module is configured to, in a time slot in which the active routing update mechanism is used to assist the hierarchical convergence mechanism, perform active update on a routing table entry by a satellite, and receive and transmit a posteriori UPDATE messages for verification.
7. A computer system comprising a memory, a processor, and a computer program / instructions stored on the memory and executable on the processor, wherein, The computer program / instruction is executed by the processor to implement the steps of the active hierarchical border gateway protocol routing method for a low-orbit giant constellation according to any one of claims 1-5.
8. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to implement the steps of the active hierarchical border gateway protocol routing method for a low-orbit giant constellation according to any one of claims 1-5.