A method for generating a satellite network multicast bit index forwarding table

Abstract

The application discloses a kind of satellite network bit index forwarding table efficient generation method, without extending field routing protocol, using the routing table generated by standard field routing protocol can generate bit index routing table, and then generate bit index forwarding table.First, based on the satellite identifier of this star spacecraft, and using the order of satellite identifier in constellation configuration table obtains BFR-ID, and then obtains bit mask, simultaneously, based on the satellite identifier obtains the End.BIER of this star BFR and the End.BIER of neighbor BFR.Then, based on the destination prefix of IGP routing table extraction second satellite identifier, and using the order of second satellite identifier in constellation configuration table obtains BFR-ID, and then obtains bit mask, simultaneously, based on second satellite identifier obtains the End.BIER of destination BFR.Next, based on the next hop IP address of IGP routing table extraction third satellite identifier, and based on third satellite identifier obtains the End.BIER of neighbor BFR.Finally, based on the standard method of BIRT generation BIFT generates BIFT.

Description

Technical Field

[0001] This invention relates to the field of multicast technology in satellite networks, and in particular to a method for generating a multicast bit index forwarding table in a satellite network. Background Technology

[0002] In satellite networks, efficient forwarding of multicast messages is a critical requirement. Traditional multicast technologies (such as protocol-independent multicast protocols) rely on complex multicast tree construction and maintenance, and require maintaining the state of each flow, resulting in high network operation and maintenance difficulty, which is particularly prominent in satellite networks with dynamically changing network topologies.

[0003] BIERv6 (Bit-Indexed Explicit Replication of IPv6) technology simplifies node processing by encapsulating the destination node set of multicast packets as a bit string in the packet header. This eliminates the need for intermediate nodes to build multicast trees and maintain flow states for each multicast stream. However, existing BIERv6 technologies typically require extensions to the Intra-Domain Routing Protocol (IGP), increasing implementation complexity and consuming significant storage and processing resources from network nodes. This poses a challenge for resource-efficient satellite network nodes. Summary of the Invention

[0004] The problem solved by this invention is to overcome the shortcomings of the prior art and provide a method for generating a multicast bit index forwarding table for satellite networks. This method does not require extending the intra-domain routing protocol, but directly uses the standard intra-domain routing protocol to generate the routing table, and uses information such as the constellation configuration table to convert it into a bit index routing table (BIRT), thereby generating a bit index forwarding table (BIFT).

[0005] The technical solution of this invention is: a method for generating a multicast bit index forwarding table for a satellite network, the method comprising the following steps:

[0006] S1. Use Bit Forwarding Router (BFR) to generate a satellite routing table for each node in the satellite network according to the standard Intra-Domain Routing Protocol (IGP).

[0007] S2. Based on the satellite's routing table and constellation configuration table, convert the satellite's routing table into a Bit Index Routing Table (BIRT).

[0008] S3. Convert the Bit Index Routing Table BIRT into the Bit Index Forwarding Table BIFT.

[0009] Preferably, the fields in the satellite's routing table include: destination prefix, prefix length, output interface, and next-hop IP address; wherein:

[0010] Destination prefix: All possible destination addresses reachable via this satellite;

[0011] Prefix length, used in conjunction with the destination prefix, indicates the number of significant digits in the destination prefix;

[0012] Output interface, indicating the router's output port number, where the router itself is represented by inloop0; the others are represented by numbers.

[0013] The next-hop IP address represents the IP address of the next-hop node, in the format: fe80::ccdd:c, where cc is the spacecraft identifier of the next-hop node, dd is the interface number of the next-hop node, and c is the onboard equipment number.

[0014] A single line of information in the satellite's routing table indicates:

[0015] After receiving the information that needs to be forwarded, the destination address in the information is parsed, and the router's transmission direction can be obtained by querying the satellite's routing table. The specific method is as follows:

[0016] Extract bits from the destination address of the information to be forwarded, from high to low, that are the same length as the prefix. Compare this bit length with the destination prefix. If the bits are the same as the valid bits of the destination prefix, then the output interface corresponding to the line containing the destination prefix is ​​used for forwarding, and the information is forwarded to the port corresponding to the next IP address.

[0017] Preferably, each node's intra-satellite subnet and satellite-to-ground link are configured with a global unicast address. Both the global unicast address and the link-local address embed the spacecraft identifier. The structure of the global unicast address is 2001:db8:0:aabb::c, where aa is the spacecraft identifier and bb is the interface number. The satellite-to-ground link is used as a direct connection route, and the inter-satellite link is configured only with a link-local address, without a global unicast address. The structure of the link-local address is fe80::aabb:c, where aa is the spacecraft identifier, bb is the interface number, c is 1 indicating an onboard router, and c is 2 to 9 for other values ​​representing onboard equipment.

[0018] Preferably, the fields in the Bit Index Routing Table (BIRT) include: Destination BFR-ID, Bit Mask, Destination BFR, Output Interface, and End.BIER Address of Neighboring BFRs;

[0019] Destination BFR-ID, representing a unique identifier for the destination BFR;

[0020] Bit mask, using bits set to 1 to represent the destination BFR-ID;

[0021] The destination BFR is the End.BIER address of the node, with the address format: 2001:db8:0:aa00:8000::1, where 0x8000 is the function field and belongs to the intra-satellite subnet segment; aa is the spacecraft identifier of the destination node;

[0022] Output interface, indicating the router's output port number, where the router itself is represented by inloop0; the others are represented by numbers.

[0023] The End.BIER address of the neighboring BFR is the global unicast address of the next node or device corresponding to the output interface. The address format is: 2001:db8:0:aa00:8000::1, where aa is the spacecraft identifier of the neighboring node.

[0024] Preferably, the fields in the satellite constellation configuration table include: node number and sequence number, wherein:

[0025] The node number serves as the spacecraft identifier for the satellite;

[0026] The sequence number indicates the order of the nodes in the constellation configuration table.

[0027] Preferably, the fields in the Bit Index Forwarding Table (BIFT) include: F-BM, output interface, and neighbor BFR;

[0028] F-BM is the forwarding bit mask;

[0029] Output interface, indicating the router's output port number, where the router itself is represented by inloop0; the others are represented by numbers.

[0030] The neighbor BFR is assigned the End.BIER address of the neighbor BFR, and the global unicast address of the next node or device corresponding to the output interface is given. The address format is: 2001:db8:0:aa00:8000::1, where aa is the spacecraft identifier of the neighbor node.

[0031] Preferably, the conversion method for the Bit Index Routing Table (BIRT) is as follows:

[0032] S1. Set the spacecraft identifier set SCIDarray to empty, i.e., SCIDarray = {}

[0033] S2. Obtain the spacecraft identifier of its own node, denoted as the first spacecraft identifier SCID1;

[0034] S3. Obtain the bit index routing table entry with the CPU inside the router as the destination address:

[0035] Query the satellite constellation configuration table to obtain the constellation configuration table sequence number corresponding to the first spacecraft identifier SCID1, and assign it to the destination BFR-ID, i.e.: BFR-ID = sequence number.

[0036] The bit mask is assigned the value 1 << (BFR-ID-1);

[0037] The output interface IF is assigned the value inloop0;

[0038] The neighbor End.BIER is assigned the value of the neighbor End.BIER corresponding to the first spacecraft identifier SCID1;

[0039] Add (BFR-ID, bitmask, IF, neighbor End.BIER) to the bit index routing table BIRT;

[0040] S4. Traverse the routing table entry i in the IGP routing table and repeat the following steps:

[0041] Extract the spacecraft identifier from the destination prefix of routing table entry i, and denote it as the second spacecraft identifier SCID2;

[0042] If the second spacecraft identifier SCID2 ≠ the first spacecraft identifier SCID1 and the second spacecraft identifier SCID2 is not in the SCIDarray, then

[0043] Obtain the serial number of the second spacecraft identifier SCID2 in the constellation configuration table and assign it to the destination BFR-ID, that is: BFR-ID = serial number;

[0044] The bit mask is assigned the value 1 << (BFR-ID-1);

[0045] The output interface IF is assigned the value of the output interface IF corresponding to the routing table entry i.

[0046] Obtain the third spacecraft identifier SCID3 from the next-hop IP address of routing table entry i;

[0047] The neighbor End.BIER is assigned the value of the neighbor End.BIER corresponding to the third spacecraft identifier SCID3;

[0048] Add (BFR-ID, bitmask, IF, neighbor End.BIER) to the bit index routing table BIRT;

[0049] Add the second spacecraft identifier SCID2 to SCIDarray.

[0050] Preferably, the End.BIER address structure of the Bit Forwarding Router (BFR) is 2001:db8:0:aa00:8000::c, where 0x8000 is the function field. The neighbor spacecraft identifier is extracted from the "next-hop IP address" in the satellite's routing table and substituted into aa to obtain the neighbor's End.BIER.

[0051] Preferably, the BIFT generation process is as follows:

[0052] Write the output interface corresponding to the output interface in the Bit Index Routing Table BIRT into the output interface field of the Bit Index Routing Table BIFT. Merge entries with the same output interface in the Bit Index Routing Table BIRT by performing a bitwise AND operation on each bit mask and writing it into the forwarding bit mask F-BM corresponding to the output interface in the Bit Index Routing Table. Then write the neighbor BFR corresponding to the output interface into the neighbor BFR field of the BIFT.

[0053] The advantages of this invention compared to the prior art are:

[0054] (1) The method given in this invention can generate BIFT based on the standard IGP protocol without extending the standard IGP protocol, thus making it simpler.

[0055] (2) The method provided by this invention can utilize the dynamic adaptation process of network topology changes by the standard IGP protocol and automatically update BIFT according to the changes in the IGP routing table. Attached Figure Description

[0056] Figure 1 This is the satellite network node structure according to an embodiment of the present invention.

[0057] Figure 2 This is a satellite network multicast scenario according to an embodiment of the present invention. Detailed Implementation

[0058] The exemplary embodiments of the present invention will be described in detail below with reference to examples. It should be understood that the embodiments shown and described in the figures are merely exemplary and are intended to illustrate the principles and spirit of the present invention, and are not intended to limit the scope of the present invention.

[0059] This invention provides a method for generating a bit index forwarding table based on an intra-domain routing protocol (IGP) routing table. This method takes advantage of the fact that each node in a satellite network is a bit forwarding router (BFR) and that the node IP address embeds the spacecraft identifier. It does not require extension of the intra-domain routing protocol, but directly uses the standard intra-domain routing protocol to generate the routing table, and uses information such as the constellation configuration table to convert it into a bit index routing table (BIRT), and then generates a bit index forwarding table (BIFT).

[0060] The following is a detailed description of each step of the present invention:

[0061] (1) Node configuration

[0062] A satellite network is a network system that uses satellite platforms to acquire, process, transmit, and distribute space information in real time. As an extension of terrestrial networks, satellite networks need to support interconnection and interoperability with terrestrial networks to form an integrated space-ground network.

[0063] A satellite network consists of multiple satellites, each acting as a node in the network. Each node is uniquely assigned a spacecraft identifier. A typical internal structure of a satellite network node is as follows: Figure 2 As shown. Each node contains an intra-satellite subnet consisting of onboard payloads and onboard routers, while also forming an inter-satellite subnet with other satellites and communicating with ground networks via a satellite-to-ground subnet. The onboard payload includes an onboard processor and several onboard devices. Each onboard device contains only one port, which connects to one port of the onboard router via an onboard switch. The onboard router also includes one port for connecting to the internal CPU (denoted as inloop0), m ports for inter-satellite links, and n ports for satellite-to-ground links, where m and n are greater than or equal to 1.

[0064] This invention uses an IPv6 addressing method with embedded spacecraft identifiers for addressing. The IPv6 addressing method is node-centric and supports addressing of inter-satellite links, satellite-to-ground links, and onboard equipment.

[0065] Each node's intra-satellite subnet and satellite-to-ground link are configured with a global unicast address. Both the global unicast address and the link-local address embed the spacecraft identifier. The structure of the global unicast address is 2001:db8:0:aabb::c, where 'aa' is the spacecraft identifier and 'bb' is the interface number. The satellite-to-ground link is used as a direct connection route. Inter-satellite links are configured only with link-local addresses, not global unicast addresses. The structure of the link-local address is fe80::aabb:c, where 'aa' is the spacecraft identifier, 'bb' is the interface number, and 'c' is the onboard device number.

[0066] Each node's Intra-Domain Routing Protocol (IGP) only publishes the intra-satellite subnet prefix. All nodes are Bit Forwarding Routers (BFRs). The End.BIER address structure of a BFR is 2001:db8:0:aa00:8000::c, where 0x8000 is the function field, belonging to the intra-satellite subnet segment.

[0067] (2) Generation of Intradomain Routing Protocol (IGP) Routing Table

[0068] Routing tables are generated in satellite networks using standard intra-domain routing protocols (IGPs), which indicate the direction in which satellite nodes forward information.

[0069] The routing table contains information such as destination prefix, prefix length, output interface, and next-hop IP address. An example of the format is shown in Table 1.

[0070] Table 1 Example of routing table format

[0071] 2001:db8:0:aabb::1 64 1 fe80::ccdd:1 … … … …

[0072] Destination prefix: All possible destination addresses reachable via this satellite;

[0073] Prefix length, used in conjunction with the destination prefix, indicates the number of significant digits in the destination prefix;

[0074] Output interface, indicating the router's output port number, where the router itself is represented by inloop0; the others are represented by numbers.

[0075] The next-hop IP address represents the IP address of the next-hop node, in the format: fe80::ccdd:c, where cc is the spacecraft identifier of the next-hop node, dd is the interface number of the next-hop node, c is 1 to indicate an onboard router, and c is 2 to 9 to indicate other values, representing onboard equipment.

[0076] A single line of information in the satellite's routing table indicates:

[0077] After receiving the information that needs to be forwarded, the destination address in the information is parsed, and the router's transmission direction can be obtained by querying the satellite's routing table. The specific method is as follows:

[0078] Extract bits from the destination address of the information to be forwarded, from high to low, that are the same length as the prefix. Compare this bit length with the destination prefix. If the bits are the same as the valid bits of the destination prefix, then the output interface corresponding to the line containing the destination prefix is ​​used for forwarding, and the information is forwarded to the port corresponding to the next IP address.

[0079] (3) BIRT generation

[0080] 1) Bit Index Routing Table (BIRT) Structure

[0081] A Bit Indexed Routing Table (BIRT) typically contains the destination BFR-ID, bitmask, destination BFR, output interface, and the End.BIER address of the neighboring BFRs, as shown in Table 2.

[0082] Table 2. Example of Bit Indexed Routing Table (BIRT) format.

[0083] 1 ...0001 2001:db8:0:aa00:8000::1 1 2001:db8:0:cc00:8000::1 … … … … …

[0084] in:

[0085] Destination BFR-ID, representing a unique identifier for the destination BFR;

[0086] Bit mask, using bits set to 1 to represent the destination BFR-ID;

[0087] The destination BFR is the End.BIER address of the node, with the address format: 2001:db8:0:aa00:8000::1, where 0x8000 is the function field and belongs to the intra-satellite subnet segment; aa is the spacecraft identifier of the destination node;

[0088] Output interface, indicating the router's output port number, where the router itself is represented by inloop0; the others are represented by numbers.

[0089] The End.BIER address of the neighboring BFR is the global unicast address of the next node or device corresponding to the output interface. The address format is: 2001:db8:0:aa00:8000::1, where aa is the spacecraft identifier of the neighboring node.

[0090] 2) BIFT structure

[0091] The Bit Index Forwarding Table (BIFT) includes F-BM (Forwarding Bit Mask), output interface, neighbor BFR, etc., and the format example is shown in Table 2:

[0092] Table 2. Example of Bit Index Forwarding Table (BIFT) format

[0093] ...0001 1 2001:db8:0:ccdd::1 … … …

[0094] 3) Zodiac Sign Configuration Table Structure

[0095] The constellation configuration table structure is a list of spacecraft identifiers. The fields in the satellite constellation configuration table include: node number and sequence number, as shown in Table 4 below; where:

[0096] The node number serves as the spacecraft identifier for the satellite;

[0097] The sequence number indicates the order of the nodes in the constellation configuration table.

[0098] The satellite can obtain the serial number of the spacecraft identifier in the constellation configuration table based on the spacecraft identifier. This serial number will serve as the BFR-ID of the satellite to which the spacecraft identifier belongs.

[0099] Table 4. Satellite Constellation Configuration Structure

[0100] scid1 1 scid2 2 … …

[0101] 4) BIFT generation process

[0102] The satellite first generates a Bit Indexed Routing Table (BIRT) based on the IGP routing table and constellation configuration table, and then converts the BIRT into a BIFT according to standard methods.

[0103] The process of generating BIRT is as follows:

[0104] S1. Set the spacecraft identifier set SCIDarray to empty, i.e., SCIDarray = {}

[0105] S2. Obtain the spacecraft identifier of its own node, denoted as the first spacecraft identifier SCID1;

[0106] S3. Obtain the bit index routing table entry with the CPU inside the router as the destination address:

[0107] Query the satellite constellation configuration table to obtain the constellation configuration table sequence number corresponding to the first spacecraft identifier SCID1, and assign it to the destination BFR-ID, i.e.: BFR-ID = sequence number.

[0108] The bit mask is assigned the value 1 << (BFR-ID-1);

[0109] The output interface IF is assigned the value inloop0;

[0110] The neighbor End.BIER is assigned the value of the neighbor End.BIER corresponding to the first spacecraft identifier SCID1;

[0111] Add (BFR-ID, bitmask, IF, neighbor End.BIER) to the bit index routing table BIRT;

[0112] S4. Traverse the routing table entry i in the IGP routing table and repeat the following steps:

[0113] Extract the spacecraft identifier from the destination prefix of routing table entry i, and denote it as the second spacecraft identifier SCID2;

[0114] If the second spacecraft identifier SCID2 ≠ the first spacecraft identifier SCID1 and the second spacecraft identifier SCID2 is not in the SCIDarray, then

[0115] Obtain the serial number of the second spacecraft identifier SCID2 in the constellation configuration table and assign it to the destination BFR-ID, that is: BFR-ID = serial number;

[0116] The bit mask is assigned the value 1 << (BFR-ID-1);

[0117] The output interface IF is assigned the value of the output interface IF corresponding to the routing table entry i.

[0118] Obtain the third spacecraft identifier SCID3 from the next-hop IP address of routing table entry i;

[0119] The neighbor End.BIER is assigned the value of the neighbor End.BIER corresponding to the third spacecraft identifier SCID3;

[0120] Add (BFR-ID, bitmask, IF, neighbor End.BIER) to the bit index routing table BIRT.

[0121] Add the second spacecraft identifier SCID2 to SCIDarray.

[0122] The above steps are summarized as follows:

[0123] Based on the local satellite spacecraft identifier, and using the order of the local satellite spacecraft identifier (first spacecraft identifier) ​​in the constellation configuration table to obtain the BFR-ID, the bit mask is obtained. At the same time, based on the spacecraft identifier, the End.BIER of the local satellite BFR and the End.BIER of the neighboring BFR are obtained.

[0124] The second spacecraft identifier is extracted from the destination prefix of the IGP routing table, and the BFR-ID is obtained by using the order of the second spacecraft identifier in the constellation configuration table. Then, the bit mask is obtained. At the same time, the End.BIER of the destination BFR is obtained based on the second spacecraft identifier.

[0125] The third spacecraft identifier is extracted from the next-hop IP address in the IGP routing table, and the End.BIER of the neighboring BFR is obtained based on the third spacecraft identifier.

[0126] Three conversion processes can be defined to extract the SCID from the IPv6 address and generate the End.BIER based on the SCID:

[0127] Procedure 1 (Extracting SCID from IPv6 Global Unicast Address): SCID = C IPG-SCID (IP);

[0128] Procedure 2 (Extracting SCID from IPv6 Link-Local Address): SCID = C IPL-SCID (IP);

[0129] Process 3 (Generating End.BIER based on SCID): End.BIER = C SCID-End.BIER (SCID);

[0130] The method for generating the neighbor End.BIER corresponding to the spacecraft identifier (generating End.BIER based on SCID) is as follows:

[0131] By extracting the neighbor spacecraft identifier from the "next-hop IP address" in the satellite's routing table and substituting it into aa, the neighbor End.BIER can be obtained.

[0132] After generating the BIRT based on the above process, the BIFT is generated using the standard process of generating the BIFT based on the BIRT. The output interface corresponding to the output interface in the bit index routing table BIRT is written into the output interface field of the bit index routing table BIFT. The entries with the same output interface in the bit index routing table BIRT are merged by performing a bitwise AND operation on each bit mask and writing it into the forwarding bit mask F-BM corresponding to the output interface in the bit index routing table. Then, the neighbor BFR corresponding to the output interface is written into the neighbor BFR field of the BIFT.

[0133] Example:

[0134] assumed Figure 1 This is an example of a satellite network multicast scenario. For ease of description, Figure 1 Assume there are 9 satellite nodes, each identified by a spacecraft numbered 1-9. Each satellite is configured with an intra-satellite subnet, numbered 0; 4 inter-satellite links, numbered 1, 2, 3, and 4 respectively (front, back, left, and right); and 1 satellite-to-ground link, numbered 5.

[0135] In a specific embodiment of the present invention, the interface number of the router connecting to the switch is 0, the port number connecting to the internal CPU is denoted as inloop0, the ports connecting to the inter-satellite link are 1 to 4, and the port connecting to the satellite-to-ground link is 5.

[0136] For intra-satellite subnets, bb is set to 0, 1 to 4 represent satellite-to-ground links; 5 is the inter-satellite link interface number (corresponding to the router's port number); c is 1 to represent an onboard router; c is 2 to 9 for other values, representing onboard equipment.

[0137] Each satellite is configured with a loopback address, which embeds the spacecraft identifier. Each satellite's inter-satellite link is assigned only a link-local address, not a global unicast address.

[0138] Each satellite's space-to-ground link is configured with a global unicast address, but as a directly connected route, the IGP does not broadcast it outwards. It should be understood that the number of satellites, the number of inter-satellite links, and the number of space-to-ground links are merely exemplary and intended to illustrate the principles and spirit of the invention, and not to limit the scope of the invention.

[0139] The routing table for satellite 5 is shown in the table below.

[0140] Table 3 Satellite 5 Routing Table

[0141]

[0142] The structure of the satellite constellation configuration table is shown in Table 4.

[0143] Table 4. Satellite Constellation Configuration Structure

[0144]

[0145]

[0146] For satellite 5, it first generates BIRT based on the routing table as follows:

[0147] Table 5 shows an example of the Bit Indexed Routing Table (BIRT) format:

[0148] 5 0 0001 0000 2001:db8:0:0500:8000::1 inloop0 :: 1 0 0000 0001 2001:db8:0:0100:8000::1 1 2001:db8:0:0200:8000::1 2 0 0000 0010 2001:db8:0:0200:8000::1 1 2001:db8:0:0200:8000::1 3 0 0000 0100 2001:db8:0:0300:8000::1 1 2001:db8:0:0200:8000::1 4 0 0000 1000 2001:db8:0:0400:8000::1 3 2001:db8:0:0400:8000::1 6 0 0010 0000 2001:db8:0:0600:8000::1 4 2001:db8:0:0600:8000::1 7 0 0100 0000 2001:db8:0:0700:8000::1 3 2001:db8:0:0400:8000::1 8 0 1000 0000 2001:db8:0:0800:8000::1 2 2001:db8:0:0800:8000::1 9 1 0000 0000 2001:db8:0:0900:8000::1 4 2001:db8:0:0600:8000::1

[0149] Next, Satellite 5 generates the BIFT according to the standard BIRT method, and the BIFT is as follows:

[0150] Table 6. Example of Bit Indexed Routing Table (BIFT) format

[0151] 0 0001 0000 inloop0 :: 0 0000 0111 1 2001:db8:0:0200:8000::1 0 1000 0000 2 2001:db8:0:0800:8000::1 0 0100 1000 3 2001:db8:0:0400:8000::1 1 0010 0000 4 2001:db8:0:0600:8000::1

[0152] In summary, this invention does not require extending the intra-domain routing protocol; the routing table generated using the standard intra-domain routing protocol can be used to generate the bit-indexed routing table, and then the bit-indexed forwarding table.

[0153] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for generating a multicast bit index forwarding table for a satellite network, characterized in that... Includes the following steps: S1. Use Bit Forwarding Router (BFR) to generate a satellite routing table for each node in the satellite network according to the standard Intra-Domain Routing Protocol (IGP). S2. Based on the satellite's routing table and constellation configuration table, convert the satellite's routing table into a Bit Index Routing Table (BIRT). S3. Convert the Bit Index Routing Table BIRT into the Bit Index Forwarding Table BIFT.

2. The method for generating a satellite network multicast bit index forwarding table according to claim 1, characterized in that, The fields in the satellite's routing table include: destination prefix, prefix length, output interface, and next-hop IP address; among which: Destination prefix: All possible destination addresses reachable via this satellite; Prefix length, used in conjunction with the destination prefix, indicates the number of significant digits in the destination prefix; Output interface, indicating the router's output port number, where the router itself is represented by inloop0; the others are represented by numbers. The next-hop IP address represents the IP address of the next-hop node, in the format: fe80::ccdd:c, where cc is the spacecraft identifier of the next-hop node, dd is the interface number of the next-hop node, and c is the onboard equipment number. A single line of information in the satellite's routing table indicates: After receiving the information that needs to be forwarded, the destination address in the information is parsed, and the router's transmission direction can be obtained by querying the satellite's routing table. The specific method is as follows: Extract bits from the destination address of the information to be forwarded, from high to low, that are the same length as the prefix. Compare this bit length with the destination prefix. If the bits are the same as the valid bits of the destination prefix, then the output interface corresponding to the line containing the destination prefix is ​​used for forwarding, and the information is forwarded to the port corresponding to the next IP address.

3. The method for generating a satellite network multicast bit index forwarding table according to claim 1, characterized in that, Each node's intra-satellite subnet and satellite-to-ground link are configured with a global unicast address. Both the global unicast address and the link-local address embed the spacecraft identifier. The structure of the global unicast address is 2001:db8:0:aabb::c, where 'aa' is the spacecraft identifier and 'bb' is the interface number. The satellite-to-ground link is used as a direct connection route. Inter-satellite links are configured only with link-local addresses, not global unicast addresses. The structure of the link-local address is fe80::aabb:c, where 'aa' is the spacecraft identifier, 'bb' is the interface number, and 'c' = 1 indicates an onboard router; 'c' = 2 to 9 represents other values ​​indicating onboard equipment.

4. The method for generating a satellite network multicast bit index forwarding table according to claim 2, characterized in that, The fields in the Bit Index Routing Table (BIRT) include: Destination BFR-ID, Bit Mask, Destination BFR, Output Interface, and End.BIER address of the neighboring BFR. Destination BFR-ID, representing the unique identifier of the destination BFR; Bit mask, using bits set to 1 to represent the destination BFR-ID; The destination BFR is the End.BIER address of the node, with the address format: 2001:db8:0:aa00:8000::1, where 0x8000 is the function field and belongs to the intra-satellite subnet segment; aa is the spacecraft identifier of the destination node; Output interface, indicating the router's output port number, where the router itself is represented by inloop0; the others are represented by numbers. The End.BIER address of the neighboring BFR is the global unicast address of the next node or device corresponding to the output interface. The address format is: 2001:db8:0:aa00:8000::1, where aa is the spacecraft identifier of the neighboring node.

5. A method for generating a satellite network multicast bit index forwarding table according to claim 3, characterized in that, The fields in the satellite constellation configuration table include: node number and sequence number, where: The node number serves as the spacecraft identifier for the satellite; The sequence number indicates the order of the nodes in the constellation configuration table.

6. A method for generating a satellite network multicast bit index forwarding table according to claim 4, characterized in that, The fields in the Bit Index Forwarding Table (BIFT) include: F-BM, Output Interface, and Neighboring Frame (BFR). F-BM is the forwarding bit mask; Output interface, indicating the router's output port number, where the router itself is represented by inloop0; the others are represented by numbers. The neighbor BFR is assigned the End.BIER address of the neighbor BFR, and the global unicast address of the next node or device corresponding to the output interface is given. The address format is: 2001:db8:0:aa00:8000::1, where aa is the spacecraft identifier of the neighbor node.

7. A method for generating a satellite network multicast bit index forwarding table according to claim 6, characterized in that, The conversion method for the Bit Index Routing Table (BIRT) is as follows: S1. Set the spacecraft identifier set SCIDarray to empty, i.e., SCIDarray = {} S2. Obtain the spacecraft identifier of its own node, denoted as the first spacecraft identifier SCID1; S3. Obtain the bit index routing table entry with the CPU inside the router as the destination address: Query the satellite constellation configuration table to obtain the constellation configuration table sequence number corresponding to the first spacecraft identifier SCID1, and assign it to the destination BFR-ID, i.e.: BFR-ID = sequence number. The bit mask is assigned the value 1 << (BFR-ID-1); The output interface IF is assigned the value inloop0; The neighbor End.BIER is assigned the value of the neighbor End.BIER corresponding to the first spacecraft identifier SCID1; Add (BFR-ID, bitmask, IF, neighbor End.BIER) to the bit index routing table BIRT; S4. Traverse the routing table entry i in the IGP routing table and repeat the following steps: Extract the spacecraft identifier from the destination prefix of routing table entry i, and denote it as the second spacecraft identifier SCID2; If the second spacecraft identifier SCID2 ≠ the first spacecraft identifier SCID1 and the second spacecraft identifier SCID2 is not in the SCIDarray, then Obtain the serial number of the second spacecraft identifier SCID2 in the constellation configuration table and assign it to the destination BFR-ID, that is: BFR-ID = serial number; The bit mask is assigned the value 1 << (BFR-ID-1); The output interface IF is assigned the value of the output interface IF corresponding to the routing table entry i. Obtain the third spacecraft identifier SCID3 from the next-hop IP address of routing table entry i; The neighbor End.BIER is assigned the value of the neighbor End.BIER corresponding to the third spacecraft identifier SCID3; Add (BFR-ID, bitmask, IF, neighbor End.BIER) to the bit index routing table BIRT; Add the second spacecraft identifier SCID2 to SCIDarray.

8. A method for generating a satellite network multicast bit index forwarding table according to claim 7, characterized in that, The End.BIER address structure of the Bit Forwarding Router (BFR) is 2001:db8:0:aa00:8000::c, where 0x8000 is the function field. The neighbor spacecraft identifier is extracted from the "next-hop IP address" in the satellite's routing table and substituted into aa to obtain the neighbor's End.BIER.

9. A method for generating a satellite network multicast bit index forwarding table according to claim 1, characterized in that, The BIFT generation process is as follows: Write the output interface corresponding to the output interface in the Bit Index Routing Table BIRT into the output interface field of the Bit Index Routing Table BIFT. Merge entries with the same output interface in the Bit Index Routing Table BIRT by performing a bitwise AND operation on each bit mask and writing it into the forwarding bit mask F-BM corresponding to the output interface in the Bit Index Routing Table. Then write the neighbor BFR corresponding to the output interface into the neighbor BFR field of the BIFT.

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