A protocol-independent satellite network multicast method

Abstract

This invention provides a protocol-independent satellite network multicast method. It employs an IGP unicast routing protocol to achieve network-wide route convergence, obtaining unicast routing tables for each satellite. The bit index forwarding table corresponding to each port is calculated using the unicast routing table, and multicast traffic forwarding is achieved based on the bit index forwarding table. This invention fills a gap in current satellite network multicast technology, alleviating bandwidth pressure on satellite networks. It avoids using traditional complex multicast protocols like PIM used on satellites, reducing bandwidth overhead and processor pressure caused by maintaining multicast groups and multicast trees. This invention does not require extending IS-IS or OSPFv3 protocol interactions with SID tags such as END.BIER; it only requires underlying support for standard IGP protocols, avoiding modifications to existing standard protocols and simplifying implementation. This invention can be applied not only to IP-based protocol stacks but also extended to non-IP protocol stacks, as long as the underlying layer supports dynamic routing protocols. This solution has the advantages of wide applicability and strong scalability.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and more specifically to a protocol-independent satellite network multicast method. Background Technology

[0002] In large-scale constellation networks, the demand for multicast in satellite communication is increasingly strong. Due to the dynamic changes in the topology of large-scale constellations, multicast technologies commonly used in the traditional Internet, such as Protocol Independent Multicast (PIM), are relatively complex and have weak scalability. Intermediate nodes need to maintain the multicast state of each stream, introducing additional control signaling into the network. Furthermore, as multicast traffic increases, the number of multicast trees in the network also increases, consuming significant resources such as memory and CPU, and also leading to problems such as prolonged convergence time after network failures. This makes it impossible to meet the low latency and high reliability requirements of some services, thus hindering deployment in large-scale satellite networks.

[0003] Therefore, a communication method is needed that can meet the multicast service requirements of large-scale constellations. Summary of the Invention

[0004] This invention addresses the problems of traditional multicast protocols, such as their relative complexity, weak scalability, high network overhead, low reliability, and difficulties in deployment and maintenance. Furthermore, the novel Bit Index Explicit Replication (BIERv6) multicast scheme cannot fully adapt to scenarios with limited onboard resources. This invention provides a protocol-independent satellite network multicast method. Based on the relatively fixed nature of satellite neighbor relationships, this method is a simplified Bit Index Explicit Replication (S-BIER) algorithm that significantly reduces satellite computational complexity and network overhead. It is independent of network protocol stack structures and fills the gap in multicast service requirements for large-scale constellations.

[0005] This invention provides a protocol-independent satellite network multicast method, comprising the following steps:

[0006] S1. Assign addresses to each satellite in the multicast network, and distinguish each satellite by its satellite number;

[0007] S2. Define the service multicast string. Each satellite occupies an independent and non-repeating position in the service multicast string. When the character position in the service multicast string is set to 1, it means that the satellite corresponding to the character position needs to receive the service multicast.

[0008] S3. Each satellite router runs the IGP protocol and exchanges link-state information or routing tables with each other.

[0009] S4. After completing the network-wide route convergence, each satellite node learns the next-hop routing table to reach other satellites in the network.

[0010] S5. Each satellite node performs bit mapping on the routing table and generates a bit index forwarding table for each interface. The bit index forwarding table refers to all destination satellites with the current interface as the next hop.

[0011] Determine if the topology has changed. If yes, return to step S3; otherwise, proceed to step S6.

[0012] S6. When a multicast source generates a multicast service, the basic header uses a multicast address negotiated on the ground. At least two independent multicast addresses are set for different satellite units. Each satellite converts the group members to which the service is to be sent into a service multicast string and carries it in the multicast service extension header.

[0013] S7. After receiving traffic, each multicast satellite determines whether it is multicast traffic. If not, it forwards the traffic in unicast mode according to the unicast routing table. If it is, it performs port mapping according to the bit index forwarding table, modifies the service multicast string, and continues to forward the multicast traffic to the next hop link. It continues to receive traffic, and a protocol-independent satellite network multicast method is completed.

[0014] In a preferred embodiment of the protocol-independent satellite network multicast method described in this invention, in step S1, it is determined whether the multicast uses the IP protocol suite. If so, the address prefix includes the satellite number; if not, each satellite can be mapped to a routing table, and other satellites can deduce their satellite identities through the routing table.

[0015] In a preferred embodiment of the protocol-independent satellite network multicast method described in this invention, in step S1, the address is an IPv6 address, which includes a prefix identifier and a host identifier.

[0016] A satellite number is a satellite identity ID represented by at least one bit, and satellite numbers are unique across the satellite network.

[0017] The protocol-independent satellite network multicast method described in this invention, as a preferred embodiment, includes a global routing prefix, a subnet ID, and an interface ID in the address; the method for embedding the satellite number into the address is to embed the satellite number into the subnet ID.

[0018] In a preferred embodiment of the protocol-independent satellite network multicast method described in this invention, in step S2, the total length of the service multicast string is greater than or equal to the total number of satellites in the constellation, and the length of the service multicast string is an integer multiple of 8.

[0019] In a preferred embodiment of the protocol-independent satellite network multicast method described in this invention, in step S2, the length of the service multicast string is greater than or equal to the number of satellites, with 1 bit representing 1 satellite.

[0020] In a preferred embodiment of the protocol-independent satellite network multicast method described in this invention, in step S5, the satellite converts the relationship between each routing table and the next-hop interface into the relationship between other satellites in the network and their corresponding next-hop interfaces. The satellites whose next-hop interfaces are selected are then selected and the corresponding positions in the string of the bit index forwarding table are set. After the satellite traverses all routing tables, the bit index forwarding table corresponding to each interface is generated.

[0021] In a preferred embodiment of the protocol-independent satellite network multicast method described in this invention, in step S7, after the multicast satellite receives the multicast traffic, the service multicast string in the multicast service extension header is extracted and ANDed with the bit index forwarding table of each interface.

[0022] Determine if the result of the AND operation is non-zero. If it is, then there are multicast members downstream of the current interface. A multicast traffic needs to be forwarded to the interface with a non-zero AND operation result, and the OR result of the service multicast strings forwarded by each interface should be a subset or the same as the service multicast strings in the received multicast traffic.

[0023] In a preferred embodiment of the protocol-independent satellite network multicast method described in this invention, when the satellite forwards multicast traffic, it modifies the service multicast string in the multicast service extension header to the result of an AND operation; if the flag corresponding to the local satellite is set in the service multicast string, then the flag is set to 0 during forwarding.

[0024] The protocol-independent satellite network multicast method described in this invention, as a preferred embodiment, involves each satellite recalculating its unicast routing table and updating its bit index forwarding table when the satellite network topology changes. When subsequent multicast traffic arrives, the traffic is forwarded according to the new bit index forwarding table.

[0025] This invention is a method for implementing large-scale constellation multicast communication based on S-BIER, belonging to the field of satellite mobile communication system technology.

[0026] This invention references a novel multicast scheme based on Bit Index Explicit Replication IPv6 encapsulation (BIERv6), a next-generation IPv6 technology. BIERv6 encapsulates the set of destination nodes for multicast packets as a bit string in the packet header. Intermediate nodes do not need to build multicast distribution trees or maintain flow states for each multicast stream; they only need to forward data based on the bit string in the packet header, reducing computational burden and network overhead. This invention simplifies the BIERv6 mechanism by designing a simplified bit index explicit replication algorithm (S-BIER) to address the relatively fixed nature of satellite neighbor relationships. This algorithm eliminates the need for label exchange via IGP protocols (such as IS-IS). Satellite transponders only need to calculate the bit index forwarding table based on the unicast routing table to distribute multicast services. Compared to traditional multicast routing protocols such as PIM, this mechanism significantly reduces satellite computational complexity and network overhead, and is independent of network protocol stack structures, thus filling the demand for multicast services in large-scale constellations.

[0027] The basic idea of ​​this invention is to use unicast routing protocols to detect network topology and generate bit index forwarding tables, thereby avoiding the additional bandwidth overhead and processor pressure on satellites due to the maintenance of multicast groups and multicast trees. Based on the terrestrial BIERv6 concept, multicast member information is carried in the message header, but there is no need to extend the dynamic routing protocol interaction label, reducing the pressure on on-board extension protocols, which has guiding significance for the development of satellite network multicast protocols.

[0028] This invention relates to a protocol-independent satellite network multicast scheme implementation method. The main steps include: (1) assigning addresses to each satellite in the multicast network, with each satellite distinguished by a satellite number, and the address prefix including the satellite number; (2) defining a service multicast string, the string length of which can be set, with each satellite occupying an independent and non-repeating position in the multicast string, and when certain positions in the service multicast string are set to 1, it indicates that the satellites corresponding to these positions need to receive a copy of the content; (3) based on step (2), each satellite router runs the IGP protocol and exchanges link state information or routing tables with each other; (4) after completing the network-wide route convergence through step (3), each satellite node can learn the next-hop routing table to reach other satellites in the network; (5) each satellite node performs bit mapping on the routing table generated in step (4) and provides it to the network. Each port generates a bit index forwarding table, which refers to all destination satellites with this interface as the next hop; (6) The multicast source generates multicast services, and the basic header uses the multicast address negotiated by the ground. For different satellite units, multiple independent multicast addresses can be set. Each satellite converts the group members to which the service is to be sent into a service multicast string and carries it in the multicast service extension header; (7) After receiving the traffic, each multicast satellite performs port mapping according to the bit index forwarding table, modifies the service multicast string, and continues to forward the traffic to the next hop link; (8) When the satellite network topology changes, each satellite recalculates the unicast routing table and updates the bit index forwarding table. When subsequent multicast traffic arrives, the traffic is forwarded according to the new bit index forwarding table. This method innovatively proposes an on-board multicast scheme, filling the gap in the current satellite network multicast technology and alleviating the bandwidth pressure of the satellite network. Compared with the traditional ground PIM multicast routing protocol, this method avoids the use of complex multicast protocols such as PIM on the satellite, reducing the bandwidth overhead and processor pressure caused by maintaining multicast groups and multicast trees. Compared to the BIERv6 solution for next-generation terrestrial networks, this method does not require extending IS-IS or OSPFv3 protocols to interact with SID tags such as END.BIER. It only requires underlying support for standard IGP protocols, avoiding modifications to existing standard protocols and simplifying implementation. Furthermore, this method can be applied not only to IP-based protocol stacks but also extended to non-IP protocol stacks, as long as the underlying layer supports dynamic routing protocols. It boasts advantages such as wide applicability and strong scalability.

[0029] The present invention has the following advantages:

[0030] (1) This invention innovatively proposes an on-board multicast scheme, which fills the gap in current satellite network multicast technology and alleviates the bandwidth pressure of satellite networks.

[0031] (2) This invention avoids the use of traditional complex multicast protocols such as PIM on satellites, reducing bandwidth overhead and processor pressure caused by maintaining multicast groups and multicast trees.

[0032] (3) Compared with the BIERv6 solution for next-generation terrestrial networks, this invention does not require the extension of IS-IS or OSPFv3 protocol interaction with SID tags such as END.BIER. It only requires the underlying layer to support the standard IGP protocol, thus avoiding modifications to the existing standard protocol and simplifying the implementation difficulty.

[0033] (4) This invention can be applied not only to IP-based protocol stack systems, but also to non-IP protocol stacks, as long as the underlying layer supports dynamic routing protocols. This solution has the advantages of wide applicability and strong scalability. Attached Figure Description

[0034] Figure 1 This is a flowchart of a protocol-independent satellite network multicast method. Detailed Implementation

[0035] 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.

[0036] Example 1

[0037] like Figure 1 As shown, a protocol-independent satellite network multicast method is presented. The technical solution of this invention is to provide a satellite network multicast scheme implementation method based on S-BIER. The IGP unicast routing protocol is used to complete network-wide route convergence to obtain the unicast routing table for each satellite. The bit index forwarding table corresponding to each port is calculated using the unicast routing table, and multicast traffic forwarding is implemented based on the bit index forwarding table.

[0038] The specific steps are as follows:

[0039] (1) Assign addresses to each satellite in the multicast network. Each satellite is distinguished by its satellite number, and the address prefix includes the satellite number.

[0040] (2) Define a service multicast string. The string length can be set. Each satellite occupies an independent and non-repeating position in the multicast string. When some positions in the service multicast string are set to 1, it means that the satellites corresponding to these positions need to receive a copy of the content.

[0041] (3) Based on step (2), each satellite router runs the IGP protocol and exchanges link state information or routing tables with each other;

[0042] (4) After the network route convergence is completed through step (3), each satellite node can learn the next-hop routing table to reach other satellites in the network;

[0043] (5) Each satellite node performs bit mapping on the routing table generated in step (4) and generates a bit index forwarding table for each port, which refers to all destination satellites with this interface as the next hop;

[0044] (6) When a multicast source generates a multicast service, the basic header uses the multicast address negotiated with the ground. For different satellite units, multiple independent multicast addresses can be set. Each satellite converts the group members to which the service is to be sent into a service multicast string and carries it in the multicast service extension header.

[0045] (7) After receiving the traffic, each multicast satellite performs port mapping according to the bit index forwarding table, modifies the service multicast string, and continues to forward the traffic to the next hop link;

[0046] (8) When the satellite network topology changes, each satellite recalculates the unicast routing table and updates the bit index forwarding table. When subsequent multicast traffic arrives, the traffic is forwarded according to the new bit index forwarding table.

[0047] Processing flow as follows Figure 1 As shown, the specific implementation is as follows:

[0048] (1) Assign addresses to each satellite in the multicast network. Each satellite is distinguished by its satellite number. If the IP protocol system is used, the address prefix includes the satellite number. If the non-IP system is used, each satellite can be mapped to a routing table. Other satellites can deduce the satellite identity through the routing table.

[0049] In this embodiment, the satellite number is a satellite identity ID represented by several bits, which is unique within the satellite network.

[0050] An address refers to an IPv6 address, but also broadly refers to an address that includes both a prefix identifier and a host identifier. Taking an IPv6 address as an example, its structure is shown in the table below:

[0051]

[0052] Global routing prefix: Assigned to an organization by the provider, typically at least 48 bits.

[0053] Subnet ID: Organizations can use subnet IDs to build local networks, typically up to the 64th bit.

[0054] Interface ID: Interface identifier used to identify a Host (device);

[0055] Prefix length: The number of bits used for routing in IPv6, including the global routing prefix and subnet ID;

[0056] Satellite ID embedded in address: The satellite ID is embedded in the subnet ID. It can be part of the subnet ID or be equivalent to the subnet ID. In this way, routing addressing is equivalent to satellite addressing. Given the satellite ID, the satellite address can also be mapped and routing can be performed.

[0057] (2) Define the service multicast string. The string length can be set. Each satellite occupies an independent and non-repeating position in the multicast string. When some positions in the service multicast string are set to 1, it means that the satellites corresponding to these positions need to receive a copy of the content. The total length of the multicast string should be greater than the total number of satellites in the constellation.

[0058] The service multicast string is a string of bits representing the satellite's identity, and its length is the same as the number of satellites. For example, if there are 1 to 8 satellites in the satellite network, 8 bits can be pre-defined to represent the meaning of each bit in the string, as shown in the table below:

[0059] bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

[0060] (3) Based on step (2), each satellite router runs the IGP protocol and exchanges link state information or routing tables with each other;

[0061] (4) After the network route convergence is completed through step (3), each satellite node can learn the next-hop routing table to reach other satellites in the network;

[0062] (5) Each satellite node performs bit mapping on the routing table generated in step (4) and generates a bit index forwarding table for each port. This table refers to all destination satellites with this interface as the next hop. Specifically, the satellite converts the relationship between each routing table and the next hop interface into the relationship between other satellites in the network and their corresponding next hop interfaces. It then filters out satellites with this interface as the next hop and sets the corresponding position in the bit index forwarding table string. After the satellite traverses all routing tables, the bit index forwarding table corresponding to each interface is generated.

[0063] (6) When a multicast source generates a multicast service, the basic header uses the multicast address negotiated with the ground. For different satellite units, multiple independent multicast addresses can be set. Each satellite converts the group members to which the service is to be sent into a service multicast string and carries it in the multicast service extension header.

[0064] (7) After receiving traffic, each multicast satellite first determines the traffic type. If it is unicast traffic, it forwards the traffic by looking up the unicast routing table. If it is multicast traffic, it extracts the service multicast string in the extended header and performs a bitwise AND operation with the bit index forwarding table of each interface. If the result is non-zero, it indicates that there are multicast members downstream of the interface and a copy of the multicast traffic needs to be forwarded to the interface. At the same time, in order to avoid the multicast traffic being transmitted repeatedly in the network, the satellite needs to modify the service multicast string in the extended header to the result of the bitwise AND operation when forwarding the traffic. If the flag corresponding to this satellite is set in the service multicast string, it should be set to 0 when forwarding to ensure that the OR result of the multicast service strings forwarded from each interface is a subset or the same as the service multicast strings in the received multicast traffic.

[0065] (8) When the satellite network topology changes, each satellite recalculates the unicast routing table and updates the bit index forwarding table of each interface. When subsequent multicast traffic arrives, the traffic is forwarded according to the new bit index forwarding table.

[0066] 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 protocol-independent satellite network multicast method, characterized in that: Includes the following steps: S1. Assign addresses to each satellite in the multicast network, and distinguish each satellite by its satellite number; S2. Define a service multicast string. Each satellite occupies an independent and non-repeating position in the service multicast string. When the character position in the service multicast string is set to 1, it indicates that the satellite corresponding to the character position needs to receive the service multicast. S3. Each satellite router runs the IGP protocol and exchanges link-state information or routing tables with each other. S4. After completing the network-wide route convergence, each satellite node learns the next-hop routing table to reach other satellites in the network. S5. Each satellite node performs bit mapping on the routing table and generates a bit index forwarding table for each interface. The bit index forwarding table refers to all destination satellites with the current interface as the next hop. Determine if the topology has changed. If yes, return to step S3; otherwise, proceed to step S6. S6. The multicast source generates multicast services. The basic header uses the multicast address negotiated by the ground. At least two independent multicast addresses are set for different satellite units. Each satellite converts the group members to which the service is to be sent into the service multicast string and carries it in the multicast service extension header. S7. After receiving traffic, each multicast satellite determines whether it is multicast traffic. If not, it forwards the traffic in unicast mode according to the unicast routing table. If so, port mapping is performed according to the bit index forwarding table, the service multicast string is modified, and multicast traffic is forwarded to the next hop link; traffic continues to be received, and a protocol-independent satellite network multicast method is completed.

2. The protocol-independent satellite network multicast method according to claim 1, characterized in that: In step S1, it is determined whether the multicast uses the IP protocol system. If so, the address prefix contains the satellite number; if not, each satellite can be mapped to a routing table, and other satellites can deduce the satellite identity through the routing table.

3. The protocol-independent satellite network multicast method according to claim 1, characterized in that: In step S1, the address is an IPv6 address, which includes a prefix identifier and a host identifier; The satellite number is a satellite identity ID represented by at least one bit, and the satellite number is unique within the satellite network.

4. The protocol-independent satellite network multicast method according to claim 3, characterized in that: The address includes a global routing prefix, a subnet ID, and an interface ID; the method for embedding the satellite number into the address is to embed the satellite number into the subnet ID.

5. The protocol-independent satellite network multicast method according to claim 1, characterized in that: In step S2, the total length of the service multicast string is greater than or equal to the total number of satellites in the constellation, and the length of the service multicast string is an integer multiple of 8.

6. The protocol-independent satellite network multicast method according to claim 5, characterized in that: In step S2, the length of the service multicast string is greater than or equal to the number of satellites, with 1 bit representing 1 satellite.

7. The protocol-independent satellite network multicast method according to claim 1, characterized in that: In step S5, the satellite converts the relationship between each routing table and the next-hop interface into the relationship between other satellites in the network and their corresponding next-hop interfaces. It then filters out satellites whose next-hop interface is the next hop and sets the corresponding position in the string of the bit index forwarding table. After the satellite traverses all routing tables, the bit index forwarding table corresponding to each interface is generated.

8. The protocol-independent satellite network multicast method according to claim 1, characterized in that: In step S7, after the multicast satellite receives the multicast traffic, it extracts the service multicast string from the multicast service extension header and performs a bitwise AND operation with the bit index forwarding table of each interface. Determine whether the result of the AND operation is non-zero. If it is, then there is a multicast member downstream of the current interface. A copy of the multicast traffic needs to be forwarded to the interface with a non-zero AND operation result, and the OR result of the service multicast strings forwarded by each interface should be a subset or the same as the service multicast strings in the received multicast traffic.

9. A protocol-independent satellite network multicast method according to claim 8, characterized in that: When forwarding the multicast traffic, the satellite modifies the service multicast string in the multicast service extension header to the result of the AND operation; if the flag corresponding to this satellite is set in the service multicast string, then the flag is set to 0 during forwarding.

10. A protocol-independent satellite network multicast method according to claim 1, characterized in that: When the satellite network topology changes, each satellite recalculates its unicast routing table and updates its bit index forwarding table. When subsequent multicast traffic arrives, it is forwarded according to the new bit index forwarding table.

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