CN117041143A - Satellite data forwarding method and system based on label switching technology - Google Patents

Abstract

The invention discloses a satellite data forwarding method and a system based on a label switching technology, comprising IP and MAC address learning of a source node and a destination node; MAC, type, CRC removal of the source node; the intermediate node forwards the extended AOS frame based on label switching; MAC, type, CRC of the destination node. The invention designs the tag field, realizes the transmission of multiple types of user services, avoids unnecessary data frame disassembly-comparison-re-framing process, and improves the data forwarding efficiency; designing an MAC address replacement method based on an NDP protocol, removing redundant data, and improving data transmission efficiency; and an independent overhead field is designed to transmit management control information, so that the conflict between user service and management control information is avoided.

Description

Satellite data forwarding method and system based on label switching technology

Technical Field

The invention relates to the technical field of satellite optical networks, in particular to a satellite data forwarding method and system based on a label switching technology.

Background

In recent years, with the explosive growth of the demand for long-distance data communication services, satellite networks adopting microwave communication technology face the problems of limited frequency band resources, weak transmission direction, small transmission rate and the like. Because laser has advantages of shorter wavelength, wider frequency band, high transmission rate and the like compared with microwaves, a novel satellite optical network (Satellite Optical Networks, SON) can be constructed by utilizing a space free optical link (Free Space Optical, FSO) to replace a microwave link. The satellite optical network has the characteristics of high confidentiality, electromagnetic interference resistance, large bandwidth, high speed and low power consumption. Current satellite optical networks employ spatial data systems consultation committee (Consultative Committee for Space Data Systems, CCSDS) standard advanced on-orbit system (Advanced Orbiting Systems, AOS) data link layer protocols for data forwarding. The standard CCSDS AOS data link layer protocol carries traffic through a fixed length data unit (i.e., standard AOS frame), and although "AOS Space Data Link protocol, ccsds732.0-B-4" provides a recommended processing flow for different types of data transmission, the current implementation method still refers to the ethernet communication protocol of the terrestrial communication network, and ethernet IP data is filled into the transmission frame data field of the AOS frame at the source edge node for transmission. And then, the received AOS frame is taken out of the transmission frame data field at the intermediate exchange node, and is compared with the IP route forwarding table, so that the port from which the AOS frame should be forwarded to the next-hop satellite node is judged, and the above process is repeated until the user service destination end. This method of de-framing-comparing-re-framing IP data makes the forwarding approach inefficient and unable to support other types of user traffic transmissions, such as bit stream traffic (Bitstream Service), virtual channel access traffic (Virtual Channel Access Service), and Packet traffic (Packet Service). When the user service is IP data, the effective content thereof is an "IP Payload" (Payload) field, and the contents of 16bytes in total such as "destination MAC" (6 bytes), "source MAC" (6 bytes), "Type" (2 bytes) and "redundancy check (CRC)" (4 bytes) can be transmitted in the transmission frame data field (Transfer frame data field) of the AOS frame after the source end of the user service is removed, and the contents are sent to the user terminal after the destination end of the user service is added through MAC address learning without the judgment of the redundant field at the intermediate node. The management control information and the user traffic are transmitted using a transmission frame data field in the standard CCSDS AOS data link layer protocol, and the management control information (or the user traffic) cannot be transmitted when the user traffic (or the management control information) is excessive. Therefore, the current satellite optical network adopts CCSDS AOS data link layer protocol to forward data, and mainly has the following problems: the routing forwarding mechanism based on the destination IP address in the CCSDS AOS data link layer protocol results in lower user traffic transmission efficiency, while the transmission of redundant user traffic (e.g., MAC address) in the transmission frame data field (Transfer frame data field) of the AOS frame reduces user traffic transmission efficiency.

Disclosure of Invention

The invention aims to solve the problem that the transmission efficiency of user service is lower when the conventional satellite optical network adopts a standard CCSDS AOS data link layer protocol for data forwarding, and provides a satellite data forwarding method and system based on a label switching technology.

In order to solve the problems, the invention is realized by the following technical scheme:

a satellite data forwarding method based on label switching technology comprises the following steps:

when the route of the satellite optical network converges, each satellite in the satellite optical network generates a label forwarding table for IPv6 services of different source IP addresses and destination IP addresses between user terminals;

the satellite of the source node receives the IPv6 service sent by the user terminal of the sending end through the user port; then, IPv6 payload after removing source MAC address, destination MAC address, type and CRC check value from IPv6 service is encapsulated into transmission frame data domain of extended AOS frame; meanwhile, according to the destination IP address, obtaining a label after matching in a label forwarding table of the current satellite, and filling the obtained label into a label field of a transmission frame insertion field of an extended AOS frame; then transmitting the extended AOS frame code to a satellite of a next hop node of the current satellite through a corresponding baseband port;

after decoding the extended AOS frame, the satellite of the intermediate node firstly takes out the label from the label domain of the transmission frame insertion domain of the extended AOS frame, updates the label after matching the label forwarding table of the current satellite, and fills the updated label into the label domain of the transmission frame insertion domain of the extended AOS frame; then transmitting the extended AOS frame code to a satellite of a next hop node of the current satellite through a corresponding baseband port;

after the satellite of the destination node decodes the extended AOS frame, firstly, the label in the label domain of the transmission frame insertion domain of the extended AOS frame is removed; decapsulating the IPv6 payload from the extended AOS frame transmission frame data domain, and re-forming the IPv6 service by taking the IPv6 payload and the MAC address of the current satellite as a source MAC address and taking the MAC address of the user terminal as a receiving end as a destination MAC address, type and CRC check value load; and then the IPv6 service is sent to the user terminal as the receiving end through the user port.

The fields of the extended AOS frame are a transmission frame head, a transmission frame insertion field, a transmission frame data field and a transmission frame tail in sequence; wherein the transport frame insertion field contains an extended control field that further contains a tag field and a data communication network field.

The data communication network domain encapsulates a management control information frame, and each field of the management control information frame is sequentially: information frame header, destination node ID, source node ID, information frame acknowledgement, information frame total length, information frame sequence number, information frame output port number, information frame input port number, information frame payload, cyclic Redundancy Check (CRC) and information frame tail.

The satellite data forwarding method further includes the step of inserting the transmission frame of the AOS frame into the domain data communication network domain to send and receive management control information, that is:

the method comprises the steps of sending a satellite of an extended AOS frame, dividing complete management control information into n pieces of management control information, packaging the n pieces of management control information into n pieces of management control information frames, and respectively filling the n pieces of management control information frames into a data communication network domain of a transmission frame insertion domain of the extended AOS frame;

receiving satellites of extended AOS frames, sequentially receiving n continuous extended AOS frames, and extracting management control information frames from a data communication network domain of a transmission frame insertion domain of the n extended AOS frames; then, the n management control information frames are unpacked to obtain n segmented management control information, and the n segmented management control information is recombined into complete management control information according to the information frame sequence number of the management control information frames; calculating the cyclic redundancy check of the management control information frame from the information frame header to the information frame payload, and comparing the calculated cyclic redundancy check value with the cyclic redundancy check value of the received management control information frame: if the management control information frames are the same, the management control information frames are indicated to be normal without error codes; otherwise, discarding the management control information frame and notifying the satellite retransmission of the extended AOS frame;

wherein n is a set value.

In the satellite data forwarding method, when the update label of the satellite of the intermediate node is a set termination label, the satellite of the next hop node is the satellite of the target node; otherwise, the satellite of the next hop node is the satellite of the intermediate node.

The satellite data forwarding method further comprises the step that each satellite in the satellite optical network finishes the IP and MAC address learning of the user terminal connected with the satellite optical network through a neighbor discovery protocol, wherein the IP and MAC address learning is divided into passive address analysis learning and active address analysis learning;

the process of passive address resolution learning of IP and MAC addresses is specifically: when the satellite receives a neighbor request message sent by the user terminal from the user port, the satellite checks the source IP and the MAC address in the neighbor request message: if the source IP and the MAC address are not in the neighbor cache table, respectively storing the source IP and the MAC address in the neighbor cache table; if the source IP and the MAC address exist in the neighbor cache table, the MAC address of a port directly connected with the satellite and the user terminal is used as the source MAC address in the neighbor advertisement message, and the MAC address of the user terminal is used as the destination MAC address; then the neighbor advertisement message is sent to the user terminal to complete passive address resolution;

the IP and MAC address active address analysis learning process specifically comprises the following steps: the satellite extracts the destination IP address in the IPv6 service, and searches whether the user terminal corresponding to the destination IP address exists in the neighbor cache table: if not, the satellite sends a neighbor request message to the user port to acquire the IP and MAC address of the user terminal, and after acquiring the IP and MAC address of the user terminal, the IPv6 service is sent to the user terminal through the corresponding user port; if yes, the destination node directly sends the IPv6 service to the user terminal through the corresponding user port.

A satellite data forwarding system based on a label switching technology comprises 1 satellite of a source node, at least 1 satellite of an intermediate node and a satellite of a destination node; the label forwarding table of IPv6 service with different source IP address and destination IP address between user terminals is stored in each satellite;

satellite of source node: firstly, receiving an IPv6 service sent by a user terminal of a sending end through a user port; then, IPv6 payload after removing source MAC address, destination MAC address, type and CRC check value from IPv6 service is encapsulated into transmission frame data domain of extended AOS frame; meanwhile, according to the destination IP address, obtaining a label after matching in a label forwarding table of the current satellite, and filling the obtained label into a label field of a transmission frame insertion field of an extended AOS frame; then transmitting the extended AOS frame code to a satellite of a next hop node of the current satellite through a corresponding baseband port;

satellite of intermediate node: after the extended AOS frame is decoded, firstly, a label is taken out from a label domain of a transmission frame insertion domain of the extended AOS frame, the label is updated after the label forwarding table of the current satellite is matched, and the updated label is filled into the label domain of the transmission frame insertion domain of the extended AOS frame; then transmitting the extended AOS frame code to a satellite of a next hop node of the current satellite through a corresponding baseband port;

satellite of destination node: after decoding the extended AOS frame, firstly removing the label in the label domain of the transmission frame insertion domain of the extended AOS frame; decapsulating the IPv6 payload from the extended AOS frame transmission frame data domain, and re-forming the IPv6 service by taking the IPv6 payload and the MAC address of the current satellite as a source MAC address and taking the MAC address of the user terminal as a receiving end as a destination MAC address, type and CRC check value load; and then the IPv6 service is sent to the user terminal as the receiving end through the user port.

Compared with the prior art, the invention designs an extended CCSDS AOS data link layer protocol (MPLS over CCSDS protocol) based on a standard CCSDS AOS data link layer protocol, and realizes the following steps: (1) The tag field is designed, so that unnecessary data frame disassembly-comparison-re-framing processes are avoided, and the data forwarding efficiency is improved; (2) Designing an MAC address replacement method based on an NDP protocol, removing redundant data, and improving data transmission efficiency; (3) And an independent overhead field is designed to transmit management control information, so that the conflict between user service and management control information is avoided.

Drawings

Fig. 1 is a schematic diagram of an AOS frame structure, (a) a standard AOS frame, (b) an extended AOS frame.

Fig. 2 is a diagram of an expanded CCSDS AOS data link layer protocol and reference model contrast, (a) an open system interconnect reference model, (b) a CCSDS expanded reference model, and (c) a CCSDS expanded protocol stack.

Fig. 3 is an extended AOS frame forwarding diagram.

Fig. 4 is a schematic diagram of a management control information frame structure.

Fig. 5 is a schematic diagram of management control information frame segmentation.

Fig. 6 is a schematic diagram of an AOS exchange device.

Fig. 7 is a diagram of bidirectional transmission procedure of IPv6 traffic.

Fig. 8 is a workflow diagram of an extended CCSDS AOS data link layer protocol.

Fig. 9 is a flow chart of IP address and MAC address resolution, (a) passive address resolution, (b) active address resolution.

Fig. 10 is a diagram of a segmented transmission management control information of a data communication network domain (DCN domain) in a control domain by extending an AOS frame.

Fig. 11 is a timing chart of an AOS frame forwarding process when transmitting IPv6 traffic in the forward direction, (a) is a timing chart in which source node AOS switch #1 removes MAC, type, CRC, encapsulates IPv6 traffic into a transmission frame data field of an AOS frame, and adds a label in a label field, (b) is a timing chart in which intermediate node AOS switch #2 replaces an in-label with an out-label, and (c) is a timing chart in which destination node AOS switch #3 removes a label, decapsulates IPv6 traffic from the AOS frame transmission frame data field, and adds MAC, type, CRC.

Fig. 12 is a timing chart of an AOS frame forwarding process when transmitting IPv6 traffic backward, (a) is a timing chart in which an AOS switching device #3 at a destination node removes MAC, type, CRC, encapsulates IPv6 traffic into a transmission frame data field of an AOS frame, and adds a label in a label field, (b) is a timing chart in which an AOS switching device #2 at an intermediate node replaces an in-label with an out-label, and (c) is a timing chart in which an AOS switching device #1 at a source node removes a label, decapsulates IPv6 traffic from the transmission frame data field of the AOS frame, and adds MAC, type, CRC.

Fig. 13 is a flow chart of IP data forwarding, (a) route-based forwarding, and (b) label-based forwarding.

Fig. 14 is a transmission frame data field schematic diagram of an AOS frame, (a) a standard AOS frame, (b) an extended AOS frame.

Fig. 15 is a schematic diagram of management control information for an AOS frame, (a) a standard AOS frame, (b) an extended AOS frame.

Detailed Description

The invention will be further described in detail below with reference to specific examples and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the invention more apparent.

A satellite data forwarding method based on label switching technology comprises the following steps:

each satellite in the satellite optical network completes the IP and MAC address learning of a user terminal connected with the satellite optical network through a neighbor discovery protocol, wherein the IP and MAC address learning is divided into passive address analysis learning and active address analysis learning;

the process of passive address resolution learning of IP and MAC addresses is specifically: when the satellite receives a neighbor request message sent by the user terminal from the user port, the satellite checks the source IP and the MAC address in the neighbor request message: if the source IP and the MAC address are not in the neighbor cache table, respectively storing the source IP and the MAC address in the neighbor cache table; if the source IP and the MAC address exist in the neighbor cache table, the MAC address of a port directly connected with the satellite and the user terminal is used as the source MAC address in the neighbor advertisement message, and the MAC address of the user terminal is used as the destination MAC address; then the neighbor advertisement message is sent to the user terminal to complete passive address resolution;

the IP and MAC address active address analysis learning process specifically comprises the following steps: the satellite extracts the destination IP address in the IPv6 service, and searches whether the user terminal corresponding to the destination IP address exists in the neighbor cache table: if not, the satellite sends a neighbor request message to the user port to acquire the IP and MAC address of the user terminal, and after acquiring the IP and MAC address of the user terminal, the IPv6 service is sent to the user terminal through the corresponding user port; if yes, the destination node directly sends the IPv6 service to the user terminal through the corresponding user port.

When the routing of the satellite optical network converges, each satellite in the satellite optical network generates a label forwarding table for IPv6 services of different source IP addresses and destination IP addresses between user terminals.

The satellite of the source node receives the IPv6 service sent by the user terminal of the sending end through the user port; then, IPv6 payload after removing source MAC address, destination MAC address, type and CRC check value from IPv6 service is encapsulated into transmission frame data domain of extended AOS frame; meanwhile, according to the destination IP address, obtaining a label after matching in a label forwarding table of the current satellite, and filling the obtained label into a label field of a transmission frame insertion field of an extended AOS frame; and then the extended AOS frame code is sent to the satellite of the next hop node of the current satellite through the corresponding baseband port.

After decoding the extended AOS frame, the satellite of the intermediate node firstly takes out the label from the label domain of the transmission frame insertion domain of the extended AOS frame, updates the label after matching the label forwarding table of the current satellite, and when the updated label of the satellite of the intermediate node is a set termination label, the satellite of the next hop node is the satellite of the target node; otherwise, the satellite of the next hop node is the satellite of the intermediate node, and the updated label is filled into the label field of the transmission frame insertion field of the extended AOS frame; the method comprises the steps of carrying out a first treatment on the surface of the And then the extended AOS frame code is sent to the satellite of the next hop node of the current satellite through the corresponding baseband port.

After the satellite of the destination node decodes the extended AOS frame, firstly, the label in the label domain of the transmission frame insertion domain of the extended AOS frame is removed; decapsulating the IPv6 payload from the extended AOS frame transmission frame data domain, and re-forming the IPv6 service by taking the IPv6 payload and the MAC address of the current satellite as a source MAC address and taking the MAC address of the user terminal as a receiving end as a destination MAC address, type and CRC check value load; and then the IPv6 service is sent to the user terminal as the receiving end through the user port.

The fields of the extended AOS frame are a transmission frame head, a transmission frame insertion field, a transmission frame data field and a transmission frame tail in sequence. Wherein the transport frame insertion field contains an extended control field that further contains a tag field and a data communication network field. The tag field includes a tag field. The data communication network domain comprises a management control information frame, and each field of the management control information frame is sequentially as follows: information frame header, destination node ID, source node ID, information frame acknowledgement, information frame total length, information frame sequence number, information frame output port number, information frame input port number, information frame payload, cyclic Redundancy Check (CRC) and information frame tail.

When 2 satellites are forwarding satellite data, the transmission frame of the extended AOS frame is further required to be inserted into the domain data communication network domain to receive and transmit management control information, namely:

the method comprises the steps of sending a satellite of an extended AOS frame, dividing complete management control information into n pieces of management control information, packaging the n pieces of management control information into n pieces of management control information frames, and respectively filling the n pieces of management control information frames into a data communication network domain of a transmission frame insertion domain of the extended AOS frame;

receiving satellites of extended AOS frames, sequentially receiving n continuous extended AOS frames, and extracting management control information frames from a data communication network domain of a transmission frame insertion domain of the n extended AOS frames; then, the n management control information frames are unpacked to obtain n segmented management control information, and the n segmented management control information is recombined into complete management control information according to the information frame sequence number of the management control information frames; calculating the cyclic redundancy check of the management control information frame from the information frame header to the information frame payload, and comparing the calculated cyclic redundancy check value with the cyclic redundancy check value of the received management control information frame: if the management control information frames are the same, the management control information frames are indicated to be normal without error codes; otherwise, discarding the management control information frame and notifying the satellite retransmission of the extended AOS frame;

wherein n is a set value.

A satellite data forwarding system based on a label switching technology comprises 1 satellite of a source node, at least 1 satellite of an intermediate node and a satellite of a destination node; wherein each satellite stores a tag forwarding table of IPv6 traffic for different source and destination IP addresses between user terminals.

Satellite of source node: firstly, receiving an IPv6 service sent by a user terminal of a sending end through a user port; then, IPv6 payload after removing source MAC address, destination MAC address, type and CRC check value from IPv6 service is encapsulated into transmission frame data domain of extended AOS frame; meanwhile, according to the destination IP address, obtaining a label after matching in a label forwarding table of the current satellite, and filling the obtained label into a label field of a transmission frame insertion field of an extended AOS frame; and then the extended AOS frame code is sent to the satellite of the next hop node of the current satellite through the corresponding baseband port.

Satellite of intermediate node: after the extended AOS frame is decoded, firstly, a label is taken out from a label domain of a transmission frame insertion domain of the extended AOS frame, the label is updated after the label forwarding table of the current satellite is matched, and the updated label is filled into the label domain of the transmission frame insertion domain of the extended AOS frame; and then the extended AOS frame code is sent to the satellite of the next hop node of the current satellite through the corresponding baseband port.

Satellite of destination node: after decoding the extended AOS frame, firstly removing the label in the label domain of the transmission frame insertion domain of the extended AOS frame; decapsulating the IPv6 payload from the extended AOS frame transmission frame data domain, and re-forming the IPv6 service by taking the IPv6 payload and the MAC address of the current satellite as a source MAC address and taking the MAC address of the user terminal as a receiving end as a destination MAC address, type and CRC check value load; and then the IPv6 service is sent to the user terminal as the receiving end through the user port.

The present invention divides a block in the transmission frame insertion domain of a standard AOS frame (see fig. 1 (a)) as an extended control domain (Extended Control Field, ECF) into extended AOS frames (see fig. 1 (b)) to implement label-based AOS frame forwarding and bearer of multiple types of traffic. The extended control domain consists of a Label domain (Label) and a data communication network domain (Data Communication Network, DCN). And the label domain is utilized to realize an AOS frame forwarding mechanism based on label switching on a label switching node (Label Switching Router, LSR) so as to replace an AOS frame forwarding mechanism based on an IP address, thereby avoiding unnecessary data frame disassembly-comparison-re-framing process. In addition, in order to support multiple types of traffic transmission, different types of traffic, such as IP traffic, bit rate traffic, virtual channel access tasks, packet traffic, etc., are placed in the transmission frame data field of the extended AOS frame for transmission.

Based on the extended AOS frame, the extended CCSDS AOS data link layer protocol designed by the present invention adds a label switching sub-layer (Label switching sublayer) between the data link sub-layer and the synchronization and channel coding layer of the standard CCSDS AOS data link protocol. As shown in fig. 2, where (a) is an open system interconnect reference model, (b) is a CCSDS extended reference model, and (c) is a CCSDS extended protocol stack. In the MPLS over CCSDS protocol, the functions implemented based on the label domain and the data communication network domain are as follows: (1) AOS frame forwarding is realized at the label core switching node by using the label domain, as shown in figure 3; (2) The data communication network domain is used for management control information interaction between nodes.

Since the content, the length, etc. of the management control information are not fixed, the management control information cannot be directly transmitted through the data communication network domain. Therefore, the invention designs a fixed-length management control information frame for transmitting the indefinite-length management control information in a segmented way. The management control information frame structure is as shown in fig. 4, and the functions of the fields are as follows:

information frame header, information frame tail: all are fixed values, and respectively represent the beginning and the end of a management control information frame;

destination node ID, source node ID: a variable value representing a start node and a stop node of the management control information frame transmission;

information frame ID: a variable value representing the uniqueness of the management control information frame in the network;

information frame response: the destination node receives the response sent to the source node after the management control information frame, so as to ensure that the management control information can reach the purpose;

total length of information frame, information frame sequence number: after the management control information with the indefinite length is transmitted in a segmented mode, the total number of the segments of the management control information and the sequence number after the segments are expressed and used for the receiving end to reorganize the management control information;

information frame out port number, information frame in port number: since the AOS switch has 8 baseband ports, the AOS switch is used for representing the sending and receiving ports of the management control information;

information frame payload: the indefinite length management control information is put into the field for transmission in a segmented mode;

cyclic redundancy check (crc): and checking (without check bits) from the information frame head to the information frame tail, wherein the check bits are used for judging the legitimacy of the management control information frame by the receiving end.

The steps of receiving and transmitting management control information through the data communication network domain are as follows: (1) At the transmitting end, the AOS switch first divides the management control information with a fixed length into 10 pieces (pieces 1 to 10), as shown in fig. 5, and then transmits the management control information by expanding the data communication network domain of the AOS frame. (2) At a receiving end, the AOS switching device sequentially receives 10 continuous extended AOS frames, extracts management control information from a data communication network domain of the extended AOS frames, and recombines the management control information into complete management control information according to an information frame sequence number; calculating the cyclic redundancy check from the information frame header to the information frame payload, and comparing the calculated cyclic redundancy check value with the cyclic redundancy check value of the received management control information: if the management control information frames are the same, the management control information frames are indicated to be normal without error codes; otherwise, the management control information frame is discarded, and the sending end is informed of retransmission.

The invention designs an AOS switching device on the satellite for verifying the MPLS over CCSDS protocol. The AOS switching device adopts a field programmable gate array (Field Programmable Gate Array, FPGA) chip as a main control chip, and is provided with 4 paths of user ports (gigabit or tera Ethernet) and 8 paths of Low-voltage differential signals (Low-Voltage Differential Signaling, LVDS) baseband ports. The AOS exchange device mainly performs 2 functions: (1) Traffic extended AOS frame adaptation (Service over AOS adaptation); (2) Label-based extended AOS frame exchange (Label-based AOS switching). As shown in fig. 6, the AOS switching device functions as:

the service adaptation (Label delivery) to various types is completed at the source satellite node (source tag edge node). Various services are packaged in a transmission frame data field of an extended AOS frame, and are sent to corresponding service caches according to data types, an extended AOS frame tag field is added, the services are sent to a sender module, parallel extended AOS frame data are subjected to 8b/10b serial coding, and then wireless channel transmission is carried out through a baseband port.

The extended AOS frame forwarding is done at the intermediate satellite node (core Label switching node) based on Label switching. The data needs to be restored to parallel encoding before being sent to the AOS switch module. According to the Label forwarding table, an In Label (In-Label) of an extended AOS frame Label domain (Label) is replaced by an Out Label (Out-Label), parallel-serial code conversion is carried Out, and the extended AOS frame is sent to the next node through a corresponding baseband port.

The labels are removed at the destination satellite node (destination Label edge node) and the data recovered. If the value of the In-label is 0xFFFF, the node is a service destination node, and label switching processing is not needed. The data payloads in the extended AOS frames are decapsulated into corresponding data service caches and then sent to corresponding user ports.

Taking the IPv6 service bidirectional transmission procedure from the user terminal #1 to the user terminal #2 in fig. 7 as an example, the node IDs of the satellite #1 (AOS switching device # 1), the satellite #2 (AOS switching device # 2), and the satellite #3 (AOS switching device # 3) are 0x0001, 0x0002, and 0x0003, respectively. The MPLS over CCSDS protocol workflow is as shown in fig. 8:

(1) IP and MAC address learning of the source node and the destination node.

The AOS switching device designed by the invention has 4 paths of user ports, so that a neighbor discovery protocol (Neighbor Discovery Protocol, NDP) needs to be realized in the AOS switching device to distinguish user terminal addresses of different user port interconnections. Because the user terminals #1, #2 and #3 cannot learn the IP and MAC addresses, the invention adds the neighbor discovery protocol module in the AOS switching device, which is used for solving the learning problem of the IP and the MAC addresses. The specific implementation method of the neighbor discovery protocol module is divided into 2 flows of IP and MAC address passive address resolution and IP and MAC address active address resolution.

1) The IP and MAC address passive address resolution flow is as in fig. 9 (a).

When the AOS switch receives a neighbor solicitation message (Neighbor Solicitation, NS) sent by a user terminal from a user port (gigabit or trillion ethernet) (e.g., 1-5 in fig. 9 (a)), the neighbor discovery protocol module (ndp_rx) of the AOS switch will check the source IP and MAC address in the message (e.g., 6 in fig. 9 (a)). If the source IP and MAC address are not in the neighbor cache table, the source IP and MAC address are stored in the neighbor cache table. If so, the IP and MAC addresses of the user ports (gigabit Ethernet or tera Ethernet) directly connected with the user terminals by the AOS switching device are used as source MAC addresses in neighbor advertisement messages (Neighbor Advertisement, NA), and the MAC addresses of the user terminals are used as destination MAC addresses. Then, the neighbor advertisement message (NA) is sent to the user terminal (as shown in fig. 9 (a) 7 to 11), and the passive address resolution process is completed.

2) IP and MAC addresses proactive address resolution flow as in fig. 9 (b).

When the AOS switching device needs to send IPv6 data, first, the destination IP address in the IPv6 data is extracted, and whether the IP address of the user terminal exists or not is searched in the neighbor cache table (as in 1 in fig. 9 (b): if not, the AOS switching device starts the active address resolution function flow, and sends a neighbor request message (NS) to the user port (gigabit Ethernet or tera Ethernet) through the NDP module to acquire the IP and MAC addresses of the user terminal (as shown in 2-13 in (b) of FIG. 9). After obtaining the IP and MAC addresses of the user terminal, the IPv6 data will be sent to the user terminal through the corresponding user port (gigabit ethernet or teraethernet) (as 4-7 in fig. 9 (b)); if so, the AOS switching device directly transmits the IPv6 data to the user terminal (4-7 in fig. 9 (b)) through the corresponding user port (gigabit Ethernet or tera Ethernet).

(2) The MAC, type, CRC of the source node is removed.

1) The user terminal #1 issues an IPv6 service forwarding instruction (the destination node ID in the management control information frame shown in fig. 4 is filled with 0x0001, the source node ID is filled with 0 xFFFF) to the AOS switching device #1 through the serial port of the AOS switching device, the instruction is that the exit port of IPv6 service allocation with the destination IPv6 address of FE 80:0:30:0:30 is the #3 port of the AOS switching device #1, the allocated ingress Label is 0x00D2, and the Label domain (Label) of the extended AOS frame is filled;

2) The AOS exchange device completes IPv6 and MAC address notification and learning of the user terminal through an NDP protocol. At the service source node AOS switching device #1, the IPv6 payload after fields such as source and destination MAC addresses (12 bytes), type (0 x86 DD), and CRC check value are removed from the IPv6 service (ICMPv 6) received from the user terminal #1 is encapsulated into the extended AOS frame transmission frame data field for transmission.

(3) The intermediate node forwards the extended AOS frame based on label switching.

1) The user terminal #1 transmits a configuration instruction (destination node ID is filled with 0x0002, source node ID is filled with 0xFFFF in the management control information frame as in fig. 4) transmitted to the AOS switch #2 to the AOS switch #1 through the serial port. AOS switch #1 receives the configuration instruction to determine that the destination node ID is 0x0002, and then transmits the configuration instruction to AOS switch #2 in 10 pieces by expanding the data communication network Domain (DCN) of the AOS frame. The AOS switch transmits management control information by expanding DCN fields in AOS frame expansion control fields, as shown in fig. 10;

2) After receiving the configuration instruction of step (1), AOS switch #2 determines that the ID of the destination node is 0x0002, which indicates that the configuration instruction needs to be processed. Then, label 0xFFFF and outlet port 1 are allocated for the extended AOS frame with 0x00D2 in label;

3) AOS switch #2 receives the extended AOS frame of step 2, replaces the in-tag (0 x00D 2) in the extended AOS frame with the out-tag 0xFFFF, fills the out-tag 0xFFFF into the tag field of the extended AOS frame, and sends the extended AOS frame to the traffic transmission path destination node AOS switch according to the out port of step (2).

(4) MAC, type, CRC of the destination node.

AOS switching device #3 completes IPv6 and MAC address advertisement and learning with user terminal #3 through NDP protocol. The AOS switch #3 at the service destination node receives the extended AOS frame of step 3, decapsulates the IPv6 payload from the frame data field transmitted in the extended AOS frame, and reassembles the IPv6 service (ICMPv 6) with the extracted IPv6 payload by using the AOS switch #3 as a source MAC address (6 bytes), the user terminal #3 as a destination MAC address (6 bytes), a Type (0 x86 DD), a recalculated CRC check value, and the like, and sends the same to the user terminal #3.

Steps 1 to 4 complete the IPv6 traffic forward transmission from the user terminal #1 to the user terminal #2 in fig. 7. Otherwise, the backward transmission of the IPv6 service from the user terminal #1 to the user terminal #2 in the figure is completed in the same way.

The bidirectional transmission path established for the IPv6 service of the user terminal #1 to the user terminal #2 is indicated as 1.

TABLE 1

The extended AOS frame forwarding procedure by the AOS switching device #1, the AOS switching device #2, and the AOS switching device #3 based on the label switching at the time of forward transmission of the IPv6 service (ICMPv 6) from the user terminal #1 to the user terminal #3 is as shown in fig. 11 (a) to (c).

The extended AOS frame forwarding procedure by the AOS switching device #1, the AOS switching device #2, and the AOS switching device #3 based on the label switching at the time of backward transmission of the IPv6 service (ICMPv 6) from the user terminal #1 to the user terminal #3 is as shown in fig. 12 (a) to (c).

The main work of the invention is as follows:

(1) And the tag field is designed, so that transmission of multiple types of user services is realized, unnecessary processes of data frame disassembly, comparison and frame re-assembly are avoided, and the data forwarding efficiency is improved.

In the conventional satellite data forwarding method, after the satellite optical network route converges, each satellite node in the network generates a next-hop satellite node IP route forwarding table, as shown in table 2.

TABLE 2

Referring to fig. 13 (a), the forwarding flow of the IP data based on the routing forwarding table is: a) When the IP data of the user terminal #1 reaches the satellite node A, the satellite node A searches a route forwarding table according to the target IP address of the IP data; b) The satellite node A finds a matched route item, encapsulates the IP data into a transmission frame data field of an extended AOS frame, and sends the IP data to the satellite node B through a sending port 1; c) The intermediate node B takes out the destination IP address from the extended AOS frame transmission frame data domain, matches the route item in the forwarding table, obtains the next hop node C and the transmitting port 2, and then transmits the next hop node C to the satellite node C; d) The satellite node C extracts the destination IP address from the extended AOS frame transmission frame data field, and if no matching routing entry is found in the forwarding table, extracts the destination IP data from the extended AOS frame transmission frame data field, and sends the extracted destination IP data to the user terminal #2.

According to the satellite data forwarding method, after the satellite optical network route is converged, each satellite in the satellite optical network generates a label forwarding table for IPv6 services of different source IP addresses and destination IP addresses between user terminals, and IPv6 service transmission between the user terminals is realized based on the label forwarding table, as shown in table 3.

TABLE 3 Table 3

Referring to fig. 13 (b), the forwarding flow of the IP data based on the label forwarding table is: a) When the IP data of the user terminal #1 reaches the satellite node A, the satellite node A performs matching in a Label forwarding table according to the destination IPv6 address, inserts a Label L1 in a Label domain, encapsulates the IP data into a transmission frame data domain of an extended AOS frame, and sends the IP data to the satellite node B through a sending port 1; b) The intermediate node B takes out the Label L1 from the Label domain, matches the Label L1 in the Label forwarding table, replaces the Label L1 (Label switching) with 0xFFFF, and sends the Label to the satellite node C through the sending port 2; c) When the satellite node C finds that the tag is 0xFFFF, the tag (Label mapping) is removed, and IP data is fetched from the extended AOS frame transmission frame data field and sent to the user terminal #2.

(2) And designing an MAC address replacement method based on an NDP protocol, removing redundant data and improving data transmission efficiency.

Based on the forwarding scheme of the IP routing forwarding table, "destination MAC" (6 bytes), "source MAC" (6 bytes), "Type (Type)" (2 bytes), "redundancy check (CRC)" (4 bytes), and "IPv6 payload" are transmitted in the extended AOS frame transmission frame data domain, as shown in fig. 14 (a). In the method for replacing the MAC address based on the NDP, which is designed by the invention, only the IPv6 payload is transmitted in the extended AOS frame transmission frame data domain, as shown in fig. 14 (b), more IP data can be transmitted in the fixed-length transmission frame data domain, and the data transmission efficiency is improved.

(3) And an independent overhead field is designed to transmit management control information, so that the conflict between user service and management control information is avoided.

Based on the forwarding mode of the IP routing forwarding table, the extended AOS frame transmission frame data field is used to transmit user traffic or management control information, as shown in fig. 15 (a). When one of the services is more, transmission congestion of the other service is caused. The invention utilizes the transmission frame insertion domain of CCSDS AOS data link layer protocol standard frame, and defines the expansion control domain therein, and the domain is composed of a label domain and a data communication network domain. The management control information is separately transmitted using the data communication network domain, and the transmission frame data domain transmits only the user traffic, avoiding the collision of the user traffic and the management control information, as shown in fig. 15 (b).

It should be noted that, although the examples described above are illustrative, this is not a limitation of the present invention, and thus the present invention is not limited to the above-described specific embodiments. Other embodiments, which are apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein, are considered to be within the scope of the invention as claimed.

Claims (7)

1. The satellite data forwarding method based on the label switching technology is characterized by comprising the following steps:

when the route of the satellite optical network converges, each satellite in the satellite optical network generates a label forwarding table for IPv6 services of different source IP addresses and destination IP addresses between user terminals;

the satellite of the source node receives the IPv6 service sent by the user terminal of the sending end through the user port; then, IPv6 payload after removing source MAC address, destination MAC address, type and CRC check value from IPv6 service is encapsulated into transmission frame data domain of extended AOS frame; meanwhile, according to the destination IP address, obtaining a label after matching in a label forwarding table of the current satellite, and filling the obtained label into a label field of a transmission frame insertion field of an extended AOS frame; then transmitting the extended AOS frame code to a satellite of a next hop node of the current satellite through a corresponding baseband port;

after decoding the extended AOS frame, the satellite of the intermediate node firstly takes out the label from the label domain of the transmission frame insertion domain of the extended AOS frame, updates the label after matching the label forwarding table of the current satellite, and fills the updated label into the label domain of the transmission frame insertion domain of the extended AOS frame; then transmitting the extended AOS frame code to a satellite of a next hop node of the current satellite through a corresponding baseband port;

after the satellite of the destination node decodes the extended AOS frame, firstly, the label in the label domain of the transmission frame insertion domain of the extended AOS frame is removed; decapsulating the IPv6 payload from the extended AOS frame transmission frame data domain, and re-forming the IPv6 service by taking the IPv6 payload and the MAC address of the current satellite as a source MAC address and taking the MAC address of the user terminal as a receiving end as a destination MAC address, type and CRC check value load; and then the IPv6 service is sent to the user terminal as the receiving end through the user port.

2. The method for forwarding satellite data based on label switching technology according to claim 1, wherein each field of the extended AOS frame is sequentially a transmission frame header, a transmission frame insertion field, a transmission frame data field, and a transmission frame tail; wherein the transport frame insertion field contains an extended control field that further contains a tag field and a data communication network field.

3. The method for forwarding satellite data based on label switching technology according to claim 1 or 2, wherein a management control information frame is encapsulated in a data communication network domain, and each field of the management control information frame is sequentially: information frame header, destination node ID, source node ID, information frame acknowledgement, information frame total length, information frame sequence number, information frame output port number, information frame input port number, information frame payload, cyclic Redundancy Check (CRC) and information frame tail.

4. A satellite data forwarding method implemented based on label switching technology according to claim 3, further comprising the step of inserting a transmission frame of an AOS frame into a domain data communication network domain to transmit and receive management control information, namely:

the method comprises the steps of sending a satellite of an extended AOS frame, dividing complete management control information into n pieces of management control information, packaging the n pieces of management control information into n pieces of management control information frames, and respectively filling the n pieces of management control information frames into a data communication network domain of a transmission frame insertion domain of the extended AOS frame;

receiving satellites of extended AOS frames, sequentially receiving n continuous extended AOS frames, and extracting management control information frames from a data communication network domain of a transmission frame insertion domain of the n extended AOS frames; then, the n management control information frames are unpacked to obtain n segmented management control information, and the n segmented management control information is recombined into complete management control information according to the information frame sequence number of the management control information frames; calculating the cyclic redundancy check of the management control information frame from the information frame header to the information frame payload, and comparing the calculated cyclic redundancy check value with the cyclic redundancy check value of the received management control information frame: if the management control information frames are the same, the management control information frames are indicated to be normal without error codes; otherwise, discarding the management control information frame and notifying the satellite retransmission of the extended AOS frame;

wherein n is a set value.

5. The method for forwarding satellite data based on label switching technology according to claim 1, wherein when the update label of the satellite of the intermediate node is a set termination label, the satellite of the next hop node is the satellite of the destination node; otherwise, the satellite of the next hop node is the satellite of the intermediate node.

6. The method for forwarding satellite data based on label switching technology according to claim 1, further comprising a step of completing IP and MAC address learning of a user terminal connected to each satellite in the satellite optical network through a neighbor discovery protocol, wherein the IP and MAC address learning is divided into passive address resolution learning and active address resolution learning;

the process of passive address resolution learning of IP and MAC addresses is specifically: when the satellite receives a neighbor request message sent by the user terminal from the user port, the satellite checks the source IP and the MAC address in the neighbor request message: if the source IP and the MAC address are not in the neighbor cache table, respectively storing the source IP and the MAC address in the neighbor cache table; if the source IP and the MAC address exist in the neighbor cache table, the MAC address of a port directly connected with the satellite and the user terminal is used as the source MAC address in the neighbor advertisement message, and the MAC address of the user terminal is used as the destination MAC address; then the neighbor advertisement message is sent to the user terminal to complete passive address resolution;

the IP and MAC address active address analysis learning process specifically comprises the following steps: the satellite extracts the destination IP address in the IPv6 service, and searches whether the user terminal corresponding to the destination IP address exists in the neighbor cache table: if not, the satellite sends a neighbor request message to the user port to acquire the IP and MAC address of the user terminal, and after acquiring the IP and MAC address of the user terminal, the IPv6 service is sent to the user terminal through the corresponding user port; if yes, the destination node directly sends the IPv6 service to the user terminal through the corresponding user port.

7. The satellite data forwarding system based on the label switching technology is characterized by comprising 1 satellite of a source node, at least 1 satellite of an intermediate node and a satellite of a destination node; the label forwarding table of IPv6 service with different source IP address and destination IP address between user terminals is stored in each satellite;

satellite of source node: firstly, receiving an IPv6 service sent by a user terminal of a sending end through a user port; then, IPv6 payload after removing source MAC address, destination MAC address, type and CRC check value from IPv6 service is encapsulated into transmission frame data domain of extended AOS frame; meanwhile, according to the destination IP address, obtaining a label after matching in a label forwarding table of the current satellite, and filling the obtained label into a label field of a transmission frame insertion field of an extended AOS frame; then transmitting the extended AOS frame code to a satellite of a next hop node of the current satellite through a corresponding baseband port;

satellite of intermediate node: after the extended AOS frame is decoded, firstly, a label is taken out from a label domain of a transmission frame insertion domain of the extended AOS frame, the label is updated after the label forwarding table of the current satellite is matched, and the updated label is filled into the label domain of the transmission frame insertion domain of the extended AOS frame; then transmitting the extended AOS frame code to a satellite of a next hop node of the current satellite through a corresponding baseband port;

satellite of destination node: after decoding the extended AOS frame, firstly removing the label in the label domain of the transmission frame insertion domain of the extended AOS frame; decapsulating the IPv6 payload from the extended AOS frame transmission frame data domain, and re-forming the IPv6 service by taking the IPv6 payload and the MAC address of the current satellite as a source MAC address and taking the MAC address of the user terminal as a receiving end as a destination MAC address, type and CRC check value load; and then the IPv6 service is sent to the user terminal as the receiving end through the user port.