CN110601975A - Label distribution method suitable for multi-satellite and multi-beam satellite communication system - Google Patents

Abstract

The invention discloses a label allocation method suitable for a multi-satellite multi-beam satellite communication system, and proposes different label allocation processes for two different services of circuit service and packet service; Different label assignments. The invention can assign labels to the packets entering the satellite network in the satellite edge switching router LER, and the on-satellite switch can perform two-layer fast forwarding through the processing and identification of the labels, which can provide sufficient flexibility for the system, and the allocation process overhead is small , which enables on-board switches to realize fast packet exchange through simple and efficient processing.

Description

A label assignment method suitable for multi-satellite multi-beam satellite communication system

technical field

The present invention relates to the technical field of satellite communication, in particular to a label allocation method suitable for a multi-satellite multi-beam satellite communication system.

Background technique

In the multi-satellite multi-beam satellite communication system, there are interstellar links between satellites. Each satellite includes multiple beams in the coverage area, and usually adopts the multi-frequency time division multiple access method. The on-board switches face the interstellar link and different beams correspond to different port. When routing and exchanging packets, Layer 3 determines the output port of the packet by looking up the routing table, and sends the packet to the queue corresponding to the output port; while at Layer 2, it needs to determine the carrier used for packet reception and transmission. and time slot resources to achieve fast exchange of messages.

In order to support various types of services and make full use of system resources, multi-satellite and multi-beam satellite communication systems need to provide efficient and low-cost switching methods. It can provide the services required by the business to a certain extent, but the efficiency is limited. Multi-protocol label switching MPLS provides a new idea for satellite communication systems, which can take into account the flexibility of Layer 3 and the efficiency of Layer 2. However, this label-based switching method requires large node and channel overhead in label allocation, and is not suitable for use in satellite communication systems with scarce resources.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a label allocation method suitable for a multi-satellite multi-beam satellite communication system, which fully simplifies the label allocation process in the system, and provides great processing flexibility for different services, not only It saves channel resources, and ensures that the on-board switch can achieve Layer 2 fast forwarding by processing and identifying labels.

In order to solve the above technical problems, the present invention provides a label allocation method suitable for a multi-satellite multi-beam satellite communication system, comprising the following steps:

(1) After the service terminal submits the label application, the on-board control completes the local label allocation, including the allocation of the incoming label and the outgoing label, and writes the two and the corresponding port mapping relationship into the on-board label forwarding table;

(2) In the circuit switching service, after the calling terminal initiates a call application, the satellite network controller judges the validity of the calling terminal and the idle state of the called terminal, and initiates a paging command to the called terminal; if the satellite network controller determines that there is idle time channel resources, then send channel allocation instructions to the calling terminal and the called terminal respectively, and the signaling includes an incoming label and an outgoing label. When the service terminal is regarded as the calling terminal, it is called the calling terminal, and when it is the called terminal, it can be called the called terminal.

Preferably, in step (1), the on-star label forwarding table format is as follows:

ingress port into the label outgoing port out label

.

Preferably, in step (2), in a system using multi-frequency time division multiple access, the incoming label includes an uplink carrier number and a time slot number, and the outgoing label includes a downlink time slot number.

A label allocation method suitable for a multi-satellite multi-beam satellite communication system, comprising the following steps:

(1) After the service terminal submits the label application, the on-board control completes the local label allocation, including the allocation of the incoming label and the outgoing label, and writes the two and the corresponding port mapping relationship into the on-board label forwarding table;

(2) In the packet switching service, the assigned label is uniformly distributed to the service terminal by the connected satellite, and the satellite network control performs IP switching; after the label is assigned, the service terminal adds the label to realize fast label switching on the satellite; When the intermediate node processes the message, it searches the on-board label forwarding table according to the incoming label carried by it, replaces the incoming label of the message with the outgoing label, and sends it to the corresponding outgoing port; when it reaches the satellite connected to the receiving terminal, the label is removed. After that, it is sent into and out of the port and sent to the receiving terminal.

Preferably, in the high-priority packet service, the service terminal actively sends a label application to the on-board network controller, the on-board network controller searches the routing table to complete the establishment of the link, assigns the label and sends it to the application terminal; in the process of establishing the connection Each intermediate node completes local label allocation; link establishment requires negotiation between the source-end service terminal and the destination-end service terminal. When the source-end access satellite receives the label application, it needs the confirmation of the destination terminal. After confirmation, the source-end service terminal is sent to the Assign labels.

Preferably, in the low-priority packet service, the service terminal does not need to issue a label application, but directly sends a data packet. When the onboard network controller receives the packet, it automatically assigns a label and sends it to the service terminal. When the service terminal receives After the label information, the label value is added to the subsequent packets, and the onboard switch performs label switching. When the link fails, the link is congested, or the link is switched due to satellite movement, and rerouting is required, the tagged IP packets can be switched from Layer 2 switching to Layer 3 for forwarding. forwarding on the path, which can greatly reduce the delay jitter.

The beneficial effects of the present invention are as follows: the present invention proposes a label allocation method suitable for a multi-satellite and multi-beam satellite communication system, which simplifies the label allocation process, saves satellite channel bandwidth resources and on-board node processing overhead, and through Differentiated processing of different services provides great flexibility, enabling on-board switches to perform fast Layer 2 forwarding of various services according to labels, without the need for repeated routing at Layer 3, further reducing on-board processing The invention can provide a comprehensive service platform to meet the access and transmission requirements of different types of terminals and services with different characteristics; ensure the flexibility and scalability of the satellite communication system; provide a connection-oriented service mode, such as on-board The high-speed performance, QoS guarantee function, and flow control function of ATM technology; the satellite communication system is conveniently and organically integrated with the ground network, compatible with circuit services and packet services, providing efficient communication services, and truly realizing the satellite-ground integrated network.

Description of drawings

FIG. 1 is a schematic structural diagram of an on-board label forwarding table of the present invention.

FIG. 2 is a schematic diagram of a circuit-switched label assignment flow diagram of the present invention.

FIG. 3 is a schematic diagram of an allocation method of a high-priority packet service label according to the present invention.

FIG. 4 is a schematic diagram of a low-priority packet service label assignment process according to the present invention.

FIG. 5 is a schematic structural diagram of an on-board switching unit of the present invention.

Detailed ways

For the two different services of circuit service and packet service, the present invention proposes different label allocation processes; for packet switching messages of different priorities, different label allocation methods are proposed. Specifically as follows:

After the service terminal submits a label application, the on-board control completes the local label allocation, including the allocation of incoming and outgoing labels, and writes the two and the corresponding port mappings into the on-board label forwarding table. The format of the label forwarding table on the star is shown in Figure 1.

For circuit switching, the label assignment is done by the satellite network controller when the call is applied. After the terminal initiates a call application, the satellite network controller determines the validity of the calling terminal and the idle state of the called terminal, and then initiates paging signaling to the called party. Send channel allocation signaling to the called party respectively, the signaling includes an incoming label and an outgoing label, and the label value can correspond to system resources. For example, in a system using multi-frequency time division multiple access, the incoming label may include an uplink carrier number and a time slot number, and the outgoing label may include a downlink time slot number, as shown in FIG. 2 .

The packet-switched service is uniformly distributed by the satellite to the terminal, that is, the label used by the terminal to send the message is determined by the satellite, and the label used by the satellite to send the message is allocated locally, because the adjacency of the satellites is very clear and single. , the label itself can satisfy the uniqueness. Before the label is allocated, it is still an ordinary IP packet, and the IP exchange is performed on the satellite. After the allocation, the terminal adds the label to realize fast label switching on the satellite. When processing a message, each satellite intermediate node searches the on-board label forwarding table according to the incoming label carried by it, replaces the incoming label of the message with the outgoing label, and sends it to the corresponding outgoing port. When reaching the satellite connected to the receiving terminal, the label is removed and sent to the outgoing port, and then delivered to the receiving terminal.

For high-priority packet services, the terminal sends a label application to the on-board network controller actively, and the on-board network controller searches the routing table to complete the link establishment, assigns the label and sends it to the application terminal. In the process of establishing the connection, each intermediate node completes the local label assignment. The link establishment process here is: the link establishment requires negotiation between the source and the destination, and after receiving the label application, the destination terminal needs to confirm, and then assign the label to the source terminal, as shown in Figure 3.

For low-priority packet services, the terminal does not actively issue a label application. When the onboard network controller receives the packet, it automatically assigns a label and sends it to the terminal. When the terminal receives the label information, it adds the label value, and the onboard switch can Label switching, as shown in Figure 4.

As shown in FIG. 5 , the onboard switching unit receives the information sent by the onboard routing module, establishes a forwarding table for forwarding messages, and receives instructions from the onboard network controller to control the forwarding process.

The onboard switching unit includes a packet switching unit, a circuit switching unit and a label identification module, as well as an input port and an output port. The packet switching unit includes a switching fabric and a shared buffer; the circuit switching unit includes a switching fabric. The on-board switching unit receives the information sent by the on-board routing module, establishes a forwarding table for forwarding messages, and also receives the instructions from the on-board network controller to control the forwarding process.

A hybrid switching method combining circuit switching and packet switching is used to realize adaptive switching based on service characteristics. Real-time services in circuit services and packet services use label-based circuit switching to provide connection-oriented services, and non-real-time services (such as short message services) in packet services use packet switching to provide connectionless services.

Messages are identified and forwarded using labels within the satellite network. The satellite terminal located on the ground adds a label to the header of the message, and the label indicates the service type of the message. After the onboard switching unit receives the message through the input port, the label identification module in it distinguishes different services and data flows according to the label. If the label indicates that the packet is a circuit service or a packet real-time service, the packet is sent to the circuit switching unit, and sent to the corresponding output port through the switching structure; if the label indicates that the packet is a non-real-time service, it is sent to the packet switching unit. Find the corresponding output port through the switch fabric, and put the packet into the shared buffer queue corresponding to the port for queuing, waiting for the scheduling of the output port.

When a data packet enters the satellite network, the satellite edge switch router (Label Edge Router, LER) assigns a label for switching to it, and the core label switch router (Label Switch router, LSR) in the satellite network is based on the label. For forwarding, IP packets carrying the same label are directly exchanged at Layer 2 in the subsequent LSR, without repeated routing at Layer 3, reducing on-board processing overhead. When the link fails, the link is congested, or the link is switched due to satellite movement, and rerouting is required, the tagged IP packets can be switched from Layer 2 switching to Layer 3 for forwarding. forwarding on the path, which can greatly reduce the delay jitter.

Claims (6)

1. A label distribution method suitable for a multi-satellite and multi-beam satellite communication system is characterized by comprising the following steps:

(1) after the service terminal proposes a label application, local label distribution is finished by the on-board network control, wherein the local label distribution comprises distributing an incoming label and an outgoing label, and writing the incoming label and the outgoing label and a corresponding port mapping relation into an on-board label forwarding table;

(2) in the circuit switching service, after a calling terminal initiates a call application, the satellite network controls and judges the legality of the calling terminal and the idle state of a called terminal, and initiates a paging instruction to the called terminal; and if the on-satellite network control judges that idle channel resources exist, respectively sending a channel allocation instruction to the calling terminal and the called terminal, wherein the signaling comprises an incoming label and an outgoing label.

2. The label distribution method for multi-satellite multi-beam satellite communication system according to claim 1, wherein in step (1), the format of the on-satellite label forwarding table is as follows:

input port Go into label Output port Go out label

。

3. The method according to claim 1, wherein in step (2), in the system using multifrequency time division multiple access, the incoming label comprises an uplink carrier number and a timeslot number, and the outgoing label comprises a downlink timeslot number.

4. A label distribution method suitable for a multi-satellite and multi-beam satellite communication system is characterized by comprising the following steps:

(1) after the service terminal proposes a label application, local label distribution is finished by the on-board network control, wherein the local label distribution comprises distributing an incoming label and an outgoing label, and writing the incoming label and the outgoing label and a corresponding port mapping relation into an on-board label forwarding table;

(2) in the packet switching service, an accessed satellite uniformly issues a distributed label to a service terminal, and the satellite network controls IP switching; after the labels are distributed, the labels are added by the service terminal, and the fast label switching is realized on the satellite; when each satellite intermediate node processes the message, searching a satellite tag forwarding table according to an incoming tag carried by the satellite intermediate node, replacing the incoming tag of the message with an outgoing tag, and sending the outgoing tag to a corresponding outgoing port; when the satellite reaches the satellite accessed by the receiving terminal, the tag is removed and then sent to the output port, and the satellite is sent to the receiving terminal.

5. The label distribution method suitable for multi-satellite multi-beam satellite communication system of claim 4, wherein in the high priority packet service, the service terminal actively sends a label application to the satellite-borne network control, the satellite-borne network control searches the routing table to complete the establishment of the link, distributes the label and sends the label to the application terminal; in the process of establishing connection, each intermediate node completes local label distribution; the link establishment needs negotiation between a source end service terminal and a destination end service terminal, the source end access satellite needs confirmation of the destination terminal after receiving the label application, and the source end service terminal is allocated with a label after the confirmation.

6. The label distribution method suitable for multi-satellite and multi-beam satellite communication system according to claim 4, wherein in the low priority packet service, the service terminal directly sends the data packet, the satellite-borne network automatically distributes the label and issues the label to the service terminal when receiving the packet, and the satellite-borne switch performs label switching after the service terminal receives the label information and adds the label value to the subsequent packet.