Network routing link state real-time sensing method based on cross-layer cooperation

Abstract

The invention relates to a network routing link state real-time sensing method based on cross-layer cooperation, and link state detection in a routing protocol not only adopts Hello packet interaction at a network layer, but also adopts frame synchronization indication reported by a physical layer; the inter-satellite link state is realized by actively detecting the inter-satellite laser terminal frame synchronization state, real-time detection of the inter-satellite link on-off state, link quality and the like is completed by combining the functions of inter-satellite link signal capturing and tracking, signal processing, link quality detection and the like, and the detection result is reported to the inter-satellite routing protocol processing function unit. And triggering route updating. According to the method, on one hand, the routing interaction overhead is effectively controlled, on the other hand, when the conditions of inter-satellite link on-off change, satellite node abnormal failure and the like occur, real-time response and rapid rerouting can be performed, and a real-time and accurate link state detection scheme is provided for a wireless network communication system.

Description

Technical Field

[0001] The present application relates to the field of satellite communication technology, and in particular to a real-time perception method for network routing link status based on cross-layer collaboration. Background Art

[0002] Link state-based routing protocols build routing tables by collecting and exchanging link state information in the network, thereby selecting the best path. This type of protocol has higher efficiency and reliability in dealing with large and complex network environments. It mainly includes two types of routing protocols: OSPF (Open Shortest Path First) and IS-IS (Intermediate System to Intermediate System).

[0003] Take OSPF as an example. OSPF is a link state routing protocol based on IGP (Interior Gateway Protocol). Link state routing protocols use the cost to reach the destination as a metric. The router calculates the weight to reach the neighbor based on the interface bandwidth. The higher the bandwidth, the smaller the weight and the better the path state. When the topology changes, the router does not send the routing table, but only sends the LSA (Link State Advertisement) containing the link change information. Then each router updates the LSDB (Link State DataBase) and uses the SPF (Shortest Path First) algorithm to calculate the route.

[0004] Each router running OSPF maintains a link state database LSDB for tracking the status of network links. The database stores various link state advertisements (LSAs) that reflect the status of routers and their links. These states include the status of the router's available interfaces, known reachable routes, and each link. The link state database is actually a map of the complete network topology of the area, which is the basis for the router to establish a routing table. In order for routers within an autonomous system to form a consistent view of the network topology, they must keep the link state database synchronized. OSPF relies on the Hello protocol, Exchange protocol, and Flooding protocol to complete the interaction process of OSPF data packets, and ultimately achieve LSDB synchronization of all routers in the same routing area.

[0005] The entire working process of OSPF consists of three major interactive protocols:

[0006] (1) Hello protocol: used to discover and maintain OSPF neighbor relationships. It is sent periodically through a timer. A Designated Router (DR) and a Backup Designated Router (BDR) are elected on the network. This is how the two routers establish a neighbor relationship. This protocol exchanges Hello packets, one of the five OSPF packets.

[0007] (2) Exchange Protocol: When two routers establish a bidirectional connection through the adjacency protocol, they must synchronize their databases. This synchronization process is accomplished through the exchange protocol. This protocol exchanges the database description packet (DD) among the five OSPF packets, which only contains LSA header information.

[0008] (3) Flooding protocol: In order to reduce unnecessary traffic, the switching protocol only sends some database description packets, and the real link state announcement is sent through the flooding protocol. This protocol exchanges the following three of the five OSPF packets: Link State Update (LSU) containing complete LSAs information, Link State Request (LSR) requesting the entire LSAs information, and Link State Acknowledge (LSA) sent to ensure the correct sending and receiving of LSAs.

[0009] The link state perception method currently used in network routing protocols is mainly applicable to wired networks. This method mainly relies on protocol message interaction to detect link disconnection, topology changes, etc. The default interaction period in the (OSPFv3) protocol (RFC5340) is 10 seconds, the number of confirmations is 3, and the link break detection time is a random value between 20 and 30 seconds. There are widespread problems such as weak real-time link detection, inability to reflect the actual link status, and long rerouting time. In large-scale networks, it is easy to cause large task response delays and high data loss rates. Summary of the invention

[0010] In order to overcome at least one deficiency in the prior art, the present application provides a method for real-time perception of network routing link status based on cross-layer collaboration.

[0011] In a first aspect, a method for real-time perception of network routing link status based on cross-layer collaboration is provided, comprising:

[0012] FPGA receives frame synchronization signals from multiple ports, and performs edge detection on the frame synchronization signals of multiple ports respectively to obtain multi-channel detection signals; the multi-channel detection signals are input into the OR gate in FPGA to obtain a combined signal; the combined signal is input into the monostable counter and maintained for a set time, and then output to the CPU processor as an interrupt signal;

[0013] The FPGA synchronously samples the frame synchronization signals of the multiple ports to obtain the frame synchronization state values ​​of the multiple ports, and maps the frame synchronization state values ​​of the multiple ports to the IO space addresses specified by the CPU processor;

[0014] After receiving the interrupt signal, the CPU processor reads the frame synchronization status value of each port in the specified IO space address through the IO bus as a new link on / off mark; when the routing protocol is initialized, the CPU processor reads the frame synchronization status value of each port in the specified IO space address through the IO bus as a link on / off mark when the routing protocol is initialized;

[0015] Compare the new link up / down flag with the current link up / down flag. If the link up / down flag of a port changes from down to up, set the link up / down flag of the port to up, start the Hello packet sending timer of the port, and establish neighbor relationships by exchanging Hello information with other routers. If the link up / down flag of a port changes from up to down, set the link up / down flag of the port to down, delete all neighbors in the port neighbor list, trigger the update of the routing table, set the DR and BDR of the port to empty, clear the port link state response queue, turn off the link state response timer, Hello packet sending timer, and waiting timer, send a Hello packet without neighbor information to inform other routers that the port is disconnected, so as to notify other routers of network changes and trigger the update of the routing table.

[0016] Update Hello packet information, send Hello packets periodically at each connected port, and each node in the network updates the routing table according to the protocol.

[0017] In one embodiment, deleting all neighbors in the port neighbor list includes:

[0018] Disable the neighbor inactivity timer, DD send timer, and link state request timer, and clear LSAs in the link state retransmission list, database summary list, and link state request list.

[0019] In one embodiment, the setting time is 50 us.

[0020] In one embodiment, the method further comprises:

[0021] When the CPU processor is powered on and initialized, the frame synchronization status value of each port is read in the specified IO space address through the IO bus as the link on / off flag during power-on initialization.

[0022] In a second aspect, a device for real-time perception of network routing link status based on cross-layer collaboration is provided, comprising an FPGA and a CPU processor, and the device is used to implement the above-mentioned method for real-time perception of network routing link status based on cross-layer collaboration.

[0023] Compared with the prior art, the present application has the following beneficial effects: the real-time perception method of network routing link status based on cross-layer collaboration in the present application, the link status detection in the routing protocol not only adopts Hello packet interaction at the network layer, but also adopts frame synchronization indication reported by the physical layer; the intersatellite link status is realized by actively detecting the frame synchronization status of the intersatellite laser terminal, and the intersatellite link signal capture and tracking, signal processing, link quality detection and other functions are combined to complete the real-time detection of the intersatellite link on-off status, link quality, etc., and report the detection results to the intersatellite routing protocol processing functional unit to trigger the routing update. On the one hand, the method of the present application effectively controls the routing interaction overhead, and on the other hand, when the intersatellite link on-off changes, the satellite node abnormal failure and other situations occur, it can respond in real time and perform fast rerouting, providing a real-time and accurate link status detection solution for the wireless network communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present application may be better understood by referring to the following description given in conjunction with the accompanying drawings, which together with the following detailed description are included in this specification and form a part of this specification. In the drawings:

[0025] Figure 1 The schematic diagram of the real-time perception method of network routing link status based on cross-layer collaboration is shown. DETAILED DESCRIPTION

[0026] The exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual embodiments are described in the specification. However, it should be understood that many implementation-specific decisions can be made in the process of developing any such actual embodiments in order to achieve the specific goals of the developer, and these decisions may vary from embodiment to embodiment.

[0027] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure closely related to the scheme according to the present application is shown in the drawings, while other details that are not closely related to the present application are omitted.

[0028] It should be understood that the present application is not limited to the described implementation forms due to the following description with reference to the accompanying drawings. In this article, where feasible, the embodiments can be combined with each other, features between different embodiments can be replaced or borrowed, and one or more features can be omitted in one embodiment.

[0029] The embodiment of the present application provides a method for real-time perception of network routing link status based on cross-layer collaboration. The method is based on FPGA (Field Programmable Gate Array) and CPU processor (Central Processing Unit) for real-time perception of intersatellite network routing link status. A laser terminal is provided on the satellite, and the laser terminal includes a laser module and a routing module. The FPGA and CPU processor are components in the routing module. In the method, the FPGA obtains the frame synchronization signals of multiple ports of the laser module, and further processes the signals, and finally realizes the method for real-time perception of network routing link status.

[0030] Figure 1 The schematic diagram of the real-time perception method of network routing link status based on cross-layer collaboration is shown in FIG. Figure 1 , methods include:

[0031] Step S1, FPGA receives frame synchronization signals from multiple ports, and performs edge detection on the frame synchronization signals of multiple ports respectively to obtain multi-channel detection signals, where edge detection includes detection of rising edge and falling edge, and the number of ports can be 2; the multi-channel detection signals are input into the OR gate in the FPGA to obtain a combined signal; the combined signal is input into a monostable counter and maintained for a set time, and then output as an interrupt signal to the CPU processor;

[0032] Here, the set time can be 50us or other values.

[0033] In this step, among the many signals indicating the link establishment status given by the laser terminal, such as tracking success indication, capture success indication, decoding synchronization indication, frame synchronization indication, and CRC check (Cyclic Redundancy Check), the frame synchronization indication (i.e., frame synchronization signal) is selected as a sign to judge whether the link is on or off. A high level of the frame synchronization indication indicates that the link is connected, and a low level indicates that the link is disconnected.

[0034] Step S2, FPGA synchronously samples the frame synchronization signals of multiple ports to obtain multiple port frame synchronization state values, and maps the multiple port frame synchronization state values ​​to the IO space address specified by the CPU processor, such as 0x00039C.

[0035] Step S3, after receiving the interrupt signal, the CPU processor reads the frame synchronization status value of each port in the specified IO space address through the IO bus as a new link on / off flag; when the routing protocol is initialized, the CPU processor reads the frame synchronization status value of each port in the specified IO space address through the IO bus as a link on / off flag when the routing protocol is initialized.

[0036] Step S4, compare the new link on / off flag with the current link on / off flag. If the link on / off flag of a port changes from off to on, set the link on / off flag of the port to up, start the Hello packet sending timer of the port, and establish a neighbor relationship by exchanging Hello information with other routers; if the link on / off flag of a port changes from on to off, set the link on / off flag of the port to down, delete all neighbors in the port neighbor list; trigger the update of the routing table, set the DR and BDR of the port to empty, clear the port link state response queue, turn off the link state response timer, the Hello packet sending timer and the waiting timer; send a Hello packet without neighbor information to inform other routers that the port is disconnected, so as to notify other routers of network changes and trigger the update of the routing table.

[0037] Specifically, delete all neighbors in the port neighbor list, including:

[0038] Disable the neighbor inactivity timer, DD send timer, and link state request timer, and clear LSAs in the link state retransmission list, database summary list, and link state request list.

[0039] Step S5, updating the Hello packet information, sending Hello packets periodically at each connected port, and each node in the network updates the routing table according to the protocol.

[0040] Furthermore, before executing step S1, when the CPU processor is powered on and initialized, the frame synchronization state value of each port is read from the specified IO space address through the IO bus as a link on / off flag during power-on and initialization.

[0041] In this embodiment, active detection of the inter-satellite link status is achieved through active detection by the inter-satellite laser terminal, and real-time detection of the inter-satellite link on / off status, link quality, etc. is completed by combining inter-satellite link signal capture and tracking, signal processing, link quality detection and other functions, and the detection results are reported to the inter-satellite routing protocol processing functional unit.

[0042] The topology prediction of the inter-satellite links of the entire network. The inter-satellite topological relationship of the low-orbit constellation has the characteristic of regular change. The constellation topology and routing information of different time periods can be pre-stored in the satellite or injected into the satellite by the ground. The inter-satellite routing protocol processing functional unit can predict the topological state of the inter-satellite links of the entire network according to the current system time; on this basis, according to the inter-satellite link status detection results reported in real time by the inter-satellite laser terminal or the inter-satellite microwave terminal, the inter-satellite topology and link status are updated and confirmed.

[0043] Local inter-satellite link periodic detection (within two hops), active detection of inter-satellite link status mainly realizes the status detection of each group of inter-satellite links, and the purpose of local inter-satellite link periodic detection is to periodically exchange neighboring nodes and link status information in the local area, on the one hand, effectively control the routing interaction overhead, on the other hand, when the inter-satellite link on-off conversion, satellite node abnormal failure and other situations occur, it can respond in real time and perform fast rerouting.

[0044] The embodiment of the present application also provides a real-time perception device for network routing link status based on cross-layer collaboration, including an FPGA and a CPU processor, and the device is used to implement the real-time perception method for network routing link status based on cross-layer collaboration in the above embodiment. The specific implementation functions and technical effects of each module can refer to the above embodiment.

[0045] Specifically, the CPU processor can adopt BM3823 CPU.

[0046] The above are only various implementations of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A real-time perception method for network routing link status based on cross-layer collaboration, characterized in that: include: The FPGA receives frame synchronization signals of multiple ports, and performs edge detection on the frame synchronization signals of the multiple ports respectively to obtain multi-channel detection signals; The multiple detection signals are input into the OR gate in the FPGA to obtain a combined signal; the combined signal is input into the monostable counter and maintained for a set time, and then output to the CPU processor as an interrupt signal; The FPGA synchronously samples the frame synchronization signals of the multiple ports to obtain multiple port frame synchronization state values, and maps the multiple port frame synchronization state values ​​to the IO space addresses specified by the CPU processor; After receiving the interrupt signal, the CPU processor reads the frame synchronization state value of each port in the specified IO space address through the IO bus as a new link on / off flag; When the routing protocol is initialized, the CPU processor reads the frame synchronization state value of each port in the specified IO space address through the IO bus as a link on / off flag when the routing protocol is initialized; Compare the new link on / off flag with the current link on / off flag. If the link on / off flag of a port changes from off to on, set the link on / off flag of the port to up, start the Hello packet sending timer of the port, and establish a neighbor relationship by exchanging Hello information with other routers; if the link on / off flag of a port changes from on to off, set the link on / off flag of the port to down, delete all neighbors in the neighbor list of the port; trigger the update of the routing table, set the DR and BDR of the port to empty, clear the link state response queue of the port, turn off the link state response timer, the Hello packet sending timer and the waiting timer; send a Hello packet without neighbor information to inform other routers that the port is disconnected, so as to notify other routers of network changes and trigger the update of the routing table; Update Hello packet information, send Hello packets periodically at each connected port, and each node in the network updates the routing table according to the protocol.

2. The method according to claim 1, characterized in that in, Delete all neighbors in the neighbor list of the port, including: Disable the neighbor inactivity timer, DD send timer, and link state request timer, and clear LSAs in the link state retransmission list, database summary list, and link state request list.

3. The method according to claim 1, characterized in that The setting time is 50us.

4. The method according to claim 1, characterized in that The method further comprises: When the CPU processor is powered on and initialized, the frame synchronization state value of each port is read in the specified IO space address through the IO bus as a link on / off mark during power-on and initialization.

5. A real-time perception device for network routing link status based on cross-layer collaboration, characterized in that: The device comprises an FPGA and a CPU processor, and is used to implement the real-time perception method of network routing link status based on cross-layer collaboration as described in any one of claims 1 to 4.

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